Why can't VC++ accept (packed)?

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I have a code snippet:

C++

typedef struct tagBITMAPFILEHEADER {
  WORD    bfType; 
  DWORD   bfSize; 
  WORD    bfReserved1; 
  WORD    bfReserved2; 
  DWORD   bfOffBits; 
} __attribute__((packed)) BITMAPFILEHEADER;

I compiled it using VC++2012 and got error message:
1>D:\programs\ATP-3\ATP3MMI\MMI\include\sys-include\Windows32/Structures.h(210): error C2065: 'packed' : undeclared identifier

How come?

What I have tried:

I googled with keywords "packed", "compiler options", "VC++" and found all of them can't help me to figure it.

Posted 4-May-16 23:14pm

Stan Huang

Updated 4-May-16 23:29pm

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OriginalGriff · Accepted Answer · 2016-05-04T23:27:00

Solution 1

Because it's a nonstandard extension, used in GCC.
For VS, you want #pragma pack[^]

Posted 4-May-16 23:27pm

OriginalGriff

Comments

Stan Huang 5-May-16 6:27am

I added
#pragma pack( 1 )
in the beginning of the file, but I still got error message:
1>D:\programs\ATP-3\ATP3MMI\MMI\include\sys-include\Windows32/Structures.h(214): error C2065: 'packed' : undeclared identifier

OriginalGriff 5-May-16 7:31am

Yes, because you didn't remove the nonstandard extension...

CPallini · Accepted Answer · 2016-05-04T23:29:00

Solution 2

With the Microsoft C++ compiler, the way to go is the pragma pack[^].

Posted 4-May-16 23:29pm

CPallini

Comments

Stan Huang 5-May-16 6:35am

Do you mean
#pragma pack[^]
?
I got the following error, VC++ doesn't accept it.
1>D:\programs\ATP-3\ATP3MMI\MMI\include\sys-include\Windows32/Structures.h(33): warning C4081: expected '('; found '['

CPallini 5-May-16 7:27am

There is a code sample in the linked page.