types war

recently, I face a spesific issue in order choosing best types for my program. my goal is choose best need for my C datatype

there has some header exists

  • stdint.h
  • sys/types.h

difference from location presefective

  • /usr/lib/clang/20/include/stdint.h
  • /usr/include/sys/types.h

see? stdint.h is more compiler oriented, and sys/types.h is more system oriented, that right, sys/types.h is POSIX. It's fundamentally about defining types used by system calls and other OS-level interfaces.

sys/types.h

Purpose: To define data types used in system-level programming. These types are often opaque and their actual size can vary between different systems (e.g., a 32-bit vs. a 64-bit system), but they provide a portable way to interface with the OS kernel.

Origin: System V and BSD systems, later standardized by POSIX.

Use sys/types.h when you are writing code that makes POSIX-compliant system calls (open, read, fork, stat, etc.).

Note

there is no format specifier header.

stdint.h

This header is part of the ISO C99 standard and later. It is focused on providing programmers with explicit control over the size of integer data types.

Purpose: To define integer types of a specific, fixed width and to provide macros for printing and scanning these types with the printf and scanf family of functions.

Note

use inttypes.h for formatting, see spesific topic about it here

conlusion

Default to <stdint.h> for all your data definitions. Only use types from <sys/types.h> when you are calling an OS/POSIX function that requires them.

normal struct? use stdint.h

interacting with os APIs, such read(), return pid, etc. use <sys/types.h>

another types wars

  • uint_least8_t vs uint8_t, imagine, you on very old board, where 8 bit int is not available, this uint_least8_t will be taken as 16 bit int. meanwhile, uint8_t give you exactly 8 bit wide variable.