Tips: Application of clock() function

 

Run time of comparison function

 

#include<iostream>
#include<time.h>
using namespace std;

clock_t strat, stop;
double duration;

double f1(int n, double a[], double x) {
	int i;
	double p = a[0];
	for (i = 1; i <= n; i++)
		p += (a[i] * pow(x, 1));
	return p;
}

double f2(int n, double a[], double x) {
	int i;
	double p = a[n];
	for (i = n; i > 0; i--)
		p = a[i - 1] + x * p;
	return p;
}

void main() {
	int i, n = 10000;
	double a[10];
	for (i = 0; i < 10; i++)
		a[i] = (double)i;

	strat = clock();
	for (i = 0; i < n; i++)
		f1(10, a, 1.1);
	stop = clock();
	duration = ((double)(stop - strat)) / CLK_TCK;
	cout << "ticks1 = " << (double)(stop - strat) << endl;
	cout << "duation1 = " << duration << endl;

	strat = clock();
	for (i = 0; i < n; i++)
		f2(10, a, 1.1);
	stop = clock();
	duration = ((double)(stop - strat)) / CLK_TCK;
	cout << "ticks2 = " << (double)(stop - strat) << endl;
	cout << "duation2 = " << duration << endl;
}