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如何有效地从字符串中间修剪选定的字符?

string performance .net c#

Meidan Alon · 技术社区 · 17 年前

我想到的最好的办法是:

public static string Trim(this string word, IEnumerable<char> selectedChars)
{
    string result = word;
    foreach (char c in selectedChars)
        result = result.Replace(c.ToString(), "");
    return result;
}

但还是太慢了。

2 回复 | 直到 17 年前

Jon Skeet 17 年前

我想到了两个选择:

使用StringBuilder

这是我的建议 StringBuilder 版本:

public static string Trim(this string word, IEnumerable<char> selectedChars)
{
    // The best form for this will depend largely on the size of selectedChars
    // If you can change how you call the method, there are optimisations you
    // could do here
    HashSet<char> charSet = new HashSet<char>(selectedChars);

    // Give enough capacity for the whole word. Could be too much,
    // but definitely won't be too little
    StringBuilder builder = new StringBuilder(word.Length);

    foreach (char c in word)
    {
        if (!charSet.Contains(c))
        {
            builder.Append(c);
        }
    }
    return builder.ToString();
}

如果您有一个要修剪的字符集,可以构建正则表达式 .

// Put this statically somewhere
Regex unwantedChars = new Regex("[def]", RegexOptions.Compiled);

// Then do this every time you need to use it:
word = unwantedChars.Replace(word, "");