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Contents. Python syntax and semantics. The syntax of the Python programming language is the set of rules that defines how a Python program will be written and interpreted (by both the runtime system and by human readers). The Python language has many similarities to Perl, C, and Java.
Syntax definition. [edit] 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 ...
Python uses the + operator for string concatenation. Python uses the * operator for duplicating a string a specified number of times. The @ infix operator. It is intended to be used by libraries such as NumPy for matrix multiplication. [106] [107] The syntax :=, called the "walrus operator", was introduced in Python 3.8. It assigns values to ...
Lexical tokenization is the conversion of a raw text into (semantically or syntactically) meaningful lexical tokens, belonging to categories defined by a "lexer" program, such as identifiers, operators, grouping symbols, and data types. The resulting tokens are then passed on to some other form of processing.
A string literal or anonymous string is a literal for a string value in the source code of a computer program. Modern programming languages commonly use a quoted sequence of characters, formally "bracketed delimiters", as in x = "foo", where , "foo" is a string literal with value foo. Methods such as escape sequences can be used to avoid the ...
The strings over an alphabet, with the concatenation operation, form an associative algebraic structure with identity element the null string—a free monoid. Sets of strings with concatenation and alternation form a semiring, with concatenation (*) distributing over alternation (+); 0 is the empty set and 1 the set consisting of just the null ...
A primary purpose of strings is to store human-readable text, like words and sentences. Strings are used to communicate information from a computer program to the user of the program. [ 2 ] A program may also accept string input from its user. Further, strings may store data expressed as characters yet not intended for human reading.
PHP generally follows C syntax, with exceptions and enhancements for its main use in web development, which makes heavy use of string manipulation. PHP variables must be prefixed by " $ ". This allows PHP to perform string interpolation in double quoted strings, where backslash is supported as an escape character.