strcspn get span until character in string res = strcspn(string_one, string_two) string_one a character string or matrix of character strings. string_two a character string or matrix of character strings. res a matrix. res = strcspn(string_one,string_two) scans string_one for the first occurrence of any of the characters that are part of string_two, returning the number of characters of string_one read before this first occurrence. string_two must have same dimensions than string_one or string_two must be a string. strspn