Microsoft KB Archive/116446

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FIX: sizeof Gives Incorrect Size for Based Structure Pointers

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Q116446

1.00 WINDOWS kbprg kbfixlist kbbuglist - The information in this article applies to: - The Microsoft C/C++ Compiler (CL.EXE) included with: - Microsoft Visual C++ for Windows, version 1.0 - SYMPTOMS ======== The sizeof macro returns an incorrect size for based structure pointers in C++ code under the compact-memory, large-memory, and huge-memory models. In C code, sizeof returns 2 bytes for a based structure pointer, but the return value is 4 bytes in C++ code. STATUS ====== Microsoft has confirmed this to be a problem with the C/C++ Compiler for MS- DOS, version 8.0. This problem was corrected with the C/C++ Compiler for MS- DOS, version 8.0c that was included with Visual C++ for Windows, version 1.5. MORE INFORMATION ================ You can use the sample code below to reproduce this problem. If you compile the example as a C++ file, sizeof(t.left) returns 4 bytes and sizeof(test) returns 2 bytes. In a C file, both expressions return 2 bytes. Sample Code --- /* Compile options needed: /AL (/AC or /AH) */ #include typedef struct tree TREE; struct tree { int name; TREE __based( (__segment)__self ) *next; }; int __based((__segment)__self) *test; void main(void) { struct tree t; t.name = 1; printf("sizeof(t) = %d bits\n", sizeof(t) * 8); printf("sizeof(t.name) = %d bits\n", sizeof(t.name) * 8); printf("sizeof(t.name) = %d bits\n", sizeof(t.next) * 8); printf("sizeof(test) = %d bits\n", sizeof(test) * 8); } Additional reference words: 8.00 1.00 fixlist8.00c fixlist1.50 buglist8.00 buglist1.00 KBCategory: kbprg kbfixlist kbbuglist KBSubcategory: CPPIss

Keywords : kb16bitonly kbCompiler kbCPPonly kbVC

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Technology : kbVCsearch kbAudDeveloper kbCVCComp