Microsoft KB Archive/131322

= Error message in Visual C++ when you delete a pointer to a const object: =

Article ID: 131322

Article Last Modified on 12/9/2005

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APPLIES TO


 * Microsoft Visual C++ 1.0 Professional Edition
 * Microsoft Visual C++ 1.5 Professional Edition
 * Microsoft Visual C++ 1.51
 * Microsoft Visual C++ 1.52 Professional Edition
 * Microsoft Visual C++ 1.0 Professional Edition
 * Microsoft Visual C++ 2.0 Professional Edition
 * Microsoft Visual C++ 2.1
 * Microsoft Visual C++ 4.0 Standard Edition
 * Microsoft Visual C++ 5.0 Enterprise Edition
 * Microsoft Visual C++ 6.0 Enterprise Edition
 * Microsoft Visual C++ 5.0 Professional Edition
 * Microsoft Visual C++ 6.0 Professional Edition
 * Microsoft Visual C++ 6.0 Standard Edition
 * Microsoft Visual C++ .NET 2003 Standard Edition
 * Microsoft Visual C++ .NET 2002 Standard Edition
 * Microsoft Visual C++ 2005 Express Edition

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This article was previously published under Q131322



SYMPTOMS
Attempting to delete a pointer to a constant causes the compiler to generate the following correct error message:

Error C2710 : cannot delete a pointer to a const object

NOTE: Visual C++ .NET compiler does not demonstrate this issue in conformance to the changes made in the C++ ANSI Standards.



CAUSE
Deleting a pointer to a constant should not be allowed by definition (ARM section 5.3.4) because it modifies the object pointed to. However, if you deliberately or accidentally use the explicit conversion, the compiler doesn't generate the error. The consequences of a such attempt are unpredictable and compiler implementation dependent.



STATUS
This behavior is by design.



Sample Code #1 to Demonstrate Behavior
/* No special compile options needed. */

const int * pi  = new int(1000); const char * pch = new char(65);

void main(void) { delete  pi  ;// Error C2710:cannot delete a pointer to a const object delete pch ;// Error C2710:cannot delete a pointer to a const object } Visual C++ version 5.0 and 6.0 generate the following error:

Error C2664: 'delete' : cannot convert parameter 1 from 'const char *' to 'void *'

Sample Code #2 to Demonstrate Behavior
/* No special compile options needed. The type casting of the pointer to const argument of the delete operator prevents the C2710 error but is not recommended. */

const int * pi  = new int(1000); const char * pch = new char(65);

void main(void) {  delete (int *) pi;   //no error C2710 generated delete (char *) pch; //no error C2710 generated

}

