pid_t in Windows with DWORD and no windows.h

Readme.md

Getting DWORD defined without Windows.h

When making platform-agnostic headers, it becomes necessary to define Windows types compatible with POSIX types and the Windows API. Here we use pid_t as an example, which on Windows may be taken as equivalent to DWORD.

Rather than include "windows.h" that is a very large header, or "windef.h" that breaks MSVC compiles, or "IntSafe.h" that includes console functions, simply apply the DWORD definition:

typedef unsigned long DWORD;

as seen in example.h.

Build and run this example

cmake -B build
cmake --build build
ctest --test-dir build -V

CMakeLists.txt

cmake_minimum_required(VERSION 3.19)

project(dword LANGUAGES C)

enable_testing()

add_executable(main main.c)
target_include_directories(main PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})

add_test(NAME ProcessID COMMAND main)

file(GENERATE OUTPUT .gitignore CONTENT "*")

example.h

#include <sys/types.h> // for pid_t on non-Windows

#ifdef _MSC_VER

#ifndef DWORD
typedef unsigned long DWORD;
#endif

#ifndef pid_t
#define pid_t DWORD
#endif

#endif

pid_t my_get_pid();

main.c

#include <example.h>

#if defined(_MSC_VER)
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#else
#include <unistd.h>
#endif

#include <stdio.h>

pid_t
my_get_pid()
{
// get process ID

#if defined(_MSC_VER)
  // https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-getcurrentprocessid
  return GetCurrentProcessId();
#else
  // https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getpid.2.html
  // https://www.man7.org/linux/man-pages/man2/getpid.2.html
  return getpid();
#endif
}


int main(void)
{
  pid_t pid = my_get_pid();
  // Print the process ID
  printf("Process ID: %d\n", (int)pid);
  return 0;
}