SIZE_T

This is an unsigned integer type used to represent sizes, counts, and indices, particularly when working with containers like std::string. Although size_t is officially defined in the <cstddef> header, it is also accessible through <string> because <string> includes headers that define it. Within the std::string class, functions such as .size(), .length(), .find(), and .substr() return or accept size_t values to ensure safe indexing and size representation across platforms. Using size_t helps avoid signed/unsigned mismatch warnings and supports consistent behavior in operations involving string lengths or positions.