C++ Program to implement Digital differential analyzer (DDA graphics algorithm)

In computer graphics, a digital differential analyzer (DDA) is hardware or software used for linear interpolation of variables over an interval between start and end point. DDAs are used for rasterization of lines, triangles and polygons. In its simplest implementation, the DDA algorithm interpolates values in interval by computing for each x_i the equations x_i = x_i−1+1/m, y_i = y_i−1 + m, where Δx = x_end − x_start and Δy = y_end − y_start and m = Δy/Δx

https://en.wikipedia.org/wiki/Digital_differential_analyzer_(graphics_algorithm)

Program

#include <iostream.h>
#include <conio.h>
#include <graphics.h>
#include <math.h>
#include <process.h>
void main()
{
float i,x1,x2,y1,y2,dx,dy,x,y,step,xinr,yinr;
int gd=DETECT,gm;
clrscr();
initgraph(&gd,&gm,"C:\\Tc\\BGI");
cout<<"Enter the values\n";
cin>>x1>>y1>>x2>>y2;
dx=x2-x1;
dy=y2-y1;
if(dx==0&&dy==0)
{
putpixel(x1,y1,15);
getch();
exit(0);
}
if(abs(dx)>=abs(dy))
step=abs(dx);
else
step=abs(dy);
xinr=dx⁄step;
yinr=dy⁄step;
x=x1;
y=y1;
for(i=1;i<=step;i++)
{
putpixel(x,y,15);
x=x+xinr;
y=y+yinr;
}
getch();
closegraph();
}