Ejercicio del reloj

#include <stdio.h>
#include <time.h>
#include <iostream>
#include <cstdlib>

using namespace std;

void delay(unsigned int mseconds)
{
clock_t goal = mseconds + clock();
while (goal > clock());
}
int main()
{
    int h,m,s;
        for(h=0; h<24; h++)
        {
            for(m=0; m<60; m++)
            {
                for(s=0; s<60; s++)
                {
                    delay(  1000000  );
                    system("clear");
                    cout<<h<<" : "<< m<<" : "<<s<<endl;
                }
            }
        }
}