We will understand better the so called functional programming in the next lessons. Here we will learn how to use the print and input functions.
Print Function
Print is a function that is used to print text in the console. We have already seen the print function in the previous lesson. Let’s see how it works.
- we can see the details on the Python documentation page here
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| # basic print statement
print('Something')
print(2+2)
print('3 + 4 = ', 3+4)
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| Something
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3 + 4 = 7
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These are the details of the print function from the Python documentation.
print(*objects, sep=' ', end='\n', file=None, flush=False)
sep is an optional argument that specifies the separator between objects. The default separator is a space. If no separator is specified, no separator is printed.end is an optional argument that specifies the ending string. The default ending string is a newline. If no ending string is specified, no ending string is printed.file is an optional argument that specifies the file to write the output to. If no file is specified, the output is printed to the console.flush is an optional argument that specifies whether to flush the output buffer. The default is False. If True, the output buffer is flushed.
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| # separator argument
print('This', 'is', 'a', 'test', sep='__')
print('a', 'b', 'c', sep='*')
# end argument
print('Hello', end=' ')
print('World')
print('!')
# file argument - we will see later
# flush argument - we will see later
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| This__is__a__test
a*b*c
Hello World
!
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Input is a function that is used to get input from the user.
- we can see the details on the Python documentation page here
input(prompt) - where prompt is an optional argument that specifies the prompt to display. The default prompt is > .
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| # let us try a basic input statement
input() # this will wait for user input but the input is not stored
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| # we need to store the input in a variable so that we can use it
a = input()
print(a)
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The input function returns a string that is the input from the user. If no input is provided, the default value '' or empty string is returned.
if we want to store a number, we need to convert it to a number using int(), float(), etc.
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| # input of a number
num = input('Enter a number: ')
num = int(num) # convert the input to an integer
print(num**2)
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If we expect to get a number, but the user inputs letters, we get an error.
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| num = input('Enter a number: ')
num = int(num) # convert the input to an integer - here we get an error if the user inputs letters
print(num)
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| ---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
Cell In[13], line 2
1 num = input('Enter a number: ')
----> 2 num = int(num) # convert the input to an integer - here we get an error if the user inputs letters
3 print(num)
ValueError: invalid literal for int() with base 10: 'po'
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For Loop
- We are introducing just a basic version of a for loop in order to have some repetitive skills.
- we use for loop to do some repetitive task for some definitive number of times.
for i in range(5) - where i is a variable that represents the number of times the loop will repeat.
- range(5) will give us the numbers from 0 to 4
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| # basic for loop
for i in range(5):
print(i)
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| for i in range(5):
print('#', end='')
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| for i in range(5):
print('#'*(i+1))
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| #
##
###
####
#####
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| for i in range(5):
print('#'*i)
for i in range(5):
print('#'*(5-i))
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| #
##
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####
#####
####
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##
#
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| for i in range(5):
print(f'{'#'*(i*2 +1):^12}')
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| #
###
#####
#######
#########
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Let us practice now some of these skills.
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| # input dogs name and years and output his name and age in dog years
name = input('Enter your dogs name: ')
age = int(input('Enter your dogs age: '))
print(f'{name} is {age*7} dog years old')
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| Fido is 70 dog years old
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Madlib Game
- Let us create a madlib game using the print and input functions.
This is an example from the web site https://hobbylark.com/party-games/How-to-Make-Your-Own-Mad-Libs
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| # madlib game
adjective1 = input('Enter an adjective: ')
adjective2 = input('Enter another adjective: ')
type_of_bird = input('Enter a type of bird: ')
room_in_a_house = input('Enter a room in a house: ')
verb_past_tense = input('Enter a verb in the past tense: ')
verb = input('Enter a verb in infinitive (to ...): ')
relative_name = input('Enter a relative\'s name: ')
noun = input('Enter a noun: ')
liquid = input('Enter a liquid: ')
room = input('Enter another room in a house: ')
body_part_plural = input('Enter a part of the body (plural): ')
plural_noun = input('Enter a plural noun: ')
verb_ending_in_ing = input('Enter a verb ending in -ing: ')
noun2 = input('Enter another noun: ')
# Use an f-string to insert the input into the template
story = f'''It was a {adjective1}, cold November day.
I woke up to the {adjective2} smell of {type_of_bird} roasting
in the {room_in_a_house} downstairs. I {verb_past_tense} down the stairs
to see if I could help {verb} the dinner.
My mom said, 'See if {relative_name} needs a fresh {noun}.'
So I carried a tray of glasses full of {liquid} into the {room}.
When I got there, I couldn't believe my {body_part_plural}!
There were {plural_noun} {verb_ending_in_ing} on the {noun2}!'''
# Output the completed story
print(story)
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| It was a rare, cold November day.
I woke up to the smart smell of swallow roasting
in the bedroom downstairs. I cut down the stairs
to see if I could help to see the dinner.
My mom said, 'See if Mark needs a fresh pot.'
So I carried a tray of glasses full of Coke into the kitchen.
When I got there, I couldn't believe my ears!
There were roads playing on the killer!
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