1. Count Controlled Loops
Look at the little children …
Why is the sun’s face features orange …

2. Warm Up Practice
Write a program that continually asks the user for a price value
When the user enters the word “end” you should end the program and add the total price of all the products
In addition, display the highest priced item and the lowest priced item

3. Warm Up Practice
Extension: Now, try writing your program so that it does not crash.

4. Count Controlled Loops
Previously, we learned the “while” loop, which we defined as the condition controlled loop
It is so called “condition controlled” because it iterates the number of times in which a Boolean expression holds True
Today, we will look at what is called a “count controlled” loop

5. Count Controlled Loops
It is called “count controlled” because it iterates a specific number of times
It is not dependent on the truth value of a Boolean expression, or condition

6. Count Controlled Loop
Now, it’s important to remember that a lot of times in Python, we can accomplish the same tasks with various different methods i.e. ELIF’s versus nested IF’s
In the same way, a count controlled loop can be created by using a “while” loop
These various methods are really for convenience’s sake
(We should also note that a while loop can be duplicated by a function controlled loop)

7. Count Controlled Loop
Example: counter = 0 while counter < 5: print (“this will print 5 times!”) counter +=1

8. Lists Python has such things called “lists”
Lists are denoted by brackets [ a, b, c, d ] and each item in the list is separated by commas
Lists can be stored and named as variables
Example:
x = [a, b, c, d]

9. Lists
One important thing to note about lists is that they can hold various data types all at once
Example:
list = [“name”, “word”, 1, 2, 3]

10. The ‘’for’’ loop
The “for” loop is Python’s native count controlled loop
Example:
for num in [1, 2, 3, 4, 5]:
print(“this will also print 5 times”)

11. The ‘’for’’ loop The “for” keyword starts the loop
The “num” is the name of the target variable
“in” is another keyword
[1, 2, 3, 4, 5] is the list of items to iterate over
Note the indentation

12. The ‘’for’’ loop
The “for” loop will iterate once for each item in the list passed to it when the loop begins
During the first iteration, the target variable will assume the value of the first item in the list
During the second iteration, it will assume the second item in the list
This continues until you reach the end of the list

13. The ‘’for’’ loop
for x in [1, 2, 3, 4, 5]: >> 1 print (x)

14. The ‘’for’’ loop
for name in [“Josh”, “Jeen”, “Nicole”]: print(“My favorite student is”, name) >> My favorite student is Josh My favorite student is Jeen My favorite student is Nicole

15. Practice – Make Dat DOE
Write a program that asks the user how much money they made from Monday to Sunday
The program should specify the day each time it asks the user for a value
Then sum up the total amount they made and print out

16. Practice – Mechanics Rewrite the following loop as a “while” loop:
for x in [10, 20, 30, 40]:
print (x)

17. The range( ) Function
So far, we’ve been TIRELESSLY writing out lists of pre-defined values in our “for” loops
The range( ) function allows us to dynamically generate lists based on pre-determined criteria

18. The range( ) Function
for x in range(5): >> iteration # 0 print(“iteration #”, x) iteration # 1 iteration # 2 iteration # 3 iteration # 4

19. The range( ) Function
The range( ) function takes at least one argument
In it’s simplest form, it takes a single integer
The range( ) function returns what we can think of as a list in Python
When passed a single integer, it will return a list of integers from 0 to the number specific minus one

20. The range( ) Function
range(5) [ 0, 1, 2, 3, 4] range (10) [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

21. The range( ) Function
However, the range( ) function can behave in different ways
It can take two arguments, which sets a start and an end value
By default, the function increments by 1
range (1, 5) [ 1, 2, 3, 4]
range (5, 10) [ 5, 6, 7, 8, 9]

22. The range( ) Function
You can also pass three arguments and set a start value, an end value, and a step value
range(0, 10, 2) [0, 2, 4, 6, 8]
range(1, 15, 3) [1, 4, 7, 10, 13]
If the step count does not perfectly fall on the end value, it will just include the number before the end value is reached

23. The range( ) Function
Lastly, you can ask the range( ) function to count backwards by passing in a negative step count

24. Import ‘’time’’
We’ll talk more about this later, but another module we can import into Python is “time”
We can ask Python to pause (for dramatic effect) by calling the sleep( ) function in time
The sleep( ) function can take one argument, denoting the number of seconds to “sleep”
**sleep( ) can also take floats

25. Import ‘’time’’
The sleep() function does not return anything and therefore can be called anywhere in your code
print(“Hello”)
time.sleep(2)
print(“Goodbye”)

26. Practice – Countdown
Write a program that counts down from 10 and then print out “HAPPY NEW YEAR!”

27. Import ‘’time’’
import time for x in range(10, 0, -1): print(x) time.sleep(1) print(“HAPPY NEW YEAR!”)

28. Loop Targets
In a “for” loop, we generally use the target variable as a reference value for some kind of calculation
Remember that the value of the target variable changes with each iteration of the loop

29. Practice – Squares
Write a program that calculates the square of the numbers between 1 and 10
Print out the number and it’s square as your loop iterates

30. Practice – Stair Master
Write a program that prints out the following:
** (2 stars)
**** (4 stars)
****** (6 stars)
******** (8 stars)
********** (10 stars)
************ (12 stars)

31. User Controlled Ranges
Sometimes, we need to ask the user to control the # of iterations within a loop
You can do this by substituting a variable within the range( ) function to control the start, end, and step values of the list that will be generated

32. User Controlled Ranges
x = int(input(“start value: “)) y = int(input(“end value: “)) z = int(input(“step value: “)) range(x, y, z)

33. User Controlled Ranges
We can also just put the input( ) function directly into the range( ) function
However, we must remember to convert it into an integer

34. User Controlled Ranges
range(int(input(“start: “)), int(input(“end: “)), int(input(“step: “)))
Just be careful, as this can be confusing and you need to keep count of how many parentheses you use

35. Practice – Stair Master
Extend your stair master program to allow the user to decide how many flights of stairs they’d like
Also allow the user to decide how many stars they’d like in each flight of stairs