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References

Useful references / articles on C; organized by date of collection not origin.

January 2025

• https://blog.demofox.org/2024/02/11/gradient-descent-with-adam-in-plain-c/

Previously collected

• https://nullprogram.com/
• https://www.reddit.com/r/C_Programming/
• Deep C Secrets

Modern C

• Generally very pleasant book to read
• Notes on C that were surprising / newish, and snippets to copy paste / cheatsheet

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

int main(int argc, [[maybe_unused]] char* argv[argc+1]) {
	return EXIT_SUCCESS;
}

• EXIT_SUCCESS comes from stdlib
• [[maybe_unused]] is an attribute
• didn’t realize I could use argc in the size of argv

double A[2] = {
  [1] = 2.9,
};

• unspecified indexes get initialized to 0

clang -std=c2x -Wall -lm -o output file.c

• left binding for qualifiers and attributes
• style rules
  • don’t use continued declarations, too confusing
  • array notation for pointer parameters (when pointer can’t be null)
  • function notation for function pointers (when it can’t be null)
  • define variables as close to first use as possible
  • prefix notation for blocks
  • digit separators: 12'345.983'123

size_t strlen(char const string[static 1])

• enforces that strlen should receive a non null pointer and should have at least 1 element

• in practice they get rewritten

• no longer need stdbool.h

Level
 Name
 Other
 Category
 Where
 printf
0
 size_t
 Unsigned
 <stddef.h>
 "%zu" "%zx"
0
 double
 Floating
 Built in
 "%e" "%f" "%g" "%a"
0
 signed
 int
 Signed
 Built in
 "%d"
0
 unsigned
 Unsigned
 Built in
 "%b" "%o" "%u" "%x"
0
 bool
 _Bool
 Unsigned
 Built in (since C23)
 "%d" as 0 or 1
1
 ptrdiff_t
 Signed
 <stddef.h>
 "%td"
1
 char const*
 String
 Built in
 "%s"
1
 char
 Character
 Built in
 "%c"
1
 void*
 Pointer
 Built in
 "%p"
2
 unsigned char
 Unsigned
 Built in
 "%hhu" "%02hhx"

• constexpr

— Kunal