How do I read a byte array into an unsigned integer using little endian formatting? I know about the .read inside the std.bitmanip but I can't fingure out how to set it to little endian.

data.read!(uint, Endian.littleEndian)();

This gives me a huge compile message including the error at the top (without the candidates)

Error: template std.bitmanip.read does not match any function template declaration.

On 11/22/2013 11:10 AM, Jeroen Bollen wrote:
> How do I read a byte array into an unsigned integer using little endian
> formatting? I know about the .read inside the std.bitmanip but I can't
> fingure out how to set it to little endian.
>
> data.read!(uint, Endian.littleEndian)();
>
> This gives me a huge compile message including the error at the top
> (without the candidates)
>
> Error: template std.bitmanip.read does not match any function template
> declaration.

It looks like you need to include std.system for Endian's definition:

import std.bitmanip;
import std.system;

void main()
{
    ubyte[] data = [ 1, 2, 3, 4 ];
    assert(data.read!(uint, Endian.littleEndian) == 0x04030201);
}

Ali

On Friday, 22 November 2013 at 19:22:16 UTC, Ali Çehreli wrote:
> On 11/22/2013 11:10 AM, Jeroen Bollen wrote:
>> How do I read a byte array into an unsigned integer using little endian
>> formatting? I know about the .read inside the std.bitmanip but I can't
>> fingure out how to set it to little endian.
>>
>> data.read!(uint, Endian.littleEndian)();
>>
>> This gives me a huge compile message including the error at the top
>> (without the candidates)
>>
>> Error: template std.bitmanip.read does not match any function template
>> declaration.
>
> It looks like you need to include std.system for Endian's definition:
>
> import std.bitmanip;
> import std.system;
>
> void main()
> {
>     ubyte[] data = [ 1, 2, 3, 4 ];
>     assert(data.read!(uint, Endian.littleEndian) == 0x04030201);
> }
>
> Ali

I have std.system included... :s

On Friday, 22 November 2013 at 19:44:56 UTC, Jeroen Bollen wrote:
> On Friday, 22 November 2013 at 19:22:16 UTC, Ali Çehreli wrote:
>> import std.bitmanip;
>> import std.system;
>>
>> void main()
>> {
>>    ubyte[] data = [ 1, 2, 3, 4 ];
>>    assert(data.read!(uint, Endian.littleEndian) == 0x04030201);
>> }
>>
>> Ali
>
> I have std.system included... :s

What is the type of your "data"?

On Friday, 22 November 2013 at 19:10:24 UTC, Jeroen Bollen wrote:
> How do I read a byte array into an unsigned integer using little endian formatting? I know about the .read inside the std.bitmanip but I can't fingure out how to set it to little endian.
>
> data.read!(uint, Endian.littleEndian)();
>
> This gives me a huge compile message including the error at the top (without the candidates)
>
> Error: template std.bitmanip.read does not match any function template declaration.

I was going to suggest using a "raw" "formattedRead", eg "%-r", but apparently, that doesn't work for reading, only writing :/

//----
import std.format;
import std.stdio;

void main()
{
    int i = 0x04_03_02_01;
    auto app = appender!string();
    formattedWrite(app, "%-r", i);
    string s = app.data;
    writeln(cast(ubyte[])s); //Produces [1, 2, 3, 4]
    formattedRead(s, "%-r", &i); //Fails on -
    formattedRead(s, "%r", &i); //Fails on r
}
//----

That would be an interesting improvement. Raw formatted write is so awesome, raw formatted read would also be very cool.

On Friday, 22 November 2013 at 21:17:56 UTC, monarch_dodra wrote:
> On Friday, 22 November 2013 at 19:44:56 UTC, Jeroen Bollen wrote:
>> On Friday, 22 November 2013 at 19:22:16 UTC, Ali Çehreli wrote:
>>> import std.bitmanip;
>>> import std.system;
>>>
>>> void main()
>>> {
>>>   ubyte[] data = [ 1, 2, 3, 4 ];
>>>   assert(data.read!(uint, Endian.littleEndian) == 0x04030201);
>>> }
>>>
>>> Ali
>>
>> I have std.system included... :s
>
> What is the type of your "data"?

immutable ubyte[]

On 11/22/2013 02:55 PM, Jeroen Bollen wrote:> On Friday, 22 November 2013 at 21:17:56 UTC, monarch_dodra wrote:
>> On Friday, 22 November 2013 at 19:44:56 UTC, Jeroen Bollen wrote:
>>> On Friday, 22 November 2013 at 19:22:16 UTC, Ali Çehreli wrote:
>>>> import std.bitmanip;
>>>> import std.system;
>>>>
>>>> void main()
>>>> {
>>>>   ubyte[] data = [ 1, 2, 3, 4 ];
>>>>   assert(data.read!(uint, Endian.littleEndian) == 0x04030201);
>>>> }
>>>>
>>>> Ali
>>>
>>> I have std.system included... :s
>>
>> What is the type of your "data"?
>
> immutable ubyte[]

That means that the slice itself cannot be modified, meaning that it cannot be consumed by read. Can't work... :)

This would work though:

  immutable(ubyte)[]

However, if you really want your main data to be immutable, you can keep it as 'immutable ubyte[]' but you must take an lvalue slice of it to be passed to read:

import std.bitmanip;
import std.system;

void main()
{
    immutable ubyte[] mainData = [ 1, 2, 3, 4 ];
    auto dataSlice = mainData[];
    assert(dataSlice.read!(uint, Endian.littleEndian) == 0x04030201);
}

Ali

On Friday, 22 November 2013 at 23:12:25 UTC, Ali Çehreli wrote:
> That means that the slice itself cannot be modified, meaning that it cannot be consumed by read. Can't work... :)

Why does read need to be able to change the byte array?

On 11/23/2013 04:08 AM, Jeroen Bollen wrote:
> On Friday, 22 November 2013 at 23:12:25 UTC, Ali Çehreli wrote:
>> That means that the slice itself cannot be modified, meaning that it
>> cannot be consumed by read. Can't work... :)
>
> Why does read need to be able to change the byte array?

From the documentation: "The T.sizeof bytes which are read are consumed from the range."

  http://dlang.org/phobos/std_bitmanip.html#.read

When it comes to arrays, only slices that support popFront() are ranges.

Ali

On Saturday, 23 November 2013 at 15:21:02 UTC, Ali Çehreli wrote:
> On 11/23/2013 04:08 AM, Jeroen Bollen wrote:
>> On Friday, 22 November 2013 at 23:12:25 UTC, Ali Çehreli wrote:
>>> That means that the slice itself cannot be modified, meaning that it
>>> cannot be consumed by read. Can't work... :)
>>
>> Why does read need to be able to change the byte array?
>
> From the documentation: "The T.sizeof bytes which are read are consumed from the range."
>
>   http://dlang.org/phobos/std_bitmanip.html#.read
>
> When it comes to arrays, only slices that support popFront() are ranges.
>
> Ali

So if I have a byte array [0, 0, 1, 0], and I read a ushort from it twice, I will get this?

ubyte[] arr = [0, 0, 1, 0];
arr.read!(ushort, Endian.littleEndian); // == 0
arr.read!(ushort, Endian.littleEndian); // == 1
arr.length; // == 0