6-11 先序输出叶结点 (15分)

void PreorderPrintLeaves( BinTree BT )
{
    if(BT)
    {
        if(!BT->Left&&!BT->Right) printf(" %c",BT->Data);
        PreorderPrintLeaves(BT->Left);
        PreorderPrintLeaves(BT->Right);
    }
}