Thread: Getline messing up code

Just started in on Allain's book and rather frustratingly ran into issues despite following the book to the letter. I'm trying to wrap my head around how getline works.

The following piece of code compiles and runs fine.

Code:

#include <iostream>
#include <string>


int main()


{
    std::string user_first_name = "test";
    
    std::cout << user_first_name << "\n";
    
    return 0;
}

But on the other hand this code, while it appears to compile, does nothing. It doesn't even print "test". Note getline @ 11. What am I missing? Thanks

Code:

#include <iostream>
#include <string>


int main()


{
    std::string user_first_name = "test";

     std::getline( std::cin, user_first_name, '\n' );
    
    std::cout << user_first_name << "\n";
    
    return 0;
}

Code was edited to reflect that Elkvis first suggestion still doesn't run on my end.

getline is in the std namespace, just like cin, and cout. you're not giving it a namespace qualification, and you have no using statement, so it fails to find it.

what operating system version and compiler version are you running?

I'm on OS X 10.9, using XCode 5.0.2. When I run the code the usual output box doesn't show anything. Although debugger reports using 276 KB of memory, it ends up filling up the space with bars.

is it possible that osx only supports unicode? what if you try using std::wstring, std::cout, and std::cin, and prefix all your string literals with a capital 'L'?

Sorry do you mind a bit of hand holding here? What would be an example of a string literal in my code where I should stick in the 'L'? Although the compiler did complain when I tried 'std::wstring'.

Finally XCode appears to give me the option to change the Text Encoding...if not Unicode (UTF-8), what should I change it to? (Allain doesn't make any mention of this in the Mac set up section).

Thanks for the help.

change the code in your first example to:

Code:

#include <iostream>
#include <string>


int main()


{
    std::wstring user_first_name = L"test";
    
    std::wcout << user_first_name << L"\n";
    
    return 0;
}

and your second to:

Code:

#include <iostream>
#include <string>


int main()


{
    std::wstring user_first_name = L"test";

     std::getline( std::wcin, user_first_name, L'\n' );
    
    std::wcout << user_first_name << L"\n";
    
    return 0;
}

Originally Posted by jocdrew21

drop the std:: when you use getline, you only need it for std::cin

wrong. getline is still in the std namespace. in the absence of a using directive, you must qualify it with the namespace name.

Thanks to both of you, jocdrew21 and Elkvis. Problem solved.

I was the boob in this case...

Should I look into the wstring, wcout, etc for more info or is that a somewhat complex concept I can tackle later?

Also interestingly, code still compiled and worked with and without std:: for 'getline' and without declaring a namespace or a using directive.

Originally Posted by jaxdid

Should I look into the wstring, wcout, etc for more info or is that a somewhat complex concept I can tackle later?

the w-prefixed version of cin, cout, string, etc. are useful for handling strings that contain unicode characters that cannot be represented with ascii.

Also interestingly, code still compiled and worked with and without std:: for 'getline' and without declaring a namespace or a using directive.

it's possible that the version of GCC that comes with xcode implicitly says "using std::getline;" when you compile your code. try other stuff without the std:: and see what happens.

Apart from whiteflags said, while it is not necessary to add std:: to getline, you should consider it good practice to do so anyway.