coordinating objects on the screen - c++

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?