VB.Net - 邏輯/位運(yùn)算符

下表顯示了VB.Net支持的所有邏輯運(yùn)算符。 假設(shè)變量A為布爾值True，變量B為布爾值False，則：

短路運(yùn)算：一種邏輯運(yùn)算規(guī)則，我們知道與邏輯運(yùn)算的算法是只要有一個(gè)假就能判定為假，或運(yùn)算符只要有一個(gè)為真就能判定為真。短路運(yùn)算的算法就是建立在這一基礎(chǔ)上。
以與運(yùn)算為例：當(dāng)兩個(gè)表達(dá)式前一個(gè)表達(dá)式判定為假時(shí)，第二個(gè)表達(dá)式不會(huì)進(jìn)行計(jì)算，直接返回假
這樣的計(jì)算被稱為短路運(yùn)算，它可以提高邏輯運(yùn)算的速度（畢竟有一部分情況只需要計(jì)算第一個(gè)表達(dá)式即可）
但是短路運(yùn)算也有其缺點(diǎn)，就是不夠嚴(yán)謹(jǐn)，特別是部分情況下還是需要運(yùn)算第二個(gè)表達(dá)式。所以很多語言都有提供短路版本和非短路版本的與運(yùn)算和或運(yùn)算。

嘗試以下示例來了解VB.Net中提供的所有邏輯/按位運(yùn)算符：

Module logicalOp

    Sub Main()
        Dim a As Boolean = True
        Dim b As Boolean = True
        Dim c As Integer = 5
        Dim d As Integer = 20
        'logical And, Or and Xor Checking
        If (a And b) Then
            Console.WriteLine("Line 1 - Condition is true")
        End If
        If (a Or b) Then
            Console.WriteLine("Line 2 - Condition is true")
        End If
        If (a Xor b) Then
            Console.WriteLine("Line 3 - Condition is true")
        End If
        'bitwise And, Or and Xor Checking
        If (c And d) Then
            Console.WriteLine("Line 4 - Condition is true")
        End If
        If (c Or d) Then
            Console.WriteLine("Line 5 - Condition is true")
        End If
        If (c Or d) Then
            Console.WriteLine("Line 6 - Condition is true")
        End If
        'Only logical operators
        If (a AndAlso b) Then
            Console.WriteLine("Line 7 - Condition is true")
        End If
        If (a OrElse b) Then
            Console.WriteLine("Line 8 - Condition is true")
        End If

        ' lets change the value of  a and b 
        a = False
        b = True
        If (a And b) Then
            Console.WriteLine("Line 9 - Condition is true")
        Else
            Console.WriteLine("Line 9 - Condition is not true")
        End If
        If (Not (a And b)) Then
            Console.WriteLine("Line 10 - Condition is true")
        End If
        Console.ReadLine()
    End Sub
End Module

當(dāng)上述代碼被編譯和執(zhí)行時(shí)，它產(chǎn)生以下結(jié)果：

Line 1 - Condition is true
Line 2 - Condition is true
Line 4 - Condition is true
Line 5 - Condition is true
Line 6 - Condition is true
Line 7 - Condition is true
Line 8 - Condition is true
Line 9 - Condition is not true
Line 10 - Condition is true