From: Ross Litscher <Litscher DOT 1 AT osu DOT edu>
Newsgroups: comp.os.msdos.djgpp
Subject: compile warning
Date: Fri, 09 May 1997 19:00:38 -0400
Organization: The Ohio State University
Message-ID: <3373AC95.2D64@osu.edu>
Reply-To: Litscher DOT 1 AT osu DOT edu
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To: djgpp AT delorie DOT com
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Hi, I am kind of new to c++ and brand new to djgpp. I got about 98% of
the following code off the internet. The problem is that I get a warning
after I compile this. It is as follows:

vidmode2.cpp(30) Warning: implicit declaration of function 'int
rand(...)' 

The program still runs correctly and all, though. By the way, there is a
point in the program where I wanted the drawing to screen to slow down a
bit so I used a 'while' loop where a number increases by 1 until it
reaches a certain number. Could someone look at this and tell me if
there is a better way to do this? Or is this fine. Any other comments
would be greatly appreciated, I'm completely new at graphics
programming, too. Thanks. The source follows. 

#include <dos.h>
#include <sys/farptr.h>
#include <go32.h>
#include <conio.h>

#define GRAPHICS  0x013
#define TEXT      0x03

long video_buffer = 0xa0000;

void put_pixel(short int x, short int y, char color)
{
 _farpokeb(_dos_ds, video_buffer + (y << 8) + (y << 6) + x, color);
}

void set_video_mode(int mode)
{
 union REGS regs;		//what does this do? (union?)
 regs.x.ax = mode;
 int86(0x10, &regs, &regs);
}

void main(void)
{
 unsigned count;

 set_video_mode(GRAPHICS);
 for(count = 0; count < 32000; count++)
           {
            put_pixel(rand() % 320, rand() % 200, rand() %256);
            int wait=0;
            while(wait < 5000)		//just to slow down 
                       {		//the writting to
                        wait++;		//video memory
                       }
           }
 getch();
 set_video_mode(TEXT);

}


Thanks,
Ross