Use std::this_thread::sleep_for Method to Sleep in C++

std::this_thread::sleep_for() is a C++ standard library function that suspends the execution of the current thread for a specified duration. It is defined in the <thread> header and works together with the <chrono> library to specify time intervals.

• Pauses only the calling thread, allowing other threads to continue execution.
• Supports time durations such as milliseconds, seconds, minutes, and hours using <chrono>.

#include <chrono>
#include <iostream>
#include <thread>

using namespace std;

int main()
{
    cout << "Start\n";

    this_thread::sleep_for(chrono::seconds(2));

    cout << "End\n";

    return 0;
}

Start
End

Explanation: The main thread pauses for 2 seconds before printing "End".

Syntax

std::this_thread::sleep_for(duration);

• Parameter: duration - A std::chrono::duration object specifying how long the current thread should sleep.
• Return Value: This function does not return any value.

Working of sleep_for()

The sleep_for() function suspends only the thread from which it is called.

• If called inside main(), the main thread pauses.
• If called inside a worker thread, only that thread pauses while other threads continue executing.
• Execution automatically resumes after the specified duration expires.

Example: Sleeping the Main Thread

#include <iostream>
#include <thread>

using namespace std;

int main()
{
    // Displaying a Statement
    cout << "1st Line" << endl;

    // Halting the execution for 10000ms (milliseconds) or
    // 10 seconds
    std::this_thread::sleep_for(10000ms);

    // Displaying the line after waiting for 10 seconds
    cout << "2nd Line" << endl;
    return 0;
}

Output

Explanation: The main thread sleeps for 3 seconds before executing the next statement.

Specifying the Sleep Duration

The duration is usually specified using the utilities provided by the <chrono> library. Some commonly used duration types are:

For convenience, C++ also provides duration literals (when enabled), such as:

using namespace std::chrono_literals;

this_thread::sleep_for(500ms);

this_thread::sleep_for(2s);

Advantages of sleep_for()

The sleep_for() function offers several benefits:

• Provides a portable way to pause thread execution.
• Suspends only the current thread instead of all threads.
• Useful for delays, scheduling, and synchronization.

Limitations of sleep_for()

Despite its usefulness, sleep_for() has some limitations:

• The actual sleep time may be slightly longer than requested due to operating system scheduling.
• It should not be used for precise real-time timing.
• Excessive use can reduce application responsiveness.