Python Loops

Use these exercises to practice working with conditional statements, while loops, and Lists in Python.

Must Haves

• Create a new folder, initialize a git repository
• Create a separate file for each section (file names are listed per section)

While Loop

Save these in a file called loops.py.

Start/End

• Ask the user for a starting number, assign it to a variable.
• Ask the user for an ending number, assign it to a variable.
• Write a loop that increments the starting number by 1 until it matches the ending number.

Solution

  start = int(input("Start from: "))
  end = int(input("End on: "))

  count = start

  while count <= end:
      print(count)
      count += 1

Multi-Condition Check

• Create string with at least 2 words and at least 16 characters total.
• Create a variable called counter with a starting value of 0
• Loop through the string
  • Increment the counter by 1
  • Stop the loop when counter is greater than the length of your string.
• IN THE LOOP
  • Write a condition to see If the counter value is an even number.
  • Also make sure the value of your string at the index of counter isn't a blank space!
  • If both of those conditions are met, print the value of your string at that counter position
• The result should be only letters that occur in even numbered indexes.

Solution

title = "Green Lantern Corp"
counter = 0
while counter < len(title):
    # print out every other letters, but leave out spaces
    if (counter % 2) == 0 and title[counter] != " ":
        print(title[counter])
    counter = counter + 1

Bonus

• Can you write a loop that increments by more than 1?
• Can you create a range of numbers from which the user can choose?
• Can you let the user know when they choose something out of that range?

Solution

# Can you write a loop that increments by more than `1`?

while count <= end:
    print(count)
    count += 5


# Can you create a range of numbers from which the user can choose?

def check_in_range(num):
    if num >= 1 and num <= 5:
        return True
    else:
        return False

# Can you let the user know when they choose something out of that range?

def throw_error(value_type):
    return "Please choose a different {} value".format(value_type)

running = True
while running == True:
    start = int(input("Pick a number from 1-5 to start from: "))
    end = int(input("Pick a number from 1-5 to end on: "))

    if check_in_range(start) == True and check_in_range(end) == True:
        if end <= start:
            print(throw_error("end"))
        while start <= end:
            print(start)
            start += 1
            if start == end:
                running = False
    else:
        if check_in_range(start) == False:
            print(throw_error("start"))
        if check_in_range(end) == False or end >= start:
            print(throw_error("end"))