type
<cstddef> <cstdio> <cstdlib> <cstring> <ctime> <cwchar>
size_t
Unsigned integral type
Alias of one of the fundamental unsigned integer types.
It is a type able to represent the size of any object in bytes: size_t is the type returned by the sizeof operator and is widely used in the standard library to represent sizes and counts.
In <cstdlib>, it is used as the type of some parameters in the functions bsearch, qsort, calloc, malloc, realloc, mblen, mbtowc, mbstowcs and wcstombs, and in the case of mbstowcs and wcstombs also as its returning type.
In all cases it is used as a type to represent the length or count in bytes of a specific buffer or string.