Programs & Examples On #Design time data

Remove HTML tags from string including &nbsp in C#


(<.+?> | &nbsp;)

will match any tag or &nbsp;

string regex = @"(<.+?>|&nbsp;)";
var x = Regex.Replace(originalString, regex, "").Trim();

then x = hello

sqldeveloper error message: Network adapter could not establish the connection error

I had this error after fresh Oracle installation.

To fix this I've launched Net configuration assistant (from start menu or netca.bat in the bin folder) and simply added a Listener.

How to "perfectly" override a dict?

You can write an object that behaves like a dict quite easily with ABCs (Abstract Base Classes) from the module. It even tells you if you missed a method, so below is the minimal version that shuts the ABC up.

from import MutableMapping

class TransformedDict(MutableMapping):
    """A dictionary that applies an arbitrary key-altering
       function before accessing the keys"""

    def __init__(self, *args, **kwargs): = dict()
        self.update(dict(*args, **kwargs))  # use the free update to set keys

    def __getitem__(self, key):

    def __setitem__(self, key, value):[self._keytransform(key)] = value

    def __delitem__(self, key):

    def __iter__(self):
        return iter(
    def __len__(self):
        return len(

    def _keytransform(self, key):
        return key

You get a few free methods from the ABC:

class MyTransformedDict(TransformedDict):

    def _keytransform(self, key):
        return key.lower()

s = MyTransformedDict([('Test', 'test')])

assert s.get('TEST') is s['test']   # free get
assert 'TeSt' in s                  # free __contains__
                                    # free setdefault, __eq__, and so on

import pickle
# works too since we just use a normal dict
assert pickle.loads(pickle.dumps(s)) == s

I wouldn't subclass dict (or other builtins) directly. It often makes no sense, because what you actually want to do is implement the interface of a dict. And that is exactly what ABCs are for.

How to display both icon and title of action inside ActionBar?

Try adding a TextView to the menubar first and using setCompoundDrawables() to place the image on whichever side you want. Bond click activity to the textview in the end.

MenuItem item = menu.add(Menu.NONE,, 10,;
TextView textBtn = getTextButton(btn_title, btn_image);
textBtn.setOnClickListener(new View.OnClickListener() {
    public void onClick(View v) {
           // your selector here   }

You can literally customize everything here:

public TextView getTextButton (String btn_title, Drawable btn_image) {
    TextView textBtn = new TextView(this);
    textBtn.setTypeface(Typeface.create("sans-serif-light", Typeface.BOLD));
    textBtn.setGravity(Gravity.CENTER_VERTICAL | Gravity.CENTER_HORIZONTAL);
    Drawable img = btn_image;
    img.setBounds(0, 0, 30, 30);
    textBtn.setCompoundDrawables(null, null, img, null); 
    // left,top,right,bottom. In this case icon is right to the text

    return textBtn;

Manage toolbar's navigation and back button from fragment in android

(Kotlin) In the activity hosting the fragment(s):

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
    when (item.itemId) { -> {
            return true
    return super.onOptionsItemSelected(item)

I have found that when I add fragments to a project, they show the action bar home button by default, to remove/disable it put this in onViewCreated() (use true to enable it if it is not showing):

val actionBar = this.requireActivity().actionBar

How to delete projects in Intellij IDEA 14?

1. Choose project, right click, in context menu, choose Show in Explorer (on Mac, select Reveal in Finder).

enter image description here

2. Choose menu File \ Close Project

enter image description here

3. In Windows Explorer, press Del or Shift+Del for permanent delete.

4. At IntelliJ IDEA startup windows, hover cursor on old project name (what has been deleted) press Del for delelte.

enter image description here

How to access environment variable values?

.env File

Here is my .env file (I changed multiple characters in each key to prevent people hacking my accounts).



I was told my data was corrupted. I was struggling to work out what was going on. I had a suspicion the values from .env were not being passed into my settings file.


The only value being printed correctly was the SECRET_KEY. I reviewed the .env file and for the life of me could not see any reason why the SECRET_KEY was working and nothing else.

I got everything working eventually by putting this above the print statements.

from dotenv import load_dotenv   #for python-dotenv method
load_dotenv()                    #for python-dotenv method

And doing

pip install -U python-dotenv

I am still not sure why SECRET_KEY was working when all the others were broken.

How to style the menu items on an Android action bar

I did this way:

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
    <item name="actionMenuTextAppearance">@style/MenuTextAppearance</item>
    <item name="android:actionMenuTextAppearance">@style/MenuTextAppearance</item>
    <item name="actionMenuTextColor">@color/colorAccent</item>

<style name="MenuTextAppearance" >
    <item name="android:textAppearance">@android:style/TextAppearance.Large</item>
    <item name="android:textSize">20sp</item>
    <item name="android:textStyle">bold</item>

How to post data in PHP using file_get_contents?

$sUrl = '';
$params = array('http' => array(
    'method'  => 'POST',
    'content' => 'username=admin195&password=d123456789'

$ctx = stream_context_create($params);
$fp = @fopen($sUrl, 'rb', false, $ctx);
if(!$fp) {
    throw new Exception("Problem with $sUrl, $php_errormsg");

$response = @stream_get_contents($fp);
if($response === false) {
    throw new Exception("Problem reading data from $sUrl, $php_errormsg");

How to access nested elements of json object using getJSONArray method

This is for Nikola.

    public static JSONObject setProperty(JSONObject js1, String keys, String valueNew) throws JSONException {
    String[] keyMain = keys.split("\\.");
    for (String keym : keyMain) {
        Iterator iterator = js1.keys();
        String key = null;
        while (iterator.hasNext()) {
            key = (String);
            if ((js1.optJSONArray(key) == null) && (js1.optJSONObject(key) == null)) {
                if ((key.equals(keym)) && (js1.get(key).toString().equals(valueMain))) {
                    js1.put(key, valueNew);
                    return js1;
            if (js1.optJSONObject(key) != null) {
                if ((key.equals(keym))) {
                    js1 = js1.getJSONObject(key);
            if (js1.optJSONArray(key) != null) {
                JSONArray jArray = js1.getJSONArray(key);
                JSONObject j;
                for (int i = 0; i < jArray.length(); i++) {
                    js1 = jArray.getJSONObject(i);
    return js1;

public static void main(String[] args) throws IOException, JSONException {
    String text = "{ "key1":{ "key2":{ "key3":{ "key4":[ { "fieldValue":"Empty", "fieldName":"Enter Field Name 1" }, { "fieldValue":"Empty", "fieldName":"Enter Field Name 2" } ] } } } }";
    JSONObject json = new JSONObject(text);
    setProperty(json, "ke1.key2.key3.key4.fieldValue", "nikola");


If it's help bro,Do not forget to up for my reputation)))

Create Test Class in IntelliJ

I think you can always try the Ctrl + Shift + A to find the action/command you need.
Here you can try to press Ctrl + Shift + A and input «test» to find the command.

Excel VBA date formats

Thanks for the input. I'm obviously seeing some issues that aren't being replicated on others machines. Based on Jean's answer I have come up with less elegant solution that seems to work.

Since if I pass the cell a value directly from cdate, or just format it as a number it leaves the cell value as a string I've had to pass the date value into a numerical variable before passing that number back to the cell.

Function CellContentCanBeInterpretedAsADate(cell As Range) As Boolean
    Dim d As Date
    On Error Resume Next
    d = CDate(cell.Value)
    If Err.Number <> 0 Then
        CellContentCanBeInterpretedAsADate = False
        CellContentCanBeInterpretedAsADate = True
    End If
    On Error GoTo 0
End Function

Example usage:

Dim cell As Range
dim cvalue as double
Set cell = Range("A1")

If CellContentCanBeInterpretedAsADate(cell) Then
    cvalue = cdate(cell.value)
    cell.value = cvalue
    cell.NumberFormat = "mm/dd/yyyy hh:mm"
    cell.NumberFormat = "General"
End If

mysql query result into php array

What about this:

while ($row = mysql_fetch_array($result)) 
    $new_array[$row['id']]['id'] = $row['id'];
    $new_array[$row['id']]['link'] = $row['link'];

To retrieve link and id:

foreach($new_array as $array)
   echo $array['id'].'<br />';
   echo $array['link'].'<br />';

Calling another method java GUI

I'm not sure what you're trying to do, but here's something to consider: c(); won't do anything. c is an instance of the class checkbox and not a method to be called. So consider this:

public class FirstWindow extends JFrame {      public FirstWindow() {         checkbox c = new checkbox();         c.yourMethod(yourParameters); // call the method you made in checkbox     } }  public class checkbox extends JFrame {      public checkbox(yourParameters) {          // this is the constructor method used to initialize instance variables     }      public void yourMethod() // doesn't have to be void     {         // put your code here     } } 

Using arrays or std::vectors in C++, what's the performance gap?

Vectors are arrays under the hood. The performance is the same.

One place where you can run into a performance issue, is not sizing the vector correctly to begin with.

As a vector fills, it will resize itself, and that can imply, a new array allocation, followed by n copy constructors, followed by about n destructor calls, followed by an array delete.

If your construct/destruct is expensive, you are much better off making the vector the correct size to begin with.

There is a simple way to demonstrate this. Create a simple class that shows when it is constructed/destroyed/copied/assigned. Create a vector of these things, and start pushing them on the back end of the vector. When the vector fills, there will be a cascade of activity as the vector resizes. Then try it again with the vector sized to the expected number of elements. You will see the difference.

Sort objects in an array alphabetically on one property of the array

// Sorts an array of objects "in place". (Meaning that the original array will be modified and nothing gets returned.)
function sortOn (arr, prop) {
    arr.sort (
        function (a, b) {
            if (a[prop] < b[prop]){
                return -1;
            } else if (a[prop] > b[prop]){
                return 1;
            } else {
                return 0;   

//Usage example:

var cars = [
        {make:"AMC",        model:"Pacer",  year:1978},
        {make:"Koenigsegg", model:"CCGT",   year:2011},
        {make:"Pagani",     model:"Zonda",  year:2006},

// ------- make -------
sortOn(cars, "make");

AMC         : Pacer : 1978
Koenigsegg  : CCGT  : 2011
Pagani      : Zonda : 2006

// ------- model -------
sortOn(cars, "model");

Koenigsegg  : CCGT  : 2011
AMC         : Pacer : 1978
Pagani      : Zonda : 2006

// ------- year -------
sortOn(cars, "year");

AMC         : Pacer : 1978
Pagani      : Zonda : 2006
Koenigsegg  : CCGT  : 2011

How do you get the Git repository's name in some Git repository?

A little bit late for this question, but if you:

cat /path/to/repo/.git/config

You will see the url of the repository which will include the reponame:

    repositoryformatversion = 0
    filemode = true
    bare = false
    logallrefupdates = true
    ignorecase = true
    precomposeunicode = true
[remote "origin"]
    url =
    fetch = +refs/heads/*:refs/remotes/origin/*
[branch "master"]
    remote = origin
    merge = refs/heads/master

Is there a Java equivalent or methodology for the typedef keyword in C++?

In some cases, a binding annotation may be just what you're looking for:

Or if you don't want to depend on Guice, just a regular annotation might do.

Updating records codeigniter

In your_controller write this...

public function update_title() 
    $data = array
        'table_id' => $this->input->post('table_id'),
        'table_title' => $this->input->post('table_title')

    $this->load->model('your_model'); // First load the model
    if($this->your_model->update_title($data)) // call the method from the controller
        // update successful...
        // update not successful...


While in your_model...

public function update_title($data)

This will works fine...

Align Div at bottom on main Div

I guess you'll need absolute position

.vertical_banner {position:relative;}
#bottom_link{position:absolute; bottom:0;}

jQuery: Check if special characters exists in string

If you really want to check for all those special characters, it's easier to use a regular expression:

var str = $('#Search').val();
if(/^[a-zA-Z0-9- ]*$/.test(str) == false) {
    alert('Your search string contains illegal characters.');

The above will only allow strings consisting entirely of characters on the ranges a-z, A-Z, 0-9, plus the hyphen an space characters. A string containing any other character will cause the alert.

Plot data in descending order as appears in data frame

You want reorder(). Here is an example with dummy data

df <- data.frame(Category = sample(LETTERS), Count = rpois(26, 6))


p1 <- ggplot(df, aes(x = Category, y = Count)) +
         geom_bar(stat = "identity")

p2 <- ggplot(df, aes(x = reorder(Category, -Count), y = Count)) +
         geom_bar(stat = "identity")

grid.arrange(arrangeGrob(p1, p2))


enter image description here

Use reorder(Category, Count) to have Category ordered from low-high.

I am getting "java.lang.ClassNotFoundException:" error even though it is defined in my classpath

Click on Deployment Assembly ( right above Java Build Path that you show as active ) and make sure that you see json-lib-2.4-jdk15.jar there.

Usually, you should add it to your build path and export it from your project. Once it's exported you will see the WTP warning that it's not a part of the deployment. Choose the Quick Fix option and add it to your deployment path.

Count number of rows matching a criteria

to get the number of observations the number of rows from your Dataset would be more valid:

nrow(dat[dat$sCode == "CA",])

How to upgrade PostgreSQL from version 9.6 to version 10.1 without losing data?

Update: This process is the same for upgrading 9.5 through at least 11.5; simply modify the commands to reflect versions 9.6 and 10, where 9.6 is the old version and 10 is the new version. Be sure to adjust the "old" and "new" directories accordingly, too.

I just upgraded PostgreSQL 9.5 to 9.6 on Ubuntu and thought I'd share my findings, as there are a couple of OS/package-specific nuances of which to be aware.

(I didn't want to have to dump and restore data manually, so several of the other answers here were not viable.)

In short, the process consists of installing the new version of PostgreSQL alongside the old version (e.g., 9.5 and 9.6), and then running the pg_upgrade binary, which is explained in (some) detail at .

The only "tricky" aspect of pg_upgrade is that failure to pass the correct value for an argument, or failure to be logged-in as the correct user or cd to the correct location before executing a command, may lead to cryptic error messages.

On Ubuntu (and probably Debian), provided you are using the "official" repo, deb xenial-pgdg main, and provided you haven't changed the default filesystem paths or runtime options, the following procedure should do the job.

Install the new version (note that we specify the 9.6, explicitly):

sudo apt install postgresql-9.6

Once installation succeeds, both versions will be running side-by-side, but on different ports. The installation output mentions this, at the bottom, but it's easy to overlook:

Creating new cluster 9.6/main ...
  config /etc/postgresql/9.6/main
  data   /var/lib/postgresql/9.6/main
  locale en_US.UTF-8
  socket /var/run/postgresql
  port   5433

Stop both server instances (this will stop both at the same time):

sudo systemctl stop postgresql

Switch to the dedicated PostgreSQL system user:

su postgres

Move into his home directory (failure to do this will cause errors):

cd ~

pg_upgrade requires the following inputs (pg_upgrade --help tells us this):

When you run pg_upgrade, you must provide the following information:
  the data directory for the old cluster  (-d DATADIR)
  the data directory for the new cluster  (-D DATADIR)
  the "bin" directory for the old version (-b BINDIR)
  the "bin" directory for the new version (-B BINDIR)

These inputs may be specified with "long names", to make them easier to visualize:

  -b, --old-bindir=BINDIR       old cluster executable directory
  -B, --new-bindir=BINDIR       new cluster executable directory
  -d, --old-datadir=DATADIR     old cluster data directory
  -D, --new-datadir=DATADIR     new cluster data directory

We must also pass the --new-options switch, because failure to do so results in the following:

connection to database failed: could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/var/lib/postgresql/.s.PGSQL.50432"?

This occurs because the default configuration options are applied in the absence of this switch, which results in incorrect connection options being used, hence the socket error.

Execute the pg_upgrade command from the new PostgreSQL version:

/usr/lib/postgresql/9.6/bin/pg_upgrade --old-bindir=/usr/lib/postgresql/9.5/bin --new-bindir=/usr/lib/postgresql/9.6/bin --old-datadir=/var/lib/postgresql/9.5/main --new-datadir=/var/lib/postgresql/9.6/main --old-options=-cconfig_file=/etc/postgresql/9.5/main/postgresql.conf --new-options=-cconfig_file=/etc/postgresql/9.6/main/postgresql.conf

Logout of the dedicated system user account:


The upgrade is now complete, but, the new instance will bind to port 5433 (the standard default is 5432), so keep this in mind if attempting to test the new instance before "cutting-over" to it.

Start the server as normal (again, this will start both the old and new instances):

systemctl start postgresql

If you want to make the new version the default, you will need to edit the effective configuration file, e.g., /etc/postgresql/9.6/main/postgresql.conf, and ensure that the port is defined as such:

port = 5432

If you do this, either change the old version's port number to 5433 at the same time (before starting the services), or, simply remove the old version (this will not remove your actual database content; you would need to use apt --purge remove postgresql-9.5 for that to happen):

apt remove postgresql-9.5

The above command will stop all instances, so you'll need to start the new instance one last time with:

systemctl start postgresql

As a final point of note, don't forget to consider pg_upgrade's good advice:

Upgrade Complete
Optimizer statistics are not transferred by pg_upgrade so,
once you start the new server, consider running:

Running this script will delete the old cluster's data files:

How to add hours to current date in SQL Server?

DATEADD (datepart , number , date )

declare @num_hours int; 
    set @num_hours = 5; 

select dateadd(HOUR, @num_hours, getdate()) as time_added, 
       getdate() as curr_date  

Wait for Angular 2 to load/resolve model before rendering view/template

EDIT: The angular team has released the @Resolve decorator. It still needs some clarification, in how it works, but until then I'll take someone else's related answer here, and provide links to other sources:

EDIT: This answer works for Angular 2 BETA only. Router is not released for Angular 2 RC as of this edit. Instead, when using Angular 2 RC, replace references to router with router-deprecated to continue using the beta router.

The Angular2-future way to implement this will be via the @Resolve decorator. Until then, the closest facsimile is CanActivate Component decorator, per Brandon Roberts. see

Although beta 0 doesn't support providing resolved values to the Component, it's planned, and there is also a workaround described here: Using Resolve In Angular2 Routes

A beta 1 example can be found here: . It uses a very similar workaround, but slightly more accurately uses the RouteData object rather than RouteParams.

@CanActivate((to) => {
    return new Promise((resolve) => { = { name: 'John' }

Also, note that there is also an example workaround for accessing nested/parent route "resolved" values as well, and other features you expect if you've used 1.x UI-Router.

Note you'll also need to manually inject any services you need to accomplish this, since the Angular Injector hierarchy is not currently available in the CanActivate decorator. Simply importing an Injector will create a new injector instance, without access to the providers from bootstrap(), so you'll probably want to store an application-wide copy of the bootstrapped injector. Brandon's second Plunk link on this page is a good starting point:

Android: Create a toggle button with image and no text

create toggle_selector.xml in res/drawable

<?xml version="1.0" encoding="utf-8"?> 
<selector xmlns:android="">
  <item android:drawable="@drawable/toggle_on" android:state_checked="true"/>
  <item android:drawable="@drawable/toggle_off" android:state_checked="false"/>

apply the selector to your toggle button


Note: for removing the text i used following in above code


Generating a list of pages (not posts) without the index file

I have never used jekyll, but it's main page says that it uses Liquid, and according to their docs, I think the following should work:

<ul> {% for page in site.pages %}     {% if page.title != 'index' %}     <li><div class="drvce"><a href="{{ page.url }}">{{ page.title }}</a></div></li>     {% endif %} {% endfor %} </ul> 

error: passing xxx as 'this' argument of xxx discards qualifiers

The objects in the std::set are stored as const StudentT. So when you try to call getId() with the const object the compiler detects a problem, mainly you're calling a non-const member function on const object which is not allowed because non-const member functions make NO PROMISE not to modify the object; so the compiler is going to make a safe assumption that getId() might attempt to modify the object but at the same time, it also notices that the object is const; so any attempt to modify the const object should be an error. Hence compiler generates an error message.

The solution is simple: make the functions const as:

int getId() const {
    return id;
string getName() const {
    return name;

This is necessary because now you can call getId() and getName() on const objects as:

void f(const StudentT & s)
     cout << s.getId();   //now okay, but error with your versions
     cout << s.getName(); //now okay, but error with your versions

As a sidenote, you should implement operator< as :

inline bool operator< (const StudentT & s1, const StudentT & s2)
    return  s1.getId() < s2.getId();

Note parameters are now const reference.

"You may need an appropriate loader to handle this file type" with Webpack and Babel

In my case, I had such error since import path was wrong:

Wrong: import Select from "react-select/src/Select"; // it was auto-generated by IDE ;)

Correct: import Select from "react-select";

How do I create a message box with "Yes", "No" choices and a DialogResult?

This should do it:

DialogResult dialogResult = MessageBox.Show("Sure", "Some Title", MessageBoxButtons.YesNo);
if(dialogResult == DialogResult.Yes)
    //do something
else if (dialogResult == DialogResult.No)
    //do something else

Cannot find module '@angular/compiler'

In my case this was required:
npm install @angular/compiler --save
npm install @angular/cli --save-dev

Removing duplicates from a list of lists

Doing it manually, creating a new k list and adding entries not found so far:

k = [[1, 2], [4], [5, 6, 2], [1, 2], [3], [4]]
new_k = []
for elem in k:
    if elem not in new_k:
k = new_k
print k
# prints [[1, 2], [4], [5, 6, 2], [3]]

Simple to comprehend, and you preserve the order of the first occurrence of each element should that be useful, but I guess it's quadratic in complexity as you're searching the whole of new_k for each element.

HTTP 404 when accessing .svc file in IIS

I found these instructions on a blog post that indicated this step, which worked for me (Windows 8, 64-bit):

Make sure that in windows features, you have both WCF options under .Net framework are ticked. So go to Control Panel –> Programs and Features –> Turn Windows Features ON/Off –> Features –> Add Features –> .NET Framework X.X Features. Make sure that .Net framework says it is installed, and make sure that the WCF Activation node underneath it is selected (checkbox ticked) and both options under WCF Activation are also checked.
These are:
* HTTP Activation
* Non-HTTP Activation
Both options need to be selected (checked box ticked).

Virtualbox shared folder permissions

In my personal experience, it's difficult to enable shared folders in VirtualBox but it Is posible. I have a debian Buster guest virtual machine installed in my Windows 10 host.

I don't recognize exactly what did it, but I remember I went to Windows defender, my antivirus to see if they recognize VirtualBox as a program and not as a virus. After that, I press right click on the document file and allowed to share the folder and I gave click to some buttons there and accepted to share with groups and with muy user in Windows 10.

Also, I found a webpage of Windows about something like virtual machines that I don't remember well, but it took me to a panel and I had to change three things double clicking so when I update Windows, it recognizes my virtual machine. Also, in muy debian, in the terminal, using some command lines, muy VirtualBox recognized my user giving permissions, I based on some info in the Ubuntu forums. I put all what I remember.

Can I give the col-md-1.5 in bootstrap?

This is not Bootstrap Standard to give col-md-1.5 and you can not edit bootstrap.min.css because is not right way. you can create like this

Matching a space in regex

You can also use the \b for a word boundary. For the name I would use something like this:


EDIT Modifying this to be a regex in Perl example

if( $fullname =~ /([^\b]+)\b[^\b]+([^\b]+)(\b|$)/ ) {
 $first_name = $1;
 $last_name = $2;

EDIT AGAIN Based on what you want:

$new_tag = preg_replace("/[\s\t]/","",$tag);

How do servlets work? Instantiation, sessions, shared variables and multithreading

When the servlet container (like Apache Tomcat) starts up, it will read from the web.xml file (only one per application) if anything goes wrong or shows up an error at container side console, otherwise, it will deploy and load all web applications by using web.xml (so named it as deployment descriptor).

During instantiation phase of the servlet, servlet instance is ready but it cannot serve the client request because it is missing with two pieces of information:
1: context information
2: initial configuration information

Servlet engine creates servletConfig interface object encapsulating the above missing information into it servlet engine calls init() of the servlet by supplying servletConfig object references as an argument. Once init() is completely executed servlet is ready to serve the client request.

Q) In the lifetime of servlet how many times instantiation and initialization happens ??

A)only once (for every client request a new thread is created) only one instance of the servlet serves any number of the client request ie, after serving one client request server does not die. It waits for other client requests ie what CGI (for every client request a new process is created) limitation is overcome with the servlet (internally servlet engine creates the thread).

Q)How session concept works?

A)whenever getSession() is called on HttpServletRequest object

Step 1: request object is evaluated for incoming session ID.

Step 2: if ID not available a brand new HttpSession object is created and its corresponding session ID is generated (ie of HashTable) session ID is stored into httpservlet response object and the reference of HttpSession object is returned to the servlet (doGet/doPost).

Step 3: if ID available brand new session object is not created session ID is picked up from the request object search is made in the collection of sessions by using session ID as the key.

Once the search is successful session ID is stored into HttpServletResponse and the existing session object references are returned to the doGet() or doPost() of UserDefineservlet.


1)when control leaves from servlet code to client don't forget that session object is being held by servlet container ie, the servlet engine

2)multithreading is left to servlet developers people for implementing ie., handle the multiple requests of client nothing to bother about multithread code

Inshort form:

A servlet is created when the application starts (it is deployed on the servlet container) or when it is first accessed (depending on the load-on-startup setting) when the servlet is instantiated, the init() method of the servlet is called then the servlet (its one and only instance) handles all requests (its service() method being called by multiple threads). That's why it is not advisable to have any synchronization in it, and you should avoid instance variables of the servlet when the application is undeployed (the servlet container stops), the destroy() method is called.

What is the difference between SQL and MySQL?

SQL is Structured Query Language

MySQL is a relational database management system. You can submit SQL queries to the MySQL database to store, retrieve, modify or delete data.

What is the difference between Dim, Global, Public, and Private as Modular Field Access Modifiers?

Dim and Private work the same, though the common convention is to use Private at the module level, and Dim at the Sub/Function level. Public and Global are nearly identical in their function, however Global can only be used in standard modules, whereas Public can be used in all contexts (modules, classes, controls, forms etc.) Global comes from older versions of VB and was likely kept for backwards compatibility, but has been wholly superseded by Public.

How to display pandas DataFrame of floats using a format string for columns?


    df = pd.DataFrame({'money': [100.456, 200.789], 'share': ['100,000', '200,000']})
    print(df.to_string(formatters={'money': '${:,.2f}'.format}))
    for col_name in ('share',):
        df[col_name] = df[col_name].map(lambda p: int(p.replace(',', '')))
        money    share
    0  100.456  100,000
    1  200.789  200,000

        money    share
    0 $100.46  100,000
    1 $200.79  200,000

         money   share
    0  100.456  100000
    1  200.789  200000

Java - removing first character of a string

Use the substring() function with an argument of 1 to get the substring from position 1 (after the first character) to the end of the string (leaving the second argument out defaults to the full length of the string).


Submitting a form on 'Enter' with jQuery?

Here's a way to do this as a JQuery plugin (in case you want to re-use the functionality):

$.fn.onEnterKey =
    function( closure ) {
            function( event ) {
                var code = event.keyCode ? event.keyCode : event.which;

                if (code == 13) {
                    return false;
            } );

Now if you want to decorate an <input> element with this type of functionality it's as simple as this:

    function() {
        // Do stuff here
    } );

Override back button to act like home button

I have use @Mirko N. answser using made the new Custom EditText

 public class EditViewCustom extends EditText {

    Button cancelBtn;
    RelativeLayout titleReleLayout;
    public EditViewCustom(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

    public EditViewCustom(Context context, AttributeSet attrs) {
        super(context, attrs);

    public EditViewCustom(Context context) {

    public void setViews(Button cancelBtn,RelativeLayout titleReleLayout){
        this.cancelBtn = cancelBtn;
        this.titleReleLayout = titleReleLayout;

    public boolean onKeyPreIme(int keyCode, KeyEvent event) {
        if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {

            return super.onKeyPreIme(keyCode, event);

        return super.onKeyPreIme(keyCode, event);


Then set data from your activity

 searchEditView.setViews(cancelBtn, titleRelativeLayout);

Thank you.

How to check if a windows form is already open, and close it if it is?

In my app I had a mainmenu form that had buttons to navigate to an assortment of other forms (aka sub-forms). I wanted only one instance of each sub-form to be running at a time. Plus I wanted to ensure if a user attempted to launch a sub-form already in existence, that the sub-form would be forced to show "front&center" if minimized or behind other app windows. Using the currently most upvoted answers, I refactored their answers into this:

private void btnOpenSubForm_Click(object sender, EventArgs e)

        Form fsf = Application.OpenForms["formSubForm"];

        if (fsf != null)
            fsf.WindowState = FormWindowState.Normal;
            fsf.TopMost = true;
            Form formSubForm = new FormSubForm();
            formSubForm.TopMost = true;

Why is it not advisable to have the database and web server on the same machine?

On the other hand, referring to a different blogging Scott (Watermasyck, of Telligent) - they found that most users could speed up the websites (using Telligent's Community Server), by putting the database on the same machine as the web site. However, in their customer's case, usually the db & web server are the only applications on that machine, and the website isn't straining the machine that much. Then, the efficiency of not having to send data across the network more that made up for the increased strain.

How to do a scatter plot with empty circles in Python?

From the documentation for scatter:

Optional kwargs control the Collection properties; in particular:

        The string ‘none’ to plot faces with no outlines
        The string ‘none’ to plot unfilled outlines

Try the following:

import matplotlib.pyplot as plt 
import numpy as np 

x = np.random.randn(60) 
y = np.random.randn(60)

plt.scatter(x, y, s=80, facecolors='none', edgecolors='r')

example image

Note: For other types of plots see this post on the use of markeredgecolor and markerfacecolor.

Insert multiple rows WITHOUT repeating the "INSERT INTO ..." part of the statement?

Your syntax almost works in SQL Server 2008 (but not in SQL Server 20051):

CREATE TABLE MyTable (id int, name char(10));

INSERT INTO MyTable (id, name) VALUES (1, 'Bob'), (2, 'Peter'), (3, 'Joe');


id |  name
1  |  Bob       
2  |  Peter     
3  |  Joe       

1 When the question was answered, it was not made evident that the question was referring to SQL Server 2005. I am leaving this answer here, since I believe it is still relevant.

Why does integer division in C# return an integer and not a float?

Since you don't use any suffix, the literals 13 and 4 are interpreted as integer:


If the literal has no suffix, it has the first of these types in which its value can be represented: int, uint, long, ulong.

Thus, since you declare 13 as integer, integer division will be performed:


For an operation of the form x / y, binary operator overload resolution is applied to select a specific operator implementation. The operands are converted to the parameter types of the selected operator, and the type of the result is the return type of the operator.

The predefined division operators are listed below. The operators all compute the quotient of x and y.

Integer division:

int operator /(int x, int y);
uint operator /(uint x, uint y);
long operator /(long x, long y);
ulong operator /(ulong x, ulong y);

And so rounding down occurs:

The division rounds the result towards zero, and the absolute value of the result is the largest possible integer that is less than the absolute value of the quotient of the two operands. The result is zero or positive when the two operands have the same sign and zero or negative when the two operands have opposite signs.

If you do the following:

int x = 13f / 4f;

You'll receive a compiler error, since a floating-point division (the / operator of 13f) results in a float, which cannot be cast to int implicitly.

If you want the division to be a floating-point division, you'll have to make the result a float:

float x = 13 / 4;

Notice that you'll still divide integers, which will implicitly be cast to float: the result will be 3.0. To explicitly declare the operands as float, using the f suffix (13f, 4f).

How to push objects in AngularJS between ngRepeat arrays

change your method to:

$scope.toggleChecked = function (index) {
    $scope.items.splice(index, 1);

Working Demo

How can I copy a Python string?

You can copy a string in python via string formatting :

>>> a = 'foo'  
>>> b = '%s' % a  
>>> id(a), id(b)  
(140595444686784, 140595444726400)  

Make Bootstrap Popover Appear/Disappear on Hover instead of Click

Set the trigger option of the popover to hover instead of click, which is the default one.

This can be done using either data-* attributes in the markup:

<a id="popover" data-trigger="hover">Popover</a>

Or with an initialization option:

$("#popover").popover({ trigger: "hover" });

Here's a DEMO.

Python urllib2, basic HTTP authentication, and

I would suggest that the current solution is to use my package urllib2_prior_auth which solves this pretty nicely (I work on inclusion to the standard lib.

Pass react component as props

Using this.props.children is the idiomatic way to pass instantiated components to a react component

const Label = props => <span>{props.children}</span>
const Tab = props => <div>{props.children}</div>
const Page = () => <Tab><Label>Foo</Label></Tab>

When you pass a component as a parameter directly, you pass it uninstantiated and instantiate it by retrieving it from the props. This is an idiomatic way of passing down component classes which will then be instantiated by the components down the tree (e.g. if a component uses custom styles on a tag, but it wants to let the consumer choose whether that tag is a div or span):

const Label = props => <span>{props.children}</span>
const Button = props => {
    const Inner = props.inner; // Note: variable name _must_ start with a capital letter 
    return <button><Inner>Foo</Inner></button>
const Page = () => <Button inner={Label}/>

If what you want to do is to pass a children-like parameter as a prop, you can do that:

const Label = props => <span>{props.content}</span>
const Tab = props => <div>{props.content}</div>
const Page = () => <Tab content={<Label content='Foo' />} />

After all, properties in React are just regular JavaScript object properties and can hold any value - be it a string, function or a complex object.

How to allocate aligned memory only using the standard library?

You could also try posix_memalign() (on POSIX platforms, of course).

Links not going back a directory?

To go up a directory in a link, use ... This means "go up one directory", so your link will look something like this:

<a href="../index.html">Home</a>

ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

I had the same problem (i.e. indexing with multi-conditions, here it's finding data in a certain date range). The (a-b).any() or (a-b).all() seem not working, at least for me.

Alternatively I found another solution which works perfectly for my desired functionality (The truth value of an array with more than one element is ambigous when trying to index an array).

Instead of using suggested code above, simply using a numpy.logical_and(a,b) would work. Here you may want to rewrite the code as

selected  = r[numpy.logical_and(r["dt"] >= startdate, r["dt"] <= enddate)]

What's the purpose of META-INF?

From the official JAR File Specification (link goes to the Java 7 version, but the text hasn't changed since at least v1.3):

The META-INF directory

The following files/directories in the META-INF directory are recognized and interpreted by the Java 2 Platform to configure applications, extensions, class loaders and services:


The manifest file that is used to define extension and package related data.


This file is generated by the new "-i" option of the jar tool, which contains location information for packages defined in an application or extension. It is part of the JarIndex implementation and used by class loaders to speed up their class loading process.

  • x.SF

The signature file for the JAR file. 'x' stands for the base file name.

  • x.DSA

The signature block file associated with the signature file with the same base file name. This file stores the digital signature of the corresponding signature file.

  • services/

This directory stores all the service provider configuration files.

Iterate through the fields of a struct in Go

Maybe too late :))) but there is another solution that you can find the key and value of structs and iterate over that

package main

import (

type person struct {
    firsName string
    lastName string
    iceCream []string

func main() {
    u := struct {
        myMap    map[int]int
        mySlice  []string
        myPerson person
        myMap:   map[int]int{1: 10, 2: 20},
        mySlice: []string{"red", "green"},
        myPerson: person{
            firsName: "Esmaeil",
            lastName: "Abedi",
            iceCream: []string{"Vanilla", "chocolate"},
    v := reflect.ValueOf(u)
    for i := 0; i < v.NumField(); i++ {
        fmt.Println("\t", v.Field(i))
and there is no *panic* for v.Field(i)

Git merge errors

git commit -m "Merged master fixed conflict."

Creating/writing into a new file in Qt

QFile file("test.txt");
 *If file does not exist, it will be created
if (! | QIODevice::Text | QIODevice::ReadWrite))

/*for Reading line by line from text file*/
while (!file.atEnd()) {
    QByteArray line = file.readLine();
    qDebug() << "read output - " << line;

/*for writing line by line to text file */
if (
    QTextStream stream(&file);
    stream << "1_XYZ"<<endl;
    stream << "2_XYZ"<<endl;

Clang vs GCC - which produces faster binaries?

The only way to determine this is to try it. FWIW I have seen some really good improvements using Apple's LLVM gcc 4.2 compared to the regular gcc 4.2 (for x86-64 code with quite a lot of SSE), but YMMV for different code bases. Assuming you're working with x86/x86-64 and that you really do care about the last few percent then you ought to try Intel's ICC too, as this can often beat gcc - you can get a 30 day evaluation license from and try it.

OpenCV - Saving images to a particular folder of choice

FOR MAC USERS if you are working with open cv

import cv2


Base64 length calculation?

I think the given answers miss the point of the original question, which is how much space needs to be allocated to fit the base64 encoding for a given binary string of length n bytes.

The answer is (floor(n / 3) + 1) * 4 + 1

This includes padding and a terminating null character. You may not need the floor call if you are doing integer arithmetic.

Including padding, a base64 string requires four bytes for every three-byte chunk of the original string, including any partial chunks. One or two bytes extra at the end of the string will still get converted to four bytes in the base64 string when padding is added. Unless you have a very specific use, it is best to add the padding, usually an equals character. I added an extra byte for a null character in C, because ASCII strings without this are a little dangerous and you'd need to carry the string length separately.

How can I hide or encrypt JavaScript code?

The only safe way to protect your code is not giving it away. With client deployment, there is no avoiding the client having access to the code.

So the short answer is: You can't do it

The longer answer is considering flash or Silverlight. Although I believe silverlight will gladly give away it's secrets with reflector running on the client.

I'm not sure if something simular exists with the flash platform.

Remove characters from NSString?

You could use:

NSString *stringWithoutSpaces = [myString 
   stringByReplacingOccurrencesOfString:@" " withString:@""];

Using Jasmine to spy on a function without an object

import * as saveAsFunctions from 'file-saver';
let saveAs;
            beforeEach(() => {
                saveAs = jasmine.createSpy('saveAs');
            it('should generate the excel on sample request details page', () => {
                spyOn(saveAsFunctions, 'saveAs').and.callFake(saveAs);

This worked for me.

JWT refresh token flow

Based in this implementation with Node.js of JWT with refresh token:

1) In this case they use a uid and it's not a JWT. When they refresh the token they send the refresh token and the user. If you implement it as a JWT, you don't need to send the user, because it would inside the JWT.

2) They implement this in a separated document (table). It has sense to me because a user can be logged in in different client applications and it could have a refresh token by app. If the user lose a device with one app installed, the refresh token of that device could be invalidated without affecting the other logged in devices.

3) In this implementation it response to the log in method with both, access token and refresh token. It seams correct to me.

How to change color of the back arrow in the new material theme?

if use Toolbar,you can try this

Drawable drawable = toolbar.getNavigationIcon();
drawable.setColorFilter(ContextCompat.getColor(appCompatActivity, colorId), PorterDuff.Mode.SRC_ATOP);

Launch an app on OS X with command line

In OS X 10.6, the open command was enhanced to allow passing of arguments to the application:

open ./ --args -AppCommandLineArg

But for older versions of Mac OS X, and because app bundles aren't designed to be passed command line arguments, the conventional mechanism is to use Apple Events for files like here for Cocoa apps or here for Carbon apps. You could also probably do something kludgey by passing parameters in using environment variables.

How can I run a windows batch file but hide the command window?

Create a shortcut to your bat file by using the right-click and selecting Create shortcut. Right-click on the shortcut you created and click on properties. Click on the Run drop-down box and select Minimized.

jQuery set checkbox checked

Set the check box after loading the modal window. I think you are setting the check box before loading the page.


Compare and contrast REST and SOAP web services?

SOAP brings it’s own protocol and focuses on exposing pieces of application logic (not data) as services. SOAP exposes operations. SOAP is focused on accessing named operations, each implement some business logic through different interfaces.

Though SOAP is commonly referred to as “web services” this is a misnomer. SOAP has very little if anything to do with the Web. REST provides true “Web services” based on URIs and HTTP.

By way of illustration here are few calls and their appropriate home with commentary.


This is a rest operation as you are accessing a resource (data).

switchCategory(User, OldCategory, NewCategory)

REST permits many different data formats where as SOAP only permits XML. While this may seem like it adds complexity to REST because you need to handle multiple formats, in my experience it has actually been quite beneficial. JSON usually is a better fit for data and parses much faster. REST allows better support for browser clients due to it’s support for JSON.

how to replace an entire column on Pandas.DataFrame

If the indices match then:

df['B'] = df1['E']

should work otherwise:

df['B'] = df1['E'].values

will work so long as the length of the elements matches

Fragments onResume from back stack

In my activity onCreate()


Use this method to catch specific Fragment and call onResume()

private FragmentManager.OnBackStackChangedListener getListener()
        FragmentManager.OnBackStackChangedListener result = new FragmentManager.OnBackStackChangedListener()
            public void onBackStackChanged()
                Fragment currentFragment = getSupportFragmentManager().findFragmentById(;
                if (currentFragment instanceof YOURFRAGMENT) {

        return result;

Unicode character in PHP string

Try Portable UTF-8:

$str = utf8_chr( 0x1000 );
$str = utf8_chr( '\u1000' );
$str = utf8_chr( 4096 );

All work exactly the same way. You can get the codepoint of a character with utf8_ord(). Read more about Portable UTF-8.

Jquery set radio button checked, using id and class selectors

" a class and a div."

I assume when you say "div" you mean "id"? Try this:

$('#test2.test1').prop('checked', true);

No need to muck about with your [attributename=value] style selectors because id has its own format as does class, and they're easily combined although given that id is supposed to be unique it should be enough on its own unless your meaning is "select that element only if it currently has the specified class".

Or more generally to select an input where you want to specify a multiple attribute selector:

$('input:radio[class=test1][id=test2]').prop('checked', true);

That is, list each attribute with its own square brackets.

Note that unless you have a pretty old version of jQuery you should use .prop() rather than .attr() for this purpose.

Set start value for column with autoincrement

From Resetting SQL Server Identity Columns:

Retrieving the identity for the table Employees:

DBCC checkident ('Employees')

Repairing the identity seed (if for some reason the database is inserting duplicate identities):

DBCC checkident ('Employees', reseed)

Changing the identity seed for the table Employees to 1000:

DBCC checkident ('Employees', reseed, 1000)

The next row inserted will begin at 1001.

NullPointerException in Java with no StackTrace

Alternate suggestion - if you're using Eclipse, you could set a breakpoint on NullPointerException itself (in the Debug perspective, go to the "Breakpoints" tab and click on the little icon that has a ! in it)

Check both the "caught" and "uncaught" options - now when you trigger the NPE, you'll immediately breakpoint and you can then step through and see how exactly it is handled and why you're not getting a stack trace.

Writing a new line to file in PHP (line feed)

You can also use file_put_contents():

file_put_contents('ids.txt', implode("\n", $gemList) . "\n", FILE_APPEND);

How to get the current branch name in Git?

function git.branch {
  br=`git branch | grep "*"`
  echo ${br/* /}

What is std::move(), and when should it be used?

Here is a full example, using std::move for a (simple) custom vector

Expected output:

 c: [10][11]
 copy ctor called
 copy of c: [10][11]
 move ctor called
 moved c: [10][11]

Compile as:

  g++ -std=c++2a -O2 -Wall -pedantic foo.cpp


#include <iostream>
#include <algorithm>

template<class T> class MyVector {
    T *data;
    size_t maxlen;
    size_t currlen;
    MyVector<T> () : data (nullptr), maxlen(0), currlen(0) { }
    MyVector<T> (int maxlen) : data (new T [maxlen]), maxlen(maxlen), currlen(0) { }

    MyVector<T> (const MyVector& o) {
        std::cout << "copy ctor called" << std::endl;
        data = new T [o.maxlen];
        maxlen = o.maxlen;
        currlen = o.currlen;
        std::copy(, + o.maxlen, data);

    MyVector<T> (const MyVector<T>&& o) {
        std::cout << "move ctor called" << std::endl;
        data =;
        maxlen = o.maxlen;
        currlen = o.currlen;

    void push_back (const T& i) {
        if (currlen >= maxlen) {
            maxlen *= 2;
            auto newdata = new T [maxlen];
            std::copy(data, data + currlen, newdata);
            if (data) {
                delete[] data;
            data = newdata;
        data[currlen++] = i;

    friend std::ostream& operator<<(std::ostream &os, const MyVector<T>& o) {
        auto s =;
        auto e = + o.currlen;;
        while (s < e) {
            os << "[" << *s << "]";
        return os;

int main() {
    auto c = new MyVector<int>(1);
    std::cout << "c: " << *c << std::endl;
    auto d = *c;
    std::cout << "copy of c: " << d << std::endl;
    auto e = std::move(*c);
    delete c;
    std::cout << "moved c: " << e << std::endl;

How to delete multiple files at once in Bash on Linux?

A wild card would work nicely for this, although to be safe it would be best to make the use of the wild card as minimal as possible, so something along the lines of this:

rm -rf abc.log.2012-*

Although from the looks of it, are those just single files? The recursive option should not be necessary if none of those items are directories, so best to not use that, just for safety.

Spring cannot find bean xml configuration file when it does exist

You have looked at src directory. The xml file indeed exist there. But look at class or bin/build directory where all your output classes are set. I suspect you will need only resources/beans.xml path to use.

Using .text() to retrieve only text not nested in child tags

I came up with a specific solution that should be much more efficient than the cloning and modifying of the clone. This solution only works with the following two reservations, but should be more efficient than the currently accepted solution:

  1. You are getting only the text
  2. The text you want to extract is before the child elements

With that said, here is the code:

// 'element' is a jQuery element
function getText(element) {
  var text = element.text();
  var childLength = element.children().text().length;
  return text.slice(0, text.length - childLength);

Escape curly brace '{' in String.Format

Use double braces {{ or }} so your code becomes:

sb.AppendLine(String.Format("public {0} {1} {{ get; private set; }}", 
prop.Type, prop.Name));

// For prop.Type of "Foo" and prop.Name of "Bar", the result would be:
// public Foo Bar { get; private set; }

INSERT statement conflicted with the FOREIGN KEY constraint - SQL Server

In your table dbo.Sup_Item_Cat, it has a foreign key reference to another table. The way a FK works is it cannot have a value in that column that is not also in the primary key column of the referenced table.

If you have SQL Server Management Studio, open it up and sp_help 'dbo.Sup_Item_Cat'. See which column that FK is on, and which column of which table it references. You're inserting some bad data.

Let me know if you need anything explained better!

Assigning a function to a variable

The syntax

def x():

is basically the same as x = lambda: print(20) (there are some differences under the hood, but for most pratical purposes, the results the same).

The syntax

def y(t):
   return t**2

is basically the same as y= lambda t: t**2. When you define a function, you're creating a variable that has the function as its value. In the first example, you're setting x to be the function lambda: print(20). So x now refers to that function. x() is not the function, it's the call of the function. In python, functions are simply a type of variable, and can generally be used like any other variable. For example:

def power_function(power):
      return  lambda x : x**power

This returns 8. power_function is a function that returns a function as output. When it's called on 3, it returns a function that cubes the input, so when that function is called on the input 2, it returns 8. You could do cube = power_function(3), and now cube(2) would return 8.

html script src="" triggering redirection with button

First you are linking the file that is here:

<script src="../Script/login.js"> 

Which would lead the website to a file in the Folder Script, but then in the second paragraph you are saying that the folder name is

and also i have onother folder named scripts that contains the the following login.js file

So, this won't work! Because you are not accessing the correct file. To do that please write the code as

<script src="/script/login.js"></script>

Try removing the .. from the beginning of the code too.

This way, you'll reach the js file where the function would run!

Just to make sure:

Just to make sure that the files are attached the HTML DOM, then please open Developer Tools (F12) and in the network workspace note each request that the browser makes to the server. This way you will learn which files were loaded and which weren't, and also why they were not!

Good luck.

Is Python strongly typed?

The term "strong typing" does not have a definite definition.

Therefore, the use of the term depends on with whom you're speaking.

I do not consider any language, in which the type of a variable is not either explicitly declared, or statically typed to be strongly typed.

Strong typing doesn't just preclude conversion (for example, "automatically" converting from an integer to a string). It precludes assignment (i.e., changing the type of a variable).

If the following code compiles (interprets), the language is not strong-typed:

Foo = 1 Foo = "1"

In a strongly typed language, a programmer can "count on" a type.

For example, if a programmer sees the declaration,

UINT64 kZarkCount;

and he or she knows that 20 lines later, kZarkCount is still a UINT64 (as long as it occurs in the same block) - without having to examine intervening code.

how to initialize a char array?

memset(msg, 0, 65546)

Why are only a few video games written in Java?

I'm playing the Sims 3, and I did some poking around. The graphics engine is C++, while the scripting and behavior engine is C#/Mono. So while C++ is there for time critical bits, other stuff like .interaction, game logic, AI is in an object oriented managed language.

is python capable of running on multiple cores?

example code taking all 4 cores on my ubuntu 14.04, python 2.7 64 bit.

import time
import threading

def t():
    with open('/dev/urandom') as f:
        for x in xrange(100):
   * 65535)

if __name__ == '__main__':
    start_time = time.time()
    print "Sequential run time: %.2f seconds" % (time.time() - start_time)

    start_time = time.time()
    t1 = threading.Thread(target=t)
    t2 = threading.Thread(target=t)
    t3 = threading.Thread(target=t)
    t4 = threading.Thread(target=t)
    print "Parallel run time: %.2f seconds" % (time.time() - start_time)


$ python
Sequential run time: 3.69 seconds
Parallel run time: 4.82 seconds

The maximum value for an int type in Go

Use the constants defined in the math package:

const (
    MaxInt8   = 1<<7 - 1
    MinInt8   = -1 << 7
    MaxInt16  = 1<<15 - 1
    MinInt16  = -1 << 15
    MaxInt32  = 1<<31 - 1
    MinInt32  = -1 << 31
    MaxInt64  = 1<<63 - 1
    MinInt64  = -1 << 63
    MaxUint8  = 1<<8 - 1
    MaxUint16 = 1<<16 - 1
    MaxUint32 = 1<<32 - 1
    MaxUint64 = 1<<64 - 1

What's the best practice to "git clone" into an existing folder?

This can be done by cloning to a new directory, then moving the .git directory into your existing directory.

If your existing directory is named "code".

git clone temp
mv temp/.git code/.git
rm -rf temp

This can also be done without doing a checkout during the clone command; more information can be found here.

Converting Hexadecimal String to Decimal Integer

Well, Mr.ajb has resolved and pointed out the error in your code.

Coming to the second part of the code, that is, converting a string with letters to decimal integer below is code for that,

import java.util.Scanner;

public class HexaToDecimal
   int number;

   void getValue()
      Scanner sc = new Scanner(;
      System.out.println("Please enter hexadecimal to convert: ");
      number = Integer.parseInt(sc.nextLine(), 16);

   void toConvert()
      String decimal = Integer.toString(number);
      System.out.println("The Decimal value is : " + decimal);

   public static void main(String[] args)
      HexaToDecimal htd = new HexaToDecimal();

You can refer example on hexadecimal to decimal for more information.

Why are static variables considered evil?

a) Reason about programs.

If you have a small- to midsize-program, where the static variable is accessed, the call to it normally comes from nowhere - there is no path, and therefore no timeline, how the variable comes to the place, where it is used. Now how do I know who set it to its actual value? How do I know, what happens, if I modify it right now? I have grep over the whole source, to collect all accesses, to know, what is going on.

If you know how you use it, because you just wrote the code, the problem is invisible, but if you try to understand foreign code, you will understand.

b) Do you really only need one?

Static variables often prevent multiple programs of the same kind running in the same JVM with different values. You often don't foresee usages, where more than one instance of your program is useful, but if it evolves, or if it is useful for others, they might experience situations, where they would like to start more than one instance of your program.

Only more or less useless code which will not be used by many people over a longer time in an intensive way might go well with static variables.

Difference between uint32 and uint32_t

uint32_t is defined in the standard, in

18.4.1 Header <cstdint> synopsis [cstdint.syn]

namespace std {
typedef unsigned integer type uint32_t; // optional

uint32 is not, it's a shortcut provided by some compilers (probably as typedef uint32_t uint32) for ease of use.

Sorting multiple keys with Unix sort

I just want to add some tips, when you using sort , be careful about your locale that effects the order of the key comparison. I usually explicitly use LC_ALL=C to make locale what I want.

Remove empty strings from a list of strings

For a list with a combination of spaces and empty values, use simple list comprehension -

>>> s = ['I', 'am', 'a', '', 'great', ' ', '', '  ', 'person', '!!', 'Do', 'you', 'think', 'its', 'a', '', 'a', '', 'joke', '', ' ', '', '?', '', '', '', '?']

So, you can see, this list has a combination of spaces and null elements. Using the snippet -

>>> d = [x for x in s if x.strip()]
>>> d
>>> d = ['I', 'am', 'a', 'great', 'person', '!!', 'Do', 'you', 'think', 'its', 'a', 'a', 'joke', '?', '?']

ng-change get new value and original value

With an angular {{expression}} you can add the old user or value to the ng-change attribute as a literal string:

<select ng-change="updateValue(user, '{{}}')" 
        ng-model="" ng-options=" as for user in users">

On ngChange, the 1st argument to updateValue will be the new user value, the 2nd argument will be the literal that was formed when the select-tag was last updated by angular, with the old value.

How do I get values from a SQL database into textboxes using C#?

The line reader.Read() is missing in your code. You should add it. It is the function which actually reads data from the database:

string conString = "Data Source=localhost;Initial Catalog=LoginScreen;Integrated Security=True";
SqlConnection con = new SqlConnection(conString);

string selectSql = "select * from Pending_Tasks";
SqlCommand com = new SqlCommand(selectSql, con);


    using (SqlDataReader read = cmd.ExecuteReader())
            CustID.Text = (read["Customer_ID"].ToString());
            CustName.Text = (read["Customer_Name"].ToString());
            Add1.Text = (read["Address_1"].ToString());
            Add2.Text = (read["Address_2"].ToString());
            PostBox.Text = (read["Postcode"].ToString());
            PassBox.Text = (read["Password"].ToString());
            DatBox.Text = (read["Data_Important"].ToString());
            LanNumb.Text = (read["Landline"].ToString());
            MobNumber.Text = (read["Mobile"].ToString());
            FaultRep.Text = (read["Fault_Report"].ToString());

EDIT : This code works supposing you want to write the last record to your textboxes. If you want to apply a different scenario, like for example to read all the records from database and to change data in the texboxes when you click the Next button, you should create and use your own Model, or you can store data in the DataTable and refer to them later if you wish.

Choosing the correct upper and lower HSV boundaries for color detection with`cv::inRange` (OpenCV)

I Created this simple program to get HSV Codes in realtime

import cv2
import numpy as np

cap = cv2.VideoCapture(0)

def nothing(x):
# Creating a window for later use

# Starting with 100's to prevent error while masking
h,s,v = 100,100,100

# Creating track bar
cv2.createTrackbar('h', 'result',0,179,nothing)
cv2.createTrackbar('s', 'result',0,255,nothing)
cv2.createTrackbar('v', 'result',0,255,nothing)


    _, frame =

    #converting to HSV
    hsv = cv2.cvtColor(frame,cv2.COLOR_BGR2HSV)

    # get info from track bar and appy to result
    h = cv2.getTrackbarPos('h','result')
    s = cv2.getTrackbarPos('s','result')
    v = cv2.getTrackbarPos('v','result')

    # Normal masking algorithm
    lower_blue = np.array([h,s,v])
    upper_blue = np.array([180,255,255])

    mask = cv2.inRange(hsv,lower_blue, upper_blue)

    result = cv2.bitwise_and(frame,frame,mask = mask)


    k = cv2.waitKey(5) & 0xFF
    if k == 27:



How can I populate a select dropdown list from a JSON feed with AngularJS?

<select name="selectedFacilityId" ng-model="selectedFacilityId">
         <option ng-repeat="facility in facilities" value="{{}}">{{}}</option>

This is an example on how to use it.

JSON encode MySQL results

For example $result = mysql_query("SELECT * FROM userprofiles where NAME='TESTUSER' ");

1.) if $result is only one row.

$response = mysql_fetch_array($result);
echo json_encode($response);

2.) if $result is more than one row. You need to iterate the rows and save it to an array and return a json with array in it.

$rows = array();
if (mysql_num_rows($result) > 0) {
    while($r = mysql_fetch_assoc($result)) {
       $id = $r["USERID"];   //a column name (ex.ID) used to get a value of the single row at at time
       $rows[$id] = $r; //save the fetched row and add it to the array.
echo json_encode($rows);

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

After running around in the Preferences dialog, the following is the location at which the highlight color for "occurrences" can be changed:

General -> Editors -> Text Editors -> Annotations

Look for Occurences from the Annotation types list.

Then, be sure that Text as highlighted is selected, then choose the desired color.

And, a picture is worth a thousand words...

Preferences dialog

Image showing occurences highlighted in orange.

How to show imageView full screen on imageView click?

Use Immersive Full-Screen Mode

enter image description here

call fullScreen() on ImageView click.

 public void fullScreen() {

        // BEGIN_INCLUDE (get_current_ui_flags)
        // The UI options currently enabled are represented by a bitfield.
        // getSystemUiVisibility() gives us that bitfield.
        int uiOptions = getWindow().getDecorView().getSystemUiVisibility();
        int newUiOptions = uiOptions;
        // END_INCLUDE (get_current_ui_flags)
        // BEGIN_INCLUDE (toggle_ui_flags)
        boolean isImmersiveModeEnabled =
                ((uiOptions | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY) == uiOptions);
        if (isImmersiveModeEnabled) {
            Log.i(TAG, "Turning immersive mode mode off. ");
        } else {
            Log.i(TAG, "Turning immersive mode mode on.");

        // Navigation bar hiding:  Backwards compatible to ICS.
        if (Build.VERSION.SDK_INT >= 14) {
            newUiOptions ^= View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;

        // Status bar hiding: Backwards compatible to Jellybean
        if (Build.VERSION.SDK_INT >= 16) {
            newUiOptions ^= View.SYSTEM_UI_FLAG_FULLSCREEN;

        // Immersive mode: Backward compatible to KitKat.
        // Note that this flag doesn't do anything by itself, it only augments the behavior
        // of HIDE_NAVIGATION and FLAG_FULLSCREEN.  For the purposes of this sample
        // all three flags are being toggled together.
        // Note that there are two immersive mode UI flags, one of which is referred to as "sticky".
        // Sticky immersive mode differs in that it makes the navigation and status bars
        // semi-transparent, and the UI flag does not get cleared when the user interacts with
        // the screen.
        if (Build.VERSION.SDK_INT >= 18) {
            newUiOptions ^= View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY;

        //END_INCLUDE (set_ui_flags)

Read more

Example Download

In Swift how to call method with parameters on GCD main thread?

Don't forget to weakify self if you are using self inside of the closure.

dispatch_async(dispatch_get_main_queue(),{ [weak self] () -> () in
    if let strongSelf = self {

How do I check when a UITextField changes?

Swift 5.0

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)),
                          for: .editingChanged)

and handle method:

@objc func textFieldDidChange(_ textField: UITextField) {


Swift 4.0

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)),
                          for: UIControlEvents.editingChanged)

and handle method:

@objc func textFieldDidChange(_ textField: UITextField) {


Swift 3.0

textField.addTarget(self, action: #selector(textFieldDidChange(textField:)), for: .editingChanged)

and handle method:

func textFieldDidChange(textField: UITextField) { 


How to find reason of failed Build without any error or warning

Go to output window , search for 'error' in output window, TADA

Open a selected file (image, pdf, ...) programmatically from my Android Application?

directly you can use this code it will open all type of files

Intent sharingIntent = new Intent(Intent.ACTION_VIEW);
    Uri screenshotUri = Uri.fromFile(your_file);
    sharingIntent.putExtra(Intent.EXTRA_STREAM, screenshotUri);
    String type = MimeTypeMap.getSingleton().getMimeTypeFromExtension(MimeTypeMap.getFileExtensionFromUrl(screenshotUri.toString()));
    sharingIntent.setDataAndType(screenshotUri, type == null ? "text/plain" : type);
    startActivity(Intent.createChooser(sharingIntent, "Share using"));

Why does CSV file contain a blank line in between each data line when outputting with Dictwriter in Python

By default, the classes in the csv module use Windows-style line terminators (\r\n) rather than Unix-style (\n). Could this be what’s causing the apparent double line breaks?

If so, you can override it in the DictWriter constructor:

output = csv.DictWriter(open('file3.csv','w'), delimiter=',', lineterminator='\n', fieldnames=headers)

How do I get an animated gif to work in WPF?

Adding on to the main response that recommends the usage of WpfAnimatedGif, you must add the following lines in the end if you are swapping an image with a Gif to ensure the animation actually executes:

ImageBehavior.SetRepeatBehavior(img, new RepeatBehavior(0));
ImageBehavior.SetRepeatBehavior(img, RepeatBehavior.Forever);

So your code will look like:

var image = new BitmapImage();
image.UriSource = new Uri(fileName);
ImageBehavior.SetAnimatedSource(img, image);
ImageBehavior.SetRepeatBehavior(img, new RepeatBehavior(0));
ImageBehavior.SetRepeatBehavior(img, RepeatBehavior.Forever);

How to initialize a dict with keys from a list and empty value in Python?

dict.fromkeys([1, 2, 3, 4])

This is actually a classmethod, so it works for dict-subclasses (like collections.defaultdict) as well. The optional second argument specifies the value to use for the keys (defaults to None.)

How to install psycopg2 with "pip" on Python?

On macOS Mojave make sure you on newest update with Command Line Tools 10.3 - that worked for me - updated it with Software Update, previous version of Command Line Tools on Mojave did not work for me.

How to store standard error in a variable

A simple solution

{ ERROR=$(./ 2>&1 1>&$out); } {out}>&1
echo "-"
echo $ERROR

Will produce:

This Is Output
This Is Error

How to convert FormData (HTML5 object) to JSON

This post is already a year old... but, I really, really like the ES6 @dzuc answer. However it is incomplete by not been able to handle multiple selects or checkboxes. This has already pointed and code solutions has been offered. I find them heavy and not optimized. So I wrote a 2 versions based on @dzuc to handle these cases:

  • For ASP style forms where multiple items name could just simple repeated.
let r=Array.from(fd).reduce(
  (o , [k,v]) => (
     ? {...o , [k] : v}
     : {...o , [k] : [...o[k] , v]}
let obj=JSON.stringify(r);

One line Hotshot version:

  • For PHP style forms where the multiple item names must have a [] suffix.
let r=Array.from(fd).reduce(
  (o , [k,v]) => (
    ? (k=k.split('[')[0]
      , (!o[k])
      ? {...o , [k] : [v]}
      : {...o , [k] : [...o[k] , v ]}
    : {...o , [k] : v}
let obj=JSON.stringify(r);

One line Hotshot version:

  • Extension of PHP form that support multi-level arrays.

Since last time I wrote the previous second case, at work it came a case that the PHP form has checkboxes on multi-levels. I wrote a new case to support previous case and this one. I created a snippet to better showcase this case, the result show on the console for this demo, modify this to your need. Tried to optimize it the best I could without compromising performance, however, it compromise some human readability. It takes advantage that arrays are objects and variables pointing to arrays are kept as reference. No hotshot for this one, be my guest.

let nosubmit = (e) => {_x000D_
  const f = Array.from(new FormData(;_x000D_
  const obj = f.reduce((o, [k, v]) => {_x000D_
    let a = v,_x000D_
      b, i,_x000D_
      m = k.split('['),_x000D_
      n = m[0],_x000D_
      l = m.length;_x000D_
    if (l > 1) {_x000D_
      a = b = o[n] || [];_x000D_
      for (i = 1; i < l; i++) {_x000D_
        m[i] = (m[i].split(']')[0] || b.length) * 1;_x000D_
        b = b[m[i]] = ((i + 1) == l) ? v : b[m[i]] || [];_x000D_
    return { ...o, [n]: a };_x000D_
  }, {});_x000D_
document.querySelector('#theform').addEventListener('submit', nosubmit, {capture: true});
<h1>Multilevel Form</h1>_x000D_
<form action="#" method="POST" enctype="multipart/form-data" id="theform">_x000D_
  <input type="hidden" name="_id" value="93242" />_x000D_
  <input type="hidden" name="_fid" value="45c0ec96929bc0d39a904ab5c7af70ef" />_x000D_
    <select name="uselect">_x000D_
      <option value="A">A</option>_x000D_
      <option value="B">B</option>_x000D_
      <option value="C">C</option>_x000D_
  <br /><br />_x000D_
  <label>Checkboxes one level:<br/>_x000D_
    <input name="c1[]" type="checkbox" checked value="1"/>v1 _x000D_
    <input name="c1[]" type="checkbox" checked value="2"/>v2_x000D_
    <input name="c1[]" type="checkbox" checked value="3"/>v3_x000D_
  <br /><br />_x000D_
  <label>Checkboxes two levels:<br/>_x000D_
    <input name="c2[0][]" type="checkbox" checked value="4"/>0 v4 _x000D_
    <input name="c2[0][]" type="checkbox" checked value="5"/>0 v5_x000D_
    <input name="c2[0][]" type="checkbox" checked value="6"/>0 v6_x000D_
    <input name="c2[1][]" type="checkbox" checked value="7"/>1 v7 _x000D_
    <input name="c2[1][]" type="checkbox" checked value="8"/>1 v8_x000D_
    <input name="c2[1][]" type="checkbox" checked value="9"/>1 v9_x000D_
  <br /><br />_x000D_
    <input type="radio" name="uradio" value="yes">YES_x000D_
    <input type="radio" name="uradio" checked value="no">NO_x000D_
  <br /><br />_x000D_
  <input type="submit" value="Submit" />_x000D_

How to improve performance of ngRepeat over a huge dataset (angular.js)?

If all your rows have equal height, you should definitely take a look at the virtualizing ng-repeat:

This demo looks very promising (and it supports inertial scrolling)

How do I download the Android SDK without downloading Android Studio?

I downloaded Android Studio and installed it. The installer said:-

Android Studio => ( 500 MB )

Android SDK => ( 2.3 GB )

Android Studio installer is actually an "Android SDK Installer" along with a sometimes useful tool called "Android Studio".

Most importantly:- Android Studio Installer will not just install the SDK. It will also:-

  • Install the latest build-tools.
  • Install the latest platform-tools.
  • Install the latest AVD Manager which you cannot do without.

Things which you will have to do manually if you install the SDK from its zip file.

Just take it easy. Install the Android Studio.

****************************** Edit ******************************

So, being inspired by the responses in the comments I would like to update my answer.

The update is that only (and only) if 500MB of hard disk space does not matter much to you than you should go for Android Studio otherwise other answers would be better for you.

Android Studio worked for me as I had a 1TB hard disk which is 2000 times 500MB.

Also, note: that RAM sizse should not a restriction for you as you would not even be running Android Studio.

I came to this solution as I was myself stuck in this problem. I tried other answers but for some reason (maybe my in-competencies) they did not work for me. I decided to go for Android Studio and realized that it was merely 18% of the total installation and SDK was 82% of it. While I used to think otherwise. I am not deleting the answers inspite of negative rating as the answer worked for me. I might work for someone elese with a 1 TB hard disk (which is pretty common these days).

How to select min and max values of a column in a datatable?

I don't know how my solution compares performance wise to previous answers.

I understand that the initial question was: What is the fastest way to get min and max values in a DataTable object, this may be one way of doing it:

DataView view = table.DefaultView;
view.Sort = "AccountLevel";
DataTable sortedTable = view.ToTable();
int min = sortedTable.Rows[0].Field<int>("AccountLevel");
int max = sortedTable.Rows[sortedTable.Rows.Count-1].Field<int>("AccountLevel");

It's an easy way of achieving the same result without looping. But performance will need to be compared with previous answers. Thought I love Cylon Cats answer most.

How to change column order in a table using sql query in sql server 2005?

You cannot. The column order is just a "cosmetic" thing we humans care about - to SQL Server, it's almost always absolutely irrelevant.

What SQL Server Management Studio does in the background when you change column order there is recreating the table from scratch with a new CREATE TABLE command, copying over the data from the old table, and then dropping it.

There is no SQL command to define the column ordering.

Auto start print html page using javascript

<body onload="window.print()"> or window.onload = function() { window.print(); }

Allow anonymous authentication for a single folder in web.config?

To make it work I build my directory like this:

Project Public Restrict

So I edited my webconfig for my public folder:

<location path="Project/Public">
        <allow users="?"/>

And for my Restricted folder:

 <location path="Project/Restricted">
        <allow users="*"/>

See here for the spec of * and ?:

I hope I have helped.

How to write multiple conditions of if-statement in Robot Framework

You should use small caps "or" and "and" instead of OR and AND.

And beware also the spaces/tabs between keywords and arguments (you need at least two spaces).

Here is a code sample with your three keywords working fine:

Here is the file ts.txt:

  *** test cases ***
    ${color} =  set variable  Red
    Run Keyword If  '${color}' == 'Red'  log to console  \nexecuted with single condition
    Run Keyword If  '${color}' == 'Red' or '${color}' == 'Blue' or '${color}' == 'Pink'  log to console  \nexecuted with multiple or

    ${color} =  set variable  Blue
    ${Size} =  set variable  Small
    ${Simple} =  set variable  Simple
    ${Design} =  set variable  Simple
    Run Keyword If  '${color}' == 'Blue' and '${Size}' == 'Small' and '${Design}' != '${Simple}'  log to console  \nexecuted with multiple and

    ${Size} =  set variable  XL
    ${Design} =  set variable  Complicated
    Run Keyword Unless  '${color}' == 'Black' or '${Size}' == 'Small' or '${Design}' == 'Simple'  log to console  \nexecuted with unless and multiple or

and here is what I get when I execute it:

$ pybot ts.txt
mytest                                                                .
executed with single condition
executed with multiple or
executed with unless and multiple or
mytest                                                                | PASS |

How to change Visual Studio 2012,2013 or 2015 License Key?

See my UPDATE at the end, before reading the following answer.

I have windows 8 and another pc with windows 8.1

I had License error saying "Prerelease software. License expired".

The only solution that I found which is inspired by the above solutions (Thanks!) was to run process monitor and see the exact registry keys that are accessed when I start the VS2013 which were:


like what are mentioned in the previous posts. However the process monitor said that this registry is access denied.

So I opened regedit and found that registry key and I could not open it. It says I have no permission to see it.

SO I had to change its permission:

  1. Right click on the "HKCR\Licenses\E79B3F9C-6543-4897-BBA5-5BFB0A02BB5C" key
  2. Permissions
  3. Add
  4. In "Enter object names to select" I have added my windows user name. Ok.
  5. check on Full control
  6. Advanced
  7. Owner click on "Change"
  8. In "Enter object names to select" I have added my windows user name. Ok.
  9. Ok. Ok. Ok.

I found that this registry key has several sub keys, however you have to restart regedit to see them.

By seeing which other registry keys are access denied in process monitor , I knew that VS2013 will specifically deal with these subkeys which are ACCESS DENIED also: 06181 0bcad

and these subkeys should be changed their permissions as well like above.

After making these permission changes everything worked well.

The same thing has been done to Microsoft visual studio 2010 because an error in the license as well and the solution worked well.

UPDATE : It turned out that starting visual studio as administrator solved this issue without this registry massage. Seems that this happened to my pc after changing the 'required password to login' removed in the user settings. (I wanted to let the pc start running without any password after restart from a crash or anything else). This made a lot of programs not able to write into some folders like temp folders unless I start the application as admin. Even printing from excel would not work, if excel is not started as admin.

Android Studio Gradle DSL method not found: 'android()' -- Error(17,0)

Change to root build.gradle file


// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
    dependencies {
        classpath ''

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files

allprojects {
    repositories {

task clean(type: Delete) {
    delete rootProject.buildDir

Django set default form values

Other solution: Set initial after creating the form:

form.fields['tank'].initial = 123

How to uninstall a Windows Service when there is no executable for it left on the system?

Create a copy of executables of same service and paste it on the same path of the existing service and then uninstall.

CardView Corner Radius

You can put your ImageView inside a CardView, and add those properties to the ImageView:


That way you will get rid of the rounded bottom corner, but keep in mind that this comes in the price of having a small portion of your image cut off.

Run java jar file on a server as background process

Systemd which now runs in the majority of distros

Step 1:

Find your user defined services mine was at /usr/lib/systemd/system/

Step 2:

Create a text file with your favorite text editor name it whatever_you_want.service

Step 3:

Put following Template to the file whatever_you_want.service

Description=webserver Daemon

ExecStart=/usr/bin/java -jar /web/server.jar


Step 4:

Run your service
as super user

$ systemctl start whatever_you_want.service # starts the service
$ systemctl enable whatever_you_want.service # auto starts the service
$ systemctl disable whatever_you_want.service # stops autostart
$ systemctl stop whatever_you_want.service # stops the service
$ systemctl restart whatever_you_want.service # restarts the service

Multipart forms from C# client

A little optimization of the class before. In this version the files are not totally loaded into memory.

Security advice: a check for the boundary is missing, if the file contains the bounday it will crash.

namespace WindowsFormsApplication1
    public static class FormUpload
        private static string NewDataBoundary()
            Random rnd = new Random();
            string formDataBoundary = "";
            while (formDataBoundary.Length < 15)
                formDataBoundary = formDataBoundary + rnd.Next();
            formDataBoundary = formDataBoundary.Substring(0, 15);
            formDataBoundary = "-----------------------------" + formDataBoundary;
            return formDataBoundary;

        public static HttpWebResponse MultipartFormDataPost(string postUrl, IEnumerable<Cookie> cookies, Dictionary<string, string> postParameters)
            string boundary = NewDataBoundary();

            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(postUrl);

            // Set up the request properties
            request.Method = "POST";
            request.ContentType = "multipart/form-data; boundary=" + boundary;
            request.UserAgent = "PhasDocAgent 1.0";
            request.CookieContainer = new CookieContainer();

            foreach (var cookie in cookies)

            #region WRITING STREAM
            using (Stream formDataStream = request.GetRequestStream())
                foreach (var param in postParameters)
                    if (param.Value.StartsWith("file://"))
                        string filepath = param.Value.Substring(7);

                        // Add just the first part of this param, since we will write the file data directly to the Stream
                        string header = string.Format("--{0}\r\nContent-Disposition: form-data; name=\"{1}\"; filename=\"{2}\";\r\nContent-Type: {3}\r\n\r\n",
                            Path.GetFileName(filepath) ?? param.Key,

                        formDataStream.Write(Encoding.UTF8.GetBytes(header), 0, header.Length);

                        // Write the file data directly to the Stream, rather than serializing it to a string.

                        byte[] buffer = new byte[2048];

                        FileStream fs = new FileStream(filepath, FileMode.Open);

                        for (int i = 0; i < fs.Length; )
                            int k = fs.Read(buffer, 0, buffer.Length);
                            if (k > 0)
                                formDataStream.Write(buffer, 0, k);
                            i = i + k;
                        string postData = string.Format("--{0}\r\nContent-Disposition: form-data; name=\"{1}\"\r\n\r\n{2}\r\n",
                        formDataStream.Write(Encoding.UTF8.GetBytes(postData), 0, postData.Length);
                // Add the end of the request
                byte[] footer = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");
                formDataStream.Write(footer, 0, footer.Length);
                request.ContentLength = formDataStream.Length;

            return request.GetResponse() as HttpWebResponse;

ImportError: No module named 'google'

I could fix it by installing the following directly.

pip install
pip install

When to use static keyword before global variables?

You should not define global variables in header files. You should define them in .c source file.

  • If global variable is to be visible within only one .c file, you should declare it static.

  • If global variable is to be used across multiple .c files, you should not declare it static. Instead you should declare it extern in header file included by all .c files that need it.


  • example.h

    extern int global_foo;
  • foo.c

    #include "example.h"
    int global_foo = 0;
    static int local_foo = 0;
    int foo_function()
       /* sees: global_foo and local_foo
          cannot see: local_bar  */
       return 0;
  • bar.c

    #include "example.h"
    static int local_bar = 0;
    static int local_foo = 0;
    int bar_function()
        /* sees: global_foo, local_bar */
        /* sees also local_foo, but it's not the same local_foo as in foo.c
           it's another variable which happen to have the same name.
           this function cannot access local_foo defined in foo.c
        return 0;

How To Execute SSH Commands Via PHP

I would use phpseclib, a pure PHP SSH implementation. An example:


$ssh = new Net_SSH2('www.domain.tld');
if (!$ssh->login('username', 'password')) {
    exit('Login Failed');

echo $ssh->exec('pwd');
echo $ssh->exec('ls -la');

"Not allowed to load local resource: file:///C:....jpg" Java EE Tomcat

This error means you can not directly load data from file system because there are security issues behind this. The only solution that I know is create a web service to serve load files.

Syntax of for-loop in SQL Server

How about this:

   Do Something
GO 10

... of course you could put an incremental counter inside it if you need to count.

ERROR 1064 (42000) in MySQL

I ran into this once - for me, deleting all the commented out lines at the beginning of my dump file is what fixed the problem. Looks like it was a whitespace error.

If Else in LINQ

I assume from db that this is LINQ-to-SQL / Entity Framework / similar (not LINQ-to-Objects);

Generally, you do better with the conditional syntax ( a ? b : c) - however, I don't know if it will work with your different queries like that (after all, how would your write the TSQL?).

For a trivial example of the type of thing you can do:

select new {p.PriceID, Type = p.Price > 0 ? "debit" : "credit" };

You can do much richer things, but I really doubt you can pick the table in the conditional. You're welcome to try, of course...

jQuery getTime function

You don't need jquery to do that, just javascript. For example, you can do a timer using this:

<body onload="clock();">

<script type="text/javascript">
function clock() {
   var now = new Date();
   var outStr = now.getHours()+':'+now.getMinutes()+':'+now.getSeconds();

<div id="clockDiv"></div>


You can view a complete reference here:

Why use multiple columns as primary keys (composite primary key)

We create composite primary keys to guarantee the uniqueness column values which compose a single record. It is a constraint which helps prevent insertion of data which should not be duplicated.

i.e: If all student Ids and birth certificate numbers are uniquely assigned to a single person. Then it would be a good idea to make the primary key for a person a composition of student id and birth certificate number because it would prevent you from accidentally inserting two people who have different student ids and the same birth certificate.

Simulate limited bandwidth from within Chrome?

if you're not familiar with Fiddler - please do. It's a great debugging tool for HTTP. You also have the option to limit the bandwidth.

AWK to print field $2 first, then field $1

The awk is ok. I'm guessing the file is from a windows system and has a CR (^m ascii 0x0d) on the end of the line.

This will cause the cursor to go to the start of the line after $2.

Use dos2unix or vi with :se ff=unix to get rid of the CRs.

How to remove a class from elements in pure JavaScript?

elements is an array of DOM objects. You should do something like this

for (var i = 0; i < elements.length; i++) {

ie: enumerate the elements collection, and for each element inside the collection call the remove method

installing cPickle with python 3.5

cPickle comes with the standard library… in python 2.x. You are on python 3.x, so if you want cPickle, you can do this:

>>> import _pickle as cPickle

However, in 3.x, it's easier just to use pickle.

No need to install anything. If something requires cPickle in python 3.x, then that's probably a bug.

how to convert `content://media/external/images/media/Y` to `file:///storage/sdcard0/Pictures/X.jpg` in android?

Will something like this work for you? What this does is query the content resolver to find the file path data that is stored for that content entry

public static String getRealPathFromUri(Context context, Uri contentUri) {
    Cursor cursor = null;
    try {
        String[] proj = { MediaStore.Images.Media.DATA };
        cursor = context.getContentResolver().query(contentUri, proj, null, null, null);
        int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
        return cursor.getString(column_index);
    } finally {
        if (cursor != null) {

This will end up giving you an absolute file path that you can construct a file uri from

repository element was not specified in the POM inside distributionManagement element or in -DaltDep loymentRepository=id::layout::url parameter

The issue is fixed by adding repository url under distributionManagement tab in main pom.xml.

Jenkin maven goal : clean deploy -U -Dmaven.test.skip=true


Spring MVC @PathVariable with dot (.) is getting truncated

adding the ":.+" worked for me, but not until I removed outer curly brackets.

value = {"/username/{id:.+}"} didn't work

value = "/username/{id:.+}" works

Hope I helped someone :)

How to close IPython Notebook properly?

Actually, I believe there's a cleaner way than killing the process(es) using kill or task manager.

In the Jupyter Notebook Dashboard (the browser interface you see when you first launch 'jupyter notebook'), browse to the location of notebook files you have closed in the browser, but whose kernels may still be running.

iPython Notebook files appear with a book icon, shown in green if it has a running kernel, or gray if the kernel is not running.

Just select the tick box next to the running file, then click on the Shutdown button that appears above it.

This will properly shut down the kernel associated with that specific notebook.

How to set the 'selected option' of a select dropdown list with jquery

You have to replace YourID and value="3" for your current ones.

$(document).ready(function() {_x000D_
  $('#YourID option[value="3"]').attr("selected", "selected");_x000D_
<script src=""></script>_x000D_
<select id="YourID">_x000D_
  <option value="1">A</option>_x000D_
  <option value="2">B</option>_x000D_
  <option value="3">C</option>_x000D_
  <option value="4">D</option>_x000D_

and value="3" for your current ones.

$('#YourID option[value="3"]').attr("selected", "selected");

<select id="YourID" >
<option value="1">A </option>
<option value="2">B</option>
<option value="3">C</option>
<option value="4">D</option>

Sorting list based on values from another list

more_itertools has a tool for sorting iterables in parallel:


from more_itertools import sort_together

X = ["a", "b", "c", "d", "e", "f", "g", "h", "i"]
Y = [ 0,   1,   1,    0,   1,   2,   2,   0,   1]


sort_together([Y, X])[1]
# ('a', 'd', 'h', 'b', 'c', 'e', 'i', 'f', 'g')

Adding rows to tbody of a table using jQuery

use this

$("#tblEntAttributes tbody").append(newRowContent);

Is there a maximum number you can set Xmx to when trying to increase jvm memory?

I think that it's around 2GB. While the answer by Pete Kirkham is very interesting and probably holds truth, I have allocated upwards of 3GB without error, however it did not use 3GB in practice. That might explain why you were able to allocate 2.5 GB on 2GB RAM with no swap space. In practice, it wasn't using 2.5GB.

Fill username and password using selenium in python

user = driver.find_element_by_name("username")
password = driver.find_element_by_name("password")


  • we useuser.clear() in order to clear the input field.
  • for locating submit button you can use any other method based on the page source code. for info see locating elements

find without recursion

If you look for POSIX compliant solution:

cd DirsRoot && find . -type f -print -o -name . -o -prune

-maxdepth is not POSIX compliant option.

Checking something isEmpty in Javascript?

what am I missing if empty array... keyless object... falseness const isEmpty = o => Array.isArray(o) && !o.join('').length || typeof o === 'object' && !Object.keys(o).length || !(+value);

Java JTable setting Column Width

Use this method

public static void setColumnWidths(JTable table, int... widths) {
    TableColumnModel columnModel = table.getColumnModel();
    for (int i = 0; i < widths.length; i++) {
        if (i < columnModel.getColumnCount()) {
        else break;

Or extend the JTable class:

public class Table extends JTable {
    public void setColumnWidths(int... widths) {
        for (int i = 0; i < widths.length; i++) {
            if (i < columnModel.getColumnCount()) {
            else break;

And then

table.setColumnWidths(30, 150, 100, 100);

Uninstall / remove a Homebrew package including all its dependencies

Save the following script as brew-purge

#:Usage: brew purge formula
#:Removes the package and all dependancies.
if [ -z "$PKG" ];then
   brew purge --help
   exit 1
brew rm $PKG
[ $? -ne 0 ] && exit 1
while brew rm $(join <(brew leaves) <(brew deps $PKG)) 2>/dev/null
  do :
echo Package $PKG and its dependancies have been removed.
exit 0

Now install it with the following command

sudo install brew-purge /usr/local/bin

Now run it

brew purge package

Example using gpg

$ brew purge gpg
Uninstalling /usr/local/Cellar/gnupg/2.2.13... (134 files, 11.0MB)
Uninstalling /usr/local/Cellar/adns/1.5.1... (14 files, 597.5KB)
Uninstalling /usr/local/Cellar/gnutls/3.6.6... (1,200 files, 8.9MB)
Uninstalling /usr/local/Cellar/libgcrypt/1.8.4... (21 files, 2.6MB)
Uninstalling /usr/local/Cellar/libksba/1.3.5... (14 files, 344.2KB)
Uninstalling /usr/local/Cellar/libusb/1.0.22... (29 files, 508KB)
Uninstalling /usr/local/Cellar/npth/1.6... (11 files, 71.7KB)
Uninstalling /usr/local/Cellar/pinentry/1.1.0_1... (12 files, 263.9KB)
Uninstalling /usr/local/Cellar/libassuan/2.5.3... (16 files, 444.2KB)
Uninstalling /usr/local/Cellar/libtasn1/4.13... (59 files, 436KB)
Uninstalling /usr/local/Cellar/libunistring/0.9.10... (54 files, 4.4MB)
Uninstalling /usr/local/Cellar/nettle/3.4.1... (85 files, 2MB)
Uninstalling /usr/local/Cellar/p11-kit/0.23.15... (63 files, 2.9MB)
Uninstalling /usr/local/Cellar/gmp/6.1.2_2... (18 files, 3.1MB)
Uninstalling /usr/local/Cellar/libffi/3.2.1... (16 files, 296.8KB)
Uninstalling /usr/local/Cellar/libgpg-error/1.35... (27 files, 854.8KB)
Package gpg and its dependancies have been removed.

Dynamically load a JavaScript file

all the major javascript libraries like jscript, prototype, YUI have support for loading script files. For example, in YUI, after loading the core you can do the following to load the calendar control

var loader = new YAHOO.util.YUILoader({

    require: ['calendar'], // what components?

    base: '../../build/',//where do they live?

    //filter: "DEBUG",  //use debug versions (or apply some
                        //some other filter?

    //loadOptional: true, //load all optional dependencies?

    //onSuccess is the function that YUI Loader
    //should call when all components are successfully loaded.
    onSuccess: function() {
        //Once the YUI Calendar Control and dependencies are on
        //the page, we'll verify that our target container is 
        //available in the DOM and then instantiate a default
        //calendar into it:
        YAHOO.util.Event.onAvailable("calendar_container", function() {
            var myCal = new YAHOO.widget.Calendar("mycal_id", "calendar_container");

    // should a failure occur, the onFailure function will be executed
    onFailure: function(o) {
        alert("error: " + YAHOO.lang.dump(o));


// Calculate the dependency and insert the required scripts and css resources
// into the document

HTTP Basic Authentication credentials passed in URL and encryption

Yes, it will be encrypted.

You'll understand it if you simply check what happens behind the scenes.

  1. The browser or application will first break down the URL and try to get the IP of the host using a DNS Query. ie: A DNS request will be made to find the IP address of the domain ( Please note that no other information will be sent via this request.
  2. The browser or application will initiate a SSL connection with the IP address received from the DNS request. Certificates will be exchanged and this happens at the transport level. No application level information will be transferred at this point. Remember that the Basic authentication is part of HTTP and HTTP is an application level protocol. Not a transport layer task.
  3. After establishing the SSL connection, now the necessary data will be passed to the server. ie: The path or the URL, the parameters and basic authentication username and password.

public static const in TypeScript

Meanwhile this can be solved through a decorator in combination with Object.freeze or Object.defineProperty, I'm using this, it's a little bit prettier than using tons of getters. You can copy/paste this directly TS Playground to see it in action. - There are two options

Make individual fields "final"

The following decorator converts both, annotated static and non-static fields to "getter-only-properties".

Note: If an instance-variable with no initial value is annotated @final, then the first assigned value (no matter when) will be the final one.

// example
class MyClass {
    public finalProp: string = "You shall not change me!";

    public static FINAL_FIELD: number = 75;

    public static NON_FINAL: string = "I am not final."

var myInstance: MyClass = new MyClass();
myInstance.finalProp = "Was I changed?";
MyClass.FINAL_FIELD = 123;
MyClass.NON_FINAL = "I was changed.";

console.log(myInstance.finalProp);  // => You shall not change me!
console.log(MyClass.FINAL_FIELD);   // => 75
console.log(MyClass.NON_FINAL);     // => I was changed.

The Decorator: Make sure you include this in your code!

* Turns static and non-static fields into getter-only, and therefor renders them "final".
* To use simply annotate the static or non-static field with: @final
function final(target: any, propertyKey: string) {
    const value: any = target[propertyKey];
    // if it currently has no value, then wait for the first setter-call
    // usually the case with non-static fields
    if (!value) {
        Object.defineProperty(target, propertyKey, {
            set: function (value: any) {
                Object.defineProperty(this, propertyKey, {
                    get: function () {
                        return value;
                    enumerable: true,
                    configurable: false
            enumerable: true,
            configurable: true
    } else { // else, set it immediatly
        Object.defineProperty(target, propertyKey, {
            get: function () {
                return value;
            enumerable: true

As an alternative to the decorator above, there would also be a strict version of this, which would even throw an Error when someone tried to assign some value to the field with "use strict"; being set. (This is only the static part though)

 * Turns static fields into getter-only, and therefor renders them "final".
 * Also throws an error in strict mode if the value is tried to be touched.
 * To use simply annotate the static field with: @strictFinal
function strictFinal(target: any, propertyKey: string) {
    Object.defineProperty(target, propertyKey, {
        value: target[propertyKey],
        writable: false,
        enumerable: true

Make every static field "final"

Possible Downside: This will only work for ALL statics of that class or for none, but cannot be applied to specific statics.

* Freezes the annotated class, making every static 'final'.
* Usage:
* @StaticsFinal
* class MyClass {
*      public static SOME_STATIC: string = "SOME_STATIC";
*      //...
* }
function StaticsFinal(target: any) {
// Usage here
class FreezeMe {
    public static FROZEN_STATIC: string = "I am frozen";

class EditMyStuff {
    public static NON_FROZEN_STATIC: string = "I am frozen";

// Test here
FreezeMe.FROZEN_STATIC = "I am not frozen.";
EditMyStuff.NON_FROZEN_STATIC = "I am not frozen.";

console.log(FreezeMe.FROZEN_STATIC); // => "I am frozen."
console.log(EditMyStuff.NON_FROZEN_STATIC); // => "I am not frozen."

Possible reason for NGINX 499 error codes

Client closed the connection doesn't mean it's a browser issue!? Not at all!

You can find 499 errors in a log file if you have a LB (load balancer) in front of your webserver (nginx) either AWS or haproxy (custom). That said the LB will act as a client to nginx.

If you run haproxy default values for:

    timeout client  60000
    timeout server  60000

That would mean that LB will time out after 60000ms if there is no respond from nginx. Time outs might happen for busy websites or scripts that need more time for execution. You'll need to find timeout that will work for you. For example extend it to:

    timeout client  180s
    timeout server  180s

And you will be probably set.

Depending on your setup you might see a 504 gateway timeout error in your browser which indicates that something is wrong with php-fpm but that will not be the case with 499 errors in your log files.

Check if application is on its first run

The following is an example of using SharedPreferences to achieve a 'forWhat' check.

    preferences = PreferenceManager.getDefaultSharedPreferences(context);
    preferencesEditor = preferences.edit();
public static boolean isFirstRun(String forWhat) {
    if (preferences.getBoolean(forWhat, true)) {
        preferencesEditor.putBoolean(forWhat, false).commit();
        return true;
    } else {
        return false;

In Python, can I call the main() of an imported module?

Martijen's answer makes sense, but it was missing something crucial that may seem obvious to others but was hard for me to figure out.

In the version where you use argparse, you need to have this line in the main body.

args = parser.parse_args(args)

Normally when you are using argparse just in a script you just write

args = parser.parse_args()

and parse_args find the arguments from the command line. But in this case the main function does not have access to the command line arguments, so you have to tell argparse what the arguments are.

Here is an example

import argparse
import sys

def x(x_center, y_center):
    print "X center:", x_center
    print "Y center:", y_center

def main(args):
    parser = argparse.ArgumentParser(description="Do something.")
    parser.add_argument("-x", "--xcenter", type=float, default= 2, required=False)
    parser.add_argument("-y", "--ycenter", type=float, default= 4, required=False)
    args = parser.parse_args(args)
    x(args.xcenter, args.ycenter)

if __name__ == '__main__':

Assuming you named this To run it you can either do any of these from the command line

python ./ -x 8
python ./ -x 8 -y 2
python ./ 

which returns respectively

X center: 8.0
Y center: 4


X center: 8.0
Y center: 2.0


X center: 2
Y center: 4

Or if you want to run from another python script you can do

import mytest

which returns

X center: 7.0
Y center: 6.0

What is the difference between `sorted(list)` vs `list.sort()`?

sorted() returns a new sorted list, leaving the original list unaffected. list.sort() sorts the list in-place, mutating the list indices, and returns None (like all in-place operations).

sorted() works on any iterable, not just lists. Strings, tuples, dictionaries (you'll get the keys), generators, etc., returning a list containing all elements, sorted.

  • Use list.sort() when you want to mutate the list, sorted() when you want a new sorted object back. Use sorted() when you want to sort something that is an iterable, not a list yet.

  • For lists, list.sort() is faster than sorted() because it doesn't have to create a copy. For any other iterable, you have no choice.

  • No, you cannot retrieve the original positions. Once you called list.sort() the original order is gone.

How do I space out the child elements of a StackPanel?

sometimes you need to set Padding, not Margin to make space between items smaller than default

Python method for reading keypress?

I was also trying to achieve this. From above codes, what I understood was that you can call getch() function multiple times in order to get both bytes getting from the function. So the ord() function is not necessary if you are just looking to use with byte objects.

while True :
    if m.kbhit() :
        k = m.getch()
        if b'\r' == k :
        elif k == b'\x08'or k == b'\x1b':
            # b'\x08' => BACKSPACE
            # b'\x1b' => ESC
        elif k == b'\xe0' or k == b'\x00':
            k = m.getch()
            if k in [b'H',b'M',b'K',b'P',b'S',b'\x08']:
                # b'H' => UP ARROW
                # b'M' => RIGHT ARROW
                # b'K' => LEFT ARROW
                # b'P' => DOWN ARROW
                # b'S' => DELETE

This code will work print any key until enter key is pressed in CMD or IDE (I was using VS CODE) You can customize inside the if for specific keys if needed

Use Device Login on Smart TV / Console

Facebook login for smarttv/devices without facebook sdk is possible throught code , check the documentation here :

Copy rows from one Datatable to another DataTable?

For those who want single command SQL query for that:


This query will copy data from TABLE001 to TABLE002 and we assume that both columns had different column names.

Column names are mapped one-to-one like:






You can also specify where clause, if you need some condition.

Unity Scripts edited in Visual studio don't provide autocomplete

I solved to install the same version of .NET on WIN that was configured in my Unity project. (Player Settings)

How to configure "Shorten command line" method for whole project in IntelliJ

Inside your .idea folder, change workspace.xml file


<property name="dynamic.classpath" value="true" />


  <component name="PropertiesComponent">


 <component name="PropertiesComponent">
    <property name="project.structure.last.edited" value="Project" />
    <property name="project.structure.proportion" value="0.0" />
    <property name="project.structure.side.proportion" value="0.0" />
    <property name="settings.editor.selected.configurable" value="preferences.pluginManager" />
    <property name="dynamic.classpath" value="true" />

If you don't see one, feel free to add it yourself

 <component name="PropertiesComponent">
    <property name="dynamic.classpath" value="true" />

Comparing strings, c++

string cat = "cat";
string human = "human";

cout << << endl; 

This code will give -1 as a result. This is due to the first non-matching character of the compared string 'h' is lower or appears after 'c' in alphabetical order, even though the compared string, 'human' is longer than 'cat'.

I find the return value described in is more accurate which are-:

0 : They compare equal

<0 : Either the value of the first character that does not match is lower in the compared string, or all compared characters match but the compared string is shorter.

more than 0 : Either the value of the first character that does not match is greater in the compared string, or all compared characters match but the compared string is longer.

Moreover, IMO's description is simpler and so far best describe to my own experience.

negative value if *this appears before the character sequence specified by the arguments, in lexicographical order

zero if both character sequences compare equivalent

positive value if *this appears after the character sequence specified by the arguments, in lexicographical order

In Javascript, how to conditionally add a member to an object?

Using spread syntax with boolean (as suggested here) is not valid syntax. Spread can only be use with iterables.

I suggest the following:

const a = {
   ...(someCondition? {b: 5}: {} )

LINQ: Select where object does not contain items from list

dump this into a more specific collection of just the ids you don't want

var notTheseBarIds = filterBars.Select(fb => fb.BarId);

then try this:

fooSelect = (from f in fooBunch
             where !notTheseBarIds.Contains(f.BarId)
             select f).ToList();

or this:

fooSelect = fooBunch.Where(f => !notTheseBarIds.Contains(f.BarId)).ToList();

Less aggressive compilation with CSS3 calc

There is several escaping options with same result:

body { width: ~"calc(100% - 250px - 1.5em)"; }
body { width: calc(~"100% - 250px - 1.5em"); }
body { width: calc(100% ~"-" 250px ~"-" 1.5em); }

How to use Lambda in LINQ select statement

You appear to be trying to mix query expression syntax and "normal" lambda expression syntax. You can either use:

IEnumerable<SelectListItem> stores =
        from store in database.Stores
        where store.CompanyID == curCompany.ID
        select new SelectListItem { Value = store.Name, Text = store.ID};
ViewBag.storeSelector = stores;


IEnumerable<SelectListItem> stores = database.Stores
        .Where(store => store.CompanyID == curCompany.ID)
        .Select(s => new SelectListItem { Value = s.Name, Text = s.ID});
ViewBag.storeSelector = stores;

You can't mix the two like you're trying to.

Return value from exec(@sql)

If i understand you correctly, (i probably don't)

'SELECT @RowCount = COUNT(*)
                   FROM dbo.Comm_Services
                   WHERE CompanyId = ' + CAST(@CompanyId AS CHAR) + '
                   AND ' + @condition

Prevent any form of page refresh using jQuery/Javascript

Back in the ole days of CGI we had many forms that would trigger various backend actions. Such as text notifications to groups, print jobs, farming of data, etc.

If the user was on a page that was saying "Please wait... Performing some HUGE job that could take some time.". They were more likely to hit REFRESH and this would be BAD!

WHY? Because it would trigger more slow jobs and eventually bog down the whole thing.

The solution? Allow them to do their form. When they submit their form... Start your job and then direct them to another page that tells them to wait.

Where the page in the middle actually held the form data that was needed to start the job. The WAIT page however contains a javascript history destroy. So they can RELOAD that wait page all they want and it will never trigger the original job to start in the background as that WAIT page only contains the form data needed for the WAIT itself.

Hope that makes sense.

The history destroy function also prevented them from clicking BACK and then refreshing as well.

It was very seamless and worked great for MANY MANY years until the non-profit was wound down.

Example: FORM ENTRY - Collect all their info and when submitted, this triggers your backend job.

RESPONSE from form entry - Returns HTML that performs a redirect to your static wait page and/or POST/GET to another form (the WAIT page).

WAIT PAGE - Only contains FORM data related to wait page as well as javascript to destroy the most recent history. Like (-1 OR -2) to only destroy the most recent pages, but still allows them to go back to their original FORM entry page.

Once they are at your WAIT page, they can click REFRESH as much as they want and it will never spawn the original FORM job on the backend. Instead, your WAIT page should embrace a META timed refresh itself so it can always check on the status of their job. When their job is completed, they are redirected away from the wait page to whereever you wish.

If they do manually REFRESH... They are simply adding one more check of their job status in there.

Hope that helps. Good luck.

With CSS, how do I make an image span the full width of the page as a background image?

Background images, ideally, are always done with CSS. All other images are done with html. This will span the whole background of your site.

body {
  background: url('../images/');
  background-size: cover;
  background-position: center;
  background-attachment: fixed;

Convert String array to ArrayList

String[] words= new String[]{"ace","boom","crew","dog","eon"};
List<String> wordList = Arrays.asList(words);

Why shouldn't I use "Hungarian Notation"?

If you don't know the type of a variable without being told, you probably shouldn't be messing with it anyways

The type might also not be that important. If you know what the methods do, you can figure out what is being done with the variable and then you'll what the program is doing

There may be times you want it; when type is important and the declaration isn't near or the type can't be inferred with ease. But it should never be seen as absolute

How to enter command with password for git pull?

This is not exactly what you asked for, but for http(s):

  • you can put the password in .netrc file (_netrc on windows). From there it would be picked up automatically. It would go to your home folder with 600 permissions.
  • you could also just clone the repo with https://user:pass@domain/repo but that's not really recommended as it would show your user/pass in a lot of places...
  • a new option is to use the credential helper. Note that credentials would be stored in clear text in your local config using standard credential helper. credential-helper with wincred can be also used on windows.

Usage examples for credential helper

  • git config credential.helper store - stores the credentials indefinitely.
  • git config credential.helper 'cache --timeout=3600'- stores for 60 minutes

For ssh-based access, you'd use ssh agent that will provide the ssh key when needed. This would require generating keys on your computer, storing the public key on the remote server and adding the private key to relevant keystore.

Android Studio installation on Windows 7 fails, no JDK found

I've tried so many of the answers here but none of them works, so I decided to mix some of the answers here and I am successful!

Successtully running android

Step 1: Go to the system properties by right-clicking on My Computer or by pressing windows button on typing This PC and right clicking on it and selecting Properties.

enter image description here

Step 2: Click the advanced system settings or Environment Variables

Step 3: Take note that there are 2 different variable. What you need to create is system variables not user variables, when you clicked new type the following

Variable name: JAVA_HOME

Variable value: C:\Program Files\Java\jdk1.8.0_25\ (Note: Please check if the path is right, sometimes it is C:\Program Files (x86)\Java\jdk1.8.0_25)

Step 4: Run the android studio, no need to restart.


*C:\Program Files\Java\jdk1.8.0_25\ depends entirely on the installation path of your JDK not JRE so don't be confused if you see something like the picture below. Just enter the location of your jdk, in my case it is C:\Program Files\Java\jdk1.8.0_25\.

*Do not include the bin folder when you enter the Variable value.

enter image description here

enter image description here

Edit: For Windows 8 and 10 Users: Try to run C:\Program Files\Android\Android Studio\bin\studio.exe instead of C:\Program Files\Android\Android Studio\binstudio64.exe

How to determine if a type implements an interface with C# reflection

Anyone searching for this might find the following extension method useful:

public static class TypeExtensions
    public static bool ImplementsInterface(this Type type, Type @interface)
        if (type == null)
            throw new ArgumentNullException(nameof(type));

        if (@interface == null)
            throw new ArgumentNullException(nameof(@interface));

        var interfaces = type.GetInterfaces();
        if (@interface.IsGenericTypeDefinition)
            foreach (var item in interfaces)
                if (item.IsConstructedGenericType && item.GetGenericTypeDefinition() == @interface)
                    return true;
            foreach (var item in interfaces)
                if (item == @interface)
                    return true;

        return false;

xunit tests:

public class TypeExtensionTests
    [InlineData(typeof(string), typeof(IList<int>), false)]
    [InlineData(typeof(List<>), typeof(IList<int>), false)]
    [InlineData(typeof(List<>), typeof(IList<>), true)]
    [InlineData(typeof(List<int>), typeof(IList<>), true)]
    [InlineData(typeof(List<int>), typeof(IList<int>), true)]
    [InlineData(typeof(List<int>), typeof(IList<string>), false)]
    public void ValidateTypeImplementsInterface(Type type, Type @interface, bool expect)
        var output = type.ImplementsInterface(@interface);
        Assert.Equal(expect, output);

CSV new-line character seen in unquoted field error

Try to run dos2unix on your windows imported files first

Spring Boot: Cannot access REST Controller on localhost (404)

Adding to MattR's answer:

As stated in here, @SpringBootApplication automatically inserts the needed annotations: @Configuration, @EnableAutoConfiguration, and also @ComponentScan; however, the @ComponentScan will only look for the components in the same package as the App, in this case your com.nice.application, whereas your controller resides in com.nice.controller. That's why you get 404 because the App didn't find the controller in the application package.

How to disable PHP Error reporting in CodeIgniter?

Here is the typical structure of new Codeigniter project:

- application/
- system/
- user_guide/
- index.php <- this is the file you need to change

I usually use this code in my CI index.php. Just change local_server_name to the name of your local webserver.

With this code you can deploy your site to your production server without changing index.php each time.

// Domain-based environment
if ($_SERVER['SERVER_NAME'] == 'local_server_name') {
    define('ENVIRONMENT', 'development');
} else {
    define('ENVIRONMENT', 'production');

 * Different environments will require different levels of error reporting.
 * By default development will show errors but testing and live will hide them.

if (defined('ENVIRONMENT')) {
    switch (ENVIRONMENT) {
        case 'development':
        case 'testing':
        case 'production':
            ini_set('display_errors', 0);  
            exit('The application environment is not set correctly.');

How to include view/partial specific styling in AngularJS

I know this question is old now, but after doing a ton of research on various solutions to this problem, I think I may have come up with a better solution.

UPDATE 1: Since posting this answer, I have added all of this code to a simple service that I have posted to GitHub. The repo is located here. Feel free to check it out for more info.

UPDATE 2: This answer is great if all you need is a lightweight solution for pulling in stylesheets for your routes. If you want a more complete solution for managing on-demand stylesheets throughout your application, you may want to checkout Door3's AngularCSS project. It provides much more fine-grained functionality.

In case anyone in the future is interested, here's what I came up with:

1. Create a custom directive for the <head> element:

app.directive('head', ['$rootScope','$compile',
    function($rootScope, $compile){
        return {
            restrict: 'E',
            link: function(scope, elem){
                var html = '<link rel="stylesheet" ng-repeat="(routeCtrl, cssUrl) in routeStyles" ng-href="{{cssUrl}}" />';
                scope.routeStyles = {};
                $rootScope.$on('$routeChangeStart', function (e, next, current) {
                    if(current && current.$$route && current.$$route.css){
                            current.$$route.css = [current.$$route.css];
                        angular.forEach(current.$$route.css, function(sheet){
                            delete scope.routeStyles[sheet];
                    if(next && next.$$route && next.$$route.css){
                            next.$$route.css = [next.$$route.css];
                        angular.forEach(next.$$route.css, function(sheet){
                            scope.routeStyles[sheet] = sheet;

This directive does the following things:

  1. It compiles (using $compile) an html string that creates a set of <link /> tags for every item in the scope.routeStyles object using ng-repeat and ng-href.
  2. It appends that compiled set of <link /> elements to the <head> tag.
  3. It then uses the $rootScope to listen for '$routeChangeStart' events. For every '$routeChangeStart' event, it grabs the "current" $$route object (the route that the user is about to leave) and removes its partial-specific css file(s) from the <head> tag. It also grabs the "next" $$route object (the route that the user is about to go to) and adds any of its partial-specific css file(s) to the <head> tag.
  4. And the ng-repeat part of the compiled <link /> tag handles all of the adding and removing of the page-specific stylesheets based on what gets added to or removed from the scope.routeStyles object.

Note: this requires that your ng-app attribute is on the <html> element, not on <body> or anything inside of <html>.

2. Specify which stylesheets belong to which routes using the $routeProvider:

app.config(['$routeProvider', function($routeProvider){
        .when('/some/route/1', {
            templateUrl: 'partials/partial1.html', 
            controller: 'Partial1Ctrl',
            css: 'css/partial1.css'
        .when('/some/route/2', {
            templateUrl: 'partials/partial2.html',
            controller: 'Partial2Ctrl'
        .when('/some/route/3', {
            templateUrl: 'partials/partial3.html',
            controller: 'Partial3Ctrl',
            css: ['css/partial3_1.css','css/partial3_2.css']

This config adds a custom css property to the object that is used to setup each page's route. That object gets passed to each '$routeChangeStart' event as .$$route. So when listening to the '$routeChangeStart' event, we can grab the css property that we specified and append/remove those <link /> tags as needed. Note that specifying a css property on the route is completely optional, as it was omitted from the '/some/route/2' example. If the route doesn't have a css property, the <head> directive will simply do nothing for that route. Note also that you can even have multiple page-specific stylesheets per route, as in the '/some/route/3' example above, where the css property is an array of relative paths to the stylesheets needed for that route.

3. You're done Those two things setup everything that was needed and it does it, in my opinion, with the cleanest code possible.

Hope that helps someone else who might be struggling with this issue as much as I was.

How to obtain the number of CPUs/cores in Linux from the command line?

Use below query to get core details

[oracle@orahost](TESTDB)$ grep -c ^processor /proc/cpuinfo

How to render pdfs using C#

PdfiumViewer is great, but relatively tightly coupled to System.Drawingand WinForms. For this reason I created my own wrapper around PDFium: PDFiumSharp

Pages can be rendered to a PDFiumBitmap which in turn can be saved to disk or exposed as a stream. This way any framework capable of loading an image in BMP format from a stream can use this library to display pdf pages.

For example in a WPF application you could use the following method to render a pdf page:

using System.Linq;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using PDFiumSharp;

static class PdfRenderer
    public static ImageSource RenderPage(string filename, int pageIndex, string password = null, bool withTransparency = true)
        using (var doc = new PdfDocument(filename, password))
            var page = doc.Pages[pageIndex];
            using (var bitmap = new PDFiumBitmap((int)page.Width, (int)page.Height, withTransparency))
                return new BmpBitmapDecoder(bitmap.AsBmpStream(), BitmapCreateOptions.None, BitmapCacheOption.OnLoad).Frames.First();

What can be the reasons of connection refused errors?

If you try to open a TCP connection to another host and see the error "Connection refused," it means that

  1. You sent a TCP SYN packet to the other host.
  2. Then you received a TCP RST packet in reply.

RST is a bit on the TCP packet which indicates that the connection should be reset. Usually it means that the other host has received your connection attempt and is actively refusing your TCP connection, but sometimes an intervening firewall may block your TCP SYN packet and send a TCP RST back to you.

See page 69:


If the RST bit is set

If this connection was initiated with a passive OPEN (i.e., came from the LISTEN state), then return this connection to LISTEN state and return. The user need not be informed. If this connection was initiated with an active OPEN (i.e., came from SYN-SENT state) then the connection was refused, signal the user "connection refused". In either case, all segments on the retransmission queue should be removed. And in the active OPEN case, enter the CLOSED state and delete the TCB, and return.

Auto populate columns in one sheet from another sheet

If I understood you right you want to have sheet1!A1 in sheet2!A1, sheet1!A2 in sheet2!A2,...right?

It might not be the best way but you may type the following


and drag it down to the maximum number of rows you expect.

Is it acceptable and safe to run pip install under sudo?

It looks like your permissions are messed up. Type chown -R markwalker ~ in the Terminal and try pip again? Let me know if you're sorted.

Simulating Key Press C#

Simple one, add before Main

[DllImport("USER32.DLL", CharSet = CharSet.Unicode)]
public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
public static extern bool SetForegroundWindow(IntPtr hWnd);

Code inside Main/Method:

string className = "IEFrame";
string windowName = "New Tab - Windows Internet Explorer";
IntPtr IE = FindWindow(className, windowName);
if (IE == IntPtr.Zero)


  1. Add InputSimulator as reference. To download Click here

  2. To find Class & Window name, use WinSpy++. To download Click here

How to SHA1 hash a string in Android?

You don't need andorid for this. You can just do it in simple java.

Have you tried a simple java example and see if this returns the right sha1.


public class AeSimpleSHA1 {
    private static String convertToHex(byte[] data) {
        StringBuilder buf = new StringBuilder();
        for (byte b : data) {
            int halfbyte = (b >>> 4) & 0x0F;
            int two_halfs = 0;
            do {
                buf.append((0 <= halfbyte) && (halfbyte <= 9) ? (char) ('0' + halfbyte) : (char) ('a' + (halfbyte - 10)));
                halfbyte = b & 0x0F;
            } while (two_halfs++ < 1);
        return buf.toString();

    public static String SHA1(String text) throws NoSuchAlgorithmException, UnsupportedEncodingException {
        MessageDigest md = MessageDigest.getInstance("SHA-1");
        byte[] textBytes = text.getBytes("iso-8859-1");
        md.update(textBytes, 0, textBytes.length);
        byte[] sha1hash = md.digest();
        return convertToHex(sha1hash);

Also share what your expected sha1 should be. Maybe ObjectC is doing it wrong.

Count(*) vs Count(1) - SQL Server

I ran a quick test on SQL Server 2012 on an 8 GB RAM hyper-v box. You can see the results for yourself. I was not running any other windowed application apart from SQL Server Management Studio while running these tests.

My table schema:

CREATE TABLE [dbo].[employee](
    [Id] [bigint] IDENTITY(1,1) NOT NULL,
    [Name] [nvarchar](50) NOT NULL,
    [Id] ASC


Total number of records in Employee table: 178090131 (~ 178 million rows)

First Query:

Set Statistics Time On
Select Count(*) From Employee
Set Statistics Time Off

Result of First Query:

 SQL Server parse and compile time: 
 CPU time = 0 ms, elapsed time = 35 ms.

 (1 row(s) affected)

 SQL Server Execution Times:
   CPU time = 10766 ms,  elapsed time = 70265 ms.
 SQL Server parse and compile time: 
   CPU time = 0 ms, elapsed time = 0 ms.

Second Query:

    Set Statistics Time On
    Select Count(1) From Employee
    Set Statistics Time Off

Result of Second Query:

 SQL Server parse and compile time: 
   CPU time = 14 ms, elapsed time = 14 ms.

(1 row(s) affected)

 SQL Server Execution Times:
   CPU time = 11031 ms,  elapsed time = 70182 ms.
 SQL Server parse and compile time: 
   CPU time = 0 ms, elapsed time = 0 ms.

You can notice there is a difference of 83 (= 70265 - 70182) milliseconds which can easily be attributed to exact system condition at the time queries are run. Also I did a single run, so this difference will become more accurate if I do several runs and do some averaging. If for such a huge data-set the difference is coming less than 100 milliseconds, then we can easily conclude that the two queries do not have any performance difference exhibited by the SQL Server Engine.

Note : RAM hits close to 100% usage in both the runs. I restarted SQL Server service before starting both the runs.

HintPath vs ReferencePath in Visual Studio

Although this is an old document, but it helped me resolve the problem of 'HintPath' being ignored on another machine. It was because the referenced DLL needed to be in source control as well:


To include and then reference an outer-system assembly
1. In Solution Explorer, right-click the project that needs to reference the assembly,,and then click Add Existing Item.
2. Browse to the assembly, and then click OK. The assembly is then copied into the project folder and automatically added to VSS (assuming the project is already under source control).
3. Use the Browse button in the Add Reference dialog box to set a file reference to assembly in the project folder.