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charp variable

Posted on 2009-05-18
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Last Modified: 2012-05-07
private void listBox1_DragOver(object sender, DragEventArgs e)
        {
            if (e.Data.GetDataPresent(DataFormats.FileDrop))
            {
                e.Effect = DragDropEffects.Copy;
            }
            else
            {
                e.Effect = DragDropEffects.None;
            }
        }



why we no need to declare  Type of  e.Effect      such as object e.Effect    or int  e.Effect

I am very new for csharp
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.Data.SqlClient;
 

namespace CDLib

{

    public partial class CDEntry : Form

    {

        public CDEntry()

        {

            InitializeComponent();

        }
 

        private void label3_Click(object sender, EventArgs e)

        {
 

        }
 

        private void button1_Click(object sender, EventArgs e)

        {

            this.Close();
 

        }
 

        private void listBox1_DragOver(object sender, DragEventArgs e)

        {

            if (e.Data.GetDataPresent(DataFormats.FileDrop))

            {

                e.Effect = DragDropEffects.Copy;

            }

            else

            {

                e.Effect = DragDropEffects.None;

            }

        }
 

        private void listBox1_DragDrop(object sender, DragEventArgs e)

        {

            if (e.Data.GetDataPresent(DataFormats.FileDrop))

            {

                // Reads the Drop files int to a string array;

                string[] filePaths =

                    (string[])(e.Data.GetData(DataFormats.FileDrop));
 

                // Iteraction 

                foreach (string filename in filePaths)

                {

                    string keyword = Path.GetFileNameWithoutExtension(filename);

                    this.AddKeyWord(keyword);

                }

            }
 

        }
 

        int AddKeyWord(string keyword)

        {

            string lowercaseKeyword = keyword.ToLower();
 

            int idx = KeyWordList.Items.IndexOf(lowercaseKeyword);

            if (idx == -1)

            {

                KeyWordList.Items.Add(lowercaseKeyword);
 

            }
 

            return idx;

        }
 

        private void SaveButton_Click(object sender, EventArgs e)

        {

            // Validate Form fields
 

            if (tbCdName.Text.Length < 5)

            {

                MessageBox.Show("Please enter a valid CD Name (min. 5 Characters)");

                return;
 

            }
 

            if (KeyWordList.Items.Count < 1)

            {

                MessageBox.Show("Please add Key Words to the keyword List");

                return;

            }
 

            try

            {

                this.Opacity = 40.0;

                this.Enabled = false;

                this.Cursor = Cursors.WaitCursor;
 

                if (SaveData())

                {

                    MessageBox.Show("CD Entry saved succesfully!");

                    this.Close();

                }

            }

            finally

            {

                this.Opacity = 100.0;

                this.Enabled = true;

                this.Cursor = Cursors.Default;

            }
 

          

        }
 
 

        

        /// <summary>

        /// Store the CD Entry to the Database

        /// </summary>

        /// <returns></returns>

        bool SaveData()

        {

            bool result = false;
 

            int cdLibraryID = 0;
 

            //TODO: Use a transaction in this scope

            // Create a connection 

            using (SqlConnection conn = new SqlConnection(CDLib.Program.Connstring))

            {

                // Create SqlCommand. We use a T-SQL Store Procedure

                // to insert the Data in to the CdLibrary table

                using (SqlCommand cmd = new SqlCommand("insert_CdLibrary", conn))

                {

                    cmd.CommandType = CommandType.StoredProcedure;
 

                    cmd.Parameters.AddWithValue("@CdName", tbCdName.Text);

                    cmd.Parameters.AddWithValue("@CdDescription", tbCdDescription.Text);

                    cmd.Parameters.AddWithValue("@Location", tbCdLocation.Text);

                    cmd.Parameters.AddWithValue("@CdType", "");
 
 

                    try

                    {

                        conn.Open();

                        cdLibraryID = Convert.ToInt32(cmd.ExecuteScalar());

                    }

                    catch (Exception ex)

                    {

                        conn.Close();

                        MessageBox.Show(ex.Message);

                        return false;

                    }

                    

                }

                // Create SqlCommand. We use a T-SQL Store Procedure

                // to insert the Data in to the CdLibrary_keyword table

                using (SqlCommand cmd = new SqlCommand("insert_cdkeywords", conn))

                {

                    cmd.CommandType = CommandType.StoredProcedure;
 

                    cmd.Parameters.AddWithValue("@EntryCDID", cdLibraryID);

                    cmd.Parameters.AddWithValue("@KeyWordIDList", GetKeyWordList());
 
 
 

                    try

                    {

                        cmd.ExecuteScalar();

                    }

                    catch (Exception ex)

                    {

                        conn.Close();

                        MessageBox.Show(ex.Message);

                        return false;

                    }
 
 

                    result = true;

                }

            }
 
 

            return result;

        }
 

        private string GetKeyWordList()

        {

            string result = string.Empty;
 

            for (int i = 0; i < KeyWordList.Items.Count - 1; i++ )

            {

                result += KeyWordList.Items[i].ToString() + ';';

            }
 

            return result;

            

        }
 

        private void CancelButton_Click(object sender, EventArgs e)

        {

            this.Close();

        }
 

        private void AddKeyWordButton_Click(object sender, EventArgs e)

        {
 

            if(tbKeyWord.Text.Length < 5)

            {

                MessageBox.Show("Please enter a valid KeyWord (min. 5 Characters)");

                return;
 

            }
 

            if (AddKeyWord(tbKeyWord.Text) != -1)

            {

                MessageBox.Show(string.Format("Keyword :{0} allready exists! Please try again.", tbKeyWord.Text));

                return;

            }
 

        }
 

        private void KeyWordList_SelectedIndexChanged(object sender, EventArgs e)

        {

            int idx = KeyWordList.SelectedIndex;

            if (idx != -1)

            {

                tbKeyWord.Text = KeyWordList.Items[idx].ToString();

            }

        }
 

       
 

        private void contextMenuStrip1_Opening(object sender, CancelEventArgs e)

        {

            if (KeyWordList.SelectedIndex == -1)

                e.Cancel = true;
 

        }
 

        private void deleteToolStripMenuItem_Click(object sender, EventArgs e)

        {

             int idx = KeyWordList.SelectedIndex;
 

             if (idx != -1)

             {

                 DialogResult result =

                     MessageBox.Show("Are you sure you want to delete this item?", "", 

                     MessageBoxButtons.YesNo, MessageBoxIcon.Question);

                 if(result == DialogResult.Yes)

                     KeyWordList.Items.RemoveAt(idx);
 

             }

        }
 

       

    }

}

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0
Comment
Question by:teera
1 Comment
 
LVL 10

Accepted Solution

by:
oxyoo earned 500 total points
ID: 24418714
Hi
The variable "e" is already declared as an DragEventArgs in the method as a parameter (DragEventArgs e) this means that you can use the variable e anywhere inside the listBox1_DragDrop method.
0

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