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Chapter 1 LabWindows/CVI Compiler
LabWindows/CVI Programmer Reference Manual 1-14
©
National Instruments Corporation
These two pragmas enable and disable run-time checking for a particular library function
throughout the module in which they appear. You can use them to override the effects of the
EnableLibraryRuntimeChecking and DisableLibraryRuntimeChecking pragmas
for individual functions. If both of these pragmas occur in a module for the same function,
LabWindows/CVI uses only the last occurrence.
Note These pragmas affect all protection, including run-time checking of function
arguments, for all calls to a specific library function. To disable breaking on
errors for a particular call to a library function, use the Utility Library function
SetBreakOnLibraryErrors. To disable the run-time checking of argument
expressions for a particular call to a library function, use the Utility Library
function
SetBreakOnProtectionErrors.
Note You cannot use pragmas to disable protection for the functions in the
statically linked libraries including User Interface, RS-232, TCP, DDE,
Formatting and I/O, Utility, X Property, and ANSI C libraries unless you place the
DisableLibraryRuntimeChecking pragma at the top of the library header file.
Details of User Protection
Pointer Casting
A cast expression consists of a left parenthesis, a type name, a right parenthesis, and an
operand expression. The cast causes the compiler to convert the operand value to the type that
appears within the parenthesis.
C programmers occasionally have to cast a pointer to one data type to a pointer to another data
type. Because LabWindows/CVI does not restructure the user protection information for each
cast expression, certain types of cast expressions implicitly disable run-time checking for the
pointer value. In particular, casting a pointer expression to the following types disables
run-time checking on the resulting value:
• Pointer to a pointer:
(AnyType **) PointerExpression
• Pointer to a structure:(struct AnyStruct *) PointerExpression
• Pointer to an array:
(AnyType (*)[]) PointerExpression
• Any non-pointer type:(unsigned) PointerExpression,
(int) PointerExpression, and so on
Note An exception exists. Casts that you apply implicitly or explicitly to the void *
values you obtain from
malloc or calloc do not disable user protection.
Casting a pointer to one arithmetic type to a pointer to a different one, such as
(int *),
(unsigned *), (short *), and so on, does not affect run-time checking on the resulting
pointer, nor does casting a pointer to a void pointer
(void *).
00ProRef.book : 06chap01.fm Page 14 Monday, March 9, 1998 3:23 PM