|
|
|
|
|
|
|
Having converted trade_price's ordinary trade structure
parameter, t, into a trade pointer parameter,
tptr, your program must, of course, dereference tptr
inside the trade_price function to identify a particular trade
structure object in the trades array. Accordingly, instead of
expressions, such as t.price, that read structure variables in a
trade copy, you need expressions that read structure
variables in a trade object identified by a dereferenced pointer.
The redefined trade_price function is as follows:
double trade_price (struct trade *tptr) {
return (*tptr).price * (*tptr).shares}
Note that you must enclose *tptr in parentheses to refer to the price
of the trade object to which tptr points, because the
structure-member operator, the period, has precedence higher than that of
the dereferencing operator, the asterisk. Accordingly, a version without
parentheses, *tptr.price, is equivalent to *(tptr.price),
which means produce the object pointed to by a pointer stored,
peculiarly, in the price member variable of a pointer to a trade object.
What you want, of course, is the version that means produce the value
stored in the price member variable of the dereferenced pointer to a trade
object.