C ++初始化变量并使用std :: cin进行赋值

Question

This might be a bit stupid question, but I have failed to find any kind of answer for it anywhere else. I am writing codes in C++ (atleast 11 I think) and have to use:

int N;
cin >> N;  

My question is if there is an elegant way to write it as a one line of command? I already know that I can just remove the linebreaks and just put them on one line, but that wouldn't let me use it in a oneliner loop:

for(int i=0; i<10; i++) myVector.push_back();

Answer 1

Apart from writing a function, you can put initialization and reading into the header of the for loop:

for (int i = 0, n ; i != 5 && cin >> n ; i++)
    x.push_back(n);

This also addresses the problem of having to check the return value of cin >> n to ensure that a value has been read properly.

Demo.

Answer 2

An other alternative using algorithms and iterators:

std::copy_n(std::istream_iterator<int>{std::cin}
           ,10
           ,std::back_insert_iterator<std::vector<int>>{myVector});

Answer 3

I don't think that your approach is the "best" one, you're pushing back positions (that's so expensive) on a vector and you already know the positions the vector have. Why don't you just do this:

myVector.resize(10);
for (int i = 0; i < 10; i++) cin >> myVector [i];

But, if you can't because you want to use push_back() , why don't you just open the braces and write the code inside? What's the matter with that?