if can answer 75% without ref to compiler or book, u can be consider as good C/C++ programmer.
but on the otherside, not all the good programmer should be able to answer these question correctly, because most of the questions are :written code in bad manner and ask you what does it mean. What you should do is know there could be a problem and avoid write it in such a way, even u are clear abotu it. for example: c=26*b==0; even u know == is the lowest priority, u'd better add a (c=26*b)==0.
but on the otherside, not all the good programmer should be able to answer these question correctly, because most of the questions are :written code in bad manner and ask you what does it mean. What you should do is know there could be a problem and avoid write it in such a way, even u are clear abotu it. for example: c=26*b==0; even u know == is the lowest priority, u'd better add a (c=26*b)==0.