Question

What is the difference between exception handling using catch with and without an argument in C++?

Answer 1

In C++, there are two different ways to handle exceptions using catch: with an argument and without an argument. Let's explore the differences between these approaches:

1. Catch with an Argument: When using catch with an argument, you specify the type of exception that you want to catch. This allows you to catch exceptions of that specific type or any of its derived types. Here's an example:

   try {
       // Code that may throw exceptions
   }
   catch (ExceptionType& exception) {
       // Handle the exception
   }
    

   With this approach, the catch block will be executed only if an exception of type ExceptionType or its derived type is thrown. The exception object is caught by reference, allowing you to access and handle it within the catch block. This gives you the ability to perform specific handling based on the type of the exception.

2. Catch without an Argument: When using catch without an argument, you can catch any exception regardless of its type. Here's an example:

   try {
       // Code that may throw exceptions
   }
   catch (...) {
       // Handle the exception
   }
    

   The ellipsis (...) in the catch block serves as a catch-all for any type of exception. It allows you to catch and handle exceptions of any type. However, since the exception type is not specified, you won't have direct access to the exception object itself within the catch block. This makes it harder to perform specific handling based on the exception type.

It's important to note that when catching exceptions, it is generally recommended to catch specific exception types whenever possible. This allows for more targeted and meaningful exception handling. However, there may be situations where a catch-all approach is needed, such as logging or generic error handling.

Here's an example that demonstrates both approaches:

#include <iostream>
#include <stdexcept>

void throwException(bool isSpecific) {
    if (isSpecific) {
        throw std::runtime_error("Specific Exception");
    }
    else {
        throw "Generic Exception";
    }
}

int main() {
    try {
        throwException(true);  // Catch with an argument
    }
    catch (std::runtime_error& exception) {
        std::cout << "Caught specific exception: " << exception.what() << std::endl;
    }
    catch (...) {
        std::cout << "Caught generic exception" << std::endl;
    }

    try {
        throwException(false); // Catch without an argument
    }
    catch (std::runtime_error& exception) {
        std::cout << "Caught specific exception: " << exception.what() << std::endl;
    }
    catch (...) {
        std::cout << "Caught generic exception" << std::endl;
    }

    return 0;
}
 

In this example, the throwException function throws either a specific exception of type std::runtime_error or a generic exception of type const char*. The first try block catches the specific exception using catch(std::runtime_error& exception), and the second try block catches the generic exception using catch (...).