昨天一个同学叫我帮编写一个符号三角形的c代码，今天就把它改写成用CodeDom生成的c#代码。

    符号三角形：在一组字符串里（只有用空格分割的+或者-组成的字符串），在每次的相邻的两个符号比较，如果相同就在中间空格插入+,否则就插入-。一直运行到字符串里只有一个+或者-时停止，输出的字符串为符号三角形。

由于是CodeDom些列，所以先介绍几个CodeDom表达式：

1：CodeConditionStatement：判断语句即是if（condition）{} else{}，看最全的那个构造函数：

public CodeConditionStatement(
CodeExpression condition,//条件
CodeStatement[] trueStatements,//为true的语句体
CodeStatement[] falseStatements//为false语句体
)

2：CodeIterationStatement()：表示 for 语句或语句块内的循环（使用测试表达式作为继续循环的条件）：

在codedom中没有提高while和dowhile但是For已经够用的

public CodeIterationStatement(
CodeStatement initStatement,//for初始化
CodeExpression testExpression,//条件表达式
CodeStatement incrementStatement,//for变化体，增或减
CodeStatement[] statements//循环体
)

3：CodeBinaryOperatorExpression：表示一个表达式，该表达式包含在两个表达式间进行的二进制运算,

public CodeBinaryOperatorExpression(
CodeExpression left,//表达式左边
CodeBinaryOperatorType op,//操作符
CodeExpression right//表达式右边
)

4：CodeArrayIndexerExpression：表示对数组的索引的引用：

public CodeArrayIndexerExpression(
CodeExpression targetObject,//数组对象
CodeExpression[] indices//下标
)

其他参见CodeDOM 快速参考：msdn.microsoft.com/zh-cn/library/f1dfsbhc(VS.80).aspx

code：

public CodeNamespace CreateNameSpace()
{
public CodeNamespace CreateNameSpace()
{
//Test
CodeMemberMethod test = new CodeMemberMethod();
test.Name = "Test";
test.Attributes = MemberAttributes.Public | MemberAttributes.Final;
test.Statements.Add(new CodeVariableDeclarationStatement(typeof(char[]), "ch", 

new CodeMethodInvokeExpression(new CodePrimitiveExpression("+ - + - + + - -"), "ToCharArray", 

new CodeExpression[] { })));
test.Statements.Add(new CodeMethodInvokeExpression(new CodeMethodReferenceExpression

(new CodeThisReferenceExpression(), "FuHaoSanJiao"), new CodeExpression[] { new CodeVariableReferenceExpression("ch"),

 new CodePrimitiveExpression(0) }));
test.Statements.Add(new CodeMethodInvokeExpression(new CodeTypeReferenceExpression("System.Console"), "Read"));
//FuHaoSanJiao
CodeMemberMethod fuHaoSanJiao = new CodeMemberMethod();
fuHaoSanJiao.Name = "FuHaoSanJiao";
fuHaoSanJiao.Parameters.Add(new CodeParameterDeclarationExpression(new CodeTypeReference(typeof(char[])), 

"ch"));
fuHaoSanJiao.Parameters.Add(new CodeParameterDeclarationExpression(new CodeTypeReference(typeof(int)), "start"));
fuHaoSanJiao.Statements.Add(new CodeMethodInvokeExpression(new CodeTypeReferenceExpression("System.Console"), 

"WriteLine", new CodeExpression[] { new CodeObjectCreateExpression(typeof(string), new CodeArgumentReferenceExpression("ch")) }));
fuHaoSanJiao.Statements.Add(new CodeConditionStatement(new CodeBinaryOperatorExpression(

new CodeArgumentReferenceExpression("start"), CodeBinaryOperatorType.GreaterThanOrEqual,
(new CodeBinaryOperatorExpression(new CodePropertyReferenceExpression(

new CodeArgumentReferenceExpression("ch"),"Length"),
CodeBinaryOperatorType.Divide ,new CodePrimitiveExpression(2)))),
new CodeMethodReturnStatement()));
CodeBinaryOperatorExpression condition=new CodeBinaryOperatorExpression(

new CodeVariableReferenceExpression("i"),
CodeBinaryOperatorType.LessThan,
new CodeBinaryOperatorExpression(new CodeBinaryOperatorExpression(new CodePropertyReferenceExpression(new CodeArgumentReferenceExpression("ch"),"Length"),
CodeBinaryOperatorType.Subtract ,new CodeArgumentReferenceExpression("start")), CodeBinaryOperatorType.Subtract,
new CodePrimitiveExpression(1)));//for 条件
CodeConditionStatement iterationBody=new CodeConditionStatement(new CodeBinaryOperatorExpression(
new CodeArrayIndexerExpression(new CodeArgumentReferenceExpression("ch"),

new CodeVariableReferenceExpression("i")),
CodeBinaryOperatorType.IdentityEquality, new CodeArrayIndexerExpression(

new CodeArgumentReferenceExpression("ch"),
new CodeBinaryOperatorExpression(new CodeVariableReferenceExpression("i"),

 CodeBinaryOperatorType.Add,new CodePrimitiveExpression(2)))),
new CodeAssignStatement(
new CodeArrayIndexerExpression(new CodeArgumentReferenceExpression("ch"),

new CodeBinaryOperatorExpression(new CodeVariableReferenceExpression("i"), CodeBinaryOperatorType.Add,

new CodePrimitiveExpression(1))),
new CodePrimitiveExpression('+')));
iterationBody.FalseStatements.Add(new CodeAssignStatement(
new CodeArrayIndexerExpression(new CodeArgumentReferenceExpression("ch"),

new CodeBinaryOperatorExpression(new CodeVariableReferenceExpression("i"), CodeBinaryOperatorType.Add,

new CodePrimitiveExpression(1))),
new CodePrimitiveExpression('-')));
CodeAssignStatement iteerationbody2 = new CodeAssignStatement(new CodeArrayIndexerExpression(

new CodeArgumentReferenceExpression("ch"), new CodeVariableReferenceExpression("i")),
new CodePrimitiveExpression(' '));
fuHaoSanJiao.Statements.Add(new CodeIterationStatement(new CodeVariableDeclarationStatement(typeof(int), 

"i", new CodeArgumentReferenceExpression("start")), condition,
new CodeAssignStatement(new CodeVariableReferenceExpression("i"),new CodeBinaryOperatorExpression(

new CodeVariableReferenceExpression("i"), CodeBinaryOperatorType.Add,
new CodePrimitiveExpression(2))), new CodeStatement[] { iterationBody, iteerationbody2 }));
// ch[ch.Length - start - 1] = ' ';
fuHaoSanJiao.Statements.Add(new CodeAssignStatement(
new CodeArrayIndexerExpression(new CodeArgumentReferenceExpression("ch"), 

new CodeBinaryOperatorExpression(new CodeBinaryOperatorExpression(

new CodePropertyReferenceExpression(new CodeArgumentReferenceExpression("ch"), "Length"),
CodeBinaryOperatorType.Subtract ,new CodeArgumentReferenceExpression("start")),

 CodeBinaryOperatorType.Subtract,
new CodePrimitiveExpression(1))),new CodePrimitiveExpression(' ')));
//  FuHaoSanJiao(ch, start + 1);
fuHaoSanJiao.Statements.Add(new CodeMethodInvokeExpression(new CodeThisReferenceExpression(),

"FuHaoSanJiao",new CodeArgumentReferenceExpression("ch")        ,
new CodeBinaryOperatorExpression(new CodeArgumentReferenceExpression("start"),

 CodeBinaryOperatorType.Add, new CodePrimitiveExpression(1))));
CodeTypeDeclaration codeDomDemo2 = new CodeTypeDeclaration("CodeDomDemo2");
codeDomDemo2.Members.Add(test);
codeDomDemo2.Members.Add(fuHaoSanJiao);
codeDomDemo2.Attributes = MemberAttributes.Public;
codeDomDemo2.Comments.Add(new CodeCommentStatement("this code is from CodeDom!"));
//codeDomDemo2.Members.AddRange();
CodeNamespace nspace = new CodeNamespace("CodeDomDemo2");
nspace.Imports.Add(new CodeNamespaceImport("System"));
nspace.Types.Add(codeDomDemo2);
return nspace;
}
}
}

输出代码为 ：

namespace CodeDomDemo2
{
using System;
// this code is from CodeDom!
public class CodeDomDemo2
{
public void Test()
{
char[] ch = "+ - + - + + - -".ToCharArray();
this.FuHaoSanJiao(ch, 0);
System.Console.Read();
}
private void FuHaoSanJiao(char[] ch, int start)
{
System.Console.WriteLine(new string(ch));
if ((start
>= (ch.Length / 2)))
{
return;
}
for (int i = start; (i
< ((ch.Length - start)
- 1)); i = (i + 2))
{
if ((ch[i] == ch[(i + 2)]))
{
ch[(i + 1)] = '+';
} else
{
ch[(i + 1)] = '-';
}
ch[i] = ' ';
}
ch[((ch.Length - start)
- 1)] = ' ';
this.FuHaoSanJiao(ch, (start + 1));
}
}
}

代码下载Demo1，Demo2