Reading and converting binary file 2 bits at a time
Andrew Brown via Digitalmars-d-learn
digitalmars-d-learn at puremagic.com
Thu Aug 27 02:38:50 PDT 2015
On Thursday, 27 August 2015 at 09:26:55 UTC, rumbu wrote:
> On Thursday, 27 August 2015 at 09:00:02 UTC, Andrew Brown wrote:
>> Hi,
>>
>> I need to read a binary file, and then process it two bits at
>> a time. But I'm a little stuck on the first step. So far I
>> have:
>>
>> import std.file;
>> import std.stdio;
>>
>> void main(){
>> auto f = std.file.read("binaryfile");
>> auto g = cast(bool[]) f;
>> writeln(g);
>> }
>>
>> but all the values of g then are just true, could you tell me
>> what I'm doing wrong? I've also looked at the bitmanip module,
>> I couldn't get it to help, but is that the direction I should
>> be looking?
>>
>> Thanks very much
>>
>> Andrew
>
> auto bytes = cast(ubyte[])read("binaryfile");
> foreach(b; bytes)
> {
> writeln((b & 0xC0) >> 6); //bits 7, 6
> writeln((b & 0x30) >> 4); //bits 5, 4
> writeln((b & 0x0C) >> 2); //bits 3, 2
> writeln((b & 0x03)); //bits 1, 0
> }
That's lovely, thank you. One quick question, the length of the
file is not a multiple of the length of ubyte, but the cast
still seems to work. Do you know how it converts a truncated
final section?
Thanks again
Andrew
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