Making a code wait for a certain time is a practice used by many programmers.

C++ has multiple ways. In this article we will see some forms for Linux and also for Windows .

We will show 5 examples in each of them for the code to wait 2 seconds in some cases also using microseconds and milliseconds .

1st Using unistd.h

This is perhaps the simplest form of all, using the #include <unistd.h> header

#include <unistd.h>
int main(){
   // 2 in sleep seconds
   sleep(2);
   return 0;
}

For more information run the command:

man 3 sleep

2º Using std::chrono

std::chrono is a flexible collection of types that track time with varying degrees of precision. For this example we will use the function: std::this_thread::sleep_for, example:

Entering the time in seconds:

#include <chrono>
#include <thread>

int main(){
   // 2 in sleep seconds
   std::this_thread::sleep_for( std::chrono::seconds(2) );
   return 0;
}

Reporting the time in microseconds

#include <chrono>
#include <thread>

int main(){
   // 2 000 000 MICROSECONDS of sleep
   // equates to 2 seconds
   std::this_thread::sleep_for( std::chrono::microseconds( 2000000 ) );
   return 0;
}

It is still possible to use: minutes, milliseconds and among others.

3º Using Windows.h

Only for Windows if you want to create portable solutions, it would be something like this:

#ifdef _WIN32
#define WINDOWS_SYSTEM
#include <Windows.h>
#else
#include <unistd.h>
#endif

int main(){

#ifdef WINDOWS_SYSTEM
   Sleep( 2000000 );
#else
   usleep( 2000000 );
#endif

   return 0;
}

4º Using the boost Library

boost.org is a collection of useful libraries for C++ that makes your code more portable.

Check first if you have it installed on your system, although I find it difficult not to have it, as many things use it.

For this example we use boost::posix_time:

#include <boost/thread.hpp>

int main(){
     // Added waits 2 seconds

     // wait 1 second
     boost::this_thread::sleep( boost::posix_time::seconds(1) );
     // wait 1000 milliseconds = 1 second
     boost::this_thread::sleep( boost::posix_time::milliseconds(1000) );

     return 0;
}

To compile use the -lboost_thread and -pthread flags together, example:

g++ -lboost_thread -pthread sleep.cpp

That’s all for today, small daily doses that will always keep us tuned with C++ !

cpp

Marcos Oliveira

Software developer

https://github.com/terroo