VB.NET入门（六）:过程与函数

　　前面学了对数据的组织，现在再来学对语句的组织。模块化程序的设计思想就是分而治之，这就有了函数，VB.NET中还有一种没有返回值的函数：过程。

　　1,使用过程4-1.vb可以改写为

'7-1.vb
Class SimpleCnl
    Public Shared Sub Main()
        Dim username As String = String.empty, password As String = String.empty
        Dim isAuthenticated As Boolean = False

        Input("输入用户名:", username)
        Input("输入密码:", password)

        ValidateUserLogin(username, password, isAuthenticated)
        If isAuthenticated Then
            System.Console.WriteLine("登陆成功")
        Else
            System.Console.WriteLine("用户名或密码有误")
        End If
    End Sub
    Public Shared Sub Input(ByVal inputTip As String, ByRef var As String)
        System.console.write(inputTip)
        var = System.console.ReadLine()
    End Sub
    Public Shared Sub ValidateUserLogin(ByVal username As String, ByVal password As String, ByRef isAuthenticated As Boolean)
        If username = "admin" And password = "123456" Then
            isAuthenticated = True
        Else
            isAuthenticated = False
        End If
    End Sub
End Class

2.使用函数则可以改为

'7-2.vb
Class SimpleCnl
    Public Shared Sub Main()
        Dim username, password As String

        username = Input("输入用户名:")
        password = Input("输入密码:")

        If ValidateUserLogin(username, password) Then
            System.Console.WriteLine("登陆成功")
        Else
            System.Console.WriteLine("用户名或密码有误")
        End If
    End Sub
    Public Shared Function Input(ByVal inputTip As String) As String
        System.Console.Write(inputTip)
        Input = System.Console.ReadLine()
    End Function
    Public Shared Function ValidateUserLogin(ByVal username As String, ByVal password As String) As Boolean
        If username = "admin" And password = "123456" Then
            Return True
        Else
            Return False
        End If
    End Function
End Class

3.不管是使用函数，还是过程，定义方式，调用方式，参数的传递方式，都是我们要搞清楚的，VB中定义可变长参数这篇文章，可以给我们一些参考。函数和过程的使用，用多了，我们自然就能掌握使用技巧了。