====== C Language ======

====== Things i should read up on ======

  * [[https://en.cppreference.com/w/c/language/operator_precedence|Operator precedence order]]
  * [[https://en.cppreference.com/w/c/language/eval_order|Evaluation order]]
  * [[http://c-faq.com/index.html|C FAQ]]
  * [[https://www.agner.org/optimize/calling_conventions.pdf|C++ ABI]] -- Not exclusively for C, but still relevant
  * [[https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html|Statements and Declarations in Expressions]]
  * What inline in combination with export and static actually does [[https://stackoverflow.com/questions/6312597/is-inline-without-static-or-extern-ever-useful-in-c99|SO1]], [[https://stackoverflow.com/questions/216510/what-does-extern-inline-do|SO2]], [[https://en.cppreference.com/w/c/language/inline|CPP reference]]
  * [[http://www.catb.org/esr/structure-packing/]] -- The lost art of structure packing

[[http://www.underhanded-c.org/|Underhanded C Contest]]

[[http://uguu.org/sources.html|uguu]] -- Anime ascii art
====== IOCCC ======

[[https://www.ioccc.org/|The International Obfuscated C Code Contest]]

  * [[https://stackoverflow.com/questions/19298778/why-does-the-1987-korn-oneliner-print-unix|Best one-liner 1987]]

====== 8 phases of translation in C ======
[[https://stackoverflow.com/questions/1476892/poster-with-the-8-phases-of-translation-in-the-c-language/1479972#1479972|stackoverflow]]

<code>
                       ANSI C translation phases
                       =========================

          +-------------------------------------------------+
          | map physical characters to source character set |
          |     replace line terminators with newlines      |
          |           decode trigraph sequences             |
          +-------------------------------------------------+
                                   |
                                   V
               +---------------------------------------+
               | join lines along trailing backslashes |
               +---------------------------------------+
                                   |
                                   V
     +-------------------------------------------------------------+
     | decompose into preprocessing tokens and whitespace/comments |
     |                      strip comments                         |
     |                      retain newlines                        |
     +-------------------------------------------------------------+        
                                   |
                                   V
          +------------------------------------------------+
          | execute preprocessing directives/invoke macros |
          |              process included files            |
          +------------------------------------------------+
                                   |
                                   V
   +----------------------------------------------------------------+
   | decode escape sequences in character constants/string literals |
   +----------------------------------------------------------------+
                                   |
                                   V
                +--------------------------------------+
                | concatenate adjacent string literals |
                +--------------------------------------+
                                   |
                                   V
              +------------------------------------------+
              | convert preprocessing tokens to C tokens |
              |       analyze and translate tokens       |
              +------------------------------------------+
                                   |
                                   V
                    +-----------------------------+
                    | resolve external references |
                    |        link libraries       |
                    |      build program image    |
                    +-----------------------------+
</code>
====== Right-to-left rule ======
[[https://stackoverflow.com/questions/8392228/complicated-right-to-left-rule-when-defining-a-variable|SO thread]]

[[https://www.reddit.com/r/learnprogramming/comments/66a4og/the_rightleft_rule_useful_for_understanding_cc/|Reddit]]

To decode the expression ''char (*(*x())[5])()''
<code c>
         x          : x is a
         x()        : function
        *x()        : returning pointer to
       (*x())[5]    : a 5-element array of 
      *(*x())[5]    : pointer to
     (*(*x())[5])() : function
char (*(*x())[5])() : returning char
</code>

====== Pointer vs Array ======
They are NOT the same, despite what people say!

<code c>
// Example of char array vs char pointer
char *str1 = "Foo"; // Pointer. "Foo" resides in TEXT-section
char str2[] = "Bar"; // Array. "Bar" resides in RAM, copied to DATA section during C-startup

str1[2] = 'O'; // Illegal, undefined behaviour
str2[2] = 'R'; // This is fine, it alters content of RAM
</code>


====== Const ======

<code c>
uint8_t const *foo; // Points at constant. Can't change the value that foo points at.
const uint8_t *foo; // Same as above.
uint8_t *const foo; // Constant pointer. Can't change the address it is holding.
</code>

====== stdint.h, printf and scanf ======
''stdint.h'' has definitions of ''uint8_t'' etc.

''inttypes.h'' has definitions of ''PRIu8'' etc, for use with printf and scanf.

[[https://en.cppreference.com/w/c/types/integer|This site]] lists all available macros and types.

<code c>
#include <stdint.h>
#include <inttypes.h>

...

  printf("Printing a uint8_t: %" PRIu8 " woop woop!", var8bit);
</code>

====== Snippets ======

===== Debug macro =====
<code c>
#define STRINGIFY_(X) #X
#define STRINGIFY(X) STRINGIFY_(X)
#define PING() debug_print_str(__FILE__ " : " STRINGIFY(__LINE__) "\n")
</code>