Simple Calculator in C#.net (in if-else statment)

Calculator in C#.net (with if-else statement)
In this tutorial we will be creating a simple c#.net calculator with the options to add, Multiply, Divide, Subtract. I am using visual studio 2012, but you can  use c# text editor that you like.
-> To start a new project goto Microsoft Visual Studio.
-> New -> Project -> Windows Form Application name Calculator in csharp (or whatever you want).
-> Design the form as follows.

Set the following properties for it in the Properties Window:

Control	Name	Text	Other Property
button1	btn1	1	Size = 54, 35
button2	btn2	2	Size = 54, 35
button3	btn3	3	Size = 54, 35
button4	btn4	4	Size = 54, 35
button5	btn5	5	Size = 54, 35
button6	btn6	6	Size = 54, 35
button7	btn7	7	Size = 54, 35
button8	btn8	8	Size = 54, 35
button9	btn9	9	Size = 54, 35
button10	btn0	0	Size = 54, 35
button11	btndot	.	Size = 54, 35
button12	btnequal	=	Size = 54, 35
button13	btnadd	+	Size = 114, 35
button14	btnminus	-	Size = 114, 35
button15	btndivide	/	Size = 114, 35
button16	btnmultiply	*	Size = 114, 35
Button17	btnclear	Clear	Size = 294, 35
Textbox1	txtresult		Size = 294, 35

In this the form have a text box and 17 buttons for different uses.

After completing the design we can start the coding .

Double click the button and write the following code.

Code for btn1

private void btn1_Click(object sender, EventArgs e)         {             txtresult.Text += btn1.Text;         }

Code for btn2

private void btn2_Click(object sender, EventArgs e)         {             txtresult.Text += btn2.Text;         }

Code for btn3

private void btn3_Click(object sender, EventArgs e)         {             txtresult.Text += btn3.Text;         }

Code for btn4

private void btn4_Click(object sender, EventArgs e)         {             txtresult.Text += btn4.Text;         }

Code for btn5

private void btn5_Click(object sender, EventArgs e)         {             txtresult.Text += btn5.Text;         }

Code for btn6

private void btn6_Click(object sender, EventArgs e)         {             txtresult.Text += btn6.Text;         }

Code for btn7

private void btn7_Click(object sender, EventArgs e)         {             txtresult.Text += btn7.Text;         }

Code for btn8

private void btn8_Click(object sender, EventArgs e)         {             txtresult.Text += btn8.Text;         }

Code for btn9

private void btn9_Click(object sender, EventArgs e)         {             txtresult.Text += btn9.Text;         }

Code for btn0

private void btn0_Click(object sender, EventArgs e)         {             txtresult.Text += btn0.Text;         }

Now add the following four instance Boolean variables and 2 instance double variable.

          double t1;

        double t2;

        bool badd = false;

        bool bminus = false;

        bool bdivide = false;

        bool bmultiply = false;

Now Double click the btnadd and write the following code:

Code for btnadd

private void btnadd_Click(object sender, EventArgs e)         {             t1 += double.Parse(txtresult.Text);             txtresult.Clear();             badd = true;             bminus = false;             bdivide = false;             bmultiply = false;         }

Now Double click the btnminus and write the following code:

Code for btnminus

private void btnminus_Click(object sender, EventArgs e)         {             t1 += double.Parse(txtresult.Text);             txtresult.Clear();             badd = false;             bminus = true;             bdivide = false;             bmultiply = false;         }

Double click the btndivide and write the following code:

Code for btndivide

private void btndivide_Click(object sender, EventArgs e)         {             t1 += double.Parse(txtresult.Text);             txtresult.Clear();             badd = false;             bminus = false;             bdivide = true;             bmultiply = false;         }

Double click the btnmultiply and write the following code:

Code for btnmultiply

private void btnmultiply_Click(object sender, EventArgs e)         {             t1 += double.Parse(txtresult.Text);             txtresult.Clear();             badd = false;             bminus = false;             bdivide = false;             bmultiply = true;         }

Double click the btnequal and write the following code:

Code for btnequal

private void btnequal_Click(object sender, EventArgs e)         {             if (badd == true)             {                 t2 = t1 + double.Parse(txtresult.Text);             }             else if (bminus == true)             {                 t2 = t1 - double.Parse(txtresult.Text);             }             else if (bdivide == true)             {                 t2 = t1 / double.Parse(txtresult.Text);             }             else if (bmultiply == true)             {                 t2 = t1 * double.Parse(txtresult.Text);             }             else             {                 MessageBox.Show("Syntex Error");             }             txtresult.Text = t2.ToString();             t1 = 0;         }

Double click the btnclear and write the following code:

Code for btnclear

private void btnclear_Click(object sender, EventArgs e)         {             txtresult.Clear();         }

Your coding window will then look like this:

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 Calculator_in_csharp

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        double t1;

        double t2;

        bool badd = false;

        bool bminus = false;

        bool bdivide = false;

        bool bmultiply = false;

        private void btn9_Click(object sender, EventArgs e)

        {

            txtresult.Text += btn9.Text;

        }

        private void btn5_Click(object sender, EventArgs e)

        {

            txtresult.Text += btn5.Text;

        }

        private void btn1_Click(object sender, EventArgs e)

        {

            txtresult.Text += btn1.Text;

        }

        private void btn2_Click(object sender, EventArgs e)

        {

            txtresult.Text += btn2.Text;

        }

        private void btn3_Click(object sender, EventArgs e)

        {

            txtresult.Text += btn3.Text;

        }

        private void btn4_Click(object sender, EventArgs e)

        {

            txtresult.Text += btn4.Text;

        }

        private void btn6_Click(object sender, EventArgs e)

        {

            txtresult.Text += btn6.Text;

        }

        private void btn7_Click(object sender, EventArgs e)

        {

            txtresult.Text += btn7.Text;

        }

        private void btn8_Click(object sender, EventArgs e)

        {

            txtresult.Text += btn8.Text;

        }

        private void btn0_Click(object sender, EventArgs e)

        {

            txtresult.Text += btn0.Text;

        }

        private void btnclear_Click(object sender, EventArgs e)

        {

            txtresult.Clear();

        }

        private void btnadd_Click(object sender, EventArgs e)

        {

            t1 += double.Parse(txtresult.Text);

            txtresult.Clear();

            badd = true;

            bminus = false;

            bdivide = false;

            bmultiply = false;

        }

        private void btnminus_Click(object sender, EventArgs e)

        {

            t1 += double.Parse(txtresult.Text);

            txtresult.Clear();

            badd = false;

            bminus = true;

            bdivide = false;

            bmultiply = false;

        }

        private void btndivide_Click(object sender, EventArgs e)

        {

            t1 += double.Parse(txtresult.Text);

            txtresult.Clear();

            badd = false;

            bminus = false;

            bdivide = true;

            bmultiply = false;

        }

        private void btnmultiply_Click(object sender, EventArgs e)

        {

            t1 += double.Parse(txtresult.Text);

            txtresult.Clear();

            badd = false;

            bminus = false;

            bdivide = false;

            bmultiply = true;

        }

        private void btnequal_Click(object sender, EventArgs e)

        {

            if (badd == true)

            {

                t2 = t1 + double.Parse(txtresult.Text);

            }

            else if (bminus == true)

            {

                t2 = t1 - double.Parse(txtresult.Text);

            }

            else if (bdivide == true)

            {

                t2 = t1 / double.Parse(txtresult.Text);

            }

            else if (bmultiply == true)

            {

                t2 = t1 * double.Parse(txtresult.Text);

            }

            else

            {

                MessageBox.Show("Syntex Error");

            }

            txtresult.Text = t2.ToString();

            t1 = 0;

        }

    }

}

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