Re: Porting from VC6 to VS2005

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"AVee" <AVee@xxxxxxxxxxxxxxxx> ha scritto nel messaggio news:%23GLBX7KIJHA.4240@xxxxxxxxxxxxxxxxxxxxxxx

In the mean time, I am interested in the loop scoping differences. Do you have a link to some info that you could quickly include?

I think that David refers to this:

Sample code snippet:

for ( int i = 0; i < N; i++ )
{
....
}

printf( "i = %d\n", i );

In VC6, the loop index 'i' has a scope outside the for loop, and you can use 'i' value like in printf above.
i.e. the above code is like this:

int i;
for ( i = 0; i < N; i++ )
...
printf( "i = %d\n", i );

Instead, new C++ standard considers 'i' as having a scope inside for loop, such that the initial for code corresponds to something like this:

{
int i;
for ( i = 0; i < N; i++ )
...
}
// You can't use 'i' here
printf( "i = %d\n", i ); // <<-- error

The new C++ standard allows you to write code like this:

for ( int i = 0; i < N; i++ )
...

for ( int i = 0; i < M; i++ )
...

for ( int i = 0; i < L; i++ )
...

because 'i' does not exist anymore when each of the for loop terminates.
Instead, you could not write code like this with VC6: you hade 'i' redefinition error.

HTH,
Giovanni


.

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