Something not sleep() but just as simple

[UDBV]

Someone told me that code that contains "sleep()" can only run on Windows. Having a knowledge of C++ that barely goes beyond 3 weeks in a 2 semester course (The other time was spent in a program called Scratch, it was fun to use, but not practical and it angered me because it was supposed to be a C++ class.) I really cannot judge what I'm told by someone who is better than me in C++. If that is a lie, I'd say I have an easy solution to this problem. But if its not, the research that I've done has only turned up sleep() - which is really not what I'm looking for - and some complex pieces (for me at least) of code that I do not understand.

Thanks in advance
-UDBV

PS What I do know is pretty much only functions, loops (for, while, do, and if), cout and cin, and goto

[coder777]

It depends. What are you trying to do with this function?

[kbw]

These delay functions are not part of C++, but provided by the OS. If the OS supports it, you can call it from C++. You will need to use correct include file.

The Windows function is Sleep().
http://msdn.microsoft.com/en-us/library/windows/desktop/ms686298%28v=vs.85%29.aspx
e.g.

#include <windows.h>
#include <iostream>

int main()
{
    std::cout << "Sleeping for 10 seconds ..." << std::endl;
    Sleep(10 * 1000);
    return 0;
}

The POSIX function is sleep().
http://pubs.opengroup.org/onlinepubs/007908799/xsh/sleep.html
e.g.

#include <unistd.h>
#include <iostream>

int main()
{
    std::cout << "Sleeping for 10 seconds ..." << std::endl;
    sleep(10);
    return 0;
}

[S G H]

Yes, Sleep is windows-only. Anyways you can recreate the function for yourself. Remember that Sleep(0) does NOT wait 0 seconds, but just idles so that your CPU is more free, and that is hardly recreable.
Besides that case, this should be the non-os-depending code:

#include <ctime>
bool Wait(const unsigned long &Time)
{
    clock_t Tick = clock_t(float(clock()) / float(CLOCKS_PER_SEC) * 1000.f);
    if(Tick < 0) // if clock() fails, it returns -1
        return 0;
    clock_t Now = clock_t(float(clock()) / float(CLOCKS_PER_SEC) * 1000.f);
    if(Now < 0)
        return 0;
    while( (Now - Tick) < Time )
    {
        Now = clock_t(float(clock()) / float(CLOCKS_PER_SEC) * 1000.f);
        if(Now < 0)
            return 0;
    }
    return 1;
}

Then in your code you can use it like:

if(!Wait(1000)) // Wait 1 second (1000 ms)
    { /* Error */ }

[kbw]

That code doesn't really sleep as it uses the CPU.

It's not easy to write a portable sleep function that releases the CPU while waiting.

[S G H]

kbw wrote:

That code doesn't really sleep as it uses the CPU.

It's not easy to write a portable sleep function that releases the CPU while waiting.

True.

I still didn't manage to know how to do it os-indipendently.
I guess Sleep() for Windows uses WaitForMessage, or a Timer (SetTimer/KillTimer).

[Peter87]

In C++11 you can use sleep_for
http://en.cppreference.com/w/cpp/thread/sleep_for

[kbw]

Thanks, I didn't know that.

[UDBV]

Yes, Sleep is windows-only. Anyways you can recreate the function for yourself. Remember that Sleep(0) does NOT wait 0 seconds, but just idles so that your CPU is more free, and that is hardly recreable.
Besides that case, this should be the non-os-depending code:

#include <ctime>
bool Wait(const unsigned long &Time)
{
    clock_t Tick = clock_t(float(clock()) / float(CLOCKS_PER_SEC) * 1000.f);
    if(Tick < 0) // if clock() fails, it returns -1
        return 0;
    clock_t Now = clock_t(float(clock()) / float(CLOCKS_PER_SEC) * 1000.f);
    if(Now < 0)
        return 0;
    while( (Now - Tick) < Time )
    {
        Now = clock_t(float(clock()) / float(CLOCKS_PER_SEC) * 1000.f);
        if(Now < 0)
            return 0;
    }
    return 1;
}

Then in your code you can use it like:

if(!Wait(1000)) // Wait 1 second (1000 ms)
    { /* Error */ }[/

I am quite new to C++ so even though I'm glad that you have provided an alternative to me, I would still like to know what exactly I'm doing. I mean I've never seen this stuff before. So if you don't mind explaining it, I would appreciate it if you could. Otherwise I'll be on my way. Thanks again.

[S G H]

Well, that's a Sleep-like function.
It simply waits some time.

[Callum5042]

#include <ctime>

void wait(int sec)
{
        clock_t endwait;
        endwait = clock() + sec * CLK_TCK;
        while (clock() < endwait) {}
}

That should work

Just use it where you want it to be with 'wait(1);' for it to wait for a second

[Lowest0ne]

These functions don't really "sleep", they are looping-looping-looping until they aren't supposed to anymore.

A "true" sleep actually makes your program sleep, it is using 0% of the CPU.

[UDBV]

These functions don't really "sleep", they are looping-looping-looping until they aren't supposed to anymore.

These will work fine for what I'm trying to achieve, thank you guys :3