RT........RT!

The C++ Standard Library（99年）中的一段比较 x++ 与 ++x 的内容：
//make all characters in the list uppercase
list<char>::iterator pos;
for (pos = coll.begin(); pos != coll.end(); ++pos) {
*pos = toupper(*pos);
}
Note that the preincrement operator (prefix ++) is used here. This is because it might have better
performance than the postincrement operator. The latter involves a temporary object because it
must return the old position of the iterator. For this reason, it generally is best to prefer ++pos
over pos++. Thus, you should avoid the following version:
for (pos = coll.begin(); pos != coll.end(); pos++) {
                                                            ^^^^^ // OK, but slower
    ...
}
For this reason, I recommend using the preincrement and pre-decrement operators in general.