How to pause a loop in C/C++

Question

I am trying to make a screen for a car game and make the screen wait for a key to go into the next screen, thing is that with this code it changes colors too fast. I've already tried delay() and sleep() which haven't worked properly. Also, after hitting a key, it closes and doesn't wait for me to enter a key. I just want the title to blink between white and red until a key is hit, and get to know why it exits after hitting a key.

Here is my code:

#include <dos.h>
#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
    int gdriver = DETECT, gmode, errorcode;
    initgraph(&gdriver, &gmode, "C|\\BORLANDC\\BGI");
    outtextxy(250,280,"POINTER DRIVER 1.0");
    outtextxy(250,290,"LCCM 10070249");
    do
    {
        setcolor(WHITE);
        outtextxy(250,380,"PRESS ANY KEY TO CONTINUE");
        // delay(10); nothing works here :(
        setcolor(RED);
        outtextxy(250,380,"PRESS ANY KEY TO CONTINUE");
    } while(!kbhit());
    cleardevice();
    outtextxy(250,290,"HELLO"); //here it draws mega fast and then exits
    getch();
    closegraph();
    return 0;
}

If you used a better and more widely used api, like SDL or SFML, or even the Windows API, I could help you. — Benjamin Lindley, Mar 04 '12 at 06:27
I'm sorry (just said so in another comment) but the professor wanted ONLY to use borland C to make graphics, also I have medium experience in java and well in C just like 1 month experience — Luis Carlos Castillo, Mar 04 '12 at 06:37

score 1 · Accepted Answer · answered Mar 04 '12 at 06:18

Instead of using delay(10), maybe try using some sort of timer variable to do this. Try something like the following (a modification of your do-while loop):

unsigned flashTimer = 0;
unsigned flashInterval = 30; // Change this to vary flash speed
do
{
    if ( flashTimer > flashInterval )
        setcolor(RED);
    else
        setcolor(WHITE);

    outtextxy(250,380,"PRESS ANY KEY TO CONTINUE");

    ++flashTimer;
    if ( flashTimer > flashInterval * 2 )
        flashTimer = 0;

    // Remember to employ any required screen-sync routine here
} while(!kbhit());

howard · Answer 2 · 2012-03-04T06:49:31.977

0

kbhit() returns true if there's a character in the buffer, but doesn't remove the character before it returns. Once you reach the getch() line, it takes the first key that you pressed to break out of the while loop.

Possible solution: While it's a bit hacky, adding a getch() right after your while loop would probably fix it.

May I also suggest using ncurses instead of those Borland libraries?

edited Mar 04 '12 at 06:49

answered Mar 04 '12 at 06:18

howard

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We were supossed to be seeing Open GL but the close minded professor acted as a total *** and said that he would work with borland C, I'll try what you said – Luis Carlos Castillo Mar 04 '12 at 06:35

How to pause a loop in C/C++

2 Answers2