nullreferenceexception was unhandled - c#

Question

I have downloaded this PictureBox ImageArray
then I've added a button which will add all it's image to sql server 2005

this is the code:

private System.Windows.Forms.PictureBox[] imgArray2;
string c_string = "server=.\\sqlexpress;database=Blue;trusted_connection=true";


for (int i = 0; i < NumOfFiles; i++)
{
    imgArray2[i].Image = Image.FromFile(imgName[i]);
    string name = imgName[i].Substring(imgName[i].LastIndexOf(@"\") + 1, imgName[i].Length - imgName[i].LastIndexOf(@"\") - 1);
    MemoryStream mstr = new MemoryStream();
    imgArray2[i].Image.Save(mstr, imgArray2[i].Image.RawFormat);
    byte[] arrImage = mstr.GetBuffer();
    string cmd = "insert into Images (ImagePart" + i + "Name, ImagePart" + i + ") values (@PName, @Pic)";

    SqlConnection c = new SqlConnection(c_string);
    SqlCommand comm = new SqlCommand(cmd, c);
    comm.Parameters.Add(new SqlParameter("@PName", SqlDbType.VarChar, 40)).Value = name;
    comm.Parameters.Add(new SqlParameter("@Pic", SqlDbType.Image)).Value = arrImage;

    try
    {
        c.Open();
        comm.ExecuteNonQuery();
    }
    catch (System.Data.SqlClient.SqlException err)
    {
        MessageBox.Show(err.Message);
    }
    finally
    {
        c.Close();
    }

}

I've added an imgArray2[] so the image from imgArray[] won't changes and even though I'm using imgArray[] it still throwing the Null error.

The error info highlights the imgArray2[i].Image = Image.FromFile(imgName[i]);
it shows nullreferenceexception was unhandled - Object reference not set to an instance of an object.

Answer 1

The imgArray value and it's contents are never initialized. It needs to be an array capable of holding at least NumFiles items and each item needs to be initialized.

imgArray2 = new System.Windows.Forms.PictureBox[NumFiles];
for (int i = 0; i < NumOfFiles; i++)
  imgArray2[i] = new System.Windows.Forms.PictureBox();

Answer 2

您需要先实例化System.Windows.Forms.PictureBox[] imgArray2数组，然后再使用它。

Answer 3

我只是看了一下，看起来您的imgArray2从未实例化……您只是声明了一个变量并尝试访问它