L3 User Input

Imagine a conversation where only one person talks—that wouldn’t be very interactive! In Python, the input() function allows the program to "listen" to the user, making it interactive.

With input(), a program can ask for information, like a name or age, and store it in a variable. This makes programs more dynamic and responsive.

💡 Analogy: input() is like a waiter taking an order—it asks a question, waits for an answer, and then processes it.

Learning Objectives

By the end of this lesson, you will be able to:

1. Use the input() function to collect user input.

2. Convert user input into different data types.

3. Understand why user input is useful in interactive programs.

Key Terms

• input() function – A built-in function that allows a program to take input from the user as a string.

• Variables – Named storage locations in memory that hold data, such as a user's name or age.

• String concatenation – The process of combining two or more strings using the + operator (e.g., "Hello " + name).

• Type conversion – Changing one data type to another, such as converting a string "25" into an integer 25 using int().

• Interactive programs – Programs that ask users for input and respond dynamically based on the provided information.

Example

name = input("What is your name? ")

print("Hello, " + name + "!")

🛑 Common Mistakes

1. Forgetting type conversion: age = input("Enter your age: ") stores a string, so age + 5 ❌ will cause an error. Use int(age) + 5 ✅.

2. Forgetting to store input: Just writing input("Enter name: ") without assigning it to a variable means the input is lost.