跨平台C++毫秒计时——以Quick Sort算法为例子

#include <iostream>
#include <stdlib.h>

using namespace std;

void Qsort(int a[],int low,int high)
{
	if(low >= high) return;
	int first = low;
	int last = high;
	int key = a[first];
	while(first < last)
	{
		while(first < last && a[last] >= key) --last;
		a[first] = a[last];
		while(first < last && a[first] <= key) ++first;
		a[last] = a[first];
	}
	a[first] = key;
	Qsort(a, low, first - 1);
	Qsort(a, first + 1, high);
}

int main(int argc, char **argv)
{
	//命令行参数数量判断
	if (argc == 0) {
		cout << "Usage: quicksort N\n";
		return 0;
	}
	//命令行第2个参数转换为长整数
	long N = atoi(argv[1]);

	//随机化数
	srand( time(0) );

	//动态分配内存
	int *a;
	a = new int[N];    //C++
	for(long i = 0; i < N; i++)
		a[i] = rand();

	//计时
	clock_t t1 = clock();
	Qsort(a, 0, N-1);/*这里原文第三个参数要减1否则内存泄露*/
	clock_t t2 = clock();
	cout << (double)(t2 - t1) / CLOCKS_PER_SEC << "毫秒" << endl;
	/*//输出
	for(int i=0;i<sizeof(a)/sizeof(a[0]);i++)
	{
		cout<<a[i]<<"";
	}
	*/
	//释放申请的内存
	delete []a;  //C++
	return 0;
}