constants.env.dev
The programming constants reference. Find the value, type, and usage for any constant across languages.
JavaScript / TypeScript41
The size in bytes of each element in a BigInt64Array, which is 8. BigInt64Array stores 64-bit signed integers using BigInt values, with a range from -2^63 to 2^63 - 1.
- Language
- JavaScript
- Value
- 8
- Type
- number
The size in bytes of each element in a Float32Array, which is 4. Float32Array stores 32-bit IEEE 754 floating-point numbers, providing about 7 decimal digits of precision.
- Language
- JavaScript
- Value
- 4
- Type
- number
The size in bytes of each element in a Float64Array, which is 8. Float64Array stores 64-bit IEEE 754 floating-point numbers (doubles), providing about 15-17 decimal digits of precision.
- Language
- JavaScript
- Value
- 8
- Type
- number
A global property that provides a standard way to access the global this value across environments. In browsers it equals window, in Node.js it equals global, and in workers it equals self.
- Language
- JavaScript
- Value
- [global object]
- Type
- object
A global property representing positive infinity. It is greater than any finite number. Used as an initial value in minimum-finding algorithms and as a result of division by zero for positive numbers.
- Language
- JavaScript
- Value
- Infinity
- Type
- number
The size in bytes of each element in an Int16Array, which is 2. Int16Array stores 16-bit signed integers with values ranging from -32768 to 32767.
- Language
- JavaScript
- Value
- 2
- Type
- number
The size in bytes of each element in an Int32Array, which is 4. Int32Array stores 32-bit signed integers with values ranging from -2147483648 to 2147483647.
- Language
- JavaScript
- Value
- 4
- Type
- number
The size in bytes of each element in an Int8Array, which is 1. Int8Array stores 8-bit signed integers with values ranging from -128 to 127.
- Language
- JavaScript
- Value
- 1
- Type
- number
Euler's number, the base of natural logarithms, approximately 2.71828. It appears naturally in compound interest calculations, probability, and as the base of the exponential function.
- Language
- JavaScript
- Module
- Math
- Value
- 2.718281828459045
- Type
- number
The natural logarithm of 10, approximately 2.302. Used for converting between natural logarithms and common (base-10) logarithms in scientific and engineering computations.
- Language
- JavaScript
- Module
- Math
- Value
- 2.302585092994046
- Type
- number
The natural logarithm of 2, approximately 0.693. This constant is useful in information theory and binary calculations where conversion between natural and base-2 logarithms is needed.
- Language
- JavaScript
- Module
- Math
- Value
- 0.6931471805599453
- Type
- number
The base-10 logarithm of Euler's number (e), approximately 0.434. Equal to 1/Math.LN10, this constant facilitates conversion from natural logarithms to common logarithms.
- Language
- JavaScript
- Module
- Math
- Value
- 0.4342944819032518
- Type
- number
The base-2 logarithm of Euler's number (e), approximately 1.442. Equal to 1/Math.LN2, this constant is used for converting natural logarithms to base-2 logarithms.
- Language
- JavaScript
- Module
- Math
- Value
- 1.4426950408889634
- Type
- number
The ratio of a circle's circumference to its diameter, approximately 3.14159. One of the most fundamental mathematical constants, used extensively in trigonometry, geometry, and physics calculations.
- Language
- JavaScript
- Module
- Math
- Value
- 3.141592653589793
- Type
- number
The square root of 1/2, approximately 0.707. Equivalent to 1/Math.SQRT2, this value appears frequently in signal processing, normalization, and rotation calculations.
- Language
- JavaScript
- Module
- Math
- Value
- 0.7071067811865476
- Type
- number
The square root of 2, approximately 1.414. Also known as Pythagoras' constant, it appears in geometry (diagonal of a unit square), trigonometry, and signal processing.
- Language
- JavaScript
- Module
- Math
- Value
- 1.4142135623730951
- Type
- number
A global property representing Not-a-Number. It is the result of invalid arithmetic operations like 0/0 or Math.sqrt(-1). NaN is unique in that it is not equal to any value including itself.
- Language
- JavaScript
- Value
- NaN
- Type
- number
The difference between 1 and the smallest floating-point number greater than 1, approximately 2.220446049250313 × 10^-16. Useful for comparing floating-point numbers with a tolerance.
- Language
- JavaScript
- Value
- 2.220446049250313e-16
- Type
- number
The maximum safe integer in JavaScript, equal to 2^53 - 1. Values beyond this cannot be represented exactly as IEEE-754 doubles and may lose precision in arithmetic operations.
- Language
- JavaScript
- Value
- 9007199254740991
- Type
- number
The largest positive finite number representable in JavaScript, approximately 1.7976931348623157 × 10^308. Values larger than this are represented as Infinity.
- Language
- JavaScript
- Value
- 1.7976931348623157e+308
- Type
- number
The minimum safe integer in JavaScript, equal to -(2^53 - 1). This is the most negative integer that can be represented exactly as an IEEE-754 double-precision number.
- Language
- JavaScript
- Value
- -9007199254740991
- Type
- number
The smallest positive number representable in JavaScript, approximately 5 × 10^-324. This is the closest positive number to zero, not the most negative number.
- Language
- JavaScript
- Value
- 5e-324
- Type
- number
Represents negative infinity. Returned when a calculation produces a value less than the negative of Number.MAX_VALUE. Behaves mathematically as expected: any positive number multiplied by NEGATIVE_INFINITY is NEGATIVE_INFINITY.
- Language
- JavaScript
- Value
- -Infinity
- Type
- number
Represents positive infinity. Returned when a calculation produces a value greater than Number.MAX_VALUE, or when explicitly referencing Infinity. Equivalent to the global Infinity value.
- Language
- JavaScript
- Value
- Infinity
- Type
- number
A static property that returns the last matched substring. Accessed as RegExp['$&'], it is updated after every successful RegExp match. This is a legacy feature and not recommended for use in new code.
- Language
- JavaScript
- Value
- ''
- Type
- string
A well-known symbol that specifies the default async iterator for an object. Used by for-await-of loops to obtain an async iterator from an async iterable.
- Language
- JavaScript
- Value
- Symbol(Symbol.asyncIterator)
- Type
- symbol
A well-known symbol used to determine if a constructor object recognizes an object as its instance. Customizes the behavior of the instanceof operator.
- Language
- JavaScript
- Value
- Symbol(Symbol.hasInstance)
- Type
- symbol
A well-known symbol that specifies the default iterator for an object. Used by for...of loops and the spread operator to obtain an iterator from an iterable object.
- Language
- JavaScript
- Value
- Symbol(Symbol.iterator)
- Type
- symbol
A well-known symbol that specifies the matching of a regular expression against a string. Used by String.prototype.match() and also determines if an object can be used as a regex.
- Language
- JavaScript
- Value
- Symbol(Symbol.match)
- Type
- symbol
A well-known symbol that specifies the method called by String.prototype.replace() to replace matched substrings. Allows custom objects to define their replacement behavior.
- Language
- JavaScript
- Value
- Symbol(Symbol.replace)
- Type
- symbol
A well-known symbol that specifies the method called by String.prototype.search() to return the index within a string that matches a pattern.
- Language
- JavaScript
- Value
- Symbol(Symbol.search)
- Type
- symbol
A well-known symbol that specifies the constructor function used to create derived objects. Used by built-in methods like Array.prototype.map() to determine the constructor for the return value.
- Language
- JavaScript
- Value
- Symbol(Symbol.species)
- Type
- symbol
A well-known symbol that specifies the method called by String.prototype.split() to split a string at the indices that match a pattern.
- Language
- JavaScript
- Value
- Symbol(Symbol.split)
- Type
- symbol
A well-known symbol that specifies a method to convert an object to a primitive value. Called by type coercion algorithms with a hint of 'number', 'string', or 'default'.
- Language
- JavaScript
- Value
- Symbol(Symbol.toPrimitive)
- Type
- symbol
A well-known symbol used to create the default string description of an object. Accessed internally by Object.prototype.toString() to produce results like '[object Map]'.
- Language
- JavaScript
- Value
- Symbol(Symbol.toStringTag)
- Type
- symbol
The size in bytes of each element in a Uint16Array, which is 2. Uint16Array stores 16-bit unsigned integers with values ranging from 0 to 65535.
- Language
- JavaScript
- Value
- 2
- Type
- number
The size in bytes of each element in a Uint32Array, which is 4. Uint32Array stores 32-bit unsigned integers with values ranging from 0 to 4294967295.
- Language
- JavaScript
- Value
- 4
- Type
- number
The size in bytes of each element in a Uint8Array, which is 1. Uint8Array stores 8-bit unsigned integers with values ranging from 0 to 255, commonly used for binary data and buffers.
- Language
- JavaScript
- Value
- 1
- Type
- number
Python32
A boolean constant that is True if Python was not started with an -O (optimize) flag. When False, assert statements and code inside 'if __debug__:' blocks are stripped at compile time.
- Language
- Python
- Value
- True
- Type
- bool
A special singleton value, also accessible as the literal '...'. Used in type hints for variable-length tuples (Tuple[int, ...]), NumPy array slicing, and as a placeholder in stub files.
- Language
- Python
- Value
- Ellipsis (...)
- Type
- ellipsis
The boolean false value in Python, an instance of int with value 0. False is a keyword and a singleton; there is only one False object. In numeric contexts, False behaves as 0.
- Language
- Python
- Value
- False
- Type
- bool
Creates a negative infinity float value. Any finite number is greater than negative infinity. Commonly used as an initial value for finding maximum values in algorithms.
- Language
- Python
- Value
- -inf
- Type
- float
Creates a positive infinity float value. Equivalent to math.inf. Any finite number is less than positive infinity. Commonly used as an initial value in optimization algorithms.
- Language
- Python
- Value
- inf
- Type
- float
Creates a Not-a-Number float value. Equivalent to math.nan. NaN is not equal to any value including itself; use math.isnan() to test. Propagates through arithmetic operations.
- Language
- Python
- Value
- nan
- Type
- float
Euler's number, the base of natural logarithms, approximately 2.71828. It is one of the most important constants in mathematics, appearing in exponential growth and calculus.
- Language
- Python
- Module
- math
- Value
- 2.718281828459045
- Type
- float
A floating-point positive infinity. Equivalent to float('inf'). Useful as an initial value for finding minimums or as a sentinel value representing unbounded quantities.
- Language
- Python
- Module
- math
- Value
- inf
- Type
- float
A floating-point Not-a-Number value. Equivalent to float('nan'). NaN is not equal to any value including itself; use math.isnan() to test for it.
- Language
- Python
- Module
- math
- Value
- nan
- Type
- float
The mathematical constant pi, the ratio of a circle's circumference to its diameter, approximately 3.14159. Available as a float with full double-precision accuracy.
- Language
- Python
- Module
- math
- Value
- 3.141592653589793
- Type
- float
The mathematical constant tau, equal to 2*pi (approximately 6.28318). Tau represents one full turn in radians, making it more natural for expressing angles in many formulas.
- Language
- Python
- Module
- math
- Value
- 6.283185307179586
- Type
- float
The sole value of the NoneType, used to represent the absence of a value. None is a keyword and a singleton. Functions that do not explicitly return a value return None.
- Language
- Python
- Value
- None
- Type
- NoneType
A special singleton value that should be returned by binary special methods (e.g. __eq__, __lt__) to indicate that the operation is not supported for the given type pair. Not the same as NotImplementedError.
- Language
- Python
- Value
- NotImplemented
- Type
- NotImplementedType
The constant string used by the OS to refer to the current directory. This is '.' on both POSIX and Windows systems.
- Language
- Python
- Module
- os
- Value
- .
- Type
- str
The file path of the null device. This is '/dev/null' on POSIX and 'nul' on Windows. Writing to this file discards all data; reading from it returns EOF immediately.
- Language
- Python
- Module
- os
- Value
- /dev/null or nul
- Type
- str
The string used to separate lines on the current platform. This is '\n' on POSIX and '\r\n' on Windows. When writing text files, use the newline parameter of open() rather than this constant.
- Language
- Python
- Module
- os
- Value
- \n or \r\n
- Type
- str
The constant string used by the OS to refer to the parent directory. This is '..' on both POSIX and Windows systems.
- Language
- Python
- Module
- os
- Value
- ..
- Type
- str
The character conventionally used to separate search path components, such as in PATH. This is ':' on POSIX and ';' on Windows.
- Language
- Python
- Module
- os
- Value
- : or ;
- Type
- str
The character used by the operating system to separate pathname components. This is '/' on POSIX systems and '\\' on Windows. Use os.path.join() instead of hardcoding separators.
- Language
- Python
- Module
- os
- Value
- / or \\
- Type
- str
A string containing all ASCII letters, both lowercase and uppercase. Equal to ascii_lowercase + ascii_uppercase: 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'.
- Language
- Python
- Module
- string
- Value
- abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ
- Type
- str
A string containing all lowercase ASCII letters: 'abcdefghijklmnopqrstuvwxyz'. This value is not locale-dependent and does not change.
- Language
- Python
- Module
- string
- Value
- abcdefghijklmnopqrstuvwxyz
- Type
- str
A string containing all uppercase ASCII letters: 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'. This value is not locale-dependent and does not change.
- Language
- Python
- Module
- string
- Value
- ABCDEFGHIJKLMNOPQRSTUVWXYZ
- Type
- str
A string containing all decimal digit characters: '0123456789'. Useful for validation and string operations involving numeric characters.
- Language
- Python
- Module
- string
- Value
- 0123456789
- Type
- str
A string containing all hexadecimal digit characters: '0123456789abcdefABCDEF'. Includes both lowercase and uppercase variants of the hex letters a-f.
- Language
- Python
- Module
- string
- Value
- 0123456789abcdefABCDEF
- Type
- str
A string containing all octal digit characters: '01234567'. Used for validation and operations involving octal number representations.
- Language
- Python
- Module
- string
- Value
- 01234567
- Type
- str
A string containing all ASCII punctuation characters: !"#$%&'()*+,-./:;<=>?@[\]^_`{|}~. Useful for stripping or identifying punctuation in text processing.
- Language
- Python
- Module
- string
- Value
- !"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~
- Type
- str
A string containing all ASCII whitespace characters: space, tab, newline, carriage return, vertical tab, and form feed. Used in string splitting and stripping operations.
- Language
- Python
- Module
- string
- Value
- \t\n\r\x0b\x0c
- Type
- str
The smallest float such that 1.0 + epsilon != 1.0, approximately 2.220446049250313 × 10^-16. Represents the machine epsilon for double-precision floating-point arithmetic.
- Language
- Python
- Module
- sys
- Value
- 2.220446049250313e-16
- Type
- float
The maximum representable positive finite float, approximately 1.7976931348623157 × 10^308. This is the largest value a Python float can hold before becoming infinity.
- Language
- Python
- Module
- sys
- Value
- 1.7976931348623157e+308
- Type
- float
The minimum positive normalized float, approximately 2.2250738585072014 × 10^-308. Values smaller than this are denormalized and may lose precision.
- Language
- Python
- Module
- sys
- Value
- 2.2250738585072014e-308
- Type
- float
The largest positive integer supported by the platform's Py_ssize_t type. Typically 2^31 - 1 on 32-bit platforms and 2^63 - 1 on 64-bit platforms. Used as a practical upper bound for container sizes.
- Language
- Python
- Module
- sys
- Value
- 9223372036854775807
- Type
- int
The boolean true value in Python, an instance of int with value 1. True is a keyword and a singleton; there is only one True object. In numeric contexts, True behaves as 1.
- Language
- Python
- Value
- True
- Type
- bool
Go25
Seek relative to the current offset in the file. Passed as the whence parameter to Seek methods. Equal to 1.
- Language
- Go
- Module
- io
- Value
- 1
- Type
- int
Seek relative to the end of the file. Passed as the whence parameter to Seek methods. Equal to 2. Using a negative offset with SeekEnd moves backward from the file's end.
- Language
- Go
- Module
- io
- Value
- 2
- Type
- int
Seek relative to the origin (beginning) of the file. Passed as the whence parameter to Seek methods. Equal to 0.
- Language
- Go
- Module
- io
- Value
- 0
- Type
- int
The natural logarithm of 10, approximately 2.30259. Used for converting between natural logarithms and common (base-10) logarithms.
- Language
- Go
- Module
- math
- Value
- 2.302585092994046
- Type
- float64
The natural logarithm of 2, approximately 0.69315. Used in information theory and conversions between natural and binary logarithms.
- Language
- Go
- Module
- math
- Value
- 0.6931471805599453
- Type
- float64
The base-10 logarithm of Euler's number (e), approximately 0.43429. Equal to 1/Ln10, used for converting natural logarithms to common logarithms.
- Language
- Go
- Module
- math
- Value
- 0.4342944819032518
- Type
- float64
The base-2 logarithm of Euler's number (e), approximately 1.44269. Equal to 1/Ln2, used for converting natural logarithms to base-2.
- Language
- Go
- Module
- math
- Value
- 1.4426950408889634
- Type
- float64
The largest finite value representable by a float32, approximately 3.4028 × 10^38. Values beyond this overflow to positive or negative infinity in float32 arithmetic.
- Language
- Go
- Module
- math
- Value
- 3.4028234663852886e+38
- Type
- float32
The largest finite value representable by a float64, approximately 1.7977 × 10^308. Values beyond this overflow to positive or negative infinity.
- Language
- Go
- Module
- math
- Value
- 1.7976931348623157e+308
- Type
- float64
The maximum value of an int, which is platform-dependent. On 64-bit systems this is 2^63 - 1 (9223372036854775807). Useful for initializing minimum-finding algorithms.
- Language
- Go
- Module
- math
- Value
- 9223372036854775807
- Type
- int
The maximum value of an int64: 2^63 - 1. This is 9223372036854775807. Commonly used as a boundary check for 64-bit signed integer arithmetic.
- Language
- Go
- Module
- math
- Value
- 9223372036854775807
- Type
- int64
The maximum value of a uint, which is platform-dependent. On 64-bit systems this is 2^64 - 1 (18446744073709551615). The uint type cannot hold negative values.
- Language
- Go
- Module
- math
- Value
- 18446744073709551615
- Type
- uint
The minimum value of an int, which is platform-dependent. On 64-bit systems this is -2^63 (-9223372036854775808). Useful for initializing maximum-finding algorithms.
- Language
- Go
- Module
- math
- Value
- -9223372036854775808
- Type
- int
The minimum value of an int64: -2^63. This is -9223372036854775808. Used for boundary validation and overflow detection in 64-bit signed integer operations.
- Language
- Go
- Module
- math
- Value
- -9223372036854775808
- Type
- int64
The smallest positive non-zero value representable by a float32, approximately 1.401 × 10^-45. This is a denormalized (subnormal) floating-point value.
- Language
- Go
- Module
- math
- Value
- 1.401298464324817e-45
- Type
- float32
The smallest positive non-zero value representable by a float64, approximately 5 × 10^-324. This is a denormalized (subnormal) floating-point value.
- Language
- Go
- Module
- math
- Value
- 5e-324
- Type
- float64
The square root of 2, approximately 1.41421. Also known as Pythagoras' constant, it is the length of the diagonal of a unit square.
- Language
- Go
- Module
- math
- Value
- 1.4142135623730951
- Type
- float64
The square root of Euler's number (e), approximately 1.64872. Equal to e^(1/2), used in probability theory and statistics.
- Language
- Go
- Module
- math
- Value
- 1.6487212707001282
- Type
- float64
The square root of the golden ratio (phi), approximately 1.27202. Used in mathematical analysis and geometry related to the golden ratio.
- Language
- Go
- Module
- math
- Value
- 1.2720196495140689
- Type
- float64
The square root of pi, approximately 1.77245. Appears in the Gaussian integral and various probability distribution formulas.
- Language
- Go
- Module
- math
- Value
- 1.7724538509055159
- Type
- float64
The OS-specific path list separator character. This is ':' on Unix/macOS and ';' on Windows. Used to split environment variables like PATH into individual directories.
- Language
- Go
- Module
- os
- Value
- : or ;
- Type
- rune
The OS-specific path separator character. This is '/' on Unix/macOS and '\\' on Windows. Used when constructing file paths manually instead of using filepath.Join().
- Language
- Go
- Module
- os
- Value
- / or \\
- Type
- rune
Rust22
The highest valid Unicode code point, U+10FFFF (1114111 in decimal). Rust's char type represents a Unicode scalar value and can hold any value from U+0000 to U+10FFFF excluding surrogates.
- Language
- Rust
- Module
- std::char
- Value
- \u{10FFFF}
- Type
- char
Euler's number, the base of natural logarithms, approximately 2.71828. It is one of the most fundamental constants in mathematics, central to calculus and exponential functions.
- Language
- Rust
- Module
- std::f64::consts
- Value
- 2.718281828459045
- Type
- f64
Pi divided by 2 (pi/2), approximately 1.5708. Represents a quarter turn or 90 degrees in radians. Commonly used in trigonometric calculations.
- Language
- Rust
- Module
- std::f64::consts
- Value
- 1.5707963267948966
- Type
- f64
Pi divided by 4 (pi/4), approximately 0.7854. Represents 45 degrees in radians. The tangent of this angle is exactly 1.
- Language
- Rust
- Module
- std::f64::consts
- Value
- 0.7853981633974483
- Type
- f64
The natural logarithm of 10, approximately 2.30259. Used for converting between natural logarithms and common (base-10) logarithms.
- Language
- Rust
- Module
- std::f64::consts
- Value
- 2.302585092994046
- Type
- f64
The natural logarithm of 2, approximately 0.69315. Used in information theory, binary calculations, and conversions between natural and base-2 logarithms.
- Language
- Rust
- Module
- std::f64::consts
- Value
- 0.6931471805599453
- Type
- f64
The base-10 logarithm of Euler's number (e), approximately 0.43429. Equal to 1/LN_10, used for converting natural logarithms to common logarithms.
- Language
- Rust
- Module
- std::f64::consts
- Value
- 0.4342944819032518
- Type
- f64
The base-2 logarithm of Euler's number (e), approximately 1.44269. Equal to 1/LN_2, used for converting natural logarithms to base-2 logarithms.
- Language
- Rust
- Module
- std::f64::consts
- Value
- 1.4426950408889634
- Type
- f64
The ratio of a circle's circumference to its diameter (pi). Provided as an f64 constant with full double-precision accuracy, approximately 3.14159265358979.
- Language
- Rust
- Module
- std::f64::consts
- Value
- 3.141592653589793
- Type
- f64
The square root of 2, approximately 1.41421. Also known as Pythagoras' constant, it is the diagonal length of a unit square and appears in geometry and linear algebra.
- Language
- Rust
- Module
- std::f64::consts
- Value
- 1.4142135623730951
- Type
- f64
The full circle constant (tau), equal to 2*pi, approximately 6.28318. Tau represents one complete revolution in radians and simplifies many trigonometric formulas.
- Language
- Rust
- Module
- std::f64::consts
- Value
- 6.283185307179586
- Type
- f64
The machine epsilon for f64, approximately 2.2204 × 10^-16. This is the difference between 1.0 and the next larger representable number, useful for floating-point comparison tolerances.
- Language
- Rust
- Module
- std::f64
- Value
- 2.220446049250313e-16
- Type
- f64
Positive infinity for f64. Results from operations like 1.0/0.0 or values exceeding f64::MAX. Greater than all finite f64 values.
- Language
- Rust
- Module
- std::f64
- Value
- inf
- Type
- f64
The largest finite f64 value, approximately 1.7977 × 10^308. This is the maximum value before overflow to infinity in 64-bit IEEE 754 floating-point representation.
- Language
- Rust
- Module
- std::f64
- Value
- 1.7976931348623157e+308
- Type
- f64
The smallest finite f64 value (most negative), approximately -1.7977 × 10^308. This is the negative of f64::MAX, not the smallest positive value.
- Language
- Rust
- Module
- std::f64
- Value
- -1.7976931348623157e+308
- Type
- f64
Not-a-Number for f64. Results from undefined operations like 0.0/0.0. NaN is not equal to any value including itself; use f64::is_nan() to test.
- Language
- Rust
- Module
- std::f64
- Value
- NaN
- Type
- f64
Negative infinity for f64. Results from operations like -1.0/0.0. Less than all finite f64 values and less than positive infinity.
- Language
- Rust
- Module
- std::f64
- Value
- -inf
- Type
- f64
The maximum value of a 32-bit signed integer: 2^31 - 1. Equal to 2147483647. Used for boundary checking in 32-bit integer arithmetic.
- Language
- Rust
- Module
- std::i32
- Value
- 2147483647
- Type
- i32
The minimum value of a 32-bit signed integer: -2^31. Equal to -2147483648. Used for boundary checking and overflow detection in 32-bit integer arithmetic.
- Language
- Rust
- Module
- std::i32
- Value
- -2147483648
- Type
- i32
The maximum value of an unsigned 8-bit integer: 255 (2^8 - 1). Commonly encountered when working with bytes, RGB color values, and binary data.
- Language
- Rust
- Module
- std::u8
- Value
- 255
- Type
- u8
The maximum value of a usize, which is platform-dependent. On 64-bit platforms this is 2^64 - 1 (18446744073709551615). Used for array indexing and memory size limits.
- Language
- Rust
- Module
- std::usize
- Value
- 18446744073709551615
- Type
- usize
The minimum value of a usize, always 0. Since usize is an unsigned type, it cannot represent negative values. The minimum is always zero regardless of platform.
- Language
- Rust
- Module
- std::usize
- Value
- 0
- Type
- usize
Java27
The Boolean object corresponding to the primitive value false. Using Boolean.FALSE avoids autoboxing overhead when a Boolean object is needed instead of the primitive boolean.
- Language
- Java
- Module
- java.lang
- Value
- false
- Type
- Boolean
The Boolean object corresponding to the primitive value true. Using Boolean.TRUE avoids autoboxing overhead when a Boolean object is needed instead of the primitive boolean.
- Language
- Java
- Module
- java.lang
- Value
- true
- Type
- Boolean
The maximum value of a byte: 127 (2^7 - 1). Java's byte is a signed 8-bit type, unlike unsigned bytes in many other languages.
- Language
- Java
- Module
- java.lang
- Value
- 127
- Type
- byte
The minimum value of a byte: -128 (-2^7). Java's byte is a signed 8-bit type, so it ranges from -128 to 127.
- Language
- Java
- Module
- java.lang
- Value
- -128
- Type
- byte
The maximum value of a char: '\uffff' (65535). Java's char is a 16-bit unsigned type representing a UTF-16 code unit. Supplementary characters require surrogate pairs.
- Language
- Java
- Module
- java.lang
- Value
- \uffff (65535)
- Type
- char
The minimum value of a char: '\u0000' (0). This is the null character (NUL). Java's char type is unsigned and cannot hold negative values.
- Language
- Java
- Module
- java.lang
- Value
- \u0000 (0)
- Type
- char
An immutable empty List instance. Prefer Collections.emptyList() which provides type-safe generics. Returned list throws UnsupportedOperationException on modification attempts.
- Language
- Java
- Module
- java.util
- Value
- []
- Type
- List
An immutable empty Map instance. Prefer Collections.emptyMap() which provides type-safe generics. Returned map throws UnsupportedOperationException on modification attempts.
- Language
- Java
- Module
- java.util
- Value
- {}
- Type
- Map
An immutable empty Set instance. Prefer Collections.emptySet() which provides type-safe generics. Returned set throws UnsupportedOperationException on modification attempts.
- Language
- Java
- Module
- java.util
- Value
- []
- Type
- Set
The largest positive finite value of type double, approximately 1.7976931348623157 × 10^308. This is the maximum value representable in IEEE 754 double-precision format.
- Language
- Java
- Module
- java.lang
- Value
- 1.7976931348623157e+308
- Type
- double
The smallest positive nonzero value of type double, approximately 4.9 × 10^-324. This is the smallest subnormal double, not the most negative double value.
- Language
- Java
- Module
- java.lang
- Value
- 4.9e-324
- Type
- double
A constant holding a Not-a-Number value for the double type. Produced by operations like 0.0/0.0. Double.NaN != Double.NaN is true; use Double.isNaN() to test.
- Language
- Java
- Module
- java.lang
- Value
- NaN
- Type
- double
A constant holding negative infinity for the double type. Results from overflow in the negative direction or division of a negative double by zero.
- Language
- Java
- Module
- java.lang
- Value
- -Infinity
- Type
- double
A constant holding positive infinity for the double type. Results from overflow or division of a positive double by zero. Greater than all finite double values.
- Language
- Java
- Module
- java.lang
- Value
- Infinity
- Type
- double
The largest positive finite value of type float, approximately 3.4028235 × 10^38. This is the maximum value representable in IEEE 754 single-precision format.
- Language
- Java
- Module
- java.lang
- Value
- 3.4028235e+38
- Type
- float
The smallest positive nonzero value of type float, approximately 1.4 × 10^-45. This is the smallest subnormal float, not the most negative float value.
- Language
- Java
- Module
- java.lang
- Value
- 1.4e-45
- Type
- float
A constant holding a Not-a-Number value for the float type. Produced by operations like 0.0f/0.0f. Float.NaN != Float.NaN is true; use Float.isNaN() to test.
- Language
- Java
- Module
- java.lang
- Value
- NaN
- Type
- float
A constant holding negative infinity for the float type. Results from overflow in the negative direction or division of a negative float by zero.
- Language
- Java
- Module
- java.lang
- Value
- -Infinity
- Type
- float
A constant holding positive infinity for the float type. Results from overflow or division of a positive float by zero. Greater than all finite float values.
- Language
- Java
- Module
- java.lang
- Value
- Infinity
- Type
- float
The maximum value of a 32-bit signed integer: 2^31 - 1. Equal to 2147483647. Frequently used as a sentinel for unreachable costs in graph algorithms and as an upper bound.
- Language
- Java
- Module
- java.lang
- Value
- 2147483647
- Type
- int
The minimum value of a 32-bit signed integer: -2^31. Equal to -2147483648. Note that Math.abs(Integer.MIN_VALUE) overflows and returns Integer.MIN_VALUE.
- Language
- Java
- Module
- java.lang
- Value
- -2147483648
- Type
- int
The maximum value of a 64-bit signed integer: 2^63 - 1. Equal to 9223372036854775807. Used for timestamp calculations and large-scale computations.
- Language
- Java
- Module
- java.lang
- Value
- 9223372036854775807
- Type
- long
The minimum value of a 64-bit signed integer: -2^63. Equal to -9223372036854775808. Like Integer.MIN_VALUE, its absolute value cannot be represented as a positive long.
- Language
- Java
- Module
- java.lang
- Value
- -9223372036854775808
- Type
- long
The maximum value of a 16-bit signed integer: 2^15 - 1. Equal to 32767. Used in audio processing and other domains where 16-bit precision suffices.
- Language
- Java
- Module
- java.lang
- Value
- 32767
- Type
- short
The minimum value of a 16-bit signed integer: -2^15. Equal to -32768. The short type is often used where memory conservation is important.
- Language
- Java
- Module
- java.lang
- Value
- -32768
- Type
- short
HTTP Status Codes59
The server has received the request headers and the client should proceed to send the request body. This interim response indicates the initial part of the request was received and has not yet been rejected.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 100
- Type
- status code
The server understands and is willing to comply with the client's request to switch protocols. Commonly used when upgrading from HTTP/1.1 to WebSocket via the Upgrade header.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 101
- Type
- status code
The server has received and is processing the request, but no response is available yet. This prevents the client from timing out when the server expects the request to take significant time.
- Language
- HTTP
- Module
- WebDAV
- Value
- 102
- Type
- status code
Used to return some response headers before the final HTTP message. Allows the browser to start preloading resources (via Link headers) while the server prepares the full response.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 103
- Type
- status code
The request has succeeded. The meaning of the success depends on the HTTP method: GET returns the resource, POST returns the result of the action, HEAD returns headers only.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 200
- Type
- status code
The request has been fulfilled and has resulted in one or more new resources being created. The primary resource is identified by a Location header or the request URI.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 201
- Type
- status code
The request has been accepted for processing, but the processing has not been completed. The request might or might not eventually be acted upon. Used for asynchronous operations.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 202
- Type
- status code
The server has successfully fulfilled the request and there is no additional content to send in the response body. Commonly used for successful DELETE operations or form submissions without navigation.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 204
- Type
- status code
The server has fulfilled the request and the user agent should reset the document view that caused the request. Used to clear form input after submission.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 205
- Type
- status code
The server is delivering only part of the resource due to a Range header sent by the client. Used for resumable downloads and video streaming to serve specific byte ranges.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 206
- Type
- status code
Conveys information about multiple resources in situations where multiple status codes might be appropriate. The response body is an XML document with individual status codes for each sub-request.
- Language
- HTTP
- Module
- WebDAV
- Value
- 207
- Type
- status code
The request has more than one possible response and the user or user agent should choose one. There is no standardized way of choosing one of the responses.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 300
- Type
- status code
The resource has been permanently moved to a new URI given by the Location header. Search engines update their links to the resource. Browsers may change POST to GET on redirect.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 301
- Type
- status code
The resource resides temporarily at a different URI given by the Location header. The client should continue using the original URI for future requests. Browsers may change POST to GET.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 302
- Type
- status code
The server is redirecting the client to a different resource using GET, typically after a POST or PUT. Unlike 301/302, the redirect always uses GET regardless of the original method.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 303
- Type
- status code
The resource resides temporarily at a different URI. Unlike 302, the HTTP method and body must not be changed when following the redirect. POST remains POST.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 307
- Type
- status code
The resource has been permanently moved to a new URI. Like 301 but guarantees that the HTTP method and body will not change on redirect. POST remains POST.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 308
- Type
- status code
The server cannot process the request due to something perceived to be a client error, such as malformed syntax, invalid request framing, or deceptive request routing.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 400
- Type
- status code
The request requires user authentication. The response includes a WWW-Authenticate header indicating the authentication scheme. Despite the name, this indicates unauthenticated, not unauthorized.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 401
- Type
- status code
Reserved for future use. Originally intended for digital payment schemes, it is not widely used. Some APIs use it to indicate that a payment or subscription is needed.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 402
- Type
- status code
The server understood the request but refuses to authorize it. Authentication will not help; the client does not have permission to access the resource. Unlike 401, identity is known.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 403
- Type
- status code
The server cannot find the requested resource. This is one of the most well-known HTTP status codes. It may also be used when a server wants to hide the existence of a resource from unauthorized clients.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 404
- Type
- status code
The HTTP method used is not supported for the requested resource. The response must include an Allow header listing the supported methods for the resource.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 405
- Type
- status code
The server cannot produce a response matching the list of acceptable values defined in the request's Accept headers (content negotiation). The server cannot serve content that the client can consume.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 406
- Type
- status code
Similar to 401 but indicates that the client must first authenticate with the proxy. The proxy returns a Proxy-Authenticate header with the required authentication scheme.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 407
- Type
- status code
The server timed out waiting for the request. The client did not produce a request within the time the server was prepared to wait. The client may retry the request without modifications.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 408
- Type
- status code
The request conflicts with the current state of the target resource. Used in situations like edit conflicts in version control, duplicate resource creation, or concurrent modification issues.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 409
- Type
- status code
The resource is no longer available and will not be available again. Unlike 404, this is a permanent condition. Search engines should remove the resource from their index.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 410
- Type
- status code
The server refuses the request because the Content-Length header is not defined and the server requires it. The client may retry the request with a valid Content-Length header.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 411
- Type
- status code
One or more conditions in the request header fields (such as If-Match or If-Unmodified-Since) evaluated to false. Used for conditional requests to prevent lost updates.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 412
- Type
- status code
The request entity is larger than the server is willing or able to process. The server may close the connection to prevent the client from continuing the request.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 413
- Type
- status code
The URI provided was too long for the server to process. This can occur when a client converts a POST request to a GET with long query data, or in redirect loops with long URIs.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 414
- Type
- status code
The server refuses the request because the payload format is not supported. The media type indicated by the Content-Type header or content encoding is not acceptable to the server.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 415
- Type
- status code
The client has asked for a portion of the file using the Range header, but the server cannot supply that portion. For example, requesting bytes beyond the end of the file.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 416
- Type
- status code
The server cannot meet the requirements of the Expect request-header field. Commonly occurs when a server does not support the '100-continue' expectation.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 417
- Type
- status code
An April Fools' joke from RFC 2324 (Hyper Text Coffee Pot Control Protocol). The server refuses to brew coffee because it is a teapot. Not expected to be implemented by actual HTTP servers.
- Language
- HTTP
- Module
- HTCPCP
- Value
- 418
- Type
- status code
The request was directed at a server that is not able to produce a response. Sent by a server that is not configured to produce responses for the combination of scheme and authority in the request URI.
- Language
- HTTP
- Module
- HTTP/2
- Value
- 421
- Type
- status code
The server understands the content type and syntax of the request, but was unable to process the contained instructions. Commonly used for validation errors in REST APIs.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 422
- Type
- status code
The resource that is being accessed is locked. Part of the WebDAV specification. The lock prevents the requested method from being applied to the resource.
- Language
- HTTP
- Module
- WebDAV
- Value
- 423
- Type
- status code
The request failed because it depended on another request that failed. Part of the WebDAV specification, used when a method could not be performed because the action depended on another action.
- Language
- HTTP
- Module
- WebDAV
- Value
- 424
- Type
- status code
The server is unwilling to risk processing a request that might be replayed. Used to prevent replay attacks when using TLS 1.3 early data (0-RTT).
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 425
- Type
- status code
The server refuses to perform the request using the current protocol but might do so after the client upgrades to a different protocol. The server sends an Upgrade header to indicate the required protocol.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 426
- Type
- status code
The origin server requires the request to be conditional. Intended to prevent the lost update problem where a client GETs a resource, modifies it, and PUTs it back while a third party has modified the resource.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 428
- Type
- status code
The user has sent too many requests in a given amount of time (rate limiting). The response should include a Retry-After header indicating how long to wait before making a new request.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 429
- Type
- status code
The server is unwilling to process the request because its header fields are too large. The request may be resubmitted after reducing the size of the request header fields.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 431
- Type
- status code
The server is denying access to the resource as a consequence of a legal demand. Named after the novel Fahrenheit 451. The response should include details about the legal restriction.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 451
- Type
- status code
The server encountered an unexpected condition that prevented it from fulfilling the request. This is a generic catch-all error when no more specific server error status code is appropriate.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 500
- Type
- status code
The server does not support the functionality required to fulfill the request. The server does not recognize the request method or lacks the ability to fulfill it.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 501
- Type
- status code
The server, while acting as a gateway or proxy, received an invalid response from an upstream server it accessed in attempting to fulfill the request.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 502
- Type
- status code
The server is currently unable to handle the request due to temporary overloading or maintenance. The server may include a Retry-After header to suggest when to retry.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 503
- Type
- status code
The server, while acting as a gateway or proxy, did not receive a timely response from the upstream server or some other auxiliary server it needed to access to complete the request.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 504
- Type
- status code
The server does not support the major version of HTTP that was used in the request. The server is indicating that it is unable or unwilling to complete the request using the same major version as the client.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 505
- Type
- status code
The server has an internal configuration error: the chosen variant resource is configured to engage in transparent content negotiation itself, creating a circular reference.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 506
- Type
- status code
The server is unable to store the representation needed to complete the request. Part of the WebDAV specification. The condition is considered temporary.
- Language
- HTTP
- Module
- WebDAV
- Value
- 507
- Type
- status code
The server detected an infinite loop while processing the request. Part of the WebDAV specification, sent when a PROPFIND with Depth: infinity encounters a binding loop.
- Language
- HTTP
- Module
- WebDAV
- Value
- 508
- Type
- status code
The policy for accessing the resource has not been met in the request. The server requires further extensions to the request in order to fulfill it.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 510
- Type
- status code
The client needs to authenticate to gain network access. Intended for use by intercepting proxies, such as captive portals for WiFi networks that require login before granting internet access.
- Language
- HTTP
- Module
- HTTP/1.1
- Value
- 511
- Type
- status code
Mathematical Constants16
The value of the Riemann zeta function at 3, denoted zeta(3), approximately 1.20206. Proved irrational by Roger Apery in 1979. Appears in quantum electrodynamics and number theory.
- Language
- Mathematics
- Value
- 1.20205690315959428540...
- Type
- irrational
The number of constituent particles in one mole of a substance, exactly 6.02214076 x 10^23 (since 2019 SI redefinition). Connects the atomic scale to the macroscopic scale in chemistry and physics.
- Language
- Mathematics
- Value
- 6.02214076e+23 mol^-1
- Type
- exact (SI definition)
Denoted k or kB, exactly 1.380649 x 10^-23 joules per kelvin (since 2019 SI redefinition). Relates the average kinetic energy of particles in a gas to the thermodynamic temperature.
- Language
- Mathematics
- Value
- 1.380649e-23 J/K
- Type
- exact (SI definition)
Denoted G or K, approximately 0.91597. Defined as the alternating sum of the reciprocals of odd squares. Appears in combinatorics, hyperbolic geometry, and many lattice problems.
- Language
- Mathematics
- Value
- 0.91596559417721901505...
- Type
- unknown rationality
The base of the natural logarithm, approximately 2.71828. It is the unique number whose natural logarithm is 1. Arises naturally in compound interest, probability theory, and as the base of the exponential function.
- Language
- Mathematics
- Value
- 2.71828182845904523536...
- Type
- irrational
The electric charge carried by a single proton, denoted e, exactly 1.602176634 x 10^-19 coulombs (since 2019 SI redefinition). The fundamental unit of electric charge; electron charge is -e.
- Language
- Mathematics
- Value
- 1.602176634e-19 C
- Type
- exact (SI definition)
Denoted by gamma, approximately 0.57722. Defined as the limiting difference between the harmonic series and the natural logarithm. It is unknown whether this constant is irrational.
- Language
- Mathematics
- Value
- 0.57721566490153286060...
- Type
- unknown rationality
Denoted alpha, approximately 1/137.036. A dimensionless physical constant characterizing the strength of the electromagnetic interaction between elementary charged particles. Its value is independent of the unit system.
- Language
- Mathematics
- Value
- 0.0072973525693...
- Type
- measured
Equal to (1 + sqrt(5)) / 2, approximately 1.61803. Two quantities are in the golden ratio if their ratio is the same as the ratio of their sum to the larger. Appears in the Fibonacci sequence, art, and nature.
- Language
- Mathematics
- Value
- 1.61803398874989484820...
- Type
- irrational
Denoted G, approximately 6.674 x 10^-11 N·m^2/kg^2. The proportionality constant in Newton's law of universal gravitation. One of the most difficult physical constants to measure precisely.
- Language
- Mathematics
- Value
- 6.67430e-11 N·m²/kg²
- Type
- measured
The natural logarithm of 2, approximately 0.69315. Appears in information theory (it converts between nats and bits), radioactive decay half-life calculations, and doubling-time formulas.
- Language
- Mathematics
- Value
- 0.69314718055994530941...
- Type
- irrational
The ratio of a circle's circumference to its diameter, one of the most fundamental and widely recognized mathematical constants. It is an irrational and transcendental number, appearing across all areas of mathematics and physics.
- Language
- Mathematics
- Value
- 3.14159265358979323846...
- Type
- irrational
A fundamental physical constant denoted h, equal to exactly 6.62607015 x 10^-34 joule-seconds (since 2019 SI redefinition). It relates the energy of a photon to its frequency via E = hf.
- Language
- Mathematics
- Value
- 6.62607015e-34 J·s
- Type
- exact (SI definition)
The speed of light in vacuum, denoted c, is exactly 299,792,458 meters per second. Since 1983 the meter has been defined in terms of the speed of light, making this value exact by definition.
- Language
- Mathematics
- Value
- 299792458 m/s
- Type
- exact (SI definition)
The square root of 2, approximately 1.41421. Also known as Pythagoras' constant, it was the first number proven to be irrational. It is the length of the diagonal of a unit square.
- Language
- Mathematics
- Value
- 1.41421356237309504880...
- Type
- irrational