C# 技术备忘 (1)

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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namespace ConsoleApp
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{
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    internal class Program
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    {
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        static void Main(string[] args)
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        {
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            // 模拟错误消息列表
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            List<string> errorMsgList = new List<string>
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            {
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                "Field 'xxx1' is empty.",
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                "Field 'xxx2' is empty.",
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                "Field 'xxx3' is empty.",
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                "Field 'xxx4' is empty."
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            };
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            if (errorMsgList != null && errorMsgList.Any())
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            {
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                // ===== 方式1：使用 StringBuilder =====
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                Console.WriteLine("=========[方式1]=========");
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                StringBuilder valiMesStrBui = new StringBuilder();
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                int index = 1;
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                foreach (string item in errorMsgList.Distinct())
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                {
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                    valiMesStrBui.AppendLine($"{index}.{item}");
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                    index++;
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                }
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                valiMesStrBui.AppendLine("存在上述异常，请维护后再尝试提交");
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                Console.WriteLine(valiMesStrBui.ToString());
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                // ===== 方式2：使用 string.Join + LINQ Select =====
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                Console.WriteLine("=========[方式2]=========");
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                string errorMessages = string.Join(
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                    Environment.NewLine,
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                    errorMsgList.Select((string msg, int i) =>
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                    $"{i + 1}.{msg}")) +
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                    "\n 存在上述异常，请维护后再尝试提交";
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                Console.WriteLine(errorMessages);
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            }
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            Console.ReadKey();
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        }
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    }
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}