This document introduces different types of programming languages including low-level languages like assembly and machine code that directly manipulate hardware, high-level languages like C# and Python that are easier for humans to read and write, and application-level languages like VBA that manipulate specific programs. It emphasizes good programming style with readability, comments, and modularity through the use of functions and subroutines. Sample code is provided for each type of language.

1. Excel Macros Level 1Preliminaries

2. Programming LanguagesAllows us to express computations that a machine can performCan be used to:Control behaviour of a machineExpress an algorithmCommunicate4/29/2010M. Campbell - 20102p. 9

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5. Low Level LanguagesDesigned to manipulate the computer via:The operating system (i.e. Windows, Linux)The hardwareExamples include:Assembly languageMachine code4/29/2010M. Campbell - 20105

6. Machine Language Samplemem[0]=0x23;mem[1]=0x00;mem[2]=0xa8; mem[3]=0x17; mem[4]=0xa9; mem[5]=0x17; mem[6]=0xaa; 4/29/2010M. Campbell - 20106

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8. High Level LanguagesDesigned to be easy to read and write inUsed to create most applications (i.e. Excel)Examples include:BASICC, C++, C#PascalCOBOLPython4/29/2010M. Campbell - 20108

9. C# Sample// Hello1.cs public class Hello1 { public static void Main() { System.Console.WriteLine("Hello, World!"); } } 4/29/2010M. Campbell - 20109

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11. Application Level LanguagesUsed to manipulate an application program such as Excel, Word, PowerPointExamples include:Excel VBAWord VBAPowerPoint VBA4/29/2010M. Campbell - 201011

12. Excel VBA SampleSub SampleWalkthrough() Dim oCell As Range Dim x As Integer For Each oCell In Selection.CellsoCell.Value = x x = x + 1 NextEnd Sub4/29/2010M. Campbell - 201012

13. Programming StyleTwo important conventions:Make your program readableHave lots and lots of comments4/29/2010M. Campbell - 201013p. 11

14. ReadabilityAim for clarity of code over cleverness4/29/2010M. Campbell - 201014p. 12

15. CommentsPreceded by a 'Aim for comments to describe the programCan write the comments first (i.e. the logic) and then fill in the code afterwards4/29/2010M. Campbell - 201015p. 11

16. ModularityUse code modules to isolate repetitive codeHelps to shorten codeImproves readability of code4/29/2010M. Campbell - 201016p. 14

17. ModularityTwo types of code modules:Functions:Return a value when finishedSubroutines:Do not return a value upon finishingCollectively referred to as procedures4/29/2010M. Campbell - 201017p. 15