How exceptions can be caught and re-thrown to be handled by higher-level functions?

Question

Aryan Kumar · Answer

Exceptions can be caught and re-thrown to be handled by higher level functions in C++ using the throw keyword. The throw keyword is used to throw an exception. The exception can be any object, but it is usually a std::exception object or a derived class of std::exception.

To catch and re-throw an exception, you can use the catch statement. The catch statement specifies the type of exception that you want to catch. If an exception of the specified type is thrown, the catch statement will be executed.

The following code shows how to catch and re-throw an exception:

C++

#include <iostream>
#include <exception>

using namespace std;

void foo() {
  throw std::runtime_error("An error occurred");
}

void bar() {
  try {
    foo();
  } catch (std::runtime_error e) {
    // Re-throw the exception
    throw e;
  }
}

int main() {
  try {
    bar();
  } catch (std::runtime_error e) {
    cout << "An error occurred: " << e.what() << endl;
  }

  return 0;
}

In this code, the foo() function throws a std::runtime_error exception. The bar() function catches this exception and then re-throws it. The main() function catches the exception and prints a message to the console.

It is important to note that the re-thrown exception will be caught by the first catch statement that matches its type. If there is no catch statement that matches the type of the exception, the program will terminate.

Here are some additional things to keep in mind when catching and re-throwing exceptions:

You can catch multiple exceptions in a single catch statement by using the | operator. For example, the following code catches both std::runtime_error and std::logic_error exceptions:

C++

catch (std::runtime_error | std::logic_error e) {

You can also catch a wildcard exception by using the catch (...) statement. The catch (...) statement will catch any exception, regardless of its type.

It is important to handle all exceptions that are thrown by your code. If an exception is not handled, the program will terminate.

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How exceptions can be caught and re-thrown to be handled by higher-level functions?

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