- As you&#39;ve mentioned, namespace works for anything, not just for functions and objects.
- As Greg has pointed out, `static` means too many things already.
- Namespaces provide a uniform and consistent way of controlling visibility at the global scope. You don&#39;t have to use different tools for the same thing.
- When using an anonymous namespace, the function/object name will get mangled properly, which allows you to see something like &quot;(anonymous namespace)::xyz&quot; in the symbol table after de-mangling, and not just &quot;xyz&quot; with static linkage.
- As pointed out in the comments below, it isn&#39;t allowed to use static things as template arguments, while with anonymous namespaces it&#39;s fine.
- More? Probably, but I can&#39;t think of anything else right now.

One reason may be that `static` already has too many meanings (I can count at least three). Since an anonymous namespace can encapsulate anything including types, it seems superior to the `static` solution.

There are two reasons I think:

 - `static` has two different meanings: at class scope, it means shared by the whole class while at file/function scope it affects the visibility/storage...
 - unnamed namespaces allow to declare new `struct`, `class` and `typedef`

One note though, the commitee backpedaled on this: `static` is no longer marked as deprecated in `n3225`.

How can I set a DateTime to the first of the month in C#?

set DateTime to start of month

How can I loop through all the properties of object?. Right now I have to write a new code line to print each property of object

    echo $obj-&gt;name;
    echo $obj-&gt;age;

Can I loop through all the properties of an object using foreach loop or any loop?

Something like this

    foreach ($obj as $property =&gt; $value)  

Looping through all the properties of object php

The section $7.3.1.1/2 from the C++ Standard reads:

&gt; The use of the static keyword is
&gt; deprecated when declaring objects in a
&gt; namespace scope; the unnamed-namespace
&gt; provides **a superior alternative.**

I don&#39;t understand why an unnamed namespace is considered a superior alternative? What is the rationale? I&#39;ve known for a long time as to what the standard says, but I&#39;ve never seriously thought about it, even when I was replying to this question: https://stackoverflow.com/questions/4422507/superiority-of-unnamed-namespace-over-static

Is it considered superior because it can be applied to user-defined types as well, as I described in my [answer][1]? Or is there some other reason as well, that I&#39;m unaware of? I&#39;m asking this, particularly because that is my reasoning in my answer, while the standard might have something else in mind.

[1]:https://stackoverflow.com/questions/4422507/superiority-of-unnamed-namespace-over-static/4422554#4422554

Why an unnamed namespace is a &quot;superior&quot; alternative to static?

The section $7.3.1.1/2 from the C++ Standard reads:
> The use of the static keyword is
> deprecated when declaring objects in a
> namespace scope; the unnamed-namespace
> provides a superior alternative.
I don't understand why an unnamed namespace is considered a superior alternative? What is the rationale? I've known for a long time as to what the standard says, but I've never seriously thought about it, even when I was replying to this question: <a href="https://stackoverflow.com/questions/4422507/superiority-of-unnamed-namespace-over-static" target="_blank" rel="noopener noreferrer">https://stackoverflow.com/questions/4422507/superiority-of-unnamed-namespace-over-static</a>
Is it considered superior because it can be applied to user-defined types as well, as I described in my <a href="https://stackoverflow.com/questions/4422507/superiority-of-unnamed-namespace-over-static/4422554#4422554" target="_blank" rel="noopener noreferrer">answer</a>? Or is there some other reason as well, that I'm unaware of? I'm asking this, particularly because that is my reasoning in my answer, while the standard might have something else in mind.

What&#39;s the best way to delete an std::string from memory allocated on the heap when I&#39;m done using it? Thanks!

How to properly free a std::string from memory

When I compile a very simple source file with gcc I don&#39;t have to specify the path to standard include files such as stdio or stdlib.

How does GCC know how to find these files?

Does it have the `/usr/include` path hardwired inside, or it will get the paths from other OS components?

What are the GCC default include directories?

I know that `std::cout` is the C++ equivalent of `printf`.

What is the C++ equivalent of `sprintf`?

C++ equivalent of sprintf?

I am reading Scott Meyers &quot;Effective C++&quot; book. It was mentioned that there are `tr1::shared_ptr` and `tr1::weak_ptr` act like built-in pointers, but they keep track of how many `tr1::shared_ptrs` point to an object.  

This is known as reference counting. This works well in preventing resource leaks in acyclic data structures, but if two or more objects contain `tr1::shared_ptrs` such that a cycle is formed, the cycle may keep each other&#39;s reference count above zero, even when all external pointers to the cycle have been destroyed.  

That&#39;s where `tr1::weak_ptrs` come in.

My question is how cyclic data structures make the reference count above zero. I kindly request an example C++ program. How is the problem solved by `weak_ptrs`? (again, with example please).

shared_ptr and weak_ptr differences

Coming from other C-derived languages (like Java or C#) to C++, it is at first very confusing that C++ has three ways to refer to members of a class: `a::b`, `a.b`, and `a-&gt;b`. When do I use which one of these operators? 

&lt;sub&gt;
_(Note: This is meant to be an entry to [Stack Overflow&#39;s C++ FAQ](https://stackoverflow.com/questions/tagged/c++-faq). If you want to critique the idea of providing an FAQ in this form, then [the posting on meta that started all this](https://meta.stackexchange.com/questions/68647/setting-up-a-faq-for-the-c-tag) would be the place to do that. Answers to that question are monitored in the [C++ chatroom](https://chat.stackoverflow.com/rooms/10/c-lounge), where the FAQ idea started out in the first place, so your answer is very likely to get read by those who came up with the idea.)_
&lt;/sub&gt;


When do I use a dot, arrow, or double colon to refer to members of a class in C++?

How to create xml document with node prefix like:

    &lt;sphinx:docset&gt;
      &lt;sphinx:schema&gt;
        &lt;sphinx:field name=&quot;subject&quot;/&gt;
        &lt;sphinx:field name=&quot;content&quot;/&gt;
        &lt;sphinx:attr name=&quot;published&quot; type=&quot;timestamp&quot;/&gt;
     &lt;/sphinx:schema&gt;
   &lt;/sphinx:docset&gt;

When I try to run something like `new XElement(&quot;sphinx:docset&quot;)` i getting exception 

&gt; Unhandled Exception: System.Xml.XmlException: The &#39;:&#39; character, hexadecimal val
ue 0x3A, cannot be included in a name.  
   at System.Xml.XmlConvert.VerifyNCName(String name, ExceptionType exceptionTyp
e)  
   at System.Xml.Linq.XName..ctor(XNamespace ns, String localName)  
   at System.Xml.Linq.XNamespace.GetName(String localName)  
   at System.Xml.Linq.XName.Get(String expandedName)

XElement namespaces (How to?)

I was reading through the source of [Artifice][1] and saw:

    module Artifice
      NET_HTTP = ::Net::HTTP
      # ...
    end

line: https://github.com/wycats/artifice/blob/master/lib/artifice.rb#L6

Why not just do `Net::HTTP` instead of `::Net::HTTP`, i.e., what does it mean when you use `::` as a prefix?

  [1]: https://github.com/wycats/artifice

Ruby: what does :: prefix do?

I am using a library that defines output stream operators (operator&lt;&lt;) in the global namespace. In my own namespace, I was always declaring such operators in the global namespace, and never had problems with them. But now for various reasons I need to declare those operators in my own namespace, and suddenly, the compiler can&#39;t seem to find the operators declared in the library anymore.

Here&#39;s a simple example that illustrates my problem: 

    #include &lt;iostream&gt;
    
    namespace A
    {
       struct MyClass {};
    }
    
    std::ostream &amp; operator&lt;&lt;( std::ostream &amp; os, const A::MyClass &amp; )
       { os &lt;&lt; &quot;namespace A&quot;; return os; }
    
    namespace B
    {
       struct MyClass {};

       std::ostream &amp; operator&lt;&lt;( std::ostream &amp; os, const B::MyClass &amp; )
          { os &lt;&lt; &quot;namespace B&quot;; return os; }
    }

    namespace B
    {
       void Test()
       {
          std::cout &lt;&lt; A::MyClass() &lt;&lt; std::endl;
          std::cout &lt;&lt; B::MyClass() &lt;&lt; std::endl;
       }
    }
    
    int main()
    {
       B::Test();
       return 1;
    }

I am getting the following error:

    error: no match for ‘operator&lt;&lt;’ in ‘std::cout &lt;&lt; A::MyClass()’

Note that if both operators are within the namespaces, or alternatively if they are both in the global namespace, the code compiles and executes correctly.

I&#39;d really like to understand what&#39;s going on and also what the &quot;good practice&quot; for defining such operators with namespaces.

Thanks! 

Namespaces and operator resolution

&gt; **Possible Duplicate:**  
&gt; [Unnamed/anonymous namespaces vs. static functions](https://stackoverflow.com/questions/154469/unnamed-anonymous-namespaces-vs-static-functions)  

&lt;!-- End of automatically inserted text --&gt;

I came across this code 

    namespace ABC {
    namespace DEF {
    
    namespace
    {

I expected the namespace should be followed by some name, but it&#39;s not the case with this code.

Is this allowed in C++? What&#39;s the advantage for this unnamed namespace? 

Namespace without a name in C++

Can PHP namespaces contain variables? If so, how can this be accomplished?

Can PHP namespaces contain variables?

Is it okay to use an anchor tag without including the `href` attribute, and instead using a JavaScript click event handler? So I would omit the `href` completely, not even have it empty (`href=&quot;&quot;`).


Is an anchor tag without the href attribute safe?

[w3fools][1] claims that URLs can contain spaces: http://w3fools.com/#html_urlencode

Is this true? How can a URL contain an un-encoded space?

I&#39;m under the impression the [request line of an HTTP Request][2] uses a space as a delimiter, being formatted as `{the method}{space}{the path}{space}{the protocol}`:

    GET /index.html http/1.1

Therefore how can a URL contain a space? If it can, where did the practice of replacing spaces with `+` come from?


  [1]: http://w3fools.com
  [2]: http://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Request_message

Spaces in URLs?

Does it depend on the platform you are using, or is there a common convention that most developers suggest/follow?

There are several options:

1. `id=&quot;someIdentifier&quot;&#39;` - looks pretty consistent with javascript code. 
2. `id=&quot;some-identifier&quot;` - looks more like html5-like attributes and other things in html.
3. `id=&quot;some_identifier&quot;` - looks pretty consistent with ruby code and is still a valid identifier inside of Javascript

I was thinking #1 and #3 above make the most sense because they play nicer with Javascript.

Is there a right answer to this?

What is the standard naming convention for html/css ids and classes?

[Attribute quotes are **optional** in HTML5](https://dev.w3.org/html5/spec-LC/syntax.html#unquoted).

What are the pros/cons to quoting them?

    id=example                     &lt;!--quotes optional--&gt;
    href=http://example.com        &lt;!--quotes optional--&gt;
    class=&quot;example example-1&quot;      &lt;!--quotes required due to space--&gt;
    href=&quot;http://example.com/p=47&quot; &lt;!--quotes required due to &#39;=&#39; sign--&gt;

Update: Added advantages based on the answers:

Advantages to quoting all attributes:

- all editors can deal with it properly
- more consistent
- better portability (easier to change doctype)
- easier to maintain (esp. if attributes might become empty)
- easier to &#39;find and replace&#39; changes
- cleaner doc (if you think quotes improve readability)
- ?

Advantages to **omitting** optional quotes:

 - slightly reduced filesize
 - cleaner doc (if you prefer minimal text)
 - ?


Do you quote HTML5 attributes?

Outside of the argument of whether or not NULLs should ever be used: I am responsible for an existing database that uses NULL to mean &quot;missing or never entered&quot; data.  It is different from empty string, which means &quot;a user set this value, and they selected &#39;empty&#39;.&quot;

Another contractor on the project is firmly on the &quot;NULLs do not exist for me; I never use NULL and nobody else should, either&quot; side of the argument.  However, what confuses me is that since the contractor&#39;s team DOES acknowledge the difference between &quot;missing/never entered&quot; and &quot;intentionally empty or indicated by the user as unknown,&quot; they use a single character &#39;Z&#39; throughout their code and stored procedures to represent &quot;missing/never entered&quot; with the same meaning as NULL throughout the rest of the database.

Although our shared customer has asked for this to be changed, and I have supported this request, the team cites this as &quot;standard practice&quot; among DBAs far more advanced than I; they are reluctant to change to use NULLs based on my ignorant request alone.  So, can anyone help me overcome my ignorance?  Is there any standard, or small group of individuals, or even a single loud voice among SQL experts which advocates the use of &#39;Z&#39; in place of NULL?

Update
-

I have a response from the contractor to add.  Here&#39;s what he said when the customer asked for the special values to be removed to allow NULL in columns with no data:

&gt; _Basically, I designed the database to avoid NULLs whenever possible.  Here is the rationale:_
&gt;  
&gt; • _A NULL in a string [VARCHAR] field is never necessary because an empty (zero-length) string furnishes exactly the same information._
&gt;
&gt;•  _A NULL in an integer field (e.g., an ID value) can be handled by using a value that would never occur in the data (e.g, -1 for an integer IDENTITY field)._ 
&gt;
&gt;•  _A NULL in a date field can easily cause complications in date calculations.  For example, in logic that computes date differences, such as the difference in days between a [RecoveryDate] and an [OnsetDate], the logic will blow up if one or both dates are NULL -- unless an explicit allowance is made for both dates being NULL.  That&#39;s extra work and extra handling.  If &quot;default&quot; or &quot;placeholder&quot; dates are used for [RecoveryDate] and [OnsetDate] (e.g., &quot;1/1/1900&quot;) , mathematical calculations might show &quot;unusual&quot; values -- but date logic will not blow up._
&gt;     
&gt;_NULL handling has traditionally been an area where developers make mistakes in stored procedures._ 
&gt;
&gt;_In my 15 years as a DBA, I&#39;ve found it best to avoid NULLs wherever possible._

This seems to validate the mostly negative reaction to this question.  Instead of applying an accepted 6NF approach to designing out NULLs, special values are used to &quot;avoid NULLs wherever possible.&quot;  I posted this question with an open mind, and I am glad I learned more about the &quot;NULLs are useful / NULLs are evil&quot; debate, but I am now quite comfortable labeling the &#39;special values&#39; approach to be complete nonsense.

&gt; an empty (zero-length) string furnishes exactly the same information. 

No, it doesn&#39;t; in the existing database we are modifying, NULL means &quot;never entered&quot; and empty string means &quot;entered as empty&quot;.
&gt;NULL handling has traditionally been an area where developers make mistakes in stored procedures.

Yes, but those mistakes have been made thousands of times by thousands of developers, and the lessons and caveats for avoiding those mistakes are known and documented.  As has been mentioned here: whether you accept or reject NULLs, representation of missing values is a _solved problem_.  There is no need to invent a new solution just because developers continue make easy-to-overcome (and easy-to-identify) mistakes.

---
_As a footnote: I have been a DBE and developer for more than 20 years (which is certainly enough time for me to know the difference beetween a database engineer and a database administrator).  Throughout my career I have always been in the &quot;NULLs are useful&quot; camp, though I was aware that several very smart people disagreed.  I was extremely skeptical about the &quot;special values&quot; approach, but not well-versed enough in the academics of &quot;How To Avoid NULL the Right Way&quot; to make a firm stand.  I always love learning new things—and I still have lots to learn after 20 years.  Thanks to all who contributed to make this a useful discussion._

Standard use of &#39;Z&#39; instead of NULL to represent missing data?

&gt; **Possible Duplicate:**  
&gt; [What’s the best way to find the inverse of datetime.isocalendar()?](https://stackoverflow.com/questions/304256/whats-the-best-way-to-find-the-inverse-of-datetime-isocalendar)  

&lt;!-- End of automatically inserted text --&gt;

I have an ISO 8601 year and week number, and I need to translate this to the date of the first day in that week (Monday). How can I do this?

[datetime.strptime()][1] takes both a `%W` and a `%U` directive, but neither adheres to the ISO 8601 weekday rules that [datetime.isocalendar()][2] use.

**Update:** [Python 3.6][3] supports the `%G`, `%V` and `%u` directives also present in libc, allowing this one-liner:


    &gt;&gt;&gt; datetime.strptime(&#39;2011 22 1&#39;, &#39;%G %V %u&#39;)
    datetime.datetime(2011, 5, 30, 0, 0)


**Update 2**: [Python 3.8][4] added the `fromisocalendar()` method, which is even more intuitive:

    &gt;&gt;&gt; datetime.fromisocalendar(2011, 22, 1)
    datetime.datetime(2011, 5, 30, 0, 0)


  [1]: http://docs.python.org/library/datetime.html#strftime-strptime-behavior
  [2]: http://docs.python.org/library/datetime.html#datetime.datetime.isocalendar
  [3]: https://docs.python.org/3.6/whatsnew/3.6.html#datetime
  [4]: https://docs.python.org/3/library/datetime.html#datetime.date.fromisocalendar

Get date from ISO week number in Python

Can I convert iso date to milliseconds?
for example I want to convert this iso 

    2012-02-10T13:19:11+0000

to milliseconds.

Because I want to compare current date from the created date. And created date is an iso date.



convert iso date to milliseconds in javascript

I&#39;m wondering if the following date is ISO8601 compliant :

    2012-03-02 14:57:05.456+0500

(for sure, 2012-03-02T14:57:05.456+0500 is compliant, but not that much human readable !)
IOW, is the T between date and time mandatory ?

In an ISO 8601 date, is the T character mandatory?

I have googled (well, DuckDuckGo&#39;ed, actually) till I&#39;m blue in the face, but cannot find a list of language codes of the type `en-GB` or `fr-CA` anywhere.

There are excellent resources about the components, in particular the [W3C I18n page](http://www.w3.org/International/articles/language-tags/#region), but I was hoping for a simple alphabetical listing, fairly canonical if possible (something like [this one](http://www.iana.org/assignments/language-subtag-registry)). Cannot find.

Can anyone point me in the right direction? Many thanks!

Where can I find a list of language + region codes?

Is there a way to extract month and day using isoformats? Lets assume today&#39;s date is March 8, 2013.

    &gt;&gt;&gt; d = datetime.date.today()
    &gt;&gt;&gt; d.month
    3
    &gt;&gt;&gt; d.day
    8

I want:

    &gt;&gt;&gt; d = datetime.date.today()
    &gt;&gt;&gt; d.month
    03
    &gt;&gt;&gt; d.day
    08

I can do this by writing if statements and concatenating a leading 0 in case the day or month is a single digit but was wondering whether there was an automatic way of generating what I want.

Content Type	Original Author	Original Content on Stackoverflow
Question	Nawaz	View Question on Stackoverflow
Solution 1 - C++	Sergei Tachenov	View Answer on Stackoverflow
Solution 2 - C++	Greg Hewgill	View Answer on Stackoverflow
Solution 3 - C++	Matthieu M.	View Answer on Stackoverflow

Why an unnamed namespace is a "superior" alternative to static?

C++ Problem Overview

C++ Solutions

Solution 1 - C++

Solution 2 - C++

Solution 3 - C++

Looping through all the properties of object php

set DateTime to start of month

Attributions