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 import ctypes

variable declaration

val = 20

get the memory address of the python

object for variable

print(id(val))

get the memory address of the python

object for list

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

get the memory address of the python

object for tuple

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

get the memory address of the python

object for set

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 import ctypes

variable declaration

val = 20

display variable

print("Actual value -", val)

get the memory address of the python object

for variable

x = id(val)

display memory address

print("Memory address - ", x)

get the value through memory address

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

display

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 import ctypes

variable declaration

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

display variable

print("Actual value -", val)

get the memory address of the python object

for variable list

x = id(val)

display memory address

print("Memory address - ", x)

get the value through memory address

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

display

print("Value - ", a)

print("____________________________________")

variable declaration

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

display variable

print("Actual value -", val)

get the memory address of the python object

for variable tuple

x = id(val)

display memory address

print("Memory address - ", x)

get the value through memory address

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

display

print("Value - ", a)

print("____________________________________")

variable declaration

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

display variable

print("Actual value -", val)

get the memory address of the python object

for variable set

x = id(val)

display memory address

print("Memory address - ", x)

get the value through memory address

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

display

print("Value - ", a)

print("____________________________________")

variable declaration

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

display variable

print("Actual value -", val)

get the memory address of the python object

for variable dictionary

x = id(val)

display memory address

print("Memory address - ", x)

get the value through memory address

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

display

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'}

____________________________________