Skip to content
Related Articles

Related Articles

Viewing all defined variables in Python
  • Last Updated : 11 Dec, 2020

In this article, we are going to discuss how to view all defined variables in Python. Viewing all defined variables plays a major role while debugging the code.

Method 1: Using dir() function

dir() is a built-in function to store all the variables inside a program along with the built-in variable functions and methods. It creates a list of all declared and built-in variables. There are two different ways to view all defined variables using dir( ). They are discussed below.

When no user-defined variable starts with ‘__’ :

  • Define some variables of various types that are not starting with ‘__’
  • Call dir and store it in a variable. It stores all the variable names defined before in the form of a list and stores the variable names as a string.
  • Iterate over the whole list where dir( ) is stored.
  • Print the item if it doesn’t start with ‘__’

Example:



Python3




# Define some variables of various types
# that are not starting with '__'
var2 = "Welcome to geeksforgeeks"
var3 = {"1": "a", "2": "b"}
var4 = 25
var5 = [1, 2, 3, 4, 5]
var6 = (58, 59)
  
# call dir and store it in a variable.
# It stores all the variable names defined
# before in the form of a list
# and stores the variable names as a string.
all_variables = dir()
  
# Iterate over the whole list where dir( )
# is stored.
for name in all_variables:
    
    # Print the item if it doesn't start with '__'
    if not name.startswith('__'):
        myvalue = eval(name)
        print(name, "is", type(myvalue), "and is equal to ", myvalue)

Output:

var2 is <class ‘str’> and is equal to  Welcome to geeksforgeeks

var3 is <class ‘dict’> and is equal to  {‘1’: ‘a’, ‘2’: ‘b’}

var4 is <class ‘int’> and is equal to  25

var5 is <class ‘list’> and is equal to  [1, 2, 3, 4, 5]

var6 is <class ‘tuple’> and is equal to  (58, 59)

Storing the built-in variables and ignoring them

  • Create a new variable and store all built-in functions within it using dir( ).
  • Define some variables of various types.
  • Again call dir and store it in a list subtracting the built-in variables stored previously.
  • Iterate over the whole list.
  • Print the desired items

Example:



Python3




# Create a new variable and store all
# built-in functions within it using dir( ).
not_my_data = set(dir())
  
# Define some variables of various types.
var2 = "Welcome to geeksforgeeks"
var3 = {"1": "a", "2": "b"}
var4 = 25
var5 = [1, 2, 3, 4, 5]
var6 = (58, 59)
  
# Again call dir and store it in a list 
# subtracting the built-in variables stored
# previously.
my_data = set(dir()) - not_my_data
  
# Iterate over the whole list is stored.
for name in my_data:
    
    # Exclude the un-necessary variable named not_my_data
    if name != "not_my_data":
        val = eval(name)
        print(name, "is", type(val), "and is equal to ", val)

Output:

var2 is <class ‘str’> and is equal to  Welcome to geeksforgeeks

var3 is <class ‘dict’> and is equal to  {‘1’: ‘a’, ‘2’: ‘b’}

var6 is <class ‘tuple’> and is equal to  (58, 59)

var4 is <class ‘int’> and is equal to  25

var5 is <class ‘list’> and is equal to  [1, 2, 3, 4, 5]

Method 2: To print local and global variables 

Locals() is a built-in function that returns a list of all local variables in that particular scope. And globals() does the same with the global variables.

Approach 

  • Create a list of all global variables using globals( ) function, to store the built-in global variables.
  • Declare some global variables
  • Declare a function.
  • Declare some local variables inside it.
  • Store all the local variables in a list, using locals keyword.
  • Iterate over the list and print the local variables.
  • Store the global variables in a list using globals keyword and subtract the previously created list of built-in global variables from it.
  • Print them.
  • Call the function.

Example:

Python3




# Create a list of all global variables using
# globals( ) function, To store the built-in
# global variables.
not_my_data = set(globals())
  
# Declare some global variables
foo5 = "hii"
foo6 = 7
  
# Declare a function.
def func():
    
    # Declare some local variables inside it.
    var2 = "Welcome to geeksforgeeks"
    var3 = {"1": "a", "2": "b"}
    var4 = 25
    var5 = [1, 2, 3, 4, 5]
    var6 = (58, 59)
  
    # Store all the local variables in a list,
    # using locals keyword.
    locals_stored = set(locals())
      
    # Iterate over the list and print the local
    # variables.
    print("Printing Local Variables")
    for name in locals_stored:
        val = eval(name)
        print(name, "is", type(val), "and is equal to ", val)
  
    # Store the global variables in a list using 
    # globals keyword and subtract the previously
    # created list of built-in global variables from it.
    globals_stored = set(globals())-not_my_data
      
    # Print the global variables
    print("\nPrinting Global Variables")
    for name in globals_stored:
        
        # Excluding func and not_my_data as they are 
        # also considered as a global variable
        if name != "not_my_data" and name != "func":
            val = eval(name)
            print(name, "is", type(val), "and is equal to ", val)
  
  
# Call the function.
func()

Output:

Printing Local Variables

var2 is <class ‘str’> and is equal to  Welcome to geeksforgeeks

var6 is <class ‘tuple’> and is equal to  (58, 59)

var4 is <class ‘int’> and is equal to  25

var5 is <class ‘list’> and is equal to  [1, 2, 3, 4, 5]

var3 is <class ‘dict’> and is equal to  {‘1’: ‘a’, ‘2’: ‘b’}

Printing Global Variables

foo6 is <class ‘int’> and is equal to  7

foo5 is <class ‘str’> and is equal to  hii

Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course.

My Personal Notes arrow_drop_up
Recommended Articles
Page :