Use this option to save processing time when a file such as a header , or . h , file for a . c or . cpp source file is included in several source files but is unchanged by preprocessing directives each time C或. cpp源文件的頭或. h文件)包括在幾個(gè)源文件內(nèi)但每次都不被預(yù)處理指令更改,則使用此選項(xiàng)以節(jié)省處理時(shí)間。