Programs & Examples On #Biztalk deployment

Relates to deployment of BizTalk applications and artifacts, whether via MSI, BTSTask or the Biztalk Deployment Framework. Included are the management of dependencies, and handling of Bindings associated with a deployment.

In a Bash script, how can I exit the entire script if a certain condition occurs?

I often include a function called run() to handle errors. Every call I want to make is passed to this function so the entire script exits when a failure is hit. The advantage of this over the set -e solution is that the script doesn't exit silently when a line fails, and can tell you what the problem is. In the following example, the 3rd line is not executed because the script exits at the call to false.

function run() {
  cmd_output=$(eval $1)
  if [ $return_value != 0 ]; then
    echo "Command $1 failed"
    exit -1
    echo "output: $cmd_output"
    echo "Command succeeded."
  return $return_value
run "date"
run "false"
run "date"

A JOIN With Additional Conditions Using Query Builder or Eloquent

I am using laravel5.2 and we can add joins with different options, you can modify as per your requirement.

Option 1:    
            ->join('contacts', function ($join) {
                $join->on('', '=', 'contacts.user_id')->orOn(...);//you add more joins here
            })// and you add more joins here

Option 2:
    $users = DB::table('users')
        ->join('contacts', '', '=', 'contacts.user_id')
        ->join('orders', '', '=', 'orders.user_id')// you may add more joins
        ->select('users.*', '', 'orders.price')

option 3:
    $users = DB::table('users')
        ->leftJoin('posts', '', '=', 'posts.user_id')
        ->leftJoin('...', '...', '...', '...')// you may add more joins

How to add and get Header values in WebApi

For WEB API 2.0:

I had to use Request.Content.Headers instead of Request.Headers

and then i declared an extestion as below

  /// <summary>
    /// Returns an individual HTTP Header value
    /// </summary>
    /// <param name="headers"></param>
    /// <param name="key"></param>
    /// <returns></returns>
    public static string GetHeader(this HttpContentHeaders headers, string key, string defaultValue)
        IEnumerable<string> keys = null;
        if (!headers.TryGetValues(key, out keys))
            return defaultValue;

        return keys.First();

And then i invoked it by this way.

  var headerValue = Request.Content.Headers.GetHeader("custom-header-key", "default-value");

I hope it might be helpful

How to check if the URL contains a given string?

Easier it gets

<script type="text/javascript">
$(document).ready(function () {
    var url = window.location.href;
    if(url.includes('franky'))    //includes() method determines whether a string contains specified string.
         alert("url contains franky");

VBA equivalent to Excel's mod function

In vba the function is MOD. e.g

 5 MOD 2

Here is a useful link.

How to get WordPress post featured image URL

You can try this:

    $feat_image = wp_get_attachment_url(get_post_thumbnail_id($post->ID)); 
    echo $feat_image; 

NoSQL Use Case Scenarios or WHEN to use NoSQL

It really is an "it depends" kinda question. Some general points:

  • NoSQL is typically good for unstructured/"schemaless" data - usually, you don't need to explicitly define your schema up front and can just include new fields without any ceremony
  • NoSQL typically favours a denormalised schema due to no support for JOINs per the RDBMS world. So you would usually have a flattened, denormalized representation of your data.
  • Using NoSQL doesn't mean you could lose data. Different DBs have different strategies. e.g. MongoDB - you can essentially choose what level to trade off performance vs potential for data loss - best performance = greater scope for data loss.
  • It's often very easy to scale out NoSQL solutions. Adding more nodes to replicate data to is one way to a) offer more scalability and b) offer more protection against data loss if one node goes down. But again, depends on the NoSQL DB/configuration. NoSQL does not necessarily mean "data loss" like you infer.
  • IMHO, complex/dynamic queries/reporting are best served from an RDBMS. Often the query functionality for a NoSQL DB is limited.
  • It doesn't have to be a 1 or the other choice. My experience has been using RDBMS in conjunction with NoSQL for certain use cases.
  • NoSQL DBs often lack the ability to perform atomic operations across multiple "tables".

You really need to look at and understand what the various types of NoSQL stores are, and how they go about providing scalability/data security etc. It's difficult to give an across-the-board answer as they really are all different and tackle things differently.

For MongoDb as an example, check out their Use Cases to see what they suggest as being "well suited" and "less well suited" uses of MongoDb.

Slide right to left Android Animations

For sliding both activity (old and new) same direction:


<?xml version="1.0" encoding="utf-8"?>
<translate xmlns:android=""


<?xml version="1.0" encoding="utf-8"?>
<translate xmlns:android=""


<?xml version="1.0" encoding="utf-8"?>
<translate xmlns:android=""
    android:toXDelta="-100%" />


<?xml version="1.0" encoding="utf-8"?>
<translate xmlns:android=""
    android:toXDelta="100%" />

startActivity transition:

overridePendingTransition(R.anim.right_in, R.anim.left_out);

onBackPressed transition:

overridePendingTransition(R.anim.left_in, R.anim.right_out);

How to solve "Could not establish trust relationship for the SSL/TLS secure channel with authority"

I encountered the same problem and I was able to resolve it with two solutions: First, I used the MMC snap-in "Certificates" for the "Computer account" and dragged the self-signed certificate into the "Trusted Root Certification Authorities" folder. This means the local computer (the one that generated the certificate) will now trust that certificate. Secondly I noticed that the certificate was generated for some internal computer name, but the web service was being accessed using another name. This caused a mismatch when validating the certificate. We generated the certificate for computer.operations.local, but accessed the web service using When we switched the URL to the one used to generate the certificate we got no more errors.

Maybe just switching URLs would have worked, but by making the certificate trusted you also avoid the red screen in Internet Explorer where it tells you it doesn't trust the certificate.

Autoplay audio files on an iPad with HTML5

I handled this by attaching an event handler for all the events for which you are allowed to trigger audio to the body element which triggers any html audio elements with autoplay to play once.

var mobile = /iPad|iPhone|iPod|android/.test(navigator.userAgent) && !window.MSStream;
if (mobile) {
    $('body').on('touchstart click doubleclick keydown', function() {

How do I set default terminal to terminator?

Copy-paste the following into your current terminal:

gsettings set org.gnome.desktop.default-applications.terminal exec /usr/bin/terminator
gsettings set org.gnome.desktop.default-applications.terminal exec-arg "-x"

This modifies the dconf to make terminator the default program. You could also use dconf-editor (a GUI-based tool) to make changes to the dconf, as another answer has suggested. If you would like to learn and understand more about this topic, this may help you.

Add "Are you sure?" to my excel button, how can I?

On your existing button code, simply insert this line before the procedure:

If MsgBox("This will erase everything! Are you sure?", vbYesNo) = vbNo Then Exit Sub

This will force it to quit if the user presses no.

Iterating over arrays in Python 3

The for loop iterates over the elements of the array, not its indexes. Suppose you have a list ar = [2, 4, 6]:

When you iterate over it with for i in ar: the values of i will be 2, 4 and 6. So, when you try to access ar[i] for the first value, it might work (as the last position of the list is 2, a[2] equals 6), but not for the latter values, as a[4] does not exist.

If you intend to use indexes anyhow, try using for index, value in enumerate(ar):, then theSum = theSum + ar[index] should work just fine.

SQL Server: Examples of PIVOTing String data

Table setup:

CREATE TABLE dbo.tbl (
    action VARCHAR(20) NOT NULL,
    view_edit VARCHAR(20) NOT NULL

INSERT INTO dbo.tbl (action, view_edit)
VALUES ('Action1', 'VIEW'),
       ('Action1', 'EDIT'),
       ('Action2', 'VIEW'),
       ('Action3', 'VIEW'),
       ('Action3', 'EDIT');

Your table: SELECT action, view_edit FROM dbo.tbl

Your table

Query without using PIVOT:

SELECT Action, 
[View] = (Select view_edit FROM tbl WHERE t.action = action and view_edit = 'VIEW'),
[Edit] = (Select view_edit FROM tbl WHERE t.action = action and view_edit = 'EDIT')
FROM tbl t

Query using PIVOT:

SELECT [Action], [View], [Edit] FROM
(SELECT [Action], view_edit FROM tbl) AS t1 
PIVOT (MAX(view_edit) FOR view_edit IN ([View], [Edit]) ) AS t2

Both queries result:
enter image description here

Type or namespace name does not exist

In my case there was no change in projects, it just stopped to compile and with "type or namespace name XXX does not exist" and in the complaining class itself intellisense for that XXX namespace/class works fine. The problem was in references indeed!

Steps to reproduce:

  1. Solution has ProjectA, ProjectB. ProjectA references to third party log4net and it is marked Copy local: true. ProjectB references ProjectA and does not have reference to log4net. Solution compiles fine.

  2. Change in ProjectA: reference property for log4net to Copy local: false.

  3. Clean bin and obj folders.
  4. When you compile, ProjectA compiles but ProjectB complains about not finding ProjectA namespace.

This is because ProjectB bin folder is missing third party library (log4net in my case)!

In this case solution would be -

  1. make sure that third party libraries references are set to Copy local: true or
  2. add path to such libraries in project properties under reference path.

How to preserve insertion order in HashMap?

LinkedHashMap is precisely what you're looking for.

It is exactly like HashMap, except that when you iterate over it, it presents the items in the insertion order.

Regex match digits, comma and semicolon?

word.matches("^[0-9,;]+$"); you were almost there

How do I get a list of files in a directory in C++?

C++11/Linux version:

#include <dirent.h>

if (auto dir = opendir("some_dir/")) {
    while (auto f = readdir(dir)) {
        if (!f->d_name || f->d_name[0] == '.')
            continue; // Skip everything that starts with a dot

        printf("File: %s\n", f->d_name);

What is the copy-and-swap idiom?

I would like to add a word of warning when you are dealing with C++11-style allocator-aware containers. Swapping and assignment have subtly different semantics.

For concreteness, let us consider a container std::vector<T, A>, where A is some stateful allocator type, and we'll compare the following functions:

void fs(std::vector<T, A> & a, std::vector<T, A> & b)
    b.clear(); // not important what you do with b

void fm(std::vector<T, A> & a, std::vector<T, A> & b)
    a = std::move(b);

The purpose of both functions fs and fm is to give a the state that b had initially. However, there is a hidden question: What happens if a.get_allocator() != b.get_allocator()? The answer is: It depends. Let's write AT = std::allocator_traits<A>.

  • If AT::propagate_on_container_move_assignment is std::true_type, then fm reassigns the allocator of a with the value of b.get_allocator(), otherwise it does not, and a continues to use its original allocator. In that case, the data elements need to be swapped individually, since the storage of a and b is not compatible.

  • If AT::propagate_on_container_swap is std::true_type, then fs swaps both data and allocators in the expected fashion.

  • If AT::propagate_on_container_swap is std::false_type, then we need a dynamic check.

    • If a.get_allocator() == b.get_allocator(), then the two containers use compatible storage, and swapping proceeds in the usual fashion.
    • However, if a.get_allocator() != b.get_allocator(), the program has undefined behaviour (cf. [container.requirements.general/8].

The upshot is that swapping has become a non-trivial operation in C++11 as soon as your container starts supporting stateful allocators. That's a somewhat "advanced use case", but it's not entirely unlikely, since move optimizations usually only become interesting once your class manages a resource, and memory is one of the most popular resources.

Load arrayList data into JTable

You probably need to use a TableModel (Oracle's tutorial here)

How implements your own TableModel

public class FootballClubTableModel extends AbstractTableModel {
  private List<FootballClub> clubs ;
  private String[] columns ; 

  public FootBallClubTableModel(List<FootballClub> aClubList){
    clubs = aClubList ;
    columns = new String[]{"Pos","Team","P", "W", "L", "D", "MP", "GF", "GA", "GD"};

  // Number of column of your table
  public int getColumnCount() {
    return columns.length ;

  // Number of row of your table
  public int getRowsCount() {
    return clubs.size();

  // The object to render in a cell
  public Object getValueAt(int row, int col) {
    FootballClub club = clubs.get(row);
    switch(col) {
      case 0: return club.getPosition();
      // to complete here...
      default: return null;

  // Optional, the name of your column
  public String getColumnName(int col) {
    return columns[col] ;


You maybe need to override anothers methods of TableModel, depends on what you want to do, but here is the essential methods to understand and implements :)
Use it like this

List<FootballClub> clubs = getFootballClub();
TableModel model = new FootballClubTableModel(clubs);
JTable table = new JTable(model);

Hope it help !


I would always use sp_executesql these days, all it really is is a wrapper for EXEC which handles parameters & variables.

However do not forget about OPTION RECOMPILE when tuning queries on very large databases, especially where you have data spanned over more than one database and are using a CONSTRAINT to limit index scans.

Unless you use OPTION RECOMPILE, SQL server will attempt to create a "one size fits all" execution plan for your query, and will run a full index scan each time it is run.

This is much less efficient than a seek, and means it is potentially scanning entire indexes which are constrained to ranges which you are not even querying :@

Default instance name of SQL Server Express

When installing SQL Express, you'll usually get a named instance called SQLExpress, which as others have said you can connect to with localhost\SQLExpress.

If you're looking to get a 'default' instance, which doesn't have a name, you can do that as well. If you put MSSQLServer as the name when installing, it will create a default instance which you can connect to by just specifying 'localhost'.

See here for details... MSDN Instance Configuration

What is the difference between a hash join and a merge join (Oracle RDBMS )?

I just want to edit this for posterity that the tags for oracle weren't added when I answered this question. My response was more applicable to MS SQL.

Merge join is the best possible as it exploits the ordering, resulting in a single pass down the tables to do the join. IF you have two tables (or covering indexes) that have their ordering the same such as a primary key and an index of a table on that key then a merge join would result if you performed that action.

Hash join is the next best, as it's usually done when one table has a small number (relatively) of items, its effectively creating a temp table with hashes for each row which is then searched continuously to create the join.

Worst case is nested loop which is order (n * m) which means there is no ordering or size to exploit and the join is simply, for each row in table x, search table y for joins to do.

How to access Winform textbox control from another class?

public partial class Form1 : Form

    public static Form1 gui;
    public Form1()
        gui = this;

    public void WriteLog(string log)
        this.Invoke(new Action(() => { txtbx_test1.Text += log; }));

public class SomeAnotherClass
    public void Test()

I like this solution.

What is a "method" in Python?

Usually, a method is called right after it is bound:


In the MyClass example, this will return the string 'hello world'. However, it is not necessary to call a method right away: x.f is a method object, and can be stored away and called at a later time. For example:

xf = x.f
while True:
    print xf()

will continue to print hello world until the end of time.

What exactly happens when a method is called? You may have noticed that x.f() was called without an argument above, even though the function definition for f() specified an argument. What happened to the argument? Surely Python raises an exception when a function that requires an argument is called without any — even if the argument isn’t actually used...

Actually, you may have guessed the answer: the special thing about methods is that the object is passed as the first argument of the function. In our example, the call x.f() is exactly equivalent to MyClass.f(x). In general, calling a method with a list of n arguments is equivalent to calling the corresponding function with an argument list that is created by inserting the method’s object before the first argument.

If you still don’t understand how methods work, a look at the implementation can perhaps clarify matters. When an instance attribute is referenced that isn’t a data attribute, its class is searched. If the name denotes a valid class attribute that is a function object, a method object is created by packing (pointers to) the instance object and the function object just found together in an abstract object: this is the method object. When the method object is called with an argument list, a new argument list is constructed from the instance object and the argument list, and the function object is called with this new argument list.

Can you hide the controls of a YouTube embed without enabling autoplay?



is something that I never found... but it was the key :) I hope it's help

Change R default library path using .libPaths in fails to work

Since most of the answers here are related to Windows & Mac OS, (and considering that I also struggled with this) I decided to post the process that helped me solve this problem on my Arch Linux setup.

Step 1:

  • Do a global search of your system (e.g. ANGRYSearch) for the term Renviron (which is the configuration file where the settings for the user libraries are set).
  • It should return only two results at the following directory paths:
    1. /etc/R/
    2. /usr/lib/R/etc/
      NOTE: The Renviron config files stored at 1 & 2 (above) are hot-linked to each other (which means changes made to one file will automatically be applied [ in the same form / structure ] to the other file when the file being edited is saved - [ you also need sudo rights for saving the file post-edit ] ).

Step 2:

  • Navigate into the 1st directory path ( /etc/R/ ) and open the Renviron file with your favourite text editor.
  • Once inside the Renviron file search for the R_LIBS_USER tag and update the text in the curly braces section to your desired directory path.

    ... Change From ( original entry ):
    ... Change To ( your desired entry ):

Step 3:

  • Save the Renviron file you've just edited ... DONE !!

How do you keep parents of floated elements from collapsing?

Although the code isn't perfectly semantic, I think it's more straightforward to have what I call a "clearing div" at the bottom of every container with floats in it. In fact, I've included the following style rule in my reset block for every project:

   clear: both;

If you're styling for IE6 (god help you), you might want to give this rule a 0px line-height and height as well.

How can I copy the output of a command directly into my clipboard?

on Wayland xcopy doesn't seem to work, use wl-clipboard instead. e.g. on fedora

sudo dnf install wl-clipboard

tree | wl-copy

wl-paste > file

What does the star operator mean, in a function call?

In a function call the single star turns a list into seperate arguments (e.g. zip(*x) is the same as zip(x1,x2,x3) if x=[x1,x2,x3]) and the double star turns a dictionary into seperate keyword arguments (e.g. f(**k) is the same as f(x=my_x, y=my_y) if k = {'x':my_x, 'y':my_y}.

In a function definition it's the other way around: the single star turns an arbitrary number of arguments into a list, and the double start turns an arbitrary number of keyword arguments into a dictionary. E.g. def foo(*x) means "foo takes an arbitrary number of arguments and they will be accessible through the list x (i.e. if the user calls foo(1,2,3), x will be [1,2,3])" and def bar(**k) means "bar takes an arbitrary number of keyword arguments and they will be accessible through the dictionary k (i.e. if the user calls bar(x=42, y=23), k will be {'x': 42, 'y': 23})".

Convert java.time.LocalDate into java.util.Date type

    LocalDate date =;
    DateFormat formatter = new SimpleDateFormat("dd-mm-yyyy");
    try {
        Date utilDate= formatter.parse(date.toString());
    } catch (ParseException e) {
        // handle exception

Regular Expression to match string starting with a specific word

If you want to match anything that starts with "stop" including "stop going", "stop" and "stopping" use:


If you want to match the word stop followed by anything as in "stop going", "stop this", but not "stopped" and not "stopping" use:


How do I iterate and modify Java Sets?

You can do what you want if you use an iterator object to go over the elements in your set. You can remove them on the go an it's ok. However removing them while in a for loop (either "standard", of the for each kind) will get you in trouble:

Set<Integer> set = new TreeSet<Integer>();

    //good way:
    Iterator<Integer> iterator = set.iterator();
    while(iterator.hasNext()) {
        Integer setElement =;
        if(setElement==2) {

    //bad way:
    for(Integer setElement:set) {
        if(setElement==2) {
            //might work or might throw exception, Java calls it indefined behaviour:

As per @mrgloom's comment, here are more details as to why the "bad" way described above is, well... bad :

Without getting into too much details about how Java implements this, at a high level, we can say that the "bad" way is bad because it is clearly stipulated as such in the Java docs:

stipulate, amongst others, that (emphasis mine):

"For example, it is not generally permissible for one thread to modify a Collection while another thread is iterating over it. In general, the results of the iteration are undefined under these circumstances. Some Iterator implementations (including those of all the general purpose collection implementations provided by the JRE) may choose to throw this exception if this behavior is detected" (...)

"Note that this exception does not always indicate that an object has been concurrently modified by a different thread. If a single thread issues a sequence of method invocations that violates the contract of an object, the object may throw this exception. For example, if a thread modifies a collection directly while it is iterating over the collection with a fail-fast iterator, the iterator will throw this exception."

To go more into details: an object that can be used in a forEach loop needs to implement the "java.lang.Iterable" interface (javadoc here). This produces an Iterator (via the "Iterator" method found in this interface), which is instantiated on demand, and will contain internally a reference to the Iterable object from which it was created. However, when an Iterable object is used in a forEach loop, the instance of this iterator is hidden to the user (you cannot access it yourself in any way).

This, coupled with the fact that an Iterator is pretty stateful, i.e. in order to do its magic and have coherent responses for its "next" and "hasNext" methods it needs that the backing object is not changed by something else than the iterator itself while it's iterating, makes it so that it will throw an exception as soon as it detects that something changed in the backing object while it is iterating over it.

Java calls this "fail-fast" iteration: i.e. there are some actions, usually those that modify an Iterable instance (while an Iterator is iterating over it). The "fail" part of the "fail-fast" notion refers to the ability of an Iterator to detect when such "fail" actions happen. The "fast" part of the "fail-fast" (and, which in my opinion should be called "best-effort-fast"), will terminate the iteration via ConcurrentModificationException as soon as it can detect that a "fail" action has happen.

web.xml is missing and <failOnMissingWebXml> is set to true

My project had nothing to do with war, but the same error. I had to remove project from eclipse, delete all eclipse files from the project folder and reimport maven project.

Selecting multiple items in ListView

In listView you can use it by Adapter

ArrayAdapter<String> adapterChannels = new ArrayAdapter<>(this, android.R.layout.simple_list_item_multiple_choice);

Facebook share link - can you customize the message body text?

To add some text, what I did some time ago , if the link you are sharing its a page you can modify. You can add some meta-tags to the shared page:

<meta name="title" content="The title you want" />
<meta name="description" content="The text you want to insert " />
<link rel="image_src" href="A thumbnail you can show" / >

It's a small hack. Although the old share button has been replaced by the "like"/"recommend" button where you can add a comment if you use the XFBML version. More info her:

Can't include C++ headers like vector in Android NDK

If you are using Android studio and you are still seeing the message "error: vector: No such file or directory" (or other stl related errors) when you're compiling using ndk, then this might help you.

In your project, open the module's build.gradle file (not your project's build.grade, but the one that is for your module) and add 'stl "stlport_shared"' within the ndk element in defaultConfig.

For eg:

android {
    compileSdkVersion 21
    buildToolsVersion "21.1.2"

    defaultConfig {
        applicationId ""
        minSdkVersion 15
        targetSdkVersion 21
        versionCode 1
        versionName "1.0"

        ndk {
            moduleName "myModuleName"
            stl "stlport_shared"

How do I append one string to another in Python?

Python 3.6 gives us f-strings, which are a delight:

var1 = "foo"
var2 = "bar"
var3 = f"{var1}{var2}"
print(var3)                       # prints foobar

You can do most anything inside the curly braces

print(f"1 + 1 == {1 + 1}")        # prints 1 + 1 == 2

What does !important mean in CSS?

The !important rule is a way to make your CSS cascade but also have the rules you feel are most crucial always be applied. A rule that has the !important property will always be applied no matter where that rule appears in the CSS document.

So, if you have the following:

.class {
   color: red !important;
.outerClass .class {
   color: blue;

the rule with the important will be the one applied (not counting specificity)

I believe !important appeared in CSS1 so every browser supports it (IE4 to IE6 with a partial implementation, IE7+ full)

Also, it's something that you don't want to use pretty often, because if you're working with other people you can override other properties.

Limiting double to 3 decimal places

Good answers above- if you're looking for something reusable here is the code. Note that you might want to check the decimal places value, and this may overflow.

public static decimal TruncateToDecimalPlace(this decimal numberToTruncate, int decimalPlaces)
    decimal power = (decimal)(Math.Pow(10.0, (double)decimalPlaces));

    return Math.Truncate((power * numberToTruncate)) / power;

Java Timer vs ExecutorService?

According to Java Concurrency in Practice:

  • Timer can be sensitive to changes in the system clock, ScheduledThreadPoolExecutor isn't.
  • Timer has only one execution thread, so long-running task can delay other tasks. ScheduledThreadPoolExecutor can be configured with any number of threads. Furthermore, you have full control over created threads, if you want (by providing ThreadFactory).
  • Runtime exceptions thrown in TimerTask kill that one thread, thus making Timer dead :-( ... i.e. scheduled tasks will not run anymore. ScheduledThreadExecutor not only catches runtime exceptions, but it lets you handle them if you want (by overriding afterExecute method from ThreadPoolExecutor). Task which threw exception will be canceled, but other tasks will continue to run.

If you can use ScheduledThreadExecutor instead of Timer, do so.

One more thing... while ScheduledThreadExecutor isn't available in Java 1.4 library, there is a Backport of JSR 166 (java.util.concurrent) to Java 1.2, 1.3, 1.4, which has the ScheduledThreadExecutor class.

How to add text to a WPF Label in code?

In normal winForms, value of Label object is changed by,

myLabel.Text= "Your desired string";

But in WPF Label control, you have to use .content property of Label control for example,

myLabel.Content= "Your desired string";

Save Javascript objects in sessionStorage

The solution is to stringify the object before calling setItem on the sessionStorage.

var user = {'name':'John'};
sessionStorage.setItem('user', JSON.stringify(user));
var obj = JSON.parse(sessionStorage.user);

Use URI builder in Android or create URL with variables

Let's say that I want to create the following URL:

To build this with the Uri.Builder I would do the following.

Uri.Builder builder = new Uri.Builder();
    .appendQueryParameter("type", "1")
    .appendQueryParameter("sort", "relevance")
String myUrl =;

Return sql rows where field contains ONLY non-alphanumeric characters

This will not work correctly, e.g. abcÑxyz will pass thru this as it has a,b,c... you need to work with Collate or check each byte.

Is JavaScript object-oriented?

Javascript is not an object oriented language as typically considered, mainly due to lack of true inheritance, DUCK typing allows for a semi-true form of inheritance/polymorphism along with the Object.prototype allowing for complex function sharing. At its heart however the lack of inheritance leads to a weak polymorphism to take place since the DUCK typing will insist some object with the same attribute names are an instance of an Object which they were not intended to be used as. Thus adding attributes to random object transforms their type's base in a manner of speaking.

Change Background color (css property) using Jquery

$("#bchange").click(function() {
    $("body, this").css("background-color","yellow");

Save Dataframe to csv directly to s3 Python

This is a more up to date answer:

import s3fs

s3 = s3fs.S3FileSystem(anon=False)

# Use 'w' for py3, 'wb' for py2
with'<bucket-name>/<filename>.csv','w') as f:

The problem with StringIO is that it will eat away at your memory. With this method, you are streaming the file to s3, rather than converting it to string, then writing it into s3. Holding the pandas dataframe and its string copy in memory seems very inefficient.

If you are working in an ec2 instant, you can give it an IAM role to enable writing it to s3, thus you dont need to pass in credentials directly. However, you can also connect to a bucket by passing credentials to the S3FileSystem() function. See documention:

Java string to date conversion

DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
Date date;
try {
    date = dateFormat.parse("2013-12-4");
    System.out.println(date.toString()); // Wed Dec 04 00:00:00 CST 2013

    String output = dateFormat.format(date);
    System.out.println(output); // 2013-12-04
catch (ParseException e) {

It works fine for me.

Rails: Check output of path helper from console

you can also

include Rails.application.routes.url_helpers

from inside a console sessions to access the helpers:

url_for controller: :users, only_path: true
# => '/users'



What is the difference between declarative and imperative paradigm in programming?

Declarative vs. Imperative

A programming paradigm is a fundamental style of computer programming. There are four main paradigms: imperative, declarative, functional (which is considered a subset of the declarative paradigm) and object-oriented.

Declarative programming : is a programming paradigm that expresses the logic of a computation(What do) without describing its control flow(How do). Some well-known examples of declarative domain specific languages (DSLs) include CSS, regular expressions, and a subset of SQL (SELECT queries, for example) Many markup languages such as HTML, MXML, XAML, XSLT... are often declarative. The declarative programming try to blur the distinction between a program as a set of instructions and a program as an assertion about the desired answer.

Imperative programming : is a programming paradigm that describes computation in terms of statements that change a program state. The declarative programs can be dually viewed as programming commands or mathematical assertions.

Functional programming : is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids state and mutable data. It emphasizes the application of functions, in contrast to the imperative programming style, which emphasizes changes in state. In a pure functional language, such as Haskell, all functions are without side effects, and state changes are only represented as functions that transform the state.

The following example of imperative programming in MSDN, loops through the numbers 1 through 10, and finds the even numbers.

var numbersOneThroughTen = new List<int> { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
//With imperative programming, we'd step through this, and decide what we want:
var evenNumbers = new List<int>();
foreach (var number in numbersOneThroughTen)
{    if (number % 2 == 0)
//The following code uses declarative programming to accomplish the same thing.
// Here, we're saying "Give us everything where it's even"
var evenNumbers = numbersOneThroughTen.Select(number => number % 2 == 0);

Both examples yield the same result, and one is neither better nor worse than the other. The first example requires more code, but the code is testable, and the imperative approach gives you full control over the implementation details. In the second example, the code is arguably more readable; however, LINQ does not give you control over what happens behind the scenes. You must trust that LINQ will provide the requested result.

How to fill the whole canvas with specific color?

If you want to do the background explicitly, you must be certain that you draw behind the current elements on the canvas.

var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
// Add behind elements.
ctx.globalCompositeOperation = 'destination-over'
// Now draw!
ctx.fillStyle = "blue";
ctx.fillRect(0, 0, canvas.width, canvas.height);

Referencing in Visual Studio

If you don't want to install the Windows SDK you can get the dll by running the following command in powershell:

Copy ([PSObject].Assembly.Location) C:\

How do I get the application exit code from a Windows command line?

A pseudo environment variable named errorlevel stores the exit code:

echo Exit Code is %errorlevel%

Also, the if command has a special syntax:

if errorlevel

See if /? for details.


@echo off
if errorlevel 1 (
   echo Failure Reason Given is %errorlevel%
   exit /b %errorlevel%

Warning: If you set an environment variable name errorlevel, %errorlevel% will return that value and not the exit code. Use (set errorlevel=) to clear the environment variable, allowing access to the true value of errorlevel via the %errorlevel% environment variable.

No ConcurrentList<T> in .Net 4.0?

In cases where reads greatly outnumber writes, or (however frequent) writes are non-concurrent, a copy-on-write approach may be appropriate.

The implementation shown below is

  • lockless
  • blazingly fast for concurrent reads, even while concurrent modifications are ongoing - no matter how long they take
  • because "snapshots" are immutable, lockless atomicity is possible, i.e. var snap = _list; snap[snap.Count - 1]; will never (well, except for an empty list of course) throw, and you also get thread-safe enumeration with snapshot semantics for free.. how I LOVE immutability!
  • implemented generically, applicable to any data structure and any type of modification
  • dead simple, i.e. easy to test, debug, verify by reading the code
  • usable in .Net 3.5

For copy-on-write to work, you have to keep your data structures effectively immutable, i.e. no one is allowed to change them after you made them available to other threads. When you want to modify, you

  1. clone the structure
  2. make modifications on the clone
  3. atomically swap in the reference to the modified clone


static class CopyOnWriteSwapper
    public static void Swap<T>(ref T obj, Func<T, T> cloner, Action<T> op)
        where T : class
        while (true)
            var objBefore = Volatile.Read(ref obj);
            var newObj = cloner(objBefore);
            if (Interlocked.CompareExchange(ref obj, newObj, objBefore) == objBefore)


CopyOnWriteSwapper.Swap(ref _myList,
    orig => new List<string>(orig),
    clone => clone.Add("asdf"));

If you need more performance, it will help to ungenerify the method, e.g. create one method for every type of modification (Add, Remove, ...) you want, and hard code the function pointers cloner and op.

N.B. #1 It is your responsibility to make sure the no one modifies the (supposedly) immutable data structure. There's nothing we can do in a generic implementation to prevent that, but when specializing to List<T>, you could guard against modification using List.AsReadOnly()

N.B. #2 Be careful about the values in the list. The copy on write approach above guards their list membership only, but if you'd put not strings, but some other mutable objects in there, you have to take care of thread safety (e.g. locking). But that is orthogonal to this solution and e.g. locking of the mutable values can be easily used without issues. You just need to be aware of it.

N.B. #3 If your data structure is huge and you modify it frequently, the copy-all-on-write approach might be prohibitive both in terms of memory consumption and the CPU cost of copying involved. In that case, you might want to use MS's Immutable Collections instead.

How to Sort a List<T> by a property in the object

Make use of LiNQ OrderBy

List<Order> objListOrder=new List<Order> ();

Call a function after previous function is complete

If method 1 has to be executed after method 2, 3, 4. The following code snippet can be the solution for this using Deferred object in JavaScript.

function method1(){_x000D_
  var dfd = new $.Deferred();_x000D_
     console.log("Inside Method - 1"); _x000D_
     method2(dfd);  _x000D_
    }, 5000);_x000D_
  return dfd.promise();_x000D_
function method2(dfd){_x000D_
   console.log("Inside Method - 2"); _x000D_
   method3(dfd); _x000D_
  }, 3000);_x000D_
function method3(dfd){_x000D_
   console.log("Inside Method - 3");  _x000D_
  }, 3000);_x000D_
function method4(){   _x000D_
   console.log("Inside Method - 4");  _x000D_
var call = method1();_x000D_
<script src=""></script>

Remove Android App Title Bar

In your res/values/styles.xml of modern Android Studio projects (2019/2020) you should be able to change the default parent theme

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">

I went one step further and had it look like this

<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
    <item name="android:windowFullscreen">true</item>

This is based on the code generated from the Microsoft PWA builder

How to include an HTML page into another HTML page without frame/iframe?

confirmed roadkill, create a .htaccess file in the web root with a single line which allows you to add php code to a .html file.

AddType application/x-httpd-php .html

How to check if a list is empty in Python?

I like Zarembisty's answer. Although, if you want to be more explicit, you can always do:

if len(my_list) == 0:
    print "my_list is empty"

Correct way to delete cookies server-side

Setting "expires" to a past date is the standard way to delete a cookie.

Your problem is probably because the date format is not conventional. IE probably expects GMT only.

How can I get the current directory name in Javascript?

This will work for actual paths on the file system if you're not talking the URL string.

var path = document.location.pathname;
var directory = path.substring(path.indexOf('/'), path.lastIndexOf('/'));

How can I make a link from a <td> table cell

This might be the most simple way to make a whole <td> cell an active hyperlink just using HTML.

I never had a satisfactory answer for this question, until about 10 minutes ago, so years in the making #humor.

Tested on Firefox 70, this is a bare-bones example where one full line-width of the cell is active:

<td><a href=""><div><br /></div></a></td>

Obviously the example just links to "this document," so fill in the href="" and replace the <br /> with anything appropriate.

Previously I used a style and class pair that I cobbled together from the answers above (Thanks to you folks.)

Today, working on a different issue, I kept stripping it down until <div>&nbsp;</div> was the only thing left, remove the <div></div> and it stops linking beyond the text. I didn't like the short "_" the &nbsp; displayed and found a single <br /> works without an "extra line" penalty.

If another <td></td> in the <tr> has multiple lines, and makes the row taller with word-wrap for instance, then use multiple <br /> to bring the <td> you want to be active to the correct number of lines and active the full width of each line.

The only problem is it isn't dynamic, but usually the mouse is closer in height than width, so active everywhere on one line is better than just the width of the text.

How to add header to a dataset in R?

in case you are interested in reading some data from a .txt file and only extract few columns of that file into a new .txt file with a customized header, the following code might be useful:

# input some data from 2 different .txt files:
civit_gps <- read.csv(file="/path2/gpsFile.csv",head=TRUE,sep=",")
civit_cam <- read.csv(file="/path2/cameraFile.txt",head=TRUE,sep=",")

# assign the name for the output file:
seqName <- "seq1_data.txt"

# Extract data from imported files
# From Camera:
frame_idx <- civit_cam$X.frame
qx        <- civit_cam$q.x.rad.
qy        <- civit_cam$q.y.rad.
qz        <- civit_cam$q.z.rad.
qw        <- civit_cam$q.w

# From GPS:
gpsT      <- civit_gps$X.gpsTime.sec.
latitude  <- civit_gps$Latitude.deg.
longitude <- civit_gps$Longitude.deg.
altitude  <- civit_gps$H.Ell.m.
heading   <- civit_gps$Heading.deg.
pitch     <- civit_gps$pitch.deg.
roll      <- civit_gps$roll.deg.
gpsTime_corr <- civit_gps[frame_idx,1]

# Export new data into the output txt file
myData <- data.frame(c(gpsTime_corr),
# Write :
cat("#GPSTime,frameIdx,qx,qy,qz,qw\n", file=seqName)
write.table(myData, file = seqName,row.names=FALSE,col.names=FALSE,append=TRUE,sep = ",")

Of course, you should modify this sample script based on your own application.

Team Build Error: The Path ... is already mapped to workspace

My issue was related to using multiple accounts. This is how I was able to switch accounts.

Open Team Explorer

From the big drop down menu near the top of the pane...

Navigate to: Projects and my Teams>Manage Connections

Navigate to: Manage Connections>Connect to Team Project

Use the "Switch User" link to switch accounts.

Now the workspace names will match the chosen account.

Setting Camera Parameters in OpenCV/Python

I had the same problem with openCV on Raspberry Pi... don't know if this can solve your problem, but what worked for me was

import time
import cv2

cap = cv2.VideoCapture(0)




cap.set(15, -8.0)

the time you have to use can be different

Declaring a boolean in JavaScript using just var

The variable will become what ever type you assign it. Initially it is undefined. If you assign it 'true' it will become a string, if you assign it true it will become a boolean, if you assign it 1 it will become a number. Subsequent assignments may change the type of the variable later.

How to fix "The ConnectionString property has not been initialized"

Referencing the connection string should be done as such:


ConfigurationManager.AppSettings["ConnectionString"] would be looking in the AppSettings for something named ConnectionString, which it would not find. This is why your error message indicated the "ConnectionString" property has not been initialized, because it is looking for an initialized property of AppSettings named ConnectionString.

ConfigurationManager.ConnectionStrings["MyDB"].ConnectionString instructs to look for the connection string named "MyDB".

Here is someone talking about using web.config connection strings

How enable auto-format code for Intellij IDEA?

Per the comment of Larson, this is now possible with the save-actions plugin.

How can I run a PHP script in the background after a form is submitted?

If you can access the server over ssh and can run your own scripts you can make a simple fifo server using php (although you will have to recompile php with posix support for fork).

The server can be written in anything really, you probably can easily do it in python.

Or the simplest solution would be sending an HttpRequest and not reading the return data but the server might destroy the script before it finish processing.

Example server :

define('FIFO_PATH', '/home/user/input.queue');
define('FORK_COUNT', 10);

if(file_exists(FIFO_PATH)) {
    die(FIFO_PATH . ' exists, please delete it and try again.' . "\n");

if(!file_exists(FIFO_PATH) && !posix_mkfifo(FIFO_PATH, 0666)){
    die('Couldn\'t create the listening fifo.' . "\n");

$pids = array();
$fp = fopen(FIFO_PATH, 'r+');
for($i = 0; $i < FORK_COUNT; ++$i) {
    $pids[$i] = pcntl_fork();
    if(!$pids[$i]) {
        echo "process(" . posix_getpid() . ", id=$i)\n";
        while(true) {
            $line = chop(fgets($fp));
            if($line == 'quit' || $line === false) break;
            echo "processing (" . posix_getpid() . ", id=$i) :: $line\n";
        //  $data = json_decode($line);
        //  processData($data);
foreach($pids as $pid){
    pcntl_waitpid($pid, $status);

Example client :

define('FIFO_PATH', '/home/user/input.queue');
if(!file_exists(FIFO_PATH)) {
    die(FIFO_PATH . ' doesn\'t exist, please make sure the fifo server is running.' . "\n");

function postToQueue($data) {
    $fp = fopen(FIFO_PATH, 'w+');
    stream_set_blocking($fp, false); //don't block
    $data = json_encode($data) . "\n";
    if(fwrite($fp, $data) != strlen($data)) {
        echo "Couldn't the server might be dead or there's a bug somewhere\n";
$i = 1000;
while(--$i) {
    postToQueue(array('xx'=>21, 'yy' => array(1,2,3)));

Spring: Returning empty HTTP Responses with ResponseEntity<Void> doesn't work

Your method implementation is ambiguous, try the following , edited your code a little bit and used HttpStatus.NO_CONTENT i.e 204 No Content as in place of HttpStatus.OK

The server has fulfilled the request but does not need to return an entity-body, and might want to return updated metainformation. The response MAY include new or updated metainformation in the form of entity-headers, which if present SHOULD be associated with the requested variant.

Any value of T will be ignored for 204, but not for 404

  public ResponseEntity<?> taxonomyPackageExists( @PathVariable final String key ) {
            LOG.debug( "taxonomyPackageExists queried with key: {0}", key ); //$NON-NLS-1$
            final TaxonomyKey taxonomyKey = TaxonomyKey.fromString( key );
            LOG.debug( "Taxonomy key created: {0}", taxonomyKey ); //$NON-NLS-1$

            if ( this.xbrlInstanceValidator.taxonomyPackageExists( taxonomyKey ) ) {
                LOG.debug( "Taxonomy package with key: {0} exists.", taxonomyKey ); //$NON-NLS-1$
                 return new ResponseEntity<T>(HttpStatus.NO_CONTENT);
            } else {
               LOG.debug( "Taxonomy package with key: {0} does NOT exist.", taxonomyKey ); //$NON-NLS-1$
                return new ResponseEntity<T>( HttpStatus.NOT_FOUND );


Add swipe to delete UITableViewCell

func tableView(tableView: UITableView, editActionsForRowAtIndexPath indexPath: NSIndexPath) -> [UITableViewRowAction]?

    let delete = UITableViewRowAction(style: UITableViewRowActionStyle.Default, title: "DELETE"){(UITableViewRowAction,NSIndexPath) -> Void in

        print("What u want while Pressed delete")
    let edit = UITableViewRowAction(style: UITableViewRowActionStyle.Normal, title: "EDIT"){(UITableViewRowAction,NSIndexPath) -> Void in

        print("What u want while Pressed Edit")

    edit.backgroundColor = UIColor.blackColor()
    return [delete,edit]

Self-references in object literals / initializers

var x = {
    a: (window.secreta = 5),
    b: (window.secretb = 6),
    c: window.secreta + window.secretb

This is almost identical to @slicedtoad's answer, but doesn't use a function.

How to provide animation when calling another activity in Android?

Since API 16 you can supply an activity options bundle when calling Context.startActivity(Intent, Bundle) or related methods. It is created via the ActivityOptions builder:

Intent myIntent = new Intent(context, MyActivity.class);
ActivityOptions options = 
   ActivityOptions.makeCustomAnimation(context, R.anim.fade_in, R.anim.fade_out);
context.startActivity(myIntent, options.toBundle());

Don't forget to check out the other methods of the ActivityOptions builder and the ActivityOptionsCompat if you are using the Support Library.

API 5+:

For apps targeting API level 5+ there is the Activities overridePendingTransition method. It takes two resource IDs for the incoming and outgoing animations. An id of 0 will disable the animations. Call this immediately after the startActivity call.


startActivity(new Intent(this, MyActivity.class));
overridePendingTransition(R.anim.fade_in, R.anim.fade_out);

API 3+:

You can prevent the default animation (Slide in from the right) with the Intent.FLAG_ACTIVITY_NO_ANIMATION flag in your intent.


Intent myIntent = new Intent(context, MyActivity.class);

then in your Activity you simply have to specify your own animation.

This also works for the 1.5 API (Level 3).

Is floating point math broken?

Floating point numbers are represented, at the hardware level, as fractions of binary numbers (base 2). For example, the decimal fraction:


has the value 1/10 + 2/100 + 5/1000 and, in the same way, the binary fraction:


has the value 0/2 + 0/4 + 1/8. These two fractions have the same value, the only difference is that the first is a decimal fraction, the second is a binary fraction.

Unfortunately, most decimal fractions cannot have exact representation in binary fractions. Therefore, in general, the floating point numbers you give are only approximated to binary fractions to be stored in the machine.

The problem is easier to approach in base 10. Take for example, the fraction 1/3. You can approximate it to a decimal fraction:


or better,


or better,


etc. No matter how many decimal places you write, the result is never exactly 1/3, but it is an estimate that always comes closer.

Likewise, no matter how many base 2 decimal places you use, the decimal value 0.1 cannot be represented exactly as a binary fraction. In base 2, 1/10 is the following periodic number:

0.0001100110011001100110011001100110011001100110011 ...

Stop at any finite amount of bits, and you'll get an approximation.

For Python, on a typical machine, 53 bits are used for the precision of a float, so the value stored when you enter the decimal 0.1 is the binary fraction.


which is close, but not exactly equal, to 1/10.

It's easy to forget that the stored value is an approximation of the original decimal fraction, due to the way floats are displayed in the interpreter. Python only displays a decimal approximation of the value stored in binary. If Python were to output the true decimal value of the binary approximation stored for 0.1, it would output:

>>> 0.1

This is a lot more decimal places than most people would expect, so Python displays a rounded value to improve readability:

>>> 0.1

It is important to understand that in reality this is an illusion: the stored value is not exactly 1/10, it is simply on the display that the stored value is rounded. This becomes evident as soon as you perform arithmetic operations with these values:

>>> 0.1 + 0.2

This behavior is inherent to the very nature of the machine's floating-point representation: it is not a bug in Python, nor is it a bug in your code. You can observe the same type of behavior in all other languages ??that use hardware support for calculating floating point numbers (although some languages ??do not make the difference visible by default, or not in all display modes).

Another surprise is inherent in this one. For example, if you try to round the value 2.675 to two decimal places, you will get

>>> round (2.675, 2)

The documentation for the round() primitive indicates that it rounds to the nearest value away from zero. Since the decimal fraction is exactly halfway between 2.67 and 2.68, you should expect to get (a binary approximation of) 2.68. This is not the case, however, because when the decimal fraction 2.675 is converted to a float, it is stored by an approximation whose exact value is :


Since the approximation is slightly closer to 2.67 than 2.68, the rounding is down.

If you are in a situation where rounding decimal numbers halfway down matters, you should use the decimal module. By the way, the decimal module also provides a convenient way to "see" the exact value stored for any float.

>>> from decimal import Decimal
>>> Decimal (2.675)
>>> Decimal ('2.67499999999999982236431605997495353221893310546875')

Another consequence of the fact that 0.1 is not exactly stored in 1/10 is that the sum of ten values ??of 0.1 does not give 1.0 either:

>>> sum = 0.0
>>> for i in range (10):
... sum + = 0.1
...>>> sum

The arithmetic of binary floating point numbers holds many such surprises. The problem with "0.1" is explained in detail below, in the section "Representation errors". See The Perils of Floating Point for a more complete list of such surprises.

It is true that there is no simple answer, however do not be overly suspicious of floating virtula numbers! Errors, in Python, in floating-point number operations are due to the underlying hardware, and on most machines are no more than 1 in 2 ** 53 per operation. This is more than necessary for most tasks, but you should keep in mind that these are not decimal operations, and every operation on floating point numbers may suffer from a new error.

Although pathological cases exist, for most common use cases you will get the expected result at the end by simply rounding up to the number of decimal places you want on the display. For fine control over how floats are displayed, see String Formatting Syntax for the formatting specifications of the str.format () method.

This part of the answer explains in detail the example of "0.1" and shows how you can perform an exact analysis of this type of case on your own. We assume that you are familiar with the binary representation of floating point numbers.The term Representation error means that most decimal fractions cannot be represented exactly in binary. This is the main reason why Python (or Perl, C, C ++, Java, Fortran, and many others) usually doesn't display the exact result in decimal:

>>> 0.1 + 0.2

Why ? 1/10 and 2/10 are not representable exactly in binary fractions. However, all machines today (July 2010) follow the IEEE-754 standard for the arithmetic of floating point numbers. and most platforms use an "IEEE-754 double precision" to represent Python floats. Double precision IEEE-754 uses 53 bits of precision, so on reading the computer tries to convert 0.1 to the nearest fraction of the form J / 2 ** N with J an integer of exactly 53 bits. Rewrite :

1/10 ~ = J / (2 ** N)

in :

J ~ = 2 ** N / 10

remembering that J is exactly 53 bits (so> = 2 ** 52 but <2 ** 53), the best possible value for N is 56:

>>> 2 ** 52
>>> 2 ** 53
>>> 2 ** 56/10

So 56 is the only possible value for N which leaves exactly 53 bits for J. The best possible value for J is therefore this quotient, rounded:

>>> q, r = divmod (2 ** 56, 10)
>>> r

Since the carry is greater than half of 10, the best approximation is obtained by rounding up:

>>> q + 1

Therefore the best possible approximation for 1/10 in "IEEE-754 double precision" is this above 2 ** 56, that is:


Note that since the rounding was done upward, the result is actually slightly greater than 1/10; if we hadn't rounded up, the quotient would have been slightly less than 1/10. But in no case is it exactly 1/10!

So the computer never "sees" 1/10: what it sees is the exact fraction given above, the best approximation using the double precision floating point numbers from the "" IEEE-754 ":

>>>. 1 * 2 ** 56

If we multiply this fraction by 10 ** 30, we can observe the values ??of its 30 decimal places of strong weight.

>>> 7205759403792794 * 10 ** 30 // 2 ** 56

meaning that the exact value stored in the computer is approximately equal to the decimal value 0.100000000000000005551115123125. In versions prior to Python 2.7 and Python 3.1, Python rounded these values ??to 17 significant decimal places, displaying “0.10000000000000001”. In current versions of Python, the displayed value is the value whose fraction is as short as possible while giving exactly the same representation when converted back to binary, simply displaying “0.1”.

Using git to get just the latest revision

Alternate solution to doing shallow clone (git clone --depth=1 <URL>) would be, if remote side supports it, to use --remote option of git archive:

$ git archive --format=tar --remote=<repository URL> HEAD | tar xf -

Or, if remote repository in question is browse-able using some web interface like gitweb or GitHub, then there is a chance that it has 'snapshot' feature, and you can download latest version (without versioning information) from web interface.

Lists: Count vs Count()

myList.Count is a method on the list object, it just returns the value of a field so is very fast. As it is a small method it is very likely to be inlined by the compiler (or runtime), they may then allow other optimization to be done by the compiler.

myList.Count() is calling an extension method (introduced by LINQ) that loops over all the items in an IEnumerable, so should be a lot slower.

However (In the Microsoft implementation) the Count extension method has a “special case” for Lists that allows it to use the list’s Count property, this means the Count() method is only a little slower than the Count property.

It is unlikely you will be able to tell the difference in speed in most applications.

So if you know you are dealing with a List use the Count property, otherwise if you have a "unknown" IEnumerabl, use the Count() method and let it optimise for you.

how to convert 2d list to 2d numpy array?

Just pass the list to np.array:

a = np.array(a)

You can also take this opportunity to set the dtype if the default is not what you desire.

a = np.array(a, dtype=...)

Saving image to file

You could try to save the image using this approach

SaveFileDialog dialog = new SaveFileDialog();
if (dialog.ShowDialog() == DialogResult.OK)
   int width = Convert.ToInt32(drawImage.Width); 
   int height = Convert.ToInt32(drawImage.Height); 
   Bitmap bmp = new Bitmap(width,height);        
   drawImage.DrawToBitmap(bmp, new Rectangle(0, 0, width, height);
   bmp.Save(dialog.FileName, ImageFormat.Jpeg);

Does adding a duplicate value to a HashSet/HashMap replace the previous value

It the case of HashSet, it does NOT replace it.

From the docs:

"Adds the specified element to this set if it is not already present. More formally, adds the specified element e to this set if this set contains no element e2 such that (e==null ? e2==null : e.equals(e2)). If this set already contains the element, the call leaves the set unchanged and returns false."

Code signing is required for product type 'Application' in SDK 'iOS 10.0' - StickerPackExtension requires a development team error

I ran into this type error by updating the Xcode version to 8.0, and under the Code signing is required for product type 'Application' in SDK 'iOS 10.0'

There is a warning:

isn't code signed but requires entitlements. It is not possible to add entitlements to a binary without signing it.

My solution is go to the TARGET ? General ? Signing -> click the Enable signing... button, and I solved the issue.

Checking if a double (or float) is NaN in C++

It seems to me that the best truly cross-platform approach would be to use a union and to test the bit pattern of the double to check for NaNs.

I have not thoroughly tested this solution, and there may be a more efficient way of working with the bit patterns, but I think that it should work.

#include <stdint.h>
#include <stdio.h>

union NaN
    uint64_t bits;
    double num;

int main()
    //Test if a double is NaN
    double d = 0.0 / 0.0;
    union NaN n;
    n.num = d;
    if((n.bits | 0x800FFFFFFFFFFFFF) == 0xFFFFFFFFFFFFFFFF)
        printf("NaN: %f", d);

    return 0;

How to wait in a batch script?

You'd better ping Windows ping pauses for one second between pings so you if you want to sleep for 10 seconds, use

ping -n 11 > nul

This way you don't need to worry about unexpected early returns (say, there's no default route and the is instantly known to be unreachable.)

Substring in excel

kennytm's links are dead and he doesn't provide an example so here's how you do substrings:

=MID(text, start_num, char_num)

Let's say cell A1 is Hello.

=MID(A1, 2, 3) 

Would return


Because it says to start at character 2, e, and to return 3 characters.

Tomcat 7 "SEVERE: A child container failed during start"

I recently moved to a new PC all my eclipse projects. I experienced this issue. What i did was:

  1. removed the project from tomcat
  2. clean tomcat
  3. run project in tomcat

Resize on div element

// this is a Jquery plugin function that fires an event when the size of an element is changed
// usage: $().sizeChanged(function(){})

(function ($) {

$.fn.sizeChanged = function (handleFunction) {
    var element = this;
    var lastWidth = element.width();
    var lastHeight = element.height();

    setInterval(function () {
        if (lastWidth === element.width()&&lastHeight === element.height())
        if (typeof (handleFunction) == 'function') {
            handleFunction({ width: lastWidth, height: lastHeight },
                           { width: element.width(), height: element.height() });
            lastWidth = element.width();
            lastHeight = element.height();
    }, 100);

    return element;


How do I 'foreach' through a two-dimensional array?

If you define your array like this:

string[][] table = new string[][] {
                       new string[] { "aa", "aaa" },
                       new string[]{ "bb", "bbb" }

Then you can use a foreach loop on it.

Concat scripts in order with Gulp

I tried several solutions from this page, but none worked. I had a series of numbered files which I simply wanted be ordered by alphabetical foldername so when piped to concat() they'd be in the same order. That is, preserve the order of the globbing input. Easy, right?

Here's my specific proof-of-concept code (print is just to see the order printed to the cli):

var order = require('gulp-order');
var gulp = require('gulp');
var print = require('gulp-print').default;

var options = {};

options.rootPath = {
  inputDir: process.env.INIT_CWD + '/Draft',
  inputGlob: '/**/*.md',

gulp.task('default', function(){
  gulp.src(options.rootPath.inputDir + options.rootPath.inputGlob, {base: '.'})
    .pipe(order([options.rootPath.inputDir + options.rootPath.inputGlob]))

The reason for the madness of gulp.src? I determined that gulp.src was running async when I was able to use a sleep() function (using a .map with sleeptime incremented by index) to order the stream output properly.

The upshot of the async of src mean dirs with more files in it came after dirs with fewer files, because they took longer to process.

Create URL from a String

URL url = new URL(yourUrl, "/api/v1/status.xml");

According to the javadocs this constructor just appends whatever resource to the end of your domain, so you would want to create 2 urls:

URL domain = new URL("");
URL url = new URL(domain + "/files/resource.xml");


Laravel Eloquent Join vs Inner Join?

Probably not what you want to hear, but a "feeds" table would be a great middleman for this sort of transaction, giving you a denormalized way of pivoting to all these data with a polymorphic relationship.

You could build it like this:


Schema::create('feeds', function($table) {

Build the feed model like so:


class Feed extends Eloquent
    protected $fillable = ['user_id', 'target_type', 'target_id'];

    public function user()
        return $this->belongsTo('User');

    public function target()
        return $this->morphTo();

Then keep it up to date with something like:


Vote::created(function(Vote $vote) {
    $target_type = 'Vote';
    $target_id   = $vote->id;
    $user_id     = $vote->user_id;

    Feed::create(compact('target_type', 'target_id', 'user_id'));

You could make the above much more generic/robust—this is just for demonstration purposes.

At this point, your feed items are really easy to retrieve all at once:


Feed::whereIn('user_id', $my_friend_ids)
    ->with('user', 'target')
    ->orderBy('created_at', 'desc')

What does the "__block" keyword mean?

It tells the compiler that any variable marked by it must be treated in a special way when it is used inside a block. Normally, variables and their contents that are also used in blocks are copied, thus any modification done to these variables don't show outside the block. When they are marked with __block, the modifications done inside the block are also visible outside of it.

For an example and more info, see The __block Storage Type in Apple's Blocks Programming Topics.

The important example is this one:

extern NSInteger CounterGlobal;
static NSInteger CounterStatic;

    NSInteger localCounter = 42;
    __block char localCharacter;

    void (^aBlock)(void) = ^(void) {
        CounterGlobal = localCounter; // localCounter fixed at block creation
        localCharacter = 'a'; // sets localCharacter in enclosing scope

    ++localCounter; // unseen by the block
    localCharacter = 'b';

    aBlock(); // execute the block
    // localCharacter now 'a'

In this example, both localCounter and localCharacter are modified before the block is called. However, inside the block, only the modification to localCharacter would be visible, thanks to the __block keyword. Conversely, the block can modify localCharacter and this modification is visible outside of the block.

How to use double or single brackets, parentheses, curly braces


if [ CONDITION ]    Test construct  
if [[ CONDITION ]]  Extended test construct  
Array[1]=element1   Array initialization  
[a-z]               Range of characters within a Regular Expression
$[ expression ]     A non-standard & obsolete version of $(( expression )) [1]


Curly Braces

${variable}                             Parameter substitution  
${!variable}                            Indirect variable reference  
{ command1; command2; . . . commandN; } Block of code  
{string1,string2,string3,...}           Brace expansion  
{a..z}                                  Extended brace expansion  
{}                                      Text replacement, after find and xargs


( command1; command2 )             Command group executed within a subshell  
Array=(element1 element2 element3) Array initialization  
result=$(COMMAND)                  Command substitution, new style  
>(COMMAND)                         Process substitution  
<(COMMAND)                         Process substitution 

Double Parentheses

(( var = 78 ))            Integer arithmetic   
var=$(( 20 + 5 ))         Integer arithmetic, with variable assignment   
(( var++ ))               C-style variable increment   
(( var-- ))               C-style variable decrement   
(( var0 = var1<98?9:21 )) C-style ternary operation

How to run .sh on Windows Command Prompt?

The error message indicates that you have not installed bash, or it is not in your PATH.

The top Google hit is but you also need to understand that most Bash scripts expect a Unix-like environment; so just installing Bash is probably unlikely to allow you to run a script you found on the net, unless it was specifically designed for this particular usage scenario. The usual solution to that is but there are many possible alternatives, depending on what exactly it is that you want to accomplish.

If Windows is not central to your usage scenario, installing a free OS (perhaps virtualized) might be the simplest way forward.

The second error message is due to the fact that Windows nominally accepts forward slash as a directory separator, but in this context, it is being interpreted as a switch separator. In other words, Windows parses your command line as app /build / (or, to paraphrase with Unix option conventions, app --build You could try app\build\ but it is unlikely to work, because of the circumstances outlined above.

How to check if an array is empty?

To check array is null:

int arr[] = null;
if (arr == null) {
 System.out.println("array is null");

To check array is empty:

arr = new int[0];
if (arr.length == 0) {
 System.out.println("array is empty");

Regex to match any character including new lines

Add the s modifier to your regex to cause . to match newlines:

$string =~ /(START)(.+?)(END)/s;

How to save an image to localStorage and display it on the next page?

To whoever also needs this problem solved:

Firstly, I grab my image with getElementByID, and save the image as a Base64. Then I save the Base64 string as my localStorage value.

bannerImage = document.getElementById('bannerImg');
imgData = getBase64Image(bannerImage);
localStorage.setItem("imgData", imgData);

Here is the function that converts the image to a Base64 string:

function getBase64Image(img) {
    var canvas = document.createElement("canvas");
    canvas.width = img.width;
    canvas.height = img.height;

    var ctx = canvas.getContext("2d");
    ctx.drawImage(img, 0, 0);

    var dataURL = canvas.toDataURL("image/png");

    return dataURL.replace(/^data:image\/(png|jpg);base64,/, "");

Then, on my next page I created an image with a blank src like so:

<img src="" id="tableBanner" />

And straight when the page loads, I use these next three lines to get the Base64 string from localStorage, and apply it to the image with the blank src I created:

var dataImage = localStorage.getItem('imgData');
bannerImg = document.getElementById('tableBanner');
bannerImg.src = "data:image/png;base64," + dataImage;

Tested it in quite a few different browsers and versions, and it seems to work quite well.

How to display errors for my MySQLi query?

Just simply add or die(mysqli_error($db)); at the end of your query, this will print the mysqli error.

 mysqli_query($db,"INSERT INTO stockdetails (`itemdescription`,`itemnumber`,`sellerid`,`purchasedate`,`otherinfo`,`numberofitems`,`isitdelivered`,`price`) VALUES ('$itemdescription','$itemnumber','$sellerid','$purchasedate','$otherinfo','$numberofitems','$numberofitemsused','$isitdelivered','$price')") or die(mysqli_error($db));

As a side note I'd say you are at risk of mysql injection, check here How can I prevent SQL injection in PHP?. You should really use prepared statements to avoid any risk.

How to tell if a file is git tracked (by shell exit code)?

Just my two cents:

git ls-files | grep -x relative/path

where relative/path can be easily determined by pressing tab within an auto-completion shell. Add an additional | wc -l to get a 1 or 0 output.

Activity, AppCompatActivity, FragmentActivity, and ActionBarActivity: When to Use Which?

Activity is the base class of all other activities, I don't think it will be deprecated. The relationship among them is:

Activity <- FragmentActivity <- AppCompatActivity <- ActionBarActivity

'<-' means inheritance here. The reference said ActionBarActivity is deprecated, use AppCompatActivity instead.

So basically, using AppCompatActivity is always the right choice. The differences between them are:

  • Activity is the basic one.
  • Based on Activity, FragmentActivity provides the ability to use Fragment.
  • Based on FragmentActivity, AppCompatActivity provides features to ActionBar.

How to create a sticky navigation bar that becomes fixed to the top after scrolling

In answer to Shubham Patwa: This way, the page is "jumpy" soon as the class "navbar-fixed-top" applies. That's because the #mainnav is throwen in and out of the document's DOM flow. This can result in an ugly UX if the page has a "critical height", jumping between fixed and un-fixed #mainnav position.

I altered the code this way, which seems to work fine (not pixel-perfect, but fine):

$(document).ready(function() {
  var navpos = $('#mainnav').offset();
  var navheight = $('#mainnav').outerHeight();

$(window).bind('scroll', function() {
  if ($(window).scrollTop() > {
   else {

How to check if memcache or memcached is installed for PHP?

You can look at phpinfo() or check if any of the functions of memcache is available. Ultimately, check whether the Memcache class exists or not.


  // Memcache is enabled.

How do I pass a datetime value as a URI parameter in mvc?

Try to use toISOString(). It returns string in ISO8601 format.

from javascript

$.get('/example/doGet?date=' + new Date().toISOString(), function (result) {

from c#

public JsonResult DoGet(DateTime date)
    return Json(date.ToString(), JsonRequestBehavior.AllowGet);

How to empty a char array?

members[0] = 0;

is enough, given your requirements.

Notice however this is not "emptying" the buffer. The memory is still allocated, valid character values may still exist in it, and so forth..

Need a row count after SELECT statement: what's the optimal SQL approach?

If you're using SQL Server, after your query you can select the @@RowCount function (or if your result set might have more than 2 billion rows use the RowCount_Big() function). This will return the number of rows selected by the previous statement or number of rows affected by an insert/update/delete statement.

SELECT my_table.my_col
  FROM my_table
 WHERE = 'bar'

SELECT @@Rowcount

Or if you want to row count included in the result sent similar to Approach #2, you can use the the OVER clause.

SELECT my_table.my_col,
    count(*) OVER(PARTITION BY AS 'Count'
  FROM my_table
 WHERE = 'bar'

Using the OVER clause will have much better performance than using a subquery to get the row count. Using the @@RowCount will have the best performance because the there won't be any query cost for the select @@RowCount statement

Update in response to comment: The example I gave would give the # of rows in partition - defined in this case by "PARTITION BY". The value of the column in each row is the # of rows with the same value of Since your example query had the clause "WHERE = 'bar'", all rows in the resultset will have the same value of and therefore the value in the column will be the same for all rows and equal (in this case) this the # of rows in the query.

Here is a better/simpler example of how to include a column in each row that is the total # of rows in the resultset. Simply remove the optional Partition By clause.

SELECT my_table.my_col, count(*) OVER() AS 'Count'
  FROM my_table
 WHERE = 'bar'

How to set array length in c# dynamically

If you don't want to use a List, ArrayList, or other dynamically-sized collection and then convert to an array (that's the method I'd recommend, by the way), then you'll have to allocate the array to its maximum possible size, keep track of how many items you put in it, and then create a new array with just those items in it:

private Update BuildMetaData(MetaData[] nvPairs)
    Update update = new Update();
    InputProperty[] ip = new InputProperty[20];  // how to make this "dynamic"
    int i;
    for (i = 0; i < nvPairs.Length; i++)
        if (nvPairs[i] == null) break;
        ip[i] = new InputProperty(); 
        ip[i].Name = "udf:" + nvPairs[i].Name;
        ip[i].Val = nvPairs[i].Value;
    if (i < nvPairs.Length)
        // Create new, smaller, array to hold the items we processed.
        update.Items = new InputProperty[i];
        Array.Copy(ip, update.Items, i);
        update.Items = ip;
    return update;

An alternate method would be to always assign update.Items = ip; and then resize if necessary:

update.Items = ip;
if (i < nvPairs.Length)
    Array.Resize(update.Items, i);

It's less code, but will likely end up doing the same amount of work (i.e. creating a new array and copying the old items).

How to fill OpenCV image with one solid color?

For an 8-bit (CV_8U) OpenCV image, the syntax is:

Mat img(Mat(nHeight, nWidth, CV_8U);
img = cv::Scalar(50);    // or the desired uint8_t value from 0-255

c# datagridview doubleclick on row with FullRowSelect

I think you are looking for this: RowHeaderMouseDoubleClick event

private void DgwModificar_RowHeaderMouseDoubleClick(object sender, DataGridViewCellMouseEventArgs e) {

to get the row index:

int indice = e.RowIndex

"Content is not allowed in prolog" when parsing perfectly valid XML on GAE

In my instance of the problem, the solution was to replace german umlauts (äöü) with their HTML-equivalents...

How to terminate a Python script

In Python 3.5, I tried to incorporate similar code without use of modules (e.g. sys, Biopy) other than what's built-in to stop the script and print an error message to my users. Here's my example:

## My example:
if "ATG" in my_DNA: 
    ## <Do something & proceed...>
    print("Start codon is missing! Check your DNA sequence!")
    exit() ## as most folks said above

Later on, I found it is more succinct to just throw an error:

## My example revised:
if "ATG" in my_DNA: 
    ## <Do something & proceed...>
    raise ValueError("Start codon is missing! Check your DNA sequence!")

How to create a localhost server to run an AngularJS project

cd <your project folder> (where your angularjs's deployable code is there)

sudo npm install serve -g


You can hit your page at

localhost:3000 or IPaddress:3000

Generate table relationship diagram from existing schema (SQL Server)

MySQL WorkBench is free software and is developed by Oracle, you can import an SQL File or specify a database and it will generate an SQL Diagram which you can move around to make it more visually appealing. It runs on GNU/Linux and Windows and it's free and has a professional look..

Disable Transaction Log

If this is only for dev machines in order to save space then just go with simple recovery mode and you’ll be doing fine.

On production machines though I’d strongly recommend that you keep the databases in full recovery mode. This will ensure you can do point in time recovery if needed.

Also – having databases in full recovery mode can help you to undo accidental updates and deletes by reading transaction log. See below or more details.

How can I rollback an UPDATE query in SQL server 2005?

Read the log file (*.LDF) in sql server 2008

If space is an issue on production machines then just create frequent transaction log backups.

SQL is null and = null

I think that equality is something that can be absolutely determined. The trouble with null is that it's inherently unknown. Null combined with any other value is null - unknown. Asking SQL "Is my value equal to null?" would be unknown every single time, even if the input is null. I think the implementation of IS NULL makes it clear.

How to scale an Image in ImageView to keep the aspect ratio

Pass your ImageView and based on screen height and width you can make it

    public void setScaleImage(EventAssetValueListenerView view){
        // Get the ImageView and its bitmap
        Drawable drawing = view.getDrawable();
        Bitmap bitmap = ((BitmapDrawable)drawing).getBitmap();
        // Get current dimensions
        int width = bitmap.getWidth();
        int height = bitmap.getHeight();

        float xScale = ((float) 4) / width;
        float yScale = ((float) 4) / height;
        float scale = (xScale <= yScale) ? xScale : yScale;

        Matrix matrix = new Matrix();
        matrix.postScale(scale, scale);

        Bitmap scaledBitmap = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix, true);
        BitmapDrawable result = new BitmapDrawable(scaledBitmap);
        width = scaledBitmap.getWidth();
        height = scaledBitmap.getHeight();


        LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) view.getLayoutParams();
        params.width = width;
        params.height = height;

How to update column with null value

If you want to set null value using update query set column value to NULL (without quotes) update tablename set columnname = NULL

However, if you are directly editing field value inside mysql workbench then use (Esc + del) keystroke to insert null value into selected column

Connecting to local SQL Server database using C#

If you use SQL authentication, use this:

using System.Data.SqlClient;

SqlConnection conn = new SqlConnection();
conn.ConnectionString = 
     "Data Source=.\SQLExpress;" + 
     "User Instance=true;" + 
     "User Id=UserName;" + 
     "Password=Secret;" + 

If you use Windows authentication, use this:

using System.Data.SqlClient;
SqlConnection conn = new SqlConnection();
conn.ConnectionString = 
     "Data Source=.\SQLExpress;" + 
     "User Instance=true;" + 
     "Integrated Security=true;" + 

Does a finally block always get executed in Java?

finally can also be exited prematurely if an Exception is thrown inside a nested finally block. The compiler will warn you that the finally block does not complete normally or give an error that you have unreachable code. The error for unreachable code will be shown only if the throw is not behind a conditional statement or inside a loop.

      //if(someCondition) --> no error because of unreachable code
      throw new RunTimeException();
   int a = 5;//unreachable code

How to style the option of an html "select" element?

As already mentioned, the only way is to use a plugin that replaces <select> functionality.

A list of jQuery plugins:

Take a look at the example using Select2 plugin:

Converting a JToken (or string) to a given Type

System.Convert.ChangeType(jtoken.ToString(), targetType);


JsonConvert.DeserializeObject(jtoken.ToString(), targetType);


Uzair, Here is a complete example just to show you they work

string json = @"{
        ""id"" : 77239923,
        ""username"" : ""UzEE"",
        ""email"" : ""[email protected]"",
        ""name"" : ""Uzair Sajid"",
        ""twitter_screen_name"" : ""UzEE"",
        ""join_date"" : ""2012-08-13T05:30:23Z05+00"",
        ""timezone"" : 5.5,
        ""access_token"" : {
            ""token"" : ""nkjanIUI8983nkSj)*#)(kjb@K"",
            ""scope"" : [ ""read"", ""write"", ""bake pies"" ],
            ""expires"" : 57723
        ""friends"" : [{
            ""id"" : 2347484,
            ""name"" : ""Bruce Wayne""
            ""id"" : 996236,
            ""name"" : ""Clark Kent""

var obj = (JObject)JsonConvert.DeserializeObject(json);
Type type = typeof(int);
var i1 = System.Convert.ChangeType(obj["id"].ToString(), type);
var i2 = JsonConvert.DeserializeObject(obj["id"].ToString(), type);

What is the best way to iterate over multiple lists at once?

The usual way is to use zip():

for x, y in zip(a, b):
    # x is from a, y is from b

This will stop when the shorter of the two iterables a and b is exhausted. Also worth noting: itertools.izip() (Python 2 only) and itertools.izip_longest() (itertools.zip_longest() in Python 3).

How do I replicate a \t tab space in HTML?

This simple formula should work. Give the element whose text will contain a tab the following CSS property: white-space:pre. Otherwise your html may not render tabs at all. Then, wherever you want to have a tab in your text, type &#9;.

Since you didn't mention CSS, if you want to do this without a CSS file, just use

<tag-name style="white-space:pre">text in element&#9;more text</tag-name>

in your HTML.

What is the purpose of the "final" keyword in C++11 for functions?

Supplement to Mario Knezovic 's answer:

class IA
  virtual int getNum() const = 0;

class BaseA : public IA
 inline virtual int getNum() const final {return ...};

class ImplA : public BaseA {...};

IA* pa = ...;
ImplA* impla = static_cast<ImplA*>(pa);

//the following line should cause compiler to use the inlined function BaseA::getNum(), 
//instead of dynamic binding (via vtable or something).
//any class/subclass of BaseA will benefit from it

int n = impla->getNum();

The above code shows the theory, but not actually tested on real compilers. Much appreciated if anyone paste a disassembled output.

Checking for duplicate strings in JavaScript array

var strArray = [ "q", "w", "w", "e", "i", "u", "r", "q"];
var alreadySeen = [];

strArray.forEach(function(str) {
  if (alreadySeen[str])
    alreadySeen[str] = true;

I added another duplicate in there from your original just to show it would find a non-consecutive duplicate.

Updated version with arrow function:

const strArray = [ "q", "w", "w", "e", "i", "u", "r", "q"];
const alreadySeen = [];

strArray.forEach(str => alreadySeen[str] ? alert(str) : alreadySeen[str] = true);

SQL Server Configuration Manager not found

If you don't have any version of SQLServerManagerXX.msc, then you simply do not have it installed. I noticed it does not come with SQL server management studio 2019.

It's available (client-connectivity tools) in the SQL Server Express edition or SQL Server Developer edition which is good for dev/test (non-production) usage.

Is an empty href valid?

Try to do <a href="#" class="arrow"> instead. (Note the sharp # character).

git is not installed or not in the PATH

Use Git CMD instead of using Win CMD.

Saving awk output to variable

I think the $() syntax is easier to read...

variable=$(ps -ef | grep "port 10 -" | grep -v "grep port 10 -"| awk '{printf "%s", $12}')

But the real issue is probably that $12 should not be qouted with ""

Edited since the question was changed, This returns valid data, but it is not clear what the expected output of ps -ef is and what is expected in variable.

What is the best way to uninstall gems from a rails3 project?

I seemed to solve this by manually removing the unicorn gem via bundler ("sudo bundler exec gem uninstall unicorn"), then rebundling ("sudo bundle install").

Not sure why it happened though, although the above fix does seem to work.

Error: request entity too large

The better use you can specify the limit of your file size as it is shown in the given lines:

app.use(bodyParser.json({limit: '10mb', extended: true}))
app.use(bodyParser.urlencoded({limit: '10mb', extended: true}))

You can also change the default setting in node-modules body-parser then in the lib folder, there are JSON and text file. Then change limit here. Actually, this condition pass if you don't pass the limit parameter in the given line app.use(bodyParser.json({limit: '10mb', extended: true})).

Get current batchfile directory

Here's what I use at the top of all my batch files. I just copy/paste from my template folder.

@echo off
set batdir=%~dp0
:: set batdir=%CD%
pushd "%batdir%"

Setting current batch file's path to %batdir% allows you to call it in subsequent stmts in current batch file, regardless of where this batch file changes to. Using PUSHD allows you to use POPD to quickly set this batch file's path to original %batdir%. Remember, if using %batdir%ExtraDir or %batdir%\ExtraDir (depending on which version used above, ending backslash or not) you will need to enclose the entire string in double quotes if path has spaces (i.e. "%batdir%ExtraDir"). You can always use PUSHD %~dp0. [https: // nt/ syntax-args .html] has more on (%~) parameters.

Note that using (::) at beginning of a line makes it a comment line. More importantly, using :: allows you to include redirectors, pipes, special chars (i.e. < > | etc) in that comment.

:: ORIG STMT WAS: dir *.* | find /v "1917" > outfile.txt

Of course, Powershell does this and lots more.

JUnit Testing private variables?

I can't tell if you've found some special case code which requires you to test against private fields. But in my experience you never have to test something private - always public. Maybe you could give an example of some code where you need to test private?

Conditional formatting using AND() function

This is probably because of the column() and row() functions. I am not sure how they are applied in conditional formatting. Try creating a new column with the value from this formula and then use it for your formatting needs.

Trimming text strings in SQL Server 2008

SQL Server does not have a TRIM function, but rather it has two. One each for specifically trimming spaces from the "front" of a string (LTRIM) and one for trimming spaces from the "end" of a string (RTRIM).

Something like the following will update every record in your table, trimming all extraneous space (either at the front or the end) of a varchar/nvarchar field:

   [YourFieldName] = LTRIM(RTRIM([YourFieldName]))

(Strangely, SSIS (Sql Server Integration Services) does have a single TRIM function!)

CSS table layout: why does table-row not accept a margin?

How's this for a work around (using an actual table)?

table {
    border-collapse: collapse;

tr.row {
    border-bottom: solid white 30px; /* change "white" to your background color */

It's not as dynamic, since you have to explicitly set the color of the border (unless there's a way around that too), but this is something I'm experimenting with on a project of my own.

Edit to include comments regarding transparent:

tr.row {
    border-bottom: 30px solid transparent;

How do I run msbuild from the command line using Windows SDK 7.1?

For Visual Studio 2019 (Preview, at least) it is now in:

C:\Program Files (x86)\Microsoft Visual Studio\2019\Preview\MSBuild\Current\Bin\MSBuild.exe

I imagine the process will be similar for the official 2019 release.

XPath - Difference between node() and text()

text() and node() are node tests, in XPath terminology (compare).

Node tests operate on a set (on an axis, to be exact) of nodes and return the ones that are of a certain type. When no axis is mentioned, the child axis is assumed by default.

There are all kinds of node tests:

  • node() matches any node (the least specific node test of them all)
  • text() matches text nodes only
  • comment() matches comment nodes
  • * matches any element node
  • foo matches any element node named "foo"
  • processing-instruction() matches PI nodes (they look like <?name value?>).
  • Side note: The * also matches attribute nodes, but only along the attribute axis. @* is a shorthand for attribute::*. Attributes are not part of the child axis, that's why a normal * does not select them.

This XML document:


represents the following DOM (simplified):

root node
   element node (name="produce")
      text node (value="\n    ")
      element node (name="item")
         text node (value="apple")
      text node (value="\n    ")
      element node (name="item")
         text node (value="banana")
      text node (value="\n    ")
      element node (name="item")
         text node (value="pepper")
      text node (value="\n")

So with XPath:

  • / selects the root node
  • /produce selects a child element of the root node if it has the name "produce" (This is called the document element; it represents the document itself. Document element and root node are often confused, but they are not the same thing.)
  • /produce/node() selects any type of child node beneath /produce/ (i.e. all 7 children)
  • /produce/text() selects the 4 (!) whitespace-only text nodes
  • /produce/item[1] selects the first child element named "item"
  • /produce/item[1]/text() selects all child text nodes (there's only one - "apple" - in this case)

And so on.

So, your questions

  • "Select the text of all items under produce" /produce/item/text() (3 nodes selected)
  • "Select all the manager nodes in all departments" //department/manager (1 node selected)


  • The default axis in XPath is the child axis. You can change the axis by prefixing a different axis name. For example: //item/ancestor::produce
  • Element nodes have text values. When you evaluate an element node, its textual contents will be returned. In case of this example, /produce/item[1]/text() and string(/produce/item[1]) will be the same.
  • Also see this answer where I outline the individual parts of an XPath expression graphically.

How to get UTC time in Python?

import datetime
import pytz

# datetime object with timezone awareness:

# seconds from epoch: 

# ms from epoch:
int( * 1000) 

"Cannot verify access to path (C:\inetpub\wwwroot)", when adding a virtual directory

I was having the same issue till just now; just as you mentioned, I tried "Connect As" and the username and password that I wrote down, was my machine's user (IIS is running on this machine), I tested the connection and it works now. Maybe if you weren't using that machine's user (try user with administrator privileges), you should give it a try, it worked for me, it may work in your case as well.

SQL ORDER BY multiple columns

yes,the sorting proceed differently. in first scenario, orders based on column1 and in addition to that process further by sorting colmun2 based on column1 .. in second scenario ,it orders completely based on column 1 only... please proceed with a simple example...u will get quickly..

Leap year calculation

Python 3.5

def is_leap_baby(year):
    if ((year % 4 is 0) and (year % 100 is not 0)) or (year % 400 is 0):
        return "{0}, {1} is a leap year".format(True, year)
    return "{0} is not a leap year".format(year)


Bootstrap 3 Collapse show state with Chevron icon

For the following HTML (from Bootstrap 3 examples):

.panel-heading .accordion-toggle:after {_x000D_
    /* symbol for "opening" panels */_x000D_
    font-family: 'Glyphicons Halflings';  /* essential for enabling glyphicon */_x000D_
    content: "\e114";    /* adjust as needed, taken from bootstrap.css */_x000D_
    float: right;        /* adjust as needed */_x000D_
    color: grey;         /* adjust as needed */_x000D_
.panel-heading .accordion-toggle.collapsed:after {_x000D_
    /* symbol for "collapsed" panels */_x000D_
    content: "\e080";    /* adjust as needed, taken from bootstrap.css */_x000D_
<link href="//" rel="stylesheet" />_x000D_
<script src="" type="text/javascript" ></script>_x000D_
<script src="//" type="text/javascript" ></script>_x000D_
<div class="panel-group" id="accordion">_x000D_
  <div class="panel panel-default">_x000D_
    <div class="panel-heading">_x000D_
      <h4 class="panel-title">_x000D_
        <a class="accordion-toggle" data-toggle="collapse" data-parent="#accordion" href="#collapseOne">_x000D_
          Collapsible Group Item #1_x000D_
    <div id="collapseOne" class="panel-collapse collapse in">_x000D_
      <div class="panel-body">_x000D_
        Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor, sunt aliqua put a bird on it squid single-origin coffee nulla assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat craft beer farm-to-table, raw denim aesthetic synth nesciunt you probably haven't heard of them accusamus labore sustainable VHS._x000D_
  <div class="panel panel-default">_x000D_
    <div class="panel-heading">_x000D_
      <h4 class="panel-title">_x000D_
        <a class="accordion-toggle collapsed" data-toggle="collapse" data-parent="#accordion" href="#collapseTwo">_x000D_
          Collapsible Group Item #2_x000D_
    <div id="collapseTwo" class="panel-collapse collapse">_x000D_
      <div class="panel-body">_x000D_
        Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor, sunt aliqua put a bird on it squid single-origin coffee nulla assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat craft beer farm-to-table, raw denim aesthetic synth nesciunt you probably haven't heard of them accusamus labore sustainable VHS._x000D_
  <div class="panel panel-default">_x000D_
    <div class="panel-heading">_x000D_
      <h4 class="panel-title">_x000D_
        <a class="accordion-toggle collapsed" data-toggle="collapse" data-parent="#accordion" href="#collapseThree">_x000D_
          Collapsible Group Item #3_x000D_
    <div id="collapseThree" class="panel-collapse collapse">_x000D_
      <div class="panel-body">_x000D_
        Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor, sunt aliqua put a bird on it squid single-origin coffee nulla assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat craft beer farm-to-table, raw denim aesthetic synth nesciunt you probably haven't heard of them accusamus labore sustainable VHS._x000D_

Visual effect:

bootstrap3 chevron icon on accordion

How to sort a list of lists by a specific index of the inner list?

in place

>>> l = [[0, 1, 'f'], [4, 2, 't'], [9, 4, 'afsd']]
>>> l.sort(key=lambda x: x[2])

not in place using sorted:

>>> sorted(l, key=lambda x: x[2])

Difference between two dates in Python

Another short solution:

from datetime import date

def diff_dates(date1, date2):
    return abs(date2-date1).days

def main():
    d1 = date(2013,1,1)
    d2 = date(2013,9,13)
    result1 = diff_dates(d2, d1)
    print '{} days between {} and {}'.format(result1, d1, d2)
    print ("Happy programmer's day!")


How to upload, display and save images using node.js and express

First of all, you should make an HTML form containing a file input element. You also need to set the form's enctype attribute to multipart/form-data:

<form method="post" enctype="multipart/form-data" action="/upload">
    <input type="file" name="file">
    <input type="submit" value="Submit">

Assuming the form is defined in index.html stored in a directory named public relative to where your script is located, you can serve it this way:

const http = require("http");
const path = require("path");
const fs = require("fs");

const express = require("express");

const app = express();
const httpServer = http.createServer(app);

const PORT = process.env.PORT || 3000;

httpServer.listen(PORT, () => {
  console.log(`Server is listening on port ${PORT}`);

// put the HTML file containing your form in a directory named "public" (relative to where this script is located)
app.get("/", express.static(path.join(__dirname, "./public")));

Once that's done, users will be able to upload files to your server via that form. But to reassemble the uploaded file in your application, you'll need to parse the request body (as multipart form data).

In Express 3.x you could use express.bodyParser middleware to handle multipart forms but as of Express 4.x, there's no body parser bundled with the framework. Luckily, you can choose from one of the many available multipart/form-data parsers out there. Here, I'll be using multer:

You need to define a route to handle form posts:

const multer = require("multer");

const handleError = (err, res) => {
    .end("Oops! Something went wrong!");

const upload = multer({
  dest: "/path/to/temporary/directory/to/store/uploaded/files"
  // you might also want to set some limits:
  upload.single("file" /* name attribute of <file> element in your form */),
  (req, res) => {
    const tempPath = req.file.path;
    const targetPath = path.join(__dirname, "./uploads/image.png");

    if (path.extname(req.file.originalname).toLowerCase() === ".png") {
      fs.rename(tempPath, targetPath, err => {
        if (err) return handleError(err, res);

          .end("File uploaded!");
    } else {
      fs.unlink(tempPath, err => {
        if (err) return handleError(err, res);

          .end("Only .png files are allowed!");

In the example above, .png files posted to /upload will be saved to uploaded directory relative to where the script is located.

In order to show the uploaded image, assuming you already have an HTML page containing an img element:

<img src="/image.png" />

you can define another route in your express app and use res.sendFile to serve the stored image:

app.get("/image.png", (req, res) => {
  res.sendFile(path.join(__dirname, "./uploads/image.png"));

Android ADB stop application command like "force-stop" for non rooted device

If you want to kill the Sticky Service,the following command NOT WORKING:

adb shell am force-stop <PACKAGE>
adb shell kill <PID>

The following command is WORKING:

adb shell pm disable <PACKAGE>

If you want to restart the app,you must run command below first:

adb shell pm enable <PACKAGE>

Set View Width Programmatically

yourView.setLayoutParams(new LinearLayout.LayoutParams(width, height));

Execution failed for task ':app:compileDebugAidl': aidl is missing

I am working with sdk 23.1.0 and gradle 1.3.1. I created a new project edited nothing and got the aidl error. I went into my project gradle file and changed tool to 22.0.1 instead of 23.1.0 and it worked:

   compileSdkVersion 23
   buildToolsVersion "22.0.1" //"23.1.0"

Project Links do not work on Wamp Server

Open index.php in www folder and set

$suppress_localhost = false;

This will prepend http://localhost/ to your project links

hexadecimal string to byte array in python

Assuming you have a byte string like so


and you know the amount of bytes and their type you can also use this approach

import struct

bytes = '\x12\x45\x00\xAB'
val = struct.unpack('<BBH', bytes)

#val = (18, 69, 43776)

As I specified little endian (using the '<' char) at the start of the format string the function returned the decimal equivalent.

0x12 = 18

0x45 = 69

0xAB00 = 43776

B is equal to one byte (8 bit) unsigned

H is equal to two bytes (16 bit) unsigned

More available characters and byte sizes can be found here

The advantages are..

You can specify more than one byte and the endian of the values


You really need to know the type and length of data your dealing with

How to show Page Loading div until the page has finished loading?

Default the contents to display:none and then have an event handler that sets it to display:block or similar after it's fully loaded. Then have a div that's set to display:block with "Loading" in it, and set it to display:none in the same event handler as before.

cat, grep and cut - translated to python

you need to use os.system module to execute shell command

import os

if you want to save the output for later use, you need to use subprocess module

import subprocess
child = subprocess.Popen('command',stdout=subprocess.PIPE,shell=True)
output = child.communicate()[0]

Center image horizontally within a div

CSS flexbox can do it with justify-content: center on the image parent element. To preserve the aspect ratio of the image, add align-self: flex-start; to it.


<div class="image-container">
  <img src="" />


.image-container {
  display: flex;
  justify-content: center;


body {_x000D_
  background: lightgray;_x000D_
.image-container {_x000D_
  width: 200px;_x000D_
  display: flex;_x000D_
  justify-content: center;_x000D_
  margin: 10px;_x000D_
  padding: 10px;_x000D_
  /* Material design properties */_x000D_
  background: #fff;_x000D_
  box-shadow: 0 2px 2px 0 rgba(0, 0, 0, 0.14), 0 3px 1px -2px rgba(0, 0, 0, 0.2), 0 1px 5px 0 rgba(0, 0, 0, 0.12);_x000D_
.image-2 {_x000D_
  width: 500px;_x000D_
  align-self: flex-start;  /* to preserve image aspect ratio */_x000D_
.image-3 {_x000D_
  width: 300px;_x000D_
  align-self: flex-start;  /* to preserve image aspect ratio */_x000D_
<div class="image-container">_x000D_
  <img src="" />_x000D_
<div class="image-container image-2">_x000D_
  <img src="" />_x000D_
<div class="image-container image-3">_x000D_
  <img src="" />_x000D_

Replace \n with <br />

You could also have problems if the string has <, > or & chars in it, etc. Pass it to cgi.escape() to deal with those.

Initializing array of structures

It's a designated initializer, introduced with the C99 standard; it allows you to initialize specific members of a struct or union object by name. my_data is obviously a typedef for a struct type that has a member name of type char * or char [N].

Delete cookie by name?

I'm not really sure if that was the situation with Roundcube version from May '12, but for current one the answer is that you can't delete roundcube_sessauth cookie from JavaScript, as it is marked as HttpOnly. And this means it's not accessible from JS client side code and can be removed only by server side script or by direct user action (via some browser mechanics like integrated debugger or some plugin).

Copy the entire contents of a directory in C#

Hmm, I think I misunderstand the question but I'm going to risk it. What's wrong with the following straightforward method?

public static void CopyFilesRecursively(DirectoryInfo source, DirectoryInfo target) {
    foreach (DirectoryInfo dir in source.GetDirectories())
        CopyFilesRecursively(dir, target.CreateSubdirectory(dir.Name));
    foreach (FileInfo file in source.GetFiles())
        file.CopyTo(Path.Combine(target.FullName, file.Name));

EDIT Since this posting has garnered an impressive number of downvotes for such a simple answer to an equally simple question, let me add an explanation. Please read this before downvoting.

First of all, this code is not intendend as a drop-in replacement to the code in the question. It is for illustration purpose only.

Microsoft.VisualBasic.Devices.Computer.FileSystem.CopyDirectory does some additional correctness tests (e.g. whether the source and target are valid directories, whether the source is a parent of the target etc.) that are missing from this answer. That code is probably also more optimized.

That said, the code works well. It has (almost identically) been used in a mature software for years. Apart from the inherent fickleness present with all IO handlings (e.g. what happens if the user manually unplugs the USB drive while your code is writing to it?), there are no known problems.

In particular, I’d like to point out that the use of recursion here is absolutely not a problem. Neither in theory (conceptually, it’s the most elegant solution) nor in practice: this code will not overflow the stack. The stack is large enough to handle even deeply nested file hierarchies. Long before stack space becomes a problem, the folder path length limitation kicks in.

Notice that a malicious user might be able to break this assumption by using deeply-nested directories of one letter each. I haven’t tried this. But just to illustrate the point: in order to make this code overflow on a typical computer, the directories would have to be nested a few thousand times. This is simply not a realistic scenario.

Most useful NLog configurations

Reporting to an external website/database

I wanted a way to simply and automatically report errors (since users often don't) from our applications. The easiest solution I could come up with was a public URL - a web page which could take input and store it to a database - that is sent data upon an application error. (The database could then be checked by a dev or a script to know if there are new errors.)

I wrote the web page in PHP and created a mysql database, user, and table to store the data. I decided on four user variables, an id, and a timestamp. The possible variables (either included in the URL or as POST data) are:

  • app (application name)
  • msg (message - e.g. Exception occurred ...)
  • dev (developer - e.g. Pat)
  • src (source - this would come from a variable pertaining to the machine on which the app was running, e.g. Environment.MachineName or some such)
  • log (a log file or verbose message)

(All of the variables are optional, but nothing is reported if none of them are set - so if you just visit the website URL nothing is sent to the db.)

To send the data to the URL, I used NLog's WebService target. (Note, I had a few problems with this target at first. It wasn't until I looked at the source that I figured out that my url could not end with a /.)

All in all, it's not a bad system for keeping tabs on external apps. (Of course, the polite thing to do is to inform your users that you will be reporting possibly sensitive data and to give them a way to opt in/out.)

MySQL stuff

(The db user has only INSERT privileges on this one table in its own database.)

CREATE TABLE `reports` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `applicationName` text,
  `message` text,
  `developer` text,
  `source` text,
  `logData` longtext,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8 COMMENT='storage place for reports from external applications'

Website code

(PHP 5.3 or 5.2 with PDO enabled, file is index.php in /report folder)

$app = $_REQUEST['app'];
$msg = $_REQUEST['msg'];
$dev = $_REQUEST['dev'];
$src = $_REQUEST['src'];
$log = $_REQUEST['log'];

$dbData =
    array(  ':app' => $app,
            ':msg' => $msg,
            ':dev' => $dev,
            ':src' => $src,
            ':log' => $log
//print_r($dbData); // For debugging only! This could allow XSS attacks.
if(isEmpty($dbData)) die("No data provided");

try {
$db = new PDO("mysql:host=$host;dbname=reporting", "reporter", $pass, array(
$s = $db->prepare("INSERT INTO reporting.reports 
print "Added report to database";
} catch (PDOException $e) {
// Sensitive information can be displayed if this exception isn't handled
//print "Error!: " . $e->getMessage() . "<br/>";
die("PDO error");

function isEmpty($array = array()) {
    foreach ($array as $element) {
        if (!empty($element)) {
            return false;
    return true;

App code (NLog config file)

<nlog xmlns="" xmlns:xsi=""
      throwExceptions="true" internalLogToConsole="true" internalLogLevel="Warn" internalLogFile="nlog.log">
    <variable name="appTitle" value="My External App"/>
    <variable name="csvPath" value="${specialfolder:folder=Desktop:file=${appTitle} log.csv}"/>
    <variable name="developer" value="Pat"/>

    <targets async="true">
        <!--The following will keep the default number of log messages in a buffer and write out certain levels if there is an error and other levels if there is not. Messages that appeared before the error (in code) will be included, since they are buffered.-->
        <wrapper-target xsi:type="BufferingWrapper" name="smartLog">
            <wrapper-target xsi:type="PostFilteringWrapper">
                <target xsi:type="File" fileName="${csvPath}"
                archiveAboveSize="4194304" concurrentWrites="false" maxArchiveFiles="1" archiveNumbering="Sequence"
                    <layout xsi:type="CsvLayout" delimiter="Comma" withHeader="false">
                        <column name="time" layout="${longdate}" />
                        <column name="level" layout="${level:upperCase=true}"/>
                        <column name="message" layout="${message}" />
                        <column name="callsite" layout="${callsite:includeSourcePath=true}" />
                        <column name="stacktrace" layout="${stacktrace:topFrames=10}" />
                        <column name="exception" layout="${exception:format=ToString}"/>
                        <!--<column name="logger" layout="${logger}"/>-->

                 <!--during normal execution only log certain messages--> 
                <defaultFilter>level >= LogLevel.Warn</defaultFilter>

                 <!--if there is at least one error, log everything from trace level--> 
                <when exists="level >= LogLevel.Error" filter="level >= LogLevel.Trace" />

        <target xsi:type="WebService" name="web"
            <parameter name="app" layout="${appTitle}"/>
            <parameter name="msg" layout="${message}"/>
            <parameter name="dev" layout="${developer}"/>
            <parameter name="src" layout="${environment:variable=UserName} (${windows-identity}) on ${machinename} running os ${environment:variable=OSVersion} with CLR v${environment:variable=Version}"/>
            <parameter name="log" layout="${file-contents:fileName=${csvPath}}"/>


        <logger name="*" minlevel="Trace" writeTo="smartLog"/>
        <logger name="*" minlevel="Error" writeTo="web"/>

Note: there may be some issues with the size of the log file, but I haven't figured out a simple way to truncate it (e.g. a la *nix's tail command).

Delete directory with files in it?

What about this:

function recursiveDelete($dirPath, $deleteParent = true){
    foreach(new RecursiveIteratorIterator(new RecursiveDirectoryIterator($dirPath, FilesystemIterator::SKIP_DOTS), RecursiveIteratorIterator::CHILD_FIRST) as $path) {
        $path->isFile() ? unlink($path->getPathname()) : rmdir($path->getPathname());
    if($deleteParent) rmdir($dirPath);

How to make an AlertDialog in Flutter?

Check out Flutter Dropdown Banner to easily alert users of events and prompt action without having to manage the complexity of presenting, delaying, and dismissing the component.

To set it up:

import 'packages:dropdown_banner/dropdown_banner.dart';
class MainApp extends StatelessWidget {
  Widget build(BuildContext context) {
    final navigatorKey = GlobalKey<NavigatorState>();
    return MaterialApp(
        home: DropdownBanner(
          child: Scaffold(...),
          navigatorKey: navigatorKey,

To use it:

import 'packages:dropdown_banner/dropdown_banner.dart';
class SomeClass {
  void doSomethingThenFail() {
      text: 'Failed to complete network request',
      textStyle: TextStyle(color: Colors.white),
Click here to see an example

How to debug when Kubernetes nodes are in 'Not Ready' state

First, describe nodes and see if it reports anything:

$ kubectl describe nodes

Look for conditions, capacity and allocatable:

  Type              Status
  ----              ------
  OutOfDisk         False
  MemoryPressure    False
  DiskPressure      False
  Ready             True
 cpu:       2
 memory:    2052588Ki
 pods:      110
 cpu:       2
 memory:    1950188Ki
 pods:      110

If everything is alright here, SSH into the node and observe kubelet logs to see if it reports anything. Like certificate erros, authentication errors etc.

If kubelet is running as a systemd service, you can use

$ journalctl -u kubelet

How to enter a series of numbers automatically in Excel

If you want to pick cell entries from a list then you have a couple of non-code based options

I would recommend The Data Validation approach where

  • creating a list of your 100 records in a single column,
  • provide a range name to this list,
  • then using Data Validation's List option

sample from Debra's site below, click on the first link above to access it.

Data Validation

How to use Fiddler to monitor WCF service

Just had this problem, what worked for me was to use localhost.fiddler:

 <endpoint address="http://localhost.fiddler/test/test.svc"

Get list of all tables in Oracle?

Execute the below commands:

Show all tables in the Oracle Database

sql> SELECT table_name FROM dba_tables;

Show tables owned by the current user

sql> SELECT table_name FROM user_tables;

Show tables that are accessible by the current user

sql> SELECT table_name FROM all_tables ORDER BY table_name; The following picture illustrates the tables that can be returned from the user_tables, all_tables, and dba_tables views:

TypeScript enum to object array

Enums are real objects that exist at runtime. So you are able to reverse the mapping doing something like this:

let value = GoalProgressMeasurements.Not_Measured;
// => Not_Measured

Based on that you can use the following code:

export enum GoalProgressMeasurements {
    Percentage = 1,
    Numeric_Target = 2,
    Completed_Tasks = 3,
    Average_Milestone_Progress = 4,
    Not_Measured = 5

let map: {id: number; name: string}[] = [];

for(var n in GoalProgressMeasurements) {
    if (typeof GoalProgressMeasurements[n] === 'number') {
        map.push({id: <any>GoalProgressMeasurements[n], name: n});



How to get the last characters in a String in Java, regardless of String size

org.apache.commons.lang3.StringUtils.substring(s, -7) 

gives you the answer. It returns the input if it is shorter than 7, and null if s == null. It never throws an exception.


Percentage Height HTML 5/CSS

I am trying to set a div to a certain percentage height in CSS

Percentage of what?

To set a percentage height, its parent element(*) must have an explicit height. This is fairly self-evident, in that if you leave height as auto, the block will take the height of its content... but if the content itself has a height expressed in terms of percentage of the parent you've made yourself a little Catch 22. The browser gives up and just uses the content height.

So the parent of the div must have an explicit height property. Whilst that height can also be a percentage if you want, that just moves the problem up to the next level.

If you want to make the div height a percentage of the viewport height, every ancestor of the div, including <html> and <body>, have to have height: 100%, so there is a chain of explicit percentage heights down to the div.

(*: or, if the div is positioned, the ‘containing block’, which is the nearest ancestor to also be positioned.)

Alternatively, all modern browsers and IE>=9 support new CSS units relative to viewport height (vh) and viewport width (vw):

div {

See here for more info.

How to test that a registered variable is not empty?

when: myvar | default('', true) | trim != ''

I use | trim != '' to check if a variable has an empty value or not. I also always add the | default(..., true) check to catch when myvar is undefined too.

Remove duplicate rows in MySQL

I found a simple way. (keep latest)

DELETE t1 FROM tablename t1 INNER JOIN tablename t2 
WHERE < AND t1.column1 = t2.column1 AND t1.column2 = t2.column2;

Run Jquery function on window events: load, resize, and scroll?

just call your function inside the events.


$(document).ready(function(){  // or  $(window).load(function(){


$(window).resize(function () {


$(window).scroll(function () {

or bind all event in one function

$(window).on("load scroll resize",function(e){

How to add dividers and spaces between items in RecyclerView?

Here's how I would do it in Kotlin, for simple space between Items with default size of 10dp:

class SimpleItemDecoration(context: Context, space: Int = 10) : RecyclerView.ItemDecoration() {

    private val spaceInDp = ConvertUtil.dpToPx(context, space)

    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {

        outRect.left = spaceInDp
        outRect.right = spaceInDp
        outRect.bottom = spaceInDp
        // Add top margin only for the first item to avoid double space between items
        if (parent.getChildAdapterPosition(view) == 0) {
   = spaceInDp

and here is the dpToPx method:

fun dpToPx(context: Context, dp: Int): Int {
        return (dp * context.resources.displayMetrics.density).toInt()

Detect if a browser in a mobile device (iOS/Android phone/tablet) is used

Many mobile devices have resolutions so high that it's hard to distinguish between them and much larger screens. There are two ways to deal with this problem:

Use the following HTML code to scale the pixels (grouping smaller pixels into groups the size of the unit pixel - 96dpi, so px units will have the same physical size on all screens). Note that this will affect the scale of pretty much everything in your website, but this is generally the way to go when making sites mobile-friendly.

<meta name="viewport" content="width=device-width, initial-scale=1">

Alternatively, measuring the screen width in @media queries using cm instead of px units can tell you if you're dealing with a physically small screen regardless of resolution.

Get all files that have been modified in git branch

I use grep so I only get the lines with diff --git which are the files path:

git diff branchA branchB | grep 'diff --git'
diff --git a/package-lock.json b/package-lock.json

Retrieve a Fragment from a ViewPager

I couldn't find a simple, clean way to do this. However, the ViewPager widget is just another ViewGroup , which hosts your fragments. The ViewPager has these fragments as immediate children. So you could just iterate over them (using .getChildCount() and .getChildAt() ), and see if the fragment instance that you're looking for is currently loaded into the ViewPager and get a reference to it. E.g. you could use some static unique ID field to tell the fragments apart.

Note that the ViewPager may not have loaded the fragment you're looking for since it's a virtualizing container like ListView.

Pause in Python

In Windows, you can use the msvcrt module.

msvcrt.kbhit() Return true if a keypress is waiting to be read.

msvcrt.getch() Read a keypress and return the resulting character. Nothing is echoed to the console. This call will block if a keypress is not already available, but will not wait for Enter to be pressed.

If you want it to also work on Unix-like systems you can try this solution using the termios and fcntl modules.

Replace given value in vector

If you want to replace lot of values in single go, you can use 'library(car)'.



x <- rep(1:5,3)

xr <- recode(x, '3=1; 4=2')

## [1] 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
## [1] 1 2 1 2 5 1 2 1 2 5 1 2 1 2 5

How to receive serial data using android bluetooth

try this code :


package Android.Arduino.Bluetooth;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.TextView;
import android.widget.EditText;  
import android.widget.Button;
import java.util.Set;
import java.util.UUID;

public class MainActivity extends Activity
TextView myLabel;
EditText myTextbox;
BluetoothAdapter mBluetoothAdapter;
BluetoothSocket mmSocket;
BluetoothDevice mmDevice;
OutputStream mmOutputStream;
InputStream mmInputStream;
Thread workerThread;
byte[] readBuffer;
int readBufferPosition;
int counter;
volatile boolean stopWorker;

public void onCreate(Bundle savedInstanceState)

    Button openButton = (Button)findViewById(;
    Button sendButton = (Button)findViewById(;
    Button closeButton = (Button)findViewById(;
    myLabel = (TextView)findViewById(;
    myTextbox = (EditText)findViewById(;

    //Open Button
    openButton.setOnClickListener(new View.OnClickListener()
        public void onClick(View v)
            catch (IOException ex) { }

    //Send Button
    sendButton.setOnClickListener(new View.OnClickListener()
        public void onClick(View v)
            catch (IOException ex) { }

    //Close button
    closeButton.setOnClickListener(new View.OnClickListener()
        public void onClick(View v)
            catch (IOException ex) { }

void findBT()
    mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    if(mBluetoothAdapter == null)
        myLabel.setText("No bluetooth adapter available");

        Intent enableBluetooth = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableBluetooth, 0);

    Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
    if(pairedDevices.size() > 0)
        for(BluetoothDevice device : pairedDevices)
                mmDevice = device;
    myLabel.setText("Bluetooth Device Found");

void openBT() throws IOException
    UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"); //Standard SerialPortService ID
    mmSocket = mmDevice.createRfcommSocketToServiceRecord(uuid);        
    mmOutputStream = mmSocket.getOutputStream();
    mmInputStream = mmSocket.getInputStream();


    myLabel.setText("Bluetooth Opened");

void beginListenForData()
    final Handler handler = new Handler(); 
    final byte delimiter = 10; //This is the ASCII code for a newline character

    stopWorker = false;
    readBufferPosition = 0;
    readBuffer = new byte[1024];
    workerThread = new Thread(new Runnable()
        public void run()
           while(!Thread.currentThread().isInterrupted() && !stopWorker)
                    int bytesAvailable = mmInputStream.available();                        
                    if(bytesAvailable > 0)
                        byte[] packetBytes = new byte[bytesAvailable];
                        for(int i=0;i<bytesAvailable;i++)
                            byte b = packetBytes[i];
                            if(b == delimiter)
     byte[] encodedBytes = new byte[readBufferPosition];
     System.arraycopy(readBuffer, 0, encodedBytes, 0, encodedBytes.length);
     final String data = new String(encodedBytes, "US-ASCII");
     readBufferPosition = 0;

                                    public void run()
                                readBuffer[readBufferPosition++] = b;
                catch (IOException ex) 
                    stopWorker = true;


void sendData() throws IOException
    String msg = myTextbox.getText().toString();
    msg += "\n";
    myLabel.setText("Data Sent");

void closeBT() throws IOException
    stopWorker = true;
    myLabel.setText("Bluetooth Closed");

AND Here the layout:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android=""
tools:ignore="TextFields,HardcodedText" >

    android:text="Type here:" />

    android:background="@android:drawable/editbox_background" />

    android:text="Open" />

    android:text="Send" />

    android:text="Close" />


Here for Manifest: add to Application

// permission must be enabled complete
<manifest ....>

    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
    <uses-permission android:name="android.permission.BLUETOOTH" />


Radio/checkbox alignment in HTML/CSS

I think I have finally solved the problem. One commonly recommended solution is to use vertical-align: middle:

<input type="radio" style="vertical-align: middle"> Label

The problem, however, is that this still produces visible misalignments even though it should theoretically work. The CSS2 specification says that:

vertical-align: middle: Align the vertical midpoint of the box with the baseline of the parent box plus half the x-height of the parent.

So it should be in the perfect centre (the x-height is the height of the character x). However, the problem seems to be caused by the fact browsers commonly add some random uneven margins to radio buttons and checkboxes. One can check, for instance in Firefox using Firebug, that the default checkbox margin in Firefox is 3px 3px 0px 5px. I'm not sure where it comes from, but the other browsers seem to have similar margins as well. So to get a perfect alignment, one needs to get rid of these margins:

<input type="radio" style="vertical-align: middle; margin: 0px;"> Label

It is still interesting to note that in the table based solution the margins are somehow eaten and everything aligns nicely.

java IO Exception: Stream Closed

Don't call write.close() in writeToFile().

Could not calculate build plan: Plugin org.apache.maven.plugins:maven-resources-plugin:2.6 or one of its dependencies could not be resolved

Step1: Delete all instances of java from you machine

Step2: Delete all the environment variables related to java/jdk/jre

Step3: Check in programm files and program files(X86) folder, there should not be java folder.

Step4: Install java again.

Step5: Go to cmd and type "java -version" Result: it will display the java version which is installed in your machine.

Step6: now delete all the files which are in C:/User/AdminOrUserNameofYourMachine/.m2 folder

Step6: go to cmd and run "mvn -v" Result: It will display the Apache maven version installed on your machine

Step7: Now Rebuild your project.

This worked for me.

How to get jQuery dropdown value onchange event

Add try this code .. Its working grt.......

 if (isset($_POST['nav'])) {_x000D_
   header("Location: $_POST[nav]");_x000D_
<form id="page-changer" action="" method="post">_x000D_
    <select name="nav">_x000D_
        <option value="">Go to page...</option>_x000D_
        <option value="">CSS-Tricks</option>_x000D_
        <option value="">Digging Into WordPress</option>_x000D_
        <option value="">Quotes on Design</option>_x000D_
    <input type="submit" value="Go" id="submit" />_x000D_
<script type="text/javascript" src="//"></script>_x000D_
$(function() {_x000D_
    $("#page-changer select").change(function() {_x000D_
        window.location = $("#page-changer select option:selected").val();_x000D_

Is it possible to style a select box?

this on uses the twitter-bootstrap styles to turn selectin dropdown menu

Cannot set content-type to 'application/json' in jQuery.ajax

I found the solution for this problem here. Don't forget to allow verb OPTIONS on IIS app service handler.

Works fine. Thank you André Pedroso. :-)

Recursively find all files newer than a given time

Given a unix timestamp (seconds since epoch) of 1494500000, do:

find . -type f -newermt "$(date '+%Y-%m-%d %H:%M:%S' -d @1494500000)"

To grep those files for "foo":

find . -type f -newermt "$(date '+%Y-%m-%d %H:%M:%S' -d @1494500000)" -exec grep -H 'foo' '{}' \;

AngularJS For Loop with Numbers & Ranges

This is jzm's improved answer (i cannot comment else i would comment her/his answer because s/he included errors). The function has a start/end range value, so it's more flexible, and... it works. This particular case is for day of month:

$scope.rangeCreator = function (minVal, maxVal) {
    var arr = [];
   for (var i = minVal; i <= maxVal; i++) {
   return arr;

<div class="col-sm-1">
    <select ng-model="monthDays">
        <option ng-repeat="day in rangeCreator(1,31)">{{day}}</option>

Python try-else

    statements # statements that can raise exceptions
    statements # statements that will be executed to handle exceptions
    statements # statements that will be executed if there is no exception

Example :

    age=int(input('Enter your age: '))
    print ('You have entered an invalid value.')
    if age <= 21:
        print('You are not allowed to enter, you are too young.')
        print('Welcome, you are old enough.')

The Output :

Enter your age: a
You have entered an invalid value.
Enter your age: 25
Welcome, you are old enough.
Enter your age: 13
You are not allowed to enter, you are too young.

Copied from :

How to fix: "No suitable driver found for jdbc:mysql://localhost/dbname" error when using pools?

Most of time it happen because two mysql-connector-java-3.0.14-production-bin.jar file. One in lib folder of tomcat and another in classpath of the project.

Just try to remove mysql-connector-java-3.0.14-production-bin.jar from lib folder.

This way it is working for me.

Room persistance library. Delete all

This is how we do it.

fun Fragment.emptyDatabase() {
    viewLifecycleOwner.lifecycleScope.launchWhenCreated {
        withContext(Dispatchers.IO) {

file_put_contents - failed to open stream: Permission denied

For anyone using Ubuntu and receiving this error when loading the page locally, but not on a web hosting service,

I just fixed this by opening up nautilus (sudo nautilus) and right click on the file you're trying to open, click properties > Settings > and give read write to 'everyone else'

Delete all objects in a list

To delete all objects in a list, you can directly write list = []

Here is example:

>>> a = [1, 2, 3]
>>> a
[1, 2, 3]
>>> a = []
>>> a

Cast IList to List

The other answers all recommend to use AddRange with an IList.

A more elegant solution that avoids the casting is to implement an extension to IList to do the job.


Public Sub AddRange(Of T)(ByRef Exttype As IList(Of T), ElementsToAdd As IEnumerable(Of T))
   For Each ele In ElementsToAdd
End Sub

And in C#:

public void AddRange<T>(this ref IList<T> Exttype, IEnumerable<T> ElementsToAdd)
    foreach (var ele in ElementsToAdd)

$date + 1 year?

I prefer the OO approach:

$date = new \DateTimeImmutable('today'); //'today' gives midnight, leave blank for current time.
$futureDate = $date->add(\DateInterval::createFromDateString('+1 Year'))

Use DateTimeImmutable otherwise you will modify the original date too! more on DateTimeImmutable:

If you just want from todays date then you can always do:

new \DateTimeImmutable('-1 Month');

How to select data of a table from another database in SQL Server?

In SQL Server 2012 and above, you don't need to create a link. You can execute directly


I don't know whether previous versions of SQL Server work as well

How to check for empty value in Javascript?

Comment as an answer:

if (timetime[0].value)

This works because any variable in JS can be evaluated as a boolean, so this will generally catch things that are empty, null, or undefined.

Convert a timedelta to days, hours and minutes

Here is a little function I put together to do this right down to microseconds:

def tdToDict(td:datetime.timedelta) -> dict:
    def __t(t, n):
        if t < n: return (t, 0)
        v = t//n
        return (t -  (v * n), v)
    (s, h) = __t(td.seconds, 3600)
    (s, m) = __t(s, 60)    
    (micS, milS) = __t(td.microseconds, 1000)

    return {
         'days': td.days
        ,'hours': h
        ,'minutes': m
        ,'seconds': s
        ,'milliseconds': milS
        ,'microseconds': micS

Here is a version that returns a tuple:

# usage: (_d, _h, _m, _s, _mils, _mics) = tdTuple(td)
def tdTuple(td:datetime.timedelta) -> tuple:
    def _t(t, n):
        if t < n: return (t, 0)
        v = t//n
        return (t -  (v * n), v)
    (s, h) = _t(td.seconds, 3600)
    (s, m) = _t(s, 60)    
    (mics, mils) = _t(td.microseconds, 1000)
    return (td.days, h, m, s, mics, mils)

Deleting an SVN branch

Assuming this branch isn't an external or a symlink, removing the branch should be as simple as:

svn rm branches/< mybranch >

svn ci -m "message"

If you'd like to do this in the repository then update to remove it from your working copy you can do something like:

svn rm http://< myurl >/< myrepo >/branches/< mybranch >

Then run:

svn update

Check Whether a User Exists

By far the simplest solution:

if id -u "$user" >/dev/null 2>&1; then
    echo 'user exists'
    echo 'user missing'

The >/dev/null 2>&1 can be shortened to &>/dev/null in Bash.