Python Functions

Python Function:

A function is a block of code which only runs when it is called.

You can pass data which is known as parameters into a function.

After getting parameters function passes some result.

Creating a Function:

def keyword is used to create function.

Example:

def first_func():
  print("Hello first function")

Here we have created a function.

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Calling a Function:

Example:

def first_func():
  print("Hello first function")

my_function() #calling function

Output:
Hello first function

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Parameters in function:

One can add as many parameters, just separate them with a comma.

Example:

def first_func(names):
  print(names + "Hello")

first_func("Ara")
first_func("Toob")

Output:
Ara Hello
Toob Hello

Note:The following example has a function with one parameter (names).

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Default Parameter Value:

Example:

def first_func(names = "Poot"):
  print(names + "Hello")

first_func()
first_func("Toob")

Output:
Poot Hello
Toob Hello

Note:If we call the function without parameter, it uses the default value.

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Return Values:

Use the return statement,to let function to return a value.

Example:

def my_function(x):
  return 5 + x
print(my_function(3))
print(my_function(5))
print(my_function(9))

Output:

8

10

14

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Key Arguments:

Example:

def my_function(car3, car2, car1):
  print("The car is " + car3)

my_function(car1 = "BMW", car2 = "MERCS", car3 = "TOYA")

Output:

The car are TOYA

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Arbitrary Arguments:

If you do not know how many arguments that will be passed into your function, add a * before the parameter name in the function definition.

Example:

def my_function(*cars):
  print("The best car is " + cars[1])

my_function("BMW", "MERCS", "TOYA")

Output:

The best car is MERCS

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Recursive function:

Python also accepts function recursion, which means a defined function can call itself.

Example:

def calc_factorial(k):
  if(k == 1):
    return 1
  else:    
    return(k * calc_factorial(k-1))

num = 3
print("The factorial of num is ",calc_factorial(num))

Output:

6

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Passing a List as parameter:

Example:

def my_function(vehicle):
  for x in vehicle:
    print(x)

cars = ["BMW", "BCW", "BKW"]

my_function(cars)

Output:

BMW

BCW

BKW

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