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coder0xff
Starting Member
1 Posts |
 Posted - Mar 17 2005 : 3:53:36 PM
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When I declare a __gc array :
System::Drawing::Bitmap* conditionalLayers __gc[];
VA X doesn't seem to consider this a declaration, and underlines 'conditionalLayers' in red. It doesn't appear in the suggestion list. If I remove the '__gc[]' it is fine. |
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"Two things are infinite: the universe and human stupidity; and Im not sure about the universe. -- Albert Einstein" |
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feline
Whole Tomato Software
United Kingdom
19020 Posts |
Posted - Mar 20 2005 : 5:04:26 PM
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this looks like it could be managed C++ code, going by the namespace usage.
what is this line doing? i have learned some C# so i know a small amount about .NET programming. however i don't recognise what this code is doing.
i am not finding any reference to "conditionalLayers" in the .NET documentation. |
zen is the art of being at one with the two'ness |
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jpizzi
Tomato Guru
USA
642 Posts |
Posted - Mar 20 2005 : 7:02:12 PM
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| conditionalLayers is his variable name. __gc[] is a garbage collected array. Can't tell if this is C# or managed C++, though. |
Joe Pizzi |
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jorgito11
Senior Member
USA
29 Posts |
Posted - Mar 21 2005 : 3:56:20 PM
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The code is managed C++ (MC++). coder0xff is creating a managed array. A managed array has two types (in this case, Bitmap and the Array types). "StringBuilder* sb[] = new StringBuilder*[3];" and "StringBuilder* sb __gc[] = __gc new StringBuilder*[3];" are essentially the same except the intellisense does not recognize the second one. Either "__gc" can be removed without causing a compiling error.
However, since types such as "int" that can be interpreted as a __value type or unmanaged POD, you are forced to use __gc:
int i __gc[] = {1, 2, 3}; // Intellisense is confused!
However, this is okay:
Int32 i[] = {1, 2, 3}; // Intellisense is working here!
since "Int32" is only a __value type.
Most MC++ programmers will use "int" before using "Int32"!
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Edited by - jorgito11 on Mar 21 2005 3:58:15 PM |
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feline
Whole Tomato Software
United Kingdom
19020 Posts |
Posted - Mar 21 2005 : 5:00:28 PM
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interesting. obviously there is a lot more to the basic types in .NET than i had realised.
case=534
experimenting with this i am getting errors when i try the line:
String *testArray __gc[];
in C#, while it compiles quite happily in managed C++. does this mean this idea only applies to managed C++? |
zen is the art of being at one with the two'ness |
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jorgito11
Senior Member
USA
29 Posts |
Posted - Mar 24 2005 : 11:55:40 AM
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Yes, this only applies to Managed C++ because MC++ can have managed and unmanaged code living together. The code,
String *testArray[], has an implied __gc before the "[]" because the type is managed. However, CString *strArray[] has no implied __gc since the type is definitely unmanaged. However, int i[] is ambiguous since it can be a managed array of Int32 __value types or an unmanaged array of POD integers. The C# compiler and itellisense does not have to worry about this difference since everything is managed.
C++/CLI in VS.NET 2005 has a new syntax to address this since it is very confusing for the developer to sort out what is managed and unmanaged. |
Edited by - jorgito11 on Apr 01 2005 11:57:37 AM |
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feline
Whole Tomato Software
United Kingdom
19020 Posts |
Posted - Mar 28 2005 : 2:24:48 PM
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*ah* i now recall reading an article about the new syntax for pointers in .NET 2005 for managed C++, but i had not started learning C# at the time i read it, and it made very little sense. now it makes a lot more sense, thank you for the explanation  |
zen is the art of being at one with the two'ness |
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