Python Syntax And Semantics
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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. However, there are some definite differences between the languages. It supports multiple programming paradigms, including structured, object-oriented programming, and functional programming, and boasts a dynamic type system and automatic memory management. Python's syntax is simple and consistent, adhering to the principle that "There should be one— and preferably only one —obvious way to do it." The language incorporates built-in data types and structures, control flow mechanisms, first-class functions, and modules for better code reusability and organization. Python also uses English keywords where other languages use punctuation, contributing to its uncluttered visual layout. The language provides robust error handling thr ...
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Python Example
Python may refer to: Snakes * Pythonidae, a family of nonvenomous snakes found in Africa, Asia, and Australia ** Python (genus), ''Python'' (genus), a genus of Pythonidae found in Africa and Asia * Python (mythology), a mythical serpent Computing * Python (programming language), a widely used high-level programming language * Python, a native code compiler for CMU Common Lisp * Python, the internal project name for the PERQ#PERQ 3, PERQ 3 computer workstation People * Python of Aenus (4th-century BCE), student of Plato * Python (painter) (ca. 360–320 BCE), vase painter in Poseidonia * Python of Byzantium (4th-century BCE), orator, diplomat of Philip II of Macedon * Python of Catana, poet who accompanied Alexander the Great * Python Anghelo (1954–2014), Romanian graphic artist Roller coasters * Python (Efteling), a roller coaster in the Netherlands * Python (Busch Gardens Tampa Bay), a defunct roller coaster * Python (Coney Island, Cincinnati, Ohio), a steel roller coaster Ve ...
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Zen Of Python
The Zen of Python is a collection of 19 Coding conventions, "guiding principles" for writing computer programs that influence the design of the Python (programming language), Python programming language. Python code that aligns with these principles is often referred to as "Pythonic". Software engineer Tim Peters (software engineer), Tim Peters wrote this set of principles and posted it on the Python mailing list in 1999. Peters' list left open a 20th principle "for Guido to fill in", referring to Guido van Rossum, the original author of the Python language. The vacancy for a 20th principle has not been filled. Peters' Zen of Python was included as entry number 20 in the language's official Python Enhancement Proposals and was released into the public domain. It is also included as an Easter egg (software), Easter egg in the Python Interpreter (computing), interpreter, where it can be displayed by entering import this. In May 2020, Barry Warsaw (developer of GNU Mailman) used it ...
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Prettyprint
Pretty-printing (or prettyprinting) is the application of any of various stylistic formatting conventions to text files, such as source code, markup, and similar kinds of content. These formatting conventions may entail adhering to an indentation style, using different color and typeface to highlight syntactic elements of source code, or adjusting size, to make the content easier for people to read, and understand. Pretty-printers for source code are sometimes called code formatters or beautifiers. Pretty-printing mathematics Pretty-printing usually refers to displaying mathematical expressions similar to the way they would be typeset professionally. For example, in computer algebra systems such as Maxima or Mathematica the system may write output like as Some graphing calculators, such as the Casio 9860 series, HP-49/50 series and HP Prime, TI-84 Plus, TI-89, and TI-Nspire, the TI-83 Plus with the PrettyPt add-on, or the TI-84 Plus with the same add-on or the "Mat ...
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Coding Conventions
Coding conventions are a set of guidelines for a specific programming language that recommend programming style, practices, and methods for each aspect of a program written in that language. These conventions usually cover file organization, indentation, comments, declarations, statements, white space, naming conventions, programming practices, programming principles, programming rules of thumb, architectural best practices, etc. These are guidelines for software structural quality. Software programmers are highly recommended to follow these guidelines to help improve the readability of their source code and make software maintenance easier. Coding conventions are only applicable to the human maintainers and peer reviewers of a software project. Conventions may be formalized in a documented set of rules that an entire team or company follows, or may be as informal as the habitual coding practices of an individual. Coding conventions are not enforced by compilers. Sof ...
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ALGOL
ALGOL (; short for "Algorithmic Language") is a family of imperative computer programming languages originally developed in 1958. ALGOL heavily influenced many other languages and was the standard method for algorithm description used by the Association for Computing Machinery (ACM) in textbooks and academic sources for more than thirty years. In the sense that the syntax of most modern languages is "Algol-like", it was arguably more influential than three other high-level programming languages among which it was roughly contemporary: FORTRAN, Lisp, and COBOL. It was designed to avoid some of the perceived problems with FORTRAN and eventually gave rise to many other programming languages, including PL/I, Simula, BCPL, B, Pascal, Ada, and C. ALGOL introduced code blocks and the begin...end pairs for delimiting them. It was also the first language implementing nested function definitions with lexical scope. Moreover, it was the first programming language which gave ...
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Block (programming)
In computer programming, a block or code block or block of code is a lexical structure of source code which is grouped together. Blocks consist of one or more declarations and statements. A programming language that permits the creation of blocks, including blocks nested within other blocks, is called a block-structured programming language. Blocks are fundamental to structured programming, where control structures are formed from blocks. Blocks have two functions: to group statements so that they can be treated as one statement, and to define scopes for names to distinguish them from the same name used elsewhere. In a block-structured programming language, the objects named in outer blocks are visible inside inner blocks, unless they are masked by an object declared with the same name. History Ideas of block structure were developed in the 1950s during the development of the first autocodes, and were formalized in the Algol 58 and Algol 60 reports. Algol 58 introduced ...
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ABC (programming Language)
ABC is an Imperative programming, imperative general-purpose programming language and integrated development environment (IDE) developed at Centrum Wiskunde & Informatica (CWI), in Amsterdam, Netherlands by Leo Geurts, Lambert Meertens, and Steven Pemberton. It is interactive, structured, High-level programming language, high-level, and intended to be used instead of BASIC, Pascal (programming language), Pascal, or AWK. It is intended for teaching or prototyping, but not as a systems-programming language. ABC had a major influence on the design of the language Python (programming language), Python, developed by Guido van Rossum, who formerly worked for several years on the ABC system in the mid-1980s. Features Its designers claim that ABC Computer program, programs are typically around a quarter the size of the equivalent Pascal (programming language), Pascal or C (programming language), C programs, and more readable. Key features include: *Only five basic data types *No requir ...
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Off-side Rule
The off-side rule describes syntax of a computer programming language that defines the bounds of a code block via indentation. The term was coined by Peter Landin, possibly as a pun on the offside law in association football. An off-side rule language is contrasted with a free-form language in which indentation has no syntactic meaning, and indentation is strictly a matter of style. An off-side rule language is also described as having significant indentation. Definition Peter Landin, in his 1966 article " The Next 700 Programming Languages", defined the off-side rule thus: "Any non-whitespace token to the left of the first such token on the previous line is taken to be the start of a new declaration." Example The following is an example of indentation blocks in Python; a popular off-side rule language. In Python, the rule is taken to define the boundaries of statements rather than declarations. def is_even(a: int) -> bool: if a % 2 0: print('Eve ...
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Control Flow
In computer science, control flow (or flow of control) is the order in which individual statements, instructions or function calls of an imperative program are executed or evaluated. The emphasis on explicit control flow distinguishes an ''imperative programming'' language from a ''declarative programming'' language. Within an imperative programming language, a ''control flow statement'' is a statement that results in a choice being made as to which of two or more paths to follow. For non-strict functional languages, functions and language constructs exist to achieve the same result, but they are usually not termed control flow statements. A set of statements is in turn generally structured as a block, which in addition to grouping, also defines a lexical scope. Interrupts and signals are low-level mechanisms that can alter the flow of control in a way similar to a subroutine, but usually occur as a response to some external stimulus or event (that can occur asynchr ...
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Whitespace Character
A whitespace character is a character data element that represents white space when text is rendered for display by a computer. For example, a ''space'' character (, ASCII 32) represents blank space such as a word divider in a Western script. A printable character results in output when rendered, but a whitespace character does not. Instead, whitespace characters define the layout of text to a limited degree, interrupting the normal sequence of rendering characters next to each other. The output of subsequent characters is typically shifted to the right (or to the left for right-to-left script) or to the start of the next line. The effect of multiple sequential whitespace characters is cumulative such that the next printable character is rendered at a location based on the accumulated effect of preceding whitespace characters. The origin of the term ''whitespace'' is rooted in the common practice of rendering text on white paper. Normally, a whitespace character is ''not' ...
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Global Variable
In computer programming, a global variable is a variable with global scope, meaning that it is visible (hence accessible) throughout the program, unless shadowed. The set of all global variables is known as the ''global environment'' or ''global state.'' In compiled languages, global variables are generally static variables, whose extent (lifetime) is the entire runtime of the program, though in interpreted languages (including command-line interpreters), global variables are generally dynamically allocated when declared, since they are not known ahead of time. In some languages, all variables are global, or global by default, while in most modern languages variables have limited scope, generally lexical scope, though global variables are often available by declaring a variable at the top level of the program. In other languages, however, global variables do not exist; these are generally modular programming languages that enforce a module structure, or class-based object-or ...
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Identifier (computer Languages)
In computer programming languages, an identifier is a Lexical analysis#Token, lexical token (also called a symbol, but not to be confused with the symbol (programming), symbol primitive data type) that names the language's entities. Some of the kinds of entities an identifier might denote include Variable (computer science), variables, data types, Label (computer science), labels, subroutines, and Modular programming, modules. Lexical form Which character sequences constitute identifiers depends on the lexical grammar of the language. A common rule is alphanumeric sequences, with underscore also allowed (in some languages, _ is not allowed), and with the condition that it can not begin with a numerical digit (to simplify Lexical analysis, lexing by avoiding confusing with integer literals) – so foo, foo1, foo_bar, _foo are allowed, but 1foo is not – this is the definition used in earlier versions of C (programming language), C and C++, Python (programming language), Python ...
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