How to do it...

We are going to create a sample application that throws and catches a custom exception and analyze how the data type choice affects efficiency. Follow these steps:

1. In your working directory, that is, ~/test, create a subdirectory called catch.
2. Use your favorite text editor to create a file called catch.cpp in the catch subdirectory.
3. Put the definition of the Error class in the catch.cpp file:

#include <iostream>

class Error {
  int code;

  public:
    Error(int code): code(code) {
      std::cout << " Error instance " << code << " was created"
                << std::endl;
    }
    Error(const Error& other): code(other.code) {
      std::cout << " Error instance " << code << " was cloned"
                << std::endl;
    }
    ~Error() {
      std::cout << " Error instance " << code << " was destroyed"
                << std::endl;
    }
};

4. Next, we add helper functions to test three different ways of throwing and handling errors. We start with the function that catches exceptions by value:

void CatchByValue() {
  std::cout << "Catch by value" << std::endl;
  try {
    throw Error(1);
  }
  catch (Error e) {
    std::cout << " Error caught" << std::endl;
  }
}

5. Then, we add a function that throws a pointer and catches the exception by pointer, as follows:

void CatchByPointer() {
  std::cout << "Catch by pointer" << std::endl;
  try {
    throw new Error(2);
  }
  catch (Error* e) {
    std::cout << " Error caught" << std::endl;
  }
}

6. Next, we add a function that uses a const reference to catch exceptions:

void CatchByReference() {
  std::cout << "Catch by reference" << std::endl;
  try {
    throw Error(3);
  }
  catch (const Error& e) {
    std::cout << " Error caught" << std::endl;
  }
}

7. After all the helper functions have been defined, we add the main function to tie everything together:

int main() {
  CatchByValue();
  CatchByPointer();
  CatchByReference();
  return 0;
}

8. We put the build rules for our application into a CMakeLists.txt file:

cmake_minimum_required(VERSION 3.5.1)
project(catch)
add_executable(catch catch.cpp)
set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR arm)

SET(CMAKE_CXX_FLAGS "--std=c++11")

set(CMAKE_CXX_COMPILER /usr/bin/arm-linux-gnueabi-g++)

9. We can now build and run the application.