Constructors and Destructors in Exception Handling

When an exception is thrown and control passes to a catch block following a try block, destructors are called for all automatic objects constructed since the beginning of the try block directly associated with that catch block. If an exception is thrown during construction of an object consisting of subobjects or array elements, destructors are only called for those subobjects or array elements successfully constructed before the exception was thrown. A destructor for a local static object will only be called if the object was successfully constructed.

If a destructor detects an exception and issues a throw , the exception can be caught if the caller of the destructor was contained within a try block and an appropriate catch is coded.

If an exception is thrown by a function called from an inner try block, but caught by an outer try block (because the inner try block did not have an appropriate handler), all objects constructed within both the outer and all inner try blocks are destroyed. If the thrown object has a destructor , the destructor is not called until the exception is caught and handled.

Because a throw expression throws an object and a catch statement can catch an object, the object thrown enables error-related information to be transferred from the point at which an exception is detected to the exception's handler. If you throw an object with a constructor, you can construct an object that contains information relevant to the catch expression. The catch block can then access information provided by the thrown object.

Exception handling can be used in conjunction with constructors and destructors to provide resource management that ensures that all locked resources are unlocked when an exception is thrown.

C++ Exception Handling Overview
Constructors and Destructors Overview

Example of Using Constructors in Exception Handling
Example of Managing Resources with Constructors and Destructors

Using Exception Handling
Transferring Control
Exception Specifications