Connect to MongoDB

Create a project directory

In your shell, navigate to where you want to create your application, then run the following command to create a directory called c-quickstart for this project:

mkdir c-quickstart

Select the tab corresponding to your operating system and run the following commands to create a quickstart.c application file in the c-quickstart directory:

cd c-quickstart
touch quickstart.c

cd c-quickstart
type nul > quickstart.c

Create your C driver application

Copy and paste the following code into the quickstart.c file, which queries the movies collection in the sample_mflix database:

#include <bson/bson.h>
#include <mongoc/mongoc.h>
#include <stdio.h>
int
main (void)
{
    const bson_t *doc;
    mongoc_init ();
    mongoc_client_t *client = mongoc_client_new ("<connection string>");
    mongoc_collection_t *collection = mongoc_client_get_collection (client, "sample_mflix", "movies");
    // Specify the query filter
    bson_t *query = BCON_NEW ("title", "The Shawshank Redemption");
    mongoc_cursor_t *results = mongoc_collection_find_with_opts (collection, query, NULL, NULL);
    // Print the results
    while (mongoc_cursor_next (results, &doc))
    {
        char* str = bson_as_canonical_extended_json (doc, NULL);
        printf ("%s\n", str);
        bson_free (str);
    }
    bson_destroy (query);
    mongoc_cursor_destroy (results);
    mongoc_collection_destroy (collection);
    mongoc_client_destroy (client);
    mongoc_cleanup ();
    return EXIT_SUCCESS;
}

Assign the connection string

Replace the <connection string> placeholder with the connection string that you copied from the Create a Connection String step of this guide.

Run your C application

In your shell, run the following commands to compile and run this application:

gcc -o quickstartc quickstart.c $(pkg-config --libs --cflags libmongoc-1.0)
./quickstartc

The command line output contains details about the retrieved movie document:

{ "_id" : { "$oid" : "..." },
"plot" : "Two imprisoned men bond over a number of years, finding solace
and eventual redemption through acts of common decency.",
...
"title" : "The Shawshank Redemption",
...

If you encounter an error or see no output, ensure that you specified the proper connection string in the quickstart.c file and that you loaded the sample data.