They make use of a pattern matching system to match the input with a certain pattern of data.
Figure 1 - These objects will determine if all our data is valid or not. Clear() 'Clear Text Box Name Valid = False 'Boolean = False Else Name Valid = True 'Everything Fine End If End Sub Easy one to start with. Focus() 'Set Focus To Text Box End If End Sub Private Sub txt Email_Lost Focus(sender As Object, e As System. Lost Focus Validate Email() 'Check Email Validity End Sub The expression may look horrible to the layman's eye, but look closer. To check if the user has entered an email that actually exists, you will have to find a different way such as to send a of some sorts.
That may seem like Captain Obvious speaking, but you'll be amazed at some of the data that gets entered into a name field. I then created an If statement to determine how the input data was formatted and whether or not the data is only alphabetic.
Sometimes people are just trying to be funny, or they are literally trying to break your program. If the data is indeed only alphabetic letters (no symbols, no numbers or any other punctuation characters) the test succeeds and stores True inside the Name Valid variable. This is because it becomes more legible than just a normal set of numbers.
You could say that a program's testers are supposed to do this; yes, they should - nobody else should. If not, if there is even just one unallowed character that is not supposed to be there, the Match method will return False. Instead of you having to loop through each character to determine what that character is, you simply need the correct Regular Expression pattern. Clear() Surname Valid = False Else Surname Valid = True End If End Sub It is basically the exact same code for the Name box, but I just included the capability to comprehend a space character as well. People expect to enter a phone number in a format similar to this: ###-###-####.
The "/" character is a logical date separator, and will appear to the user as the date separator appropriate to the application's current culture. If users do not want to enter the optional characters, they can either enter spaces or place the mouse pointer directly at the position in the mask represented by the first 0. Mask yazan yere 5 sıfır yazıldığı en fazla 5 sayı girilebilir. Phone number: Telefon numarası girişlerinde kullanabiliriz. Bunu sadece sayının kullanılacağı zamanlarda kullanıcının sayı dışında başka bir karakter girmesini engelleyebiliriz. Masked Text Box のText Mask Formatプロパティを変更することで、どのように文字列を取得するかを 変更できる。 たとえば、Masked Text Box A に"____年__月__日" というマスクを設定して、テキストボックスに"2012年02月20日"と入力された場合 フォーマット文字列を除いて取得： Masked Text Box A. Exclude Prompt And Literals str Input = Masked Text Box str Input："20120220" フォーマット文字列を含めて取得： Masked Text Box A. Well, sometimes a good structured and thought out If statement can suffice, but it can become quite long and cumbersome in the future. By using Regular Expressions this way, you can reduce the chances of getting errors at erratic times. This sub checks the email's format and if it thinks that it matches, it returns True and vice versa.