dda line drawing Program

#include "stdio.h"
#include "conio.h"
#include "graphics.h"
#include "math.h"
void dda (float x1,float y1,float x2,float y2)
{
    float delx,dely,length;
    int x,y,i;
    if (x1==x2 && y1==y2)
    {
        printf ("The line cannot be drawn");
        return;
    }
    else
    {
        delx = fabs (x2-x1);
        dely = fabs (y2-y1);
    }
    if (delx >= dely)
    {
        length = delx;
    }
    else
    {
        length = dely;
    }
    delx = (x2-x1)/length;
    dely = (y2-y1)/length;
    x = x1 + 0.5;
    y = x2 + 0.5;
    i=1;
    while (i <= length)
    {
        putpixel (x,y,14);
        x = x + delx;
        y = y + dely;
        i = i + 1;
    }
}
void main ()
{
    int gd,gm;
    float x1,y1,x2,y2;
    clrscr ();
    printf ("Enter the starting points: ");
    scanf ("%f%f",&x1,&y1);
    printf ("Enter the ending points: ");
    scanf ("%f%f",&x2,&y2);
    detectgraph (&gd,&gm);
    initgraph (&gd,&gm,"c:\\TC\\BGI");
    dda (x1,y1,x2,y2);
getch ();
closegraph ();
}

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