C Error Handling
⚠️ C Error Handling
Unlike some modern languages, C does not have built-in exception handling (like try-catch).
Instead, C uses several alternative mechanisms for detecting and managing errors manually.
🔹 Methods of Error Handling in C
| Method | Used For |
|---|---|
| Return values | Function failure signals |
errno | Global error reporting |
perror() / strerror() | Human-readable error messages |
Assertions (assert) | Debugging and sanity checks |
setjmp() / longjmp() | Manual exception-like behavior |
1. Error Handling using Return Values
Functions often return special values like -1, NULL, or 0 to indicate failure.
Example:
2. Error Handling Using errno
errno is a global variable set by some library functions when an error occurs.
Include:
Example:
3. perror() and strerror()
| Function | Purpose |
|---|---|
perror("message") | Prints a system error message with context |
strerror(errno) | Returns error message as a string |
Example:
Output example:
4. Using assert() (Debugging Only)
Stops the program if a condition is false.
⚠️ Assertions are removed in production builds using:
5. setjmp() and longjmp() (Manual Exception Handling)
Used to jump to a saved execution point — similar to exceptions.
🧪 Real Example: Safe File Opening
🧠 Best Practices
✔ Always check return values (especially for I/O and pointer operations)
✔ Use errno, perror(), and strerror() for readable errors
✔ Use assert() in debugging, not production
✔ Use setjmp() and longjmp() only for advanced cases
🏁 Summary Table
| Technique | Best For |
|---|---|
| Return codes | Simple functions |
errno | System/library errors |
perror() / strerror() | User-friendly error messages |
assert() | Debug/testing |
setjmp() / longjmp() | Advanced error control |
