5 ms·

I was expecting to see "None of them" as kind of a joke. For a web app developer are these useful? For fun? yes. For profit? no. Title should be Low Level Bit

I was expecting to see "None of them" as kind of a joke. For a web app developer are these useful? For fun? yes. For profit? no. Title should be Low Level Bit Hacks You May Find Interesting.

jackowayed 17y ago
same here! I was hoping it would just have the title and then be a blank page.
paulgb 17y ago
I assume the title was targeted at Peteris' normal audience, not web app developers. From the about: Peteris Krumins’ blog about programming, hacking, software reuse, software ideas, computer security, google and technology.
- notaddicted 17y ago
  The purpose of the Hacker News website is to serve past/present/future ycombinator candidates. I'm not even a web app developer, I wrote C code for an $8 processor today. The title (as submitted by the author of the blog) says "Absolutely Must Know," which is quite hyperbolic. I would suggest: Basic tricks of bit manipulation. Consider that this topic is covered in K. N. King's book C Programming: A Modern Approach, in Chapter 20: Low-Level Programming, on page 451
jf 17y ago
Yes, even for web applications, bitwise manipulation will come in handy at some point. Personal anecdote: I recently had to combine two arbitrary unsigned 32 bit integers into one unsigned 64 bit integer to make a unique ID for an index. Not sure how I would have done that without bitwise manipulation.
- notaddicted 17y ago
  lol. in python: (2 ^ 32)*upper + lower edit: dbl star goes blank .. so in almost python
  - tptacek 17y ago
    You're XORing 32 into 2, multiplying it by the top word, and adding the bottom word? Also, you think exponentiation and multiplication is faster than a shift and an OR? I think you're the target audience for this article, and I revise my opinion (thankfully unstated) about whether this is material every developer "must" know.
    - notaddicted 17y ago
      Okay okay ... I should have written: import math; math.pow(2,32) I tried to use the double star operator, but that is markup for italics in this software, so it was edited out.
    - comatose_kid 17y ago
      Surprisingly (I just benchmarked it myself), the times are near the same. Here's my benchmark (in case I made a mistake): import time def combine(upper,lower): return (2**32)*upper + lower def combine2(upper,lower): return (upper << 32) | lower def test_combine(): start = time.clock() for i in range(10000000): combine(i,i) end = time.clock() output = 'The time taken for combine() is ' + str(end - start) print output def test_combine2(): start = time.clock() for i in range(10000000): combine2(i,i) end = time.clock() output = 'The time taken for combine() is ' + str(end - start) print output Also see http://wiki.python.org/moin/PythonSpeed/PerformanceTips#PythonisnotC http://wiki.python.org/moin/PythonSpeed/PerformanceTips#Pyth...
      - tptacek 17y ago
        That's surprising; it's more than twice as slow in Ruby (yeah, yeah). It's also (for obvious reasons) orders of magnitude faster in C --- if you were crazy enough to actually write code that way.
      - ramchip 17y ago
        I don't know much about Python so forgive me if this is stupid - but could 2^32 have been optimized as a constant, so that the result is just a multiplication and an addition?
noodle 17y ago
not all of us here are (purely/originally) web app developers.
CodeMage 17y ago
Maybe I'm missing something... Why the assumption that all (or even the majority of) HN readers are interested only in developing web apps?
- piramida 17y ago
  for a non-php developer that article is kind of trivial entry level stuff so no value either.
- yters 17y ago
  Quick, someone bring more koolaid!
- kscaldef 17y ago
  It suffices that just one such individual exists to invalidate the claim of the title.
strlen 17y ago
Here's an example where a web developer may find bit=fiddling useful: - How would you, compactly and discretely, represent in a cookie the days on which a user has visited your site this month? (I am decided not a web developer, but this is a question I'd ask a web developer on a phone screen were I to hire one).

I was expecting to see "None of them" as kind of a joke. For a web app developer are these useful? For fun? yes. For profit? no. Title should be Low Level Bit Hacks You May Find Interesting.

jackowayed 17y ago

same here! I was hoping it would just have the title and then be a blank page.

paulgb 17y ago

I assume the title was targeted at Peteris' normal audience, not web app developers. From the about: Peteris Krumins’ blog about programming, hacking, software reuse, software ideas, computer security, google and technology.

notaddicted 17y ago
The purpose of the Hacker News website is to serve past/present/future ycombinator candidates. I'm not even a web app developer, I wrote C code for an $8 processor today. The title (as submitted by the author of the blog) says "Absolutely Must Know," which is quite hyperbolic. I would suggest: Basic tricks of bit manipulation. Consider that this topic is covered in K. N. King's book C Programming: A Modern Approach, in Chapter 20: Low-Level Programming, on page 451

jf 17y ago

Yes, even for web applications, bitwise manipulation will come in handy at some point. Personal anecdote: I recently had to combine two arbitrary unsigned 32 bit integers into one unsigned 64 bit integer to make a unique ID for an index. Not sure how I would have done that without bitwise manipulation.

notaddicted 17y ago
lol. in python: (2 ^ 32)*upper + lower edit: dbl star goes blank .. so in almost python
- tptacek 17y ago
  You're XORing 32 into 2, multiplying it by the top word, and adding the bottom word? Also, you think exponentiation and multiplication is faster than a shift and an OR? I think you're the target audience for this article, and I revise my opinion (thankfully unstated) about whether this is material every developer "must" know.
  - notaddicted 17y ago
    Okay okay ... I should have written: import math; math.pow(2,32) I tried to use the double star operator, but that is markup for italics in this software, so it was edited out.
  - comatose_kid 17y ago
    Surprisingly (I just benchmarked it myself), the times are near the same. Here's my benchmark (in case I made a mistake): import time def combine(upper,lower): return (2**32)*upper + lower def combine2(upper,lower): return (upper << 32) | lower def test_combine(): start = time.clock() for i in range(10000000): combine(i,i) end = time.clock() output = 'The time taken for combine() is ' + str(end - start) print output def test_combine2(): start = time.clock() for i in range(10000000): combine2(i,i) end = time.clock() output = 'The time taken for combine() is ' + str(end - start) print output Also see http://wiki.python.org/moin/PythonSpeed/PerformanceTips#PythonisnotC http://wiki.python.org/moin/PythonSpeed/PerformanceTips#Pyth...
    - tptacek 17y ago
      That's surprising; it's more than twice as slow in Ruby (yeah, yeah). It's also (for obvious reasons) orders of magnitude faster in C --- if you were crazy enough to actually write code that way.
    - ramchip 17y ago
      I don't know much about Python so forgive me if this is stupid - but could 2^32 have been optimized as a constant, so that the result is just a multiplication and an addition?

noodle 17y ago

not all of us here are (purely/originally) web app developers.

CodeMage 17y ago

Maybe I'm missing something... Why the assumption that all (or even the majority of) HN readers are interested only in developing web apps?

piramida 17y ago
for a non-php developer that article is kind of trivial entry level stuff so no value either.
yters 17y ago
Quick, someone bring more koolaid!
kscaldef 17y ago
It suffices that just one such individual exists to invalidate the claim of the title.

strlen 17y ago

Here's an example where a web developer may find bit=fiddling useful: - How would you, compactly and discretely, represent in a cookie the days on which a user has visited your site this month? (I am decided not a web developer, but this is a question I'd ask a web developer on a phone screen were I to hire one).