2. Information Systems
System
A collection of pieces working together to achieve a common
goal
An information system includes
Data, People, Procedure, Hardware/Software
System Development Life Cycle (SDLC)
An organized process (or set of steps) used to develop systems
in an orderly fashion
3. PROGRAM, PROGRAMMING & PROGRAMMER
• Program:
A set of step-by-step instructions that directs a
computer to perform a specific task and to produce the
required results.
• Programming:
Programming is a process of designing/ creating a
program.
• Programmer:
Programmer is a person who writes the program.
4. Problem Opportunity
Identification
Analysis
Design
Development &
Documentation
Testing & Installation
Maintenance & Evaluation
One step is completed before proceeding to the next
System Development Life Cycle
5. The Life Cycle of a Program
Programming is the process of translating a
task into a series of commands a computer will
use to perform that task.
Programming involves:
Identifying the parts of a task the computer can perform.
Describing tasks in a specific and complete manner
Translating the tasks into a language that is understood by
the computer’s CPU.
6. Program Development Life Cycle
Step • Analyze Problem
1
Step • Design Programs
2
Step • Code Programs
3
Step • Debugging
4
Step • Formalize Solution
5
Step • Maintain Programs
6
7. Step 1 : Analyze Problem
The problem statement is:
The starting point of programming
A description of tasks the program is to accomplish
How the program will execute the tasks
Created through interaction between the developer and the
user
The program statement includes error handling
and a testing plan
8. What is involved in analyzing problem?
• Review program specifications
package
• Meet with systems analyst and users
• Identify each program’s input, output,
and processing components
9. Step 2 : Design Program
Develop an algorithm:
A set of specific, sequential steps that describe what the
computer program must do
Complex algorithms include decision points:
Binary (yes/no)
Loop (repeating actions)
Visual tools used to track algorithm and decision points
include:
Flowchart
Pseudo Code
Top Down design
Object Oriented Analysis
10. Step 3 : Coding
Coding is translating an algorithm into a
programming language
Generations of programming languages
11. What is involved in coding programs?
Two Steps
Translating Entering
solution algorithm programming
into a programming language code into
language the computer
12. Step 4 : Debugging
Running a program to find errors is known as
debugging
Sample inputs are used to determine runtime
(logic) errors
Debugger: Tool that helps programmers locate
runtime errors
13. What is involved in testing programs?
Goal is to ensure program runs correctly and is
error free
Three types of errors
Syntax
Logic
Run time
14. Syntax Errors
• Refers to an error in the syntax of a sequence of characters or
tokens that is intended to be written in a particular programming
language.
• For compiled languages syntax errors occur strictly at compile-
time. A program will not compile until all syntax errors are
corrected.
• For interpreted languages however syntax errors cannot be
detected until runtime and it is not necessarily simple to
differentiate a syntax error from a semantic error.
• A syntax error may also occur when an invalid equation is
entered into a calculator. This can be caused, for instance, by
opening brackets without closing them, or less commonly,
entering several decimal points in one number.
15. Logic Errors
• A logic error (sometimes called a semantic error) is a bug in a
program that causes it to operate incorrectly, but not to
terminate abnormally (or crash).
• A logic error produces unintended or undesired output or other
behaviour, although it may not immediately be recognized as
such.
• Logic errors occur in both compiled and interpreted languages.
• Unlike a program with a syntax error, a program with a logic
error is a valid program in the language, though it does not
behave as intended.
16. Run time Errors
• A runtime error is a computer error that appears in the form of a
message box consisting of a particular code along with its
corresponding definitions.
• Usually, a user will notice that the computer becomes
noticeably slow before a runtime error appears.
• After the runtime error message has been displayed and
closed, the software that shows this error would normally close
or freeze. In some cases, the operating system will reboot.
• A wide variety of errors cause these problems. These include:
• conflicts between the TSR (Terminate and Stay Resident Program)
• currently running applications
• software issues
• memory problems
• and harmful applications such as computer viruses
17. Step 5 : Formalize Solution
What is involved in formalizing solution?
Programmer performs two activities:
• Reviews program code
• Reviews documentation
18. Step 6 : Maintain Programs
What is involved in maintaining programs?
Identify
errors Identify
enhancements
Involves modifying existing programs
to improve their functionality
19. Programming language
Set of words, symbols, and codes that enables a programmer
to communicate a solution algorithm to the computer
Program Development Tool
User-friendly software products designed to assist in the
creation of information system solutions