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amohr

fairly serious bug when using longs

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I had to implement a function called get_bit because I couldn't implement it as a macro since the compiler support for longs is so weak.  The problem I found is that it's treating the long parameter as a reference!  Which means that if I modify the parameter value in the function it's reflected in the caller's copy...i.e.

 

char get_bit(unsigned long x, char y) {

char i;

 

for(i=0; i<y; i++)

  x >>= 1;

 

x &= 1;

 

return x;

}

 

   long i = 1;     // i == 1

   get_bit(i, 2);  

                     // i now == 0 !!!

 

eeeeeeeee

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Guest Pavel

Can't reproduce the problem. The variable does not get changed in caller. If you still see this problem send me a zipped projects and descriptions what to do to reproduce it.

 

Regards,

Pavel

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shouldn't you cast the variable x to a char?

 

your returnvalue is a char, but the value x is unsigned long.

 

Regards,

Pim

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