Thread: Replacing system("PAUSE")

This is covered in the FAQ, actually: How do I get my program to wait for a keypress?.

I looked at the link. Why we needed the myflush() for the C++ implementation?

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.

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

Originally Posted by brewbuck

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?

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?

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.

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;
}