The sleep [man page](http://linux.die.net/man/3/sleep) says it is declared in `&lt;unistd.h&gt;`.

Synopsis:
```c
#include &lt;unistd.h&gt;
```

&gt; **unsigned int sleep(unsigned int seconds);**

`sleep` is a non-standard function. 

 - On UNIX, you shall include `&lt;unistd.h&gt;`.   
 - On MS-Windows, `Sleep` is rather from `&lt;windows.h&gt;`. 

In every case, check the documentation.

this is what I use for a cross-platform code:

    #ifdef _WIN32
    #include &lt;Windows.h&gt;
    #else
    #include &lt;unistd.h&gt;
    #endif

    int main()
    {
      pollingDelay = 100
      //do stuff

      //sleep:
      #ifdef _WIN32
      Sleep(pollingDelay);
      #else
      usleep(pollingDelay*1000);  /* sleep for 100 milliSeconds */
      #endif

      //do stuff again
      return 0;
    }

&gt;*What is the proper #include for the function &#39;sleep()&#39;?*

`sleep()` isn&#39;t Standard C, but POSIX so it should be:

    #include &lt;unistd.h&gt;


[`sleep(3)`][1] is in `unistd.h`, not `stdlib.h`.  Type `man 3 sleep` on your command line to confirm for your machine, but I presume you&#39;re on a Mac since you&#39;re learning Objective-C, and on a Mac, you need `unistd.h`.

[1]: http://www.manpagez.com/man/3/Sleep/


I have written a query:

    function print_ui_hosts
    {
    local sql = &quot;select .........&quot;
    print_sql &quot;$ sql&quot;
    }

local sql - a very long string. Query is not formatted.
How can I split a string into multiple lines?

How to specify a multi-line shell variable?

I&#39;ve been trying to find some way of removing the icon/logo from the action bar but the only thing I&#39;ve found after an hour of searching SO, Android&#39;s documentation and Google is how to remove the title bar in whole. That is not what I want. Only want to remove the icon/logo from the title bar.

Any one know how to accomplish this? Preferably I&#39;d like to do this in **XML**.


Remove icon/logo from action bar on android

I am using the Big Nerd Ranch book Objective-C Programming, and it starts out by having us write in C in the first few chapters. In one of my programs it has me create, I use the sleep function. In the book it told me to put `#include &lt;stdlib.h&gt;` under the `#include &lt;stdio.h&gt;` part. This is supposed to get rid of the warning that says &quot;Implicit declaration of function &#39;sleep&#39; is invalid in C99&quot;. But for some reason after I put `#include &lt;stdlib.h&gt;`, the warning does not go away.. This problem does not stop the program from running fine, but I was just curious on which `#include` I needed to use!

What is the proper #include for the function &#39;sleep()&#39;?

<p>I am using the Big Nerd Ranch book Objective-C Programming, and it starts out by having us write in C in the first few chapters. In one of my programs it has me create, I use the sleep function. In the book it told me to put <code>#include &#x3C;stdlib.h></code> under the <code>#include &#x3C;stdio.h></code> part. This is supposed to get rid of the warning that says "Implicit declaration of function 'sleep' is invalid in C99". But for some reason after I put <code>#include &#x3C;stdlib.h></code>, the warning does not go away.. This problem does not stop the program from running fine, but I was just curious on which <code>#include</code> I needed to use!</p>


I&#39;m trying to create a hello world project for Linux dynamic libraries (.so files). So I have a file hello.c:

    #include &lt;stdio.h&gt;
    void hello()
    {
        printf(&quot;Hello world!\n&quot;);
    }

How do I create a .so file that exports `hello()`, using gcc from the command line?

Build .so file from .c file using gcc command line

While browsing through the gcc compiler source code (gcc/c-family/c-pragma.c) I see:

    typedef struct GTY(()) align_stack {
      int                  alignment;
      tree                 id;
      struct align_stack * prev;
    } align_stack;

and regardless of having lots of C programming years behind me, these bits: `(())` are totally unknown to me yet. Can someone please explain what they mean? Google does not seem to find it.

What is this (( ))?

if I allocate some memory using `malloc()` is there a way to mark it readonly. So memcpy()  fails if someone attempt to write to it?

This is connected to a faulty api design where users are miss-using a const pointer returned by a method  `GetValue()` which is part of large memory structure. Since we want to avoid copying of large chunk of memory we return live pointer within a structured memory which is of a specific format. Now problem is that some user find hack to get there stuff working by writing to this memory directly and avoid SetValue() call that does allocation and properly handing in memory binary format that we have developed. Although there hack sometime work but sometime it causes memory access violation due to incorrect interpretation of control flags which has been overridden by user.

Educating user is one task but let say for now we want there code to fail.

I am just wondering if we can simply protect against this case.

For analogy assume someone get a blob column from sqlite statement and then write back to it. Although in case of sqlite it will not make sense but this somewhat happing in our case.



Is there a way to mark a chunk of allocated memory readonly?

What basically `__asm__ __volatile__ ()` does and what is significance of `&quot;memory&quot;` for ARM architecture?


Working of __asm__ __volatile__ (&quot;&quot; : : : &quot;memory&quot;)

Often in my inner loops I need to index an array in a &quot;wrap-around&quot; way, so that (for example) if the array size is 100 and my code asks for element -2, it should be given element 98. In many high level languages such as Python, one can do this simply with `my_array[index % array_size]`, but for some reason C&#39;s integer arithmetic (usually) rounds toward zero instead of consistently rounding down, and consequently its modulo operator returns a negative result when given a negative first argument.

Often I know that `index` will not be less than `-array_size`, and in these cases I just do `my_array[(index + array_size) % array_size]`. However, sometimes this can&#39;t be guaranteed, and for those cases I would like to know the fastest way to implement an always-positive modulo function. There are several &quot;clever&quot; ways to do it without branching, such as

    inline int positive_modulo(int i, int n) {
        return (n + (i % n)) % n;
    }

or 

    inline int positive_modulo(int i, int n) {
        return (i % n) + (n * (i &lt; 0));
    }

Of course I can profile these to find out which is the fastest on my system, but I can&#39;t help worrying that I might have missed a better one, or that what&#39;s fast on my machine might be slow on a different one.

So is there a standard way to do this, or some clever trick that I&#39;ve missed that&#39;s likely to be the fastest possible way?

Also, I know it&#39;s probably wishful thinking, but if there&#39;s a way of doing this that can be auto-vectorised, that would be amazing.


Fastest way to get a positive modulo in C/C++

Is there a reliable way to kill all the processes of a given user? `kill(-1, SIGKILL)` as that user will work, unless a rogue process of that user kills the killing process first. The best I can find so far is to loop through `system(&quot;ps -u&quot;)` for that user and kill the processes that way, but that seems really hacky and inefficient.

EDIT: To clarify, I&#39;m specifically asking for a POSIX-compatable solution. For some reason I thought tagging the question posix would put that in the title.

Kill all processes for a given user

Is there a POSIX Compliant way to limit the scope of a variable to the function it is declared in? i.e.:

    Testing()
    {
        TEST=&quot;testing&quot;
    }

    Testing
    echo &quot;Test is: $TEST&quot;

should print &quot;Test is:&quot;. I&#39;ve read about the declare, local, and typeset keywords, but it doesn&#39;t look like they are required POSIX built-ins.

POSIX-Compliant Way to Scope Variables to a Function in a Shell Script

I&#39;m hoping someone could shed some light on how to make the parent wait for _ALL_ child processes to finish before continuing after the fork. I have cleanup code which I want to run but the child processes need to have returned before this can happen.

    for (int id=0; id&lt;n; id++) {
      if (fork()==0) {
        // Child
        exit(0);      
      } else {
        // Parent
        ...
      }
      ...
    }

How to make parent wait for all child processes to finish?

In [this](https://stackoverflow.com/questions/5656530/how-to-use-shared-memory-with-linux-in-c) thread the OP is suggested to use `mmap()` instead of `shmget()` to get shared memory in Linux.
I visited [this](http://www.cs.cf.ac.uk/Dave/C/node27.html) page and [this](http://www.jimscode.ca/index.php/component/content/article/13-c/45-c-simple-mmap-example) page to get some documentation, but the second one gives an obscure example regarding `mmap()`.

Being almost a newbie, and needing to share some information (in text form) between two processes, should I use the `shmget()` method or `mmap()`? And why?

Linux shared memory: shmget() vs mmap()?

I have the following code in my bash script. Now I wanna use it in POSIX sh. How can I convert it?
 

    DIR=&quot;$( cd &quot;$( dirname &quot;${BASH_SOURCE[0]}&quot; )&quot; &gt; /dev/null &amp;&amp; pwd )&quot;

How to get script directory in POSIX sh?

I have a JavaScript code that I need to add a sleep/wait function to. The code I am running is already in a function, eg:

    function myFunction(time)
    {
        alert(&#39;time starts now&#39;);
        //code to make the program wait before continuing
        alert(&#39;time is up&#39;)
    }

I have heard that a possible solution might include

    setTimeout
but I am not sure how to use it in this case.

I can&#39;t use PHP, as my server does not support it, although using jQuery would be fine.

JavaScript sleep/wait before continuing

So I a label here (&quot;&quot;). When the button (button1) is clicked, the label text turns into &quot;Test&quot;. After 2 seconds, the text is set back into &quot;&quot;. I made this work with a timer (which has an interval of 2000):

    private void button1_Click(object sender, EventArgs e)
    {
        label1.Text = &quot;Test&quot;;
        timer.Enabled = true;
    }
    
    private void timer_Tick(object sender, EventArgs e)
    {
        label1.Text = &quot;&quot;;
    }

This works; however though, I am curious about making it work in an async method.

My code looks like this currently:

    private void button1_Click(object sender, EventArgs e)
    {
        label1.Text = &quot;Test&quot;;
        MyAsyncMethod();
    }
    
    public async Task MyAsyncMethod()
    {
        await Task.Delay(2000);
        label1.Text = &quot;&quot;;
    }

This doesn&#39;t work though.

Using async to sleep in a thread without freezing

What&#39;s the best way to sleep a certain amount of time, but be able to be interrupted by a `IsCancellationRequested` from a `CancellationToken`?

I&#39;m looking for a solution which works in .NET 4.0.

I&#39;d like to write


    void MyFunc (CancellationToken ct)
    {
       //... 
       // simulate some long lasting operation that should be cancelable 
       Thread.Sleep(TimeSpan.FromMilliseconds(10000), ct); 
    }
    

How to &quot;sleep&quot; until timeout or cancellation is requested in .NET 4.0

I&#39;m currently trying to learn nodejs and a small project I&#39;m working is writing an API to control some networked LED lights.

The microprocessor controlling the LEDs has a processing delay, and I need to space commands sent to the micro at least 100ms apart. In C# I&#39;m used to just calling Thread.Sleep(time), but I have not found a similar feature in node.

I have found several solutions using the setTimeout(...) function in node, however, this is asynchronous and does not block the thread ( which is what I need in this scenario).

Is anyone aware of a blocking sleep or delay function? Preferably something that does not just spin the CPU, and has an accuracy of +-10 ms?

How to create a sleep/delay in nodejs that is Blocking?

I am trying to do something in Java and I need something to wait / delay for an amount of seconds in a while loop.

    while (true) {
        if (i == 3) {
            i = 0;
        }

        ceva[i].setSelected(true);

        // I need to wait here

        ceva[i].setSelected(false);

        // I need to wait here

        i++;
    }

I want to build a step sequencer and I&#39;m new to Java. Any suggestions?



Content Type	Original Author	Original Content on Stackoverflow
Question	trludt	View Question on Stackoverflow
Solution 1 - C	simonc	View Answer on Stackoverflow
Solution 2 - C	md5	View Answer on Stackoverflow
Solution 3 - C	Romain VIOLLETTE	View Answer on Stackoverflow
Solution 4 - C	alk	View Answer on Stackoverflow
Solution 5 - C	Carl Norum	View Answer on Stackoverflow

What is the proper #include for the function 'sleep()'?

C Problem Overview

C Solutions

Solution 1 - C

Solution 2 - C

Solution 3 - C

Solution 4 - C

Solution 5 - C

Remove icon/logo from action bar on android

How to specify a multi-line shell variable?

Attributions