Code is failing to run properly after trying to read input from file

Question

I have an input file set up like this:

Hello there
1 4
Goodbye now
4.9 3

And I try to read the data as so:

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

int main(){
    ifstream input("file.txt");
    string name;
    double num1, num2;

    while(!input.eof()){
        getline(input, name);
        input >> num1;
        input >> num2;

        cout << name << endl;
        cout << num1 << " " << num2 << endl;
    }
}

But the read seems to be failing. Can anyone help me here?

Prefer `"\n"` to `std::endl` unless you have a reason to flush. — aschepler, Dec 04 '13 at 03:18

score 2 · Answer 1 · edited May 23 '17 at 12:13

2

Problem 1: getline with >>. Solution from this post: C++ iostream: Using cin >> var and getline(cin, var) input errors

Problem 2: inupt.eof() to test the end of loop, this post: Why is iostream::eof inside a loop condition considered wrong?

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

int main(){
  ifstream input("dat.txt");
  string name;
  double num1, num2;

  while (getline(input, name)) {  // getline fails at the end of file
    input >> num1 >> num2;
    input.ignore();
    cout << name << endl;
    cout << num1 << " " << num2 << endl;
  }
}

edited May 23 '17 at 12:13

Community

1
1

answered Dec 04 '13 at 03:17

gongzhitaao

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The output i get with your code for the file contents mentioned in the question is Hello there \n 1 4 \n 0 4 – Abhishek Bagchi Mar 06 '14 at 06:55
@AbhishekBagchi Interesting, I got the correct output with `gcc 4.8` on `Ubuntu 13.10`. – gongzhitaao Mar 07 '14 at 15:50

score 0 · Answer 2 · answered Mar 06 '14 at 07:14

This would work..

ifstream input("command2");
string name;
double num1, num2;

int x;

while(getline(input, name)){
    input >> num1;
    input >> num2;
    input.clear();
    cout << name << endl;
    cout << num1 << " " << num2 << endl;
    string dummy;
    getline(input,dummy);
}

I write the second getline() to make sure that the \n at the line with 1 4 is read.

Without that, what i get is

Hello there
1 4

0 4
Goodbye now
4.9 3

Hope this helps.

Code is failing to run properly after trying to read input from file

2 Answers2