CODEWITHSUNDEEP
c++
user2699451
user2699451

Reputation:

using cin.get() doubles output in code

So I am teaching myself C++ and I cant see what is wrong here:

code: 

// Arrays.cpp : Defines the entry point for the console application.

#include "stdafx.h"
#include <iostream>

int _tmain(int argc, _TCHAR* argv[])
{
    int i = 0;
    char input = ' ';

    for(i = 1; i <= 100; ++i)
    {
        std::cout << "enter a value for element number " << i << ": " ;
        do
        {
            input = std::cin.get();
            std::cout << "recorded element in position " << i << " is " << input << "\n"; 
        } while (!input == 'q') ;
    }
}

problem:

line 17: input std::cin.get();

It gives me this: It asks for input, then records it and automatically completes element 2 for me

enter a value for element number 1: 5 recorded element in position 1
is 5 enter a value for element number 2: recorded element in position
2 is

enter a value for element number 3:

But when I replace it with std::cin >> input it doesn't, why?

Upvotes: 0

Views: 78

Answers (1)

Dietmar K&#252;hl
Dietmar K&#252;hl

Reputation: 154035

It seems you entered a newline: when you use the return key, you'll get another character ('\n') which is also obtained from std::cin.get(). The member std::istream::get() is an unformatted input function which doesn't attempt to skip whitespace before trying to read whatever if tries to read.

On the other hand, when using formatted input, e.g., std::cin >> input the stream will skip all leading whitespace before trying to read something. That is, the newline you also entered is skipped.

You can use (std::cin >> std::ws).get() to have leading whitespace consumed before using get(). ... and the other way around, you can set up the stream not skip leading whitespace automatically for formatted input using std::cin >> std::noskipws (and reverse this setting again using std::cin >> std::skipws). In general it isn't advisable to not skip leading whitespace for formatted input, though.

Upvotes: 4

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