Re: gEDA-user: pcb crooked traces

[Peter Clifton <pcjc2@xxxxxxxxx>]

On Wed, 2010-10-13 at 00:05 +0200, Karl Hammar wrote:

>  Why does
> 
> #include <stdio.h>
> int main(void) {
>  char cc = 0xc4 // 'Ã' in latin1
>  short str = cc;
>  printf("0x%04hx\n", str);
> }
> 
>  print 0xffc4 instead of 0x00c4 ?

It is because 0xc4 is inserted into a "char", not an "unsigned char",
and is in binary:

1100 0100

Which is a _negative_ number. (-60 in decimal)

The compiler will (correctly) sign-extend the assigned value in str when
performing the type conversion.


I wasn't sure this was a question you already knew the answer two or
not.. but it is certainly a nice example of why you have to be careful
mixing different types, and signed-ness in general.

-- 
Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA

Tel: +44 (0)7729 980173 - (No signal in the lab!)
Tel: +44 (0)1223 748328 - (Shared lab phone, ask for me)



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