National Instruments 320685D-01 ユーザーズマニュアル

Chapter 1

LabWindows/CVI Compiler

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 National Instruments Corporation

1-13

LabWindows/CVI Programmer Reference Manual

This macro could be useful in the following situation: LabWindows/CVI reports erroneous 
run-time errors because you set a pointer to dynamic memory in a source module and you then 
resize it in an object module. The following steps describe how this error occurs: 

1.

You declare a pointer in a source module you compile with debugging enabled. You then 
assign to the pointer an address that 

malloc

 or 

calloc

 returns: 

AnyType *ptr;

ptr = malloc(N);

2.

You reallocate the pointer in an object module so that it points to the same location in 
memory as before. This might occur if you call the 

realloc

 function or free the pointer 

and then reassign it to memory that you allocate with 

malloc

:

ptr = realloc(ptr, M); /* M > N */

or

free(ptr);

ptr = malloc(M);

3.

You use the same pointer in a source module you compile with debugging enabled. At 
this point, LabWindows/CVI still expects the pointer to point to a block of memory of 
the original size 

(N)

.

*(ptr+(M-1))

/* This generates a fatal run-time error, */

/* even though it is a legal expression.  */

To prevent this error, use the 

DISABLE_RUNTIME_CHECKING

 macro to disable checking for 

the pointer after you allocate memory for it in the source module:

ptr = malloc(N);

DISABLE_RUNTIME_CHECKING(ptr);

You can disable or enable library protection errors by placing pragmas in the source code. 
LabWindows/CVI ignores these pragmas when you compile without debugging information, 
that is, if the debugging level is None. For example, the following two pragmas enable and 
disable library checking for all the function declarations that occur after the pragma within a 
header or source file. The pragmas affect only the functions declared in the file in which the 
pragmas occur. These pragmas do not affect nested include files.

#pragma EnableLibraryRuntimeChecking 

#pragma DisableLibraryRuntimeChecking 

The following pragmas enable and disable library checking for a particular function. You 
must declare the function before the occurrence of the pragma.

#pragma EnableFunctionRuntimeChecking 

#pragma DisableFunctionRuntimeChecking 

 

00ProRef.book : 06chap01.fm  Page 13  Monday, March 9, 1998  3:23 PM