• Kai (18/18) May 12 2014 Hi I am trying to iterate over a mmfile (ubyte[]) and convert it
• Jonathan M Davis via Digitalmars-d-learn (12/29) May 12 2014 The problem is that the compiler isn't smart enough to realize that

"Kai" <trengere gmail.com> writes:

Hi I am trying to iterate over a mmfile (ubyte[]) and convert it 
to uint

void main(){
	MmFile inn = new MmFile("mmData.dat");
	ubyte[] arr = cast(ubyte[])inn[];
	for(ulong index = 0; index<arr.length; index+=4){
		ulong stop = index+4;	
		uint num  = littleEndianToNative!uint(arr[index..stop]);
	}
if i try to compile this i get the following error:
Error: template std.bitmanip.littleEndianToNative cannot deduce 
function from argument types !(uint)(ubyte[])

but if change the last line to:
uint num  = littleEndianToNative!uint(arr[30..34]);

then it compiles and runs...

Am I doing something wrong with my variables "index" and "stop"?
cheers
Kai T

Jonathan M Davis via Digitalmars-d-learn writes:

On Mon, 12 May 2014 20:12:41 +0000
Kai via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> wrote:

 Hi I am trying to iterate over a mmfile (ubyte[]) and convert it
 to uint

 void main(){
   MmFile inn = new MmFile("mmData.dat");
   ubyte[] arr = cast(ubyte[])inn[];
   for(ulong index = 0; index<arr.length; index+=4){
       ulong stop = index+4;
       uint num  =
 littleEndianToNative!uint(arr[index..stop]); }
 if i try to compile this i get the following error:
 Error: template std.bitmanip.littleEndianToNative cannot deduce
 function from argument types !(uint)(ubyte[])

 but if change the last line to:
 uint num  = littleEndianToNative!uint(arr[30..34]);

 then it compiles and runs...

 Am I doing something wrong with my variables "index" and "stop"?
 cheers

The problem is that the compiler isn't smart enough to realize that
arr[index .. stop] is guaranteed to result in a array with a length of 4.

auto num = littleEndianToNative!uint(cast(ubyte[4])arr[index..stop]);

would work. On a side note, if you wanted to be safer, you should probably use
uint.sizeof everyewhere instead of 4. that would also make it easier to
convert it to a different integral type. Also, you should be using size_t, not
ulong for the indices. Array indices are size_t, and while that's ulong on a
64-bit system, it's uint on a 32-bit system, so your code won't compile on a
32-bit system.

- Jonathan M Davis