bson_oid_t man page

bson_oid_t — BSON ObjectID Abstraction


#include <bson.h>

typedef struct
   uint8_t bytes[12];
} bson_oid_t;


The bson_oid_t structure contains the 12‐byte ObjectId notation defined by the BSON ObjectID specificiation

ObjectId is a 12‐byte BSON type, constructed using:

a 4‐byte value representing the seconds since the Unix epoch (in Big Endian)
a 3‐byte machine identifier
a 2‐byte process id (Big Endian), and
a 3‐byte counter (Big Endian), starting with a random value.

String Conversion

You can convert an Object ID to a string using bson_oid_to_string(3) and back with bson_oid_init_from_string(3)


A bson_oid_t can be used in hashtables using the function bson_oid_hash(3) and bson_oid_equal(3)


A bson_oid_t can be compared to another using bson_oid_compare(3) for qsort(3) style comparing and bson_oid_equal(3) for direct equality.


You can validate that a string containing a hex‐encoded ObjectID is valid using the function bson_oid_is_valid(3)


#include <bson.h>
#include <stdio.h>

int main (int argc, char *argv[])
   bson_oid_t oid;
   char str[25];

   bson_oid_init (&oid, NULL);
   bson_oid_to_string (&oid, str);
   printf ("%s\n", str);

   if (bson_oid_is_valid (str, sizeof str)) {
      bson_oid_init_from_string (&oid, str);

   printf ("The UNIX time was: %u\n",
           (unsigned)bson_oid_get_time_t (&oid));

   return 0;


This page is part of libbson. Please report any bugs at


2016‐10‐28 libbson