Use istream_iterator and find : find « STL Algorithms Non modifying sequence operations « C++ Tutorial

1. C++ Tutorial
2. STL Algorithms Non modifying sequence operations
3. find

#include <iostream>        
#include <cassert>
#include <algorithm>
#include <list>
#include <iterator>
using namespace std;

int main()
{
  cout << "Type some characters, including an 'x' followed\n"
    << "by at least one nonwhite-space character: " << flush;

  istream_iterator<char> in(cin);
  istream_iterator<char> eos;
  find(in, eos, 'x');

  cout << "The first nonwhite-space character following\n"
       << "the first 'x' was '" << *(++in) << "'." << endl;

  return 0;
}

Type some characters, including an 'x' followed
by at least one nonwhite-space character: x is after y
The first nonwhite-space character following
the first 'x' was 'i'.