以下程序的功能是根据输入的'y'('Y')与'n'('N'),在屏幕上分别显示出'This is YES.'与'This is NO.'。空白处需要填入的内容是 include void YesNo(char ch) { switch(ch) { case′y′: case′Y′: printf('/nThis is YES./n'); case ′n′: case ′N′: printf('/nThis is NO./n');} main() { char ch; printf('/nEnter a char y,Y or n,N:'); ch=【 】; printf(' ch;%c' ,ch); YesNo(ch); }