You get undefined behaviour - you need to check that the container contains something using empty() (which checks if the container is empty) before calling front().

You get undefined behaviour.

To get range checking use at(0). If this fails you get a `out_of_range` exception.

Yes, you can use &#39;at&#39; like Graham mentioned instead of using front.

But, at(0) is only available for some containers - vectors, deque and not for others - list, queue, stack. In these cases you&#39;ve to fall back on the safety of the &#39;empty&#39; check.

You&#39;ve always have to be sure your container is not empty before calling front() on this instance.
Calling empty() as a safe guard is good.

Of course, depending on your programm design, always having a non-empty container could be an invariant statement allowing you to prevent and save the call to empty() each time you call front(). (or at least in some part of your code?)

But as stated above, if you want to avoid undefinied behavior in your program, make it a strong invariant.

I need to get unmanaged Windows C++ clients to talk to a WCF service. C++ clients could be running on Win2000 and later. I have a control over both WCF service and which C++ API is being used. Since it&#39;s for a proprietary application, it is preferable to use Microsoft stuff where possible, definitely not GNU licensed APIs. Those of you who have it working, can you share a step-by-step process how to make it working?

I have researched following options so far:

- WWSAPI - not good, will not work on Win 2000 clients.
- ATL Server, used [following guide][1] as a reference. I followed the steps outlined (remove policy refs and flatten WSDL), however the resulting WSDL is still not usable by sproxy

Any more ideas? Please answer only if you actually have it working yourself.

***Edit1***: I apologize for anyone who I might have confused: what I was looking for was a way to call WCF service from client(s) where no .NET framework is installed, so using .NET-based helper library is not an option, it must be pure unmanaged C++

  [1]: http://icoder.wordpress.com/2007/07/25/consuming-a-wcf-service-with-an-unmanaged-c-client-with-credential-passing/

Create WCF service for unmanaged C++ clients

I am about to start a project (.NET) and need to decide between TFS and SVN.

I am more used to SVN(with tortoise client), CVS and VSS. Does TFS have all features available in SVN

Have any of you switched from SVN to TFS and found it worthwhile?&lt;br/&gt;
Also it looks like we may need Visual Studio if we need to work with TFS.

**[Edit]**&lt;br/&gt;
Money is not a consideration since we already have the licenses for TFS in place.
And I am more interested in the Source Control features of TFS vs SVN, of course other features list is also welcome.


TFS vs SVN

If `front()` returns a reference and the container is empty what do I get, an undefined reference? Does it mean I need to check `empty()` before each `front()`?


What do I get from front() of empty std container?

<p>If <code>front()</code> returns a reference and the container is empty what do I get, an undefined reference? Does it mean I need to check <code>empty()</code> before each <code>front()</code>?</p>


How do I generate random floats in C++?

I thought I could take the integer rand and divide it by something, would that be adequate enough?

Random float number generation

Consider the case of a templated function with variadic template arguments:

    template&lt;typename Tret, typename... T&gt; Tret func(const T&amp;... t);

Now, I have a tuple `t` of values. How do I call `func()` using the tuple values as arguments?
I&#39;ve read about the `bind()` function object, with `call()` function, and also the `apply()` function in different some now-obsolete documents. The GNU GCC 4.4 implementation seems to have a `call()` function in the `bind()` class, but there is very little documentation on the subject.

Some people suggest hand-written recursive hacks, but the true value of variadic template arguments is to be able to use them in cases like above.

Does anyone have a solution to is, or hint on where to read about it?

How do I expand a tuple into variadic template function&#39;s arguments?

In VC++ 2003, I could just save the source file as UTF-8 and all strings were used as is. In other words, the following code would print the strings as is to the console. If the source file was saved as UTF-8 then the output would be UTF-8.

    printf(&quot;Chinese (Traditional)&quot;);
    printf(&quot;中国語 (繁体)&quot;);
    printf(&quot;중국어 (번체)&quot;);
    printf(&quot;Chin&#234;s (Tradicional)&quot;);

I have saved the file in UTF-8 format with the UTF-8 BOM. However compiling with VC2008 results in:

    warning C4566: character represented by universal-character-name &#39;\uC911&#39; 
    cannot be represented in the current code page (932)
    warning C4566: character represented by universal-character-name &#39;\uAD6D&#39; 
    cannot be represented in the current code page (932)
    etc.

The characters causing these warnings are corrupted. The ones that do fit the locale (in this case 932 = Japanese) are converted to the locale encoding, i.e. Shift-JIS.

I cannot find a way to get VC++ 2008 to compile this for me. Note that it doesn&#39;t matter what locale I use in the source file. There doesn&#39;t appear to be a locale that says &quot;I know what I&#39;m doing, so don&#39;t f$%##ng change my string literals&quot;. In particular, the useless UTF-8 pseudo-locale doesn&#39;t work.

    #pragma setlocale(&quot;.65001&quot;) 
    =&gt; error C2175: &#39;.65001&#39; : invalid locale

Neither does &quot;C&quot;:

    #pragma setlocale(&quot;C&quot;) 
    =&gt; see warnings above (in particular locale is still 932)

It appears that VC2008 forces all characters into the specified (or default) locale, and that locale cannot be UTF-8. I do not want to change the file to use escape strings like &quot;\xbf\x11...&quot; because the same source is compiled using gcc which can quite happily deal with UTF-8 files.

Is there any way to specify that compilation of the source file should leave string literals untouched?

To ask it differently, what compile flags can I use to specify backward compatibility with VC2003 when compiling the source file. i.e. do not change the string literals, use them byte for byte as they are.

&lt;b&gt;Update&lt;/b&gt;

Thanks for the suggestions, but I want to avoid wchar. Since this app deals with strings in UTF-8 exclusively, using wchar would then require me to convert all strings back into UTF-8 which should be unnecessary. All input, output and internal processing is in UTF-8. It is a simple app that works fine as is on Linux and when compiled with VC2003. I want to be able to compile the same app with VC2008 and have it work. 

For this to happen, I need VC2008 to not try to convert it to my local machine&#39;s locale (Japanese, 932). I want VC2008 to be backward compatible with VC2003. I want a locale or compiler setting that says strings are used as is, essentially as opaque arrays of char, or as UTF-8. It looks like I might be stuck with VC2003 and gcc though, VC2008 is trying to be too smart in this instance.

How to create a UTF-8 string literal in Visual C++ 2008

    int fn();
    
    void whatever()
    {
        (void) fn();
    }

Is there any reason for casting an unused return value to void, or am I right in thinking it&#39;s a complete waste of time?



Why cast unused return values to void?

Regarding the C++ STL map, erasing by key:-

     size_type map::erase ( const key_type&amp; x );

Is it legal to erase a non-existing key? i.e. is the snippet below ok?

    map&lt;char,int&gt; mymap;
    mymap[&#39;c&#39;]=30;
    mymap.erase(&#39;c&#39;);
    mymap.erase(&#39;c&#39;);
    mymap.erase(&#39;D&#39;);

Cheers


C++ STL map::erase a non-existing key

I am using std::queue for implementing JobQueue class. ( Basically this class process each job in FIFO manner).
In one scenario, I want to clear the queue in one shot( delete all jobs from the queue).
I don&#39;t see any clear method available in std::queue class.

How do I efficiently implement the clear method for JobQueue class ?

I have one simple solution of popping in a loop but I am looking for better ways.


 
    //Clears the job queue
    void JobQueue ::clearJobs()
     {
      // I want to avoid pop in a loop
        while (!m_Queue.empty())
        {
            m_Queue.pop();
        }
    }





How do I clear the std::queue efficiently?

I have always wondered why you cannot use locally defined classes as predicates to STL algorithms. 

In the question: [Approaching STL algorithms, lambda, local classes and other approaches][1], BubbaT mentions says that &#39;*Since the C++ standard forbids local types to be used as arguments*&#39;

Example code:

    int main() {
       int array[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
       std::vector&lt;int&gt; v( array, array+10 );
    
       struct even : public std::unary_function&lt;int,bool&gt;
       {
          bool operator()( int x ) { return !( x % 2 ); }
       };
       std::remove_if( v.begin(), v.end(), even() ); // error
    }

Does anyone know where in the standard is the restriction? What is the rationale for disallowing local types?

  [1]: https://stackoverflow.com/questions/256557/approaching-stl-algorithms-lambda-local-classes-and-other-approaches

---
**EDIT**: Since C++11, it is legal to use a local type as a template argument.

Using local classes with STL algorithms

I have a `std::vector` with `n` elements. Now I need to pass a pointer to a vector that has the last `n-1` elements to a function.

For example, my `vector&lt;int&gt; foo` contains `(5,2,6,87,251)`. A function takes `vector&lt;int&gt;*` and I want to pass it a pointer to `(2,6,87,251)`.

Can I just (safely) take the iterator `++foo.begin()`, convert it to a pointer and pass that to the function? Or use `&amp;foo[1]`?

**UPDATE:** People suggest that I change my function to take an iterator rather than a pointer. That seems not possible in my situation, since the function I mentioned is the `find` function of `unordered_set&lt;std::vector*&gt;`. So in that case, is copying the `n-1` elements from `foo` into a new vector and calling `find` with a pointer to that the only option? Very inefficient! It&#39;s like Shlemiel the painter, especially since i have to query many subsets: the last `n-1`, then `n-2`, etc. elements and see if they are in the `unordered_set`.

Convert iterator to pointer?

As an extension to this question [Are `const_iterators` faster?][1], I have another question on `const_iterators`. How to remove constness of a `const_iterator`? 
Though iterators are generalised form of pointers but still `const_iterator` and `iterator`s are two different things. Hence, I  believe, I also cannot use `const_cast&lt;&gt;` to covert from `const_iterator` to `iterator`s.

One approach could be that you define an iterator which moves &#39;til the element to which `const_iterator` points. But this looks to be a linear time algorithm.

Any idea on what is the best way to achieve this?


  [1]: https://stackoverflow.com/questions/755347/are-constiterators-faster

Content Type	Original Author	Original Content on Stackoverflow
Question	jackhab	View Question on Stackoverflow
Solution 1 - C++	anon	View Answer on Stackoverflow
Solution 2 - C++	graham.reeds	View Answer on Stackoverflow
Solution 3 - C++	Arun R	View Answer on Stackoverflow
Solution 4 - C++	yves Baumes	View Answer on Stackoverflow
Solution 5 - C++	anil	View Answer on Stackoverflow

What do I get from front() of empty std container?

C++ Problem Overview

C++ Solutions

Solution 1 - C++

Solution 2 - C++

Solution 3 - C++

Solution 4 - C++

Solution 5 - C++

TFS vs SVN

Create WCF service for unmanaged C++ clients

Attributions