Find a substring in a string.
size_t strcspn( LPCSTR lpcszString, LPCSTR lpcszCharSet )
Returns the index of the first occurrence of a character in string that is in strCharSet. All characters before returned index are not in character set.
char str = "xyzababc";
pos = strcspn( str, "abc" );
printf( "First a, b or c in %s is at character %d\n", str, pos );