(C++)1 dimensional battleship game help? advice for improvement

Question

Unfortunately I do not have the Instructor to aid me with this assignment over the weekend and I am stuck. I'm just learning C++ and I've taken a Logic and Design class for Programming but like I said I'm very new to C++. I'm having a hard time catching up to the rest of the students.

I'd like if someone could list improvements and maybe clarify if I've done anything wrong in comparison to the assignment statement. I do really appreciate the help!

My code is repetitive and I'm sure I could go another way into displaying the array values without all that code. An error also pops up after use of the application that says:

"Run-Time Check Failure #2 - Stack around the variable 'enemy' was corrupted.

If there is a handler for this exception, the program may be safely continued."

The assignment is:

"Create a Battleship struct containing 5 one-dimensional integer coordinates representing its location within a region (of any size). Instantiate 2 copies of the struct and have the user enter a single coordinate for each Battleship. Design your code to take this single coordinate and use it to populate the remaining 4 coordinates for each ship. Do this for both ship structs. Then, have your code calculate the numeric distance between the 2 ships based on their respective coordinates. Finally, display the resulting distance to the user with an English language sentence."

My code as for right now is :

#include <iostream>
#include <string>

using namespace std;

struct Ship
{
    int x[5];
    int y[5];
};

int main()
{
    Ship good;
    Ship enemy;

    good.x[0] = 0;
    enemy.y[0] = 0;

    cout << "Enter a coordinate (out of 100) for good ship: "<< endl;
    cin >> good.x[0];

    good.x[1] = good.x[0] + 1;
    good.x[2] = good.x[1] + 1;
    good.x[3] = good.x[2] + 1;
    good.x[4] = good.x[3] + 1;

    cout << "Good ship coordinates:" << endl;
    cout << good.x[0]<< "*" << endl;
    cout << good.x[1]<< endl;
    cout << good.x[2]<< endl;
    cout << good.x[3]<< endl;
    cout << good.x[4]<< endl;

    cout << "Enter a coordinate (out of 100) for enemy ship: "<< endl;
    cin >> enemy.y[0];

    enemy.y[1] = enemy.y[0] + 1;
    enemy.y[2] = enemy.y[1] + 1;
    enemy.y[3] = enemy.y[2] + 1;
    enemy.y[4] = enemy.y[3] + 1;

    cout << "enemy ship coordinates:" << endl;
    cout << enemy.y[0]<< "*" << endl;
    cout << enemy.y[1]<< endl;
    cout << enemy.y[2]<< endl;
    cout << enemy.y[3]<< endl;
    cout << enemy.y[4]<< endl;

    int distance=0;
    distance = good.x[1] - enemy.y[1];

    cout << "The distance between good ship and enemy ship is: " << distance << endl; 

    system("pause");
    return 0;
}

Answer 1

The error probably comes from having only 4 coordinates in each struct, not 5. When you declare an array with int x[4];, it will only have 4 elements, namely x[0] to x[3].

There are a number of other problems:

1. You do not need two structs for two ships. Use just one. That's the whole point of structs/classes: to represents classes of objects. Use only one struct (named e.g. Ship) and declare both your ships good and enemy to have that type.

2. Don't be afraid of both the enemy ship and the good ship having x coordinates. The compiler and the computer won't get confused at that, and neither should you.

3. Learn to use loops. Even if you get confused at first, remember that loops are one of the most (if not the most) important tools at a programmers disposal. Think what would happen if you had 100 ships, each with 100 coordinates...

4. Remember, again, that the first element of an array is at index 0, not index 1. (And the last element is at index N-1.)

5. Calculating the distance is a little more complex than you've written. Can the distance between two objects ever be negative? What happens if the enemy ship's coordinate is greater than the friendly ship? What's the actual formula for one-dimensional distances?

6. Remove unused code. What's the use of that region variable? Have you used it anywhere?

UPDATE: (For anyone reading in the future, remember that OP has updated and modified their question and code, to the point that some of my point would not apply or would apply differently.)

7. Do you REALLY need both xs and ys in Ship?

Answer 2

Not sure if the use of system("PAUSE") is something your instructor taught, but that's definitely something you could improve on, too. Explained here

Answer 3

So starting with

Create a Battleship struct containing 5 one-dimensional integer coordinates representing its location within a region (of any size). Instantiate 2 copies of the struct and have the user enter a single coordinate for each Battleship

You need a single struct:

struct Ship
{
    int x[5];
};

Now make 2 copies

int main()
{
    Ship good;
    Ship bad;
    ...

Then the rest looks good, it compiles and runs without any issues on my computer. You can add a function to populate the ship to reduce the number of code

Ship createShip(int startPos) {
    Ship newShip;
    newShip[0] = startPos;
    // ... <- rest of your code that you have to populate
    return newShip;
}

int main() 
{ 
    int pos;
    cout << "Enter a coordinate (out of 100) for good ship: "<< endl;
    cin >> pos;
    Ship good = createShip(pos);
    //... 
    //... <- Get pos of bad ship
    Ship bad = createShip(pos); 
 }

Then you can also create a simular function that prints the location of the ship