C Primer Plus®, Third Edition

Beyond the Array to the Linked List

Ideally, you'd like to be able to add data indefinitely (or until the program runs out of memory) without specifying in advance how many entries you'll make and without committing the program to allocating huge chunks of memory unnecessarily. You can do this by calling malloc() after each entry and allocating just enough space to hold the new entry. If the user enters three films, the program calls malloc() three times. If the user enters 300 films, the program calls malloc() 300 times.

This fine idea raises a new problem. To see what it is, compare calling malloc() once, asking for enough space for 300 film structures, and calling malloc() 300 times, each time asking for enough space for one film structure. ...