mirror of
https://github.com/pkivolowitz/asm_book.git
synced 2026-06-21 06:46:50 +08:00
51 lines
2 KiB
Markdown
51 lines
2 KiB
Markdown
# FizzBuzz
|
|
|
|
In this chapter we build the classic tech interview question: FizzBuzz.
|
|
|
|
The idea is simple. Write a program that enumerates the integers from 0 to some stopping value, perhaps 100.
|
|
|
|
For each integer:
|
|
|
|
* If it is a multiple of 3, print Fizz
|
|
|
|
* If it is a multiple of 5, print Buzz
|
|
|
|
* If it is a multiple of both 3 *and* 5, print FizzBuzz
|
|
|
|
* Otherwise, if none of the above applies, print the integer.
|
|
|
|
The interviewer's hope is that you get twisted in knots trying
|
|
to navigate the case where the integer is a multiple of both 3 and
|
|
5. There are many ways to solve this challenge.
|
|
|
|
One way might be to test for being a multiple of 15 *first* and print
|
|
FizzBuzz if true. Then test against 3 and then against 5.
|
|
|
|
Another way is to accumulate the correct out by testing against 3 and
|
|
adding Fizz to a buffer. Then test against 5 and if appropriate append
|
|
Buzz to the buffer. Either the buffer was empty, in which case you get
|
|
Buzz alone - or it already contained Fizz in which case the buffer now
|
|
contains FizzBuzz. Finally, if *anything* is in the buffer, cause the
|
|
buffer to be printed and append a new line.
|
|
|
|
In C++, the buffer could be a C++ string or a stringstream. In C
|
|
you might think that you must resort to using an array of `char` to
|
|
act as the buffer, filling it with `strncpy` or some such nonsense.
|
|
|
|
But you don't have to bother! `printf` is a buffered output stream.
|
|
It won't print anything until it encounters a new line character.
|
|
|
|
In this program, we'll use this to buffer up either Fizz, Buzz or
|
|
both then as indicated above, we'll end with a new line and BAM -
|
|
whatever was in the `printf` buffer gets sent to the console.
|
|
|
|
[Here is a video](https://youtu.be/aJSGTIxu4ik) where we walk through
|
|
the process of writing FizzBuzz from scratch in ARM 64 bit assembly
|
|
language.
|
|
|
|
[Here is the source code](./fizzbuzz.s).
|
|
|
|
The video is long but there is much benefit to be had by watching
|
|
and listening to another person's process as they write the code.
|
|
**AND especially** listening and watching to them debug when
|
|
things go wrong!
|