Python Built-in functions

Built-in functions of Python are predefined functions that are always available without the need to import any additional modules. They offer a vast range of utilities for input/output, mathematical calculations, sequence manipulations, type conversion, and much more. They save time and make common operations easy.

Main features of Built-in functions

Always Available: No imports are necessary.
Versatile: Implements a variety of tasks such as math, I/O, string handling.
Optimized: Efficient and strong implementations.
Dynamic: It can work on various data types (polymorphism).

1. Input/Output

print(*objects, sep=' ', end='\n', file=sys.stdout, flush=False)
Displays output to the console.
Example:

print("Hello", "World", sep=", ", end="!\n") # Output: Hello, World!

input(prompt=None)
Takes input from the user and returns it as a string.
Example:

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

2. Type Conversion

int(x, base=10)
Converts x to an integer.
Example:

int("123") # Output: 123
int("101", 2) # Output: 5

float(x)
Converts x to a floating-point number.
Example:

float("3.14") # Output: 3.14

str(x)
Converts x to a string.
Example:

str(123) # Output: "123"

bool(x)
Converts x to a boolean value (True or False).
Example:

bool(0) # Output: False
bool(1) # Output: True

3. Mathematical Functions

abs(x)
Returns the absolute value of x.
Example:

abs(-5) # Output: 5

pow(x, y, z=None)
Calculates x raised to the power y (x^y). If z is provided, computes (x^y) % zv.
Example:

pow(2, 3) # Output: 8
pow(2, 3, 5) # Output: 3

round(number, ndigits=None)
Rounds number to ndigits decimal places.
Example:

round(3.14159, 2) # Output: 3.14

divmod(a, b)
Returns a tuple (a // b, a % b).
Example:

divmod(10, 3) # Output: (3, 1)

4. Sequence Operations

len(s)
Returns the number of items in a sequence.
Example:

len("Python") # Output: 6
len([1, 2, 3]) # Output: 3

min(iterable, *[, key, default])
Returns the smallest item in an iterable.
Example:

min([3, 1, 4]) # Output: 1

max(iterable, *[, key, default])
Returns the largest item in an iterable.
Example:

max([3, 1, 4]) # Output: 4

sum(iterable, start=0)
Returns the sum of a sequence.
Example:

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

5. Object Inspection

type(object)
Returns the type of object.
Example:

type(123) # Output: <class 'int'>

id(object)
Returns the memory address of object.
Example:

id(123) # Output: A unique integer

dir([object])
Lists attributes and methods of object (or current scope if omitted).
Example:

dir(str) # Lists methods of the string class

6. Advanced Functions

enumerate(iterable, start=0)
Returns an iterator of tuples (index, value).
Example:

for i, v in enumerate(["a", "b", "c"]):
   print(i, v)
# Output:
# 0 a
# 1 b
# 2 c

zip(*iterables)
Combines multiple iterables into tuples.
Example:

list(zip([1, 2], ['a', 'b'])) # Output: [(1, 'a'), (2, 'b')]

map(function, iterable)
Applies function to every item of iterable.
Example:

list(map(str.upper, ['a', 'b', 'c'])) # Output: ['A', 'B', 'C']

filter(function, iterable)
Filters items in iterable where function returns True.
Example:

list(filter(lambda x: x > 2, [1, 2, 3])) # Output: [3]

7. Miscellaneous

help([object])
Displays help documentation for object.
Example:

help(print) # Shows documentation for the print function

isinstance(object, classinfo)
Checks if object is an instance of classinfo.
Example:

isinstance(123, int) # Output: True

sorted(iterable, key=None, reverse=False)
Returns a sorted list from the items in iterable.
Example:

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

Python’s built-in functions form the foundation of everyday programming tasks. They improve efficiency, readability, and simplicity so that developers can focus on solving complex problems rather than reinventing the wheel.