Line Drawing using DDA Algorithm

To learn about how this program is work read the DDA Algorithm.

#include <stdio.h>
#include <graphics.h>
#include <math.h>
int main()
{
    int gd = DETECT, gm;
    // gd=graphics driver (detects best graphics driver and assigns it as default, gm=graphics

    int x1, y1, x2, y2, steps, k;
    float xincr, yincr, x, y, dx, dy;
    printf("enter x1,y1: ");
    scanf("%d%d", &x1, &y1);
    printf("enter x2,y2: ");
    scanf("%d%d", &x2, &y2);
    initgraph(&gd, &gm, ""); // initializes the graph dx=x2-x1;
    dy = y2 - y1;
    if (abs(dx) > abs(dy))
        steps = abs(dx);
    else
        steps = abs(dy);
    xincr = dx / steps;
    yincr = dy / steps;
    x = x1;
    y = y1;
    for (k = 1; k <= steps; k++)
    {
        delay(100); // for seeing the line drawing process slowly. x+=xincr;
        y += yincr;
        putpixel(round(x), round(y), WHITE);
    }
    outtextxy(200, 20, "Digital Differential Analyzer Algorithm (DDA)");
    // for printing text at desired screen location. outtextxy(x1+5,y1-5,"(x1,y1)");
    outtextxy(x2 + 5, y2 + 5, "(x2,y2)");
    getch();
    closegraph(); // closes the graph and comes back to previous graphic mode.
}

Output

enter x1,y1: 100 200
enter x2,y2: 300 400

After enter the value of (x1, y1) and (x2, y2)