coordinating objects on the screen

Question

So I want to display an object with certain coordinates on the screen and make it able to move. If for example "u" is pressed it goes up and etc. So I tried using variables X and Y (initialized to 0) and after a "clear screen" deploying the object with a for loop. So check this out:

#include <iostream>
#include <conio.h>
#include <cstdlib>
#include <vector>
#include <iomanip>
using namespace std;
char input;
char player = 1;
char keyup = 0x48, keydown = 0x50, keyright = 0x4d, keyleft = 0x4b;
int x = 0, y = 0;
void position()
{
    for (int start = 0; start <= y; start++)
    {
        cout << "\n";
    }
    for (int start = 0; start <= x; start++)
    {
        cout << " ";
    }
    cout << player;
}
void moveup()
{
    x - 1;
    system("cls");
    position();
}
void movedown()
{
    y + 1;
    system("cls");
    position();
}
void moveright()
{
    x + 1;
    system("cls");
    position();
}
void moveleft()
{
    y - 1;
    system("cls");
    position();
}
int main()
{
    while (1)
    {
        position();
        cin >> input;
        if (input == keyup) moveup();
        if (input == keydown) movedown();
        if (input == keyright) moveright();
        if (input == keyleft) moveleft();
        system("cls");
    }
}

So when I run it it just shows me the cube for ASCII key = 1; And no matter what I press it just blinks showing me the 'player' on the same position. Can you guys tell me what is the PROBLEM?

Answer 1

At first, I recomment using character literals instead of numerical values:

char const keyup = 'u';
//    ^ they are constants, aren't they???

0 is not a printable character, so using it as symbol won't print anything on the screen... You might use e. g. '+' instead.

Then you are repeating pretty much code within your functions. What you actually need is just one printing function; something like:

void update()
{
    system("cls");
    for(int i = 0; i < y; ++i)
        std::cout << '\n'; // navigate to appropriate line

    for(int i = 0; i < x; ++i)
        std::cout << ' '; // navigate to column

    std::cout << symbol << std::endl; // endl flashes buffer, too
}

You can use this to print the the symbol to current position (x/y). On input you just need to modify the coordinates (I personally recommend a switch statement instead of the if/else chain):

std::cin >> input;
switch(input)
{
case keyup: // NEEDS to be a constant to be used that way!
    --y;
    break;
case keydown:
    ++y;
    break;
case keyleft:
    --x;
    break;
case keyright:
    ++x;
    break;
default: // catch invalid user input
    // if you have, appropriate error handling – or just ignore
    break;      
}

An empty default could be left out – it's a good habit, though, always to catch the invalid cases.

Finally: The second clearing of the screen (after your if/else chain) would empty the screen again before user might have seen anything. Just leave it out. All combined:

for(;;)
{
    update(); // first screen update and returning here in every loop
    std::cin >> input;
    switch(input)
    {
    // ...
    case ExitKey: // recommend to add it!
        // the only disadvantage of switch: cannot use 'break' to exit loop!
        goto LOOP_END;
    default:
        break;
    }
}
LOOP_END:
// clean up application
return 0; // exit main...

One thing I yet omitted above, but very important: range checks! Before incrementing or decrementing one of the coordinates, you need to check if you can at all:

if(x > 0)
    --x;

Or a variant I personally like:

y += y < SCREEN_HEIGHT; // needs to be defined appropriately...

About screen size: this might be of interest...

Answer 2

So the improved code would look like this:

#include <iostream>
#include <conio.h>
#include <cstdlib>
#include <vector>
#include <iomanip>
using namespace std;
char input;
char player = 1;
const char keyup = 'u', keydown = 'd', keyright = 'r', keyleft = 'l', Exitkey = 'k';
int x = 0, y = 0;
void space()
{
    for (int start = 0; start < 7; start++)
    {
        cout << "\n";
    }
}
void update()
{
    system("cls");
    for (int i = 0; i < y; ++i)
    cout << '\n'; 

    for (int i = 0; i < x; ++i)
    cout << ' ';
    cout << player << endl;
}
void inputfunc()
{
    cin >> input; 
    switch (input)
    {
    case keyup:
        if (y = 0)
        {
            y = 0;
        }
        else --y;
        goto endloop;
    case keydown:
        ++y;
        goto endloop;
    case keyleft:
        if (x = 0)
        {
            x = 0;
        }
        else --x;
        goto endloop;
    case keyright:
        ++x;
        goto endloop;
    case Exitkey:
        goto endloop;
    default:
        break;
    }
endloop:;
}
int main()
{
    for (;;)
    {
        update();
        space();
        inputfunc();
    }
}

And one more thing: I do not know how to make it automatically after entering ONE character go on. I need to enter as many characters as I want and then press ENTER to deploy the player.How can I do that Scheff?