Understanding Functions in Python

Definition of Functions

• Functions are blocks of reusable code.
• To invoke (call) a function, use parentheses after the function name.

Example: Singing Happy Birthday

• To sing Happy Birthday three times without repeating code or using loops, we define a function.
• Defining a Function:
  • Syntax: def function_name():
  • Indent the code that belongs to the function.
• Invoking the Function:
  • Syntax: function_name()
  • Example: happy_birthday() three times.

Parameters and Arguments

• Arguments: Data sent to a function when invoked.
• Parameters: Variables in a function definition that match the arguments.
• Example of using a parameter:
  • def happy_birthday(name):
  • Invocation: happy_birthday("Bro")
  • Output: Happy Birthday to Bro

Passing Multiple Arguments

• You can pass more than one argument to a function:
  • Example: Using name and age as parameters.
• Error Handling:
  • Must match the number of arguments to parameters.
  • Example correction:
    • Define function with two parameters: def happy_birthday(name, age):

Using F-Strings for Outputs

• Utilize f-strings for formatted strings:
  • Syntax: f"{placeholder}"
• Example output: Happy Birthday to {name}, you are {age} years old.

Return Statement

• Purpose of Return: Ends a function and sends a result back to the caller.
• Example of a function that adds numbers:
  • def add(x, y): return x + y
• Printing Result:
  • Assign returned value to a variable.

Creating Full Name Function

• Define a function to create a full name:
  • def create_name(first, last):
  • Capitalize first and last names, then return concatenated string.
• Example Usage:
  • full_name = create_name("john", "doe")

Summary

• Functions are important for code reusability.
• Call functions with their name and parentheses; pass data as arguments.
• Ensure matching parameters in function definitions and handle returns properly.
• Practice writing and invoking functions to enhance coding skills.