Python 中如何从地址中获取值？
在本文中，我们将讨论如何在 Python 中从地址中获取值。首先，我们要计算变量或 python 对象的内存地址，这可以通过使用 id() 函数来完成。
语法:
id(python_object)
其中，python_object 是任何 python 变量或数据结构，如列表、元组集等。
示例:获取特定 python 对象内存地址的 Python 程序
Python 3
#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}))
输出:
93937093504096
140292920620368
140292954508752
140292954711056
现在我们有了地址，我们可以使用 ctypes 模块再次从内存地址中获取 value/python 对象。
ctypes 代表兼容的数据类型，它允许在 dll 或共享库中调用函数。它可以用来用纯 Python 包装这些库。它用于使用内存地址获取值/Python 对象
语法:
ctypes.cast(memory_address，ctypes.py_object)。价值
哪里，
- memeory _ address 是变量的内存地址
- 值是用于提取值的方法
示例 1: Python 程序从内存地址访问值
Python 3
#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)
输出:
Actual value - 20
Memory address - 93937093504096
Value - 20
示例 2: Python 程序从 Python 数据结构的内存地址中获取值
Python 3
#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("____________________________________")
输出:
实际值–[ 1，2，3，4，5]
内存地址–140292824840224
值–[ 1，2，3，4，5]
实际值–( 1，2，3，4，5)
内存地址–140292853914128
值–( 1，2，3，4，5)
实际值–{ 1，2，3，4，5}
内存地址–140292824862304
价值–{ 1，2，3，4，5}
实际值–{ ' id ':1，' name': 'sravan kumar '，' address': 'kakumanu'}
内存地址–140292825009760
value –{ ' id ':1，' name': 'sravan kumar '，' address': 'kakumanu'}
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