Programs & Examples On #Geography

Geography is the science that deals with the study of the Earth and its lands, features, inhabitants, and phenomena.

Getting distance between two points based on latitude/longitude

You can use Uber's H3,point_dist() function to compute the spherical distance between two (lat, lng) points. We can set return unit ('km', 'm', or 'rads'). The default unit is Km.

Example :

import H3

coords_1 = (52.2296756, 21.0122287)
coords_2 = (52.406374, 16.9251681)
distance = h3.point_dist(coords_1,coords_2) #278.4584889328128

Hope this will usefull!

Calculate distance between 2 GPS coordinates

I guess you want it along the curvature of the earth. Your two points and the center of the earth are on a plane. The center of the earth is the center of a circle on that plane and the two points are (roughly) on the perimeter of that circle. From that you can calculate the distance by finding out what the angle from one point to the other is.

If the points are not the same heights, or if you need to take into account that the earth is not a perfect sphere it gets a little more difficult.

updating table rows in postgres using subquery

Postgres allows:

UPDATE dummy
SET customer=subquery.customer,
    address=subquery.address,
    partn=subquery.partn
FROM (SELECT address_id, customer, address, partn
      FROM  /* big hairy SQL */ ...) AS subquery
WHERE dummy.address_id=subquery.address_id;

This syntax is not standard SQL, but it is much more convenient for this type of query than standard SQL. I believe Oracle (at least) accepts something similar.

How to get the MD5 hash of a file in C++?

I have used Botan to perform this operation and others before. AraK has pointed out Crypto++. I guess both libraries are perfectly valid. Now it is up to you :-).

How do you use youtube-dl to download live streams (that are live)?

I'll be using this Live Event from NASA TV as an example:

https://www.youtube.com/watch?v=21X5lGlDOfg

First, list the formats for the video:

$  ~ youtube-dl --list-formats https://www.youtube.com/watch\?v\=21X5lGlDOfg
[youtube] 21X5lGlDOfg: Downloading webpage
[youtube] 21X5lGlDOfg: Downloading m3u8 information
[youtube] 21X5lGlDOfg: Downloading MPD manifest
[info] Available formats for 21X5lGlDOfg:
format code  extension  resolution note
91           mp4        256x144    HLS  197k , avc1.42c00b, 30.0fps, mp4a.40.5@ 48k
92           mp4        426x240    HLS  338k , avc1.4d4015, 30.0fps, mp4a.40.5@ 48k
93           mp4        640x360    HLS  829k , avc1.4d401e, 30.0fps, mp4a.40.2@128k
94           mp4        854x480    HLS 1380k , avc1.4d401f, 30.0fps, mp4a.40.2@128k
300          mp4        1280x720   3806k , avc1.4d4020, 60.0fps, mp4a.40.2 (best)

Pick the format you wish to download, and fetch the HLS m3u8 URL of the video from the manifest. I'll be using 94 mp4 854x480 HLS 1380k , avc1.4d401f, 30.0fps, mp4a.40.2@128k for this example:

?  ~ youtube-dl -f 94 -g https://www.youtube.com/watch\?v\=21X5lGlDOfg
https://manifest.googlevideo.com/api/manifest/hls_playlist/expire/1592099895/ei/1y_lXuLOEsnXyQWYs4GABw/ip/81.190.155.248/id/21X5lGlDOfg.3/itag/94/source/yt_live_broadcast/requiressl/yes/ratebypass/yes/live/1/goi/160/sgoap/gir%3Dyes%3Bitag%3D140/sgovp/gir%3Dyes%3Bitag%3D135/hls_chunk_host/r5---sn-h0auphxqp5-f5fs.googlevideo.com/playlist_duration/30/manifest_duration/30/vprv/1/playlist_type/DVR/initcwndbps/8270/mh/N8/mm/44/mn/sn-h0auphxqp5-f5fs/ms/lva/mv/m/mvi/4/pl/16/dover/11/keepalive/yes/beids/9466586/mt/1592078245/disable_polymer/true/sparams/expire,ei,ip,id,itag,source,requiressl,ratebypass,live,goi,sgoap,sgovp,playlist_duration,manifest_duration,vprv,playlist_type/sig/AOq0QJ8wRgIhAM2dGSece2shUTgS73Qa3KseLqnf85ca_9u7Laz7IDfSAiEAj8KHw_9xXVS_PV3ODLlwDD-xfN6rSOcLVNBpxKgkRLI%3D/lsparams/hls_chunk_host,initcwndbps,mh,mm,mn,ms,mv,mvi,pl/lsig/AG3C_xAwRQIhAJCO6kSwn7PivqMW7sZaiYFvrultXl6Qmu9wppjCvImzAiA7vkub9JaanJPGjmB4qhLVpHJOb9fZyhMEeh1EUCd-3Q%3D%3D/playlist/index.m3u8

Note that link could be different and it contains expiration timestamp, in this case 1592099895 (about 6 hours).

Now that you have the HLS playlist, you can open this URL in VLC and save it using "Record", or write a small ffmpeg command:

ffmpeg -i \
https://manifest.googlevideo.com/api/manifest/hls_playlist/expire/1592099895/ei/1y_lXuLOEsnXyQWYs4GABw/ip/81.190.155.248/id/21X5lGlDOfg.3/itag/94/source/yt_live_broadcast/requiressl/yes/ratebypass/yes/live/1/goi/160/sgoap/gir%3Dyes%3Bitag%3D140/sgovp/gir%3Dyes%3Bitag%3D135/hls_chunk_host/r5---sn-h0auphxqp5-f5fs.googlevideo.com/playlist_duration/30/manifest_duration/30/vprv/1/playlist_type/DVR/initcwndbps/8270/mh/N8/mm/44/mn/sn-h0auphxqp5-f5fs/ms/lva/mv/m/mvi/4/pl/16/dover/11/keepalive/yes/beids/9466586/mt/1592078245/disable_polymer/true/sparams/expire,ei,ip,id,itag,source,requiressl,ratebypass,live,goi,sgoap,sgovp,playlist_duration,manifest_duration,vprv,playlist_type/sig/AOq0QJ8wRgIhAM2dGSece2shUTgS73Qa3KseLqnf85ca_9u7Laz7IDfSAiEAj8KHw_9xXVS_PV3ODLlwDD-xfN6rSOcLVNBpxKgkRLI%3D/lsparams/hls_chunk_host,initcwndbps,mh,mm,mn,ms,mv,mvi,pl/lsig/AG3C_xAwRQIhAJCO6kSwn7PivqMW7sZaiYFvrultXl6Qmu9wppjCvImzAiA7vkub9JaanJPGjmB4qhLVpHJOb9fZyhMEeh1EUCd-3Q%3D%3D/playlist/index.m3u8 \
-c copy output.ts

How to return the current timestamp with Moment.js?

Try this

console.log(moment().format("MM ddd, YYYY HH:mm:ss a"));

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console.log(moment().format("MM ddd, YYYY hh:mm:ss a"));
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.22.1/moment.min.js"></script>
_x000D_
_x000D_
_x000D_

How get sound input from microphone in python, and process it on the fly?

I know it's an old question, but if someone is looking here again... see https://python-sounddevice.readthedocs.io/en/0.4.1/index.html .

It has a nice example "Input to Ouput Pass-Through" here https://python-sounddevice.readthedocs.io/en/0.4.1/examples.html#input-to-output-pass-through .

... and a lot of other examples as well ...

How do I use floating-point division in bash?

There are scenarios in wich you cannot use bc becouse it might simply not be present, like in some cut down versions of busybox or embedded systems. In any case limiting outer dependencies is always a good thing to do so you can always add zeroes to the number being divided by (numerator), that is the same as multiplying by a power of 10 (you should choose a power of 10 according to the precision you need), that will make the division output an integer number. Once you have that integer treat it as a string and position the decimal point (moving it from right to left) a number of times equal to the power of ten you multiplied the numerator by. This is a simple way of obtaining float results by using only integer numbers.

here-document gives 'unexpected end of file' error

Here is a flexible way to do deal with multiple indented lines without using heredoc.

  echo 'Hello!'
  sed -e 's:^\s*::' < <(echo '
    Some indented text here.
    Some indented text here.
  ')
  if [[ true ]]; then
    sed -e 's:^\s\{4,4\}::' < <(echo '
      Some indented text here.
        Some extra indented text here.
      Some indented text here.
    ')
  fi

Some notes on this solution:

  • if the content is expected to have simple quotes, either escape them using \ or replace the string delimiters with double quotes. In the latter case, be careful that construction like $(command) will be interpreted. If the string contains both simple and double quotes, you'll have to escape at least of kind.
  • the given example print a trailing empty line, there are numerous way to get rid of it, not included here to keep the proposal to a minimum clutter
  • the flexibility comes from the ease with which you can control how much leading space should stay or go, provided that you know some sed REGEXP of course.

How to add a .dll reference to a project in Visual Studio

You probably are looking for AddReference dialog accessible from Project Context Menu (right click..)

From there you can reference dll's, after which you can reference namespaces that you need in your code.

How can I remove an element from a list?

If you don't want to modify the list in-place (e.g. for passing the list with an element removed to a function), you can use indexing: negative indices mean "don't include this element".

x <- list("a", "b", "c", "d", "e"); # example list

x[-2];       # without 2nd element

x[-c(2, 3)]; # without 2nd and 3rd

Also, logical index vectors are useful:

x[x != "b"]; # without elements that are "b"

This works with dataframes, too:

df <- data.frame(number = 1:5, name = letters[1:5])

df[df$name != "b", ];     # rows without "b"

df[df$number %% 2 == 1, ] # rows with odd numbers only

How to create an array containing 1...N

The question was for alternatives to this technique but I wanted to share the faster way of doing this. It's nearly identical to the code in the question but it allocates memory instead of using push:

function range(n) {
    let a = Array(n);
    for (let i = 0; i < n; a[i++] = i);
    return a;
}

How to view the contents of an Android APK file?

4 suggested ways to open apk files:

1.open apk file by Android Studio (For Photo,java code and analyze size) the best way

enter image description here

2.open by applications winRar,7zip,etc (Just to see photos and ...)

3.use website javadecompilers (For Photo and java code)

4.use APK Tools (For Photo and java code)

How to use "Share image using" sharing Intent to share images in android?

I found the easiest way to do this is by using the MediaStore to temporarily store the image that you want to share:

Drawable mDrawable = mImageView.getDrawable();
Bitmap mBitmap = ((BitmapDrawable) mDrawable).getBitmap();

String path = MediaStore.Images.Media.insertImage(getContentResolver(), mBitmap, "Image Description", null);
Uri uri = Uri.parse(path);

Intent intent = new Intent(Intent.ACTION_SEND);
intent.setType("image/jpeg");
intent.putExtra(Intent.EXTRA_STREAM, uri);
startActivity(Intent.createChooser(intent, "Share Image"));

From: Sharing Content With Intents

How can I get current date in Android?

I wrote calendar app using CalendarView and it's my code:

CalendarView cal = (CalendarView) findViewById(R.id.calendar);
cal.setDate(new Date().getTime());

'calendar' field is my CalendarView. Imports:

import android.widget.CalendarView;
import java.util.Date;

I've got current date without errors.

How to check if array element exists or not in javascript?

This is exactly what the in operator is for. Use it like this:

if (index in currentData) 
{ 
    Ti.API.info(index + " exists: " + currentData[index]);
}

The accepted answer is wrong, it will give a false negative if the value at index is undefined:

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_x000D_
const currentData = ['a', undefined], index = 1;_x000D_
_x000D_
if (index in currentData) {_x000D_
  console.info('exists');_x000D_
}_x000D_
// ...vs..._x000D_
if (typeof currentData[index] !== 'undefined') {_x000D_
  console.info('exists');_x000D_
} else {_x000D_
  console.info('does not exist'); // incorrect!_x000D_
}
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_x000D_
_x000D_

Creating Scheduled Tasks

This works for me https://www.nuget.org/packages/ASquare.WindowsTaskScheduler/

It is nicely designed Fluent API.

//This will create Daily trigger to run every 10 minutes for a duration of 18 hours
SchedulerResponse response = WindowTaskScheduler
    .Configure()
    .CreateTask("TaskName", "C:\\Test.bat")
    .RunDaily()
    .RunEveryXMinutes(10)
    .RunDurationFor(new TimeSpan(18, 0, 0))
    .SetStartDate(new DateTime(2015, 8, 8))
    .SetStartTime(new TimeSpan(8, 0, 0))
    .Execute();

IE11 Document mode defaults to IE7. How to reset?

By default, IE displays webpages in the Intranet zone in compatibility view. To change this:

  • Press Alt to display the IE menu.
  • Choose Tools | Compatibility View settings
  • Remove the checkmark next to Display intranet sites in Compatibility View.
  • Choose Close.

At this point, IE should rely on the webpage itself (or any relevant group policies) to determine the compatibility settings for your Intranet webpages.

Note that certain sites may no longer function correctly after making this change. You can use the same dialog box to add specific sites to enable compatibility view when needed.

How to align checkboxes and their labels consistently cross-browsers

<fieldset class="checks">
    <legend>checks for whatevers</legend>
    <input type="" id="x" />
    <label for="x">Label</label>
    <input type="" id="y" />
    <label for="y">Label</label>
    <input type="" id="z" />
    <label for="z">Label</label>
</fieldset>

You should wrap form controls grouped together in their own fieldsets anyways, here, it plays the wrappa. set input/label do display:block, input float left, label float right, set your widths, control spacing with left/right margins, align label text accordingly.

so

fieldset.checks {
    width:200px
}
.checks input, .checks label {
    display:block;
}
.checks input {
    float:right;
    width:10px;
    margin-right:5px
}
.checks label {
    float:left;
    width:180px;
    margin-left:5px;
    text-align:left;
    text-indent:5px
}

you probably need to set border, outline and line-height on both as well for cross-browser/media solutions.

How Best to Compare Two Collections in Java and Act on Them?

I have created an approximation of what I think you are looking for just using the Collections Framework in Java. Frankly, I think it is probably overkill as @Mike Deck points out. For such a small set of items to compare and process I think arrays would be a better choice from a procedural standpoint but here is my pseudo-coded (because I'm lazy) solution. I have an assumption that the Foo class is comparable based on it's unique id and not all of the data in it's contents:

Collection<Foo> oldSet = ...;
Collection<Foo> newSet = ...;

private Collection difference(Collection a, Collection b) {
    Collection result = a.clone();
    result.removeAll(b)
    return result;
}

private Collection intersection(Collection a, Collection b) {
    Collection result = a.clone();
    result.retainAll(b)
    return result;
}

public doWork() {
    // if foo is in(*) oldSet but not newSet, call doRemove(foo)
    Collection removed = difference(oldSet, newSet);
    if (!removed.isEmpty()) {
        loop removed {
            Foo foo = removedIter.next();
            doRemove(foo);
        }
    }
    //else if foo is not in oldSet but in newSet, call doAdd(foo)
    Collection added = difference(newSet, oldSet);
    if (!added.isEmpty()) {
        loop added  {
            Foo foo = addedIter.next();
            doAdd(foo);
        }
    }

    // else if foo is in both collections but modified, call doUpdate(oldFoo, newFoo)
    Collection matched = intersection(oldSet, newSet);
    Comparator comp = new Comparator() {
        int compare(Object o1, Object o2) {
            Foo f1, f2;
            if (o1 instanceof Foo) f1 = (Foo)o1;
            if (o2 instanceof Foo) f2 = (Foo)o2;
            return f1.activated == f2.activated ? f1.startdate.compareTo(f2.startdate) == 0 ? ... : f1.startdate.compareTo(f2.startdate) : f1.activated ? 1 : 0;
        }

        boolean equals(Object o) {
             // equal to this Comparator..not used
        }
    }
    loop matched {
        Foo foo = matchedIter.next();
        Foo oldFoo = oldSet.get(foo);
        Foo newFoo = newSet.get(foo);
        if (comp.compareTo(oldFoo, newFoo ) != 0) {
            doUpdate(oldFoo, newFoo);
        } else {
            //else if !foo.activated && foo.startDate >= now, call doStart(foo)
            if (!foo.activated && foo.startDate >= now) doStart(foo);

            // else if foo.activated && foo.endDate <= now, call doEnd(foo)
            if (foo.activated && foo.endDate <= now) doEnd(foo);
        }
    }
}

As far as your questions: If I convert oldSet and newSet into HashMap (order is not of concern here), with the IDs as keys, would it made the code easier to read and easier to compare? How much of time & memory performance is loss on the conversion? I think that you would probably make the code more readable by using a Map BUT...you would probably use more memory and time during the conversion.

Would iterating the two sets and perform the appropriate operation be more efficient and concise? Yes, this would be the best of both worlds especially if you followed @Mike Sharek 's advice of Rolling your own List with the specialized methods or following something like the Visitor Design pattern to run through your collection and process each item.

Global npm install location on windows?

According to: https://docs.npmjs.com/files/folders

  • Local install (default): puts stuff in ./node_modules of the current package root.
  • Global install (with -g): puts stuff in /usr/local or wherever node is installed.
  • Install it locally if you're going to require() it.
  • Install it globally if you're going to run it on the command line. -> If you need both, then install it in both places, or use npm link.

prefix Configuration

The prefix config defaults to the location where node is installed. On most systems, this is /usr/local. On windows, this is the exact location of the node.exe binary.

The docs might be a little outdated, but they explain why global installs can end up in different directories:

(dev) go|c:\srv> npm config ls -l | grep prefix
; prefix = "C:\\Program Files\\nodejs" (overridden)
prefix = "C:\\Users\\bjorn\\AppData\\Roaming\\npm"

Based on the other answers, it may seem like the override is now the default location on Windows, and that I may have installed my office version prior to this override being implemented.

This also suggests a solution for getting all team members to have globals stored in the same absolute path relative to their PC, i.e. (run as Administrator):

mkdir %PROGRAMDATA%\npm
setx PATH "%PROGRAMDATA%\npm;%PATH%" /M
npm config set prefix %PROGRAMDATA%\npm

open a new cmd.exe window and reinstall all global packages.

Explanation (by lineno.):

  1. Create a folder in a sensible location to hold the globals (Microsoft is adamant that you shouldn't write to ProgramFiles, so %PROGRAMDATA% seems like the next logical place.
  2. The directory needs to be on the path, so use setx .. /M to set the system path (under HKEY_LOCAL_MACHINE). This is what requires you to run this in a shell with administrator permissions.
  3. Tell npm to use this new path. (Note: folder isn't visible in %PATH% in this shell, so you must open a new window).

how to change the default positioning of modal in bootstrap?

I know it's a bit late but I had issues with a modal window not allowing some links on the menu bar to work, even when it has not been triggered. But I solved it by doing the following:

.modal{
display:none;
}

Origin null is not allowed by Access-Control-Allow-Origin

I would like to humbly add that according to this SO source: https://stackoverflow.com/a/14671362/1743693, this kind of trouble is now partially solved simply by using the following jQuery instruction:

<script> 
    $.support.cors = true;
</script>

I tried it on IE10.0.9200, and it worked immediately (using jquery-1.9.0.js).

On chrome 28.0.1500.95 - this instruction doesn't work (this happens all over as david complains in the comments at the link above)

Running chrome with --allow-file-access-from-files did not work for me (as Maistora's claims above)

Difference between Subquery and Correlated Subquery

CORRELATED SUBQUERIES: Is evaluated for each row processed by the Main query. Execute the Inner query based on the value fetched by the Outer query. Continues till all the values returned by the main query are matched. The INNER Query is driven by the OUTER Query

Ex:

SELECT empno,fname,sal,deptid FROM emp e WHERE sal=(SELECT AVG(sal) FROM emp WHERE deptid=e.deptid)

The Correlated subquery specifically computes the AVG(sal) for each department.

SUBQUERY: Runs first,executed once,returns values to be used by the MAIN Query. The OUTER Query is driven by the INNER QUERY

XML Carriage return encoding

A browser isn't going to show you white space reliably. I recommend the Linux 'od' command to see what's really in there. Comforming XML parsers will respect all of the methods you listed.

PHP AES encrypt / decrypt

$sDecrypted and $sEncrypted were undefined in your code. See a solution that works (but is not secure!):


STOP!

This example is insecure! Do not use it!


$Pass = "Passwort";
$Clear = "Klartext";        

$crypted = fnEncrypt($Clear, $Pass);
echo "Encrypred: ".$crypted."</br>";

$newClear = fnDecrypt($crypted, $Pass);
echo "Decrypred: ".$newClear."</br>";        

function fnEncrypt($sValue, $sSecretKey)
{
    return rtrim(
        base64_encode(
            mcrypt_encrypt(
                MCRYPT_RIJNDAEL_256,
                $sSecretKey, $sValue, 
                MCRYPT_MODE_ECB, 
                mcrypt_create_iv(
                    mcrypt_get_iv_size(
                        MCRYPT_RIJNDAEL_256, 
                        MCRYPT_MODE_ECB
                    ), 
                    MCRYPT_RAND)
                )
            ), "\0"
        );
}

function fnDecrypt($sValue, $sSecretKey)
{
    return rtrim(
        mcrypt_decrypt(
            MCRYPT_RIJNDAEL_256, 
            $sSecretKey, 
            base64_decode($sValue), 
            MCRYPT_MODE_ECB,
            mcrypt_create_iv(
                mcrypt_get_iv_size(
                    MCRYPT_RIJNDAEL_256,
                    MCRYPT_MODE_ECB
                ), 
                MCRYPT_RAND
            )
        ), "\0"
    );
}

But there are other problems in this code which make it insecure, in particular the use of ECB (which is not an encryption mode, only a building block on top of which encryption modes can be defined). See Fab Sa's answer for a quick fix of the worst problems and Scott's answer for how to do this right.

C# How to determine if a number is a multiple of another?

Try

public bool IsDivisible(int x, int n)
{
   return (x % n) == 0;
}

The modulus operator % returns the remainder after dividing x by n which will always be 0 if x is divisible by n.

For more information, see the % operator on MSDN.

How to get the max of two values in MySQL?

You can use GREATEST function with not nullable fields. If one of this values (or both) can be NULL, don't use it (result can be NULL).

select 
    if(
        fieldA is NULL, 
        if(fieldB is NULL, NULL, fieldB), /* second NULL is default value */
        if(fieldB is NULL, field A, GREATEST(fieldA, fieldB))
    ) as maxValue

You can change NULL to your preferred default value (if both values is NULL).

Page redirect with successful Ajax request

$.ajax({
        url: 'mail3.php',
        type: 'POST',
        data: 'contactName=' + name + '&contactEmail=' + email + '&spam=' + spam,

        success: function(result) {

            //console.log(result);
            $('#results,#errors').remove();
            $('#contactWrapper').append('<p id="results">' + result + '</p>');
            $('#loading').fadeOut(500, function() {
                $(this).remove();

            });

            if(result === "no_errors") location.href = "http://www.example.com/ThankYou.html"

        }
    });

IndentationError: unexpected unindent WHY?

@MaxPython The answer above is missing ":"

try:
   #do something
except:
  # print 'error/exception'

def printError(e): print e

How do I change the default location for Git Bash on Windows?

I am using Git bash on Windows 10, here is my solution:

  1. Close all git bash sessions
  2. Hit windows key and type: env; then click Edit environment variables for your account (control panel)
  3. Under "User variables for ...."; hit New button
  4. Variable Name: HOME
  5. Variable value: path where you would like ~/ to be in git bash

Open a git bash session and test it by typing: pwd and double check by doing cd ~/ && pwd

How can I plot separate Pandas DataFrames as subplots?

You can manually create the subplots with matplotlib, and then plot the dataframes on a specific subplot using the ax keyword. For example for 4 subplots (2x2):

import matplotlib.pyplot as plt

fig, axes = plt.subplots(nrows=2, ncols=2)

df1.plot(ax=axes[0,0])
df2.plot(ax=axes[0,1])
...

Here axes is an array which holds the different subplot axes, and you can access one just by indexing axes.
If you want a shared x-axis, then you can provide sharex=True to plt.subplots.

Count distinct values

I think this link is pretty good.

Sample output from that link:

mysql> SELECT cate_id,COUNT(DISTINCT(pub_lang)), ROUND(AVG(no_page),2)
    -> FROM book_mast
    -> GROUP BY cate_id;
+---------+---------------------------+-----------------------+
| cate_id | COUNT(DISTINCT(pub_lang)) | ROUND(AVG(no_page),2) |
+---------+---------------------------+-----------------------+
| CA001   |                         2 |                264.33 | 
| CA002   |                         1 |                433.33 | 
| CA003   |                         2 |                256.67 | 
| CA004   |                         3 |                246.67 | 
| CA005   |                         3 |                245.75 | 
+---------+---------------------------+-----------------------+
5 rows in set (0.00 sec)

Unnamed/anonymous namespaces vs. static functions

I recently began replacing static keywords with anonymous namespaces in my code but immediately ran into a problem where the variables in the namespace were no longer available for inspection in my debugger. I was using VC60, so I don't know if that is a non-issue with other debuggers. My workaround was to define a 'module' namespace, where I gave it the name of my cpp file.

For example, in my XmlUtil.cpp file, I define a namespace XmlUtil_I { ... } for all of my module variables and functions. That way I can apply the XmlUtil_I:: qualification in the debugger to access the variables. In this case, the _I distinguishes it from a public namespace such as XmlUtil that I may want to use elsewhere.

I suppose a potential disadvantage of this approach compared to a truly anonymous one is that someone could violate the desired static scope by using the namespace qualifier in other modules. I don't know if that is a major concern though.

"Cannot send session cache limiter - headers already sent"

"Headers already sent" means that your PHP script already sent the HTTP headers, and as such it can't make modifications to them now.

Check that you don't send ANY content before calling session_start. Better yet, just make session_start the first thing you do in your PHP file (so put it at the absolute beginning, before all HTML etc).

Select row and element in awk

To print the columns with a specific string, you use the // search pattern. For example, if you are looking for second columns that contains abc:

awk '$2 ~ /abc/'

... and if you want to print only a particular column:

awk '$2 ~ /abc/ { print $3 }'

... and for a particular line number:

awk '$2 ~ /abc/ && FNR == 5 { print $3 }'

how to exit a python script in an if statement

This works fine for me:

while True:
   answer = input('Do you want to continue?:')
   if answer.lower().startswith("y"):
      print("ok, carry on then")
   elif answer.lower().startswith("n"):
      print("sayonara, Robocop")
      exit()

edit: use input in python 3.2 instead of raw_input

plot legends without border and with white background

As documented in ?legend you do this like so:

plot(1:10,type = "n")
abline(v=seq(1,10,1), col='grey', lty='dotted')
legend(1, 5, "This legend text should not be disturbed by the dotted grey lines,\nbut the plotted dots should still be visible",box.lwd = 0,box.col = "white",bg = "white")
points(1:10,1:10)

enter image description here

Line breaks are achieved with the new line character \n. Making the points still visible is done simply by changing the order of plotting. Remember that plotting in R is like drawing on a piece of paper: each thing you plot will be placed on top of whatever's currently there.

Note that the legend text is cut off because I made the plot dimensions smaller (windows.options does not exist on all R platforms).

Android Writing Logs to text File

You should take a look at microlog4android. They have a solution ready to log to a file.

http://code.google.com/p/microlog4android/

How do you copy a record in a SQL table but swap out the unique id of the new row?

I'm guessing you're trying to avoid writing out all the column names. If you're using SQL Management Studio you can easily right click on the table and Script As Insert.. then you can mess around with that output to create your query.

What is the use of static synchronized method in java?

Suppose there are multiple static synchronized methods (m1, m2, m3, m4) in a class, and suppose one thread is accessing m1, then no other thread at the same time can access any other static synchronized methods.

How can I disable the UITableView selection?

You can use ....

[cell setSelectionStyle:UITableViewCellSelectionStyleNone];

HTML5 input type range show range value

If you want your current value to be displayed beneath the slider and moving along with it, try this:

_x000D_
_x000D_
<!DOCTYPE html>_x000D_
<html>_x000D_
<head>_x000D_
  <meta charset="utf-8">_x000D_
  <title>MySliderValue</title>_x000D_
_x000D_
</head>_x000D_
<body>_x000D_
  <h1>MySliderValue</h1>_x000D_
_x000D_
  <div style="position:relative; margin:auto; width:90%">_x000D_
    <span style="position:absolute; color:red; border:1px solid blue; min-width:100px;">_x000D_
    <span id="myValue"></span>_x000D_
    </span>_x000D_
    <input type="range" id="myRange" max="1000" min="0" style="width:80%"> _x000D_
  </div>_x000D_
_x000D_
  <script type="text/javascript" charset="utf-8">_x000D_
var myRange = document.querySelector('#myRange');_x000D_
var myValue = document.querySelector('#myValue');_x000D_
var myUnits = 'myUnits';_x000D_
var off = myRange.offsetWidth / (parseInt(myRange.max) - parseInt(myRange.min));_x000D_
var px =  ((myRange.valueAsNumber - parseInt(myRange.min)) * off) - (myValue.offsetParent.offsetWidth / 2);_x000D_
_x000D_
  myValue.parentElement.style.left = px + 'px';_x000D_
  myValue.parentElement.style.top = myRange.offsetHeight + 'px';_x000D_
  myValue.innerHTML = myRange.value + ' ' + myUnits;_x000D_
_x000D_
  myRange.oninput =function(){_x000D_
    let px = ((myRange.valueAsNumber - parseInt(myRange.min)) * off) - (myValue.offsetWidth / 2);_x000D_
    myValue.innerHTML = myRange.value + ' ' + myUnits;_x000D_
    myValue.parentElement.style.left = px + 'px';_x000D_
  };_x000D_
  </script>_x000D_
_x000D_
</body>_x000D_
</html>
_x000D_
_x000D_
_x000D_

Note that this type of HTML input element has one hidden feature, such as you can move the slider with left/right/down/up arrow keys when the element has focus on it. The same with Home/End/PageDown/PageUp keys.

How do I automatically scroll to the bottom of a multiline text box?

This only worked for me...

txtSerialLogging->Text = "";

txtSerialLogging->AppendText(s);

I tried all the cases above, but the problem is in my case text s can decrease, increase and can also remain static for a long time. static means , static length(lines) but content is different.

So, I was facing one line jumping situation at the end when the length(lines) remains same for some times...

Counting how many times a certain char appears in a string before any other char appears

The simplest approach would be to use LINQ:

var count = text.TakeWhile(c => c == '$').Count();

There are certainly more efficient approaches, but that's probably the simplest.

Is it possible to insert HTML content in XML document?

so long as your html content doesn't need to contain a CDATA element, you can contain the HTML in a CDATA element, otherwise you'll have to escape the XML entities.

<element><![CDATA[<p>your html here</p>]]></element>

VS

<element>&lt;p&gt;your html here&lt;/p&gt;</element>

Address already in use: JVM_Bind

as the exception says there is already another server running on the same port. you can either kill that service or change glassfish to run on another poet

A potentially dangerous Request.Form value was detected from the client

Disable the page validation if you really need the special characters like, >, , <, etc. Then ensure that when the user input is displayed, the data is HTML-encoded.

There is a security vulnerability with the page validation, so it can be bypassed. Also the page validation shouldn't be solely relied on.

See: http://web.archive.org/web/20080913071637/http://www.procheckup.com:80/PDFs/bypassing-dot-NET-ValidateRequest.pdf

Unable to open debugger port in IntelliJ IDEA

Just restart the Android studio before try these all. I face same right now and i fix it by this way.

Happy coding :)

How do I check whether input string contains any spaces?

string name = "Paul Creasey";
if (name.contains(" ")) {

}

Array versus List<T>: When to use which?

Lists in .NET are wrappers over arrays, and use an array internally. The time complexity of operations on lists is the same as would be with arrays, however there is a little more overhead with all the added functionality / ease of use of lists (such as automatic resizing and the methods that come with the list class). Pretty much, I would recommend using lists in all cases unless there is a compelling reason not to do so, such as if you need to write extremely optimized code, or are working with other code that is built around arrays.

Top 1 with a left join

Because the TOP 1 from the ordered sub-query does not have profile_id = 'u162231993' Remove where u.id = 'u162231993' and see results then.

Run the sub-query separately to understand what's going on.

How can you tell if a value is not numeric in Oracle?

There is no built-in function. You could write one

CREATE FUNCTION is_numeric( p_str IN VARCHAR2 )
  RETURN NUMBER
IS
  l_num NUMBER;
BEGIN
  l_num := to_number( p_str );
  RETURN 1;
EXCEPTION
  WHEN value_error
  THEN
    RETURN 0;
END;

and/or

CREATE FUNCTION my_to_number( p_str IN VARCHAR2 )
  RETURN NUMBER
IS
  l_num NUMBER;
BEGIN
  l_num := to_number( p_str );
  RETURN l_num;
EXCEPTION
  WHEN value_error
  THEN
    RETURN NULL;
END;

You can then do

IF( is_numeric( str ) = 1 AND 
    my_to_number( str ) >= 1000 AND
    my_to_number( str ) <= 7000 )

If you happen to be using Oracle 12.2 or later, there are enhancements to the to_number function that you could leverage

IF( to_number( str default null on conversion error ) >= 1000 AND
    to_number( str default null on conversion error ) <= 7000 )

ArrayList of String Arrays

Use a second ArrayList for the 3 strings, not a primitive array. Ie.
private List<List<String>> addresses = new ArrayList<List<String>>();

Then you can have:

ArrayList<String> singleAddress = new ArrayList<String>();
singleAddress.add("17 Fake Street");
singleAddress.add("Phoney town");
singleAddress.add("Makebelieveland");

addresses.add(singleAddress);

(I think some strange things can happen with type erasure here, but I don't think it should matter here)

If you're dead set on using a primitive array, only a minor change is required to get your example to work. As explained in other answers, the size of the array can not be included in the declaration. So changing:

private ArrayList<String[]> addresses = new ArrayList<String[3]>();

to

private ArrayList<String[]> addresses = new ArrayList<String[]>();

will work.

"[notice] child pid XXXX exit signal Segmentation fault (11)" in apache error.log

Attach gdb to one of the httpd child processes and reload or continue working and wait for a crash and then look at the backtrace. Do something like this:

$ ps -ef|grep httpd
0     681     1   0 10:38pm ??         0:00.45 /Applications/MAMP/Library/bin/httpd -k start
501   690   681   0 10:38pm ??         0:00.02 /Applications/MAMP/Library/bin/httpd -k start

...

Now attach gdb to one of the child processes, in this case PID 690 (columns are UID, PID, PPID, ...)

$ sudo gdb
(gdb) attach 690
Attaching to process 690.
Reading symbols for shared libraries . done
Reading symbols for shared libraries ....................... done
0x9568ce29 in accept$NOCANCEL$UNIX2003 ()
(gdb) c
Continuing.

Wait for crash... then:

(gdb) backtrace

Or

(gdb) backtrace full

Should give you some clue what's going on. If you file a bug report you should include the backtrace.

If the crash is hard to reproduce it may be a good idea to configure Apache to only use one child processes for handling requests. The config is something like this:

StartServers 1
MinSpareServers 1
MaxSpareServers 1

How to convert a Hibernate proxy to a real entity object

I found a solution to deproxy a class using standard Java and JPA API. Tested with hibernate, but does not require hibernate as a dependency and should work with all JPA providers.

Onle one requirement - its necessary to modify parent class (Address) and add a simple helper method.

General idea: add helper method to parent class which returns itself. when method called on proxy, it will forward the call to real instance and return this real instance.

Implementation is a little bit more complex, as hibernate recognizes that proxied class returns itself and still returns proxy instead of real instance. Workaround is to wrap returned instance into a simple wrapper class, which has different class type than the real instance.

In code:

class Address {
   public AddressWrapper getWrappedSelf() {
       return new AddressWrapper(this);
   }
...
}

class AddressWrapper {
    private Address wrappedAddress;
...
}

To cast Address proxy to real subclass, use following:

Address address = dao.getSomeAddress(...);
Address deproxiedAddress = address.getWrappedSelf().getWrappedAddress();
if (deproxiedAddress instanceof WorkAddress) {
WorkAddress workAddress = (WorkAddress)deproxiedAddress;
}

How do I improve ASP.NET MVC application performance?

If you are running your ASP.NET MVC application on Microsoft Azure (IaaS or PaaS), then do the following at least at before the first deployment.

  • Scan your code with static code analyzer for any type of code debt, duplication, complexity and for security.
  • Always enable the Application Insight, and monitor the performance, browsers, and analytics frequently to find the real-time issues in the application.
  • Implement Azure Redis Cache for static and less frequent change data like Images, assets, common layouts etc.
  • Always rely on APM (Application Performance Management) tools provided by Azure.
  • See application map frequently to investigate the communication performance between internal parts of the application.
  • Monitor Database/VM performance too.
  • Use Load Balancer (Horizontal Scale) if required and within the budget.
  • If your application has the target audience all over the globe, then use Azure Trafic Manager to automatically handle the incoming request and divert it to the most available application instance.
  • Try to automate the performance monitoring by writing the alerts based on low performance.

SQL Server SELECT INTO @variable?

Sounds like you want temp tables. http://www.sqlteam.com/article/temporary-tables

Note that #TempTable is available throughout your SP.

Note the ##TempTable is available to all.

How to unstash only certain files?

git checkout stash@{N} <File(s)/Folder(s) path> 

Eg. To restore only ./test.c file and ./include folder from last stashed,

git checkout stash@{0} ./test.c ./include

converting list to json format - quick and easy way

For me, it worked to use Newtonsoft.Json:

using Newtonsoft.Json;
// ...
var output = JsonConvert.SerializeObject(ListOfMyObject);

Convert Python program to C/C++ code?

I know this is an older thread but I wanted to give what I think to be helpful information.

I personally use PyPy which is really easy to install using pip. I interchangeably use Python/PyPy interpreter, you don't need to change your code at all and I've found it to be roughly 40x faster than the standard python interpreter (Either Python 2x or 3x). I use pyCharm Community Edition to manage my code and I love it.

I like writing code in python as I think it lets you focus more on the task than the language, which is a huge plus for me. And if you need it to be even faster, you can always compile to a binary for Windows, Linux, or Mac (not straight forward but possible with other tools). From my experience, I get about 3.5x speedup over PyPy when compiling, meaning 140x faster than python. PyPy is available for Python 3x and 2x code and again if you use an IDE like PyCharm you can interchange between say PyPy, Cython, and Python very easily (takes a little of initial learning and setup though).

Some people may argue with me on this one, but I find PyPy to be faster than Cython. But they're both great choices though.

Edit: I'd like to make another quick note about compiling: when you compile, the resulting binary is much bigger than your python script as it builds all dependencies into it, etc. But then you get a few distinct benefits: speed!, now the app will work on any machine (depending on which OS you compiled for, if not all. lol) without Python or libraries, it also obfuscates your code and is technically 'production' ready (to a degree). Some compilers also generate C code, which I haven't really looked at or seen if it's useful or just gibberish. Good luck.

Hope that helps.

How do I count unique items in field in Access query?

Access-Engine does not support

SELECT count(DISTINCT....) FROM ...

You have to do it like this:

SELECT count(*) 
FROM
(SELECT DISTINCT Name FROM table1)

Its a little workaround... you're counting a DISTINCT selection.

Css height in percent not working

You need to set 100% height on the parent element.

What Regex would capture everything from ' mark to the end of a line?

'.*$

Starting with a single quote ('), match any character (.) zero or more times (*) until the end of the line ($).

How do I solve the "server DNS address could not be found" error on Windows 10?

Steps to manually configure DNS:

  1. You can access Network and Sharing center by right clicking on the Network icon on the taskbar.

  2. Now choose adapter settings from the side menu.

  3. This will give you a list of the available network adapters in the system . From them right click on the adapter you are using to connect to the internet now and choose properties option.

  4. In the networking tab choose ‘Internet Protocol Version 4 (TCP/IPv4)’.

  5. Now you can see the properties dialogue box showing the properties of IPV4. Here you need to change some properties.

    Select ‘use the following DNS address’ option. Now fill the following fields as given here.

    Preferred DNS server: 208.67.222.222

    Alternate DNS server : 208.67.220.220

    This is an available Open DNS address. You may also use google DNS server addresses.

    After filling these fields. Check the ‘validate settings upon exit’ option. Now click OK.

You have to add this DNS server address in the router configuration also (by referring the router manual for more information).

Refer : for above method & alternative

If none of this works, then open command prompt(Run as Administrator) and run these:

ipconfig /flushdns
ipconfig /registerdns
ipconfig /release
ipconfig /renew
NETSH winsock reset catalog
NETSH int ipv4 reset reset.log
NETSH int ipv6 reset reset.log
Exit

Hopefully that fixes it, if its still not fixed there is a chance that its a NIC related issue(driver update or h/w).

Also FYI, this has a thread on Microsoft community : Windows 10 - DNS Issue

Remove first 4 characters of a string with PHP

function String2Stars($string='',$first=0,$last=0,$rep='*'){
  $begin  = substr($string,0,$first);
  $middle = str_repeat($rep,strlen(substr($string,$first,$last)));
  $end    = substr($string,$last);
  $stars  = $begin.$middle.$end;
  return $stars;
}

example

$string = 'abcdefghijklmnopqrstuvwxyz';
echo String2Stars($string,5,-5);   // abcde****************vwxyz

Display Bootstrap Modal using javascript onClick

I had the same problem, after researching a lot, I finally built a js function to create modals dynamically based on my requirements. Using this function, you can create popups in one line such as:

puyModal({title:'Test Title',heading:'Heading',message:'This is sample message.'})

Or you can use other complex functionality such as iframes, video popups, etc.

Find it on https://github.com/aybhalala/puymodals For demo, go to http://pateladitya.com/puymodals/

How to use protractor to check if an element is visible?

I had a similar issue, in that I only wanted return elements that were visible in a page object. I found that I'm able to use the css :not. In the case of this issue, this should do you...

expect($('i.icon-spinner:not(.ng-hide)').isDisplayed()).toBeTruthy();

In the context of a page object, you can get ONLY those elements that are visible in this way as well. Eg. given a page with multiple items, where only some are visible, you can use:

this.visibileIcons = $$('i.icon:not(.ng-hide)'); 

This will return you all visible i.icons

How to log a method's execution time exactly in milliseconds?

Since you want to optimize time moving from one page to another in a UIWebView, does it not mean you really are looking to optimize the Javascript used in loading these pages?

To that end, I'd look at a WebKit profiler like that talked about here:

http://www.alertdebugging.com/2009/04/29/building-a-better-javascript-profiler-with-webkit/

Another approach would be to start at a high level, and think how you can design the web pages in question to minimize load times using AJAX style page loading instead of refreshing the whole webview each time.

Simplest PHP example for retrieving user_timeline with Twitter API version 1.1

Important Note: As of mid-2018, the process to get twitter API tokens became a lot more bureaucratic. It has taken me over one working week to be provided a set of API tokens, and this is for an open source project for you guys and girls with over 1.2 million installations on Packagist and 1.6k stars on Github, which theoretically should be higher priority.

If you are tasked with working with the twitter API for your work, you must take this potentially extremely long wait-time into account. Also consider other social media avenues like Facebook or Instagram and provide these options, as the process for retrieving their tokens is instant.


So you want to use the Twitter v1.1 API?

Note: the files for these are on GitHub.

Version 1.0 will soon be deprecated and unauthorised requests won't be allowed. So, here's a post to help you do just that, along with a PHP class to make your life easier.

1. Create a developer account: Set yourself up a developer account on Twitter

You need to visit the official Twitter developer site and register for a developer account. This is a free and necessary step to make requests for the v1.1 API.

2. Create an application: Create an application on the Twitter developer site

What? You thought you could make unauthenticated requests? Not with Twitter's v1.1 API. You need to visit http://dev.twitter.com/apps and click the "Create Application" button.

Enter image description here

On this page, fill in whatever details you want. For me, it didn't matter, because I just wanted to make a load of block requests to get rid of spam followers. The point is you are going to get yourself a set of unique keys to use for your application.

So, the point of creating an application is to give yourself (and Twitter) a set of keys. These are:

  • The consumer key
  • The consumer secret
  • The access token
  • The access token secret

There's a little bit of information here on what these tokens for.

3. Create access tokens: You'll need these to make successful requests

OAuth requests a few tokens. So you need to have them generated for you.

Enter image description here

Click "create my access token" at the bottom. Then once you scroll to the bottom again, you'll have some newly generated keys. You need to grab the four previously labelled keys from this page for your API calls, so make a note of them somewhere.

4. Change access level: You don't want read-only, do you?

If you want to make any decent use of this API, you'll need to change your settings to Read & Write if you're doing anything other than standard data retrieval using GET requests.

Enter image description here

Choose the "Settings" tab near the top of the page.

Enter image description here

Give your application read / write access, and hit "Update" at the bottom.

You can read more about the applications permission model that Twitter uses here.


5. Write code to access the API: I've done most of it for you

I combined the code above, with some modifications and changes, into a PHP class so it's really simple to make the requests you require.

This uses OAuth and the Twitter v1.1 API, and the class I've created which you can find below.

require_once('TwitterAPIExchange.php');

/** Set access tokens here - see: https://dev.twitter.com/apps/ **/
$settings = array(
    'oauth_access_token' => "YOUR_OAUTH_ACCESS_TOKEN",
    'oauth_access_token_secret' => "YOUR_OAUTH_ACCESS_TOKEN_SECRET",
    'consumer_key' => "YOUR_CONSUMER_KEY",
    'consumer_secret' => "YOUR_CONSUMER_SECRET"
);

Make sure you put the keys you got from your application above in their respective spaces.

Next you need to choose a URL you want to make a request to. Twitter has their API documentation to help you choose which URL and also the request type (POST or GET).

/** URL for REST request, see: https://dev.twitter.com/docs/api/1.1/ **/
$url = 'https://api.twitter.com/1.1/blocks/create.json';
$requestMethod = 'POST';

In the documentation, each URL states what you can pass to it. If we're using the "blocks" URL like the one above, I can pass the following POST parameters:

/** POST fields required by the URL above. See relevant docs as above **/
$postfields = array(
    'screen_name' => 'usernameToBlock', 
    'skip_status' => '1'
);

Now that you've set up what you want to do with the API, it's time to make the actual request.

/** Perform the request and echo the response **/
$twitter = new TwitterAPIExchange($settings);
echo $twitter->buildOauth($url, $requestMethod)
             ->setPostfields($postfields)
             ->performRequest();

And for a POST request, that's it!

For a GET request, it's a little different. Here's an example:

/** Note: Set the GET field BEFORE calling buildOauth(); **/
$url = 'https://api.twitter.com/1.1/followers/ids.json';
$getfield = '?username=J7mbo';
$requestMethod = 'GET';
$twitter = new TwitterAPIExchange($settings);
echo $twitter->setGetfield($getfield)
             ->buildOauth($url, $requestMethod)
             ->performRequest();     

Final code example: For a simple GET request for a list of my followers.

$url = 'https://api.twitter.com/1.1/followers/list.json';
$getfield = '?username=J7mbo&skip_status=1';
$requestMethod = 'GET';
$twitter = new TwitterAPIExchange($settings);
echo $twitter->setGetfield($getfield)
             ->buildOauth($url, $requestMethod)
             ->performRequest();  

I've put these files on GitHub with credit to @lackovic10 and @rivers! I hope someone finds it useful; I know I did (I used it for bulk blocking in a loop).

Also, for those on Windows who are having problems with SSL certificates, look at this post. This library uses cURL under the hood so you need to make sure you have your cURL certs set up probably. Google is also your friend.

Configure Nginx with proxy_pass

Nginx prefers prefix-based location matches (not involving regular expression), that's why in your code block, /stash redirects are going to /.

The algorithm used by Nginx to select which location to use is described thoroughly here: https://www.digitalocean.com/community/tutorials/understanding-nginx-server-and-location-block-selection-algorithms#matching-location-blocks

iOS: Multi-line UILabel in Auto Layout

I have a UITableViewCell which has a text wrap label. I worked text wrapping as follows.

1) Set UILabel constraints as follows.

enter image description here

2) Set no. of lines to 0.

3) Added UILabel height constraint to UITableViewCell.

@IBOutlet weak var priorityLabelWidth: NSLayoutConstraint!

4) On UITableViewCell:

priorityLabel.sizeToFit()
priorityLabelWidth.constant = priorityLabel.intrinsicContentSize().width+5

When should you use 'friend' in C++?

The friend keyword has a number of good uses. Here are the two uses immediately visible to me:

Friend Definition

Friend definition allows to define a function in class-scope, but the function will not be defined as a member function, but as a free function of the enclosing namespace, and won't be visible normally except for argument dependent lookup. That makes it especially useful for operator overloading:

namespace utils {
    class f {
    private:
        typedef int int_type;
        int_type value;

    public:
        // let's assume it doesn't only need .value, but some
        // internal stuff.
        friend f operator+(f const& a, f const& b) {
            // name resolution finds names in class-scope. 
            // int_type is visible here.
            return f(a.value + b.value);
        }

        int getValue() const { return value; }
    };
}

int main() {
    utils::f a, b;
    std::cout << (a + b).getValue(); // valid
}

Private CRTP Base Class

Sometimes, you find the need that a policy needs access to the derived class:

// possible policy used for flexible-class.
template<typename Derived>
struct Policy {
    void doSomething() {
        // casting this to Derived* requires us to see that we are a 
        // base-class of Derived.
        some_type const& t = static_cast<Derived*>(this)->getSomething();
    }
};

// note, derived privately
template<template<typename> class SomePolicy>
struct FlexibleClass : private SomePolicy<FlexibleClass> {
    // we derive privately, so the base-class wouldn't notice that, 
    // (even though it's the base itself!), so we need a friend declaration
    // to make the base a friend of us.
    friend class SomePolicy<FlexibleClass>;

    void doStuff() {
         // calls doSomething of the policy
         this->doSomething();
    }

    // will return useful information
    some_type getSomething();
};

You will find a non-contrived example for that in this answer. Another code using that is in this answer. The CRTP base casts its this pointer, to be able to access data-fields of the derived class using data-member-pointers.

Can I hide the HTML5 number input’s spin box?

Maybe change the number input with javascript to text input when you don't want a spinner;

document.getElementById('myinput').type = 'text';

and stop the user entering text;

  document.getElementById('myinput').onkeydown = function(e) {
  if(!((e.keyCode > 95 && e.keyCode < 106)
    || (e.keyCode > 47 && e.keyCode < 58) 
    || e.keyCode == 8
    || e.keyCode == 9)) {
          return false;
      }
  }

then have the javascript change it back in case you do want a spinner;

document.getElementById('myinput').type = 'number';

it worked well for my purposes

java.net.UnknownHostException: Invalid hostname for server: local

Try the following :

String url = "http://www.google.com/search?q=java";
URL urlObj = (URL)new URL(url.trim());
HttpURLConnection httpConn = 
(HttpURLConnection)urlObj.openConnection();
httpConn.setRequestMethod("GET");
Integer rescode = httpConn.getResponseCode();
System.out.println(rescode);

Trim() the URL

Case Function Equivalent in Excel

If you don't have a SWITCH statement in your Excel version (pre-Excel-2016), here's a VBA implementation for it:

Public Function SWITCH(ParamArray args() As Variant) As Variant
    Dim i As Integer
    Dim val As Variant
    Dim tmp As Variant

    If ((UBound(args) - LBound(args)) = 0) Or (((UBound(args) - LBound(args)) Mod 2 = 0)) Then
        Error 450       'Invalid arguments
    Else
        val = args(LBound(args))
        i = LBound(args) + 1
        tmp = args(UBound(args))

        While (i < UBound(args))
            If val = args(i) Then
                tmp = args(i + 1)
            End If
            i = i + 2
        Wend
    End If

    SWITCH = tmp
End Function

It works exactly like expected, a drop-in replacement for example for Google Spreadsheet's SWITCH function.

Syntax:

=SWITCH(selector; [keyN; valueN;] ...  defaultvalue)

where

  • selector is any expression that is compared to keys
  • key1, key2, ... are expressions that are compared to the selector
  • value1, value2, ... are values that are selected if the selector equals to the corresponding key (only)
  • defaultvalue is used if no key matches the selector

Examples:

=SWITCH("a";"?")                       returns "?"
=SWITCH("a";"a";"1";"?")               returns "1"
=SWITCH("x";"a";"1";"?")               returns "?"
=SWITCH("b";"a";"1";"b";TRUE;"?")      returns TRUE
=SWITCH(7;7;1;7;2;0)                   returns 2
=SWITCH("a";"a";"1")                   returns #VALUE!

To use it, open your Excel, go to Develpment tools tab, click Visual Basic, rightclick on ThisWorkbook, choose Insert, then Module, finally copy the code into the editor. You have to save as a macro-friendly Excel workbook (xlsm).

Adding attribute in jQuery

Add attribute as:

$('#Selector_id').attr('disabled',true);

How to handle "Uncaught (in promise) DOMException: play() failed because the user didn't interact with the document first." on Desktop with Chrome 66?

To make the autoplay on html 5 elements work after the chrome 66 update you just need to add the muted property to the video element.

So your current video HTML

_x000D_
_x000D_
<video_x000D_
    title="Advertisement"_x000D_
    webkit-playsinline="true"_x000D_
    playsinline="true"_x000D_
    style="background-color: rgb(0, 0, 0); position: absolute; width: 640px; height: 360px;"_x000D_
    src="http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/BigBuckBunny.mp4"_x000D_
    autoplay=""></video>
_x000D_
_x000D_
_x000D_

Just needs muted="muted"

_x000D_
_x000D_
<video_x000D_
    title="Advertisement"_x000D_
    style="background-color: rgb(0, 0, 0); position: absolute; width: 640px; height: 360px;"_x000D_
    src="http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/BigBuckBunny.mp4"_x000D_
    autoplay="true"_x000D_
    muted="muted"></video>
_x000D_
_x000D_
_x000D_

I believe the chrome 66 update is trying to stop tabs creating random noise on the users tabs. That's why the muted property make the autoplay work again.

System.currentTimeMillis() vs. new Date() vs. Calendar.getInstance().getTime()

System.currentTimeMillis() is obviously the most efficient since it does not even create an object, but new Date() is really just a thin wrapper about a long, so it is not far behind. Calendar, on the other hand, is relatively slow and very complex, since it has to deal with the considerably complexity and all the oddities that are inherent to dates and times (leap years, daylight savings, timezones, etc.).

It's generally a good idea to deal only with long timestamps or Date objects within your application, and only use Calendar when you actually need to perform date/time calculations, or to format dates for displaying them to the user. If you have to do a lot of this, using Joda Time is probably a good idea, for the cleaner interface and better performance.

ASP.NET Core configuration for .NET Core console application

It's something like this, for a dotnet 2.x core console application:

        using Microsoft.Extensions.Configuration;
        using Microsoft.Extensions.DependencyInjection;
        using Microsoft.Extensions.Logging;

        [...]
        var configuration = new ConfigurationBuilder()
            .SetBasePath(Directory.GetCurrentDirectory())
            .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
            .AddEnvironmentVariables()
            .Build();
        var serviceProvider = new ServiceCollection()
            .AddLogging(options => options.AddConfiguration(configuration).AddConsole())
            .AddSingleton<IConfiguration>(configuration)
            .AddSingleton<SomeService>()
            .BuildServiceProvider();
        [...]
        await serviceProvider.GetService<SomeService>().Start();

The you could inject ILoggerFactory, IConfiguration in the SomeService.

How do I find the index of a character within a string in C?

Just subtract the string address from what strchr returns:

char *string = "qwerty";
char *e;
int index;

e = strchr(string, 'e');
index = (int)(e - string);

Note that the result is zero based, so in above example it will be 2.

How to align footer (div) to the bottom of the page?

UPDATE

My original answer is from a long time ago, and the links are broken; updating it so that it continues to be useful.

I'm including updated solutions inline, as well as a working examples on JSFiddle. Note: I'm relying on a CSS reset, though I'm not including those styles inline. Refer to normalize.css

Solution 1 - margin offset

https://jsfiddle.net/UnsungHero97/ur20fndv/2/

HTML

<div id="wrapper">
  <div id="content">
    <h1>Hello, World!</h1>
  </div>
</div>
<footer id="footer">
  <div id="footer-content">Sticky Footer</div>
</footer>

CSS

html, body {
  margin: 0px;
  padding: 0px;
  min-height: 100%;
  height: 100%;
}

#wrapper {
  background-color: #e3f2fd;
  min-height: 100%;
  height: auto !important;
  margin-bottom: -50px; /* the bottom margin is the negative value of the footer's total height */
}

#wrapper:after {
  content: "";
  display: block;
  height: 50px; /* the footer's total height */
}

#content {
  height: 100%;
}

#footer {
  height: 50px; /* the footer's total height */
}

#footer-content {
  background-color: #f3e5f5;
  border: 1px solid #ab47bc;
  height: 32px; /* height + top/bottom paddding + top/bottom border must add up to footer height */
  padding: 8px;
}

Solution 2 - flexbox

https://jsfiddle.net/UnsungHero97/oqom5e5m/3/

HTML

<div id="content">
  <h1>Hello, World!</h1>
</div>
<footer id="footer">Sticky Footer</footer>

CSS

html {
  height: 100%;
}

body {
  display: flex;
  flex-direction: column;
  min-height: 100%;
}

#content {
  background-color: #e3f2fd;
  flex: 1;
  padding: 20px;
}

#footer {
  background-color: #f3e5f5;
  padding: 20px;
}

Here's some links with more detailed explanations and different approaches:


ORIGINAL ANSWER

Is this what you mean?

http://ryanfait.com/sticky-footer/

This method uses only 15 lines of CSS and hardly any HTML markup. Even better, it's completely valid CSS, and it works in all major browsers. Internet Explorer 5 and up, Firefox, Safari, Opera and more.

This footer will stay at the bottom of the page permanently. This means that if the content is more than the height of the browser window, you will need to scroll down to see the footer... but if the content is less than the height of the browser window, the footer will stick to the bottom of the browser window instead of floating up in the middle of the page.

Let me know if you need help with the implementation. I hope this helps.

Reading text files using read.table

From ?read.table: The number of data columns is determined by looking at the first five lines of input (or the whole file if it has less than five lines), or from the length of col.names if it is specified and is longer. This could conceivably be wrong if fill or blank.lines.skip are true, so specify col.names if necessary.

So, perhaps your data file isn't clean. Being more specific will help the data import:

d = read.table("foobar.txt", 
               sep="\t", 
               col.names=c("id", "name"), 
               fill=FALSE, 
               strip.white=TRUE)

will specify exact columns and fill=FALSE will force a two column data frame.

WCF Service, the type provided as the service attribute values…could not be found

  1. When you create an IIS application only the /bin or /App_Code folder is in the root directory of the IIS app. So just remember put all the code in the root /bin or /App_code directory (see http://blogs.msdn.com/b/chrsmith/archive/2006/08/10/wcf-service-nesting-in-iis.aspx).

  2. Make sure that the service name and the contract contain full name(e.g namespace.ClassName), and the service name and interface is the same as the name attribute of the service tag and contract of endpoint in web.config.

Invoking modal window in AngularJS Bootstrap UI using JavaScript

The AngularJS Bootstrap website hasn't been updated with the latest documentation. About 3 months ago pkozlowski-opensource authored a change to separate out $modal from $dialog commit is below:

https://github.com/angular-ui/bootstrap/commit/d7a48523e437b0a94615350a59be1588dbdd86bd

In that commit he added new documentation for $modal, which can be found below:

https://github.com/angular-ui/bootstrap/blob/d7a48523e437b0a94615350a59be1588dbdd86bd/src/modal/docs/readme.md.

Hope this helps!

Moment.js: Date between dates

You can use one of the moment plugin -> moment-range to deal with date range:

var startDate = new Date(2013, 1, 12)
  , endDate   = new Date(2013, 1, 15)
  , date  = new Date(2013, 2, 15)
  , range = moment().range(startDate, endDate);

range.contains(date); // false

CORS with POSTMAN

While all of the answers here are a really good explanation of what cors is but the direct answer to your question would be because of the following differences postman and browser.

Browser: Sends OPTIONS call to check the server type and getting the headers before sending any new request to the API endpoint. Where it checks for Access-Control-Allow-Origin. Taking this into account Access-Control-Allow-Origin header just specifies which all CROSS ORIGINS are allowed, although by default browser will only allow the same origin.

Postman: Sends direct GET, POST, PUT, DELETE etc. request without checking what type of server is and getting the header Access-Control-Allow-Origin by using OPTIONS call to the server.

SQL: How to perform string does not equal

Your where clause will return all rows where tester does not match username AND where tester is not null.

If you want to include NULLs, try:

where tester <> 'username' or tester is null

If you are looking for strings that do not contain the word "username" as a substring, then like can be used:

where tester not like '%username%'

HikariCP - connection is not available

From stack trace:

HikariPool: Timeout failure pool HikariPool-0 stats (total=20, active=20, idle=0, waiting=0) Means pool reached maximum connections limit set in configuration.

The next line: HikariPool-0 - Connection is not available, request timed out after 30000ms. Means pool waited 30000ms for free connection but your application not returned any connection meanwhile.

Mostly it is connection leak (connection is not closed after borrowing from pool), set leakDetectionThreshold to the maximum value that you expect SQL query would take to execute.

otherwise, your maximum connections 'at a time' requirement is higher than 20 !

HQL "is null" And "!= null" on an Oracle column

No. You have to use is null and is not null in HQL.

Rails DateTime.now without Time

What about Date.today.to_time?

How to change status bar color in Flutter?

Works for both iOS and Android

import 'package:flutter/services.dart';

@override
Widget build(BuildContext context) {
  SystemChrome.setSystemUIOverlayStyle(SystemUiOverlayStyle.dark);

  return Scaffold();
}
    

How to install a private NPM module without my own registry?

Very simple -

npm config set registry https://path-to-your-registry/

It actually sets registry = "https://path-to-your-registry" this line to /Users/<ur-machine-user-name>/.npmrc

All the value you have set explicitly or have been set by default can be seen by - npm config list

Running Internet Explorer 6, Internet Explorer 7, and Internet Explorer 8 on the same machine

There is one elegant way to run IE6, IE7 and IE8 on the same machine, called virtual PC.

First download virtual PC from Microsoft website here: http://www.microsoft.com/downloadS/details.aspx?FamilyID=04d26402-3199-48a3-afa2-2dc0b40a73b6&displaylang=en

Then download 3 EXE files with IE6, IE7 and IE8 here:http://www.microsoft.com/downloads/details.aspx?FamilyId=21EABB90-958F-4B64-B5F1-73D0A413C8EF&displaylang=en

Install them on your PC and test your web applications. Saved me days of looking for similar solutions.

.war vs .ear file

A WAR (Web Archive) is a module that gets loaded into a Web container of a Java Application Server. A Java Application Server has two containers (runtime environments) - one is a Web container and the other is a EJB container.

The Web container hosts Web applications based on JSP or the Servlets API - designed specifically for web request handling - so more of a request/response style of distributed computing. A Web container requires the Web module to be packaged as a WAR file - that is a special JAR file with a web.xml file in the WEB-INF folder.

An EJB container hosts Enterprise java beans based on the EJB API designed to provide extended business functionality such as declarative transactions, declarative method level security and multiprotocol support - so more of an RPC style of distributed computing. EJB containers require EJB modules to be packaged as JAR files - these have an ejb-jar.xml file in the META-INF folder.

Enterprise applications may consist of one or more modules that can either be Web modules (packaged as a WAR file), EJB modules (packaged as a JAR file), or both of them. Enterprise applications are packaged as EAR files - these are special JAR files containing an application.xml file in the META-INF folder.

Basically, EAR files are a superset containing WAR files and JAR files. Java Application Servers allow deployment of standalone web modules in a WAR file, though internally, they create EAR files as a wrapper around WAR files. Standalone web containers such as Tomcat and Jetty do not support EAR files - these are not full-fledged Application servers. Web applications in these containers are to be deployed as WAR files only.

In application servers, EAR files contain configurations such as application security role mapping, EJB reference mapping and context root URL mapping of web modules.

Apart from Web modules and EJB modules, EAR files can also contain connector modules packaged as RAR files and Client modules packaged as JAR files.

What is a faster alternative to Python's http.server (or SimpleHTTPServer)?

Also consider devd a small webserver written in go. Binaries for many platforms are available here.

devd -ol path/to/files/to/serve

It's small, fast, and provides some interesting optional features like live-reloading when your files change.

Update Android SDK Tool to 22.0.4(Latest Version) from 22.0.1

You may need to go to Window -> Android SDK Manager -> Packages -> Reload to fetch latest updates and then update the SDK.

Add new attribute (element) to JSON object using JavaScript

Uses $.extend() of jquery, like this:

token = {_token:window.Laravel.csrfToken};
data = {v1:'asdass',v2:'sdfsdf'}
dat = $.extend(token,data); 

I hope you serve them.

You are trying to add a non-nullable field 'new_field' to userprofile without a default

I honestly fount the best way to get around this was to just create another model with all the fields that you require and named slightly different. Run migrations. Delete unused model and run migrations again. Voila.

Adding padding to a tkinter widget only on one side

The padding options padx and pady of the grid and pack methods can take a 2-tuple that represent the left/right and top/bottom padding.

Here's an example:

import tkinter as tk

class MyApp():
    def __init__(self):
        self.root = tk.Tk()
        l1 = tk.Label(self.root, text="Hello")
        l2 = tk.Label(self.root, text="World")
        l1.grid(row=0, column=0, padx=(100, 10))
        l2.grid(row=1, column=0, padx=(10, 100)) 

app = MyApp()
app.root.mainloop()

Android: How to turn screen on and off programmatically?

Hi I hope this will help:

 private PowerManager mPowerManager;
 private PowerManager.WakeLock mWakeLock;

 public void turnOnScreen(){
     // turn on screen
     Log.v("ProximityActivity", "ON!");
     mWakeLock = mPowerManager.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP, "tag");
     mWakeLock.acquire();
}

 @TargetApi(21) //Suppress lint error for PROXIMITY_SCREEN_OFF_WAKE_LOCK
 public void turnOffScreen(){
     // turn off screen
     Log.v("ProximityActivity", "OFF!");
     mWakeLock = mPowerManager.newWakeLock(PowerManager.PROXIMITY_SCREEN_OFF_WAKE_LOCK, "tag");
     mWakeLock.acquire();
}

How do I set ANDROID_SDK_HOME environment variable?

from command prompt:

set ANDROID_SDK_HOME=C:\[wherever your sdk folder is]

should do the trick.

What's the difference between REST & RESTful

Coming at it from the perspective of an object oriented programming mindset, REST is analogous to the interface to be implemented, and a RESTfull service is analogous to the actual implementation of the REST "interface".

REST just defines a set of rules that says what it is to be a REST api, and a RESTfull service follows those rules.

Allot of answers above already laid out most of those rules, but I know one of the big things that is required, and in my experience often overlooked, as that a true REST api has to be hyperlink driven, in addition to all of the HTTP PUT, POST, GET, DELETE jazz.

belongs_to through associations

The has_many :choices creates an association named choices, not choice. Try using current_user.choices instead.

See the ActiveRecord::Associations documentation for information about about the has_many magic.

How can I let a user download multiple files when a button is clicked?

I've solved this a different way by using window.location. It works in Chrome, which fortunately is the only browser I had to support. Might be useful to someone. I'd initally used Dan's answer, which also needed the timeout I've used here or it only downloaded one file.

var linkArray = [];
linkArray.push("http://example.com/downloadablefile1");
linkArray.push("http://example.com/downloadablefile2");
linkArray.push("http://example.com/downloadablefile3");    

function (linkArray) {
  for (var i = 0; i < linkArray.length; i++) { 
    setTimeout(function (path) { window.location = path; }, 200 + i * 200, linkArray[i]);
  }        
};

The character encoding of the HTML document was not declared

I had the same problem when I ran my form application in Firefox. Adding <meta charset="utf-8"/> in the html code solved my issue in Firefox.

_x000D_
_x000D_
<!DOCTYPE html>_x000D_
<html>_x000D_
_x000D_
<head>_x000D_
  <meta charset="utf-8" />_x000D_
  <title>Voice clip upload</title>_x000D_
  <script src="voiceclip.js"></script>_x000D_
</head>_x000D_
_x000D_
<body>_x000D_
  <h2>Upload Voice Clip</h2>_x000D_
  <form id="upload_form" enctype="multipart/form-data" method="post">_x000D_
    <input type="file" name="file1" id="file1" onchange="uploadFile()"><br>_x000D_
    <progress id="progressBar" value="0" max="100" style="width:300px;"></progress>_x000D_
  </form>_x000D_
</body>_x000D_
_x000D_
</html>
_x000D_
_x000D_
_x000D_

Run all SQL files in a directory

If you can use Interactive SQL:

1 - Create a .BAT file with this code:

@ECHO OFF ECHO
for %%G in (*.sql) do dbisql -c "uid=dba;pwd=XXXXXXXX;ServerName=INSERT-DB-NAME-HERE" %%G
pause

2 - Change the pwd and ServerName.

3 - Put the .BAT file in the folder that contains .SQL files and run it.

How do I turn off PHP Notices?

Double defined constants

To fix the specific error here you can check if a constant is already defined before defining it:

if ( ! defined( 'DIR_FS_CATALOG' ) ) 
  define( 'DIR_FS_CATALOG', 'something...' );

I'd personally start with a search in the codebase for the constant DIR_FS_CATALOG, then replace the double definition with this.

Hiding PHP notices inline, case-by-case

PHP provides the @ error control operator, which you can use to ignore specific functions that cause notices or warnings.

Using this you can ignore/disable notices and warnings on a case-by-case basis in your code, which can be useful for situations where an error or notice is intentional, planned, or just downright annoying and not possible to solve at the source. Place an @ before the function or var that's causing a notice and it will be ignored.

Here's an example:

// Intentional file error
$missing_file = @file( 'non_existent_file' );

More on this can be found in PHP's Error Control Operators docs.

window.open(url, '_blank'); not working on iMac/Safari

You can't rely on window.open because browsers may have different policies. I had the same issue and I used the code below instead.

let a = document.createElement("a");
document.body.appendChild(a);
a.style = "display: none";
a.href = <your_url>;
a.download = <your_fileName>;
a.click();
document.body.removeChild(a);

Checking something isEmpty in Javascript?

If you're testing for an empty string:

if(myVar === ''){ // do stuff };

If you're checking for a variable that has been declared, but not defined:

if(myVar === null){ // do stuff };

If you're checking for a variable that may not be defined:

if(myVar === undefined){ // do stuff };

If you're checking both i.e, either variable is null or undefined:

if(myVar == null){ // do stuff };

Jenkins vs Travis-CI. Which one would you use for a Open Source project?

Travis-ci and Jenkins, while both are tools for continuous integration are very different.

Travis is a hosted service (free for open source) while you have to host, install and configure Jenkins.

Travis does not have jobs as in Jenkins. The commands to run to test the code are taken from a file named .travis.yml which sits along your project code. This makes it easy to have different test code per branch since each branch can have its own version of the .travis.yml file.

You can have a similar feature with Jenkins if you use one of the following plugins:

  • Travis YML Plugin - warning: does not seem to be popular, probably not feature complete in comparison to the real Travis.
  • Jervis - a modification of Jenkins to make it read create jobs from a .jervis.yml file found at the root of project code. If .jervis.yml does not exist, it will fall back to using .travis.yml file instead.

There are other hosted services you might also consider for continuous integration (non exhaustive list):


How to choose ?

You might want to stay with Jenkins because you are familiar with it or don't want to depend on 3rd party for your continuous integration system. Else I would drop Jenkins and go with one of the free hosted CI services as they save you a lot of trouble (host, install, configure, prepare jobs)

Depending on where your code repository is hosted I would make the following choices:

  • in-house ? Jenkins or gitlab-ci
  • Github.com ? Travis-CI

To setup Travis-CI on a github project, all you have to do is:

  • add a .travis.yml file at the root of your project
  • create an account at travis-ci.com and activate your project

The features you get are:

  • Travis will run your tests for every push made on your repo
  • Travis will run your tests on every pull request contributors will make

Understanding the Gemfile.lock file

It looks to me like PATH lists the first-generation dependencies directly from your gemspec, whereas GEM lists second-generation dependencies (i.e. what your dependencies depend on) and those from your Gemfile. PATH::remote is . because it relied on a local gemspec in the current directory to find out what belongs in PATH::spec, whereas GEM::remote is rubygems.org, since that's where it had to go to find out what belongs in GEM::spec.

In a Rails plugin, you'll see a PATH section, but not in a Rails app. Since the app doesn't have a gemspec file, there would be nothing to put in PATH.

As for DEPENDENCIES, gembundler.com states:

Runtime dependencies in your gemspec are treated like base dependencies, 
and development dependencies are added by default to the group, :development

The Gemfile generated by rails plugin new my_plugin says something similar:

# Bundler will treat runtime dependencies like base dependencies, and
# development dependencies will be added by default to the :development group.

What this means is that the difference between

s.add_development_dependency "july" # (1)

and

s.add_dependency "july" # (2)

is that (1) will only include "july" in Gemfile.lock (and therefore in the application) in a development environment. So when you run bundle install, you'll see "july" not only under PATH but also under DEPENDENCIES, but only in development. In production, it won't be there at all. However, when you use (2), you'll see "july" only in PATH, not in DEPENDENCIES, but it will show up when you bundle install from a production environment (i.e. in some other gem that includes yours as a dependency), not only development.

These are just my observations and I can't fully explain why any of this is the way it is but I welcome further comments.

How to make an image center (vertically & horizontally) inside a bigger div

In CSS do it as:

img
{

  display:table-cell;
  vertical-align:middle;
  margin:auto;
}

How to insert special characters into a database?

For Example:
$parent_category_name = Men's Clothing
Consider here the SQL query

$sql_category_name = "SELECT c.*, cd.name, cd.category_id  as iid FROM ". DB_PREFIX . "category c LEFT JOIN " . DB_PREFIX . "category_description cd ON (c.category_id = cd.category_id) WHERE cd.name = '" .  $this->db->escape($parent_category_name) . "' AND c.parent_id =0 "; 

Error:

Static analysis:

1 errors were found during analysis.

Ending quote ' was expected. (near "" at position 198)
SQL query: Documentation

SELECT c.*, cd.name, cd.category_id as iid FROM oc_category c LEFT JOIN oc_category_description cd ON (c.category_id = cd.category_id) WHERE cd.name = 'Men's Clothing' AND c.parent_id =0 LIMIT 0, 25

MySQL said: Documentation

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 's Clothing' AND c.parent_id =0 LIMIT 0, 25' at line 1

Try to implement:

$this->db->escape($parent_category_name)

The above method works on OpenCart framework. Find your framework & implement OR mysql_real_escape_string() in Core PHP

This will become Men\'s Clothing i.e, In my case

$sql_category_name = "SELECT c.*, cd.name, cd.category_id  as iid FROM ". DB_PREFIX . "category c LEFT JOIN " . DB_PREFIX . "category_description cd ON (c.category_id = cd.category_id) WHERE cd.name = '" .  $this->db->escape($parent_category_name) . "' AND c.parent_id =0 "; 

So you'll get the clear picture of the query by implementing escape() as

SELECT c.*, cd.name, cd.category_id as iid FROM oc_category c LEFT JOIN oc_category_description cd ON (c.category_id = cd.category_id) WHERE cd.name = 'Men\'s Clothing' AND c.parent_id =0

import an array in python

Another option is numpy.genfromtxt, e.g:

import numpy as np
data = np.genfromtxt("myfile.dat",delimiter=",")

This will make data a numpy array with as many rows and columns as are in your file

Best way of invoking getter by reflection

I think this should point you towards the right direction:

import java.beans.*

for (PropertyDescriptor pd : Introspector.getBeanInfo(Foo.class).getPropertyDescriptors()) {
  if (pd.getReadMethod() != null && !"class".equals(pd.getName()))
    System.out.println(pd.getReadMethod().invoke(foo));
}

Note that you could create BeanInfo or PropertyDescriptor instances yourself, i.e. without using Introspector. However, Introspector does some caching internally which is normally a Good Thing (tm). If you're happy without a cache, you can even go for

// TODO check for non-existing readMethod
Object value = new PropertyDescriptor("name", Person.class).getReadMethod().invoke(person);

However, there are a lot of libraries that extend and simplify the java.beans API. Commons BeanUtils is a well known example. There, you'd simply do:

Object value = PropertyUtils.getProperty(person, "name");

BeanUtils comes with other handy stuff. i.e. on-the-fly value conversion (object to string, string to object) to simplify setting properties from user input.

How to display tables on mobile using Bootstrap?

All tables within bootstrap stretch according to the container they're in. You can put your tables inside a .span element to control the size. This SO Question may help you out

Why do Twitter Bootstrap tables always have 100% width?

Notepad++ Setting for Disabling Auto-open Previous Files

Ok, I had a problem with Notepad++ not remembering that I had chosen not the "Remember Current Session". I tried hacking the config file, but that didn't work. Then I found out that there is a secret config file in your C:\Users\myuseraccount\AppData\Roaming\Notepad++ directory (Windows 7 x64). Mine was empty, meaning who know where the config was really coming from, but I copied over the file with the one in C:\Program Files (x86)\Notepad++ and now everything works just like you would expect it to.

Reverse Singly Linked List Java

public class Linkedtest {
    public static void reverse(List<Object> list) {

        int lenght = list.size();
        for (int i = 0; i < lenght / 2; i++) {
            Object as = list.get(i);
            list.set(i, list.get(lenght - 1 - i));
            list.set(lenght - 1 - i, as);
        }
    }
    public static void main(String[] args) {
        LinkedList<Object> st = new LinkedList<Object>();
        st.add(1);
        st.add(2);
        st.add(3);
        st.add(4);
        st.add(5);
        Linkedtest.reverse(st);
        System.out.println("Reverse Value will be:"+st);
    }
}

This will be useful for any type of collection Object.

How to calculate a time difference in C++

Just a side note: if you're running on Windows, and you really really need precision, you can use QueryPerformanceCounter. It gives you time in (potentially) nanoseconds.

Val and Var in Kotlin

val property is similar to final property in Java. You are allowed to assign it a value only for one time. When you try to reassign it with a value for second time you will get a compilation error. Whereas var property is mutable which you are free to reassign it when you wish and for any times you want.

Submit two forms with one button

You can submit the first form using AJAX, otherwise the submission of one will prevent the other from being submitted.

Help with packages in java - import does not work

Okay, just to clarify things that have already been posted.

You should have the directory com, containing the directory company, containing the directory example, containing the file MyClass.java.

From the folder containing com, run:

$ javac com\company\example\MyClass.java

Then:

$ java com.company.example.MyClass
Hello from MyClass!

These must both be done from the root of the source tree. Otherwise, javac and java won't be able to find any other packages (in fact, java wouldn't even be able to run MyClass).

A short example

I created the folders "testpackage" and "testpackage2". Inside testpackage, I created TestPackageClass.java containing the following code:

package testpackage;

import testpackage2.MyClass;

public class TestPackageClass {
    public static void main(String[] args) {
        System.out.println("Hello from testpackage.TestPackageClass!");
        System.out.println("Now accessing " + MyClass.NAME);
    }
}

Inside testpackage2, I created MyClass.java containing the following code:

package testpackage2;
public class MyClass {
    public static String NAME = "testpackage2.MyClass";
}

From the directory containing the two new folders, I ran:

C:\examples>javac testpackage\*.java

C:\examples>javac testpackage2\*.java

Then:

C:\examples>java testpackage.TestPackageClass
Hello from testpackage.TestPackageClass!
Now accessing testpackage2.MyClass

Does that make things any clearer?

Permission denied at hdfs

Start a shell as hduser (from root) and run your command

sudo -u hduser bash
hadoop fs -put /usr/local/input-data/ /input

[update] Also note that the hdfs user is the super user and has all r/w privileges.

What is the => assignment in C# in a property signature

This is a new feature of C# 6 called an expression bodied member that allows you to define a getter only property using a lambda like function.

While it is considered syntactic sugar for the following, they may not produce identical IL:

public int MaxHealth
{
    get
    {
        return Memory[Address].IsValid
               ?   Memory[Address].Read<int>(Offs.Life.MaxHp)
               :   0;
    }
}

It turns out that if you compile both versions of the above and compare the IL generated for each you'll see that they are NEARLY the same.

Here is the IL for the classic version in this answer when defined in a class named TestClass:

.property instance int32 MaxHealth()
{
    .get instance int32 TestClass::get_MaxHealth()
}

.method public hidebysig specialname 
    instance int32 get_MaxHealth () cil managed 
{
    // Method begins at RVA 0x2458
    // Code size 71 (0x47)
    .maxstack 2
    .locals init (
        [0] int32
    )

    IL_0000: nop
    IL_0001: ldarg.0
    IL_0002: ldfld class [mscorlib]System.Collections.Generic.Dictionary`2<int64, class MemoryAddress> TestClass::Memory
    IL_0007: ldarg.0
    IL_0008: ldfld int64 TestClass::Address
    IL_000d: callvirt instance !1 class [mscorlib]System.Collections.Generic.Dictionary`2<int64, class MemoryAddress>::get_Item(!0)
    IL_0012: ldfld bool MemoryAddress::IsValid
    IL_0017: brtrue.s IL_001c

    IL_0019: ldc.i4.0
    IL_001a: br.s IL_0042

    IL_001c: ldarg.0
    IL_001d: ldfld class [mscorlib]System.Collections.Generic.Dictionary`2<int64, class MemoryAddress> TestClass::Memory
    IL_0022: ldarg.0
    IL_0023: ldfld int64 TestClass::Address
    IL_0028: callvirt instance !1 class [mscorlib]System.Collections.Generic.Dictionary`2<int64, class MemoryAddress>::get_Item(!0)
    IL_002d: ldarg.0
    IL_002e: ldfld class Offs TestClass::Offs
    IL_0033: ldfld class Life Offs::Life
    IL_0038: ldfld int64 Life::MaxHp
    IL_003d: callvirt instance !!0 MemoryAddress::Read<int32>(int64)

    IL_0042: stloc.0
    IL_0043: br.s IL_0045

    IL_0045: ldloc.0
    IL_0046: ret
} // end of method TestClass::get_MaxHealth

And here is the IL for the expression bodied member version when defined in a class named TestClass:

.property instance int32 MaxHealth()
{
    .get instance int32 TestClass::get_MaxHealth()
}

.method public hidebysig specialname 
    instance int32 get_MaxHealth () cil managed 
{
    // Method begins at RVA 0x2458
    // Code size 66 (0x42)
    .maxstack 2

    IL_0000: ldarg.0
    IL_0001: ldfld class [mscorlib]System.Collections.Generic.Dictionary`2<int64, class MemoryAddress> TestClass::Memory
    IL_0006: ldarg.0
    IL_0007: ldfld int64 TestClass::Address
    IL_000c: callvirt instance !1 class [mscorlib]System.Collections.Generic.Dictionary`2<int64, class MemoryAddress>::get_Item(!0)
    IL_0011: ldfld bool MemoryAddress::IsValid
    IL_0016: brtrue.s IL_001b

    IL_0018: ldc.i4.0
    IL_0019: br.s IL_0041

    IL_001b: ldarg.0
    IL_001c: ldfld class [mscorlib]System.Collections.Generic.Dictionary`2<int64, class MemoryAddress> TestClass::Memory
    IL_0021: ldarg.0
    IL_0022: ldfld int64 TestClass::Address
    IL_0027: callvirt instance !1 class [mscorlib]System.Collections.Generic.Dictionary`2<int64, class MemoryAddress>::get_Item(!0)
    IL_002c: ldarg.0
    IL_002d: ldfld class Offs TestClass::Offs
    IL_0032: ldfld class Life Offs::Life
    IL_0037: ldfld int64 Life::MaxHp
    IL_003c: callvirt instance !!0 MemoryAddress::Read<int32>(int64)

    IL_0041: ret
} // end of method TestClass::get_MaxHealth

See https://msdn.microsoft.com/en-us/magazine/dn802602.aspx for more information on this and other new features in C# 6.

See this post Difference between Property and Field in C# 3.0+ on the difference between a field and a property getter in C#.

Update:

Note that expression-bodied members were expanded to include properties, constructors, finalizers and indexers in C# 7.0.

Select all child elements recursively in CSS

Use a white space to match all descendants of an element:

div.dropdown * {
    color: red;
}

x y matches every element y that is inside x, however deeply nested it may be - children, grandchildren and so on.

The asterisk * matches any element.

Official Specification: CSS 2.1: Chapter 5.5: Descendant Selectors

Mocking Extension Methods with Moq

I have used a Wrapper to get around this problem. Create a wrapper object and pass your mocked method.

See Mocking Static Methods for Unit Testing by Paul Irwin, it has nice examples.

LINQ - Left Join, Group By, and Count

Consider using a subquery:

from p in context.ParentTable 
let cCount =
(
  from c in context.ChildTable
  where p.ParentId == c.ChildParentId
  select c
).Count()
select new { ParentId = p.Key, Count = cCount } ;

If the query types are connected by an association, this simplifies to:

from p in context.ParentTable 
let cCount = p.Children.Count()
select new { ParentId = p.Key, Count = cCount } ;

iPhone keyboard, Done button and resignFirstResponder

From the documentation (any version):

It is your application’s responsibility to dismiss the keyboard at the time of your choosing. You might dismiss the keyboard in response to a specific user action, such as the user tapping a particular button in your user interface. You might also configure your text field delegate to dismiss the keyboard when the user presses the “return” key on the keyboard itself. To dismiss the keyboard, send the resignFirstResponder message to the text field that is currently the first responder. Doing so causes the text field object to end the current editing session (with the delegate object’s consent) and hide the keyboard.

So, you have to send resignFirstResponder somehow. But there is a possibility that textfield loses focus another way during processing of textFieldShouldReturn: message. This also will cause keyboard to disappear.

How to start http-server locally

To start server locally paste the below code in package.json and run npm start in command line.

"scripts": { "start": "http-server -c-1 -p 8081" },

How to initialize HashSet values by construction?

With the release of and the convenience factory methods this is possible in a cleaner way:

Set set = Set.of("a", "b", "c");

How to calculate mean, median, mode and range from a set of numbers

    public static Set<Double> getMode(double[] data) {
            if (data.length == 0) {
                return new TreeSet<>();
            }
            TreeMap<Double, Integer> map = new TreeMap<>(); //Map Keys are array values and Map Values are how many times each key appears in the array
            for (int index = 0; index != data.length; ++index) {
                double value = data[index];
                if (!map.containsKey(value)) {
                    map.put(value, 1); //first time, put one
                }
                else {
                    map.put(value, map.get(value) + 1); //seen it again increment count
                }
            }
            Set<Double> modes = new TreeSet<>(); //result set of modes, min to max sorted
            int maxCount = 1;
            Iterator<Integer> modeApperance = map.values().iterator();
            while (modeApperance.hasNext()) {
                maxCount = Math.max(maxCount, modeApperance.next()); //go through all the value counts
            }
            for (double key : map.keySet()) {
                if (map.get(key) == maxCount) { //if this key's value is max
                    modes.add(key); //get it
                }
            }
            return modes;
        }

        //std dev function for good measure
        public static double getStandardDeviation(double[] data) {
            final double mean = getMean(data);
            double sum = 0;
            for (int index = 0; index != data.length; ++index) {
                sum += Math.pow(Math.abs(mean - data[index]), 2);
            }
            return Math.sqrt(sum / data.length);
        }


        public static double getMean(double[] data) {
        if (data.length == 0) {
            return 0;
        }
        double sum = 0.0;
        for (int index = 0; index != data.length; ++index) {
            sum += data[index];
        }
        return sum / data.length;
    }

//by creating a copy array and sorting it, this function can take any data.
    public static double getMedian(double[] data) {
        double[] copy = Arrays.copyOf(data, data.length);
        Arrays.sort(copy);
        return (copy.length % 2 != 0) ? copy[copy.length / 2] : (copy[copy.length / 2] + copy[(copy.length / 2) - 1]) / 2;
    }

Is it possible to ping a server from Javascript?

It might be a lot easier than all that. If you want your page to load then check on the availability or content of some foreign page to trigger other web page activity, you could do it using only javascript and php like this.

yourpage.php

<?php
if (isset($_GET['urlget'])){
  if ($_GET['urlget']!=''){
    $foreignpage= file_get_contents('http://www.foreignpage.html');
    // you could also use curl for more fancy internet queries or if http wrappers aren't active in your php.ini
    // parse $foreignpage for data that indicates your page should proceed
    echo $foreignpage; // or a portion of it as you parsed
    exit();  // this is very important  otherwise you'll get the contents of your own page returned back to you on each call
  }
}
?>

<html>
  mypage html content
  ...

<script>
var stopmelater= setInterval("getforeignurl('?urlget=doesntmatter')", 2000);

function getforeignurl(url){
  var handle= browserspec();
  handle.open('GET', url, false);
  handle.send();
  var returnedPageContents= handle.responseText;
  // parse page contents for what your looking and trigger javascript events accordingly.
  // use handle.open('GET', url, true) to allow javascript to continue executing. must provide a callback function to accept the page contents with handle.onreadystatechange()
}
function browserspec(){
  if (window.XMLHttpRequest){
    return new XMLHttpRequest();
  }else{
    return new ActiveXObject("Microsoft.XMLHTTP");
  }
}

</script>

That should do it.

The triggered javascript should include clearInterval(stopmelater)

Let me know if that works for you

Jerry

Is it possible to make desktop GUI application in .NET Core?

I have been searching for this for ages now and none of the solution above are to my satisfaction.

I ended up working with https://github.com/mellinoe/ImGui.NET for now.

I can confirm it works at least across macos and win10 and claims to be compatible with linux.

Leaving this here in case it can help someone.

enter image description here

PHP shell_exec() vs exec()

shell_exec returns all of the output stream as a string. exec returns the last line of the output by default, but can provide all output as an array specifed as the second parameter.

See

The best way to remove duplicate values from NSMutableArray in Objective-C?

One more simple way you can try out which will not add duplicate Value before adding object in array:-

//Assume mutableArray is allocated and initialize and contains some value

if (![yourMutableArray containsObject:someValue])
{
   [yourMutableArray addObject:someValue];
}

What does this symbol mean in JavaScript?

See the documentation on MDN about expressions and operators and statements.

Basic keywords and general expressions

this keyword:

var x = function() vs. function x() — Function declaration syntax

(function(){})() — IIFE (Immediately Invoked Function Expression)

someFunction()() — Functions which return other functions

=> — Equal sign, greater than: arrow function expression syntax

|> — Pipe, greater than: Pipeline operator

function*, yield, yield* — Star after function or yield: generator functions

[], Array() — Square brackets: array notation

If the square brackets appear on the left side of an assignment ([a] = ...), or inside a function's parameters, it's a destructuring assignment.

{key: value} — Curly brackets: object literal syntax (not to be confused with blocks)

If the curly brackets appear on the left side of an assignment ({ a } = ...) or inside a function's parameters, it's a destructuring assignment.

`${}` — Backticks, dollar sign with curly brackets: template literals

// — Slashes: regular expression literals

$ — Dollar sign in regex replace patterns: $$, $&, $`, $', $n

() — Parentheses: grouping operator


Property-related expressions

obj.prop, obj[prop], obj["prop"] — Square brackets or dot: property accessors

?., ?.[], ?.() — Question mark, dot: optional chaining operator

:: — Double colon: bind operator

new operator

...iter — Three dots: spread syntax; rest parameters


Increment and decrement

++, -- — Double plus or minus: pre- / post-increment / -decrement operators


Unary and binary (arithmetic, logical, bitwise) operators

delete operator

void operator

+, - — Plus and minus: addition or concatenation, and subtraction operators; unary sign operators

|, &, ^, ~ — Single pipe, ampersand, circumflex, tilde: bitwise OR, AND, XOR, & NOT operators

% — Percent sign: remainder operator

&&, ||, ! — Double ampersand, double pipe, exclamation point: logical operators

?? — Double question mark: nullish-coalescing operator

** — Double star: power operator (exponentiation)


Equality operators

==, === — Equal signs: equality operators

!=, !== — Exclamation point and equal signs: inequality operators


Bit shift operators

<<, >>, >>> — Two or three angle brackets: bit shift operators


Conditional operator

?:… — Question mark and colon: conditional (ternary) operator


Assignment operators

= — Equal sign: assignment operator

%= — Percent equals: remainder assignment

+= — Plus equals: addition assignment operator

&&=, ||=, ??= — Double ampersand, pipe, or question mark, followed by equal sign: logical assignments

Destructuring


Comma operator

, — Comma operator


Control flow

{} — Curly brackets: blocks (not to be confused with object literal syntax)

Declarations

var, let, const — Declaring variables


Label

label: — Colon: labels


# — Hash (number sign): Private methods or private fields

What is the proper use of an EventEmitter?

There is no: nono and no: yesyes. The truth is in the middle And no reasons to be scared because of the next version of Angular.

From a logical point of view, if You have a Component and You want to inform other components that something happens, an event should be fired and this can be done in whatever way You (developer) think it should be done. I don't see the reason why to not use it and i don't see the reason why to use it at all costs. Also the EventEmitter name suggests to me an event happening. I usually use it for important events happening in the Component. I create the Service but create the Service file inside the Component Folder. So my Service file becomes a sort of Event Manager or an Event Interface, so I can figure out at glance to which event I can subscribe on the current component.

I know..Maybe I'm a bit an old fashioned developer. But this is not a part of Event Driven development pattern, this is part of the software architecture decisions of Your particular project.

Some other guys may think that use Observables directly is cool. In that case go ahead with Observables directly. You're not a serial killer doing this. Unless you're a psychopath developer, So far the Program works, do it.

Creating a ZIP archive in memory using System.IO.Compression

Function to return stream that contain zip file

public static Stream ZipGenerator(List<string> files)
    {
        ZipArchiveEntry fileInArchive;
        Stream entryStream;
        int i = 0;
        List<byte[]> byteArray = new List<byte[]>();

        foreach (var file in files)
        {
            byteArray.Add(File.ReadAllBytes(file));
        }

        var outStream = new MemoryStream();

        using (var archive = new ZipArchive(outStream, ZipArchiveMode.Create, true))
        {
            foreach (var file in files)
            {
                fileInArchive=(archive.CreateEntry(Path.GetFileName(file), CompressionLevel.Optimal));

                using (entryStream = fileInArchive.Open())
                {
                        using (var fileToCompressStream = new MemoryStream(byteArray[i]))
                        {
                            fileToCompressStream.CopyTo(entryStream);
                        }
                        i++;
                }
            }
        }
        outStream.Position = 0;
        return outStream;
    }

If you want , write zip to file stream.

using (var fileStream = new FileStream(@"D:\Tools\DBExtractor\DBExtractor\bin\Debug\test.zip", FileMode.Create))
{
   outStream.Position = 0;
   outStream.WriteTo(fileStream);
}

`

How to use confirm using sweet alert?

document.querySelector('#from1').onsubmit = function(e){

 swal({
    title: "Are you sure?",
    text: "You will not be able to recover this imaginary file!",
    type: "warning",
    showCancelButton: true,
    confirmButtonColor: '#DD6B55',
    confirmButtonText: 'Yes, I am sure!',
    cancelButtonText: "No, cancel it!",
    closeOnConfirm: false,
    closeOnCancel: false
 },
 function(isConfirm){

   if (isConfirm){
     swal("Shortlisted!", "Candidates are successfully shortlisted!", "success");

    } else {
      swal("Cancelled", "Your imaginary file is safe :)", "error");
         e.preventDefault();
    }
 });
};

HTML input file selection event not firing upon selecting the same file

Do whatever you want to do after the file loads successfully.just after the completion of your file processing set the value of file control to blank string.so the .change() will always be called even the file name changes or not. like for example you can do this thing and worked for me like charm

   $('#myFile').change(function () {
       LoadFile("myFile");//function to do processing of file.
       $('#myFile').val('');// set the value to empty of myfile control.
    });

Changing the child element's CSS when the parent is hovered

Use toggleClass().

$('.parent').hover(function(){
$(this).find('.child').toggleClass('color')
});

where color is the class. You can style the class as you like to achieve the behavior you want. The example demonstrates how class is added and removed upon mouse in and out.

Check Working example here.

Moment js get first and last day of current month

moment startOf() and endOf() is the answer you are searching for.. For Example:-

moment().startOf('year');    // set to January 1st, 12:00 am this year
moment().startOf('month');   // set to the first of this month, 12:00 am
moment().startOf('week');    // set to the first day of this week, 12:00 am
moment().startOf('day');     // set to 12:00 am today

Excel: Creating a dropdown using a list in another sheet?

Excel has a very powerful feature providing for a dropdown select list in a cell, reflecting data from a named region. It'a a very easy configuration, once you have done it before. Two steps are to follow:

Create a named region,
Setup the dropdown in a cell.

There is a detailed explanation of the process HERE.

How to count the number of words in a sentence, ignoring numbers, punctuation and whitespace?

import string 

sentence = "I     am having  a   very  nice  23!@$      day. "
# Remove all punctuations
sentence = sentence.translate(str.maketrans('', '', string.punctuation))
# Remove all numbers"
sentence = ''.join([word for word in sentence if not word.isdigit()])
count = 0;
for index in range(len(sentence)-1) :
    if sentence[index+1].isspace() and not sentence[index].isspace():
        count += 1 
print(count)

HashMap(key: String, value: ArrayList) returns an Object instead of ArrayList?

The get method of the HashMap is returning an Object, but the variable current is expected to take a ArrayList:

ArrayList current = new ArrayList();
// ...
current = dictMap.get(dictCode);

For the above code to work, the Object must be cast to an ArrayList:

ArrayList current = new ArrayList();
// ...
current = (ArrayList)dictMap.get(dictCode);

However, probably the better way would be to use generic collection objects in the first place:

HashMap<String, ArrayList<Object>> dictMap =
    new HashMap<String, ArrayList<Object>>();

// Populate the HashMap.

ArrayList<Object> current = new ArrayList<Object>();      
if(dictMap.containsKey(dictCode)) {
    current = dictMap.get(dictCode);   
}

The above code is assuming that the ArrayList has a list of Objects, and that should be changed as necessary.

For more information on generics, The Java Tutorials has a lesson on generics.

Avoid trailing zeroes in printf()

I found problems in some of the solutions posted. I put this together based on answers above. It seems to work for me.

int doubleEquals(double i, double j) {
    return (fabs(i - j) < 0.000001);
}

void printTruncatedDouble(double dd, int max_len) {
    char str[50];
    int match = 0;
    for ( int ii = 0; ii < max_len; ii++ ) {
        if (doubleEquals(dd * pow(10,ii), floor(dd * pow(10,ii)))) {
            sprintf (str,"%f", round(dd*pow(10,ii))/pow(10,ii));
            match = 1;
            break;
        }
    }
    if ( match != 1 ) {
        sprintf (str,"%f", round(dd*pow(10,max_len))/pow(10,max_len));
    }
    char *pp;
    int count;
    pp = strchr (str,'.');
    if (pp != NULL) {
        count = max_len;
        while (count >= 0) {
             count--;
             if (*pp == '\0')
                 break;
             pp++;
        }
        *pp-- = '\0';
        while (*pp == '0')
            *pp-- = '\0';
        if (*pp == '.') {
            *pp = '\0';
        }
    }
    printf ("%s\n", str);
}

int main(int argc, char **argv)
{
    printTruncatedDouble( -1.999, 2 ); // prints -2
    printTruncatedDouble( -1.006, 2 ); // prints -1.01
    printTruncatedDouble( -1.005, 2 ); // prints -1
    printf("\n");
    printTruncatedDouble( 1.005, 2 ); // prints 1 (should be 1.01?)
    printTruncatedDouble( 1.006, 2 ); // prints 1.01
    printTruncatedDouble( 1.999, 2 ); // prints 2
    printf("\n");
    printTruncatedDouble( -1.999, 3 ); // prints -1.999
    printTruncatedDouble( -1.001, 3 ); // prints -1.001
    printTruncatedDouble( -1.0005, 3 ); // prints -1.001 (shound be -1?)
    printTruncatedDouble( -1.0004, 3 ); // prints -1
    printf("\n");
    printTruncatedDouble( 1.0004, 3 ); // prints 1
    printTruncatedDouble( 1.0005, 3 ); // prints 1.001
    printTruncatedDouble( 1.001, 3 ); // prints 1.001
    printTruncatedDouble( 1.999, 3 ); // prints 1.999
    printf("\n");
    exit(0);
}

TypeError: object of type 'int' has no len() error assistance needed

Abstract:

The reason why you are getting this error message is because you are trying to call a method on an int type of a variable. This would work if would have called len() function on a list type of a variable. Let's examin the two cases:

Fail:

num = 10

print(len(num))

The above will produce an error similar to yours due to calling len() function on an int type of a variable;

Success:

data = [0, 4, 8, 9, 12]

print(len(data))

The above will work since you are calling a function on a list type of a variable;

Confusion: @NotNull vs. @Column(nullable = false) with JPA and Hibernate

@NotNull is a JSR 303 Bean Validation annotation. It has nothing to do with database constraints itself. As Hibernate is the reference implementation of JSR 303, however, it intelligently picks up on these constraints and translates them into database constraints for you, so you get two for the price of one. @Column(nullable = false) is the JPA way of declaring a column to be not-null. I.e. the former is intended for validation and the latter for indicating database schema details. You're just getting some extra (and welcome!) help from Hibernate on the validation annotations.

About "*.d.ts" in TypeScript

d stands for Declaration Files:

When a TypeScript script gets compiled there is an option to generate a declaration file (with the extension .d.ts) that functions as an interface to the components in the compiled JavaScript. In the process the compiler strips away all function and method bodies and preserves only the signatures of the types that are exported. The resulting declaration file can then be used to describe the exported virtual TypeScript types of a JavaScript library or module when a third-party developer consumes it from TypeScript.

The concept of declaration files is analogous to the concept of header file found in C/C++.

declare module arithmetics {
    add(left: number, right: number): number;
    subtract(left: number, right: number): number;
    multiply(left: number, right: number): number;
    divide(left: number, right: number): number;
}

Type declaration files can be written by hand for existing JavaScript libraries, as has been done for jQuery and Node.js.

Large collections of declaration files for popular JavaScript libraries are hosted on GitHub in DefinitelyTyped and the Typings Registry. A command-line utility called typings is provided to help search and install declaration files from the repositories.

Add tooltip to font awesome icon

The issue of adding tooltips to any HTML-Output (not only FontAwesome) is an entire book on its own. ;-)

The default way would be to use the title-attribute:

  <div id="welcomeText" title="So nice to see you!">
    <p>Welcome Harriet</p>
  </div>

or

<i class="fa fa-cog" title="Do you like my fa-coq icon?"></i>

But since most people (including me) do not like the standard-tooltips, there are MANY tools out there which will "beautify" them and offer all sort of enhancements. My personal favourites are jBox and qtip2.

What are the differences between type() and isinstance()?

For the real differences, we can find it in code, but I can't find the implement of the default behavior of the isinstance().

However we can get the similar one abc.__instancecheck__ according to __instancecheck__.

From above abc.__instancecheck__, after using test below:

# file tree
# /test/__init__.py
# /test/aaa/__init__.py
# /test/aaa/aa.py
class b():
pass

# /test/aaa/a.py
import sys
sys.path.append('/test')

from aaa.aa import b
from aa import b as c

d = b()

print(b, c, d.__class__)
for i in [b, c, object]:
    print(i, '__subclasses__',  i.__subclasses__())
    print(i, '__mro__', i.__mro__)
    print(i, '__subclasshook__', i.__subclasshook__(d.__class__))
    print(i, '__subclasshook__', i.__subclasshook__(type(d)))
print(isinstance(d, b))
print(isinstance(d, c))

<class 'aaa.aa.b'> <class 'aa.b'> <class 'aaa.aa.b'>
<class 'aaa.aa.b'> __subclasses__ []
<class 'aaa.aa.b'> __mro__ (<class 'aaa.aa.b'>, <class 'object'>)
<class 'aaa.aa.b'> __subclasshook__ NotImplemented
<class 'aaa.aa.b'> __subclasshook__ NotImplemented
<class 'aa.b'> __subclasses__ []
<class 'aa.b'> __mro__ (<class 'aa.b'>, <class 'object'>)
<class 'aa.b'> __subclasshook__ NotImplemented
<class 'aa.b'> __subclasshook__ NotImplemented
<class 'object'> __subclasses__ [..., <class 'aaa.aa.b'>, <class 'aa.b'>]
<class 'object'> __mro__ (<class 'object'>,)
<class 'object'> __subclasshook__ NotImplemented
<class 'object'> __subclasshook__ NotImplemented
True
False

I get this conclusion, For type:

# according to `abc.__instancecheck__`, they are maybe different! I have not found negative one 
type(INSTANCE) ~= INSTANCE.__class__
type(CLASS) ~= CLASS.__class__

For isinstance:

# guess from `abc.__instancecheck__`
return any(c in cls.__mro__ or c in cls.__subclasses__ or cls.__subclasshook__(c) for c in {INSTANCE.__class__, type(INSTANCE)})

BTW: better not to mix use relative and absolutely import, use absolutely import from project_dir( added by sys.path)

Asynchronous method call in Python?

The native Python way for asynchronous calls in 2021 with Python 3.9 suitable also for Jupyter / Ipython Kernel

Camabeh's answer is the way to go since Python 3.3.

async def display_date(loop):
    end_time = loop.time() + 5.0
    while True:
        print(datetime.datetime.now())
        if (loop.time() + 1.0) >= end_time:
            break
        await asyncio.sleep(1)


loop = asyncio.get_event_loop()
# Blocking call which returns when the display_date() coroutine is done
loop.run_until_complete(display_date(loop))
loop.close()

This will work in Jupyter Notebook / Jupyter Lab but throw an error:

RuntimeError: This event loop is already running

Due to Ipython's usage of event loops we need something called nested asynchronous loops which is not yet implemented in Python. Luckily there is nest_asyncio to deal with the issue. All you need to do is:

!pip install nest_asyncio # use ! within Jupyter Notebook, else pip install in shell
import nest_asyncio
nest_asyncio.apply()

(Based on this thread)

Only when you call loop.close() it throws another error as it probably refers to Ipython's main loop.

RuntimeError: Cannot close a running event loop

I'll update this answer as soon as someone answered to this github issue.

Is there a default password to connect to vagrant when using `homestead ssh` for the first time?

This is the default working setup https://www.youtube.com/watch?v=XiD7JTCBdpI

Use Connection Method: standard TCP/IP over ssh

Then ssh hostname: 127.0.0.1:2222

SSH Username: vagrant password vagrant

MySQL Hostname: localhost

Username: homestead password:secret

Difference between a SOAP message and a WSDL?

WSDL act as an interface between sender and receiver.
SOAP message is request and response in xml format.

comparing with java RMI

WSDL is the interface class
SOAP message is marshaled request and response message.

Multiline TextView in Android?

Simplest Way

<TableRow>
    <TextView android:id="@+id/address1"
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content"
        android:gravity="left"
        android:maxLines="4" 
        android:singleLine="false"              
        android:text="Johar Mor,\n Gulistan-e-Johar,\n Karachi" >
    </TextView> 
</TableRow>

Use \n where you want to insert a new line Hopefully it will help you

Kill some processes by .exe file name

Quick Answer:

foreach (var process in Process.GetProcessesByName("whatever"))
{
    process.Kill();
}

(leave off .exe from process name)

How to decode a Base64 string?

Base64 encoding converts three 8-bit bytes (0-255) into four 6-bit bytes (0-63 aka base64). Each of the four bytes indexes an ASCII string which represents the final output as four 8-bit ASCII characters. The indexed string is typically 'A-Za-z0-9+/' with '=' used as padding. This is why encoded data is 4/3 longer.

Base64 decoding is the inverse process. And as one would expect, the decoded data is 3/4 as long.

While base64 encoding can encode plain text, its real benefit is encoding non-printable characters which may be interpreted by transmitting systems as control characters.

I suggest the original poster render $z as bytes with each bit having meaning to the application. Rendering non-printable characters as text typically invokes Unicode which produces glyphs based on your system's localization.

Base64decode("the answer to life the universe and everything") = 00101010

CSS: background-color only inside the margin

If your margin is set on the body, then setting the background color of the html tag should color the margin area

html { background-color: black; }
body { margin:50px; background-color: white; }

http://jsfiddle.net/m3zzb/

Or as dmackerman suggestions, set a margin of 0, but a border of the size you want the margin to be and set the border-color

Using variable in SQL LIKE statement

I had also problem using local variables in LIKE.
Important is to know: how long is variable.
Below, ORDER_NO is 50 characters long, so You can not use: LIKE @ORDER_NO, because in the end will be spaces.
You need to trim right side of the variable first.
Like this:

DECLARE @ORDER_NO char(50)
SELECT @ORDER_NO = 'OR/201910/0012%'

SELECT * FROM orders WHERE ord_no LIKE RTRIM(@ORDER_NO)

Eclipse Generate Javadoc Wizard: what is "Javadoc Command"?

There are already useful answers to this question above, however there is one more possibility which I don't see being addressed here.

We should consider that the java is installed correctly (that's why eclipse could have been launched in the first place), and the JDK is also added correctly to the eclipse. So the issue might be for some reason (e.g. migration of eclipse to another OS) the path for javadoc is not right which you can easily check and modify in the javadoc wizard page. Here is detailed instructions:

  1. Open the javadoc wizard by Project->Generate Javadoc...
  2. In the javadoc wizard window make sure the javadoc command path is correct as illustrated in below screenshot:

EclipseJavadocWizard

Why do I get "Procedure expects parameter '@statement' of type 'ntext/nchar/nvarchar'." when I try to use sp_executesql?

Sounds like you're calling sp_executesql with a VARCHAR statement, when it needs to be NVARCHAR.

e.g. This will give the error because @SQL needs to be NVARCHAR

DECLARE @SQL VARCHAR(100)
SET @SQL = 'SELECT TOP 1 * FROM sys.tables'
EXECUTE sp_executesql @SQL

So:

DECLARE @SQL NVARCHAR(100)
SET @SQL = 'SELECT TOP 1 * FROM sys.tables'
EXECUTE sp_executesql @SQL

Unix epoch time to Java Date object

Better yet, use JodaTime. Much easier to parse strings and into strings. Is thread safe as well. Worth the time it will take you to implement it.

How to Call VBA Function from Excel Cells?

The issue you have encountered is that UDFs cannot modify the Excel environment, they can only return a value to the calling cell.

There are several alternatives

  1. For the sample given you don't actually need VBA. This formula will work
    ='C:\Users\UserName\Desktop\[TestSample.xlsx]Sheet1'!$B$2

  2. Use a rather messy work around: See this answer

  3. You can use ExecuteExcel4Macro or OLEDB

Microsoft.ACE.OLEDB.12.0 is not registered

The easiest fix for me was to change SQL Agent job to run in 32-bit runtime. Go to SQL Job > right click properties > step > edit(step) > Execution option tab > Use 32 bit runtime

screenshot

Determining if an Object is of primitive type

For those who like terse code.

private static final Set<Class> WRAPPER_TYPES = new HashSet(Arrays.asList(
    Boolean.class, Character.class, Byte.class, Short.class, Integer.class, Long.class, Float.class, Double.class, Void.class));
public static boolean isWrapperType(Class clazz) {
    return WRAPPER_TYPES.contains(clazz);
}

How to make a script wait for a pressed key?

Cross Platform, Python 2/3 code:

# import sys, os

def wait_key():
    ''' Wait for a key press on the console and return it. '''
    result = None
    if os.name == 'nt':
        import msvcrt
        result = msvcrt.getch()
    else:
        import termios
        fd = sys.stdin.fileno()

        oldterm = termios.tcgetattr(fd)
        newattr = termios.tcgetattr(fd)
        newattr[3] = newattr[3] & ~termios.ICANON & ~termios.ECHO
        termios.tcsetattr(fd, termios.TCSANOW, newattr)

        try:
            result = sys.stdin.read(1)
        except IOError:
            pass
        finally:
            termios.tcsetattr(fd, termios.TCSAFLUSH, oldterm)

    return result

I removed the fctl/non-blocking stuff because it was giving IOErrors and I didn't need it. I'm using this code specifically because I want it to block. ;)

Addendum:

I implemented this in a package on PyPI with a lot of other goodies called console:

>>> from console.utils import wait_key

>>> wait_key()
'h'

ConnectivityManager getNetworkInfo(int) deprecated

NetManager that you can use to check internet connection on Android with Kotlin

If you use minSdkVersion >= 23

class NetManager @Inject constructor(var applicationContext: Context) {
    val isConnectedToInternet: Boolean?
        get() = with(
            applicationContext.getSystemService(Context.CONNECTIVITY_SERVICE)
                    as ConnectivityManager
        ) {
            isConnectedToInternet()
        }
}

fun ConnectivityManager.isConnectedToInternet() = isConnected(getNetworkCapabilities(activeNetwork))

fun isConnected(networkCapabilities: NetworkCapabilities?): Boolean {
    return when (networkCapabilities) {
        null -> false
        else -> with(networkCapabilities) { hasTransport(TRANSPORT_CELLULAR) || hasTransport(TRANSPORT_WIFI) }
    }
}

If you use minSdkVersion < 23

class NetManager @Inject constructor(var applicationContext: Context) {
    val isConnectedToInternet: Boolean?
        get() = with(
            applicationContext.getSystemService(Context.CONNECTIVITY_SERVICE)
                    as ConnectivityManager
        ) {
            isConnectedToInternet()
        }
}

fun ConnectivityManager.isConnectedToInternet(): Boolean = if (Build.VERSION.SDK_INT < 23) {
    isConnected(activeNetworkInfo)
} else {
    isConnected(getNetworkCapabilities(activeNetwork))
}


fun isConnected(network: NetworkInfo?): Boolean {
    return when (network) {
        null -> false
        else -> with(network) { isConnected && (type == TYPE_WIFI || type == TYPE_MOBILE) }
    }
}

fun isConnected(networkCapabilities: NetworkCapabilities?): Boolean {
    return when (networkCapabilities) {
        null -> false
        else -> with(networkCapabilities) { hasTransport(TRANSPORT_CELLULAR) || hasTransport(TRANSPORT_WIFI) }
    }
}

Best practices for adding .gitignore file for Python projects?

When using buildout I have following in .gitignore (along with *.pyo and *.pyc):

.installed.cfg
bin
develop-eggs
dist
downloads
eggs
parts
src/*.egg-info
lib
lib64

Thanks to Jacob Kaplan-Moss

Also I tend to put .svn in since we use several SCM-s where I work.

How to get UTC time in Python?

Simple, standard library only. Gives timezone-aware datetime, unlike datetime.utcnow().

from datetime import datetime,timezone
now_utc = datetime.now(timezone.utc)

What are the differences between "git commit" and "git push"?

Just want to add the following points:

Yon can not push until you commit as we use git push to push commits made on your local branch to a remote repository.

The git push command takes two arguments:

A remote name, for example, origin A branch name, for example, master

For example:

git push  <REMOTENAME> <BRANCHNAME> 
git push  origin       master

.NET NewtonSoft JSON deserialize map to a different property name

Adding to Jacks solution. I need to Deserialize using the JsonProperty and Serialize while ignoring the JsonProperty (or vice versa). ReflectionHelper and Attribute Helper are just helper classes that get a list of properties or attributes for a property. I can include if anyone actually cares. Using the example below you can serialize the viewmodel and get "Amount" even though the JsonProperty is "RecurringPrice".

    /// <summary>
    /// Ignore the Json Property attribute. This is usefule when you want to serialize or deserialize differently and not 
    /// let the JsonProperty control everything.
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public class IgnoreJsonPropertyResolver<T> : DefaultContractResolver
    {
        private Dictionary<string, string> PropertyMappings { get; set; }

        public IgnoreJsonPropertyResolver()
        {
            this.PropertyMappings = new Dictionary<string, string>();
            var properties = ReflectionHelper<T>.GetGetProperties(false)();
            foreach (var propertyInfo in properties)
            {
                var jsonProperty = AttributeHelper.GetAttribute<JsonPropertyAttribute>(propertyInfo);
                if (jsonProperty != null)
                {
                    PropertyMappings.Add(jsonProperty.PropertyName, propertyInfo.Name);
                }
            }
        }

        protected override string ResolvePropertyName(string propertyName)
        {
            string resolvedName = null;
            var resolved = this.PropertyMappings.TryGetValue(propertyName, out resolvedName);
            return (resolved) ? resolvedName : base.ResolvePropertyName(propertyName);
        }
    }

Usage:

        var settings = new JsonSerializerSettings();
        settings.DateFormatString = "YYYY-MM-DD";
        settings.ContractResolver = new IgnoreJsonPropertyResolver<PlanViewModel>();
        var model = new PlanViewModel() {Amount = 100};
        var strModel = JsonConvert.SerializeObject(model,settings);

Model:

public class PlanViewModel
{

    /// <summary>
    ///     The customer is charged an amount over an interval for the subscription.
    /// </summary>
    [JsonProperty(PropertyName = "RecurringPrice")]
    public double Amount { get; set; }

    /// <summary>
    ///     Indicates the number of intervals between each billing. If interval=2, the customer would be billed every two
    ///     months or years depending on the value for interval_unit.
    /// </summary>
    public int Interval { get; set; } = 1;

    /// <summary>
    ///     Number of free trial days that can be granted when a customer is subscribed to this plan.
    /// </summary>
    public int TrialPeriod { get; set; } = 30;

    /// <summary>
    /// This indicates a one-time fee charged upfront while creating a subscription for this plan.
    /// </summary>
    [JsonProperty(PropertyName = "SetupFee")]
    public double SetupAmount { get; set; } = 0;


    /// <summary>
    /// String representing the type id, usually a lookup value, for the record.
    /// </summary>
    [JsonProperty(PropertyName = "TypeId")]
    public string Type { get; set; }

    /// <summary>
    /// Billing Frequency
    /// </summary>
    [JsonProperty(PropertyName = "BillingFrequency")]
    public string Period { get; set; }


    /// <summary>
    /// String representing the type id, usually a lookup value, for the record.
    /// </summary>
    [JsonProperty(PropertyName = "PlanUseType")]
    public string Purpose { get; set; }
}

Are there any log file about Windows Services Status?

Under Windows 7, open the Event Viewer. You can do this the way Gishu suggested for XP, typing eventvwr from the command line, or by opening the Control Panel, selecting System and Security, then Administrative Tools and finally Event Viewer. It may require UAC approval or an admin password.

In the left pane, expand Windows Logs and then System. You can filter the logs with Filter Current Log... from the Actions pane on the right and selecting "Service Control Manager." Or, depending on why you want this information, you might just need to look through the Error entries.

enter image description here

The actual log entry pane (not shown) is pretty user-friendly and self-explanatory. You'll be looking for messages like the following:

"The Praxco Assistant service entered the stopped state."
"The Windows Image Acquisition (WIA) service entered the running state."
"The MySQL service terminated unexpectedly. It has done this 3 time(s)."

rotating axis labels in R

First, create the data for the chart

H <- c(1.964138757, 1.729143013,    1.713273714,    1.706771799,    1.67977205)
M <- c("SP105", "SP30", "SP244", "SP31",    "SP147")

Second, give the name for a chart file

png(file = "Bargraph.jpeg", width = 500, height = 300)

Third, Plot the bar chart

barplot(H,names.arg=M,ylab="Degree ", col= rainbow(5), las=2, border = 0, cex.lab=1, cex.axis=1, font=1,col.axis="black")
title(xlab="Service Providers", line=4, cex.lab=1)

Finally, save the file

dev.off()

Output:

enter image description here

Scheduling Python Script to run every hour accurately

One option is to write a C/C++ wrapper that executes the python script on a regular basis. Your end-user would run the C/C++ executable, which would remain running in the background, and periodically execute the python script. This may not be the best solution, and may not work if you don't know C/C++ or want to keep this 100% python. But it does seem like the most user-friendly approach, since people are used to clicking on executables. All of this assumes that python is installed on your end user's computer.

Another option is to use cron job/Task Scheduler but to put it in the installer as a script so your end user doesn't have to do it.

passing several arguments to FUN of lapply (and others *apply)

You can do it in the following way:

 myfxn <- function(var1,var2,var3){
      var1*var2*var3

    }

    lapply(1:3,myfxn,var2=2,var3=100)

and you will get the answer:

[[1]] [1] 200

[[2]] [1] 400

[[3]] [1] 600

Jquery assiging class to th in a table

You had thead in your selector, but there is no thead in your table. Also you had your selectors backwards. As you mentioned above, you wanted to be adding the tr class to the th, not vice-versa (although your comment seems to contradict what you wrote up above).

$('tr th').each(function(index){     if($('tr td').eq(index).attr('class') != ''){         // get the class of the td         var tdClass = $('tr td').eq(index).attr('class');         // add it to this th         $(this).addClass(tdClass );     } }); 

Fiddle

Thread pooling in C++11

Edit: This now requires C++17 and concepts. (As of 9/12/16, only g++ 6.0+ is sufficient.)

The template deduction is a lot more accurate because of it, though, so it's worth the effort of getting a newer compiler. I've not yet found a function that requires explicit template arguments.

It also now takes any appropriate callable object (and is still statically typesafe!!!).

It also now includes an optional green threading priority thread pool using the same API. This class is POSIX only, though. It uses the ucontext_t API for userspace task switching.


I created a simple library for this. An example of usage is given below. (I'm answering this because it was one of the things I found before I decided it was necessary to write it myself.)

bool is_prime(int n){
  // Determine if n is prime.
}

int main(){
  thread_pool pool(8); // 8 threads

  list<future<bool>> results;
  for(int n = 2;n < 10000;n++){
    // Submit a job to the pool.
    results.emplace_back(pool.async(is_prime, n));
  }

  int n = 2;
  for(auto i = results.begin();i != results.end();i++, n++){
    // i is an iterator pointing to a future representing the result of is_prime(n)
    cout << n << " ";
    bool prime = i->get(); // Wait for the task is_prime(n) to finish and get the result.
    if(prime)
      cout << "is prime";
    else
      cout << "is not prime";
    cout << endl;
  }  
}

You can pass async any function with any (or void) return value and any (or no) arguments and it will return a corresponding std::future. To get the result (or just wait until a task has completed) you call get() on the future.

Here's the github: https://github.com/Tyler-Hardin/thread_pool.

Get child node index

I had issue with text nodes, and it was showing wrong index. Here is version to fix it.

function getChildNodeIndex(elem)
{   
    let position = 0;
    while ((elem = elem.previousSibling) != null)
    {
        if(elem.nodeType != Node.TEXT_NODE)
            position++;
    }

    return position;
}

How can I display my windows user name in excel spread sheet using macros?

Range("A1").value = Environ("Username")

This is better than Application.Username, which doesn't always supply the Windows username. Thanks to Kyle for pointing this out.

  • Application Username is the name of the User set in Excel > Tools > Options
  • Environ("Username") is the name you registered for Windows; see Control Panel >System

how to call a method in another Activity from Activity

public class ActivityB extends AppCompatActivity {

static Context mContext;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_b);

    try {

        Bundle bundle = getIntent().getExtras();
        if (bundle != null) {
            String texto = bundle.getString("message");
            if (texto != null) {
              //code....
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static void launch(String message) {
        Intent intent = new Intent(mContext, ActivityB.class);
        intent.putExtra("message", message);
        mContext.startActivity(intent);
    }
}

In ActivityA or Service.

public class Service extends Service{

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {    

        String text = "Value to send";
        ActivityB.launch(text);
        Log.d(TAG, text);
    }
}

C# Lambda expressions: Why should I use them?

This is just one way of using a lambda expression. You can use a lambda expression anywhere you can use a delegate. This allows you to do things like this:

List<string> strings = new List<string>();
strings.Add("Good");
strings.Add("Morning")
strings.Add("Starshine");
strings.Add("The");
strings.Add("Earth");
strings.Add("says");
strings.Add("hello");

strings.Find(s => s == "hello");

This code will search the list for an entry that matches the word "hello". The other way to do this is to actually pass a delegate to the Find method, like this:

List<string> strings = new List<string>();
strings.Add("Good");
strings.Add("Morning")
strings.Add("Starshine");
strings.Add("The");
strings.Add("Earth");
strings.Add("says");
strings.Add("hello");

private static bool FindHello(String s)
{
    return s == "hello";
}

strings.Find(FindHello);

EDIT:

In C# 2.0, this could be done using the anonymous delegate syntax:

  strings.Find(delegate(String s) { return s == "hello"; });

Lambda's significantly cleaned up that syntax.

How to remove all duplicate items from a list

This should be faster and will preserve the original order:

seen = {}
new_list = [seen.setdefault(x, x) for x in my_list if x not in seen]

If you don't care about order, you can just:

new_list = list(set(my_list))

When to use an interface instead of an abstract class and vice versa?

I think the most succinct way of putting it is the following:

Shared properties => abstract class.
Shared functionality => interface.

And to put it less succinctly...

Abstract Class Example:

public abstract class BaseAnimal
{
    public int NumberOfLegs { get; set; }

    protected BaseAnimal(int numberOfLegs)
    {
        NumberOfLegs = numberOfLegs;
    }
}

public class Dog : BaseAnimal
{
    public Dog() : base(4) { }
}

public class Human : BaseAnimal 
{
    public Human() : base(2) { }
}

Since animals have a shared property - number of legs in this case - it makes sense to make an abstract class containing this shared property. This also allows us to write common code that operates on that property. For example:

public static int CountAllLegs(List<BaseAnimal> animals)
{
    int legCount = 0;
    foreach (BaseAnimal animal in animals)
    {
        legCount += animal.NumberOfLegs;
    }
    return legCount;
}

Interface Example:

public interface IMakeSound
{
    void MakeSound();
}

public class Car : IMakeSound
{
    public void MakeSound() => Console.WriteLine("Vroom!");
}

public class Vuvuzela : IMakeSound
{
    public void MakeSound() => Console.WriteLine("VZZZZZZZZZZZZZ!");        
}

Note here that Vuvuzelas and Cars are completely different things, but they have shared functionality: making a sound. Thus, an interface makes sense here. Further, it will allow programmers to group things that make sounds together under a common interface -- IMakeSound in this case. With this design, you could write the following code:

List<IMakeSound> soundMakers = new List<ImakeSound>();
soundMakers.Add(new Car());
soundMakers.Add(new Vuvuzela());
soundMakers.Add(new Car());
soundMakers.Add(new Vuvuzela());
soundMakers.Add(new Vuvuzela());

foreach (IMakeSound soundMaker in soundMakers)
{
    soundMaker.MakeSound();
}

Can you tell what that would output?

Lastly, you can combine the two.

Combined Example:

public interface IMakeSound
{
    void MakeSound();
}

public abstract class BaseAnimal : IMakeSound
{
    public int NumberOfLegs { get; set; }

    protected BaseAnimal(int numberOfLegs)
    {
        NumberOfLegs = numberOfLegs;
    }

    public abstract void MakeSound();
}

public class Cat : BaseAnimal
{
    public Cat() : base(4) { }

    public override void MakeSound() => Console.WriteLine("Meow!");
}

public class Human : BaseAnimal 
{
    public Human() : base(2) { }

    public override void MakeSound() => Console.WriteLine("Hello, world!");
}

Here, we're requiring all BaseAnimals make a sound, but we don't know its implementation yet. In such a case, we can abstract the interface implementation and delegate its implementation to its subclasses.

One last point, remember how in the abstract class example we were able to operate on the shared properties of different objects and in the interface example we were able to invoke the shared functionality of different objects? In this last example, we could do both.

.NET DateTime to SqlDateTime Conversion

var sqlCommand = new SqlCommand("SELECT * FROM mytable WHERE start_time >= @StartTime");
sqlCommand.Parameters.Add("@StartTime", SqlDbType.DateTime);
sqlCommand.Parameters("@StartTime").Value = MyDateObj;

SQL Server: What is the difference between CROSS JOIN and FULL OUTER JOIN?

For SQL Server, CROSS JOIN and FULL OUTER JOIN are different. CROSS JOIN is simply Cartesian Product of two tables, irrespective of any filter criteria or any condition.

FULL OUTER JOIN gives unique result set of LEFT OUTER JOIN and RIGHT OUTER JOIN of two tables. It also needs ON clause to map two columns of tables.

Table 1 contains 10 rows and Table 2 contains 20 rows with 5 rows matching on specific columns.

Then CROSS JOIN will return 10*20=200 rows in result set.

FULL OUTER JOIN will return 25 rows in result set.

FULL OUTER JOIN (or any other JOIN) always returns result set with less than or equal to Cartesian Product number.

Number of rows returned by FULL OUTER JOIN equal to (No. of Rows by LEFT OUTER JOIN) + (No. of Rows by RIGHT OUTER JOIN) - (No. of Rows by INNER JOIN).

Python int to binary string?

Here's a simple binary to decimal converter that continuously loops

t = 1
while t > 0:
    binaryNumber = input("Enter a binary No.")
    convertedNumber = int(binaryNumber, 2)

    print(convertedNumber)

print("")

writing to serial port from linux command line

echo '\x12\x02'

will not be interpreted, and will literally write the string \x12\x02 (and append a newline) to the specified serial port. Instead use

echo -n ^R^B

which you can construct on the command line by typing CtrlVCtrlR and CtrlVCtrlB. Or it is easier to use an editor to type into a script file.

The stty command should work, unless another program is interfering. A common culprit is gpsd which looks for GPS devices being plugged in.

MySQL - Cannot add or update a child row: a foreign key constraint fails

Hope this will assist anyone having the same error while importing CSV data into related tables. In my case the parent table was OK, but I got the error while importing data to the child table containing the foreign key. After temporarily removing the foregn key constraint on the child table, I managed to import the data and was suprised to find some of the values in the FK column having values of 0 (obviously this had been causing the error since the parent table did not have such values in its PK column). The cause was that, the data in my CSV column preceeding the FK column contained commas (which I was using as a field delimeter). Changing the delimeter for my CSV file solved the problem.

Tool to convert java to c# code

Microsoft has a tool called JLCA: Java Language Conversion Assistant. I can't tell if it is better though, as I have never compared the two.

Measuring text height to be drawn on Canvas ( Android )

You must use Rect.width() and Rect.Height() which returned from getTextBounds() instead. That works for me.

How to disable Hyper-V in command line?

You can have a Windows 10 configuration with and without Hyper-V as follows in an Admin prompt:

bcdedit /copy {current} /d "Windows 10 no Hyper-V"

find the new id of the just created "Windows 10 no Hyper-V" bootentry, eg. {094a0b01-3350-11e7-99e1-bc5ec82bc470}

bcdedit /set {094a0b01-3350-11e7-99e1-bc5ec82bc470} hypervisorlaunchtype Off

After rebooting you can choose between Windows 10 with and without Hyper-V at startup

Output to the same line overwriting previous output?

I found that for a simple print statement in python 2.7, just put a comma at the end after your '\r'.

print os.path.getsize(file_name)/1024, 'KB / ', size, 'KB downloaded!\r',

This is shorter than other non-python 3 solutions, but also more difficult to maintain.

How can I add a class to a DOM element in JavaScript?

Use the .classList.add() method:

_x000D_
_x000D_
const element = document.querySelector('div.foo');_x000D_
element.classList.add('bar');_x000D_
console.log(element.className);
_x000D_
<div class="foo"></div>
_x000D_
_x000D_
_x000D_

This method is better than overwriting the className property, because it doesn't remove other classes and doesn't add the class if the element already has it.

You can also toggle or remove classes using element.classList (see the MDN documentation).

How to split a large text file into smaller files with equal number of lines?

In case you just want to split by x number of lines each file, the given answers about split are OK. But, i am curious about no one paid attention to requirements:

  • "without having to count them" -> using wc + cut
  • "having the remainder in extra file" -> split does by default

I can't do that without "wc + cut", but I'm using that:

split -l  $(expr `wc $filename | cut -d ' ' -f3` / $chunks) $filename

This can be easily added to your bashrc functions so you can just invoke it passing filename and chunks:

 split -l  $(expr `wc $1 | cut -d ' ' -f3` / $2) $1

In case you want just x chunks without remainder in extra file, just adapt the formula to sum it (chunks - 1) on each file. I do use this approach because usually i just want x number of files rather than x lines per file:

split -l  $(expr `wc $1 | cut -d ' ' -f3` / $2 + `expr $2 - 1`) $1

You can add that to a script and call it your "ninja way", because if nothing suites your needs, you can build it :-)

ValueError: all the input arrays must have same number of dimensions

(n,) and (n,1) are not the same shape. Try casting the vector to an array by using the [:, None] notation:

n_lists = np.append(n_list_converted, n_last[:, None], axis=1)

Alternatively, when extracting n_last you can use

n_last = n_list_converted[:, -1:]

to get a (20, 1) array.

How can get the text of a div tag using only javascript (no jQuery)

Because textContent is not supported in IE8 and older, here is a workaround:

var node = document.getElementById('test'),
var text  = node.textContent || node.innerText;
alert(text);

innerText does work in IE.

How to secure database passwords in PHP?

Store them in a file outside web root.

PostgreSQL: How to make "case-insensitive" query

Use LOWER function to convert the strings to lower case before comparing.

Try this:

SELECT id 
  FROM groups
 WHERE LOWER(name)=LOWER('Administrator')