Introduction

Accessing an object's memory address means different things in different languages. In C and C++, addresses are part of normal programming. In Python, Java, and most managed runtimes, the runtime hides most of that detail because identity and lifetime are handled differently.

Low-Level Languages Expose Addresses Directly

In C and C++, objects occupy memory locations and the language exposes them through pointers.

1#include <iostream>
2
3int main() {
4    int value = 42;
5    int* ptr = &value;
6
7    std::cout << "address: " << ptr << '\n';
8    std::cout << "value: " << *ptr << '\n';
9}

The & operator returns the object's address, and the pointer can then be dereferenced. This is powerful, but it also means you must manage lifetime and aliasing carefully.

Python Gives Identity, Not a General Pointer API

Python does not expose raw pointers in normal code. The closest common tool is id(obj).

value = {"name": "Ava"}
print(id(value))

In CPython, that number is usually the memory address of the object header. But that is an implementation detail, not a guaranteed language rule across all Python runtimes.

So id() is useful for:

• Checking whether two names refer to the same object.
• Debugging accidental object reuse.
• Understanding identity versus equality.

It is not a safe substitute for low-level pointer work.

Identity Versus Equality in Python

Many "address" questions in Python are really identity questions.

1a = [1, 2, 3]
2b = [1, 2, 3]
3c = a
4
5print(a == b)   # same value
6print(a is b)   # different object
7print(a is c)   # same object
8print(id(a), id(b), id(c))

This is usually the right mental model in Python: compare value with == and identity with is.

Managed Languages Do Not Promise Stable Addresses

Languages such as C# and Java often move objects during garbage collection. Because of that, a stable public "memory address" concept is not usually part of normal application code.

In C#, you can access addresses in unsafe contexts:

1unsafe
2{
3    int value = 42;
4    int* ptr = &value;
5    Console.WriteLine((nint)ptr);
6}

But this is a specialized feature, not normal application design.

When Accessing an Address Is Legitimate

Addresses are useful in a few specific scenarios:

• Interop with native libraries.
• Systems programming.
• Debugging memory corruption.
• Understanding object aliasing in C or C++.

They are usually the wrong tool for:

• Business object identifiers.
• Serialization keys.
• Application-level equality checks.
• Cross-process references.

If the problem is really about identity, ownership, or equality, solve that directly instead of using an address as a shortcut.

Lifetime Is More Important Than the Address Itself

Getting an address is easy. Using it safely is the real challenge.

Common bugs include:

• Returning a pointer to a local stack variable.
• Keeping a pointer after the object is destroyed.
• Assuming address stability across GC in managed runtimes.
• Treating CPython behavior as if it were universal Python behavior.

Without lifetime discipline, an address is just a dangerous implementation detail.

Debugging With Addresses

Addresses can still be useful in diagnostics. In C++, printing two pointers quickly confirms whether two references point to the same object.

1#include <iostream>
2
3struct User {
4    int id;
5};
6
7int main() {
8    User user{7};
9    User* a = &user;
10    User* b = &user;
11
12    std::cout << a << '\n';
13    std::cout << b << '\n';
14}

If both pointer values match, both variables refer to the same underlying object.

Common Pitfalls

• Treating Python id() as a portable pointer API.
• Using addresses as persistent identifiers.
• Confusing identity and value equality.
• Ignoring lifetime rules when storing pointers in C or C++.
• Expecting managed runtimes to provide stable object addresses by default.

Summary

• Memory addresses are a normal concept in C and C++, but mostly abstracted away elsewhere.
• In Python, id() is best understood as an identity tool, not a low-level pointer feature.
• In managed runtimes, direct address access is restricted because objects may move.
• Raw addresses matter mainly in systems code, interop, and low-level debugging.
• Most application code should reason about identity, equality, and ownership instead of addresses.