displaying time_t values

[fabio <fabio@crearium.com>]

hello,

I would like to know how to display the full seconds and miliseconds 
transacurrent since 2 points in a program.

main()
{
    time_t t1_t2;
    (void)time(&t1);
    cpu_intensive_function();
    (void)time(&t2);
    printf("the full time spent in the process is:");
    // how should i display it ? ej: 51,56745 seconds ot 1024,04546 seconds

}

Thanks,

fabolo