#include <stdlib.h>long long int strtoll(const char * restrict start, char ** restrict end, int radix);
strtoll( ) was added by C99.
The strtoll( ) function is similar to strtol( ) except that it returns a long long int. If the result cannot be represented by a long integer, LLONG_MAX or LLONG_MIN is returned, and the global errno is set to ERANGE, indicating a range error. If start does not point to a number, no conversion takes place and zero is returned.
Related functions are atol( ) and strtol( ).