Scanning a .txt file of names using a windows form app (c#)

Question

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I want a program that scans a list(doctors.txt) and determines if the first and second letter (the ones entered into textbox 1&2) matches a name on the list. The names that match should popup in a messagebox. I can get it to work in as a c++ console app, but not in a c# form app.

I'm getting the following error: "Object reference not set to an instance of an object"; the error shows on the following code: "name = temp.ToCharArray();" I googled the error message, but I'm too much of a noob to make anything out of what I found. Thanks in advance for any help.

The below assumes a file named "doctors.txt" exists at "C:\"

C#

namespace doc_forms
{
    public partial class Form1 : Form
    {

        string temp;
        const string path = @"C:\doctors.txt";
        StreamReader FileOut = new StreamReader (path);
        public Form1()
        {
            InitializeComponent();
        }
        private void button1_Click(object sender, EventArgs e)
        {

            while ((temp = FileOut.ReadLine()) != null)
            {
                temp = FileOut.ReadLine();
                char[] name = new char[10];
                name = temp.ToCharArray();
                string letter = textBox1.ToString();
                string letter2 = textBox2.ToString();
                string nameL1 = name[0].ToString();
                string nameL2 = name[1].ToString();
                if (letter == nameL1 && letter2 == nameL2)
                {
                    MessageBox.Show(temp);
                }
            }
        }
    }
}

*UPDATE* 11/12 8PM
Yep, that solved it, thanks! I know the program is crap. I wasn't able to get farther because I never heard of "Substring". I will polish this ~~turd~~ now. Thanks again.

[Family friendly language please.]

Posted 12-Nov-10 15:12pm

thomas struss

Updated 13-Nov-10 4:53am

Toli Cuturicu

v3

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3 solutions

Solution 2

This design seems to be better, because you can use as many letters as you want to use as a pattern; moreover, you input is in one Textbox.

C#

const string path = @"F:\TEMP\doctors.txt";
       private void button1_Click(object sender, EventArgs e)
       {
           string input = File.ReadAllText(path);
           string pattern = @"^" + textBox1.Text + @"\w*\r";
           foreach (Match m in Regex.Matches(input, pattern, RegexOptions.Multiline))
           {
               MessageBox.Show(m.Value);
           }
       }

Posted 12-Nov-10 17:01pm

Heinzzy

Solution 3

C#

namespace doc_forms{    public partial class Form1 : Form    {        string temp;        const string path = @"C:\doctors.txt";        StreamReader FileOut = new StreamReader (path);        public Form1()        {            InitializeComponent();        }        private void button1_Click(object sender, EventArgs e)        {            while ((temp = FileOut.ReadLine()) != null)            {                temp = FileOut.ReadLine();                char[] name = new char[10];                name = temp.ToCharArray();                string letter = textBox1.ToString();                string letter2 = textBox2.ToString();                string nameL1 = name[0].ToString();                string nameL2 = name[1].ToString();                if (letter == nameL1 && letter2 == nameL2)                {                    MessageBox.Show(temp);                }            }        }    }}

Posted 9-Dec-10 7:01am

raju kumar singh

Comments

fjdiewornncalwe 9-Dec-10 14:39pm

Hey Raju: This was answered almost a month ago... Please don't add another answer to one that is that old if an approved answer already exists. Cheers.

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Heinzzy · Accepted Answer · 2010-11-12T16:44:00

Here it is. First of all remove the second "temp" line after while and you wont see any exceptions.

C#

string temp;
        const string path = @"F:\TEMP\doctors.txt";
        StreamReader FileOut = new StreamReader(path);
        private void button1_Click(object sender, EventArgs e)
        {
            while ((temp = FileOut.ReadLine()) != null)
            {
                if ((textBox1.Text+textBox2.Text)==(temp.Substring(0,2)))
                {
                    MessageBox.Show(temp);
                }
            }
        }

But the whole program seems to be ... not so good