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digitalmars.D.learn - Prompting using stdio

reply =?UTF-8?B?Ik5vcmRsw7Z3Ig==?= <per.nordlow gmail.com> writes:
I thought

int main(string[] args)
{
     import std.stdio;
     write(`Press enter to continue: `);
     stdout.flush;
     auto line = readln();
     writeln("Read ", line);
     return 0;
}

would function as a good prompting but it doesn't.

I outputs the string given to write *after* I've pressed return. 
Why?
Sep 28 2014
parent reply "H. S. Teoh via Digitalmars-d-learn" <digitalmars-d-learn puremagic.com> writes:
On Sun, Sep 28, 2014 at 02:16:29PM +0000, "Nordlöw" via Digitalmars-d-learn
wrote:

 I thought
 
 int main(string[] args)
 {
     import std.stdio;
     write(`Press enter to continue: `);
     stdout.flush;
     auto line = readln();
     writeln("Read ", line);
     return 0;
 }
 
 would function as a good prompting but it doesn't.
 
 I outputs the string given to write *after* I've pressed return. Why?


It's an OS limitation. If you're on Posix, you need to switch your
terminal to cbreak mode, otherwise the program doesn't actually receive
any data until after you press Return. I'm not sure what the Windows
equivalent is, but a similar thing happens there -- the input line is
buffered by the OS and the program doesn't see it until Return is
pressed.

You might be interested in Adam Ruppe's terminal.d library, that handles
such low-level details for you:

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


T

-- 
People who are more than casually interested in computers should have at least
some idea of what the underlying hardware is like. Otherwise the programs they
write will be pretty weird. -- D. Knuth
Sep 28 2014
parent reply "Marc =?UTF-8?B?U2Now7x0eiI=?= <schuetzm gmx.net> writes:
On Sunday, 28 September 2014 at 14:48:03 UTC, H. S. Teoh via 
Digitalmars-d-learn wrote:

 On Sun, Sep 28, 2014 at 02:16:29PM +0000, "Nordlöw" via 
 Digitalmars-d-learn wrote:

 I thought
 
 int main(string[] args)
 {
     import std.stdio;
     write(`Press enter to continue: `);
     stdout.flush;
     auto line = readln();
     writeln("Read ", line);
     return 0;
 }
 
 would function as a good prompting but it doesn't.
 
 I outputs the string given to write *after* I've pressed 
 return. Why?


 It's an OS limitation. If you're on Posix, you need to switch 
 your
 terminal to cbreak mode, otherwise the program doesn't actually 
 receive
 any data until after you press Return. I'm not sure what the 
 Windows
 equivalent is, but a similar thing happens there -- the input 
 line is
 buffered by the OS and the program doesn't see it until Return 
 is
 pressed.


That's not his problem though - he doesn't see "Press enter to 
continue" in the terminal before he enters text.

However, I can't reproduce it with DMD master on Linux, it works 
for me as intended.
Sep 28 2014
parent reply =?UTF-8?B?Ik5vcmRsw7Z3Ig==?= <per.nordlow gmail.com> writes:
On Sunday, 28 September 2014 at 15:36:17 UTC, Marc Schütz wrote:

 However, I can't reproduce it with DMD master on Linux, it 
 works for me as intended.


My fault. I was too clever and call the program through a wrapper 
to rdmd I call rdmd-dev containing




http://forum.dlang.org/thread/qvznmjdmdvkyyrkhbkgy forum.dlang.org

if type ddemangle &> /dev/null; then
     exec rdmd -L--export-dynamic -color=on -g -gs -debug $* 2>&1 
| ddemangle
else
     exec rdmd -L--export-dynamic -color=on -g -gs -debug $* 2>&1
fi

The piping to ddemangle messed things up...

Thanks anyway.
Sep 28 2014
parent reply =?UTF-8?B?Ik5vcmRsw7Z3Ig==?= <per.nordlow gmail.com> writes:
On Sunday, 28 September 2014 at 16:01:06 UTC, Nordlöw wrote:

 The piping to ddemangle messed things up...

 Thanks anyway.


Does anybody have a better solution to this? I would still like 
the linker error output be ddemangled...
Sep 28 2014
parent "Marc =?UTF-8?B?U2Now7x0eiI=?= <schuetzm gmx.net> writes:
On Sunday, 28 September 2014 at 16:02:44 UTC, Nordlöw wrote:

 On Sunday, 28 September 2014 at 16:01:06 UTC, Nordlöw wrote:

 The piping to ddemangle messed things up...

 Thanks anyway.


 Does anybody have a better solution to this? I would still like 
 the linker error output be ddemangled...


You can redirect stderr to ddemangle:

     rdmd ... 2> >( ddemangle )
Sep 28 2014