1. I Power Higher Computing Software Development Development Languages and Environments

2. Machine Code As we know computers only understand binary numbers. The instructions made up of binary are called machine code. Programs written in machine code run very fast but are difficult for humans to understand. Int 2

3. High Level languages To make it easy for programmers, code can be written in a high level language. High level language describes any language that uses English commands. E.g. Print/Repeat. Because computers only understand Machine code the computer must translate the High Level Language into machine code which slows the computer down. Int 2

4. Text Editors High Level languages can be written in a Text Editor. Text editors (notepad) allow us to: enter the code Edit the code Copy/Paste – Search/Replace Indent the code Some text editors assist us by colouring keywords and predicting the text. Int 2

5. Translators In order for the computer to understand the High level language that we have been programming in we the code must first be translated into machine code. The two translators that we need to know about are: Compilers. Interpreters. Int 2

6. Compilers The whole program (the source code) is translates into machine code at once creating a new file (the object code). The source code can be translated from many different platforms to produce different object files. Once translated the object code can be executed many time without being translated again. This means that the execution of the program will be faster as there is no need to load the translator into RAM. The disadvantage is the object code will not run if there are any syntax errors in the code. Int 2

7. Interpreters The whole program file is translated and executed each line at a time. No object code is created. The translator must be loaded into RAM every time the code is executed making the program slow. The code can be translated on a number of platforms if different translators are used. The interpreter will run part of the code if there are syntax errors in it. Int 2

8. What we will learn Types of Programming Languages. Types of translators. Module Libraries. Int 2

9. Types of Programming Language When Programming it is important to choose a suitable program for the task given. There are several different types of categories that we must know about. Int 2

10. Categories Procedural Languages. Declarative Languages. Event Driven Languages. Scripting Languages. Int 2

11. Procedural languages (imperative languages). Theses are high level languages that use command and key words for instructions. Normally a sequence of instructions with a clear start and end. Higher

12. Procedural Example 10 Print “What is your Name?” 20 Input Name$ 30 Print “Hello “;Name$ 40 End Higher

13. Declarative Languages These are a collection of facts and rules which describe a problem. The user would type in a query and the program will match it with the program and return any missing information it may know. Higher

14. Declarative Example Male (John). Male (Robert). Parent (John,Ruth). Father (X,Y) :- Parent (X,Y), Male (X). Higher

15. Event-Driven Languages These are similar to procedural languages, the difference is the way that they are designed to run. Modules of code are tie to objects or buttons on the screen. The code is only run when the user performs some operation on the screen. E.g. clicking a button or moving the mouse. Higher

16. This code is run only when the display button is pressed Event-Driven Example Private Sub Cmdclear_Click() txtmessage.Text = "" Cmdclear.Enabled = False Cmddisplay.Enabled = True End Sub Private Sub Cmddisplay_Click() txtmessage.Text = "Hello World" Cmddisplay.Enabled = False Cmdclear.Enabled = True End Sub Private Sub Cmdexit_Click() End End Sub Higher

17. Scripting Language These are like a procedural language, in that they use variables etc. The main difference is where these are used. Scripting languages are used to automate or extend the functionality of an application. E.g. VBScript. NOT VB Int 2

18. Scripting Language These scripts may create an applet (Small Application) or a macro (A stored list of actions recorded from users actions). Run Example. Int 2

19. Module Libraries In order to save programmers time small pieces of code that do simple tasks are saved separately. These pieces of code are called Modules. Modules are stored together in Module Libraries. Advantages are: You do not have to rewrite code that has been written before. The code has already been tested for errors. These modules should be well documented. Int 2