The difftime function computes the difference between the two supplied time values timer0 and timer1.
double difftime( time_t timer1, time_t timer0 )
the elapsed time in seconds, from timer0 to timer1. The value returned is a double-precision floating-point number.
time_t start, finish;
double result, elapsed_time;
printf( "Multiplying 2 floating point numbers 100 thousand times...\n" );
time( &start );
for( loop = 0; loop < 100000; loop++ )
result = 3.63 * 5.27;
time( &finish );
elapsed_time = difftime( finish, start );
printf( "\nProgram takes %6.0f seconds.\n", elapsed_time );