Getting input from users is essential for interactive programs. In Python, the input() function allows your program to read data from the user via the console.

This tutorial covers:

• How input() works

• Converting input data types

• Formatting prompts

• Using input in conditionals and loops

• Common mistakes and best practices

• A complete example project

What is input()?

Python’s built-in input() function reads a line of text entered by the user and returns it as a string.

name = input("Enter your name: ")
print("Hello, " + name + "!")

Sample Output:

Enter your name: Alice
Hello, Alice!

Note: Everything returned by input() is of type str (string), even if the user enters a number.

Converting Input Types

To use numbers, convert the string input using int(), float(), etc.

Example: Convert to Integer

age = int(input("Enter your age: "))
print("You will be", age + 1, "next year.")

Example: Convert to Float

price = float(input("Enter the price: "))
print("With tax:", price * 1.07)

⚠️ If the input cannot be converted, Python will raise a ValueError. Use try-except to handle this gracefully.

Validating User Input

Always validate user input when expecting specific formats or data types.

Example: Using try-except

try:
    score = int(input("Enter your score: "))
    print("Score recorded:", score)
except ValueError:
    print("Invalid input. Please enter a number.")

Input Inside Loops

You can use input() in loops to keep prompting until the user enters valid data.

Example: Input Until Correct

while True:
    answer = input("Type 'yes' to continue: ").lower()
    if answer == "yes":
        break
    print("Try again!")

Formatting Prompts

Make prompts more user-friendly by:

• Using descriptive messages

• Including units or formats in the prompt

Example:

height = float(input("Enter your height in meters: "))

Real-World Input Example: Simple Calculator

print("Simple Calculator")
try:
    num1 = float(input("Enter first number: "))
    operator = input("Enter operator (+, -, *, /): ")
    num2 = float(input("Enter second number: "))

    if operator == '+':
        result = num1 + num2
    elif operator == '-':
        result = num1 - num2
    elif operator == '*':
        result = num1 * num2
    elif operator == '/':
        result = num1 / num2
    else:
        result = "Unknown operator"

    print("Result:", result)

except ValueError:
    print("Invalid input! Please enter numbers.")

✅ Tips for Using input()

⚠️ Common Pitfalls

Complete Example: Interactive Greeting

def greet_user():
    name = input("What is your name? ").strip().title()
    try:
        age = int(input("How old are you? "))
        print(f"\nHi {name}, you are {age} years old!")
        if age < 18:
            print("You're still a minor.")
        else:
            print("You're an adult.")
    except ValueError:
        print("Invalid age. Please enter a number.")

greet_user()

Conclusion

The input() function is your gateway to creating interactive Python programs. Whether you're building games, forms, or calculators, knowing how to collect and validate user input is essential.

Remember:

• Always convert and validate input.

• Use friendly, clear prompts.

• Wrap input logic in functions for better reuse and testing.