Building our app

We will be building a command-line based CSV reader that prints the unique entries of the columns and their counts, based on user input in Kotlin Native.

Writing the main function

Kotlin Native has the same language syntax and includes the standard library. Hence, the main function in Kotlin Native looks the same as the main function in JVM or JS. It is similar to the following syntax:

    // Starting point
    fun main(args: Array<String>) {
      // Rest of code over here..
    }

The main function takes args, which contains the arguments from the command line.

Reading command-line arguments

We will be taking two arguments from the command line:

• The name of the CSV file to read
• The column number to find unique entries from

The following code block shows how to read arguments passed from the command line:

    // Get command line input
    if (args.size != 2) {
      println("Usage: csv_filename column_number")
      return
    }
    val fileName = args[0]
    val columnNumber...