SIMPLE OPENGL PROGRAM TO DRAW AN LINE

#include<GL/glut.h>
#include<stdlib.h>

const int screenWidth=640;
const int screenHeight=480;

void myInit()
{
     glClearColor(1.0,1.0,1.0,0.0);
     glColor3f(0.0,0.0,0.0);
     glPointSize(2.0);
     glMatrixMode(GL_PROJECTION);
     glLoadIdentity();
     gluOrtho2D(0.0,(GLdouble)screenWidth,0.0,(GLdouble)screenHeight);
     }
    
    
     void myDisplay()
     {
          glClear(GL_COLOR_BUFFER_BIT);
          glBegin(GL_LINES);
                            glVertex2i(10,10);
                            glVertex2i(100,100);
          glEnd();
          glFlush();
          }
         
          int main(int argc,char **argv)
          {
              glutInit(&argc,argv);
              glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
              glutInitWindowSize(screenWidth,screenHeight);
              glutCreateWindow("lines");
              glutDisplayFunc(myDisplay);
              myInit();
             
              glutMainLoop();
              }