使用CodeDom来生成.cs文件

在学使用CodeDom来动态生成.cs文件，使用帮助里的例子，代码居然编译不通过
自己修改，调试通过，整理后主要代码如下：
命名空间：
using System.CodeDom;
using System.CodeDom.Compiler;
using Microsoft.CSharp;
using System.IO;
??private void button1_Click(object sender, System.EventArgs e)
??{
???CodeCompileUnit CompileUnit = new CodeCompileUnit();
???CodeNamespace Samples = new CodeNamespace("Samples");
???Samples.Imports.Add( new CodeNamespaceImport("System") );
???CompileUnit.Namespaces.Add( Samples );
???CodeTypeDeclaration Class1 = new CodeTypeDeclaration("Class1");
???Samples.Types.Add(Class1);
???CodeEntryPointMethod Start = new CodeEntryPointMethod();
???
???//输出HelloWord
???CodeMethodInvokeExpression cs1 = new CodeMethodInvokeExpression( new
????CodeTypeReferenceExpression("System.Console"), "WriteLine", new
????CodePrimitiveExpression("Hello World!") );
???
???Start.Statements.Add(cs1);
???
???Class1.Members.Add( Start );
???//CSharpCodeProvider provider = new CSharpCodeProvider();
???//ICodeGenerator gen = provider.CreateGenerator();
???GenerateGraph(CompileUnit);
??}
??public void GenerateGraph(CodeCompileUnit compileunit)
??{
???// Obtains an ICodeGenerator from a CodeDomProvider class.
???CSharpCodeProvider provider = new CSharpCodeProvider();
???ICodeGenerator gen = provider.CreateGenerator();
??
???// Creates a StreamWriter to an output file.

补充：asp.net教程,基础入门