VB.NET：选项比较文本和泛型 [英] VB.NET: Option Compare Text and Generics

问题描述

我无法弄清楚为什么这不起作用。

I can't figure out why this doesn't work.

Option Compare Text
..
Private Shared Function AreEqual(Of T)(ByVal a As T, ByVal b As T) As Boolean
    If a Is Nothing AndAlso b Is Nothing Then
        Return True
    ElseIf a IsNot Nothing AndAlso b IsNot Nothing AndAlso a.Equals(b)  Then
        Return True
    Else
        Return False
    End If
End Function

假设我打电话：

Suppose I call:

AreEqual(Of String)("Hello", "HELLO")

我希望上面的调用返回TRUE，因为Option Compare Text是组。 MSDN说（ http://msdn.microsoft.com/en-us/library/ 8t3khw5f（VS.80）.aspx [ ^ ]：

I would expect the call above to return TRUE because the "Option Compare Text" is set. MSDN says (http://msdn.microsoft.com/en-us/library/8t3khw5f(VS.80).aspx[^]:

Option Compare Statement
Declares the default comparison method to use when comparing string data.

Copy
Option Compare { Binary | Text }
Parts
--------------------------------------------------------------------------------
Text
Optional. Results in string comparisons based on a case-insensitive text sort order determined by your system's locale.

然而，它返回假。有任何想法吗？ （也尝试在我的AreEquals方法中使用调试器中的a = b，仍然说它是假的）

Yet, it returns FALSE. Any ideas? (also tried to use "a=b" in the debugger in my "AreEquals" method, still says it's FALSE)

推荐答案

使用选项与string.equals比较不会工作，但将比较方法更改为下面的示例将产生您之后的结果



使用选项比较示例

using option compare with string.equals wont work, but changing the compare method to the example below will produce the results that you are after

using option compare example

option compare text

Public Class Form2
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim a As String = "Hi"
        Dim b As String = "HI"
        If a = b Then
            MessageBox.Show("TRUE")
        Else
            MessageBox.Show("FALSE")
        End If
    End Sub

End Clas

请注意使用选项比较在它自己的默认为二进制和上面的例子不会工作，因为它的排序顺序不同于文本



，如您提供的msdn文章所示，备注文章的部分文本比较它不区分大小写，但二进制比较是例如A< B< a< b

Please note that using option compare on its own defaults to binary and the above example wont work as its sort order is different to text

as shown by the msdn article that you have provided, the remarks section of the article with Text compare it isn't case sensitive, but binary compare is e.g. A < B < a < b

Dave答案的进一步证明



MSDN String.equals

Further proof to Dave's answer

MSDN String.equals

Remarks

This method performs an ordinal (case-sensitive and culture-insensitive) comparison

因为a不等于b。



你需要设置一个上限和比较。

Because a does not equal b.

You would need to set a to caps and compare.

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