Replacing system("PAUSE")

This is a discussion on Replacing system("PAUSE") within the C++ Programming forums, part of the General Programming Boards category; I know that using system("PAUSE") to pause a running program is bad. But I need it so that user can ...

  1. #1
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    Replacing system("PAUSE")

    I know that using system("PAUSE") to pause a running program is bad. But I need it so that user can read the output. Is there any way to achieve the same effect of system("PAUSE") without using it? Thanks in advance

  2. #2
    C++ Witch laserlight's Avatar
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    This is covered in the FAQ, actually: How do I get my program to wait for a keypress?.
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    I looked at the link. Why we needed the myflush() for the C++ implementation?
    Last edited by jk1998; 05-11-2007 at 01:18 PM.

  4. #4
    C++ Witch laserlight's Avatar
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    Some characters may be left on the buffer, so without such an "input flush" the next character would just be read without actually appearing to pause the program.
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    Thanks

  6. #6
    "Why use dynamic memory?"
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    you could use <conio.h> library with
    getch();


    before
    return 0;

    but i dont advice you to use it to be honest. "I think" it has performance issue
    "C makes it easy to shoot yourself in the foot; C++ makes it harder, but when you do, it blows away your whole leg."-Bjarne Stroustrup
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  7. #7
    Registered User whiteflags's Avatar
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    There is no reason to include a whole non Standard library just to replace system( "pause" );
    Write something using Standard code, like the FAQ tells you to.

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    You can also output what you want to know to a file.

  9. #9
    Captain Crash brewbuck's Avatar
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    Quote Originally Posted by Hussain Hani View Post
    but i dont advice you to use it to be honest. "I think" it has performance issue
    You're concerned about a performance issue in a function that is being used to wait for the user to exit the program?

  10. #10
    Deathray Engineer MacGyver's Avatar
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    Quote Originally Posted by brewbuck View Post
    You're concerned about a performance issue in a function that is being used to wait for the user to exit the program?
    LOL.

    But seriously, can someone explain to me why people insist upon using the non-portable getch() and conio.h? What would kill them to just use std::cin.ignore() or fgetc(stdin) to read off a single char?

  11. #11
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    getch() and cin.ignore() are different. If you can use getch() on your platform, it works better and more often than cin.ignore() (or cin.get()). That's why some people prefer to use it.

    I personally prefer the standard solutions because they aren't that hard to get right and I don't want to worry about who has conio and who doesn't.

  12. #12
    Deathray Engineer MacGyver's Avatar
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    Yes, they're different, but at least you know something standard works. I would imagine if it was important enough to get something like this to work exactly as you want it, shouldn't you just write your own OS specific getch() type of function to work with most operating systems that you'll target?

  13. #13
    Cat without Hat CornedBee's Avatar
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    Well, here's the POSIX version, C99 code:
    Code:
    #include <unistd.h>
    #include <termios.h>
    #include <string.h>
    
    void pause(const char *msg)
    {
      printf("&#37;s\n", msg);
      struct termios trm;
      memset(&trm, 0, sizeof(struct termios));
      cfmakeraw(&trm);
      struct termios old;
      tcgetattr(STDIN_FILENO, &old);
      tcsetattr(STDIN_FILENO, TCSAFLUSH, &trm);
      char buf;
      read(STDIN_FILENO, &buf, 1);
      tcsetattr(STDIN_FILENO, TCSAFLUSH, &old);
    }
    I'm sure someone can write a WinAPI version that does the same: print a message, wait for a single keypress.
    All the buzzt!
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  14. #14
    Deathray Engineer MacGyver's Avatar
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    What's wrong with system("PAUSE") on Windows?

    But a little more seriously, I looked through the Windows API for console functions, and decided to try to write one up. Is there anything wrong with this that could cause any unexpected issues?

    I know one "problem" is that if you're using the C (and possibly the same thing occurs with the C++ file system), the FILE * buffer maintained in the stdin FILE object are obviously not drained (or flushed as people like to say, even for input streams). That is left up to the programmer to handle.

    Code:
    #include <windows.h>
    
    void pause(const char *szMsg)
    {
    	char c;
    	DWORD dwWritten, dwRead, dwOld;
    	HANDLE in = GetStdHandle(STD_INPUT_HANDLE);
    	HANDLE out = GetStdHandle(STD_OUTPUT_HANDLE);
    	
    	if((in) && (out))
    	{
    		WriteConsoleA(out,szMsg,strlen(szMsg),&dwWritten,NULL);
    		FlushConsoleInputBuffer(in);
    		GetConsoleMode(in,&dwOld);
    		SetConsoleMode(in,0);
    		ReadConsoleA(in,&c,1,&dwRead,NULL);
    		SetConsoleMode(in,dwOld);
    	}
    	return;
    }

  15. #15
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    >> shouldn't you just write your own OS specific getch() type of function to work with most operating systems that you'll target?

    No. Most people who do this are just beginners. It is often important for them to get it working with minimal effort so they can concentrate on learning to program. If getch() works, then it works.

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