Python Key Skills - 2

Table of Contents

1. Python Key Skills 2
- Learn It - for loops and while loops
  - for loops
  - while loops
- Learn It - check if a whole number is even or odd

1 Python Key Skills 2

Learn It - for loops and while loops

The purpose of loops is to repeat a set of commands or a block of code

for loops

for loops are normally used to repeat a set of commands for a specific known number of times.

for i in range(5):
    print("Hello world!")

the above code will print out "Hello world!" 5 times with i starting from 0, increasing each loop by 1, up to 4.
the range is a Python built-in function that produce a series of numbers.

while loops

while loops are normally used to repeat a set of commands until certain condition(s) are no longer true.
Example while loop 1:

i=0
while i < 5:
    print("Hello world!")
    i = i + 1

Example while loop 2:

hungry = True
while hungry:
    print("I need eat more.")
    answer = input("Are you still hungry?(Y/N)")
    if answer == "N":
       hungry = False

The above loop will end if the user input "N", which changes the hungry variable to "False". This means, the condition is not true anymore.

Learn It - check if a whole number is even or odd

We know from maths that all even numbers can be divisible by 2. In other words, any even number, when divided by 2, the reminder should be 0 - no reminder.
In Python, we have learned that the reminder operator is %. For example: 24%2 = 0; 25%2=1; 1%2=1 etc
So if the reminder is 0 when divided by 2, then the number is even.

myNum = int(input("Please give me a whole number: "))

if myNum % 2 == 0:
   print("The number you game to me is an even number")
else:
   print("The number you game to me is an odd number")