Cs 1114 - lecture-10
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Transcript of Cs 1114 - lecture-10
Instructor : Muhammad Haris
All Rights Reserved to Department of Computer Science – GCU Lahore
Programming Fundamentals
Test Yourself
Find sum of all integers between any two numbersHow many times you have to repeat it?
Programming Fundamentals | Lecture-10 2
Consider this Example
Find even and odd numbers from first n natural numbersWhat’s different in this example?
○ Let’s have a look at the solutions of finding even and odd numbers separately
Programming Fundamentals | Lecture-10 3
Find first n even numbers
Programming Fundamentals | Lecture-9 4
START
count = count + 1
STOP
count < n
count = 0
YesNo
DISPLAY even
even = 0
even = even + 2
All odd numbers are skipped
by this solution
Find first n odd numbers
Programming Fundamentals | Lecture-9 5
START
count = count + 1
STOP
count < n
count = 0
YesNo
DISPLAY odd
odd = -1
odd = odd + 2
All even numbers are skipped
by this solution
What’s Required
We have to consider all odd and even numbers up to nIt is quite obvious that our solution needs to
decide whether a number is even or odd○ Hence, we’ll use a decision box while finding a
number in every repetitionWhat should be the decision rule? Or how can we
decide that a number that is even or odd?- If we divide a number by 2 and remainder is 0 (the
number is divisible by 2), it is considered as an even number
- How can we check the remainder of a division?
Programming Fundamentals | Lecture-10 6
Remainder Operator
An operator like “+”, “-”, “/” etc. denoted by “%”, that performs the division between two number and gives you the remainderExamples:
○ 4%2 will give 0 as answer because remainder of 4/2 is “0”
○ 9%2 will give you “1”○ 11%3 = ?○ 54%5 = ?
Programming Fundamentals | Lecture-10 7
Programming Fundamentals | Lecture-10 8
START
count = count + 1
STOP
count < n
count = 0
No
No
DISPLAY count “is odd”
READ n
count % 2 == 0
DISPLAY count “is even”
Yes
Yes
Important Observation
Any kind of decision making can be done while repeatedly doing a taskIt can range from simple decision making to
complex series of decision makings as you learnt in your previous lessons
Programming Fundamentals | Lecture-10 9
Try this Yourself
Find all numbers which are divisible by 3 from first n integers
Find all numbers which are divisible by a number from first n integers
Programming Fundamentals | Lecture-10 10
Programming Fundamentals | Lecture-10 11
START
count = count + 1
STOP
count < n
count = 0
YesNo
READ n
count % 3 == 0
DISPLAY count
YesNo
Consider this Example
Find all odd numbers which are divisible by 3 from first n integersHow many decisions are required in every
repetition?
Programming Fundamentals | Lecture-10 12
Programming Fundamentals | Lecture-10 13
START
count = count + 1
STOP
count < n
count = 0
YesNo
READ n
YesNo count % 2 != 0
count % 3 == 0
DISPLAY count
YesNo
Consider this Example
Display “multiplication table” of a number only if the number is not equal to “0”
Programming Fundamentals | Lecture-10 14
Programming Fundamentals | Lecture-10 15
START
count = count + 1
STOP
count < n
count = 0
YesNo
DISPLAY num * count
READ num, n
num != 0
No
YesNo
Important Observation
“Decision Making” and “Repetitions” can be inter-mixed in either wayRepeatedly doing a task if a certain
condition is true ORWhile repeatedly doing a task, making
certain decisions ORBoth of the above
Programming Fundamentals | Lecture-10 16
A Premonition
All of you who are not yet practicing well enough and taking this course “lightly and non-seriously” should:Get ready to face hard-time (as things are
going to get worse for them) ORStart practicing before it gets too late
Programming Fundamentals | Lecture-10 17
Tasks (to be done by next lecture) Display “Fibonacci Series” up to n
Display “Fibonacci Series” up to n, if n is not less than 0
Programming Fundamentals | Lecture-10 18
Programming Fundamentals | Lecture-10 19
BE PREPAREDFOR QUIZ
INNEXT LECTURE