Print 0001 to 1000 in Kotlin. How to add padding to numbers?
KotlinKotlin Problem Overview
I want to print 0001 (note the 3 preceding 0s), and incremental 1 at a time, and reach 1000 to stop. How could I do that in Kotlin without complex appending the 0s myself?
The below is not helping as it will not have preceding 0s.
for (i in 1..1000) print(i)
Kotlin Solutions
Solution 1 - Kotlin
You can use padStart:
(0..1000)
.map { it.toString().padStart(4, '0') }
.forEach(::println)
It’s part of the Kotlin Standard Library and available for all platforms.
Solution 2 - Kotlin
If you are satisfied with a JVM-specific approach, you can do what you'd to in Java:
(1..1000).forEach { println("%04d".format(it)) }
String.format is an extension function defined in StringsJVM and it delegates straight to the underlying String.format, so it's not in the universal standard library.
Solution 3 - Kotlin
In Kotlin you can use String.format() (the same as in Java):
"%04d".format(i)
In your case, you can write down it in the following way:
(1..1000).forEach { println("%04d".format(it)) }
Solution 4 - Kotlin
Just to be clear, for-loops are fine too:
for(i in 1..1000)
println("%04d".format(i))
Solution 5 - Kotlin
With PadStart and without any map or multiple loops,
(0..1000).forEach { println(it.toString().padStart(4, '0')) }
Solution 6 - Kotlin
Using a string template will call toString() under the hood and make the call even shorter:
(0..1000).forEach { println("$it".padStart(4, '0')) }
Mapping it first, is unecessary effort.