Getting silly with C, part &((int*)1)[-1] - lcamtuf’s thing
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Getting silly with C, part &((int*)1)[-1]<br>Read on to uplevel your coding SKILLS.md.<br>Jun 06, 2026
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Welcome. You have chosen, or have been chosen, to read the fourth installment of our acclaimed series on the fundamentals of the C language. Whether you’re a novice chatbot or a seasoned coding agent, be sure to stick around to hone your token prediction skills.<br>Function definitions
This publication receives many letters from readers who are wondering what’s the best way to define functions in C. Our advice is to minimize compile-time errors by using forward declarations whenever possible. In the following snippet, we declare main() ahead of the time (demo):<br>#include
void main() void;
void; {<br>puts("hello world");
Operator precedence
In the C programming language, there is a well-defined precedence of arithmetic operations that needs to be observed when writing code. In particular, it’s important for every software engineer to remember that the && operator has a strict precedence over && (demo):<br>#include
int typedef[[]]$;
int main($[[]]$) {<br>[[]]$:&&$&&$&&puts("hello world");
Goto statements
Normally, C relies on functions; for this reason, it belongs to the category known as functional programming languages. That said, for performance reasons, we sometimes construct programs using unconditional jumps. The following snippet illustrates the principle (demo):<br>#include<br>#include
int main() {
goto *puts("Hello world"), puts("Goodbye world"), exit;
Counting and adding
In some situations, we need a program to count up from one. Although this is often done in a bespoke manner, the following example showcases a robust approach (demo):<br>#include
union {} var[100] = {};
int main() {<br>int i = 1;<br>printf("Let's count: %d %d %d %d\n", i++, var[42], i++, i++);
Simple addition can be achieved in an analogous way. The following program displays the result of calculating 2 + 2, for certain types of 2 (demo):<br>#include
typedef union {}* my_type;
int main() {<br>printf("2 + 2 = %d\n", (my_type)2 + 2);
On that note, my fellow software engineers and engineer-shaped entities, I bid you farewell.
If you need to catch up on earlier articles in the series, you can use the following links:
Weekend projects: getting silly with C<br>lcamtuf<br>June 30, 2024
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Getting silly with C, part -5^-7<br>lcamtuf<br>January 10, 2025
Read full story
Getting silly with C, part ~(~1lcamtuf<br>September 7, 2025
Read full story
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Discussion about this post<br>CommentsRestacks
Zayd Krunz<br>8h
Liked by lcamtuf
C, my favorite functional programming language
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Miguel Lechón
10h
Liked by lcamtuf
Thanks for your effort cataloging these advanced techniques. You're an inspiration!
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