One thing to consider for CS and engineering is that they are popular majors that are filled to capacity at some colleges. In this case, beware of the following situations if he is unsure of his major:
A. Direct admission to the CS or E major is more difficult than admission to the school is generally. Changing into the CS or E major is difficult if one enrolls without direct admission to the CS or E major. (e.g. UT Austin, Washington for CS, UIUC)
B. School enrolls CS or E majors with direct admission, but has high GPA thresholds to stay in the major. (e.g. Wisconsin for engineering)
C. School enrolls frosh in a pre-engineering program, but then requires a moderately competitive process to get into specific CS or E majors. (e.g. Texas A&M, Purdue, Minnesota, probably Washington for engineering)
D. School enrolls frosh in a pre-engineering program; entering a CS or E major is non-competitive if one passes the prerequisites. However, frosh who enroll outside of the pre-engineering program may find it difficult to switch into the pre-engineering program or a CS or E major. (e.g. Michigan, USC)
E. CS and E majors are non-competitive to enter once the student is enrolled at the school. (e.g. Wisconsin for CS, Case Western Reserve, MIT, Stanford)
Obviously, (E) above is the most desirable for an undecided student who may choose CS or an engineering major.