//to int
val strNumber = "42"
//the first method
val number1 = strNumber.toInt()
//the second method
val number2 = strNumber.toIntOrNull()
if (number2 != null) {
    println("number2 is $number2")
}

//to Double and Float
//the first method
val strPi = "3.14"
val pi = strPi.toFloat()

//the second method
val strExp = "2.71828"
val exp = strExp.toFloatOrNull()

//the third method
val strHalf = "0,5"
val half = strHalf.replace(",", ".").toDouble()

println("number1 is $number1")
println("pi is $pi")
println("exp is $exp")
println("half is $half")