Lynn Allan said (on or about) 11/11/2006 09:46:
UInt32 baseOffset = 4000000;
UInt32 testOffset = baseOffset + (30000 * 4); // 3988928
testOffset = baseOffset + ((UInt32)30000 * (UInt32)4); // 4120000
testOffset = baseOffset + (30000L * 4L); // 4120000
I'm using CW9.3 and seeing unexpected results when adding constants. I would
expect the 2nd, 3rd, and 4th statements to all result in testOffset being set
to 4,120,000, but the 2nd statement seems to treat the (30000*4) as Int16
numbers, and it becomes a negative number.
Is this a bug, or defined/expected behavior? Or am I confused?
This has thrown me off several times. Is there a setting to cause constants to
be treated as Int32?
The calculation (30000 * 4) is being done by the compiler
at compile time. I don't recall whether this is defined
by the language standard or left to be defined by the
compiler implementation. Either way, I would write my code
as if I expected that the constant 30000 would be forced
into the smallest signed type that could hold it and write
the code defensively to make sure that the result was what
I wanted it to be.
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