recursion - recursive solution to find index of match for two strings -

my code below return random values matching starting index 2 strings. example, if s = mississippi, , t = sip, function should return 6. set code up, print out value of m before returns it. indeed, program prints out 6, returns random values in millions.

int index_of_sub(string s, string t, int m) {   if(s.length() - m < t.length())   {     return -1;    }   if(s.substr(m, t.length()) == t)   {     cout << m << endl;      return m;    }   else   {     index_of_sub(s, t, m + 1);    } }//end index_of_sub function int index_of(string s, string t) {   return index_of_sub(s, t, 0);  }//end index_of function 

you need put return statement on last else.

else {    return index_of_sub(s, t, m + 1);     ^^^^^^ } 

since not explicitly returning result of recursive call, garbage value being returned why getting such strange results.