how to get sum of vowels in list in kotlin答案

【问题标题】：how to get sum of vowels in list in kotlinhow to get sum of vowels in list in kotlin
【发布时间】：2022-12-27 22:17:15
【问题描述】：

i need to get sum of vowels from list of strings with help function .fold

i tried:

val student = listOf("Sheldon", "Leonard", "Howard", "Raj", "Penny", "Amy", "Bernadette")

val vowels = setOf('a','A','e','E','i','I','o','O','y','Y','u','U')

val sumVowels = student.fold(0){acc, student, ->
if(student.contains(vowels)) acc + 1 else acc + 0

I don't know how to place vowels in .contains. Maybe I choose not the right way to solve the problem, but I should use fold anyway

【问题讨论】：

标签： list kotlin contains fold

【解决方案1】：

val list = listOf("Sheldon", "Leonard", "Howard", "Raj", "Penny", "Amy", "Bernadette")
val vowels = setOf('a', 'A', 'e', 'E', 'i', 'I', 'o', 'O', 'y', 'Y', 'u', 'U')

val result = list
  .joinToString("")
  .count { char -> char in vowels }

println(result)   // Output: 16

【讨论】：

While this is good code*, it doesn't strictly answer the question, which asked for a solution using fold(). (* Actually, I think I prefer the slightly more complex but more memory-efficient approach of list.sumOf{ it.count{ it in vowels }}.)

【解决方案2】：

you can write

val sumVowels = student.fold(0){acc, s -> acc + s.count{it in vowels}}

【讨论】：

【解决方案3】：

val list = listOf("Sheldon", "Leonard", "Howard", "Raj", "Penny", "Amy", "Bernadette")
val vowels = setOf('a', 'A', 'e', 'E', 'i', 'I', 'o', 'O', 'y', 'Y', 'u', 'U')
var numberOfVowels = 0
list.forEach{s ->
   numberOfVowels += s.count{it in vowels}
}
println(numberOfVowels)

Output: 16

【讨论】：