www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.learn - Read non-UTF8 file

reply Nrgyzer <nrgyzer gmail.com> writes:
Hey guys,

I've the following source:

module filereader;

import std.file;
import std.stdio : writeln;

void main(string[] args) {
	File f = new File("myFile.ext", FileMode.In);
	while(!f.eof()) {
		writeln(convertToUTF8(f.readLine()));
	}
	f.close();
}

string convertToUTF8(char[] text) {
	string result;
	for (uint i=0; i<text.length; i++) {
		wchar ch = text[i];
		if (ch < 0x80) {
			result ~= ch;
		} else {
			result ~= 0xC0 | (ch >> 6);
			result ~= 0x80 | (ch & 0x3F);
		}
	}
	return result;
}

It compiles and works as long as the returned char-array/string of f.readLine()
doesn't contain non-UTF8 character(s). If it contains such
chars, writeln() doesn't write anything to the console. Is there any chance to
read such files?

Thanks a lot!
Feb 13 2011
parent reply Stewart Gordon <smjg_1998 yahoo.com> writes:
On 13/02/2011 21:49, Nrgyzer wrote:
<snip>

 It compiles and works as long as the returned char-array/string of
f.readLine() doesn't
 contain non-UTF8 character(s). If it contains such chars, writeln() doesn't
write
 anything to the console. Is there any chance to read such files?



Please post sample input that shows the problem, and the output generated by
replacing the 
writeln call with

     writefln("%s", cast(ubyte[]) convertToUTF8(f.readLine()));

so that we can see what it is actually reading in.

Stewart.
Feb 18 2011
next sibling parent reply Nrgyzer <nrgyzer gmail.com> writes:
== Auszug aus Stewart Gordon (smjg_1998 yahoo.com)'s Artikel

 On 13/02/2011 21:49, Nrgyzer wrote:
 <snip>

 It compiles and works as long as the returned char-array/string of
f.readLine() doesn't
 contain non-UTF8 character(s). If it contains such chars, writeln() doesn't
write
 anything to the console. Is there any chance to read such files?



 writeln call with
      writefln("%s", cast(ubyte[]) convertToUTF8(f.readLine()));
 so that we can see what it is actually reading in.
 Stewart.



My file contains the following:

ä
ö
ü

Now... and with writefln("%s", cast(ubyte[]) convertToUTF8(f.readLine())); I
get the following:

[195, 131, 164]
[195, 131, 182]
[195, 131, 188]
Feb 19 2011
next sibling parent Nrgyzer <nrgyzer gmail.com> writes:
== Auszug aus spir (denis.spir gmail.com)'s Artikel

 On 02/19/2011 02:42 PM, Nrgyzer wrote:

 == Auszug aus Stewart Gordon (smjg_1998 yahoo.com)'s Artikel

 On 13/02/2011 21:49, Nrgyzer wrote:
 <snip>

 It compiles and works as long as the returned char-array/string













 contain non-UTF8 character(s). If it contains such chars,













 anything to the console. Is there any chance to read such files?













 writeln call with
       writefln("%s", cast(ubyte[]) convertToUTF8(f.readLine()));
 so that we can see what it is actually reading in.
 Stewart.



 My file contains the following:

 �
 �
 �

 Now... and with writefln("%s", cast(ubyte[])







 [195, 131, 164]
 [195, 131, 182]
 [195, 131, 188]







 is common when representing converted latin text). But having 3




 131) which is the code for 'Ã' is weird.
 What is your source text, what is its encoding, and where does it




 What don't you /start/ and tell us about that?
 Denis



It seems that my input chars doesn't show correctly above... it
contains the following chars:

0xE4 (or 228), 0xF6 (or 246) and 0xFC (or 252)

I used notepad to create the file and saved it as ANSI encoding. The
file is for testing purposes only.
Feb 20 2011
prev sibling parent reply Stewart Gordon <smjg_1998 yahoo.com> writes:
What compiler version/platform are you using?  I had to fix some errors before
it would 
compile on mine (1.066/2.051 Windows).

On 19/02/2011 13:42, Nrgyzer wrote:
<snip>

 Now... and with writefln("%s", cast(ubyte[]) convertToUTF8(f.readLine())); I
get the following:

 [195, 131, 164]
 [195, 131, 182]
 [195, 131, 188]



It took a while for me to make sense of what's going on!

The expressions (0xC0 | (ch >> 6)) and (0x80 | (ch & 0x3F)) both have type int.
 It 
appears that, in D2, if you append an int to a string then it treats the int as
a Unicode 
codepoint and automagically converts it to UTF-8.  But why is it doing it on
the first 
byte and not the second?  This looks like a bug.

Casting each UTF-8 byte value to a char

     if (ch < 0x80) {
         result ~= cast(char) ch;
     } else {
         result ~= cast(char) (0xC0 | (ch >> 6));
         result ~= cast(char) (0x80 | (ch & 0x3F));
     }

gives the expected output

[195, 164]
[195, 182]
[195, 188]

HTH

Stewart.
Feb 21 2011
parent Nrgyzer <nrgyzer gmail.com> writes:
== Auszug aus Stewart Gordon (smjg_1998 yahoo.com)'s Artikel

 What compiler version/platform are you using?  I had to fix some errors before
it would
 compile on mine (1.066/2.051 Windows).
 On 19/02/2011 13:42, Nrgyzer wrote:
 <snip>

 Now... and with writefln("%s", cast(ubyte[]) convertToUTF8(f.readLine())); I
get the following:

 [195, 131, 164]
 [195, 131, 182]
 [195, 131, 188]



 The expressions (0xC0 | (ch >> 6)) and (0x80 | (ch & 0x3F)) both have type
int.  It
 appears that, in D2, if you append an int to a string then it treats the int
as a Unicode
 codepoint and automagically converts it to UTF-8.  But why is it doing it on
the first
 byte and not the second?  This looks like a bug.
 Casting each UTF-8 byte value to a char
      if (ch < 0x80) {
          result ~= cast(char) ch;
      } else {
          result ~= cast(char) (0xC0 | (ch >> 6));
          result ~= cast(char) (0x80 | (ch & 0x3F));
      }
 gives the expected output
 [195, 164]
 [195, 182]
 [195, 188]
 HTH
 Stewart.



I also wondered because I've used the same code in D1 and it worked without any
problems. Anyway... thanks :)
Feb 22 2011
prev sibling parent spir <denis.spir gmail.com> writes:
On 02/19/2011 02:42 PM, Nrgyzer wrote:

 == Auszug aus Stewart Gordon (smjg_1998 yahoo.com)'s Artikel

 On 13/02/2011 21:49, Nrgyzer wrote:
 <snip>

 It compiles and works as long as the returned char-array/string of
f.readLine() doesn't
 contain non-UTF8 character(s). If it contains such chars, writeln() doesn't
write
 anything to the console. Is there any chance to read such files?



 writeln call with
       writefln("%s", cast(ubyte[]) convertToUTF8(f.readLine()));
 so that we can see what it is actually reading in.
 Stewart.



 My file contains the following:

 �
 �
 �

 Now... and with writefln("%s", cast(ubyte[]) convertToUTF8(f.readLine())); I
get the following:

 [195, 131, 164]
 [195, 131, 182]
 [195, 131, 188]



At first sight, I find your input strange. Actually, it looks like utf-8 (195 
is common when representing converted latin text). But having 3 times (195, 
131) which is the code for 'Ã' is weird.
What is your source text, what is its encoding, and where does it come from? 
What don't you /start/ and tell us about that?

Denis
-- 
_________________
vita es estrany
spir.wikidot.com
Feb 19 2011