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lihaoquan
12,045 PointsDeclarative vs Imperative vs Procedural programming.
Can anyone explain what these 3 types of programming do? Why and when to use them?
2 Answers
Marcus Parsons
15,719 PointsHey Li Hao Quan,
From my understanding, declarative and imperative are two contrasting programming paradigms.
Declarative programming (also known as functional programming) languages do not attempt to control the flow of a program; they establish desired results i.e. specifying what they want to happen but not how it should happen. HTML is an example of declarative programming because it does not attempt to control the flow of a program; it simply states what it would like to appear but not how it is done.
Imperative programming languages, on the other hand, do attempt to control the flow of a program; they establish commands that will tell the compiler how they wish the code to run but not explicitly what they want to happen.
Procedural programming is a subset of imperative programming where programs are built off of procedures. Pretty much all languages in use today are procedural languages. Object oriented programming languages, such as Java, JavaScript, PHP, etc. etc., are procedural programming languages. A good list of procedural languages exists here: http://en.wikipedia.org/wiki/Category:Procedural_programming_languages
Some more reading: https://msdn.microsoft.com/en-us/library/bb669144.aspx
I hope this helps =]
ellie adam
26,377 PointsHi There,
Declarative describe a result and get it via a black box. Examples: yacc Treetop SQL Regular Expressions lex XSLT markup, troff, CSS, VHDL
Procedural describe the algorithm and process steps, at various degrees of abstraction.
C, most legacy languages PHP, mostly in some sense all major languages
Object Oriented
Tends to be in the procedural category, typically refers to languages that exhibit a hierarchy of types that inherit both methods and state from base types to derived types, but also kind of includes prototype-based languages like JavaScript. Somewhat a separate dimension from the other categories here.
Imperative Programming It is what most professional programmers use in their day-to-day jobs. It's the name given to languages like C, C++, Java, COBOL, etc. In imperative programming, you tell the computer what to do. "Computer, add x and y," or "Computer, slap a dialog box onto the screen." And (usually) the computer goes and does it. This is where most of us spend our lives, in looping structures and if-then-else statements and the like.
http://en.wikipedia.org/wiki/Comparison_of_programming_paradigms
I hope this help :)
lihaoquan
12,045 Pointslihaoquan
12,045 PointsAm I right to say that Declarative programming just "DELCARES" the desired result, and then have the imperative programs work it out? E.g HTML is declarative programming, it declares how the end result will look like, then, an IMPERATIVE program e.g ( HTML interpreter ) works out how to run the code in order to give the Declarative HTML its desired appearance. Do they work together like this?
Marcus Parsons
15,719 PointsMarcus Parsons
15,719 PointsFrom my understanding, HTML is declarative, but you wouldn't count the interpreter as being declarative or imperative because we don't have any interaction with it. CSS and JavaScript would be imperative because they control the flow of the document. I may be wrong, but this has been my understanding of these two concepts.