Search results
Results from the WOW.Com Content Network
In all versions of Python, boolean operators treat zero values or empty values such as "", 0, None, 0.0, [], and {} as false, while in general treating non-empty, non-zero values as true. The boolean values True and False were added to the language in Python 2.2.1 as constants (subclassed from 1 and 0 ) and were changed to be full blown ...
The null coalescing operator is a binary operator that is part of the syntax for a basic conditional expression in several programming languages, such as (in alphabetical order): C# [1] since version 2.0, [2] Dart [3] since version 1.12.0, [4] PHP since version 7.0.0, [5] Perl since version 5.10 as logical defined-or, [6] PowerShell since 7.0.0, [7] and Swift [8] as nil-coalescing operator.
Bot is useful in typing the "leaf nodes" of polymorphic data structures. For example, List(Bot) is a good type for nil. Bot is a natural type for the "null pointer" value (a pointer which does not point to any object) of languages like Java: in Java, the null type is the universal subtype of reference types.
In all modern character sets, the null character has a code point value of zero. In most encodings, this is translated to a single code unit with a zero value. For instance, in UTF-8 it is a single zero byte. However, in Modified UTF-8 the null character is encoded as two bytes: 0xC0,0x80. This allows the byte with the value of zero, which is ...
In some programming language environments (at least one proprietary Lisp implementation, for example), [citation needed] the value used as the null pointer (called nil in Lisp) may actually be a pointer to a block of internal data useful to the implementation (but not explicitly reachable from user programs), thus allowing the same register to be used as a useful constant and a quick way of ...
The number 0 is represented by zero while null is a representation of an empty set {}. Hence in computer science a zero represents the outcome of a mathematical computation such as 2−2, while null is used for an undefined state (for example, a memory location that has not been explicitly initialised).
As a result, the empty set is the unique initial object of the category of sets and functions. The empty set can be turned into a topological space, called the empty space, in just one way: by defining the empty set to be open. This empty topological space is the unique initial object in the category of topological spaces with continuous maps.
The Cantor set is an example of an uncountable null set. It is uncountable because it contains all numbers between 0 and 1 whose ternary form contains only 0's and 2's in their decimal expansion, and it is null because it is constructed by beginning with the closed interval of real numbers from 0 to 1 and multiplying the length by 2/3 continuously.