如何强制用户从文本框中输入仅包含无整数的字符的字符串? [英] How can I force a user to enter a string with characters only with no integer from a text box?

问题描述

我有一个文本框，该文本框仅包含完整的字符串，例如人名.如果用户输入(paul123)或(1234)之类的内容，则应该获得无效的输入.

I have textbox that takes only a fully characters string for example person name. If the user enter something like (paul123) or (1234), it should get an invalid input.

我尝试:

Integer.parse(me.nametextbox.text)
msgbox("invalid")
me.nametextbox.lostfocus

当用户首先键入一个整数时，它起作用了，它给出了消息，但是用户首先键入了它经历的一个字符-那不是我想要的.

It works when the user types an integer first, it gives the message but user types a character first it goes through - that is not what I want.

有什么主意吗?

最好的问候

推荐答案

测试有可能被解释为十六进制数.与其使用TryParse来确定它是否是一个好数字，不如使用正则表达式.

It''s possible that the test is being interpreted as a hexadecimal number. Instead of using TryParse to determine if it''s a good number, use a regular expression instead.

尝试一下 私有Sub me.nametextbox_KeyPress(按对象发送ByVal发送者，按System.Windows.Forms.KeyPressEventArgs接收ByVal e)处理me.nametextbox.KeyPress 如果(不是(Char.IsDigit(e.KeyChar)或Char.IsControl(e.KeyChar))) e.Handled = True:MsgBox(请输入有效的字符."，MsgBoxStyle.Information，消息") 万一 结束Sub

Try This Private Sub me.nametextbox_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles me.nametextbox.KeyPress If (Not (Char.IsDigit(e.KeyChar) Or Char.IsControl(e.KeyChar))) Then e.Handled = True : MsgBox("Please enter valid Char.", MsgBoxStyle.Information, "Message") End If End Sub

"[0-9]"

该正则表达式将在字符串中找到任何数字.因此，您要做的是检查字符串以查看该正则表达式是否返回任何结果.如果是这样，则表示该字符串包含一个数字.我不想让您觉得这太容易(因为我希望您能学习，并且仅在遇到无法解决的问题时才来找我们)，所以我将不去理会如何使用正则表达式由您决定.这应该使您入门: .Net正则表达式.

或者，您可以遍历字符串中的每个字符并检查它是否为数字.同样，这应该非常简单，所以我将其留给您练习.

That regular expression will find any digit in a string. So, what you want to do is check the string to see if that regular expression returns any results. If it does, that means the string contains a digit. I don''t want to make it too easy for you (as I expect you to do the learning and only come to us when you are running into a problem you can''t seem to solve), so I will leave figuring out how to use the regular expression up to you. This should get you started: .Net Regular Expressions.

Alternatively, you could just loop through each character in the string and check if it is a digit. Again, that should be extremely simple, so I''ll leave that as an exercise for you to do.

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