Lecture_01-Problem_Solving[1]||ProgrammingFundamental.ppt

Programming
Fundamentals
Lecture 1: Problem Analysis
By: Ms. Humaira Anwer

Agenda
 Problem solving steps
 Algorithm
 Flowcharts
 Pseudocode
 Computer Program
 Exercises

ALGORITHMS AND FLOWCHARTS
 A typical programming task can be divided into
two phases:
 Problem solving phase
 produce an ordered sequence of steps that describe
solution of problem
 this sequence of steps is called an algorithm
 Implementation phase
 implement the program in some programming
language

Steps in Problem Solving
 First produce a general algorithm (one can use
pseudocode)
 Refine the algorithm successively to get step by
step detailed algorithm that is very close to a
computer language.
 Pseudocode is an artificial and informal
language that helps programmers develop
algorithms. Pseudocode is very similar to
everyday English.

Computer Program
 A computer program is a set of instructions
for the computer to perform a certain task.
 Written in computer language
 These programs are easy to read and
understand by programmers but not
understandable by the computer.
 The computer only understands its own
machine language.
 It consists of binary which is ones and zeros.

Pseudocode & Algorithm
 Example 1: Write an algorithm to
determine a student’s final grade and
indicate whether it is passing or failing.
The final grade is calculated as the
average of four marks.

Pseudocode:
 Input a set of 4 marks
 Calculate their average by summing and dividing
by 4
 if average is below 50
Print “FAIL”
else
Print “PASS”

 Detailed Algorithm
 Step 1: Input M1,M2,M3,M4
Step 2: GRADE  (M1+M2+M3+M4)/4
Step 3: if (GRADE < 50) then
Print “FAIL”
else
Print “PASS”
endif

The Flowchart
 (Dictionary) A schematic representation of a sequence of
operations, as in a manufacturing process or computer
program.
 (Technical) A graphical representation of the sequence of
operations in an information system or program.
 Information system flowcharts show how data flows from source
documents through the computer to final distribution to users.
 Program flowcharts show the sequence of instructions in a single
program or subroutine. Different symbols are used to draw each
type of flowchart.

The Flowchart
A Flowchart
shows logic of an algorithm
emphasizes individual steps and their
interconnections
e.g. control flow from one action to the next

Flowchart Symbols
Basic
Oval
Parallelogram
Rectangle
Diamond
Hybrid
Name Symbol Use in Flowchart
Denotes the beginning or end of the program
Denotes an input operation
Denotes an output operation
Denotes a decision (or branch) to be made.
The program should continue along one of
two routes. (e.g. IF/THEN/ELSE)
Denotes a process to be carried out
e.g. addition, subtraction, division etc.
Flow line Denotes the direction of logic flow in the program

Example
PRINT
“PASS”
Step 1: Input M1,M2,M3,M4
Step 2: GRADE  (M1+M2+M3+M4)/4
Step 3: if (GRADE <50) then
Print “FAIL”
else
Print “PASS”
endif
START
Input
M1,M2,M3,M4
GRADE(M1+M2+M3+M4)/4
IS
GRADE<5
0
PRINT
“FAIL”
STOP
Y
N

Example 2
 Write an algorithm and draw a flowchart to
convert the length in feet to centimeter.
Pseudocode:
 Input the length in feet (Lft)
 Calculate the length in cm (Lcm) by
multiplying LFT with 30
 Print length in cm (LCM)

Example 2
Algorithm
 Step 1: Input Lft
 Step 2: Lcm  Lft x 30
 Step 3: Print Lcm
START
Input
Lft
Lcm  Lft x 30
Print
Lcm
STOP
Flowchart

Example 3
Write an algorithm and draw a flowchart that
will read the two sides of a rectangle and
calculate its area.
Pseudocode
 Input the width (W) and Length (L) of a rectangle
 Calculate the area (A) by multiplying L with W
 Print A

Example 3
Algorithm
 Step 1: Input W,L
 Step 2: A  L x W
 Step 3: Print A
START
Input
W, L
A  L x W
Print
A
STOP

Principles of Programming - NI July
2005 17
Flowcharts
 Flowcharts is a graph used to depict or
show a step by step solution using
symbols which represent a task.
 The symbols used consist of geometrical
shapes that are connected by flow lines.
 It is an alternative to pseudocoding;
whereas a pseudocode description is
verbal, a flowchart is graphical in nature.

2005 18
Flowchart – sequence control structure
Statement 2
Statement 1
Statement 3
:

2005 19
Flowchart – selection control structure
Condition
else-
statement(s)
then-
statement(s)
Yes
No

2005 20
Flowchart – example 1
Begin
Read birth date
Calculate
Age = current year – birth date
Display
age
End

2005 21
Flowchart – example 2
Begin
Read age
End
Age > 55? NO
YES
print “Pencen” print “Kerja lagi”

Exercises: Algorithm &
Flowchart
1.) Create an algorithm and a flowchart that
will accept/read two numbers and then
display the bigger number.

Flowchart
will compute the area of a circle.

Flowchart
will compute the sum of two numbers. If
the sum is below or equal to twenty, two
numbers will be entered again. If the sum
is above 20, it will display the sum.

Lab Activity: Algorithm &
Flowchart
4) Create an algorithm and a flowchart that
will output the largest number among the
three numbers.

Lecture_01-Problem_Solving[1]||ProgrammingFundamental.ppt

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