The header file graphics.h contains putpixel() function which plots a pixel at location (x, y) of specified color.
void putpixel(int x, int y, int color); where, (x, y) is the location at which pixel is to be put , and color specifies the color of the pixel.
Explanation : A RED color pixel at (50, 40) can be drawn by using putpixel(50, 40, RED). putpixel() function can be used to draw circles, lines and ellipses using various algorithms.
Below is the implementation of putpixel() function.