Is there a better way to do string input in C++ via standard input?

This is my little piece of code. I'm a little rusty, so I don't remember
how to do this 100%. But basically, the below example will allow to
enter a string up to 100 chars, output it and just for kicks, turn it into
a string class object.

It works, but it can be improved on.

Now, my question is this, would there be a way that would liberate me
from the C character array?

Code:

#include <iostream>#include <ios>
#include <limits>


using namespace std;


int main(int argc, char * argv[])
{
    char testString[100];
    std::cout << "Please enter a string: ";
    std::cin.getline(testString, 100);


    cout << "This is the string that you entered: " << testString << std::endl << std::endl;
    std::string simpleString(testString);


    std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
    std::cin.get();


    return 0;
}

I tried this example (all the way at the bottom) in my VC++ 2010 and
when I typed in getline, my IDE told me the following:

Error: no instance of 'getline' matches the argument list

:-/

there is the wonderful string object

Originally Posted by rogster001

there is the wonderful string object

I know... but you can't do std::cin >> stringObjectVariable. I did that as my first guess.

oops sorry wasnt reading your question right! - but you can? c++ ref website code below I never considered it before like:

Code:

// cin with strings
#include <iostream>
#include <string>
using namespace std;

int main ()
{
	string mystr;
	cout << "What's your name? ";
	getline (cin, mystr);
	cout << "Hello " << mystr << ".\n";
	cout << "What is your favorite team? ";
	getline (cin, mystr);
	cout << "I like " << mystr << " too!\n";
	return 0;
}

Originally Posted by rogster001

oops sorry wasnt reading your question right! - but you can? c++ ref website code below I never considered it before like:

Code:

// cin with strings
#include <iostream>
#include <string>
using namespace std;

int main ()
{
    string mystr;
    cout << "What's your name? ";
    getline (cin, mystr);
    cout << "Hello " << mystr << ".\n";
    cout << "What is your favorite team? ";
    getline (cin, mystr);
    cout << "I like " << mystr << " too!\n";
    return 0;
}

Yup, and I tried that very example that I listed in VC++ 2010 and I got the following error:

Error: no instance of 'getline' matches the argument list

you can also do this:

Code:

#include <iostream>
#include <string>

int main()
{
  std::string s;
  std::cin >> s;

  return 0;
}

the standard defines the std::istream >> operator for std::string. see this link.

Originally Posted by Elkvis

you can also do this:

Code:

#include <iostream>
#include <string>

int main()
{
  std::string s;
  std::cin >> s;

  return 0;
}

the standard defines the std::istream >> operator for std::string. see this link.

Thanks.

I swear I tried this and VS said that I was doing something wrong. Probably made a stupid
mistake and thought that it could not be done. Will need to pay closer attention in the
future.

keep in mind that the >> operator likes to stop reading when it encounters white space. if you need to accept data that contains white space, you will need to use std::getline.

Am I missing something? What is wrong with getline() with the std::string instead of using the C-string version of getline()?

Jim

Originally Posted by jimblumberg

Am I missing something? What is wrong with getline() with the std::string instead of using the C-string version of getline()?

Jim

How weird. This is what I tried in Visual Studio:

Code:

/**
 * hello-world.cpp:
 */
#include <iostream>
#include <ios>
#include <limits>
#include <string>
#include <sstream>


int main(int argc, char * argv[])
{
    std::string stuff;
    std::cout << "Please enter a string: ";
    std::getline(std::cin, stuff, 100);
    std::cout << "The stuff: " << stuff << std::endl << std::endl;

    std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
    std::cin.get();

    return 0;
}

And the errors that I got:

Code:

1>------ Build started: Project: hello-world, Configuration: Debug Win32 ------1>  hello-world.cpp
1>c:\documents\visual studio 2010\projects\hello-world\hello-world\hello-world.cpp(34): error C2780: 'std::basic_istream<_Elem,_Traits> &std::getline(std::basic_istream<_Elem,_Traits> &,std::basic_string<_Elem,_Traits,_Alloc> &)' : expects 2 arguments - 3 provided
1>          c:\program files\microsoft visual studio 10.0\vc\include\string(479) : see declaration of 'std::getline'
1>c:\documents\visual studio 2010\projects\hello-world\hello-world\hello-world.cpp(34): error C2782: 'std::basic_istream<_Elem,_Traits> &std::getline(std::basic_istream<_Elem,_Traits> &,std::basic_string<_Elem,_Traits,_Alloc> &,const _Elem)' : template parameter '_Elem' is ambiguous
1>          c:\program files\microsoft visual studio 10.0\vc\include\string(468) : see declaration of 'std::getline'
1>          could be 'int'
1>          or       'char'
1>c:\documents\visual studio 2010\projects\hello-world\hello-world\hello-world.cpp(34): error C2780: 'std::basic_istream<_Elem,_Traits> &std::getline(std::basic_istream<_Elem,_Traits> &&,std::basic_string<_Elem,_Traits,_Alloc> &)' : expects 2 arguments - 3 provided
1>          c:\program files\microsoft visual studio 10.0\vc\include\string(448) : see declaration of 'std::getline'
1>c:\documents\visual studio 2010\projects\hello-world\hello-world\hello-world.cpp(34): error C2782: 'std::basic_istream<_Elem,_Traits> &std::getline(std::basic_istream<_Elem,_Traits> &&,std::basic_string<_Elem,_Traits,_Alloc> &,const _Elem)' : template parameter '_Elem' is ambiguous
1>          c:\program files\microsoft visual studio 10.0\vc\include\string(395) : see declaration of 'std::getline'
1>          could be 'int'
1>          or       'char'
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

This... should work...

Maybe my VS install is borked.

[edit]

I tried the above code in GCC 4.5.3 (in cygwin), these are the errors that I got:

Code:

hello-world.cpp: In function ‘int main(int, char**)’:
hello-world.cpp:14:38: error: no matching function for call to ‘getline(std::istream&, std::string&, int)’

No you're using the wrong getline() there are two versions of getline() one for std::string and one for C-strings. You need to use the proper version depending upon you're using a C-string or std::string.

You must also get the parameters correct. The std::string getline() doesn't use a "size" parameter.

Jim

Oooooh, I see where I went wrong. Gotcha. Thank you.