父子窗口传值

窗体传值可以分为两类。
1、主窗体往子窗体传值
有两种方法，一种是在子窗体提供重载构造函数，利用重载构造函数传递值，适用于传值数量比较少；第二种是，在子窗体中定义一个主窗体对象，然后就可以接收到主窗体的属性值了，适用于传值数量大。
主窗体代码如下：

 public partial class frmParent : Form
    {
        private string strValueA = "";
        public string StrValueA
        {
            get
            {
                return this.strValueA;
            }
            set { this.strValueA = value; }
        }
        public frmParent()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            this.strValueA = textBox1.Text;
            frmChild frmchild = new frmChild();
            frmchild.Owner = this;
            frmchild.ShowDialog();
            frmchild.Dispose();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            frmChild frmchild = new frmChild(this.textBox1.Text);
            string returnValue = "";
            if (frmchild.ShowDialog() == DialogResult.OK)
            {
                returnValue = frmchild.Str;
                this.textBox1.Text = returnValue;
            }
        }
    }
子窗体代码如下：

public partial class frmChild : Form
    {
        private string str;
        public string Str
        {
            get { return this.str; }
            set { this.str = value; }
        }
        private frmParent frmparent;

        public frmChild()
        {
            InitializeComponent();
        }
        public frmChild(string str)
        {
            this.str = str;
            InitializeComponent();
            this.textBox1.Text = str;
        }
        private void frmChild_Load(object sender, EventArgs e)
        {
            frmparent = (frmParent)this.Owner;
            //this.textBox1.Text = frmparent.StrValueA;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //frmparent = (frmParent)this.Owner;
            this.Str = this.textBox1.Text;
            this.DialogResult = DialogResult.OK;
            this.Close();
           
        }
    }
2、从子窗体返回值到主窗体中
利用了子窗体的属性保存子窗体的值，在主窗体中可以访问到子窗体的属性
主窗体代码如下：

 public partial class frmParent : Form
    {
        private string strValueA = "";
        public string StrValueA
        {
            get
            {
                return this.strValueA;
            }
            set { this.strValueA = value; }
        }
        public frmParent()
        {
            InitializeComponent();
        }
        private void button2_Click(object sender, EventArgs e)
        {
            frmChild frmchild = new frmChild(this.textBox1.Text);
            string returnValue = "";
            if (frmchild.ShowDialog() == DialogResult.OK)
            {
                returnValue = frmchild.Str;
                this.textBox1.Text = returnValue;
            }
        }
    }
子窗体代码如下：

public partial class frmChild : Form
    {
        private string str;
        public string Str
        {
            get { return this.str; }
            set { this.str = value; }
        }
        private frmParent frmparent;

        public frmChild()
        {
            InitializeComponent();
        }
         private void frmChild_Load(object sender, EventArgs e)
        {
            frmparent = (frmParent)this.Owner;
            //this.textBox1.Text = frmparent.StrValueA;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //frmparent = (frmParent)this.Owner;
            this.Str = this.textBox1.Text;
            this.DialogResult = DialogResult.OK;
            this.Close();
           
        }
    }