Lecture Slide 2 Understand Program Artifacts

7/28/2019 Lecture Slide 2 Understand Program Artifacts

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@2011 AITI-KACE All Rights Reserved - Fundamentals of Programming 1

Session 2Understanding the artefact of a

Computer programming


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objective

Understand basic data types

Understand variables

Statement

Understand value assignment

How to execute a program

Compilation

interpretation

Modularization

Scope of variables


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Basic Data types

What is a data type:

Is an internal code used by a computer to keeptrack of data it process.

Mostprogramming languages and databasesystems require the programmer to declare a datatype for any data object.

Note: data types normally differ from one

programming language to another.

Note: programming language = programming technology


4/12@2011 AITI-KACE All Rights Reserved - Fundamentals of Programming 4

Basic Data types

Integer : In more common parlance, whole

number; a number that has no fractional part. Examples are : short, int, long, byte

floating-point : A number with a decimal point.For example, 3 is an integer, but 3.5 is afloating-point number.

Examples are : float, double

character (text ): Readable text


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Examples of data types

Note: Every programming technology support a set of these basic data types!


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Variable

A symbolor name that stands for a value.

Two types of variables:

Dynamic variable

Static variable

Properties Naming

be mindful of keywords and special character to use

Length

number of characters Data type

for most compiled programming languages


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Statement

In programming, a statement is a line of code that

is valid in a particular programming technology. Types of statements

instructional statement

comment in a particular programming language

adding of libraries

Properties

termination of statement

syntax

Example: (how to comment in some technologies) HTML :

VB : ' comment

Java: /* */


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Assignment statement

The assignment operator is used to assign a

value or an object to a variable. Example 1:

int age = 18; Once 18 has been assigned to age, unless another value is

assigned to age in subsequent statements whenever age will becalled 18 will be used.

Example 2:

double salary = 800.50; salary = 950.67;

Question: What is the values now assigned to salary?


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How to execute a program

Two types of programming technologies

compiled programming technologies The source code must be compiled first with a compiler

The resulting code is then executed

Examples: C , C++, Java, etc...

scripting programming technologies

An interpreter is used to interpret the source

Examples: Javascript, Ruby, Python, etc...


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Modularity

The modularity is a concept use in software

design to break down a complex problem intosmaller units normally called modules.

Characteristics

each module has a name

module name must be mnemonic

each module accomplishes a task

can be reuse

can accept inputs in the form of arguments

Note: Other names used in place of modules are method and function


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Example 1 - Modularity

Determining an employee's pay based on hours

worked and pay rate while using somecompany standard values for overtime.

Employee_Pay

M1.[Get_Employee_Pay_Values]

M2.[Calculate_Net_Pay]DISPLAY netPay

END

M1.Get_Employee_Pay_Values

Get_Hours_Worked

Get_Rate_of_Pay

RETURN

M2. Calculate_Net_Pay

M2.1[Calculate_Gross_Pay]

M2.2[Calculate_Total_Deductions]

netPay = grossPay - deductions

RETURN

M2.1 Calculate_Gross_Pay

M2.1.1[Calculate Regular Pay]

M2.1.2[Calculate Overtime Pay]

grossPay = regularPay + overtimePay

RETURN


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Variable scope vs Modularity

If you define a scope with a

module, function or method

variable(s) declared within a module is limited onlyto the unit.

If a variable created independent of a module

Is called global variable Any module can used it

Note: any module can change its value.

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Lecture Slide 2 Understand Program Artifacts