Question

Random rnd = new Random(DateTime.Now.Millisecond);

string rt = "tst xtstx xtste tst tst!!";

if (rnd.Next(3) == 0)
{
    string[] replaceWords = { "something", "nice" };
    rt.Replace("tst", replaceWords[rnd.Next(replaceWords.Length - 1)]);
}
if (rnd.Next(3) == 0)
{
    string[] replaceWords = { "cool", "crazy" };
    rt.Replace("xtste", replaceWords[rnd.Next(replaceWords.Length - 1)]);
}

我想用一个随机的单词替换一个单词，有33％的几率。问题是如果我运行它将替换所有出现的tst，并且只替换这种情况：

string rt = "tst xtstx xtste tst tst!!";
//           /\              /\  /\

有一种更好的方法来替换这些单词吗？我将在我的代码中多次使用相同的想法。

Answer 1

您需要使用正则表达式。

匹配所有tst字词的正则表达式，您需要使用\btst\b正则表达式。

要替换所有出现，请使用Regex.Replace方法之一。

Here is a something similar example

也不要使用Random(DateTime.Now.Millisecond)，Random的默认构造函数的种子比此更好。

示例：

static Random rnd = new Random();
static string Replace(string input, string word, params string[] words)
{
     return Regex.Replace(input, "\b" + word + "\b", m=>words[rnd.Next(words.Length)]);
}

现在您可以将其用作：

string rt = "tst xtstx xtste tst tst!!";

if (rnd.Next(3) == 0)
{
    rt = Replace(rt, "tst", "something", "nice");
}
if (rnd.Next(3) == 0)
{
    rt = Replace(rt, "xtste", "cool", "crazy");
}

Answer 2

这样做。使用Regex.Replace和/b仅使用单词。

Random rnd = new Random(DateTime.Now.Millisecond);

string rt = "tst xtstx xtste tst tst!!";

if (rnd.Next(3) == 0)
{
    string[] replaceWords = { "something", "nice" };
    rt = Regex.Replace(rt, @"\tst\b", replaceWords[rnd.Next(replaceWords.Length - 1)]);
}
if (rnd.Next(3) == 0)
{
    string[] replaceWords = { "cool", "crazy" };
    rt = Regex.Replace(rt, @"\xtste\b", replaceWords[rnd.Next(replaceWords.Length - 1)]);
}

做一些重复工作的方法。

public string ReplaceRandom(string[] words, string wordToReplace, string inputString)
{
    Random rnd = new Random(DateTime.Now.Millisecond);
    inputString = Regex.Replace(inputString, @"\b" + wordToReplace + @"\b", words[rnd.Next(words.Length - 1)]);
    return inputString;
}

或者，如果你想使用扩展方法来坚持你可以做的String.Replace思路。使用rt.ReplaceWithRandom(replaceWords, "tst");

进行调用

public static string ReplaceWithRandom(this string inputString, string[] words, string wordToReplace)
{
    Random rnd = new Random(DateTime.Now.Millisecond);
    inputString = Regex.Replace(inputString, @"\b" + wordToReplace + @"\b", words[rnd.Next(words.Length - 1)]);
}

Answer 3

您可以使用\b来表示带有正则表达式的单词边界。

另外 - 不要忘记分配回原始字符串！

Random rnd = new Random();

string rt = "tst xtstx xtste tst tst!!";

if (rnd.Next(3) == 0)
{
    string[] replaceWords = { "something", "nice" };
    rt = Regex.Replace(rt, @"\btst\b", replaceWords[rnd.Next(replaceWords.Length - 1)]);
}
if (rnd.Next(3) == 0)
{
    string[] replaceWords = { "cool", "crazy" };
    rt = Regex.Replace(rt, @"\bxtste\b", replaceWords[rnd.Next(replaceWords.Length - 1)]);
}

Answer 4

在我看来，你想为每场比赛想要一个不同的随机词。这是一个为你做这个的课程。

public class RandomStringReplacer
{
    // no need to seed this w/ the current time, the default constructor does that already
    private readonly Random _random = new Random();

    private readonly Regex _regex;

    private readonly string[] _replacementStrings;

    public RandomStringReplacer(string pattern, params string[] replacementStrings)
    {
        _regex = new Regex(pattern);
        _replacementStrings = replacementStrings.ToArray();
    }

    // each time we get a replacement string, a randomly selected one is chosen
    private string RandomReplacement
    {
        get { return _replacementStrings[_random.Next(_replacementStrings.Length)]; }
    }

    public string Replace(string text)
    {
        var random = new Random();
        var result = text;

        // get the matches as a stack, because we want to replace backwards so that indexes still match the correct spot in the string
        var matches = new Stack<Match>(_regex.Matches(text).OfType<Match>());
        while (matches.Count > 0)
        {
            var match = matches.Pop();
            // each match has a 1/3 chance to be replaced
            if (random.Next(3) == 0)
            {
                result = result.Remove(match.Index, match.Length).Insert(match.Index, RandomReplacement);
            }
        }
        return result;
    }
}

用法：

var replacements = new[]{"foo", "bar", "FUBAR"};
var pattern = @"(tst)|(xtste)";
var replacer = new RandomStringReplacer(pattern, replacements);

var text = "tst xtstx xtste tst tst!!";
replacer.Replace(text).Dump();

检查字符串是否包含单词

4 个答案: