Connect the C++ driver to your database

The C++ driver does not support the vector data type. These instructions are for users connecting to HCD databases.

Create your .c file, add connection code, build, and link your application against the C++ driver to connect. This example also includes code to create a CassStatement object to connect to your Hyper-Converged Database (HCD) database, run a CQL query, and print the output to the console.

Prerequisite

You have installed a cluster.
You have created a keyspace.
You have installed C++.

HCD APIs use the term keyspace to refer to both namespaces and keyspaces.

Connect to your database

Create a connect_database.c file in the main directory for your C++ project.
```
$ cd my_project
$ touch connect_database.c
```

Copy the following connection code into the connect_database.c file.

#include <cassandra.h>
#include <stdio.h>

int main(int argc, char* argv[]) {
     /* Setup and connect to cluster /
     CassCluster cluster = cass_cluster_new();
     CassSession* session = cass_session_new();
     }

     /* Set credentials provided when creating your database /
     cass_cluster_set_credentials(cluster, "username", "password");

     CassFuture connect_future = cass_session_connect(session, cluster);

     if (cass_future_error_code(connect_future) == CASS_OK) {
       /* Use the session to run queries /
     } else {
       / Handle error */
     }

     cass_future_free(connect_future);
     cass_cluster_free(cluster);
     cass_session_free(session);

     return 0;
}

Build and link your application against the C++ driver.

Linux or macOS
Windows

For static linking, use cassandra_static.a.

cc connect_database.c -I/path/to/cassandra.h -L/path/to/cassandra.so -lcassandra

Include these libraries in your Microsoft Visual Studio project by adding them to the project’s properties under Configuration Properties > Linker > Input > Additional Dependencies.

For static linking, use cassandra_static.lib.

Link your application against cassandra.lib. cassandra.dll must be in the runtime path for your application.

After connecting to your database, use the following code to query your database. This code creates a CassStatement object to connect to your Hyper-Converged Database (HCD) database, runs a CQL query, and prints the output to the console.

/* Build statement and execute query */
const char_ query = "SELECT release_version FROM system.local";
CassStatement* statement = cass_statement_new(query, 0);

CassFuture* result_future = cass_session_execute(session, statement);

if (cass_future_error_code(result_future) == CASS_OK) {
  /* Retrieve result set and get the first row */
  const CassResult_ result = cass_future_get_result(result_future);
  const CassRow* row = cass_result_first_row(result);

  if (row) {
    const CassValue* value = cass_row_get_column_by_name(row, "release_version");

    const char* release_version;
    size_t release_version_length;
    cass_value_get_string(value, &release_version, &release_version_length);
    printf("release_version: '%._s'\n", (int)release_version_length, release_version);
  }

    cass_result_free(result);
  } else {
    /_ Handle error _/
    const char_ message;
    size_t message_length;
    cass_future_error_message(result_future, &message, &message_length);
    fprintf(stderr, "Unable to run query: '%.*s'\n", (int)message_length, message);
  }

  cass_statement_free(statement);
  cass_future_free(result_future);
}

Installation and data migration instructions are located in the C++ driver quickstart.

Connect the C++ driver to your database

Prerequisite

Connect to your database

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