Searching

Returns index of start of match
s1.find(s2);
first occurance of s2 in s1
s1.rfind(s2);
last occurance of s2 in s1
 std::string  s1  =  "abcdef---defghi";
 std::string  s2  =  "def";
 s1.find(s2);  //  returns 3
 s1.rfind(s2);  //  returns 9