There was a huge debate about this oddity when the feature was originally designed back in C# 2.0. The problem is that C# users are completely used to this being meaningful: if(someReference == null) When extending equality to nullable value types, you have the following choices. Nullable equality is truly lifted. If one or both … Read more
Instead of using int you can use Integer (Integer javadoc) because it is a nullable Java class.
Then presumably you’ll need to lift them to the non-nullable form, using Nullable.GetUnderlyingType, and perhaps change a few null values to DbNull.Value… Change the assignment to be: row[prop.Name] = prop.GetValue(item) ?? DBNull.Value; and when adding the columns to be: table.Columns.Add(prop.Name, Nullable.GetUnderlyingType( prop.PropertyType) ?? prop.PropertyType); And it works. (?? is the null-coalescing operator; it uses the … Read more
This should work: [XmlIgnore] public int? Age { get; set; } [XmlElement(“Age”)] public string AgeAsText { get { return (Age.HasValue) ? Age.ToString() : null; } set { Age = !string.IsNullOrEmpty(value) ? int.Parse(value) : default(int?); } }
In Java 8, you could use Stream.allMatch to check whether all of the values match a certain condition, such as being null. Not much shorter, but maybe a bit easier to read. if (Stream.of(a, b, c).allMatch(x -> x == null)) { … } And analogeously for anyMatch and noneMatch. About your “more challenging example”: In … Read more
This is one of the biggest sources of confusion with VB.Net, IMO. Nothing in VB.Net is the equivalent of default(T) in C#: the default value for the given type. For value types, this is essentially the equivalent of ‘zero’: 0 for Integer, False for Boolean, DateTime.MinValue for DateTime, … For reference types, it is the … Read more
First of all, thanks for pointing out that the spec isn’t clear on the non-dynamic nullable-bool case. I will fix that in a future version. The compiler’s behavior is the intended behavior; && and || are not supposed to work on nullable bools. The dynamic binder does not seem to implement this restriction, though. Instead, … Read more
In .Net, you cannot assign a null value to an int or any other struct. Instead, use a Nullable<int>, or int? for short: int? value = 0; if (value == 0) { value = null; } Further Reading Nullable Types (C# Programming Guide)
int? x = string.IsNullOrEmpty(cert) ? (int?)null : int.Parse(cert);
You can achieve what you want by re-arranging your query a bit. The trick is that the ISNULL has to be on the outside before SQL Server will understand that the resulting value can never be NULL. SELECT ISNULL(CAST( CASE Status WHEN 3 THEN 1 ELSE 0 END AS bit), 0) AS HasStatus FROM dbo.Product … Read more