在Delphi中，如果要在一台PC电脑上同时控制多台打印机，并且各台打印的纸张大小不同，此函数非常有用。

如果要只定把数据打印在那一台打印机，不需要控制打印机端口，只需要使用打印机索引即可，默认打印机为第一台打印机，以后按顺序排序，但第一台打印机的索引号为 –1并不是0.

-in Delphi, in a PC computer can control many printers, and the print paper units of different sizes, this function very useful. If only to set the print data which printers do not need to control the printer port, only need to use the printer can Index, the default printer for the first printers, according to the order after order, but the first printers, the index is 0 to -1.