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PONullable DateTime conversion
 

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    <blockquote> <p><strong>Possible Duplicate:</strong><br> <a href="https://stackoverflow.com/questions/330471/c-sharp-why-cant-a-nullable-int-be-assigned-null-as-a-value">c# why cant a nullable int be assigned null as a value</a> </p> </blockquote> <p>Im trying to convert my reader[3] object which is datetime to be null if there is no lastPostDate for a Forum but it says Im missing a conversion. Error:</p> <blockquote> <p>Type of conditional expression cannot be determined because there is no implicit conversion between <code>&lt;null&gt;</code> and 'System.DateTime' </p> </blockquote> <pre><code>public class Forums { public List&lt;Forum&gt; GetForums() { using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["CMS"].ConnectionString)) { conn.Open(); SqlCommand cmd = new SqlCommand("sproc_Forums_GetForums", conn); cmd.CommandType = CommandType.StoredProcedure; SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.Default); List&lt;Forum&gt; forums = new List&lt;Forum&gt;(); while (reader.Read()) { var title = reader[6].ToString(); var threadCount = (int)reader[5]; var lastPostTitle = reader[4].ToString(); // below is where im having a problem Nullable&lt;DateTime&gt; lastPostDate = (reader[3] == DBNull.Value ? null : Convert.ToDateTime(reader[3])); var lastPostBy = reader[2].ToString(); var forumGroup = reader[1].ToString(); var description = reader[0].ToString(); Forum forum = new Forum(0, "",DateTime.Now, reader["Title"].ToString(),description, 0,false,"","",DateTime.Now,true, forumGroup, (int)threadCount, lastPostBy, lastPostDate, lastPostTitle); forums.Add(forum);/**/ } return forums; } } } </code></pre> <p>Below is my class object for Forum with a Nullable lastPostDate</p> <pre><code> public class Forum { public Forum(int forumID, string addedBy, DateTime addedDate, string title, string description, int parentID, bool moderated, string imageUrl, string updatedBy, DateTime? updatedDate, bool active, string forumGroup, int threadCount, string lastPostBy, Nullable&lt;DateTime&gt; lastPostDate, string lastPostTitle) { this.ForumID = forumID; this.AddedBy = addedBy; this.AddedDate = addedDate; this.Title = title; this.Description = description; this.ParentID = parentID; this.Moderated = moderated; this.ImageUrl = imageUrl; this.UpdatedBy = updatedBy; this.UpdatedDate = updatedDate; this.Active = active; this.ForumGroup = forumGroup; this.ThreadCount = threadCount; this.LastPostBy = lastPostBy; this.LastPostDate = lastPostDate; this.LastPostTitle = lastPostTitle; } private int _forumID; public int ForumID { get { return _forumID; } set { _forumID = value; } } private string _addedBy; public string AddedBy { get { return _addedBy; } set { _addedBy = value; } } private DateTime _addedDate = DateTime.Now; public DateTime AddedDate { get { return _addedDate; } set { _addedDate = value; } } private string _title = ""; public string Title { get { return _title; } set { _title = value; } } private string _description = ""; public string Description { get { return _description; } set { _description = value; } } private int _parentID = 0; public int ParentID { get { return _parentID; } set { _parentID = value; } } private bool _moderated = false; public bool Moderated { get { return _moderated; } set { _moderated = value; } } private string _imageUrl = ""; public string ImageUrl { get { return _imageUrl; } set { _imageUrl = value; } } private string _updatedBy = ""; public string UpdatedBy { get { return _updatedBy; } set { _updatedBy = value; } } private DateTime? _updatedDate = null; public DateTime? UpdatedDate { get { return _updatedDate; } set { _updatedDate = value; } } private bool _active = false; public bool Active { get { return _active; } set { _active = value; } } private string _forumGroup = ""; public string ForumGroup { get { return _forumGroup; } set { _forumGroup = value; } } private int _threadCount = 0; public int ThreadCount { get { return _threadCount; } set { _threadCount = value; } } private string _lastPostBy = ""; public string LastPostBy { get { return _lastPostBy; } set { _lastPostBy = value; } } private Nullable&lt;DateTime&gt; _lastPosteDate = null; public Nullable&lt;DateTime&gt; LastPostDate { get { return _lastPosteDate; } set { _lastPosteDate = value; } } private string _lastPostTitle = ""; public string LastPostTitle { get { return _lastPostTitle; } set { _lastPostTitle = value; } } } </code></pre>
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    1. COTip: you can use DateTime? as shorthand for Nullable<DateTime>, as with all Nullable<> types. e.g. int? is Nullable<int>, Guid? is Nullable<Guid>, etc.
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    2. COAnother duplicate: http://stackoverflow.com/q/858080/385844
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    3. COCan you please removed the irrelevant code to this question? you can keep this line only: `Nullable<DateTime> lastPostDate = (reader[3] == DBNull.Value ? null : Convert.ToDateTime(reader[3]));`
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