1Binary I/O11/14/20072Opening Discussion■Do you have any questions about the quiz?■Let's look at solutions to the interclass problem.■Quantum computers: if and when.3Quicksort■Quicksort can sort in place. At each step we pick a special element called the pivot. We move elements so that the pivot is in its proper place. Then we recursively call quicksort on the parts below and above the pivot.■All the work happens going down the recursion.■Expected behavior is O(n log n), but poor pivot selection leads to worst case of O(n2).■For our code we will just take the first element as the pivot. We could easily pick another and swap it to the first spot.4Binary Files vs. Text Files■We have already played with files, but the files that we used were text files.■Text files have the advantage that they are human readable and can be easily edited with any text editor.■Most files that programs use a binary files. These are typically smaller and more efficient. With binary files we write the data to the disk as it appears in the memory of the machine.■Binary files also allow us to do direct access which is vital in many applications.5Using Binary Files■Working with binary files we use fopen and fclose just like normal, but you need to specify that it is a binary file in the fopen.■Instead of fprintf or fscanf we use fread and fwrite.■These functions directly copy from disk to memory or from memory to disk.■Let's look at the man pages for these functions.6Random Access■What really makes binary files significant is the ability to jump to any place in the file to read or write.■This random access ability makes them very fast for accessing large amounts of data. Databases are built around this ability.■The simplest form of direct access involves fixed length records. This is basically like having an array on disk.7Code■Let's write some code to see how this works.8Minute Essay■What are going to be some of the problems/challenges of dealing with random access files?■Interclass Problem – Make a binary file that has an array of integers. If you want a challenge, write a function to sort that which doesn't use an array, but sorts it on the file never loading more than two numbers at a
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