Image save / retrieve/ extension / delete

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image save
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public string Save_Photo = HttpContext.Current.Server.MapPath("~/Upload/User_Photo/");
public string Get_Photo = "~/Upload/User_Photo/";

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image retrieve
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Img_USER_PHOTO.ImageUrl = clas.Get_Photo + dt.Rows[0]["USER_PHOTO"].ToString();


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Sub string
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Fup_USER_PHOTO.FileName.Substring(Fup_USER_PHOTO.FileName.LastIndexOf('.'));

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delete image from folder
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System.IO.File.Delete(HttpContext.Current.Server.MapPath("~/images/") + DropDownList1.SelectedValue);

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File search
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if (File.Exists(clas.Save_Photo + Photo_Del))
{
File.Delete(clas.Save_Photo + Photo_Del);
}

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File extensions
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if (fu.HasFile) // fu refers to FileUpload control.
{
String fileExtension = System.IO.Path.GetExtension(fu.FileName).ToLower();
String[] allowedExtensions = { ".jpg", ".gif", ".png" };
for (int i = 0; i < allowedExtensions.Length; i++)
{
if (fileExtension == allowedExtensions[i])
{
fileOK = true;
if (fileOk == true) { fu.SaveAs("path" + fu.FileName); }
}
}