Python - Examples of Common Built-in Functions

Examples of Common Built-in Functions in Python 

Python offers a rich set of built-in functions that are always available for use, without the need for imports. These functions provide a wide range of capabilities, such as type conversion, mathematical calculations, sequence processing, and more. This guide will walk through many of the most commonly used built-in functions in Python with syntax explanations and practical examples.

Introduction to Built-in Functions

Built-in functions in Python are predefined in the Python interpreter. They help simplify programming tasks by providing convenient functionality that is ready to use. There are over 60 built-in functions, but here we will cover the most frequently used ones across different areas of development.

1. Type Conversion Functions

int()

Converts a number or a string to an integer.

x = int("10")  # Output: 10

float()

Converts an integer or string to a floating-point number.

y = float("3.14")  # Output: 3.14

str()

Converts an object to a string.

z = str(123)  # Output: "123"

bool()

Returns the boolean value of an object.

print(bool(0))      # False
print(bool("abc"))  # True

list()

Converts an iterable (like a string or tuple) to a list.

lst = list("hello")  # Output: ['h', 'e', 'l', 'l', 'o']

tuple()

Converts an iterable to a tuple.

tpl = tuple([1, 2, 3])  # Output: (1, 2, 3)

set()

Returns a set object from an iterable, removing duplicates.

s = set([1, 2, 2, 3])  # Output: {1, 2, 3}

dict()

Creates a dictionary object.

d = dict(name="Alice", age=30)  # Output: {'name': 'Alice', 'age': 30}

2. Mathematical Functions

abs()

Returns the absolute value of a number.

print(abs(-5))  # Output: 5

round()

Rounds a number to a given precision in decimal digits.

print(round(3.456, 2))  # Output: 3.46

pow()

Returns the power of a number.

print(pow(2, 3))  # Output: 8

divmod()

Returns a tuple of quotient and remainder.

print(divmod(9, 2))  # Output: (4, 1)

3. Sequence and Collection Functions

len()

Returns the number of items in a sequence.

print(len("Python"))  # Output: 6

sum()

Returns the total sum of all elements in an iterable.

print(sum([1, 2, 3]))  # Output: 6

min()

Returns the smallest item in an iterable.

print(min([1, 2, 3]))  # Output: 1

max()

Returns the largest item in an iterable.

print(max([1, 2, 3]))  # Output: 3

sorted()

Returns a new sorted list.

print(sorted([3, 1, 2]))  # Output: [1, 2, 3]

reversed()

Returns an iterator that accesses the given sequence in the reverse order.

print(list(reversed([1, 2, 3])))  # Output: [3, 2, 1]

4. Utility Functions

type()

Returns the type of an object.

print(type(5))  # Output: <class 'int'>

id()

Returns the identity of an object.

a = 10
print(id(a))

isinstance()

Checks if an object is of a certain type.

print(isinstance("Hello", str))  # Output: True

callable()

Checks if the object appears callable (like a function).

print(callable(len))  # Output: True

5. Input/Output Functions

input()

Takes input from the user.

name = input("Enter your name: ")
print("Hello", name)

print()

Prints the given object(s) to the standard output.

print("Hello", "World", sep=", ")

6. Functional Programming Helpers

map()

Applies a function to every item of an iterable.

def square(x): return x*x
print(list(map(square, [1, 2, 3])))

filter()

Filters items out of an iterable using a function that returns True or False.

def is_even(n): return n % 2 == 0
print(list(filter(is_even, [1, 2, 3, 4])))

zip()

Combines two or more iterables into tuples.

a = [1, 2, 3]
b = ['a', 'b', 'c']
print(list(zip(a, b)))  # Output: [(1, 'a'), (2, 'b'), (3, 'c')]

enumerate()

Adds an index to an iterable.

for index, value in enumerate(["apple", "banana"]):
    print(index, value)

7. Advanced Functions

eval()

Evaluates a string as Python code.

x = 1
print(eval("x + 1"))  # Output: 2

exec()

Executes Python code dynamically.

exec("for i in range(3): print(i)")

compile()

Compiles source into a code or AST object.

code = compile('a + b', 'file', 'eval')
print(eval(code, {'a': 1, 'b': 2}))

8. Object and Attribute Functions

hasattr()

Checks if an object has a given attribute.

class Person:
    name = "Alice"

print(hasattr(Person, "name"))  # Output: True

getattr()

Returns the value of the named attribute.

print(getattr(Person, "name"))  # Output: Alice

setattr()

Sets the value of the named attribute.

setattr(Person, "age", 25)
print(Person.age)

delattr()

Deletes the named attribute.

delattr(Person, "age")

Built-in functions in Python are a powerful feature that simplifies many common programming tasks. From type conversions and mathematical calculations to working with collections and introspecting objects, these functions improve code readability and efficiency. Mastering these built-in functions is essential for becoming a proficient Python developer.

In this guide, we’ve explored over 30 common Python built-in functions. Remember, Python’s official documentation offers a full list of built-in functions that can further enhance your development workflow. Experiment with these functions to fully understand their potential in various applications, from simple scripts to complex data processing pipelines.