Stopping an event from executing code in windows forms

David Oest

Im in my first C# and GUI class and im wondering how i stop an event from executing. In my case i have a button and a textbox, if the button is clicked when there is invalid input in the textbox the button event should stop executing.

3 Replies

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Naimish Makwana3y ago

Accepted answer

Hello David,

You can use the return statement to stop the execution of the event handler method.

Example:

private void Button_Click(object sender, EventArgs e)
{
    string name = txtName.Text;

    if (!Validate(name))
    {
        MessageBox.Show("Invalid name!");
        return; //From here your execution stop
    }

    // Continue processing...
}

Thanks

Naimish Makwana

David Oest3y ago
Thank you so much for the simple and fast answer.
Vishal Joshi3y ago
Hello

Please try the below way to complete the requirement.

In properties choose “Events” and under focus double-click on “validating”. after select validation method you need to write method like below code sample:
```
private void textBoxName_Validating(object sender, CancelEventArgs e)   
{  
    if (string.IsNullOrWhiteSpace(textBoxName.Text))   
    {  
        e.Cancel = true;  
        textBoxName.Focus();  
        errorProviderApp.SetError(textBoxName, "Name should not be left blank!");  
    } else   
    {  
        e.Cancel = false;  
        errorProviderApp.SetError(textBoxName, "");  
    }  
} 
```
Please check below article for more details.

https://www.c-sharpcorner.com/blogs/how-to-use-validation-in-windows-form-application

Thanks