string 在 Scala 中有效地重复一个字符/字符串 n 次
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Efficiently repeat a character/string n times in Scala
提问by TimY
I would like to do the following more efficiently:
我想更有效地执行以下操作：
def repeatChar(char:Char, n: Int) = List.fill(n)(char).mkString
def repeatString(char:String, n: Int) = List.fill(n)(char).mkString
repeatChar('a',3) // res0: String = aaa
repeatString("abc",3) // res0: String = abcabcabc
回答by Travis Brown
For strings you can just write "abc" * 3, which works via StringOpsand uses a StringBufferbehind the scenes.
对于字符串，您可以只编写"abc" * 3，它通过StringOps并StringBuffer在幕后使用 a 。
For characters I think your solution is pretty reasonable, although char.toString * nis arguably clearer. Do you have any reason to suspect the List.fillversion isn't efficient enough for your needs? You could write your own method that would use a StringBuffer(similar to *on StringOps), but I would suggest aiming for clarity first and then worrying about efficiency only when you have concrete evidence that that's an issue in your program.
对于角色，我认为您的解决方案非常合理，尽管char.toString * n可以说更清晰。您是否有任何理由怀疑该List.fill版本的效率不足以满足您的需求？您可以编写自己的方法来使用 a StringBuffer（类似于*on StringOps），但我建议首先以清晰为目标，然后仅在您有具体证据表明这是您的程序中存在问题时才担心效率。
