`dir()` Function in Python [ English ]

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1. Introduction

The dir() function in Python is a built-in function used to list the names of attributes and methods of an object. It helps programmers explore the properties, variables, and functions available in modules, classes, or objects.

dir() is commonly used in interactive Python sessions and during program development to understand what operations can be performed on a particular object.

2. Syntax

dir(object)

Parameter

• object (optional) – The object whose attributes and methods need to be listed.

Return Value

• Returns a list of strings containing the names of attributes and methods associated with the object.

3. Using dir() Without Arguments

If dir() is called without any argument, it returns the list of names defined in the current local scope.

a = 10
b = 20

print(dir())

Output (example)

['__annotations__', '__builtins__', '__name__', 'a', 'b']

Explanation

• The output shows the names of variables (a, b) and other built-in names available in the current environment.

4. Using dir() With an Object

dir() can be used to see all available methods and attributes of an object.

text = "Python"

print(dir(text))

Output (partial)

['capitalize', 'casefold', 'center', 'count', 'encode',
 'endswith', 'find', 'format', 'index', 'join', 'lower', 'replace']

Explanation

• The function returns a list of string methods that can be applied to the variable text.

Example:

print(text.upper())

Output:

PYTHON

5. Example with List Object

numbers = [1, 2, 3]

print(dir(numbers))

Output (partial)

['append', 'clear', 'copy', 'count', 'extend', 'index',
 'insert', 'pop', 'remove', 'reverse', 'sort']

Explanation

• The result shows all the methods available for list objects.

Example usage:

numbers.append(4)
print(numbers)

Output:

[1, 2, 3, 4]

6. Example with a Module

dir() can also be used to see the contents of a module.

import math

print(dir(math))

Output (partial)

['acos', 'asin', 'atan', 'ceil', 'cos', 'factorial',
 'floor', 'log', 'pi', 'pow', 'sqrt', 'tan']

Explanation

• The output shows functions and constants available in the math module, such as sqrt, pi, and factorial.

Example:

print(math.sqrt(25))

Output:

5.0

7. Practical Use of dir()

The dir() function is useful for:

• Exploring objects and modules
• Learning available methods
• Debugging programs
• Understanding unfamiliar libraries

For example, when using a new library, dir() helps discover available functions.

8. Summary

• dir() is a built-in Python function used to list attributes and methods of objects.
• It returns a list of names available in an object.
• When used without arguments, it lists names in the current scope.
• It is commonly used for program exploration and debugging.