URL Validation using C#

Submitted by donbermoy on Wednesday, June 4, 2014 - 19:00.

Today, i will teach you how to create a program that will validate a URL inputted using C#. We know that a URL is the address of a specific Web site or file on the Internet. It cannot have spaces or certain other characters and uses forward slashes to denote different directories. Some examples of URLs are http://www.sourcecodester.com/, http://google.com/, etc. Now, let's start this validating a URL tutorial! 1. Let's start with creating a Windows Form Application in C# for this tutorial by following the following steps in Microsoft Visual Studio: Go to File, click New Project, and choose Windows Application and name your project validate url. 2. Next, add only one TextBox named Textbox1 for inputting a desired URL. Add also one button named Button1 to know if the inputted URL is valid or not. You must design your layout like this: design

3. Import a namespace named System.Text.RegularExpressions because we will use regular expression function to commnunicate with our input. We have imported System.Text.RegularExpressions because we will use a regular expression to match the pattern of the URL and the inputted URL in the textbox using IsMatch method.

    using System.Diagnostics;
    using System;
    using System.Windows.Forms;
    using System.Collections;
    using System.Drawing;
    using System.Data;
    using System.Collections.Generic;
     
    using System.Text.RegularExpressions;

4. Now put add this code for your code module. The Button1_click here will trigger to decide if the inputted URL in the textbox is valid or not. We will have to initialize pattern as String to hold a string value of http(s)?://([\w+?\.\w+])+([a-zA-Z0-9\~\!\@\#\$\%\^\&\*_\-\=\+\\\/\?\.\:\;\'\,]*)?. because this regular expression is the pattern for validating URL.

string pattern = default(string);
pattern = "http(s)?://([\\w+?\\.\\w+])+([a-zA-Z0-9\\~\\!\\@\\#\\$\\%\\^\\&\\*\\(\\)_\\-\\=\\+\\\\\\/\\?\\.\\:\\;\\\'\\,]*)?";

If the pattern will match the inputted URL in the textbox then it will display Valid URL!. Otherwise, it will prompt an Invalid URL!. Note: It will be a valid URL if it has htpp at the start not www.

if (Regex.IsMatch(TextBox1.Text, pattern))
{
        MessageBox.Show("Valid URL!");
}
else
{
        MessageBox.Show("Invalid URL!");
}

Full source code:

using System.Diagnostics;
using System;
using System.Windows.Forms;
using System.Collections;
using System.Drawing;
using Microsoft.VisualBasic;
using System.Data;
using System.Collections.Generic;
 
 
using System.Text.RegularExpressions;
 
namespace validate_url
{
        public partial class Form1
        {
                public Form1()
                {
                        InitializeComponent();
                        
                
                }
                
                public void Button1_Click(System.Object sender, System.EventArgs e)
                {
                        string pattern = default(string);
                        pattern = "http(s)?://([\\w+?\\.\\w+])+([a-zA-Z0-9\\~\\!\\@\\#\\$\\%\\^\\&\\*\\(\\)_\\-\\=\\+\\\\\\/\\?\\.\\:\\;\\\'\\,]*)?";
                        if (Regex.IsMatch(TextBox1.Text, pattern))
                        {
                                MessageBox.Show("Valid URL!");
                        }
                        else
                        {
                                MessageBox.Show("Invalid URL!");
                        }
                }
        }
}

Output: output

Best Regards, Engr. Lyndon Bermoy IT Instructor/System Developer/Android Developer/Freelance Programmer If you have some queries, feel free to contact the number or e-mail below. Mobile: 09488225971 Landline: 826-9296 E-mail:[email protected] Add and Follow me on Facebook: https://www.facebook.com/donzzsky Visit and like my page on Facebook at: https://www.facebook.com/BermzISware

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