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Python example 'lesson4-ForLoops'
lesson4-ForLoops
Python beginners example: lesson4-ForLoops
# Make a list of ordinal words to demonstrate the use of a for loop.
ordinals = ['first', 'second', 'third', 'fourth', 'fifth']
# A for loop is used when you want to perform the same operations FOR each item
# in a list. (Technically it can be any iterable, not just a list.)
for currentWord in ordinals:
# The for loop syntax is: for [someLoopingVarialbe] in [someList]:
# The looping variable will be set equal to the first item in the list and the
# loop code will run. Then the looping variable will be equal to the second
# item and the code will run again. And so on until all list items are used.
print("This is the " + currentWord + " time through the loop.")
print() # Just to get a blank line
# Make a new list to contain the user's favorite songs.
favoriteSongs = []
# In the past we've used a while loop to populate a list with user input.
# Now we'll populate the list using a for loop. Notice that this loop will run
# once for each ordinal in the list
for canBeCalledAnything in ordinals:
song = input("What's your {} favorite song? ".format(canBeCalledAnything))
favoriteSongs.append(song)
print()
# This is an ugly way to print(a list:)
print("Your favorite songs are :")
print(favoriteSongs)
print()
# A for loop is a perfect way to print(the list more nicely.)
print("Your favorite songs are :")
number = 1
for song in favoriteSongs:
print("{}. {}".format(number, song))
number += 1
print()
# ---------------- Exercises -----------------
# 1. The for loop in line 6 creates a looping variable called currentWord. That
# name is fine, but it is very common to use the singular form of the list
# name itself. Change the name of the looping variable to 'ordinal'. Don't
# forget to change it in other places it is used too.
# 2. While you're at it, you could change the name of the looping variable in
# line 20 as well. Do note that the variable really can be called anything.
# But as always it is best to choose a meaningful name
# 3. The loop that asks users about their favorite songs works pretty well, but
# it doesn't sound very natural to say 'your first favorite'. Put an if
# statement in that loop to surpress the word 'first' from printing.
# 3. Add an ordinal to the list on line 2. Predict how the program will run
# differently in comments in the lines below.
#
#
#
#
Useful links
- Learn Python: https://pythonbasics.org
- Download Python: https://python.org