How to Make Calculator in C#

Today in this article I will show you how to make a simple basic calculator in C#.

Global variables

// Global variables

private double FirstNumber = 0.0;

private double SecondNumber = 0.0;

private string OperatorString = "+";

private double Result = 0.0;

Diagram

calculator

Button events

//zero button click event

        private void ZeroButton_Click(object sender, EventArgs e)

        {

            ZeroRemove(0);

        }

        //zero remove function and here other number will add on the texbox

        private void ZeroRemove(int number)

        {

            if (CalcTextBox.Text == "0")

                CalcTextBox.Text =number.ToString();

            else

                CalcTextBox.Text += number.ToString();

        }

        //three button click event

        private void OneButton_Click(object sender, EventArgs e)

        {

            ZeroRemove(1);

        }

        //three button click event

        private void TwoButton_Click(object sender, EventArgs e)

        {

            ZeroRemove(2);

        }

        //three button click event

        private void ThreeButton_Click(object sender, EventArgs e)

        {

            ZeroRemove(3);

        }

 

        private void FourButton_Click(object sender, EventArgs e)

        {

            ZeroRemove(4);

        }

 

        private void FiveButton_Click(object sender, EventArgs e)

        {

            ZeroRemove(5);

        }

 

        private void SixButton_Click(object sender, EventArgs e)

        {

            ZeroRemove(6);

        }

 

        private void SevenButton_Click(object sender, EventArgs e)

        {

            ZeroRemove(7);

        }

 

        private void EightButton_Click(object sender, EventArgs e)

        {

            ZeroRemove(8);

        }

 

        private void NineButton_Click(object sender, EventArgs e)

        {

            ZeroRemove(9);

        }

        //Clear button click event here clear the texbox

        private void ClearButton_Click(object sender, EventArgs e)

        {

            CalcTextBox.Clear();

            CalcTextBox.Text = "0";

            FirstNumber = 0.0;

            SecondNumber = 0.0;

            Result = 0.0;

 

        }

        //Here put . in the textbox

        private void DoBtutton_Click(object sender, EventArgs e)

        {

            if (!CalcTextBox.Text.Contains("."))

                CalcTextBox.Text += ".";

        }

        //plus button

        private void PlusButton_Click(object sender, EventArgs e)

        {

            SuppliedOperator("+");

 

        }

        // It is general function which recieve the coming operator

        private void SuppliedOperator(string operatorString)

        {

            OperatorString = operatorString;

            FirstNumber = double.Parse(CalcTextBox.Text);

            CalcTextBox.Text = "0";

        }

 

        private void MinusButton_Click(object sender, EventArgs e)

        {

            SuppliedOperator("-");

        }

 

        private void DivisionButton_Click(object sender, EventArgs e)

        {

            SuppliedOperator("/");

        }

 

        private void MultiplyButton_Click(object sender, EventArgs e)

        {

            SuppliedOperator("*");

        }

        //Equal button

        private void EqualButton_Click(object sender, EventArgs e)

        {

            SecondNumber = double.Parse(CalcTextBox.Text);// here recieve second number from the user.

 

            switch (OperatorString)// switch

            {

                case "+":

                    Result = FirstNumber + SecondNumber;

                    break;

                case "-":

                    Result = FirstNumber - SecondNumber;

                    break;

                case "/":

                    Result = FirstNumber / SecondNumber;

                    break;

                case "*":

                    Result = FirstNumber * SecondNumber;

                    break;

                case "%":

                    Result = FirstNumber % SecondNumber;

                    break;

                case "sin":

                    Result = System.Math.Sin(FirstNumber);

                    break;

                case "cos":

                    Result = System.Math.Cos(FirstNumber);

                    break;

                case "tan":

                    Result = System.Math.Tan(FirstNumber);

                    break;

            }

            CalcTextBox.Text = Result.ToString();

        }

 

        private void MinusPlusButton_Click(object sender, EventArgs e)

        {

            if (!CalcTextBox.Text.Contains("-"))

                CalcTextBox.Text = "-" + CalcTextBox.Text;

            else

                CalcTextBox.Text = CalcTextBox.Text.Trim('-');

        }

 

        private void PercentageButton_Click(object sender, EventArgs e)

        {

            SuppliedOperator("%");

        }

        //sin button

        private void SinButton_Click(object sender, EventArgs e)

        {

            SuppliedOperator("sin");

        }

 

        private void CosButton_Click(object sender, EventArgs e)

        {

            SuppliedOperator("cos");

        }

        //cos button

        private void TanButton_Click(object sender, EventArgs e)

        {

            SuppliedOperator("cos");

        }

I have also attached the source code so you can download it and run it in your PC.