When to use Exception handling

Exception handling in C++ is used for dealing with unexpected situations, or "exceptions", that can occur during the execution of your program. An exception is an event that arises during the execution of a program and disrupts the normal flow of the program's instructions.

You should use exception handling in the following cases:

When the error can't be handled where it occurs: Sometimes the function that detects the error isn't equipped to handle the error. An exception allows the error to be thrown up to a higher level where there might be sufficient information or functionality to handle the error.
When you're building a library or API: When you're building libraries to be used by others, you don't know how they'll want to handle errors. By throwing exceptions, you give them the ability to catch and handle errors in a way that makes sense for their application.
When you want to separate error handling code from regular code: Mixing error handling code with regular code can make your program harder to read and maintain. By using exceptions, you can keep them separate.
When you want to propagate errors up the call stack: This is particularly useful when an error needs to be handled at a higher level than where it occurred.
When dealing with runtime errors: Compile-time errors are often syntax errors, which are typically caught before the code is run. Runtime errors, however, can happen during program execution, and these are the kinds of errors you'd use exception handling for. Examples include division by zero, file not found, memory allocation failed, etc.

Remember that exception handling introduces an overhead and can impact performance, especially if exceptions are thrown frequently. Therefore, it is not recommended to use exceptions for controlling normal program flow. They should only be used for handling error or exceptional situations.

Examples:

File Operations: If your program needs to open a file and perform operations on it, many things can go wrong. The file might not exist at the specified path, or the program might not have permissions to read from or write to the file. In these cases, it's good practice to use exception handling to catch these errors and provide meaningful feedback to the user, or handle it appropriately.

Memory Allocation: If your program dynamically allocates memory, and there's not enough memory available, a std::bad_alloc exception is thrown. This is a critical issue and the program should handle this situation.

Division by Zero: If your program includes a division operation, there's a possibility of a divide by zero error. This can be checked and handled using exception handling.

Database Operations: If your program is trying to connect to a database, you might face issues such as the database not being available, invalid credentials being provided, or network issues. Exception handling can help you manage these potential problems gracefully.

Web API Connections: When making requests to a web API, there are numerous potential points of failure, including network errors, invalid responses, or issues with the API itself. Exception handling can provide a way to catch these issues and handle them appropriately.