Keep looping until user enters a blank line? - c++

Question

So I've run into the following problem. My goal is to create a loop that keeps taking user input over and over until the user doesn't enter anything into 'cin >>', leaves the line blank, and simply presses the ENTER key to move on, at which point the program is supposed to break out of the loop and continue on with the rest of program execution. Something like this:
do {
cout << "\nEnter a name: ";
cin >> input1;
if (input1.empty())
{
break;
}
else
{
user_name = input1;
}
} while (!input1.empty());
As you can see, I've already tried using the empty() function, but that didn't work, the program simply stays in the loop and doesn't break out, no matter how many times I press enter. It just keeps prompting me to enter a name. I've also tried using something like
if (input1 == "")
but that doesnt work either. Can anyone help? How do I break out of this loop?
UPDATE: OK guys, I've tried your recommendations, and it worked! Thank you so much! Unfortunately, although the getline function works, it has also created a new problem for me. Basically, in the first initial loop, the program prompts for a name, I type in a name, and the name is stored in user_name. However, in the SECOND loop, the program doesn't even give me the chance to enter any input, it simply prints "Enter a name: ", and then instantly exits out of the loop, and continues on with the rest of program execution. Why is this happening?

Answer 1

Use this getline(std::cin, input1):
while (getline(std::cin, input1))
{
if (input1.empty())
break;
username =input1;
std::cout << input1 << std::endl << "Enter Input : ";
}

Answer 2

Use std::getline(cin, input1); instead to read a line from the console.
Using cin directly reads exactly one word from stdin. If the user does not input anything, no word has been given and cin does not return yet (your empty check is not even executed).
After you use std::getline you can leave your empty-check as-is:
std::getline(cin, input1);
if(input1.empty())
break;
BTW: In C++ you should also check if the underlying stream has run into an error. So check the return code of cin or getline. This can be done with the following code:
if(!std::getline(cin, input1))
// I/O error

Answer 3

In general, looping until an empty line is entered would be:
while ( std::getline( line ) && !line.empty() ) ...
If you need a prompt: the prompt is part of the input logic, and
should be implemented as such:
std::string
getlineWithPrompt( std::string const& prompt )
{
std::cout << prompt;
std::string results;
return std::getline( std::cin, results )
? results
: std::string();
}
You then do something like:
std::string line = getlineWithPrompt( "prompt for first line" );
while ( !line.empty() ) {
// ...
getlineWithPrompt( "prompt for further line" );
}
(This is actually somewhat simplified, as it treats hard errors
on input, end of file, and empty lines identical, which is
rarely the right thing in professional software. But for
learning purposes, it should be sufficient.)

Answer 4

Cin won't read the whitespace that you call an empty line. Getline may do this, but I am not entirely sure. You could define an end character that the user would type and check for that. Gets would also work, it will just set the starting character to 0x0. Be careful with gets(), it is prone to allow buffer overflows.

Answer 5

This works as well:
char line[128];
do
{
cout << "Enter something: ";
gets(line);
} while (strcmp(&line[0], "\0") != 0);

Answer 6

#JamesKanze
So something like this to exit the while loop?
string str = "foo";
while (str == "foo"){
getline(cin, str);
}
str = "foo";