C-Charp

Create an new windwos forms project. Design Size. Add panel. design panel color,size,style. Add button. calculartor button and oper button. Coding button function. Declaring variables double fstNum,secNum; string oper;Identify button function btnCE private void btnCE_Click(object sender, EventArgs e) { textDisplay.Text = "0"; string f, s; f = Convert.ToString(fstNum); s = Convert.ToString(secNum); f = ""; s = ""; }backspace private void backspace_Click(object sender, EventArgs e) { if (textDisplay.Text.Length > 0) { textDisplay.Text = textDisplay.Text.Remove(textDisplay.Text.Length - 1, 1); } if (textDisplay.Text == "") { textDisplay.Text = "0"; } }btn9 private void btn9_Click(object sender, EventArgs e) { if (textDisplay.Text == "0") { textDisplay.Text = "9"; } else { textDisplay.Text = textDisplay.Text + "9"; } }btnAdd private void btnAdd_Click(object sender, EventArgs e) { fstNum = double.Parse(textDisplay.Text); oper = "+"; textDisplay.Text = ""; }btnPM ...