Transcript Computer Programming

COMPUTER
PROGRAMMING
Source: Computing Concepts (the I-series) by Haag, Cummings, and Rhea, McGraw-Hill/Irwin, 2002.
WHAT IS COMPUTER
PROGRAMMING?
 A vocabulary and set of grammatical rules for instructing a
computer to perform specific tasks.
 The term programming language usually
refers to high-level languages, such as BASIC,
C, C++, COBOL, FORTRAN, Java, and Pascal.
 Each language has a unique set of keywords (words that it
understands) and a special syntax for organizing program
instructions.
 Regardless of what language you use, you eventually need
to convert your program into machine language so that the
computer can understand it. There are two ways to do this:
– compile the program
– interpret the program
THE PROGRAMMING PROCESS
1. Analyze the Problem
2. Develop an Algorithm
3. Document the Program
4. Write Code for the Program
5. Run the Program
6. Test the Results
ANALYZE THE PROBLEM
A programmer must know what information will go into the
software, how it will process the information, and what will result.
All software must work with three concepts to be successful:
– Input:
Information that comes from an external source and enters the
software. Input can come from typing on a keyboard, from records in a
database, or from clicking on an image with the mouse
– Processing:
Manages information according to a piece of software’s
logic. Processing is what the software does to the input it receives. This
can be anything from adding a few numbers together to mapping the
earth’s climate.
– Output:
The information software produces after it has processed
input. Output can appear on a computer screen, in a printout, or in
records in a database.
ALGORITHMS
 Algorithms are the steps needed to solve a
problem using pseudocode or flowcharts.
 After creating an algorithm,
programmers check its logic.
 A logic error is a mistake in the
way an algorithm solves a
problem.
 Programmers check their algorithms by
inputting test data and checking the logic
by hand or with a calculator.
PSEUDOCODE
 Pseudocode uses English statements to create an outline of
the necessary steps for a piece of software to operate.
 Programmers call these steps an algorithm. An algorithm is a
set of specific steps that solves a problem or carries out a
task.
 While there is no set of rules for writing pseudocode, it
usually follows rules such as:
– Using simple English
– Putting one command on a line
– Placing any important words in bold
– Starting from the top and work toward
the bottom
– Separating processes with spaces to
form modules
PROGRAM FLOWCHARTS
 Programmers also use program flowcharts
to plot the software’s algorithm.
 A program flowchart is a graphical
depiction of the detailed steps that
software will perform.
 Unlike pseudocode, which
has less structure, in
flowcharts programmers
must use symbols.
CODING
 Coding is when a programmer
translates an algorithm into a
programming language.
TESTING PROGRAMS
 Debugging – the process of finding errors in software code.
 Bugs – are a common name for software errors. When
programmers debug code, they look for syntax, run-time, and
logic errors.
 Syntax errors – mistakes in a software code’s grammar. If
you are supposed to use a semi-colon (;) and you use a colon
(:) instead, you have made a syntax error.
 Run-time errors – mistakes that occur when a programmer
runs the software code.
 Logic errors – mistake made in the way an algorithm solves a
problem.
OBJECT-ORIENTED
PROGRAMMING
 Object-oriented programming (OOP) is any
programming language that uses objects to code
software.
 An object instance is an exact copy of an object in
OOP.
 An event-driven language responds to actions
users perform on the program. It’s an event when
you click on a button, use a pull-down menu, or
scroll down a window.
 In an event-driven language, each event triggers
the program to action.
WEB
PROGRAMMING
 HyperText Markup Language (HTML) is the basic
language for web programming.
 JavaScript – a scripting language that allows you to add
interactivity and other features to a Web page.
 Java Applets – A small piece of software that enables
applications to run on a Web page.
 Dynamic HTML – combines cascading style sheets,
JavaScript, etc., to bring high interactivity to Web sites.
 VBScript – an interpreted scripting language based on
Visual Basic. It is similar to JavaScript but only Microsoft’s
Internet Explorer Web browser can use it.
PROGRAMMING
LANGUAGES
BASIC
Stands for Beginner’s All-purpose Symbolic Instruction Code. Basic was developed in
1964 and is still in use today. Many variations of it exist and it’s on most desktop and
notebook computers. It’s a procedural, interpreted language.
Visual
Basic
Developed by Microsoft, VB uses a graphical interface to develop event-driven Windows
programs. Visual Basic for Applications (VBA) is a subset of VB that allows programmers
to develop macros in the Microsoft Office environment.
COBOL
Stands for Common Business Oriented Language, COBOL is a widely used procedural
language in business applications. It’s primarily used on mainframe computers.
C
C is a compiled procedural program used to develop operating systems and application
software. It is a powerful and efficient program, but it’s difficult to use.
C++
An object-oriented version of C. It’s used for man of the same applications as C as well
as database and Internet programs. You don’t need to know C to learn C++.
FORTRAN
Stands for Formula Translator. FORTRAN is the oldest high-level language still in use.
Scientists and engineers use it to handle complex mathematical and scientific
calculations.
Pascal
Developed in the late 1960s to help students learn structured programming concepts. It’s
named after the 17th-century French mathematician, Blaise Pascal. Turbo Pascal is an
object-oriented version.
Java
A high-level, object-oriented programming language based on C++. Java is optimized for
Web and Internet appliance applications.
SQL
Stands for Structured Query Language. SQL was developed to provide a common
means to work with databases. SQL is a declarative fourth generation language that
assists programmers in deriving the necessary information from databases.