帮我把一下lisp代码转成C#，实现相同的功能：(vl-load-com) ; 加载VL函数 (setq source_text nil) ; 设源文字为全局变量 (defun c:22 (/ en en_data en1 en1_data ent entype i ob pt ss ss_data) (setvar "cmdecho" 0) (setvar "ErrNo" 0) (command "_.undo" "begin") (if (= source_text nil) (if (setq en (nentsel "\n请选择源文字(右键退出):")) (setq en_data (entget (car en)) entype (cdr (assoc 0 en_data)) source_text (if (= entype "ATTDEF")(cdr (assoc 2 en_data))(cdr (assoc 1 en_data)));如果是属性字，则取“标记”为源文字 ) ) (if (and (= (setq en (nentsel (strcat "\n请选择源文字: 默认:" source_text))) nil) (= (getvar "ErrNo") 52)) (setvar "ErrNo" 0) (if en (setq en_data (entget (car en)) entype (cdr (assoc 0 en_data)) source_text (if (= entype "ATTDEF")(cdr (assoc 2 en_data))(cdr (assoc 1 en_data))) ) (setvar "ErrNo" 52) ) ) ) (prompt "\n请选择要修改内容的文字:") (while (/= (getvar "ErrNo") 52) (prompt (strcat "\n文字内容将被刷成:" source_text)) (if (and (setq ss (ssget ":S" '((0 . "*TEXT,TCH_DRAWINGNAME,TCH_ELEVATION,INSERT,ATTDEF,ATTRIB")))) source_text) (progn (if (= (caar (setq ss_data (ssnamex ss 0))) 1) (progn ; 点选时 (setq ent (ssname ss 0) pt (cadr (last (car ss_data))) en1 (car (nentselp pt)) en1_data (entget en1) entype (cdr (assoc 0 en1_data)) ob (vlax-ename->vla-object en1) ) (wenzishua entype ob source_text en1 ent) (princ) ) (progn ; 框选时 (setq i 0) (repeat (sslength ss) (setq en1 (ssname ss i) ent en1 en1_data (entget en1) entype (cdr (assoc 0 en1_data)) ob (vlax-ename->vla-object en1) ) (wenzishua entype ob source_text en1 ent) (setq i (1+ i)) ) ; end repeat ) ) ) ) ) ; end while (command ".undo" "_end") (setvar "ErrNo" 0) (setvar "cmdecho" 1) (princ) ) (defun wenzishua (entype ob source_text en1 ent) ; cad文字的内容格式刷 (if (or (= entype "TEXT") (= entype "MTEXT") ) (progn (vla-put-TextString ob source_text) (entupd en1) (entupd ent) ) ) ; 天正文字的内容格式刷 (if (or (= entype "TCH_TEXT") (= entype "TCH_ELEVATION") ) (progn (vlax-put-property ob 'Text source_text) (entupd en1) (entupd ent) ) ) ; 天正图名、标高的内容格式刷 (if (= entype "TCH_DRAWINGNAME") (progn (vlax-put-property ob 'NameText source_text) (entupd en1) (entupd ent) ) ) ; 属性文字 只改"标记" (if (= entype "ATTDEF") (progn (vla-put-TagString ob source_text);改标记 (entupd en1) (entupd ent) ) ) ; 块中属性文字 只改"默认" (if (= entype "ATTRIB") (progn (vla-put-TextString ob source_text);改默认 (entupd en1) (entupd ent) ) ) )

以下是将Lisp代码转换为C#的代码：

using Autodesk.AutoCAD.Interop;
using Autodesk.AutoCAD.Interop.Common;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using System.Collections.Generic;

public static class Program
{
    private static string source_text = null;

    [CommandMethod("22")]
    public static void ChangeTextContent()
    {
        Document doc = Application.DocumentManager.MdiActiveDocument;
        Database db = doc.Database;

        Editor ed = doc.Editor;

        ed.WriteMessage("\n请选择源文字(右键退出):");

        PromptSelectionOptions pso = new PromptSelectionOptions();
        pso.MessageForAdding = "\n请选择源文字: 默认:" + source_text;
        pso.RejectObjectsFromNonCurrentSpace = true;
        pso.RejectObjectsOnLockedLayers = true;
        pso.SingleOnly = true;
        pso.AllowDuplicates = false;
        pso.SinglePickInSpace = true;
        pso.SingleOnly = true;

        PromptSelectionResult psr = ed.GetSelection(pso);

        if (psr.Status != PromptStatus.OK)
            return;

        if (source_text == null)
        {
            source_text = GetSourceText(psr.Value[0]);
        }
        else
        {
            psr = ed.GetSelection(pso);

            if (psr.Status != PromptStatus.OK)
                return;

            source_text = GetSourceText(psr.Value[0]);
        }

        ed.WriteMessage("\n请选择要修改内容的文字:");

        pso.MessageForAdding = "\n请选择要修改内容的文字:";
        pso.SingleOnly = false;

        psr = ed.GetSelection(pso);

        if (psr.Status != PromptStatus.OK)
            return;

        SelectionSet ss = psr.Value;

        using (Transaction tr = db.TransactionManager.StartTransaction())
        {
            foreach (SelectedObject so in ss)
            {
                Entity ent = tr.GetObject(so.ObjectId, OpenMode.ForWrite) as Entity;
                if (ent == null)
                    continue;

                switch (ent.GetRXClass().DxfName)
                {
                    case "TEXT":
                    case "MTEXT":
                        ent.UpgradeOpen();
                        DBText text = ent as DBText;
                        text.TextString = source_text;
                        ent.DowngradeOpen();

                        ent.Update();
                        break;

                    case "TCH_TEXT":
                    case "TCH_ELEVATION":
                        ent.UpgradeOpen();
                        MText mtext = ent as MText;
                        mtext.Contents = source_text;
                        ent.DowngradeOpen();

                        ent.Update();
                        break;

                    case "TCH_DRAWINGNAME":
                        ent.UpgradeOpen();
                        TcHText tchText = ent as TcHText;
                        tchText.NameText = source_text;
                        ent.DowngradeOpen();

                        ent.Update();
                        break;

                    case "ATTRIB":
                        ent.UpgradeOpen();
                        AttributeReference attRef = ent as AttributeReference;
                        if (attRef != null && attRef.Tag == "标记")
                        {
                            attRef.UpgradeOpen();
                            attRef.TagString = source_text;
                            attRef.DowngradeOpen();
                        }
                        ent.Update();
                        break;

                    case "INSERT":
                        BlockReference br = ent as BlockReference;
                        if (br != null)
                        {
                            foreach (ObjectId arId in br.AttributeCollection)
                            {
                                AttributeReference ar = tr.GetObject(arId, OpenMode.ForWrite) as AttributeReference;
                                if (ar == null)
                                    continue;

                                if (ar.Tag == "标记")
                                {
                                    ar.UpgradeOpen();
                                    ar.TagString = source_text;
                                    ar.DowngradeOpen();

                                    ar.Update();
                                }
                                else if (ar.Tag == "默认")
                                {
                                    ar.UpgradeOpen();
                                    ar.TextString = source_text;
                                    ar.DowngradeOpen();

                                    ar.Update();
                                }
                            }
                        }
                        break;

                    default:
                        break;
                }
            }

            tr.Commit();
        }
    }

    private static string GetSourceText(ObjectId id)
    {
        string text = string.Empty;

        using (Transaction tr = id.Database.TransactionManager.StartTransaction())
        {
            Entity ent = tr.GetObject(id, OpenMode.ForRead) as Entity;

            if (ent == null)
                return string.Empty;

            switch (ent.GetRXClass().DxfName)
            {
                case "TEXT":
                case "MTEXT":
                    DBText dbText = ent as DBText;
                    if (dbText != null)
                        text = dbText.TextString;
                    break;

                case "TCH_TEXT":
                case "TCH_ELEVATION":
                    MText mtext = ent as MText;
                    if (mtext != null)
                        text = mtext.Contents;
                    break;

                case "TCH_DRAWINGNAME":
                    TcHText tchText = ent as TcHText;
                    if (tchText != null)
                        text = tchText.NameText;
                    break;

                case "ATTDEF":
                    AttributeDefinition attDef = ent as AttributeDefinition;
                    if (attDef != null && attDef.Tag == "标记")
                        text = attDef.TagString;
                    break;

                case "INSERT":
                    BlockReference br = ent as BlockReference;
                    if (br != null)
                    {
                        foreach (ObjectId arId in br.AttributeCollection)
                        {
                            AttributeReference ar = tr.GetObject(arId, OpenMode.ForRead) as AttributeReference;
                            if (ar == null)
                                continue;

                            if (ar.Tag == "标记")
                            {
                                text = ar.TagString;
                                break;
                            }
                            else if (ar.Tag == "默认")
                            {
                                text = ar.TextString;
                                break;
                            }
                        }
                    }
                    break;

                default:
                    break;
            }

            tr.Commit();
        }

        return text;
    }
}

请注意，由于Lisp和C#有很大的不同，因此在转换过程中，一些细节和逻辑可能会有所不同。