Errors typically occur when something goes wrong in your program, and could range from syntax errors, logical errors or runtime errors. A syntax error occurs when the compiler does not understand your code because you violated the grammar rules of the programming language. Logical errors occur when your program does not do what you intended because of a mistake in the program's logic. Runtime errors are those that occur during runtime, caused by doing something like dividing by zero, or dealing with null data.

Exceptions on the other hand, are types of runtime errors. The difference is that exceptions can be caught and handled within the code, giving the programmer the opportunity to control the system's reaction to the error. This makes the system robust and resilient. The above code demonstrates an example of an exception. Here, we are trying to divide a number by zero, which is not permitted, and the program will throw an exception. This exception is caught and handled by providing an error message to the end user. The 'throw' statement allows you to create your own exceptions. We 'throw' an exception when a problem is detected which we cannot handle.

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#include <iostream>

using namespace std;

int main() {

  int num1 = 5;

  int num2 = 0;

  int result;

  try {

    if (num2 == 0)

      throw 0;

    result = num1 / num2;

    cout << result;

  }

  catch (int e) {

    cout << "Error: Division by zero is not allowed.";

  }

  return 0;

}

The try block includes the code that might throw an exception, which means lead to some error. The catch block then handles that exception, prevents the program from crashing, and allows it to continue running. In our example, the try-catch block is being used to handle the divide by zero error in our code.

If we didn't use the try-catch block, our program would terminate immediately when it encounters the division by zero error. But with the try-catch block, we're able to catch the exception and handle it gracefully by providing a meaningful error message to the user.

The throw statement is used to throw an exception when you encounter an issue. The exception is thrown up to the nearest catch block. However, we will detail its usage later on.

Using try, throw, and catch is critical for building resilient software that handles different types of errors and exceptions, such as unexpected system failures, network errors, or invalid user input. For example, if you're working on a financial software that makes real-time trades, you wouldn't want your program to crash in the middle of a trade. With try, throw, and catch, you can handle such exceptions and prevent your system from crashing.

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#include <iostream>

using namespace std;

int main() {

  try {

    // Trying to divide by zero

    int divisor = 0;

    int result = 10 / divisor;

    cout << "The division was successful.";

  } catch (const exception& e) {

    // Catch exception and print error message

    cout << "An error occurred: " << e.what();

  }

  return 0;

}

Here we have a practical example that uses try, throw, and catch in an age verification system, essential for many web applications dealing with age-restricted content. We can imagine a scenario where a user must be at least 18 years old to access a certain feature or product.

We place the code that might throw an exception (in this case the user being underage) inside a try block, and we handle the exception in the catch block. If an exception is thrown (i.e., the user's age is less than 18), the catch block catches the exception and executes the code inside it.

Our code throws an exception if the age is less than 18. We then catch the exception and print a custom error message, notifying the user that they must be at least 18 to access the desired feature. We also print out the user's actual age by catching the thrown variable age as myNum.

This is a simplified example. In a real-world application, you would likely be working with more complex data and have more sophisticated error handling mechanisms. But it shows how try, throw, catch can be used as part of the error handling strategy in a web development context.

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#include <iostream>

using namespace std;

​

int main() {

  try {

    int age = 15;

    if (age >= 18) {

      cout << "Access granted - you are old enough.";

    } else {

      throw (age);

    }

  }

  catch (int myNum) {

    cout << "Access denied - You must be at least 18 years old." << '\n';

    cout << "You are " << myNum << " years old.";

  }

​

  return 0;

}

So far we've used the predefined exceptions provided by C++, but what if none of these standard exceptions meet your needs? In such a case, you can create your own custom exceptions. Our senior engineer who has an interest in AI and finance might want to create a custom exception if an AI model's performance drops below an acceptable threshold for a financial algorithm.

To create a custom exception in C++, you can define a new class derived from the base class std::exception. You can override the what method with your own error message. Here, we've created a custom exception class MyException.

In the main function, we use throw MyException() to throw our custom exception. Our catch block catches MyException and displays your custom error message.

Custom exceptions give you much more flexibility over standard exceptions and can respond better to the unique needs of your applications, especially when different actions need to be taken for different types of exception events.

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```cpp

#include <iostream>

#include <exception>

using namespace std;

​

// Define a custom exception

class MyException : public exception {

public:

  const char * what () const throw () {

    return "MyException: AI model performance below acceptable threshold.";

  }

};

int main() {

  try {

    throw MyException();

  }

  catch(MyException& e) {

    std::cout << e.what() << std::endl;

  }

  catch(std::exception& e) {

    // Other errors...

  }

}

Let's go through a practical coding example using custom exceptions related to our reader's interest in AI finance. Imagine we have an AI strategy in place for predicting market patterns, and we have an acceptable performance threshold of 80%. If the performance of the current AI model falls below this threshold, we want to throw a Strategy (Strat) Error.

Here's how we'd set that up in C++:

First, we create a StratError class, derived from std::exception and override the what method to print out a helpful error message.

In the main function, we simulate the performance of our current AI model with a variable modelPerformance. We set a try block that checks if the performance is below the threshold, in which case it throws a StratError. The catch block catches this and uses cerr to output our custom error message. This example showcases how you can create specific exceptions for certain use-cases and handle them accordingly.

Please note that std::cerr is used instead of the usual std::cout for error messages. Like cout, cerr also writes to the standard output. However, cerr is unbuffered, and is typically used for error output. You will thus immediately see error messages, which is beneficial and often essential for debugging.

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#include <iostream>

#include <exception>

class StratError : public std::exception {

public:

    virtual const char* what() const throw() {

        return 

        "Strategy performance fell below acceptable threshold";

    }

};

​

int main() {

    try {

        int modelPerformance = 70;

        if (modelPerformance < 80) {

            throw StratError();

        }

    } catch (StratError& e) {

        std::cerr << e.what() << std::endl;

    }

return 0;

}

Exception handling is an important aspect of any C++ programming, especially in domains such as AI and finance where error tolerance is incredibly low. As a senior engineer, following certain best practices can reduce the risks and improve the efficiency of your code:

1. Do not ignore exceptions: Ignoring exceptions or leaving them unhandled can have drastic consequences. It's better to handle them appropriately according to the context.

2. Use meaningful exception messages: a good practice is to make custom exceptions convey meaningful messages which directly specify the type and cause of error.

3. Don't use exceptions for flow control: Exceptions should be used for exceptional situations and not as a way to control the standard flow of your program.

4. Do not throw exceptions in destructors: An exception that is thrown and not caught can result in a call to std::terminate. If a destructor throws an exception while processing another exception, the program can terminate.

5. Clean up resources after exceptions: In C++, exceptions often bypass the usual flow of control, so cleanup code must be carefully structured to prevent leaks (especially important if your code is related to predictive financial models). In the AI/finance field, a memory leak, even a minor one, could bring down the entire system.

The concept of RAII (Resource Allocation Is Initialization) is often used in C++ to ensure that resources are correctly cleaned up, using the scope of variables to control their lifetimes. This can help avoid memory or resource leaks and makes your code safer and more robust, especially when dealing with exceptions.

Reviewing these best practices on a regular basis is a great way to avoid common pitfalls in C++ exception handling. By incorporating these practices into your work, you can ensure the robustness and reliability of your code, contributing to reliable AI models and optimized financial strategies.

Exception handling in C++ is crucial to building robust and efficient AI models and financial systems. As we have seen, unhandled exceptions can disrupt program flow and cause unexpected behavior. This could have dire consequences in critical systems, such as those used in AI and finance.

Throughout this course, we have encountered both system-defined and custom exceptions. We have learned to use try, throw, and catch blocks in handling exceptions in our C++ code. The try block encloses the code which might throw an exception whereas the catch block catches and handles any exceptions thrown within the preceding try block.

Using meaningful exception messages is recommended for easily identifying the origin and cause of an error. However, exceptions should not be used as a method of flow control in your programs. Always remember to clean up resources after exceptions to avoid memory leaks.

The concept of RAII (Resource Allocation Is Initialization) further helps in managing resources neatly and avoiding potential memory leaks especially when dealing with exceptions.

In conclusion, adopting the best practices in exception handling, like not ignoring any exceptions, not using exceptions for flow control, and not throwing exceptions in destructors can immensely contribute to building reliable systems in the domains of AI and finance.

Mastering exception handling in C++ goes a long way in enhancing your coding skills, particularly in developing efficient AI models and financial systems.