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Python's is operator may be used to compare object identities (comparison by reference), and comparisons may be chained—for example, a <= b <= c. Python uses and, or, and not as Boolean operators. Python has a type of expression named a list comprehension, and a more general expression named a generator expression. [78]
Python supports normal floating point numbers, which are created when a dot is used in a literal (e.g. 1.1), when an integer and a floating point number are used in an expression, or as a result of some mathematical operations ("true division" via the / operator, or exponentiation with a negative exponent).
Parse tree of Python code with inset tokenization. The syntax of textual programming languages is usually defined using a combination of regular expressions (for lexical structure) and Backus–Naur form (a metalanguage for grammatical structure) to inductively specify syntactic categories (nonterminal) and terminal symbols. [7]
A regular expression (shortened as regex or regexp), [1] sometimes referred to as rational expression, [2] [3] is a sequence of characters that specifies a match pattern in text. Usually such patterns are used by string-searching algorithms for "find" or "find and replace" operations on strings, or for input validation.
The tag name can be any sequence of alphanumeric characters that may be used to indicate how the enclosed block is to be deciphered. For example, #<latex> could indicate the start of a block of LaTeX formatted documentation. Scheme and Racket. The next complete syntactic component (s-expression) can be commented out with #;. ABAP
A representative example in Python is: for an item in some_iterable_object : do_something () do_something_else () Where some_iterable_object is either a data collection that supports implicit iteration (like a list of employee's names), or may be an iterator itself.
The expression 5 > 3 is evaluated as true. The expression 3 > 5 is evaluated as false. 5>=3 and 3<=5 are equivalent Boolean expressions, both of which are evaluated as true. Of course, most Boolean expressions will contain at least one variable (X > 3), and often more (X > Y).
The detailed semantics of "the" ternary operator as well as its syntax differs significantly from language to language. A top level distinction from one language to another is whether the expressions permit side effects (as in most procedural languages) and whether the language provides short-circuit evaluation semantics, whereby only the selected expression is evaluated (most standard ...