What are the built-in functions in Python and what are they used for?

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Jayant Kumar · Accepted Answer

Table of Contants
Introduction
Python comes with a variety of built-in functions that make it easier for developers to perform common tasks such as data conversion, mathematical operations, and handling input/output. These functions are always available and do not require importing external libraries. This guide provides an overview of some of the most commonly used Python built-in functions and their usage with examples.
Common Python Built-in Functions
 Type Conversion Functions
Python provides built-in functions to convert between different data types, ensuring that data is handled appropriately in your programs.

**int()**: Converts a value to an integer.
**float()**: Converts a value to a floating-point number.
**str()**: Converts a value to a string.
**list()**: Converts an iterable (like a tuple or set) into a list.
**tuple()**: Converts an iterable into a tuple.

# Examples of type conversion
x = "10"
print(int(x))   # Converts string to integer
print(float(x)) # Converts string to float

Input/Output Functions
Python's built-in functions for input and output allow interaction with the user and display results.

**input()**: Accepts input from the user as a string.
**print()**: Outputs data to the console.

name = input("Enter your name: ")
print(f"Hello, {name}!")  # Output: Hello, [user's name]!

Mathematical Functions
Python offers several built-in functions to perform mathematical operations without needing to import the math module for basic tasks.

**abs()**: Returns the absolute value of a number.
**min()** and **max()**: Return the smallest and largest values from a list or iterable.
**round()**: Rounds a floating-point number to the nearest integer or specified decimal place.

print(abs(-10))      # Output: 10
print(min(5, 3, 8))  # Output: 3
print(round(3.567, 2)) # Output: 3.57

. Sequence Handling Functions
Python provides several built-in functions to manipulate and handle sequences such as lists, tuples, and strings.

**len()**: Returns the length of an object (e.g., list, string, or tuple).
**sorted()**: Returns a new sorted list from the items in an iterable.
**sum()**: Adds up the elements in an iterable.

my_list = [3, 1, 4, 1, 5]
print(len(my_list))      # Output: 5
print(sorted(my_list))   # Output: [1, 1, 3, 4, 5]
print(sum(my_list))      # Output: 14

Object and Type Inspection Functions
These functions are useful for checking the type or properties of an object in Python.

**type()**: Returns the type of an object.
**isinstance()**: Checks if an object is an instance of a specific class or type.

x = 10
print(type(x))               # Output: &#x3C;class 'int'>
print(isinstance(x, int))    # Output: True

Practical Examples
Example : Validating User Input with isinstance()
You can use isinstance() to ensure the user provides valid input of a specific type, such as integers.
def get_positive_number():
    num = input("Enter a positive number: ")
    try:
        num = int(num)
        if isinstance(num, int) and num > 0:
            print(f"Valid input: {num}")
        else:
            print("Please enter a positive integer.")
    except ValueError:
        print("Invalid input. Please enter a number.")

Example : Summing a List of Numbers
Using sum() to calculate the total of a list of numbers.
numbers = [5, 10, 15]
total = sum(numbers)
print(f"The total is: {total}")  # Output: The total is: 30

Conclusion
Python's built-in functions make coding faster, easier, and more readable. Whether you are converting data types, performing calculations, or handling input/output operations, these functions provide essential utilities that you can leverage without importing additional libraries. Understanding and using Python’s built-in functions is fundamental for writing efficient and maintainable code.

What are the built-in functions in Python and what are they used for?

Table of Contants

Introduction

Common Python Built-in Functions

Type Conversion Functions

Input/Output Functions

Mathematical Functions

. Sequence Handling Functions

Object and Type Inspection Functions

Practical Examples

Example : Validating User Input with `isinstance()`

Example : Summing a List of Numbers

Conclusion

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