WinForm development of the form pass value

Data transfer between WinForm forms is an essential technology for development, and several typical methods of passing values are described below

1, the value of the constructor, but this method is one-way (recommended)

On the code, first pass the value

Private void button2_click (object  sender, EventArgs e)        {            new Form3 (" the value to pass. " );            FR3. ShowDialog ();        }

The value is, yes, you need to overload a Form3 constructor, and then show the value you got.

 Public FORM3 (string  Canshu)        {            InitializeComponent ();             = Canshu;        }

, it's so simple

2, static variable transfer value (not recommended)

Static variables can be declared where you need them, such as a single class, or a form, as we declare here in Form2

 Public Static string xvalue;

Private void button2_click (object  sender, EventArgs e)        {            " the value to be passed Xvalue ";             New Form3 ();            FR3. ShowDialog ();        }

Assign the value first, then the value in the FORM3

 Public Form3 ()        {            InitializeComponent ();             = Form2.xvalue; // Form2 is actually a class, take the static value directly, if the static variable Xvalue defined in other classes, will be Form2 to            replace it        }

On

3. Pass value by common attribute

First create a common property in the form you want to open, and then assign a value in the call window. For example, the following Form2 start Form3, that is, to Form3 yvalue value

(1) Defining common attributes in FORM3

 Public string yvalue {            get             {                return  Label1. Text.tostring ();            }             Set              {                = value;            }        }

(2) Start the FORM3 in Form2 and pass the value

Private void button2_click (object  sender, EventArgs e)        {                       new  Form3 ();             " the value to pass. " ;            FR3. ShowDialog ();        }

4. Pass the value through the Owner property

(1) Declare a public variable in caller Form2 and assign a value to set the owner of the Form3 that needs to be started

 Public string Xvalue;         Private void button2_click (object  sender, EventArgs e)        {            "Form2 value to pass" ";             New Form3 ();              This ;            FR3. ShowDialog ();        }

(2) Starting the form FORM3 value

Private void Form3_load (object  sender, EventArgs e)        {            = (Form2)this. Owner;             = fr2.xvalue;        }

This method actually passes Form2 to FORM3, so FORM3 can take all the public variables and properties of Form2.

5. Transfer value (recommended)

Delegate event passing value is mainly used in the subform to the parent form on the value, that is, the above Form3 to Form2 value

(1) Declare the Commission event in FORM3 first

 Public Delegate void Puthandler (string  text);          Public Puthandler Puttexthandler; // Delegate Object        Private void button1_click (object  sender, EventArgs e)        {            ifnull  )            {                Puttexthandler (textBox1.Text.ToString ());            }        }

(2) Binding delegate events in Form2

 Public void getValue (string  strv)          {             this. TextBox1.Text = strv;         }                 Private void button1_click (object  sender, EventArgs e)        {            new  FORM3 ();             = GetValue;            FR3. ShowDialog ();                  }

Of course, there are other ways to pass the value, but also interested friends can be studied.

WinForm development of the form pass value