`for` Loops
Learn about Kotlin's `for` loops to iterate over any iterable structure, and how to build ranges for iteration.
We'll cover the following...
In contrast to while
loops, Kotlin’s for
loops work a bit differently than you may be used to from other languages.
for
Loops #
Kotlin’s for
loops are different from many other languages because they’re used in the same manner as for-each loops (or for-in loops). Thus, you always give an iterable to the for
loop over which it iterates:
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for (number in 1..5) println(number) // 1, 2, 3, 4, 5for (number in 1 until 5) println(number) // 1, 2, 3, 4for (number in 1..5 step 2) println(number) // 1, 3, 5for (number in 5 downTo 1) println(number) // 5, 4, 3, 2, 1for (number in 5 downTo 1 step 2) println(number) // 5, 3, 1for (char in 'a'..'c') println(char) // 'a', 'b', 'c'for (planet in planets) println(planet) // "Jupiter", "Saturn", ...for (char in "Venus") println(char) // 'V', 'e', 'n', 'u', 's'
A few things to note here:
- Ranges are commonly used for basic loops, e.g.,
1..5
.- There are utilities to construct more complex ranges,