Download (SDLC) involves Six Stages: (a) Analysis (b)

LECTURE – 4 TO 6
The System Development Life Cycle (SDLC) involves Six Stages:
(a) Analysis
(b) Design
(c)Coding i.e, Programming
(d) Testing
(e)Launch
(f) Evaluation
The Analysis involves study of the existing system and the
problem identification (which is beyond the scope of our course). In
our present course we will be doing the stage two, three and four of
the SDLC.
The Design phase involves two steps :
(i)
(ii)
Development of an Algorithm – which is nothing but
defining the Process (Method).
Development of Flow Chart – which is nothing but Pictorial
representation of the Process Flow. We also call it
Process Flow Diagram.
In our syllabus we give the problem and our aim is to develop
Algorithm and Flowchart for the given problem:
Before going further, we shall now understand the symbols used :
+ : Addition
-
: Subtraction
*
: Multiply (You should not use X)
/
: Divide
%
: Modulo Division
^
: Exponent (e2 to be written as e ^2 and so on)
&
: Amberson And / Logic And
=
: Assignment operator (say x = 5 etc)
The System evaluates Left to Right with order of Precedence as
under:
(1)
Brackets
(2)
Exponents
(3)
Modulo Division
(4)
Divide and Multiply
(5)
Addition and Subtraction
Example : Evaluate : 2 +3 * (5-2) * 2^3/12
Sol: First Bracket is evaluated
= 2 + 3 * 3 * 2 ^ 3 / 12
Now exponent is evaluated
= 2 + 3 * 3 * 8 / 12
Now Multiply and Divide are evaluated
= 2 + 72/12
Now Add symbol is evaluated.
=2+6
=8
(Note : Assignment and Homework Problems will be sent separately)
Flow chart symbols:
Start / End
:
Input / Output
:
Assignment / Calculations
:
Decision (Yes / No – Logical T/F)
:
Note : The following Algorithms and Flowchart will be used for
Design of Forms, Development of Programs etc.
Qn1: Develop and Algorithm and draw flow chart to find the
average of three given numbers A, B, C.
Sol: Here the user first has to decide the variables required.
1. The developer has to declare three variables for input say A, B and
C.
2. Then there should be a variable for storing the Answer say Avg.
3. The formula one should know, ie., Avg = ∑ Xn /
general formula where n is the number of items.
n (this is
Algorithm:
Step1: Input A, B, C, Avg
Step2: Find Avg = (A+B+C)/3
Flow Chart:
START
Step3: Write Avg
Step4: Stop - Close the Program
INPUT A, B,C,
AVG
AVG = (A+B+C)/3
WRITE AVG
STOP
Qn : 2 To find the Area of a Triangle given three sides A, B, C
using the Heron’s Formula:
Area = (S * (S-A) * (S-B) * (S-C) ) ^ (1/2)
Where S = (A+B+C)/2 i.e., Semi Perimeter
Solution:
Algorithm:
Step1: Input A, B, C, S, Area
Step2: Find S = (A+B+C)/2
Flow Chart:
START
Step3: Find Area using the Formula
Area = (S*(S-A)*(S-B)*(S-C))^(1/2)
Step4: Write Area
Step 5: Stop - Close the Program
INPUT A, B,C,
AVG
S = (A+B+C)/2
Area = (S*(S-A)*(S-B)*(S-C))^(1/2)
WRITE Area
STOP
Qn 3: To find the greatest of three numbers A, B, C:
Solution:
Algorithm:
Step1: Input A, B, C, Ans
Step2: If A> B Ans = A else Ans=B
Flow Chart:
Step3: If C > Ans, Ans = C
Step4: Write Ans
Step 5: Stop - Close the Program
START
INPUT A, B,C
A >C
A IS
BIG
A > B
B > C
B IS BIG
C IS BIG
STOP
HOME WORK
1. Develop an Algorithm and Flowchart to find the Simple Interest (I)
for given Principal (P), Rate of Interest (R), Time (T) using the
formula I = (P * R * T) / 100
2. Develop and Alogrithm and Flowchart to find the Amount
Payable on Principal (P), Rate of Interest (R), Time (n) where
interest is compounded annually using the formula
A = P + (1 +r/100)^n and also the Interest using the formula
I=A–P
3. Develop an Algorithm and Flow chart to find the smallest of three
numbers A, B, C
4.
To find the Surface Area of a Cuboid using the formula
S = 2 * (l*b + b * h + l * h)
 ***
(Algorithm and Flowchart for control structures and Looping will
be sent)