Cs 1114 - lecture-2

Instructor : Muhammad Haris

All Rights Reserved to Department of Computer Science – GCU Lahore

Programming Fundamentals

This Course

Problem Solving Using Computers

Implementing the Solution using a

Programming Language

1 2

The first part is mostly ignored which leads to poor programming skills

2Programming Fundamentals | Lecture-2



1

Steps in Problem Solving

Define the Problem Design the Solution

1 2


1. Define the Problem After careful reading, the problem should

be divided into three separate componentsInput

○ Data provided to the problemOutput

○ What is required from the solutionProcessing

○ List of actions needed to produce the required output


Solution of a Problemin your mind

2. Design the Solution

Solution in terms ofno. of steps

Transform

There are more than 1 ways to do that but we will use a graphical approach

which will involve usage of Geometrical Shapes

to represent different kinds of steps in a solution




Example-1


Step-1: Define the Problem

Input Output ProcessingNumber1 Sum Add Numbers Together

Number2

Programming Fundamentals | Lecture-2 8

Problem: Find the sum of two numbers

Step-2: Design the Solution Start by drawing a “Start” symbol Show a symbol for Input Show process symbol(s) for processing

There can be more than 1 such steps depending on the complexity of the problem

Show a symbol for Output Finish by drawing a “Stop” Symbol


Step-2: Design the Solution


START

READ number1, number2

sum = number1 + number2

DISPLAY sum

STOP

Legend


Symbol Meaning

Terminal Symbol (Oval) : indicates the beginning and ending of a program

Input-Output Symbol (Parallelogram): shows an input or an output operation

Process Symbol (Rectangle): shows an instruction other than input or output

Other Simple Examples Find sum of three numbers Division, multiplication, subtraction of

two/three numbers Find Average of two numbers Find square of a number Find acceleration for a given velocity

and time Find Velocity


Average of Two Numbers


START

READ number1, number2

sum = number1 + number2

DISPLAY average

STOP

average = sum / 2

Square of a Number


START

READ number

square = number * number

DISPLAY square

STOP

Acceleration


START

READ v1, v2, t

change = v2 – v1

DISPLAY acceleration

STOP

acceleration = change / t

Velocity


START

READ d1, d2, t1, t2

positionChange = d2 – d1

DISPLAY velocity

STOP

timeChange = t2 – t1

velocity = postionChange / timeChange

Why to use Computers? Can do many complicated tasks at very

high speeds and can store large quantities of data

Some SituationsExtensive InputExtensive outputMethod of solution is too complicated to

implement manuallyIf done manually, it takes an excessive long

time to solve

Tasks (to be done before next lecture) Calculate area of a rectangle

area = base height Find Cube of a Number Calculate Marks Percentage

(marks obtained / total marks) 100 Calculate Sales Tax

amount (tax percent / 100) Find “no. of minutes” and “no. of seconds”

for given “no of years”



BE READY FOR QUIZ

IN NEXT LECTURE

Cs 1114 - lecture-2

Technology

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