Reading a text File in c++?

Question

I am trying to read a data from the file, but i am unable to do it. I am using code blocks IDE version 16.01.

my code:

#include <iostream>
#include <fstream>

using namespace std;

int main()
{
    ifstream read_file;
    read_file.open("rfile.txt");
    int numFromFile=0,sum;
    while(!read_file.eof())
    {
        read_file >> numFromFile;
        sum+=numFromFile;
    }
    cout <<"sum of numbers :" << sum << endl;
    read_file.close();
    return 0;
}

To begin with, your usage of `while(!read_file.eof())` is [wrong](https://stackoverflow.com/questions/5605125/why-is-iostreameof-inside-a-loop-condition-i-e-while-stream-eof-cons). — MikeCAT, May 21 '21 at 15:13
Consider [turning on compiler warnings](https://godbolt.org/z/x9ohY4MTa) to be informed of potential code mistakes. — Drew Dormann, May 21 '21 at 16:01

score 0 · Answer 1 · answered May 21 '21 at 16:00

You should initialize sum at first, and read the file content inside the while condition:

#include <iostream>
#include <fstream>

int main()
{
    std::ifstream read_file;
    read_file.open("rfile.txt");
    int numFromFile = 0, sum = 0;
    while(read_file >> numFromFile)
    {
        sum += numFromFile;
    }
    std::cout << "sum of numbers :" << sum << std::endl;
    read_file.close();
    return 0;
}

Reading a text File in c++?

1 Answers1