How to get value from address in Python ? (original) (raw)

Last Updated : 23 Aug, 2021

In this article, we will discuss how to get the value from the address in Python. First, we have to calculate the memory address of the variable or python object which can be done by using the id() function.

Syntax:

id(python_object)

where, python_object is any python variable or data structure like list, tuple set, etc.

Example: Python program to get the memory address of particular python objects

Python3

import ctypes

val = 20

print ( id (val))

print ( id ([ 1 , 2 , 3 , 4 , 5 ]))

print ( id (( 1 , 2 , 3 , 4 , 5 )))

print ( id ({ 1 , 2 , 3 , 4 , 5 }))

Output:

93937093504096 140292920620368 140292954508752 140292954711056

Now that we have addresses, we can get value/python objects again from the memory address using ctypes module.

ctypes stands for compatible data types, which allows calling functions in DLLs or shared libraries. It can be used to wrap these libraries in pure Python. It is used to get the value/Python objects using memory address

Syntax:

ctypes.cast(memory_address,ctypes.py_object).value

where,

• memeory_address is the memory address of the variable
• value is the method which is used to extract a value

Example 1: Python program to access the value from memory address

Python3

import ctypes

val = 20

print ( "Actual value -" , val)

x = id (val)

print ( "Memory address - " , x)

a = ctypes.cast(x, ctypes.py_object).value

print ( "Value - " , a)

Output:

Actual value - 20 Memory address - 93937093504096 Value - 20

Example 2: Python program to get the value from memory address of python data structures

Python3

import ctypes

val = [ 1 , 2 , 3 , 4 , 5 ]

print ( "Actual value -" , val)

x = id (val)

print ( "Memory address - " , x)

a = ctypes.cast(x, ctypes.py_object).value

print ( "Value - " , a)

print ( "____________________________________" )

val = ( 1 , 2 , 3 , 4 , 5 )

print ( "Actual value -" , val)

x = id (val)

print ( "Memory address - " , x)

a = ctypes.cast(x, ctypes.py_object).value

print ( "Value - " , a)

print ( "____________________________________" )

val = { 1 , 2 , 3 , 4 , 5 }

print ( "Actual value -" , val)

x = id (val)

print ( "Memory address - " , x)

a = ctypes.cast(x, ctypes.py_object).value

print ( "Value - " , a)

print ( "____________________________________" )

val = { 'id' : 1 , "name" : "sravan kumar" , "address" : "kakumanu" }

print ( "Actual value -" , val)

x = id (val)

print ( "Memory address - " , x)

a = ctypes.cast(x, ctypes.py_object).value

print ( "Value - " , a)

print ( "____________________________________" )

Output:

Actual value – [1, 2, 3, 4, 5]

Memory address – 140292824840224

Value – [1, 2, 3, 4, 5]

____________________________________

Actual value – (1, 2, 3, 4, 5)

Memory address – 140292853914128

Value – (1, 2, 3, 4, 5)

____________________________________

Actual value – {1, 2, 3, 4, 5}

Memory address – 140292824862304

Value – {1, 2, 3, 4, 5}

____________________________________

Actual value – {‘id’: 1, ‘name’: ‘sravan kumar’, ‘address’: ‘kakumanu’}

Memory address – 140292825009760

Value – {‘id’: 1, ‘name’: ‘sravan kumar’, ‘address’: ‘kakumanu’}

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