Loading Variables from Text File in C++

Question

I know this question has been asked a million times before, but most of the questions are more complex than I need. I already know which lines will have what data, so I just want to load each line as its own variable.

For example, in "settings.txt":

800
600
32

And then, in the code, line 1 is set to int winwidth, line 2 is set to int winheight, and line 3 is set to int wincolor.

Sorry, I'm pretty new to I/O.

score 3 · Answer 1 · answered Aug 31 '12 at 02:51

3

Possibly the simplest thing you can do is this:

std::ifstream settings("settings.txt");
int winwidth;
int winheight;
int wincolor;

settings >> winwidth;
settings >> winheight;
settings >> wincolor;

However this will not ensure that each variable is on a new line, and doesn't contain any error handling.

answered Aug 31 '12 at 02:51

Michael Anderson

70,661
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1

I didn't end up using your code, but I did get it to work. Thanks for your reply, though, Michael. – user1637573 Aug 31 '12 at 02:59
1

@user1637573:If your problem is solved, you should mark it as solved. This is sheer waste of time of others otherwise. – Vinayak Garg Aug 31 '12 at 05:50

derpface · Answer 2 · 2012-08-31T04:00:22.407

#include <iostream>
#include <fstream>
#include <string>

using std::cout;
using std::ifstream;
using std::string;

int main()
{
    int winwidth,winheight,wincolor;       // Declare your variables
    winwidth = winheight = wincolor = 0;   // Set them all to 0

    string path = "filename.txt";          // Storing your filename in a string
    ifstream fin;                          // Declaring an input stream object

    fin.open(path);                        // Open the file
    if(fin.is_open())                      // If it opened successfully
    {
        fin >> winwidth >> winheight >> wincolor;  // Read the values and
                           // store them in these variables
        fin.close();                   // Close the file
    }

    cout << winwidth << '\n';
    cout << winheight << '\n';
    cout << wincolor << '\n';


    return 0;
}

ifstream can be used with the extraction operator >> in much the same way you use cin. Obviously there is a lot more to file I/O than this, but as requested, this is keeping it simple.

Loading Variables from Text File in C++

2 Answers2

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