C ++'\\ n'中断while循环

Question

I'm trying to write a program that will echo input chars to the screen using get() and put() until the user presses '\\n' '\\n' but it breaks with just one '\\n'. Thanks for your help.

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <cstdlib>
using namespace std;

int main()
{
    char ch1, ch2;
    do 
    {    
        cin.get(ch1);
        cout.put(ch1);
        cin.get(ch2);
        cout.put(ch2);
    } while ((ch1 != '\n') && (ch2 != '\n'));
}

Answer 1

You should use || instead of &&

int main()
{
char ch1, ch2;
do 
{    
cin.get(ch1);
cout.put(ch1);
cin.get(ch2);
cout.put(ch2);
} while ((ch1 != '\n') || (ch2 != '\n'));
}

Answer 2

You have turned your logic around.

} while ((ch1 != '\n') && (ch2 != '\n'));

your here saying which i don't have a '\\n' and and not have a '\\n' but you do have a '\\n' so the first part is false and then the second clause is irrelevant as C++ short-circuit evaluation of || && expressions.

ie.

false && something 

is always false.

Answer 3

Try using | | instead of &&.