不区分大小写

Question

If TextBox2.Text = "a" AndAlso TextBox21.Text = "a" Then
        'MessageBox.Show("A")
        totCorrect = totCorrect + corAns
    ElseIf TextBox2.Text = "b" AndAlso TextBox21.Text = "b" Then
        'MessageBox.Show("B")
        totCorrect = totCorrect + corAns
    ElseIf TextBox2.Text = "c" AndAlso TextBox21.Text = "c" Then
        'MessageBox.Show("C")
        totCorrect = totCorrect + corAns
    ElseIf TextBox2.Text = "d" AndAlso TextBox21.Text = "d" Then
        'MessageBox.Show("D")
        totCorrect = totCorrect + corAns
    Else
        totWrong = totWrong + wrgAns
        Label13.Visible = True
    End If

我试图让用户输入不敏感的字母a，b，c，d。试图使用UCase，但它不起作用（不确定我是否使用它错了）。我在Visual Studio 2012中使用VB。任何参考都会很棒。

Answer 1

您可以使用String.Compare方法：String.Compare (String strA, String strB, Boolean ignoreCase)

与ignoreCase传递true参数将执行不区分大小写的比较。

If String.Compare(TextBox2.Text, "a", true) = 0 AndAlso String.Compare(TextBox21.Text, "a", true) = 0 Then
        'MessageBox.Show("A")
        totCorrect = totCorrect + corAns
    ElseIf String.Compare(TextBox2.Text, "b", true) = 0 AndAlso String.Compare(TextBox21.Text, "b", true) = 0 Then
        'MessageBox.Show("B")
        totCorrect = totCorrect + corAns
    ElseIf String.Compare(TextBox2.Text, "c", true) = 0 AndAlso String.Compare(TextBox21.Text, "c", true) = 0 Then
        'MessageBox.Show("C")
        totCorrect = totCorrect + corAns
    ElseIf String.Compare(TextBox2.Text, "d", true) = 0 AndAlso String.Compare(TextBox21.Text, "d", true) = 0 Then
        'MessageBox.Show("D")
        totCorrect = totCorrect + corAns
    Else
        totWrong = totWrong + wrgAns
        Label13.Visible = True
    End If

另一个想法是使用ToUpper或ToLower来大写或小写输入。

If TextBox2.Text.ToUpper() = "A" AndAlso TextBox21.Text.ToUpper() = "A" Then
            'MessageBox.Show("A")
            totCorrect = totCorrect + corAns
        ElseIf TextBox2.Text.ToUpper() = "B" AndAlso TextBox21.Text.ToUpper() = "B" Then
            'MessageBox.Show("B")
            totCorrect = totCorrect + corAns
        ElseIf TextBox2.Text.ToUpper() = "C" AndAlso TextBox21.Text.ToUpper() = "C" Then
            'MessageBox.Show("C")
            totCorrect = totCorrect + corAns
        ElseIf TextBox2.Text.ToUpper() = "D" AndAlso TextBox21.Text.ToUpper() = "D" Then
            'MessageBox.Show("D")
            totCorrect = totCorrect + corAns
        Else
            totWrong = totWrong + wrgAns
            Label13.Visible = True
        End If

Answer 2

根据VB.NET中的MSDN，只需在文件中添加1行代码即可使用Option Compare Statement：

Option Compare Text

如果将上面的行添加到代码的开头，则告诉CLR从默认（Option Compare Binary）切换到不区分大小写的比较作为=运算符的新默认值。

我不知道是否有任何C＃替代品。