C# App: Exception Handling

[Shani Aulakh]

Hi All,

Is it the right way of handling exception in a method?

        public int DeleteFilesOlderThan(int days, int hrs, int mins)
        {
            string[] older = FilesOlderThan(Days, Hrs, Mins);
            int count = 0;
            foreach (string file in files)
            {
                try
                {
                    File.Delete(file);
                    count++;
                }
                catch (Exception e)
                {
                    Console.WriteLine("Unable to delete " + file);
                    Console.WriteLine("Reason: {0}", e);
                    //Console.WriteLine("Detected an exception!!!\n" + e );
                }
                Console.WriteLine("Files successfully deleted");
            }
            // presumably number of files deleted to be returned
            return count;
        }
 

[Plater]

That looks like a pretty solid handling to me.

[Shani Aulakh]

Thanks, But when i debug the application, the files get deleted but i dont see the msg showing Files successfully deleted.

[Shani Aulakh]

can you check if this is coded properly using date time object

        public static DateTime GetRelativeDateTime(int days, int hours, int minutes)
        {
            return DateTime.Now.AddDays(-days).AddHours(-hours).AddMinutes(-minutes);
        }
 
        public int DeleteFilesOlderThan(DateTime dt)
        {
            string[] older = FilesOlderThan(dt);
            int count = 0;
            foreach (string file in files)
            {
                try
                {
                    File.Delete(file.Name);
                    count++;
                }
                catch (Exception e)
                {
                    Console.WriteLine("Unable to delete " + file);
                    Console.WriteLine("Reason: {0}", e);
                    //Console.WriteLine("Detected an exception!!!\n" + e );
                }
                Console.WriteLine("Files successfully deleted");
            }
            // presumably number of files deleted to be returned
            return count;
        }
 
        public static string[] FilesOlderThan(DateTime dt)
        {
            DirectoryInfo directory = new DirectoryInfo(Directory.GetCurrentDirectory());
            FileInfo[] files = directory.GetFiles(FolderPath); //get FileInfos for the files in the current directory 
            ArrayList older = new ArrayList(); //list to hold the result 
            foreach (FileInfo file in files)
            {
                if (file.CreationTime < dt) //if smaller (older) than the relative time 
                    older.Add(file.Name); //add it to the list 
            }
        }
 

[Plater]

Thanks, But when i debug the application, the files get deleted but i dont see the msg showing Files successfully deleted.

Does it show the messages you print out in your catch {} block?

[Shani Aulakh]

Before when i was compiling the application, it was showing in pending checkins that files successfully deleted. but not anymore:S

[Shani Aulakh]

okay i did some modification in my class...but its not deleting specific files from event handler...
[code]
using System;
using System.IO;
using System.Collections;

namespace Files_ExtLib1
{
public class FolderWatcher
{
string m_FolderPath;

public FolderWatcher()
{
//
// TODO: Add constructor logic here
//
}

#region Property
public string FolderPath
{
get
{
return m_FolderPath;
}
set
{
m_FolderPath = value;
}
}
#endregion

public int DeleteFilesOlderThan(int Days, int Hrs, int Mins, string filter)
{
DateTime dt = GetRelativeDateTime(Days, Hrs, Mins);
ArrayList oldFilePaths = FilesOlderThan(dt, filter);
int count = 0;
foreach (string filePath in oldFilePaths)
{
try
{
File.Delete(filePath);
count++;
}
catch (Exception e)
{
Console.WriteLine("Unable to delete {0}", filePath);
Console.WriteLine("Reason: {0}", e);
}
Console.WriteLine("Files successfully deleted");
}
return count;
}

public static DateTime GetRelativeDateTime(int days, int hours, int minutes)
{
return DateTime.Now.AddDays(-days).AddHours(-hours).AddMinutes(-minutes);
}

public static ArrayList FilesOlderThan(DateTime dt, string filter)
{
DirectoryInfo directory = new DirectoryInfo(Directory.GetCurrentDirectory());
FileInfo[] files = directory.GetFiles(filter); //get FileInfos for the files in the current directory matching the filter expression
ArrayList older = new ArrayList(); //list to hold the result
foreach (FileInfo file in files)
{
if (file.CreationTime < dt) //if smaller (older) than the relative time
older.Add(file.Name); //add it to the list
}

return older;
}
}
}
[code]

button event handler that deletes files..

        private void DeleteFiles_Click(object sender, EventArgs e)
        {
            FolderWatcher fw = new FolderWatcher();
            fw.FolderPath = @"c:\csharp"; // FolderName
            fw.DeleteFilesOlderThan(0, 0, 0, "*.txt"); // deletes everything older than specified days,hrs, and mins respectively 
        }
 

[Plater]

And you keep getting the exceptions printed out?

[Shani Aulakh]

nopes, I am not getting any exceptions printed out

[Plater]

Have you put a breakpoint on the File.Delete() to see if
A) it's actually getting called
and
B) What value is being passed to it?

[Shani Aulakh]

okay i will check that out.......i want to know another thing. I wrote the following code to create text files and to create multiple text files i guess i can run the code in a loop. but i want to generate dummy files using .txt, .log, .exe file format in button GenerateTestFiles eventhandler

using System;
using System.IO;
 
class FileTest
{
    static void Main()
    {
        StreamWriter outStream = null;
        string filename = "output.txt";
 
        try
        {
            outStream = new StreamWriter(filename);
            outStream.WriteLine("Hello World");
            outStream.Close();
        }
        catch (Exception e)
        {
            Console.WriteLine("Unable to create file {0}", filename);
            Console.WriteLine("Reason: {0}", e);
            return;
        }
        Console.WriteLine("File successfully created");
    }
}
 

[Shani Aulakh]

I created three textboxes to enter days, mins, hrs and a combo box for extension on my form.

this wouldn't work?

        private void DeleteFiles_Click(object sender, EventArgs e)
        {
            FolderWatcher fw = new FolderWatcher();
            fw.FolderPath = @"c:\csharp"; // FolderName
            OpenFileDialog OpenFileDialog1 = new OpenFileDialog();
            fw.DeleteFilesOlderThan(int.Parse(Textbox1.Text), int.Parse(Textbox2.Text), int.Parse(Textbox3.Text), OpenFileDialog1.Filter); // deletes everything older than specified days,hrs, and mins respectively 
        }
 

[Plater]

It might or it might not, did you go in and check to see if it even found any files that matched the search pattern?

[Shani Aulakh]

i put a breakpoint to check it throughly. this is the FolderWatcher.cs class. I modified the code using DateTime object. I think FolderPath is not defined in the current directory

using System;
using System.IO;
using System.Collections;
 
namespace Files_ExtLib1
{
    public class FolderWatcher
    {
        string m_FolderPath;
 
        public FolderWatcher()
        {
            //
            // TODO: Add constructor logic here
            //
        }
 
        #region Property
        public string FolderPath
        {
            get
            {
                return m_FolderPath;
            }
            set
            {
                m_FolderPath = value;
            }
        }
        #endregion
 
        /// <summary>
        /// Deletes the files older the days, hours, and
        /// minutes specified
        /// </summary>
        /// <param name="Days"></param>
        /// <param name="Hrs"></param>
        /// <param name="Mins"></param>
        /// <returns>Number of files deleted</returns>
        //public int DeleteFilesOlderThan(int Days, int Hrs, int Mins)
        //{
        //    string[] oldFilePaths = FilesOlderThan(Days, Hrs, Mins);
        //    int count = 0;
        //    foreach (string filePath in oldFilePaths)
        //    {
        //        try
        //        {
        //            File.Delete(filePath);
        //            count++;
        //        }
        //        catch (Exception e)
        //        {
        //            Console.WriteLine("Unable to delete " + filePath);
        //            Console.WriteLine("Reason: {0}", e);
        //            //Console.WriteLine("Detected an exception!!!\n" + e );
        //        }
        //        Console.WriteLine("Files successfully deleted");
        //    }
        //    // presumably number of files deleted to be returned
        //    return count;
        //}
 
 
        /// <summary>
        /// Reurns filenames having last modified time older than
        /// specified period.
        /// </summary>
        /// <param name="Days"></param>
        /// <param name="Hrs"></param>
        /// <param name="Mins"></param>
        /// <returns></returns>
        //public string[] FilesOlderThan(int Days, int Hrs, int Mins)
        //{
        //    TimeSpan ts = new TimeSpan(Days, Hrs, Mins, 0);
        //    ArrayList oldFilePaths = new ArrayList();
        //    // FolderPath is assumed to be path being watched
        //    string[] filePaths = Directory.GetFiles(FolderPath);
        //    DateTime currentDate = DateTime.Now;
        //    foreach (string filePath in filePaths)
        //    {
        //        DateTime lastWriteDate = File.GetLastWriteTime(filePath);
        //        if ((currentDate - lastWriteDate) > ts)
        //        {
        //            oldFilePaths.Add(filePath);
        //        }
        //    }
        //    return (string[])oldFilePaths.ToArray(typeof(string));
        //}
 
        public int DeleteFilesOlderThan(int Days, int Hrs, int Mins, string filter)
        {
            DateTime dt = GetRelativeDateTime(Days, Hrs, Mins);
            ArrayList oldFilePaths = FilesOlderThan(dt, filter);
            int count = 0;
            foreach (string filePath in oldFilePaths)
            {
                try
                {
                    File.Delete(filePath);
                    count++;
                }
                catch (Exception e)
                {
                    Console.WriteLine("Unable to delete {0}", filePath);
                    Console.WriteLine("Reason: {0}", e);
                }
                Console.WriteLine("Files successfully deleted");
            }
            return count;
        }
 
        public static DateTime GetRelativeDateTime(int days, int hours, int minutes)
        {
            return DateTime.Now.AddDays(-days).AddHours(-hours).AddMinutes(-minutes);
        }
 
        public static ArrayList FilesOlderThan(DateTime dt, string filter)
        {
            DirectoryInfo directory = new DirectoryInfo(Directory.GetCurrentDirectory());
            FileInfo[] files = directory.GetFiles(filter); //get FileInfos for the files in the current directory matching the filter expression
            ArrayList older = new ArrayList(); //list to hold the result 
            foreach (FileInfo file in files)
            {
                if (file.CreationTime < dt) //if smaller (older) than the relative time 
                    older.Add(file.Name); //add it to the list 
            }
 
            return older;
        }
    }
}