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In computer programming, several language mechanisms exist for exception handling. The term exception is typically used to denote a data structure storing information about an exceptional condition. One mechanism to transfer control, or raise an exception, is known as a throw; the exception is said to be thrown. Execution is transferred to a catch.
Exceptions are defined by different layers of a computer system, and the typical layers are CPU-defined interrupts, operating system (OS)-defined signals, programming language-defined exceptions. Each layer requires different ways of exception handling although they may be interrelated, e.g. a CPU interrupt could be turned into an OS signal.
The exception object is stored in "ex". Catch ex As ExceptionType ' Handle Exception of a specified type (i.e. DivideByZeroException, OverflowException, etc.) Catch ex As Exception ' Handle Exception (catch all exceptions of a type not previously specified) Catch ' Handles anything that might be thrown, including non-CLR exceptions.
The exception is propagated upwards through the call stack until a matching catch block is found within one of the currently active methods. If the exception propagates all the way up to the top-most main method without a matching catch block being found, a textual description of the exception is written to the standard output stream.
In this C# example, all exceptions are caught regardless of type, and a new generic exception is thrown, keeping only the message of the original exception. The original stacktrace is lost, along with the type of the original exception, any exception for which the original exception was a wrapper, and any other information captured in the ...
SEH on 64-bit Windows does not involve a runtime exception handler list; instead, it uses a stack unwinding table (UNWIND_INFO) interpreted by the system when an exception occurs. [4] [5] This means that the compiler does not have to generate extra code to manually perform stack unwinding and to call exception handlers appropriately. It merely ...
An enabled interrupt, a debug exception, the BINIT signal, the INIT signal, or the RESET signal resumes execution, which means the processor can always be restarted. [15] Some of the early Intel DX4 chips have a problem with the HLT instruction and cannot be restarted after this instruction is used, which disables the computer and turns HLT ...
Exception safety is the state of code working correctly when exceptions are thrown. [1] To aid in ensuring exception safety, C++ standard library developers have devised a set of exception safety levels , contractual guarantees of the behavior of a data structure's operations with regards to exceptions.