C++ File Handeling Problem

Question

I have just started learning file handeling in C++.

I know the basics, like fstream contains ofstream | ifstream, etc.

I tried to make a project, but there I needed a function that prints out all the numbers from a txt file.
You might thing that this code would work:

int gpr(const string& filename){
         fstream file
         file.open(filename, ios::in);

         if(!file){
                  cout << "The program is unable to locate the file." << endl;
                  return -1;
         }

         int value;
         file >> value;
         file.close();
         return value;
}

Which would, but the only problem is that it only reads the first line. Like if my txt file contains this:
90
102
91

The overall results would be 90. The other ones under 90 are getting ignored. I need a code that reads every single line and returns an integer. Please, make sure your code is:
1. Simple
2. Understandable
3. Not so long(in columns)
4. only contains these libraries: iostream, fstream, string. Nothing else.

Answer 1

You need to iterate through the whole file, not just read once from it. Collect the numbers in your preferred collection (std::vector<int> would be my number 1 choice probably) and return that, like this:

#include <iostream>
#include <fstream>
#include <vector>

std::vector<int> gpr(const std::string & fileName)
{
    std::ifstream file(fileName);
    std::vector<int> values;

    if (!file)
    {
        std::cout << "The program is unable to locate the file." << std::endl;
        return values;
    }
    
    while (!file.eof())
    {
        int value;
        file >> value;
        values.push_back(value);
    }
    
    file.close();
    return values;
}

int main()
{
    std::vector<int> values = gpr("numbers.txt");
    for (int value : values)
        std::cout << value << std::endl;

    return 0;
}

Comments

Im in my work