Delay function in cpp

Add Timed Delay in C++

In C++ 11, we are provided with specific functions for making thread sleep. This means the execution of the process can be put on hold for the time it is in the sleep.

Add Timed Delay in C++

This tutorial will give you a brief guide on adding a timed delay in your C++ program.

This can be done in many ways using some functions that C++ libraries provide us. We will discuss some functions along with their working demo.

Any process, task, or thread in a computer program can sleep or become inactive. This means the execution of the process can be put on hold for the time it is in the sleep.

When the sleep interval expires or a signal or interruption causes the execution to resume, the execution will be resumed. There are different methods for this purpose:

1. the sleep() system call
2. the usleep() method
3. the sleep_for() method
4. the sleep_until() method

Use the sleep() System Call to Add a Timed Delay in C++

A sleep system call can put a program (task, process, or thread) to sleep. The time parameter in a typical sleep system call tells how much time the program needs to sleep or remain inactive.

The C++ language does not have its sleep function. This functionality is provided by operating-system-specific files such as unistd.h for Linux and Windows.h for Windows.

To use the sleep() function on a Linux or UNIX operating system, we must include the «unistd.h» header file in our program.

Function Prototype

unsigned sleep(unsigned seconds); 

It takes a parameter amount of seconds for which we need to suspend the execution and returns 0 if it successfully returns to the execution. If the sleep is interrupted in between, the total time minus the interruption time is returned.

#ifdef _WIN32 #include #else #include #endif #include #include using namespace std; int main()

Before sleep call After sleep call 

Use the usleep() Function to Add a Timed Delay in C++

Another function in the header unistd.h is usleep() , which allows you to pause the execution of a program for a set amount of time. The operation is identical to the previously described sleep() function.

The function usleep() suspends the caller thread’s execution for useconds microseconds or until the signal interrupting the execution is sent.

Function Prototype

int usleep(useconds_t useconds); 

This function takes as a parameter the no of microseconds for which you need to pause the execution and return 0 if successfully resumed and -1 if some failure occurs.

#include #include #include using namespace std; int main()

Before Usleep Call After Usleep call 

As you can see in the above code snippet, we have provided a wait of 10000 microseconds between printing two statements.

In C++ 11, we are provided with specific functions for making thread sleep. There are two methods for this purpose, sleep_for and sleep_until .

Let’s discuss these two methods:

Use the sleep_for() Function to Add a Timed Delay in C++

The function sleep_for() is defined in the header. The sleep_for () function suspends the current thread’s execution for the duration specified in sleep duration.

Due to scheduling activities or resource contention delays, this function may block for longer than the provided period.

Function Prototype

template < class Rep, class Period >void sleep_for( const std::chrono::duration& sleep_duration ); 

#include #include #include using namespace std; int main()

Hello I'm here before waiting I Waited for 10000 ms 

In the above code snippet, we have made the main thread sleep for 10000 milliseconds which means that the current thread will block 10000 milliseconds and then resume its execution.

Use the sleep_until() Function to Add a Timed Delay in C++

The header defines this function. The sleep_until () method stops a thread from running till the sleep time has passed.

Due to scheduling activities or resource contention delays, this function, like the others, may block for longer than the specified time.

Function Prototype

template < class Clock, class Duration >void sleep_until( const std::chrono::time_point& sleep_time ); 

It takes in as a parameter the period for which the thread needs to be blocked and returns nothing.

#include #include #include using namespace std; int main()

Hello I'm here before waiting I Waited for 2 seconds 

How to properly use __delay_ms() in libraries in, 2 Answers. You define _XTAL_FREQ in your C source file containing main () but, since you’re calling __delay_ms () in qc3.c (a separate translation unit), that’s where that definition needs to exist. The easiest fix is probably to define it in qc3.h. you must give _XTAL_FREQ inside the .c file then you may get.

How to delay output in C++?

I am doing a project that need to read data from a file.
But before the file is opened i want to display Loading . . . . . I want the dots after «Loading» to get printed one by one and each after about 2-3 seconds and then i display my file’s contents. That is, after first 3 seconds Loading . displays and after another 3 seconds Loading . . displays and so on. I Couldn’t find a way to do, please help.

This is platform-dependent.

The parameter is the amount of time in milliseconds. You need to include windows.h in order to use this function.

On POSIX-compatible, you may use sleep():

sleep(3); // parameter is in seconds 

If you need better precision, you may use usleep():

usleep(3000000); // parameter is in microseconds 

For both functions, you need to include unistd.h

In c++11, you can create a thread that loop on sleep 3sec and print dots just before reading the file. You must use condition or variable guarded by mutex to exit the thread.

1 use sleep() of usleep() to block it. 2. use a while loop to let cpu busy loop.

In production, we usualy do the first solution. But be cautious about this always. make sure this is what you want to do.

Another way is, use a event loop approach and set a timer for this event. it can be ran later after timer is timed-out

#include #include . using namespace std::chrono_literals; . std::this_thread::sleep_for(2s); 

Delay in Dev C++, I had an alternative way for using it with the help of for loop but i aint got its proper syntax in my mind to use it properly. I wish, you folks, might be able to resolve the problem for me. Thanks in Advance.. #include int main () < delay (1000) cout

How to delay in c++?

I am working on a rehabilitation application that relies on four ARuco markers,i need to draw on the four markers in the exercise sequence i.e. the object appears on the first marker, when the patient’s hand reaches the object, it moves to the next marker, etc. . I could draw on only the first marker by selecting its marker id, now i need to make a delay to draw on the next marker, here is the code:

std::vector ids; std::vector > corners; cv::aruco::detectMarkers(image, marker_dict, corners, ids); // Draw markers using opencv tool cv::aruco::drawDetectedMarkers(mid, corners, ids); // Draw markers custom for (size_t i = 0; i < corners.size(); ++i) < // Convert to integer ponits int num = static_cast(corners[i].size()); std::vector points; for (size_t j = 0; j < corners[i].size(); ++j) points.push_back(cv::Point(static_cast(corners[i][j].x), static_cast(corners[i][j].y))); const cv::Point* pts = &(points[0]); // Draw if (ids.at(i) == 45)

Use the std::chrono library to measure time that has passed, when your desired delay has passed, execute the code you want at that time.

Here is a simple example using a while loop which checks if 100 milliseconds have passed

#include #include #include int main() < using Clock = std::chrono::steady_clock; std::chrono::time_pointstart, now; std::chrono::milliseconds duration; start = Clock::now(); while (true) < now = Clock::now(); duration = std::chrono::duration_cast(now - start); if (duration.count() >= 100) < //do stuff every 100 milliseconds start = Clock::now(); >> return 0; > 

No sleep necessary either.

You can use the headers chromo and thread. After the function, you can put the sleep(); anywhere with the amount of seconds in the brackets. You can use decimals and whole numbers.

#include #include #include void sleep(float seconds) < clock_t startClock = clock(); float secondsAhead = seconds * CLOCKS_PER_SEC; // do nothing until the elapsed time has passed. while(clock() < startClock+secondsAhead); return; >int main()

C++ - "delay()" Function not working not working in Dev, c++ delay. Share. Improve this question. Follow asked Mar 12, 2020 at 15:19. user12994514 user12994514. 1. Is there any reason you use such ancient headers? Modern C++ has all the funtions you need -> std::this_thread::sleep_for – churill. Mar 12, 2020 at 17:21.

What is delay() in C? Is it a system function?

In a book, I saw a piece of code.

but when I ran this code it said: C:\Users\dipankar\Desktop\cla.cpp [Error] 'delay' was not declared in this scope

They used it without proper documentation. They only said that "delay() is used to delay the execution of the next line by few milliseconds". please help.

The book you are reading is crap. Avoid the book and tell others to do the same.

• is a system-specific header and not guaranteed to be available on many platforms.
• The result of fgetc must never be stored in a char variable.
• The function feof must never be used in a loop condition.

The book probably comes from the 1980s or early 1990s. There is a function delay in Turbo Pascal that takes milliseconds. Maybe that's the one the author means.

It's a millisecond delay function. Where it's defined depends a lot on what platform/toolchain you're compiling against. Often it would be found in

I am not aware of any sleep function as part of the C standard. However, you would use nanosleep (https://linux.die.net/man/2/nanosleep) for this purpose in Linux.

Delay loop output in C++, The best accuracy you can achieve is by using Operating System (OS) functions. You need to find the API that also has a callback function. The callback function is a function you write that the OS will call when the timer has expired.. Be aware that the OS may lose timing precision due to other tasks and activities that …

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Delay() function in C++

Hello everyone, In this post, we will learn about the delay() function in C++. There can be many instances when we need to create a delay in our programs. C++ provides us with an easy way to do so. We can use a delay() function for this purpose in our code. This function is imported from the “dos.h” header file in C++. We can run the code after a specific time in C++ using delay() function.

delay() function in C++

Now let us understand the syntax for delay() function. It is as follows:

void delay(unsigned int milliseconds);

• Here, void suggests that this function returns nothing.
• ‘delay’ is the function name.
• The function takes one parameter which is unsigned integer.

Create a delay in time in a C++ program

The key point to note here is that this delay() function accepts parameter in milliseconds. That is if we want to create a 1-second delay in our program we have to pass 1000 as a parameter to the function.

Example of delay() in C++

#include #include //for delay() #include //for getch() int main() < clrscr(); int n; cout>n; delay(n*1000); cout

Enter the delay (in seconds) you want to make after giving input. 5 This has been printed after 5 seconds delay.

How it worked:

As you can see in the program, we are taking input from the user ( To know: Taking only integer input in C++ ) and passing it to the delay function after multiplying it with 1000 to convert the seconds into milliseconds.
“dos.h” header file has been included so that a call to delay() function can be made.

NOTE: Your compiler must have dos.h header file in it.

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