参见英文答案 > My regex is matching too much. How do I make it stop?5个
我需要替换一个字符串,它遵循一个特定的字符串和一些不同的数据.我需要保持开头和中间,只需更换结束.当我尝试下面的代码时,它只替换最后一次出现.我试过切换到非贪婪的比赛,但后来却找不到它.中间可以包含新的行,空格,字母和数字.

String s = "Beginning of story. Keep this sentence. Old ending.\n";
s += s;
s += s;
s1 = Regex.Replace(s,@"Beginning of story. ([\s\S]*) Old ending.","Beginning of story. " + @"$1" + " New ending.",RegexOptions.Multiline | RegexOptions.IgnoreCase);

The result is this:
Beginning of story. Keep this sentence. Old ending.
Beginning of story. Keep this sentence. Old ending.
Beginning of story. Keep this sentence. Old ending.
Beginning of story. Keep this sentence. New ending.

如何更换“旧结局”的每一次出现.

我认为Kendall正在使用相关链接 a non greedy match,例如

s1 = Regex.Replace(s,@"Beginning of story. ([\s\S]*?) Old ending.",RegexOptions.Multiline | RegexOptions.IgnoreCase);

应该做的伎俩.

编辑：

您还应该能够将捕获区域内的模式更改为：.*在哪里将匹配除换行符之外的任何字符.

我有一个字符串数组：

string[] arr2 = { "/","@","&" };

我有另一个字符串(即strValue).是否有一种干净的方法用单个值(即下划线)替换数组内容的所有实例？所以之前：

strValue = "a/ new string,with some@ values&"

之后：

strValue = "a_ new string,with some_ values_"

我考虑过这样做：

strValue = strValue.Replace("/","_");
strValue = strValue.Replace("@","_");
strValue = strValue.Replace("&","_");

但我要替换的角色数组可能会变得更大.

你可以自己编写,而不是一遍又一遍地使用替换.这可能是你提到的性能提升

But my array may get a lot bigger.

public string Replace(string original,char replacement,params char[] replaceables)
{
    StringBuilder builder = new StringBuilder(original.Length);
    HashSet<char> replaceable = new HashSet<char>(replaceables);
    foreach(Char character in original)
    {
        if (replaceable.Contains(character))
            builder.Append(replacement);
        else
            builder.Append(character);
    }
    return builder.ToString();
}

public string Replace(string original,string replaceables)
{
    return Replace(original,replacement,replaceables.tochararray());
}

可以像这样调用：

Debug.WriteLine(Replace("a/ new string,with some@ values&",'_','/','@','&'));
Debug.WriteLine(Replace("a/ new string,new[] { '/','&' }));
Debug.WriteLine(Replace("a/ new string,existingArray));
Debug.WriteLine(Replace("a/ new string,"/@&"));

输出：

a_ new string,with some_ values_
a_ new string,with some_ values_

正如@Sebi指出的那样,这也可以作为一种扩展方法：

public static class StringExtensions
{
    public static string Replace(this string original,params char[] replaceables)
    {
        StringBuilder builder = new StringBuilder(original.Length);
        HashSet<Char> replaceable = new HashSet<char>(replaceables);
        foreach (Char character in original)
        {
            if (replaceable.Contains(character))
                builder.Append(replacement);
            else
                builder.Append(character);
        }
        return builder.ToString();
    }

    public static string Replace(this string original,string replaceables)
    {
        return Replace(original,replaceables.tochararray());
    }
}

用法：

"a/ new string,with some@ values&".Replace('_','&');
existingString.Replace('_','&' });
// etc.