Question

 If txtFirstName.Text <> "First Name" & txtLastName.Text <> "Last Name" & txtUsername.Text <> "Username" & txtPassword.Text = txtConfirmPassword.Text & txtAge.Text <> "Age ( Years )" & txtHeight.Text <> "Height ( Cm )" & txtWeight.Text <> "Weight ( Kg )" & txtAroundWrist.Text <> "Around Wrist ( Cm )" & ComboBox1.Text <> "" Then
     'do something
End If

我总是在vb 2010的第一行（ Conversion from string to type boolean is not valid ）中收到 if txtFirstName.Text... 错误。

你有什么建议？

Answer 1

您需要使用And运算符而不是＆amp;操作

Answer 2

VB.NET中的

&用于字符串连接。

您可能来自C / C ++ / C＃world，其中&表示And。您可以在VB.NET中使用And，或者更好地使用AndAlso运算符（相当于C＃中的&&）。像这样：

If txtFirstName.Text <> "First Name" AndAlso
   txtLastName.Text <> "Last Name" AndAlso
   txtUsername.Text <> "Username" AndAlso
   txtPassword.Text = txtConfirmPassword.Text AndAlso
   txtAge.Text <> "Age ( Years )" AndAlso
   txtHeight.Text <> "Height ( Cm )" AndAlso
   txtWeight.Text <> "Weight ( Kg )" AndAlso
   txtAroundWrist.Text <> "Around Wrist ( Cm )" AndAlso
   ComboBox1.Text <> "" Then
 'do something
End If

通常，And用作按位运算符，而AndAlso是逻辑运算符。另见：

Which is better for performance? And vs AndAlso @ StackOverflow

没有从字符串转换为类型布尔值，但我得到错误

2 个答案: