I have to match up airlines for flights in c++, but for certain matchups, the value would be equal to x. I need help to do it.

Here's the code I have so far:

#include <iostream>
using namespace std;

int main()
{

    int nROWS = 4;
    int nCOLUMNS = 4;
    int anArray[4][4] = {{0,1,2,3}, {10,11,12,13}, {20,21,22,23}, {30,31,32,33}};
    string headings[4] = {"LA", "CLT", "SVO", "FR"};
     
    cout << headings[4]<<endl;
    
    for (int ROWS = 0; ROWS < nROWS; ROWS++)
    {
        cout << headings[ROWS]<<endl;
        for (int COLUMNS = 0; COLUMNS < nCOLUMNS; COLUMNS++){
            cout << anArray[ROWS][COLUMNS] << endl;
            if (anArray[1][1] = 0)
               cout << "X";
            else
                cout << anArray[ROWS];
            if (anArray[2][1] = 10)
               cout << "X";
            else
                cout << anArray[ROWS];
            if (anArray[2][2] = 11)
               cout << "X";
            else
                cout << anArray[ROWS];
            if (anArray[3][3] = 22)
               cout << "X";
            else
                cout << anArray[ROWS];
            if (anArray[4][4] = 33)
               cout <<"X";
            else
                cout << anArray[ROWS];
            }
            }
     system("pause");
     return 0;
}

I have to match up airlines for flights in c++, but for certain matchups, the value would be equal to x. I need help to do it.

Here's the code I have so far:

#include <iostream>
using namespace std;

int main()
{

    int nROWS = 4;
    int nCOLUMNS = 4;
    int anArray[4][4] = {{0,1,2,3}, {10,11,12,13}, {20,21,22,23}, {30,31,32,33}};
    string headings[4] = {"LA", "CLT", "SVO", "FR"};
     
    cout << headings[4]<<endl;
    
    for (int ROWS = 0; ROWS < nROWS; ROWS++)
    {
        cout << headings[ROWS]<<endl;
        for (int COLUMNS = 0; COLUMNS < nCOLUMNS; COLUMNS++){
            cout << anArray[ROWS][COLUMNS] << endl;
            if (anArray[1][1] = 0)
               cout << "X";
            else
                cout << anArray[ROWS];
            if (anArray[2][1] = 10)
               cout << "X";
            else
                cout << anArray[ROWS];
            if (anArray[2][2] = 11)
               cout << "X";
            else
                cout << anArray[ROWS];
            if (anArray[3][3] = 22)
               cout << "X";
            else
                cout << anArray[ROWS];
            if (anArray[4][4] = 33)
               cout <<"X";
            else
                cout << anArray[ROWS];
            }
            }
     system("pause");
     return 0;
}

Well I'm not to sure what you are having troubles with (or really, even what this program is supposed to do) but you can start by replacing the assignment operator (=) with the comparison operator (==) in every if statement. What you are doing is assigning the various 'predetermined' points in the array rather than checking for equality.
ie if (anArray[4][4] = 33) should be if (anArray[4][4] == 33)

Using an assignment operator doesn't return any bool values to test in a comparitive statement, and corrupts the data in the array.

Also, in the very first line where you display the headings, you should use a loop to iterate the array and display them. You are trying to display a string that has not been declared (index of 4)! When you create an array like that, the index of the last member will always be 1 less than the 'total' initialized size. This is because 0 is counted (ie. header[0] to header[3] are valid, header[4] is not. saying cout << header[4] therefore makes no sense, and i'm suprised it doesn't produce a compiler error).

what the program is actually supposed to do is it is supposed to output a matrix and certain values in the array are supposed to be X.

Using header[4] won't give a compile error, but it'll make the code crash at runtime.

You should implement skatamatic's suggestions for changing your assignments (=) to comparisons (==) in your if statements, and also fix your array index accesses.
Then you can check your output to see how much it varies from what you expect.