Programs & Examples On #Universal binary

How to include another XHTML in XHTML using JSF 2.0 Facelets?

Included page:

<!-- opening and closing tags of included page -->
<ui:composition ...>
</ui:composition>

Including page:

<!--the inclusion line in the including page with the content-->
<ui:include src="yourFile.xhtml"/>
  • You start your included xhtml file with ui:composition as shown above.
  • You include that file with ui:include in the including xhtml file as also shown above.

Convert XmlDocument to String

There aren't any quotes. It's just VS debugger. Try printing to the console or saving to a file and you'll see. As a side note: always dispose disposable objects:

using (var stringWriter = new StringWriter())
using (var xmlTextWriter = XmlWriter.Create(stringWriter))
{
    xmlDoc.WriteTo(xmlTextWriter);
    xmlTextWriter.Flush();
    return stringWriter.GetStringBuilder().ToString();
}

Get array of object's keys

In case you're here looking for something to list the keys of an n-depth nested object as a flat array:

_x000D_
_x000D_
const getObjectKeys = (obj, prefix = '') => {_x000D_
  return Object.entries(obj).reduce((collector, [key, val]) => {_x000D_
    const newKeys = [ ...collector, prefix ? `${prefix}.${key}` : key ]_x000D_
    if (Object.prototype.toString.call(val) === '[object Object]') {_x000D_
      const newPrefix = prefix ? `${prefix}.${key}` : key_x000D_
      const otherKeys = getObjectKeys(val, newPrefix)_x000D_
      return [ ...newKeys, ...otherKeys ]_x000D_
    }_x000D_
    return newKeys_x000D_
  }, [])_x000D_
}_x000D_
_x000D_
console.log(getObjectKeys({a: 1, b: 2, c: { d: 3, e: { f: 4 }}}))
_x000D_
_x000D_
_x000D_

Creating a new dictionary in Python

>>> dict(a=2,b=4)
{'a': 2, 'b': 4}

Will add the value in the python dictionary.

Modify XML existing content in C#

Forming a XML file

XmlTextWriter xmlw = new XmlTextWriter(@"C:\WINDOWS\Temp\exm.xml",System.Text.Encoding.UTF8);
xmlw.WriteStartDocument();            
xmlw.WriteStartElement("examtimes");
xmlw.WriteStartElement("Starttime");
xmlw.WriteString(DateTime.Now.AddHours(0).ToString());
xmlw.WriteEndElement();
xmlw.WriteStartElement("Changetime");
xmlw.WriteString(DateTime.Now.AddHours(0).ToString());
xmlw.WriteEndElement();
xmlw.WriteStartElement("Endtime");
xmlw.WriteString(DateTime.Now.AddHours(1).ToString());
xmlw.WriteEndElement();
xmlw.WriteEndElement();
xmlw.WriteEndDocument();  
xmlw.Close();           

To edit the Xml nodes use the below code

XmlDocument doc = new XmlDocument(); 
doc.Load(@"C:\WINDOWS\Temp\exm.xml"); 
XmlNode root = doc.DocumentElement["Starttime"]; 
root.FirstChild.InnerText = "First"; 
XmlNode root1 = doc.DocumentElement["Changetime"]; 
root1.FirstChild.InnerText = "Second"; 
doc.Save(@"C:\WINDOWS\Temp\exm.xml"); 

Try this. It's C# code.

RecyclerView: Inconsistency detected. Invalid item position

This exception raised on API 19, 21 (but not new). In Kotlin coroutine I loaded data (in background thread) and in UI thread added and showed them:

adapter.addItem(item)

Adapter:

var list: MutableList<Item> = mutableListOf()

init {
    this.setHasStableIds(true)
}

open fun addItem(item: Item) {
    list.add(item)
    notifyItemInserted(list.lastIndex)
}

For some reason Android doesn't render quick enough or something else, so, I update a list in post method of the RecyclerView (add, remove, update events of items):

view.recycler_view.post { adapter.addItem(item) }

This exception is similar to "Cannot call this method in a scroll callback. Scroll callbacks mightbe run during a measure & layout pass where you cannot change theRecyclerView data. Any method call that might change the structureof the RecyclerView or the adapter contents should be postponed tothe next frame.": Recyclerview - cannot call this method in a scroll callback.

Str_replace for multiple items

In my use case, I parameterized some fields in an HTML document, and once I load these fields I match and replace them using the str_replace method.

<?php echo str_replace(array("{{client_name}}", "{{client_testing}}"), array('client_company_name', 'test'), 'html_document'); ?>

C/C++ line number

Use __LINE__, but what is its type?

LINE The presumed line number (within the current source file) of the current source line (an integer constant).

As an integer constant, code can often assume the value is __LINE__ <= INT_MAX and so the type is int.

To print in C, printf() needs the matching specifier: "%d". This is a far lesser concern in C++ with cout.

Pedantic concern: If the line number exceeds INT_MAX1 (somewhat conceivable with 16-bit int), hopefully the compiler will produce a warning. Example:

format '%d' expects argument of type 'int', but argument 2 has type 'long int' [-Wformat=]

Alternatively, code could force wider types to forestall such warnings.

printf("Not logical value at line number %ld\n", (long) __LINE__);
//or
#include <stdint.h>
printf("Not logical value at line number %jd\n", INTMAX_C(__LINE__));

Avoid printf()

To avoid all integer limitations: stringify. Code could directly print without a printf() call: a nice thing to avoid in error handling2 .

#define xstr(a) str(a)
#define str(a) #a

fprintf(stderr, "Not logical value at line number %s\n", xstr(__LINE__));
fputs("Not logical value at line number " xstr(__LINE__) "\n", stderr);

1 Certainly poor programming practice to have such a large file, yet perhaps machine generated code may go high.

2 In debugging, sometimes code simply is not working as hoped. Calling complex functions like *printf() can itself incur issues vs. a simple fputs().

Fastest JSON reader/writer for C++

rapidjson is a C++ JSON parser/generator designed to be fast and small memory footprint.

There is a performance comparison with YAJL and JsonCPP.


Update:

I created an open source project Native JSON benchmark, which evaluates 29 (and increasing) C/C++ JSON libraries, in terms of conformance and performance. This should be an useful reference.

Recommended way to insert elements into map

To quote:

Because map containers do not allow for duplicate key values, the insertion operation checks for each element inserted whether another element exists already in the container with the same key value, if so, the element is not inserted and its mapped value is not changed in any way.

So insert will not change the value if the key already exists, the [] operator will.

EDIT:

This reminds me of another recent question - why use at() instead of the [] operator to retrieve values from a vector. Apparently at() throws an exception if the index is out of bounds whereas [] operator doesn't. In these situations it's always best to look up the documentation of the functions as they will give you all the details. But in general, there aren't (or at least shouldn't be) two functions/operators that do the exact same thing.

My guess is that, internally, insert() will first check for the entry and afterwards itself use the [] operator.

How do I use an INSERT statement's OUTPUT clause to get the identity value?

You can either have the newly inserted ID being output to the SSMS console like this:

INSERT INTO MyTable(Name, Address, PhoneNo)
OUTPUT INSERTED.ID
VALUES ('Yatrix', '1234 Address Stuff', '1112223333')

You can use this also from e.g. C#, when you need to get the ID back to your calling app - just execute the SQL query with .ExecuteScalar() (instead of .ExecuteNonQuery()) to read the resulting ID back.

Or if you need to capture the newly inserted ID inside T-SQL (e.g. for later further processing), you need to create a table variable:

DECLARE @OutputTbl TABLE (ID INT)

INSERT INTO MyTable(Name, Address, PhoneNo)
OUTPUT INSERTED.ID INTO @OutputTbl(ID)
VALUES ('Yatrix', '1234 Address Stuff', '1112223333')

This way, you can put multiple values into @OutputTbl and do further processing on those. You could also use a "regular" temporary table (#temp) or even a "real" persistent table as your "output target" here.

Passing data to a bootstrap modal

This is how you can send the id_data to a modal :

<input
    href="#"
    data-some-id="uid0123456789"
    data-toggle="modal"
    data-target="#my_modal"
    value="SHOW MODAL"
    type="submit"
    class="btn modal-btn"/>

<div class="col-md-5">
  <div class="modal fade" id="my_modal">
   <div class="modal-body modal-content">
     <h2 name="hiddenValue" id="hiddenValue" />
   </div>
   <div class="modal-footer" />
</div>

And the javascript :

    $(function () {
     $(".modal-btn").click(function (){
       var data_var = $(this).data('some-id');
       $(".modal-body h2").text(data_var);
     })
    });

Version of Apache installed on a Debian machine

I think you have to be sure what type of installation you have binary or source. To check what binary packages is installed: with root rights execute following command:

dpkg -l |grep apache2

result should be something like:

dpkg -l |grep apache2
ii  apache2                               2.4.10-10+deb8u8                      amd64        Apache HTTP Server
ii  apache2-bin                           2.4.10-10+deb8u8                      amd64        Apache HTTP Server (modules and other binary files)
ii  apache2-data                          2.4.10-10+deb8u8                      all          Apache HTTP Server (common files)
ii  apache2-doc                           2.4.10-10+deb8u8                      all          Apache HTTP Server (on-site documentation)

To find version you can run :

apache2ctl -V |grep -i "Server version"

result should be something like: Server version: Apache/2.4.10 (Debian)

Using Transactions or SaveChanges(false) and AcceptAllChanges()?

With the Entity Framework most of the time SaveChanges() is sufficient. This creates a transaction, or enlists in any ambient transaction, and does all the necessary work in that transaction.

Sometimes though the SaveChanges(false) + AcceptAllChanges() pairing is useful.

The most useful place for this is in situations where you want to do a distributed transaction across two different Contexts.

I.e. something like this (bad):

using (TransactionScope scope = new TransactionScope())
{
    //Do something with context1
    //Do something with context2

    //Save and discard changes
    context1.SaveChanges();

    //Save and discard changes
    context2.SaveChanges();

    //if we get here things are looking good.
    scope.Complete();
}

If context1.SaveChanges() succeeds but context2.SaveChanges() fails the whole distributed transaction is aborted. But unfortunately the Entity Framework has already discarded the changes on context1, so you can't replay or effectively log the failure.

But if you change your code to look like this:

using (TransactionScope scope = new TransactionScope())
{
    //Do something with context1
    //Do something with context2

    //Save Changes but don't discard yet
    context1.SaveChanges(false);

    //Save Changes but don't discard yet
    context2.SaveChanges(false);

    //if we get here things are looking good.
    scope.Complete();
    context1.AcceptAllChanges();
    context2.AcceptAllChanges();

}

While the call to SaveChanges(false) sends the necessary commands to the database, the context itself is not changed, so you can do it again if necessary, or you can interrogate the ObjectStateManager if you want.

This means if the transaction actually throws an exception you can compensate, by either re-trying or logging state of each contexts ObjectStateManager somewhere.

See my blog post for more.

AngularJS - How to use $routeParams in generating the templateUrl?

//module dependent on ngRoute  
 var app=angular.module("myApp",['ngRoute']);
    //spa-Route Config file
    app.config(function($routeProvider,$locationProvider){
          $locationProvider.hashPrefix('');
          $routeProvider
            .when('/',{template:'HOME'})
            .when('/about/:paramOne/:paramTwo',{template:'ABOUT',controller:'aboutCtrl'})
            .otherwise({template:'Not Found'});
    }
   //aboutUs controller 
    app.controller('aboutCtrl',function($routeParams){
          $scope.paramOnePrint=$routeParams.paramOne;
          $scope.paramTwoPrint=$routeParams.paramTwo;
    });

in index.html

<a ng-href="#/about/firstParam/secondParam">About</a>

firstParam and secondParam can be anything according to your needs.

How to check if all inputs are not empty with jQuery

Just use:

$("input:empty").length == 0;

If it's zero, none are empty.

To be a bit smarter though and also filter out items with just spaces in, you could do:

$("input").filter(function () {
    return $.trim($(this).val()).length == 0
}).length == 0;

Maven Installation OSX Error Unsupported major.minor version 51.0

The problem is because you haven't set JAVA_HOME in Mac properly. In order to do that, you should do set it like this:

export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_40.jdk/Contents/Home

In my case my JDK installation is jdk1.8.0_40, make sure you type yours.

Then you can use maven commands.

Regards!

Remove multiple objects with rm()

Another variation you can try is(expanding @mnel's answer) if you have many temp'x'.

here "n" could be the number of temp variables present

rm(list = c(paste("temp",c(1:n),sep="")))

No resource found that matches the given name '@style/ Theme.Holo.Light.DarkActionBar'

If you use android studio, this might be useful for you.

I had a similar problem and i solved it by changing the skd path from the default C:\Program Files (x86)\Android\android-studio\sdk to C:\Program Files (x86)\Android\android-sdk .

It seems the problem came from the compiler version (gradle sets it automatically to the highest one available in the sdk folder) which doesn't support this theme, and since android studio had only the api 7 in its sdk folder, it gave me this error.

For more information on how to change Android sdk path in Android Studio: Android Studio - How to Change Android SDK Path

ngModel cannot be used to register form controls with a parent formGroup directive

OK, finally got it working: see https://github.com/angular/angular/pull/10314#issuecomment-242218563

In brief, you can no longer use name attribute within a formGroup, and must use formControlName instead

Download a working local copy of a webpage

wget is capable of doing what you are asking. Just try the following:

wget -p -k http://www.example.com/

The -p will get you all the required elements to view the site correctly (css, images, etc). The -k will change all links (to include those for CSS & images) to allow you to view the page offline as it appeared online.

From the Wget docs:

‘-k’
‘--convert-links’
After the download is complete, convert the links in the document to make them
suitable for local viewing. This affects not only the visible hyperlinks, but
any part of the document that links to external content, such as embedded images,
links to style sheets, hyperlinks to non-html content, etc.

Each link will be changed in one of the two ways:

    The links to files that have been downloaded by Wget will be changed to refer
    to the file they point to as a relative link.

    Example: if the downloaded file /foo/doc.html links to /bar/img.gif, also
    downloaded, then the link in doc.html will be modified to point to
    ‘../bar/img.gif’. This kind of transformation works reliably for arbitrary
    combinations of directories.

    The links to files that have not been downloaded by Wget will be changed to
    include host name and absolute path of the location they point to.

    Example: if the downloaded file /foo/doc.html links to /bar/img.gif (or to
    ../bar/img.gif), then the link in doc.html will be modified to point to
    http://hostname/bar/img.gif. 

Because of this, local browsing works reliably: if a linked file was downloaded,
the link will refer to its local name; if it was not downloaded, the link will
refer to its full Internet address rather than presenting a broken link. The fact
that the former links are converted to relative links ensures that you can move
the downloaded hierarchy to another directory.

Note that only at the end of the download can Wget know which links have been
downloaded. Because of that, the work done by ‘-k’ will be performed at the end
of all the downloads. 

How to add a local repo and treat it as a remote repo

I am posting this answer to provide a script with explanations that covers three different scenarios of creating a local repo that has a local remote. You can run the entire script and it will create the test repos in your home folder (tested on windows git bash). The explanations are inside the script for easier saving to your personal notes, its very readable from, e.g. Visual Studio Code.

I would also like to thank Jack for linking to this answer where adelphus has good, detailed, hands on explanations on the topic.

This is my first post here so please advise what should be improved.

## SETUP LOCAL GIT REPO WITH A LOCAL REMOTE
# the main elements:
# - remote repo must be initialized with --bare parameter
# - local repo must be initialized
# - local repo must have at least one commit that properly initializes a branch(root of the commit tree)
# - local repo needs to have a remote
# - local repo branch must have an upstream branch on the remote

{ # the brackets are optional, they allow to copy paste into terminal and run entire thing without interruptions, run without them to see which cmd outputs what

cd ~
rm -rf ~/test_git_local_repo/

## Option A - clean slate - you have nothing yet

mkdir -p ~/test_git_local_repo/option_a ; cd ~/test_git_local_repo/option_a
git init --bare local_remote.git # first setup the local remote
git clone local_remote.git local_repo # creates a local repo in dir local_repo
cd ~/test_git_local_repo/option_a/local_repo
git remote -v show origin # see that git clone has configured the tracking
touch README.md ; git add . ; git commit -m "initial commit on master" # properly init master
git push origin master # now have a fully functional setup, -u not needed, git clone does this for you

# check all is set-up correctly
git pull # check you can pull
git branch -avv # see local branches and their respective remote upstream branches with the initial commit
git remote -v show origin # see all branches are set to pull and push to remote
git log --oneline --graph --decorate --all # see all commits and branches tips point to the same commits for both local and remote

## Option B - you already have a local git repo and you want to connect it to a local remote

mkdir -p ~/test_git_local_repo/option_b ; cd ~/test_git_local_repo/option_b
git init --bare local_remote.git # first setup the local remote

# simulate a pre-existing git local repo you want to connect with the local remote
mkdir local_repo ; cd local_repo
git init # if not yet a git repo
touch README.md ; git add . ; git commit -m "initial commit on master" # properly init master
git checkout -b develop ; touch fileB ; git add . ; git commit -m "add fileB on develop" # create develop and fake change

# connect with local remote
cd ~/test_git_local_repo/option_b/local_repo
git remote add origin ~/test_git_local_repo/option_b/local_remote.git
git remote -v show origin # at this point you can see that there is no the tracking configured (unlike with git clone), so you need to push with -u
git push -u origin master # -u to set upstream
git push -u origin develop # -u to set upstream; need to run this for every other branch you already have in the project

# check all is set-up correctly
git pull # check you can pull
git branch -avv # see local branch(es) and its remote upstream with the initial commit
git remote -v show origin # see all remote branches are set to pull and push to remote
git log --oneline --graph --decorate --all # see all commits and branches tips point to the same commits for both local and remote

## Option C - you already have a directory with some files and you want it to be a git repo with a local remote

mkdir -p ~/test_git_local_repo/option_c ; cd ~/test_git_local_repo/option_c
git init --bare local_remote.git # first setup the local remote

# simulate a pre-existing directory with some files
mkdir local_repo ; cd local_repo ; touch README.md fileB

# make a pre-existing directory a git repo and connect it with local remote
cd ~/test_git_local_repo/option_c/local_repo
git init
git add . ; git commit -m "inital commit on master" # properly init master
git remote add origin ~/test_git_local_repo/option_c/local_remote.git
git remote -v show origin # see there is no the tracking configured (unlike with git clone), so you need to push with -u
git push -u origin master # -u to set upstream

# check all is set-up correctly
git pull # check you can pull
git branch -avv # see local branch and its remote upstream with the initial commit
git remote -v show origin # see all remote branches are set to pull and push to remote
git log --oneline --graph --decorate --all # see all commits and branches tips point to the same commits for both local and remote
}

Node: log in a file instead of the console

I just build a pack to do this, hope you like it ;) https://www.npmjs.com/package/writelog

A failure occurred while executing com.android.build.gradle.internal.tasks

I already had multidex enabled but the version was too old so upgraded and it fixed the issue:

// Old version
implementation 'com.android.support:multidex:1.0.3'
// New version
def multidex_version = "2.0.1"
implementation 'androidx.multidex:multidex:$multidex_version'

SELECT INTO a table variable in T-SQL

The purpose of SELECT INTO is (per the docs, my emphasis)

To create a new table from values in another table

But you already have a target table! So what you want is

The INSERT statement adds one or more new rows to a table

You can specify the data values in the following ways:

...

By using a SELECT subquery to specify the data values for one or more rows, such as:

  INSERT INTO MyTable 
 (PriKey, Description)
        SELECT ForeignKey, Description
        FROM SomeView

And in this syntax, it's allowed for MyTable to be a table variable.

Resolve promises one after another (i.e. in sequence)?

First, you need to understand that a promise is executed at the time of creation.
So for example if you have a code:

["a","b","c"].map(x => returnsPromise(x))

You need to change it to:

["a","b","c"].map(x => () => returnsPromise(x))

Then we need to sequentially chain promises:

["a", "b", "c"].map(x => () => returnsPromise(x))
    .reduce(
        (before, after) => before.then(_ => after()),
        Promise.resolve()
    )

executing after(), will make sure that promise is created (and executed) only when its time comes.

Symfony2 : How to get form validation errors after binding the request to the form

You have two possible ways of doing it:

  • do not redirect user upon error and display {{ form_errors(form) }} within template file
  • access error array as $form->getErrors()

How can I determine the current CPU utilization from the shell?

You can use top or ps commands to check the CPU usage.

using top : This will show you the cpu stats

top -b -n 1 |grep ^Cpu

using ps: This will show you the % cpu usage for each process.

ps -eo pcpu,pid,user,args | sort -r -k1 | less

Also, you can write a small script in bash or perl to read /proc/stat and calculate the CPU usage.

setting content between div tags using javascript

If the number of your messages is limited then the following may help. I used jQuery for the following example, but it works with plain js too.

The innerHtml property did not work for me. So I experimented with ...

    <div id=successAndErrorMessages-1>100% OK</div>
    <div id=successAndErrorMessages-2>This is an error mssg!</div>

and toggled one of the two on/off ...

 $("#successAndErrorMessages-1").css('display', 'none')
 $("#successAndErrorMessages-2").css('display', '')

For some reason I had to fiddle around with the ordering before it worked in all types of browsers.

Multithreading in Bash

Sure, just add & after the command:

read_cfg cfgA &
read_cfg cfgB &
read_cfg cfgC &
wait

all those jobs will then run in the background simultaneously. The optional wait command will then wait for all the jobs to finish.

Each command will run in a separate process, so it's technically not "multithreading", but I believe it solves your problem.

How to initialize a List<T> to a given size (as opposed to capacity)?

string [] temp = new string[] {"1","2","3"};
List<string> temp2 = temp.ToList();

Google Chrome: This setting is enforced by your administrator

(MacOS) I got this issue after getting some malware that was forcing me to use WeKnow as a search engine. To fix this on MacOs I followed these steps

  1. Go to System Preferences, then check if there's an icon named Profiles.

  2. Remove AdminPrefs profile

  3. Change default search engine settings, Restart Chrome

The above partially helped (I still had WeKnow as my home page). After that I followed these steps:

  1. Type chrome://policy/ to see the policies. You cannot change them there

  2. Copy paste this into your terminal

defaults write com.google.Chrome HomepageIsNewTabPage -bool false

defaults write com.google.Chrome NewTabPageLocation -string "https://www.google.com/"

defaults write com.google.Chrome HomepageLocation -string "https://www.google.com/"

defaults delete com.google.Chrome DefaultSearchProviderSearchURL

defaults delete com.google.Chrome DefaultSearchProviderNewTabURL

defaults delete com.google.Chrome DefaultSearchProviderName

I've also ran a scan of my system with Avast antivirus that has detected some malware

How to change the interval time on bootstrap carousel?

You can also use the data-interval attribute eg. <div class="carousel" data-interval="10000">

How to "properly" create a custom object in JavaScript?

To continue off of bobince's answer

In es6 you can now actually create a class

So now you can do:

class Shape {
    constructor(x, y) {
        this.x = x;
        this.y = y;
    }

    toString() {
        return `Shape at ${this.x}, ${this.y}`;
    }
}

So extend to a circle (as in the other answer) you can do:

class Circle extends Shape {
    constructor(x, y, r) {
        super(x, y);
        this.r = r;
    }

    toString() {
        let shapeString = super.toString();
        return `Circular ${shapeString} with radius ${this.r}`;
    }
}

Ends up a bit cleaner in es6 and a little easier to read.


Here is a good example of it in action:

_x000D_
_x000D_
class Shape {_x000D_
  constructor(x, y) {_x000D_
    this.x = x;_x000D_
    this.y = y;_x000D_
  }_x000D_
_x000D_
  toString() {_x000D_
    return `Shape at ${this.x}, ${this.y}`;_x000D_
  }_x000D_
}_x000D_
_x000D_
class Circle extends Shape {_x000D_
  constructor(x, y, r) {_x000D_
    super(x, y);_x000D_
    this.r = r;_x000D_
  }_x000D_
_x000D_
  toString() {_x000D_
    let shapeString = super.toString();_x000D_
    return `Circular ${shapeString} with radius ${this.r}`;_x000D_
  }_x000D_
}_x000D_
_x000D_
let c = new Circle(1, 2, 4);_x000D_
_x000D_
console.log('' + c, c);
_x000D_
_x000D_
_x000D_

How to create/make rounded corner buttons in WPF?

Although this question is long-since answered, I used an alternative approach that people might find simpler than any of these solutions (even Keith Stein's excellent answer). So I'm posting it in case it might help anyone.

You can achieve rounded corners on a button without having to write any XAML (other than a Style, once) and without having to replace the template or set/change any other properties. Just use an EventSetter in your style for the button's "Loaded" event and change it in code-behind.

(And if your style lives in a separate Resource Dictionary XAML file, then you can put the event code in a code-behind file for your resource dictionary.)

I do it like this:

Xaml Style:

<Style x:Key="ButtonStyle" TargetType="{x:Type Button}" BasedOn="{StaticResource {x:Type Button}}">
    <EventSetter Event="Loaded"                   Handler="ButtonLoaded"/>
</Style>

Code-Behind:

public partial class ButtonStyles
{
    private void ButtonLoaded(object sender, RoutedEventArgs e)
    {
        if (!(sender is Button b))
            return;

        // Find the first top-level border we can.

        Border border = default;
        for (var i = 0; null == border && i < VisualTreeHelper.GetChildrenCount(b); ++i)
            border = VisualTreeHelper.GetChild(b, i) as Border;

        // If we found it, set its corner radius how we want.  

        if (border != null)
            border.CornerRadius = new CornerRadius(3);
    }
}

If you had to add the code-behind file to an existing resource dictionary xaml file, you can even have the code-behind file automatically appear underneath that XAML file in the Visual Studio Solution if you want. In a .NET Core project, just give it appropriate corresponding name (e.g if the resource Dictionary is "MyDictionary.xaml", name the code-behind file "MyDictionary.xaml.cs"). In a .NET Framework project, you need to edit the .csproj file in XML mode

What is the difference between max-device-width and max-width for mobile web?

max-device-width is the device rendering width

@media all and (max-device-width: 400px) {
    /* styles for devices with a maximum width of 400px and less
       Changes only on device orientation */
}

@media all and (max-width: 400px) {
    /* styles for target area with a maximum width of 400px and less
       Changes on device orientation , browser resize */
}

The max-width is the width of the target display area means the current size of browser.

How to solve "sign_and_send_pubkey: signing failed: agent refused operation"?

What worked here : on the client

1) ssh-add

2) ssh-copy-id user@server

The keys has been created some time ago with plain "ssh-keygen -t rsa" I sw the error message because I copied across my ssh public key from client to server (with ssh-id-copy) without running ssh-add first, since I erroneously assumed I'd added them some time earlier.

Remove a string from the beginning of a string

<?php
$str = 'bla_string_bla_bla_bla';
echo preg_replace('/bla_/', '', $str, 1); 
?>

Hiding and Showing TabPages in tabControl

A different approach would be to have two tab controls, one visible, and one not. You can move the tabs from one to the other like this (vb.net):

If Me.chkShowTab1.Checked = True Then
    Me.tabsShown.TabPages.Add(Me.tabsHidden.TabPages("Tab1"))
    Me.tabsHidden.TabPages.RemoveByKey("Tab1")
Else
    Me.tabsHidden.TabPages.Add(Me.tabsShown.TabPages("Tab1"))
    Me.tabsShown.TabPages.RemoveByKey("Tab1")
End If

If the tab order is important, change the .Add method on tabsShown to .Insert and specify the ordinal position. One way to do that is to call a routine that returns the desired ordinal position.

Where to place and how to read configuration resource files in servlet based application?

You can you with your source folder so whenever you build, those files are automatically copied to the classes directory.

Instead of using properties file, use XML file.

If the data is too small, you can even use web.xml for accessing the properties.

Please note that any of these approach will require app server restart for changes to be reflected.

How do you get the footer to stay at the bottom of a Web page?

I wasn't having any luck with the solutions suggested on this page before but then finally, this little trick worked. I'll include it as another possible solution.

footer {
  position: fixed;
  right: 0;
  bottom: 0;
  left: 0;
  padding: 1rem;
  background-color: #efefef;
  text-align: center;
}

auto refresh for every 5 mins

Refresh document every 300 seconds using HTML Meta tag add this inside the head tag of the page

 <meta http-equiv="refresh" content="300">

Using Script:

            setInterval(function() {
                  window.location.reload();
                }, 300000); 

update columns values with column of another table based on condition

Something like this should do it :

UPDATE table1 
   SET table1.Price = table2.price 
   FROM table1  INNER JOIN  table2 ON table1.id = table2.id

You can also try this:

UPDATE table1 
   SET price=(SELECT price FROM table2 WHERE table1.id=table2.id);

How can I see which Git branches are tracking which remote / upstream branch?

git for-each-ref --format='%(refname:short) <- %(upstream:short)' refs/heads

will show a line for each local branch. A tracking branch will look like:

master <- origin/master

A non-tracking one will look like:

test <- 

Android studio Error "Unsupported Modules Detected: Compilation is not supported for following modules"

  1. save .idea folder somewhere else (for backup)
  2. remove .idea folder
  3. start AndroidStudio
  4. select project
  5. [there may be an error, ignore that]
  6. click File -> Invalidate Caches/ Restart
  7. click button: Invalidate Caches/ Restart
  8. resolved

How do I import other TypeScript files?

If you're using AMD modules, the other answers won't work in TypeScript 1.0 (the newest at the time of writing.)

You have different approaches available to you, depending upon how many things you wish to export from each .ts file.

Multiple exports

Foo.ts

export class Foo {}
export interface IFoo {}

Bar.ts

import fooModule = require("Foo");

var foo1 = new fooModule.Foo();
var foo2: fooModule.IFoo = {};

Single export

Foo.ts

class Foo
{}

export = Foo;

Bar.ts

import Foo = require("Foo");

var foo = new Foo();

Eclipse: How do you change the highlight color of the currently selected method/expression?

If you're using eclipse with PHP package and want to change highlighted colour then there is slight difference to above answer.

  1. Right click on highlighted word
  2. Select 'Preferences'
  3. Go to General > Editors > Text Editors > Annotations. Now look for "PHP elements 'read' occurrences" and "PHP elements 'write' occurrences". You can select your desired colour there.

Change Highlighted text colour in Eclips with PHP

Exporting data In SQL Server as INSERT INTO

If you are running SQL Server 2008 R2 the built in options on to do this in SSMS as marc_s described above changed a bit. Instead of selecting Script data = true as shown in his diagram, there is now a new option called "Types of data to script" just above the "Table/View Options" grouping. Here you can select to script data only, schema and data or schema only. Works like a charm.

c++ bool question

Yes that is correct. "Boolean variables only have two possible values: true (1) and false (0)." cpp tutorial on boolean values

What is content-type and datatype in an AJAX request?

contentType is the type of data you're sending, so application/json; charset=utf-8 is a common one, as is application/x-www-form-urlencoded; charset=UTF-8, which is the default.

dataType is what you're expecting back from the server: json, html, text, etc. jQuery will use this to figure out how to populate the success function's parameter.

If you're posting something like:

{"name":"John Doe"}

and expecting back:

{"success":true}

Then you should have:

var data = {"name":"John Doe"}
$.ajax({
    dataType : "json",
    contentType: "application/json; charset=utf-8",
    data : JSON.stringify(data),
    success : function(result) {
        alert(result.success); // result is an object which is created from the returned JSON
    },
});

If you're expecting the following:

<div>SUCCESS!!!</div>

Then you should do:

var data = {"name":"John Doe"}
$.ajax({
    dataType : "html",
    contentType: "application/json; charset=utf-8",
    data : JSON.stringify(data),
    success : function(result) {
        jQuery("#someContainer").html(result); // result is the HTML text
    },
});

One more - if you want to post:

name=John&age=34

Then don't stringify the data, and do:

var data = {"name":"John", "age": 34}
$.ajax({
    dataType : "html",
    contentType: "application/x-www-form-urlencoded; charset=UTF-8", // this is the default value, so it's optional
    data : data,
    success : function(result) {
        jQuery("#someContainer").html(result); // result is the HTML text
    },
});

Addressing localhost from a VirtualBox virtual machine

I had to go into virtualbox and change my network settings to 'NAT'. After that, I was able to hit localhost running on my host machine from my emulator on virtualbox through http://10.0.2.2:3000

How to make a checkbox checked with jQuery?

You don't need to control your checkBoxes with jQuery. You can do it with some simple JavaScript.

This JS snippet should work fine:

document.TheFormHere.test.Value = true;

How to check if a date is in a given range?

Converting them to timestamps is the way to go alright, using strtotime, e.g.

$start_date = '2009-06-17';

$end_date = '2009-09-05';

$date_from_user = '2009-08-28';

check_in_range($start_date, $end_date, $date_from_user);


function check_in_range($start_date, $end_date, $date_from_user)
{
  // Convert to timestamp
  $start_ts = strtotime($start_date);
  $end_ts = strtotime($end_date);
  $user_ts = strtotime($date_from_user);

  // Check that user date is between start & end
  return (($user_ts >= $start_ts) && ($user_ts <= $end_ts));
}

Java count occurrence of each item in an array

This is a simple script I used in Python but it can be easily adapted. Nothing fancy though.

def occurance(arr):
  results = []
  for n in arr:
      data = {}
      data["point"] = n
      data["count"] = 0
      for i in range(0, len(arr)):
          if n == arr[i]:
              data["count"] += 1
      results.append(data)
  return results

Pythonically add header to a csv file

You just add one additional row before you execute the loop. This row contains your CSV file header name.

schema = ['a','b','c','b']
row = 4
generators = ['A','B','C','D']
with open('test.csv','wb') as csvfile:    
     writer = csv.writer(csvfile, delimiter=delimiter)
# Gives the header name row into csv
     writer.writerow([g for g in schema])   
#Data add in csv file       
     for x in xrange(rows):
         writer.writerow([g() for g in generators])

iOS9 Untrusted Enterprise Developer with no option to trust

For iOS 9 beta 3,4 users. Since the option to view profiles is not viewable do the following from Xcode.

  1. Open Xcode 7.
  2. Go to window, devices.
  3. Select your device.
  4. Delete all of the profiles loaded on the device.
  5. Delete the old app on your device.
  6. Clean and rebuild the app to your device.

On iOS 9.1+ n iOS 9.2+ go to Settings -> General -> Device Management -> press the Profile -> Press Trust.

How do I change the background color of a plot made with ggplot2

To change the panel's background color, use the following code:

myplot + theme(panel.background = element_rect(fill = 'green', colour = 'red'))

To change the color of the plot (but not the color of the panel), you can do:

myplot + theme(plot.background = element_rect(fill = 'green', colour = 'red'))

See here for more theme details Quick reference sheet for legends, axes and themes.

Error: " 'dict' object has no attribute 'iteritems' "

I had a similar problem (using 3.5) and lost 1/2 a day to it but here is a something that works - I am retired and just learning Python so I can help my grandson (12) with it.

mydict2={'Atlanta':78,'Macon':85,'Savannah':72}
maxval=(max(mydict2.values()))
print(maxval)
mykey=[key for key,value in mydict2.items()if value==maxval][0]
print(mykey)
YEILDS; 
85
Macon

How to force a script reload and re-execute?

Here's a method which is similar to Kelly's but will remove any pre-existing script with the same source, and uses jQuery.

<script>
    function reload_js(src) {
        $('script[src="' + src + '"]').remove();
        $('<script>').attr('src', src).appendTo('head');
    }
    reload_js('source_file.js');
</script>

Note that the 'type' attribute is no longer needed for scripts as of HTML5. (http://www.w3.org/html/wg/drafts/html/master/scripting-1.html#the-script-element)

How do I conditionally add attributes to React components?

juandemarco's answer is usually correct, but here is another option.

Build an object how you like:

var inputProps = {
  value: 'foo',
  onChange: this.handleChange
};

if (condition)
  inputProps.disabled = true;

Render with spread, optionally passing other props also.

<input
    value="this is overridden by inputProps"
    {...inputProps}
    onChange={overridesInputProps}
 />

Reading a string with scanf

I think that this below is accurate and it may help. Feel free to correct it if you find any errors. I'm new at C.

char str[]  
  1. array of values of type char, with its own address in memory
  2. array of values of type char, with its own address in memory as many consecutive addresses as elements in the array
  3. including termination null character '\0' &str, &str[0] and str, all three represent the same location in memory which is address of the first element of the array str

    char *strPtr = &str[0]; //declaration and initialization

alternatively, you can split this in two:

char *strPtr; strPtr = &str[0];
  1. strPtr is a pointer to a char
  2. strPtr points at array str
  3. strPtr is a variable with its own address in memory
  4. strPtr is a variable that stores value of address &str[0]
  5. strPtr own address in memory is different from the memory address that it stores (address of array in memory a.k.a &str[0])
  6. &strPtr represents the address of strPtr itself

I think that you could declare a pointer to a pointer as:

char **vPtr = &strPtr;  

declares and initializes with address of strPtr pointer

Alternatively you could split in two:

char **vPtr;
*vPtr = &strPtr
  1. *vPtr points at strPtr pointer
  2. *vPtr is a variable with its own address in memory
  3. *vPtr is a variable that stores value of address &strPtr
  4. final comment: you can not do str++, str address is a const, but you can do strPtr++

What is FCM token in Firebase?

I have an update about "Firebase Cloud Messaging token" which I could get an information.

I really wanted to know about that change so just sent a mail to Support team. The Firebase Cloud Messaging token will get back to Server key soon again. There will be nothing to change. We can see Server key again after soon.

Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[]]

Just go to the project Properties->Project Facets

  1. Uncheck the dynamic module, click apply.

  2. Maven->update the project.

How to print a single backslash?

do you like it

print(fr"\{''}")

or how about this

print(r"\ "[0])

getting the screen density programmatically in android?

This should help on your activity ...

void printSecreenInfo(){

    Display display = getWindowManager().getDefaultDisplay();
    DisplayMetrics metrics = new DisplayMetrics();
    display.getMetrics(metrics);

    Log.i(TAG, "density :" +  metrics.density);

    // density interms of dpi
    Log.i(TAG, "D density :" +  metrics.densityDpi);

    // horizontal pixel resolution
    Log.i(TAG, "width pix :" +  metrics.widthPixels);

     // actual horizontal dpi
    Log.i(TAG, "xdpi :" +  metrics.xdpi);

    // actual vertical dpi
    Log.i(TAG, "ydpi :" +  metrics.ydpi);

}

OUTPUT :

I/test( 1044): density :1.0

I/test( 1044): D density :160

I/test( 1044): width pix :800

I/test( 1044): xdpi :160.0

I/test( 1044): ydpi :160.42105

Store output of sed into a variable

Use command substitution like this:

line=$(sed -n '2p' myfile)
echo "$line"

Also note that there is no space around the = sign.

How to remove element from an array in JavaScript?

shift() is ideal for your situation. shift() removes the first element from an array and returns that element. This method changes the length of the array.

array = [1, 2, 3, 4, 5];

array.shift(); // 1

array // [2, 3, 4, 5]

how to loop through rows columns in excel VBA Macro

Here is my sugestion:

Dim i As integer, j as integer

With Worksheets("TimeOut")
    i = 26
    Do Until .Cells(8, i).Value = ""
        For j = 9 to 100 ' I do not know how many rows you will need it.'
            .Cells(j, i).Formula = "YourVolFormulaHere"
            .Cells(j, i + 1).Formula = "YourCapFormulaHere"
        Next j

        i = i + 2
    Loop
 End With

Counting repeated characters in a string in Python

Below code worked for me without looking for any other Python libraries.

def count_repeated_letter(string1):
    list1=[]

    for letter in string1:
        if string1.count(letter)>=2:
            if letter not in list1:
                list1.append(letter)


    for item in list1:
        if item!= " ":
            print(item,string1.count(item))


count_repeated_letter('letter has 1 e and 2 e and 1 t and two t')

Output:

e 4
t 5
a 4
1 2
n 3
d 3

Command copy exited with code 4 when building - Visual Studio restart solves it

I had the same issue. It was caused by having the same flag twice, for example:

if $(ConfigurationName) == Release (xcopy "$(TargetDir)." "$(SolutionDir)Deployment\$(ProjectName)\" /e /d /i /y /e)

Observe that the "/e" flag appears twice. Removing the duplicate solved the issue.

How to use Checkbox inside Select Option

Alternate Vanilla JS version with click outside to hide checkboxes:

let expanded = false;
const multiSelect = document.querySelector('.multiselect');

multiSelect.addEventListener('click', function(e) {
  const checkboxes = document.getElementById("checkboxes");
    if (!expanded) {
    checkboxes.style.display = "block";
    expanded = true;
  } else {
    checkboxes.style.display = "none";
    expanded = false;
  }
  e.stopPropagation();
}, true)

document.addEventListener('click', function(e){
  if (expanded) {
    checkboxes.style.display = "none";
    expanded = false;
  }
}, false)

I'm using addEventListener instead of onClick in order to take advantage of the capture/bubbling phase options along with stopPropagation(). You can read more about the capture/bubbling here: https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener

The rest of the code matches vitfo's original answer (but no need for onclick() in the html). A couple of people have requested this functionality sans jQuery.

Here's codepen example https://codepen.io/davidysoards/pen/QXYYYa?editors=1010

Check if value already exists within list of dictionaries?

Here's one way to do it:

if not any(d['main_color'] == 'red' for d in a):
    # does not exist

The part in parentheses is a generator expression that returns True for each dictionary that has the key-value pair you are looking for, otherwise False.


If the key could also be missing the above code can give you a KeyError. You can fix this by using get and providing a default value. If you don't provide a default value, None is returned.

if not any(d.get('main_color', default_value) == 'red' for d in a):
    # does not exist

Boolean operators ( &&, -a, ||, -o ) in Bash

Rule of thumb: Use -a and -o inside square brackets, && and || outside.

It's important to understand the difference between shell syntax and the syntax of the [ command.

  • && and || are shell operators. They are used to combine the results of two commands. Because they are shell syntax, they have special syntactical significance and cannot be used as arguments to commands.

  • [ is not special syntax. It's actually a command with the name [, also known as test. Since [ is just a regular command, it uses -a and -o for its and and or operators. It can't use && and || because those are shell syntax that commands don't get to see.

But wait! Bash has a fancier test syntax in the form of [[ ]]. If you use double square brackets, you get access to things like regexes and wildcards. You can also use shell operators like &&, ||, <, and > freely inside the brackets because, unlike [, the double bracketed form is special shell syntax. Bash parses [[ itself so you can write things like [[ $foo == 5 && $bar == 6 ]].

onclick or inline script isn't working in extension

As already mentioned, Chrome Extensions don't allow to have inline JavaScript due to security reasons so you can try this workaround as well.

HTML file

<!doctype html>
    <html>
        <head>
            <title>
                Getting Started Extension's Popup
            </title>
            <script src="popup.js"></script>
        </head>
        <body>
            <div id="text-holder">ha</div><br />
            <a class="clickableBtn">
                  hyhy
            </a>
        </body>
    </html>
<!doctype html>

popup.js

window.onclick = function(event) {
    var target = event.target ;
    if(target.matches('.clickableBtn')) {
        var clickedEle = document.activeElement.id ;
        var ele = document.getElementById(clickedEle);
        alert(ele.text);
    }
}

Or if you are having a Jquery file included then

window.onclick = function(event) {
    var target = event.target ;
    if(target.matches('.clickableBtn')) {
        alert($(target).text());
    }
}

Can I remove the URL from my print css, so the web address doesn't print?

Now we can do this with:

<style type="text/css" media="print">
@page {
    size: auto;   /* auto is the initial value */
    margin: 0;  /* this affects the margin in the printer settings */
}
</style>

Source: https://stackoverflow.com/a/14975912/1760939

Close a div by clicking outside

This question might have been answered here. There might be some potential issues when event propagation is interrupted, as explained by Philip Walton in this post.

A better approach/solution would be to create a custom jQuery event, e.g. clickoutside. Ben Alman has a great post (here) that explains how to implement one (and also explains how special events work), and he's got a nice implementation of it (here).

More reading on jQuery events API and jQuery special events:

Best way to overlay an ESRI shapefile on google maps?

Free "Export to KML" script for ArcGIS 9

Here is a list of available methods that someone found.

Also, it seems to me that the most efficient representation of a polygon layer is by using Google Maps API's polyline encoding, which significantly compresses lat-lng data. But getting into that format takes work: use ArcMap to export Shape as lat/lng coordinates, then convert into polylines using Google Maps API.

What does cmd /C mean?

The part you should be interested in is the /? part, which should solve most other questions you have with the tool.

Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

C:\>cmd /?
Starts a new instance of the Windows XP command interpreter

CMD [/A | /U] [/Q] [/D] [/E:ON | /E:OFF] [/F:ON | /F:OFF] [/V:ON | /V:OFF]
    [[/S] [/C | /K] string]

/C      Carries out the command specified by string and then terminates
/K      Carries out the command specified by string but remains
/S      Modifies the treatment of string after /C or /K (see below)
/Q      Turns echo off
/D      Disable execution of AutoRun commands from registry (see below)
/A      Causes the output of internal commands to a pipe or file to be ANSI
/U      Causes the output of internal commands to a pipe or file to be
        Unicode
/T:fg   Sets the foreground/background colors (see COLOR /? for more info)
/E:ON   Enable command extensions (see below)
/E:OFF  Disable command extensions (see below)
/F:ON   Enable file and directory name completion characters (see below)
/F:OFF  Disable file and directory name completion characters (see below)
/V:ON   Enable delayed environment variable expansion using ! as the
        delimiter. For example, /V:ON would allow !var! to expand the
        variable var at execution time.  The var syntax expands variables
        at input time, which is quite a different thing when inside of a FOR
        loop.
/V:OFF  Disable delayed environment expansion.

Disabling swap files creation in vim

If you are using git, you can add *.swp to .gitignore.

Selecting the first "n" items with jQuery

Use lt pseudo selector:

$("a:lt(n)")

This matches the elements before the nth one (the nth element excluded). Numbering starts from 0.

How to split the filename from a full path in batch?

I don't know that much about batch files but couldn't you have a pre-made batch file copied from the home directory to the path you have that would return a list of the names of the files then use that name?

Here is a link I think might be helpful in making the pre-made batch file.

http://www.ericphelps.com/batch/lists/filelist.htm

2D character array initialization in C

char **options[2][100];

declares a size-2 array of size-100 arrays of pointers to pointers to char. You'll want to remove one *. You'll also want to put your string literals in double quotes.

Differences between unique_ptr and shared_ptr

unique_ptr is the light-weight smart pointer of choice if you just have a dynamic object somewhere for which one consumer has sole (hence "unique") responsibility -- maybe a wrapper class that needs to maintain some dynamically allocated object. unique_ptr has very little overhead. It is not copyable, but movable. Its type is template <typename D, typename Deleter> class unique_ptr;, so it depends on two template parameters.

unique_ptr is also what auto_ptr wanted to be in the old C++ but couldn't because of that language's limitations.

shared_ptr on the other hand is a very different animal. The obvious difference is that you can have many consumers sharing responsibility for a dynamic object (hence "shared"), and the object will only be destroyed when all shared pointers have gone away. Additionally you can have observing weak pointers which will intelligently be informed if the shared pointer they're following has disappeared.

Internally, shared_ptr has a lot more going on: There is a reference count, which is updated atomically to allow the use in concurrent code. Also, there's plenty of allocation going on, one for an internal bookkeeping "reference control block", and another (often) for the actual member object.

But there's another big difference: The shared pointers type is always template <typename T> class shared_ptr;, and this is despite the fact that you can initialize it with custom deleters and with custom allocators. The deleter and allocator are tracked using type erasure and virtual function dispatch, which adds to the internal weight of the class, but has the enormous advantage that different sorts of shared pointers of type T are all compatible, no matter the deletion and allocation details. Thus they truly express the concept of "shared responsibility for T" without burdening the consumer with the details!

Both shared_ptr and unique_ptr are designed to be passed by value (with the obvious movability requirement for the unique pointer). Neither should make you worried about the overhead, since their power is truly astounding, but if you have a choice, prefer unique_ptr, and only use shared_ptr if you really need shared responsibility.

find: missing argument to -exec

Just in case anyone sees a similar "missing -exec args" in Amazon Opsworks Chef bash scripts, I needed to add another backslash to escape the \;

bash 'remove_wars' do
  user 'ubuntu'
  cwd '/'
  code <<-EOH
    find /home/ubuntu/wars -type f -name "*.war" -exec rm {} \\;
  EOH
  ignore_failure true
end

Observable.of is not a function

I had this problem today. I'm using systemjs to load the dependencies.

I was loading the Rxjs like this:

...
    paths: {
        "rxjs/*": "node_modules/rxjs/bundles/Rx.umd.min.js"
    },
...

Instead of use paths use this:

var map = {
...
'rxjs':                       'node_modules/rxjs',
...
}

var packages = {
...
'rxjs': { main: 'bundles/Rx.umd.min.js', defaultExtension: 'js' }
...
}

This little change in the way systemjs loads the library fixed my problem.

How do I change column default value in PostgreSQL?

If you want to remove the default value constraint, you can do:

ALTER TABLE <table> ALTER COLUMN <column> DROP DEFAULT;

Abort a Git Merge

as long as you did not commit you can type

git merge --abort

just as the command line suggested.

What does <> mean?

could be a shorthand for React.Fragment

How should I store GUID in MySQL tables?

Binary(16) would be fine, better than use of varchar(32).

Cannot bulk load because the file could not be opened. Operating System Error Code 3

I dont know if you solved this issue, but i had same issue, if the instance is local you must check the permission to access the file, but if you are accessing from your computer to a server (remote access) you have to specify the path in the server, so that means to include the file in a server directory, that solved my case

example:

BULK INSERT Table
FROM 'C:\bulk\usuarios_prueba.csv' -- This is server path not local
WITH 
  (
     FIELDTERMINATOR =',',
     ROWTERMINATOR ='\n'
  );

How to hide html source & disable right click and text copy?

You potentially can not prevent user from viewing the HTML source content. The site that you have listed prevents user from right click. but fact is you can still do CTRL + U in Firefox to view source!

How to show full column content in a Spark Dataframe?

Within Databricks you can visualize the dataframe in a tabular format. With the command:

display(results)

It will look like

enter image description here

Creating random numbers with no duplicates

There is another way of doing "random" ordered numbers with LFSR, take a look at:

http://en.wikipedia.org/wiki/Linear_feedback_shift_register

with this technique you can achieve the ordered random number by index and making sure the values are not duplicated.

But these are not TRUE random numbers because the random generation is deterministic.

But depending your case you can use this technique reducing the amount of processing on random number generation when using shuffling.

Here a LFSR algorithm in java, (I took it somewhere I don't remeber):

public final class LFSR {
    private static final int M = 15;

    // hard-coded for 15-bits
    private static final int[] TAPS = {14, 15};

    private final boolean[] bits = new boolean[M + 1];

    public LFSR() {
        this((int)System.currentTimeMillis());
    }

    public LFSR(int seed) {
        for(int i = 0; i < M; i++) {
            bits[i] = (((1 << i) & seed) >>> i) == 1;
        }
    }

    /* generate a random int uniformly on the interval [-2^31 + 1, 2^31 - 1] */
    public short nextShort() {
        //printBits();

        // calculate the integer value from the registers
        short next = 0;
        for(int i = 0; i < M; i++) {
            next |= (bits[i] ? 1 : 0) << i;
        }

        // allow for zero without allowing for -2^31
        if (next < 0) next++;

        // calculate the last register from all the preceding
        bits[M] = false;
        for(int i = 0; i < TAPS.length; i++) {
            bits[M] ^= bits[M - TAPS[i]];
        }

        // shift all the registers
        for(int i = 0; i < M; i++) {
            bits[i] = bits[i + 1];
        }

        return next;
    }

    /** returns random double uniformly over [0, 1) */
    public double nextDouble() {
        return ((nextShort() / (Integer.MAX_VALUE + 1.0)) + 1.0) / 2.0;
    }

    /** returns random boolean */
    public boolean nextBoolean() {
        return nextShort() >= 0;
    }

    public void printBits() {
        System.out.print(bits[M] ? 1 : 0);
        System.out.print(" -> ");
        for(int i = M - 1; i >= 0; i--) {
            System.out.print(bits[i] ? 1 : 0);
        }
        System.out.println();
    }


    public static void main(String[] args) {
        LFSR rng = new LFSR();
        Vector<Short> vec = new Vector<Short>();
        for(int i = 0; i <= 32766; i++) {
            short next = rng.nextShort();
            // just testing/asserting to make 
            // sure the number doesn't repeat on a given list
            if (vec.contains(next))
                throw new RuntimeException("Index repeat: " + i);
            vec.add(next);
            System.out.println(next);
        }
    }
}

Redirect From Action Filter Attribute

Alternatively to a redirect, if it is calling your own code, you could use this:

actionContext.Result = new RedirectToRouteResult(
    new RouteValueDictionary(new { controller = "Home", action = "Error" })
);

actionContext.Result.ExecuteResult(actionContext.Controller.ControllerContext);

It is not a pure redirect but gives a similar result without unnecessary overhead.

What is the actual use of Class.forName("oracle.jdbc.driver.OracleDriver") while connecting to a database?

Use oracle.jdbc.OracleDriver, not oracle.jdbc.driver.OracleDriver. You do not need to register it if the driver jar file is in the "WEB-INF\lib" directory, if you are using Tomcat. Save this as test.jsp and put it in your web directory, and redeploy your web app folder in Tomcat manager:

<%@ page import="java.sql.*" %>

<HTML>
<HEAD>
<TITLE>Simple JSP Oracle Test</TITLE>
</HEAD><BODY>
<%
Connection conn = null;
try {
    Class.forName("oracle.jdbc.OracleDriver");
    conn = DriverManager.getConnection("jdbc:oracle:thin:@XXX.XXX.XXX.XXX:XXXX:dbName", "user", "password");
    Statement stmt = conn.createStatement();
    out.println("Connection established!");
}
catch (Exception ex)
{
    out.println("Exception: " + ex.getMessage() + "");

}
finally
{
    if (conn != null) {
        try {
            conn.close();   
        }
        catch (Exception ignored) {
            // ignore
        }
    }
}

%>

String field value length in mongoDB

For MongoDB 3.6 and newer:

The $expr operator allows the use of aggregation expressions within the query language, thus you can leverage the use of $strLenCP operator to check the length of the string as follows:

db.usercollection.find({ 
    "name": { "$exists": true },
    "$expr": { "$gt": [ { "$strLenCP": "$name" }, 40 ] } 
})

For MongoDB 3.4 and newer:

You can also use the aggregation framework with the $redact pipeline operator that allows you to proccess the logical condition with the $cond operator and uses the special operations $$KEEP to "keep" the document where the logical condition is true or $$PRUNE to "remove" the document where the condition was false.

This operation is similar to having a $project pipeline that selects the fields in the collection and creates a new field that holds the result from the logical condition query and then a subsequent $match, except that $redact uses a single pipeline stage which is more efficient.

As for the logical condition, there are String Aggregation Operators that you can use $strLenCP operator to check the length of the string. If the length is $gt a specified value, then this is a true match and the document is "kept". Otherwise it is "pruned" and discarded.


Consider running the following aggregate operation which demonstrates the above concept:

db.usercollection.aggregate([
    { "$match": { "name": { "$exists": true } } },
    {
        "$redact": {
            "$cond": [
                { "$gt": [ { "$strLenCP": "$name" }, 40] },
                "$$KEEP",
                "$$PRUNE"
            ]
        }
    },
    { "$limit": 2 }
])

If using $where, try your query without the enclosing brackets:

db.usercollection.find({$where: "this.name.length > 40"}).limit(2);

A better query would be to to check for the field's existence and then check the length:

db.usercollection.find({name: {$type: 2}, $where: "this.name.length > 40"}).limit(2); 

or:

db.usercollection.find({name: {$exists: true}, $where: "this.name.length > 
40"}).limit(2); 

MongoDB evaluates non-$where query operations before $where expressions and non-$where query statements may use an index. A much better performance is to store the length of the string as another field and then you can index or search on it; applying $where will be much slower compared to that. It's recommended to use JavaScript expressions and the $where operator as a last resort when you can't structure the data in any other way, or when you are dealing with a small subset of data.


A different and faster approach that avoids the use of the $where operator is the $regex operator. Consider the following pattern which searches for

db.usercollection.find({"name": {"$type": 2, "$regex": /^.{41,}$/}}).limit(2); 

Note - From the docs:

If an index exists for the field, then MongoDB matches the regular expression against the values in the index, which can be faster than a collection scan. Further optimization can occur if the regular expression is a “prefix expression”, which means that all potential matches start with the same string. This allows MongoDB to construct a “range” from that prefix and only match against those values from the index that fall within that range.

A regular expression is a “prefix expression” if it starts with a caret (^) or a left anchor (\A), followed by a string of simple symbols. For example, the regex /^abc.*/ will be optimized by matching only against the values from the index that start with abc.

Additionally, while /^a/, /^a.*/, and /^a.*$/ match equivalent strings, they have different performance characteristics. All of these expressions use an index if an appropriate index exists; however, /^a.*/, and /^a.*$/ are slower. /^a/ can stop scanning after matching the prefix.

Query comparing dates in SQL

You put <= and it will catch the given date too. You can replace it with < only.

Where to find "Microsoft.VisualStudio.TestTools.UnitTesting" missing dll?

I know this is old, this is what came up in my Google search. I needed to reference these packages on NuGet:

enter image description here

Duplicate / Copy records in the same MySQL table

I have a similar issue, and this is what I'm doing:

insert into Preguntas  (`EncuestaID`, `Tipo` , `Seccion` , `RespuestaID` , `Texto` )  select '23', `Tipo`, `Seccion`, `RespuestaID`, `Texto` from Preguntas where `EncuestaID`= 18

Been Preguntas:

CREATE TABLE IF NOT EXISTS `Preguntas` (
  `ID` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `EncuestaID` int(11) DEFAULT NULL,
  `Tipo` char(5) COLLATE utf8_unicode_ci DEFAULT NULL,
  `Seccion` int(11) DEFAULT NULL,
  `RespuestaID` bigint(11) DEFAULT NULL,
  `Texto` text COLLATE utf8_unicode_ci ,
  PRIMARY KEY (`ID`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=522 ;

So, the ID is automatically incremented and also I'm using a fixed value ('23') for EncuestaID.

Is there a way to get a <button> element to link to a location without wrapping it in an <a href ... tag?

LINKS ARE TRICKY

Consider the tricks that <a href> knows by default but javascript linking won't do for you. On a decent website, anything that wants to behave as a link should implement these features one way or another. Namely:

  • Ctrl+Click: opens link in new tab
    You can simulate this by using a window.open() with no position/size argument
  • Shift+Click: opens link in new window
    You can simulate this by window.open() with size and/or position specified
  • Alt+Click: download target
    People rarely use this one, but if you insist to simulate it, you'll need to write a special script on server side that responds with the proper download headers.

EASY WAY OUT

Now if you don't want to simulate all that behaviour, I suggest to use <a href> and style it like a button, since the button itself is roughly a shape and a hover effect. I think if it's not semantically important to only have "the button and nothing else", <a href> is the way of the samurai. And if you worry about semantics and readability, you can also replace the button element when your document is ready(). It's clear and safe.

Setting paper size in FPDF

They say it right there in the documentation for the FPDF constructor:

FPDF([string orientation [, string unit [, mixed size]]])

This is the class constructor. It allows to set up the page size, the orientation and the unit of measure used in all methods (except for font sizes). Parameters ...

size

The size used for pages. It can be either one of the following values (case insensitive):

A3 A4 A5 Letter Legal

or an array containing the width and the height (expressed in the unit given by unit).

They even give an example with custom size:

Example with a custom 100x150 mm page size:

$pdf = new FPDF('P','mm',array(100,150));

Import Excel Data into PostgreSQL 9.3

I have used Excel/PowerPivot to create the postgreSQL insert statement. Seems like overkill, except when you need to do it over and over again. Once the data is in the PowerPivot window, I add successive columns with concatenate statements to 'build' the insert statement. I create a flattened pivot table with that last and final column. Copy and paste the resulting insert statement into my EXISTING postgreSQL table with pgAdmin.

Example two column table (my table has 30 columns from which I import successive contents over and over with the same Excel/PowerPivot.)

Column1 {a,b,...} Column2 {1,2,...}

In PowerPivot I add calculated columns with the following commands:

Calculated Column 1 has "insert into table_name values ('"

Calculated Column 2 has CONCATENATE([Calculated Column 1],CONCATENATE([Column1],"','"))

...until you get to the last column and you need to terminate the insert statement:

Calculated Column 3 has CONCATENATE([Calculated Column 2],CONCATENATE([Column2],"');"

Then in PowerPivot I add a flattened pivot table and have all of the insert statement that I just copy and paste to pgAgent.

Resulting insert statements:

insert into table_name values ('a','1');

insert into table_name values ('b','2');

insert into table_name values ('c','3');

NOTE: If you are familiar with the power pivot CONCATENATE statement, you know that it can only handle 2 arguments (nuts). Would be nice if it allowed more.

Duplicate headers received from server

Just put a pair of double quotes around your file name like this:

this.Response.AddHeader("Content-disposition", $"attachment; filename=\"{outputFileName}\"");

user authentication libraries for node.js?

Quick simple example using mongo, for an API that provides user auth for ie Angular client

in app.js

var express = require('express');
var MongoStore = require('connect-mongo')(express);

// ...

app.use(express.cookieParser());
// obviously change db settings to suit
app.use(express.session({
    secret: 'blah1234',
    store: new MongoStore({
        db: 'dbname',
        host: 'localhost',
        port: 27017
    })
}));

app.use(app.router);

for your route something like this:

// (mongo connection stuff)

exports.login = function(req, res) {

    var email = req.body.email;
    // use bcrypt in production for password hashing
    var password = req.body.password;

    db.collection('users', function(err, collection) {
        collection.findOne({'email': email, 'password': password}, function(err, user) {
            if (err) {
                res.send(500);
            } else {
                if(user !== null) {
                    req.session.user = user;
                    res.send(200);
                } else {
                    res.send(401);
                }
            }
        });
    });
};

Then in your routes that require auth you can just check for the user session:

if (!req.session.user) {
    res.send(403);
}

Bootstrap 3 collapse accordion: collapse all works but then cannot expand all while maintaining data-parent

For whatever reason $('.panel-collapse').collapse({'toggle': true, 'parent': '#accordion'}); only seems to work the first time and it only works to expand the collapsible. (I tried to start with a expanded collapsible and it wouldn't collapse.)

It could just be something that runs once the first time you initialize collapse with those parameters.

You will have more luck using the show and hide methods.

Here is an example:

$(function() {

  var $active = true;

  $('.panel-title > a').click(function(e) {
    e.preventDefault();
  });

  $('.collapse-init').on('click', function() {
    if(!$active) {
      $active = true;
      $('.panel-title > a').attr('data-toggle', 'collapse');
      $('.panel-collapse').collapse('hide');
      $(this).html('Click to disable accordion behavior');
    } else {
      $active = false;
      $('.panel-collapse').collapse('show');
      $('.panel-title > a').attr('data-toggle','');
      $(this).html('Click to enable accordion behavior');
    }
  });

});

http://bootply.com/98201

Update

Granted KyleMit seems to have a way better handle on this then me. I'm impressed with his answer and understanding.

I don't understand what's going on or why the show seemed to be toggling in some places.

But After messing around for a while.. Finally came with the following solution:

$(function() {
  var transition = false;
  var $active = true;

  $('.panel-title > a').click(function(e) {
    e.preventDefault();
  });

  $('#accordion').on('show.bs.collapse',function(){
    if($active){
        $('#accordion .in').collapse('hide');
    }
  });

  $('#accordion').on('hidden.bs.collapse',function(){
    if(transition){
        transition = false;
        $('.panel-collapse').collapse('show');
    }
  });

  $('.collapse-init').on('click', function() {
    $('.collapse-init').prop('disabled','true');
    if(!$active) {
      $active = true;
      $('.panel-title > a').attr('data-toggle', 'collapse');
      $('.panel-collapse').collapse('hide');
      $(this).html('Click to disable accordion behavior');
    } else {
      $active = false;
      if($('.panel-collapse.in').length){
        transition = true;
        $('.panel-collapse.in').collapse('hide');       
      }
      else{
        $('.panel-collapse').collapse('show');
      }
      $('.panel-title > a').attr('data-toggle','');
      $(this).html('Click to enable accordion behavior');
    }
    setTimeout(function(){
        $('.collapse-init').prop('disabled','');
    },800);
  });
});

http://bootply.com/98239

Bash script plugin for Eclipse?

Just follow the official instructions from ShellEd's InstallGuide

Removing "bullets" from unordered list <ul>

In my case

li {
  list-style-type : none;
}

It doesn't show the bullet but leaved some space for the bullet.

I use

li {
  list-style-type : '';
}

It works perfectly.

hadoop copy a local file system folder to HDFS

In Short

hdfs dfs -put <localsrc> <dest>

In detail with example:

Checking source and target before placing files into HDFS

[cloudera@quickstart ~]$ ll files/
total 132
-rwxrwxr-x 1 cloudera cloudera  5387 Nov 14 06:33 cloudera-manager
-rwxrwxr-x 1 cloudera cloudera  9964 Nov 14 06:33 cm_api.py
-rw-rw-r-- 1 cloudera cloudera   664 Nov 14 06:33 derby.log
-rw-rw-r-- 1 cloudera cloudera 53655 Nov 14 06:33 enterprise-deployment.json
-rw-rw-r-- 1 cloudera cloudera 50515 Nov 14 06:33 express-deployment.json

[cloudera@quickstart ~]$ hdfs dfs -ls
Found 1 items
drwxr-xr-x   - cloudera cloudera          0 2017-11-14 00:45 .sparkStaging

Copy files HDFS using -put or -copyFromLocal command

[cloudera@quickstart ~]$ hdfs dfs -put files/ files

Verify the result in HDFS

[cloudera@quickstart ~]$ hdfs dfs -ls
Found 2 items
drwxr-xr-x   - cloudera cloudera          0 2017-11-14 00:45 .sparkStaging
drwxr-xr-x   - cloudera cloudera          0 2017-11-14 06:34 files

[cloudera@quickstart ~]$ hdfs dfs -ls files
Found 5 items
-rw-r--r--   1 cloudera cloudera       5387 2017-11-14 06:34 files/cloudera-manager
-rw-r--r--   1 cloudera cloudera       9964 2017-11-14 06:34 files/cm_api.py
-rw-r--r--   1 cloudera cloudera        664 2017-11-14 06:34 files/derby.log
-rw-r--r--   1 cloudera cloudera      53655 2017-11-14 06:34 files/enterprise-deployment.json
-rw-r--r--   1 cloudera cloudera      50515 2017-11-14 06:34 files/express-deployment.json

Substring with reverse index

here is my custom function

function reverse_substring(str,from,to){
  var temp="";
  var i=0;
  var pos = 0;
  var append;      
  for(i=str.length-1;i>=0;i--){
    //alert("inside loop " + str[i]);
    if(pos == from){
         append=true;
    }

    if(pos == to){
         append=false;
         break;
    }
    if(append){
         temp = str[i] + temp;
    }
    pos++;
  }
  alert("bottom loop " + temp);
}

var str = "bala_123";
reverse_substring(str,0,3);

This function works for reverse index.

How do I remove duplicates from a C# array?

The best way? Hard to say, the HashSet approach looks fast, but (depending on the data) using a sort algorithm (CountSort ?) can be much faster.

using System;
using System.Collections.Generic;
using System.Linq;
class Program
{
    static void Main()
    {
        Random r = new Random(0); int[] a, b = new int[1000000];
        for (int i = b.Length - 1; i >= 0; i--) b[i] = r.Next(b.Length);
        a = new int[b.Length]; Array.Copy(b, a, b.Length);
        a = dedup0(a); Console.WriteLine(a.Length);
        a = new int[b.Length]; Array.Copy(b, a, b.Length);
        var w = System.Diagnostics.Stopwatch.StartNew();
        a = dedup0(a); Console.WriteLine(w.Elapsed); Console.Read();
    }

    static int[] dedup0(int[] a)  // 48 ms  
    {
        return new HashSet<int>(a).ToArray();
    }

    static int[] dedup1(int[] a)  // 68 ms
    {
        Array.Sort(a); int i = 0, j = 1, k = a.Length; if (k < 2) return a;
        while (j < k) if (a[i] == a[j]) j++; else a[++i] = a[j++];
        Array.Resize(ref a, i + 1); return a;
    }

    static int[] dedup2(int[] a)  //  8 ms
    {
        var b = new byte[a.Length]; int c = 0;
        for (int i = 0; i < a.Length; i++) 
            if (b[a[i]] == 0) { b[a[i]] = 1; c++; }
        a = new int[c];
        for (int j = 0, i = 0; i < b.Length; i++) if (b[i] > 0) a[j++] = i;
        return a;
    }
}

Almost branch free. How? Debug mode, Step Into (F11) with a small array: {1,3,1,1,0}

    static int[] dedupf(int[] a)  //  4 ms
    {
        if (a.Length < 2) return a;
        var b = new byte[a.Length]; int c = 0, bi, ai, i, j;
        for (i = 0; i < a.Length; i++)
        { ai = a[i]; bi = 1 ^ b[ai]; b[ai] |= (byte)bi; c += bi; }
        a = new int[c]; i = 0; while (b[i] == 0) i++; a[0] = i++;
        for (j = 0; i < b.Length; i++) a[j += bi = b[i]] += bi * i; return a;
    }

A solution with two nested loops might take some time, especially for larger arrays.

    static int[] dedup(int[] a)
    {
        int i, j, k = a.Length - 1;
        for (i = 0; i < k; i++)
            for (j = i + 1; j <= k; j++) if (a[i] == a[j]) a[j--] = a[k--];
        Array.Resize(ref a, k + 1); return a;
    }

ListView item background via custom selector

instead of:

android:drawable="@color/transparent" 

write

android:drawable="@android:color/transparent"

Get/pick an image from Android's built-in Gallery app programmatically

Assuming you have an image folder in your SD card directory for images only.

Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
// tells your intent to get the contents
// opens the URI for your image directory on your sdcard
intent.setType("file:///sdcard/image/*"); 
startActivityForResult(intent, 1);

Then you can decide with what you would like to do with the content back in your activity.

This was an example to retrieve the path name for the image, test this with your code just to make sure you can handle the results coming back. You can change the code as needed to better fit your needs.

protected final void onActivityResult(final int requestCode, final int
                     resultCode, final Intent i) {
    super.onActivityResult(requestCode, resultCode, i);

  // this matches the request code in the above call
  if (requestCode == 1) {
      Uri _uri = i.getData();

    // this will be null if no image was selected...
    if (_uri != null) {
      // now we get the path to the image file
     cursor = getContentResolver().query(_uri, null,
                                      null, null, null);
     cursor.moveToFirst();
     String imageFilePath = cursor.getString(0);
     cursor.close();
     }
   }

My advice is to try to get retrieving images working correctly, I think the problem is the content of accessing the images on the sdcard. Take a look at Displaying images on sd card.

If you can get that up and running, probably by the example supplying a correct provider, you should be able to figure out a work-around for your code.

Keep me updated by updating this question with your progress. Good luck

Convert string to JSON Object

Combining Saurabh Chandra Patel's answer with Molecular Man's observation, you should have something like this:

JSON.parse('{"TeamList" : [{"teamid" : "1","teamname" : "Barcelona"}]}');

Volatile vs Static in Java

Not sure static variables are cached in thread local memory or NOT. But when I executed two threads(T1,T2) accessing same object(obj) and when update made by T1 thread to static variable it got reflected in T2.

Is it .yaml or .yml?

The nature and even existence of file extensions is platform-dependent (some obscure platforms don't even have them, remember) -- in other systems they're only conventional (UNIX and its ilk), while in still others they have definite semantics and in some cases specific limits on length or character content (Windows, etc.).

Since the maintainers have asked that you use ".yaml", that's as close to an "official" ruling as you can get, but the habit of 8.3 is hard to get out of (and, appallingly, still occasionally relevant in 2013).

How to use CURL via a proxy?

Here is a working version with your bugs removed.

$url = 'http://dynupdate.no-ip.com/ip.php';
$proxy = '127.0.0.1:8888';
//$proxyauth = 'user:password';

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$url);
curl_setopt($ch, CURLOPT_PROXY, $proxy);
//curl_setopt($ch, CURLOPT_PROXYUSERPWD, $proxyauth);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_HEADER, 1);
$curl_scraped_page = curl_exec($ch);
curl_close($ch);

echo $curl_scraped_page;

I have added CURLOPT_PROXYUSERPWD in case any of your proxies require a user name and password. I set CURLOPT_RETURNTRANSFER to 1, so that the data will be returned to $curl_scraped_page variable.

I removed a second extra curl_exec($ch); which would stop the variable being returned. I consolidated your proxy IP and port into one setting.

I also removed CURLOPT_HTTPPROXYTUNNEL and CURLOPT_CUSTOMREQUEST as it was the default.

If you don't want the headers returned, comment out CURLOPT_HEADER.

To disable the proxy simply set it to null.

curl_setopt($ch, CURLOPT_PROXY, null);

Any questions feel free to ask, I work with cURL every day.

jQuery select element in parent window

You can also use,

parent.jQuery("#testdiv").attr("style", content from form);

NOW() function in PHP

My answer is superfluous, but if you are OCD, visually oriented and you just have to see that now keyword in your code, use:

date( 'Y-m-d H:i:s', strtotime( 'now' ) );

Begin, Rescue and Ensure in Ruby?

Yes, ensure is called in any circumstances. For more information see "Exceptions, Catch, and Throw" of the Programming Ruby book and search for "ensure".

Can you do a For Each Row loop using MySQL?

Not a for each exactly, but you can do nested SQL

SELECT 
    distinct a.ID, 
    a.col2, 
    (SELECT 
        SUM(b.size) 
    FROM 
        tableb b 
    WHERE 
        b.id = a.col3)
FROM
    tablea a

Import Excel to Datagridview

try the following program

using System;
using System.Data;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        System.Data.OleDb.OleDbConnection MyConnection;
        System.Data.DataSet DtSet;
        System.Data.OleDb.OleDbDataAdapter MyCommand;
        MyConnection = new System.Data.OleDb.OleDbConnection(@"provider=Microsoft.Jet.OLEDB.4.0;Data Source='c:\csharp.net-informations.xls';Extended Properties=Excel 8.0;");
        MyCommand = new System.Data.OleDb.OleDbDataAdapter("select * from [Sheet1$]", MyConnection);
        MyCommand.TableMappings.Add("Table", "Net-informations.com");
        DtSet = new System.Data.DataSet();
        MyCommand.Fill(DtSet);
        dataGridView1.DataSource = DtSet.Tables[0];
        MyConnection.Close();
    }
}
} 

What is the difference between the kernel space and the user space?

In Linux there are two space 1st is user space and another one is kernal space. user space consist of only user application which u want to run. as the kernal service there is process management, file management, signal handling, memory management, thread management, and so many services are present there. if u run the application from the user space that appliction interact with only kernal service. and that service is interact with device driver which is present between hardware and kernal. the main benefit of kernal space and user space seperation is we can acchive a security by the virus.bcaz of all user application present in user space, and service is present in kernal space. thats why linux doesn,t affect from the virus.

How can I throw a general exception in Java?

Java has a large number of built-in exceptions for different scenarios.

In this case, you should throw an IllegalArgumentException, since the problem is that the caller passed a bad parameter.

How to check existence of user-define table type in SQL Server 2008?

You can look in sys.types or use TYPE_ID:

IF TYPE_ID(N'MyType') IS NULL ...

Just a precaution: using type_id won't verify that the type is a table type--just that a type by that name exists. Otherwise gbn's query is probably better.

How do I delete an exported environment variable?

Because the original question doesn't mention how the variable was set, and because I got to this page looking for this specific answer, I'm adding the following:

In C shell (csh/tcsh) there are two ways to set an environment variable:

  1. set x = "something"
  2. setenv x "something"

The difference in the behaviour is that variables set with setenv command are automatically exported to subshell while variable set with set aren't.

To unset a variable set with set, use

unset x

To unset a variable set with setenv, use

unsetenv x

Note: in all the above, I assume that the variable name is 'x'.

credits:

https://www.cyberciti.biz/faq/unix-linux-difference-between-set-and-setenv-c-shell-variable/ https://www.oreilly.com/library/view/solaristm-7-reference/0130200484/0130200484_ch18lev1sec24.html

Laravel Eloquent LEFT JOIN WHERE NULL

I would be using laravel whereDoesntHave to achieve this.

Customer::whereDoesntHave('orders')->get();

Android ADT error, dx.jar was not loaded from the SDK folder

Also, make sure that the version of the ADT is supported by the AndroidSDKTools. That fixed my problem. In the SDK Manager, File->Reload will lead to the latest revisions.

Are the PUT, DELETE, HEAD, etc methods available in most web browsers?

HTML forms support GET and POST. (HTML5 at one point added PUT/DELETE, but those were dropped.)

XMLHttpRequest supports every method, including CHICKEN, though some method names are matched against case-insensitively (methods are case-sensitive per HTTP) and some method names are not supported at all for security reasons (e.g. CONNECT).

Browsers are slowly converging on the rules specified by XMLHttpRequest, but as the other comment pointed out there are still some differences.

mysql command for showing current configuration variables

What you are looking for is this:

SHOW VARIABLES;  

You can modify it further like any query:

SHOW VARIABLES LIKE '%max%';  

Proper use of const for defining functions in JavaScript

Although using const to define functions seems like a hack, but it comes with some great advantages that make it superior (in my opinion)

  1. It makes the function immutable, so you don't have to worry about that function being changed by some other piece of code.

  2. You can use fat arrow syntax, which is shorter & cleaner.

  3. Using arrow functions takes care of this binding for you.

example with function

_x000D_
_x000D_
// define a function_x000D_
function add(x, y) { return x + y; }_x000D_
_x000D_
// use it_x000D_
console.log(add(1, 2)); // 3_x000D_
_x000D_
// oops, someone mutated your function_x000D_
add = function (x, y) { return x - y; };_x000D_
_x000D_
// now this is not what you expected_x000D_
console.log(add(1, 2)); // -1
_x000D_
_x000D_
_x000D_

same example with const

_x000D_
_x000D_
// define a function (wow! that is 8 chars shorter)_x000D_
const add = (x, y) => x + y;_x000D_
_x000D_
// use it_x000D_
console.log(add(1, 2)); // 3_x000D_
_x000D_
// someone tries to mutate the function_x000D_
add = (x, y) => x - y; // Uncaught TypeError: Assignment to constant variable._x000D_
// the intruder fails and your function remains unchanged
_x000D_
_x000D_
_x000D_

Is there a way to rollback my last push to Git?

Since you are the only user:

git reset --hard HEAD@{1}
git push -f
git reset --hard HEAD@{1}

( basically, go back one commit, force push to the repo, then go back again - remove the last step if you don't care about the commit )

Without doing any changes to your local repo, you can also do something like:

git push -f origin <sha_of_previous_commit>:master

Generally, in published repos, it is safer to do git revert and then git push

Why are #ifndef and #define used in C++ header files?

Those are called #include guards.

Once the header is included, it checks if a unique value (in this case HEADERFILE_H) is defined. Then if it's not defined, it defines it and continues to the rest of the page.

When the code is included again, the first ifndef fails, resulting in a blank file.

That prevents double declaration of any identifiers such as types, enums and static variables.

Why does Git treat this text file as a binary file?

I was having this issue where Git GUI and SourceTree was treating Java/JS files as binary and thus wouldn’t show a diff.

Creating a file named attributes in .git/info with following content solved the problem:

*.java diff
*.js diff
*.pl diff
*.txt diff
*.ts diff
*.html diff
*.sh diff
*.xml diff

If you would like this to apply to all repositories, then you can add the file attributes in $HOME/.config/git/attributes.

MySQL my.cnf performance tuning recommendations

Try starting with the Percona wizard and comparing their recommendations against your current settings one by one. Don't worry there aren't as many applicable settings as you might think.

https://tools.percona.com/wizard

Update circa 2020: Sorry, this tool reached it's end of life: https://www.percona.com/blog/2019/04/22/end-of-life-query-analyzer-and-mysql-configuration-generator/

Everyone points to key_buffer_size first which you have addressed. With 96GB memory I'd be wary of any tiny default value (likely to be only 96M!).

select dept names who have more than 2 employees whose salary is greater than 1000

SELECT DEPTNAME
FROM(SELECT D.DEPTNAME,COUNT(EMPID) AS TOTEMP
     FROM DEPT AS D,EMPLOYEE AS E
     WHERE D.DEPTID=E.DEPTID AND SALARY>1000
     GROUP BY D.DEPTID
     )
WHERE TOTEMP>2;

What is a Windows Handle?

A HANDLE in Win32 programming is a token that represents a resource that is managed by the Windows kernel. A handle can be to a window, a file, etc.

Handles are simply a way of identifying a particulate resource that you want to work with using the Win32 APIs.

So for instance, if you want to create a Window, and show it on the screen you could do the following:

// Create the window
HWND hwnd = CreateWindow(...); 
if (!hwnd)
   return; // hwnd not created

// Show the window.
ShowWindow(hwnd, SW_SHOW);

In the above example HWND means "a handle to a window".

If you are used to an object oriented language you can think of a HANDLE as an instance of a class with no methods who's state is only modifiable by other functions. In this case the ShowWindow function modifies the state of the Window HANDLE.

See Handles and Data Types for more information.

How to check if click event is already bound - JQuery

If using jQuery 1.7+:

You can call off before on:

$('#myButton').off('click', onButtonClicked) // remove handler
              .on('click', onButtonClicked); // add handler

If not:

You can just unbind it first event:

$('#myButton').unbind('click', onButtonClicked) //remove handler
              .bind('click', onButtonClicked);  //add handler

Get second child using jQuery

Try this:

$("td:eq(1)", $(t))

or

$("td", $(t)).eq(1)

How to Get the Query Executed in Laravel 5? DB::getQueryLog() Returning Empty Array

Apparently with Laravel 5.2, the closure in DB::listen only receives a single parameter.

So, if you want to use DB::listen in Laravel 5.2, you should do something like:

DB::listen(
    function ($sql) {
        // $sql is an object with the properties:
        //  sql: The query
        //  bindings: the sql query variables
        //  time: The execution time for the query
        //  connectionName: The name of the connection

        // To save the executed queries to file:
        // Process the sql and the bindings:
        foreach ($sql->bindings as $i => $binding) {
            if ($binding instanceof \DateTime) {
                $sql->bindings[$i] = $binding->format('\'Y-m-d H:i:s\'');
            } else {
                if (is_string($binding)) {
                    $sql->bindings[$i] = "'$binding'";
                }
            }
        }

        // Insert bindings into query
        $query = str_replace(array('%', '?'), array('%%', '%s'), $sql->sql);

        $query = vsprintf($query, $sql->bindings);

        // Save the query to file
        $logFile = fopen(
            storage_path('logs' . DIRECTORY_SEPARATOR . date('Y-m-d') . '_query.log'),
            'a+'
        );
        fwrite($logFile, date('Y-m-d H:i:s') . ': ' . $query . PHP_EOL);
        fclose($logFile);
    }
);

REST API using POST instead of GET

If I understand the question correctly, he needs to perform a REST GET action, but wonders if it's OK to send in data via HTTP POST method.

As Scott had nicely laid out in his answer earlier, there are many good reasons to POST input data. IMHO it should be done this way, if quality of solution is the top priority.

A while back we created an REST API to authenticate users, taking username/password and returning an access token. The API is encrypted under TLS, but exposed to public internet. After evaluating different options, we chose HTTP POST for the REST method of "GET access token," because that's the only way to meet security standards.

In PHP how can you clear a WSDL cache?

You can safely delete the WSDL cache files. If you wish to prevent future caching, use:

ini_set("soap.wsdl_cache_enabled", 0);

or dynamically:

$client = new SoapClient('http://somewhere.com/?wsdl', array('cache_wsdl' => WSDL_CACHE_NONE) );

How to autoplay HTML5 mp4 video on Android?

In Android 4.1 and 4.2, I use the following code.

    evt.initMouseEvent( "click", true,true,window,0,0,0,0,0,false,false,false,false,0, true );
    var v = document.getElementById("video");
    v.dispatchEvent(evt);

where html is

    <video id="video" src="sample.mp4" poster="image.jpg" controls></video>

This works well. But In Android 4.4, it does not work.

Angular 2 two way binding using ngModel is not working

As per Angular2 final, you do not even have to import FORM_DIRECTIVES as suggested above by many. However, the syntax has been changed as kebab-case was dropped for the betterment.

Just replace ng-model with ngModel and wrap it in a box of bananas. But you have spilt the code into two files now:

app.ts:

import { Component } from '@angular/core';

@Component({
  selector: 'ng-app',
  template: `
    <input id="name" type="text" [(ngModel)]="name"  />
    {{ name }}
  `
})
export class DataBindingComponent {
  name: string;

  constructor() {
    this.name = 'Jose';
  }
}

app.module.ts:

import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { BrowserModule } from '@angular/platform-browser';
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { DataBindingComponent } from './app'; //app.ts above

@NgModule({
  declarations: [DataBindingComponent],
  imports:      [BrowserModule, FormsModule],
  bootstrap:    [DataBindingComponent]
})
export default class MyAppModule {}

platformBrowserDynamic().bootstrapModule(MyAppModule);

Setting up MySQL and importing dump within Dockerfile

The latest version of the official mysql docker image allows you to import data on startup. Here is my docker-compose.yml

data:
  build: docker/data/.
mysql:
  image: mysql
  ports:
    - "3307:3306"
  environment:
    MYSQL_ROOT_PASSWORD: 1234
  volumes:
    - ./docker/data:/docker-entrypoint-initdb.d
  volumes_from:
    - data

Here, I have my data-dump.sql under docker/data which is relative to the folder the docker-compose is running from. I am mounting that sql file into this directory /docker-entrypoint-initdb.d on the container.

If you are interested to see how this works, have a look at their docker-entrypoint.sh in GitHub. They have added this block to allow importing data

    echo
    for f in /docker-entrypoint-initdb.d/*; do
        case "$f" in
            *.sh)  echo "$0: running $f"; . "$f" ;;
            *.sql) echo "$0: running $f"; "${mysql[@]}" < "$f" && echo ;;
            *)     echo "$0: ignoring $f" ;;
        esac
        echo
    done

An additional note, if you want the data to be persisted even after the mysql container is stopped and removed, you need to have a separate data container as you see in the docker-compose.yml. The contents of the data container Dockerfile are very simple.

FROM n3ziniuka5/ubuntu-oracle-jdk:14.04-JDK8

VOLUME /var/lib/mysql

CMD ["true"]

The data container doesn't even have to be in start state for persistence.

Interface naming in Java

There is also another convention, used by many open source projects including Spring.

interface User {
}

class DefaultUser implements User {
}

class AnotherClassOfUser implements User {
}

I personally do not like the "I" prefix for the simple reason that its an optional convention. So if I adopt this does IIOPConnection mean an interface for IOPConnection? What if the class does not have the "I" prefix, do I then know its not an interface..the answer here is no, because conventions are not always followed, and policing them will create more work that the convention itself saves.

Android: How to change the ActionBar "Home" Icon to be something other than the app icon?

The ActionBar will use the android:logo attribute of your manifest, if one is provided. That lets you use separate drawable resources for the icon (Launcher) and the logo (ActionBar, among other things).

Create an application setup in visual studio 2013

Microsoft also release the Microsoft Visual Studio 2015 Installer Projects Extension This is the same extension as the 2013 version but for Visual Studio 2015

A JRE or JDK must be available in order to run Eclipse. No JVM was found after searching the following locations

I had this problem too on a win7 machine. I wanted to update the jre with a jdk. So i deleted the jre folder and downloaded and unzipped the new jdk. The issue was i manually deleted the jre folder, when instead i should've uninstalled it. This leaves a bunch of registry entries that still point to the old jre. Somehow eclipse still wants to use the old jre. I couldn't uninstall the old java vm, i kept getting this error:

Error 1723. There is a problem with this Windows Installer package. A DLL required for this install to complete could not be run. Contact your support personnel or package vendor

So i had to use this MS utility to fix the uninstall:

http://support.microsoft.com/kb/2438651/

Then i had to install again the vm. I installed to the same location the original one was at, to avoid losing another hour! After that eclipse started correctly.

Julio

How can I run a PHP script inside a HTML file?

I'm not sure if this is what you wanted, but this is a very hackish way to include php. What you do is you put the php you want to run in another file, and then you include that file in an image. For example:

RunFromHTML.php

<?php
  $file = fopen("file.txt", "w");
  //This will create a file called file.txt,
  //provided that it has write access to your filesystem
  fwrite($file, "Hello World!");
  //This will write "Hello World!" into file.txt
  fclose($file);
  //Always remember to close your files!
?>

RunPhp.html

<html>
  <!--head should be here, but isn't for demonstration's sake-->
  <body>
    <img style="display: none;" src="RunFromHTML.php">
    <!--This will run RunFromHTML.php-->
  </body>
</html>

Now, after visiting RunPhp.html, you should find a file called file.txt in the same directory that you created the above two files, and the file should contain "Hello World!" inside of it.

Benefits of using the conditional ?: (ternary) operator

The conditional operator is great for short conditions, like this:

varA = boolB ? valC : valD;

I use it occasionally because it takes less time to write something that way... unfortunately, this branching can sometimes be missed by another developer browsing over your code. Plus, code isn't usually that short, so I usually help readability by putting the ? and : on separate lines, like this:

doSomeStuffToSomething(shouldSomethingBeDone()
    ? getTheThingThatNeedsStuffDone()
    : getTheOtherThingThatNeedsStuffDone());

However, the big advantage to using if/else blocks (and why I prefer them) is that it's easier to come in later and add some additional logic to the branch,

if (shouldSomethingBeDone()) {
    doSomeStuffToSomething(getTheThingThatNeedsStuffDone());
    doSomeAdditionalStuff();
} else {
doSomeStuffToSomething(getTheOtherThingThatNeedsStuffDone());
}

or add another condition:

if (shouldSomethingBeDone()) {
    doSomeStuffToSomething(getTheThingThatNeedsStuffDone());
    doSomeAdditionalStuff();
} else if (shouldThisOtherThingBeDone()){
    doSomeStuffToSomething(getTheOtherThingThatNeedsStuffDone());
}

So, in the end, it's about convenience for you now (shorter to use :?) vs. convenience for you (and others) later. It's a judgment call... but like all other code-formatting issues, the only real rule is to be consistent, and be visually courteous to those who have to maintain (or grade!) your code.

(all code eye-compiled)

Hex transparency in colors

enter image description here

This might be very late answer. But this chart kills it.

All percentage values are mapped to the hexadecimal values.

http://online.sfsu.edu/chrism/hexval.html

How can I tell how many objects I've stored in an S3 bucket?

Here's the boto3 version of the python script embedded above.

import sys
import boto3

s3 = boto3.resource('s3')
s3bucket = s3.Bucket(sys.argv[1])
size = 0
totalCount = 0

for key in s3bucket.objects.all():
    totalCount += 1
    size += key.size

print('total size:')
print("%.3f GB" % (size*1.0/1024/1024/1024))
print('total count:')
print(totalCount)`

What's the difference between getPath(), getAbsolutePath(), and getCanonicalPath() in Java?

The big thing to get your head around is that the File class tries to represent a view of what Sun like to call "hierarchical pathnames" (basically a path like c:/foo.txt or /usr/muggins). This is why you create files in terms of paths. The operations you are describing are all operations upon this "pathname".

  • getPath() fetches the path that the File was created with (../foo.txt)
  • getAbsolutePath() fetches the path that the File was created with, but includes information about the current directory if the path is relative (/usr/bobstuff/../foo.txt)
  • getCanonicalPath() attempts to fetch a unique representation of the absolute path to the file. This eliminates indirection from ".." and "." references (/usr/foo.txt).

Note I say attempts - in forming a Canonical Path, the VM can throw an IOException. This usually occurs because it is performing some filesystem operations, any one of which could fail.

Double border with different color

You can use outline with outline offset

<div class="double-border"></div>
.double-border{
background-color:#ccc;
outline: 1px solid #f00;
outline-offset: 3px;
}

Different between parseInt() and valueOf() in java?

Integer.parseInt can just return int as native type.

Integer.valueOf may actually need to allocate an Integer object, unless that integer happens to be one of the preallocated ones. This costs more.

If you need just native type, use parseInt. If you need an object, use valueOf.

Also, because of this potential allocation, autoboxing isn't actually good thing in every way. It can slow down things.

Android simple alert dialog

You can easily make your own 'AlertView' and use it everywhere.

alertView("You really want this?");

Implement it once:

private void alertView( String message ) {
 AlertDialog.Builder dialog = new AlertDialog.Builder(context);
 dialog.setTitle( "Hello" )
       .setIcon(R.drawable.ic_launcher)
       .setMessage(message)
//     .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
//      public void onClick(DialogInterface dialoginterface, int i) {
//          dialoginterface.cancel();   
//          }})
      .setPositiveButton("Ok", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialoginterface, int i) {   
        }               
        }).show();
 }

Delete specified file from document directory

In Swift both 3&4

 func removeImageLocalPath(localPathName:String) {
            let filemanager = FileManager.default
            let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory,.userDomainMask,true)[0] as NSString
            let destinationPath = documentsPath.appendingPathComponent(localPathName)
 do {
        try filemanager.removeItem(atPath: destinationPath)
        print("Local path removed successfully")
    } catch let error as NSError {
        print("------Error",error.debugDescription)
    }
    }

or This method can delete all local file

func deletingLocalCacheAttachments(){
        let fileManager = FileManager.default
        let documentsURL = fileManager.urls(for: .documentDirectory, in: .userDomainMask)[0]
        do {
            let fileURLs = try fileManager.contentsOfDirectory(at: documentsURL, includingPropertiesForKeys: nil)
            if fileURLs.count > 0{
                for fileURL in fileURLs {
                    try fileManager.removeItem(at: fileURL)
                }
            }
        } catch {
            print("Error while enumerating files \(documentsURL.path): \(error.localizedDescription)")
        }
    }

How do I use extern to share variables between source files?

In C a variable inside a file say example.c is given local scope. The compiler expects that the variable would have its definition inside the same file example.c and when it does not find the same , it would throw an error.A function on the other hand has by default global scope . Thus you do not have to explicitly mention to the compiler "look dude...you might find the definition of this function here". For a function including the file which contains its declaration is enough.(The file which you actually call a header file). For example consider the following 2 files :
example.c

#include<stdio.h>
extern int a;
main(){
       printf("The value of a is <%d>\n",a);
}

example1.c

int a = 5;

Now when you compile the two files together, using the following commands :

step 1)cc -o ex example.c example1.c step 2)./ex

You get the following output : The value of a is <5>

Difference between ApiController and Controller in ASP.NET MVC

In Asp.net Core 3+ Vesrion

Controller: If wants to return anything related to IActionResult & Data also, go for Controllercontroller

ApiController: Used as attribute/notation in API controller. That inherits ControllerBase Class

ControllerBase: If wants to return data only go for ControllerBase class

Binding Button click to a method

Some more explanations to the solution Rachel already gave:

"WPF Apps With The Model-View-ViewModel Design Pattern"

by Josh Smith

http://msdn.microsoft.com/en-us/magazine/dd419663.aspx

Mask output of `The following objects are masked from....:` after calling attach() function

You use attach without detach - every time you do it new call to attach masks objects attached before (they contain the same names). Either use detach or do not use attach at all. Nice discussion and tips are here.

MySQL stored procedure vs function, which would I use when?

A stored function can be used within a query. You could then apply it to every row, or within a WHERE clause.

A procedure is executed using the CALL query.

How can I select multiple columns from a subquery (in SQL Server) that should have one record (select top 1) for each record in the main query?

You'll have to make a join:

SELECT A.SalesOrderID, B.Foo
FROM A
JOIN B bo ON bo.id = (
     SELECT TOP 1 id
     FROM B bi
     WHERE bi.SalesOrderID = a.SalesOrderID
     ORDER BY bi.whatever
     )
WHERE A.Date BETWEEN '2000-1-4' AND '2010-1-4'

, assuming that b.id is a PRIMARY KEY on B

In MS SQL 2005 and higher you may use this syntax:

SELECT SalesOrderID, Foo
FROM (
  SELECT A.SalesOrderId, B.Foo,
         ROW_NUMBER() OVER (PARTITION BY B.SalesOrderId ORDER BY B.whatever) AS rn
  FROM A
  JOIN B ON B.SalesOrderID = A.SalesOrderID
  WHERE A.Date BETWEEN '2000-1-4' AND '2010-1-4'
) i
WHERE rn

This will select exactly one record from B for each SalesOrderId.

Detect click inside/outside of element with single event handler

This question can be answered with X and Y coordinates and without JQuery:

       var isPointerEventInsideElement = function (event, element) {
            var pos = {
                x: event.targetTouches ? event.targetTouches[0].pageX : event.pageX,
                y: event.targetTouches ? event.targetTouches[0].pageY : event.pageY
            };
            var rect = element.getBoundingClientRect();
            return  pos.x < rect.right && pos.x > rect.left && pos.y < rect.bottom && pos.y > rect.top;
        };

        document.querySelector('#my-element').addEventListener('click', function (event) {
           console.log(isPointerEventInsideElement(event, document.querySelector('#my-any-child-element')))
        });

How do I use .woff fonts for my website?

After generation of woff files, you have to define font-family, which can be used later in all your css styles. Below is the code to define font families (for normal, bold, bold-italic, italic) typefaces. It is assumed, that there are 4 *.woff files (for mentioned typefaces), placed in fonts subdirectory.

In CSS code:

@font-face {
    font-family: "myfont";
    src: url("fonts/awesome-font.woff") format('woff');
}

@font-face {
    font-family: "myfont";
    src: url("fonts/awesome-font-bold.woff") format('woff');
    font-weight: bold;
}

@font-face {
    font-family: "myfont";
    src: url("fonts/awesome-font-boldoblique.woff") format('woff');
    font-weight: bold;
    font-style: italic;
}

@font-face {
    font-family: "myfont";
    src: url("fonts/awesome-font-oblique.woff") format('woff');
    font-style: italic;
}

After having that definitions, you can just write, for example,

In HTML code:

<div class="mydiv">
    <b>this will be written with awesome-font-bold.woff</b>
    <br/>
    <b><i>this will be written with awesome-font-boldoblique.woff</i></b>
    <br/>
    <i>this will be written with awesome-font-oblique.woff</i>
    <br/>
    this will be written with awesome-font.woff
</div>

In CSS code:

.mydiv {
    font-family: myfont
}

The good tool for generation woff files, which can be included in CSS stylesheets is located here. Not all woff files work correctly under latest Firefox versions, and this generator produces 'correct' fonts.

How to find the duration of difference between two dates in java?

Date d2 = new Date();
Date d1 = new Date(1384831803875l);

long diff = d2.getTime() - d1.getTime();
long diffSeconds = diff / 1000 % 60;
long diffMinutes = diff / (60 * 1000) % 60;
long diffHours = diff / (60 * 60 * 1000);
int diffInDays = (int) diff / (1000 * 60 * 60 * 24);

System.out.println(diffInDays+"  days");
System.out.println(diffHours+"  Hour");
System.out.println(diffMinutes+"  min");
System.out.println(diffSeconds+"  sec");

Converting XDocument to XmlDocument and vice versa

If you need to convert the instance of System.Xml.Linq.XDocument into the instance of the System.Xml.XmlDocument this extension method will help you to do not lose the XML declaration in the resulting XmlDocument instance:

using System.Xml; 
using System.Xml.Linq;

namespace www.dimaka.com
{ 
    internal static class LinqHelper 
    { 
        public static XmlDocument ToXmlDocument(this XDocument xDocument) 
        { 
            var xmlDocument = new XmlDocument(); 
            using (var reader = xDocument.CreateReader()) 
            { 
                xmlDocument.Load(reader); 
            }

            var xDeclaration = xDocument.Declaration; 
            if (xDeclaration != null) 
            { 
                var xmlDeclaration = xmlDocument.CreateXmlDeclaration( 
                    xDeclaration.Version, 
                    xDeclaration.Encoding, 
                    xDeclaration.Standalone);

                xmlDocument.InsertBefore(xmlDeclaration, xmlDocument.FirstChild); 
            }

            return xmlDocument; 
        } 
    } 
}

Hope that helps!

Key Shortcut for Eclipse Imports

IntelliJ just inserts them automagically; no shortcut required. If the class name is ambiguous, it'll show me the list of possibilities to choose from. It reads my mind....

Fade Effect on Link Hover?

I know in the question you state "I assume JavaScript is used to create this effect" but CSS can be used too, an example is below.

CSS

.fancy-link {
   color: #333333;
   text-decoration: none;
   transition: color 0.3s linear;
   -webkit-transition: color 0.3s linear;
   -moz-transition: color 0.3s linear;
}

.fancy-link:hover {
   color: #F44336;
}

HTML

<a class="fancy-link" href="#">My Link</a>

And here is a JSFIDDLE for the above code!


Marcel in one of the answers points out you can "transition multiple CSS properties" you can also use "all" to effect the element with all your :hover styles like below.

CSS

.fancy-link {
   color: #333333;
   text-decoration: none;
   transition: all 0.3s linear;
   -webkit-transition: all 0.3s linear;
   -moz-transition: all 0.3s linear;
}

.fancy-link:hover {
   color: #F44336;
   padding-left: 10px;
}

HTML

<a class="fancy-link" href="#">My Link</a>

And here is a JSFIDDLE for the "all" example!

C# static class constructor

Yes, a static class can have static constructor, and the use of this constructor is initialization of static member.

static class Employee1
{
    static int EmpNo;
    static Employee1()
    {
        EmpNo = 10;
        // perform initialization here
    }
    public static void Add()
    { 

    }
    public static void Add1()
    { 

    }
}

and static constructor get called only once when you have access any type member of static class with class name Class1

Suppose you are accessing the first EmployeeName field then constructor get called this time, after that it will not get called, even if you will access same type member.

 Employee1.EmployeeName = "kumod";
        Employee1.Add();
        Employee1.Add();

How to get method parameter names?

In CPython, the number of arguments is

a_method.func_code.co_argcount

and their names are in the beginning of

a_method.func_code.co_varnames

These are implementation details of CPython, so this probably does not work in other implementations of Python, such as IronPython and Jython.

One portable way to admit "pass-through" arguments is to define your function with the signature func(*args, **kwargs). This is used a lot in e.g. matplotlib, where the outer API layer passes lots of keyword arguments to the lower-level API.

How do I redirect with JavaScript?

Compared to window.location="url"; it is much easyer to do just location="url"; I always use that

Enable IIS7 gzip

If you are also trying to gzip dynamic pages (like aspx) and it isnt working, its probably because the option is not enabled (you need to install the Dynamic Content Compression module using Windows Features):

http://support.esri.com/en/knowledgebase/techarticles/detail/38616

Define a fixed-size list in Java

This should work pretty nicely. It will never grow beyond the initial size. The toList method will give you the entries in the correct chronological order. This was done in groovy - but converting it to java proper should be pretty easy.

static class FixedSizeCircularReference<T> {
    T[] entries
    FixedSizeCircularReference(int size) {
        this.entries = new Object[size] as T[]
        this.size = size
    }
    int cur = 0
    int size
    void add(T entry) {
        entries[cur++] = entry
        if (cur >= size) {
            cur = 0
        }
    }
    List<T> asList() {
        List<T> list = new ArrayList<>()
        int oldest = (cur == size - 1) ? 0 : cur
        for (int i = 0; i < this.entries.length; i++) {
            def e = this.entries[oldest + i < size ? oldest + i : oldest + i - size]
            if (e) list.add(e)
        }
        return list
    }
}

FixedSizeCircularReference<String> latestEntries = new FixedSizeCircularReference(100)
latestEntries.add('message 1') 
// .....
latestEntries.add('message 1000') 
latestEntries.asList() //Returns list of '100' messages

how to get a list of dates between two dates in java

java9 features you can calculate like this

public  List<LocalDate> getDatesBetween (
 LocalDate startDate, LocalDate endDate) {

   return startDate.datesUntil(endDate)
     .collect(Collectors.toList());
}
`` 


What is an undefined reference/unresolved external symbol error and how do I fix it?

Your linkage consumes libraries before the object files that refer to them

  • You are trying to compile and link your program with the GCC toolchain.
  • Your linkage specifies all of the necessary libraries and library search paths
  • If libfoo depends on libbar, then your linkage correctly puts libfoo before libbar.
  • Your linkage fails with undefined reference to something errors.
  • But all the undefined somethings are declared in the header files you have #included and are in fact defined in the libraries that you are linking.

Examples are in C. They could equally well be C++

A minimal example involving a static library you built yourself

my_lib.c

#include "my_lib.h"
#include <stdio.h>

void hw(void)
{
    puts("Hello World");
}

my_lib.h

#ifndef MY_LIB_H
#define MT_LIB_H

extern void hw(void);

#endif

eg1.c

#include <my_lib.h>

int main()
{
    hw();
    return 0;
}

You build your static library:

$ gcc -c -o my_lib.o my_lib.c
$ ar rcs libmy_lib.a my_lib.o

You compile your program:

$ gcc -I. -c -o eg1.o eg1.c

You try to link it with libmy_lib.a and fail:

$ gcc -o eg1 -L. -lmy_lib eg1.o 
eg1.o: In function `main':
eg1.c:(.text+0x5): undefined reference to `hw'
collect2: error: ld returned 1 exit status

The same result if you compile and link in one step, like:

$ gcc -o eg1 -I. -L. -lmy_lib eg1.c
/tmp/ccQk1tvs.o: In function `main':
eg1.c:(.text+0x5): undefined reference to `hw'
collect2: error: ld returned 1 exit status

A minimal example involving a shared system library, the compression library libz

eg2.c

#include <zlib.h>
#include <stdio.h>

int main()
{
    printf("%s\n",zlibVersion());
    return 0;
}

Compile your program:

$ gcc -c -o eg2.o eg2.c

Try to link your program with libz and fail:

$ gcc -o eg2 -lz eg2.o 
eg2.o: In function `main':
eg2.c:(.text+0x5): undefined reference to `zlibVersion'
collect2: error: ld returned 1 exit status

Same if you compile and link in one go:

$ gcc -o eg2 -I. -lz eg2.c
/tmp/ccxCiGn7.o: In function `main':
eg2.c:(.text+0x5): undefined reference to `zlibVersion'
collect2: error: ld returned 1 exit status

And a variation on example 2 involving pkg-config:

$ gcc -o eg2 $(pkg-config --libs zlib) eg2.o 
eg2.o: In function `main':
eg2.c:(.text+0x5): undefined reference to `zlibVersion'

What are you doing wrong?

In the sequence of object files and libraries you want to link to make your program, you are placing the libraries before the object files that refer to them. You need to place the libraries after the object files that refer to them.

Link example 1 correctly:

$ gcc -o eg1 eg1.o -L. -lmy_lib

Success:

$ ./eg1 
Hello World

Link example 2 correctly:

$ gcc -o eg2 eg2.o -lz

Success:

$ ./eg2 
1.2.8

Link the example 2 pkg-config variation correctly:

$ gcc -o eg2 eg2.o $(pkg-config --libs zlib) 
$ ./eg2
1.2.8

The explanation

Reading is optional from here on.

By default, a linkage command generated by GCC, on your distro, consumes the files in the linkage from left to right in commandline sequence. When it finds that a file refers to something and does not contain a definition for it, to will search for a definition in files further to the right. If it eventually finds a definition, the reference is resolved. If any references remain unresolved at the end, the linkage fails: the linker does not search backwards.

First, example 1, with static library my_lib.a

A static library is an indexed archive of object files. When the linker finds -lmy_lib in the linkage sequence and figures out that this refers to the static library ./libmy_lib.a, it wants to know whether your program needs any of the object files in libmy_lib.a.

There is only object file in libmy_lib.a, namely my_lib.o, and there's only one thing defined in my_lib.o, namely the function hw.

The linker will decide that your program needs my_lib.o if and only if it already knows that your program refers to hw, in one or more of the object files it has already added to the program, and that none of the object files it has already added contains a definition for hw.

If that is true, then the linker will extract a copy of my_lib.o from the library and add it to your program. Then, your program contains a definition for hw, so its references to hw are resolved.

When you try to link the program like:

$ gcc -o eg1 -L. -lmy_lib eg1.o

the linker has not added eg1.o to the program when it sees -lmy_lib. Because at that point, it has not seen eg1.o. Your program does not yet make any references to hw: it does not yet make any references at all, because all the references it makes are in eg1.o.

So the linker does not add my_lib.o to the program and has no further use for libmy_lib.a.

Next, it finds eg1.o, and adds it to be program. An object file in the linkage sequence is always added to the program. Now, the program makes a reference to hw, and does not contain a definition of hw; but there is nothing left in the linkage sequence that could provide the missing definition. The reference to hw ends up unresolved, and the linkage fails.

Second, example 2, with shared library libz

A shared library isn't an archive of object files or anything like it. It's much more like a program that doesn't have a main function and instead exposes multiple other symbols that it defines, so that other programs can use them at runtime.

Many Linux distros today configure their GCC toolchain so that its language drivers (gcc,g++,gfortran etc) instruct the system linker (ld) to link shared libraries on an as-needed basis. You have got one of those distros.

This means that when the linker finds -lz in the linkage sequence, and figures out that this refers to the shared library (say) /usr/lib/x86_64-linux-gnu/libz.so, it wants to know whether any references that it has added to your program that aren't yet defined have definitions that are exported by libz

If that is true, then the linker will not copy any chunks out of libz and add them to your program; instead, it will just doctor the code of your program so that:-

  • At runtime, the system program loader will load a copy of libz into the same process as your program whenever it loads a copy of your program, to run it.

  • At runtime, whenever your program refers to something that is defined in libz, that reference uses the definition exported by the copy of libz in the same process.

Your program wants to refer to just one thing that has a definition exported by libz, namely the function zlibVersion, which is referred to just once, in eg2.c. If the linker adds that reference to your program, and then finds the definition exported by libz, the reference is resolved

But when you try to link the program like:

gcc -o eg2 -lz eg2.o

the order of events is wrong in just the same way as with example 1. At the point when the linker finds -lz, there are no references to anything in the program: they are all in eg2.o, which has not yet been seen. So the linker decides it has no use for libz. When it reaches eg2.o, adds it to the program, and then has undefined reference to zlibVersion, the linkage sequence is finished; that reference is unresolved, and the linkage fails.

Lastly, the pkg-config variation of example 2 has a now obvious explanation. After shell-expansion:

gcc -o eg2 $(pkg-config --libs zlib) eg2.o

becomes:

gcc -o eg2 -lz eg2.o

which is just example 2 again.

I can reproduce the problem in example 1, but not in example 2

The linkage:

gcc -o eg2 -lz eg2.o

works just fine for you!

(Or: That linkage worked fine for you on, say, Fedora 23, but fails on Ubuntu 16.04)

That's because the distro on which the linkage works is one of the ones that does not configure its GCC toolchain to link shared libraries as-needed.

Back in the day, it was normal for unix-like systems to link static and shared libraries by different rules. Static libraries in a linkage sequence were linked on the as-needed basis explained in example 1, but shared libraries were linked unconditionally.

This behaviour is economical at linktime because the linker doesn't have to ponder whether a shared library is needed by the program: if it's a shared library, link it. And most libraries in most linkages are shared libraries. But there are disadvantages too:-

  • It is uneconomical at runtime, because it can cause shared libraries to be loaded along with a program even if doesn't need them.

  • The different linkage rules for static and shared libraries can be confusing to inexpert programmers, who may not know whether -lfoo in their linkage is going to resolve to /some/where/libfoo.a or to /some/where/libfoo.so, and might not understand the difference between shared and static libraries anyway.

This trade-off has led to the schismatic situation today. Some distros have changed their GCC linkage rules for shared libraries so that the as-needed principle applies for all libraries. Some distros have stuck with the old way.

Why do I still get this problem even if I compile-and-link at the same time?

If I just do:

$ gcc -o eg1 -I. -L. -lmy_lib eg1.c

surely gcc has to compile eg1.c first, and then link the resulting object file with libmy_lib.a. So how can it not know that object file is needed when it's doing the linking?

Because compiling and linking with a single command does not change the order of the linkage sequence.

When you run the command above, gcc figures out that you want compilation + linkage. So behind the scenes, it generates a compilation command, and runs it, then generates a linkage command, and runs it, as if you had run the two commands:

$ gcc -I. -c -o eg1.o eg1.c
$ gcc -o eg1 -L. -lmy_lib eg1.o

So the linkage fails just as it does if you do run those two commands. The only difference you notice in the failure is that gcc has generated a temporary object file in the compile + link case, because you're not telling it to use eg1.o. We see:

/tmp/ccQk1tvs.o: In function `main'

instead of:

eg1.o: In function `main':

See also

The order in which interdependent linked libraries are specified is wrong

Putting interdependent libraries in the wrong order is just one way in which you can get files that need definitions of things coming later in the linkage than the files that provide the definitions. Putting libraries before the object files that refer to them is another way of making the same mistake.

How to pass a list from Python, by Jinja2 to JavaScript

I had a similar problem using Flask, but I did not have to resort to JSON. I just passed a list letters = ['a','b','c'] with render_template('show_entries.html', letters=letters), and set

var letters = {{ letters|safe }}

in my javascript code. Jinja2 replaced {{ letters }} with ['a','b','c'], which javascript interpreted as an array of strings.

How to read attribute value from XmlNode in C#?

Use

item.Attributes["Name"].Value;

to get the value.

Create a .tar.bz2 file Linux

You are not indicating what to include in the archive.

Go one level outside your folder and try:

sudo tar -cvjSf folder.tar.bz2 folder

Or from the same folder try

sudo tar -cvjSf folder.tar.bz2 *

Cheers!

How does MySQL process ORDER BY and LIMIT in a query?

It will order first, then get the first 20. A database will also process anything in the WHERE clause before ORDER BY.

Suppress output of a function

It isn't clear why you want to do this without sink, but you can wrap any commands in the invisible() function and it will suppress the output. For instance:

1:10 # prints output
invisible(1:10) # hides it

Otherwise, you can always combine things into one line with a semicolon and parentheses:

{ sink("/dev/null"); ....; sink(); }

How to determine one year from now in Javascript

2020

It's perfect date/time library called Moment.js with this library you can simply write:

moment().subtract(1,'year')

and call any format you wish:

moment().subtract(1,'year').toDate()
moment().subtract(1,'year').toISOString()

See full documentation here: https://momentjs.com/

Rename a table in MySQL

RENAME TABLE tb1 TO tb2;

tb1 - current table name. tb2 - the name you want your table to be called.

Reference jars inside a jar

In Eclipse you have option to export executable jar. enter image description here You have an option to package all project related jars into generated jar and in this way eclipse add custom class loader which will refer to you integrated jars within new jar.

enter image description here

Make div stay at bottom of page's content all the time even when there are scrollbars

I just want to add - most of the other answers worked fine for me; however, it took a long time to get them working!

This is because setting height: 100% only picks up parent div's height!

So if your entire html (inside of the body) looks like the following:

<div id="holder">
    <header>.....</header>
    <div id="body">....</div>
    <footer>....</footer>
</div>

Then the following will be fine:

html,body{
    height: 100%
}

#holder{
    min-height: 100%;
    position:relative;
}

#body{
    padding-bottom: 100px;    /* height of footer */
}

footer{
    height: 100px; 
    width:100%;
    position: absolute;
    left: 0;
    bottom: 0; 
}

...as "holder" will pick up it's height directly from "body".

Kudos to My Head Hurts, whose answer was the one I ended up getting to work!

However. If your html is more nested (because it's only an element of the full page, or it's within a certain column, etc) then you need to make sure every containing element also has height: 100% set on the div. Otherwise, the information on height will be lost between "body" and "holder".

E.g. the following, where I've added the "full height" class to every div to make sure the height gets all the way down to our header/body/footer elements:

<div class="full-height">
    <div class="container full-height">
        <div id="holder">
            <header>.....</header>
            <div id="body">....</div>
            <footer>....</footer>
        </div>
    </div>
</div>

And remember to set height on full-height class in the css:

#full-height{
    height: 100%;
}

That fixed my issues!

What is a database transaction?

Here's a simple explanation. You need to transfer 100 bucks from account A to account B. You can either do:

accountA -= 100;
accountB += 100;

or

accountB += 100;
accountA -= 100;

If something goes wrong between the first and the second operation in the pair you have a problem - either 100 bucks have disappeared, or they have appeared out of nowhere.

A transaction is a mechanism that allows you to mark a group of operations and execute them in such a way that either they all execute (commit), or the system state will be as if they have not started to execute at all (rollback).

beginTransaction;
accountB += 100;
accountA -= 100;
commitTransaction;

will either transfer 100 bucks or leave both accounts in the initial state.

Styling the arrow on bootstrap tooltips

For styling each directional arrows(left, right,top and bottom), we have to select each arrow using CSS attribute selector and then style them individually.

Trick: Top arrow must have border color only on top side and transparent on other 3 sides. Other directional arrows also need to be styled this way.

click here for Working Jsfiddle Link

Here is the simple CSS,

.tooltip-inner { background-color:#8447cf;}

[data-placement="top"] + .tooltip > .tooltip-arrow { border-top-color: #8447cf;}

[data-placement="right"] + .tooltip > .tooltip-arrow { border-right-color: #8447cf;}

[data-placement="bottom"] + .tooltip > .tooltip-arrow {border-bottom-color: #8447cf;}

[data-placement="left"] + .tooltip > .tooltip-arrow {border-left-color: #8447cf; }

SET NOCOUNT ON usage

Ok now I've done my research, here is the deal:

In TDS protocol, SET NOCOUNT ON only saves 9-bytes per query while the text "SET NOCOUNT ON" itself is a whopping 14 bytes. I used to think that 123 row(s) affected was returned from server in plain text in a separate network packet but that's not the case. It's in fact a small structure called DONE_IN_PROC embedded in the response. It's not a separate network packet so no roundtrips are wasted.

I think you can stick to default counting behavior almost always without worrying about the performance. There are some cases though, where calculating the number of rows beforehand would impact the performance, such as a forward-only cursor. In that case NOCOUNT might be a necessity. Other than that, there is absolutely no need to follow "use NOCOUNT wherever possible" motto.

Here is a very detailed analysis about insignificance of SET NOCOUNT setting: http://daleburnett.com/2014/01/everything-ever-wanted-know-set-nocount/

Waiting for Target Device to Come Online

None of solutions above worked for me, so I had to wipe content of

C:\Users\your_name\.android\avd

and re-create emulated device

Getting the array length of a 2D array in Java

There's not a cleaner way at the language level because not all multidimensional arrays are rectangular. Sometimes jagged (differing column lengths) arrays are necessary.

You could easy create your own class to abstract the functionality you need.

If you aren't limited to arrays, then perhaps some of the various collection classes would work as well, like a Multimap.

Sending command line arguments to npm script

For PowerShell users on Windows

The accepted answer did not work for me with npm 6.14. Neither adding no -- nor including it once does work. However, putting -- twice or putting "--" once before the arguments does the trick. Example:

npm run <my_script> -- -- <my arguments like --this>

Suspected reason

Like in bash, -- instructs PowerShell to treat all following arguments as literal strings, and not options (E.g see this answer). The issues seems to be that the command is interpreted one time more than expected, loosing the '--'. For instance, by doing

npm run <my_script> -- --option value

npm will run

<my_script> value

However, doing

npm run <my_script> "--" --option value

results in

<my_script> "--option" "value"

which works fine.

Combine a list of data frames into one data frame by row

One other option is to use a plyr function:

df <- ldply(listOfDataFrames, data.frame)

This is a little slower than the original:

> system.time({ df <- do.call("rbind", listOfDataFrames) })
   user  system elapsed 
   0.25    0.00    0.25 
> system.time({ df2 <- ldply(listOfDataFrames, data.frame) })
   user  system elapsed 
   0.30    0.00    0.29
> identical(df, df2)
[1] TRUE

My guess is that using do.call("rbind", ...) is going to be the fastest approach that you will find unless you can do something like (a) use a matrices instead of a data.frames and (b) preallocate the final matrix and assign to it rather than growing it.

Edit 1:

Based on Hadley's comment, here's the latest version of rbind.fill from CRAN:

> system.time({ df3 <- rbind.fill(listOfDataFrames) })
   user  system elapsed 
   0.24    0.00    0.23 
> identical(df, df3)
[1] TRUE

This is easier than rbind, and marginally faster (these timings hold up over multiple runs). And as far as I understand it, the version of plyr on github is even faster than this.

java get file size efficiently

The benchmark given by GHad measures lots of other stuff (such as reflection, instantiating objects, etc.) besides getting the length. If we try to get rid of these things then for one call I get the following times in microseconds:

   file sum___19.0, per Iteration___19.0
    raf sum___16.0, per Iteration___16.0
channel sum__273.0, per Iteration__273.0

For 100 runs and 10000 iterations I get:

   file sum__1767629.0, per Iteration__1.7676290000000001
    raf sum___881284.0, per Iteration__0.8812840000000001
channel sum___414286.0, per Iteration__0.414286

I did run the following modified code giving as an argument the name of a 100MB file.

import java.io.*;
import java.nio.channels.*;
import java.net.*;
import java.util.*;

public class FileSizeBench {

  private static File file;
  private static FileChannel channel;
  private static RandomAccessFile raf;

  public static void main(String[] args) throws Exception {
    int runs = 1;
    int iterations = 1;

    file = new File(args[0]);
    channel = new FileInputStream(args[0]).getChannel();
    raf = new RandomAccessFile(args[0], "r");

    HashMap<String, Double> times = new HashMap<String, Double>();
    times.put("file", 0.0);
    times.put("channel", 0.0);
    times.put("raf", 0.0);

    long start;
    for (int i = 0; i < runs; ++i) {
      long l = file.length();

      start = System.nanoTime();
      for (int j = 0; j < iterations; ++j)
        if (l != file.length()) throw new Exception();
      times.put("file", times.get("file") + System.nanoTime() - start);

      start = System.nanoTime();
      for (int j = 0; j < iterations; ++j)
        if (l != channel.size()) throw new Exception();
      times.put("channel", times.get("channel") + System.nanoTime() - start);

      start = System.nanoTime();
      for (int j = 0; j < iterations; ++j)
        if (l != raf.length()) throw new Exception();
      times.put("raf", times.get("raf") + System.nanoTime() - start);
    }
    for (Map.Entry<String, Double> entry : times.entrySet()) {
        System.out.println(
            entry.getKey() + " sum: " + 1e-3 * entry.getValue() +
            ", per Iteration: " + (1e-3 * entry.getValue() / runs / iterations));
    }
  }
}

Postgresql - unable to drop database because of some auto connections to DB

In macOS try to restart postgresql database through the console using the command:

brew services restart postgresql

Pandas DataFrame Groupby two columns and get counts

Inserting data into a pandas dataframe and providing column name.

import pandas as pd
df = pd.DataFrame([['A','C','A','B','C','A','B','B','A','A'], ['ONE','TWO','ONE','ONE','ONE','TWO','ONE','TWO','ONE','THREE']]).T
df.columns = [['Alphabet','Words']]
print(df)   #printing dataframe.

This is our printed data:

enter image description here

For making a group of dataframe in pandas and counter,
You need to provide one more column which counts the grouping, let's call that column as, "COUNTER" in dataframe.

Like this:

df['COUNTER'] =1       #initially, set that counter to 1.
group_data = df.groupby(['Alphabet','Words'])['COUNTER'].sum() #sum function
print(group_data)

OUTPUT:

enter image description here