Kotlin ‘For’ loop

This post was originally posted at https://agrawalsuneet.github.io/blogs/kotlin-for-loop/ and reposted on Medium on 12th Jan 2018.
Oh no !!!
  1. Simple for loop in java that iterates from some number to some number incrementing one on each loop pass.
for (int i = 0; i <= 10; i++){
System.out.print(i);
}
for (i in 0..10) {
print(i)
}
  • no need to declare the data type of variable
  • if iterating over a range, we can use in variable
  • the lower and upper (including) limit can be defined on both the sides of .. operator.
oh !!!
for (int j = 0; j < 10; j++) {
System.out.print(j); //this will print only up to 9
}
for (j in 0..9) {
print(j)
}
for (j in 0 until 10) {
print(j)
}
Oh I see
for (int i = 0; i <= 10; i += 2) {
System.out.print(i);
}
for (i in 0..10 step 2) {
print(i)
}
for (int i = 10; i > 0; i--) {
System.out.print(i);
}
for (i in 10 downTo 1) {
print(i)
}
Java
for (int i = 10; i > 0; i -= 3) {
System.out.print(i);
}
Kotlin
for (i in 10 downTo 1 step 3) {
print(i)
}
for (int k = 2; k <= 256; k *= 2) {
System.out.print(k);
}
var k = 2
while (k <= 256) {
print(k)
k *= 2
}
int[] arr = new int[5];
for (int i = 0; i < arr.length; i++) {
System.out.print(arr[i]);
}
val arr = IntArray(5)
for (i in arr.indices) {
print(arr[i])
}
int[] arr = new int[5];
for (int item: arr) {
System.out.print(item);
}
for(item in arr){
print(item)
}
List<Integer> arrayList = new ArrayList<>();
for (int i = 0; i < arrayList.size(); i++) {
System.out.print(arrayList.get(i));
}
List<Integer> vector = new Vector<>();
for (int i = 0; i < vector.size(); i++) {
System.out.print(vector.get(i));
}
val arrayList = ArrayList<Int>()
for (i in arrayList.indices) {
print(arrayList[i])
}
val vector = Vector<Int>()
for (i in vector.indices) {
print(vector[i])
}
for (int item : arrayList) {
System.out.print(item);
}
for (int item : vector) {
System.out.print(item);
}
for (item in arrayList) {
print(item)
}
for (item in vector) {
print(item)
}
for ((i, value) in arr.withIndex()) {
println(“the element at $i is $value”)
}

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