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05-03-2016 , 08:30 AM

#1201

RustyBrooks

Carpal \'Tunnel

Join Date: Feb 2006 Posts: 24,646

Quote:

Originally Posted by CyberShark93

Hey friends, suppose if I want to run an exhaustive search across all permutations in 16 different arrays in c, is there a elegant way to write this without having 16 nested loops?

Sure, you can do it either recursively or iteratively. I think recursively is probably easier to understand. Here it is in python

Code:

def permutate(val, arrays, output):
    if not len(arrays):
        output.append(val)
        return

    for el in arrays[0]:
        permutate(val+[el], arrays[1:], output)

arrays = [[1,2,3], ['a','b', 'c'], ['X', 'Y', 'Z'], ['!', '@','#']]
output = []
permutate([], arrays, output)
print output

The iterative version is probably a little harder to follow but isn't that much longer or more complicated.

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05-03-2016 , 08:54 AM

#1202

ChrisV

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Join Date: Jul 2004 Posts: 40,336

Quote:

Originally Posted by Wolfram

3) Intro to C# - the language of Microsoft. Similar to java in many ways, better than java if you want to make Windows Gui apps. Arguably worse than java for backend stuff because it forces you to use their proprietary tech stack.

Not anymore.

Quote

05-03-2016 , 11:28 AM

#1203

coon74

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Join Date: Apr 2011 Posts: 10,458

Quote:

Originally Posted by CyberShark93

Hey friends, suppose if I want to run an exhaustive search across all permutations in 16 different arrays in c, is there a elegant way to write this without having 16 nested loops?

Yes, Donald Knuth provided many non-recursive algorithms for generation of all permutations in section 7.2.1.2 of volume 4 of 'The Art of Computer Programming'.

Also, non-recursive C code (using a string instead of an array) can be found here.

Last edited by coon74; 05-03-2016 at 11:44 AM.

Quote

05-03-2016 , 11:57 AM

#1204

Wolfram

Carpal \'Tunnel

Join Date: Jan 2006 Posts: 15,066

Quote:

Originally Posted by ChrisV

Not anymore.

too little, too late

Quote

05-04-2016 , 06:25 PM

#1205

gaming_mouse

Carpal \'Tunnel

Join Date: Oct 2004 Posts: 13,786

Quote:

Originally Posted by CyberShark93

Hey friends, suppose if I want to run an exhaustive search across all permutations in 16 different arrays in c, is there a elegant way to write this without having 16 nested loops?

Not C, but here's a js version that used the ramda library for the permutation function that i think expresses the algorithm pretty nicely:

Code:

var perm = (arr, result=[[]]) => 
  !arr.length ? map(flatten, result) :
    addIndex(chain)(
      (x,i) => perm(remove(i,1,arr), xprod(result, of(x)))
    , arr)

Note: addIndex(chain) is just the "flatMap" function with an index attached. xprod is the cross product of two arrays (useful utility for your general problem) which in this case i'm just using to attach to attach a single element to the end of every array in an array. that is, as a synonym for map(concat(x))

Quote

05-08-2016 , 02:00 AM

#1206

penguinpoker

enthusiast

Join Date: Nov 2015 Posts: 95

Any idea what the -4:00 means in this timestamp?

"timestamp": "2016-03-24T13:25:34.000-04:00"

Quote

05-08-2016 , 02:34 AM

#1207

_dave_

_Pooh_Bah_

Join Date: Feb 2005 Posts: 13,154

Timezone. EDT, in this case I think.

Quote

05-08-2016 , 12:46 PM

#1208

RustyBrooks

Carpal \'Tunnel

Join Date: Feb 2006 Posts: 24,646

Well, it's not really "time zone" it's just "offset from UTC", i.e. "4 hours behind UTC".

I really hate this means of recording datetimes, because the "right" offset for wherever you are will change a couple times a year. But then again dealing with timezones is a giant cluster**** in nearly every programming environment no matter what you do.

Quote

05-09-2016 , 09:11 PM

#1209

Shaomai888

banned

Join Date: Dec 2015 Posts: 834

SOF FAQ say when you edit your unanswered question it will get bumped up. does not seem to be working for me. ??

Quote

05-10-2016 , 07:32 PM

#1210

adios

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Join Date: Sep 2002 Posts: 22,558

Quote:

Originally Posted by RustyBrooks

Win32 handles it pretty well in my view FWIW

Quote

05-10-2016 , 07:55 PM

#1211

RustyBrooks

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Join Date: Feb 2006 Posts: 24,646

What does "win32" mean? When I say programming environment I mean a programming langauge and it's associated libraries. If you mean at a system level, I think I probably disagree, the win32 os library for timezones is pretty much as crazypants as most things I've seen.

Nearly every mainstream language has at least one way to make timezone stuff work well enough, as long as you don't make any mistakes or follow the wrong path. And most of them also have ways that seem like they should work, but do not.

A python example comes to mind.

Code:

>>> x = datetime.datetime(2016, 1, 1, 0, 0, tzinfo=pytz.timezone('US/Central'))
>>> x
datetime.datetime(2016, 1, 1, 0, 0, tzinfo=<DstTzInfo 'US/Central' LMT-1 day, 18:09:00 STD>)

What? 18:09? Let's see what this is in UTC

Code:

>>> x.astimezone(pytz.utc)
datetime.datetime(2016, 1, 1, 5, 51, tzinfo=<UTC>)

5:51. So somehow midnight in US/Central turned into 5:51 in UTC. That's pretty ****ed up. The reason why is fairly clear once you understand how pytz works, but it's bitten nearly every python programmer I ever met.

Quote

05-10-2016 , 10:55 PM

#1212

adios

Carpal \'Tunnel

Join Date: Sep 2002 Posts: 22,558

Quote:

Originally Posted by RustyBrooks

Code:

>>> x = datetime.datetime(2016, 1, 1, 0, 0, tzinfo=pytz.timezone('US/Central'))
>>> x
datetime.datetime(2016, 1, 1, 0, 0, tzinfo=<DstTzInfo 'US/Central' LMT-1 day, 18:09:00 STD>)

What? 18:09? Let's see what this is in UTC

Code:

>>> x.astimezone(pytz.utc)
datetime.datetime(2016, 1, 1, 5, 51, tzinfo=<UTC>)

Piece of cake to convert UTC to local time with win32. Regarding what win32 is, Google is your friend.

Quote

05-11-2016 , 08:40 AM

#1213

RustyBrooks

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Join Date: Feb 2006 Posts: 24,646

It's a piece of cake to convert UTC to local time in most programming languages. The problem is, most of them have several ways to do it that will give a wrong result in some circumstances.

I know what win32 is. It's not a programming language, so I don't know why you answered in that way. It's like if I said "most cars have problems with brakes" and you replied "the brakes on highway 95 are pretty good"

Quote

05-11-2016 , 08:43 PM

#1214

Loki

binary duo

Join Date: Nov 2015 Posts: 12,772

thought this was interesting and worth a share:

Quote:

An anonymous reader has shared an interesting article that talks about one of the most common challenges faced by novice developers: "I know how to program, but I don't know what to program."

https://news.slashdot.org/story/16/0...hat-to-program

Quote

05-21-2016 , 10:36 PM

#1215

penguinpoker

enthusiast

Join Date: Nov 2015 Posts: 95

Anyone have experience with Wordpress and AWS? Basically I followed this tutorial, https://aws.amazon.com/getting-start...press-website/ Easy peasy. Then I tried editing a wordpress theme and this is where my trouble starts.

I am on my page, let's say it is www.myexample.com/admin. I try changing a wordpress theme but I get the message, 'You need to make this file writable before you can save your changes. See the Codex https://codex.wordpress.org/Changing...rmission_Modes for more information.' I look at the codex and I don't understand anything. Then I google for a few hours and make no progress. Stuff like this makes me question if I am really cut out for programming. I feel like I don't have even a basic understanding of what is going on.

Quote

05-21-2016 , 10:54 PM

#1216

Craggoo

banned

Join Date: Sep 2006 Posts: 12,645

Quote:

Originally Posted by penguinpoker

your first problem is that editing a wordpress theme is not programming

Quote

05-21-2016 , 11:16 PM

#1217

penguinpoker

enthusiast

Join Date: Nov 2015 Posts: 95

It is a php file that I would be changing.

Quote

05-22-2016 , 12:03 AM

#1218

penguinpoker

enthusiast

Join Date: Nov 2015 Posts: 95

By following this tutorial, https://wiki.bitnami.com/Amazon_clou...through_SSH.3f I was able to SSH into my account. I think. No real idea what this means yet, but if something comes of it I will post back.

Quote

05-22-2016 , 12:37 AM

#1219

penguinpoker

enthusiast

Join Date: Nov 2015 Posts: 95

Well looks like I am getting somewhere. Once you are in SSH you navigate to the folder and then set the permission by doing $ chmod -v 746 foldername. This changes the permission, however doing so causes an error, stylesheet not found. This is really strange because the stylesheet is still there. I am not actually even changing the files yet, just changing the permissions.

Last edited by penguinpoker; 05-22-2016 at 12:58 AM.

Quote

05-22-2016 , 04:31 AM

#1220

penguinpoker

enthusiast

Join Date: Nov 2015 Posts: 95

Promise this will be the last post for now. If I could delete earlier posts I would.

Think I have a decent understanding now. First you can download MAMP (Mac, Apache, MSQL, PHP) and then download Wordpress and put it into your MAMP folder so that you develop locally. Then once you develop locally you can push up a file or even a whole folder to your AWS instance by using something called SSH. So no need to even edit your files on AWS!

Weird how some days you make zero progress and other days you make a lot. Once I decided to try and figure out how to SSH then everything sort of went from there. Even though I didn't know if it would help me at all at the start.

Quote

05-22-2016 , 05:38 AM

#1221

Loki

binary duo

Join Date: Nov 2015 Posts: 12,772

Wait until you learn about ssh tunneling.

Quote

05-22-2016 , 06:11 AM

#1222

adios

Carpal \'Tunnel

Join Date: Sep 2002 Posts: 22,558

Quote:

Originally Posted by RustyBrooks

Well, it's not really "time zone" it's just "offset from UTC", i.e. "4 hours behind UTC".

I really hate this means of recording datetimes, because the "right" offset for wherever you are will change a couple times a year. But then again dealing with timezones is a giant cluster**** in nearly every programming environment no matter what you do.

Quote:

Originally Posted by RustyBrooks

It's a piece of cake to convert UTC to local time in most programming languages. The problem is, most of them have several ways to do it that will give a wrong result in some circumstances.

I know what win32 is. It's not a programming language, so I don't know why you answered in that way. It's like if I said "most cars have problems with brakes" and you replied "the brakes on highway 95 are pretty good"

Interesting and please show me the post where I stated win32 was a programming language. Thanks. No programming environments that utilize the win32 API? Cmon.

Not hard to use this function.

win32 -GetLocalTime

Last edited by adios; 05-22-2016 at 06:21 AM.

Quote

05-22-2016 , 02:04 PM

#1223

RustyBrooks

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Join Date: Feb 2006 Posts: 24,646

GetLocalTime specifically *doesn't* deal with timezones. It gives you the system time. It doesn't even give you a time back that contains information about what the local timezone *is*

Quote

05-22-2016 , 04:02 PM

#1224

daveT

S.A.G.E. Master

Join Date: Jun 2005 Posts: 23,955

Quote:

Originally Posted by penguinpoker

You need to add the -R flag. R means recursive. The chmod commands are pretty straightforward, and I disagree with your numbers. Also, you probably need to do that with sudo, since the folder is probably owned by root.

Quote

05-22-2016 , 06:11 PM

#1225

RustyBrooks

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Join Date: Feb 2006 Posts: 24,646

I actually prefer using the named parameters instead of the numbers. It's easier to get right. For example

chmod a+rw
means "give everyone (a=all) read and write permision"

chmod g-x
means "take away execute permission from group"

and so forth.

You're probably getting stylesheet not found because you don't have the execute bit set on one of the folders. The "read" flag allows you to list the files in a directory, but the "execute" flag allows you to change directories into it (i.e. you can't access a subdir if you don't have execute permissions on the parent dir)

"7" gives rwx to the owner of the directory, 4 gives just r to the group and 6 gives rw to everyone else. This probably is not what you want. I would give the directories all a+rx at the least.