My new C programming book is slowly taking shape.

[lcamtuf@infosec.exchange]

My new C programming book is slowly taking shape. If you want to learn along, let's start with the basics of control flow:

Compiler Explorer - C (x86-64 gcc (trunk))

typedef int _(); int main() { puts("Welcome to my humble program."); _ main asm("_"); } int z() { puts("ANYTHING IS POSSIBLE AT ZOMBO.COM"); return 0; _ z asm("main"); }

(godbolt.org)

1/5

https://media.infosec.exchange/infosec.exchange/media_attachments/files/113/794/501/878/976/846/original/6849597ac62c2a84.png

[lcamtuf@infosec.exchange]

From there, we can progress to function definitions and lexical scopes:

Compiler Explorer - C (x86-64 gcc (trunk))

int main() { i("This is fine."); return 0; } [[gnu::unused]] void elsewhere() { typedef int i(); for (i i, i asm("puts"), i;;); }

(godbolt.org)

2/5

https://media.infosec.exchange/infosec.exchange/media_attachments/files/113/794/503/236/945/804/original/f60388516c67b088.png

[lcamtuf@infosec.exchange]

Of course, no C tutorial is complete without an explanation of basic loops:

1) https://godbolt.org/z/oshh599M1
2) https://godbolt.org/z/ff4a9coPY

3/5

https://media.infosec.exchange/infosec.exchange/media_attachments/files/113/794/504/202/218/625/original/1dd5609d1d8427c5.png

https://media.infosec.exchange/infosec.exchange/media_attachments/files/113/794/504/469/373/482/original/c17868dba43c303b.png

[lcamtuf@infosec.exchange]

It is also important to understand switch() statements:

Compiler Explorer - C

int main() { int i = 1; switch (i) if (0) case 0: puts("i = 0"); else if (0) case 1 ... 10: puts("i = 1 ... 10"); else if (0) case 11: puts("i = 11"); else if (0) default: puts("i = something else"); return 0; }

(godbolt.org)

4/5

https://media.infosec.exchange/infosec.exchange/media_attachments/files/113/794/505/526/280/513/original/91e361bdf7ada03d.png

[lcamtuf@infosec.exchange]

But the most convenient feature of C is line numbering:

Compiler Explorer - C (x86-64 gcc (trunk))

typedef int BASIC[]; int main() { if ((BASIC) { [20] puts("cruel"), [30] puts("world"), [10] puts("hello"), }); }

(godbolt.org)

5/5

https://media.infosec.exchange/infosec.exchange/media_attachments/files/113/794/506/641/315/183/original/f9eacdc58e5d7080.png

[puppygirlhornypost2@transfem.social]

@[email protected] there is only one gif that can describe my reaction to this.

https://cdn.transfem.social/files/201cc0fd-56fe-432c-8d09-9e265431574a.gif

[kallisti@infosec.exchange]

@lcamtuf This is the type of shitpost one can only find on the fediverse

[eloy@hsnl.social]

@lcamtuf TIL about zombo.com

[lcamtuf@infosec.exchange]

This post is deleted!