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digitalmars.D.learn - How to simulate Window's "Press any key to continue..."

reply FireController#1847 <usfirepilot123 gmail.com> writes:
I'm an extreme beginner to DLang (just started using it.. oh, an 
hour ago?), and I already can't figure out a, what I'd consider, 
fairly simplistic thing.

This is my current code:

module DTestApp1;

import std.stdio;

int main() {
     write("Press any key to continue...");
     stdin.read();
     return 0;
}

I am using Visual Studio to write it, and no matter what I do I 
cannot get it to work. I attempted to import std.stream;, but it 
said that while it could find the file, it cannot be read. Am I 
using the wrong function?

For those who don't know, what I'm trying to do is pause the 
program until literally any key is pressed while in the console.
Nov 21 2019
next sibling parent reply mipri <mipri minimaltype.com> writes:

wrote:

 I'm an extreme beginner to DLang (just started using it.. oh, 
 an hour ago?), and I already can't figure out a, what I'd 
 consider, fairly simplistic thing.

 This is my current code:

 module DTestApp1;

 import std.stdio;

 int main() {
     write("Press any key to continue...");
     stdin.read();
     return 0;
 }

 I am using Visual Studio to write it, and no matter what I do I 
 cannot get it to work. I attempted to import std.stream;, but 
 it said that while it could find the file, it cannot be read. 
 Am I using the wrong function?

 For those who don't know, what I'm trying to do is pause the 
 program until literally any key is pressed while in the console.


The error doesn't suggest the right replacement, but it still
tells you that the function you want isn't available:

./test.d(6): Error: no property read for type File, did you mean 
std.stdio.File.readf(alias format, Data...)(auto ref Data data) 
if (isSomeString!(typeof(format)))?

std.stdio's documentation is here: 
https://dlang.org/phobos/std_stdio.html

and readln is a function you can use for your purpose.

   stdin.readln();

Or just:

   readln;
Nov 21 2019
parent reply FireController#1847 <usfirepilot123 gmail.com> writes:
On Friday, 22 November 2019 at 04:19:40 UTC, mipri wrote:

 On Friday, 22 November 2019 at 04:10:23 UTC, 


 I'm an extreme beginner to DLang (just started using it.. oh, 
 an hour ago?), and I already can't figure out a, what I'd 
 consider, fairly simplistic thing.

 This is my current code:

 module DTestApp1;

 import std.stdio;

 int main() {
     write("Press any key to continue...");
     stdin.read();
     return 0;
 }

 I am using Visual Studio to write it, and no matter what I do 
 I cannot get it to work. I attempted to import std.stream;, 
 but it said that while it could find the file, it cannot be 
 read. Am I using the wrong function?

 For those who don't know, what I'm trying to do is pause the 
 program until literally any key is pressed while in the 
 console.


 The error doesn't suggest the right replacement, but it still
 tells you that the function you want isn't available:

 ./test.d(6): Error: no property read for type File, did you 
 mean std.stdio.File.readf(alias format, Data...)(auto ref Data 
 data) if (isSomeString!(typeof(format)))?

 std.stdio's documentation is here: 
 https://dlang.org/phobos/std_stdio.html

 and readln is a function you can use for your purpose.

   stdin.readln();

 Or just:

   readln;


Right, but readln will only wait until the user presses the 
delimiter (by default Enter/Return). I want it to wait until ANY 
key is pressed, not a specific key
Nov 21 2019
next sibling parent reply mipri <mipri minimaltype.com> writes:

wrote:

 Right, but readln will only wait until the user presses the 
 delimiter (by default Enter/Return). I want it to wait until 
 ANY key is pressed, not a specific key


If curses is available you can use it, at the cost of completely
changing how you do I/O (in a good way if you need lots of
updates):


/+ dub.sdl:
     dependency "nice-curses" version="~>0.2.5"
+/
import std.stdio;
import nice.curses: Curses;

void main() {
     auto curses = new Curses;
     auto scr = curses.stdscr;

     curses.setCursor(0);
     scr.addstr("Press any key to continue...");
     scr.refresh;
     curses.update;
     scr.getch;
}

If you really just briefly want getch-style input in a normal
terminal program, and still have a posix system, you can do that
with tcsetattr.

https://stackoverflow.com/questions/7469139/what-is-the-equivalent-to-getch-getche-in-linux

struct Terminal {
     import core.stdc.stdio: getchar;
     import core.sys.posix.termios:
         tcgetattr, tcsetattr, termios,
         ECHO, ICANON, TCSANOW, TCSAFLUSH;
     private termios last;

     int getch() { return getchar(); }

     int getch_once() {
         raw;
         auto r = getchar;
         reset;
         return r;
     }

     void raw() {
         termios term;
         tcgetattr(0, &last);
         term = last;
         term.c_lflag &= ~(ICANON | ECHO);
         tcsetattr(0, TCSANOW, &term);
     }

     void reset() { tcsetattr(0, TCSAFLUSH, &last); }

     ~this() { reset(); }
}

void main() {
     import std.stdio: write, writeln;
     Terminal term;

     write("Press any key to continue:");
     term.getch_once();
     writeln;
}
Nov 21 2019
parent mipri <mipri minimaltype.com> writes:
On Friday, 22 November 2019 at 04:41:30 UTC, mipri wrote:

     ~this() { reset(); }


Oh, if you don't ever call raw() this will break your terminal.
I just copied some code from a toy program and adapted it, and
didn't notice that until I posted.
Nov 21 2019
prev sibling parent reply Mike Parker <aldacron gmail.com> writes:

wrote:


 Right, but readln will only wait until the user presses the 
 delimiter (by default Enter/Return). I want it to wait until 
 ANY key is pressed, not a specific key


The documentation for std.stdio.File shows two functions for 
reading input: readln and readf. If readln isn't what you want, 
then readf probably is:

https://dlang.org/phobos/std_stdio.html#.File.readf

Also, there's a freely available book online to help get you up 
to speed: Programming in D. Here's the section on reading from 
stdin with readf:

http://ddili.org/ders/d.en/input.html
Nov 21 2019
next sibling parent reply Mike Parker <aldacron gmail.com> writes:
On Friday, 22 November 2019 at 04:45:21 UTC, Mike Parker wrote:

 On Friday, 22 November 2019 at 04:22:07 UTC, 



 Right, but readln will only wait until the user presses the 
 delimiter (by default Enter/Return). I want it to wait until 
 ANY key is pressed, not a specific key


 The documentation for std.stdio.File shows two functions for 
 reading input: readln and readf. If readln isn't what you want, 
 then readf probably is:

 https://dlang.org/phobos/std_stdio.html#.File.readf

 Also, there's a freely available book online to help get you up 
 to speed: Programming in D. Here's the section on reading from 
 stdin with readf:

 http://ddili.org/ders/d.en/input.html


Sorry, I just noticed the book doesn't cover how to do what you 
want and it's probably not obvious. You need to call readf with a 
character format string (%c):

import std.stdio;
void main()
{
     writeln("Press any key to continue...");

     char c;
     readf("%c", &c);
     writeln("Thanks!");
}
Nov 21 2019
parent reply =?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:
On 11/21/19 9:10 PM, Mike Parker wrote:> On Friday, 22 November 2019 at 
04:45:21 UTC, Mike Parker wrote:


 You need to call readf with a character
 format string (%c):

 import std.stdio;
 void main()
 {
      writeln("Press any key to continue...");

      char c;
      readf("%c", &c);
      writeln("Thanks!");
 }


Unfortunately, that won't work either as it requires stdin to be 
unbuffered, which is not the case in most terminals.

The main issue here is that a D program cannot know that stdin is bound 
to a keyword. One needs to use a terminal module like the suggested 
curses or Adam's terminal.d:

   https://github.com/adamdruppe/arsd/blob/master/terminal.d

If it's too much unnecessary complication, then "Press Enter to 
continue..." is perfectly fine to me. ;) (But of course you can't move 
the cursor with that. :/)

Ali
Nov 22 2019
parent Adam D. Ruppe <destructionator gmail.com> writes:
On Friday, 22 November 2019 at 09:25:37 UTC, Ali Çehreli wrote:

   https://github.com/adamdruppe/arsd/blob/master/terminal.d


I have this exact thing as a sample in my docs:

http://dpldocs.info/experimental-docs/arsd.terminal.html#single-key

You could wrap that up in a function if you don't want anything 
else.

though personally I'd just do "press enter to continue" since it 
is so much easier and avoids the dependency.

you can use my module by copying the whole file to your source 
and using it, or it is a dub package arsd-official:terminal too
Nov 22 2019
prev sibling parent IGotD- <nise nise.com> writes:
On Friday, 22 November 2019 at 04:45:21 UTC, Mike Parker wrote:

 On Friday, 22 November 2019 at 04:22:07 UTC, 



 Right, but readln will only wait until the user presses the 
 delimiter (by default Enter/Return). I want it to wait until 
 ANY key is pressed, not a specific key


 The documentation for std.stdio.File shows two functions for 
 reading input: readln and readf. If readln isn't what you want, 
 then readf probably is:

 https://dlang.org/phobos/std_stdio.html#.File.readf

 Also, there's a freely available book online to help get you up 
 to speed: Programming in D. Here's the section on reading from 
 stdin with readf:

 http://ddili.org/ders/d.en/input.html


stdin is buffered and will not be forwarded to the D-library 
until you press enter. The solution is different on Linux and 
Windows. On Linux you need to disable the "CANON" mode in the 
terminal.

https://stackoverflow.com/questions/1449324/how-to-simulate-press-any-key-to-continue

There are a few suggestions for Windows in the link as well. 
Annoyingly complicated for such a simple thing but that's how it 
is.
Nov 22 2019
prev sibling parent Jesse Phillips <Jesse.K.Phillips+D gmail.com> writes:

wrote:

 I'm an extreme beginner to DLang (just started using it.. oh, 
 an hour ago?), and I already can't figure out a, what I'd 
 consider, fairly simplistic thing.

 This is my current code:

 module DTestApp1;

 import std.stdio;

 int main() {
     write("Press any key to continue...");
     stdin.read();
     return 0;
 }

 I am using Visual Studio to write it, and no matter what I do I 
 cannot get it to work. I attempted to import std.stream;, but 
 it said that while it could find the file, it cannot be read. 
 Am I using the wrong function?

 For those who don't know, what I'm trying to do is pause the 
 program until literally any key is pressed while in the console.


execute(["pause"]);
Nov 22 2019