Copyright 2003 Scott/Jones Publishing Brief Version of Starting Out with C++, 4th Edition Chapter 1 Introduction to Computers and Programming

Copyright 2003 Scott/Jones Publishing

Brief Version of

Starting Out with C++, 4th Edition

Chapter 1

Introduction to Computers and Programming

Chapter 1 slide 2 4th Ed. Home Page Appendices

Contents

1.3 Programs and Programming Languages

1.4 What Is a Program Made of?

1.5 Input, Processing, and Output

1.6 The Programming Process

1.7 Procedural and Object-Oriented Programming


Software – Programs That Run on a Computer

• Categories of software:

– Operating system:

• programs that manage the computer hardware and the programs that run on them. Ex: Windows, UNIX, Linux

– Application software:

• programs that provide services to the user. Ex: word processing, games, programs to solve specific problems


1.3 Programs and Programming Languages

• Program: a set of instructions to a computer to perform a task

• Programming Language: a language used to write programs


Programs and Programming Languages

• Types of languages:

– Low-level: used for communication with computer hardware directly. Often written in binary machine code (0’s/1’s) directly.

– High-level: closer to human language


Table 1-1Language Description

C A structured, general purpose language developed at Bell Labs. C offers

both high-level and low-level features.

C++ Based on the C language, C++ offers object-oriented features not found in C. Also invented at Bell Laboratories.

Java An object-oriented language invented at Sun Microsystems. Java may be used to develop programs that run over the Internet, in a web browser.

BASIC Beginners All-purpose Symbolic Instruction Code. A general programming language originally designed to be simple enough for beginners to learn.

COBOL Common Business-Oriented Language. A language designed for business applications.

RPG A programming language for business applications used primarily on IBM midrange and mainframe computers.

FORTRAN Formula Translator. A language designed for programming complex mathematical algorithms.

Pascal A structured, general purpose language designed primarily for teaching programming.


From a High-level Program to an Executable File

a) Code the program with a text editor or using an IDE.

b) Run preprocessor to convert source file directives to source code program statements.

c) Run compiler to convert source program statements into machine language instructions.

d) Run linker to connect hardware-specific code to machine instructions, producing an executable file.

- Steps b–d are often performed by a single command or button click.

- Errors detected at any step will prevent execution of following steps.


From a High-level Program to an Executable File

Source Code

Preprocessor

ModifiedSource Code

Compiler

Object Code

Linker

Executable Code


C and C++

• Both languages were developed at Bell Labs

• C was written by Dennis Ritchie in 1972

• C++ was written by Bjarne Stroustrup in the early 1980’s

• C++ extends the C language to permit object-oriented programming


1.4 What Is a Program Made Of?

• Common elements in programming languages:

– Keywords– Programmer-Defined Symbols– Operators– Punctuation– Syntax


Language Elements, Table 1-2Language Element

Description

Keywords Words that have a special meaning. Keywords may only be used for their intended purpose. AKA reserved words.

Programmer-Defined Symbols

Words or names defined by the programmer. They are symbolic names (identifiers) that refer to variables or programming routines.

Operators Operators perform operations on one or more operands. An operand is a piece of data, like a number.

Punctuation Punctuation characters that mark the beginning or ending of a statement, or separate items in a list.

Syntax

Rules that must be followed when construction a program. Syntax dictates how key words and operators may be used, and where punctuation symbols must appear.


Example Program#include <iostream>#include <string>using namespace std;

int main() {

string name;

cout << "What is your name? "; cin >> name;

cout << "Hello there, " << name;

return 0;}


Program 1-1// This program calculates gross pay.

#include <iostream>using namespace std;

int main(){

double hours, rate, pay;

cout << “How many hours did you work? ”;cin >> hours;

cout << “How much do you get paid per hour? ”;cin >> rate;

pay = hours * rate;cout << “You have earned $” << pay << endl;

return 0;}


Program Output

How many hours did you work? 10How much do you get paid per hour? 15

You have earned $150


Key Words

• Also known as reserved words

• Have a special meaning in C++

• Can not be used for another purpose

• Examples in program: – using, namespace, int


Programmer-Defined Symbols( Identifiers )

• Names made up by the programmer

• Not part of the C++ language

• Used to represent various things: – variables (memory locations), functions, etc.

• Example in program: – name, hours, rate, calcPay()


Operators

• Used to perform operations on data

• Many types of operators:Arithmetic: +, -, *, /, %

Assignment: =

• Examples in program: << stream insertion operator

>> stream extraction operator


Punctuation

• Characters that mark the end of a statement, or that separate items in a list

• Examples in program:– ; , ~ () []


Syntax

• The rules of grammar that must be followed when writing a program

• Controls the use of:

– key words

– operators

– programmer-defined symbols

– punctuation


Lines and Statements

cout << "How many hours did you work? ";

cout << "How many hours " << "did you work? ";

There are 2 statements above.• The first statement uses one line• the second statements spans two lines• the semicolon ( ; ) is the statement terminator


Variable Definitions

• Two types of information: – numbers and characters

• Numbers may be integers or floating-point•

• The statement below creates three variables in memory named hours, rate, and pay that each can store a floating-point number

• double hours, rate, pay;



Three steps many programs perform:1) Gather input data:

- from keyboard- from files on disk drives

2) Process the input data

3) Generate output:- send it to the screen- write it to a file



• Outputcout << "Enter your hours and rate " << "separated by a space: ";

• Input:cin >> hours; cin >> rate;

• Processing:pay = hours * rate;

• Outputcout << “You have earned $” << pay;



• The programming process consists of several steps, which include:– Design– Code– Test– Debug– Document



1. Clearly define what the program is to do.Inputs / Processing / Outputs

2. Develop logic using a flowchart or pseudocode.

3. Desk check for logical errors.4. Enter/Edit the code and compile it.5. Correct any errors found during compilation.

Repeat steps 4 and 5 as many times as necessary.


The Programming Process

6. Run the program with test data for input.

7. Correct any errors found while running the program. Repeat steps 4 through 7 as many times as necessary.

8. Validate the results of the program.


1.7 Procedural and Object-Oriented

Programming• Procedural programming: focus is on the

process. Procedures/functions are written to process data.

• Object-Oriented programming: focus is on objects, which contain data and the means to manipulate the data. Messages are sent to objects to perform operations.

Documents

Copyright 2003 Scott/Jones Publishing Brief Version of Starting Out with C++, 4th Edition Chapter 1 Introduction to Computers and Programming