c#正则表达式匹配和替换使用函数 [英] c# Regex match and replace using function

问题描述

/// <summary>
/// Given HTML overlay for an image in the store, render it.
/// [p:n] renders as price for item ID n
/// </summary>
/// <returns>Rendered result</returns>
public static string RenderHTMLOverlay(string overlayHTML, int currencyID)
{
    const string pattern = "\\[p\\:(\\b\\d+\\b)\\]";
    overlayHTML = Regex.Replace(overlayHTML, pattern, FormatCurrency(GetItemPriceOnDate(DateTime.Now, currencyID, int.Parse("$1"))));

    return overlayHTML;
}

这不起作用，因为 $1 无法作为参数正确传递给 int.Parse.

This doesn't work because $1 can't be passed as a parameter correctly to int.Parse.

Exception Details: System.FormatException: Input string was not in a correct format.

有人知道我如何解决这个限制吗?

Does anyone know how I can work around this limitation?

推荐答案

如果 replacement 参数是字符串，你只能使用 $1 表示法，所以你结束了将 $1 作为文字字符串传递给 int.Parse 方法.

You can only use the $1 notation if the replacement argument is a string, so you ended up passing $1 as a literal string to the int.Parse method.

改为使用(String, String, MatchEvaluator) 使用匿名方法重载:

Instead, use the (String, String, MatchEvaluator) overload with an anonymous method:

Regex.Replace(overlayHTML, pattern, 
match => FormatCurrency(GetItemPriceOnDate(DateTime.Now, currencyID, int.Parse(match.Groups[1].Value)))
)

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