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Chapter 1

LabWindows/CVI Compiler

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 National Instruments Corporation

1-5

LabWindows/CVI Programmer Reference Manual

You can set the maximum alignment as follows:

#pragma pack(4) /* sets maximum alignment to 4 bytes */

#pragma pack(8) /* sets maximum alignment to 8 bytes */

#pragma pack()  /* resets to the default*/

The maximum alignment the compiler applies to a structure is based on the last 

pack 

pragma

 statement it sees before the definition of the structure.

Under Windows 95/NT, you can use 

WinMain

 instead of 

main

 as the entry-point function to 

your program. You might want to do this if you plan to link your executable using an external 
compiler. You must include 

windows.h

 for the data types that normally appear in the 

WinMain

 parameter list. The following is the prototype for 

WinMain

 with the Windows data 

types reduced to intrinsic C types.

int __stdcall

WinMain(void *

hInstance, void *

hPrevInstance, 

char *

lpszCmdLine int nCmdShow)

This section discusses special considerations in LabWindows/CVI in the areas of low-level 
I/O functions and the UNIX C library.

Many functions in the UNIX libraries and the C compiler libraries for the PC are not ANSI C 
Standard Library functions. In general, LabWindows/CVI implements the ANSI C Standard 
Library. Under UNIX, you can call UNIX libraries for the non-ANSI C functions in 
conjunction with LabWindows/CVI.

The low-level I/O functions 

open

, 

close

, 

read

, 

write

, 

lseek

, and 

eof

 are not in the 

ANSI C Standard Library. Under UNIX, these functions are available in the UNIX C library. 
Refer to Chapter 5, 

, for more information.

Under Windows, you can use these functions along with 

sopen

 and 

fdopen

 if you include 

lowlvlio.h

. 

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