Question

For Example:
If I need to read a multiple line input like(and I dont know How many lines would be there!!):

1 20

2 31

3 41

I am using something like

int main()
{
  string line;

  while(getline(cin,line) != NULL)
  {
       // some code
       // some code    
  }


}

Now the program never stops- i.e always it expects some input. How do i beak the loop when there are no more input lines ?

Answer 1

Just test the variable line for empty each time you read a line. If the use presses enter with no other data, then line will be empty.

#include <iostream>
#include <string>

using std::cin;
using std::getline;
using std::string;

int main(int argc, char *argv[]) {

    string line;

    while (true) {
        getline(cin, line);
        if (line.empty()) {
            break;
        }
        // some code
    }
    return 0;
}