C++ In a Nutshell

<cstdlib>

The <cstdlib> header is the C++ version of the C standard <stdlib.h> header, which declares macros, types, and functions of general utility. Several functions in <cstdlib> convert character arrays to numbers. You can also use a string stream (see <sstream>) if you want more control over the conversion, or if you need to convert a number to a string.

The multibyte functions (mblen, etc.) have counterparts in <cwchar> that are reentrant, that is, the <cwchar> functions take an explicit mbstate_t* parameter to avoid using an internal, static shift state.