Moving a printed character

Hi all,

Is there a function in Visual C++ which will allow me to move a letter or number I have printed on the screen left and right, for example, if I start with '0' printed in the top centre of the screen, is there any way in which I can use the left arrow key to move it to the left?

Thanks.

EDIT - Failing this, how can I destroy what I previously wrote on the screen to replace it with something new, so that I don't get loads of zeros on the screen?

Is there a function to delete a char?

I've never done anything like this so I dont know exactly what APIs may exist. I know there is "ncurses" which is for creating nice text-based interfaces, and I imagine that has capability of doing what you want ("moving" characters, etc). However, I dont think this is available for Windows. You can try searching for a Windows port or similar library for Windows.

Alternatively, you can simulate a move by printing a character at position X, clearing the screen, and printing the character again at position (X+1). Search around on MSDN and for examples.
- clear screen: How To Performing Clear Screen (CLS) in a Console Application and How to clear the Console window with Visual C++ .NET or Visual C++ 2005
- set cursor position to print: SetConsoleCursorPosition Function (Windows)
- etc, etc.

If you refresh the screen very often, you'll probably notice a "flickering", so you may want to investigate a different method.

Thanks for the info - could I use the gotoxy () function to move the cursor position and then print a character with it?

Try this (its commented so it will explain itself!):

Code:

---

/* Load Libraries */
#include <conio.h>
#include <windows.h>
#include <stdio.h>

/* Declare Goto Function */
void gotoxy(int, int);

/* Init X and Y plus the Variables which hold
 previous X and Y. */
int x, y, lastx, lasty;

/* Make a CHAR variable to get Key Input */
char a;

/* Main Function */
int main()
{
 /* Give a value to all integer variables we declared */
 x = 1; y = 1;
 lastx = x; lasty = y;
 
 /* start an Infinite Loop */
 while(1 == 1)
 {
 /* Head to LastX and LastY and clear old O*/
 gotoxy(lastx, lasty);
 printf(" ");
 /* Draw New O */
 gotoxy(x,y);
 printf("O");
 /* Get Input */
 a = getch();
 /* Remember Old X and Y */
 lastx = x; lasty = y;
/* If Down Arrow is Pressed, Y is increased */
 if (a == 80) y = y + 1;
/* If Up Arrow is Pressed, Y is decreased */
 if (a == 72) y = y - 1;
/* If Right Arrow is Pressed, X is increased */
 if (a == 77) x = x + 1;
/* If Left Arrow is Pressed, X is decreased */
 if (a == 75) x = x - 1;
 }
}

/* Make GOTOXY function */
void gotoxy(int eex, int eey)
{
  COORD coord;
  coord.X = eex;
  coord.Y = eey;
  SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), coord);
}

---

Great - it works - thanks.

I have another question - how do I get a character to appear at a random coordinate every time I start the program?
Which operator do I use?

Thanks.

EDIT - Let me rephrase:

How do I get a character to appear at pre-defined co-ordinates, for example, X and Y?

updated Code, (this code will explain itself as well).

Code:

---

/* Load Libraries */
#include <conio.h>
#include <windows.h>
#include <stdio.h>
#include <time.h>

/* Declare Goto Function */
void gotoxy(int, int);

/* Init X and Y plus the Variables which hold
 previous X and Y. */
int x, y, lastx, lasty;

/* Make a CHAR variable to get Key Input */
char a;

/* Main Function */
int main()
{
 /* if we dont use SRAND, RAND returns the same number over and over */
 srand((unsigned) time(NULL));
 /* a typical Console screen is 80x40, since a Console Screen is
    made of only text. 80 is the number of columns and 40 is the
    number of rows. so we randomize X and Y in those areas */

 x = (rand() % 80) + 1; y = (rand() % 40) + 1;
 /* Store the previous X and Y */
 lastx = x; lasty = y;
 
 /* start an Infinite Loop */
 while(1 == 1)
 {
 /* Head to LastX and LastY and clear old O*/
 gotoxy(lastx, lasty);
 printf(" ");
 /* Draw New O */
 gotoxy(x,y);
 printf("O");
 /* Get Input */
 a = getch();
 /* Remember Old X and Y */
 lastx = x; lasty = y;
/* If Down Arrow is Pressed, Y is increased */
 if (a == 80) y = y + 1;
/* If Up Arrow is Pressed, Y is decreased */
 if (a == 72) y = y - 1;
/* If Right Arrow is Pressed, X is increased */
 if (a == 77) x = x + 1;
/* If Left Arrow is Pressed, X is decreased */
 if (a == 75) x = x - 1;
 }
}

/* Make GOTOXY function */
void gotoxy(int eex, int eey)
{
  COORD coord;
  coord.X = eex;
  coord.Y = eey;
  SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), coord);
}

---

Thanks for the help. Is there a way to make a timer run alongside the program, for example, to time 10 seconds and then display a message? i can get a timer to run before the program starts, but not in parallel.

Thanks.

Quote:

---

Originally Posted by george7378

Thanks for the help. Is there a way to make a timer run alongside the program, for example, to time 10 seconds and then display a message? i can get a timer to run before the program starts, but not in parallel.

Thanks.

---

You could look at http://linux.die.net/man/3/timer_create for linux, or http://msdn.microsoft.com/en-us/libr...06(VS.85).aspx for Windows.

Thanks - is that for GUI based code, or for command based code - I am using command based.

I found this code:

Code:

---

void wait(double val)
{
        int i;

        for (i = 0; i <= val; i++)
        {
                continue;
        }
}

wait(4000000); //etc

---

Will it do what I need?

Quote:

---

Originally Posted by george7378

I found this code:

Code:

---

void wait(double val)
{
        int i;

        for (i = 0; i <= val; i++)
        {
                continue;
        }
}

wait(4000000); //etc

---

Will it do what I need?

---

The functions I provided will work in either a console or GUI application. Although, they will take quite a bit of research on your part to get working. I suggest you try and find examples or tutorials on them.

As for this function, absolutely not. Look what you're doing here. You've created a simple for loop that increments an integer a rediculous amount of times. The fact that the number is so large is the only reason you may get a pause; also keep in mind that this loop you've created is CPU-intensive, will block, and will also pause for a different amount of time on everyone's computer (depending on the computer's speed).
The fact that you asked for a timer that runs "parallel" with your program is why I offered you the timer options.

However, if all you want is a blocking call that will wait for a certain amount of time, I suggest you research sleep.

a loop is not good for delay. E.G if the function delays 5 seconds with your
processor, a faster computer will make the function to delay 2 seconds while
a slower one will make the function to delay 10 seconds. and so on. anyway,
here is a working alternative which delays the same no matter how much
fast your Pc is:

Code:

---

/* Load Libraries */
#include <conio.h>
#include <windows.h>
#include <stdio.h>
#include <time.h>
/* Load also Stdlib.h because it has the sleep function */
#include <stdlib.h>

/* Declare Goto Function */
void gotoxy(int, int);

/* Init X and Y plus the Variables which hold
 previous X and Y. */
int x, y, lastx, lasty;

/* Make a CHAR variable to get Key Input */
char a;

/* Main Function */
int main()
{
 /* type some message for the user */
 printf("My Moving Char program!\n\n");
 /* sleep waits in miliseconds, so 5 * 1000 = 5 seconds */
 sleep(5 * 1000);
 /* Clear the screen completely */
 system("cls");
 /* if we dont use SRAND, RAND returns the same number over and over */
 srand((unsigned) time(NULL));
 /* a typical Console screen is 80x40, since a Console Screen is
    made of only text. 80 is the number of columns and 40 is the
    number of rows. so we randomize X and Y in those areas */

 x = (rand() % 80) + 1; y = (rand() % 40) + 1;
 /* Store the previous X and Y */
 lastx = x; lasty = y;
 
 /* start an Infinite Loop */
 while(1 == 1)
 {
 /* Head to LastX and LastY and clear old O*/
 gotoxy(lastx, lasty);
 printf(" ");
 /* Draw New O */
 gotoxy(x,y);
 printf("O");
 /* Get Input */
 a = getch();
 /* Remember Old X and Y */
 lastx = x; lasty = y;
/* If Down Arrow is Pressed, Y is increased */
 if (a == 80) y = y + 1;
/* If Up Arrow is Pressed, Y is decreased */
 if (a == 72) y = y - 1;
/* If Right Arrow is Pressed, X is increased */
 if (a == 77) x = x + 1;
/* If Left Arrow is Pressed, X is decreased */
 if (a == 75) x = x - 1;
 }
}

/* Make GOTOXY function */
void gotoxy(int eex, int eey)
{
  COORD coord;
  coord.X = eex;
  coord.Y = eey;
  SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), coord);
}

---