Test function running time

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Test function running time

Time is money, efficiency is life! The quality of the program depends to a certain extent on its execution efficiency.

This is a method I found on the Internet to test the execution time of a function through a function. This should be relatively primitive. Maybe the compiler has this function. But it is good to understand some things in depth. I think this is also the direction I want to work hard on.

demo

clock():捕捉从程序开始运行到clock()被调用时所耗费的时间。这个时间单位是clock tick，即“时钟打点”。
常数CLK_TCK:机器时钟每秒所走的时钟打点数。

program

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

using namespace std;

clock_t start, stop;//clock_t是clock()函数返回的变量类型
double duration;//记录函数运行时间，以秒为单位

void PrintN(int N) {
    
    
	//不在测试范围内的准备工作写在clock()调用之前
	void PrintN(int N) {
    
    
	if (N) {
    
    
		PrintN(N - 1);
		cout << N << endl;
	}
	return;
}

int main() {
    
    
	int N;
	cin >> N;

	start = clock();
	PrintN(N);
	stop = clock();
	duration = ((double)(stop - start)) / CLK_TCK;
	cout << duration << endl;

	/*其他不在测试范围的处理写在后面，例如输出duration*/
	return 0;
}

This is a recursive program. After testing, the recursive program is slightly slower than the normal loop, and when N is greater than or equal to 100000, the recursive program crashes and the stack overflows.

Therefore, although recursion has its advantages, you must be careful when choosing recursion.

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