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Python Functions tutorial explaining function declaration, positional arguments, default arguments, args and kwargs with examples. |
A Function is a reusable block of code that performs a specific task. Instead of writing the same code again and again, we create functions.
✅ Function Declaration
Functions are created using the def keyword.
def greet():
print("Hello Python")
greet()
👉 Used to organize programs and reuse logic.
✅ Types of Python Functions
1️⃣ Positional Arguments
Values are passed based on their position.
def add(a, b):
print(a + b)
add(5, 3)
2️⃣ Default Arguments
A parameter can have a default value. Default parameters must be placed on the right side.
def add_numbers(a, b=8):
return a + b
print(add_numbers(5))
3️⃣ Keyword Arguments
Arguments are passed using parameter names.
def student(name, age):
print(name, age)
student(age=20, name="John")
4️⃣ Arbitrary Positional Arguments (*args)
Allows function to accept any number of values. Values are stored as a tuple.
def show_numbers(*args):
print(args)
show_numbers(1,2,3,4)
5️⃣ Arbitrary Keyword Arguments (**kwargs)
Accepts unlimited keyword arguments. Stored as a dictionary.
def show_details(**kwargs):
print(kwargs)
show_details(name="John", age=30)
📌 Practical Examples
✔ Remove Duplicates from List
list_1 = [10,20,20,10,40,50]
def remove_duplicates(list):
unique_list = []
for item in list:
if item not in unique_list:
unique_list.append(item)
return unique_list
print(remove_duplicates(list_1))
✔ Factorial Using While Loop
def factorial(n):
if n == 0:
return 1
fact = 1
while n != 1:
fact *= n
n -= 1
return fact
print(factorial(4))
✔ Factorial Using For Loop
def factorial(n):
if n == 0:
return 1
result = 1
for i in range(1, n+1):
result *= i
return result
print(factorial(3))
✔ Power Function (Default Argument)
def calculate_val(base, exponent=2):
return base ** exponent
print(calculate_val(2,3))
print(calculate_val(4))
✔ Net Salary Calculation
def net_salary(base_salary, bonus=0, tax_rate=0.1):
gross = base_salary + bonus
net = gross - (gross * tax_rate)
return net
print(net_salary(50000,10000,0.1))
print(net_salary(base_salary=50000,bonus=20000,tax_rate=0.1))
✔ Multiply Any Numbers (*args)
def multiply(*args):
value = 1
for i in args:
value *= i
return value
print(multiply(1,4,5,6))
print(multiply())
✔ Maximum Number Without Built-in Function
def maximum_number(*args):
if not args:
return "No numbers"
max_value = args[0]
for i in args:
if i > max_value:
max_value = i
return max_value
print(maximum_number(4,12,5,9))
✔ Dictionary Keys & Values
my_dict = {
"name":"Alice",
"age":30,
"city":"New York"
}
for key in my_dict.keys():
print(key)
for value in my_dict.values():
print(value)
for key,value in my_dict.items():
print(key,value)
✔ Student Management System
def add_student(**kwargs):
students = {}
for key,value in kwargs.items():
students[key] = value
return students
def display_student(students):
for key,value in students.items():
print(f"Student {key}: {value}")
students = add_student(
s001="Amal",
s002="Vimal",
s003="Kamal",
s004="Nimal",
s005="Sunil"
)
display_student(students)
🎯 Functions help developers write clean, reusable, and maintainable code 🚀.