C# Object reference not set to an instance of an object

Question

im getting the Object reference not set to an instance of an object for line 43 and i cant figure out why, i have searched the web and cant seem to find the answer. i am new to C# and programming in general and trying to learn. if some one can help me out it would be great

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;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;

namespace test
{
    public partial class Form1 : Form
    {
        [Serializable]
        public class ore 
        {
            public float Titan;
            public float Eperton;
        }

        ore b1 = null;
        ore b2 = null;

        public Form1()
        {
            InitializeComponent();

            ore b2 = new ore();
            ore b1 = new ore();
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            float tempFloat;

            if (float.TryParse(textBox1.Text, out tempFloat))
            {
                b1.Titan = tempFloat; //line 43; where error happens
            }
            else
                MessageBox.Show("uh oh");
        }

        private void textBox2_TextChanged(object sender, EventArgs e)
        {
            float tempFloat;
            if (float.TryParse(textBox1.Text, out tempFloat))
            {
                b2.Eperton = tempFloat;
            }
            else
                MessageBox.Show("uh oh");
        }

        private void button1_Click(object sender, EventArgs e)
        {
            List<ore> oreData = new List<ore>();
            oreData.Add(b1);
            oreData.Add(b2);

            FileStream fs = new FileStream("ore.dat", FileMode.Create);
            BinaryFormatter bf = new BinaryFormatter();
            bf.Serialize(fs, oreData);
            fs.Close();
        }
    }
}

This isn't the full code... It should work. Edit: Damn, missed that. — Vercas
– Vercas, Commented Jun 26, 2011 at 23:12
Vercas: it is the full code, see Rob's answer. The mistake is very subtle. — Femaref
– Femaref, Commented Jun 26, 2011 at 23:13
pastebin.com/y7xCACbn this is a pastebin link of the entire code just in case it didnt copy correctly — doc
– doc, Commented Jun 26, 2011 at 23:14
it compiles fine but when and number is added to the text box the error shows — doc
– doc, Commented Jun 26, 2011 at 23:14

Rob · Accepted Answer · 2011-06-26 23:13:18Z

6

I'm assuming it's failing on any of the b1/b2 references.

ore b1 = null;
ore b2 = null;

Here you're declaring two private variables for your class

ore b2 = new ore();
ore b1 = new ore();

Here you're declaring two local variables for that method call. You're not altering the original variables. Change it to:

b2 = new ore();
b1 = new ore();

answered Jun 26, 2011 at 23:13

Rob♦

27.5k16 gold badges89 silver badges103 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

doc Over a year ago

AWESOME okay that error is gone. i have a new issue however, the button is supposed to list ore and write it to a file called ore.dat in the programs directory. i ran the program and hit the save button BUT no new file in my project directory??

Martin Liversage · Accepted Answer · 2011-06-26 23:13:42Z

5

You never assign the field b1. The b1 you assign in the constructor is a local variable. Change the code in the constructor to this:

b2 = new ore();
b1 = new ore();

answered Jun 26, 2011 at 23:13

Martin Liversage

107k24 gold badges216 silver badges263 bronze badges

Comments

Mo Valipour · Accepted Answer · 2011-06-26 23:14:37Z

3

change your constructor to this:

public Form1()
    {
        InitializeComponent();

        b2 = new ore();
        b1 = new ore();
    }

answered Jun 26, 2011 at 23:14

Mo Valipour

13.5k13 gold badges64 silver badges87 bronze badges

Collectives™ on Stack Overflow

C# Object reference not set to an instance of an object

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related