Who invented null?

Speaking at a software conference in 2009, Tony Hoare apologized for inventing the null reference: 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).

Why was null a mistake?

The problem with NULL is that it is a non-value value, a sentinel, a special case that was lumped in with everything else. Instead, we need an entity that contains information about (1) whether it contains a value and (2) the contained value, if it exists.

Is null good or bad?

The fundamental problem of null is that it is trying to represent the fact that it is not a value while being assigned as a value. This fundamental flaw then snowballs and manifests into problems that we see in everyday production code.

What is the point of null?

A NULL value is a special marker used in SQL to indicate that a data value does not exist in the database. In other words, it is just a placeholder to denote values that are missing or that we do not know. NULL can be confusing and cumbersome at first.

Why is it often said that the introduction of null is a billion dollar mistake?

The language could have been designed without it. Tony Hoare , the inventor of null (in ALGOL) calls it a “billion dollar mistake”: This has led to innumerable errors, vulnerabilities, and system crashes, which have probably caused a billion dollars of pain and damage in the last forty years.

Null References The Billion Dollar Mistake

Is null really a mistake?

While undefined has been in existence since the creation of coding, null is the misguided invention of British computer scientist Tony Hoare (most famous for his Quicksort algorithm) in 1964, who coined his invention of null references as his “billion dollar mistake”.

What is null first?

Specifying the order of NULL values

In a descending sort, DESC NULLS FIRST specifies that rows with a NULL value in the sort key column precede non-NULL rows in the sorted result set. The NULLS LAST keywords instruct the database server to put NULL values last in the sorted query results.

What happens if you write to null?

If a reference points to null , it simply means that there is no value associated with it. Technically speaking, the memory location assigned to the reference contains the value 0 (all bits at zero), or any other value that denotes null in the given environment.

Why is null true?

If a string-based field has null=True , that means it has two possible values for "no data": NULL , and the empty string. In most cases, it's redundant to have two possible values for "no data"; the Django convention is to use the empty string, not NULL .

What does null actually mean?

Null means having no value; in other words null is zero, like if you put so little sugar in your coffee that it's practically null. Null also means invalid, or having no binding force. From the Latin nullus, meaning "not any," poor, powerless null is not actually there at all. Or if it was, it's gone now.

Why do people hate null?

The problems with null have little to do with null pointer exceptions. The problem with null is that it puts a lot of burden on every line of code to say, “This might be null”. Effectively that doubles your work load on every line… which means that the work goes up exponentially.

How do you escape from null?

But there is no way to escape the null character. To "escape" something means to remove its usual or its special interpretation, or to give it some other interpretation. In C string and character constants, the backslash character \ gives a special meaning to the character following it.

Is null a legendary?

Type: Null (Japanese: タイプ：ヌル Type: Null) is a Normal-type Legendary Pokémon introduced in Generation VII.

What is null in time?

time(NULL) returns the number of seconds elapsed since 00:00:00 hours, GMT (Greenwich Mean Time), January 1, 1970.

Why is it bad to return null?

It's very tempting to just return a null reference, but this could cause problems for the caller. If the caller(or callers), fails to do a null check, it could result in a NullPointerException being thrown if some value from the item object is used.

Which languages are null safe?

The C# language implements compile-time null safety check since version 8. However, to stay compatible with anterior versions of the language, the feature is opt-in on a per project or per file basis. Other languages that use null-safe types by default include JetBrains' Kotlin, Rust, and Apple's Swift.

Is null == null true?

null == undefined evaluates as true because they are loosely equal. null === undefined evaluates as false because they are not, in fact, equal. <null_variable> === null is the best way to strictly check for null.

Is null always 0?

The null pointer constant is always 0. The NULL macro may be defined by the implementation as a naked 0 , or a cast expression like (void *) 0 , or some other zero-valued integer expression (hence the "implementation defined" language in the standard).

Is null null false?

If the value of expression is NULL, IS NULL returns TRUE; otherwise, it returns FALSE.

Is it safe to delete null?

Yes it is safe. There's no harm in deleting a null pointer; it often reduces the number of tests at the tail of a function if the unallocated pointers are initialized to zero and then simply deleted. There are all sorts of nits that can be picked with the sample code, but the concept is (I hope) clear.

What is null in math?

In mathematical sets, the null set is a set that does not contain any values or elements. It is expressed as { } and denoted using the Greek letter ∅ (phi). A null set is also known as an empty set or void set. There is only one null set because, logically, there's only one way that a set can contain nothing.

What is null in Python?

In many other languages, null is just a synonym for 0 , but null in Python is a full-blown object: >>> >>> type(None) <class 'NoneType'> This line shows that None is an object, and its type is NoneType .

Is the null 1 or 0?

The null hypothesis is a default hypothesis that a quantity to be measured is zero (null).

WHERE does null come from?

English borrowed null from the Anglo-French nul, meaning "not any." That word, in turn, traces to the Latin word nullus, from ne-, meaning "not," and ullus, meaning "any." Null often pops up in legal and scientific contexts.

What is null code?

In computer science, a null value represents a reference that points, generally intentionally, to a nonexistent or invalid object or address. The meaning of a null reference varies among language implementations. In JavaScript, null is marked as one of the primitive values, because its behavior is seemingly primitive.