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The star height problem in formal language theory is the question whether all regular languages can be expressed using regular expressions of limited star height, i.e. with a limited nesting depth of Kleene stars. Specifically, is a nesting depth of one always sufficient? If not, is there an algorithm to determine how many are required? The ...
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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.
In C, array indexing is formally defined in terms of pointer arithmetic; that is, the language specification requires that array[i] be equivalent to *(array + i). [8] Thus in C, arrays can be thought of as pointers to consecutive areas of memory (with no gaps), [8] and the syntax for accessing arrays is identical for that which can be used to ...
A class diagram exemplifying the singleton pattern. In object-oriented programming, the singleton pattern is a software design pattern that restricts the instantiation of a class to a singular instance. It is one of the well-known "Gang of Four" design patterns, which describe how to solve recurring problems in object-oriented software. [1]
The C headers <stdnoreturn.h> and <threads.h> do not have C++ equivalents and their C headers are not supported in C++. C++ does not provide the C POSIX library as part of any standard, however it is legal to use in a C++ program. If used in C++, the POSIX headers are not prepended with a "c" at the beginning of the name, and all contain the .h ...
For example, \11 is an octal escape sequence denoting a byte with decimal value 9 (11 in octal). However, \1111 is the octal escape sequence \111 followed by the digit 1 . In order to denote the byte with numerical value 1, followed by the digit 1 , one could use "\1""1" , since C concatenates adjacent string literals.
Given a set , define = {} (the language consisting only of the empty string), =, and define recursively the set + = {:} for each >. If is a formal language, then , the -th power of the set , is a shorthand for the concatenation of set with itself times.