Chapter 12
Programming Concepts
and Languages
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Presentation Overview
•
•
•
•
Programming Concepts
Problem-Solving Techniques
The Evolution of Programming Approaches
Programming Development and
Documentation Tools
• Programming Errors
• The Software Development Life Cycle
• Major Programming Languages
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Programming Concepts
What makes up a programming language?
– Program – instructions telling a computer how to
perform tasks
– Programming languages – languages that
communicate with the computer to create programs
– Source code – text files that make up a
programming language
– Four main computer language programming
elements are variables, executable statements,
looping, and decision statements.
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Programming Concepts
High-Level versus Low-Level Languages
– Low-level language (machine code) is a binary
language consisting of 1s and 0s;
runs faster and takes up less disk space.
– High-level language is similar to natural languages,
making it easier to learn and use.
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Programming Concepts
Each
generation
of programs
builds on the
contributions
of the group
of languages
that preceded
it.
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Programming Concepts
Classic Programming Elements
– Variable – data value stored in computer memory
– Executable statement –performs an action and
then proceeds to the next statement in sequence
– Looping – allows a program to return to a
previously executed instruction and repeat it
– Decision statement – point in a program where
different actions may be performed depending on
specific conditions
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Programming
Concepts
Looping allows
a computer
program to
continuously
repeat the same
steps, such as a
program designed
to direct a traffic
light to display
yellow, red, and
green lights at a
consistent rate.
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Programming
Concepts
Using an if-then
statement based
on a particular
action, such as
pushing the
crosswalk button,
a program can
interrupt the
looping pattern,
making the
program more
useful.
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Problem-Solving Techniques
Top-down
design
approach
helps
programmers
break a large
project into
manageable
parts.
Breakdown
process
continues
until there
are no more
steps.
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Problem-Solving Techniques
Problem-Solving Steps
1.
2.
3.
4.
5.
6.
Identify the problem.
Analyze the problem.
Brainstorm solutions and choose the best one.
Write the algorithm.
Prototype the solution.
Implement and test the solution.
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ProblemSolving
Techniques
Step-by-step
pseudocode
algorithm for
changing a
lightbulb.
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The Evolution of Programming
Approaches
Structured Programming
– Creates groups of instructions as independent
elements.
– Structured groups of instructions are built on a
routine, which is a section of a program to handle
a function.
– A routine is broken down into steps to accomplish
the function.
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The Evolution of Programming
Approaches
Modules
– Code modules handle separate components of a
program.
– Each module is a solid portion of a larger structure.
– Modules are reusable, and modularity helps in
tracking down errors.
– A macro is a recording of steps to perform a
repetitive task.
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The Evolution of Programming
Approaches
Object-Oriented Programming
– Object-oriented programming (OOP) defines
each module (object) with definite rules for
interfacing and a protected set of variables.
– Protected variables allow a programmer to
prevent data from being altered during program
execution.
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The Evolution of Programming
Approaches
Rapid Application Development
Rapid application development (RAD) reduces cost
by decreasing time needed to develop a project.
Programmers using RAD follow guidelines
• Use visual development (4GL) tools when possible
• Rapidly prototype new projects
• Approach coding with these priorities
– Use existing code first.
– Buy someone else’s code second.
– Write new code last.
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Programming Development
and Documentation Tools
Compilers and Interpreters
– Compiler – program that translates programming
language source code into machine code
– Interpreter – translates instructions one-by-one as
source code is being executed; identifies errors as
they are encountered, including the line containing
the error
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Programming Development
and Documentation Tools
Debuggers
– Debugger – a software tool that helps programmers
find errors quickly.
– Allows programmers to examine closely what is
happening when a program runs.
– Usually an integral component of compilers and
interpreters.
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Programming Development
and Documentation Tools
Document Tools
– Flowchart – provides a visual diagram of an
algorithm
– CASE tools – help programming team schedule and
coordinate its operations
– Comment – informal message inserted into a
program usually to explain source code to later users
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Programming
Development
and
Documentation
Tools
These symbols
are used in
flowcharts to
represent the
logic of a
program.
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Programming
Development
and
Documentation
Tools
Flowcharts help
programmers
visualize the steps
in a software
program.
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Programming Development and
Documentation Tools
Flowcharts help programmers visualize the steps in a software
program.
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Programming Errors
What programming errors are in programs?
– Syntax errors – typing errors or misunderstanding of
rules of the language
– Logic errors – program instructs computer to
perform an action incorrectly
– Run-time errors – mistakes that occur when an
application is running (crash or infinite loop)
– Style errors – poorly written programming code that
may cause dissatisfaction with program
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The Software Development
Life Cycle
What are the steps in the software development
life
cycle?
The software development life cycle involves planning, designing,
implementing, testing, and release of application software.
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Major Programming Languages
Commonly used programming languages
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Major Programming Languages
Machine Code
– programming language that computers actually read
and interpret
– machine code written in a binary string of 1s and 0s
– difficult to memorize the long binary strings that
comprise the machine code
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Major Programming Languages
Assembly Language
– uses symbols and words to represent elements of
machine code
– must be converted to machine code by a compiler
– runs fastest and uses least memory
– programs are difficult to write and development times
are lengthened
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Major Programming Languages
COBOL
– used chiefly for business applications by large
institutions and companies
– is slow and cumbersome language, but has large body
of existing code and many programmers know the
language
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Major Programming Languages
RPG
– commonly used in business environments
– inefficient, but simplifies coding of database
applications
– is familiar to many programmers
– often used on midrange and mainframe computers
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Major Programming Languages
FORTRAN
– for many years, the language of choice for math,
science, and engineering projects
– still in use today in factories and laboratories
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Major Programming Languages
BASIC
– high-level language that is friendlier and more natural
than COBOL or FORTRAN.
– runs slowly, but faster to develop for programmers.
This sequence of code will print the numbers 1 to 10.
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Major Programming Languages
Visual Basic (VB)
– language of choice for developing software
prototypes or for developing interfaces for Windows
platforms
– quick and easy to develop, but run slowly and is
demanding of RAM and disk space
– supports graphic interfaces
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Major Programming Languages
C
– compromise between high-level and low-level
languages, containing components of BASIC and
assembly language
– not as easy to read as BASIC, but runs considerably
faster and uses less space
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Major Programming Languages
C++
– superset of C; any C program should run in C++.
– added features such as object-oriented programming.
This sequence of code will print the numbers 1 to 10.
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Major Programming Languages
C#
– modern object-oriented language derived from C++
and Java
– combines productivity of Visual Basic with power of
C++
– allows use of features in Microsoft.NET framework,
C, and Microsoft’s Component Object Model (COM)
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Major Programming Languages
Scripting Languages
– interpreted language that is relatively easy to learn and
use
– explains what a computer should do in English-like
terms but not precisely how the computer should do it
– Hypertext Markup Language (HTML), JavaScript,
VBScript, and perl are scripting languages
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Major
Programming
Languages
This sequence
of code directs
a browser to
display buttons
users can click
to change the
background
color within
the Web
browser
window.
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On the Horizon
Based on the information presented in this
chapter and your own experience, what do
you think is on the horizon?
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