[C++] Implement press any key to continue

[figgy]

How to implement press any key to continue?

The following doesn't work, it requires me to press enter.

void pressAnyKeyToContinue()
{
	cin.sync();
	cout << endl << "Press any key to continue..." << endl;
	cin.get();
}

Neither does getchar(); instead on cin.get();

[boogerjones]

What platform are you using?

Without implementing some kind of keyboard hook, I think it's only possible on Windows.:

A) system("pause") - which will make people rant about how "slow" and unreliable it is (but you don't give a **** since you just want to end the program)

B) use the _getch function, which is included in conio.h

[Owen W Veteran]

What platform are you using?

Without implementing some kind of keyboard hook, I think it's only possible on Windows:

A) system("pause") - which will make people rant about how "slow" it is (like you give a **** since you just want to end the program)

B) use the _getch function, which is included in conio.h

Getch(); would work great for you. Though "cin" should already be waiting...but I think your problem is that cin.get(); waits for a specific key (Default Enter)

[Andre S. Veteran]

Keep your original code, just change the message to "Press ENTER to continue". Both system("pause") and _getch() are Windows-specific; don't introduce that dependency just for the sake of supporting any key (if you already have that dependency, nevermind). In any case, most users press space or enter when prompted for any key.

[boogerjones]

Keep your original code, just change the message to "Press ENTER to continue". Both system("pause") and _getch() are Windows-specific; don't introduce that dependency just for the sake of supporting any key (if you already have that dependency, nevermind). In any case, most users press space or enter when prompted for any key.

Your argument is made ad infinitum on the web, but it simply doesn't address the OP's question. He wants the user to be able to press any key, not the enter key. And I clearly pointed out that those 2 functions were Windows-specific. But if that's the platform he's developing on, then like you mention, it's perfectly fine. If not, then what he's asking is probably not possible without implementing some low-level key-event hook, but I doubt that would be cross-platform so we'd gain nothing there anyway.

[hdood]

It's worth considering both. If it's homework or something, it might be best to simply ask the user to press enter, because this can be done in a cross-platform manner.

If you really want the any key thing and this is for Windows, use boogerjones' option B. There is no good reason to call pause, even if the overhead doesn't really matter. _getch() does the same thing. Remember that you probably want to flush stdin before you call it, otherwise you can end up just reading a character that is already in the buffer instead of prompting for a new one.

If it's for another platform, you would have to find out what the equivalent terminal I/O stuff is there.

[Ryuurei]

Couldn't he use something like

void Continue()
{
      cout << "Press any key to continue . . .\n";
      cin.get();
      cin.clear();
}

cin.get() will take any input, but will store it in the input queue. To fix this, call cin.clear() which should clear the input.

[hdood]

No, cin.clear just resets the state of the stream, not flush the buffer (which I presume is what your logic is there). There's also the issue of cin.get being synchronous, meaning it won't even return until it has read a full line.

[Ryuurei]

I see.. Well this then is a pretty difficult problem to overcome. Although ultimately it doesn't really matter much that you have a "press any key to continue" sort of function.

Although.. could he perhaps do something like

int main()
{
char c;
//....code.....
//...more code...
cout << "Press any key to continue.\n";
cin >> c;
//..more code
cout << "I dont know why I have so many pauses here...\n";
cin >> c;
//...etc...
}

Something like this. Just create a character to be used in the "pause" mechanism that comes with getting input.

It's not flawless, but you could just disregard the character otherwise. It only takes up one byte, anyway.

It's still not perfect but hey, do what you can.

[Rudy]

I think this should work:

#include <stdio.h>
#include <unistd.h>
#include <termios.h>

int main()
{
char x = ' ';

printf("Press any key to continue...\n");
x = getch();

printf("The key you entered is: %c \n", x);

return 0;
}

int getch(void)
{
int ch;
struct termios oldt;
struct termios newt;
tcgetattr(STDIN_FILENO, &oldt); /*store old settings */
newt = oldt; /* copy old settings to new settings */
newt.c_lflag &= ~(ICANON | ECHO); /* make one change to old settings in new settings */
tcsetattr(STDIN_FILENO, TCSANOW, &newt); /*apply the new settings immediatly */
ch = getchar(); /* standard getchar call */
tcsetattr(STDIN_FILENO, TCSANOW, &oldt); /*reapply the old settings */
return ch; /*return received char */
}

I found it here: http://ubuntuforums.org/archive/index.php/t-225713.html

[hdood]

Something like this. Just create a character to be used in the "pause" mechanism that comes with getting input.

It's not flawless, but you could just disregard the character otherwise. It only takes up one byte, anyway.

It's still not perfect but hey, do what you can.

No, it won't work. It will block at the first cin until you hit enter.

Rudy's code probably will work for the specific platform it's designed for (Linux?), as it's basically an implementation of the Windows _getch().

[Rudy]

No, it won't work. It will block at the first cin until you hit enter.

Rudy's code probably will work for the specific platform it's designed for (Linux?), as it's basically an implementation of the Windows _getch().

Unfortunately I don't have a c/c++ compiler on my Windows machine at work.... so I can't test it but yes I believe it was written for Linux (but I figured it might work on Windows or give him an idea where to start)

[hdood]

Unfortunately I don't have a c/c++ compiler on my Windows machine at work.... so I can't test it but yes I believe it was written for Linux (but I figured it might work on Windows or give him an idea where to start)

It won't, because the Windows console is completely different. Still good to have though, since he didn't specify an OS.

The Windows implementation I described earlier would look like this (in C):

void pause(void)
{
	puts("Press any key to continue...");
	FlushConsoleInputBuffer(GetStdHandle(STD_INPUT_HANDLE));
	_getch();
}

If you wanted it to run on both Windows and Linux, you'd just have to add some #ifdefs.

[Andre S. Veteran]

Your argument is made ad infinitum on the web, but it simply doesn't address the OP's question. He wants the user to be able to press any key, not the enter key.

No need to be so picky. I was not trying to contradict you, just propose an alternative - since you did not mention it, did you? ;). While "Press ENTER to continue" is technically not the same as "Press any key to continue", in many cases it achieves almost the same effect while avoiding a dependency on a non-standard C++ feature. Chances are the OP hadn't thought of it and might consider it a worthy solution. Of course your reply did address his point more directly, but since you already had done so, I saw no reason to repeat what you said.

That's all. :)

[figgy]

Wow! I am impressed by the quality/quantity of options provided.

The code needs to be portable, but I can work with the all your responses.

Thanks to everyone who posted on the thread.

[hdood]

The code needs to be portable, but I can work with the all your responses.

Right, then you have to just ask for enter. There is no portable way to ask for "any" key. It simply doesn't exist. I suppose you could use #ifdefs to add the platform-specific code for the platforms you support and have tested, and then fall back to asking for just enter on all other platforms.