In C99 the available basic integer types (the ones without _t) were deemed insufficient, because their actual sizes may vary across different systems. 

So, the C99 standard includes definitions of several new integer types to enhance the portability of programs. The new types are especially useful in embedded environments.

All of the new types are suffixed with a _t and are guaranteed to be defined uniformly across all systems.

For more info see the [fixed-width integer types section of the wikipedia article on Stdint][1]. 


  [1]: http://en.wikipedia.org/wiki/Stdint.h#stdint.h

The main difference is that the `uintX_t` types are standard C defined by C99 and later while `UIntX` is not. This has implications for how portable the code is. Code using `uintX_t` types can be compiled on any standard C compiler without any other dependencies. Code that uses `UIntX` on the other hand, must either define those types itself, or depend on some library or framework that does so.

I don&#39;t think Objective-C as such defines any extra integer types, but it may well be that your framework (Coacoa, OpenStep?) does so. If your code makes no sense outside of the framework, use what&#39;s idiomatic in the framework context. Otherwise try to stick to the standard types.

normally they are used as a typedef datatypes. &quot;_t&quot; stand for a typedef datatype.
we give such name so that they can be used and read easily across all the file or huge code base.


*UInt8 and uint8_t - Char* 

**typedef unit8_t unsigned char**

*UInt16 and unit16_t*

**typedef unit16_t unsigned int** ( on a 16 bit compiler)

Is it possible to find the largest document size in MongoDB? 

`db.collection.stats()` shows average size, which is not really representative because in my case sizes can differ considerably.

Find largest document size in MongoDB

I have a User object with properties Name and Surname. I want to search these fields using one query, and I found `multi_match` in the documentation, but I don&#39;t know how to properly use that with a wildcard. Is it possible? 

I tried with a `multi_match` query but it didn&#39;t work:

    {
        &quot;query&quot;: {
            &quot;multi_match&quot;: {
                &quot;query&quot;: &quot;*mar*&quot;,
                &quot;fields&quot;: [
                    &quot;user.name&quot;,
                    &quot;user.surname&quot;
                ]
            }
        }
    }

Elasticsearch how to use multi_match with wildcard

What is the differnce between `UInt8` and `uint8_t`, or `UInt16` and `unit16_t`?

What does the `_t` imply?

Whats the difference between UInt8 and uint8_t

<p>What is the differnce between <code>UInt8</code> and <code>uint8_t</code>, or <code>UInt16</code> and <code>unit16_t</code>?</p>
<p>What does the <code>_t</code> imply?</p>


In C++ you can declare lambdas for example like this:

    int x = 5;
    auto a = [=]() mutable { ++x; std::cout &lt;&lt; x &lt;&lt; &#39;\n&#39;; };
    auto b = [&amp;]()         { ++x; std::cout &lt;&lt; x &lt;&lt; &#39;\n&#39;; };

Both let me modify `x`, so what is the difference?

C++ Lambdas: Difference between &quot;mutable&quot; and capture-by-reference

First of all, I know this question is all over this site but I have looked at almost all of them and can&#39;t seem to find out what is wrong. This is in VS 2012. Thanks.

    //Socket.h
    #pragma once
    
    #include &lt;iostream&gt;
    #include &lt;WinSock2.h&gt;
    
    using namespace std;
    
    const int STRLEN = 256;
    
    class Socket
    {
        protected:
            WSADATA wsaData;
            SOCKET mySocket;
            SOCKET myBackup;
            SOCKET acceptSocket;
            sockaddr_in myAddress;
        public:
            Socket();
            ~Socket();
            bool SendData( char* );
            bool RecvData( char*, int );
            void CloseConnection();
            void GetAndSendMessage();
    };
    
    class ServerSocket : public Socket
    {
        public:
            void Listen();
            void Bind( int port );
            void StartHosting( int port );
    };
    
    class ClientSocket : public Socket
    {
        public:
            void ConnectToServer( const char *ipAddress, int port );
    };
Here&#39;s Socket.cpp

    //Socket.cpp
 

    #include &quot;stdafx.h&quot;
    #include &quot;Socket.h&quot;

    
    Socket::Socket()
    {
        if( WSAStartup( MAKEWORD(2, 2), &amp;wsaData ) != NO_ERROR )
        {
            cerr&lt;&lt;&quot;Socket Initialization: Error with WSAStartup\n&quot;;
            system(&quot;pause&quot;);
            WSACleanup();
            exit(10);
        }
    
        //Create a socket
        mySocket = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP );
    
        if ( mySocket == INVALID_SOCKET )
        {
            cerr&lt;&lt;&quot;Socket Initialization: Error creating socket&quot;&lt;&lt;endl;
            system(&quot;pause&quot;);
            WSACleanup();
            exit(11);
        }
    
        myBackup = mySocket;
    }
    
    Socket::~Socket()
    {
        WSACleanup();
    }
    
    bool Socket::SendData( char *buffer )
    {
        send( mySocket, buffer, strlen( buffer ), 0 );
        return true;
    }
    
    bool Socket::RecvData( char *buffer, int size )
    {
        int i = recv( mySocket, buffer, size, 0 );
        buffer[i] = &#39;\0&#39;;
        return true;
    }
    
    void Socket::CloseConnection()
    {
        //cout&lt;&lt;&quot;CLOSE CONNECTION&quot;&lt;&lt;endl;
        closesocket( mySocket );
        mySocket = myBackup;
    }
    
    void Socket::GetAndSendMessage()
    {
        char message[STRLEN];
        cin.ignore();//without this, it gets the return char from the last cin and ignores the following one!
        cout&lt;&lt;&quot;Send &gt; &quot;;
        cin.get( message, STRLEN );
        SendData( message );
    }
    
    void ServerSocket::StartHosting( int port )
    {
         Bind( port );
         Listen();
    }
    
    void ServerSocket::Listen()
    {
        //cout&lt;&lt;&quot;LISTEN FOR CLIENT...&quot;&lt;&lt;endl;
        
        if ( listen ( mySocket, 1 ) == SOCKET_ERROR )
        {
            cerr&lt;&lt;&quot;ServerSocket: Error listening on socket\n&quot;;
            system(&quot;pause&quot;);
            WSACleanup();
            exit(15);
        }
        
        //cout&lt;&lt;&quot;ACCEPT CONNECTION...&quot;&lt;&lt;endl;
        
        acceptSocket = accept( myBackup, NULL, NULL );
        while ( acceptSocket == SOCKET_ERROR )
        {
            acceptSocket = accept( myBackup, NULL, NULL );
        }
        mySocket = acceptSocket;
    }
    
    void ServerSocket::Bind( int port )
    {
        myAddress.sin_family = AF_INET;
        myAddress.sin_addr.s_addr = inet_addr( &quot;0.0.0.0&quot; );
        myAddress.sin_port = htons( port );
        
        //cout&lt;&lt;&quot;BIND TO PORT &quot;&lt;&lt;port&lt;&lt;endl;
    
        if ( bind ( mySocket, (SOCKADDR*) &amp;myAddress, sizeof( myAddress) ) == SOCKET_ERROR )
        {
            cerr&lt;&lt;&quot;ServerSocket: Failed to connect\n&quot;;
            system(&quot;pause&quot;);
            WSACleanup();
            exit(14);
        }
    }
    
    void ClientSocket::ConnectToServer( const char *ipAddress, int port )
    {
        myAddress.sin_family = AF_INET;
        myAddress.sin_addr.s_addr = inet_addr( ipAddress );
        myAddress.sin_port = htons( port );
        
        //cout&lt;&lt;&quot;CONNECTED&quot;&lt;&lt;endl;
    
        if ( connect( mySocket, (SOCKADDR*) &amp;myAddress, sizeof( myAddress ) ) == SOCKET_ERROR )
        {
            cerr&lt;&lt;&quot;ClientSocket: Failed to connect\n&quot;;
            system(&quot;pause&quot;);
            WSACleanup();
            exit(13);
        } 

    }

And here&#39;s stdafx.h

    #pragma once
    
    #include &quot;targetver.h&quot;
    
    #define WIN32_LEAN_AND_MEAN             // Exclude rarely-used stuff from Windows headers
    // Windows Header Files:
    #include &lt;windows.h&gt;
    
    // C RunTime Header Files
    #include &lt;stdlib.h&gt;
    #include &lt;malloc.h&gt;
    #include &lt;memory.h&gt;
    #include &lt;tchar.h&gt;
    
    
    // TODO: reference additional headers your program requires here
    #include &quot;Socket.h&quot;

And here are my error messages:

    1&gt;------ Build started: Project: Client, Configuration: Debug Win32 ------
    1&gt;  stdafx.cpp
    1&gt;  Socket.cpp
    1&gt;  Client.cpp
    1&gt;  Generating Code...
    1&gt;Socket.obj : error LNK2019: unresolved external symbol __imp__accept@12 referenced in function &quot;public: void __thiscall ServerSocket::Listen(void)&quot; (?Listen@ServerSocket@@QAEXXZ)
    1&gt;Socket.obj : error LNK2019: unresolved external symbol __imp__bind@12 referenced in function &quot;public: void __thiscall ServerSocket::Bind(int)&quot; (?Bind@ServerSocket@@QAEXH@Z)
    1&gt;Socket.obj : error LNK2019: unresolved external symbol __imp__closesocket@4 referenced in function &quot;public: void __thiscall Socket::CloseConnection(void)&quot; (?CloseConnection@Socket@@QAEXXZ)
    1&gt;Socket.obj : error LNK2019: unresolved external symbol __imp__connect@12 referenced in function &quot;public: void __thiscall ClientSocket::ConnectToServer(char const *,int)&quot; (?ConnectToServer@ClientSocket@@QAEXPBDH@Z)
    1&gt;Socket.obj : error LNK2019: unresolved external symbol __imp__htons@4 referenced in function &quot;public: void __thiscall ServerSocket::Bind(int)&quot; (?Bind@ServerSocket@@QAEXH@Z)
    1&gt;Socket.obj : error LNK2019: unresolved external symbol __imp__inet_addr@4 referenced in function &quot;public: void __thiscall ServerSocket::Bind(int)&quot; (?Bind@ServerSocket@@QAEXH@Z)
    1&gt;Socket.obj : error LNK2019: unresolved external symbol __imp__listen@8 referenced in function &quot;public: void __thiscall ServerSocket::Listen(void)&quot; (?Listen@ServerSocket@@QAEXXZ)
    1&gt;Socket.obj : error LNK2019: unresolved external symbol __imp__recv@16 referenced in function &quot;public: bool __thiscall Socket::RecvData(char *,int)&quot; (?RecvData@Socket@@QAE_NPADH@Z)
    1&gt;Socket.obj : error LNK2019: unresolved external symbol __imp__send@16 referenced in function &quot;public: bool __thiscall Socket::SendData(char *)&quot; (?SendData@Socket@@QAE_NPAD@Z)
    1&gt;Socket.obj : error LNK2019: unresolved external symbol __imp__socket@12 referenced in function &quot;public: __thiscall Socket::Socket(void)&quot; (??0Socket@@QAE@XZ)
    1&gt;Socket.obj : error LNK2019: unresolved external symbol __imp__WSAStartup@8 referenced in function &quot;public: __thiscall Socket::Socket(void)&quot; (??0Socket@@QAE@XZ)
    1&gt;Socket.obj : error LNK2019: unresolved external symbol __imp__WSACleanup@0 referenced in function &quot;public: __thiscall Socket::Socket(void)&quot; (??0Socket@@QAE@XZ)
    1&gt;C:\Users\ajayp_000\documents\visual studio 2012\Projects\Client\Debug\Client.exe : fatal error LNK1120: 12 unresolved externals
    ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========



Unresolved external symbol LNK2019

The title is pretty self-descriptive. I&#39;ve downloaded Qt Creator 2.7.0, and I am trying to compile some basic C++11 code:

    int my_array[5] = {1, 2, 3, 4, 5};
    for(int &amp;x : my_array)
    {
      x *= 2;
    }

I&#39;m receiving the following error:

    range based for loops are not allowed in c++ 98 mode

Yet, according to [this article][1] this version of Qt Creator supports C++11. So how do I enable it?


  [1]: http://blog.qt.digia.com/blog/2013/03/21/qt-creator-2-7-0-released/

How to enable C++11 in Qt Creator?

When I run this code:

    struct X {
        int a;
    };
     
    struct Y : public X {};
     
    X x = {0};
    Y Y = {0};

I get:

    error: could not convert ‘{0}’ from ‘&lt;brace-enclosed initializer list&gt;’ to ‘Y’

Why does brace initialization work for the base class but not the derived class?

Why can I not brace initialize a struct derived from another struct?

I know that:

    #define foo 4  
    #define str(s) #s

with `str(foo)` writes out: `&quot;foo&quot;`, because stringify is executed first of text expansion, but this:


     #define xstr(s) str(s)
     #define str(s) #s
     #define foo 4

with `xstr(foo)` writes out: `&quot;4&quot;`.

Why? What are the steps involved in the process?



Stringification - how does it work?

I know how to change the `UINavigationBar` background image by doing 

    [[UINavigationBar appearance] setBackgroundImage:[UIImage imageNamed:@&quot;nabbar&quot;] forBarMetrics:UIBarMetricsDefault];

and I know how to set the bar to different colors within each `Views`..... Now I want to change the background color *without using an image* to a solid color from the `app delegate`. I do not want to set it each time from each view and I do not want to write a `CGRect`.

I tried  `[[UINavigationBar appearance] setBackgroundColor:[UIColor colorWithRed:33/255.0 green:34/255.0 blue:36/255.0 alpha:1.0]];` but I doesn&#39;t work and I cant find a code anywhere that works in the app delegate. 

Could anyone please point me in the right direction?

How to change UINavigationBar background color from the AppDelegate

I want to set subject for email sharing in `UIActivityViewController` and also want to share in Twitter. I know in Twitter if we want to share — we need compress text to 140 chars. I checked many SO solutions, but nothing is working. 

Is this issue fixed in latest iOS releases? Any other &quot;working solutions&quot;?

How to set a mail Subject in UIActivityViewController?

Does anybody know of any controls that will replicate the iOS7 style blur views. 

I&#39;m assumming there can be some kind of UIView subclass that will replicate the behavior. 

I&#39;m talking about these type views which blur the background extremely thickly so that they have pull effects from the background view. 


![enter image description here][1]


![][2]


  [1]: http://i.stack.imgur.com/MIYZa.jpg
  [2]: http://i.stack.imgur.com/iUzLc.jpg

iOS 7 style Blur view

In the Music app of the new iOS, we can see an album cover behind a view that blurs it. 

How can something like that be accomplished? I&#39;ve read the documentation, but did not find anything there.

![][1]


  [1]: http://i.stack.imgur.com/QXEg4m.jpg

Creating a blurring overlay view

I know it&#39;s a new feature and this may not be possible, but I would love to be able to use an Asset Catalog to organize my assets, but I access all of my images programmatically. How would I access my images, now? Do I still access them by their file names like so:

`[UIImage imageNamed:@&quot;my-asset-name.png&quot;];`

Seemingly, the Asset Catalog doesn&#39;t reference the extension, so would it be more efficient to access it without the &quot;.png&quot;?

The reason I am asking instead of testing for myself is that even after removing my assets and Asset Catalog, then cleaning the build folder, I can still access my assets in my application. This is preventing me from testing the Asset Catalog, when I implement it.

After looking through the Asset Catalog, I found the &quot;Contents.json&quot; for each asset and it&#39;s formatted like so:

    {
      &quot;images&quot; : [
        {
          &quot;idiom&quot; : &quot;universal&quot;,
          &quot;scale&quot; : &quot;1x&quot;
        },
        {
          &quot;idiom&quot; : &quot;universal&quot;,
          &quot;scale&quot; : &quot;2x&quot;,
          &quot;filename&quot; : &quot;my-asset@2x.png&quot;
        }
      ],
      &quot;info&quot; : {
        &quot;version&quot; : 1,
        &quot;author&quot; : &quot;xcode&quot;
      }
    }

I&#39;m still unsure of how I should be accessing it, but maybe this will help?

Access Asset Catalog programmatically

When terminating a string, it seems to me that logically `char c=0` is equivalent to `char c=&#39;\0&#39;`, since the &quot;null&quot; (ASCII 0) byte is `0`, but usually people tend to do `&#39;\0&#39;` instead. Is this purely out of preference or should it be a better &quot;practice&quot;?

What is the preferred choice?

------------

**EDIT:** ***K&amp;R*** *says*: &quot;The character constant `&#39;\0&#39;` represents the character with value zero, the null character. `&#39;\0&#39;` is often written instead of `0` to emphasize the character nature of some expression, but the numeric value is just `0`.

String termination - char c=0 vs char c=&#39;\0&#39;

I&#39;ve seen definitions in C 

    #define TRUE (1==1)
    #define FALSE (!TRUE)

Is this necessary? What&#39;s the benefit over simply defining TRUE as 1, and FALSE as 0?

Why #define TRUE (1==1) in a C boolean macro instead of simply as 1?

I’m looking for a free copy version of the [C89/C90 standard][1], but I can’t find it anywhere! Why is so hard to find it?

C99 and C11 standards are very easy to get a copy of on Internet. Even in the Stack Overflow questions *[Where do I find the current C or C++ standard documents?][2]* and *[The C Standard, Obtaining the Standard][3]* don’t contain what I’m looking for.

Web searches didn’t helped either, nor did *[Open Standards][4]*.

  [1]: https://en.wikipedia.org/wiki/ANSI_C#C89_and_C90
  [2]: https://stackoverflow.com/questions/81656
  [3]: http://clc-wiki.net/wiki/The_C_Standard#Obtaining_the_Standard
  [4]: http://www.open-std.org

Where can one find the C89/C90 standards in PDF format?

First, to clarify, I am **not** talking about dereferencing invalid pointers!

Consider the following two examples.

**Example 1**

    typedef struct { int *p; } T;

    T a = { malloc(sizeof(int) };
    free(a.p);  // a.p is now indeterminate?
    T b = a;    // Access through a non-character type?

**Example 2**

    void foo(int *p) {}

    int *p = malloc(sizeof(int));
    free(p);   // p is now indeterminate?
    foo(p);    // Access through a non-character type?

**Question**

Do either of the above examples invoke undefined behaviour?

**Context**

This question is posed in response to [this discussion](https://stackoverflow.com/questions/17019778/what-will-happen-if-a-stdvector-element-commits-suicide-using-delete-this/17019929#comment24597487_17019929).  The suggestion was that, for example, pointer arguments may be passed to a function via x86 segment registers, which could cause a hardware exception.

From the C99 standard, we learn the following (emphasis mine):

&gt; **[3.17]** *indeterminate value* - either an unspecified value or a **trap representation**

and then:

&gt; **[6.2.4 p2]** The value of a pointer becomes **indeterminate** when
the object it points to reaches the end of its lifetime.

and then:

&gt; **[6.2.6.1 p5]** Certain object representations need not represent a value of the object type. If the stored value of an object has such a representation and is read by an lvalue expression that does not have character type, **the behavior is undefined**. If such a representation is produced by a side effect that modifies all or any part of the object by an lvalue expression that does not have character type, the behavior is undefined.  Such a representation is called a **trap representation**.

Taking all of this together, what restrictions do we have on accessing pointers to &quot;dead&quot; objects?

**Addendum**

Whilst I&#39;ve quoted the C99 standard above, I&#39;d be interested to know if the behaviour differs in any of the C++ standards.


Content Type	Original Author	Original Content on Stackoverflow
Question	user1845029	View Question on Stackoverflow
Solution 1 - C++	vdbuilder	View Answer on Stackoverflow
Solution 2 - C++	harald	View Answer on Stackoverflow
Solution 3 - C++	subbupkb	View Answer on Stackoverflow

Whats the difference between UInt8 and uint8_t

C++ Problem Overview

C++ Solutions

Solution 1 - C++

Solution 2 - C++

Solution 3 - C++

Elasticsearch how to use multi_match with wildcard

Find largest document size in MongoDB

Attributions