函数重载未按预期工作

问题描述

我有一个类，它有两个具有相同名称和不同类型参数的函数，如下所述：

I have a class having two functions with same name and different type of arguments as described below:

  Public Class functionOverload
'<--- first function starts here
        Public Function Test(ByVal x As Int16, ByVal y As Int16) As Double
            Return x * y
        End Function
'<--- first function Ends here

'<--- Second function starts here
        Public Function Test(ByVal x As Int32, ByVal y As Int32) As Integer
            Return x + y
        End Function
'<--- Second function ends here
    End Class

在我的主模块中，我创建了一个对象这个类并使用不同的参数调用函数：

In my main module i had created an object of this class and call the function using different arguments:

Dim obj As New functionOverload
 MsgBox(obj.Test(10, 20)) '<--- will call second function as both the parameters are of type int32
 Dim i, j As Int16
 i = 10
 j = 20
 MsgBox(obj.Test(i, j)) '<--- will call First function as both the parameters are of type int16

到目前为止工作正常。我尝试了更多如下：

Up to this works fine as excepted. and i had tried even more as follows:

MsgBox(obj.Test(i, 10)) '<--- will call second function even though their is no matching function
MsgBox(obj.Test(20, j)) '<--- will call second function even though their is no matching function

问题：为什么会这样？函数超载的规则是不同的vb.net

Question : why this is happening? Is the rules for function over loading is different in vb.net

推荐答案

MsgBox(obj.Test(i, 10)) '<--- will call second function even though their is no matching function
MsgBox(obj.Test(20, j)) '<--- will call second function even though their is no matching function

它的工作原理是因为将 Int16 上传到 Int32 是安全的，所以编译器这样做，然后你有一个调用，你传递两个 Int32 s（这是第二个函数）为 10 和 20 将被解释为 Int32 s，除非另有说明。



希望这有帮助，

Fredrik

It works because upcasting an Int16 to an Int32 is safe, so the compiler that do that, and then you have a call where you pass two Int32s (which is the second function) as the 10 and 20 will be interpreted as Int32s unless specified.

Hope this helps,
Fredrik

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