Main function as entry point in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the main function in a Kotlin program?

The main function is the starting point of a Kotlin program. When you run the program, the code inside main is executed first.

beginner

How do you declare the main function in Kotlin that takes no arguments?

You declare it like this:

fun main() {
    // code here
}

This function runs when the program starts.

intermediate

Can the main function in Kotlin accept command-line arguments? If yes, how?

Yes, it can accept arguments as an array of strings:

fun main(args: Array<String>) {
    // use args here
}

This lets you use inputs from the command line.

beginner

What happens if you write a Kotlin program without a main function?

The program will not run because Kotlin needs a main function as the entry point to start executing code.

intermediate

Is it possible to have multiple main functions in a Kotlin project?

Yes, but only one main function is used when you run the program. You can have multiple in different files for testing or different programs, but you must specify which one to run.

What is the correct way to declare a main function in Kotlin that accepts command-line arguments?

A main() fun {}

B fun main(args: Array<String>) {}

C void main() {}

D fun main() args: String[] {}

The correct syntax is fun main(args: Array) {} to accept command-line arguments.

What role does the main function play in a Kotlin program?

A It compiles the program.

B It stores variables.

C It is used only for testing.

D It is the entry point where the program starts running.

The main function is the entry point where the program begins execution.

Which of these is NOT a valid main function declaration in Kotlin?

A fun main() {}

B fun main(args: Array<String>) {}

C fun main(args: List<String>) {}

D fun main(vararg args: String) {}

The main function must accept Array<String>, not List<String>.

What happens if you run a Kotlin program without a main function?

A The program will not run and shows an error.

B The program runs normally.

C The program runs but skips the <code>main</code> function.

D The program runs but prints nothing.

Kotlin requires a main function as the entry point; without it, the program cannot run.

Can you have multiple main functions in a Kotlin project?

A Yes, but only one is used when running the program.

B No, only one <code>main</code> function is allowed in the whole project.

C Yes, and all run simultaneously.

D No, <code>main</code> functions are not allowed.

You can have multiple main functions in different files, but only one is used when you run the program.

Explain the role of the main function in Kotlin and how to declare it.

Think about where the program begins and how you write the function.

Describe what happens if a Kotlin program does not have a main function.

Consider what Kotlin needs to start running code.