Input, Output and f-strings

You will format output clearly and understand how text entered with input becomes a string.

9 min read 10 quiz questions

Printing values

print() can display several values and can change its ending.

name = 'Mina'
points = 42
print('Player:', name, 'Points:', points)
print('Ready', end='!\n')

print() puts spaces between separate values, so the first line is easy to read. Its usual ending is a new line. Here end='!\n' changes that ending to an exclamation mark and then a new line.

Formatting strings

An f-string puts variables and expressions directly inside text.

item = 'notebook'
price = 3.5
quantity = 4
print(f'{quantity} {item}s cost ${price * quantity:.2f}')
print(f'Next quantity: {quantity + 1}')

Put an f before a quoted string to make an f-string. Curly braces hold a value or expression. :.2f formats the price with exactly two digits after the decimal point.

Formatting can add thousands separators, and str.format() is another option.

visitors = 1234567
city = 'Lima'
print(f'{city} had {visitors:,} visitors.')
print('{} has {} letters.'.format('Python', 6))

The : inside an f-string starts a format instruction. The , instruction adds thousands separators. You may also use str.format(), as in the second line, but f-strings are often easier to read.

Getting user input

This simulates text that a user could have entered.

entered_age = '12'
age = int(entered_age)
print(f'Next year you will be {age + 1}.')

The simulated value starts as text. int() changes '12' into the number 12, so Python can add 1 before printing the sentence.

Key points

print() displays values and normally starts a new line after them.
F-strings use curly braces for values and expressions.
Use :.2f for two decimal places and :, for thousands separators.
str.format() is an older formatting style you may still see.
Text returned by input() must be converted for numeric math.

Worked example

A bKash-style receipt: build a neat line from a name and an amount with an f-string.

Example

name = "Nusrat"
amount = 1250.5
print(f"{name} sent {amount:.2f} taka")

How it works, step by step

Put f before the quote to make an f-string.
{name} drops the variable's value into the text.
{amount:.2f} formats the number to exactly 2 decimal places.

References & Further Reading

Related entries from PyLabs's own reference library.

input() (Read a line of text typed by a user.)
print() (Print objects to the text stream file, separated by sep and followed by end.)
format() (Format a value as text using a format specification.)

Your notes

Practice exercise

Not passed yet

Set name to 'Kai' and score to 12500. Use one f-string to print the sentence below with a thousands separator.

Expected output:

Kai scored 12,500 points.

# Write your code below

Want another challenge on this module? More coding practice

Check yourself

Input, Output and f-strings quiz

10 questions. You get instant feedback per question, and the timer starts when you press the button.

Lesson incomplete

Not completed

Create an ID or sign in to save lesson completion across devices.

Create ID to save

Module lesson progress0/5 complete

Module cheat sheet