c++ string 和 strcmp效率比较测试

乡村农夫

已于 2023-06-30 09:15:26 修改

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文章标签： c++ 算法开发语言

于 2023-06-29 22:38:11 首次发布

本文链接：https://blog.youkuaiyun.com/qq_23114283/article/details/131465802

版权

结论：strcmp比string快成百上千倍。

代码：


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

using namespace std;

string str = "SA203";
string str2 = "SA203";
char c_str[32] = "SA203";
char c_str2[32] = "SA206";
int f()
{
	return strcmp(c_str, c_str2) == 0;
}

int f2()
{
	return str == str2;
}

int f3()
{
	return 1;
}

int main()
{
	int num = 10000000;

	int begin = clock();
	for (int i = 0; i < num; ++i)
	{
		f();
	}
	cout << "strcmp耗时：" << clock() - begin << endl;
	begin = clock();
	for (int i = 0; i < num; ++i)
	{
		f2();
	}
	cout << "string耗时" << clock() - begin << endl;
	begin = clock();
	for (int i = 0; i < num; ++i)
	{
		f3();
	}
	cout << "空函数耗时" << clock() - begin << endl;

	string i;
	cin >> i;
	return 0;
}

输出结果：

strcmp耗时：138
string耗时1234
空函数耗时168

测试代码2：


#include <string>
#include <time.h>
#include <iostream>
using namespace std;
string str = "SA203";
string str2 = "SA203";
char c_str[32] = "SA203";
char c_str2[32] = "SA206";

int main()
{
	int num = 10000000;

	int begin = clock();
	for (int i = 0; i < num; ++i)
	{
		strcmp(c_str, c_str2) == 0;
	}
	cout << "strcmp耗时: " << clock() - begin << endl;
	begin = clock();
	for (int i = 0; i < num; ++i)
	{
		strcmp(str.c_str(), str2.c_str()) == 0;
	}
	cout << "string strcmp耗时: " << clock() - begin << endl;
	begin = clock();
	for (int i = 0; i < num; ++i)
	{
		str == str2;
	}
	cout << "string耗时: " << clock() - begin << endl;
	begin = clock();
	for (int i = 0; i < num; ++i)
	{
	}
	cout << "空循环耗时: " << clock() - begin << endl;

	string i; cin >> i;
	return 0;
}

输出结果2：

strcmp耗时: 32
string strcmp耗时: 619
string耗时: 1085
空循环耗时: 17