Q:

How Can I Make This Open GL Program Rotate Without Terminating

So I have this OpenGL program that displays a cube using
gluLookAt(0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);

And it allows users to modify/rotate it along the x, y and z axis using input. Right now it looks it works pretty well, however, it terminates once the image is displayed according to the users input (on wether to rotate along the x, y or z axis).
How can I modify this program so you can rotate it without it terminating? As in, displaying only the first rotation during the first input.
Or to put it simply, how can I let the users rotae this cube along the x,y and z axis in real time?
//cube.cpp
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>
#include <iostream>
using namespace std;
void init(void) 
{
   glClearColor (0.0, 0.0, 0.0, 0.0);
   glShadeModel (GL_FLAT);
}
void display(void)
{
   glClear (GL_COLOR_BUFFER_BIT);
   glColor3f (1.0, 1.0, 1.0);
   glLoadIdentity ();             /* clear the matrix */
   /* viewing transformation  */
      /* Move about the x, y and z axis*/
   cout << "Type x, y or z to rotatate the cube about that respective axis by 5 degrees." << endl;
   char input;
   cin >> input;
   if (input == 'x')
   {
      gluLookAt (5.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
   }
   else if (input == 'y')
   {
      gluLookAt (0.0, 5.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
   }
   else if (input == 'z')
   {
      gluLookAt (0.0, 0.0, 10.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
   }
   else
   {
      gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
   }
     // gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
   glScalef (1.0, 2.0, 1.0);      /* modeling transformation */ 
   glutWireCube (1.0);
   glFlush ();
}
void reshape (int w, int h)
{
   glViewport (0, 0, (GLsizei) w, (GLsizei) h); 
   glMatrixMode (GL_PROJECTION);
   glLoadIdentity ();
   glFrustum (-1.0, 1.0, -1.0, 1.0, 1.5, 20.0);
   glMatrixMode (GL_MODELVIEW);
}
int main(int argc, char** argv)
{   
   glutInit(&argc, argv);
   glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
   glutInitWindowSize (500, 500); 
   glutInitWindowPosition (100, 100);
   glutCreateWindow (argv[0]);
   init ();
   glutDisplayFunc(display); 
   glutReshapeFunc(reshape);
   glutMainLoop();
   return 0;
}

A:

Use GLUT's keyboard handling instead of iostreams:
#include <GL/glut.h>

float rx = 0;
float ry = 0;
float rz = 0;
void display()
{
    glClearColor (0.0, 0.0, 0.0, 0.0);
    glClear (GL_COLOR_BUFFER_BIT);

    glMatrixMode (GL_PROJECTION);
    glLoadIdentity ();
    glFrustum (-1.0, 1.0, -1.0, 1.0, 1.5, 20.0);

    glMatrixMode (GL_MODELVIEW);
    glLoadIdentity ();
    glTranslatef( 0, 0, -3 );

    glColor3f (1.0, 1.0, 1.0);
    glScalef (1.0, 2.0, 1.0);
    glRotatef( -rx, 1, 0, 0 );
    glRotatef( -ry, 0, 1, 0 );
    glRotatef( -rz, 0, 0, 1 );
    glutWireCube (1.0);

    glutSwapBuffers();
}

void keyboard( unsigned char key, int x, int y )
{
    if( key == 'x' ) rx += 5;
    if( key == 'y' ) ry += 5;
    if( key == 'z' ) rz += 5;
}

void timer( int extra )
{
    // run display() every 16ms or so
    glutTimerFunc( 16, timer, 0 );
    glutPostRedisplay();
}

int main(int argc, char** argv)
{   
    glutInit(&argc, argv);
    glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGBA);
    glutInitWindowSize (500, 500); 
    glutCreateWindow(argv[0]);

    glShadeModel (GL_FLAT);

    glutDisplayFunc(display); 
    glutKeyboardFunc( keyboard );
    glutTimerFunc( 0, timer, 0 );
    glutMainLoop();
    return 0;
}

