仅用Regex替换某些组

让我们假设我有以下正则表达式:

-(\d+)-

我想用c#将Group 1 (\d+)替换为AA，得到:

-AA-

现在我用:

var text = "example-123-example";
var pattern = @"-(\d+)-";
var replaced = Regex.Replace(text, pattern, "-AA-");

但我真的不喜欢这样，因为如果我改变模式来匹配_(\d+)_，我将不得不改变替换字符串由_AA_，这是违反DRY原则。

我想要的是:

保持匹配的文本完全是如何，但改变组1的文本和组2的另一个文本…

编辑: 这只是一个例子。我只是在寻找一种通用的方法来做上面所说的事情。

它应该适用于:

任何(\d+)更多的文本和任何你能想象的图案。

我所要做的只是替换组，并保留其余的匹配。

当前回答

你可以使用前向和后向来做到这一点:

var pattern = @"(?<=-)\d+(?=-)";
var replaced = Regex.Replace(text, pattern, "AA");

2011-05-15 00:13:58

其他回答

替换代码:

var text = "example-123-example";
var pattern = @"-(\d+)-";
var replaced = Regex.ReplaceGroupValue(text, pattern, 1, "AA");

扩展类:

public static class RegexExtensions
{
    [Pure]
    public static string ReplaceGroupValue(this Regex source, string input, string groupName, string destinationValue)
    {
        return ReplaceGroupValue(
            source,
            input,
            m => m.Groups[groupName],
            p => destinationValue);
    }

    [Pure]
    public static string ReplaceGroupValue(this Regex source, string input, int groupIdx, string destinationValue)
    {
        return ReplaceGroupValue(
            source,
            input,
            m => m.Groups[groupIdx],
            p => destinationValue);
    }

    [Pure]
    public static string ReplaceGroupValue(this Regex source, string input, string groupName, Func<string, string> destinationValueSelector)
    {
        return ReplaceGroupValue(
            source,
            input,
            m => m.Groups[groupName],
            destinationValueSelector);
    }

    [Pure]
    public static string ReplaceGroupValue(this Regex source, string input, int groupIdx, Func<string, string> destinationValueSelector)
    {
        return ReplaceGroupValue(
            source,
            input,
            m => m.Groups[groupIdx],
            destinationValueSelector);
    }

    [Pure]
    private static string ReplaceGroupValue(
        Regex source,
        string input,
        Func<Match, Group> groupSelector,
        Func<string, string> destinationValueSelector)
    {
        var matchResult = source.Matches(input);

        if (matchResult.Count <= 0)
        {
            return input;
        }

        var text = input;

        foreach (var group in matchResult.OfType<Match>().Select(groupSelector).OrderByDescending(p => p.Index))
        {
            var begin = group.Index > 0 ? text.Substring(0, group.Index) : string.Empty;
            var end = group.Index + group.Length < text.Length
                ? text.Substring(group.Index + group.Length)
                : string.Empty;
            var destinationValue = destinationValueSelector.Invoke(group.Value);
            text = $"{begin}{destinationValue}{end}";
        }

        return text;
    }
}

2021-05-19 14:43:46

如果你不想改变你的模式，你可以使用匹配组的Group Index和Length属性。

var text = "example-123-example";
var pattern = @"-(\d+)-";
var regex = new RegEx(pattern);
var match = regex.Match(text);

var firstPart = text.Substring(0,match.Groups[1].Index);    
var secondPart = text.Substring(match.Groups[1].Index + match.Groups[1].Length);
var fullReplace = firstPart + "AA" + secondPart;

2013-02-01 15:52:33

这是另一个很好的干净的选择，不需要改变你的模式。

        var text = "example-123-example";
        var pattern = @"-(\d+)-";

        var replaced = Regex.Replace(text, pattern, (_match) =>
        {
            Group group = _match.Groups[1];
            string replace = "AA";
            return String.Format("{0}{1}{2}", _match.Value.Substring(0, group.Index - _match.Index), replace, _match.Value.Substring(group.Index - _match.Index + group.Length));
        });

2015-06-15 18:24:45

我也有这个需要，我为它创建了以下扩展方法:

public static class RegexExtensions
{
    public static string ReplaceGroup(
        this Regex regex, string input, string groupName, string replacement)
    {
        return regex.Replace(
            input,
            m =>
            {
                var group = m.Groups[groupName];
                var sb = new StringBuilder();
                var previousCaptureEnd = 0;
                foreach (var capture in group.Captures.Cast<Capture>())
                {
                    var currentCaptureEnd =
                        capture.Index + capture.Length - m.Index;
                    var currentCaptureLength =
                        capture.Index - m.Index - previousCaptureEnd;
                    sb.Append(
                        m.Value.Substring(
                            previousCaptureEnd, currentCaptureLength));
                    sb.Append(replacement);
                    previousCaptureEnd = currentCaptureEnd;
                }
                sb.Append(m.Value.Substring(previousCaptureEnd));

                return sb.ToString();
            });
    }
}

用法:

var input = @"[assembly: AssemblyFileVersion(""2.0.3.0"")][assembly: AssemblyFileVersion(""2.0.3.0"")]";
var regex = new Regex(@"AssemblyFileVersion\(""(?<version>(\d+\.?){4})""\)");


var result = regex.ReplaceGroup(input , "version", "1.2.3");

结果:

[assembly: AssemblyFileVersion("1.2.3")][assembly: AssemblyFileVersion("1.2.3")]

2014-08-26 19:42:15

你可以使用前向和后向来做到这一点:

var pattern = @"(?<=-)\d+(?=-)";
var replaced = Regex.Replace(text, pattern, "AA");

2011-05-15 00:13:58

仅用Regex替换某些组

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