Limiting the number of characters of user input

问题

I'm trying to limit # of characters a user can input.
It's not like when user inputs abcde, and I limit the input length to be 3,
and only abc is taken into account.

Is there a way to physically limit user from inputting more than certain amount of characters?
For example, if user trys to type 12345, and if I limit it to 3 characters, only 123 gets typed.

I've tried the following code:

cin.width(5);
cin >> n;

But I've realized it doesn't physically limit the user input, but only limits the buffersize of input.

Is there a way to do something like this?

+) I'm working on Console Application

回答1:

You can't do it in a standard console window but if you use c++ to make your own window with your own input box then you have some more flexibility.

回答2:

You could do some weird thing like reading individual characters one at a time, and if they don't hit return by the 4th character, say invalid input and then make them start over, but it's cleaner and easier to just call long input invalid after they try to submit it.

回答3:

You may be searching for this:--

#include <iostream>
#include <string>

using namespace std;

int main()
{
    string MyInput;
    std::cout << "INPUT HERE: ";
    std::getline(cin,MyInput);
    if (MyInput.length() == 3)
    {
        std::cout << "OKAY IT IS THREE CHARS" << std::endl;
    }
    else if (!(MyInput.length() == 3))
    {
        MyInput.erase(MyInput.begin()+3,MyInput.end());
        std::cout << "Look: " << MyInput << std::endl;
    }
}

来源：https://stackoverflow.com/questions/17181594/limiting-the-number-of-characters-of-user-input