C#实现文本文件首元素相同行的字段拼接方案咨询

Got it, let's get this sorted for you! Here's a complete C# implementation that handles the grouping, cleaning, and formatting exactly as your requirements specify:

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;

class Program
{
    static void Main(string[] args)
    {
        string path = "your-file-path-here.txt"; // Replace with your actual file path
        ProcessFile(path);
    }

    static void ProcessFile(string path)
    {
        using (StreamReader reader = new StreamReader(path))
        {
            string fileContent = reader.ReadToEnd();
            string[] lines = fileContent.Split(new string[] { "\n", "\r\n" }, StringSplitOptions.RemoveEmptyEntries);
            
            // Dictionary to group unique second fields by the cleaned first field
            Dictionary<string, HashSet<string>> groupedData = new Dictionary<string, HashSet<string>>();
            
            foreach (string line in lines)
            {
                string[] segments = line.Split(',', StringSplitOptions.RemoveEmptyEntries);
                if (segments.Length < 2) continue; // Skip lines that don't have at least two fields
                
                // Clean the first segment: strip leading zeros, default to "0" if all zeros
                string firstKey = segments[0].TrimStart('0');
                firstKey = string.IsNullOrEmpty(firstKey) ? "0" : firstKey;
                
                // Clean the second segment: strip leading zeros, ignore if it becomes empty (all zeros)
                string secondValue = segments[1].TrimStart('0');
                if (string.IsNullOrEmpty(secondValue)) continue;
                
                // Add the value to the corresponding group
                if (!groupedData.ContainsKey(firstKey))
                {
                    groupedData[firstKey] = new HashSet<string>();
                }
                groupedData[firstKey].Add(secondValue);
            }
            
            // Build the final output string
            StringBuilder outputBuilder = new StringBuilder();
            foreach (var group in groupedData)
            {
                outputBuilder.Append("HI:").Append(group.Key);
                if (group.Value.Count > 0)
                {
                    outputBuilder.Append(",").Append(string.Join(",", group.Value));
                }
                outputBuilder.AppendLine();
            }
            
            // Print the result or write to a file
            Console.WriteLine(outputBuilder.ToString().TrimEnd());
            // Uncomment below to save to a file:
            // File.WriteAllText("formatted-output.txt", outputBuilder.ToString().TrimEnd());
        }
    }
}

Key Details Explained: #

• Grouping Logic: We use a Dictionary paired with a HashSet to automatically handle grouping by the first field and ensure no duplicate second fields are included (even if your input has repeated lines).
• Field Cleaning:
  • The first field is stripped of leading zeros—if the result is empty (like "00000"), we default to "0" to avoid blank keys.
  • The second field is also stripped of leading zeros; if it becomes empty (meaning it was all zeros, like "00000"), we skip adding it to the group (matching your example where these values are omitted from the output).
• Output Formatting: We loop through each group to build lines in the HI:key,value1,value2,... format you need.

内容的提问来源于stack exchange，提问作者Cicciux