The role of question marks in C# value types
While the question mark is typically used in conditional statements (e.g., x ? "yes" : "no" ), it also has a different purpose in the context of value types.
Nullable value type
In C#, a question mark after a value type (for example, int? myVariable) indicates that the value type is nullable. This means that it can represent not only the standard value range of the underlying data type, but also the special null value.
For example, Nullable
Advantages of nullable types
Nullable types have the following advantages:
- Accurate representation of unknown data: They allow missing or unassigned values to be correctly represented in data structures.
- Safe assignment of null values: Use nullable types to ensure that null values are handled explicitly, thus preventing errors and crashes.
- Consistent handling of null values: Nullable types provide a consistent way to handle null values, simplifying code development and maintenance.
Example usage
The following code snippet demonstrates the use of nullable integer values:
class NullableExample { static void Main() { int? num = null; if (num.HasValue) System.Console.WriteLine("num = " + num.Value); else System.Console.WriteLine("num = Null"); int y = num.GetValueOrDefault(); try { y = num.Value; } catch (System.InvalidOperationException e) { System.Console.WriteLine(e.Message); } } }
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