Low-Level Mastery: The Mechanics of Pointer Arithmetic

Miraly — Wed, 25 Feb 2026 20:31:21 +0000

0. Introduction

Imagine a program that manipulates memory with the precision of a grandmaster moving pieces on a chessboard. This capability is granted to developers through pointer arithmetic. Let’s explore the underlying mechanics of this powerful tool.

1. The Pointer: A Foundation

A pointer is a variable that stores the memory address of an object. Through a pointer, you can perform any operation that you would on the object directly: reading, writing, and lifecycle management.

A key distinction in C++ is the member access operator (->). When dealing with pointers to structs or classes, -> is used to dereference the pointer and access the member in a single step:

struct Car {
    int speed{};
};

Car* ptr = new Car;
ptr->speed = 150; // Syntactic shorthand for (*ptr).speed
std::cout << ptr->speed << std::endl;

delete ptr;

2. Dynamic Arrays and Syntactic Sugar

Pointers allow for the creation of dynamic arrays whose size is determined at runtime. While the subscript operator [] is standard, it is essentially "syntactic sugar" for pointer arithmetic.

Let’s examine a pure C implementation that bypasses the sugar to manipulate memory directly:

#include <stdio.h>
#include <stdlib.h>

int main() {
    // Allocate memory for 10 integers
    int* arr = (int*)malloc(10 * sizeof(int));

    if (arr == NULL) return 1; // Error handling: a must for senior code

    for (int i = 0; i < 10; ++i) {
        *(arr + i) = i; // Direct pointer arithmetic
    }

    free(arr);
    return 0;
}

3. The Scale Factor

Why do we use (arr + i) instead of manually calculating the byte offset like *(arr + i * 4)?
The compiler handles this through type-based scaling. When you increment an int, the address increases by sizeof(int). This abstraction ensures that the developer focuses on logic rather than manual memory offsets.

4. Arrays vs. Pointers: Key Distinctions

While arrays often "decay" into pointers when passed to functions, they are not identical:
• Allocation: Stack-allocated arrays have a fixed size at compile-time. Pointers can manage heap memory of arbitrary size.
• Mutatibility: A pointer is a variable that can be reassigned; an array name acts as a constant pointer to the first element.
• Performance: At the assembly level, arr[i] and *(arr + i) result in the same machine instructions. The difference lies solely in memory management and scope.

5. Real-World Applications and Critical Risks

Pointer arithmetic is the backbone of high-performance engineering:
• Data Processing: Efficiently traversing large datasets, buffers, or image pixels.
• System Architecture: Implementing complex data structures (trees, graphs) and custom memory allocators.
• Security & Red Teaming: Developing exploits and performing memory forensics.

Common Pitfalls:

Buffer Overflows: Accessing memory outside of allocated bounds leads to Undefined Behavior.
Memory Leaks: Failing to deallocate memory, leading to resource exhaustion.
Dangling Pointers: Attempting to dereference memory that has already been freed.

End

The pointer in C/C++ is like fire. In the right hands, it's a powerful and very useful weapon, but fire in the hands of a fool will cause his own house to crumble.

That's all, I hope you learned something new.

Bootstrapping: A compiler written in its own language

Miraly — Tue, 24 Feb 2026 00:28:58 +0000

Bootstrapping: A sign of the maturity of programming languages

Bootstrapping is the process by which a programming language or its compiler is written in the same language. This is an indicator of his maturity.

What language are compilers written in?
For example, many people believe that C++ is written in C, and this is true, but only partially. In the past, the first versions of C++ were indeed written in C, but today languages like C, C++, Java, Rust and Go are largely written in themselves. Interestingly, the nasm assembler compiler is written in C. Many might assume that it is written in "zeros and ones", but this is not the case.

The value of Bootstrapping

Bootstrapping demonstrates that the language has sufficient flexibility and maturity to support its own implementation. It also means that the language can serve projects of various levels of complexity, from small scripts to large systems. For example, Rust, written on its own, is actively used to create secure and efficient software, from embedded systems to server applications.

Varieties of Python

You've probably asked yourself if Python is written in Python. The main version of Python, CPython, is indeed written in C, as are most of its libraries. However, there is also a version of Python written in Python — PyPy. Although Python is not by nature the fastest language, PyPy is significantly faster than CPython thanks to JIT-compilation (Just-In-Time). This process optimizes code execution during its execution, which can lead to significant performance gains, but also requires more RAM than a Java virtual machine.

There are also alternatives:
Jython, a version written in Java that allows you to use Java libraries directly from the Python code. However, it does not support all the features of Python, such as some C extension modules.
IronPython is a version for .NET that allows you to use .NET libraries and create interfaces with applications on the .NET platform.

Besides these options, there are others such as:

MicroPython
CircuitPython
Brython
Transcrypt
Stackless Python
Pyjamas
Nuitka
Pyston

Conclusion

Bootstrapping is a sign of the maturity of the language. If the compiler or interpreter of a language is written in the same language, this indicates the quality and development of the language.

Hi! My name is Mirali. I study hacking and low-level development, going down to the very bottom to see what lies behind a ton of layers of abstractions. I write in Asm, C, C++, and also use scripting languages: Python and JavaScript. This is my first post, and I'd be interested to know which versions of Python you prefer and why. Subscribe if you want to learn more about low-level programming or hacking!

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