C# calculator application

Question

This is the code for the calculator in which i have been attempting to make. I have got it to work except i have one error that i cant seem to figure out how to fix it.

whenever the user clicks the wrong operator then clicks the correct one that they wish to use the operator (+ button - button ect)will not change to the correct one and the function carried out will be in incorrect one.

    double value_1 = 0;
    bool double_operation = false;
    bool clickable_decimal = true;
    bool operation_pressed = false;
    bool second_click = false;
    bool second_equals = false;
    String math_operator = "";


    private void btn_Click(object sender, EventArgs e)
    {
        if (second_equals == true)
        {
            txt_display.Text = "0";
            //value_1 = 0;
            second_equals = false;
        }
        if ((txt_display.Text == "0") || (operation_pressed == true))
        {
            txt_display.Clear();
        }
        operation_pressed = false;
        Button btn = (Button)sender;
        txt_display.Text = txt_display.Text + btn.Text;
        double_operation = false;

    }

    private void btn_clear_Click(object sender, EventArgs e)
    {
        txt_display.Text = "0";
        value_1 = 0;
    }

    private void btn_deci_Click(object sender, EventArgs e)
    {
        {
            if (clickable_decimal == true)
            {
                Button btn = (Button)sender;
                txt_display.Text = txt_display.Text + btn.Text;
                clickable_decimal = false;
            }

        }
    }

    private void btn_operator_Click(object sender, EventArgs e)
    {
        if (double_operation == false)
        {
            if (second_click == false)
            {

                Button btn = (Button)sender;
                math_operator = btn.Text;
                value_1 = double.Parse(txt_display.Text);
                operation_pressed = true;
                clickable_decimal = true;
                second_equals = false;
            }

            if (second_click == true)
            {
                Button btn = (Button)sender;

                //value_2 = double.Parse(txt_display.Text);
                operation_pressed = true;
                clickable_decimal = true;

                switch (math_operator)
                {
                    case "+":
                        txt_display.Text = (value_1 + double.Parse(txt_display.Text)).ToString();
                        break;

                    case "-":
                        txt_display.Text = (value_1 - double.Parse(txt_display.Text)).ToString();
                        break;

                    case "/":
                        txt_display.Text = (value_1 / double.Parse(txt_display.Text)).ToString();
                        break;

                    case "*":
                        txt_display.Text = (value_1 * double.Parse(txt_display.Text)).ToString();
                        break;

                }//end switch
                value_1 = double.Parse(txt_display.Text);
                math_operator = btn.Text;
                second_equals = true;
            }
            second_click = true;
        }
        double_operation = true;

}

    private void btn_equals_Click(object sender, EventArgs e)
    {
        if (second_equals == false)
        {
            switch (math_operator)
            {
                case "+":
                    txt_display.Text = (value_1 + double.Parse(txt_display.Text)).ToString();
                    break;

                case "-":
                    txt_display.Text = (value_1 - double.Parse(txt_display.Text)).ToString();
                    break;

                case "/":
                    txt_display.Text = (value_1 / double.Parse(txt_display.Text)).ToString();
                    break;

                case "*":
                    txt_display.Text = (value_1 * double.Parse(txt_display.Text)).ToString();
                    break;

            }//end switch
            value_1 = double.Parse(txt_display.Text);
            second_click = false;
            second_equals = true;
        }

Answer 1

You're using math_operator to store the selected math operator. Its value is only set when second_click == false (in btn_operator_Click() ), therefore it seems clear why the second click doesn't change things.

Answer 2

I figured out the answer and anyone who is interested here it is.

    double value_1 = 0;
    bool double_operation = false;
    bool clickable_decimal = true;
    bool operation_pressed = false;
    bool second_click = false;
    bool second_equals = false;
    String math_operator = "";


    private void btn_Click(object sender, EventArgs e)
    {
        if (second_equals == true)
        {
            txt_display.Text = "0";
            //value_1 = 0;
            second_equals = false;
        }
        if ((txt_display.Text == "0") || (operation_pressed == true))
        {
            txt_display.Clear();
        }
        operation_pressed = false;
        Button btn = (Button)sender;
        txt_display.Text = txt_display.Text + btn.Text;
        double_operation = false;

    }

    private void btn_clear_Click(object sender, EventArgs e)
    {
        txt_display.Text = "0";
        value_1 = 0;
    }

    private void btn_deci_Click(object sender, EventArgs e)
    {
        {
            if (clickable_decimal == true)
            {
                Button btn = (Button)sender;
                txt_display.Text = txt_display.Text + btn.Text;
                clickable_decimal = false;
            }

        }
    }

    private void btn_operator_Click(object sender, EventArgs e)
    {
//==========================================================================
        if (double_operation == true)
        {
            math_operator = "";
            double_operation = false;
            second_click = false; // however it will work without this but i       
            //do not know why so ill leave it in 
        }
 // this is the solution 
 //=========================================================================
        if (double_operation == false)
        {
            if (second_click == false)
            {

                Button btn = (Button)sender;
                math_operator = btn.Text;
                value_1 = double.Parse(txt_display.Text);
                operation_pressed = true;
                clickable_decimal = true;
                second_equals = false;
            }

            if (second_click == true)
            {
                Button btn = (Button)sender;
                operation_pressed = true;
                clickable_decimal = true;
                switch (math_operator)
                {
                    case "+":
                        txt_display.Text = (value_1 + double.Parse(txt_display.Text)).ToString();
                        break;

                    case "-":
                        txt_display.Text = (value_1 - double.Parse(txt_display.Text)).ToString();
                        break;

                    case "/":
                        txt_display.Text = (value_1 / double.Parse(txt_display.Text)).ToString();
                        break;

                    case "*":
                        txt_display.Text = (value_1 * double.Parse(txt_display.Text)).ToString();
                        break;

                }//end switch
                value_1 = double.Parse(txt_display.Text);
                math_operator = btn.Text;
                second_equals = true;
            }
            second_click = true;
        }
        double_operation = true;

}

    private void btn_equals_Click(object sender, EventArgs e)
    {
        if (second_equals == false)
        {
            switch (math_operator)
            {
                case "+":
                    txt_display.Text = (value_1 + double.Parse(txt_display.Text)).ToString();
                    break;

                case "-":
                    txt_display.Text = (value_1 - double.Parse(txt_display.Text)).ToString();
                    break;

                case "/":
                    txt_display.Text = (value_1 / double.Parse(txt_display.Text)).ToString();
                    break;

                case "*":
                    txt_display.Text = (value_1 * double.Parse(txt_display.Text)).ToString();
                    break;

            }//end switch
            value_1 = double.Parse(txt_display.Text);
            second_click = false;
            second_equals = true;
        }

By clicking the wrong operator it will reset the math_operator to equal nothing then setting double_operation to false so that the rest if the code below can be preformed when the user hits the correct operator.