vb.net 将文本框值转换为整数
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Convert Textbox value to Integer
提问by Nuke
I have the following Integer variables
我有以下整数变量
Dim sMaxAmount As Integer
Dim sMinAmount As Integer
I am trying to compare them with a TextBox field.
我正在尝试将它们与 TextBox 字段进行比较。
If (Convert.ToInt32(txtTransactionAmount) < sMinAmount And Convert.ToInt32(txtTransactionAmount) > sMaxAmount) Then
Although I am converting it to IntegerI get exception
虽然我正在将其转换为Integer我得到异常
Unable to cast object of type 'System.Web.UI.WebControls.TextBox' to type 'System.IConvertible'.
无法将“System.Web.UI.WebControls.TextBox”类型的对象转换为“System.IConvertible”类型。
What am I doing wrong?
我究竟做错了什么？
回答by Reagan Gallant
Typo: use txtTransactionAmount.Textinstead of txtTransactionAmount
错别字：使用txtTransactionAmount.Text代替txtTransactionAmount
If (Convert.ToInt32(txtTransactionAmount.Text) < sMinAmount AndAlso Convert.ToInt32(txtTransactionAmount.Text) > sMaxAmount)
回答by Blackwood
In addition to not using the Text property to get the string contained in the TextBox, there are two other problems with your code.
除了不使用 Text 属性来获取包含在 TextBox 中的字符串之外，您的代码还有另外两个问题。
- You are not validating the contents of the TextBox. If the user enters something that can't be converted to an integer, an exception will be thrown.
- The test you are doing doesn't make sense given the names of the variables. The value in the TextBox can't be bothless than the minimum and more than the maximum.
- 您没有验证 TextBox 的内容。如果用户输入的内容无法转换为整数，则会抛出异常。
- 鉴于变量的名称，您正在进行的测试没有意义。TextBox 中的值不能既小于最小值又大于最大值。
The following code uses Integer.TryParseto validate the contents of the TextBox and convert it to an Integer. It also checks that the value in greater than or equal to sMinAmountand less than or equal to sMaxAmount.
以下代码使用Integer.TryParse验证 TextBox 的内容并将其转换为 Integer。它还检查 中的值是否大于或等于sMinAmount且小于或等于sMaxAmount。
Dim amount As Integer
If Integer.TryParse(txtTransactionAmount.Text, amount) _
AndAlso amount >= sMinAmount AndAlso aamount <= sMaxAmount Then
'The Integer called "amount" now contains a value between sMinAmount and sMinAmount
End If
回答by Nover Yearfourth
Val(TextBox.Text)will convert the value of a TextBox to an Integer.
Val(TextBox.Text)将文本框的值转换为整数。
txtTotal.text= Val(txtPrice.text) * Val(txtQuantity.text)```
