Is there a decent wait function in C

Question

One of the first things I learned in C   was that   include  lt iostream gt  int main         std  cout lt  lt  Hello  World  n       return 0      would simply appear and disappear extremely quickly without pause  To prevent this  I had to go to notepad  and save  helloworld exe pause   ase  helloworld bat   This got tedious when I needed to create a bunch of small test programs  and eventually I simply put while true   at the end on most of my test programs  just so I could see the results  Is there a better wait function I can use

User · Answer

Before the return statement in you main  insert this code   system  pause     This will hold the console until you hit a key    include lt iostream gt   include lt string gt   using namespace std   int main         string s      cout  lt  lt   Please enter your first name followed by a newline n       cin  gt  gt  s      cout  lt  lt   Hello     lt  lt  s  lt  lt    n       system  pause        return 0     this return statement isn t necessary

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There is a C  11 way of doing it  It is quite simple  and I believe it is portable  Of course  as Lightness Races in Orbit pointed out  you should not do this in order to be able to see an Hello World in your terminal  but there exist some good reason to use a wait function  Without further ado    include  lt chrono gt     std  chrono  microseconds  include  lt thread gt     std  this thread  sleep for std  this thread  sleep for std  chrono  microseconds       More details are available here  See also sleep until

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Lots of people have suggested POSIX sleep  Windows Sleep  Windows system  pause    C   cin get   hellip  there s even a DOS  getch   in there  from roughly the late 1920s   Please don t do any of these   None of these solutions would pass code review in my team  That means  if you submitted this code for inclusion in our products  your commit would be blocked and you would be told to go and find another solution   One might argue that things aren t so serious when you re just a hobbyist playing around  but I propose that developing good habits in your pet projects is what will make you a valued professional in a business organisation  and keep you hired    Keeping the console window open so you can read the output of your program is not the responsibility of your program  When you add a wait sleep block to the end of your program  you are violating the single responsibility principle  creating a massive abstraction leak  and obliterating the re-usability chainability of your program  It no longer takes input and gives output  mdash  it blocks for transient usage reasons  This is very non-good   Instead  you should configure your environment to keep the prompt open after your program has finished its work  Your Batch script wrapper is a good approach  I can see how it would be annoying to have to keep manually updating  and you can t invoke it from your IDE  You could make the script take the path to the program to execute as a parameter  and configure your IDE to invoke it instead of your program directly   An interim  quick-start approach would be to change your IDE s run command from cmd exe  lt myprogram gt  or  lt myprogram gt   to cmd exe  K  lt myprogram gt   The  K switch to cmd exe makes the prompt stay open after the program at the given path has terminated  This is going to be slightly more annoying than your Batch script solution  because now you have to type exit or click on the red  X  when you re done reading your program s output  rather than just smacking the space bar     I assume usage of an IDE  because otherwise you re already invoking from a command prompt  and this would not be a problem in the first place  Furthermore  I assume the use of Windows  based on detail given in the question   but this answer applies to any platform hellip  which is  incidentally  half the point

User · Answer

You can use sleep   or usleep        Wait 5 seconds sleep  5

User · Answer

Well  this is an old post but I will just contribute to the question -- someone may find it useful later   adding  cin get     function just before the return of the main   seems to always stop the program from exiting before printing the results  see sample code below   int main          string fname  lname       ask user to enter name first and last name   cout  lt  lt   Please enter your first name       cin  gt  gt  fname     cout  lt  lt   Please enter your last name       cin  gt  gt  lname         cout  lt  lt    n n n nyour first name is     lt  lt  fname  lt  lt    nyour last name is        lt  lt  lname  lt  lt endl       stop program from exiting before printing results on the screen   cin get      return 0

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The appearance and disappearance of a window for displaying text is a feature of how you are running the program  not of C     Run in a persistent command line environment  or include windowing support in your program  or use sleep or wait on input as shown in other answers

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What you have can be written easier   Instead of    include lt iostream gt  int main         std  cout lt  lt  Hello  World  n       return 0      write   include lt iostream gt  int main         std  cout lt  lt  Hello  World  n       system  PAUSE        return 0      The system function executes anything you give it as if it was written in the command prompt  It suspends execution of your program while the command is executing so you can do anything with it  you can even compile programs from your cpp program

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The second thing to learn  one would argue that this should be the first  is the command line interface of your OS and compiler linker flags and switches

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Please note that the code above was tested on Code  Blocks 12 11 and Visual Studio 2012 on Windows 7   For forcing your programme stop or wait  you have several options       sleep unsigned int    The value has to be a positive integer in millisecond  That means that if you want your programme wait for 2 seconds  enter 2000     Here s an example     include  lt iostream gt        for using cout  include  lt stdlib h gt        for using the function sleep  using namespace std       for using cout  int main void                cout  lt  lt   test   lt  lt  endl     sleep 5000             make the programme waiting for 5 seconds    cout  lt  lt   test   lt  lt  endl     sleep 2000              wait for 2 seconds before closing     return 0      If you wait too long  that probably means the parameter is in seconds  So change it to this   sleep 5     For those who get error message or problem using sleep try to replace it by  sleep or Sleep especially on Code  Bloks  And if you still getting problems  try to add of one this library on the beginning of the code    include  lt stdio h gt   include  lt time h gt   include  lt unistd h gt   include  lt dos h gt   include  lt windows h gt       system  PAUSE     A simple  Hello world  programme on windows console application would probably close before you can see anything  That the case where you can use system  Pause      include  lt iostream gt       using namespace std      int main void                 cout  lt  lt   Hello world    lt  lt  endl       system  PAUSE         return 0      If you get the message  error   system  was not declared in this scope  just add  the following line at the biggining of the code     include  lt cstdlib gt       cin ignore     The same result can be reached by using cin ignore       include  lt iostream gt        using namespace std       int main void                 cout  lt  lt   Hello world    lt  lt  endl       cin ignore         return 0         cin get     example     include  lt iostream gt        using namespace std       int main void                 cout  lt  lt   Hello world    lt  lt  endl       cin get         return 0         getch     Just don t forget to add the library conio h     include  lt iostream gt        include  lt conio h gt       for using the function getch    using namespace std       int main void         cout  lt  lt   Hello world    lt  lt  endl       getch         return 0      You can have message telling you to use  getch   insted of getch

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Actually  contrary to the other answers  I believe that OP s solution is the one that is most elegant   Here s what you gain by using an external  bat wrapper    The application obviously waits for user input  so it already does what you want  You don t clutter the code with awkward calls  Who should wait  main    You don t need to deal with cross platform issues - see how many people suggested system  pause   here  Without this  to test your executable in automatic way in black box testing model  you need to simulate the enter keypress  unless you do things mentioned in  the footnote   Perhaps most importantly - should any user want to run your application through terminal  cmd exe on Windows platform   they don t want to wait  since they ll see the output anyway  With the  bat wrapper technique  they can decide whether to run the  bat  or  sh  wrapper  or run the executable directly    Focusing on the last two points - with any other technique  I d expect the program to offer at least --no-wait switch so that I  as the user  can use the application with all sort of operations such as piping the output  chaining it with other programs etc  These are part of normal CLI workflow  and adding waiting at the end when you re already inside a terminal just gets in the way and destroys user experience   For these reasons  IMO  bat solution is the nicest here

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you can require the user to hit enter before closing the program    something like this works    include  lt iostream gt  int main       std  cout  lt  lt   Hello  World n     std  cin ignore      return 0      The cin reads in user input  and the  ignore   function of cin tells the program to just ignore the input   The program will continue once the user hits enter   Link

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Syntax   void sleep unsigned seconds    sleep   suspends execution for an interval  seconds   With a call to sleep  the current program is suspended from execution for the number of seconds specified by the argument seconds  The interval is accurate only to the nearest hundredth of a second or to the accuracy of the operating system clock  whichever is less accurate   This example should make it clear    include  lt dos h gt   include  lt stdio h gt   include  lt conio h gt   int main        printf  Message 1 n       sleep 2     Parameter in sleep is in seconds    printf  Message 2 a two seconds after Message 1       return 0      Remember you have to  include dos h  EDIT   You could also use winAPI   VOID WINAPI Sleep  DWORD dwMilliseconds      Sleep Function Windows   Just a note the parameter in the function provided by winapi is in milliseconds  so the sleep line at the code snippet above would look like this  Sleep 2000

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getchar   provides a simplistic answer  waits for keyboard input   Call Sleep milliseconds  to sleep before exit  Sleep function  MSDN

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the equivalent to the batch program would be    include lt iostream gt  int main         std  cout lt  lt  Hello  World  n       std  cin get        return 0      The additional line does exactly what PAUSE does  waits for a single character input

[c++] Is there a decent wait function in C++?

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