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In C, two null pointers of any type are guaranteed to compare equal. [3] The preprocessor macro NULL is defined as an implementation-defined null pointer constant in <stdlib.h>, [4] which in C99 can be portably expressed as ((void *)0), the integer value 0 converted to the type void* (see pointer to void type). [5]
Many languages have explicit pointers or references. Reference types differ from these in that the entities they refer to are always accessed via references; for example, whereas in C++ it's possible to have either a std:: string and a std:: string *, where the former is a mutable string and the latter is an explicit pointer to a mutable string (unless it's a null pointer), in Java it is only ...
The null character (also null terminator) is a control character with the value zero. [1][2][3][4] It is present in many character sets, including those defined by the Baudot and ITA2 codes, ISO/IEC 646 (or ASCII), the C0 control code, the Universal Coded Character Set (or Unicode), and EBCDIC. It is available in nearly all mainstream ...
Python 3.8 introduced assignment expressions, but uses the walrus operator := instead of a regular equal sign (=) to avoid bugs which simply confuse == with =. [13] The advantage of avoiding null behavior can also be considered a disadvantage, as null pointer errors can be hidden and only appear much later in the program.
Python is a multi-paradigm programming language. Object-oriented programming and structured programming are fully supported, and many of their features support functional programming and aspect-oriented programming (including metaprogramming [70] and metaobjects). [71] Many other paradigms are supported via extensions, including design by ...
C (pronounced / ˈsiː / – like the letter c) [6] is a general-purpose programming language. It was created in the 1970s by Dennis Ritchie and remains very widely used and influential. By design, C's features cleanly reflect the capabilities of the targeted CPUs. It has found lasting use in operating systems code (especially in kernels [7 ...
Computer science applications. In subtyping systems, the bottom type is a subtype of all types. [1] It is dual to the top type, which spans all possible values in a system. If a type system is sound, the bottom type is uninhabited and a term of bottom type represents a logical contradiction. In such systems, typically no distinction is drawn ...
In C and C++, 0 represents the null pointer. As with Boolean values, the C standard library includes a macro definition NULL whose use is encouraged. Other languages provide a specific null or nil value and when this is the case no alternative should be used. The typed pointer constant nullptr has been introduced with C++11.