DDA algorithm :   Define the nodes, i.e end points in form of (x1,y1) and (x2,y2).  Calculate the distance between the two end points vertically and horizontally, i.e dx=|x1-x2| and dy=|y1-y2|.  Define new variable name ‘pixel’, and compare dx and dy values,  if dx > dy then  pixel=dx  else  pixel =dy.  dx=dx/pixel  and dy=dy/pixel  x=x1;  y=y1;  while (i<=pixel) compute the pixel and plot the pixel with x=x+dx and y=y+dy.     c program for dda algorithm :      #include <graphics.h> #include <stdio.h> #include <math.h>  int main( ) {     float x,y,x1,y1,x2,y2,dx,dy,pixel;     int i,gd,gm;      printf("Enter the value of x1 : ");     scanf("%f",&x1);     printf("Enter the value of y1 : ");     scanf("%f",&y1);     printf("Enter the value of x2 : ");     scanf("%f",&x2);     printf("Enter the value of y1 : ");     scanf("%f",&y2);      detectgraph(&gd,&gm);   ...