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digitalmars.D.learn - read single characters from stdin

reply Thomas Koch <thomas koch.ro> writes:
Hi,

to learn D, I'd like to write a simple type trainer. It should write a line 
to stdout and then read single characters from stdin and only accept the 
correct characters

How can I read single characters?

A similar question has been asked before without a working answer:
http://forum.dlang.org/thread/jl79f7$2083$1 digitalmars.com

But I can't beliebe that there isn't a simple solution in D for this 
problem...

Regards, Thomas Koch
Sep 26 2012
next sibling parent reply "Adam D. Ruppe" <destructionator gmail.com> writes:
On Wednesday, 26 September 2012 at 17:51:03 UTC, Thomas Koch 
wrote:

 How can I read single characters?


The way I'd do it is with the C call fgetc(stdin). You can do it 
in D the same way if you import core.stdc.stdio;

But, if you are on Linux, it isn't going to be that simple. The 
Linux terminal/operating system will buffer input, not sending 
any data to you until the user presses enter.

You'll probably want to use a library like ncurses on linux... 
you can do without too, turning on raw mode to the terminal I 
think, but I don't remember how to do it right now. Are you on 
Linux or Windows?

(I'm pretty sure it just works on windows but it's been a while 
since I've done an app like this.)
Sep 26 2012
parent 1100110 <0b1100110 gmail.com> writes:
On Wed, 26 Sep 2012 13:06:03 -0500, Adam D. Ruppe  
<destructionator gmail.com> wrote:


 On Wednesday, 26 September 2012 at 17:51:03 UTC, Thomas Koch wrote:

 How can I read single characters?


 The way I'd do it is with the C call fgetc(stdin). You can do it in D  
 the same way if you import core.stdc.stdio;

 But, if you are on Linux, it isn't going to be that simple. The Linux  
 terminal/operating system will buffer input, not sending any data to you  
 until the user presses enter.

 You'll probably want to use a library like ncurses on linux... you can  
 do without too, turning on raw mode to the terminal I think, but I don't  
 remember how to do it right now. Are you on Linux or Windows?

 (I'm pretty sure it just works on windows but it's been a while since  
 I've done an app like this.)



ncurses will do it with getch().
pdpurses should have the same function.

You will most likely still have to ncurses setup and teardown though.  
shrug.
Sep 28 2012
prev sibling next sibling parent reply =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 09/26/2012 10:51 AM, Thomas Koch wrote:

 Hi,

 to learn D, I'd like to write a simple type trainer. It should write 


a line

 to stdout and then read single characters from stdin and only accept the
 correct characters

 How can I read single characters?

 A similar question has been asked before without a working answer:
 http://forum.dlang.org/thread/jl79f7$2083$1 digitalmars.com


Considering that stdin is a char stream and that there is no concept of 
a keyboard or a monitor in D (nor in C and nor in C++), I stand by my 
solution from that thread: :)

import std.stdio;

void main()
{
     while (!stdin.eof) {
         char code;
         readf("%s", &code);
         writefln("%u", code);
     }
}

Just remember that char is a UTF-8 code unit.


 But I can't beliebe that there isn't a simple solution in D for this
 problem...


This thread may have some answers:

   http://forum.dlang.org/thread/im8cnf$ioe$1 digitalmars.com?page=1

Ali
Sep 26 2012
parent Thomas Koch <thomas koch.ro> writes:
Ali Çehreli wrote:

 Considering that stdin is a char stream and that there is no concept of
 a keyboard or a monitor in D (nor in C and nor in C++), I stand by my
 solution from that thread: :)


Thank you, especially for the link, but your proposal still requires to 
press enter.

Regards, Thomas Koch
Sep 28 2012
prev sibling next sibling parent reply "nazriel" <spam dzfl.pl> writes:
On Wednesday, 26 September 2012 at 17:51:03 UTC, Thomas Koch 
wrote:

 Hi,

 to learn D, I'd like to write a simple type trainer. It should 
 write a line
 to stdout and then read single characters from stdin and only 
 accept the
 correct characters

 How can I read single characters?

 A similar question has been asked before without a working 
 answer:
 http://forum.dlang.org/thread/jl79f7$2083$1 digitalmars.com

 But I can't beliebe that there isn't a simple solution in D for 
 this
 problem...

 Regards, Thomas Koch


http://dpaste.dzfl.pl/eb1387cc

;-)
Sep 26 2012
parent reply Thomas Koch <thomas koch.ro> writes:
nazriel wrote:

 http://dpaste.dzfl.pl/eb1387cc


Thank you. Your solution does not seem to work with multibyte characters, so 
I extended it:


import core.sys.posix.termios;
import core.stdc.stdio;

char getch()
{
        int ch;
        termios oldt;
        termios newt;

        tcgetattr(0, &oldt);
        newt = oldt;
        newt.c_lflag &= ~(ICANON | ECHO);
        tcsetattr(0, TCSANOW, &newt);
        ch = getchar();
        tcsetattr(0, TCSANOW, &oldt);

        return cast(char) ch;
}

import std.utf;

char readChar()
{
    char[4] buffer;

    buffer[0] = getch();
    auto len = stride(buffer,0);

    foreach (i ; 1 .. len)
        buffer[i] = getch();

    size_t i;
    return cast(char) decode(buffer, i);
}
Sep 28 2012
parent "nazriel" <spam dzfl.pl> writes:
On Friday, 28 September 2012 at 09:45:30 UTC, Thomas Koch wrote:

 nazriel wrote:

 http://dpaste.dzfl.pl/eb1387cc


 Thank you. Your solution does not seem to work with multibyte 
 characters, so
 I extended it:


Nice, I didn't need multibyte support as I was using it mainly 
for getting keycode


 import core.sys.posix.termios;
 import core.stdc.stdio;

 char getch()
 {
         int ch;
         termios oldt;
         termios newt;

         tcgetattr(0, &oldt);
         newt = oldt;
         newt.c_lflag &= ~(ICANON | ECHO);
         tcsetattr(0, TCSANOW, &newt);
         ch = getchar();
         tcsetattr(0, TCSANOW, &oldt);

         return cast(char) ch;
 }

 import std.utf;

 char readChar()
 {
     char[4] buffer;

     buffer[0] = getch();
     auto len = stride(buffer,0);

     foreach (i ; 1 .. len)
         buffer[i] = getch();

     size_t i;
     return cast(char) decode(buffer, i);
 }


I think it should return dchar then, and cast(char) should be 
dropped otherwise you will lose visual representation of anything 
that is bigger than 8bits
Sep 28 2012
prev sibling parent Jacob Carlborg <doob me.com> writes:
On 2012-09-26 19:51, Thomas Koch wrote:

 Hi,

 to learn D, I'd like to write a simple type trainer. It should write a line
 to stdout and then read single characters from stdin and only accept the
 correct characters

 How can I read single characters?

 A similar question has been asked before without a working answer:
 http://forum.dlang.org/thread/jl79f7$2083$1 digitalmars.com


This works for me on Mac OS X:

http://forum.dlang.org/thread/jl79f7$2083$1 digitalmars.com?page=2#post-jlhn4d:241a5v:241:40digitalmars.com

-- 
/Jacob Carlborg
Sep 28 2012