Fixed width integer types (since C99) - cppreference.com

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# Fixed width integer types (since C99)

From cppreference.com
< c‎ | types

### [edit] Types

Defined in header `<stdint.h>`
`int8_t` `int16_t` `int32_t` `int64_t` | signed integer type with width of exactly 8, 16, 32 and 64 bits respectively with no padding bits and using 2's complement for negative values (provided only if the implementation directly supports the type)
`int_fast8_t` `int_fast16_t` `int_fast32_t` `int_fast64_t` | fastest signed integer type with width of at least 8, 16, 32 and 64 bits respectively
`int_least8_t` `int_least16_t` `int_least32_t` `int_least64_t` | smallest signed integer type with width of at least 8, 16, 32 and 64 bits respectively
`intmax_t` | maximum width integer type
`intptr_t` | integer type capable of holding a pointer
`uint8_t` `uint16_t` `uint32_t` `uint64_t` | unsigned integer type with width of exactly 8, 16, 32 and 64 bits respectively (provided only if the implementation directly supports the type)
`uint_fast8_t` `uint_fast16_t` `uint_fast32_t` `uint_fast64_t` | fastest unsigned integer type with width of at least 8, 16, 32 and 64 bits respectively
`uint_least8_t` `uint_least16_t` `uint_least32_t` `uint_least64_t` | smallest unsigned integer type with width of at least 8, 16, 32 and 64 bits respectively
`uintmax_t` | maximum width unsigned integer type
`uintptr_t` | unsigned integer type capable of holding a pointer

### [edit] Macro constants

Defined in header `<stdint.h>`
##### Signed integers : minimum value
INT8_MININT16_MININT32_MININT64_MIN | minimum value of an object of type int8_t, int16_t, int32_t, int64_t (macro constant)
INT_FAST8_MININT_FAST16_MININT_FAST32_MININT_FAST64_MIN | minimum value of an object of type int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t (macro constant)
INT_LEAST8_MININT_LEAST16_MININT_LEAST32_MININT_LEAST64_MIN | minimum value of an object of type int_least8_t, int_least16_t, int_least32_t, int_least64_t (macro constant)
INTPTR_MIN | minimum value of an object of type intptr_t (macro constant)
INTMAX_MIN | minimum value of an object of type intmax_t (macro constant)
##### Signed integers : maximum value
INT8_MAXINT16_MAXINT32_MAXINT64_MAX | maximum value of an object of type int8_t, int16_t, int32_t, int64_t (macro constant)
INT_FAST8_MAXINT_FAST16_MAXINT_FAST32_MAXINT_FAST64_MAX | maximum value of an object of type int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t (macro constant)
INT_LEAST8_MAXINT_LEAST16_MAXINT_LEAST32_MAXINT_LEAST64_MAX | maximum value of an object of type int_least8_t, int_least16_t, int_least32_t, int_least64_t (macro constant)
INTPTR_MAX | maximum value of an object of type intptr_t (macro constant)
INTMAX_MAX | maximum value of an object of type intmax_t (macro constant)
##### Unsigned integers : maximum value
UINT8_MAXUINT16_MAXUINT32_MAXUINT64_MAX | maximum value of an object of type uint8_t, uint16_t, uint32_t, uint64_t (macro constant)
UINT_FAST8_MAXUINT_FAST16_MAXUINT_FAST32_MAXUINT_FAST64_MAX | maximum value of an object of type uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t (macro constant)
UINT_LEAST8_MAXUINT_LEAST16_MAXUINT_LEAST32_MAXUINT_LEAST64_MAX | maximum value of an object of type uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t (macro constant)
UINTPTR_MAX | maximum value of an object of type uintptr_t (macro constant)
UINTMAX_MAX | maximum value of an object of type uintmax_t (macro constant)

### [edit] Function macros for minimum-width integer constants

INT8_CINT16_CINT32_CINT64_C | expands to an integer constant expression having the value specified by its argument and the type int_least8_t, int_least16_t, int_least32_t, int_least64_t respectively (function macro)
INTMAX_C | expands to an integer constant expression having the value specified by its argument and the type intmax_t (function macro)
UINT8_CUINT16_CUINT32_CUINT64_C | expands to an integer constant expression having the value specified by its argument and the type uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t respectively (function macro)
UINTMAX_C | expands to an integer constant expression having the value specified by its argument and the type uintmax_t (function macro)

    #include <stdint.h>
    UINT64_C(0x123) // might expand to 0x123ULL or 0x123UL

### [edit] Format macro constants

| This section is incomplete Reason: will look better as a table

Defined in header `<inttypes.h>`
##### Format constants for the fprintf family of functions
PRId8PRId16PRId32PRId64PRIdLEAST8PRIdLEAST16PRIdLEAST32PRIdLEAST64PRIdFAST8PRIdFAST16PRIdFAST32PRIdFAST64PRIdMAXPRIdPTR | format conversion specifier to output a signed decimal integer value of type int8_t, int16_t, int32_t, int64_t, int_least8_t, int_least16_t, int_least32_t, int_least64_t, int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t, intmax_t, intptr_t respectively, equivalent to `%d` for int (macro constant)
PRIi8PRIi16PRIi32PRIi64PRIiLEAST8PRIiLEAST16PRIiLEAST32PRIiLEAST64PRIiFAST8PRIiFAST16PRIiFAST32PRIiFAST64PRIiMAXPRIiPTR | format conversion specifier to output a signed decimal integer value of type int8_t, int16_t, int32_t, int64_t, int_least8_t, int_least16_t, int_least32_t, int_least64_t, int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t, intmax_t, intptr_t respectively, equivalent to `%i` for int (macro constant)
PRIu8PRIu16PRIu32PRIu64PRIuLEAST8PRIuLEAST16PRIuLEAST32PRIuLEAST64PRIuFAST8PRIuFAST16PRIuFAST32PRIuFAST64PRIuMAXPRIuPTR | format conversion specifier to output an unsigned decimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to `%u` for unsigned int (macro constant)
PRIo8PRIo16PRIo32PRIo64PRIoLEAST8PRIoLEAST16PRIoLEAST32PRIoLEAST64PRIoFAST8PRIoFAST16PRIoFAST32PRIoFAST64PRIoMAXPRIoPTR | format conversion specifier to output an unsigned octal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to `%o` for unsigned int (macro constant)
PRIx8PRIx16PRIx32PRIx64PRIxLEAST8PRIxLEAST16PRIxLEAST32PRIxLEAST64PRIxFAST8PRIxFAST16PRIxFAST32PRIxFAST64PRIxMAXPRIxPTR | format conversion specifier to output an unsigned hexadecimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to `%x` for unsigned int (macro constant)
PRIX8PRIX16PRIX32PRIX64PRIXLEAST8PRIXLEAST16PRIXLEAST32PRIXLEAST64PRIXFAST8PRIXFAST16PRIXFAST32PRIXFAST64PRIXMAXPRIXPTR | format conversion specifier to output an unsigned uppercase hexadecimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to `%X` for unsigned int (macro constant)
##### Format constants for the fscanf family of functions
SCNd8SCNd16SCNd32SCNd64SCNdLEAST8SCNdLEAST16SCNdLEAST32SCNdLEAST64SCNdFAST8SCNdFAST16SCNdFAST32SCNdFAST64SCNdMAXSCNdPTR | format conversion specifier to input a signed decimal integer value of type int8_t, int16_t, int32_t, int64_t, int_least8_t, int_least16_t, int_least32_t, int_least64_t, int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t, intmax_t, intptr_t respectively, equivalent to `%d` for int (macro constant)
SCNi8SCNi16SCNi32SCNi64SCNiLEAST8SCNiLEAST16SCNiLEAST32SCNiLEAST64SCNiFAST8SCNiFAST16SCNiFAST32SCNiFAST64SCNiMAXSCNiPTR | format conversion specifier to input a signed decimal/octal/hexadecimal integer value of type int8_t, int16_t, int32_t, int64_t, int_least8_t, int_least16_t, int_least32_t, int_least64_t, int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t, intmax_t, intptr_t respectively, equivalent to `%i` for int (macro constant)
SCNu8SCNu16SCNu32SCNu64SCNuLEAST8SCNuLEAST16SCNuLEAST32SCNuLEAST64SCNuFAST8SCNuFAST16SCNuFAST32SCNuFAST64SCNuMAXSCNuPTR | format conversion specifier to input an unsigned decimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to `%u` for unsigned int (macro constant)
SCNo8SCNo16SCNo32SCNo64SCNoLEAST8SCNoLEAST16SCNoLEAST32SCNoLEAST64SCNoFAST8SCNoFAST16SCNoFAST32SCNoFAST64SCNoMAXSCNoPTR | format conversion specifier to input an unsigned octal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to `%o` for unsigned int (macro constant)
SCNx8SCNx16SCNx32SCNx64SCNxLEAST8SCNxLEAST16SCNxLEAST32SCNxLEAST64SCNxFAST8SCNxFAST16SCNxFAST32SCNxFAST64SCNxMAXSCNxPTR | format conversion specifier to input an unsigned hexadecimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to `%x` for unsigned int (macro constant)
SCNX8SCNX16SCNX32SCNX64SCNXLEAST8SCNXLEAST16SCNXLEAST32SCNXLEAST64SCNXFAST8SCNXFAST16SCNXFAST32SCNXFAST64SCNXMAXSCNXPTR | format conversion specifier to input an unsigned uppercase hexadecimal integer value of type uint8_t, uint16_t, uint32_t, uint64_t, uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t, uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t, uintmax_t, uintptr_t respectively, equivalent to `%X` for unsigned int (macro constant)

### [edit] Example

Run this code

    #include <stdio.h>
    #include <inttypes.h>

    int main(void)
    {
        printf("%zu\n", sizeof(int64_t));
        printf("%s\n", PRId64);
        printf("%+"PRId64"\n", INT64_MIN);
        printf("%+"PRId64"\n", INT64_MAX);

        int64_t n = 7;
        printf("%+"PRId64"\n", n);

        return 0;
    }

Possible output:

    8
    ld
    -9223372036854775808
    +9223372036854775807
    +7

### [edit] See also

- Arithmetic types
- C++ type system overview
- Type support (basic types, RTTI, type traits)

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