How to Get value from another Form in C#

Open your Visual Studio, then click New Project, then select Visual C# on the left, then Windows and then select Windows Forms Application. Name your project "GetValueFromAnotherForm" and then click OK

Design your form as shown below.

Form1

This form will contain Add and Edit buttons to open the second form (frmAddEditStudent) and retrieve a value from it.

frmAddEditStudent

Create a student class to map data

public class Student
{
    public string ID { get; set; }
    public string FullName { get; set; }
}

Add code to handle your form as shown below.

Form1

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

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

        private void btnAdd_Click(object sender, EventArgs e)
        {
            //Add a student to binding source
            using(frmAddEditStudent frm = new frmAddEditStudent() { StudentInfo = new Student() })
            {
                if (frm.ShowDialog() == DialogResult.OK)
                    studentBindingSource.Add(frm.StudentInfo);
            }
        }

        private void btnEdit_Click(object sender, EventArgs e)
        {
            Student obj = studentBindingSource.Current as Student;
            if(obj != null)
            {
                using(frmAddEditStudent frm = new frmAddEditStudent() { StudentInfo = obj })
                {
                    if(frm.ShowDialog() == DialogResult.OK)
                    {
                        studentBindingSource.EndEdit();
                        btnEdit.Focus();
                    }
                }
            }
        }
    }
}

frmAddEditStudent

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace GetValueFromAnotherForm
{
    public partial class frmAddEditStudent : Form
    {
        public Student StudentInfo { get; set; }
        public frmAddEditStudent()
        {
            InitializeComponent();
        }

        private void frmAddEditStudent_Load(object sender, EventArgs e)
        {
            //Init data
            if (StudentInfo != null)
            {
                txtStudentID.Text = StudentInfo.ID;
                txtFullName.Text = StudentInfo.FullName;
            }
        }

        private void btnOK_Click(object sender, EventArgs e)
        {
            StudentInfo.ID = txtStudentID.Text;
            StudentInfo.FullName = txtFullName.Text;
        }
    }
}

By using properties and the modal dialog pattern, you can easily pass values between forms in a C# Windows Forms application.

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