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 <ctime>, it is used in the function strftime as the type of its parameter maxsize and as its return value. In both cases it is used to express counts of characters.