RpcExcept macro (rpc.h)

Article
04/02/2021

The RpcExcept statement provides structured exception handling for RPC applications.

Windows Vista and later versions of Windows: RpcExceptionFilter is recommended for structured exception handling for the most common exceptions as an alternative to custom filters with RpcExcept. Custom exception filters must still use RpcExcept, however.

Syntax

void RpcExcept(
   expr
);

Parameters

expr

Expression that is evaluated when an exception occurs. If expression evaluates to a nonzero value, the exception statements are executed. If expression evaluates to a zero value, unwinding continues to the next RpcTryExcept or RpcTryFinally function.

Return value

None

Remarks

If an exception does not occur, the expression and exception statements are skipped and execution continues at the statement following the RpcEndExcept statement.

The compound statement after the RpcTryExcept clause is the body or guarded section. The compound statement after the RpcExcept clause is the exception handler. The handler specifies a set of actions to be taken if an exception is raised during execution of the body of the guarded section. Execution proceeds as follows:

The guarded section is executed.
If no exception occurs during execution of the guarded section, execution continues at the statement after RpcEndExcept clause.
If an exception occurs during execution of the guarded section or in any routine the guarded section calls, the __except expression is evaluated and the value determines how the exception is handled. There are three values:
- EXCEPTION_CONTINUE_EXECUTION (–1) Exception is dismissed. Continue execution at the point where the exception occurred.
- EXCEPTION_CONTINUE_SEARCH (0) Exception is not recognized. Continue to search up the stack for a handler, first for containing try-except statements, then for handlers with the next highest precedence.
- Exception is recognized. Transfer control to the exception handler by executing the __except compound statement, then continue execution after the __except block.

Because the RpcExcept expression is evaluated as a C expression, it is limited to a single value, the conditional-expression operator, or the comma operator. If more extensive processing is required, the expression can call a routine that returns one of the three values listed above.

RpcExceptionCode can be used in both expression and exception statements to determine which exception occurred.

The following restrictions apply:

Jumping (through a goto) into guarded statements is not allowed.
Jumping (through a goto) into exception statements is not allowed.
Returning or jumping (through a goto) from guarded statements is not allowed.
Returning or jumping (through a goto) from exception statements is not allowed.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	rpc.h