Check function execution time by calling clock()

clocktest.cpp

//  clocktest.cpp
//  ClockTest
//
//  Created by Angelo Stavrow on 10 July, 2012

#include <time.h>
#include "iostream"

using namespace std;

// Calculate the factorial of n recursively.
unsigned long long recursiveFactorial(int n) {
    // Define the base case.
    if (n == 1) {
        return n;
    }
    
    // To handle other cases, call self recursively.
    else {
        return (n * recursiveFactorial(n - 1));
    }
}

int main() {
    int n = 60;
    unsigned long long result;
    clock_t start, stop;
    
    // Mark the start time.
    start = clock();
    
    // Calculate the factorial of n;
    result = recursiveFactorial(n);
    
    // Mark the end time.
    stop = clock();
    
    // Output the result of the factorial and the elapsed time.
    cout << "The factorial of " << n << " is " << result << endl;
    cout << "The calculation took " << ((double) (stop - start) / CLOCKS_PER_SEC) << " seconds." << endl;
    
    return 0;
}