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“The only way to do great work is to love what you do.”
– Steve Jobs
A function is a block of reusable code that performs a specific task. It’s reusable, which means you can call it multiple times in your program. This helps to organize your code, make it more readable, and avoid repetition.
**Why Do We Use Functions? **
We use functions in Python for several reasons:
To define a function, you use the def keyword followed by the function name, parentheses for parameters, and a colon. The code block that defines the function is indented.
Syntax:
def function_name(parameters):
# Function body
# Code to be executed
def greet(name):
print("Hello,", name + "!")
# Calling the function
greet("Ahmad") # Output: Hello, Ahmad!
Explanation:
def greet(name): defines a function named greet that takes one parameter, name.print("Hello,", name + "!") is the function body, which prints a greeting message using the provided name.greet("Ahmad") calls the function with the argument “Ahmad”.Key Points:
return statement.return keyword.def add(x, y):
return x + y
result = add(3, 5)
print(result) # Output: 8
Function Requirements:
calculate_area that takes two parameters: length and width.Input:
Output:
Expected Output
The area of the rectangle with length 5 and width 3 is: 15
Additional Test Cases
length = 7, width = 2
The area of the rectangle with length 7 and width 2 is: 14length = 10.5, width = 4.2
The area of the rectangle with length 10.5 and width 4.2 is: 44.1Function Requirements:
is_even that takes one parameter: number."Even" if the number is even, and "Odd" if the number is odd.Input:
Output:
"Even" or "Odd"Expected Output
The number 4 is: Even
Encourage beginners to test the function with various numbers:
num = 7
The number 7 is: Oddnum = -2
The number -2 is: Evennum = 0
The number 0 is: EvenYou can assign default values to parameters, which makes them optional when calling the function.
Video: Learn How to Use Default Parameters in Function Definition
def greet(name, message="Hello"):
print(f"{message}, {name}!")
greet("Alice") # Uses default message "Hello"
greet("Alice", "Hi") # Overrides default with "Hi"
def multiply(a, b):
return a * b
result = multiply(b=3, a=5) # You can specify arguments in any order
greet that takes a name as an argument and a greeting message with a default value of “Hello”. If no greeting is provided, the function should use “Hello.”greet("Alice") should output "Hello, Alice!" and greet("Alice", "Good morning") should output "Good morning, Alice!"calc_price that accepts price, tax=0.05, and discount=0. Calculate the final price after applying tax and discount. Test with various keyword arguments to see how changes affect the result.calc_price(100), calc_price(100, discount=0.1), calc_price(100, tax=0.07, discount=0.1)
video: Guard Statements in Python: Explained Simply
def greet():
print("Hello World!")
greeting = greet
def myfunction(val):
return val % 4 == 0
print(myfunction (13) or myfunction (8))
E) 3.5
def greet(name="User"):
return "Hello, " + name
print(greet("Ahmad"))
A) `Hello, User`
B) `Hello, Ahmad`
C) `Hello`
D) `Error`
def my_function():
pass
print(my_function())
- A) `None`
- B) `0`
- C) `True`
- D) `Error`
def my_func(a, b=2, c=3):
return a + b + c
print(my_func(5, c=4))
111210Errordef my_func(a, b, c=3):
return a + b + c
my_func(1, 2)my_func(1, 2, 4)my_func(a=1, b=2, c=5)my_func(1, c=4, b=2, 5)def change_value(x):
x = 10
num = 5
change_value(num)
print(num)
510ErrorNonedef greet(name: str) -> str:
return "Hello, " + name + "!"
result = greet(5)
print(result)
- A) Hello, 5!
- B) TypeError
- C) None
- D) Hello, !
def func(x, y=2):
return x * y
print(func(3))
sum3(num1,num3,num3) that takes three numbers as input and returns the sum.Write a function SumNum(num1) that takes a number as input and returns the sum of numbers from 1 to that number (num1).
Write a function sumSquares(x) that takes a list of numbers as input and returns the sum of their squares.
Write a function order_food that accepts a main_dish, an optional side_dish with a default value of "fries", and an optional drink with a default of "water". Call this function using both positional and keyword arguments.
order_food("burger"), order_food("pizza", drink="soda"), and order_food("salad", side_dish="breadsticks", drink="juice")Create a function introduce that takes three parameters: name, age, and city. Set default values for age to 18 and city to “Unknown”. Test calling the function with different combinations of arguments.
introduce("John"), introduce("John", 25), introduce("John", 25, "New York")Define a function student_profile that accepts name, grade, and subject with a default value of "Math". Use keyword arguments to call this function in different orders.
student_profile(grade="A", name="Emma") and student_profile("Sophia", "B", subject="History")Write a function add_numbers that takes two numbers and returns their sum.
add_numbers(3, 5) should return 8Write a function circle_area that calculates the area of a circle given its radius. Use the formula: area = π * radius² (you can use 3.14 for π).
circle_area(3) should return approximately 28.26celsius_to_fahrenheit that takes a temperature in Celsius and converts it to Fahrenheit using the formula: Fahrenheit = Celsius * (9/5) + 32.celsius_to_fahrenheit(25) should return 77.0is_even that takes a number and returns True if the number is even, and False otherwise.is_even(4) should return True and is_even(7) should return Falsemax_of_three that takes three numbers and returns the largest one.max_of_three(3, 7, 5) should return 7simple_interest that calculates simple interest given principal, rate, and time using the formula: interest = (principal * rate * time) / 100.simple_interest(1000, 5, 2) should return 100.0is_prime that checks if a number is prime. A prime number has only two divisors: 1 and itself.is_prime(7) should return True and is_prime(8) should return Falsefactorial that takes a number and returns its factorial. (Factorial of 5 is 5 * 4 * 3 * 2 * 1 = 120)factorial(5) should return 120Write a program with three functions:
isEven(n): This function takes an integer n as input and returns True if n is even and False otherwise. You can use the modulo operator (%) to check for evenness.printTable(n): This function takes an integer n as input and prints its multiplication table. The table should show the product of n with each number from 1 to 10, formatted like n * i = n * i, where i is the current number in the loop.main: The main program should:
isEven(n) function to check if the entered number is even.printTable(n) function to print its multiplication table.Example output:
Enter an integer: 4
4 is even! Here's its multiplication table:
4 * 1 = 4
4 * 2 = 8
4 * 3 = 12
...
4 * 10 = 40
fibonacci that takes a number n and returns the nth number in the Fibonacci sequence.fibonacci(5) should return 5 (sequence: 0, 1, 1, 2, 3, 5, …)Function Requirements:
guess_number that takes no parameters.Input:
Output:
When the user plays the game, the interaction might look like this:
Welcome to the Number Guessing Game!
Guess a number between 1 and 100.
Enter your guess: 50
Too low! Try again.
Enter your guess: 75
Too high! Try again.
Enter your guess: 60
Congratulations! You've guessed the number 60 in 3 attempts.
random module to select a random number.input() to get the user’s guess and convert it to an integer.Which of the following will cause a syntax error due to incorrect indentation in Python?
A)
print("Hello World!")
B)
def my_function():
print("Hello World!")
C)
if x == 10:
print("x is 10")
D)
x = 10
Answer: B
Parameters are defined by the names that appear in a function definition, whereas arguments are the values actually passed to a function when calling it. Parameters define what kind of arguments a function can accept.
See also the FAQ question of Python Documentation on the difference between arguments and parameters.
def greet(name): # 'name' is a parameter
print("Hello,", name + "!")
greet("Alice") # "Alice" is an argument
In this example:
name is a parameter in the function greet."Alice" is an argument passed to the function when it’s called.To summarize:
Think of it like this:
Sure! Here’s a simple task for beginners to practice writing functions in Python, along with input and output examples.