C Academy · Lesson

Exception Handling in C

Implement robust error-handling strategies without built-in exception handling.

Lesson 3 of 310 steps

Exception Handling in C is a free C Academy lesson on CoddyKit. This is lesson 3 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the C Academy learning path, and your progress syncs across the web and the CoddyKit app. The C Academy course includes 3 lessons in total.

Introduction to Exception Handling

Exception Handling in C

Unlike languages like C++ and Java, C does not have built-in exception handling.

In this lesson, you will learn:

How to handle errors using return values.
How to use setjmp and longjmp for exception handling.
How to use errno for system error handling.

Exception Handling in C — illustration 1

Handling Errors with Return Values

The simplest way to handle errors in C is to use return values.

Example:

int divide(int a, int b) {
    if (b == 0) return -1; // Error code
    return a / b;
}

The caller checks the return value for errors.

Example: Error Handling with Return Values

This program checks for division by zero using return values.

#include <stdio.h>

int divide(int a, int b) {
    if (b == 0) {
        printf("Error: Division by zero!\n");
        return -1;
    }
    return a / b;
}

int main() {
    int result = divide(10, 0);
    if (result != -1) {
        printf("Result: %d\n", result);
    }
    return 0;
}

Using setjmp and longjmp for Error Handling

The setjmp and longjmp functions allow non-local jumps, simulating exception handling.

Steps:

Use setjmp() to mark a recovery point.
Use longjmp() to jump back when an error occurs.

Example: Using setjmp and longjmp

This program uses setjmp and longjmp for error handling.

#include <stdio.h>
#include <setjmp.h>

jmp_buf buffer;

void errorHandler() {
    printf("Error occurred! Jumping back to safe state.\n");
    longjmp(buffer, 1);
}

int main() {
    if (setjmp(buffer) == 0) {
        printf("Executing main program...\n");
        errorHandler();
    } else {
        printf("Recovered from error.\n");
    }
    return 0;
}

Using errno for System Errors

The errno variable stores error codes from system calls.

Example:

#include

Functions like fopen() set errno when errors occur.

Example: Using errno for File Handling

This program checks errno when opening a non-existent file.

#include <stdio.h>
#include <errno.h>

int main() {
    FILE *file = fopen("nonexistent.txt", "r");
    if (!file) {
        perror("Error opening file");
    }
    return 0;
}

Best Practices for Error Handling

To manage errors effectively:

Check return values of functions.
Use errno for system errors.
Use setjmp and longjmp only when necessary.

Summary

In this lesson, you learned:

How to handle errors using return values.
How setjmp and longjmp simulate exception handling.
How to use errno for system error detection.

This concludes the Debugging and Error Handling section in C!

Exception Handling in C — illustration 10

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Frequently Asked Questions

Is the “Exception Handling in C” lesson free?

Yes — the full text of “Exception Handling in C” is free to read here on the web. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the C Academy course, upgrade to CoddyKit PRO. The C Academy course includes 3 lessons in total.

What will I learn in “Exception Handling in C”?

Implement robust error-handling strategies without built-in exception handling. You practise C Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start C Academy?

No prior experience is required. C Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 3 of 3.

How long does the “Exception Handling in C” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this C Academy lesson?

Yes. Every C Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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