# Db::cursor

`

###

    #include <db_cxx.h>

    int
    Db::cursor(DbTxn *txnid, Dbc **cursorp, u_int32_t flags);

# Description

The Db::cursor method creates a cursor and copies a pointer to it into the memory referenced by cursorp.

A cursor is a structure used to provide sequential access through a database. This interface and its associated functions replaces the functionality provided by the seq function in previous releases of Berkeley DB.

If the file is being accessed under transaction protection, the txnid parameter is a transaction ID returned from DbEnv::txn_begin, otherwise, NULL.

If transaction protection is enabled, cursors must be opened and closed within the context of a transaction, and the txnid parameter specifies the transaction context in which the cursor may be used.

The flags value must be set to 0 or by bitwise inclusively OR'ing together one or more of the following values.

DB_WRITECURSOR
  Specify that the cursor will be used to update the database. This flag should only be set when the DB_INIT_CDB flag was specified to DbEnv::open.

The Db::cursor method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success.

# Errors

The Db::cursor method may fail and throw an exception or return a non-zero error for the following conditions:

EINVAL
  An invalid flag value or parameter was specified.

The Db::cursor method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods. If a catastrophic error has occurred, the Db::cursor method may fail and either return DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.

### Class

Db

# See Also

Db::close, Db::cursor, Db::del, Db::err, Db::fd, Db::get, Db::get_byteswapped, Db::get_type, Db::join, Db::key_range, Db::open, Db::put, Db::remove, Db::set_bt_compare, Db::set_bt_minkey, Db::set_bt_prefix, Db::set_cachesize, Db::set_dup_compare, Db::set_errcall, Db::set_errfile, Db::set_errpfx, Db::set_flags, Db::set_h_ffactor, Db::set_h_hash, Db::set_h_nelem, Db::set_lorder, Db::set_malloc, Db::set_pagesize, Db::set_paniccall, Db::set_realloc, Db::set_re_delim, Db::set_re_len, Db::set_re_pad, Db::set_re_source, Db::stat, Db::sync, Db::upgrade and Db::verify.`

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