C#: 通过动态编译获取字符串所表达的值

王朝c#·作者佚名  2006-01-09
窄屏简体版  字體: |||超大  

看到许多人经常问到这个问题: 怎么由字符串 “126 + (256 - 2^4 )”,或者怎么判断 “115 > 56 || 14<45”的结果等等,在MSDN上查了查,写了一个Eval类

/*****************************************************************

** 文件名: Eval.cs

** Copyright (c) 1999 -2003

** 创建人: Phoenix

** 创建日期:

** 修改人:

** 修改日期:

** 描 述: 获取字符串所表示的逻辑意义

** 版 本:1.0

******************************************************************/

using System.CodeDom;

using System.CodeDom.Compiler;

using Microsoft.CSharp;

using System.Reflection;

public class Eval

{

static object GetValue( string value )

{

string codeSnippet = "using System; " + "\r\n" +

"namespace CzG {" + "\r\n" +

" public class Eval" + "\r\n" +

" {" + "\r\n" +

" public Eval(){} " + "\r\n" +

" public object GetValue()" + "\r\n" +

" {" + "\r\n" +

" return " + value + ";" + "\r\n" +

" }" + "\r\n" +

" } }";

CodeSnippetCompileUnit unit = new CodeSnippetCompileUnit( codeSnippet );

ICodeCompiler compiler = new CSharpCodeProvider().CreateCompiler();

CompilerParameters para = new CompilerParameters();

para.ReferencedAssemblies.Add( "System.dll" );

para.GenerateInMemory = true;

para.GenerateExecutable = false;

para.OutputAssembly = "Eval.dll";

Assembly asm = compiler.CompileAssemblyFromDom( para , unit ).CompiledAssembly;

Type type = asm.GetType( "CzG.Eval" );

MethodInfo mi = type.GetMethod( "GetValue" , BindingFlags.Public | BindingFlags.Instance );

object obj = asm.CreateInstance( "CzG.Eval" );

return mi.Invoke( obj , null );

}

}

------------------------------------------------------------------------

调用:

Console.WriteLine( Eval.GetValue(“125 -23” ) );

Console.WriteLine( Eval.GetValue(“125<23“ ) );

Output:

102

False

 
 
 
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