Today, I will teach you how to validate a Registration Form using Regular Expressions in C#. Regular Expression contains the formated rules and check lengths to validate the inputs of a certain texbox. This method is very useful because it will help you restrict each fields in the form.
Let’s get started:
Open Microsoft Visual Studio 2008 and create new Windows Form Application for C#. Then, do the following design of a Form as follows.
Go to the Solution Explorer, click the “View Code” to make the code editor appear.
In the code editor, import the regural expression library above the namespace.
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using System.Text.RegularExpressions; |
After that, create the following method inside the class. These methods are use to format the specific fields using the correct patern.
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//Method for validating email address private static Regex Email_Address() { string Email_Pattern = @"^(?!\.)(""([^""\r\\]|\\[""\r\\])*""|" + @"([-a-z0-9!#$%&'*+/=?^_`{|}~]|(?<!\.)\.)*)(?<!\.)" + @"@[a-z0-9][\w\.-]*[a-z0-9]\.[a-z][a-z\.]*[a-z]$"; return new Regex(Email_Pattern, RegexOptions.IgnoreCase); } //Method for string only validation private static Regex StringOnly() { string StringAndNumber_Pattern = "^[a-zA-Z]"; return new Regex(StringAndNumber_Pattern, RegexOptions.IgnoreCase); } //Method for numbers only validation private static Regex NumbersOnly() { string StringAndNumber_Pattern = "^[0-9]*$"; return new Regex(StringAndNumber_Pattern, RegexOptions.IgnoreCase); } //Method for validating password private static Regex ValidPassword() { string Password_Pattern = "(?!^[0-9]*$)(?!^[a-zA-Z]*$)^([a-zA-Z0-9]{8,15})$"; return new Regex(Password_Pattern, RegexOptions.IgnoreCase); } |
Go back to the design view, double click the button and do the following code for the validation of the registration form.
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//it validate all textboxes when the button clicked private void button1_Click(object sender, EventArgs e) { //for firstname if (Valid_Fname.IsMatch(txtfName.Text) != true) { MessageBox.Show("Firstname accepts only alphabetical characters", "Invalid", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); txtfName.Focus(); return; } //for Lastname if (Valid_Lname.IsMatch(txtLname.Text) != true) { MessageBox.Show("Lastname accepts only alphabetical characters", "Invalid", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); txtLname.Focus(); return; } //for Address if (txtAdd.Text == "") { MessageBox.Show("Address cannot be empty!", "Invalid", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); txtAdd.Focus(); return; } //for Contacts if (Valid_Contact.IsMatch(txtContact.Text) != true) { MessageBox.Show("Contact accept numbers only.", "Invalid", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); txtContact.Focus(); return; } //for username if (txtuname.Text == "") { MessageBox.Show("Username cannot be empty!", "Invalid", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); txtuname.Focus(); return; } //for password if (Valid_Password.IsMatch(txtPass.Text) != true) { MessageBox.Show("Password must be atleast 8 to 15 characters. It contains atleast one Upper case and numbers.", "Invalid", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); txtPass.Focus(); return; } //for Email Address if (Valid_Email.IsMatch(txtEmail.Text) != true) { MessageBox.Show("Invalid Email Address!","Invalid",MessageBoxButtons.OK ,MessageBoxIcon.Exclamation ); txtEmail.Focus(); return; } //success message MessageBox.Show("You are now successfully registered."); //hidding all object in the form foreach(Control txt in this.Controls) { if (txt is Control) { txt.Visible = false; } } } |
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