Python Basic Function Programs

 

In Python, a function is a block of code that performs a specific task and can be called using a name. Functions help you organize your code, make it more readable, and reusable.

Here's an example of a simple function in Python:

def greet(name):
  print("Hello, " + name)

greet("John")  # prints "Hello, John"

In this example, the greet function takes in a parameter called name and prints a greeting message using the value of name.

To define a function in Python, you use the def keyword followed by the function name and a list of parameters in parentheses. The function code is indented and is executed when the function is called.

You can call a function by using its name followed by a set of parentheses, and passing any required arguments inside the parentheses.

You can also define default values for function parameters, which allows you to call the function without specifying a value for that parameter. If you don't specify a value for a parameter with a default value, the default value will be used.

def greet(name, greeting="Hello"):
  print(greeting + ", " + name)

greet("John")  # prints "Hello, John"
greet("John", "Hi")  # prints "Hi, John"

Functions can also return a value using the return statement. For example:

def add(a, b):
  return a + b

result = add(3, 4)  # 7

Here are 15 examples of Python functions:

1) A function to calculate the area of a circle.

def circle_area(radius):
  return 3.14 * radius * radius

area = circle_area(2)  # prints 12.56

2) A function to check if a number is prime.

def is_prime(n):
  if n < 2:
    return False
  for i in range(2, n):
    if n % i == 0:
      return False
  return True

print(is_prime(2))  # True
print(is_prime(3))  # True
print(is_prime(4))  # False

3) A function to reverse a string.

def reverse_string(s):
  return s[::-1]

print(reverse_string("hello"))  # olleh

4) A function to calculate the factorial of a number.

def factorial(n):
  if n == 0:
    return 1
  return n * factorial(n-1)

print(factorial(5))  # 120

5) A function to check if a string is a palindrome.

def is_palindrome(s):
  return s == s[::-1]

print(is_palindrome("racecar"))  # True
print(is_palindrome("hello"))  # False

6) A function to generate a list of prime numbers.

def generate_primes(n):
  primes = []
  for i in range(2, n+1):
    is_prime = True
    for j in range(2, i):
      if i % j == 0:
        is_prime = False
        break
    if is_prime:
      primes.append(i)
  return primes

print(generate_primes(10))  # [2, 3, 5, 7]

7) A function to calculate the Fibonacci sequence.

def fibonacci(n):
  if n == 0:
    return 0
  elif n == 1:
    return 1
  else:
    return fibonacci(n-1) + fibonacci(n-2)

print(fibonacci(10))  # 55

8) A function to sort a list of numbers.

def bubble_sort(numbers):
  for i in range(len(numbers)-1):
    for j in range(len(numbers)-1-i):
      if numbers[j] > numbers[j+1]:
        numbers[j], numbers[j+1] = numbers[j+1], numbers[j]
  return numbers

print(bubble_sort([5, 2, 7, 1, 3]))  # [1, 2, 3, 5, 7]

9) A function to calculate the average of a list of numbers.

def average(numbers):
  return sum(numbers) / len(numbers)

print(average([1, 2, 3]))  # 2

10) A function to check if a string is a palindrome.

def is_palindrome(s):
  s = s.lower()
  s = s.replace(" ", "")
  return s == s[::-1]

print(is_palindrome("A man a plan a canal Panama"))  # True
print(is_palindrome("racecar"))  # True
print(is_palindrome("Hello world"))  # False

11) A function to find the maximum value in a list.

def max_value(numbers):
  return max(numbers)

print(max_value([1, 2, 3, 4, 5]))  # 5

12) A function to check if a number is even.

def is_even(n):
  return n % 2 == 0

print(is_even(2))  # True
print(is_even(3))  # False

13) A function to calculate the greatest common divisor (GCD) of two numbers.

def gcd(a, b):
  if b == 0:
    return a
  return gcd(b, a % b)

print(gcd(10, 15))  # 5

14) A function to convert a list of strings to a single string.

def list_to_string(lst):
  return " ".join(lst)

print(list_to_string(["This", "is", "a", "string"]))  # "This is a string"

15) A function to check if a string starts with a specific prefix.

def starts_with(s, prefix):
  return s.startswith(prefix)

print(starts_with("Hello world", "He"))  # True
print(starts_with("Hello world", "he"))  # False

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