Language Types

What is a computer program?

Programming: Intro

Do you wish you could change some of your software to work just the way you want it to? Do you sometimes think "I could do better than THIS!" when your software crashes? Well, maybe you can!! It will take some work, of course.

What you'd have to learn is how to program your computer. While I can't teach you how to do that in this series of lessons (Breathe a sigh of relief now!), you can learn a little about what programming is all about.

Simply put, a computer program is a set of detailed directions telling the computer exactly what to do, one step at a time. A program can be as short as one line of code, or as long as several millions lines of code. (We'll hope those long ones do a lot of different and complex things!)

Programming has changed a lot since the first computers were created. The original programs were very simple and straight forward compared to today's elaborate databases, word processors, schedulers, and action games.

Different computer languages have been created with which to write these increasingly complex computer programs. They can be categorized based on how close to normal speech they are, and thus how far from the computer's internal language.

Machine Languages	The language of the CPU (The central processing unit of the computer, which is the part that does the "thinking"). The lowest level language. Composed of 0's and 1's
Assembly Languages	Abbreviations for machine language
High-Level Languages	Use program statements - words and algebra-type expressions. Developed in the 50's and 60's. After a program is written in one of the high-level languages, it must be either compiled or interpreted. A compiler program rewrites the program into machine language that the CPU can understand. This is done all at once and the program is saved in this new form. A compiled program is generally considerably larger than the original. An interpreter program translates the program statements into machine language one line at a time as the program is running. An interpreted program will be smaller than a compiled one but will take longer to execute.
4th Generation Languages	= 4GL. Very high-level languages. These are results oriented and include database query languages like SQL. There are fewer options for programmers, but the programs are much easier to write than in lower level languages. These too must be compiled or interpreted.
Natural Languages	5th Generation Languages. We don't really have any programming languages yet that use natural language. In such a language you would write statements that look like normal sentences. For example, instead of odd-looking code you would write "Who are the salesmen with sales over $20,000 last month?"

Дата добавления: 2014-12-23