Input and Output — PythonLessonLab

THE IDEA

Understand the concept

In a normal Python terminal, input() reads a line and returns it as a string. If you need a number, convert that text with int() or float() before doing arithmetic.

The input box below the editor supplies one response per line to input(). We have put 17 there so the example runs immediately. Change it and run again. print() can show multiple values, and an f-string can give the result a clear label.

input() returns text
Convert numeric text
Label output clearly

WORKED EXAMPLES

See it step by step

Read the code, predict the output, then compare it with the result.

01. Convert numeric text

PYTHON

age_text = "21"
age = int(age_text)
print(f"Current age: {age}")
print(f"Next year: {age + 1}")

EXPECTED OUTPUT

Current age: 21
Next year: 22

input() also returns text like '21'. int() converts it before arithmetic; labels make the output clear.

02. Display labeled text

PYTHON

name = "Maya"
print("Learner:", name)
print(f"Name type: {type(name).__name__}")

EXPECTED OUTPUT

Learner: Maya
Name type: str

print() can combine a label and a value. An f-string gives you another way to label output.

HANDS-ON

Try it in Python

Edit the example and run it. Python starts in your browser the first time you click Run.

Python console

Ready to run

entered_age = input("How old are you? ")
age = int(entered_age)
next_year = age + 1
print(f"Next year you will be {next_year}.")

Need input()? Add one value per line

Input lines

Ctrl / ⌘ + Enter to run

OUTPUT

Your output appears here.

Your turnChange the value in the input box to 21 and run again. Add a second print line that shows the current age and next-year age with clear labels.

Need a hint?

Enter 21 in the console's input box before running. Keep int(entered_age); then print a line such as f'Current age: {age}; next year: {next_year}'.

Complete the task and select Check task to verify your code.

KNOWLEDGE CHECK

Quick quiz

Three questions. You can change your answers and try again.

DEBUG BETTER

Typical mistakes

Everyone meets these errors. See what causes them and how to fix them.

Adding a number to input text

COMMON MISTAKE

entered_age = "17"
print(entered_age + 1)

FIX

entered_age = "17"
print(int(entered_age) + 1)

What happens: TypeError because entered_age is text.
Convert numeric text before arithmetic.

Converting nonnumeric text