C#中的Methode随机字符[重复]

Question

我应该从字符串 txt "jvn" 中，只获取 1 个随机字符，但由于某种原因，它无法正常工作，我还尝试在循环后将我的字符再次转换为字符串，但它不起作用，我没有返回值

static char Zufallszeichen(string s)
{

    Random rnd = new Random();
    string x = "jvn";

    string result = "";
    Convert.ToChar(x);

    for (int i = 0; i < 1; i++)
    {
        result += x.Substring(rnd.Next(0, x.Length), 1);

    }

    return x;
}

Answer 1

我假设您想从输入字符串中获取随机字符，对吧？

首先要做的事情： 您似乎对 C# 或一般编程相当陌生。也许你想要一些tutorials。或者你可以拿一本好的编程书。

尽管如此，让我们来看看这个：

static char Zufallszeichen(string s) /* You never use the argument, why do you have one* */
    {

        Random rnd = new Random();
        string x = "jvn"; // You are creating this string and returning it unchanged at the end

        string result = "";
        Convert.ToChar(x); // This ->returns<- the input as char... so basicly you have to catch the value. But why would you that in the first place

        for (int i = 0; i < 1; i++) // You're looping for 1 iteration (i.e. running the code inside once)
        {
            result += x.Substring(rnd.Next(0, x.Length), 1); // You're appending a random character to the result _string_ but never returning it.

        }

        return x; // You will only return jvn, as x has remained unchanged.
    }

这里有一个非常简单的方法：

public static char GetRandomCharacterFromString(string input)
{
    // Do some basic null-checking
    if(input == null)
    {
        return char.MinValue; // Or throw an exception or, or, or...
    }

    var random = new Random();
    var inputAsCharArray = input.ToCharArray();
    var index = random.Next(0, input.Length);

    return inputAsCharArray[index];
}

编辑：我知道有更简单或更简单的答案，但我希望这种方法更“易于理解”。

Answer 2

跟随为我工作的代码：

static char randomLetter(string s)
    {

        Random rnd = new Random();
        int index = rnd.Next (0, s.Length);
        return s[index];
    }
char leter = randomLetter ("abcdef");