If Statements

// if else
if (fname != "")
{
    label_nameOutput.Text = "Hello " + fname + " " + lname + "!";
}
else
{
    MessageBox.Show("Rob is amazing.");
}   

//switch
switch (expression)
{
    case value_1:
        statements;
        break;
    case value_2;
        satemetns;
        break;
    default:
        statements;
        break;
}

// checkbox
if (choiceRadioButton.Checked) {} else {};
//or
if (choiceRadioButton.Checked == true) {} else {};

// int.TryParse | if successful returens true
int number;
if (int.TryParse(inputTextBox.Text, out number)) {
    //code
}

// if selectbox doesnt have a value
// switch statement for value of selectbox
if (listBox_timezones.SelectedIndex != -1)
{

    switch (listBox_timezones.SelectedIndex)
    {
        case 0:
            label_timezone_output.Text = "Eastern";
            break;
        case 1:
            label_timezone_output.Text = "Mountain";
            break;
        case 2:
            label_timezone_output.Text = "Pacific";
            break;

        default:
            break;
    }

}
else
{
    MessageBox.Show("Please select an item.");

}

// grab number from textbox, check if its a number

string tb_input = textBox_enterint.Text;
int tb_input_int;

if (int.TryParse(tb_input, out tb_input_int))
{

    switch (tb_input_int)
    {
        case 1:
            label_answer.Text = "I";
            break;
        case 2:
            label_answer.Text = "II";
            break;
        case 3:
            label_answer.Text = "III";
            break;
        case 4:
            label_answer.Text = "IV";
            break;
        case 5:
            label_answer.Text = "V";
            break;
        case 6:
            label_answer.Text = "VI";
            break;
        case 7:
            label_answer.Text = "VII";
            break;
        case 8:
            label_answer.Text = "VIII";
            break;
        case 9:
            label_answer.Text = "IX";
            break;
        case 10:
            label_answer.Text = "X";
            break;

        default:
            MessageBox.Show("Your entry is invalid.");
            textBox_enterint.Text = "";
            break;
    }

}
else
{
    MessageBox.Show("Please enter an integer only.");
    textBox_enterint.Text = "";

}

// get number from textbox, check if number, do stuff acording the value.

const int PRICE = 99;
double discount;
string tb_input = textBox_numberOfPackages.Text;
int amount;
string discount_display;

if (int.TryParse(tb_input, out amount))
{

    if (amount < 10)
    {
        discount = 1;
        discount_display = "None";
    }
    else if (amount < 20)
    {
        discount = 0.2;
        discount_display = "20%";

    }
    else if (amount < 50)
    {
        discount = 0.3;
        discount_display = "30%";

    }
    else if (amount < 100)
    {
        discount = 0.4;
        discount_display = "40%";

    }
    else
    {
        discount = 0.5;
        discount_display = "50%";

    }

    label_discount.Text = discount_display;
    label_total.Text = "$" + ((PRICE * amount) * discount);

}
else
{
    MessageBox.Show("Please enter an integer only.");
    textBox_numberOfPackages.Text = "";
    textBox_numberOfPackages.Focus();
}