Question

此函数计算字母在给定字符串中出现的频率并将其放入数组中（索引是ascii-number of letter和value ist count occurrence）。现在我需要返回字母（它已经做过）和值。只是通过在线阅读我无法弄清楚如何使用ref和替代品来做到这一点。

static char MostCommonLetter(string s)
    {
        int[] occurrances = new int[255];
        for (int i = 0; i < s.Length; i++)
        {
            if (char.IsLetter(s[i]))
            {
                int ascii = (int)s[i];
                occurrances[ascii]++;
            }
        }
        char maxValue = (char)Array.IndexOf(occurrances, occurrances.Max());
        return maxValue;
    }

Answer 1

在C＃7及以上版本中，Value Tuples是您最好的选择。您可以按如下方式定义函数：

static (char letter, int occurrences) MostCommonLetter(string s)
{
    int[] occurrences = new int[255];
    for (int i = 0; i < s.Length; i++)
    {
        if (char.IsLetter(s[i]))
        {
            int ascii = (int)s[i];
            occurrances[ascii]++;
        }
    }
    char letter = (char)Array.IndexOf(occurrences, occurrences.Max());
    return (index: letter, occurrences: occurrences);
}

然后您可以像这样引用输出：

var (index, occurrences) = MostCommonLetter(yourString);

Answer 2

您可以使用“out”参数从函数中返回其他参数。

    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="2.1.0" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="2.1.0" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Relational" Version="2.1.0" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.1.0" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="2.1.0" />
    <DotNetCliToolReference Include="Microsoft.EntityFrameworkCore.Tools" Version="2.0.0" />
    <DotNetCliToolReference Include="Microsoft.EntityFrameworkCore.Tools.DotNet" Version="2.0.0" />

Answer 3

另一种解决方案是使用LINQ：

string str = "Hello World!";

var result = str.GroupBy(c => c)
                .Select(group => new { Letter = group.Key, Count = group.Count() })
                .OrderByDescending(x => x.Count)
                .First();

char letter = result.Letter;
int count = result.Count;

letter =＆＃39; l＆＃39;

count = 3

Answer 4

在C＃中执行所需操作的最佳和最灵活的方法是使用结构。

以这种方式定义结构并使用它同时返回多个结果（结构甚至可以包含函数......您可以将这些结构看作更亮的类）：

namespace YourApp.AnyNamespace {

    // Other things

    public struct SampleName
    {
        public char mostCommon;
        public int occurancies;
    }
}

如何让函数返回数组的索引和值？

4 个答案: