C# Discussion Boards - CodeProject

Reading A Specific value From Txt File

14-Feb-09 22:18

When posting with errors/exceptions it's helpful if you indicate which line the exception occurred on!

Anyway, you didn't change the FileHelperEngine instanciation line as I suggested previously, so I guess the error is there.

Fh1 = new FileHelperEngine(typeof(type));

now needs to be

Fh1 = new FileHelperEngine(type);

as you already have the Type in type - no need (and it won't compile) to do a typeof on it.

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

wwwxyz14-Feb-09 8:53

14-Feb-09 8:53

my t1.txt is:
1
5
18
125
.
.
.
I want to read a specific value from txt file( sample 3.value that is 18)

using System;<br />
using System.Collections.Generic;<br />
using System.IO;<br />
<br />
class Program<br />
{<br />
    static void Main()<br />
    {<br />
        const string f =(@"C:\t1.txt");<br />
<br />
        // 1<br />
        // Declare new List.<br />
        List<string> lines = new List<string>();<br />
<br />
        // 2<br />
        // Use using StreamReader for disposing.<br />
        using (StreamReader r = new StreamReader(f))<br />
        {<br />
            // 3<br />
            // Use while != null pattern for loop<br />
            string line;<br />
            while ((line = r.ReadLine()) != null)<br />
            {<br />
                // 4<br />
                // Insert logic here.<br />
                // ...<br />
                // "line" is a line in the file. Add it to our List.<br />
                lines.Add(line);<br />
            }<br />
        }<br />
<br />
        // 5<br />
        // Print out all the lines.<br />
        foreach (string s in lines)<br />
        { <br />
            Console.WriteLine(s);<br />
        }<br />
     <br />
    }<br />
}</string></string>

Wendelius14-Feb-09 9:11

Wendelius

14-Feb-09 9:11

You could try using File.ReadAllLines[^] which returns an array of data from your file.

If you want to refer to specific line (for example 3 as in your post) you would simply use ...yourvariable[2]...

The need to optimize rises from a bad design.My articles[^]

Calin Tatar14-Feb-09 9:14

Calin Tatar

14-Feb-09 9:14

this means you want to read the value from line X?
you may implement a helper method wich takes the StreamReader and returns the value contained in a file at line X. use a loop to skip the lines and count them.

Calin

Nuri Ismail14-Feb-09 9:18

14-Feb-09 9:18

If you want a value from the specific line, you can simply count the lines and use the value from the correct one. Just like this:

string line;

int current_line = 0;
int desired_line = 3;

while ((line = r.ReadLine()) != null)
{
  current_line++;

  if(current_line == desired_line)
  { 
    lines.Add(line);
    break;
  }
}

This is just a sample logic. I hope you can use something like that for your case.

wwwxyz14-Feb-09 9:28

14-Feb-09 9:28

thank you problem solved

Deresen14-Feb-09 11:01

Deresen

14-Feb-09 11:01

To comment on this post, I'd write this code a little different and smaller, like this.

It maybe is just my style, but I think it's better:

int desired_line = 3;

for(int current_line = 0, string line; (line = r.ReadLine()) != null; current_line++)
{
   if(current_line == desired_line)
   {
      lines.Add(line);
      break;
   }
}

wwwxyz14-Feb-09 11:18

14-Feb-09 11:18

thanks for replies
t1.txt is:
11
22
33
44
55
.
.

how can I get x value? x=a(line's 1 value)+b(line's 3 value)+c(line 5)that is c must 99

using System;<br />
using System.IO;<br />
<br />
class MainClass<br />
{<br />
    public static void Main(string[] args)<br />
    {<br />
        try<br />
        {<br />
            FileStream fs = new FileStream("c:\\t1.txt", FileMode.Open);<br />
            StreamReader sr = new StreamReader(fs);<br />
<br />
            string line = "";<br />
<br />
            int lineNo = 0;<br />
            do<br />
            {<br />
                line = sr.ReadLine();<br />
                if (line != null)<br />
                {<br />
                    Console.WriteLine("{0}: {1}", lineNo, line);<br />
                    lineNo++;<br />
                  x=a+b+c;-------->values=?<br />
                }<br />
            } while (line != null);<br />
        }<br />
        catch (Exception e)<br />
        {<br />
            Console.WriteLine("Exception in ShowFile: {0}", e);<br />
        }<br />
    }<br />
}

Deresen14-Feb-09 11:30

Deresen

14-Feb-09 11:30

First of all: use the pre tag, it's better than the code tag.

Secondly it is not as tough as you think. Just use common sense for this question:

You are using the do while construction, but if I where you, I should use the while function or for function.

List<string> lines = new List<string>();
String line;
//add all the lines to a list
while((line = sr.ReadLine()) != null)
{
     lines.Add(line);
}
//read the lines you would like to read:
try
{
   int numberOne = Int32.Parse(lines[0]);
   int numberThree = Int32.Parse(lines[2]);
   int numberFive = Int32.Parse(lines[4]);
   int x = numberOne + numberThree + numberFive;
}
catch {}
</string></string>

You could use the TryParse method, but you can also use the try catch block.

Good luck!

wwwxyz14-Feb-09 11:53

14-Feb-09 11:53

wonderful
thank you very much

imagemap with highlight

Axell14-Feb-09 8:19

Axell

14-Feb-09 8:19

Hi!

I have a world map in my GUI and I want the countries to highlight when mouse hovers over a country. Something like this http://www.netzgesta.de/mapper/

Is this possible to do this with c# at all?

I have read about the Imagemap controller with which it is possible to do polygon hotspots, but I'm not sure this is exactly what I need. It can't change anything within the coordinates of the polygon when mouse hovers over the hotspots.

Can someone give me a clue what to do?

Nuri Ismail14-Feb-09 8:27

14-Feb-09 8:27

Have a look at this:

http://www.codeproject.com/KB/miscctrl/imagemapcontrol.aspx[^]

DaveyM6914-Feb-09 8:29

14-Feb-09 8:29

LMAO! Just posted the exact same link Big Grin | :-D

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

Axell14-Feb-09 8:34

Axell

14-Feb-09 8:34

Yes, but it doesn't have that hover effect.

DaveyM6914-Feb-09 11:29

14-Feb-09 11:29

So use it as a base and program the hover effect yourself.

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

DaveyM6914-Feb-09 8:28

array table or string table

14-Feb-09 8:28

There's an article here[^] that might help

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

abbd14-Feb-09 7:38

14-Feb-09 7:38

hello,

I would stock a list of string, i make this

<br />
string[] TableauString;<br />
<br />
TableauString[tt]= (nom.Trim() + ";" + prenom.Trim() + ";" + adresse1.Trim() + ";" + cp.Trim() + ";" + ville.Trim() + resultat3.Trim() + resultat2.Trim());<br />
tt++;<br />
<br />

there are exception : the referce is not instance of obkect, help me please to resolve this problem, thank you verry mutch

Nuri Ismail14-Feb-09 8:04

14-Feb-09 8:04

The exception occurs because you don't allocate any memory for the string array. Try something like this:

string[] TableauString = new string[10]; // Array of 10 strings

Here i allocate a memory for 10 elements. This is only an example. You have to specify correct size for the array depending on your needs.

abbd14-Feb-09 8:39

14-Feb-09 8:39

If i don't know the size of my elements?? thank you verry mutch

hendrik14-Feb-09 8:53

hendrik

14-Feb-09 8:53

You can use the code as shown bellow just replace
"The Size" with an int number

TestArray= Array.CreateInstance(typeof(String),"The Size");

this will create a array based on the size that you want

hopes this helps

Nuri Ismail14-Feb-09 8:55

14-Feb-09 8:55

Then you can use ArrayList. Here is a sample code:

using System.Collections;

........

ArrayList myList = new ArrayList();

// Adding an element
myList.Add(new string(" Here is your string "));

// Or you can add elements like this
for(int i=0; i<5; i++)
    myList.Add(new string(" Here is your string "));

abbd14-Feb-09 8:59

14-Feb-09 8:59

When i declare array list, this error appear : Erreur 1 The type or namespace name 'ArrayList' could not be found (are you missing a using directive or an assembly reference?) C:\Documents and Settings\Administrateur\Mes documents\Visual Studio 2005\Projects\Form@Home1.0\WindowsApplication2\Form1.cs 20 83 WindowsApplication2

Thank you verry mutch

Nuri Ismail14-Feb-09 9:02

14-Feb-09 9:02

You have to insert the next "using" directive at the top of your source file:

using System.Collections;

abbd14-Feb-09 9:14