Working of finally Keyword in C#
- Any resources allocated in the try block can be cleaned up by using Finally block of code and the Finally block of code runs regardless of the exception raised in the try block.
- The statements in the Finally block of code are executed when the control leaves the try block of code. ...
What is the finally keyword?
Definition and Usage The finally keyword is used to execute code (used with exceptions - try..catch statements) no matter if there is an exception or not.
What does finally do in JavaScript?
The code inside a finally block will get executed regardless of whether or not there is an exception. This comes in very handy when it comes to certain housekeeping functions you need to always run like closing connections. try { doSomething (); } catch { catchSomething (); } finally { alwaysDoThis (); }
What is the purpose of the finally block?
It always executes whether the try block terminates normally or terminates due to an exception. The main purpose of finally block is to release the system resources. The finally block follows try/catch block.
When do we need a finally clause in a C program?
There are many cases where such need for finally clause arises, mostly as I can see it, it always happen when a programmer uses a third party or legacy "C oriented" library that deals with resources in a procedural way like open/close file or connect/disconnect a service.
What is the primary use of finally block of code?
The primary use of finally block of code is to release all the allocated expensive resources in the try block.
Why won't the control leave the finally block?
The control will not leave the finally block because there is no goto statement, break statement, continue statement or return statement in finally block.
What happens to code inside a finally block?
The code inside a finally block will get executed regardless of whether or not there is an exception. This comes in very handy when it comes to certain housekeeping functions you need to always run like closing connections.
Why is the finally block important?
The finally blockis valuable for cleaning up any resources allocated in the try block as well as running any code that must execute even if there is an exception. Control is always passed to the finally block regardless of how the try block exits.
What happens if you pull the power cord out while a machine is executing a try clause?
If you pull the power cord out while a machine is executing a try clause the finally clause will not be called.
What happens when a catch clause is found?
Once a matching catch clause is found, the system prepares to transfer control to the first statement of the catch clause. Before execution of the catch clause begins, the system first executes, in order, any finally clauses that were associated with try statements more nested that than the one that caught the exception.
Can Finally statements execute after return?
Finally statements can execute even after return.
Does always dothis() always execute?
With the latter code, the "alwaysDoThis();" call won't execute if the code inside the catch statement issues a return or throws a new exception.
What is the purpose of final keyword?
One purpose of the final keyword is to prevent accidental overriding of a method. In my example, DoStuff () may have been a helper function that the derived class simply needs to rename to get correct behavior. Without final, the error would not be discovered until testing.
What does final add do?
final adds an explicit intent to not have your function overridden, and will cause a compiler error should this be violated:
What does a->foo call?
a->foo () will always call A::foo.
What is the purpose of C++11?
It is to prevent a class from being inherited. From Wikipedia: C++11 also adds the ability to prevent inheriting from classes or simply preventing overriding methods in derived classes. This is done with the special identifier final.
Is override a language keyword?
Note that neither override nor final are language keywords. They are technically identifiers; they only gain special meaning when used in those specific contexts. In any other location, they can be valid identifiers.
Can a class extend C?
Other classes can extend A and B and override their foo, but it a class extends C then it is not allowed .
Can B::foo be declared again?
there's no way to make B::foo a new, unrelated function that can be independently at the head of a new virtual hierarchy. Once a function is final, it can never be declared again in any derived class.
Why use "finally" like construct?
Another reason to use this " finally " like construct is for external resources that should be reclaimed no matter what happened after they were successfully claimed. For example, deterministic log-out of a remote service no matter what happens after a successful log-in to that service. That way prevents the remote dangling service from waiting for a log-out until some time-out routine will close the remote socket...
What does the finally class do?
The finally class provides a means of running commands upon leaving the block by using the destructor of the class.
What are the functions in C++?
For beginners, I strongly suggest to read briefly the following items in the C++ reference: 1 Lambda Functions in C++11 - the Definitive Guide 2 Function objects 3 std::function 4 std::bind
Is Straustrup's technique better than finally clause?
Maybe people who come to C from the world of Java or C# feel "finally starvation" - but it`s just a matter of habbit, and if you start using Straustrup`s technique, you might feel it even better than finally clause.
Does C++ imitate other languages?
It imitate the behavior of other languages finally. That is, it guaranties to run set of instruction in case of getting out of scope. it saves the need to write the code twice, once in catch clause and once after catch clause. There is no way for me to change the C++ language to have the look and feel of other languages.
Why do we use final in C++?
In Java, we can use final for a function to make sure that it cannot be overridden. We can also use final in Java to make sure that a class cannot be inherited. Similarly, the latest C++ standard C++ 11 added final. Sometimes you don’t want to allow derived class to override the base class’ virtual function.
Why is CPP not a keyword?
final has meaning only when used in above contexts, otherwise it’s just an identifier. One possible reason to not make final a keyword is to ensure backward compatibility. There may exist production codes which use final for other purposes.
What is the second use of final specifier?
2nd use of final specifier:#N#final specifier in C++ 11 can also be used to prevent inheritance of class / struct. If a class or struct is marked as final then it becomes non inheritable and it cannot be used as base class/struct.