<div id="readability-page-1" class="page"><div><h2 id="if-expression">If Expression</h2><code>if</code>는 expression, 즉 값을 return 하므로 <code>tenary operator</code>(condition ? then : else)가 없다고 한다.(난 tenary operator 좋은데..)그럼 if 표현식을 보자<div><pre><code data-lang="kotlin">// Traditional usage
var max = a
if (a &lt; b) max = b

// With else
var max: Int
if (a &gt; b) {
 max = a
} else {
 max = b
}

// As expression
val max = if (a &gt; b) a else b
</code></pre></div>마지막 코드인 <code>val max = if (a &gt; b) a else b</code>가 tenary operator와 비슷해보인다.if문을 이런 식으로 써서 변수에 값을 넣어 줄 수도 있다.<div><pre><code data-lang="kotlin">val max = if (a &gt; b) {
 print("Choose a")
 a
} else {
 print("Choose b")
 b
}
</code></pre></div><h2 id="when-expression">When Expression</h2>when <code>switch</code>와 같은 표현입니다<div><pre><code data-lang="kotlin">when (x) {
 1 -&gt; print("x == 1")
 2 -&gt; print("x == 2")
 else -&gt; { // Note the block
 print("x is neither 1 nor 2")
 }
}

when (x) {
 0, 1 -&gt; print("x == 0 or x == 1")
 else -&gt; print("otherwise")
}

when (x) {
 parseInt(s) -&gt; print("s encodes x")
 else -&gt; print("s does not encode x")
}

when (x) {
 in 1..10 -&gt; print("x is in the range")
 in validNumbers -&gt; print("x is valid")
 !in 10..20 -&gt; print("x is outside the range")
 else -&gt; print("none of the above")
}

fun hasPrefix(x: Any) = when(x) {
 is String -&gt; x.startsWith("prefix")
 else -&gt; false
}

when {
 x.isOdd() -&gt; print("x is odd")
 x.isEven() -&gt; print("x is even")
 else -&gt; print("x is funny")
}


//Since, Kotlin 1.3
fun Request.getBody() =
 when (val response = executeRequest()) {
 is Success -&gt; response.body
 is HttpError -&gt; throw HttpException(response.status)
 }
</code></pre></div><h2 id="for-loops">For Loops</h2><code>for loop</code>는 다음과 같이 표현 할 수 있다.<div><pre><code data-lang="kotlin">for (item in collection) print(item)

for (item: Int in ints) {
 // ...
}

for (i in 1..3) {
 println(i)
}

(0..10).forEach { }

for (i in 6 downTo 0 step 2) {
 println(i)
}

// Iterate through an array or a list with an index
for (i in array.indices) {
 println(array[i])
}

for ((index, value) in array.withIndex()) {
 println("the element at $index is $value")
}
</code></pre></div><code>for</code>는 무엇이든 반복자들이 주어지면 iterate를 한다.<h2 id="while-loops">While Loops</h2>흔히 쓰는 while 문의 형태를 갖고 있다.<div><pre><code data-lang="kotlin">while (x &gt; 0) {
 x--
}

do {
 val y = retrieveData()
} while (y != null) // y is visible here!
</code></pre></div><hr>Reference<ul><li><a href="https://kotlinlang.org/docs/reference/control-flow.html">https://kotlinlang.org/docs/reference/control-flow.html</a></li><li><a href="https://devhints.io/kotlin">https://devhints.io/kotlin</a></li></ul></div></div>

Call Me Maru

CHOI HEE JAE

If Expression if는 expression, 즉 값을 return 하므로 tenary operator(condition ? then : else)가 없다고 한다.(난 tenary operator 좋은데..)
그럼 if 표현식을 보자
// Traditional usage var max = a if (a < b) max = b // With else var max: Int if (a > b) { max = a } else { max = b } // As expression val max = if (a > b) a else b 마지막 코드인 val max = if (a > b) a else b가 tenary operator와 비슷해보인다.

[Maru의 Kotlin Tour - 공식 문서 편] #2 Control Flow

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