Dec 4, 2009 · 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 …

In Java I am told that when doing a null check one should use == instead of .equals(). What are the reasons for this?

And then == null does a perfect job, because it covers exactly those 2 values. (i.e. == null is equivalent to === null && === undefined) In exceptional cases you do want a clear distinction …

Sep 21, 2021 · The only difference (besides the syntax) is, that the compiler guarantees that no user-overloaded operator is called when using is not null instead of != null (or is null instead of …

In C, there appear to be differences between various values of zero -- NULL, NUL and 0. I know that the ASCII character '0' evaluates to 48 or 0x30. The NULL pointer is usually defined as: …

Sep 6, 2013 · The operators for Nullable<T> are so-called "lifted" operators]; the c# compiler takes the operators available for T and applies a set of pre-defined rules; for example, with +, …

The title of this bug says "check for undefined or null", but the question itself checks for undeclared or null.

In other words, a null pointer is a pointer of any type pointing at a well-defined "nowhere". Any pointer can turn into a null pointer when it is assigned a null pointer constant. The standard …

Sep 6, 2017 · Comparing NULL with anything yields a NULL. NULL is part of trinary logic: TRUE, FALSE, and NULL. -- These are all NULL. select NULL > -1, NULL < -1, NULL = NULL, NULL …

But in this case only null and undefined are loosely equal to each other, therefore != null will return false for either of the two value, true for everything else. typeof input !== "undefined" Here the …