字符串全排列+sizeof(T)大小验证

void output(string res,string left)
{   
    if(left.empty())
    {   
        cout<<res<<endl;
        return;
    }
    size_t size=left.size();
    for(size_t i=0;i<size;i++)
    {   
        string res1=res,left1=left;
        res1+=left1[i];
        if(i==size-1)
        {   
            left1=left1.substr(0,i);
        }
        else
        {   
            left1=left1.substr(0,i)+left1.substr(i+1);
        }
        output(res1,left1);
    }
 
}
int main()
{
    //1////////////////////
    std::cout<<"int:"<<sizeof(int)<<std::endl;
    std::cout<<"int*:"<<sizeof(int*)<<std::endl;
    std::cout<<"long:"<<sizeof(long)<<std::endl;
    std::cout<<"long*:"<<sizeof(long*)<<std::endl;
    std::cout<<"char:"<<sizeof(char)<<std::endl;
    std::cout<<"char*:"<<sizeof(char*)<<std::endl;
    std::cout<<"short int:"<<sizeof(short int)<<std::endl;
    //2///////////////////
    const int a=1;
    //a=2;
    const int& b=a;
    //b=3;
    std::cout<<b;
    //3////////////////////////////
    string aa="abcd",bb;
    output(bb,aa);

    return 0;
}