limits.h includes definitions of the characteristics of common variable types. The values are implementation specific, but may not be of lower magnitude than certain specified values in a conforming C implementation.
The C99 standard also specifies the <stdint.h> header file, which provides names and limits for explicitly-sized platform-independent integer datatypes (e.g. int32_t for a 32-bit signed integer).
Two's complement implementations have SCHARMIN equal to −128 (and similarly for all other MIN values). 32-bit implementations will set INTMAX equal to +2,147,483,647 (and likewise for INTMIN and UINTMAX) Unicode-supporting implementations will set MBLENMAX to 4 or more. Many DSPs have CHARBIT equal to 16 or more.
Member constants[edit]
The 'minimum-magnitude value' column is the minimum possible magnitude for this constant as specified by the standard. In particular, _MIN values represent the minimum magnitude representable in the rarely-used one's complement and sign-magnitude forms. Most implementations will have larger magnitudes for at least some of these numbers. For instance: /afv-tom-bergeron-auto-tune.html.
- Two's complement implementations have
SCHAR_MINequal to −128 (and similarly for all other_MINvalues). - 32-bit implementations will set
INT_MAXequal to +2,147,483,647 (and likewise forINT_MINandUINT_MAX) - Unicode-supporting implementations will set
MB_LEN_MAXto 4 or more. - Many DSPs have
CHAR_BITequal to 16 or more[1][2].
| Name | Description | Typical value | ANSI standard minimum- or maximum magnitude value | |
|---|---|---|---|---|
CHAR_BIT | Number of bits in a char | 8 | ≥+8 | |
SCHAR_MIN | Minimum value for a signed char | −128 | ≤−127 | |
SCHAR_MAX | Maximum value for a signed char | +127 | ≥+127 | |
UCHAR_MAX | Maximum value for an unsigned char | +255 | ≥+255 | |
CHAR_MIN | Minimum value for a char | −128 | ≤−127 (if char is represented as asigned char; otherwise ≤0) | |
CHAR_MAX | Maximum value for a char | +127 | ≥+127 (if char is represented as asigned char; otherwise ≥+255) | |
MB_LEN_MAX | Maximum multi byte length of a character across all locales | varies, usually at least 4 | ≥+1 | |
SHRT_MIN | Minimum value for a short int | −32,768 | ≤−32,767 | |
SHRT_MAX | Maximum value for a short int | +32,767 | ≥+32,767 | |
USHRT_MAX | Maximum value for an unsigned short int | +65,535 | ≥+65,535 | |
INT_MIN | Minimum value for an int | −2,147,483,648 | ≤−32,767 | |
INT_MAX | Maximum value for an int | +2,147,483,647 | ≥+32,767 | |
UINT_MAX | Maximum value for an unsigned int | +4,294,967,295 | ≥+65,535 | |
LONG_MIN | Minimum value for a long int | 32 bit compiler | −2,147,483,648 | ≤−2,147,483,647 |
| 64 bit compiler | −9,223,372,036,854,775,808 | |||
LONG_MAX | Maximum value for a long int | 32 bit compiler | +2,147,483,647 | ≥+2,147,483,647 |
| 64 bit compiler | +9,223,372,036,854,775,807 | |||
ULONG_MAX | Maximum value for an unsigned long int | 32 bit compiler | +4,294,967,295 | ≥+4,294,967,295 |
| 64 bit compiler | +18,446,744,073,709,551,615 | |||
LLONG_MIN | Minimum value for a long long int | −9,223,372,036,854,775,808 | ≤−9,223,372,036,854,775,807 | |
LLONG_MAX | Maximum value for a long long int | +9,223,372,036,854,775,807 | ≥+9,223,372,036,854,775,807 | |
ULLONG_MAX | Maximum value for an unsigned long long int | +18,446,744,073,709,551,615 | ≥+18,446,744,073,709,551,615 | |
References[edit]
- C Guide--2.5 limits.h, accessed on September 2006.
