how to pass value from form1 to form2 in c# windows application

why didn't you google it??

it's the basic question, i think when you are able to post here then you must be able to search it on google before posting here..
Few links here..

Passing Data Between Forms[^]
Pass value between forms using events[^]
Pass value between forms using events[^]

As the question turned out to be very popular, and my previous answers often were not well understood, probably were not clear enough, I decided to write a Tips/Trick article complete with detailed code samples and explanations: Many Questions Answered at Once — Collaboration between Windows Forms or WPF Windows.

—SA

Hi,

There are two ways:
1. Use the constructor to take the value as input.
2. Use the property.

Take a static class Property.

class Class1
   {
      static string name;
     static  string add;

       public static string PName
       {
           get
           {
               return name;
           }
           set
           {
               name = value;
           }
       }

       public static string PAddress
       {
           get
           {
               return add;
           }
           set
           {
               add = value;
           }
       }
   }

Now on Form1 take two textbox and two button
and write this code on .cs file.

private void button2_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (textBox1.Text == "" || textBox2.Text == "")
            {
                MessageBox.Show("Please don`t leave any textbox empty.");
            }

            else
            {

                 Class1.PName = textBox1.Text;
                 Class1.PAddress = textBox2.Text;

                Form2 f2 = new Form2();
                f2.Show();

            }
        }

Now take another form (Form2)
Take two label and one button on it.
Now write this code on .cs file to received value from Form1 and display it.

private void button1_Click(object sender, EventArgs e)
{
    this.Close();
}

private void Form2_Load(object sender, EventArgs e)
{

    label1.Text = Class1.PName;
    label2.Text = Class1.PAddress;
}

check
Passing Data Between Forms[^]

passing-value-from-form2-to-form1[^]

This is the popular question about form collaboration. The most robust solution is implementation of an appropriate interface in form class and passing the interface reference instead of reference to a "whole instance" of a Form. Please see my past solution for more detail: How to copy all the items between listboxes in two forms[^].

Please also see other solutions in this discussion. If the application is simple enough, the solution could be as simple as declaring of some internal property in one form and passing a reference to the instance of one form to the instance of another form. For more complex projects, such violation of strictly encapsulated style and loose coupling could add up the the accidental complexity of the code and invite mistakes, so the well-encapsulated solution would be preferable.

Please see also:
http://en.wikipedia.org/wiki/Accidental_complexity[^],
http://en.wikipedia.org/wiki/Loose_coupling[^].

—SA