c sharp project

[Loren Rogers]

Doing this project for school.. am not new to computers, but am new to programming.
I keep getting an error stating that "boardFootPrice " is an unassigned local variable.. Could use some advice.
here is my code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        private int boardLength;
        double totalSales;
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            textBox1.Clear();
            textBox2.Clear();
            textBox3.Clear();
            panel1.Visible = false;
            Oak.Checked = true;
        }

        private void button3_Click(object sender, EventArgs e)
        {
            const double    OAK_PRICE = 6.00,
                            MAPLE_PRICE = 7.40,
                            WALNUT_PRICE = 8.50;
            int boardLength, boardWidth, boardThickness;
            double boardFeet, boardFootPrice, totalCost;
            if (Oak.Checked)
                boardFootPrice = OAK_PRICE;
            if (Maple.Checked)
                boardFootPrice = MAPLE_PRICE;
            if (Walnut.Checked)
                boardFootPrice = WALNUT_PRICE;
            boardLength = Convert.ToInt32 (textBox1.Text);
            boardWidth = Convert.ToInt32 (textBox2.Text);
            boardThickness = Convert.ToInt32 (textBox3.Text);
            boardFeet = boardLength * (boardWidth / 12.0) * boardThickness;
            totalCost = boardFeet*boardFootPrice;
            totalSales += totalCost;
            label7.Text = string.Format ("{0 2:c6}",boardFeet);
            label8.Text = string.Format ("{0 2:c6}",boardFootPrice);
            label9.Text = string.Format ("{0 2:c6}",totalCost);
            label11.Text = string.Format("{0 2:c6}", totalSales);
            textBox1.Clear();
            textBox2.Clear();
            textBox3.Clear();
            textBox1.Focus();
            Oak.Checked = true;
            button3.Enabled = false;
        }

        private void button2_Click(object sender, EventArgs e)
        {
            Close();
        }
    }
}

[GaryTexmo]

In this case the error is correctly describing the problem. You've got a local variable called boardFootPrice that you create without a default value, then you assign a value to it if certain conditions are met. However, there is a possible case none of your conditions are met and boardFootPrice doesn't get a value. You then use it in a calculation farther down.

The compiler is letting you know that you are using a variable that you haven't assigned a value to. To get rid of this error, you can assign a default value to it when you declare it...

double boardFootPrice = 0.00;

... or you can do your assignment in an if-elseif-else block...

double boardFootPrice;
if (<condition 1>)
  boardFootPrice = 1.10;
else if (<condition 2>)
  boardFootPrice = 1.25;
...
else
  boardFootPrice = 0.00;

Whichever you choose is up to you, but make sure that boardFootPrice will always have some value in it :)