c# - Open text file, loop through contents and check against -

so have generic number check trying implement:

    public static bool isnumbervalid(string number)     {     } 

and want read contents of textfile (only contains numbers) , check each line number , verify valid number using isnumbervalid. want output results new textfile, got far:

    private void button2_click(object sender, eventargs e)     {         int size = -1;         dialogresult result = openfiledialog1.showdialog(); // show dialog.         if (result == dialogresult.ok) // test result.         {             string file = openfiledialog1.filename;             try             {                 string text = file.readalltext(file);                 size = text.length;                 using (stringreader reader = new stringreader(text))                 {                          foreach (int number in text)                         {                             // check against isnumbervalid                             // write results new textfile                          }                     }                 }              catch (ioexception)             {             }         }     } 

kind of stuck here if can help?

the textfile contains several numbers in list:

4564

4565

4455

etc.

the new textfile want write numbers true or false appended end:

4564 true

you try keep pattern following...

private void button1_click(object sender, eventargs e) {     dialogresult result = openfiledialog1.showdialog(); // show dialog.     if (result == dialogresult.ok) // test result.     {         string file = openfiledialog1.filename;         try         {             using (var reader = new streamreader(file))             {                 using (var writer = new streamwriter("results.txt"))                 {                     string currentnumber;                     while ((currentnumber = reader.readline()) != null)                     {                         if (isnumbervalid(currentnumber))                             writer.writeline(string.format("{0} true", currentnumber));                     }                 }             }         }          catch (ioexception)         {         }     } }  public bool isnumbervalid(string number) {     //whatever code use check number }