Solved

What's The Difference.....

Posted on 2004-09-07
3
238 Views
Last Modified: 2010-04-01
....between "std::string whatever;" and "string whatever;"?

Thanks,
Tony
0
Comment
Question by:fattumsdad
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
3 Comments
 
LVL 55

Assisted Solution

by:Jaime Olivares
Jaime Olivares earned 100 total points
ID: 12001814
a little difference:

both are refered to the same class from STL library, but first version specifies "namespace". Namespaces allows you to avoid homonime classes by separating in different "namespaces", but if you want to access a particular namespace frecuently you can use this sentence:

using namespace namespace_here;

So, to simplify the first version you must use:

using namespace std;   // put this at the beginning of your file
string whatever;

Alternatively:

std::string whatever;

If you write:

string whatever;

you will have an "unrecognized class name" because it is not in the "global" namespace.
0
 
LVL 55

Expert Comment

by:Jaime Olivares
ID: 12001832
Forgot to mention that "std" is the namespace name for STL library.
0
 
LVL 30

Accepted Solution

by:
Axter earned 25 total points
ID: 12002350
>>....between "std::string whatever;" and "string whatever;"?

Just to add to above comments, it's common practice to add using namespace std to your *.cpp file (implementation).

However, you should never put this in your header file.
In your header file you should always reference objects by full qualified name.

class foo
{
   std::string data;
};

The reason why you don't want to add using namespace std to your header is because any code that uses your header will get the namespace, and this can conflict with other code or other namespace.

So, it's ok to use using namespace std in your *.cpp file, but not OK for the header.
0

Featured Post

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

What is C++ STL?: STL stands for Standard Template Library and is a part of standard C++ libraries. It contains many useful data structures (containers) and algorithms, which can spare you a lot of the time. Today we will look at the STL Vector. …
This article will show you some of the more useful Standard Template Library (STL) algorithms through the use of working examples.  You will learn about how these algorithms fit into the STL architecture, how they work with STL containers, and why t…
The goal of the tutorial is to teach the user how to use functions in C++. The video will cover how to define functions, how to call functions and how to create functions prototypes. Microsoft Visual C++ 2010 Express will be used as a text editor an…
The viewer will learn additional member functions of the vector class. Specifically, the capacity and swap member functions will be introduced.

627 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question