c++ throw exception

Include the necessary header file: In C++, when we want to use exceptions, we need to include the <stdexcept> header file. This file contains the necessary classes and functions for handling exceptions.

Throw an exception: To throw an exception, we use the throw keyword followed by an expression or an object. This expression or object represents the exception that we want to throw. For example, we can throw a string object to indicate an error condition.

Catch the exception: To catch an exception, we use a try block followed by one or more catch blocks. Inside the try block, we write the code that might throw an exception. Inside the catch block, we handle the exception that was thrown. The catch block can have a parameter that represents the exception object.

Handle the exception: Inside the catch block, we can write code to handle the exception. This can involve displaying an error message, logging the error, or taking any other action to handle the exceptional condition. We can also re-throw the exception if we want to handle it at a higher level.

Multiple catch blocks: If we want to handle different types of exceptions differently, we can have multiple catch blocks. Each catch block can handle a specific type of exception. The catch blocks are checked in order, and the first one that matches the type of the thrown exception is executed.

Catch-all block: We can also have a catch-all catch block at the end to handle any exception that was not caught by the previous catch blocks. This catch-all block can be useful for logging or handling unexpected exceptions.

Rethrow exception: If we catch an exception but cannot handle it properly, we can rethrow the exception using the throw keyword without any expression. This allows the exception to be caught and handled at a higher level.

Exception hierarchy: In C++, exceptions are organized in a hierarchy. The base class for all exceptions is std::exception. This class provides a virtual function called what() that returns a string describing the exception. Derived classes can be created to represent specific types of exceptions.

Custom exceptions: We can also create our own custom exception classes by inheriting from std::exception or any other exception class. These custom exception classes can have additional member variables or functions to provide more information about the exception.

Exception safety: When writing code that can throw exceptions, it is important to ensure exception safety. This involves handling exceptions properly, making sure that resources are properly cleaned up, and ensuring that the program remains in a consistent state even if an exception is thrown.