This document discusses Python functions. It defines what functions are and how they can be created and used in Python. It covers creating basic functions, functions that accept arguments, functions that return values, and recursive functions that call themselves. Examples are provided for each concept to demonstrate how to structure functions and pass/return different data types.

1. Python Functions
‫إعداد‬:
‫م‬.‫محمد‬ ‫علي‬

2. Objectives
 Functions in Python
 Create a function
 Create a function with arguments
 Pass more than one arguments
 Default Parameter values
 Create a function and return the value
 Recursion

3. Functions in Python
 A function is a block of code which only runs when it is called.
 We can pass data, known as parameters, into a function.
 A function can return data as a result
 We must define the function before using it
 We can create a function in python using (def) keyword

4. Create a function
 Example:
def example_function():
print(“welcome from function”)
example_function()

5. Create a function with arguments
 We can pass data, known as parameters, into a function.
 We can use this parameters in the function
 Example:
def example_function(arg):
print(“this is the argument you pass to the function”, arg)
example_function(“ali”)

6. Pass more than one arguments
 We can pass more than one parameters into the function
 We can use this parameters in the function
 Example:
def example_function(arg1,arg2):
print(“this is the argument you pass to the function”, arg)
print(“this is the argument you pass to the function”, arg)
example_function(“ali”,”mohammad”)

7. Pass more than one arguments
 Arbitrary Arguments, *args:
 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.
def my_function(*kids):
print("The youngest child is " + kids[2])
my_function(“Ali", “Mohammad", “Ghadeer")
The Result is: The youngest child is Ghadeer

8. Pass more than one arguments
 Keyword Arguments:
 You can also send arguments with the key = value syntax.
 This way the order of the arguments does not matter.
 Example:
def my_function(child3, child2, child1):
print("The youngest child is " + child3)
my_function(child1 = “Ali", child2 = “Mohammad", child3 = “Ghadeer")
 Result: Ghadeer

9. Pass more than one arguments
 Arbitrary Keyword Arguments, **kwargs:
 If we do not know how many keyword arguments that will be passed into
your function, add two asterisk (**) before the parameter name in the
function definition.
 This way the function will receive a dictionary of arguments, and can
access the items accordingly.
 Example:
def my_function(**kid):
print("His last name is " + kid["lname"])
my_function(fname = “Ali", lname = “Mohammad")

10. Default Parameter values
 The following example shows how to use a default parameter value.
 If we call the function without argument, it uses the default value:
 Example:
def my_function(city = “Homs"):
print("I am from " + city)
my_function(“Damascus")
my_function(“Tartous")
my_function()
my_function(“Hama")

11. Passing a List as an Argument
 You can send any data types of argument to a function (string, number,
list, dictionary etc.), and it will be treated as the same data type inside the
function.
 Example:
def my_function(food):
for x in food:
print(x)
fruits = ["apple", "banana", "cherry"]
my_function(fruits)

12. Create a function and return the value
 To let a function return a value, use the (return) keyword
 Example:
def my_function(x):
return 5 * x
print(my_function(3))
print(my_function(5))
print(my_function(9))

13. Recursion
 Python also accepts function recursion, which means a defined function
can call itself.
 Recursion is a common mathematical and programming concept. It means
that a function calls itself. This has the benefit of meaning that you can
loop through data to reach a result.
 Example:

14. Recursion
def tri_recursion(k):
if(k > 0):
result = k + tri_recursion(k - 1)
print(result)
else:
result = 0
return result
print("Recursion Example Results")
tri_recursion(6)
Result:
1
3
6
10
15
21