定义全局变量浪费时间

#include<iostream>

using namespace std;

double a=22;

int main()

{

    //double a=22;

    double a1=a;

    a1=7;

    //cout<<a<<endl;

    //int a1={0};

    cout<<a1<<endl;

    return 0;
}

7

Process returned 0 (0x0)   execution time : 3.734 s

Press any key to continue.

int main()

{

    double a=22;

    double a1=a;

    a1=7;

    //cout<<a<<endl;

    //int a1={0};

    cout<<a1<<endl;

    return 0;

}

7

Process returned 0 (0x0)   execution time : 0.752 s

Press any key to continue.

以上可以比较出来全局变量耗时