namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private void textBox2_TextChanged(object sender, EventArgs e)
        {
            textBox2.ReadOnly = true;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            var s = textBox1.Text;
            byte[] bytes = Encoding.ASCII.GetBytes(s);
            var result = BitConverter.ToInt32(bytes, 0);
            textBox2.Text = result;
        }

    }
}