struct.unpack on 64-bit platforms

[Nadav Samet]

Hi,

I am trying to unpack a 32-bit unsigned integer from a string using
struct.unpack.
so using string.unpack('L', data) would work fine on 32-bit systems,

But apparently, on 64-bit platforms it tries to read 64-bit unsigned
integer (since
that's what the C Type unsigned long means on 64-bit platforms).

So what's the way to make it read exactly 32-bits, on all platforms?

Thanks,
Nadav

 

[Georg Brandl]

Hi,

I am trying to unpack a 32-bit unsigned integer from a string using
struct.unpack.
so using string.unpack('L', data) would work fine on 32-bit systems,

But apparently, on 64-bit platforms it tries to read 64-bit unsigned
integer (since
that's what the C Type unsigned long means on 64-bit platforms).

So what's the way to make it read exactly 32-bits, on all platforms?

Looking into the docs, prepending your format string with "=" should
make "L" exactly 32 bits on each platform.

Georg

 

[Jorgen Grahn]

But apparently, on 64-bit platforms it tries to read 64-bit unsigned
integer (since
that's what the C Type unsigned long means on 64-bit platforms).

On /some/ 64-bit platforms. Others let unsigned long be 32-bit and introduce
the 64-bit 'long long' types (and 64-bit pointers).

The term "64-bit", like "32-bit" before it, is too vague to use in technical
discussions, IMHO.

/Jorgen