Where is ssize_t defined in Linux?

OS: Debian 9 (Linux 4.9)

Compiler: GCC 8.2

Currently I am including <stddef.h> (where size_t is defined) and <stdint.h> (where most integral types are defined), but I still don’t have ssize_t.

Where is it defined?

Answer

ssize_t is defined in sys/types.h.

Per the POSIX documentation:

NAME

sys/types.h – data types

SYNOPSIS

#include <sys/types.h>

DESCRIPTION

The header shall define at least the following types:

…

ssize_t

    Used for a count of bytes or an error indication.