Many of the DBTools structures use bit fields to hold Boolean information in a compact manner. For example, the backup structure includes the following bit fields:
a_bit_field backup_database : 1; a_bit_field backup_logfile : 1; a_bit_field no_confirm : 1; a_bit_field quiet : 1; a_bit_field rename_log : 1; a_bit_field truncate_log : 1; a_bit_field rename_local_log: 1; a_bit_field server_backup : 1;
Each bit field is one bit long, indicated by the 1 to the right of the colon in the structure declaration. The specific data type used depends on the value assigned to a_bit_field, which is set at the top of dbtools.h, and is operating system-dependent.
You assign a value of 0 or 1 to a bit field to pass Boolean information in the structure.
Discuter à propos de cette page dans DocCommentXchange.
|Copyright © 2013, SAP AG ou société affiliée SAP - SAP Sybase SQL Anywhere 16.0|