{"id":7294,"date":"2022-09-07T23:37:24","date_gmt":"2022-09-07T18:07:24","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-when-to-use-return-statements-in-scala\/"},"modified":"2022-09-07T23:37:24","modified_gmt":"2022-09-07T18:07:24","slug":"solved-when-to-use-return-statements-in-scala","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-when-to-use-return-statements-in-scala\/","title":{"rendered":"[Solved] When to use return statements in Scala?"},"content":{"rendered":"

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The key is to understand in Scala if-else expressions<\/strong> are just that – expressions<\/strong>, not control structures. Hence<\/p>\n

if (x == 5) \"equal to 5\"\n<\/code><\/pre>\n
does not mean <\/p>\n
“if x equals five, then return five”,<\/em> <\/p>\n
instead it means something like<\/p>\n
“if x equals five, then evaluate this expression to five, otherwise evaluate to uknown value.”<\/em><\/p>\n
In fact we could write<\/p>\n
val v: Any = if (x == 5) \"equal to 5\"\n<\/code><\/pre>\n
Note how the type of v<\/code> is Any<\/code>, because we have not provided the else<\/code> part of the expression, so the best compiler can do is deduce Any<\/code> type. Providing else clause we have<\/p>\n
val v: String = if (x == 5) \"equal to 5\" else \"not equal to 5\"\n<\/code><\/pre>\n
where we see v<\/code> is now nicely typed to String<\/code> as required. Now in Scala if we put an expression as the last<\/strong> expression in the block, then this becomes the return value of the function. Thus<\/p>\n
def temp(x: Int): String = {\n  if (x == 5)\n    \"equal to 5\"\n  \"not equal to 5\"\n}  \n<\/code><\/pre>\n
is equivalent to<\/p>\n
def temp(x: Int): String = {\n  val v1: Any = if (x == 5) \"equal to 5\"\n  \/\/ do nothing with v1\n\n  val v2: String = \"not equal to 5\"\n  return v2\n}  \n<\/code><\/pre>\n
where we see temp<\/code> will always return just v2<\/code>. Instead we should write simply<\/p>\n
def temp(x: Int): String =\n  if (x == 5) \"equal to 5\" else \"not equal to 5\"\n<\/code><\/pre>\n
We could say if-else expression acts as a traditional control structure only when it is the last expression in the block.<\/p>\n
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More formally, in conditional expression<\/a> if (?1) ?2 else ?3<\/code><\/p>\n