20190322 Iterating Arrays And Lists

Here I compare these aspects :

How are arrays and lists declared
Is it possible to add new elements to arrays
How do you iterate over complete lists and arrays

Groovy

Arrays and lists are the same in Groovy, they are declared with [], Groovy itself has no array datatype
Since there are only lists, you can add new elements to arrays

You can iterate over lists using the for-loop where you can break and the ‘each’ method, where you cannot break

def words = ["Hello", ",", " ", "World", "!"]
  
println ""
println "Sentence :"
for (String w : words) {
    print w
}
  
words.add(" ")
words.add("How")
words.add(" ")
words.add("are")
words.add(" ")
words.add("you")
words.add("?")
  
println ""
println "Sentence :"
words.each { w ->
    print w
}

Python

Arrays and lists are the same in Python, they are declared with [], Python itself has no array datatype
Python has an Array module for maths operations which can only work with numbers (not shown here)
Since there are only lists, you can append new elements to arrays

You can iterate over lists using the for-loop and you can implement your own foreach-function(shown later)

words = ["Hello", ",", " ", "World", "!"]
for w in words:
    print w

words.append("How")
words.append("are")
words.append("you")
words.append("?")

for w in words:
    print w

Kotlin

In Kotlin arrays can be created with arrayOf
Arrays in Kotlin have a fixed size, you cannot add elements to it
With listOf you can create immutable lists where you cannot add elements, too

You need to use a MutableList to add elements to it

var words1 = listOf("Hello", " ", "World", "!")
var words2 = arrayOf("Hello", " ", "World", "!")
   
val iterator = words2.iterator()
  
for (w in words1) {
    print(w)
}
  
iterator.forEach {w ->
    print(w)
}
    
var words3 : MutableList<String> = mutableListOf("Hello", " ", "World", "!")
  
words3.add("How")
words3.add(" ")
words3.add("are")
words3.add(" ")
words3.add("you ")
words3.add("?")
  
for (w in words3) {
    print(w)
}

Swift

In Swift Arrays and Lists are both called Array
If you declare it var it will be a variable list where you can add elements with append
If you declare it letit becomes an array with a constant immutable size

Both for-loopand forEachmethod are available

var words = ["Hello", ",", " ", "World", "!"]
  
for w in words {
    print(w)
}
  
words.append("How")
words.append(" ")
words.append("Are")
words.append(" ")
words.append("You")
words.append("?")

words.forEach { w in
    print(w)
}