How to C# String Null

using System;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
 public partial class Form1 : Form
 {
  public Form1()
  {
   InitializeComponent();
  }

  private void button1_Click(object sender, EventArgs e)
  {
   string str =null;

   if (str == null)
   {
    MessageBox.Show("String is null");
   }
   else
   {
    MessageBox.Show("String is not null");
   }

   str = "test";

   if (string.IsNullOrEmpty(str))
   {
    MessageBox.Show("String is empty or null");
   }
   else
   {
    MessageBox.Show("String is not empty or null");
   }

  }
 }
}

How to use C# string Copy

using System;
using System.Windows.Forms;

namespace WindowsApplication1
{
 public partial class Form1 : Form
 {
  public Form1()
  {
   InitializeComponent();
  }

  private void button1_Click(object sender, EventArgs e)
  {
   string str1 = null;
   string str2 = null;

   str1 = "CSharp Copy() test";
   str2 = string.Copy(str1);

   MessageBox.Show(str2); 
  }
 }
}

When you run this C# source code you will get same content of str1 in str2 

How to use C# string Equals

using System;
using System.Windows.Forms;

namespace WindowsApplication1
{
 public partial class Form1 : Form
 {
  public Form1()
  {
   InitializeComponent();
  }

  private void button1_Click(object sender, EventArgs e)
  {
   string str1 = "Equals";
   string str2 = "Equals";

   if (string.Equals(str1, str2))
   {
    MessageBox.Show("Strings are Equal() ");
   }
   else
   {
    MessageBox.Show("Strings are not Equal() ");
   }
  }
 }
}

When you run this C# program you will get message "Strings are Equal() " 

How to use C# string Insert

using System;
using System.Windows.Forms;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string str = "This is CSharp Test";
            string insStr = "Insert ";
            string strRes = str.Insert(15, insStr);
            MessageBox.Show(strRes); 
        }
    }
}

When you execute this C# program you will get the message box 

showing "This is CSharp Insert Test" 

How to use C# string Contains

using System;
using System.Windows.Forms;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string str = null;
            str = "CSharp TOP 10 BOOKS";
            if (str.Contains("TOP") == true)
            {
                MessageBox.Show("The string Contains() 'TOP' ");
            }
            else
            {
                MessageBox.Show("The String does not Contains() 'TOP'");
            } 
        }
    }
}

When you run the C# program you will get the MessageBox with message 

"The string Contains() 'TOP' " 

How to use C# string Compare

using System;
using System.Windows.Forms;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string str1 = null;
            string str2 = null;

            str1 = "csharp";
            str2 = "CSharp";

            int result = 0;

            result = string.Compare(str1, str2);
            MessageBox.Show(result.ToString());

            result = string.Compare(str1, str2, true);
            MessageBox.Show(result.ToString());
        }
    }
}

When you run this C# program first u will get -1 in message box and then 0

How to use C# string IndexOf

using System;
using System.Windows.Forms;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string str = null;
            str = "CSharp TOP 10 BOOKS";
            MessageBox.Show(str.IndexOf("BOOKS").ToString()); 
        }
    }
}

When you execute this C# program you will get the number 14 in the message box. 

That means the substring "BOOKS" occurred and start in the position 14. 

How to validate a string in C#

using System;
using System.Windows.Forms;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            bool isNumeric;
            int i;
            string str = "100";
            isNumeric = int.TryParse(str, out i);
            MessageBox.Show("The value of i is " + i);
        }
    }
}

How to use C# string Format

using System;
using System.Windows.Forms;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            double dNum = 0;
            dNum = 32.123456789;
            MessageBox.Show("Formated String " + string.Format("{0:n4}", dNum)); 
        }
    }
}

When you run this C# source code you will get "Formated String 32.1234" 

How to use C# string Length

using System;
using System.Windows.Forms;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string str = null;
            str = "This is a Test";
            MessageBox.Show(str.Length.ToString()); 
        }
    }
}

When you execute this C# source code you will get 14 in the messagebox. 

How to use C# string Clone

using System;
using System.Windows.Forms;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            {
                string str = "Clone() Test";
                string clonedString = null;
                clonedString = (String)str.Clone();
                MessageBox.Show (clonedString);
            }
        }
    }
}

When you run this C# program you will get the same content of the 

first string "Clone() Test" 

How to use C# string Concat

using System;
using System.Windows.Forms;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string str1 = null;
            string str2 = null;

            str1 = "Concat() ";
            str2 = "Test";
            MessageBox.Show(string.Concat(str1, str2)); 
        }
    }
}

When you run this C# source code you will get "Concat() Test " in message box. 

How to use C# string Split

using System; using System.Windows.Forms; namespace WindowsApplication1 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { string str = null; string[] strArr = null; int count = 0; str = "CSharp split test"; char[] splitchar = { ' ' }; strArr = str.Split(splitchar); for (count = 0; count <= strArr.Length - 1; count++) { MessageBox.Show(strArr[count]); } } } }