# Fixed width integer types (since C99)

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< c‎ | types

### 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

The implementation may define typedef names `intN_t`, `int_fastN_t`, `int_leastN_t`, `uintN_t`, `uint_fastN_t`, and `uint_leastN_t` when N is not 8, 16, 32 or 64. Typedef names of the form `intN_t` may only be defined if the implementation supports an integer type of that width with no padding. Thus, uint24_t denotes an unsigned integer type with a width of exactly 24 bits.

Each of the macros listed in below is defined if and only if the implementation defines the corresponding typedef name. The macros `INTN_C` and `UINTN_C` correspond to the typedef names `int_leastN_t` and `uint_leastN_t`, respectively.

### Macro constants

Defined in header ``<stdint.h>``

##### Signed integers : width

INT8_WIDTHINT16_WIDTHINT32_WIDTHINT64_WIDTH (C23)(optional) | bit width of an object of type int8_t, int16_t, int32_t, int64_t (exactly 8, 16, 32, 64) (macro constant)
INT_FAST8_WIDTHINT_FAST16_WIDTHINT_FAST32_WIDTHINT_FAST64_WIDTH (C23) | bit width of an object of type int_fast8_t, int_fast16_t, int_fast32_t, int_fast64_t (macro constant)
INT_LEAST8_WIDTHINT_LEAST16_WIDTHINT_LEAST32_WIDTHINT_LEAST64_WIDTH (C23) | bit width of an object of type int_least8_t, int_least16_t, int_least32_t, int_least64_t (macro constant)
INTPTR_WIDTH (C23)(optional) | bit width of an object of type intptr_t (macro constant)
INTMAX_WIDTH (C23) | bit width of an object of type intmax_t (macro constant)

##### 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 : width

UINT8_WIDTHUINT16_WIDTHUINT32_WIDTHUINT64_WIDTH (C23)(optional) | bit width of an object of type uint8_t, uint16_t, uint32_t, uint64_t (exactly 8, 16, 32, 64) (macro constant)
UINT_FAST8_WIDTHUINT_FAST16_WIDTHUINT_FAST32_WIDTHUINT_FAST64_WIDTH (C23) | bit width of an object of type uint_fast8_t, uint_fast16_t, uint_fast32_t, uint_fast64_t (macro constant)
UINT_LEAST8_WIDTHUINT_LEAST16_WIDTHUINT_LEAST32_WIDTHUINT_LEAST64_WIDTH (C23) | bit width of an object of type uint_least8_t, uint_least16_t, uint_least32_t, uint_least64_t (macro constant)
UINTPTR_WIDTH (C23)(optional) | bit width of an object of type uintptr_t (macro constant)
UINTMAX_WIDTH (C23) | bit width of an object of type uintmax_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)

### 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

### Format macro constants

Defined in header ``<inttypes.h>``

#### Format constants for the fprintf family of functions

Each of the `PRI` macros listed here is defined if and only if the implementation defines the corresponding typedef name.

Equivalent for int or unsigned int | Description | Macros for data types
--- | --- | ---
`[u]intx_t` | `[u]int_leastx_t` | `[u]int_fastx_t` | `[u]intmax_t` | `[u]intptr_t`
`d` | output of a signed decimal integer value | PRIdx | PRIdLEASTx | PRIdFASTx | PRIdMAX | PRIdPTR
`i` | PRIix | PRIiLEASTx | PRIiFASTx | PRIiMAX | PRIiPTR
`u` | output of an unsigned decimal integer value | PRIux | PRIuLEASTx | PRIuFASTx | PRIuMAX | PRIuPTR
`o` | output of an unsigned octal integer value | PRIox | PRIoLEASTx | PRIoFASTx | PRIoMAX | PRIoPTR
`x` | output of an unsigned lowercase hexadecimal integer value | PRIxx | PRIxLEASTx | PRIxFASTx | PRIxMAX | PRIxPTR
`X` | output of an unsigned uppercase hexadecimal integer value | PRIXx | PRIXLEASTx | PRIXFASTx | PRIXMAX | PRIXPTR

#### Format constants for the fscanf family of functions

Each of the `SCN` macros listed in here is defined if and only if the implementation defines the corresponding typedef name and has a suitable fscanf length modifier for the type.

Equivalent for int or unsigned int | Description | Macros for data types
--- | --- | ---
`[u]intx_t` | `[u]int_leastx_t` | `[u]int_fastx_t` | `[u]intmax_t` | `[u]intptr_t`
`d` | input of a signed decimal integer value | SCNdx | SCNdLEASTx | SCNdFASTx | SCNdMAX | SCNdPTR
`i` | input of a signed integer value (base is determined by the first characters parsed) | SCNix | SCNiLEASTx | SCNiFASTx | SCNiMAX | SCNiPTR
`u` | input of an unsigned decimal integer value | SCNux | SCNuLEASTx | SCNuFASTx | SCNuMAX | SCNuPTR
`o` | input of an unsigned octal integer value | SCNox | SCNoLEASTx | SCNoFASTx | SCNoMAX | SCNoPTR
`x` | input of an unsigned hexadecimal integer value | SCNxx | SCNxLEASTx | SCNxFASTx | SCNxMAX | SCNxPTR

### Example

See also C++ compatibility note regarding spaces before format macros used in this example.

Run this code

    #include <inttypes.h>
    #include <stdio.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);
    }

Possible output:

    8
    lld
    -9223372036854775808
    +9223372036854775807
    +7

### References

- C23 standard (ISO/IEC 9899:2024):

  - 7.8.1 Macros for format specifiers (p: TBD)

  - 7.18 Integer types <stdint.h> (p: TBD)

- C17 standard (ISO/IEC 9899:2018):

  - 7.8.1 Macros for format specifiers (p: 158-159)

  - 7.18 Integer types <stdint.h> (p: 212-216)

- C11 standard (ISO/IEC 9899:2011):

  - 7.8.1 Macros for format specifiers (p: 217-218)

  - 7.18 Integer types <stdint.h> (p: 289-295)

- C99 standard (ISO/IEC 9899:1999):

  - 7.8.1 Macros for format specifiers (p: 198-199)

  - 7.18 Integer types <stdint.h> (p: 255-261)

### See also

- Arithmetic types

C++ documentation for Fixed width integer types
C++ documentation for User-defined literals (formatting macros note)

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