Re: [avr-gcc-list] integer overflow

[Bruce D. Lightner]

Ömer,

> i have an overflow warning from the compiler
> here is the code that makes the problem
> unsigned long val;
> 
> val = 1000*60*60*24;
> 
> i think the problem stems from the sizeof long , as far as i know long
> is 4 bytes for atmel processors and integer is 2 bytes.the maximum
> value for 4 bytes is
> 
> FFFFFFFF which is 4,294,967,295 that is bigger than 86,400,000.
> 
> if long is 2 bytes than is there a built in structure for carrying 4
> bytes ?

Try...

  val = 1000L*60*60*24;

"Ints" are 2 bytes with "avr-gcc".  Integer constant expressions therefore
use only 2 bytes, unless you somehow promote the expression evaluation to
use 4-byte longs.  Replacing 1000 by 1000L will cause this to happen. 

Best regards,

Bruce

P.S.- There are many other ways to do this, which I'm sure Joerg will soon
share with you...

-- 
 Bruce D. Lightner
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