Defined in header <cstdlib> unsigned long strtoul( const char *str, char **str_end, int base ); unsigned long long strtoull( const char *str, char **str_end, int base ); (since C++11)
Interprets an unsigned integer value in a byte string pointed to by str.
Discards any whitespace characters (as identified by calling isspace()) until the first non-whitespace character is found, then takes as many characters as possible to form a valid base-n (where n=base) unsigne