Question

QUESTION 3: Text Processing and Persistence (a) Explain in detail why buffered streams are so important while reading from, or writing [05] to, a file. Please note: Do not provide code, you just need to explain. (b) Provide a single regular expression that matches all load shedding schedules in the follow- [05] ing format. • 6A Dressdorp 14:00 • 82 Chessburg 20:00 • 1B Jeffstown 06:30 . 9M Bergplein 12:30 Total: 10

Answer 1

a). Buffered Streams

Reading data from disk byte by byte is a very inefficient process. One way to speed up is to use a buffer. Instead of reading one byte at a time, read a few thousand bytes at once, and put them in a buffer, in memory. Then we read from buffer with greater speed and efficiency.

When working with files, read and write operations are way more. We could optimize it by having to read and write from the memory instead of the file. So, we use a buffer in memory which temporarily store data to be read from or written to a file. In effect, we are increasing memory access operations instead of file access operations, considering the tradeoff between the two.

b). Regular Expression

\d[A-Z] [a-zA-Z]+ \d{2}:\d{2}

• \d any digit
• [A-Z] any uppercase letter
• [a-zA-Z]+ one or more chararacters, either lower case or upper case
• \d{2} exactly 2 digits