PROBLEM SOLVED! Solution found thanks to Debaug in the comments section. Thank you all for helping.

!!!! Update: I added the function perror() inside my check function and it tells me "no such file or directory". So I am pretty sure that my problem comes from where my file is stored. As said in the comments, the file probably isn't in the projects root directory. However I have no idea how to access the root directory. !!!!

I am new to c++ and to programming in general. My problem is very basic but none of the existing answers found on the web worked for it.

I am trying to open a file stored on my computer and to extract the data from it. Here is my code:

#include <iostream>
#include <fstream>
#include <iomanip>
#include <cmath>
#include <cstdio>

using namespace std;

int main()
{
    // Naming the variables
    float Grade;
    float Total;
    float Grade_In_Percentage;
    ifstream inData;

    // Opening the file
    inData.open("test.txt");

    if(inData.fail())
    {
        cout << "Fail: Cannot open the file" << endl;
        perror(0)
        return 1;
    }
    
    // Extracting the data
    cin >> Grade >> Total;

    // Calculations
    Grade_In_Percentage = Grade * 100 / Total;

    // Display
    cout << "Your grade in percentage is:" << setprecision(7) << Grade_In_Percentage << endl;
    Grade_In_Percentage = ceil(Grade_In_Percentage);
    cout << "round up:" << Grade_In_Percentage << endl;

    if (Grade_In_Percentage < 50)
        cout << "Fail" << endl;
    else if (Grade_In_Percentage >= 60)
            cout << "Need improvment" << endl;
        else if (Grade_In_Percentage > 70)
                cout << "Good" << endl;
            else if (Grade_In_Percentage > 80)
                    cout << "Well done" << endl;
                else if (Grade_In_Percentage > 90)
                        cout << "Excellent" << endl;

    return 0;
}

As a result, I get "Fail: Cannot open the file".

What could I do?