检查字符串列表中元音的最简单方法

Question

I have the code

List<String> words

There is only currently 2 counted words in the list which are: [0] "abc", [1] "abc"

What is the simplest way of going through the list and checking if a vowel exists in these words?

Answer 1

You can use LINQ to find the list of all words with vowels in it.

string vowels = "aeiou";
List<string> words = new List<string>() { "apple", "crypt" };
List<string> wordsWithVowels = words.Where(w => w.ToArray().Intersect(vowels.ToArray()).Count() > 0).ToList();

OR

List<string> wordsWithVowels = words.Where(w => w.ToArray().Any(c => vowels.ToArray().Contains(Char.ToLower(c)))).ToList();

Use Char.ToLower for case sensitivity

Answer 2

public class VowelChecker
{
    private char[] vowels = new [] { 'a', 'A', 'e', 'E', 'i', 'I', 'o', 'O', 'u', 'U' };

    public bool ContainsVowel(string word)
    {
        foreach (char vowel in vowels)
        {
            if (word.Contains(vowel))
            {
                return true;
            }
        }
        return false;
    }
}

Usage:

List<string> words = new List<string>();
words.Add("ABC");
words.Add("elephant");
words.Add("FLY");

VowelChecker checker = new VowelChecker();
foreach (string word in words)
{
    Console.WriteLine("{0} contains a vowel: {1}", word, checker.ContainsVowel(word));
}

Console.ReadLine();

Results:

Answer 3

This problem is quite easy to solve in various ways... The only thing that is important is to know that not everywhere the lower-to-upper case conversion is the same... See http://blog.codinghorror.com/whats-wrong-with-turkey/ (starting from Strings are where it really starts to get hairy )

To make it short, in Turkey the uppercase of i is İ , while the lowercase of I is ı . see the difference? :-)

string vowels = "aeiou";
List<string> words = new List<string>() { "APPLE", "crypt" };
List<string> wordsWithVowels = words.Where(w => vowels.Any(v => w.IndexOf(v.ToString(), StringComparison.CurrentCultureIgnoreCase) != -1)).ToList();

or probably even more pedantic-correct

CompareInfo comparer = new CultureInfo("en-US").CompareInfo;
List<string> wordsWithVowels = words.Where(w => vowels.Any(v => comparer.IndexOf(w, v, CompareOptions.IgnoreCase) != -1)).ToList();

(where en-US is the language you are looking the vowels of)

There are very good methods to do case insensitive comparisons, and so it is useless and wrong to use ToLower() / ToUpper() to do them.

As I've commented, this is probably moot because the concept of vowel is language-connected, so in Turkey they have different vowels.

Note that even in English, sometimes the y is a vowel (see wiki )

Answer 4

This feels like homework but I'm bored.

public int CountVowels(List<string> words)
{
    return words.Sum(CountVowels);
}

public int CountVowels(string word)
{
    return Enumerable.Range(0, word.Length).Count(i => IsVowel(word, i));
}

public bool IsVowel(string word, int i)
{
    if (i < 0) return false;
    if (i >= word.length) return false;

    switch(word[i].ToLowerCase())
    {
        case 'a':
        case 'e':
        case 'i':
        case 'o':
        case 'u':
            return true;
        case 'y':
            // I'm pretty sure 'y' is a consonant if it follows, 
            // or is followed by a vowel
            return !(IsVowel(word, i-1) || IsVowel(word, i+1));
    }

    return false;
}