• baws (33/33) May 29 2013 Im trying to learn D, lovely language for a C++ lover. I have a
• baws (3/36) May 29 2013 Oh clap guys, sorry for wasting time, I just noticed the
• Adam D. Ruppe (11/15) May 29 2013 You're reading the file correctly, just not printing it all out
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (4/9) May 29 2013 There is also the nested array formatting. Pretty cool but dyslecix! :)
• bearophile (11/12) May 29 2013 But usually I prefer to show all the zero nibbles:
• bearophile (3/10) May 29 2013 I have pasted the outputs inverted, sorry.
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (3/7) May 29 2013 And only then the output would make sense. Thanks. :)
• baws (25/58) May 29 2013 Erhm, why isnt this compiling guys? all i did was add your
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (11/13) May 29 2013 Your code compiles here with dmd 2.062 and v2.063-devel-f6d55a9-dirty.

"baws" <blaquee gmail.com> writes:

Im trying to learn D, lovely language for a C++ lover. I have a 
file Im trying to parse, but I need to read the contents as 
binary data. I also need help understanding how read() works. I'd 
like to read the first four bytes which identify the file header, 
I need it to show as a sequence of bytes, how can i output the 
first 4 bytes to show like 0xFFCF?

With my code, im getting the integer values, If i use 
cast(byte[]) on read and writefln("Reading header info: 0x%x", 
bytesRead[0]);

Ill only get the first byte 0xCF.


import std.stdio;
import std.file;
import std.array;

struct xsdhead{
     int head1;
     int head2;
     int numTables;
};

immutable int headerInfo1 = 0xFFCF;
immutable int headerInfo2 = 0x0002;

int main(string [] args){
     writeln("start");
     if(args[1] == null){
         writeln("pass a file");
         return 0;
     }
     auto file = args[1];
     writeln("Working on ", file);

     auto bytesRead =  cast(byte[]) read(file, 4);
     writefln("Reading header info: %s", bytesRead);
     writefln("Address of caret is: 0x%X", &bytesRead);

     return 0;
}

"baws" <blaquee gmail.com> writes:

On Wednesday, 29 May 2013 at 22:03:24 UTC, baws wrote:
 Im trying to learn D, lovely language for a C++ lover. I have a 
 file Im trying to parse, but I need to read the contents as 
 binary data. I also need help understanding how read() works. 
 I'd like to read the first four bytes which identify the file 
 header, I need it to show as a sequence of bytes, how can i 
 output the first 4 bytes to show like 0xFFCF?

 With my code, im getting the integer values, If i use 
 cast(byte[]) on read and writefln("Reading header info: 0x%x", 
 bytesRead[0]);

 Ill only get the first byte 0xCF.


 import std.stdio;
 import std.file;
 import std.array;

 struct xsdhead{
     int head1;
     int head2;
     int numTables;
 };

 immutable int headerInfo1 = 0xFFCF;
 immutable int headerInfo2 = 0x0002;

 int main(string [] args){
     writeln("start");
     if(args[1] == null){
         writeln("pass a file");
         return 0;
     }
     auto file = args[1];
     writeln("Working on ", file);

     auto bytesRead =  cast(byte[]) read(file, 4);
     writefln("Reading header info: %s", bytesRead);
     writefln("Address of caret is: 0x%X", &bytesRead);

     return 0;
 }

Oh clap guys, sorry for wasting time, I just noticed the 
std.stdio.File library! Ill come back to this later!

"Adam D. Ruppe" <destructionator gmail.com> writes:

On Wednesday, 29 May 2013 at 22:03:24 UTC, baws wrote:
 With my code, im getting the integer values, If i use 
 cast(byte[]) on read and writefln("Reading header info: 0x%x", 
 bytesRead[0]);

You're reading the file correctly, just not printing it all out 
in hex.

     writefln("Reading header info: %s", bytesRead);

this line should be printing the right data, just in decimal 
notation instead of hex. If you do the %x with one byte at a time 
you'll probably get the output you want:

         byte[] a = [10, 16, 32, 123];
         writef("0x");
         foreach(b; a)
             writef("%x", b);
         writef("\n");

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 05/29/2013 03:23 PM, Adam D. Ruppe wrote:

          byte[] a = [10, 16, 32, 123];
          writef("0x");
          foreach(b; a)
              writef("%x", b);
          writef("\n");

There is also the nested array formatting. Pretty cool but dyslecix! :)

     writefln("0x%(%x%)", a);

Ali

"bearophile" <bearophileHUGS lycos.com> writes:

Ali Çehreli:

     writefln("0x%(%x%)", a);

But usually I prefer to show all the zero nibbles:

void main() {
     import std.stdio;
     ubyte[] a = [10, 16, 32, 123];
     writefln("0x%(%02x%)", a); // Output: 0xa10207b
     static assert(is(typeof(a[0]) == ubyte), "Only ubyte[]");
     writefln("0x%(%x%)", a);   // Output: 0x0a10207b
}

Bye,
bearophile

"bearophile" <bearophileHUGS lycos.com> writes:

 void main() {
     import std.stdio;
     ubyte[] a = [10, 16, 32, 123];
     writefln("0x%(%02x%)", a); // Output: 0xa10207b
     static assert(is(typeof(a[0]) == ubyte), "Only ubyte[]");
     writefln("0x%(%x%)", a);   // Output: 0x0a10207b
 }

I have pasted the outputs inverted, sorry.

Bye,
bearophile

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 05/29/2013 04:11 PM, bearophile wrote:

 Ali Çehreli:

     writefln("0x%(%x%)", a);

 But usually I prefer to show all the zero nibbles:

      writefln("0x%(%02x%)", a); // Output: 0xa10207b

And only then the output would make sense. Thanks. :)

Ali

"baws" <blaquee gmail.com> writes:

On Wednesday, 29 May 2013 at 22:03:24 UTC, baws wrote:
 Im trying to learn D, lovely language for a C++ lover. I have a 
 file Im trying to parse, but I need to read the contents as 
 binary data. I also need help understanding how read() works. 
 I'd like to read the first four bytes which identify the file 
 header, I need it to show as a sequence of bytes, how can i 
 output the first 4 bytes to show like 0xFFCF?

 With my code, im getting the integer values, If i use 
 cast(byte[]) on read and writefln("Reading header info: 0x%x", 
 bytesRead[0]);

 Ill only get the first byte 0xCF.


 import std.stdio;
 import std.file;
 import std.array;

 struct xsdhead{
     int head1;
     int head2;
     int numTables;
 };

 immutable int headerInfo1 = 0xFFCF;
 immutable int headerInfo2 = 0x0002;

 int main(string [] args){
     writeln("start");
     if(args[1] == null){
         writeln("pass a file");
         return 0;
     }
     auto file = args[1];
     writeln("Working on ", file);

     auto bytesRead =  cast(byte[]) read(file, 4);
     writefln("Reading header info: %s", bytesRead);
     writefln("Address of caret is: 0x%X", &bytesRead);

     return 0;
 }

Erhm, why isnt this compiling guys? all i did was add your 
suggestions... :/

import std.stdio;
import std.file;
import std.array;

struct xsdhead{
     int head1;
     int head2;
     int numTables;
};

immutable int headerInfo1 = 0xFFCF;
immutable int headerInfo2 = 0x0002;

int main(string [] args){
     writeln("start");
     if(!args[1]){
         writeln("pass a file");
         return 0;
     }
     auto file = args[1];
     writeln("Working on: ", file);

     auto bytesRead =  cast(byte[])read(file, 4);
     writefln("Reading header info: 0x%(%02x%)", bytesRead);

     return 0;
}

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 05/29/2013 09:00 PM, baws wrote:

 Erhm, why isnt this compiling guys? all i did was add your
 suggestions... :/

Your code compiles here with dmd 2.062 and v2.063-devel-f6d55a9-dirty. 
What is the compiler error in your case?

The program has a run time error though: args[1] is an invalid access 
when args has only one element. Also, you are making an incorrect 
assumption: Unlike C, the last element of args is not null; such an 
element simply does not exist. You need a check like this:

     if (args.length != 2) {
         // ...
     }

Ali