Introduction to Input and Output

Input and output are essential for interacting with a program. Input allows users to provide data, while output displays information back to them.

In this lesson, you’ll learn how to use the input() and print() functions in Python.

The print() Function

The print() function displays text or information on the screen. For example:

print("Hello, World!")

This will output:

Hello, World!

# Using the print function
print("Hello, World!")

The input() Function

The input() function allows users to enter data into a program. For example:

When you run this code, Python will prompt the user to enter their name and then greet them.

# Using the input function
name = input("What is your name? ")
print("Hello,", name)

Combining Input and Output

You can combine the input() and print() functions to create interactive programs. For example:

# Combining input and output
age = input("How old are you? ")
print("You are", age, "years old!")

Formatting Output

You can format output using the f-strings feature in Python. For example:

# Formatting output using f-strings
name = "Alice"
age = 25
print(f"{name} is {age} years old.")

Using Input with Numbers

The input() function always returns a string, even if the user enters a number. You can convert it to an integer or float using int() or float(). For example:

# Using input with numbers
num = int(input("Enter a number: "))
print("Your number multiplied by 2 is", num * 2)

Error Handling with Input

If the user enters invalid data, it can cause an error. You can handle such cases using a try-except block:

# Handling errors with input
try:
    num = int(input("Enter a number: "))
    print("Your number is", num)
except ValueError:
    print("That’s not a valid number!")

What Did We Learn?

In this lesson, you learned:

• How to use the print() function to display output.
• How to use the input() function to take user input.
• How to format output and handle input errors.

Great job! Let’s move to the next topic.