Article: Q116240
Product(s): Microsoft C Compiler
Version(s): 1.0,1.5,2.0,4.0,4.1,4.2,5.0,6.0
Operating System(s):
Keyword(s): kbCompiler kbCPPonly kbVC kbVC100bug kbVC150bug kbVC200bug kbVC400bug kbVC410bug kbVC42
Last Modified: 11-FEB-2002
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The information in this article applies to:
- The C/C++ Compiler (CL.EXE), used with:
- Microsoft C/C++ for MS-DOS
- Microsoft Visual C++ for Windows, 16-bit edition, versions 1.0, 1.5
- Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0, 4.0, 4.1, 4.2, 5.0, 6.0
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SYMPTOMS
========
Initializing a "const" reference to an array with a "non-const" array causes
incorrect compiler errors to be generated. Two such errors are C2607 and C2561.
CAUSE
=====
The C++ compiler does not properly handle initialization of a "const T&",
where T is an array. For example, you should be able to initialize a variable of
type "const float (&ref)[3][2]" with a variable of type "float [3][2]", but
the compiler does not handle this case. Furthermore, interactions between const
declarations and typedefs of arrays do not work in all circumstances.
RESOLUTION
==========
To work around the problem, either do not use the const specifier or add
explicit casts to the appropriate const types.
STATUS
======
Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.
This problem was corrected in Microsoft Visual C++ .NET.
MORE INFORMATION
================
The sample code below demonstrates the problem. Compiling it yields at least one
of the following error messages:
error C2607: 'initializing' : cannot implicitly convert a 'int [3][2]' to a
'int __near &[3][2]' that is not const
error C2561: 'getMtx' : function must return a value
To work around the problem, use each commented line in the program to replace the
line immediately above it.
Note: Simply removing the const specifier from the getMtx function's return type
eliminates the problem.
Sample Code
-----------
/* Compile options needed: none
*/
typedef int Matrix[3][2];
class Data
{
Matrix Mtx;
const Matrix& getMtx();
// const int (&getMtx() const)[3][2];
};
inline const Matrix& Data::getMtx()
// inline const int (&Data::getMtx() const)[3][2]
{
return Data::Mtx;
// return (const int (&)[3][2])Data::Mtx[0][0];
}
Additional query words: kbVC400bug 8.00 8.00c 9.00
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Keywords : kbCompiler kbCPPonly kbVC kbVC100bug kbVC150bug kbVC200bug kbVC400bug kbVC410bug kbVC420bug kbVC500bug kbVC600bug kbNoUpdate
Technology : kbVCsearch kbAudDeveloper kbCVCComp
Version : :1.0,1.5,2.0,4.0,4.1,4.2,5.0,6.0
Issue type : kbbug
Solution Type : kbfix
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