Handling Runtime Errors and Exceptions

When writing programs, it is essential to anticipate and handle errors that may occur during the execution of the code. Runtime errors and exceptions are examples of such errors that need to be managed carefully to ensure the program's stability. In this article, we will explore the significance of handling runtime errors and exceptions in the C programming language, along with some effective techniques to deal with them.

Understanding Runtime Errors

Runtime errors, also known as exceptions, are unforeseen issues that occur during the execution of a program. These errors stop the normal execution flow and require specific error-handling techniques to prevent program crashes or erroneous outputs. Common causes of runtime errors include:

  • Division by zero
  • Invalid input or arguments
  • Out of memory
  • Accessing invalid memory addresses
  • Improper file operations

To handle these runtime errors, C provides two primary mechanisms: return codes and exceptions.

Using Return Codes

One way to handle runtime errors is by using return codes. Functions in C typically return a value to indicate the success or failure of the operation. By defining a set of meaningful return codes, you can notify the calling code about the execution status and any encountered errors.

For example, if a function accepts an input and performs some calculations, it can return a specific value (e.g., 0 for success and non-zero for an error). The calling code can then check this return value and take appropriate actions accordingly, such as displaying an error message or attempting to recover from the error condition.

Using return codes for error handling requires explicit checking at every call site and can become cumbersome in larger codebases. To overcome this, C also allows the usage of exception handling.

Exception Handling in C

Although C does not have built-in exception handling constructs like other high-level languages, you can implement your own exception handling mechanism using a combination of setjmp and longjmp functions. These functions allow you to establish a "checkpoint" in the code and jump back to that point upon encountering an error or exception.

The setjmp function is used to set the checkpoint, while longjmp performs the actual jump back to that point. By wrapping potentially error-prone code sections with setjmp and longjmp, you can effectively handle exceptions and execute error-specific cleanup operations.

However, it is important to note that exception handling using setjmp and longjmp should be used sparingly and only for exceptional cases. Overusing this mechanism can lead to convoluted code and hinder program readability.

Best Practices for Error Handling

To effectively handle runtime errors and exceptions in your C programs, consider following these best practices:

  1. Identify potential error scenarios: Analyze your code to identify all possible runtime errors that may occur during execution, such as division by zero or invalid file operations.

  2. Use return codes judiciously: For simple error cases, utilize return codes to indicate failures. Make sure to document the specific error codes and their meanings.

  3. Implement exception handling selectively: Reserve exception handling mechanisms like setjmp and longjmp for critical error scenarios where recovery or proper cleanup is required. Avoid excessive use of these techniques.

  4. Log and report errors: Whenever an error occurs, log relevant information about the error, including the error code and a descriptive message. This information can greatly assist in debugging and troubleshooting.

  5. Gracefully exit on fatal errors: If a runtime error or exception is non-recoverable, it is preferable to gracefully exit the program instead of letting it crash. This ensures that resources are properly released and prevents unexpected behavior.

  6. Test error scenarios: Thoroughly test your code by deliberately triggering error conditions and verifying that the error handling mechanisms behave as expected.

By adhering to these practices, you can significantly enhance the reliability and stability of your C programs, making them more robust and less prone to crashes or erroneous behavior.


Handling runtime errors and exceptions is a critical aspect of writing reliable code. By correctly identifying potential errors, using appropriate error-handling techniques, and following best practices, you can effectively manage runtime errors and ensure the smooth execution of your C programs. Remember, proactive error handling significantly contributes to the overall quality and user experience of your software.

noob to master © copyleft