C++ 对容器的下标访问、C++11新特性访问以及迭代器访问速度对比

最新推荐文章于 2023-07-16 19:59:14 发布

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最新推荐文章于 2023-07-16 19:59:14 发布

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分类专栏： C++11 文章标签： C++ 速度

本文链接：https://blog.youkuaiyun.com/weixin_42907473/article/details/94405500

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结论：下标访问最快，其次到C++11新特性方式，最慢的是迭代器访问

贴代码：

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

int main()
{
    vector<int> pri(10000,1);

    time_t begin,end;
    double ret=0;
    begin = clock();
    for(auto iter=pri.begin();iter!=pri.end();iter++)
        *iter+1;
    end = clock();
    ret=double(end-begin);
    cout<<"1runtime:   "<<ret<<" "<<endl;

    ret = 0;
    begin = clock();
    for(auto iter=pri.begin();iter!=pri.end();iter++)
        *iter+1;
    end = clock();
    ret=double(end-begin);
    cout<<"2runtime:   "<<ret<<" "<<endl;

    ret = 0;
    begin = clock();
    for(int i=pri.size()-1;i>=0;i--)
        pri[i]+1;
    end = clock();
    ret=double(end-begin);
    cout<<"5runtime:   "<<ret<<" "<<endl;

    ret = 0;
    begin = clock();
    for(auto iter=pri.begin();iter!=pri.end();iter++)
        *iter+1;
    end = clock();
    ret=double(end-begin);
    cout<<"3runtime:   "<<ret<<" "<<endl;

    ret = 0;
    begin = clock();
    for(int i=pri.size()-1;i>=0;i--)
        pri[i]+1;
    end = clock();
    ret=double(end-begin);
    cout<<"6runtime:   "<<ret<<" "<<endl;

    ret = 0;
    begin = clock();
    for(auto iter=pri.begin();iter!=pri.end();iter++)
        *iter+1;
    end = clock();
    ret=double(end-begin);
    cout<<"4runtime:   "<<ret<<" "<<endl;

    ret = 0;
    begin = clock();
    for(int gg:pri)
        gg+1;
    end = clock();
    ret=double(end-begin);
    cout<<"6runtime:   "<<ret<<" "<<endl;

    ret = 0;
    begin = clock();
    for(int gg:pri)
        gg+1;
    end = clock();
    ret=double(end-begin);
    cout<<"7runtime:   "<<ret<<" "<<endl;
    return 0;
}

贴输出结果：

1runtime: 155
2runtime: 174
5runtime: 26
3runtime: 159
6runtime: 19
4runtime: 148
6runtime: 67
7runtime: 66

单一过程测试多次是因为cpu波动，希望测出稳定的结果