DDA Line Implementation

/* DDA Line Implementation - Subhranath Chunder */

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

void lineDDA(int,int,int,int);
void setPixel(int,int);

void main()
{
int x1,y1,x2,y2;
int driver=DETECT,mode;

clrscr();
printf("Enter the co-ordinates of the first point (a b): ");
scanf("%d %d",&x1,&y1);
printf("Enter the co-ordinates of the second point (a b): ");
scanf("%d %d",&x2,&y2);
printf("<Press any key to continue>");
getch();

initgraph(&driver,&mode,"F:\\TC\\BGI");
lineDDA(x1,y1,x2,y2);
getch();
closegraph();
}

void lineDDA(int x1,int y1,int x2,int y2)
{
float m,x,y;
x=x1;
y=y1;
setPixel(x,y);
if(x1==x2)
{
   while(y!=y2)
   {
      if(y2-y1>0)
         ++y;
      else
         --y;
      setPixel(x,y);
   }
}
else
{
   m=(float)(y2-y1)/(x2-x1);
   if(m<=1 && m>=-1)
   {
      while(x!=x2)
      {
         if(x2-x1>0)
         {
            y=y+m;
            ++x;
         }
         else
         {
            y=y-m;
            --x;
         }
         setPixel(x,y);
      }
   }
   else
   {
      while(y!=y2)
      {
         if((y2-y1)>0)
         {
            x=x+(1/m);
            ++y;
         }
         else
         {
            x=x-(1/m);
            --y;
         }
         setPixel(x,y);
      }
   }
}
}

void setPixel(int x,int y)
{
putpixel(x,y,2);
}