putpixel function plots a pixel at location (x, y) of specified color.
Declaration: void putpixel(int x, int y, int color);
For example,if we want to draw a GREEN color pixel at (35, 45) then we will write putpixel(35, 35, GREEN); in our c program, putpixel function can be used to draw circles, lines and ellipses using various algorithms.
C programming code for putpixel
int gd = DETECT, gm;
initgraph(&gd, &gm, "C:\\TC\\BGI");
putpixel(25, 25, RED);
Output of this program will be a RED pixel on screen at (25, 25) . Try to spot that pixel with your eyes at left top portion of your computer screen.