.Net实现表达式计算(公式) 表达式字符串

文档原址：/article/1408176.html

实现复杂公式计算，比如含IF分支判断等，可考虑通过调用EXCEL公式获取值。

Excel公式计算参考：/article/6011426.html

方法一： MSScriptControl.ScriptControl

VB.NET

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Dim exp As String = "3 + 4"

Dim t As Type = Type.GetTypeFromProgID("MSScriptControl.ScriptControl")

Dim obj As Object = Activator.CreateInstance(t)

t.InvokeMember("Language", System.Reflection.BindingFlags.SetProperty, _

Nothing, obj, New Object() {"vbscript"})

Dim result As Object = t.InvokeMember("Eval", System.Reflection.BindingFlags.InvokeMethod, _

Nothing, obj, New Object() {exp})

MsgBox("method 1: " & CStr(result))

C#

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var exp = "3 + (2 + 3)/5";

var type = Type.GetTypeFromProgID("MSScriptControl.ScriptControl");

var obj = Activator.CreateInstance(type);

type.InvokeMember("Language", BindingFlags.SetProperty, null,

obj, new object[] { "javascript" });

var result = type.InvokeMember("Eval", BindingFlags.InvokeMethod, null,

obj, new object[] { exp });

Console.WriteLine("{0} = {1}", exp, result);

方法二： CodeDOM

VB.NET

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Dim oCodeProvider As VBCodeProvider = New VBCodeProvider

Dim oCParams As CompilerParameters = New CompilerParameters

Dim oCResults As CompilerResults = Nothing

Dim oAssy As System.Reflection.Assembly = Nothing

Dim oExecInstance As Object = Nothing

Dim oRetObj As Object = Nothing

Dim oMethodInfo As MethodInfo = Nothing

Dim oType As Type = Nothing

Dim strSource As String = _

"Public Class MainClass " + vbCrLf + _

" Public Shared Function Eval() As Integer" + vbCrLf + _

" Return 3 + 4" + vbCrLf + _

" End Function" + vbCrLf + _

"End Class"

oCParams.CompilerOptions = "/t:library"

oCParams.GenerateInMemory = True

oCResults = oCodeProvider.CompileAssemblyFromSource(oCParams, strSource)

If oCResults.Errors.Count <> 0 Then

MsgBox("Error")

End If

oAssy = oCResults.CompiledAssembly

'oExecInstance = oAssy.CreateInstance("MainClass")

'oType = oExecInstance.GetType

'oMethodInfo = oType.GetMethod("Eval")

'oRetObj = oMethodInfo.Invoke(oExecInstance, Nothing)

oType = oAssy.GetType("MainClass")

oRetObj = oType.InvokeMember("Eval", BindingFlags.InvokeMethod, Nothing, Nothing, Nothing)

MsgBox("method 2: " & CStr(oRetObj))

C#

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var exp = "3 + (2 + 3)/5";

var csCodeProvider = new CSharpCodeProvider();

var csParams = new CompilerParameters();

var source = "public class MainClass { public static object Eval() { return (#exp#); } }";

source = source.Replace("#exp#", exp);

csParams.CompilerOptions = "/t:library";

csParams.GenerateInMemory = true;

var csResults = csCodeProvider.

CompileAssemblyFromSource(csParams, source);

if (csResults.Errors.Count > 0)

{

Console.WriteLine(csResults.Errors[0].ToString());

return;

}

var ass = csResults.CompiledAssembly;

var type = ass.GetType("MainClass");

var result = type.InvokeMember("Eval", BindingFlags.InvokeMethod,

null, null, null);

Console.WriteLine("{0} = {1}", exp, result);

方法三： DataColumn.Expression & DataTable.Compute方法。

VB.NET

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Dim dt As DataTable = New DataTable

dt.Columns.Add("Val1", GetType(Integer))

dt.Columns.Add("Val2", GetType(Integer))

dt.Columns.Add("Result").Expression = String.Format("Val1 + Val2", Me.TextBox1.Text)

dt.Rows.Add(New Object() {3, 4})

MsgBox("method 3: " & dt.Rows(0)("Result"))

C#

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var exp = "3 + (2 + 3)/5";

DataTable dt = new DataTable();

dt.Columns.Add("Result").Expression = exp;

dt.Rows.Add(dt.NewRow());

var result = dt.Rows[0]["Result"];

Console.WriteLine("{0} = {1}", exp, result);