c++ - Alternative Characters - HackerRank -

i beginner, alternative code welcomed. program crashes after inputing values. want know more problem, since have seen many time.

#include<cstdio> #include<vector> #include<iostream> #include<string> using namespace std;   int main() { vector<string> str; int n,i=0,count=0,a=0,b=1; string j;  cin >> n;  while(i<n) {     cin >> j;     str.push_back(j);     i++; }  for(i=0;i<n;i++) {     while(b!='\0')     {         if(str[i][a] == str[i][b])            {              count++;            }         a++;         b++;     } }  cout << count; return 0; } 

in order strange program work should 3 things: set init values a , b on every external loop step; change b!='\0' condition str[i].c_str()[b]!='\0' in order check not b, string literal; call string::c_str() method on strings, because not guaranteed string null-terminated, c-style strings stand condition.

for(i=0;i<n;i++) {     = 0;     b = 1;     while(str[i].c_str()[b]!='\0')     {         if(str[i].c_str()[a] == str[i].c_str()[b])            {              count++;            }         a++;         b++;     } }