🔍 Why This Error Occurs

• Missing main() function in the source file
• Misspelled or incorrectly defined main()
• Compiling the wrong file or an empty file
• Using main inside a library file instead of a main application file

✅ How to Fix It

1. Make Sure You Have a Proper main() Function

int main() {
    return 0;
}

2. Don’t Misspell the Function

Wrong:

int Main() {
    return 0;
}

Right:

int main() {
    return 0;
}

3. Check File Selection in Online Compilers

If you're using an online compiler with multiple files, make sure the file that contains main() is selected as the main entry file.

4. Don't Use main() in a Header or Library File

Library files should not include main(). Reserve main() for the main source file only.

📌 Final Tip

The C compiler always looks for the main() function to start program execution. If it’s not defined or not spelled correctly, you'll get this error.

🧑‍💻 Bonus: Correct C Program Template

#include <stdio.h>

int main() {
    printf("Program compiled and ran successfully!\n");
    return 0;
}