What is the correct printf specifier for printing pid_t
With integer types lacking a matching format specifier as in the case of pid_t, yet with known sign-ness1, cast to widest matching signed type and print.
If sign-ness is not known for other system type, cast to the widest unsigned type or alternate opinion
pid_t pid = foo();// C99#include <stdint.h>printf("pid = %jd\n", (intmax_t) pid);Or
// C99#include <stdint.h>#include <inttypes.h>printf("pid = %" PRIdMAX "\n", (intmax_t) pid);Or
// pre-C99pid_t pid = foo();printf("pid = %ld\n", (long) pid);1The pid_t data type is a signed integer type which is capable of representing a process ID.