• bellinom (9/9) Aug 25 2011 Hello,
• Jonathan M Davis (5/16) Aug 25 2011 I would point out that www.ideone.com is horribly out of date. It uses d...
• bellinom (4/4) Aug 25 2011 Thanks for that, I didn't realize they were that far out of date. I use ...
• Jonathan M Davis (22/25) Aug 25 2011 That's probably not something that has changed, but many bugs have been ...
• Timon Gehr (20/24) Aug 25 2011 current ways
• Timon Gehr (3/28) Aug 25 2011 whoops, this is better:
• Joel Christensen (6/10) Aug 25 2011 Or,
• Timon Gehr (2/14) Aug 25 2011 ... good catch.
• Andrej Mitrovic (6/6) Aug 26 2011 to!(T[]) is awesome.
• Trass3r (13/15) Aug 25 2011 A nifty way of reading by byte is the undocumented (only the writer is
• Trass3r (1/2) Aug 25 2011 Of course I mean by character.

bellinom <bellinom nsuok.edu> writes:

Hello,

I'm in the process of learning D, and I have some questions about reading from
stdin. I've checked out the documentation but it's really not helping too
much. I'd like to know how to read from stdin one character at a time, read
with whitespace as a delimiter, and read line by line. Essentially just the
equivalents of cin.get(), cin >>, and cin.getline(). At the momoent I'm using
the D compiler on www.ideone.com, which I assume uses Phobos.

Thanks in advance for any help.

Malcolm

"Jonathan M Davis" <jmdavisProg gmx.com> writes:

On Thursday, August 25, 2011 10:49 bellinom wrote:
 Hello,
 
 I'm in the process of learning D, and I have some questions about reading
 from stdin. I've checked out the documentation but it's really not helping
 too much. I'd like to know how to read from stdin one character at a time,
 read with whitespace as a delimiter, and read line by line. Essentially
 just the equivalents of cin.get(), cin >>, and cin.getline(). At the
 momoent I'm using the D compiler on www.ideone.com, which I assume uses
 Phobos.
 
 Thanks in advance for any help.

I would point out that www.ideone.com is horribly out of date. It uses dmd 
2.042, while the latest version is 2.054. So, some stuff will not work there 
in the same way that they work with the latest release.

- Jonathan M Davis

bellinom <bellinom nsuok.edu> writes:

Thanks for that, I didn't realize they were that far out of date. I use the
latest
version of the compiler on my home PC, so I'd like to know the most current ways
of reading from stdin.

Thanks

"Jonathan M Davis" <jmdavisProg gmx.com> writes:

On Thursday, August 25, 2011 14:34 bellinom wrote:
 Thanks for that, I didn't realize they were that far out of date. I use the
 latest version of the compiler on my home PC, so I'd like to know the most
 current ways of reading from stdin.

That's probably not something that has changed, but many bugs have been fixed, 
and whole modules have been added or deprecated since 2.042, so it does affect 
a lot of stuff.

As for exactly how to read from stdin, it's not something that I normally do, 
so I'm not particularly well-versed in it, but stdin is a std.stdio.File with 
read-only access, so all of the std.stdio.File operations which read from the 
file should work. readln reads in a single line, and I believe that there's a 
version of it in stdio's module scope, so readln by itself should work rather 
than needing stdin.readln. If you want to read in a particular type, then 
std.stdio.File.rawRead would be what you would use, I believe, and you can 
probably use that to read a single character if you want to, but I don't know. 
There's also readf, which is similar to C's scanf.

All in all, I'd suggest reading the documentation for std.stdio ( http://d-
programming-language.org/phobos/std_stdio.html ) and playing around with it a 
bit, though perhaps someone who is actually familiar with reading from stdin 
could provide better insight. Personally, the closest that I normally get to 
operating on stuff from stdin is by operator on program arguments. Most of my 
programs which operate on I/O, operate on files, and I usually just use 
std.file.readText for that, since it's nice and simple. But that won't work 
for stdin.

- Jonathan M Davis

Timon Gehr <timon.gehr gmx.ch> writes:

On 08/25/2011 11:34 PM, bellinom wrote:
 Thanks for that, I didn't realize they were that far out of date. I 

use the latest
 version of the compiler on my home PC, so I'd like to know the most 

current ways
 of reading from stdin.

 Thanks

Currently what you get is readf and readln with std.conv.to, and if you 
need speed for formatted reads, use the C function scanf.


Some examples:

import std.stdio;

read a single line:

string r=readln();

read array of whitespace-delimited integers on a single line:

auto arr=to!(int[])(strip!(readln()));

read all of stdin by line:

foreach(s; stdin.byLine){
     // s is the current line
}

int i;
readf(" %s",&i); // read i, skipping leading whitespace

with readf, you can always use %s in your format strings.

Don't use readf if you care for performance, because the current 
implementation is very slow.

Timon Gehr <timon.gehr gmx.ch> writes:

On 08/26/2011 12:19 AM, Timon Gehr wrote:
 On 08/25/2011 11:34 PM, bellinom wrote:
  > Thanks for that, I didn't realize they were that far out of date. I
 use the latest
  > version of the compiler on my home PC, so I'd like to know the most
 current ways
  > of reading from stdin.
  >
  > Thanks

 Currently what you get is readf and readln with std.conv.to, and if you
 need speed for formatted reads, use the C function scanf.


 Some examples:

 import std.stdio;

 read a single line:

 string r=readln();

 read array of whitespace-delimited integers on a single line:

 auto arr=to!(int[])(strip!(readln()));

whoops, this is better:

auto arr=to!(int[])(split(strip!(readln())));

 read all of stdin by line:

 foreach(s; stdin.byLine){
 // s is the current line
 }

 int i;
 readf(" %s",&i); // read i, skipping leading whitespace

 with readf, you can always use %s in your format strings.

 Don't use readf if you care for performance, because the current
 implementation is very slow.

Joel Christensen <joelcnz gmail.com> writes:

On 26-Aug-11 10:20 AM, Timon Gehr wrote:
 On 08/26/2011 12:19 AM, Timon Gehr wrote:
 On 08/25/2011 11:34 PM, bellinom wrote:

 whoops, this is better:

 auto arr=to!(int[])(split(strip!(readln())));

Or,
auto arr2=to!(int[])( readln.strip.split );

Got rid of the second ! too (does not work with it). I not sure about 
having no () for 3 of the functions though.

- Joel

Timon Gehr <timon.gehr gmx.ch> writes:

On 08/26/2011 06:12 AM, Joel Christensen wrote:
 On 26-Aug-11 10:20 AM, Timon Gehr wrote:
 On 08/26/2011 12:19 AM, Timon Gehr wrote:
 On 08/25/2011 11:34 PM, bellinom wrote:

 whoops, this is better:

 auto arr=to!(int[])(split(strip!(readln())));

 Or,
 auto arr2=to!(int[])( readln.strip.split );

 Got rid of the second ! too (does not work with it). I not sure about
 having no () for 3 of the functions though.

 - Joel

... good catch.

Andrej Mitrovic <andrej.mitrovich gmail.com> writes:

to!(T[]) is awesome.

I've ported this little C thingy:
sscanf(oneline, "%f %f %f %f %f", &x, &y, &z, &u, &v);

to this:
to!(float[])(line.split);

Can't get easier than that!

Trass3r <un known.com> writes:

 I'd like to know how to read from stdin one character at a time, read  
 with whitespace as a delimiter, and read line by line.

A nifty way of reading by byte is the undocumented (only the writer is  
documented):

import std.stdio;
void main()
{
     foreach(c; LockingTextReader(stdin))
         ....
}

by line is
     foreach(c; stdin.byLine)

and you should also be able to abuse the function to split by whitespace:
http://d-programming-language.org/phobos/std_stdio.html#ByLine
See the terminator parameter.

Trass3r <un known.com> writes:

 A nifty way of reading by byte is

Of course I mean by character.