有A,B两个数,当A,B都为空或者A,B都为零时,则取值C,否则取A,B的和,要如何设置判断条件?
if((A == null && B==null) || (A == 0 && B == 0),C,A+B)
if(or(AND(len(a)==0,len(b)==0),and(A == 0,B == 0)),C,A+B)