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In this Guide we will discuss about basic syntax of Kotlin.

Kotlin Program Entry Point

An entry point of a Kotlin application is the main() function. A function can be defined as a block of code designed to perform a particular task.

Let’s start with a basic Kotlin program to print “Hello adglob!” on the standard output:

fun main() {
     var string: string = "Hello adglob!"
println("$string")
}

When you run the above Kotlin program, it will generate the following output:

Hello adglob!

Entry Point with Parameters

Another form of main() function accepts a variable number of String arguments as follows:

fun main(args: Array<String>){
    println("Hello, adglob!")
}

When you run the above Kotlin program, it will generate the following output:

Hello, adglob!

If you have observed, its clear that both the programs generate same output, so it is very much optional to pass a parameter in main() function starting from Kotlin version 1.3.

print() vs println()

The print() is a function in Kotlin which prints its argument to the standard output, similar way the println() is another function which prints its argument on the standard output but it also adds a line break in the output.

Let’s try the following program to understand the difference between these two important functions:

fun main(args: Array<String>){
    println("Hello,")
    println(" adglob!")

    print("Hello,")
    print(" adglob!")
}

When you run the above Kotlin program, it will generate the following output:

Hello, 
 adglob!
Hello, adglob!

Both the functions (print() and println()) can be used to print numbers as well as strings and at the same time to perform any mathematical calculations as below:

fun main(args: Array<String>){
    println( 200 )
    println( "200" )
    println( 2 + 2 )

    print(4*3)
}

When you run the above Kotlin program, it will generate the following output:

200
200
4
12

Semicolon (;) in Kotlin

Kotlin code statements do not require a semicolon (;) to end the statement like many other programming languages, such as Java, C++, C#, etc. do need it.

Though you can compile and run a Kotlin program with and without semicolon successfully as follows:

fun main() {
    println("I'm without semi-colon")
    
    println("I'm with semi-colon");
}

I'm without semi-colon
I'm with semi-colon

package org.adglob.in

fun main() {
    println("Hello, World!")
}

When you run the above Kotlin program, it will generate the following output:

Hello, World!

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