Unit 6 - Software Design and Development LESSON 4 DATA TYPES

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1 Unit 6 - Software Design and Development LESSON 4 DATA TYPES

2 Previously Paradigms Choice of languages Key features of programming languages sequence; selection eg case, if then else; iteration eg repeat until, while.. do; variables eg naming conventions, local and global variables, logical operators; assignment statements; input statements; output statements

3 Variables Task 11 Refer to the programme created for lab04 Create a short presentation to explain some Key features of programming languages Collect code snippets to show: Sequence Selection Iteration Use these code snippets to illustrate what each of these terms means.

4 What is covered in this session Arrays Logical Operators Data types Assignment 1

5 Arrays Used to store a series of related values First value is numbered zero Dim age_0 as integer Dim age_1 as integer Dim age_2 as integer Dim age_3 as integer Dim age_4 as integer Dim age_n as integer Dim age(n-1) as integer A six-element array from age(0) to age(5) We could be here sometime writing this lot out

6 Array declarations VB.net Dim intcalendardays() As Int32 = {31, 28, 31, 30} ' etc Python calendardays = [31,28,31,30,..] Php $calendardays = array(31,28,31,30,.);

7 Logical operators Used by selection statements Boolean logic AND both conditions must be met OR only one condition needs to be met NOT reverses the input, often used in emergency stop routines.

8 Variables and their type All variables have a data type! In vb.net and C# you must declare the variable along with its type. Dim x as int32 Int32 x; Vb.net C#

9 Variables and their type In some languages the type is inferred the first time you assign a value to it. In Python for example 1. $x = $x = abc22 What are the types for these variables?

10 Datatypes in vb.net Type Used for Range of values Boolean True or false True or false Byte Whole numbers 0 to 255 Integer Whole numbers -32,768 to 32,767 Long Very large Whole numbers ~ +/- 2 billion Currency 2 decimal places Single Floating point decimal Up to 7 sig. fig. Double Large numbers with decimal Up to 14 sig.fig Date Date and time Variant Any type of data String Any type of text

11 advantages of having a type 1. Variable size in memory. All variables occupy memory and the space needed is determined by its datatype. 2. Choosing the correct variable type helps to use memory (RAM) more efficiently in terms of space and processing. If wrong can cause system to crash. 3. Choosing the correct variable type is also a type of validation. cannot store a string into a variable where the datatype is integer

12 advantages of having a type 4. In.net languages you cannot change the type of variable at runtime. This is a good thing. 5. Python does allow you to change datatype at runtime. This is bad practice.

13 Assignment 1: submit to Turnitin L3U06A1JohnDoe2017 Prepare a presentation, including speaker notes, to provide guidance to trainees on the typical applications for the major programming paradigms. Provide a brief description of the paradigm. Give examples of the types of program that each paradigm should be used to write. Describe the limitations of each paradigm. Include the following paradigms: Procedural Object-oriented Event-driven

14 Assignment 1: submit to Turnitin L3U06A1JohnDoe2017 Create a table detailing at least three languages used in your company, one of which must be a visual language. Describe at least two factors which could influence the choice of each of these languages to do a specific task; consider the criteria described in the unit content (lesson 2, slide 11) Types of language to include - Procedural Object Orientated Programming Visual Script

15 Assignment 1: submit to Turnitin L3U06A1JohnDoe2017 In a new presentation, explain how sequence, selection and iteration are used when writing programs. Based on your answers (i.e. the languages you used) in Task 2, give an example of each and, if you use any images, reference your images. (Note: You discussed three languages in task 2 and you must provide an example of sequence, selection and iteration for each language).

16 Assignment 1: submit to Turnitin L3U06A1JohnDoe2017 Write a short paragraph (not more than 100 words) describing why it is beneficial to have a variety of data types in programming. In a table, list at least six data types. Use the following columns to explain why different data types are needed in programs and describe the benefits of having a variety of data types available to the programmer: a. data type b. example c. space occupied d. comment

Unit 6 - Software Design and Development LESSON 3 KEY FEATURES

Unit 6 - Software Design and Development LESSON 3 KEY FEATURES Last session 1. Language generations. 2. Reasons why languages are used by organisations. 1. Proprietary or open source. 2. Features and tools.