Why "global" variable can't be processed properly?
Tue Apr 28 14:24:00 GMT 2009
2009/4/28 Robin.Horde <email@example.com>:
> I have a question about "global" variable accessing when gcc compile some code. See example below:
> aiArray[iCurArrayIdx] = GetNewValue( aiArray[iCurArrayIdx] );
I'm not sure, but it feels like this is due to unspecified order of
evaluation. There's nothing that says that GetNewValue needs to be
evaluated before the aiArray + iCurArrayIdx in the LHS, so it's
probably the old use-and-modification between sequence points problem.
To put it another way, one compiler is doing this:
int t = GetNewValue( aiArray[iCurArrayIdx] );
aiArray[iCurArrayIdx] = t;
while the other is doing this:
int &t = aiArray[iCurArrayIdx];
t = GetNewValue( aiArray[iCurArrayIdx] );
and I don't know of anything that specifies that it's supposed to be
one or the other.
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