How to make a Calculator in C#.net

In this tutorials will teach how to make a calculator in C#.net windows form application step by step. How to create the calculator in C#.net application in best coding practice.

First Step

Declare the variables

string CalTotal;
        int num1;
        int num2;
        string option;
        int result;

You have to paste the below Codes 1 to 0 buttons

private void btn1_Click(object sender, EventArgs e)
        {
            txtTotal.Text = txtTotal.Text + "1";
        }

        private void btn2_Click(object sender, EventArgs e)
        {
            txtTotal.Text = txtTotal.Text + "2";
        }

        private void btn3_Click(object sender, EventArgs e)
        {
            txtTotal.Text = txtTotal.Text + "3";
        }

        private void btn4_Click(object sender, EventArgs e)
        {
            txtTotal.Text = txtTotal.Text + "4";
        }

        private void btn5_Click(object sender, EventArgs e)
        {
            txtTotal.Text = txtTotal.Text + "5";
        }

        private void btn6_Click(object sender, EventArgs e)
        {
            txtTotal.Text = txtTotal.Text + "6";
        }

        private void btn7_Click(object sender, EventArgs e)
        {
            txtTotal.Text = txtTotal.Text + "7";
        }

        private void btn8_Click(object sender, EventArgs e)
        {
            txtTotal.Text = txtTotal.Text + "8";
        }

        private void btn9_Click(object sender, EventArgs e)
        {
            txtTotal.Text = txtTotal.Text + "9";
        }

        private void btn0_Click(object sender, EventArgs e)
        {
            txtTotal.Text = txtTotal.Text + "0";
        }

Paste the following codes to **+,-,*,/ button**

private void btnPlus_Click(object sender, EventArgs e)
        {
            option = "+";
            num1 = int.Parse(txtTotal.Text);

            txtTotal.Clear();
        }

        private void btnMin_Click(object sender, EventArgs e)
        {
            option = "-";
            num1 = int.Parse(txtTotal.Text);

            txtTotal.Clear();
        }

        private void btnMul_Click(object sender, EventArgs e)
        {
            option = "*";
            num1 = int.Parse(txtTotal.Text);

            txtTotal.Clear();
        }

        private void btnDiv_Click(object sender, EventArgs e)
        {
            option = "/";
            num1 = int.Parse(txtTotal.Text);

            txtTotal.Clear();
        }

Paste the following codes inside the = Button

private void btnEql_Click(object sender, EventArgs e)
        {
            num2 = int.Parse(txtTotal.Text);

            if (option.Equals("+"))
                result = num1 + num2;

            if (option.Equals("-"))
                result = num1 - num2;

            if (option.Equals("*"))
                result = num1 * num2;

            if (option.Equals("/"))
                result = num1 / num2;

            txtTotal.Text = result + "";
        }

Paste the following codes inside the Clear Button

private void btnClear_Click(object sender, EventArgs e)
        {
            txtTotal.Clear();
            result = (0);
            num1 = (0);
            num2 = (0);
        }