CODEWITHSUNDEEP
c#winforms
Amrit Sharma
Amrit Sharma

Reputation: 1916

Value passed from one form to another form comes as null value

In my windows form application, I am trying to pass one of the value to another form but when the code reach to another form the value shows as null when I use breakpoints.

In Form1 I have one method that generates the OrderNumber and this order number is being used by Form1 itself as well as Form2. If I called Form1.OrderNumber from Form2 it will generate different order number. I want both Forms should have same order number.

So in Form1 I declare global variable as 

public string ord;

Now this "ord" variable gets its value from the following method in Form1.

 public string orderNumber()
            {
                string ord = "ORD" + DateTime.Now.Year + get_next_id();
               return ord;
}

where the get_next_id is another method which generates number according to the previous number in database.

Now in form1 itself when I use the "ord" variable value in following code the value comes as null.

InsertUser(maskedTextBox1.Text, comboBox1.Text, maskedTextBox2.Text, maskedTextBox3.Text, maskedTextBox4.Text, maskedTextBox5.Text,
                       maskedTextBox6.Text, maskedTextBox7.Text, maskedTextBox8.Text, maskedTextBox9.Text, listItems, DateTime.Now, maskedTextBox10.Text, ord, get_next_id());




   }

And same happens in form2 as well.

I am not sure where I am wrong. I posted this question before as well but didn't receive any useful answer. Any help please..

To pass the value of "ord" to form2 I am calling this code in form 1.

                        SaveAllListItems();
                        //this.Close();
                        PrintOrder m = new PrintOrder(ord);
                        m.Show();

where PrintOrder is form2

Upvotes: 0

Views: 1760

Answers (4)

DOT.NET
DOT.NET

Reputation: 101

public static string ord;

Simple used the static keyword. The Advantage of the Static keyword.

  1. Share the memory in whole application.
  2. If any user update the value this value get a updated value like that, One user update the value int x=18 , another user get a value update.
  3. static keyword used on compile time binding.

Upvotes: 1

dparpyani
dparpyani

Reputation: 2493

That is because in the following code, you are declaring a new local variable called ord.

public string orderNumber()
{
    string ord = "ORD" + DateTime.Now.Year + get_next_id();
    return ord;
}

To make it work, change the above function to:

public void OrderNumber()
{
    ord = "ORD" + DateTime.Now.Year + get_next_id();
}

OrderNumber does not need to return a value since you will be using ord anyways.

OrderNumber needs to be called before you try to retrieve the value for ord. When you initially declare ord, the value is null. Calling OrderNumber will change it's value from null to whatever you like.

Upvotes: 0

Habib
Habib

Reputation: 223257

Now this "ord" variable gets its value from the following method in Form1.,

Its not, you are defining a local variable again in the method, you r not setting the class level variable in your method. 

public string orderNumber()
{
   string ord = "ORD" + DateTime.Now.Year + get_next_id();
   ^^^^^^^^^^
   //indicating a local variable, not class level
   return ord;
}

Should be:

public string orderNumber()
{
   ord = "ORD" + DateTime.Now.Year + get_next_id();
   return ord;
}

Upvotes: 2

Benny
Benny

Reputation: 317

instead of

string ord = "ORD" + DateTime.Now.Year + get_next_id();

use

ord = "ORD" + DateTime.Now.Year + get_next_id();

Upvotes: 0

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