How to get the running process' pid in C / C++?

How to get the running process’ pid in C / C++?

In C and C++, you can call the getpid() library function which is a function from the POSIX library.

#include <sys/types.h>
#include <unistd.h>

pid_t getpid(void);

getppid() returns the process ID of the calling process.

Example usage:

getpid.c

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>

int main()
{
  pid_t pid = getpid();

  printf("pid: %lun", pid);
}

Build and run it:

$ gcc getpid.c -o s && ./s
pid: 7108

One comment:

Please update the reuslt section with actual result.

$ gcc getpid.c -o s && ./s
ppid: 7108

But printf is
printf(“pid: %lun”, pid);

How come it prints “ppid” for print statement of “pid”.