![]() ![]() Hovering the mouse over the error icon will tell you what is wrong and how to fix it. You will find as you tab through the textboxes on the form, that you will get the error icon appearing unless you enter data in the right format. I have attached a sample project written in C#, which has a typical (though simplified) data entry form for some customer information. You could have one with a yellow icon rather than red, for when a field is valid but could be better. You can have as many error providers on a form as you wish, but I can only see a potential use for two. Private void txtTown_Validating(object sender, BlinkStyle tells whether the icon should blink. It's up to you how you do your validation, it could be as simple as text length constraints or as advanced as regular expressions matching. You can drop an ErrorProvider control on a form and then set its few properties in the Properties window. Now, in the Validating event of the textbox you need to put the code to test the contents for validity and optionally display the error icon. Put an ErrorProvider in your component tray too. ![]() Using it on a formĬreate yourself a form, with a textbox on it. ![]() While this may sound trivial, it's actually rather useful. After adding the items, double click the Current Date and Time to fire the click event handler of it. After that, click the ContextMenuStrip and add the following items into it. Drag a ContextMenuStrip, NotifyIcon, Button and it will look like this. When the user hovers their mouse over this icon a tooltip is instantly displayed with information about the invalid field. Open the Visual Basic and create a new Windows Form Application. What this component can do is display a little red icon beside any control which is invalid. It is a component rather than a control, so when you put it on your form it will sit in the component tray below. This little Gem is often left unnoticed, which is a funny thing considering it sits in the Windows Forms Controls Toolbox by default. So what we need is a method of unobtrusively showing that data is invalid, and presenting it in such a way that it is immediately obvious what is wrong and what to do about it. Also, we don't want all the validation done when the user presses the OK button, because they could then potentially be given a great big message with all the fields that are wrong. That would be an unnecessary interruption. The last thing we need is for a Message Box to pop up when we tab away from a field, telling us it's invalid. Drag a TextBox on the form, drag an ErrorProvider, drag a button then, double click the button, add following code: (this. Mt s thuc tính có trong ErrorProvider: Mt s phng thc ca ErrorProvider: 4. Thông thng khi iu khin trên Form li, ErrorProvider s cung cp mt biu tng thông báo li bên cánh iu khin ó. When we do get it wrong, however, we don't want to be bugged about it. ErrorProvider ErrorProvider giúp báo cho ngi dùng bit thông tin li ca iu khin trên Form. When a user is tabbing fast through a dialog entering data, they are sometimes going to get it wrong. Built-in validation doesn't go much further than an enforcable maximum length for textboxes, but there are some nice methods you can use to make validation a breeze. Data input validation in Windows Forms is essential. ![]()
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