C++ reading from file is not giving expected, or any output

Question

I am trying to make a game which loads it's levels from a text file. I decided to do this with the help of a 2 dimensional vector of integers. Before implementing it in my main code, I first decided to check whether my logic was right so I made a Test.txt file containing the the level I wanted to draw.

Test.txt:-

1 1 0 0 1 0 0 0 0 0 1 1 1 1 1 1 1 0 1 0 1 0 0 1 0 0 1 0 0 1 1 0  
1 0 1 0 1 1 1 0 1 1 0 1 1 0 1 1 1 0 1 0 0 1 1 1 1 1 1 0 0 1 0 0  
0 0 0 0 0 0 0 1 0 1 0 0 0 1 1 0 1 1 0 0 0 0 0 0 1 0 0 1 0 1 1 0  
0 0 1 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 0 1 1 1 1 0 0 0 1 0 1 1 1 0  
1 0 0 0 1 0 0 0 1 1 1 1 1 1 1 1 1 1 1 0 1 0 0 0 0 0 1 0 0 1 0 1  
0 1 0 1 0 1 1 1 0 0 1 0 0 0 0 1 0 1 0 0 1 0 1 1 0 0 0 0 1 1 0 1  
0 1 1 1 0 1 1 0 1 0 1 1 0 1 1 0 0 1 0 0 0 1 1 0 1 1 1 1 1 1 0 1  
0 0 0 0 0 0 0 1 1 0 1 1 0 0 0 0 0 1 0 1 0 1 1 0 0 1 0 0 0 1 0 0  
0 0 1 1 1 0 0 0 1 0 0 1 1 1 1 0 0 1 1 0 0 0 1 1 1 0 1 1 1 1 0 1  
0 1 0 0 1 1 0 0 1 0 1 1 0 1 0 0 1 1 0 1 1 0 1 0 0 1 1 1 1 0 1 1  
1 1 0 1 1 1 1 0 0 1 0 0 1 0 0 1 0 1 0 1 1 1 1 1 0 0 0 1 1 0 1 0  
0 0 1 0 0 0 1 1 1 0 1 0 0 1 0 1 1 0 0 0 1 1 0 1 0 0 0 0 1 1 0 1  
0 1 1 0 0 0 0 0 0 1 1 0 1 1 0 1 1 0 1 0 0 1 0 0 1 1 0 1 1 1 1 0  
1 0 1 1 1 0 1 1 1 1 0 0 0 0 0 0 1 0 1 0 0 0 1 1 1 0 0 1 1 0 0 0  
1 0 1 1 0 0 0 0 1 0 0 1 1 0 0 0 1 0 0 1 0 0 0 1 0 1 0 1 1 0 0 1  
0 0 1 1 1 0 1 1 1 0 1 0 0 0 1 0 1 1 1 1 0 0 0 0 0 0 1 1 1 1 1 0  
0 0 0 1 0 1 0 1 0 1 0 0 1 1 1 0 0 1 1 0 1 0 1 0 1 1 1 0 0 0 1 0  
1 0 1 0 1 0 0 0 1 1 0 0 0 1 0 1 1 1 1 1 0 0 1 0 1 0 1 1 1 1 1 1  

Each integer is seperated by a space and only one number is supposed to be read once at a time. The 1 and 0 tell the game which tile to draw. Now, with this wrote the following code in c++ to read the file and populate the vector with it's contents. After that it's supposed to output the contents of the vector.

Test.cpp:-

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

using namespace std;

int num;
vector<vector<int>> nums;

int main(void) {

    ifstream FileIn;
    FileIn.open("Test.txt");

    for(int i = 0; i < 18; i++) {
        vector<int> temp;
        for(int j = 0; j < 32; j++) {
            FileIn >> num;
            temp.push_back(num);
        }
        nums.push_back(temp);
        temp.clear();
    }
    
    cout << nums.size() << '\n'; // outputs 18
    
    for (unsigned int i=0; i < nums.size(); i++) {
        for (unsigned int j=0; j < nums[i].size(); j++) {
            cout << nums[i][j];
            if (j == nums[i].size() - 1) cout << '\n';
        }
    }

    FileIn.close();

    return 0;
}

but this is where the problem starts. The code doesn't output anything to the terminal it just starts and then goes back to the prompt.

The executable compiles with no errors and there are no crashes or runtime error either. There is just no output.

Things i have tried:

• Putting in spaces between the numbers
• Keeping all integers on the same line
• both of the solutions above, but together this time

I am using atom with the platformio terminal plugin on windows 10 (64-bit) on a intel with amd-64 architecture. Any help would be very appreciated.

Answer 1

A few things: Start learning how to use a debugger. Your question to stackoverflow is something you probably could easily answer on your own, if you stepped through your code with a debugger. That'd save you time - and us.

Edited:

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Also, you open 'test.txt' without verifying or setting the "current working directory". This will work only if you start the application from the same path, test.txt is in. But if you run the app from someplace else, the working directory may be different.

---

You did not check for eof or any other error condition. How do you know if opening the file did actually work? Or reading the number? Or that there are exactly the amount of numbers you are expecting.

Checking error conditions may seem like a nuisance, but it's definitely not. Hunting for errors, which you did not check in your code, is much more time consuming than forming a habit to check for errors.

Here is some code:

   ifstream FileIn;
   FileIn.open("test.txt");
   if (!FileIn.good())
      cerr << "Could not open file...";
   else {
      while (!FileIn.eof()) {
         int num; ///!!! DONT make `num` a global variable
         FileIn >> num;
         if (FileIn.bad()) {
            cerr << "Invalid number in file...";
            return 1; // return prematurely from the application
         }
         // Do something with the number
      }
   }

Also, use cout << endl instead of cout << '\n';. endl is the official way of inserting a line break and it will work on any platform, whereas '\n' may or may not work. Some platforms require two characters.