Article ID: 40027
Article Last Modified on 7/5/2005
APPLIES TO
- Microsoft C Professional Development System 6.0a
- 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++ 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
This article was previously published under Q40027
SUMMARY
The pack pragma affects declarations, not definitions. Place #pragma pack() prior to data declarations.
MORE INFORMATION
Sample Code
The following program demonstrates usage of #pragma pack():
/* compile options needed */
/* Elements of variables of type struct x will be byte-aligned. */
#pragma pack(1)
struct x { int a; char b; int c; };
/* Elements of variables of type struct y will be word-aligned. */
#pragma pack(2)
struct y { int a; char b; int d; };
/* The pragma below does NOT affect the definitions that follow. */
#pragma pack(4)
struct x X;
struct y Y;
void main (void)
{ /* dummy main */ }
NOTE: The default packing value for the 16-bit products mentioned above is 2 bytes. The default packing value for Visual C++ 32-bit, versions 1.0 and 2.xx, is 4 bytes. The default packing value for Visual C++ 32-bit, version 4.0, is 4 bytes for bit fields and 8 bytes otherwise.
Keywords: kbinfo kblangc KB40027
