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What do two question marks together mean in C#?
Hi, I was looking for some trainings of MVC 2 in C# and I found this sintax:
ViewData["something"] = something ?? true; So, what is that '??' means ?.
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An operator is a symbol that operates on a value or a variable. For example: + is an operator to perform addition. C has a wide range of operators to perform various operations.
Summary. An operator is a symbol which operates on a variable or value. There are types of operators like arithmetic, logical, conditional, relational, bitwise, assignment operators etc. Some special types of operators are also present in C like sizeof(), Pointer operator, Reference operator etc.
It means to perform a bitwise operation with the values on the left and right-hand side, and then assign the result to the variable on the left, so a bit of a short form.
It's the null-coalescing operator.
It returns the first argument unless it is null, in which case it returns the second.
x ?? y is roughly equivalent to this (except that the first argument is only evaluated once):
if (x == null) { result = y; } else { result = x; } Or alternatively:
(x == null) ? y : x It is useful for providing a default value for when a value can be null:
Color color = user.FavouriteColor ?? defaultColor; COALESCE
When used in a LINQ to SQL query the ?? operator can be translated to a call to COALESCE. For example this LINQ query:
var query = dataContext.Table1.Select(x => x.Col1 ?? "default"); can result in this SQL query:
SELECT COALESCE([t0].[col1],@p0) AS [value] FROM [dbo].[table1] AS [t0] If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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