strspn

Returns the length of the leading characters in a string that are contained in a specified string.

size_t *strspn( const char *string, const char *skipset);

string	Null-terminated string to be scanned.
skipset	Null-terminated string containing character set.

strspn returns the length of the substring that starts at the beginning of string and contains only characters that are in skipset.

Return Values

Returns the length of the initial substring of argument string that is only composed of characters included in skipset.