How to send NULL in HTTP query string? - Stack Overflow
So if you don't need to support the difference between empty and null/absent string you may also consider the empty parameter as null. If instead you want to recreate point 4. of JSON …
Null object in Python - Stack Overflow
2010年7月20日 · How do I refer to the null object in Python?
What is the convention in JSON for empty vs. null?
2012年3月8日 · I know that in most programming scenarios, the preference is for empty collections to null collections when there are 0 elements. However, most languages that …
What exactly is meant by "dereferencing a NULL pointer"?
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 …
How do I create a unique constraint that also allows nulls?
2009年4月20日 · I want to have a unique constraint on a column which I am going to populate with GUIDs. However, my data contains null values for this columns. How do I create the …
javascript - Why is null an object and what's the difference …
2009年4月29日 · In order to be able to query this difference, JavaScript has null and undefined: While null is - just like in other languages an object, undefined cannot be an object because …
What is a NullReferenceException, and how do I fix it?
I have some code and when it executes, it throws a NullReferenceException, saying: Object reference not set to an instance of an object. What does this mean, and what can I do to fix …
What is a NullPointerException, and how do I fix it?
What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? What methods/tools can be used to determine the cause so that you stop the exception from …
.net - What does "Object reference not set to an instance of an …
If you try to access a member of a class instance using a null reference then you get a System.NullReferenceException. Which is the same as Object reference not set to an instance …
Java "?." operator for checking null - What is it? (Not Ternary!)
2015年11月18日 · Take the latest version of Java, which tries to make null-pointer checking easier by offering shorthand syntax for the endless pointer testing. Just adding a question …