Programs & Examples On #Opacitymask

How To change the column order of An Existing Table in SQL Server 2008

Relying on column order is generally a bad idea in SQL. SQL is based on Relational theory where order is never guaranteed - by design. You should treat all your columns and rows as having no order and then change your queries to provide the correct results:

For Columns:

  • Try not to use SELECT *, but instead specify the order of columns in the select list as in: SELECT Member_ID, MemberName, MemberAddress from TableName. This will guarantee order and will ease maintenance if columns get added.

For Rows:

  • Row order in your result set is only guaranteed if you specify the ORDER BY clause.
  • If no ORDER BY clause is specified the result set may differ as the Query Plan might differ or the database pages might have changed.

Hope this helps...

Group by with union mysql select query

This may be what your after:

SELECT Count(Owner_ID), Name
    SELECT M.Owner_ID, O.Name, T.Type
    FROM Transport As T, Owner As O, Motorbike As M
    WHERE T.Type = 'Motorbike'
    AND O.Owner_ID = M.Owner_ID
    AND T.Type_ID = M.Motorbike_ID


    SELECT C.Owner_ID, O.Name, T.Type
    FROM Transport As T, Owner As O, Car As C
    WHERE T.Type = 'Car'
    AND O.Owner_ID = C.Owner_ID
    AND T.Type_ID = C.Car_ID

ANTLR: Is there a simple example?

version 4.7.1 was slightly different : for import:

import org.antlr.v4.runtime.*;

for the main segment - note the CharStreams:

CharStream in = CharStreams.fromString("12*(5-6)");
ExpLexer lexer = new ExpLexer(in);
CommonTokenStream tokens = new CommonTokenStream(lexer);
ExpParser parser = new ExpParser(tokens);

How do I check if a string contains a specific word?

A string can be checked with the below function:

function either_String_existor_not($str, $character) {
    if (strpos($str, $character) !== false) {
        return true;
    return false;

How can I tell if a DOM element is visible in the current viewport?

This checks if an element is at least partially in view (vertical dimension):

function inView(element) {
    var box = element.getBoundingClientRect();
    return inViewBox(box);

function inViewBox(box) {
    return ((box.bottom < 0) || ( > getWindowSize().h)) ? false : true;

function getWindowSize() {
    return { w: document.body.offsetWidth || document.documentElement.offsetWidth || window.innerWidth, h: document.body.offsetHeight || document.documentElement.offsetHeight || window.innerHeight}

Compare integer in bash, unary operator expected

Your piece of script works just great. Are you sure you are not assigning anything else before the if to "i"?

A common mistake is also not to leave a space after and before the square brackets.

Does calling clone() on an array also clone its contents?

clone() creates a shallow copy. Which means the elements will not be cloned. (What if they didn't implement Cloneable?)

You may want to use Arrays.copyOf(..) for copying arrays instead of clone() (though cloning is fine for arrays, unlike for anything else)

If you want deep cloning, check this answer

A little example to illustrate the shallowness of clone() even if the elements are Cloneable:

ArrayList[] array = new ArrayList[] {new ArrayList(), new ArrayList()};
ArrayList[] clone = array.clone();
for (int i = 0; i < clone.length; i ++) {



casting Object array to Integer array error

You can't cast an Object array to an Integer array. You have to loop through all elements of a and cast each one individually.

Object[] a = new Object[1];
Integer b=1;
Integer[] c = new Integer[a.length];
for(int i = 0; i < a.length; i++)
    c[i] = (Integer) a[i];

Edit: I believe the rationale behind this restriction is that when casting, the JVM wants to ensure type-safety at runtime. Since an array of Objects can be anything besides Integers, the JVM would have to do what the above code is doing anyway (look at each element individually). The language designers decided they didn't want the JVM to do that (I'm not sure why, but I'm sure it's a good reason).

However, you can cast a subtype array to a supertype array (e.g. Integer[] to Object[])!

What is the Python equivalent of static variables inside a function?

A little bit more readable, but more verbose (Zen of Python: explicit is better than implicit):

>>> def func(_static={'counter': 0}):
...     _static['counter'] += 1
...     print _static['counter']
>>> func()
>>> func()

See here for an explanation of how this works.

Insert a row to pandas dataframe

I put together a short function that allows for a little more flexibility when inserting a row:

def insert_row(idx, df, df_insert):
    dfA = df.iloc[:idx, ]
    dfB = df.iloc[idx:, ]

    df = dfA.append(df_insert).append(dfB).reset_index(drop = True)

    return df

which could be further shortened to:

def insert_row(idx, df, df_insert):
    return df.iloc[:idx, ].append(df_insert).append(df.iloc[idx:, ]).reset_index(drop = True)

Then you could use something like:

df = insert_row(2, df, df_new)

where 2 is the index position in df where you want to insert df_new.

Calculating Distance between two Latitude and Longitude GeoCoordinates

And here, for those still not satisfied (like me), the original code from .NET-Frameworks GeoCoordinate class, refactored into a standalone method:

public double GetDistance(double longitude, double latitude, double otherLongitude, double otherLatitude)
    var d1 = latitude * (Math.PI / 180.0);
    var num1 = longitude * (Math.PI / 180.0);
    var d2 = otherLatitude * (Math.PI / 180.0);
    var num2 = otherLongitude * (Math.PI / 180.0) - num1;
    var d3 = Math.Pow(Math.Sin((d2 - d1) / 2.0), 2.0) + Math.Cos(d1) * Math.Cos(d2) * Math.Pow(Math.Sin(num2 / 2.0), 2.0);
    return 6376500.0 * (2.0 * Math.Atan2(Math.Sqrt(d3), Math.Sqrt(1.0 - d3)));

Brew doctor says: "Warning: /usr/local/include isn't writable."

What worked for me was too

sudo chmod g+w /usr/local
sudo chgrp staff /usr/local

How can I get the current date and time in the terminal and set a custom command in the terminal for it?

The command is date

To customise the output there are a myriad of options available, see date --help for a list.

For example, date '+%A %W %Y %X' gives Tuesday 34 2013 08:04:22 which is the name of the day of the week, the week number, the year and the time.

Add Legend to Seaborn point plot

Old question, but there's an easier way.

plt.legend(labels=['legendEntry1', 'legendEntry2', 'legendEntry3'])

This lets you add the plots sequentially, and not have to worry about any of the matplotlib crap besides defining the legend items.

Perfect 100% width of parent container for a Bootstrap input?

In order to get the desired result, you must set "box-sizing: border-box" vs. the default which is "box-sizing: content-box". This is precisely the issue you are referring to (From MDN):


This is the initial and default value as specified by the CSS standard. The width and height properties are measured including only the content, but not the padding, border or margin.


The width and height properties include the content, the padding and border, but not the margin."


Compatibility for this CSS is good.

How do I access refs of a child component in the parent component

  1. Inside the child component add a ref to the node you need
  2. Inside the parent component add a ref to the child component.
* Child component
class Child extends React.Component {
  render() {
    return (
      <div id="child">
        <h1 ref={(node) => { this.heading = node; }}>

 * Parent component
class Parent extends React.Component {
  componentDidMount() {
    // Access child component refs via parent component instance like this

  render() {
    return (
          ref={(node) => { this.child = node; }}


New xampp security concept: Access Forbidden Error 403 - Windows 7 - phpMyAdmin

This could be because of wrong configuration, esp if your other sites are working fine.

<VirtualHost cmsdemo.git:88>
    DocumentRoot "C:/Projects/rwp/"
    ServerName cmsdemo.git
    <Directory C:/Projects/cmsdemo/>
        Require all granted 
        AllowOverride All

Notice in DocumentRoot I am specifying one folder and in Directory, I am specifying another hence 403 Error. This fixed my problem.

Find records with a date field in the last 24 hours

There are so many ways to do this. The listed ones work great, but here's another way if you have a datetime field:

SELECT [fields] 
FROM [table] 
WHERE timediff(now(), my_datetime_field) < '24:00:00'

timediff() returns a time object, so don't make the mistake of comparing it to 86400 (number of seconds in a day), or your output will be all kinds of wrong.

How To Show And Hide Input Fields Based On Radio Button Selection

Use display:none/block, instead of visibility, and add a margin-top/bottom for the space you want to see ONLY when the inputs are shown

 function yesnoCheck() {
        if (document.getElementById('yesCheck').checked) {
           document.getElementById('ifYes').style.display = 'block';
        } else {
           document.getElementById('ifYes').style.display = 'none';

and your HTML line for the ifYes tag

<div id="ifYes" style="display:none;margin-top:3%;">If yes, explain:

How to change context root of a dynamic web project in Eclipse?

If using eclipse to deploy your application . We can use this maven plugin


now go to your project root folder and open cmd prompt at that location type this command :

mvn eclipse:eclipse -Dwtpversion=2.0

You may need to restart eclipse , or in server view delete server and create agian to see affect. I wonder this exercise make sense in real life but works.

Why do I get an UnsupportedOperationException when trying to remove an element from a List?

Quite a few problems with your code:

On Arrays.asList returning a fixed-size list

From the API:

Arrays.asList: Returns a fixed-size list backed by the specified array.

You can't add to it; you can't remove from it. You can't structurally modify the List.


Create a LinkedList, which supports faster remove.

List<String> list = new LinkedList<String>(Arrays.asList(split));

On split taking regex

From the API:

String.split(String regex): Splits this string around matches of the given regular expression.

| is a regex metacharacter; if you want to split on a literal |, you must escape it to \|, which as a Java string literal is "\\|".



On better algorithm

Instead of calling remove one at a time with random indices, it's better to generate enough random numbers in the range, and then traversing the List once with a listIterator(), calling remove() at appropriate indices. There are questions on stackoverflow on how to generate random but distinct numbers in a given range.

With this, your algorithm would be O(N).

How do I get the value of a registry key and ONLY the value using powershell

Well you need to be specific here. As far as I know, the key in a registry is a "folder" of properties. So did you mean get the value of a property? If so, try something like this:

(Get-ItemProperty HKLM:\Software\Microsoft\PowerShell\1\PowerShellEngine -Name PowerShellVersion).PowerShellVersion

First we get an object containing the property we need with Get-ItemProperty and then we get the value of for the property we need from that object. That will return the value of the property as a string. The example above gives you the PS version for "legacy"/compatibility-mdoe powershell (1.0 or 2.0).

Change the Blank Cells to "NA"

Couldn't you just use

dat <- read.csv("data2.csv",na.strings=" ",header=TRUE)

should convert all blanks to NA as the data are read in be sure to put a space between your quotation

jQuery: How to get to a particular child of a parent?

Calling .parents(".box .something1") will return all parent elements that match the selector .box .something. In other words, it will return parent elements that are .something1 and are inside of .box.

You need to get the children of the closest parent, like this:


This code calls .closest to get the innermost parent matching a selector, then calls .children on that parent element to find the uncle you're looking for.

Java method to swap primitives

You can't create a method swap, so that after calling swap(x,y) the values of x and y will be swapped. You could create such a method for mutable classes by swapping their contents¹, but this would not change their object identity and you could not define a general method for this.

You can however write a method that swaps two items in an array or list if that's what you want.

¹ For example you could create a swap method that takes two lists and after executing the method, list x will have the previous contents of list y and list y will have the previous contents of list x.

append to url and refresh page

One small bug fix for @yeyo's thoughtful answer above.


var parameters =\?|&/);


var parameters =\?|&amp;/);

Command-line svn for Windows?

If you have Windows 10 you can use Bash on Ubuntu on Windows to install subversion.

Why does foo = filter(...) return a <filter object>, not a list?

filter expects to get a function and something that it can iterate over. The function should return True or False for each element in the iterable. In your particular example, what you're looking to do is something like the following:

In [47]: def greetings(x):
   ....:     return x == "hello"

In [48]: filter(greetings, ["hello", "goodbye"])
Out[48]: ['hello']

Note that in Python 3, it may be necessary to use list(filter(greetings, ["hello", "goodbye"])) to get this same result.

Error inflating class

I faced with same problem. Solution that worked for me. If you use v7.Toolbar you must use theme extended from Theme.AppCompat.* You can't use theme extended from android:Theme.Material.* because they have different style attributes.

Hope it will helpful.

I just discovered why all ASP.Net websites are slow, and I am trying to work out what to do about it

OK, so big Props to Joel Muller for all his input. My ultimate solution was to use the Custom SessionStateModule detailed at the end of this MSDN article:

This was:

  • Very quick to implement (actually seemed easier than going the provider route)
  • Used a lot of the standard ASP.Net session handling out of the box (via the SessionStateUtility class)

This has made a HUGE difference to the feeling of "snapiness" to our application. I still can't believe the custom implementation of ASP.Net Session locks the session for the whole request. This adds such a huge amount of sluggishness to websites. Judging from the amount of online research I had to do (and conversations with several really experienced ASP.Net developers), a lot of people have experienced this issue, but very few people have ever got to the bottom of the cause. Maybe I will write a letter to Scott Gu...

I hope this helps a few people out there!

How to deserialize JS date using Jackson?

This works for me - i am using jackson 2.0.4

ObjectMapper objectMapper = new ObjectMapper();
final DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");

Netbeans - class does not have a main method

This happens when you move your main class location manually because Netbeans doesn't refresh one of its property files. Open nbproject/ and change the value of main.class to the correct package location.

How to set JAVA_HOME path on Ubuntu?

I normally set paths in


However for Java, I followed instructions at

and it was sufficient for me.

you can also define multiple java_home's and have only one of them active (rest commented).

suppose in your bashrc file, you have

export JAVA_HOME=......jdk1.7

#export JAVA_HOME=......jdk1.8

notice 1.8 is commented. Once you do

source ~/.bashrc

jdk1.7 will be in path.

you can switch them fairly easily this way. There are other more permanent solutions too. The link I posted has that info.

String date to xmlgregoriancalendar conversion


  • Use modern java.time classes as much as possible, rather than the terrible legacy classes.
  • Always specify your desired/expected time zone or offset-from-UTC rather than rely implicitly on JVM’s current default.

Example code (without exception-handling):

XMLGregorianCalendar xgc = 
    DatatypeFactory                           // Data-type converter.
    .newInstance()                            // Instantiate a converter object.
    .newXMLGregorianCalendar(                 // Converter going from `GregorianCalendar` to `XMLGregorianCalendar`.
        GregorianCalendar.from(               // Convert from modern `ZonedDateTime` class to legacy `GregorianCalendar` class.
            LocalDate                         // Modern class for representing a date-only, without time-of-day and without time zone.
            .parse( "2014-01-07" )            // Parsing strings in standard ISO 8601 format is handled by default, with no need for custom formatting pattern. 
            .atStartOfDay( ZoneOffset.UTC )   // Determine the first moment of the day as seen in UTC. Returns a `ZonedDateTime` object.
        )                                     // Returns a `GregorianCalendar` object.
    )                                         // Returns a `XMLGregorianCalendar` object.

Parsing date-only input string into an object of XMLGregorianCalendar class

Avoid the terrible legacy date-time classes whenever possible, such as XMLGregorianCalendar, GregorianCalendar, Calendar, and Date. Use only modern java.time classes.

When presented with a string such as "2014-01-07", parse as a LocalDate.

LocalDate.parse( "2014-01-07" )

To get a date with time-of-day, assuming you want the first moment of the day, specify a time zone. Let java.time determine the first moment of the day, as it is not always 00:00:00.0 in some zones on some dates.

LocalDate.parse( "2014-01-07" )
         .atStartOfDay( ZoneId.of( "America/Montreal" ) )

This returns a ZonedDateTime object.

ZonedDateTime zdt = 
        .parse( "2014-01-07" )
        .atStartOfDay( ZoneId.of( "America/Montreal" ) )

zdt.toString() = 2014-01-07T00:00-05:00[America/Montreal]

But apparently, you want the start-of-day as seen in UTC (an offset of zero hours-minutes-seconds). So we specify ZoneOffset.UTC constant as our ZoneId argument.

ZonedDateTime zdt = 
        .parse( "2014-01-07" )
        .atStartOfDay( ZoneOffset.UTC )

zdt.toString() = 2014-01-07T00:00Z

The Z on the end means UTC (an offset of zero), and is pronounced “Zulu”.

If you must work with legacy classes, convert to GregorianCalendar, a subclass of Calendar.

GregorianCalendar gc = GregorianCalendar.from( zdt ) ;

gc.toString() = java.util.GregorianCalendar[time=1389052800000,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="UTC",offset=0,dstSavings=0,useDaylight=false,transitions=0,lastRule=null],firstDayOfWeek=2,minimalDaysInFirstWeek=4,ERA=1,YEAR=2014,MONTH=0,WEEK_OF_YEAR=2,WEEK_OF_MONTH=2,DAY_OF_MONTH=7,DAY_OF_YEAR=7,DAY_OF_WEEK=3,DAY_OF_WEEK_IN_MONTH=1,AM_PM=0,HOUR=0,HOUR_OF_DAY=0,MINUTE=0,SECOND=0,MILLISECOND=0,ZONE_OFFSET=0,DST_OFFSET=0]

Apparently, you really need an object of the legacy class XMLGregorianCalendar. If the calling code cannot be updated to use java.time, convert.

XMLGregorianCalendar xgc = 
        .newXMLGregorianCalendar( gc ) 

Actually, that code requires a try-catch.

    XMLGregorianCalendar xgc =
                    .newXMLGregorianCalendar( gc );
catch ( DatatypeConfigurationException e )

xgc = 2014-01-07T00:00:00.000Z

Putting that all together, with appropriate exception-handling.

// Given an input string such as "2014-01-07", return a `XMLGregorianCalendar` object
// representing first moment of the day on that date as seen in UTC. 
static public XMLGregorianCalendar getXMLGregorianCalendar ( String input )
    Objects.requireNonNull( input );
    if( input.isBlank() ) { throw new IllegalArgumentException( "Received empty/blank input string for date argument. Message # 11818896-7412-49ba-8f8f-9b3053690c5d." ) ; }
    XMLGregorianCalendar xgc = null;
    ZonedDateTime zdt = null;

        zdt =
                        .parse( input )
                        .atStartOfDay( ZoneOffset.UTC );
    catch ( DateTimeParseException e )
        throw new IllegalArgumentException( "Faulty input string for date does not comply with standard ISO 8601 format. Message # 568db0ef-d6bf-41c9-8228-cc3516558e68." );

    GregorianCalendar gc = GregorianCalendar.from( zdt );
        xgc =
                        .newXMLGregorianCalendar( gc );
    catch ( DatatypeConfigurationException e )

    Objects.requireNonNull( xgc );
    return xgc ;


String input = "2014-01-07";
XMLGregorianCalendar xgc = App.getXMLGregorianCalendar( input );

Dump to console.

System.out.println( "xgc = " + xgc );

xgc = 2014-01-07T00:00:00.000Z

Modern date-time classes versus legacy

Table of date-time types in Java, both modern and legacy

Date-time != String

Do not conflate a date-time value with its textual representation. We parse strings to get a date-time object, and we ask the date-time object to generate a string to represent its value. The date-time object has no ‘format’, only strings have a format.

So shift your thinking into two separate modes: model and presentation. Determine the date-value you have in mind, applying appropriate time zone, as the model. When you need to display that value, generate a string in a particular format as expected by the user.

Avoid legacy date-time classes

The Question and other Answers all use old troublesome date-time classes now supplanted by the java.time classes.

ISO 8601

Your input string "2014-01-07" is in standard ISO 8601 format.

The T in the middle separates date portion from time portion.

The Z on the end is short for Zulu and means UTC.

Fortunately, the java.time classes use the ISO 8601 formats by default when parsing/generating strings. So no need to specify a formatting pattern.


The LocalDate class represents a date-only value without time-of-day and without time zone.

LocalDate ld = LocalDate.parse( "2014-01-07" ) ;

ld.toString(): 2014-01-07

Start of day ZonedDateTime

If you want to see the first moment of that day, specify a ZoneId time zone to get a moment on the timeline, a ZonedDateTime. The time zone is crucial because the date varies around the globe by zone. A few minutes after midnight in Paris France is a new day while still “yesterday” in Montréal Québec.

Never assume the day begins at 00:00:00. Anomalies such as Daylight Saving Time (DST) means the day may begin at another time-of-day such as 01:00:00. Let java.time determine the first moment.

ZoneId z = ZoneId.of( "America/Montreal" ) ;
ZonedDateTime zdt = ld.atStartOfDay( z ) ;

zdt.toString(): 2014-01-07T00:00:00Z

For your desired format, generate a string using the predefined formatter DateTimeFormatter.ISO_LOCAL_DATE_TIME and then replace the T in the middle with a SPACE.

String output = zdt.format( DateTimeFormatter.ISO_LOCAL_DATE_TIME )
                   .replace( "T" , " " ) ; 

2014-01-07 00:00:00

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

Where to obtain the java.time classes?

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

What are the correct version numbers for C#?

I've summarised most of the versions in this table. The only ones missing should be ASP.NET Core versions. I've also added different versions of ASP.NET MVC.

Note that ASP.NET 5 has been rebranded as ASP.NET Core 1.0 and ASP.NET MVC 6 has been rebranded as ASP.NET Core MVC 1.0.0. I believe this change occurred sometime around Jan 2016.

I have included the release date of ASP.NET 5 RC1 in the table, but I've yet to include ASP.NET core 1.0 and other core versions, because I couldn't find the exact release dates. You can read more about the release dates regarding ASP.NET Core here: When is ASP.NET Core 1.0 (ASP.NET 5 / vNext) scheduled for release?


How to import multiple csv files in a single load?

Using Spark 2.0+, we can load multiple CSV files from different directories using df =['directory_1','directory_2','directory_3'.....], header=True). For more information, refer the documentation here

Making Maven run all tests, even when some fail

A quick answer:

mvn -fn test

Works with nested project builds.

How to show soft-keyboard when edittext is focused

After trying every individual answer here the keyboard doesn't show up.. I got hours to get this solved, so hope someone doesn't waste it in the future..

For my case, the issue was not a programming issue at at, I was testing on an emulator with a phone that has a hardware keyboard, so it doesn't show up the software keyboard by default, to solve this, you need to make sure that the show soft input enabled in your emulator by turning off the hardware keyboard or enable the soft keyboard.

In faced this only on API-15 & 16. Here are screen shots how to do that

On Geny Motion emulator:

enter image description here enter image description here

On Android Studio emulator:

enter image description here

Add line break to 'git commit -m' from the command line

You should be able to use

git commit -m $'first line\nsecond line'

From the Bash manual:

Words of the form $'string' are treated specially. The word expands to string, with backslash-escaped characters replaced as specified by the ANSI C standard.

This includes support for newlines as shown above, plus hex and Unicode codes and others. Go to the linked section to see a list of the backslash-escaped characters.

Display all post meta keys and meta values of the same post ID in wordpress

I use it in form of a meta box. Here is a function that dumps values of all the meta data for post.

    function dump_all_meta(){

        echo "<h3>All Post Meta</h3>";

        // Get all the data.

        foreach( $getPostCustom as $name=>$value ) {

            echo "<strong>".$name."</strong>"."  =>  ";

            foreach($getPostCustom as $name=>$value) {

        echo "<strong>".$name."</strong>"."  =>  ";

        foreach($value as $nameAr=>$valueAr) {
                echo "<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;";
                echo $nameAr."  =>  ";
                echo var_dump($valueAr);

        echo "<br /><br />";

    } // Callback funtion ended.

Hope it helps. You can use it inside a meta box or at the front-end.

How can I align two divs horizontally?

Nowadays, we could use some flexbox to align those divs.

.container {_x000D_
    display: flex;_x000D_
<div class="container">_x000D_
        <span>source list</span>_x000D_
        <select size="10">_x000D_
            <option />_x000D_
            <option />_x000D_
            <option />_x000D_
        <span>destination list</span>_x000D_
        <select size="10">_x000D_
            <option />_x000D_
            <option />_x000D_
            <option />_x000D_

How to Convert a Text File into a List in Python

Going with what you've started:

row = [[]] 
crimefile = open(fileName, 'r') 
for line in crimefile.readlines(): 
    tmp = []
    for element in line[0:-1].split(','):

Converting Columns into rows with their respective data in sql server

declare @T table (ScripName varchar(50), ScripCode varchar(50), Price int)
insert into @T values ('20 MICRONS', '533022', 39)

  'ScripName' as ColName,
  ScripName as ColValue
from @T
union all
  'ScripCode' as ColName,
  ScripCode as ColValue
from @T
union all
  'Price' as ColName,
  cast(Price as varchar(50)) as ColValue
from @T

jQuery: Slide left and slide right

You can always just use jQuery to add a class, .addClass or .toggleClass. Then you can keep all your styles in your CSS and out of your scripts.

How to get history on react-router v4?

Basing on this answer if you need history object only in order to navigate to other component:

import { useHistory } from "react-router-dom";

function HomeButton() {
  const history = useHistory();

  function handleClick() {

  return (
    <button type="button" onClick={handleClick}>
      Go home

GitHub "fatal: remote origin already exists"

You can see what remote repositories you are configured to connect to via

git remote -v

That will return a list in this format:

origin  [email protected]:github/git-reference.git (fetch)
origin  [email protected]:github/git-reference.git (push)

That might help you figure out what the original 'origin' pointed to.

If you want to keep the remote connection that you see with the -v, but still want to follow the Rails tutorial without having to remember 'github' (or some other name) for your tutorial's repo, you can rename your other repository with the command:

git remote rename [current name] [new name]

as in:

git remote rename origin oldrepo

You should then be able to resume your tutorial.

Autoincrement VersionCode with gradle extra properties

The First Commented code will increment the number while each "Rebuild Project" and save the the value in the "Version Property" file.

The Second Commented code will generate new version name of APK file while "Build APKs".

android {
    compileSdkVersion 28
    buildToolsVersion "29.0.0"
    def Properties versionProps = new Properties()
    def versionPropsFile = file('')
        versionProps.load(new FileInputStream(versionPropsFile))
    def code = (versionProps['VERSION_CODE'] ?: "0").toInteger() + 1
    versionProps['VERSION_CODE'] = code.toString(), null)
    defaultConfig {
        applicationId "com.example.myapp"
        minSdkVersion 15
        targetSdkVersion 28
        versionCode 1
        versionName "0.19"
        testInstrumentationRunner ""
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), ''
            android.applicationVariants.all { variant ->
                variant.outputs.all {
                    def appName = "MyAppSampleName"
                    outputFileName = appName+"_v${variant.versionName}.${versionProps['VERSION_CODE']}.apk"

How do I access the $scope variable in browser's console using AngularJS?

This is a way of getting at scope without Batarang, you can do:

var scope = angular.element('#selectorId').scope();

Or if you want to find your scope by controller name, do this:

var scope = angular.element('[ng-controller=myController]').scope();

After you make changes to your model, you'll need to apply the changes to the DOM by calling:



You can also have a look at this related question. That user reported that using a join provided better performance than using a sub query.

"Fade" borders in CSS

You can specify gradients for colours in certain circumstances in CSS3, and of course borders can be set to a colour, so you should be able to use a gradient as a border colour. This would include the option of specifying a transparent colour, which means you should be able to achieve the effect you're after.

However, I've never seen it used, and I don't know how well supported it is by current browsers. You'll certainly need to accept that at least some of your users won't be able to see it.

A quick google turned up these two pages which should help you on your way:

Hope that helps.

Twitter Bootstrap add active class to li

I had the same problem, and this is what I added in my app launch script, and it worked smoothly. Here is the javascript

  var navs = $('nav > ul.nav');

  // Add class .active to current link

    var cUrl = String(window.location).split('?')[0];
    if (cUrl.substr(cUrl.length - 1) === '#') {
      cUrl = cUrl.slice(0,-1);

    if ($($(this))[0].href===cUrl) {


And the corresponding HTML is shown below. I'm using CoreUI, a phenomenal open source admin template and has support for many front end frameworks like Angular, plain bootstrap, Angular 4 etc.

<div class="sidebar">
<nav class="sidebar-nav open" >
    <ul class="nav" id="navTab" role="tablist">
        <li class="nav-item">
            <a class="nav-link"    href="/summary"><i class="icon-speedometer"></i> Dashboard </a>
        <li class="nav-item">
            <a class="nav-link"    href="/balanceSheet"><i class="icon-chart"></i> Balance Sheet </a>
        <li class="divider"></li>
        <li class="nav-title border-bottom">
            <p class="h5 mb-0">
                <i class="icon-graph"></i> Assets

what is the use of Eval() in

While binding a databound control, you can evaluate a field of the row in your data source with eval() function.

For example you can add a column to your gridview like that :

<asp:BoundField DataField="YourFieldName" />

And alternatively, this is the way with eval :

        <asp:Label ID="lbl" runat="server" Text='<%# Eval("YourFieldName") %>'>

It seems a little bit complex, but it's flexible, because you can set any property of the control with the eval() function :

        <asp:HyperLink ID="HyperLink1" runat="server" 
          NavigateUrl='<%# "ShowDetails.aspx?id="+Eval("Id") %>' 
          Text='<%# Eval("Text", "{0}") %>'></asp:HyperLink>

How to get data from observable in angular2

Angular is based on observable instead of promise base as of angularjs 1.x, so when we try to get data using http it returns observable instead of promise, like you did

 return this.http
      .map(res => res.json());

then to get data and show on view we have to convert it into desired form using RxJs functions like .map() function and .subscribe()

.map() is used to convert the observable (received from http request)to any form like .json(), .text() as stated in Angular's official website,

.subscribe() is used to subscribe those observable response and ton put into some variable so from which we display it into the view

this.myService.getConfig().subscribe(res => {
   console.log(res); = res;

Warning: Cannot modify header information - headers already sent by ERROR

This typically occurs when there is unintended output from the script before you start the session. With your current code, you could try to use output buffering to solve it.

try adding a call to the ob_start(); function at the very top of your script and ob_end_flush(); at the very end of the document.

What is the best way to check for Internet connectivity using .NET?

Instead of checking, just perform the action (web request, mail, ftp, etc.) and be prepared for the request to fail, which you have to do anyway, even if your check was successful.

Consider the following:

1 - check, and it is OK
2 - start to perform action 
3 - network goes down
4 - action fails
5 - lot of good your check did

If the network is down your action will fail just as rapidly as a ping, etc.

1 - start to perform action
2 - if the net is down(or goes down) the action will fail

Could not open input file: composer.phar

Another solution could be.. find the location of composer.phar file in your computer. If composer is installed successfully then it can be found in the installed directory.

Copy that location & instead of composer.phar in the command line, put the entire path there.

It also worked for me!

FragmentActivity to Fragment

first of all;

a Fragment must be inside a FragmentActivity, that's the first rule,

a FragmentActivity is quite similar to a standart Activity that you already know, besides having some Fragment oriented methods

second thing about Fragments, is that there is one important method you MUST call, wich is onCreateView, where you inflate your layout, think of it as the setContentLayout

here is an example:

    @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {     mView       = inflater.inflate(R.layout.fragment_layout, container, false);       return mView; } 

and continu your work based on that mView, so to find a View by id, call mView.findViewById(..);

for the FragmentActivity part:

the xml part "must" have a FrameLayout in order to inflate a fragment in it

        <FrameLayout             android:id="@+id/content_frame"             android:layout_width="match_parent"             android:layout_height="match_parent"  >         </FrameLayout> 

as for the inflation part

getSupportFragmentManager().beginTransaction().replace(, new YOUR_FRAGMENT, "TAG").commit();

begin with these, as there is tons of other stuf you must know about fragments and fragment activities, start of by reading something about it (like life cycle) at the android developer site

How to connect to SQL Server from another computer?

I'll edit my previous answer based on further info supplied. You can clearely ping the remote computer as you can use terminal services.

I've a feeling that port 1433 is being blocked by a firewall, hence your trouble. See TCP Ports Needed for Communication to SQL Server Through a Firewall by Microsoft.

Try using this application to ping your servers ip address and port 1433.

tcping your.server.ip.address 1433

And see if you get a "Port is open" response from tcping.

Ok, next to try is to check SQL Server. RDP onto the SQL Server computer. Start SSMS. Connect to the database. In object explorer (usually docked on the left) right click on the server and click properties.

alt text

Goto the Connections settings and make sure "Allow remote connections to this server" is ticket.

alt text

Call PHP function from Twig template

If you really know what you do and you don't mind the evil ways, this is the only additional Twig extension you'll ever need:

function evilEvalPhp($eval, $args = null)
    $result = null;
    return $result;

RecyclerView and java.lang.IndexOutOfBoundsException: Inconsistency detected. Invalid view holder adapter positionViewHolder in Samsung devices

In my case, I was getting this problem because of getting data updates from server (I am using Firebase Firestore) and while the first set of data is being processed by DiffUtil in the background, another set of data update comes and causes a concurrency issue by starting another DiffUtil.

In short, if you are using DiffUtil on a Background thread which then comes back to the Main Thread to dispatch the results to the RecylerView, then you run the chance of getting this error when multiple data updates come in short time.

I solved this by following the advice in this wonderful explanation:

Just to explain the solution is to push the updates while the current one is running to a Deque. The deque can then run the pending updates once the current one finishes, hence handling all subsequent updates but avoiding inconsistency errors as well!

Hope this helps because this one made me scratch my head!

How to check if a key exists in Json Object and get its value

Use below code to find key is exist or not in JsonObject. has("key") method is used to find keys in JsonObject.

containerObject = new JSONObject(container);
//has method
if (containerObject.has("video")) {
    //get Value of video
    String video = containerObject.optString("video");

If you are using optString("key") method to get String value then don't worry about keys are existing or not in the JsonObject.

How to create a self-signed certificate with OpenSSL

As of 2021, the following command serves all your needs, including SAN:

openssl req -x509 -newkey rsa:4096 -sha256 -days 3650 -nodes \
  -keyout example.key -out example.crt -extensions san -config \
  <(echo "[req]"; 
    echo distinguished_name=req; 
    echo "[san]"; 
    ) \
  -subj "/"

In OpenSSL = 1.1.1, this can be shortened to:

openssl req -x509 -newkey rsa:4096 -sha256 -days 3650 -nodes \
  -keyout example.key -out example.crt -subj "/" \
  -addext ",,IP:"

It creates a certificate that is

  • valid for the (sub)domains and (SAN),
  • also valid for the IP address (SAN),
  • relatively strong (as of 2021) and
  • valid for 3650 days (~10 years).

It creates the following files:

  • Private key: example.key
  • Certificate: example.crt

All information is provided at the command line. There is no interactive input that annoys you. There are no config files you have to mess around with. All necessary steps are executed by a single OpenSSL invocation: from private key generation up to the self-signed certificate.

Remark #1: Crypto parameters

Since the certificate is self-signed and needs to be accepted by users manually, it doesn't make sense to use a short expiration or weak cryptography.

In the future, you might want to use more than 4096 bits for the RSA key and a hash algorithm stronger than sha256, but as of 2021 these are sane values. They are sufficiently strong while being supported by all modern browsers.

Remark #2: Parameter "-nodes"

Theoretically you could leave out the -nodes parameter (which means "no DES encryption"), in which case example.key would be encrypted with a password. However, this is almost never useful for a server installation, because you would either have to store the password on the server as well, or you'd have to enter it manually on each reboot.

Remark #3: See also

error: command 'gcc' failed with exit status 1 while installing eventlet

What worked for me on CentOS was:

sudo yum -y install gcc
sudo yum install python-devel

Split String by delimiter position using oracle SQL

Therefore, I would like to separate the string by the furthest delimiter.

I know this is an old question, but this is a simple requirement for which SUBSTR and INSTR would suffice. REGEXP are still slower and CPU intensive operations than the old subtsr and instr functions.

  2    ( SELECT 'F/P/O' str FROM dual
  3    )
  4  SELECT SUBSTR(str, 1, Instr(str, '/', -1, 1) -1) part1,
  5         SUBSTR(str, Instr(str, '/', -1, 1) +1) part2
  7  /

----- -----
F/P   O

As you said you want the furthest delimiter, it would mean the first delimiter from the reverse.

You approach was fine, but you were missing the start_position in INSTR. If the start_position is negative, the INSTR function counts back start_position number of characters from the end of string and then searches towards the beginning of string.

How do I automatically set the $DISPLAY variable for my current session?

do you use Bash? Go to the file .bashrc in your home directory and set the variable, then export it.

DISPLAY=localhost:0.0 ; export DISPLAY

you can use /etc/bashrc if you want to do it for all the users.

You may also want to look in ~/.bash_profile and /etc/profile


function get_xserver ()
    case $TERM in
       xterm )
            XSERVER=$(who am i | awk '{print $NF}' | tr -d ')''(' )    
        aterm | rxvt)           

if [ -z ${DISPLAY:=""} ]; then
    if [[ -z ${XSERVER}  || ${XSERVER} == $(hostname) || \
      ${XSERVER} == "unix" ]]; then 
        DISPLAY=":0.0"          # Display on local host.
        DISPLAY=${XSERVER}:0.0  # Display on remote host.

export DISPLAY

How to zip a whole folder using PHP

Use this is working fine.

$dir = '/Folder/';
$zip = new ZipArchive();
$res = $zip->open(trim($dir, "/") . '.zip', ZipArchive::CREATE | ZipArchive::OVERWRITE);
if ($res === TRUE) {
    foreach (glob($dir . '*') as $file) {
        $zip->addFile($file, basename($file));
} else {
    echo 'Failed to create to zip. Error: ' . $res;

Delegates in swift?

Delegates are a design pattern that allows one object to send messages to another object when a specific event happens. Imagine an object A calls an object B to perform an action. Once the action is complete, object A should know that B has completed the task and take necessary action, this can be achieved with the help of delegates! Here is a tutorial implementing delegates step by step in swift 3

Tutorial Link

Simple post to Web Api

It's been quite sometime since I asked this question. Now I understand it more clearly, I'm going to put a more complete answer to help others.

In Web API, it's very simple to remember how parameter binding is happening.

  • if you POST simple types, Web API tries to bind it from the URL
  • if you POST complex type, Web API tries to bind it from the body of the request (this uses a media-type formatter).

  • If you want to bind a complex type from the URL, you'll use [FromUri] in your action parameter. The limitation of this is down to how long your data going to be and if it exceeds the url character limit.

    public IHttpActionResult Put([FromUri] ViewModel data) { ... }

  • If you want to bind a simple type from the request body, you'll use [FromBody] in your action parameter.

    public IHttpActionResult Put([FromBody] string name) { ... }

as a side note, say you are making a PUT request (just a string) to update something. If you decide not to append it to the URL and pass as a complex type with just one property in the model, then the data parameter in jQuery ajax will look something like below. The object you pass to data parameter has only one property with empty property name.

var myName = 'ABC';
$.ajax({url:.., data: {'': myName}});

and your web api action will look something like below.

public IHttpActionResult Put([FromBody] string name){ ... }

This page explains it all.

Using a BOOL property

Apple simply recommends declaring an isX getter for stylistic purposes. It doesn't matter whether you customize the getter name or not, as long as you use the dot notation or message notation with the correct name. If you're going to use the dot notation it makes no difference, you still access it by the property name:

@property (nonatomic, assign) BOOL working;

[self setWorking:YES];         // Or self.working = YES;
BOOL working = [self working]; // Or = self.working;


@property (nonatomic, assign, getter=isWorking) BOOL working;

[self setWorking:YES];           // Or self.working = YES;, same as above
BOOL working = [self isWorking]; // Or = self.working;, also same as above

Summarizing multiple columns with dplyr?

All the examples are great, but I figure I'd add one more to show how working in a "tidy" format simplifies things. Right now the data frame is in "wide" format meaning the variables "a" through "d" are represented in columns. To get to a "tidy" (or long) format, you can use gather() from the tidyr package which shifts the variables in columns "a" through "d" into rows. Then you use the group_by() and summarize() functions to get the mean of each group. If you want to present the data in a wide format, just tack on an additional call to the spread() function.


# Create reproducible df
df <- tibble(a   = sample(1:5, 10, replace=T), 
             b   = sample(1:5, 10, replace=T), 
             c   = sample(1:5, 10, replace=T), 
             d   = sample(1:5, 10, replace=T), 
             grp = sample(1:3, 10, replace=T))

# Convert to tidy format using gather
df %>%
    gather(key = variable, value = value, a:d) %>%
    group_by(grp, variable) %>%
    summarize(mean = mean(value)) %>%
    spread(variable, mean)
#> Source: local data frame [3 x 5]
#> Groups: grp [3]
#>     grp        a     b        c        d
#> * <int>    <dbl> <dbl>    <dbl>    <dbl>
#> 1     1 3.000000   3.5 3.250000 3.250000
#> 2     2 1.666667   4.0 4.666667 2.666667
#> 3     3 3.333333   3.0 2.333333 2.333333

Repeating a function every few seconds

For this the System.Timers.Timer works best

// Create a timer
myTimer = new System.Timers.Timer();
// Tell the timer what to do when it elapses
myTimer.Elapsed += new ElapsedEventHandler(myEvent);
// Set it to go off every five seconds
myTimer.Interval = 5000;
// And start it        
myTimer.Enabled = true;

// Implement a call with the right signature for events going off
private void myEvent(object source, ElapsedEventArgs e) { }

See Timer Class (.NET 4.6 and 4.5) for details

fatal error C1083: Cannot open include file: 'xyz.h': No such file or directory?

This problem can be easily solved by installing the following Individual components:

enter image description here

How to set a selected option of a dropdown list control using angular JS

I don't know if this will help anyone or not but as I was facing the same issue I thought of sharing how I got the solution.

You can use track by attribute in your ng-options.

Assume that you have:

variants:[{'id':0, name:'set of 6 traits'}, {'id':1, name:'5 complete sets'}]

You can mention your ng-options as:

ng-options=" for v in variants track by"

Hope this helps someone in future.

How to properly use jsPDF library

first, you have to create a handler.

var specialElementHandlers = {
    '#editor': function(element, renderer){
        return true;

then write this code in click event:

doc.fromHTML($('body').get(0), 15, 15, {
    'width': 170, 
    'elementHandlers': specialElementHandlers

var pdfOutput = doc.output();
            console.log(">>>"+pdfOutput );

assuming you've already declared doc variable. And Then you have save this pdf file using File-Plugin.

How to make an inline element appear on new line, or block element not occupy the whole line?

For the block element not occupy the whole line, set it's width to something small and the white-space:nowrap


How do I export (and then import) a Subversion repository?

Basically, there are plenty of ways to accomplish the task. The topic is covered in depth in SVNBook | Migrating Repository Data Elsewhere, so I suggest reading the book's section.

Here is a brief description of your options:

  • It depends on your environment, but there is a great chance that you can simply copy the repository to the new server and it will work. You have to revise repository hook scripts after copying the repo to ensure that they are working as you expect.

  • You can use svnadmin dump and svnadmin load commands to, ehm, generate full dump and then load it to another repository on another server. You will need to svnadmin create a new clean repository to load the dump into it. Keep in mind that the approach deals with repository history only and does not move hook scripts and repository configuration files! As well, you must have read filesystem access to the original repository to dump it.

  • Since Subversion 1.7, svnrdump tool is available. Generally speaking, it mimics svnadmin dump and svnadmin load functionality, but operates remotely. You are not required to have read / write filesystem access to original and target repositories as tool operates remotely like Subversion client, e.g. over HTTPS protocol. So you need to have read access to original repository and read / write to the target one.

  • Another option is to use svnadmin hotcopy command. The command is mostly used for backup purpose, it creates full copy of the repository including configuration and hook scripts. You can move hotcopied repository to another server then.

$date + 1 year?

In my case (i want to add 3 years to current date) the solution was:

$future_date = date('Y-m-d', strtotime("now + 3 years"));

To Gardenee, Treby and Daniel Lima: what will happen with 29th February? Sometimes February has only 28 days :)

How do you manually execute SQL commands in Ruby On Rails using NuoDB

For me, I couldn't get this to return a hash.

results = ActiveRecord::Base.connection.execute(sql)

But using the exec_query method worked.

results = ActiveRecord::Base.connection.exec_query(sql)

Two divs side by side - Fluid display

Using this CSS for my current site. It works perfect!


Apache error: _default_ virtualhost overlap on port 443

I ran into this problem because I had multiple wildcard entries for the same ports. You can easily check this by executing apache2ctl -S:

# apache2ctl -S
[Wed Oct 22 18:02:18 2014] [warn] _default_ VirtualHost overlap on port 30000, the first has precedence
[Wed Oct 22 18:02:18 2014] [warn] _default_ VirtualHost overlap on port 20001, the first has precedence
VirtualHost configuration:       is a NameVirtualHost
         default server (/etc/apache2/sites-enabled/
         port 80 namevhost (/etc/apache2/sites-enabled/
         [...]      is a NameVirtualHost
         default server (/etc/apache2/sites-enabled/
         port 443 namevhost (/etc/apache2/sites-enabled/
wildcard NameVirtualHosts and _default_ servers:
*:80          (/etc/apache2/sites-enabled/000-default:1)
*:20001       (/etc/apache2/sites-enabled/000-default:33)
*:30000       (/etc/apache2/sites-enabled/000-default:57)
_default_:443 (/etc/apache2/sites-enabled/default-ssl:2)
*:20001       (/etc/apache2/sites-enabled/default-ssl:163)
*:30000       (/etc/apache2/sites-enabled/default-ssl:178)
Syntax OK

Notice how at the beginning of the output are a couple of warning lines. These will indicate which ports are creating the problems (however you probably already knew that).

Next, look at the end of the output and you can see exactly which files and lines the virtualhosts are defined that are creating the problem. In the above example, port 20001 is assigned both in /etc/apache2/sites-enabled/000-default on line 33 and /etc/apache2/sites-enabled/default-ssl on line 163. Likewise *:30000 is listed in 2 places. The solution (in my case) was simply to delete one of the entries.

Local dependency in package.json

There is great yalc that helps to manage local packages. It helped me with local lib that I later deploy. Just pack project with .yalc directory (with or without /node_modules). So just do:

npm install -g yalc  

in directory lib/$ yalc publish 

in project:

project/$ yalc add lib

project/$ npm install 

that's it.

When You want to update stuff:

lib/$ yalc push   //this will updated all projects that use your "lib"

project/$ npm install 

Pack and deploy with Docker

tar -czvf <compresedFile> <directories and files...>
tar -czvf app.tar .yalc/ build/ src/ package.json package-lock.json

Note: Remember to add .yalc directory.


FROM node:lts-alpine3.9

ADD app.tar /app

RUN npm install

CMD [ "node", "src/index.js" ]

Hibernate: get entity by id

In getUserById you shouldn't create a new object (user1) which isn't used. Just assign it to the already (but null) initialized user. Otherwise Hibernate.initialize(user); is actually Hibernate.initialize(null);

Here's the new getUserById (I haven't tested this ;)):

public User getUserById(Long user_id) {
    Session session = null;
    Object user = null;
    try {
        session = HibernateUtil.getSessionFactory().openSession();
        user = (User)session.load(User.class, user_id);
    } catch (Exception e) {
    } finally {
        if (session != null && session.isOpen()) {
    return user;

Connecting client to server using

You need to make sure that you add forward slash before your link to

<script src="/"></script>

Then in the view/controller just do:

var socket = io.connect()

That should solve your problem.

Oracle insert from select into table with more columns

Just add in the '0' in your select.

INSERT INTO table_name (a,b,c,d)
       other_table.a AS a,
       other_table.b AS b,
       other_table.c AS c,
       '0' AS d
    FROM other_table

What is wrong with this code that uses the mysql extension to fetch data from a database in PHP?

use this code

  while ($rows = mysql_fetch_array($query)):

   $name = $rows['Name'];
   $address = $rows['Address'];
   $email = $rows['Email'];
   $subject = $rows['Subject'];
   $comment = $rows['Comment'];

   echo "$name<br>$address<br>$email<br>$subject<br>$comment<br><br>";



Fastest way to convert string to integer in PHP

I've just set up a quick benchmarking exercise:

Function             time to run 1 million iterations
(int) "123":                0.55029
intval("123"):              1.0115  (183%)

(int) "0":                  0.42461
intval("0"):                0.95683 (225%)

(int) int:                  0.1502
intval(int):                0.65716 (438%)

(int) array("a", "b"):      0.91264
intval(array("a", "b")):    1.47681 (162%)

(int) "hello":              0.42208
intval("hello"):            0.93678 (222%)

On average, calling intval() is two and a half times slower, and the difference is the greatest if your input already is an integer.

I'd be interested to know why though.

Update: I've run the tests again, this time with coercion (0 + $var)

| INPUT ($x)      |  (int) $x  |intval($x) |  0 + $x   |
| "123"           |   0.51541  |  0.96924  |  0.33828  |
| "0"             |   0.42723  |  0.97418  |  0.31353  |
| 123             |   0.15011  |  0.61690  |  0.15452  |
| array("a", "b") |   0.8893   |  1.45109  |  err!     |
| "hello"         |   0.42618  |  0.88803  |  0.1691   |

Addendum: I've just come across a slightly unexpected behaviour which you should be aware of when choosing one of these methods:

$x = "11";
(int) $x;      // int(11)
intval($x);    // int(11)
$x + 0;        // int(11)

$x = "0x11";
(int) $x;      // int(0)
intval($x);    // int(0)
$x + 0;        // int(17) !

$x = "011";
(int) $x;      // int(11)
intval($x);    // int(11)
$x + 0;        // int(11) (not 9)

Tested using PHP 5.3.1

How to download python from command-line?

Well if you are getting into a linux machine you can use the package manager of that linux distro.

If you are using Ubuntu just use apt-get search python, check the list and do apt-get install python2.7 (not sure if python2.7 or python-2.7, check the list)

You could use yum in fedora and do the same.

if you want to install it on your windows machine i dont know any package manager, i would download the wget for windows, donwload the package from and install it

How make background image on newsletter in outlook?

The only way I was able to do this is via this code (TD tables). I tested in outlook client 2010. I also tested via webmail client and it worked for both.

The only things you have to do is change your_image.jpg (there are two instances of this for the same image make sure you update both for your code) and #your_color.

<td bgcolor="#your_color" background="your_image.jpg">

<!--[if gte mso 9]>

<v:image xmlns:v="urn:schemas-microsoft-com:vml" id="theImage" style='behavior: url(#default#VML); display:inline-block; position:absolute; height:300px; width:600px; top:0; left:0; border:0; z-index:1;' src="your_image.jpg"/>

<v:shape xmlns:v="urn:schemas-microsoft-com:vml" id="theText" style='behavior: url(#default#VML); display:inline-block; position:absolute; height:300px; width:600px; top:-5; left:-10; border:0; z-index:2;'>


<p>Text over background image.</p>

<!--[if gte mso 9]>





MySQL Where DateTime is greater than today

Remove the date() part

SELECT name, datum 
FROM tasks 
WHERE datum >= NOW()

and if you use a specific date, don't forget the quotes around it and use the proper format with :

SELECT name, datum 
FROM tasks 
WHERE datum >= '2014-05-18 15:00:00'

How to solve PHP error 'Notice: Array to string conversion in...'

Array to string conversion in latest versions of php 7.x is error, rather than notice, and prevents further code execution.

Using print, echo on array is not an option anymore.

Suppressing errors and notices is not a good practice, especially when in development environment and still debugging code.

Use var_dump,print_r, iterate through input value using foreach or for to output input data for names that are declared as input arrays ('name[]')

Most common practice to catch errors is using try/catch blocks, that helps us prevent interruption of code execution that might cause possible errors wrapped within try block.

  try{  //wrap around possible cause of error or notice
        echo $_POST['C'];

  }catch(Exception $e){

    //handle the error message $e->getMessage();

Job for mysqld.service failed See "systemctl status mysqld.service"

This amazingly worked.

/etc/init.d/mysql stop
service mysql stop
killall -KILL mysql mysqld_safe mysqld
/etc/init.d/mysql start
service mysql start

How do you force Visual Studio to regenerate the .designer files for aspx/ascx files?

Apart from all the good answers already given, I'd like to add to @johan-leino's great answer. In my case, for some arbitrary reason, the CodeBehind attribute was omitted from the @Page directive/.aspx file. Likewise, it might be worthwhile to check the CodeFile attribute for @Control directives/.ascx files (obviously in conjunction with an Inherits attribute in both cases).

Depending on the exact scenario and reason required to 'force' a regenerate of .designer.cs, one could also try to format the document (potentially indicating a parsing error) before (quick) saving (regardless whether there were any changes or not) and check the Error List for warnings.

Removing an element from an Array (Java)

You could use the ArrayUtils API to remove it in a "nice looking way". It implements many operations (remove, find, add, contains,etc) on Arrays.
Take a look. It has made my life simpler.

How to Serialize a list in java?

List is just an interface. The question is: is your actual List implementation serializable? Speaking about the standard List implementations (ArrayList, LinkedList) from the Java run-time, most of them actually are already.

How do I find the data directory for a SQL Server instance?

You can find default Data and Log locations for the current SQL Server instance by using the following T-SQL:

DECLARE @defaultDataLocation nvarchar(4000)
DECLARE @defaultLogLocation nvarchar(4000)

EXEC master.dbo.xp_instance_regread
    @defaultDataLocation OUTPUT

EXEC master.dbo.xp_instance_regread
    @defaultLogLocation OUTPUT

SELECT @defaultDataLocation AS 'Default Data Location',
       @defaultLogLocation AS 'Default Log Location'

How to find time complexity of an algorithm

Although there are some good answers for this question. I would like to give another answer here with several examples of loop.

  • O(n): Time Complexity of a loop is considered as O(n) if the loop variables is incremented / decremented by a constant amount. For example following functions have O(n) time complexity.

    // Here c is a positive integer constant   
    for (int i = 1; i <= n; i += c) {  
        // some O(1) expressions
    for (int i = n; i > 0; i -= c) {
        // some O(1) expressions
  • O(n^c): Time complexity of nested loops is equal to the number of times the innermost statement is executed. For example the following sample loops have O(n^2) time complexity

    for (int i = 1; i <=n; i += c) {
       for (int j = 1; j <=n; j += c) {
          // some O(1) expressions
    for (int i = n; i > 0; i += c) {
       for (int j = i+1; j <=n; j += c) {
          // some O(1) expressions

    For example Selection sort and Insertion Sort have O(n^2) time complexity.

  • O(Logn) Time Complexity of a loop is considered as O(Logn) if the loop variables is divided / multiplied by a constant amount.

    for (int i = 1; i <=n; i *= c) {
       // some O(1) expressions
    for (int i = n; i > 0; i /= c) {
       // some O(1) expressions

    For example Binary Search has O(Logn) time complexity.

  • O(LogLogn) Time Complexity of a loop is considered as O(LogLogn) if the loop variables is reduced / increased exponentially by a constant amount.

    // Here c is a constant greater than 1   
    for (int i = 2; i <=n; i = pow(i, c)) { 
       // some O(1) expressions
    //Here fun is sqrt or cuberoot or any other constant root
    for (int i = n; i > 0; i = fun(i)) { 
       // some O(1) expressions

One example of time complexity analysis

int fun(int n)
    for (int i = 1; i <= n; i++)
        for (int j = 1; j < n; j += i)
            // Some O(1) task


For i = 1, the inner loop is executed n times. For i = 2, the inner loop is executed approximately n/2 times. For i = 3, the inner loop is executed approximately n/3 times. For i = 4, the inner loop is executed approximately n/4 times. ……………………………………………………. For i = n, the inner loop is executed approximately n/n times.

So the total time complexity of the above algorithm is (n + n/2 + n/3 + … + n/n), Which becomes n * (1/1 + 1/2 + 1/3 + … + 1/n)

The important thing about series (1/1 + 1/2 + 1/3 + … + 1/n) is equal to O(Logn). So the time complexity of the above code is O(nLogn).

Ref: 1 2 3

How to delete row in gridview using rowdeleting event?

I think you are doing same mistake of rebinding as mentioned in this link

How to delete row from gridview?

Changing the JFrame title

these methods can help setTitle("your new title"); or super("your new title");

Django - filtering on foreign key properties

student_user = User.objects.get(id=user_id)
available_subjects = Subject.objects.exclude(subject_grade__student__user=student_user) # My ans
enrolled_subjects = SubjectGrade.objects.filter(student__user=student_user)
context.update({'available_subjects': available_subjects, 'student_user': student_user, 
                'request':request, 'enrolled_subjects': enrolled_subjects})

In my application above, i assume that once a student is enrolled, a subject SubjectGrade instance will be created that contains the subject enrolled and the student himself/herself.

Subject and Student User model is a Foreign Key to the SubjectGrade Model.

In "available_subjects", i excluded all the subjects that are already enrolled by the current student_user by checking all subjectgrade instance that has "student" attribute as the current student_user

PS. Apologies in Advance if you can't still understand because of my explanation. This is the best explanation i Can Provide. Thank you so much

List Highest Correlation Pairs from a Large Correlation Matrix in Pandas?

I didn't want to unstack or over-complicate this issue, since I just wanted to drop some highly correlated features as part of a feature selection phase.

So I ended up with the following simplified solution:

# map features to their absolute correlation values
corr = features.corr().abs()

# set equality (self correlation) as zero
corr[corr == 1] = 0

# of each feature, find the max correlation
# and sort the resulting array in ascending order
corr_cols = corr.max().sort_values(ascending=False)

# display the highly correlated features
display(corr_cols[corr_cols > 0.8])

In this case, if you want to drop correlated features, you may map through the filtered corr_cols array and remove the odd-indexed (or even-indexed) ones.

Get current clipboard content?

Following will give you the selected content as well as updating the clipboard.

Bind the element id with copy event and then get the selected text. You could replace or modify the text. Get the clipboard and set the new text. To get the exact formatting you need to set the type as "text/hmtl". You may also bind it to the document instead of element.

document.querySelector('element').bind('copy', function(event) {
  var selectedText = window.getSelection().toString(); 
  selectedText = selectedText.replace(/\u200B/g, "");

  clipboardData = event.clipboardData || window.clipboardData || event.originalEvent.clipboardData;
  clipboardData.setData('text/html', selectedText);


VBA Convert String to Date

I used this code:

ws.Range("A:A").FormulaR1C1 = "=DATEVALUE(RC[1])"

column A will be mm/dd/yyyy

RC[1] is column B, the TEXT string, eg, 01/30/12, THIS IS NOT DATE TYPE

System.BadImageFormatException An attempt was made to load a program with an incorrect format

For running it on any CPU either 62 bit or 32 bit follow these steps: Right click on the name of the project in Solution Explorer> Properties>Build and have these under Configuration: Active(Release), Platform:Active(Any CPU) and Target:x86. and just beside the Run button Select option Release and Any CPU from the options. And then Save it and Run.

WebView link click open default browser

I had to do the same thing today and I have found a very useful answer on StackOverflow that I want to share here in case someone else needs it.

Source (from sven)

webView.setWebViewClient(new WebViewClient(){
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
        if (url != null && (url.startsWith("http://") || url.startsWith("https://"))) {
                new Intent(Intent.ACTION_VIEW, Uri.parse(url)));
            return true;
        } else {
            return false;

word-wrap break-word does not work in this example

to get the smart break (break-word) work well on different browsers, what worked for me was the following set of rules:

#elm {
    word-break:break-word; /* webkit/blink browsers */
    word-wrap:break-word; /* ie */
-moz-document url-prefix() {/* catch ff */
    #elm {
        word-break: break-all; /* in ff-  with no break-word we'll settle for break-all */

What are the best PHP input sanitizing functions?


You're making a mistake here. Oh, no, you've picked the right PHP functions to make your data a bit safer. That's fine. Your mistake is in the order of operations, and how and where to use these functions.

It's important to understand the difference between sanitizing and validating user data, escaping data for storage, and escaping data for presentation.

Sanitizing and Validating User Data

When users submit data, you need to make sure that they've provided something you expect.

Sanitization and Filtering

For example, if you expect a number, make sure the submitted data is a number. You can also cast user data into other types. Everything submitted is initially treated like a string, so forcing known-numeric data into being an integer or float makes sanitization fast and painless.

What about free-form text fields and textareas? You need to make sure that there's nothing unexpected in those fields. Mainly, you need to make sure that fields that should not have any HTML content do not actually contain HTML. There are two ways you can deal with this problem.

First, you can try escaping HTML input with htmlspecialchars. You should not use htmlentities to neutralize HTML, as it will also perform encoding of accented and other characters that it thinks also need to be encoded.

Second, you can try removing any possible HTML. strip_tags is quick and easy, but also sloppy. HTML Purifier does a much more thorough job of both stripping out all HTML and also allowing a selective whitelist of tags and attributes through.

Modern PHP versions ship with the filter extension, which provides a comprehensive way to sanitize user input.


Making sure that submitted data is free from unexpected content is only half of the job. You also need to try and make sure that the data submitted contains values you can actually work with.

If you're expecting a number between 1 and 10, you need to check that value. If you're using one of those new fancy HTML5-era numeric inputs with a spinner and steps, make sure that the submitted data is in line with the step.

If that data came from what should be a drop-down menu, make sure that the submitted value is one that appeared in the menu.

What about text inputs that fulfill other needs? For example, date inputs should be validated through strtotime or the DateTime class. The given date should be between the ranges you expect. What about email addresses? The previously mentioned filter extension can check that an address is well-formed, though I'm a fan of the is_email library.

The same is true for all other form controls. Have radio buttons? Validate against the list. Have checkboxes? Validate against the list. Have a file upload? Make sure the file is of an expected type, and treat the filename like unfiltered user data.

Every modern browser comes with a complete set of developer tools built right in, which makes it trivial for anyone to manipulate your form. Your code should assume that the user has completely removed all client-side restrictions on form content!

Escaping Data for Storage

Now that you've made sure that your data is in the expected format and contains only expected values, you need to worry about persisting that data to storage.

Every single data storage mechanism has a specific way to make sure data is properly escaped and encoded. If you're building SQL, then the accepted way to pass data in queries is through prepared statements with placeholders.

One of the better ways to work with most SQL databases in PHP is the PDO extension. It follows the common pattern of preparing a statement, binding variables to the statement, then sending the statement and variables to the server. If you haven't worked with PDO before here's a pretty good MySQL-oriented tutorial.

Some SQL databases have their own specialty extensions in PHP, including SQL Server, PostgreSQL and SQLite 3. Each of those extensions has prepared statement support that operates in the same prepare-bind-execute fashion as PDO. Sometimes you may need to use these extensions instead of PDO to support non-standard features or behavior.

MySQL also has its own PHP extensions. Two of them, in fact. You only want to ever use the one called mysqli. The old "mysql" extension has been deprecated and is not safe or sane to use in the modern era.

I'm personally not a fan of mysqli. The way it performs variable binding on prepared statements is inflexible and can be a pain to use. When in doubt, use PDO instead.

If you are not using an SQL database to store your data, check the documentation for the database interface you're using to determine how to safely pass data through it.

When possible, make sure that your database stores your data in an appropriate format. Store numbers in numeric fields. Store dates in date fields. Store money in a decimal field, not a floating point field. Review the documentation provided by your database on how to properly store different data types.

Escaping Data for Presentation

Every time you show data to users, you must make sure that the data is safely escaped, unless you know that it shouldn't be escaped.

When emitting HTML, you should almost always pass any data that was originally user-supplied through htmlspecialchars. In fact, the only time you shouldn't do this is when you know that the user provided HTML, and that you know that it's already been sanitized it using a whitelist.

Sometimes you need to generate some Javascript using PHP. Javascript does not have the same escaping rules as HTML! A safe way to provide user-supplied values to Javascript via PHP is through json_encode.

And More

There are many more nuances to data validation.

For example, character set encoding can be a huge trap. Your application should follow the practices outlined in "UTF-8 all the way through". There are hypothetical attacks that can occur when you treat string data as the wrong character set.

Earlier I mentioned browser debug tools. These tools can also be used to manipulate cookie data. Cookies should be treated as untrusted user input.

Data validation and escaping are only one aspect of web application security. You should make yourself aware of web application attack methodologies so that you can build defenses against them.

Can typescript export a function?

If you are using this for Angular, then export a function via a named export. Such as:

function someFunc(){}

export { someFunc as someFuncName }

otherwise, Angular will complain that object is not a function.

Where is Python's sys.path initialized from?

Python really tries hard to intelligently set sys.path. How it is set can get really complicated. The following guide is a watered-down, somewhat-incomplete, somewhat-wrong, but hopefully-useful guide for the rank-and-file python programmer of what happens when python figures out what to use as the initial values of sys.path, sys.executable, sys.exec_prefix, and sys.prefix on a normal python installation.

First, python does its level best to figure out its actual physical location on the filesystem based on what the operating system tells it. If the OS just says "python" is running, it finds itself in $PATH. It resolves any symbolic links. Once it has done this, the path of the executable that it finds is used as the value for sys.executable, no ifs, ands, or buts.

Next, it determines the initial values for sys.exec_prefix and sys.prefix.

If there is a file called pyvenv.cfg in the same directory as sys.executable or one directory up, python looks at it. Different OSes do different things with this file.

One of the values in this config file that python looks for is the configuration option home = <DIRECTORY>. Python will use this directory instead of the directory containing sys.executable when it dynamically sets the initial value of sys.prefix later. If the applocal = true setting appears in the pyvenv.cfg file on Windows, but not the home = <DIRECTORY> setting, then sys.prefix will be set to the directory containing sys.executable.

Next, the PYTHONHOME environment variable is examined. On Linux and Mac, sys.prefix and sys.exec_prefix are set to the PYTHONHOME environment variable, if it exists, superseding any home = <DIRECTORY> setting in pyvenv.cfg. On Windows, sys.prefix and sys.exec_prefix is set to the PYTHONHOME environment variable, if it exists, unless a home = <DIRECTORY> setting is present in pyvenv.cfg, which is used instead.

Otherwise, these sys.prefix and sys.exec_prefix are found by walking backwards from the location of sys.executable, or the home directory given by pyvenv.cfg if any.

If the file lib/python<version>/dyn-load is found in that directory or any of its parent directories, that directory is set to be to be sys.exec_prefix on Linux or Mac. If the file lib/python<version>/ is is found in the directory or any of its subdirectories, that directory is set to be sys.prefix on Linux, Mac, and Windows, with sys.exec_prefix set to the same value as sys.prefix on Windows. This entire step is skipped on Windows if applocal = true is set. Either the directory of sys.executable is used or, if home is set in pyvenv.cfg, that is used instead for the initial value of sys.prefix.

If it can't find these "landmark" files or sys.prefix hasn't been found yet, then python sets sys.prefix to a "fallback" value. Linux and Mac, for example, use pre-compiled defaults as the values of sys.prefix and sys.exec_prefix. Windows waits until sys.path is fully figured out to set a fallback value for sys.prefix.

Then, (what you've all been waiting for,) python determines the initial values that are to be contained in sys.path.

  1. The directory of the script which python is executing is added to sys.path. On Windows, this is always the empty string, which tells python to use the full path where the script is located instead.
  2. The contents of PYTHONPATH environment variable, if set, is added to sys.path, unless you're on Windows and applocal is set to true in pyvenv.cfg.
  3. The zip file path, which is <prefix>/lib/ on Linux/Mac and os.path.join(os.dirname(sys.executable), "") on Windows, is added to sys.path.
  4. If on Windows and no applocal = true was set in pyvenv.cfg, then the contents of the subkeys of the registry key HK_CURRENT_USER\Software\Python\PythonCore\<DLLVersion>\PythonPath\ are added, if any.
  5. If on Windows and no applocal = true was set in pyvenv.cfg, and sys.prefix could not be found, then the core contents of the of the registry key HK_CURRENT_USER\Software\Python\PythonCore\<DLLVersion>\PythonPath\ is added, if it exists;
  6. If on Windows and no applocal = true was set in pyvenv.cfg, then the contents of the subkeys of the registry key HK_LOCAL_MACHINE\Software\Python\PythonCore\<DLLVersion>\PythonPath\ are added, if any.
  7. If on Windows and no applocal = true was set in pyvenv.cfg, and sys.prefix could not be found, then the core contents of the of the registry key HK_CURRENT_USER\Software\Python\PythonCore\<DLLVersion>\PythonPath\ is added, if it exists;
  8. If on Windows, and PYTHONPATH was not set, the prefix was not found, and no registry keys were present, then the relative compile-time value of PYTHONPATH is added; otherwise, this step is ignored.
  9. Paths in the compile-time macro PYTHONPATH are added relative to the dynamically-found sys.prefix.
  10. On Mac and Linux, the value of sys.exec_prefix is added. On Windows, the directory which was used (or would have been used) to search dynamically for sys.prefix is added.

At this stage on Windows, if no prefix was found, then python will try to determine it by searching all the directories in sys.path for the landmark files, as it tried to do with the directory of sys.executable previously, until it finds something. If it doesn't, sys.prefix is left blank.

Finally, after all this, Python loads the site module, which adds stuff yet further to sys.path:

It starts by constructing up to four directories from a head and a tail part. For the head part, it uses sys.prefix and sys.exec_prefix; empty heads are skipped. For the tail part, it uses the empty string and then lib/site-packages (on Windows) or lib/pythonX.Y/site-packages and then lib/site-python (on Unix and Macintosh). For each of the distinct head-tail combinations, it sees if it refers to an existing directory, and if so, adds it to sys.path and also inspects the newly added path for configuration files.

Importing images from a directory (Python) to list or dictionary

from PIL import Image
import os, os.path

imgs = []
path = "/home/tony/pictures"
valid_images = [".jpg",".gif",".png",".tga"]
for f in os.listdir(path):
    ext = os.path.splitext(f)[1]
    if ext.lower() not in valid_images:

Getting number of elements in an iterator in Python

One simple way is using set() built-in function:

iter = zip([1,2,3],['a','b','c'])
print(len(set(iter)) # set(iter) = {(1, 'a'), (2, 'b'), (3, 'c')}
Out[45]: 3


iter = range(1,10)
print(len(set(iter)) # set(iter) = {1, 2, 3, 4, 5, 6, 7, 8, 9}
Out[47]: 9

Authentication failed because remote party has closed the transport stream

I would advise against restricting the SecurityProtocol to TLS 1.1.

The recommended solution is to use

System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls

Another option is add the following Registry key:

Key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319 
Value: SchUseStrongCrypto 

It is worth noting that .NET 4.6 will use the correct protocol by default and does not require either solution.

How to create a new text file using Python

# Method 1
f = open("Path/To/Your/File.txt", "w")   # 'r' for reading and 'w' for writing
f.write("Hello World from " +    # Write inside file 
f.close()                                # Close file 

# Method 2
with open("Path/To/Your/File.txt", "w") as f:   # Opens file and casts as f 
    f.write("Hello World form " +       # Writing
    # File closed automatically

There are many more methods but these two are most common. Hope this helped!

Create a data.frame with m columns and 2 rows

For completeness:

Along the lines of Chase's answer, I usually use to coerce the matrix to a data.frame:

m <-, ncol = 30, nrow = 2))

EDIT: speed test data.frame vs.

system.time(replicate(10000, data.frame(matrix(0, ncol = 30, nrow = 2))))
   user  system elapsed 
  8.005   0.108   8.165 

system.time(replicate(10000,, ncol = 30, nrow = 2))))
   user  system elapsed 
  3.759   0.048   3.802 

Yes, it appears to be faster (by about 2 times).

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

using System;
using System.IO;
using System.IO.Compression;

namespace ConsoleApplication
    class Program`enter code here`
        static void Main(string[] args)
            using (FileStream zipToOpen = new FileStream(@"c:\users\exampleuser\", FileMode.Open))
                using (ZipArchive archive = new ZipArchive(zipToOpen, ZipArchiveMode.Update))
                    ZipArchiveEntry readmeEntry = archive.CreateEntry("Readme.txt");
                    using (StreamWriter writer = new StreamWriter(readmeEntry.Open()))
                            writer.WriteLine("Information about this package.");

hadoop No FileSystem for scheme: file

Another possible cause (though the OPs question doesn't itself suffer from this) is if you create a configuration instance that does not load the defaults:

Configuration config = new Configuration(false);

If you don't load the defaults then you won't get the default settings for things like the FileSystem implementations which leads to identical errors like this when trying to access HDFS. Switching to the parameterless constructor of passing in true to load defaults may resolve this.

Additionally if you are adding custom configuration locations (e.g. on the file system) to the Configuration object be careful of which overload of addResource() you use. For example if you use addResource(String) then Hadoop assumes that the string is a class path resource, if you need to specify a local file try the following:

File configFile = new File("example/config.xml");
config.addResource(new Path("file://" + configFile.getAbsolutePath()));

#1062 - Duplicate entry for key 'PRIMARY'

The DB I was importing had a conflict during the import due to the presence of a column both autoincrement and primary key.

The problem was that in the .sql file the table was chopped into multiple "INSERT INTO" and during the import these queries were executed all together.

MY SOLUTION was to deselect the "Run multiple queries in each execution" on Navicat and it worked perfectly

Is there an easy way to attach source in Eclipse?

When you add a jar file to a classpath you can attach a source directory or zip or jar file to that jar. In the Java Build Path properties, on the Libraries tab, expand the entry for the jar and you'll see there's an item for the source attachment. Select this item and then click the Edit button. This lets you select the folder, jar or zip that contains the source.

Additionally, if you select a class or a method in the jar and CTRL+CLICK on it (or press F3) then you'll go into the bytecode view which has an option to attach the source code.

Doing these things will give you all the parameter names as well as full javadoc.

If you don't have the source but do have the javadoc, you can attach the javadoc via the first method. It can even reference an external URL if you don't have it downloaded.

UIViewController viewDidLoad vs. viewWillAppear: What is the proper division of labor?

Initially used only ViewDidLoad with tableView. On testing with loss of Wifi, by setting device to airplane mode, realized that the table did not refresh with return of Wifi. In fact, there appears to be no way to refresh tableView on the device even by hitting the home button with background mode set to YES in -Info.plist.

My solution:

-(void) viewWillAppear: (BOOL) animated { [self.tableView reloadData];}

Group array items using object

Using ES6, this can be done quite nicely using .reduce() with a Map as the accumulator, and then using Array.from() with its mapping function to map each grouped map-entry to an object:

const arr = [{"group":"one","color":"red"},{"group":"two","color":"blue"},{"group":"one","color":"green"},{"group":"one","color":"black"}];

const res = Array.from(arr.reduce((m, {group, color}) => 
    m.set(group, [...(m.get(group) || []), color]), new Map
  ), ([group, color]) => ({group, color})


If you have additional properties in your objects other than just group and color, you can take a more general approach by setting a grouped object as the map's values like so:

const arr = [{"group":"one","color":"red"},{"group":"two","color":"blue"},{"group":"one","color":"green"},{"group":"one","color":"black"}];

const groupAndMerge = (arr, groupBy, mergeInto) => 
  Array.from(arr.reduce((m, o) => {
    const curr = m.get(o[groupBy]);
    return m.set(o[groupBy], {...o, [mergeInto]: [...(curr && curr[mergeInto] || []), o[mergeInto]]});
  }, new Map).values());

console.log(groupAndMerge(arr, 'group', 'color'));

If you can support optional chaining and the nullish coalescing operator (??), you can simplify the above method to the following:

const arr = [{"group":"one","color":"red"},{"group":"two","color":"blue"},{"group":"one","color":"green"},{"group":"one","color":"black"}];
const groupAndMerge = (arr, groupBy, mergeWith) =>
  Array.from(arr.reduce((m, o) => m.set(o[groupBy], {...o, [mergeWith]: [...(m.get(o[groupBy])?.[mergeWith] ?? []), o[mergeWith]]}), new Map).values());

console.log(groupAndMerge(arr, 'group', 'color'));

Node.js server that accepts POST requests

The following code shows how to read values from an HTML form. As @pimvdb said you need to use the request.on('data'...) to capture the contents of the body.

const http = require('http')

const server = http.createServer(function(request, response) {

  if (request.method == 'POST') {
    var body = ''
    request.on('data', function(data) {
      body += data
      console.log('Partial body: ' + body)
    request.on('end', function() {
      console.log('Body: ' + body)
      response.writeHead(200, {'Content-Type': 'text/html'})
      response.end('post received')
  } else {
    var html = `
                    <form method="post" action="http://localhost:3000">Name: 
                        <input type="text" name="name" />
                        <input type="submit" value="Submit" />
    response.writeHead(200, {'Content-Type': 'text/html'})

const port = 3000
const host = ''
server.listen(port, host)
console.log(`Listening at http://${host}:${port}`)

If you use something like Express.js and Bodyparser then it would look like this since Express will handle the request.body concatenation

var express = require('express')
var fs = require('fs')
var app = express()


app.get('/', function(request, response) {
  console.log('GET /')
  var html = `
            <form method="post" action="http://localhost:3000">Name: 
                <input type="text" name="name" />
                <input type="submit" value="Submit" />
  response.writeHead(200, {'Content-Type': 'text/html'})
})'/', function(request, response) {
  console.log('POST /')
  response.writeHead(200, {'Content-Type': 'text/html'})

port = 3000
console.log(`Listening at http://localhost:${port}`)

compareTo() vs. equals()

equals() should be the method of choice in the case of the OP.

Looking at the implementation of equals() and compareTo() in java.lang.String on grepcode, we can easily see that equals is better if we are just concerned with the equality of two Strings:


1012  public boolean equals(Object anObject) {
1013 if (this == anObject) {
1014 return true;
1015 }
1016 if (anObject instanceof String) {
1017 String anotherString = (String)anObject;
1018 int n = count;
1019 if (n == anotherString.count) {
1020 char v1[] = value;
1021 char v2[] = anotherString.value;
1022 int i = offset;
1023 int j = anotherString.offset;
1024 while (n-- != 0) {
1025 if (v1[i++] != v2[j++])
1026 return false;
1027 }
1028 return true;
1029 }
1030 }
1031 return false;
1032 }

and compareTo():

1174  public int compareTo(String anotherString) {
1175 int len1 = count;
1176 int len2 = anotherString.count;
1177 int n = Math.min(len1, len2);
1178 char v1[] = value;
1179 char v2[] = anotherString.value;
1180 int i = offset;
1181 int j = anotherString.offset;
1183 if (i == j) {
1184 int k = i;
1185 int lim = n + i;
1186 while (k < lim) {
1187 char c1 = v1[k];
1188 char c2 = v2[k];
1189 if (c1 != c2) {
1190 return c1 - c2;
1191 }
1192 k++;
1193 }
1194 } else {
1195 while (n-- != 0) {
1196 char c1 = v1[i++];
1197 char c2 = v2[j++];
1198 if (c1 != c2) {
1199 return c1 - c2;
1200 }
1201 }
1202 }
1203 return len1 - len2;
1204 }

When one of the strings is a prefix of another, the performance of compareTo() is worse as it still needs to determine the lexicographical ordering while equals() won't worry any more and return false immediately.

In my opinion, we should use these two as they were intended:

  • equals() to check for equality, and
  • compareTo() to find the lexical ordering.

In JavaScript, why is "0" equal to false, but when tested by 'if' it is not false by itself?

It's PHP where the string "0" is falsy (false-when-used-in-boolean-context). In JavaScript, all non-empty strings are truthy.

The trick is that == against a boolean doesn't evaluate in a boolean context, it converts to number, and in the case of strings that's done by parsing as decimal. So you get Number 0 instead of the truthiness boolean true.

This is a really poor bit of language design and it's one of the reasons we try not to use the unfortunate == operator. Use === instead.

Comments in Markdown

If you are using Jekyll or octopress following will also work.

{% comment %} 
    These commments will not include inside the source.
{% endcomment %}

The Liquid tags {% comment %} are parsed first and removed before the MarkDown processor even gets to it. Visitors will not see when they try to view source from their browser.

How do I set the rounded corner radius of a color drawable using xml?

Use the <shape> tag to create a drawable in XML with rounded corners. (You can do other stuff with the shape tag like define a color gradient as well).

Here's a copy of a XML file I'm using in one of my apps to create a drawable with a white background, black border and rounded corners:

<?xml version="1.0" encoding="UTF-8"?> 
<shape xmlns:android=""> 
    <solid android:color="#ffffffff"/>    
    <stroke android:width="3dp"
            android:color="#ff000000" />

    <padding android:left="1dp"
             android:bottom="1dp" /> 
    <corners android:radius="7dp" /> 

ASP.NET Web API : Correct way to return a 401/unauthorised response

You get a 500 response code because you're throwing an exception (the HttpException) which indicates some kind of server error, this is the wrong approach.

Just set the response status code .e.g

Response.StatusCode = (int)HttpStatusCode.Unauthorized;

PHP date add 5 year to current date

You may use DateInterval for this purpose;

$currentDate = new \DateTime(); //creates today timestamp
$currentDate->add(new \DateInterval('P5Y')); //this means 5 Years
and you can now format it;

How to avoid reverse engineering of an APK file?

Its not possible to completely avoid RE but By making them more complex internally, you put make it more difficult for attackers to see the clear operation of the app, which may reduce the number of attack vectors.

If the application handles highly sensitive data, Various techniques exist which can increase the complexity of reverse engineering your code. One technique is to use C/C++ to limit easy runtime manipulation by the attacker. There are ample C and C++ libraries that are very mature and easy to integrate with Android offers JNI. An attacker must first circumvent the debugging restrictions in order to attack the application on a low level. This adds further complexity to an attack. Android applications should have android:debuggable=”false” set in the application manifest to prevent easy run time manipulation by an attacker or malware.

Trace Checking – An application can determine whether or not it is currently being traced by a debugger or other debugging tool. If being traced, the application can perform any number of possible attack response actions, such as discarding encryption keys to protect user data, notifying a server administrator, or other such type responses in an attempt to defend itself. This can be determined by checking the process status flags or using other techniques like comparing the return value of ptrace attach, checking parent process, blacklist debuggers in the process list or comparing timestamps on different places of the program.

Optimizations - To hide advanced mathematical computations and other types of complex logic, utilizing compiler optimizations can help obfuscate the object code so that it cannot easily be disassembled by an attacker, making it more difficult for an attacker to gain an understanding of the particular code. In Android this can more easily be achieved by utilizing natively compiled libraries with the NDK. In addition, using an LLVM Obfuscator or any protector SDK will provide better machine code obfuscation.

Stripping binaries – Stripping native binaries is an effective way to increase the amount of time and skill level required of an attacker in order to view the makeup of your application’s low level functions. By stripping a binary, the symbol table of the binary is stripped, so that an attacker cannot easily debug or reverse engineer an application.You can refer techniques used on GNU/Linux systems like sstriping or using UPX.

And at last you must be aware about obfuscation and tools like ProGuard.

Javascript switch vs. if...else if...else

The performance difference between a switch and if...else if...else is small, they basically do the same work. One difference between them that may make a difference is that the expression to test is only evaluated once in a switch while it's evaluated for each if. If it's costly to evaluate the expression, doing it one time is of course faster than doing it a hundred times.

The difference in implementation of those commands (and all script in general) differs quite a bit between browsers. It's common to see rather big performance differences for the same code in different browsers.

As you can hardly performance test all code in all browsers, you should go for the code that fits best for what you are doing, and try to reduce the amount of work done rather than optimising how it's done.

What are .dex files in Android?

dex file is a file that is executed on the Dalvik VM.

Dalvik VM includes several features for performance optimization, verification, and monitoring, one of which is Dalvik Executable (DEX).

Java source code is compiled by the Java compiler into .class files. Then the dx (dexer) tool, part of the Android SDK processes the .class files into a file format called DEX that contains Dalvik byte code. The dx tool eliminates all the redundant information that is present in the classes. In DEX all the classes of the application are packed into one file. The following table provides comparison between code sizes for JVM jar files and the files processed by the dex tool.

The table compares code sizes for system libraries, web browser applications, and a general purpose application (alarm clock app). In all cases dex tool reduced size of the code by more than 50%.

enter image description here

In standard Java environments each class in Java code results in one .class file. That means, if the Java source code file has one public class and two anonymous classes, let’s say for event handling, then the java compiler will create total three .class files.

The compilation step is same on the Android platform, thus resulting in multiple .class files. But after .class files are generated, the “dx” tool is used to convert all .class files into a single .dex, or Dalvik Executable, file. It is the .dex file that is executed on the Dalvik VM. The .dex file has been optimized for memory usage and the design is primarily driven by sharing of data.

How to HTML encode/escape a string? Is there a built-in?

Comparaison of the different methods:

> CGI::escapeHTML("quote ' double quotes \"")
=> "quote &#39; double quotes &quot;"

> Rack::Utils.escape_html("quote ' double quotes \"")
=> "quote &#x27; double quotes &quot;"

> ERB::Util.html_escape("quote ' double quotes \"")
=> "quote &#39; double quotes &quot;"

I wrote my own to be compatible with Rails ActiveMailer escaping:

def escape_html(str)
  CGI.escapeHTML(str).gsub("&#39;", "'")

Entity Framework - Generating Classes

  1. Open the EDMX model
  2. Right click -> Update Model from Browser -> Stored Procedure -> Select your stored procedure -> Finish
  3. See the Model Browser popping up next to Solution Explorer.
  4. Go to Function Imports -> Right click on your Stored Procedure -> Add Function Import
  5. Select the Entities under Return a Collection of -> Select your Entity name from the drop down
  6. Build your Solution.

Convert Pandas column containing NaNs to dtype `int`

I ran into this issue working with pyspark. As this is a python frontend for code running on a jvm, it requires type safety and using float instead of int is not an option. I worked around the issue by wrapping the pandas pd.read_csv in a function that will fill user-defined columns with user-defined fill values before casting them to the required type. Here is what I ended up using:

def custom_read_csv(file_path, custom_dtype = None, fill_values = None, **kwargs):
    if custom_dtype is None:
        return pd.read_csv(file_path, **kwargs)
        assert 'dtype' not in kwargs.keys()
        df = pd.read_csv(file_path, dtype = {}, **kwargs)
        for col, typ in custom_dtype.items():
            if fill_values is None or col not in fill_values.keys():
                fill_val = -1
                fill_val = fill_values[col]
            df[col] = df[col].fillna(fill_val).astype(typ)
    return df

Insert Data Into Temp Table with Query

This is possible. Try this way:

Create Global Temporary Table 
On Commit Preserve Rows 
select ArtistName, sum(Songs) As NumberOfSongs 
 from Spotfy 
    where ArtistName = 'BossaDoSamba'
 group by ArtistName;

Set variable in jinja

Nice shorthand for Multiple variable assignments

{% set label_cls, field_cls = "col-md-7", "col-md-3" %}

Fully change package name including company domain

The simplest way of doing this would be to rename the root app folder from com.example.MyApp to com.newcompanyname.MyNewAppName and then replace all occurrences of the old path to the new path in whatever IDE you're using.

How to change an Eclipse default project into a Java project

Depending on the Eclipse in question the required WTP packages may be found with different names. For example in Eclipse Luna I found it easiest to search with "Tools" and choose one that mentioned Tools for Java EE development. That added the project facet functionality. Searching with "WTP" wasn't of much help.

Angular 2 : No NgModule metadata found

I had this issue when i cloned from a git repository and I had it resolved when I created a new project and re-inserted the src folder from the old project.

The src folder is the only folder needed when deploying your angular application but you must reconfigure the dev environment, using this solution.

Rename multiple files in a directory in Python

Try this:

import os
import shutil

for file in os.listdir(dirpath):
    newfile = os.path.join(dirpath, file.split("_",1)[1])

I'm assuming you don't want to remove the file extension, but you can just do the same split with periods.

Python: How to ignore an exception and proceed?

There's a new way to do this coming in Python 3.4:

from contextlib import suppress

with suppress(Exception):
  # your code

Here's the commit that added it:

And here's the author, Raymond Hettinger, talking about this and all sorts of other Python hotness (relevant bit at 43:30):

If you wanted to emulate the bare except keyword and also ignore things like KeyboardInterrupt—though you usually don't—you could use with suppress(BaseException).

Edit: Looks like ignored was renamed to suppress before the 3.4 release.

What are NR and FNR and what does "NR==FNR" imply?

Look up NR and FNR in the awk manual and then ask yourself what is the condition under which NR==FNR in the following example:

$ cat file1

$ cat file2

$ awk '{print FILENAME, NR, FNR, $0}' file1 file2
file1 1 1 a
file1 2 2 b
file1 3 3 c
file2 4 1 d
file2 5 2 e

Hamcrest compare collections

To complement @Joe's answer:

Hamcrest provides you with three main methods to match a list:

contains Checks for matching all the elements taking in count the order, if the list has more or less elements, it will fail

containsInAnyOrder Checks for matching all the elements and it doesn't matter the order, if the list has more or less elements, will fail

hasItems Checks just for the specified objects it doesn't matter if the list has more

hasItem Checks just for one object it doesn't matter if the list has more

All of them can receive a list of objects and use equals method for comparation or can be mixed with other matchers like @borjab mentioned:

assertThat(myList , contains(allOf(hasProperty("id", is(7L)), 
                                   hasProperty("name", is("testName1")),
                                   hasProperty("description", is("testDesc1"))),
                             allOf(hasProperty("id", is(11L)), 
                                   hasProperty("name", is("testName2")),
                                   hasProperty("description", is("testDesc2")))));

Select a date from date picker using Selenium webdriver

Just do

  JavascriptExecutor js = (JavascriptExecutor)driver;

npm - "Can't find Python executable "python", you can set the PYTHON env variable."


Install all the required tools and configurations using Microsoft's windows-build-tools by running npm install -g windows-build-tools from an elevated PowerShell (run as Administrator).

Index Error: list index out of range (Python)

Generally it means that you are providing an index for which a list element does not exist.

E.g, if your list was [1, 3, 5, 7], and you asked for the element at index 10, you would be well out of bounds and receive an error, as only elements 0 through 3 exist.

How to calculate percentage when old value is ZERO

There is no rate of growth from 0 to any other number. That is to say, there is no percentage of increase from zero to greater than zero and there is no percentage of decrease from zero to less than zero (a negative number). What you have to decide is what to put as an output when this situation happens. Here are two possibilities I am comfortable with:

  1. Any time you have to show a rate of increase from zero, output the infinity symbol (8). That's Alt + 236 on your number pad, in case you're wondering. You could also use negative infinity (-8) for a negative growth rate from zero.
  2. Output a statement such as "[Increase/Decrease] From Zero" or something along those lines.

Unfortunately, if you need the growth rate for further calculations, the above options will not work, but, on the other hand, any number would give your following calculations incorrect data any way so the point is moot. You'd need to update your following calculations to account for this eventuality.

As an aside, the ((New-Old)/Old) function will not work when your new and old values are both zero. You should create an initial check to see if both values are zero and, if they are, output zero percent as the growth rate.

“Unable to find manifest signing certificate in the certificate store” - even when add new key

To sign an assembly with a strong name using attributes

Open AssemblyInfo.cs (in $(SolutionDir)\Properties)

the AssemblyKeyFileAttribute or the AssemblyKeyNameAttribute, specifying the name of the file or container that contains the key pair to use when signing the assembly with a strong name.

add the following code:


How to fetch JSON file in Angular 2


import { Injectable } from '@angular/core';
import { Http,Response} from '@angular/http';
import { Observable } from 'rxjs';
import 'rxjs/add/operator/map';

  providedIn: 'root'
export class ServiceService {
 private url="some URL";

constructor(private http:Http) { }     

//getData() is a method to fetch the data from web api or json file

          return this.http.get(this.url)


//In this component get the data using suscribe() and store it in local object as dataObject and display the data in display.component.html like {{dataObject .propertyName}}.

import { Component, OnInit } from '@angular/core';
import { ServiceService } from 'src/app/service.service';

  selector: 'app-display',
  templateUrl: './display.component.html',
  styleUrls: ['./display.component.css']
export class DisplayComponent implements OnInit {
      dataObject :any={};
constructor(private service:ServiceService) { }

  ngOnInit() {
      .subscribe(resData=>this.dataObject =resData)

Why would a " Connection timed out" exception occur when URL is up?

This can be a IPv6 problem (the host publishes an IPv6 AAAA-Address and the users host thinks it is configured for IPv6 but it is actually not correctly connected). This can also be a network MTU problem, a firewall block, or the target host might publish different IP addresses (randomly or based on originators country) which are not all reachable. Or similliar network problems.

You cant do much besides setting a timeout and adding good error messages (especially printing out the hosts' resolved address). If you want to make it more robust add retry, parallel trying of all addresses and also look into name resolution caching (positive and negative) on the Java platform.

How to parse a month name (string) to an integer for comparison in C#?

You could do something like this:

Convert.ToDate(month + " 01, 1900").Month

Adding an external directory to Tomcat classpath

You can create a new file, (or setenv.bat) inside tomcats bin directory and add following line there


How to add a constant column in a Spark DataFrame?

Spark 2.2+

Spark 2.2 introduces typedLit to support Seq, Map, and Tuples (SPARK-19254) and following calls should be supported (Scala):

import org.apache.spark.sql.functions.typedLit

df.withColumn("some_array", typedLit(Seq(1, 2, 3)))
df.withColumn("some_struct", typedLit(("foo", 1, 0.3)))
df.withColumn("some_map", typedLit(Map("key1" -> 1, "key2" -> 2)))

Spark 1.3+ (lit), 1.4+ (array, struct), 2.0+ (map):

The second argument for DataFrame.withColumn should be a Column so you have to use a literal:

from pyspark.sql.functions import lit

df.withColumn('new_column', lit(10))

If you need complex columns you can build these using blocks like array:

from pyspark.sql.functions import array, create_map, struct

df.withColumn("some_array", array(lit(1), lit(2), lit(3)))
df.withColumn("some_struct", struct(lit("foo"), lit(1), lit(.3)))
df.withColumn("some_map", create_map(lit("key1"), lit(1), lit("key2"), lit(2)))

Exactly the same methods can be used in Scala.

import org.apache.spark.sql.functions.{array, lit, map, struct}

df.withColumn("new_column", lit(10))
df.withColumn("map", map(lit("key1"), lit(1), lit("key2"), lit(2)))

To provide names for structs use either alias on each field:

    struct(lit("foo").alias("x"), lit(1).alias("y"), lit(0.3).alias("z"))

or cast on the whole object

    struct(lit("foo"), lit(1), lit(0.3)).cast("struct<x: string, y: integer, z: double>")

It is also possible, although slower, to use an UDF.


The same constructs can be used to pass constant arguments to UDFs or SQL functions.

JPA OneToMany and ManyToOne throw: Repeated column in mapping for entity column (should be mapped with insert="false" update="false")

You should never use the unidirectional @OneToMany annotation because:

  1. It generates inefficient SQL statements
  2. It creates an extra table which increases the memory footprint of your DB indexes

Now, in your first example, both sides are owning the association, and this is bad.

While the @JoinColumn would let the @OneToMany side in charge of the association, it's definitely not the best choice. Therefore, always use the mappedBy attribute on the @OneToMany side.

public class User{
    @OneToMany(fetch=FetchType.LAZY, cascade = CascadeType.ALL, mappedBy="user")
    public List<APost> aPosts;

    @OneToMany(fetch=FetchType.LAZY, cascade = CascadeType.ALL, mappedBy="user")
    public List<BPost> bPosts;

public class BPost extends Post {

    public User user;

public class APost extends Post {

     public User user;

Spark: Add column to dataframe conditionally

My bad, I had missed one part of the question.

Best, cleanest way is to use a UDF. Explanation within the code.

// create some example data...BY DataFrame
// note, third record has an empty string
case class Stuff(a:String,b:Int)
val d= sc.parallelize(Seq( ("a",1),("b",2),
     ("",3) ,("d",4)).map { x => Stuff(x._1,x._2)  }).toDF

// now the good stuff.
import org.apache.spark.sql.functions.udf
// function that returns 0 is string empty 
val func = udf( (s:String) => if(s.isEmpty) 0 else 1 )
// create new dataframe with added column named "notempty"
val r = $"a", $"b", func($"a").as("notempty") )

|  a|  b|notempty|
|  a|  1|    1111|
|  b|  2|    1111|
|   |  3|       0|
|  d|  4|    1111|

python error: no module named pylab

The error means pylab is not part of the standard Python libraries. You will need to down-load it and install it. I think it's available Here They have installation instructions here

How to select rows with NaN in particular column?

Try the following:


Missing `server' JVM (Java\jre7\bin\server\jvm.dll.)

To Fix The "Missing "server" JVM at C:\Program Files\Java\jre7\bin\server\jvm­­.dll, please install or use the JRE or JDK that contains these missing components.

Follow these steps:

Go to and install Java JRE7 (Check if Java 6 is not installed already)

After that, go to C:/Program files/java/jre7/bin

Here, create an folder called Server

Now go into the C:/Program files/java/jre7/bin/client folder

Copy all the data in this folder into the new C:/Program files/java/jre7/bin/Server folder

Can't import database through phpmyadmin file size too large

Here is what I've done:

  1. Gone to my XAMPP installed directoy C:\xampp\php
  2. Open the "Configuration Settings" file named php.ini using your text editor, preferably you can also you Notepad for Windows machine.
  3. Somewhere nearby on line no 886, please update it to upload_max_filesize = 128M
  4. Similarly on line no 735 post_max_size = 128M
  5. On line no 442 max_execution_time = 300
  6. On line no 452 max_input_time = 60
  7. Restart your Apache from either XAMPP Control Panel or using CMD in Windows


Iterate over a Javascript associative array in sorted order

var a = new Array();_x000D_
a['b'] = 1;_x000D_
a['z'] = 1;_x000D_
a['a'] = 1;_x000D_
var keys=Object.keys(a).sort();_x000D_
for(var i=0,key=keys[0];i<keys.length;key=keys[++i]){_x000D_
  document.write(key+' : '+a[key]+'<br>');_x000D_

Detect changed input text box

In my case, I had a textbox that was attached to a datepicker. The only solution that worked for me was to handle it inside the onSelect event of the datepicker.

<input type="text"  id="bookdate">

     onSelect: function (selected) {
         //handle change event here

Locate Git installation folder on Mac OS X

Is it in your PATH? If so just run which git in the terminal and it will tell you.

PHP Warning: Unknown: failed to open stream

Experienced the same error, for me it was caused because on my Mac I have changed the DocumentRoot to my users Sites directory.

To fix it, I ran the recursive command to ensure that the Apache service has read permissions.

sudo chmod -R 755 ~/Sites

How to create a .NET DateTime from ISO 8601 format

DateTime.ParseExact(...) allows you to tell the parser what each character represents.

Setting Timeout Value For .NET Web Service

After creating your client specifying the binding and endpoint address, you can assign an OperationTimeout,

client.InnerChannel.OperationTimeout = new TimeSpan(0, 5, 0);

jQuery scrollTop() doesn't seem to work in Safari or Chrome (Windows)

Works for Safari, Firefox, and IE7 (haven't tried IE8). Simple test:

<button onclick='$("body,html").scrollTop(0);'>  Top </button>

<button onclick='$("body,html").scrollTop(100);'> Middle </button>

<button onclick='$("body,html").scrollTop(250);'> Bottom </button>

Most examples use either one or both, but in reverse order (i.e., "html,body").


(And semantic purists out there, don't bust my chops -- I've been looking for this for weeks, this is a simple example, that validates XHTML strict. Feel free to create 27 layers of abstraction and event binding bloat for your OCD peace of mind. Just please give due credit, since the folks in the jQuery forums, SO, and the G couldn't cough up the goods. Peace out.)

Sending Email in Android using JavaMail API without using the default/built-in app

For sending a mail with attachment..

public class SendAttachment{
                    public static void main(String [] args){ 
             //to address
                    String to="[email protected]";//change accordingly
                    //from address
                    final String user="[email protected]";//change accordingly
                    final String password="password";//change accordingly 
                     MailcapCommandMap mc = (MailcapCommandMap) CommandMap.getDefaultCommandMap();
                   mc.addMailcap("text/html;; x-java-content-handler=com.sun.mail.handlers.text_html");
                  mc.addMailcap("text/xml;; x-java-content-handler=com.sun.mail.handlers.text_xml");
                  mc.addMailcap("text/plain;; x-java-content-handler=com.sun.mail.handlers.text_plain");
                  mc.addMailcap("multipart/*;; x-java-content-handler=com.sun.mail.handlers.multipart_mixed");
                  mc.addMailcap("message/rfc822;; x-java-content-handler=com.sun.mail.handlers.message_rfc822");
                  //1) get the session object   
                  Properties properties = System.getProperties();
                  properties.put("mail.smtp.port", "465"); 
                  properties.put("", "");
                    properties.put("mail.smtp.socketFactory.port", "465");
                    properties.put("mail.smtp.auth", "true");
                    properties.put("mail.smtp.port", "465");

                  Session session = Session.getDefaultInstance(properties,
                   new javax.mail.Authenticator() {
                   protected PasswordAuthentication getPasswordAuthentication() {
                   return new PasswordAuthentication(user,password);

                  //2) compose message   
                    MimeMessage message = new MimeMessage(session);
                    message.setFrom(new InternetAddress(user));
                    message.addRecipient(Message.RecipientType.TO,new InternetAddress(to));
                    //3) create MimeBodyPart object and set your message content    
                    BodyPart messageBodyPart1 = new MimeBodyPart();
                    messageBodyPart1.setText("How is This"); 
                    //4) create new MimeBodyPart object and set DataHandler object to this object    
                    MimeBodyPart messageBodyPart2 = new MimeBodyPart();
                //Location of file to be attached
                    String filename = Environment.getExternalStorageDirectory().getPath()+"/";//change accordingly
                    DataSource source = new FileDataSource(filename);
                    messageBodyPart2.setDataHandler(new DataHandler(source));
                    //5) create Multipart object and add MimeBodyPart objects to this object    
                    Multipart multipart = new MimeMultipart();
                    //6) set the multiplart object to the message object
                    message.setContent(multipart ); 
                    //7) send message 
                   System.out.println("MESSAGE SENT....");
                   }catch (MessagingException ex) {ex.printStackTrace();}

How can I kill all sessions connecting to my oracle database?

Additional info

Important Oracle 11g changes to alter session kill session

Oracle author Mladen Gogala notes that an @ sign is now required to kill a session when using the inst_id column:

alter system kill session '130,620,@1';

Input type "number" won't resize

Rather than set the length, set the max and min values for the number input.

The input box then resizes to fit the longest valid value.

If you want to allow a 3-digit number then set 999 as the max

 <input type="number" name="quantity" min="0" max="999">

Setting up and using Meld as your git difftool and mergetool

For Windows 10 I had to put this in my .gitconfig:

  tool = meld
[mergetool "meld"]
  cmd = 'C:/Program Files (x86)/Meld/Meld.exe' $LOCAL $BASE $REMOTE --output=$MERGED
  prompt = false

Everything else you need to know is written in this super answer by mattst further above.

PS: For some reason, this only worked with Meld 3.18.x, Meld 3.20.x gives me an error.

MongoError: connect ECONNREFUSED

You probably need to continue running your DB process (by running mongod) while running your node server.

How to get jSON response into variable from a jquery script

Look out for this pitfal:

Searched several houres before I found there were some linebreaks in the included files.

Play audio as microphone input

Just as there are printer drivers that do not connect to a printer at all but rather write to a PDF file, analogously there are virtual audio drivers available that do not connect to a physical microphone at all but can pipe input from other sources such as files or other programs.

I hope I'm not breaking any rules by recommending free/donation software, but VB-Audio Virtual Cable should let you create a pair of virtual input and output audio devices. Then you could play an MP3 into the virtual output device and then set the virtual input device as your "microphone". In theory I think that should work.

If all else fails, you could always roll your own virtual audio driver. Microsoft provides some sample code but unfortunately it is not applicable to the older Windows XP audio model. There is probably sample code available for XP too.

is there any way to force copy? copy without overwrite prompt, using windows?

MOVE /-Y Source Destination

Note:/-y will make the announcement of yes/no for overwrite

The SELECT permission was denied on the object 'Users', database 'XXX', schema 'dbo'

Using SSMS, I made sure the user had connect permissions on both the database and ReportServer.

On the specific database being queried, under properties, I mapped their credentials and enabled datareader and public permissions. Also, as others have stated-I made sure there were no denyread/denywrite boxes selected.

I did not want to enable db ownership when for their reports since they only needed to have select permissions.

How do I convert uint to int in C#?

Convert.ToInt32() takes uint as a value.

No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin '...' is therefore not allowed access

You need to add this at start of your php page "login.php"

<?php header('Access-Control-Allow-Origin: *'); ?>

How to finish current activity in Android

If you are doing a loading screen, just set the parameter to not keep it in activity stack. In your manifest.xml, where you define your activity do:

<activity android:name=".LoadingScreen" android:noHistory="true" ... />

And in your code there is no need to call .finish() anymore. Just do startActivity(i);

There is also no need to keep a instance of your current activity in a separate field. You can always access it like LoadingScreen.this.doSomething() instead of private LoadingScreen loadingScreen;

how to parse a "dd/mm/yyyy" or "dd-mm-yyyy" or "dd-mmm-yyyy" formatted date string using JavaScript or jQuery

Date.parse recognizes only specific formats, and you don't have the option of telling it what your input format is. In this case it thinks that the input is in the format mm/dd/yyyy, so the result is wrong.

To fix this, you need either to parse the input yourself (e.g. with String.split) and then manually construct a Date object, or use a more full-featured library such as datejs.

Example for manual parsing:

var input = $('#' + controlName).val();
var parts = str.split("/");
var d1 = new Date(Number(parts[2]), Number(parts[1]) - 1, Number(parts[0]));

Example using date.js:

var input = $('#' + controlName).val();
var d1 = Date.parseExact(input, "d/M/yyyy");

Working Copy Locked

I fixed it by deleting the hidden .svn folder and replaced it with the fresh checkout .svn and it worked. Probably this hidden folder got messed up!

Bitbucket fails to authenticate on git pull

You need to reset the password as shown below.

On macOS:

git config --global credential.helper osxkeychain

On Windows 10:

git config --global credential.helper store

After executing this, it prompts you for the user name and password for your repo.

Using current time in UTC as default value in PostgreSQL

Function already exists: timezone('UTC'::text, now())

How to get bitmap from a url in android?

Okay so you are trying to get a bitmap from a file? Title says URL. Anyways, when you are getting files from external storage in Android you should never use a direct path. Instead call getExternalStorageDirectory() like so:

File bitmapFile = new File(Environment.getExternalStorageDirectory() + "/" + PATH_TO_IMAGE);
Bitmap bitmap = BitmapFactory.decodeFile(bitmapFile);

getExternalStorageDirectory() gives you the path to the SD card. Also you need to declare the WRITE_EXTERNAL_STORAGE permission in the Manifest.

Common MySQL fields and their appropriate data types

Since you're going to be dealing with data of a variable length (names, email addresses), then you'd be wanting to use VARCHAR. The amount of space taken up by a VARCHAR field is [field length] + 1 bytes, up to max length 255, so I wouldn't worry too much about trying to find a perfect size. Take a look at what you'd imagine might be the longest length might be, then double it and set that as your VARCHAR limit. That said...:

I generally set email fields to be VARCHAR(100) - i haven't come up with a problem from that yet. Names I set to VARCHAR(50).

As the others have said, phone numbers and zip/postal codes are not actually numeric values, they're strings containing the digits 0-9 (and sometimes more!), and therefore you should treat them as a string. VARCHAR(20) should be well sufficient.

Note that if you were to store phone numbers as integers, many systems will assume that a number starting with 0 is an octal (base 8) number! Therefore, the perfectly valid phone number "0731602412" would get put into your database as the decimal number "124192010"!!

cocoapods - 'pod install' takes forever

I fixed this issue like that:

rm -fr ~/Library/Caches/CocoaPods && \
gem update --system && \
gem update && \
gem cleanup && \
pod setup


User GETDATE() to put current date into SQL variable

SELECT @LastChangeDate = GETDATE()

Git Pull is Not Possible, Unmerged Files

I got solved with git remove the unmerged file locally.

$ git rm <the unmerged file name>
$ git reset --hard
$ git pull --rebase
$ git rebase --skip
$ git pull
Already up-to-date.

When I send git commit afterward:

$ git commit . -m "my send commit"
On branch master
Your branch is up-to-date with 'origin/master'.
nothing to commit, working directory clean

Using CSS td width absolute, position

The reason it doesn't work in the link your provided is because you are trying to display a 300px column PLUS 52 columns the span 7 columns each. Shrink the number of columns and it works. You can't fit that many on the screen.

If you want to force the columns to fit try setting:

body {min-width:4150px;}

see my jsfiddle: @mike I can't comment yet.

How to change the icon of .bat file programmatically?

If you want an icon for a batch file, first create a link for the batch file as follows

Right click in window folder where you want the link select New -> Shortcut, then specify where the .bat file is.

This creates the .lnk file you wanted. Then you can specify an icon for the link, on its properties page.

Some nice icons are available here:


Note For me on Windows 10: %SystemRoot% == C:\Windows\

More Icons are here: C:\Windows\System32\imageres.dll

Also you might want to have the first line in the batch file to be "cd .." if you stash your batch files in a bat subdirectory one level below where your shortcuts, are supposed to execute.

Which is the default location for keystore/truststore of Java applications?

In Java, according to the JSSE Reference Guide, there is no default for the keystore, the default for the truststore is "jssecacerts, if it exists. Otherwise, cacerts".

A few applications use ~/.keystore as a default keystore, but this is not without problems (mainly because you might not want all the application run by the user to use that trust store).

I'd suggest using application-specific values that you bundle with your application instead, it would tend to be more applicable in general.

How can I escape a single quote?

You could use HTML entities:

  • &#39; for '
  • &#34; for "
  • ...

For more, you can take a look at Character entity references in HTML.

In MS DOS copying several files to one file

type data1.csv > combined.csv
type data2.csv >> combined.csv
type data3.csv >> combined.csv
type data4.csv >> combined.csv


Assume that your using files without headers and all files have the same columns.

How to permanently export a variable in Linux?

add the line to your .bashrc or .profile. The variables set in $HOME/.profile are active for the current user, the ones in /etc/profile are global. The .bashrc is pulled on each bash session start.

When to use <span> instead <p>?

A practical explanation: By default, <p> </p> will add line breaks before and after the enclosed text (so it creates a paragraph). <span> does not do this, that is why it is called inline.

Evaluate empty or null JSTL c tags

How can I validate if a String is null or empty using the c tags of JSTL?

You can use the empty keyword in a <c:if> for this:

<c:if test="${empty var1}">
    var1 is empty or null.
<c:if test="${not empty var1}">
    var1 is NOT empty or null.

Or the <c:choose>:

    <c:when test="${empty var1}">
        var1 is empty or null.
        var1 is NOT empty or null.

Or if you don't need to conditionally render a bunch of tags and thus you could only check it inside a tag attribute, then you can use the EL conditional operator ${condition? valueIfTrue : valueIfFalse}:

<c:out value="${empty var1 ? 'var1 is empty or null' : 'var1 is NOT empty or null'}" />

To learn more about those ${} things (the Expression Language, which is a separate subject from JSTL), check here.

See also:

How to center horizontal table-cell

Sometimes you have things other than text inside a table cell that you'd like to be horizontally centered. In order to do this, first set up some css...

    div.centered {
        margin: auto;
        width: 100%;
        display: flex;
        justify-content: center;

Then declare a div with class="centered" inside each table cell you want centered.

    <div class="centered">
        Anything: text, controls, etc... will be horizontally centered.

How to view data saved in android database(SQLite)?

If you are able to copy the actual SQLite database file to your desktop, you can use this tools to browse the data.

req.query and req.param in ExpressJS

req.query will return a JS object after the query string is parsed.

/user?name=tom&age=55 - req.query would yield {name:"tom", age: "55"}

req.params will return parameters in the matched route. If your route is /user/:id and you make a request to /user/5 - req.params would yield {id: "5"}

req.param is a function that peels parameters out of the request. All of this can be found here.


If the verb is a POST and you are using bodyParser, then you should be able to get the form body in you function with req.body. That will be the parsed JS version of the POSTed form.

How to get current PHP page name

You can use basename() and $_SERVER['PHP_SELF'] to get current page file name

echo basename($_SERVER['PHP_SELF']); /* Returns The Current PHP File Name */

How to use OAuth2RestTemplate?

My simple solution. IMHO it's the cleanest.

First create a application.yml

spring.main.allow-bean-definition-overriding: true

      clientId: XXX
      clientSecret: XXX
      accessTokenUri: XXX
      tokenName: access_token
      grant-type: client_credentials

Create the main class: Main

public class Main extends WebSecurityConfigurerAdapter {

    protected void configure(HttpSecurity http) throws Exception {

    public static void main(String[] args) {, args);

    public OAuth2RestTemplate oauth2RestTemplate(ClientCredentialsResourceDetails details) {
        return new OAuth2RestTemplate(details);


Then Create the controller class: Controller

class OfferController {

    private OAuth2RestOperations restOperations;

    @RequestMapping(value = "/<your url>"
            , method = RequestMethod.GET
            , produces = "application/json")
    public String foo() {
        ResponseEntity<String> responseEntity = restOperations.getForEntity(<the url you want to call on the server>, String.class);
        return responseEntity.getBody();

Maven dependencies


How to set the UITableView Section title programmatically (iPhone/iPad)?

Note that -(NSString *)tableView: titleForHeaderInSection: is not called by UITableView if - (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section is implemented in delegate of UITableView;