Identify object-oriented programming languages

A computer program is a series of instructionsthat direct a computer to perform specific tasks.

A programming language is a set of words, symbols, and codes that enable a programmer to instruct the computer to perform a set of tasks.

Programming languages are either low-level or high-level.

Computer Programs

Low-level Programming Languages

Machine Language - a first generation computer language

Assembly Language – a second generation computer language

Machine language uses a series of binary digits (1s and 0s), or combinations of numbers and letters that represent binary digits, and is the only language a computer directly understands.

Machine Language(First Generation Language)

00090

000090 50E0 30B2   010B4

000094 1B44

000096 1B55

000098 F273 30D6 2C81 010D8 00C83

00009A 4F50 30D6 010D8

0000A0 F275 30D6 2C7B 010D8 00C7D

0000A4 4F70 30D6 010D8

0000AE 5070 304A 0104C

0000B2 1C47

0000B4 5050 304E 01050

0000B8 58E0 30B2 010B4

0000BC 07FE

Assembly language uses symbolic instruction codes. Symbolic instruction codes are meaningful abbreviations & codes in which “A” might stand for addition, “C” might stand for compare, or “M” might stand for multiply. Assembly languages also use symbolic addresses to identify storage locations. For example, RATE might refer to a storage location that contains the pay rate being used in the program. This language is slightly more user friendly than machine language.

Assembly Language(Second Generation Language)

CALCPAY EQU *

ST 14,SAVERTPY

SR 4.4

SR 7.7

SR 5.5

PACK DOUBLE,RTHRSIN

CVB 4.DOUBLE

ST 7.RATE

High-Level Languages(Procedural Programming Languages)

With a procedural language, or third-generation language (3GL), programmers write instructions using code that is very similar to the English language, which simplifies the program development process. For example, ADD stands for addition and PRINT means to print. Arithmetic operations are represented by + for addition, - for subtraction, / for division, and * for multiplication.

* COMPUTE REGULAR TIME PAY

MULTIPLY REGULAR-TIME HOURS BY HOUR-RATE

GIVING REGULAR-TIME-PAY

* COMPUTER OVERTIME PAYIF OVERTIME-HOURS >0

COMPUTER OVERTIME-PAY = OVERTIME-HOURS * 1.5 * HOUR RATE

ELSE

MOVE 0 TO OVERTIME PAY

Popular Standard procedural languages are:

BASIC—a simple, interactive problem-solving language

COBOL—a language designed for business applications

C—a powerful language that requires professional programming skills

High-Level Languages(Procedural Programming Languages)

Below is an example of code written in BASIC:

High-Level Languages(BASIC)

Sample 1: Unstructured original BASIC (Applesoft BASIC) Sample 2: Modern Structured BASIC (e.g. QBASIC)

An example of code written in COBOL.

COBOL stands for Common Business Oriented Language

High-Level Languages(COBOL)

Below is an example of code written in “C”:

High-Level Languages(C)

/* Computer Regular Time Pay */

rt_pay – rt_hrs * pay_rate;

/* Computer Overtime Pay */

if (ot_hrs > 0)

ot_pay – ot_hrs * 1.5 * pay_rate;

else

ot_pay = 0;

/* Compute Gross Pay */

Gross – rt_pay * ot_pay;

/* Print Gross Pay */

Printf(“The gross pay is %d\n”. gross):

A tcompiler or an interpreter ranslates the 3GL source program into a machine language object code that a computer can execute.

An interpreted program runs each line of code individually and translates it into machine language while it is executing the program.

A compiled program is run through a compilation process that converts the entire program from the source code into machine code. Compiled programs run much faster than interpreted programs and are usually identified by the filename extension of .exe.

Compiling or Interpreting Computer Code

Visual programming languages are sometimes called fifth-generation languages (5GL) and provide a visual or graphical interface, called a visual programming environment (VPE) for creating source code.

Visual Programming

Visual programming languages are often used in a rapid application development (RAD) environment. RAD allows programmers to implement a program in segments and use pre-built components which simplify program development.

Visual ProgrammingRapid Application Development (RAD)

An example of RAD would be the icons shown on the above desktop and folder. The icon of the diskdrive representing the computer drives is used in several places – but the same routine is used to create all of them.

Visual programming languages include:

Visual Basic .NET 2003 Visual C++ .NET 2003 Visual C# .NET 2003 Delphi PowerBuilder

Visual Programming

This is an example of a Visual Basic 6.0 environment used to create a program in Visual Basic.

Characteristics of Object-Oriented Programming Languages

Programmers use an object-oriented programming (OOP) language to implement object-oriented design.

An object is an item that can contain both data and the procedures that read or manipulate the data.

A major benefit of OOP is its ability to reuse and modify existing objects, which allows programmers to create applications faster.

OOP languages include C++, which is an object-oriented extension of the C programming language, and Java, which is similar to C++ but uses a just-in-time (JIT) compiler to convert its source code into machine code.

On the right is the HTML code that produced the webpage shown on the left. Examine the code and see if you can determine what some of it does.See if you can explain what the code in red does.

Web Page Written in HTML

<html><Head><center><Title>DogieO's Homepage</title><br></head><body bgcolor="#FFFFFF" text="#OOOOOO">

<h1>DoggieO's Home Page</h1><br><image src="doggieo.gif"><br>Hello, my name is DoggieO. I enjoy all aspects of life, especially chasing other animals.<br> I am a freshman at Cannine High School where I am on the Fetch Team.<br> Below are my favoriate links.<br><br><a href="http://www.Petsmart.com">Petsmart where I get my food and toys.</a><br>

<a href="http://www.google.com">Google Search Engine where I get all my information.</a><br><br></center></body></html>

On the right is the Java code that makes the buttons on the left page change color. When the user “mouse-overs” the button, it switches the graphic which represents the button so that the button appears to change colors or “light up” showing it is active. Below are the two buttons that switch in and out of the page as a result of the Java script code below.

Web Page Written in Java

<title>Pop Activities Page</title>

script LANGUAGE="JavaScript"><!--

if (navigator.userAgent.indexOf("Mozilla") != -1){ if (parseInt(navigator.appVersion) > 2) BrowserOK = 1; else BrowserOK = 0;}function highlight(img) { if (BrowserOK == 0) return; document[img].src = img + "G.jpg";}function unhighlight(img) { if (BrowserOK == 0) return; document[img].src = img + "S.JPG";}// -->

</script>

As you can see, we have many languages. Below are just a few. Languages are improved upon or new languages are developed as we find new applications and uses for computers.

Although we have many languages, they all share common elements; so it is easy to learn and program in other languages once you are exposed to writing code for one program language.