Programs & Examples On #Factory method

A design pattern which defines an interface for creating an object, but lets the classes that implement the interface decide which class to instantiate. One of the Gang of Four's creational design patterns.

What are static factory methods?

NOTE! "The static factory method is NOT the same as the Factory Method pattern" (c) Effective Java, Joshua Bloch.

Factory Method: "Define an interface for creating an object, but let the classes which implement the interface decide which class to instantiate. The Factory method lets a class defer instantiation to subclasses" (c) GoF.

"Static factory method is simply a static method that returns an instance of a class." (c) Effective Java, Joshua Bloch. Usually this method is inside a particular class.

The difference:

The key idea of static factory method is to gain control over object creation and delegate it from constructor to static method. The decision of object to be created is like in Abstract Factory made outside the method (in common case, but not always). While the key (!) idea of Factory Method is to delegate decision of what instance of class to create inside Factory Method. E.g. classic Singleton implementation is a special case of static factory method. Example of commonly used static factory methods:

  • valueOf
  • getInstance
  • newInstance

How to implement the factory method pattern in C++ correctly

I know this question has been answered 3 years ago, but this may be what your were looking for.

Google has released a couple of weeks ago a library allowing easy and flexible dynamic object allocations. Here it is:

What are the differences between Abstract Factory and Factory design patterns?

Difference between AbstractFactory and Factory design patterns are as follows:

  • Factory Method is used to create one product only but Abstract Factory is about creating families of related or dependent products.
  • Factory Method pattern exposes a method to the client for creating the object whereas in the case of Abstract Factory they expose a family of related objects which may consist of these Factory methods.
  • Factory Method pattern hides the construction of a single object whereas Abstract Factory hides the construction of a family of related objects. Abstract factories are usually implemented using (a set of) factory methods.
  • Abstract Factory pattern uses composition to delegate the responsibility of creating an object to another class while Factory Method design pattern uses inheritance and relies on a derived class or subclass to create an object.
  • The idea behind the Factory Method pattern is that it allows for the case where a client doesn't know what concrete classes it will be required to create at runtime, but just wants to get a class that will do the job while Abstract Factory pattern is best utilized when your system has to create multiple families of products or you want to provide a library of products without exposing the implementation details.!

Factory Method Pattern Implementation: Factory Method UML

Abstract Factory Pattern Implementation:

Abstract Factory UML

What is the basic difference between the Factory and Abstract Factory Design Patterns?

I think we can understand the difference between these two by seeing a Java8 example code:

  interface Something{}

  interface OneWhoCanProvideSomething {
     Something getSomething();

  interface OneWhoCanProvideCreatorsOfSomething{
     OneWhoCanProvideSomething getCreator();

public class AbstractFactoryExample {

    public static void main(String[] args) {
        //I need something
        //Let's create one
        Something something = new Something() {};

        //Or ask someone (FACTORY pattern)
        OneWhoCanProvideSomething oneWhoCanProvideSomethingOfTypeA = () -> null;
        OneWhoCanProvideSomething oneWhoCanProvideSomethingOfTypeB = () -> null;

        //Or ask someone who knows soemone who can create something (ABSTRACT FACTORY pattern)
        OneWhoCanProvideCreatorsOfSomething oneWhoCanProvideCreatorsOfSomething = () -> null;

        //Same thing, but you don't need to write you own interfaces
        Supplier<Something> supplierOfSomething = () -> null;
        Supplier<Supplier<Something>> supplierOfSupplier = () -> null;


Now the question is which way of creation should you use and why: The first way (no pattern, just plain constructor): creating by yourself is not a good idea, you have to do all the work, and your client code is tied to the particular implementation.

The second way (using Factory pattern): provides you the benefit that you can pass any type of implementation, which can provide different type of something based on some condition (maybe a parameter passed to creational method).

The third way (using Abstract Factory pattern): This gives you more flexibility. You can find different types of creators of something based on some condition (maybe a parameter passed).

Note that you can always get away with Factory pattern by combining two conditions together (which slightly increases code complexity, and coupling), I guess that's why we rarely see real life use cases of Abstract Factory pattern.

What is the difference between Builder Design pattern and Factory Design pattern?

First some general things to follow my argumentation:

The main challenge in designing big software systems is that they have to be flexible and uncomplicated to change. For this reason, there are some metrics like coupling and cohesion. To achieve systems that can be easily altered or extended in its functionality without the need to redesign the whole system from scratch, you can follow the design principles (like SOLID, etc.). After a while some developer recognized that if they follow those principles there are some similar solutions that worked well to similar problems. Those standard solutions turned out to be the design patterns.

So the design patterns are to support you to follow the general design principles in order to achieve loosely coupled systems with high cohesion.

Answering the question:

By asking the difference between two patterns you have to ask yourself what pattern makes your system in which way more flexible. Each pattern has its own purpose to organize dependencies between classes in your system.

The Abstract Factory Pattern: GoF: “Provide an interface for creating families of related or dependent objects without specifying their concrete classes.”

What does this mean: By providing an interface like this the call to the constructor of each of the family’s product is encapsulated in the factory class. And because this is the only place in your whole system where those constructors are called you can alter your system by implementing a new factory class. If you exchange the representation of the factory through another, you can exchange a whole set of products without touching the majority of your code.

The Builder Pattern: GoF: “Separate the construction of a complex object from its representation so that the same construction process can create different representations.”

What does this mean: You encapsulate the process of construction in another class, called the director (GoF). This director contains the algorithm of creating new instances of the product (e.g. compose a complex product out of other parts). To create the integral parts of the whole product the director uses a builder. By exchanging the builder in the director you can use the same algorithm to create the product, but change the representations of single parts (and so the representation of the product). To extend or modify your system in the representation of the product, all you need to do is to implement a new builder class.

So in short: The Abstract Factory Pattern’s purpose is to exchange a set of products which are made to be used together. The Builder Pattern’s purpose is to encapsulate the abstract algorithm of creating a product to reuse it for different representations of the product.

In my opinion you can’t say that the Abstract Factory Pattern is the big brother of the Builder Pattern. YES, they are both creational patterns, but the main intent of the patterns is entirely different.

Factory Pattern. When to use factory methods?

I think it will depend of loose coupling degree that you want to bring to your code.

Factory method decouples things very well but factory class no.

In other words, it's easier to change things if you use factory method than if you use a simple factory (known as factory class).

Look into this example: . Now, imagine that you want to bring a new Animal. In Factory class you need to change the Factory but in the factory method, no, you only need to add a new subclass.

What's the function like sum() but for multiplication? product()?

There's a prod() in numpy that does what you're asking for.

MS Access - execute a saved query by name in VBA

To use CurrentDb.Execute, your query must be an action query, AND in quotes.

CurrentDb.Execute "queryname"

Duplicating a MySQL table, indices, and data

After I tried the solution above, I come up with my own way.

My solution a little manual and needs DBMS.

First, export the data.

Second, open the export data.

Third, replace old table name with new table name.

Fourth, change all the trigger name in the data (I use MySQL and it show error when I don't change trigger name).

Fifth, import your edited SQL data to the database.

How to uninstall Golang?

Use this command to uninstall Golang for Ubuntu.

This will remove just the golang-go package itself.

sudo apt-get remove golang-go

Uninstall golang-go and its dependencies:

sudo apt-get remove --auto-remove golang-go

Datanode process not running in Hadoop

I ran into the same issue. I have created a hdfs folder '/home/username/hdfs' with sub-directories name, data, and tmp which were referenced in config xml files of hadoop/conf.

When I started hadoop and did jps, I couldn't find datanode so I tried to manually start datanode using bin/hadoop datanode. Then I realized from error message that it has permissions issue accessing the which was referenced in one of the hadoop config files. All I had to do was stop hadoop, delete the contents of /home/username/hdfs/tmp/* directory and then try this command - chmod -R 755 /home/username/hdfs/ and then start hadoop. I could find the datanode!

Gradle - Could not target platform: 'Java SE 8' using tool chain: 'JDK 7 (1.7)'

I had a very related issue but for higher Java versions:

$ ./gradlew clean assemble

... <other normal Gradle output>

Could not target platform: 'Java SE 11' using tool chain: 'JDK 8 (1.8)'.

I noticed that the task succeeded when running using InteliJ. Adding a file (same level as build.gradle) called .java-version solved my issue:

 # .java-version

How do I display the current value of an Android Preference in the Preference summary?

Android documentation says one can use a String formatting marker in getSummary():

If the summary has a String formatting marker in it (i.e. "%s" or "%1$s"), then the current entry value will be substituted in its place.

Simply specifying android:summary="Clean up messages after %s days" in ListPreference xml declaration worked for me.

Note: This only works for ListPreference.

Using CSS in Laravel views?

You can also write a simple link tag as you normaly would and then on the href attr use:

<link rel="stylesheet" href="<?php echo asset('css/common.css')?>" type="text/css"> 

of course you need to put your css file under public/css

Python - OpenCV - imread - Displaying Image

In openCV whenever you try to display an oversized image or image bigger than your display resolution you get the cropped display. It's a default behaviour.
In order to view the image in the window of your choice openCV encourages to use named window. Please refer to namedWindow documentation

The function namedWindow creates a window that can be used as a placeholder for images and trackbars. Created windows are referred to by their names.

cv.namedWindow(name, flags=CV_WINDOW_AUTOSIZE) where each window is related to image container by the name arg, make sure to use same name


import cv2
frame = cv2.imread('1.jpg')
cv2.namedWindow("Display 1")
cv2.resizeWindow("Display 1", 300, 300)
cv2.imshow("Display 1", frame)

C++: How to round a double to an int?

Casting to an int truncates the value. Adding 0.5 causes it to do proper rounding.

int y = (int)(x + 0.5);

Uncaught ReferenceError: function is not defined with onclick

I got this resolved in angular with (click) = "someFuncionName()" in the .html file for the specific component.

Testing pointers for validity (C/C++)

Setting the pointer to NULL before and after using is a good technique. This is easy to do in C++ if you manage pointers within a class for example (a string):

class SomeClass

    void SetText( const char *text);
    char *GetText() const { return MyText; }
    void Clear();

    char * MyText;

    MyText = NULL;


void SomeClass::Clear()
    if (MyText)
        free( MyText);

    MyText = NULL;

void SomeClass::Settext( const char *text)

    MyText = malloc( strlen(text));

    if (MyText)
        strcpy( MyText, text);

How Should I Declare Foreign Key Relationships Using Code First Entity Framework (4.1) in MVC3?

If you have an Order class, adding a property that references another class in your model, for instance Customer should be enough to let EF know there's a relationship in there:

public class Order
    public int ID { get; set; }

    // Some other properties

    // Foreign key to customer
    public virtual Customer Customer { get; set; }

You can always set the FK relation explicitly:

public class Order
    public int ID { get; set; }

    // Some other properties

    // Foreign key to customer
    public string CustomerID { get; set; }
    public virtual Customer Customer { get; set; }

The ForeignKeyAttribute constructor takes a string as a parameter: if you place it on a foreign key property it represents the name of the associated navigation property. If you place it on the navigation property it represents the name of the associated foreign key.

What this means is, if you where to place the ForeignKeyAttribute on the Customer property, the attribute would take CustomerID in the constructor:

public string CustomerID { get; set; }
public virtual Customer Customer { get; set; }

EDIT based on Latest Code You get that error because of this line:

public Patient Patient { get; set; }

EF will look for a property called Parent to use it as the Foreign Key enforcer. You can do 2 things:

1) Remove the ForeignKeyAttribute and replace it with the RequiredAttribute to mark the relation as required:

public virtual Patient Patient { get; set; }

Decorating a property with the RequiredAttribute also has a nice side effect: The relation in the database is created with ON DELETE CASCADE.

I would also recommend making the property virtual to enable Lazy Loading.

2) Create a property called Parent that will serve as a Foreign Key. In that case it probably makes more sense to call it for instance ParentID (you'll need to change the name in the ForeignKeyAttribute as well):

public int ParentID { get; set; }

In my experience in this case though it works better to have it the other way around:

public int ParentID { get; set; }

public virtual Patient Patient { get; set; }

Changing text color of menu item in navigation drawer

NavigationView has a method called setItemTextColor(). It uses a ColorStateList.

int[][] state = new int[][] {
        new int[] {-android.R.attr.state_enabled}, // disabled
        new int[] {android.R.attr.state_enabled}, // enabled
        new int[] {-android.R.attr.state_checked}, // unchecked
        new int[] { android.R.attr.state_pressed}  // pressed


int[] color = new int[] {

ColorStateList csl = new ColorStateList(state, color);

int[][] states = new int[][] {
        new int[] {-android.R.attr.state_enabled}, // disabled
        new int[] {android.R.attr.state_enabled}, // enabled
        new int[] {-android.R.attr.state_checked}, // unchecked
        new int[] { android.R.attr.state_pressed}  // pressed


int[] colors = new int[] {

ColorStateList csl2 = new ColorStateList(states, colors);

Here is where I got that answer. And then right after assigning my NavigationView:

if (nightMode == 0) {

ipython notebook clear cell output in code

And in case you come here, like I did, looking to do the same thing for plots in a Julia notebook in Jupyter, using Plots, you can use:


so for a kind of animated plot of multiple runs

    if nrun==1  
      display(plot(x,y))         # first plot
      IJulia.clear_output(true)  # clear the window (as above)
      display(plot!(x,y))        # plot! overlays the plot

Without the clear_output call, all plots appear separately.

what are the .map files used for in Bootstrap 3.x?

Have you ever found yourself wishing you could keep your client-side code readable and more importantly debuggable even after you've combined and minified it, without impacting performance? Well now you can through the magic of source maps.

This article explains Source Maps using a practical approach.

Constants in Kotlin -- what's a recommended way to create them?

Avoid using companion objects. Behind the hood, getter and setter instance methods are created for the fields to be accessible. Calling instance methods is technically more expensive than calling static methods.

public class DbConstants {
    companion object {
        val TABLE_USER_ATTRIBUTE_EMPID = "_id"
        val TABLE_USER_ATTRIBUTE_DATA = "data"

Instead define the constants in object.

Recommended practice :

object DbConstants {
        const val TABLE_USER_ATTRIBUTE_EMPID = "_id"
        const val TABLE_USER_ATTRIBUTE_DATA = "data"

and access them globally like this: DbConstants.TABLE_USER_ATTRIBUTE_EMPID

How to terminate a process in vbscript

The Win32_Process class provides access to both 32-bit and 64-bit processes when the script is run from a 64-bit command shell.

If this is not an option for you, you can try using the taskkill command:

Dim oShell : Set oShell = CreateObject("WScript.Shell")

' Launch notepad '
oShell.Run "notepad"
WScript.Sleep 3000

' Kill notepad '
oShell.Run "taskkill /im notepad.exe", , True

What can be the reasons of connection refused errors?

In Ubuntu, Try sudo ufw allow <port_number> to allow firewall access to both of your server and db.

Regex for remove everything after | (with | )

If you want to get everything after | excluding set character use this code.


Others solutions \|.*$

Results : | mypcworld

This one [^|]*$

Results : mypcworld

Open Jquery modal dialog on click event

Try this

    $(function() {

$('#clickMe').click(function(event) {
    var mytext = $('#myText').val();

    $('<div id="dialog">'+mytext+'</div>').appendTo('body');        

            width: 600,
            modal: true,
            close: function(event, ui) {
    }); //close click

And in HTML

<h3 id="clickMe">Open dialog</h3>
<textarea cols="0" rows="0" id="myText" style="display:none">Some hidden text display none</textarea>

Internal Error 500 Apache, but nothing in the logs?

Please Note: The original poster was not specifically asking about PHP. All the php centric answers make large assumptions not relevant to the actual question.

The default error log as opposed to the scripts error logs usually has the (more) specific error. often it will be permissions denied or even an interpreter that can't be found.

This means the fault almost always lies with your script. e.g you uploaded a perl script but didnt give it execute permissions? or perhaps it was corrupted in a linux environment if you write the script in windows and then upload it to the server without the line endings being converted you will get this error.

in perl if you forget

print "content-type: text/html\r\n\r\n";

you will get this error

There are many reasons for it. so please first check your error log and then provide some more information.

The default error log is often in /var/log/httpd/error_log or /var/log/apache2/error.log.

The reason you look at the default error logs (as indicated above) is because errors don't always get posted into the custom error log as defined in the virtual host.

Assumes linux and not necessarily perl

Html attributes for EditorFor() in ASP.NET MVC

Here is the VB.Net code syntax for html attributes in MVC 5.1 EditorFor

@Html.EditorFor(Function(x) x.myStringProp, New With {.htmlAttributes = New With {.class = "myCssClass", .maxlength="30"}}))

How do I create a MessageBox in C#?

Also you can use a MessageBox with OKCancel options, but it requires many codes. The if block is for OK, the else block is for Cancel. Here is the code:

if (MessageBox.Show("Are you sure you want to do this?", "Question", MessageBoxButtons.OKCancel, MessageBoxIcon.Question) == DialogResult.OK)
    MessageBox.Show("You pressed OK!");
    MessageBox.Show("You pressed Cancel!");

You can also use a MessageBox with YesNo options:

if (MessageBox.Show("Are you sure want to doing this?", "Question", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
    MessageBox.Show("You are pressed Yes!");
    MessageBox.Show("You are pressed No!");

How to downgrade from Internet Explorer 11 to Internet Explorer 10?

  1. Save and close all Internet Explorer windows and then, run Windows Task Manager to end the running processes in background.
  2. Go to Control Panel.
  3. Click Programs and choose the View installed updates instead.
  4. Locate the following Windows Internet Explorer 11 or you can type "Internet Explorer" for a quick search.
  5. Choose the Yes option from the following "Uninstall an update".
  6. Please wait while Windows Internet Explorer 10 is being restored and reconfigured automatically.
  7. Follow the Microsoft Windows wizard to restart your system.

Note: You can do it for as many earlier versions you want, i.e. IE9, IE8 and so on.

How can I find the number of days between two Date objects in Ruby?

In Ruby 2.1.3 things have changed:

> endDate =, 1, 2)
 => #<Date: 2014-01-02 ((2456660j,0s,0n),+0s,2299161j)> 
> beginDate =, 1, 1)
 => #<Date: 2014-01-01 ((2456659j,0s,0n),+0s,2299161j)> 
> days = endDate - beginDate
 => (1/1) 
> days.class
 => Rational 
> days.to_i
 => 1 

How to call function that takes an argument in a Django template?

By design, Django templates cannot call into arbitrary Python code. This is a security and safety feature for environments where designers write templates, and it also prevents business logic migrating into templates.

If you want to do this, you can switch to using Jinja2 templates (, or any other templating system you like that supports this. No other part of django will be affected by the templates you use, because it is intentionally a one-way process. You could even use many different template systems in the same project if you wanted.

How can I get my Android device country code without using GPS?

Here is a complete example. It tries to get the country code from TelephonyManager (from SIM or CDMA devices), and if not available, tries to get it from the local configuration.

private static String getDeviceCountryCode(Context context) {
    String countryCode;

    // Try to get country code from TelephonyManager service
    TelephonyManager tm = (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
    if(tm != null) {
        // Query first getSimCountryIso()
        countryCode = tm.getSimCountryIso();
        if (countryCode != null && countryCode.length() == 2)
            return countryCode.toLowerCase();

        if (tm.getPhoneType() == TelephonyManager.PHONE_TYPE_CDMA) {
            // Special case for CDMA Devices
            countryCode = getCDMACountryIso();
        else {
            // For 3G devices (with SIM) query getNetworkCountryIso()
            countryCode = tm.getNetworkCountryIso();

        if (countryCode != null && countryCode.length() == 2)
            return countryCode.toLowerCase();

    // If network country not available (tablets maybe), get country code from Locale class
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        countryCode = context.getResources().getConfiguration().getLocales().get(0).getCountry();
    else {
        countryCode = context.getResources().getConfiguration().locale.getCountry();

    if (countryCode != null && countryCode.length() == 2)
        return  countryCode.toLowerCase();

    // General fallback to "us"
    return "us";

private static String getCDMACountryIso() {
    try {
        // Try to get country code from SystemProperties private class
        Class<?> systemProperties = Class.forName("android.os.SystemProperties");
        Method get = systemProperties.getMethod("get", String.class);

        // Get homeOperator that contain MCC + MNC
        String homeOperator = ((String) get.invoke(systemProperties,

        // First three characters (MCC) from homeOperator represents the country code
        int mcc = Integer.parseInt(homeOperator.substring(0, 3));

        // Mapping just countries that actually use CDMA networks
        switch (mcc) {
            case 330: return "PR";
            case 310: return "US";
            case 311: return "US";
            case 312: return "US";
            case 316: return "US";
            case 283: return "AM";
            case 460: return "CN";
            case 455: return "MO";
            case 414: return "MM";
            case 619: return "SL";
            case 450: return "KR";
            case 634: return "SD";
            case 434: return "UZ";
            case 232: return "AT";
            case 204: return "NL";
            case 262: return "DE";
            case 247: return "LV";
            case 255: return "UA";
    catch (ClassNotFoundException ignored) {
    catch (NoSuchMethodException ignored) {
    catch (IllegalAccessException ignored) {
    catch (InvocationTargetException ignored) {
    catch (NullPointerException ignored) {

    return null;

Also another idea is to try an API request like in this answer.

References are here and here.

Html.RenderPartial() syntax with Razor

Html.RenderPartial() is a void method - you can check whether a method is a void method by placing your mouse over the call to RenderPartial in your code and you will see the text (extension) void HtmlHelper.RenderPartial...

Void methods require a semicolon at the end of the calling code.

In the Webforms view engine you would have encased your Html.RenderPartial() call within the bee stings <% %>

like so

<% Html.RenderPartial("Path/to/my/partial/view"); %>

when you are using the Razor view engine the equivalent is


How does ApplicationContextAware work in Spring?

Spring source code to explain how ApplicationContextAware work
when you use ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
In AbstractApplicationContext class,the refresh() method have the following code:

// Prepare the bean factory for use in this context.

enter this method,beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this)); will add ApplicationContextAwareProcessor to AbstractrBeanFactory.

protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
        // Tell the internal bean factory to use the context's class loader etc.
        beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
        beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
        // Configure the bean factory with context callbacks.
        beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));

When spring initialize bean in AbstractAutowireCapableBeanFactory, in method initializeBean,call applyBeanPostProcessorsBeforeInitialization to implement the bean post process. the process include inject the applicationContext.

    public Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName)
            throws BeansException {
        Object result = existingBean;
        for (BeanPostProcessor beanProcessor : getBeanPostProcessors()) {
            result = beanProcessor.postProcessBeforeInitialization(result, beanName);
            if (result == null) {
                return result;
        return result;

when BeanPostProcessor implement Objectto execute the postProcessBeforeInitialization method,for example ApplicationContextAwareProcessor that added before.

private void invokeAwareInterfaces(Object bean) {
        if (bean instanceof Aware) {
            if (bean instanceof EnvironmentAware) {
                ((EnvironmentAware) bean).setEnvironment(this.applicationContext.getEnvironment());
            if (bean instanceof EmbeddedValueResolverAware) {
                ((EmbeddedValueResolverAware) bean).setEmbeddedValueResolver(
                        new EmbeddedValueResolver(this.applicationContext.getBeanFactory()));
            if (bean instanceof ResourceLoaderAware) {
                ((ResourceLoaderAware) bean).setResourceLoader(this.applicationContext);
            if (bean instanceof ApplicationEventPublisherAware) {
                ((ApplicationEventPublisherAware) bean).setApplicationEventPublisher(this.applicationContext);
            if (bean instanceof MessageSourceAware) {
                ((MessageSourceAware) bean).setMessageSource(this.applicationContext);
            if (bean instanceof ApplicationContextAware) {
                ((ApplicationContextAware) bean).setApplicationContext(this.applicationContext);

What's the difference between import java.util.*; and import java.util.Date; ?

but what I got is something like this: Date@124bbbf  
while I change the import to: import java.util.Date;  
the code works perfectly, why? 

What do you mean by "works perfectly"? The output of printing a Date object is the same no matter whether you imported java.util.* or java.util.Date. The output that you get when printing objects is the representation of the object by the toString() method of the corresponding class.

How to solve the memory error in Python

Assuming your example text is representative of all the text, one line would consume about 75 bytes on my machine:

In [3]: sys.getsizeof('usedfor zipper fasten_coat')
Out[3]: 75

Doing some rough math:

75 bytes * 8,000,000 lines / 1024 / 1024 = ~572 MB

So roughly 572 meg to store the strings alone for one of these files. Once you start adding in additional, similarly structured and sized files, you'll quickly approach your virtual address space limits, as mentioned in @ShadowRanger's answer.

If upgrading your python isn't feasible for you, or if it only kicks the can down the road (you have finite physical memory after all), you really have two options: write your results to temporary files in-between loading in and reading the input files, or write your results to a database. Since you need to further post-process the strings after aggregating them, writing to a database would be the superior approach.

How is TeamViewer so fast?

A bit late answer, but I suggest you have a look at a not well known project on codeplex called ConferenceXP

ConferenceXP is an open source research platform that provides simple, flexible, and extensible conferencing and collaboration using high-bandwidth networks and the advanced multimedia capabilities of Microsoft Windows. ConferenceXP helps researchers and educators develop innovative applications and solutions that feature broadcast-quality audio and video in support of real-time distributed collaboration and distance learning environments.

Full source (it's huge!) is provided. It implements the RTP protocol.

Get real path from URI, Android KitKat new storage access framework

Before new gallery access in KitKat I got my real path in sdcard with this method

That was never reliable. There is no requirement that the Uri that you are returned from an ACTION_GET_CONTENT or ACTION_PICK request has to be indexed by the MediaStore, or even has to represent a file on the file system. The Uri could, for example, represent a stream, where an encrypted file is decrypted for you on the fly.

How could I manage to obtain the real path in sdcard?

There is no requirement that there is a file corresponding to the Uri.

Yes, I really need a path

Then copy the file from the stream to your own temporary file, and use it. Better yet, just use the stream directly, and avoid the temporary file.

I have changed my Intent.ACTION_GET_CONTENT for Intent.ACTION_PICK

That will not help your situation. There is no requirement that an ACTION_PICK response be for a Uri that has a file on the filesystem that you can somehow magically derive.

Understanding repr( ) function in Python

When you say

foo = 'bar'

you are not passing foo to the baz function. foo is just a name used to represent a value, in this case 'bar', and that value is passed to the baz function.

How to convert a HTMLElement to a string

The element outerHTML property (note: supported by Firefox after version 11) returns the HTML of the entire element.


<div id="new-element-1">Hello world.</div>

<script type="text/javascript"><!--

var element = document.getElementById("new-element-1");
var elementHtml = element.outerHTML;
// <div id="new-element-1">Hello world.</div>


Similarly, you can use innerHTML to get the HTML contained within a given element, or innerText to get the text inside an element (sans HTML markup).

See Also

  1. outerHTML - Javascript Property
  2. Javascript Reference - Elements

PHP 7 RC3: How to install missing MySQL PDO

I had, pretty much, the same problem. I was able to see that PDO was enabled but I had no available drivers (using PHP 7-RC4). I managed to resolve the issue by adding the php_pdo_mysql extension to those which were enabled.

Hope this helps!

npm check and update package if needed

npm outdated will identify packages that should be updated, and npm update <package name> can be used to update each package. But prior to [email protected], npm update <package name> will not update the versions in your package.json which is an issue.

The best workflow is to:

  1. Identify out of date packages
  2. Update the versions in your package.json
  3. Run npm update to install the latest versions of each package

Check out npm-check-updates to help with this workflow.

  • Install npm-check-updates
  • Run npm-check-updates to list what packages are out of date (basically the same thing as running npm outdated)
  • Run npm-check-updates -u to update all the versions in your package.json (this is the magic sauce)
  • Run npm update as usual to install the new versions of your packages based on the updated package.json

Transpose a data frame

You'd better not transpose the data.frame while the name column is in it - all numeric values will then be turned into strings!

Here's a solution that keeps numbers as numbers:

# first remember the names
n <- df.aree$name

# transpose all but the first column (name)
df.aree <-[,-1]))
colnames(df.aree) <- n
df.aree$myfactor <- factor(row.names(df.aree))

str(df.aree) # Check the column types

Sending HTML email using Python

You might try using my mailer module.

from mailer import Mailer
from mailer import Message

message = Message(From="[email protected]",
                  To="[email protected]")
message.Subject = "An HTML Email"
message.Html = """<p>Hi!<br>
   How are you?<br>
   Here is the <a href="">link</a> you wanted.</p>"""

sender = Mailer('')

How can I pad an integer with zeros on the left?

If performance is important in your case you could do it yourself with less overhead compared to the String.format function:

 * @param in The integer value
 * @param fill The number of digits to fill
 * @return The given value left padded with the given number of digits
public static String lPadZero(int in, int fill){

    boolean negative = false;
    int value, len = 0;

    if(in >= 0){
        value = in;
    } else {
        negative = true;
        value = - in;
        in = - in;
        len ++;

    if(value == 0){
        len = 1;
    } else{         
        for(; value != 0; len ++){
            value /= 10;

    StringBuilder sb = new StringBuilder();


    for(int i = fill; i > len; i--){


    return sb.toString();       


public static void main(String[] args) {
    Random rdm;
    long start; 

    // Using own function
    rdm = new Random(0);
    start = System.nanoTime();

    for(int i = 10000000; i != 0; i--){
        lPadZero(rdm.nextInt(20000) - 10000, 4);
    System.out.println("Own function: " + ((System.nanoTime() - start) / 1000000) + "ms");

    // Using String.format
    rdm = new Random(0);        
    start = System.nanoTime();

    for(int i = 10000000; i != 0; i--){
        String.format("%04d", rdm.nextInt(20000) - 10000);
    System.out.println("String.format: " + ((System.nanoTime() - start) / 1000000) + "ms");


Own function: 1697ms

String.format: 38134ms

OpenSSL Verify return code: 20 (unable to get local issuer certificate)

I had the same problem on OSX OpenSSL 1.0.1i from Macports, and also had to specify CApath as a workaround (and as mentioned in the Ubuntu bug report, even an invalid CApath will make openssl look in the default directory). Interestingly, connecting to the same server using PHP's openssl functions (as used in PHPMailer 5) worked fine.

How to overplot a line on a scatter plot in python?

You can use this tutorial by Adarsh Menon

This way is the easiest I found and it basically looks like:

import numpy as np
import matplotlib.pyplot as plt  # To visualize
import pandas as pd  # To read data
from sklearn.linear_model import LinearRegression
data = pd.read_csv('data.csv')  # load data set
X = data.iloc[:, 0].values.reshape(-1, 1)  # values converts it into a numpy array
Y = data.iloc[:, 1].values.reshape(-1, 1)  # -1 means that calculate the dimension of rows, but have 1 column
linear_regressor = LinearRegression()  # create object for the class, Y)  # perform linear regression
Y_pred = linear_regressor.predict(X)  # make predictions
plt.scatter(X, Y)
plt.plot(X, Y_pred, color='red')

Getting scroll bar width using JavaScript

Assuming container is only on page once and you are using jQuery, then:

var containerEl = $('.container')[0];
var scrollbarWidth = containerEl.offsetWidth - containerEl.clientWidth;

Also see this answer for more details.

Run php function on button click

You are trying to call a javascript function. If you want to call a PHP function, you have to use for example a form:

    <form action="action_page.php">
       First name:<br>
       <input type="text" name="firstname" value="Mickey">
       Last name:<br>
       <input type="text" name="lastname" value="Mouse">
       <input type="submit" value="Submit">

(Original Code from:

So if you want do do a asynchron call, you could use 'Ajax' - and yeah, that's the Javascript-Way. But I think, that my code example is enough for this time :)

Map isn't showing on Google Maps JavaScript API v3 when nested in a div tag

I just want to add what worked for me, I added height and width to both divs and used bootstrap to make it responsive

   <div class="col-lg-1 mapContainer">
       <div id="map"></div>

        height: 100%;

in order for col-lg-1 to work add bootstrap reference located Here

codeigniter, result() vs. result_array()

in my experince the problem using result() and result_array() in my JSON if using result() there no problem its works but if using result_array() i got error "Trying to get property of non-object" so im not search into deep the problem so i just using result() if using JSON and using result_array() if not using JSON

Select all from table with Laravel and Eloquent

 public function getAllPosts()
   return  Blog::all();        

Have a look at the docs this is probably the first thing they explain..

Multiple Where clauses in Lambda expressions

You can include it in the same where statement with the && operator...

x=> x.Lists.Include(l => l.Title).Where(l=>l.Title != String.Empty 
    && l.InternalName != String.Empty)

You can use any of the comparison operators (think of it like doing an if statement) such as...

List<Int32> nums = new List<int>();


var results = nums.Where(x => x == 3 || x == 10);

...would bring back 3 and 10.

When should I use GET or POST method? What's the difference between them?

You should use POST if there is a lot of data, or sort-of sensitive information (really sensitive stuff needs a secure connection as well).

Use GET if you want people to be able to bookmark your page, because all the data is included with the bookmark.

Just be careful of people hitting REFRESH with the GET method, because the data will be sent again every time without warning the user (POST sometimes warns the user about resending data).

char *array and char array[]

No. Actually it's the "same" as

char array[] = {'O', 'n', 'e', ..... 'i','c','\0');

Every character is a separate element, with an additional \0 character as a string terminator.

I quoted "same", because there are some differences between char * array and char array[]. If you want to read more, take a look at C: differences between char pointer and array

How can I check Drupal log files?

Make sure drush is installed (you may also need to make sure the dblog module is enabled) and use:

drush watchdog-show --tail

Available in drush v8 and below.

This will give you a live look at the logs from your console.

Bundler::GemNotFound: Could not find rake-10.3.2 in any of the sources

I solved the simmilar problem, when i tried to push to repo via gitlab ci/cd pipeline by the command "gem install rake && bundle install"

Python urllib2 Basic Auth Problem

The second parameter must be a URI, not a domain name. i.e.

passman = urllib2.HTTPPasswordMgrWithDefaultRealm()
passman.add_password(None, "", username, password)

Split comma-separated values

A way to do this without Linq & Lambdas

string source = "a,b, b, c";
string[] items = source.Split(new char[] { ',', ' ' }, StringSplitOptions.RemoveEmptyEntries);

How do I resize a Google Map with JavaScript after it has loaded?

If you're using Google Maps v2, call checkResize() on your map after resizing the container. link


Google Maps JavaScript API v2 was deprecated in 2011. It is not available anymore.

Fatal error: Can't open and lock privilege tables: Table '' doesn't exist

If you move your datadir, you not only need to give the new datadir permissions, but you need to ensure all parent directories have permission.

I moved my datadir to a hard drive, mounted in Ubuntu as:


and my datadir was Databases.

I had to set permissions to 771 to each of the media, user and Data directories:

sudo chmod 771 *DIR*

If this does not work, another way you can get mysql to work is to change user in /etc/mysql/my.cnf to root; though there are no doubt some issues with doing that from a security perspective.

Copy/duplicate database without using mysqldump


function cloneDatabase($dbName, $newDbName){
    global $admin;
    $db_check = @mysql_select_db ( $dbName );
    $getTables  =   $admin->query("SHOW TABLES");   
    $tables =   array();
    while($row = mysql_fetch_row($getTables)){
        $tables[]   =   $row[0];
    $createTable    =   mysql_query("CREATE DATABASE `$newDbName` DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;") or die(mysql_error());
    foreach($tables as $cTable){
        $db_check   =   @mysql_select_db ( $newDbName );
        $create     =   $admin->query("CREATE TABLE $cTable LIKE ".$dbName.".".$cTable);
        if(!$create) {
            $error  =   true;
        $insert     =   $admin->query("INSERT INTO $cTable SELECT * FROM ".$dbName.".".$cTable);
    return !isset($error);

// usage
$clone  = cloneDatabase('dbname','newdbname');  // first: toCopy, second: new database

Formatting a float to 2 decimal places

String.Format("{0:#,###.##}", value)

A more complex example from String Formatting in C#:

String.Format("{0:$#,##0.00;($#,##0.00);Zero}", value);

This will output “$1,240.00" if passed 1243.50. It will output the same format but in parentheses if the number is negative, and will output the string “Zero” if the number is zero.

Shell script variable not empty (-z option)

I think this is the syntax you are looking for:

if [ -z != $errorstatus ] 

How do I get information about an index and table owner in Oracle?

The following helped me as I didn't have DBA access and also wanted the column names.


select ind.table_owner || '.' || ind.table_name as "TABLE",
       LISTAGG(ind_col.column_name, ',')
            WITHIN GROUP(order by ind_col.column_position) as columns,
from sys.all_indexes ind
join sys.all_ind_columns ind_col
           on ind.owner = ind_col.index_owner
           and ind.index_name = ind_col.index_name
where ind.table_owner not in ('ANONYMOUS','CTXSYS','DBSNMP','EXFSYS',
    -- AND ind.table_name='TableNameGoesHereIfYouWantASpecificTable'
group by ind.table_owner,
order by ind.table_owner,

Is it possible to install iOS 6 SDK on Xcode 5?

Find and download old SDK. Older SDKs are found here.

I have copied the directory as

Now you can test and debug in both xcode versions. You have to run them from the corresponding folders or create shortcuts in your desktop. When building from command line give the parameter as iPhoneOS6.1 instead of iPhoneOS7.0

This worked great for me in Xcode5 and iOS.

Go to into Xcode5's SDK dir. Its usually located at:


Add a symbolic link to the old SDK like this:

sudo ln -s /Applications/ iPhoneOS6.1.sdk

Or more accurately from anywhere in the command line,

sudo ln -s /Applications/  /Applications/

Add an element to an array in Swift

In Swift 4.1 and Xcode 9.4.1

We can add objects to Array basically in Two ways

let stringOne = "One"
let strigTwo = "Two"
let stringThree = "Three"
var array:[String] = []//If your array is string type

Type 1)

//To append elements at the end

Type 2)

//To add elements at specific index
array.insert(strigTwo, at: 1)

If you want to add two arrays

var array1 = [1,2,3,4,5]
let array2 = [6,7,8,9]

let array3 = array1+array2
array1.append(contentsOf: array2)

Find the most frequent number in a NumPy array

Also if you want to get most frequent value(positive or negative) without loading any modules you can use the following code:

lVals = [1,2,3,1,2,1,1,1,3,2,2,1]
print max(map(lambda val: (lVals.count(val), val), set(lVals)))

Typescript: TS7006: Parameter 'xxx' implicitly has an 'any' type

I encounted this error and found that it was because the "strict" parameter was set to true in the tsconfig.json file. Just set it "false" (obviously). In my case I had generated the tsconfig file from the cmd prompt and simply missed the "strict" parameter, which was located further down in the file.

Countdown timer using Moment js

I thought I'd throw this out there too (no plugins). It counts down for 10 seconds into the future.

    var countDownDate = moment().add(10, 'seconds');_x000D_
      var x = setInterval(function() {_x000D_
        diff = countDownDate.diff(moment());_x000D_
        if (diff <= 0) {_x000D_
           // If the count down is finished, write some text _x000D_
        } else_x000D_
      }, 1000);
<script src=""></script>_x000D_
<script src=""></script>_x000D_
<div class="countdown"></div>

ReDim Preserve to a Multi-Dimensional Array in Visual Basic 6

I haven't tested every single one of these answers but you don't need to use complicated functions to accomplish this. It's so much easier than that! My code below will work in any office VBA application (Word, Access, Excel, Outlook, etc.) and is very simple. Hope this helps:

''Dimension 2 Arrays
Dim InnerArray(1 To 3) As Variant ''The inner is for storing each column value of the current row
Dim OuterArray() As Variant ''The outer is for storing each row in
Dim i As Byte

    i = 1
    Do While i <= 5

        ''Enlarging our outer array to store a/another row
        ReDim Preserve OuterArray(1 To i)

        ''Loading the current row column data in
        InnerArray(1) = "My First Column in Row " & i
        InnerArray(2) = "My Second Column in Row " & i
        InnerArray(3) = "My Third Column in Row " & i

        ''Loading the entire row into our array
        OuterArray(i) = InnerArray

        i = i + 1

    ''Example print out of the array to the Intermediate Window
    Debug.Print OuterArray(1)(1)
    Debug.Print OuterArray(1)(2)
    Debug.Print OuterArray(2)(1)
    Debug.Print OuterArray(2)(2)

What is the fastest/most efficient way to find the highest set bit (msb) in an integer in C?

Expanding on Josh's benchmark... one can improve the clz as follows

/***************** clz2 ********************/

#define NUM_OF_HIGHESTBITclz2(a) ((a)                              \
                  ? (((1U) << (sizeof(unsigned)*8-1)) >> __builtin_clz(a)) \
                  : 0)

Regarding the asm: note that there are bsr and bsrl (this is the "long" version). the normal one might be a bit faster.

Align HTML input fields by :

I have just given width to Label and input type were aligned automatically.

input[type="text"] {_x000D_
 background-color: lightblue;_x000D_
border:2px dotted black;_x000D_
font-family:AR CENA;_x000D_
<label>First Name:</label><input type="text" name="fname"><br>_x000D_
<label>Last Name:</label><input type="text" name="lname"><br>

Can you force Vue.js to reload/re-render?

using v-if directive

<div v-if="trulyvalue">
    <component-here />

So simply by changing the value of trulyvalue from false to true will cause the component between the div to rerender again

Public free web services for testing soap client

There is a bunch on here:

Just google for "Free WebService" or "Open WebService" and you'll find tons of open SOAP endpoints.

Remember, you can get a WSDL from any ASMX endpoint by adding ?WSDL to the url.

Apply .gitignore on an existing repository already tracking large number of files

  1. Create a .gitignore file, so to do that, you just create any blank .txt file.

  2. Then you have to change its name writing the following line on the cmd (where git.txt is the name of the file you've just created):

    rename git.txt .gitignore

  3. Then you can open the file and write all the untracked files you want to ignore for good. For example, mine looks like this:


OS junk files

#Visual Studio files


#Project files

#Subversion files

# Office Temp Files

There's a whole collection of useful .gitignore files by GitHub

  1. Once you have this, you need to add it to your git repository just like any other file, only it has to be in the root of the repository.

  2. Then in your terminal you have to write the following line:

    git config --global core.excludesfile ~/.gitignore_global

From oficial doc:

You can also create a global .gitignore file, which is a list of rules for ignoring files in every Git repository on your computer. For example, you might create the file at ~/.gitignore_global and add some rules to it.

Open Terminal. Run the following command in your terminal: git config --global core.excludesfile ~/.gitignore_global

If the respository already exists then you have to run these commands:

git rm -r --cached .
git add .
git commit -m ".gitignore is now working"

If the step 2 doesn´t work then you should write the hole route of the files that you would like to add.

How to set image for bar button with swift?

Initialize barbuttonItem like following:

let pauseButton = UIBarButtonItem(image: UIImage(named: "big"),
                                  style: .plain,
                                  target: self,
                                  action: #selector(PlaybackViewController.pause))

How to append one DataTable to another DataTable

The datatype in the same columns name must be equals.


After that the result is:

dataTable1 = dataTable1 + dataTable2

Keyboard shortcut to clear cell output in Jupyter notebook

Add following at start of cell and run it:

from IPython.display import clear_output

Row count where data exists

lastrow = Sheet1.Range("A#").End(xlDown).Row

This is more easy to determine the row count.
Make sure you declare the right variable when it comes to larger rows.
By the way the '#' sign must be a number where you want to start the row count.

PadLeft function in T-SQL

More efficient way is :

Select id, LEN(id)
From TableA
Order by 2,1 

The result :

Find an object in SQL Server (cross-database)

    ,schema_name(o.schema_id) AS SchemaName, OBJECT_NAME(o.parent_object_id) as TableName
FROM sys.objects o
WHERE o.is_ms_shipped = 0
    AND o.NAME LIKE '%UniqueID%'

Java, return if trimmed String in List contains String

You may be able to use an approximate string matching library to do this, e.g. SecondString, but that is almost certainly overkill - just use one of the for-loop answers provided instead.

How to make promises work in IE11

If you want this type of code to run in IE11 (which does not support much of ES6 at all), then you need to get a 3rd party promise library (like Bluebird), include that library and change your coding to use ES5 coding structures (no arrow functions, no let, etc...) so you can live within the limits of what older browsers support.

Or, you can use a transpiler (like Babel) to convert your ES6 code to ES5 code that will work in older browsers.

Here's a version of your code written in ES5 syntax with the Bluebird promise library:

<script src=""></script>


'use strict';

var promise = new Promise(function(resolve) {
    setTimeout(function() {
    }, 1000);

promise.then(function(result) {
    alert("Fulfilled: " + result);
}, function(error) {
    alert("Rejected: " + error);


How much overhead does SSL impose?

Assuming you don't count connection set-up (as you indicated in your update), it strongly depends on the cipher chosen. Network overhead (in terms of bandwidth) will be negligible. CPU overhead will be dominated by cryptography. On my mobile Core i5, I can encrypt around 250 MB per second with RC4 on a single core. (RC4 is what you should choose for maximum performance.) AES is slower, providing "only" around 50 MB/s. So, if you choose correct ciphers, you won't manage to keep a single current core busy with the crypto overhead even if you have a fully utilized 1 Gbit line. [Edit: RC4 should not be used because it is no longer secure. However, AES hardware support is now present in many CPUs, which makes AES encryption really fast on such platforms.]

Connection establishment, however, is different. Depending on the implementation (e.g. support for TLS false start), it will add round-trips, which can cause noticable delays. Additionally, expensive crypto takes place on the first connection establishment (above-mentioned CPU could only accept 14 connections per core per second if you foolishly used 4096-bit keys and 100 if you use 2048-bit keys). On subsequent connections, previous sessions are often reused, avoiding the expensive crypto.

So, to summarize:

Transfer on established connection:

  • Delay: nearly none
  • CPU: negligible
  • Bandwidth: negligible

First connection establishment:

  • Delay: additional round-trips
  • Bandwidth: several kilobytes (certificates)
  • CPU on client: medium
  • CPU on server: high

Subsequent connection establishments:

  • Delay: additional round-trip (not sure if one or multiple, may be implementation-dependant)
  • Bandwidth: negligible
  • CPU: nearly none

Running a script inside a docker container using shell script

Assuming that your docker container is up and running, you can run commands as:

docker exec mycontainer /bin/sh -c "cmd1;cmd2;...;cmdn"

How do you pass a function as a parameter in C?

This question already has the answer for defining function pointers, however they can get very messy, especially if you are going to be passing them around your application. To avoid this unpleasantness I would recommend that you typedef the function pointer into something more readable. For example.

typedef void (*functiontype)();

Declares a function that returns void and takes no arguments. To create a function pointer to this type you can now do:

void dosomething() { }

functiontype func = &dosomething;

For a function that returns an int and takes a char you would do

typedef int (*functiontype2)(char);

and to use it

int dosomethingwithchar(char a) { return 1; }

functiontype2 func2 = &dosomethingwithchar
int result = func2('a');

There are libraries that can help with turning function pointers into nice readable types. The boost function library is great and is well worth the effort!

boost::function<int (char a)> functiontype2;

is so much nicer than the above.

Programmatically close aspx page from code behind

You should inject a startup script that will close the page after the postback has finished.

ClientScript.RegisterStartupScript(typeof(Page), "closePage", "<script type='text/JavaScript'>window.close();</script>"); 

Why doesn't java.util.Set have get(int index)?

Set is an interface and some of its implementation classes are HashSet, TreeSet and LinkedHashSet. It uses HashMap under the hood to store values. Because HashMap does not preserve the order, it is not possible to get value by index.

You now must be thinking how Set is using HashMap since HashMap stores a key, value pair but the Set does not. valid question. when you add an element in Set, internally, it maintains a HashMap where the key is the element you want to enter in Set and the value is the dummy constant. Below is an internal implementation of add function. Hence, all the keys in the HashMap will have the same constant value.

// Dummy value to associate with an Object in the backing Map
private static final Object PRESENT = new Object();

public boolean add(E e) {
    return map.put(e, PRESENT)==null;

In Ruby, how do I skip a loop in a .each loop, similar to 'continue'

next - it's like return, but for blocks! (So you can use this in any proc/lambda too.)

That means you can also say next n to "return" n from the block. For instance:

puts [1, 2, 3].map do |e|
  next 42 if e == 2

This will yield 46.

Note that return always returns from the closest def, and never a block; if there's no surrounding def, returning is an error.

Using return from within a block intentionally can be confusing. For instance:

def my_fun
  [1, 2, 3].map do |e|
    return "Hello." if e == 2

my_fun will result in "Hello.", not [1, "Hello.", 2], because the return keyword pertains to the outer def, not the inner block.

List to array conversion to use ravel() function

I wanted a way to do this without using an extra module. First turn list to string, then append to an array:

dataset_list = ''.join(input_list)
dataset_array = []
for item in dataset_list.split(';'): # comma, or other

Code for download video from Youtube on Java, Android

3 steps:

  1. Check the sorce code (HTML) of YouTube, you'll get the link like this ( ...);

  2. Decode the url (remove the codes %2B,%25 etc), create a decoder with the codes: and use the function Uri.decode(url) to replace invalid escaped octets;

  3. Use the code to download stream:

    URL u = null;
    InputStream is = null;  
    try {
        u = new URL(url);
        is = u.openStream(); 
        HttpURLConnection huc = (HttpURLConnection)u.openConnection(); //to know the size of video
        int size = huc.getContentLength();                 
        if(huc != null) {
            String fileName = "FILE.mp4";
            String storagePath = Environment.getExternalStorageDirectory().toString();
            File f = new File(storagePath,fileName);
            FileOutputStream fos = new FileOutputStream(f);
            byte[] buffer = new byte[1024];
            int len1 = 0;
            if(is != null) {
                while ((len1 = > 0) {
                    fos.write(buffer,0, len1);  
            if(fos != null) {
    } catch (MalformedURLException mue) {
    } catch (IOException ioe) {
    } finally {
        try {               
            if(is != null) {
        } catch (IOException ioe) {
            // just going to ignore this one

That's all, most of stuff you'll find on the web!!!

Batch file to split .csv file

This will give you lines 1 to 20000 in newfile1.csv
and lines 20001 to the end in file newfile2.csv

It overcomes the 8K character limit per line too.

This uses a helper batch file called findrepl.bat from -

Place findrepl.bat in the same folder as the batch file or on the path.

It's more robust than a plain batch file, and quicker too.

findrepl /o:1:20000 <file.csv >newfile1.csv
findrepl /o:20001   <file.csv >newfile2.csv

How do I use reflection to call a generic method?

Just an addition to the original answer. While this will work:

MethodInfo method = typeof(Sample).GetMethod("GenericMethod");
MethodInfo generic = method.MakeGenericMethod(myType);
generic.Invoke(this, null);

It is also a little dangerous in that you lose compile-time check for GenericMethod. If you later do a refactoring and rename GenericMethod, this code won't notice and will fail at run time. Also, if there is any post-processing of the assembly (for example obfuscating or removing unused methods/classes) this code might break too.

So, if you know the method you are linking to at compile time, and this isn't called millions of times so overhead doesn't matter, I would change this code to be:

Action<> GenMethod = GenericMethod<int>;  //change int by any base type 
                                          //accepted by GenericMethod
MethodInfo method = this.GetType().GetMethod(GenMethod.Method.Name);
MethodInfo generic = method.MakeGenericMethod(myType);
generic.Invoke(this, null);

While not very pretty, you have a compile time reference to GenericMethod here, and if you refactor, delete or do anything with GenericMethod, this code will keep working, or at least break at compile time (if for example you remove GenericMethod).

Other way to do the same would be to create a new wrapper class, and create it through Activator. I don't know if there is a better way.

Make an html number input always display 2 decimal places

an inline solution combines Groot and Ivaylo suggestions in the format below:


Error message "Linter pylint is not installed"

I had the same problem. Open the cmd and type:

python -m pip install pylint

What is the difference between localStorage, sessionStorage, session and cookies?

OK, LocalStorage as it's called it's local storage for your browsers, it can save up to 10MB, SessionStorage does the same, but as it's name saying, it's session based and will be deleted after closing your browser, also can save less than LocalStorage, like up to 5MB, but Cookies are very tiny data storing in your browser, that can save up 4KB and can be accessed through server or browser both...

I also created the image below to show the differences at a glance:

LocalStorage, SessionStorage and Cookies

Multiline input form field using Bootstrap

I think the problem is that you are using type="text" instead of textarea. What you want is:

<textarea class="span6" rows="3" placeholder="What's up?" required></textarea>

To clarify, a type="text" will always be one row, where-as a textarea can be multiple.

jQuery SVG vs. Raphael

As a Javascript beginner, I found Rapahel samples not so easy, I recommend, which is a real Step by step tutorial.

How can I replace a newline (\n) using sed?

Fast answer

sed ':a;N;$!ba;s/\n/ /g' file
  1. :a create a label 'a'
  2. N append the next line to the pattern space
  3. $! if not the last line, ba branch (go to) label 'a'
  4. s substitute, /\n/ regex for new line, / / by a space, /g global match (as many times as it can)

sed will loop through step 1 to 3 until it reach the last line, getting all lines fit in the pattern space where sed will substitute all \n characters


All alternatives, unlike sed will not need to reach the last line to begin the process

with bash, slow

while read line; do printf "%s" "$line "; done < file

with perl, sed-like speed

perl -p -e 's/\n/ /' file

with tr, faster than sed, can replace by one character only

tr '\n' ' ' < file

with paste, tr-like speed, can replace by one character only

paste -s -d ' ' file

with awk, tr-like speed

awk 1 ORS=' ' file

Other alternative like "echo $(< file)" is slow, works only on small files and needs to process the whole file to begin the process.

Long answer from the sed FAQ 5.10

5.10. Why can't I match or delete a newline using the \n escape
sequence? Why can't I match 2 or more lines using \n?

The \n will never match the newline at the end-of-line because the
newline is always stripped off before the line is placed into the
pattern space. To get 2 or more lines into the pattern space, use
the 'N' command or something similar (such as 'H;...;g;').

Sed works like this: sed reads one line at a time, chops off the
terminating newline, puts what is left into the pattern space where
the sed script can address or change it, and when the pattern space
is printed, appends a newline to stdout (or to a file). If the
pattern space is entirely or partially deleted with 'd' or 'D', the
newline is not added in such cases. Thus, scripts like

  sed 's/\n//' file       # to delete newlines from each line             
  sed 's/\n/foo\n/' file  # to add a word to the end of each line         

will NEVER work, because the trailing newline is removed before
the line is put into the pattern space. To perform the above tasks,
use one of these scripts instead:

  tr -d '\n' < file              # use tr to delete newlines              
  sed ':a;N;$!ba;s/\n//g' file   # GNU sed to delete newlines             
  sed 's/$/ foo/' file           # add "foo" to end of each line          

Since versions of sed other than GNU sed have limits to the size of
the pattern buffer, the Unix 'tr' utility is to be preferred here.
If the last line of the file contains a newline, GNU sed will add
that newline to the output but delete all others, whereas tr will
delete all newlines.

To match a block of two or more lines, there are 3 basic choices:
(1) use the 'N' command to add the Next line to the pattern space;
(2) use the 'H' command at least twice to append the current line
to the Hold space, and then retrieve the lines from the hold space
with x, g, or G; or (3) use address ranges (see section 3.3, above)
to match lines between two specified addresses.

Choices (1) and (2) will put an \n into the pattern space, where it
can be addressed as desired ('s/ABC\nXYZ/alphabet/g'). One example
of using 'N' to delete a block of lines appears in section 4.13
("How do I delete a block of specific consecutive lines?"). This
example can be modified by changing the delete command to something
else, like 'p' (print), 'i' (insert), 'c' (change), 'a' (append),
or 's' (substitute).

Choice (3) will not put an \n into the pattern space, but it does
match a block of consecutive lines, so it may be that you don't
even need the \n to find what you're looking for. Since GNU sed
version 3.02.80 now supports this syntax:

  sed '/start/,+4d'  # to delete "start" plus the next 4 lines,           

in addition to the traditional '/from here/,/to there/{...}' range
addresses, it may be possible to avoid the use of \n entirely.

How can I simulate an array variable in MySQL?

I'm surprised none of the answers mention ELT/FIELD.

ELT/FIELD works very similar to an array especially if you have static data.

FIND_IN_SET also works similar but doesn't have a built in complementary function but it's easy enough to write one.

mysql> select elt(2,'AA','BB','CC');
| elt(2,'AA','BB','CC') |
| BB                    |
1 row in set (0.00 sec)

mysql> select field('BB','AA','BB','CC');
| field('BB','AA','BB','CC') |
|                          2 |
1 row in set (0.00 sec)

mysql> select find_in_set('BB','AA,BB,CC');
| find_in_set('BB','AA,BB,CC') |
|                            2 |
1 row in set (0.00 sec)

| BB                                                        |
1 row in set (0.01 sec)

Circle line-segment collision detection algorithm?

Here is my solution in TypeScript, following the idea that @Mizipzor suggested (using projection):

 * Determines whether a line segment defined by a start and end point intersects with a sphere defined by a center point and a radius
 * @param a the start point of the line segment
 * @param b the end point of the line segment
 * @param c the center point of the sphere
 * @param r the radius of the sphere
export function lineSphereIntersects(
  a: IPoint,
  b: IPoint,
  c: IPoint,
  r: number
): boolean {
  // find the three sides of the triangle formed by the three points
  const ab: number = distance(a, b);
  const ac: number = distance(a, c);
  const bc: number = distance(b, c);

  // check to see if either ends of the line segment are inside of the sphere
  if (ac < r || bc < r) {
    return true;

  // find the angle between the line segment and the center of the sphere
  const numerator: number = Math.pow(ac, 2) + Math.pow(ab, 2) - Math.pow(bc, 2);
  const denominator: number = 2 * ac * ab;
  const cab: number = Math.acos(numerator / denominator);

  // find the distance from the center of the sphere and the line segment
  const cd: number = Math.sin(cab) * ac;

  // if the radius is at least as long as the distance between the center and the line
  if (r >= cd) {
    // find the distance between the line start and the point on the line closest to
    // the center of the sphere
    const ad: number = Math.cos(cab) * ac;
    // intersection occurs when the point on the line closest to the sphere center is
    // no further away than the end of the line
    return ad <= ab;
  return false;

export function distance(a: IPoint, b: IPoint): number {
  return Math.sqrt(
    Math.pow(b.z - a.z, 2) + Math.pow(b.y - a.y, 2) + Math.pow(b.x - a.x, 2)

export interface IPoint {
  x: number;
  y: number;
  z: number;

How to center horizontal table-cell

Just add this class in your css

.column p{

Replace all whitespace with a line break/paragraph mark to make a word list

The portable way to do this is:

sed -e 's/[ \t][ \t]*/\

That's an actual newline between the backslash and the slash-g. Many sed implementations don't know about \n, so you need a literal newline. The backslash before the newline prevents sed from getting upset about the newline. (in sed scripts the commands are normally terminated by newlines)

With GNU sed you can use \n in the substitution, and \s in the regex:

sed -e 's/\s\s*/\n/g'

GNU sed also supports "extended" regular expressions (that's egrep style, not perl-style) if you give it the -r flag, so then you can use +:

sed -r -e 's/\s+/\n/g'

If this is for Linux only, you can probably go with the GNU command, but if you want this to work on systems with a non-GNU sed (eg: BSD, Mac OS-X), you might want to go with the more portable option.

Load CSV file with Spark

Spark 2.0.0+

You can use built-in csv data source directly:
    "some_input_file.csv", header=True, mode="DROPMALFORMED", schema=schema


    .option("header", "true")
    .option("mode", "DROPMALFORMED")

without including any external dependencies.

Spark < 2.0.0:

Instead of manual parsing, which is far from trivial in a general case, I would recommend spark-csv:

Make sure that Spark CSV is included in the path (--packages, --jars, --driver-class-path)

And load your data as follows:

(df = sqlContext
    .option("header", "true")
    .option("inferschema", "true")
    .option("mode", "DROPMALFORMED")

It can handle loading, schema inference, dropping malformed lines and doesn't require passing data from Python to the JVM.


If you know the schema, it is better to avoid schema inference and pass it to DataFrameReader. Assuming you have three columns - integer, double and string:

from pyspark.sql.types import StructType, StructField
from pyspark.sql.types import DoubleType, IntegerType, StringType

schema = StructType([
    StructField("A", IntegerType()),
    StructField("B", DoubleType()),
    StructField("C", StringType())

    .option("header", "true")
    .option("mode", "DROPMALFORMED")

Working with SQL views in Entity Framework Core

Views are not currently supported by Entity Framework Core. See

That said, you can trick EF into using a view by mapping your entity to the view as if it were a table. This approach comes with limitations. e.g. you can't use migrations, you need to manually specific a key for EF to use, and some queries may not work correctly. To get around this last part, you can write SQL queries by hand

context.Images.FromSql("SELECT * FROM dbo.ImageView")

How can I select checkboxes using the Selenium Java WebDriver?

If you want to click on all checkboxes at once, a method like this will do:

private void ClickAllCheckboxes()
    foreach (IWebElement e in driver.FindElements(By.xpath("//input[@type='checkbox']")))

What is the difference between venv, pyvenv, pyenv, virtualenv, virtualenvwrapper, pipenv, etc?

PyPI packages not in the standard library:

  • virtualenv is a very popular tool that creates isolated Python environments for Python libraries. If you're not familiar with this tool, I highly recommend learning it, as it is a very useful tool, and I'll be making comparisons to it for the rest of this answer.

    It works by installing a bunch of files in a directory (eg: env/), and then modifying the PATH environment variable to prefix it with a custom bin directory (eg: env/bin/). An exact copy of the python or python3 binary is placed in this directory, but Python is programmed to look for libraries relative to its path first, in the environment directory. It's not part of Python's standard library, but is officially blessed by the PyPA (Python Packaging Authority). Once activated, you can install packages in the virtual environment using pip.

  • pyenv is used to isolate Python versions. For example, you may want to test your code against Python 2.7, 3.6, 3.7 and 3.8, so you'll need a way to switch between them. Once activated, it prefixes the PATH environment variable with ~/.pyenv/shims, where there are special files matching the Python commands (python, pip). These are not copies of the Python-shipped commands; they are special scripts that decide on the fly which version of Python to run based on the PYENV_VERSION environment variable, or the .python-version file, or the ~/.pyenv/version file. pyenv also makes the process of downloading and installing multiple Python versions easier, using the command pyenv install.

  • pyenv-virtualenv is a plugin for pyenv by the same author as pyenv, to allow you to use pyenv and virtualenv at the same time conveniently. However, if you're using Python 3.3 or later, pyenv-virtualenv will try to run python -m venv if it is available, instead of virtualenv. You can use virtualenv and pyenv together without pyenv-virtualenv, if you don't want the convenience features.

  • virtualenvwrapper is a set of extensions to virtualenv (see docs). It gives you commands like mkvirtualenv, lssitepackages, and especially workon for switching between different virtualenv directories. This tool is especially useful if you want multiple virtualenv directories.

  • pyenv-virtualenvwrapper is a plugin for pyenv by the same author as pyenv, to conveniently integrate virtualenvwrapper into pyenv.

  • pipenv aims to combine Pipfile, pip and virtualenv into one command on the command-line. The virtualenv directory typically gets placed in ~/.local/share/virtualenvs/XXX, with XXX being a hash of the path of the project directory. This is different from virtualenv, where the directory is typically in the current working directory. pipenv is meant to be used when developing Python applications (as opposed to libraries). There are alternatives to pipenv, such as poetry, which I won't list here since this question is only about the packages that are similarly named.

Standard library:

  • pyvenv is a script shipped with Python 3 but deprecated in Python 3.6 as it had problems (not to mention the confusing name). In Python 3.6+, the exact equivalent is python3 -m venv.

  • venv is a package shipped with Python 3, which you can run using python3 -m venv (although for some reason some distros separate it out into a separate distro package, such as python3-venv on Ubuntu/Debian). It serves the same purpose as virtualenv, but only has a subset of its features (see a comparison here). virtualenv continues to be more popular than venv, especially since the former supports both Python 2 and 3.

Recommendation for beginners:

This is my personal recommendation for beginners: start by learning virtualenv and pip, tools which work with both Python 2 and 3 and in a variety of situations, and pick up other tools once you start needing them.

Show Console in Windows Application?

What you want to do is not possible in a sane way. There was a similar question so look at the answers.

Then there's also an insane approach (site down - backup available here.) written by Jeffrey Knight:

Question: How do I create an application that can run in either GUI (windows) mode or command line / console mode?

On the surface of it, this would seem easy: you create a Console application, add a windows form to it, and you're off and running. However, there's a problem:

Problem: If you run in GUI mode, you end up with both a window and a pesky console lurking in the background, and you don't have any way to hide it.

What people seem to want is a true amphibian application that can run smoothly in either mode.

If you break it down, there are actually four use cases here:

User starts application from existing cmd window, and runs in GUI mode
User double clicks to start application, and runs in GUI mode
User starts application from existing cmd window, and runs in command mode
User double clicks to start application, and runs in command mode.

I'm posting the code to do this, but with a caveat.

I actually think this sort of approach will run you into a lot more trouble down the road than it's worth. For example, you'll have to have two different UIs' -- one for the GUI and one for the command / shell. You're going to have to build some strange central logic engine that abstracts from GUI vs. command line, and it's just going to get weird. If it were me, I'd step back and think about how this will be used in practice, and whether this sort of mode-switching is worth the work. Thus, unless some special case called for it, I wouldn't use this code myself, because as soon as I run into situations where I need API calls to get something done, I tend to stop and ask myself "am I overcomplicating things?".

Output type=Windows Application

using System;
using System.Collections.Generic;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Diagnostics;
using Microsoft.Win32;

namespace WindowsApplication
    static class Program
    DEMO CODE ONLY: In general, this approach calls for re-thinking 
    your architecture!
    There are 4 possible ways this can run:
    1) User starts application from existing cmd window, and runs in GUI mode
    2) User double clicks to start application, and runs in GUI mode
    3) User starts applicaiton from existing cmd window, and runs in command mode
    4) User double clicks to start application, and runs in command mode.

    To run in console mode, start a cmd shell and enter:
        c:\path\to\Debug\dir\WindowsApplication.exe console
        To run in gui mode,  EITHER just double click the exe, OR start it from the cmd prompt with:
        c:\path\to\Debug\dir\WindowsApplication.exe (or pass the "gui" argument).
        To start in command mode from a double click, change the default below to "console".
    In practice, I'm not even sure how the console vs gui mode distinction would be made from a
    double click...
        string mode = args.Length > 0 ? args[0] : "console"; //default to console

        [DllImport("kernel32.dll", SetLastError = true)]
        static extern bool AllocConsole();

        [DllImport("kernel32.dll", SetLastError = true)]
        static extern bool FreeConsole();

        [DllImport("kernel32", SetLastError = true)]
        static extern bool AttachConsole(int dwProcessId);

        static extern IntPtr GetForegroundWindow();

        [DllImport("user32.dll", SetLastError = true)]
        static extern uint GetWindowThreadProcessId(IntPtr hWnd, out int lpdwProcessId);

        static void Main(string[] args)
            //TODO: better handling of command args, (handle help (--help /?) etc.)
            string mode = args.Length > 0 ? args[0] : "gui"; //default to gui

            if (mode == "gui")
                MessageBox.Show("Welcome to GUI mode");



                Application.Run(new Form1());
            else if (mode == "console")

                //Get a pointer to the forground window.  The idea here is that
                //IF the user is starting our application from an existing console
                //shell, that shell will be the uppermost window.  We'll get it
                //and attach to it
                IntPtr ptr = GetForegroundWindow();

                int  u;

                GetWindowThreadProcessId(ptr, out u);

                Process process = Process.GetProcessById(u);

                if (process.ProcessName == "cmd" )    //Is the uppermost window a cmd process?

                    //we have a console to attach to ..
                    Console.WriteLine("hello. It looks like you started me from an existing console.");
                    //no console AND we're in console mode ... create a new console.


                    Console.WriteLine(@"hello. It looks like you double clicked me to start
                   AND you want console mode.  Here's a new console.");
                    Console.WriteLine("press any key to continue ...");


jQuery .load() call doesn't execute JavaScript in loaded HTML file

Well I had the same problem that only seemed to happen for Firefox, and I couldn't use another JQuery command except for .load() since I was modifying the front-end on exisitng PHP files...

Anyways, after using the .load() command, I embedded my JQuery script within the external HTML that was getting loaded in, and it seemed to work. I don't understand why the JS that I loaded at the top of the main document didn't work for the new content however...

chrome : how to turn off user agent stylesheet settings?

  1. Open Chrome dev tools
  2. Click gear icon on bottom right
  3. In General section, check or uncheck "Show user agent styles".

What does "for" attribute do in HTML <label> tag?

It labels whatever input is the parameter for the for attribute.

<input id='myInput' type='radio'>_x000D_
<label for='myInput'>My 1st Radio Label</label>_x000D_
<input id='input2' type='radio'>_x000D_
<label for='input2'>My 2nd Radio Label</label>_x000D_
<input id='input3' type='radio'>_x000D_
<label for='input3'>My 3rd Radio Label</label>

How to check if a word is an English word with Python?

For a semantic web approach, you could run a sparql query against WordNet in RDF format. Basically just use urllib module to issue GET request and return results in JSON format, parse using python 'json' module. If it's not English word you'll get no results.

As another idea, you could query Wiktionary's API.

Alternative to header("Content-type: text/xml");

Now I see what you are doing. You cannot send output to the screen then change the headers. If you are trying to create an XML file of map marker and download them to display, they should be in separate files.

Take this

function parseToXML($htmlStr)
return $xmlStr;
// Opens a connection to a MySQL server
$connection=mysql_connect (localhost, $username, $password);
if (!$connection) {
  die('Not connected : ' . mysql_error());
// Set the active MySQL database
$db_selected = mysql_select_db($database, $connection);
if (!$db_selected) {
  die ('Can\'t use db : ' . mysql_error());
// Select all the rows in the markers table
$query = "SELECT * FROM markers WHERE 1";
$result = mysql_query($query);
if (!$result) {
  die('Invalid query: ' . mysql_error());
header("Content-type: text/xml");
// Start XML file, echo parent node
echo '<markers>';
// Iterate through the rows, printing XML nodes for each
while ($row = @mysql_fetch_assoc($result)){
  echo '<marker ';
  echo 'name="' . parseToXML($row['name']) . '" ';
  echo 'address="' . parseToXML($row['address']) . '" ';
  echo 'lat="' . $row['lat'] . '" ';
  echo 'lng="' . $row['lng'] . '" ';
  echo 'type="' . $row['type'] . '" ';
  echo '/>';
// End XML file
echo '</markers>';

and place it in phpsqlajax_genxml.php so your javascript can download the XML file. You are trying to do too many things in the same file.

Round button with text and icon in flutter

You can simply use named constructors for creating different types of buttons with icons. For instance

FlatButton.icon(onPressed: null, icon: null, label: null);
RaisedButton.icon(onPressed: null, icon: null, label: null);

But if you have specfic requirements then you can always create custom button with different layouts or simply wrap a widget in GestureDetector.

@font-face not working

Not sure exactly what your problem is, but try the following:

  1. Do the font files exist?
  2. Do you need quotes around the URLs?
  3. Are you using a CSS3-enabled browser?

Check here for examples, if they don't work for you then you have another problem


You have a bunch of repeated declarations in your source, does this work?

@font-face { font-family: Gotham; src: url('../fonts/gothammedium.eot'); }

a { font-family:Gotham,Verdana,Arial; }

jQuery has deprecated synchronous XMLHTTPRequest

My workabout: I use asynchronous requests dumping the code to a buffer. I have a loop checking the buffer every second. When the dump has arrived to the buffer I execute the code. I also use a timeout. For the end user the page works as if synchronous requests would be used.

Python List & for-each access (Find/Replace in built-in list)

Answering this has been good, as the comments have led to an improvement in my own understanding of Python variables.

As noted in the comments, when you loop over a list with something like for member in my_list the member variable is bound to each successive list element. However, re-assigning that variable within the loop doesn't directly affect the list itself. For example, this code won't change the list:

my_list = [1,2,3]
for member in my_list:
    member = 42
print my_list


[1, 2, 3]

If you want to change a list containing immutable types, you need to do something like:

my_list = [1,2,3]
for ndx, member in enumerate(my_list):
    my_list[ndx] += 42
print my_list


[43, 44, 45]

If your list contains mutable objects, you can modify the current member object directly:

class C:
    def __init__(self, n):
        self.num = n
    def __repr__(self):
        return str(self.num)

my_list = [C(i) for i in xrange(3)]
for member in my_list:
    member.num += 42
print my_list

[42, 43, 44]

Note that you are still not changing the list, simply modifying the objects in the list.

You might benefit from reading Naming and Binding.

Android SQLite SELECT Query

Try trimming the string to make sure there is no extra white space:

Cursor c = db.rawQuery("SELECT * FROM tbl1 WHERE TRIM(name) = '"+name.trim()+"'", null);

Also use c.moveToFirst() like @thinksteep mentioned.

This is a complete code for select statements.

SQLiteDatabase db = this.getReadableDatabase();
Cursor c = db.rawQuery("SELECT column1,column2,column3 FROM table ", null);
if (c.moveToFirst()){
    do {
        // Passing values 
        String column1 = c.getString(0);
        String column2 = c.getString(1);
        String column3 = c.getString(2); 
        // Do something Here with values
    } while(c.moveToNext());

Use Excel pivot table as data source for another Pivot Table

I guess your end goal is to show Distinct (unique) values inside your original Pivot table.

For example you could have data set with OrderNumber, OrderDate, OrderItem, orderQty

First pivot table will show you OrderDate and sum of OrderQty and you probably want to see Count of unique orders in the same Pivot. You woudln't be able to do so within standard pivot table

If you want to do it, you would need Office 2016 (or perhaps pover Pivot might work). In office 2016 select your data > Insert > Pivot Table > choose tick "Add this data to the Data Model"

After that, you would be able to select grouping method as Distinct (Count)

How to sum all values in a column in Jaspersoft iReport Designer?

iReports Custom Fields for columns (sum, average, etc)

  1. Right-Click on Variables and click Create Variable

  2. Click on the new variable

    a. Notice the properties on the right

  3. Rename the variable accordingly

  4. Change the Value Class Name to the correct Data Type

    a. You can search by clicking the 3 dots

  5. Select the correct type of calculation

  6. Change the Expression

    a. Click the little icon

    b. Select the column you are looking to do the calculation for

    c. Click finish

  7. Set Initial Value Expression to 0

  8. Set the increment type to none

  9. Leave Incrementer Factory Class Name blank
  10. Set the Reset Type (usually report)

  11. Drag a new Text Field to stage (Usually in Last Page Footer, or Column Footer)

  12. Double Click the new Text Field
  13. Clear the expression “Text Field”
  14. Select the new variable

  15. Click finish

  16. Put the new text in a desirable position ?

Maven Run Project

clean package exec:java -P Class_Containing_Main_Method command is also an option if you have only one Main method(PSVM) in the project, with the following Maven Setup.

Don't forget to mention the class in the <properties></properties> section of pom.xml :



STS Run Configuration along with above Maven Setup:

enter image description here

UnsupportedClassVersionError unsupported major.minor version 51.0 unable to load class

Even though your JDK in eclipse is 1.7, you need to make sure eclipse compilance level also set to 1.7. You can check compilance level--> Window-->Preferences--> Java--Compiler--compilance level.

Unsupported major minor error happens in cases where compilance level doesn't match with runtime.

How to quickly drop a user with existing privileges

The accepted answer resulted in errors for me when attempting REASSIGN OWNED BY or DROP OWNED BY. The following worked for me:

DROP USER username;

The user may have privileges in other schemas, in which case you will have to run the appropriate REVOKE line with "public" replaced by the correct schema. To show all of the schemas and privilege types for a user, I edited the \dp command to make this query:

  n.nspname as "Schema",
  CASE c.relkind 
    WHEN 'r' THEN 'table' 
    WHEN 'v' THEN 'view' 
    WHEN 'm' THEN 'materialized view' 
    WHEN 'S' THEN 'sequence' 
    WHEN 'f' THEN 'foreign table' 
  END as "Type"
FROM pg_catalog.pg_class c
LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHERE pg_catalog.array_to_string(c.relacl, E'\n') LIKE '%username%';

I'm not sure which privilege types correspond to revoking on TABLES, SEQUENCES, or FUNCTIONS, but I think all of them fall under one of the three.

Default fetch type for one-to-one, many-to-one and one-to-many in Hibernate

To answer your question, Hibernate is an implementation of the JPA standard. Hibernate has its own quirks of operation, but as per the Hibernate docs

By default, Hibernate uses lazy select fetching for collections and lazy proxy fetching for single-valued associations. These defaults make sense for most associations in the majority of applications.

So Hibernate will always load any object using a lazy fetching strategy, no matter what type of relationship you have declared. It will use a lazy proxy (which should be uninitialized but not null) for a single object in a one-to-one or many-to-one relationship, and a null collection that it will hydrate with values when you attempt to access it.

It should be understood that Hibernate will only attempt to fill these objects with values when you attempt to access the object, unless you specify fetchType.EAGER.

android pinch zoom

I implemented a pinch zoom for my TextView, using this tutorial. The resulting code is this:

private GestureDetector gestureDetector;
private View.OnTouchListener gestureListener;

and in onCreate():

    // Zoom handlers
    gestureDetector = new GestureDetector(new MyGestureDetector());
    gestureListener = new View.OnTouchListener() {

        // We can be in one of these 2 states
        static final int NONE = 0;
        static final int ZOOM = 1;
        int mode = NONE;

        static final int MIN_FONT_SIZE = 10;
        static final int MAX_FONT_SIZE = 50;

        float oldDist = 1f;

        public boolean onTouch(View v, MotionEvent event) {
            TextView textView = (TextView) findViewById(;

            switch (event.getAction() & MotionEvent.ACTION_MASK) {
                case MotionEvent.ACTION_POINTER_DOWN:
                    oldDist = spacing(event);
                    Log.d(TAG, "oldDist=" + oldDist);
                    if (oldDist > 10f) {
                       mode = ZOOM;
                       Log.d(TAG, "mode=ZOOM" );
                case MotionEvent.ACTION_POINTER_UP:
                    mode = NONE;
                case MotionEvent.ACTION_MOVE:
                    if (mode == ZOOM) {
                        float newDist = spacing(event);
                        // If you want to tweak font scaling, this is the place to go.
                        if (newDist > 10f) {
                            float scale = newDist / oldDist;

                            if (scale > 1) {
                                scale = 1.1f;
                            } else if (scale < 1) {
                                scale = 0.95f;

                            float currentSize = textView.getTextSize() * scale;
                            if ((currentSize < MAX_FONT_SIZE && currentSize > MIN_FONT_SIZE)
                                    ||(currentSize >= MAX_FONT_SIZE && scale < 1)
                                    || (currentSize <= MIN_FONT_SIZE && scale > 1)) {
                                textView.setTextSize(TypedValue.COMPLEX_UNIT_PX, currentSize);
            return false;

Magic constants 1.1 and 0.95 were chosen empirically (using scale variable for this purpose made my TextView behave kind of weird).

Javascript (+) sign concatenates instead of giving sum of variables

Use only:

divID = "question-" + parseInt(i) + 1;

When "n" comes from html input field or is declared as string, you need to use explicit conversion.

var n = "1"; //type is string
var frstCol = 5;
lstCol = frstCol + parseInt(n);

If "n" is integer, don't need conversion.

n = 1; //type is int
var frstCol = 5, lstCol = frstCol + n;

Convert string to variable name in JavaScript

The window['variableName'] method ONLY works if the variable is defined in the global scope. The correct answer is "Refactor". If you can provide an "Object" context then a possible general solution exists, but there are some variables which no global function could resolve based on the scope of the variable.

    var findMe = 'no way';

What's the best way to limit text length of EditText in Android

I have had this problem and I consider we are missing a well explained way of doing this programmatically without losing the already set filters.

Setting the length in XML:

As the accepted answer states correctly, if you want to define a fixed length to an EditText which you won't change further in the future just define in your EditText XML:


Setting the length programmatically

To set the length programmatically you'll need to set it through an InputFilter. But if you create a new InputFilter and set it to the EditText you will lose all the other already defined filters (e.g. maxLines, inputType, etc) which you might have added either through XML or programatically.

So this is WRONG:

editText.setFilters(new InputFilter[] {new InputFilter.LengthFilter(maxLength)});

To avoid losing previously added filters you need to get those filters, add the new one (maxLength in this case), and set the filters back to the EditText as follow:


InputFilter[] editFilters = editText.getFilters();
InputFilter[] newFilters = new InputFilter[editFilters.length + 1];
System.arraycopy(editFilters, 0, newFilters, 0, editFilters.length);
newFilters[editFilters.length] = new InputFilter.LengthFilter(maxLength); 

Kotlin however made it easier for everyone, you also need to add the filter to the already existing ones but you can achieve that with a simple:

editText.filters += InputFilter.LengthFilter(maxLength)

Using Node.JS, how do I read a JSON file into (server) memory?

In Node 8 you can use the built-in util.promisify() to asynchronously read a file like this

const {promisify} = require('util')
const fs = require('fs')
const readFileAsync = promisify(fs.readFile)

readFileAsync(`${__dirname}/my.json`, {encoding: 'utf8'})
  .then(contents => {
    const obj = JSON.parse(contents)
  .catch(error => {
    throw error

Why can't decimal numbers be represented exactly in binary?

BCD - Binary-coded Decimal - representations are exact. They are not very space-efficient, but that's a trade-off you have to make for accuracy in this case.

MySQL CURRENT_TIMESTAMP on create and on update

You cannot have two TIMESTAMP column with the same default value of CURRENT_TIMESTAMP on your table. Please refer to this link:

What is System, out, println in System.out.println() in Java

Whenever you're confused, I would suggest consulting the Javadoc as the first place for your clarification.

From the javadoc about System, here's what the doc says:

public final class System
extends Object

The System class contains several useful class fields and methods. It cannot be instantiated.
Among the facilities provided by the System class are standard input, standard output, and error output streams; access to externally defined properties and environment variables; a means of loading files and libraries; and a utility method for quickly copying a portion of an array.


Regarding System.out

public static final PrintStream out
The "standard" output stream. This stream is already open and ready to accept output data. Typically this stream corresponds to display output or another output destination specified by the host environment or user.
For simple stand-alone Java applications, a typical way to write a line of output data is:


HttpWebRequest using Basic authentication

Try this:

System.Net.CredentialCache credentialCache = new System.Net.CredentialCache(); 
    new System.Uri(""),
    new System.Net.NetworkCredential("username", "password")


httpWebRequest.Credentials = credentialCache; 

Java NoSuchAlgorithmException - SunJSSE,$DefaultSSLContext

I had the similar issue. The problem was in the passwords: the Keystore and private key used different passwords. (KeyStore explorer was used)

After creating Keystore with the same password as private key had the issue was resolved.

Python, print all floats to 2 decimal places in output

Format String Syntax.

from math import pi
var1, var2, var3, var4 = pi, pi*2, pi*3, pi*4
'{:0.2f}, kg={:0.2f}, lb={:0.2f}, gal={:0.2f}'.format(var1, var2, var3, var4)

The output would be:

'3.14, kg=6.28, lb=9.42, gal=12.57'

How to scale images to screen size in Pygame

If you scale 1600x900 to 1280x720 you have

scale_x = 1280.0/1600
scale_y = 720.0/900

Then you can use it to find button size, and button position

button_width  = 300 * scale_x
button_height = 300 * scale_y

button_x = 1440 * scale_x
button_y = 860  * scale_y

If you scale 1280x720 to 1600x900 you have

scale_x = 1600.0/1280
scale_y = 900.0/720

and rest is the same.

I add .0 to value to make float - otherwise scale_x, scale_y will be rounded to integer - in this example to 0 (zero) (Python 2.x)

recursion versus iteration

Most of the answers seem to assume that iterative = for loop. If your for loop is unrestricted (a la C, you can do whatever you want with your loop counter), then that is correct. If it's a real for loop (say as in Python or most functional languages where you cannot manually modify the loop counter), then it is not correct.

All (computable) functions can be implemented both recursively and using while loops (or conditional jumps, which are basically the same thing). If you truly restrict yourself to for loops, you will only get a subset of those functions (the primitive recursive ones, if your elementary operations are reasonable). Granted, it's a pretty large subset which happens to contain every single function you're likely to encouter in practice.

What is much more important is that a lot of functions are very easy to implement recursively and awfully hard to implement iteratively (manually managing your call stack does not count).

What is the difference between Scala's case class and class?

According to Scala's documentation:

Case classes are just regular classes that are:

  • Immutable by default
  • Decomposable through pattern matching
  • Compared by structural equality instead of by reference
  • Succinct to instantiate and operate on

Another feature of the case keyword is the compiler automatically generates several methods for us, including the familiar toString, equals, and hashCode methods in Java.

How to get the public IP address of a user in C#

You can use "HTTP_X_FORWARDED_FOR" or "REMOTE_ADDR" header attribute.

Refer method GetVisitorIPAddress from Machine Syntax blog .

    /// <summary>
    /// method to get Client ip address
    /// </summary>
    /// <param name="GetLan"> set to true if want to get local(LAN) Connected ip address</param>
    /// <returns></returns>
    public static string GetVisitorIPAddress(bool GetLan = false)
        string visitorIPAddress = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];

        if (String.IsNullOrEmpty(visitorIPAddress))
            visitorIPAddress = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];

        if (string.IsNullOrEmpty(visitorIPAddress))
            visitorIPAddress = HttpContext.Current.Request.UserHostAddress;

        if (string.IsNullOrEmpty(visitorIPAddress) || visitorIPAddress.Trim() == "::1")
            GetLan = true;
            visitorIPAddress = string.Empty;

        if (GetLan && string.IsNullOrEmpty(visitorIPAddress))
                //This is for Local(LAN) Connected ID Address
                string stringHostName = Dns.GetHostName();
                //Get Ip Host Entry
                IPHostEntry ipHostEntries = Dns.GetHostEntry(stringHostName);
                //Get Ip Address From The Ip Host Entry Address List
                IPAddress[] arrIpAddress = ipHostEntries.AddressList;

                    visitorIPAddress = arrIpAddress[arrIpAddress.Length - 2].ToString();
                        visitorIPAddress = arrIpAddress[0].ToString();
                            arrIpAddress = Dns.GetHostAddresses(stringHostName);
                            visitorIPAddress = arrIpAddress[0].ToString();
                            visitorIPAddress = "";


        return visitorIPAddress;

How to get xdebug var_dump to show full object/array

I know this is a super old post, but I figured this may still be helpful.

If you're comfortable with reading json format you could replace your var_dump with:

return json_encode($myvar);

I've been using this to help troubleshoot a service I've been building that has some deeply nested arrays. This will return every level of your array without truncating anything or requiring you to change your php.ini file.

Also, because the json_encoded data is a string it means you can write it to the error log easily


It probably isn't the best choice for every situation, but it's a choice!

How do I install Python OpenCV through Conda?

The correct command for installing the current version of OpenCV 3.3 in Anaconda windows:

conda install -c conda-forge opencv


conda install -c conda-forge/label/broken opencv

For 3.2 use this:

conda install -c menpo opencv3

Custom Listview Adapter with filter Android

please check below code it will help you

            .setOnItemClickListener(new OnItemClickListener() {

                public void onItemClick(AdapterView<?> parent, View view,
                        int position, long id) {

                    int pos = position;
                    Intent intent = new Intent(getContext(),
                    intent.putExtra("model", list.get(position));
    return convertView;

public android.widget.Filter getFilter() {

    return new android.widget.Filter() {

        protected void publishResults(CharSequence constraint,
                FilterResults results) {

            ArrayList<UserListModel> updatelist = (ArrayList<UserListModel>) results.values;
            UserListCustomAdaptor newadaptor = new UserListCustomAdaptor(
                    getContext(), getCount(), updatelist);

            if (results.equals(constraint)) {
            if (results.count > 0) {
            } else {


        protected FilterResults performFiltering(CharSequence constraint) {

            FilterResults filterResults = new FilterResults();
            list = new ArrayList<UserListModel>();

            if (constraint != null && DrawerActivity.userlist != null) {

                constraint = constraint.toString().toLowerCase();
                int length = DrawerActivity.userlist.size();
                int i = 0;
                while (i < length) {

                    UserListModel modelobj = DrawerActivity.userlist.get(i);
                    String data = modelobj.getFirstName() + " "
                            + modelobj.getLastName();
                    if (data.toLowerCase().contains(constraint.toString())) {

                filterResults.values = list;
                filterResults.count = list.size();
            return filterResults;

public int getCount() {
    return list.size();

public UserListModel getItem(int position) {

    return list.get(position);

Checking if a worksheet-based checkbox is checked

Building on the previous answers, you can leverage the fact that True is -1 and False is 0 and shorten your code like this:

Sub Button167_Click()
  Range("Y12").Value = _
    Abs(Worksheets(1).Shapes("Check Box 1").OLEFormat.Object.Value > 0)
End Sub

If the checkbox is checked, .Value = 1.

Worksheets(1).Shapes("Check Box 1").OLEFormat.Object.Value > 0 returns True.

Applying the Abs function converts True to 1.

If the checkbox is unchecked, .Value = -4146.

Worksheets(1).Shapes("Check Box 1").OLEFormat.Object.Value > 0 returns False.

Applying the Abs function converts False to 0.

Parsing JSON Object in Java

Thank you so much to @Code in another answer. I can read any JSON file thanks to your code. Now, I'm trying to organize all the elements by levels, for could use them!

I was working with Android reading a JSON from an URL and the only I had to change was the lines

Set<Object> set = jsonObject.keySet(); Iterator<Object> iterator = set.iterator();


Iterator<?> iterator = jsonObject.keys();

I share my implementation, to help someone:

public void parseJson(JSONObject jsonObject) throws ParseException, JSONException {

    Iterator<?> iterator = jsonObject.keys();
    while (iterator.hasNext()) {
        String obj =;

        if (jsonObject.get(obj) instanceof JSONArray) {
            //Toast.makeText(MainActivity.this, "Objeto: JSONArray", Toast.LENGTH_SHORT).show();
            TextView txtView = new TextView(this);
        } else {
            if (jsonObject.get(obj) instanceof JSONObject) {
                //Toast.makeText(MainActivity.this, "Objeto: JSONObject", Toast.LENGTH_SHORT).show();
                parseJson((JSONObject) jsonObject.get(obj));
            } else {
                //Toast.makeText(MainActivity.this, "Objeto: Value", Toast.LENGTH_SHORT).show();
                //System.out.println(obj.toString() + "\t"+ jsonObject.get(obj));
                TextView txtView = new TextView(this);
                txtView.setText(obj.toString() + "\t"+ jsonObject.get(obj));

Deserialize a json string to an object in python

Another way is to simply pass the json string as a dict to the constructor of your object. For example your object is:

class Payload(object):
    def __init__(self, action, method, data, *args, **kwargs):
        self.action = action
        self.method = method = data

And the following two lines of python code will construct it:

j = json.loads(yourJsonString)
payload = Payload(**j)

Basically, we first create a generic json object from the json string. Then, we pass the generic json object as a dict to the constructor of the Payload class. The constructor of Payload class interprets the dict as keyword arguments and sets all the appropriate fields.

Java, How to add library files in netbeans?

How to import a commons-library into netbeans.

  1. Evaluate the error message in NetBeans:

    java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory
  2. NoClassDeffFoundError means somewhere under the hood in the code you used, a method called another method which invoked a class that cannot be found. So what that means is your code did this: MyFoobarClass foobar = new MyFoobarClass() and the compiler is confused because nowhere is defined this MyFoobarClass. This is why you get an error.

  3. To know what to do next, you have to look at the error message closely. The words 'org/apache/commons' lets you know that this is the codebase that provides the tools you need. You have a choice, either you can import EVERYTHING in apache commons, or you could import JUST the LogFactory class, or you could do something in between. Like for example just get the logging bit of apache commons.

  4. You'll want to go the middle of the road and get commons-logging. Excellent choice, fire up the google and search for apache commons-logging. The first link takes you to Go to downloads. There you will find the most up-to-date ones. If your project was compiled under ancient versions of commons-logging, then use those same ancient ones because if you use the newer ones, the code may fail because the newer versions are different.

  5. You're going to want to download the or something to that effect. Read what the name is saying. The .zip means it's a compressed file. commons-logging means that this one should contain the LogFactory class you desire. the middle 1.1.3 means that is the version. if you are compiling for an old version, you'll need to match these up, or else you risk the code not compiling right due to changes due to upgrading.

  6. Download that zip. Unzip it. Search around for things that end in .jar. In netbeans right click your project, click properties, click libraries, click "add jar/folder" and import those jars. Save the project, and re-run, and the errors should be gone.

The binaries don't include the source code, so you won't be able to drill down and see what is happening when you debug. As programmers you should be downloading "the source" of apache commons and compiling from source, generating the jars yourself and importing those for experience. You should be smart enough to understand and correct the source code you are importing. These ancient versions of apache commons might have been compiled under an older version of Java, so if you go too far back, they may not even compile unless you compile them under an ancient version of java.

How to use moment.js library in angular 2 typescript app?

The following worked for me.

First, install the type definitions for moment.

typings install moment --save

(Note: NOT --ambient)

Then, to work around the lack of a proper export:

import * as moment from 'moment';

How can I format the output of a bash command in neat columns

If your output is delimited by tabs a quick solution would be to use the tabs command to adjust the size of your tabs.

tabs 20
keys | awk '{ print $1"\t\t" $2 }'

Using curl POST with variables defined in bash script functions

Here's what actually worked for me, after guidance from answers here:

export BASH_VARIABLE="[1,2,3]"
curl http://localhost:8080/path -d "$(cat <<EOF
  "name": $BASH_VARIABLE,
  "something": [
)" -H 'Content-Type: application/json'

Git Stash vs Shelve in IntelliJ IDEA

I would prefer to shelve changes instead of stashing them if I am not sharing my changes elsewhere.

Stashing is a git feature and doesn't give you the option to select specific files or changes inside a file. Shelving can do that but this is an IDE-specific feature, not a git feature:

enter image description here

As you can see I am able to choose to specify which files/lines to include on my shelve. Note that I can't do that with stashing.

Beware using shelves in the IDE may limit the portability of your patches because those changes are not stored in a .git folder.

Some helpful links:

The permissions granted to user ' are insufficient for performing this operation. (rsAccessDenied)"}

I know it's for a long time ago but you (or any other new comers) can resolve this issue by

  1. Add the [Domain\User] to Administrator, IISUser, SQLReportingUser groups
  2. Delete Encryption Key in SSRS configuration tools
  3. ReRun the Database Change in SSRS configuration tools
  4. Open WebServiceUrl from SSRS configuration tools (http://localhost/reportserver)
  5. creating Reports Folder manually
  6. go to Properties of created folder and add these roles to security (builtin\users , builtin\Administrator, domain\user)
  7. Deploy your reports and your problem resolved

ValueError: Wrong number of items passed - Meaning and suggestions?

for i in range(100):
  #Your code here

This one worked for me.

How to create a file in Ruby

You can also use constants instead of strings to specify the mode you want. The benefit is if you make a typo in a constant name, your program will raise an runtime exception.

The constants are File::RDONLY or File::WRONLY or File::CREAT. You can also combine them if you like.

Full description of file open modes on

Unresolved Import Issues with PyDev and Eclipse

I'm running Eclipse 4.2.0 (Juno) and PyDev 2.8.1, and ran into this problem with a lib installed to my site-packages path. According to this SO question:

Pydev and *.pyc Files

...there is an issue with PyDev and pyc files. In the case of the particular lib I tried to reference, all that is delivered is pyc files.

Here's what I did to address this:

  1. Install uncompyle2 from
  2. Run uncompyle2 against the *.pyc files in the site-packages lib. Example:

    uncompyle2 -r -o /tmp /path/to/site-packages/lib

  3. Rename the resulting *.pyc_dis files produced from uncompyle2 to *.py
  4. Move / copy these *.py files to the site-packages path
  5. In Eclipse, select File > Restart

The unresolved import error relating to .pyc files should now disappear.

Trigger event on body load complete js/jquery


  $(document).ready(function() {


what you are looking for?

How to connect to a MS Access file (mdb) using C#?

Another simplest way to connect is through an OdbcConnection using App.config file like this

    <add key="Conn" value="Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|MyDB.mdb;Persist Security Info=True"/>

MyDB.mdb is my database file and it is present in current primary application folder with main exe file.

if your mdf file has password then use like this

    <add key="Conn" value="Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|MyDB.mdb;Persist Security Info=True;Jet OLEDB:Database Password=Admin$@123"/>

Moment JS - check if a date is today or in the future

i wanted it for something else but eventually found a trick which you can try

somedate.calendar(compareDate, { sameDay: '[Today]'})=='Today'

var d = moment();_x000D_
 var today = moment();_x000D_
 console.log("Usign today's date, is Date is Today? ",d.calendar(today, {_x000D_
    sameDay: '[Today]'})=='Today');_x000D_
 var someRondomDate = moment("2012/07/13","YYYY/MM/DD");_x000D_
 console.log("Usign Some Random Date, is Today ?",someRondomDate.calendar(today, {_x000D_
    sameDay: '[Today]'})=='Today');_x000D_
 var anotherRandomDate =  moment("2012/07/13","YYYY/MM/DD");_x000D_
 console.log("Two Random Date are same date ? ",someRondomDate.calendar(anotherRandomDate, {_x000D_
    sameDay: '[Today]'})=='Today');
<script src=""></script>

Simple (I think) Horizontal Line in WPF?

For anyone else struggling with this: Qwertie's comment worked well for me.

<Border Width="1" Margin="2" Background="#8888"/>

This creates a vertical seperator which you can talior to suit your needs.

Using GCC to produce readable assembly?

If you compile with debug symbols, you can use objdump to produce a more readable disassembly.

>objdump --help
-S, --source             Intermix source code with disassembly
-l, --line-numbers       Include line numbers and filenames in output

objdump -drwC -Mintel is nice:

  • -r shows symbol names on relocations (so you'd see puts in the call instruction below)
  • -R shows dynamic-linking relocations / symbol names (useful on shared libraries)
  • -C demangles C++ symbol names
  • -w is "wide" mode: it doesn't line-wrap the machine-code bytes
  • -Mintel: use GAS/binutils MASM-like .intel_syntax noprefix syntax instead of AT&T
  • -S: interleave source lines with disassembly.

You could put something like alias disas="objdump -drwCS -Mintel" in your ~/.bashrc


> gcc -g -c test.c
> objdump -d -M intel -S test.o

test.o:     file format elf32-i386

Disassembly of section .text:

00000000 <main>:
#include <stdio.h>

int main(void)
   0:   55                      push   ebp
   1:   89 e5                   mov    ebp,esp
   3:   83 e4 f0                and    esp,0xfffffff0
   6:   83 ec 10                sub    esp,0x10
   9:   c7 04 24 00 00 00 00    mov    DWORD PTR [esp],0x0
  10:   e8 fc ff ff ff          call   11 <main+0x11>

    return 0;
  15:   b8 00 00 00 00          mov    eax,0x0
  1a:   c9                      leave  
  1b:   c3                      ret

Note that this isn't using -r so the call rel32=-4 isn't annotated with the puts symbol name. And looks like a broken call that jumps into the middle of the call instruction in main. Remember that the rel32 displacement in the call encoding is just a placeholder until the linker fills in a real offset (to a PLT stub in this case, unless you statically link libc).

Excel concatenation quotes

I was Forming some Programming Logic Used CHAR(34) for Quotes at Excel : A small Part of same I am posting which can be helpfull ,Hopefully

1   Customers
2   Invoices

Formula Used :


Result :


ESLint - "window" is not defined. How to allow global variables in package.json

I found it on this page:

In package.json, this works:

"eslintConfig": {
  "globals": {
    "window": true

Laravel eloquent update record without loading from database

You can also use firstOrCreate OR firstOrNew

// Retrieve the Post by the attributes, or create it if it doesn't exist...
$post = Post::firstOrCreate(['id' => 3]);
// OR
// Retrieve the Post by the attributes, or instantiate a new instance...
$post = Post::firstOrNew(['id' => 3]); 

// update record
$post->title = "Updated title";

Hope it will help you :)

Difference between decimal, float and double in .NET?

float 7 digits of precision

double has about 15 digits of precision

decimal has about 28 digits of precision

If you need better accuracy, use double instead of float. In modern CPUs both data types have almost the same performance. The only benifit of using float is they take up less space. Practically matters only if you have got many of them.

I found this is interesting. What Every Computer Scientist Should Know About Floating-Point Arithmetic

Rails Active Record find(:all, :order => ) issue

I just ran into the same problem, but I manage to have my query working in SQLite like this:

@shows = Show.order("datetime(date) ASC, attending DESC")

I hope this might help someone save some time

Best/Most Comprehensive API for Stocks/Financial Data

I usually find that ProgrammableWeb is a good place to go when looking for APIs.

Understanding INADDR_ANY for socket programming

INADDR_ANY is used when you don't need to bind a socket to a specific IP. When you use this value as the address when calling bind(), the socket accepts connections to all the IPs of the machine.

"The page you are requesting cannot be served because of the extension configuration." error message

Verify that the application pool in IIS (in the case of IIS7 or above) is selected as integrated. In this case, probably change to Classic can solve this problem.

How do I loop through a date range?

I have a Range class in MiscUtil which you could find useful. Combined with the various extension methods, you could do:

foreach (DateTime date in StartDate.To(EndDate).ExcludeEnd()
    // Do something with the date

(You may or may not want to exclude the end - I just thought I'd provide it as an example.)

This is basically a ready-rolled (and more general-purpose) form of mquander's solution.

iterating over each character of a String in ruby 1.8.6 (each_char)

"ABCDEFG".chars.each do |char|
  puts char


"ABCDEFG".each_char {|char| p char}

Ruby version >2.5.1

npm command to uninstall or prune unused packages in Node.js

Note: Recent npm versions do this automatically when package-locks are enabled, so this is not necessary except for removing development packages with the --production flag.

Run npm prune to remove modules not listed in package.json.

From npm help prune:

This command removes "extraneous" packages. If a package name is provided, then only packages matching one of the supplied names are removed.

Extraneous packages are packages that are not listed on the parent package's dependencies list.

If the --production flag is specified, this command will remove the packages specified in your devDependencies.

Connection timeout for SQL server

If you want to dynamically change it, I prefer using SqlConnectionStringBuilder .

It allows you to convert ConnectionString i.e. a string into class Object, All the connection string properties will become its Member.

In this case the real advantage would be that you don't have to worry about If the ConnectionTimeout string part is already exists in the connection string or not?

Also as it creates an Object and its always good to assign value in object rather than manipulating string.

Here is the code sample:

var sscsb = new SqlConnectionStringBuilder(_dbFactory.Database.ConnectionString);

sscsb.ConnectTimeout = 30;

var conn = new SqlConnection(sscsb.ConnectionString);

Get current value selected in dropdown using jQuery

You can also use :checked

$("#myselect option:checked").val(); //to get value

or as said in other answers simply

$("#myselect").val(); //to get value


$("#myselect option:checked").text(); //to get text

TestNG ERROR Cannot find class in classpath

Please make sure that you have specified your class/package in TestNG.xml file.

<test name="test1" preserve-order="false">
        <class name="ABC"/>

Text size of android design TabLayout tabs


<style name="tab">
    <item name="android:textSize">@dimen/_10ssp</item>
    <item name="android:textColor">#FFFFFF</item>



        android:text="TAB 1"

        android:text="TAB 2" />

        android:text="TAB 3" />

How can I view an object with an alert()

you can use toSource method like this


SSRS 2008 R2 - SSRS 2012 - ReportViewer: Reports are blank in Safari and Chrome

I've used this. Add a script reference to jquery on the Report.aspx page. Use the following to link up JQuery to the microsoft events. Used a little bit of Eric's suggestion for setting the overflow.

$(document).ready(function () {
    if (navigator.userAgent.toLowerCase().indexOf("webkit") >= 0) {        
        Sys.Application.add_init(function () {
            var prm = Sys.WebForms.PageRequestManager.getInstance();
            if (!prm.get_isInAsyncPostBack()) {
                prm.add_endRequest(function () {
                    var divs = $('table[id*=_fixedTable] > tbody > tr:last > td:last > div')
                    divs.each(function (idx, element) {
                        $(element).css('overflow', 'visible');

Failed to connect to mailserver at "localhost" port 25

First of all, you aren't forced to use an SMTP on your localhost, if you change that localhost entry into the DNS name of the MTA from your ISP provider (who will let you relay mail) it will work right away, so no messing about with your own email service. Just try to use your providers SMTP servers, it will work right away.

String strip() for JavaScript?

Steven Levithan once wrote about how to implement a Faster JavaScript Trim. It’s definitely worth a look.

Center a popup window on screen?

I had an issue with centering a popup window in the external monitor and window.screenX and window.screenY were negative values (-1920, -1200) respectively. I have tried all the above of the suggested solutions and they worked well in primary monitors. I wanted to leave

  • 200 px margin for left and right
  • 150 px margin for top and bottom

Here is what worked for me:

 function createPopupWindow(url) {
    var height = screen.height;
    var width = screen.width;
    var left, top, win;

    if (width > 1050) {
        width = width - 200;
    } else {
        width = 850;

    if (height > 850) {
        height = height - 150;
    } else {
        height = 700;

    if (window.screenX < 0) {
        left = (window.screenX - width) / 2;
    } else {
        left = (screen.width - width) / 2;

    if (window.screenY < 0) {
        top = (window.screenY + height) / 4;
    } else {
        top = (screen.height - height) / 4;
    } url,"myTarget", "width="+width+", height="+height+",left="+left+",top="+top+"menubar=no, status=no, location=no, resizable=yes, scrollbars=yes");
    if (win.focus) {

PostgreSQL query to list all table names?

If you want list of database

SELECT datname FROM pg_database WHERE datistemplate = false;

If you want list of tables from current pg installation of all databases

SELECT table_schema,table_name FROM information_schema.tables
ORDER BY table_schema,table_name;

Why is "npm install" really slow?

This link helped me boost npm installs. Force npm to use http over https and disable progress display.

What is an example of the simplest possible example?

Edit: I feel it's better for anyone to consult the excellent chat example on the Socket.IO getting started page. The API has been quite simplified since I provided this answer. That being said, here is the original answer updated small-small for the newer API.

Just because I feel nice today:


<!doctype html>
        <script src='/'></script>
            var socket = io();

            socket.on('welcome', function(data) {

                // Respond with a message including this clients' id sent from the server
                socket.emit('i am client', {data: 'foo!', id:});
            socket.on('time', function(data) {
            socket.on('error', console.error.bind(console));
            socket.on('message', console.log.bind(console));

            function addMessage(message) {
                var text = document.createTextNode(message),
                    el = document.createElement('li'),
                    messages = document.getElementById('messages');

        <ul id='messages'></ul>


var http = require('http'),
    fs = require('fs'),
    // NEVER use a Sync function except at start-up!
    index = fs.readFileSync(__dirname + '/index.html');

// Send index.html to all requests
var app = http.createServer(function(req, res) {
    res.writeHead(200, {'Content-Type': 'text/html'});

// server listens to our app
var io = require('').listen(app);

// Send current time to all connected clients
function sendTime() {
    io.emit('time', { time: new Date().toJSON() });

// Send current time every 10 secs
setInterval(sendTime, 10000);

// Emit welcome message on connection
io.on('connection', function(socket) {
    // Use socket to communicate with this particular client only, sending it it's own id
    socket.emit('welcome', { message: 'Welcome!', id: });

    socket.on('i am client', console.log);


Nginx serves .php files as downloads, instead of executing them

My solution was to add

    location ~ \.php$ {
    try_files $uri =404;
    fastcgi_split_path_info ^(.+\.php)(/.+)$;
    fastcgi_pass unix:/run/php/php7.0-fpm.sock;
    fastcgi_index index.php;
    fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
    include fastcgi_params;

to my custom configuration file, for example etc/nginx/sites-available/

Adding to /etc/nginx/sites-available/default didn't work for me.

Difference between javacore, thread dump and heap dump in Websphere

Heap dumps anytime you wish to see what is being held in memory Out-of-memory errors Heap dumps - picture of in memory objects - used for memory analysis Java cores - also known as thread dumps or java dumps, used for viewing the thread activity inside the JVM at a given time. IBM javacores should a lot of additional information besides just the threads and stacks -- used to determine hangs, deadlocks, and reasons for performance degredation System cores

"Could not find a valid gem in any repository" (rubygame and others)

Can you post your versions?

ruby -v
#=> ruby 1.9.3p125 (2012-02-16 revision 34643) [x86_64-linux]

gem -v
#=> 1.8.19

If your gem command is not current, you can update it like this:

gem update --system

To see if you can connect to using Ruby:

require 'net/http'
require 'uri'
puts Net::HTTP.get URI.parse('')

If yes, that's good.

If no, then somehow Ruby is blocked from opening a net connection. Try these and see if any of them work:


curl --local-port 1080

curl --local-port 8080

env | grep -i proxy

If you're using a company machine, or within a company firewall, or running your own firewall, you may need to use a proxy.

For info on Ruby and proxies see

C++ convert from 1 char to string?

All of

std::string s(1, c); std::cout << s << std::endl;


std::cout << std::string(1, c) << std::endl;


std::string s; s.push_back(c); std::cout << s << std::endl;

worked for me.

jQuery counter to count up to a target number

Needed a break, so I cobbled the following together. Not sure it would be worth creating a plugin from though.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "">
<html xmlns="">
        <script type="text/javascript" src=""></script>
        <script type="text/javascript">
                function createCounter(elementId,start,end,totalTime,callback)
                    var jTarget=jQuery("#"+elementId);
                    var interval=totalTime/(end-start);
                    var intervalId;
                    var current=start;
                    var f=function(){
        <div id="counterTarget"></div>

get string from right hand side

If you want to list last 3 chars, simplest way is

 select substr('123456',-3) from dual;

How to Replace dot (.) in a string in Java

You need two backslashes before the dot, one to escape the slash so it gets through, and the other to escape the dot so it becomes literal. Forward slashes and asterisk are treated literal.

str=xpath.replaceAll("\\.", "/*/");          //replaces a literal . with /*/,%20java.lang.String)

Twitter Bootstrap add active class to li

You don't really need any JavaScript with Bootstrap:

 <ul class="nav">
     <li><a data-target="#" data-toggle="pill" href="#accounts">Accounts</a></li>
     <li><a data-target="#" data-toggle="pill" href="#users">Users</a></li>

To do more tasks after the menu item is selected you need JS as explained by other posts here.

Hope this helps.

Is it possible to preview stash contents in git?

When this question was first asked, this may not have been an option, but, if you use PyCharm, you can use the UnStash Changes tool (VCS->Git->UnStash Changes...). This allows you to view the list of stashed changes, as well as pop, drop, clear, or apply (into a new branch if desired):

Unstash Changes Window

and view the changed files per stash:

Paths Affected Window

as well as diffs per file. In the diffs you can cherry-pick individual changes to apply from the stashed changes to the working branch (using the left-pointing chevron):

enter image description here

What is the difference between bottom-up and top-down?

A key feature of dynamic programming is the presence of overlapping subproblems. That is, the problem that you are trying to solve can be broken into subproblems, and many of those subproblems share subsubproblems. It is like "Divide and conquer", but you end up doing the same thing many, many times. An example that I have used since 2003 when teaching or explaining these matters: you can compute Fibonacci numbers recursively.

def fib(n):
  if n < 2:
    return n
  return fib(n-1) + fib(n-2)

Use your favorite language and try running it for fib(50). It will take a very, very long time. Roughly as much time as fib(50) itself! However, a lot of unnecessary work is being done. fib(50) will call fib(49) and fib(48), but then both of those will end up calling fib(47), even though the value is the same. In fact, fib(47) will be computed three times: by a direct call from fib(49), by a direct call from fib(48), and also by a direct call from another fib(48), the one that was spawned by the computation of fib(49)... So you see, we have overlapping subproblems.

Great news: there is no need to compute the same value many times. Once you compute it once, cache the result, and the next time use the cached value! This is the essence of dynamic programming. You can call it "top-down", "memoization", or whatever else you want. This approach is very intuitive and very easy to implement. Just write a recursive solution first, test it on small tests, add memoization (caching of already computed values), and --- bingo! --- you are done.

Usually you can also write an equivalent iterative program that works from the bottom up, without recursion. In this case this would be the more natural approach: loop from 1 to 50 computing all the Fibonacci numbers as you go.

fib[0] = 0
fib[1] = 1
for i in range(48):
  fib[i+2] = fib[i] + fib[i+1]

In any interesting scenario the bottom-up solution is usually more difficult to understand. However, once you do understand it, usually you'd get a much clearer big picture of how the algorithm works. In practice, when solving nontrivial problems, I recommend first writing the top-down approach and testing it on small examples. Then write the bottom-up solution and compare the two to make sure you are getting the same thing. Ideally, compare the two solutions automatically. Write a small routine that would generate lots of tests, ideally -- all small tests up to certain size --- and validate that both solutions give the same result. After that use the bottom-up solution in production, but keep the top-bottom code, commented out. This will make it easier for other developers to understand what it is that you are doing: bottom-up code can be quite incomprehensible, even you wrote it and even if you know exactly what you are doing.

In many applications the bottom-up approach is slightly faster because of the overhead of recursive calls. Stack overflow can also be an issue in certain problems, and note that this can very much depend on the input data. In some cases you may not be able to write a test causing a stack overflow if you don't understand dynamic programming well enough, but some day this may still happen.

Now, there are problems where the top-down approach is the only feasible solution because the problem space is so big that it is not possible to solve all subproblems. However, the "caching" still works in reasonable time because your input only needs a fraction of the subproblems to be solved --- but it is too tricky to explicitly define, which subproblems you need to solve, and hence to write a bottom-up solution. On the other hand, there are situations when you know you will need to solve all subproblems. In this case go on and use bottom-up.

I would personally use top-bottom for Paragraph optimization a.k.a the Word wrap optimization problem (look up the Knuth-Plass line-breaking algorithms; at least TeX uses it, and some software by Adobe Systems uses a similar approach). I would use bottom-up for the Fast Fourier Transform.

How to revert the last migration?

The other thing that you can do is delete the table created manually.

Along with that, you will have to delete that particular migration file. Also, you will have to delete that particular entry in the django-migrations table(probably the last one in your case) which correlates to that particular migration.

Loop through a comma-separated shell variable

Not messing with IFS
Not calling external command

for i in ${variable//,/ }
    # call your procedure/other scripts here below
    echo "$i"

Using bash string manipulation

Center align with table-cell

This would be easier to do with flexbox. Using flexbox will let you not to specify the height of your content and can adjust automatically on the height it contains.


here's the gist of the demo


  display: flex;
  height: 100%;
  justify-content: center;
  align-items: center;



<div class="container">
  <div class='content'> //you can size this anyway you want
    put anything you want here,

enter image description here

Connecting to TCP Socket from browser using javascript

This will be possible via the navigator interface as shown below:

navigator.tcpPermission.requestPermission({remoteAddress:"", remotePort:6789}).then(
  () => {
    // Permission was granted
    // Create a new TCP client socket and connect to remote host
    var mySocket = new TCPSocket("", 6789);

    // Send data to server
    mySocket.writeable.write("Hello World").then(
        () => {

            // Data sent sucessfully, wait for response
            console.log("Data has been sent to server");
                ({ value, done }) => {
                    if (!done) {
                        // Response received, log it:
                        console.log("Data received from server:" + value);

                    // Close the TCP connection
        e => console.error("Sending error: ", e)

More details are outlined in the tcp-udp-sockets documentation.

Another alternative is to use Chrome Sockets

Creating connections

chrome.sockets.tcp.create({}, function(createInfo) {
    IP, PORT, onConnectedCallback);

Sending data

chrome.sockets.tcp.send(socketId, arrayBuffer, onSentCallback);

Receiving data

chrome.sockets.tcp.onReceive.addListener(function(info) {
  if (info.socketId != socketId)
  // is an arrayBuffer.

You can use also attempt to use HTML5 Web Sockets (Although this is not direct TCP communication):

var connection = new WebSocket('ws://IPAddress:Port');

connection.onopen = function () {
  connection.send('Ping'); // Send the message 'Ping' to the server

Your server must also be listening with a WebSocket server such as pywebsocket, alternatively you can write your own as outlined at Mozilla

Marker content (infoWindow) Google Maps

Although this question has already been answered, I think this approach is better : extract from this question on StackOverFlow google maps - open marker infowindow given the coordinates:

Each marker gets an "infowindow" entry :

function createMarker(lat, lon, html) {
    var newmarker = new google.maps.Marker({
        position: new google.maps.LatLng(lat, lon),
        map: map,
        title: html

    newmarker['infowindow'] = new google.maps.InfoWindow({
            content: html

    google.maps.event.addListener(newmarker, 'mouseover', function() {
        this['infowindow'].open(map, this);