Programming with User Interaction

Introduction

• Learn to create programs that respond to user inputs.
• The individual running the program is referred to as the "user."
• Previously, programs interacted in a one-way fashion (output only).

Two-Way Interaction

• New goal: Write programs that ask the user for information.
• Need to retrieve and store user input.
• Variables can store input.

Using the input() Function

• Retrieves text from the user.
• To use, include a string prompt in parentheses.
• Execution pauses until the user inputs and presses Enter.
• Example:

  name = input("Enter your name: ")
  print(name)
  

• Type of input: Stored as str (string).
• Any user entry, even numbers, is initially a string.

Converting Strings to Numbers

• Problem: Cannot perform arithmetic on a string.
• Solution: Use int() to convert a string to an integer.
• Example:
  • User enters a number, stored initially as string.
  • int() converts it for arithmetic operations.

Function Composition

• Evaluate expressions from the inside out.
• Example process:
  1. input() captures user input.
  2. int() converts input string to integer.
  3. Store integer in a variable.
• Concept helps manage complex expressions in programming.

Conclusion

• Understanding user input and data conversion is essential.
• Mastery of these concepts is foundational for interactive programming.