Software develop....

My first slides
Designed by:
Iqra Aleem

PROGRAMMING FUNDAMENTALS
Course Code: 104
BSCS: 1st Semester

Software Development Method
What is SDM?
A framework that describes the activities
performed at each stage of a software
development project.

Phases
Specification of needs
Problem analysis
Implementation
Testing and
Verification
Design and
Algorithmic
Representation
Documentation

Specification of Needs
In this phase we actually learn about:
 What the problem is
 What is needed to solve it
 What solution should provide
 If there are constraint and special conditions.

Problem analysis
In this phase we should identify
following:
 Input to the problem, their form and input media
to be used
 Output expected, their form and output media to
be used
 Special constraints and conditions
 Formulas or equations to be used.

Design andAlgorithmic Representation
 An algorithm is a sequence of infinite number of
steps arranged in a specific logic order which,
when executed, produces the solution for a
problem
An algorithm must satisfy these
requirements:
 It may have an input
 It may have an output
 It should not be ambiguous
o Every step in algorithm must be clear as what is supposed to
do

Design andAlgorithmic Representation cont….
 It must be general
 It must be correct and it must solve the problem for which
it is designed
 It must execute and terminate in a finite amount of time
 It must be efficient enough so that it can solve the
intended problem using the recourses currently available
on the computer
 An algorithm can be represented by using:
orPseudo codes Flow chart

Control Structure
 In order to tackle a problem, we need:
 A correct algorithm
 To apply the algorithm at the good moment
 To decide which algorithm to apply
 To know if a certain operation to be repeated
 An algorithm can be described using only three
control structures:
sequence selection reputation

Pseudocodes
 A pseudocode is a semiformal, english-like
language with limited vocabulary that can be
used to design and describe algorithm
 Criteria of a good pseudocode:
 Easy to understand, precise and clear
 Gives correct solution in all cases
 Eventually end

Pseudocodes: the sequence control structure
 A series of steps or statement that are executed in the order they
are written in algorithm
 The beginning and ends of a block of statement can be optionally
marked with keywords begin and end.
o Example:
Begin
Read the birth date from user.
Calculate the difference between birth date and today’s date.
Print the user age.
End

Pseudocodes: The selection control structure
 Defines two courses of action depending on outcome
of a condition. A condition is an expression that is,
when computed, evaluated either true or false.
 The keywords used are if and else.
if condition if age is greater than 23
then-part printf “retire”
Else else
Else-part print “work work
work”
end_if end_if
Format Example

Pseudocodes: The repetition control structure
 The repetition control structure may be like this
example:
 Summing up to 10 numbers
Cumulative sum =0
current num = 1
while current num is less or equal to 10
cumulative sum = cumulative sum + current number
current number = current number + 1
end_while
print the value of cumulative number
o In this algorithm, we have used both sequence and repetition control
structure.

Flow charts
 Flow chart is a graph used to depict or show a step by step
solution using symbols which represent a task.
 The symbols used consists of geometrically shapes that
are connected by flow lines.
 Flow chart is graphical in nature.

Flowchart symbols
Terminal symbol-indicates the beginning and ending
points.
Process symbol-shows an instruction.
Input/output symbol- shows an input/output
operations
Disk storage-indicates input or output from disk storage.
printer output symbol- shows hard copy printer output
selection symbol-shows a selection process for two way
selection.
off page connector-provides continuation of a logical
path of another page.

Flow chart symbols cont….
On page connector-provides continuation of a logical path at another
point of the same page.
flow lines-indicates the logical sequence of execution steps.
 Flow chart –sequence control structure:
statement1
statement2
:

Flow chart-selection control structure
It’s may be in this form
condition
Else- statement Then-statement

Flow chart- repatriation control structure
 It’s may be like this
yes
no
condition
Loop
statement

Implementation
 The process of implementing on algorithm by writing a
computer program using a programming language.
 The output of the program must be solution of problem.
 The program must not do anything that is not supposed to
do
 (think of those may viruses, buffer overflow, trogon horses
etc, that we experience almost daily . All these results
from programs doing more than they were intended to do)

Testing and verification
 Program testing is the process of executing a program
to demonstrate its correctness
 Program verification is the process of ensuring that a
program meets user requirements
 After the program is compiled , we must run the
program and verify it with different inputs before the
program can be released to the public or other users

Documentation
 Contains details produced at all stages of program
development cycle.
 It can be done in two ways:
 Writing comments between your lines of codes
 Creating a separate text file to explain the program
 Important not for only other people to use or modify your
program, but also for you to understand your own program
after a long time

Documentation conti…..
 Documentation is important because:
 You may return to this program in future to use the whole of or part of
it again
 Other programmer or end user will need some information about your
program for reference or maintenance
 You may some day have to modify the program or may discover
errors in your program
 Although documentation is listed as the last stage of
software development method , it is actually an ongoing
process which should be done from very beginning of
software development method.

Software develop....

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