Misc Flashcards
What is a global variable?
— A global variable is one which can be used anywhere in a program
What is a local variable?
— A local variable is one which is defined and can only be used within one part of a program (usually a function or procedure)
Give three reasons why a modular approach to coding is a good idea
— It allows the task of coding to be split between a team of people
— it allows code to be reused (thus shortening the amount of code and thus the time needed to produce it)
— it is easier to maintain as the code is in one place and reused not repeated throughout the program
What is a module?
— A block of code that is reused
What is a procedure?
— A module of code that may or may not take parameters but which does not return a value
— The procedure should carry out one task or action that is clearly indicated by its name
What is a function?
— A module of code that may or may not take parameters and which returns a value. The function should carry out one task or action that is clearly indicated by its name
Stack vs Heap
Stack
— neue Daten immer nur oben drauf gelegt werden können => LIFO
— kann, bedingt durch seine Struktur, sehr effizient verwaltet werden, weshalb Stack-Operationen sehr schnell sind
— jeder Thread eines Programmes erhält für den Stack einen eigenen Speicherbereich mit fixer Größe zugewiesen
Darauf werden Informationen zum Programmablauf (z.B. Funktionsparameter) und lokale Variablen gespeichert
— the stack grows and shrinks as functions push and pop local variables
— there is no need to manage the memory yourself, variables are allocated and freed automatically
— the stack has size limits
— stack variables only exist while the function that created them, is running
— very fast access
Heap
— eine zumeist auf Bäumen basierende abstrakte Datenstruktur
— variables can be accessed globally
— no limit on memory size
— (relatively) slower access
— no guaranteed efficient use of space, memory may become fragmented over time as blocks of memory are allocated, then freed
— you must manage memory (you’re in charge of allocating and freeing variables)
— variables can be resized using realloc()
Declarative vs Programmatic UI
Declarative UI
— You say what you want without having to say how to do it
— You do not have to specify the exact steps to get the result
— You just set the command or order, and let it be up to the system how to complete that order
— For example, SQL is more declarative than procedural, because the queries don’t specify steps to produce the result
— You adapt a markup language like HTML or XML, possibly in combination with a layout language like CSS, to define the identity and basic placement of widgets and controls
— You traverse your declared UI using a real programming language like Javascript in order to add functionality and advanced UI features
Programmatic UI
— You define the whole process and provide the steps how to do it
— You create and lay-out the elements of the UI directly in a programming language
— While you may still achieve separation of concerns by delegating UI creation and layout to a dedicated “View” object, all actions necessary to construct the UI are programmatically guided instead of declaratively specified
— All older UIs used this approach, and it is commonly used today to construct UIs for a vast variety of desktop frameworks and can also be used to manipulate the web DOM
What makes Python special?
— It is an interpreted, object-oriented, high-level programming language with dynamic semantics
Functional vs Procedural Programming
— Functional programming focuses on expressions
— Procedural programming focuses on statements
— In computer science, functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids state and mutable data
— It emphasizes the application of functions, in contrast with the procedural programming style that emphasizes changes in state
