Generate the answer for a given question. The question requires common knowledge of English. Make sure that the answer is in detail, long, consistent with the context, and requires general knowledge of English. To be less repetitive, please vary your language for each question. Give a proper explanation to answer, and if necessary, provide the definition of various terms. And conclude your answer if it's long. If you have used other resources (e.g., Merriam Webster's.) to answer the question, include citations in your answer. You don't need to paraphrase the context of your resources, but make sure that your answer is consistent and complete.

I often read the expression 'would of' used instead of 'would have'. Each time I read it I get annoyed so I googled it and found out -as I expected- that it is an incorrect way to say 'would have'. Now, there are a lot of brilliant slang words/expressions, so my question is, why do people use this one? It's so annoying to read, stupid and clearly wrong, it is pointless, why did they come up with this expression? Edit: I don't think my question is a duplicate as I didn't ask how can somebody use it (since I know it's incorrect and I know that I can use it with commas giving it a different meaning) but I asked why and how people came up with this expression.
Correction: what annoys you is people writing 'would of' when they are saying /wdv/, which is the standard pronunciation of the contraction would've. The vowel of the preposition 'of' is almost always reduced in actual speech, yielding /v/. Thus 'would've' and 'would of' are homophones. So no surprise that some people spell it that way, even though it makes no grammatical sense. Would've can be even further reduced to /wd/, which some people spell woulda as a kind of phonetic eye dialect to represent actual speech or set an informal tone. The same goes for the modals, shoulda, coulda, musta. Spelling as it sounds can yield amusing results: Along the way the details of his past are sordid out and he realizes that what he once thought about his parents isn't the truth at all. Amazon.com Review. A speaker of British English, of course, would never write sorted in this manner, but with an American flapped t, it's a perfect fit.

In computer programming, when you append a 'string' to another, you add it to the end of the former string. E.g. String string1 = 'abcd'; String string2 = 'efgh'; Appending the two strings would give 'abcdefgh' But what if I wanted to add string2 before string1 to have the result: 'efghabcd' What would be a good name for that that reverse operation? What is the opposite of 'append'?.
Prepend: (computing, linguistics, transitive) To attach (an expression, phrase, etc.) to another, as a prefix.

I'm describing what an opiate addict looks like before recovery. Instead of saying 'he looked like a vampire,' I'd like to say something like 'he looked [vampiric].' I actually just found out vampiric was a word, but I want something that sounds better (more colloquial/natural, I suppose) and covers a variety of traits (pale, emaciated, sickly, etc). Why I don't just use 'vampiric': As @chepner commented: I think the idea is to find a word that isn't so 'circular', and doesn't refer explicitly to vampires or require knowledge of vampires in context. If someone were to ask 'What does a vampire look like?', then 'It looks vampiric/vampirish' wouldn't be terribly helpful. I don't want to explicitly refer to drug addicts as vampires. I just want to capture those traits in the best way.

I'd suggest cadaverous. It incorporates many facets of what I believe you're trying to convey: a corpse-like appearance, including pallid and underweight. From Merriam-Webster.com: 1a : of or relating to a corpse b : suggestive of corpses or tombs 2a : PALLID, LIVID b : GAUNT, EMACIATED grossly underweight