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Unsigned usage?

Posted on 1999-01-14
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Last Modified: 2010-04-15
Hi,
  I am not sure what is unsigned char used for???
While I know when to differentiate usage of unsigned int/long and signed int/long, I don't see when to use unsigned and signed char? Can anybody explain to me in detial how to use unsigned and signed char (or generally) and when to use ..?

Thanks in advance
Thanks
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Question by:thiamwah
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5 Comments
 
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Accepted Solution

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Mirkwood earned 60 total points
ID: 1255893
An unsigned char is mostly referred to as a BYTE.
Its range goes from 0-255 while is signed char is
-128 to 127.
It all has to do how a the value should be interpreted by the compiler when converting it to e.g. a long and when the compiler reaches an overflow.

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Expert Comment

by:ozo
ID: 1255894
also relational operators
(and unsigned types never overflow)
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Author Comment

by:thiamwah
ID: 1255895
"It all has to do how a the value should be interpreted by the compiler when converting it to e.g. a long "
can u give an example? A simple one would suffice. :)
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LVL 13

Expert Comment

by:Mirkwood
ID: 1255896
char t1;
unsigned char t2;
long l1;
long l2;

t1 = 127;
t2 = 127;
t1 *= 2;
t2 *= 2;
l1 = t1;
l2 = t2;
---
Result:
l1 gives either an overflow or becomes -2 (I think) or given an overflow.
l2 becomes 254

Bitwise shift operations give also nice results.


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Author Comment

by:thiamwah
ID: 1255897
thanks!

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