Microsoft KB Archive/205681

= FIX: Operator ++ In Return Statement May Cause Access Violation =

Article ID: 205681

Article Last Modified on 11/18/2003

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APPLIES TO


 * Microsoft Visual C++ 6.0 Enterprise Edition
 * Microsoft Visual C++ 6.0 Professional Edition
 * Microsoft Visual C++ 6.0 Standard Edition

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This article was previously published under Q205681



SYMPTOMS
A compiled program may cause access violation if it contains a function returning a struct by value, and the return expression has either a postfix increment or decrement operator.



RESOLUTION
There following are workarounds for this problem.


 * 1) Remove the postfix increment/decrement operator from the return expression.
 * 2) Use the prefix increment/decrement operator.



STATUS
Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.

This bug was corrected in Visual Studio 6.0 Service Pack 3. For more information about Visual Studio service packs, please see the following articles in the Microsoft Knowledge Base:

194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed



MORE INFORMATION
To reproduce the problem, build and run the following sample program.

Sample


 * 1) include 
 * 2) include 

typedef struct { int  type; int  offset; } ST;

int i;

struct { ST *tab; int used; } STAdmin;

ST MyFunction {  int temp = i++; return STAdmin.tab[temp];
 * 1) ifdef WORKAROUND_1
 * 1) endif

return STAdmin.tab[++i - 1];
 * 1) ifdef WORKAROUND_2
 * 1) endif

return STAdmin.tab[i++]; }

void main(void) {  ST a;   int i;

STAdmin.tab = (ST*) malloc(sizeof(ST)*10); STAdmin.used = 0;

// Initialize the Array for(i=0;i<10;i++) {      STAdmin.tab[i].offset=i; printf("%d\n",STAdmin.tab[i].offset); }

// Read in the Array for(i=0;i<10;i++) {   a = MyFunction; printf("%d\n",a.offset); } } // End of Sample Code

Additional query words: kbDSupport

Keywords: kbbug kbfix kbvs600sp3fix KB205681

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