Defined in header <uchar.h>
typedef uint_least16_t char16_t;
(since C11)
Defined in header <stdint.h>
typedef /*implementation-defined*/ uint_least16_t;
(since C99)

char16_t is an unsigned integer type used for 16-bit wide characters and is the same type as uint_least16_t.

uint_least16_t is the smallest unsigned integer type with width of at least 16 bits.


On any given platform, the width of type char16_t can be greater than 16 bits, but the actual values stored in an object of type char16_t will always have a width of 16 bits.


#include <uchar.h>
#include <stdio.h>
int main(void)
    char16_t wcs[] = u"zß水🍌"; // or "z\u00df\u6c34\U0001f34c"
    size_t wcs_sz = sizeof wcs / sizeof *wcs;
    printf("%zu UTF-16 code units: [ ", wcs_sz);
    for (size_t n = 0; n < wcs_sz; ++n) printf("%#x ", wcs[n]);

Possible output:

6 UTF-16 code units: [ 0x7a 0xdf 0x6c34 0xd83c 0xdf4c 0 ]


  • C11 standard (ISO/IEC 9899:2011):
    • 7.28 Unicode utilities <uchar.h> (p: 398)
    • Minimum-width integer types (p: 290)
  • C99 standard (ISO/IEC 9899:1999):
    • Minimum-width integer types (p: 256)

See also

C++ documentation for Fundamental types

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