|
- c# - What does null! statement mean? - Stack Overflow
It can be used on a type to control Nullability, it is then called the "Null Forgiving Operator" Basically, null! applies the ! operator to the value null This overrides the nullability of the value null to non-nullable, telling the compiler that null is a "non-null" type
- What is the purpose of null? - Stack Overflow
Null: The Billion Dollar Mistake Tony Hoare: I call it my billion-dollar mistake It was the invention of the null reference in 1965 At that time, I was designing the first comprehensive type system for references in an object oriented language (ALGOL W) My goal was to ensure that all use of references should be absolutely safe, with checking performed automatically by the compiler But I
- Why does NULL = NULL evaluate to false in SQL server
The expression "NULL = NULL" evaluates to NULL, but is actually invalid in SQL; yet ORDER BY treats NULLs as equal (whatever they precede or follow "regular" values is left to DBMS vendor)
- What is null in Java? - Stack Overflow
The null reference can always be cast to any reference type In practice, the programmer can ignore the null type and just pretend that null is merely a special literal that can be of any reference type What is null? As the JLS quote above says, in practice you can simply pretend that it's "merely a special literal that can be of any reference
- What is the difference between is not null and != null?
The main difference between e != null and e is not null is the way the the compiler executes the comparison Microsoft: "The compiler guarantees that no user-overloaded equality operator == is invoked when expression x is null is evaluated " Bottom Line: If you are writing code that you don't want to depend on someone's implementation of the != and == operators, use is null and is not null
- How do I check for null values in JavaScript? - Stack Overflow
How can I check for null values in JavaScript? I wrote the code below but it didn't work
- What is the difference between null and undefined in JavaScript?
From the preceding examples, it is clear that undefined and null are two distinct types: undefined is a type itself (undefined) while null is an object Proof :
- How can I check for an undefined or null variable in JavaScript?
The one benefit I can see is that it does not require knowing that == null and != null treat a declared variable with value undefined as equal to null IMHO, that isn't reason enough to use this unfamiliar (and inefficent - creates an array every time) syntax
|
|
|