如何编写函数提取XML标签<>中的所有字符串并返回列表？

To solve this problem, we can use regular expressions to efficiently match and extract the tag names between < and > (ignoring closing tags like </TagName>). Here's a straightforward implementation tailored to your needs:

Step 1: Add Required Namespaces #

First, include these namespaces at the top of your C# file to access the necessary classes:

using System.Collections.Generic;
using System.Text.RegularExpressions;

Step 2: Implement the getTypes Function #

This function uses a regex pattern to find all opening tag names, captures them, and returns them as a List<string>:

public List<string> getTypes(string input)
{
    List<string> tagNames = new List<string>();
    
    // Regex pattern to match opening tags (e.g., <FirstName>)
    // Captures content inside <> that doesn't start with a slash (avoids closing tags)
    string pattern = @"<([^/>]+)>";
    MatchCollection matches = Regex.Matches(input, pattern);
    
    foreach (Match match in matches)
    {
        // Extract the captured tag name (group 1) and add to the list
        if (match.Groups.Count > 1)
        {
            string cleanTagName = match.Groups[1].Value.Trim();
            // Skip empty strings in case tags have extra whitespace
            if (!string.IsNullOrEmpty(cleanTagName))
            {
                tagNames.Add(cleanTagName);
            }
        }
    }
    
    return tagNames;
}

Regex Pattern Breakdown #

• <: Matches the opening angle bracket.
• ([^/>]+): Captures one or more characters that are not / or > (this skips closing tags like </FirstName>).
• >: Matches the closing angle bracket.

Step 3: Use the Function with Your Example #

Here's how to integrate this function into your code as you described:

string s = "<FirstName> John </FirstName> <LastName> Snow </LastName>";
List<string> container = getTypes(s);

foreach(string item in container)
{
    Console.WriteLine(item);
}

Expected Output #

FirstName
LastName

Optional: Get Unique Tag Names #

If you want to avoid duplicate tag names (e.g., if the input has multiple instances of the same tag), use a HashSet to store unique values before converting back to a list:

public List<string> getUniqueTypes(string input)
{
    HashSet<string> uniqueTags = new HashSet<string>();
    string pattern = @"<([^/>]+)>";
    MatchCollection matches = Regex.Matches(input, pattern);
    
    foreach (Match match in matches)
    {
        if (match.Groups.Count > 1)
        {
            string cleanTagName = match.Groups[1].Value.Trim();
            if (!string.IsNullOrEmpty(cleanTagName))
            {
                uniqueTags.Add(cleanTagName);
            }
        }
    }
    
    return uniqueTags.ToList();
}

Quick Note #

This solution works great for simple tag structures. For complex HTML/XML (like nested tags or malformed markup), consider using a dedicated parser (such as XmlDocument or HtmlAgilityPack) instead of regex—regex can struggle with edge cases in full markup languages.

内容的提问来源于stack exchange，提问作者Gashio Lee