Programs & Examples On #Wcf interoperability

Changing upload_max_filesize on PHP

This can also be controlled with the apache configuration. Check the httpd.conf and/or .htaccess for something like the following:

php_value upload_max_filesize 10M

How to use SSH to run a local shell script on a remote machine?

Also, don't forget to escape variables if you want to pick them up from the destination host.

This has caught me out in the past.

For example:

user@host> ssh user2@host2 "echo \$HOME"

prints out /home/user2


user@host> ssh user2@host2 "echo $HOME"

prints out /home/user

Another example:

user@host> ssh user2@host2 "echo hello world | awk '{print \$1}'"

prints out "hello" correctly.

Convert a string to int using sql query

Starting with SQL Server 2012, you could use TRY_PARSE or TRY_CONVERT.

SELECT TRY_PARSE(MyVarcharCol as int)


Bootstrap 3 Glyphicons CDN

If you only want to have glyphicons icons without any additional css you can create a css file and put the code below and include it into main css file.

I have to create this extra file as link below was messing with my site styles too.


Instead to using it directly I created a css file bootstrap-glyphicons.css

@font-face{font-family:'Glyphicons Halflings';src:url('');src:url('') format('embedded-opentype'),url('') format('woff'),url('') format('truetype'),url('') format('svg');}.glyphicon{position:relative;top:1px;display:inline-block;font-family:'Glyphicons Halflings';font-style:normal;font-weight:normal;line-height:1;-webkit-font-smoothing:antialiased;}_x000D_

And imported the created css file into my main css file which enable me to just import the glyphicons only. Hope this help

@import url("bootstrap-glyphicons.css");

Composer: file_put_contents(./composer.json): failed to open stream: Permission denied

In my case, .composer was owned by root, so I did sudo rm -fr .composer and then my global require worked.

Be warned! You don't wanna use that command if you are not sure what you are doing.

Is it good practice to use the xor operator for boolean checks?

I find that I have similar conversations a lot. On the one hand, you have a compact, efficient method of achieving your goal. On the other hand, you have something that the rest of your team might not understand, making it hard to maintain in the future.

My general rule is to ask if the technique being used is something that it is reasonable to expect programmers in general to know. In this case, I think that it is reasonable to expect programmers to know how to use boolean operators, so using xor in an if statement is okay.

As an example of something that wouldn't be okay, take the trick of using xor to swap two variables without using a temporary variable. That is a trick that I wouldn't expect everybody to be familiar with, so it wouldn't pass code review.

Origin is not allowed by Access-Control-Allow-Origin

If you have an ASP.NET / ASP.NET MVC application, you can include this header via the Web.config file:


            <!-- Enable Cross Domain AJAX calls -->
            <remove name="Access-Control-Allow-Origin" />
            <add name="Access-Control-Allow-Origin" value="*" />

Role/Purpose of ContextLoaderListener in Spring?

It will give you point of hook to put some code that you wish to be executed on web application deploy time

Function Pointers in Java

Java8 has introduced lambdas and method references. So if your function matches a functional interface (you can create your own) you can use a method reference in this case.

Java provides a set of common functional interfaces. whereas you could do the following:

public class Test {
   public void test1(Integer i) {}
   public void test2(Integer i) {}
   public void consumer(Consumer<Integer> a) {
   public void provideConsumer() {
     consumer(this::test1);   // method reference
     consumer(x -> test2(x)); // lambda

How to solve maven 2.6 resource plugin dependency?

This issue is happening due to change of protocol from http to https for central repository. please refer following link for more details. 

In order to fix the problem, copy following into your file. This will set the repository url to use https.

            <name>Central Repository</name>
            <name>Central Repository</name>

How to post SOAP Request from PHP

PHP has SOAP support. Just call

$client = new SoapClient($url);

to connect to the SoapServer and then you can get list of functions and call functions simply by doing...


$result = $client->functionName();  

for more

SQL, Postgres OIDs, What are they and why are they useful?

OID's are still in use for Postgres with large objects (though some people would argue large objects are not generally useful anyway). They are also used extensively by system tables. They are used for instance by TOAST which stores larger than 8KB BYTEA's (etc.) off to a separate storage area (transparently) which is used by default by all tables. Their direct use associated with "normal" user tables is basically deprecated.

The oid type is currently implemented as an unsigned four-byte integer. Therefore, it is not large enough to provide database-wide uniqueness in large databases, or even in large individual tables. So, using a user-created table's OID column as a primary key is discouraged. OIDs are best used only for references to system tables.

Apparently the OID sequence "does" wrap if it exceeds 4B 6. So in essence it's a global counter that can wrap. If it does wrap, some slowdown may start occurring when it's used and "searched" for unique values, etc.

See also

IOException: The process cannot access the file 'file path' because it is being used by another process

I got this error because I was doing File.Move to a file path without a file name, need to specify the full path in the destination.

Excel VBA If cell.Value =... then

I think it would make more sense to use "Find" function in Excel instead of For Each loop. It works much much faster and it's designed for such actions. Try this:

 Sub FindSomeCells(strSearchQuery As String)   

    Set SearchRange = Worksheets("Sheet1").Range("A1:A100")
    FindWhat = strSearchQuery
    Set FoundCells = FindAll(SearchRange:=SearchRange, _
                            FindWhat:=FindWhat, _
                            LookIn:=xlValues, _
                            LookAt:=xlWhole, _
                            SearchOrder:=xlByColumns, _
                            MatchCase:=False, _
                            BeginsWith:=vbNullString, _
                            EndsWith:=vbNullString, _
    If FoundCells Is Nothing Then
        Debug.Print "Value Not Found"
        For Each FoundCell In FoundCells
            FoundCell.Interior.Color = XlRgbColor.rgbLightGreen
        Next FoundCell
    End If

End Sub

That subroutine searches for some string and returns a collections of cells fullfilling your search criteria. Then you can do whatever you want with the cells in that collection. Forgot to add the FindAll function definition:

Function FindAll(SearchRange As Range, _
                FindWhat As Variant, _
               Optional LookIn As XlFindLookIn = xlValues, _
                Optional LookAt As XlLookAt = xlWhole, _
                Optional SearchOrder As XlSearchOrder = xlByRows, _
                Optional MatchCase As Boolean = False, _
                Optional BeginsWith As String = vbNullString, _
                Optional EndsWith As String = vbNullString, _
                Optional BeginEndCompare As VbCompareMethod = vbTextCompare) As Range
' FindAll
' This searches the range specified by SearchRange and returns a Range object
' that contains all the cells in which FindWhat was found. The search parameters to
' this function have the same meaning and effect as they do with the
' Range.Find method. If the value was not found, the function return Nothing. If
' BeginsWith is not an empty string, only those cells that begin with BeginWith
' are included in the result. If EndsWith is not an empty string, only those cells
' that end with EndsWith are included in the result. Note that if a cell contains
' a single word that matches either BeginsWith or EndsWith, it is included in the
' result.  If BeginsWith or EndsWith is not an empty string, the LookAt parameter
' is automatically changed to xlPart. The tests for BeginsWith and EndsWith may be
' case-sensitive by setting BeginEndCompare to vbBinaryCompare. For case-insensitive
' comparisons, set BeginEndCompare to vbTextCompare. If this parameter is omitted,
' it defaults to vbTextCompare. The comparisons for BeginsWith and EndsWith are
' in an OR relationship. That is, if both BeginsWith and EndsWith are provided,
' a match if found if the text begins with BeginsWith OR the text ends with EndsWith.

Dim FoundCell As Range
Dim FirstFound As Range
Dim LastCell As Range
Dim ResultRange As Range
Dim XLookAt As XlLookAt
Dim Include As Boolean
Dim CompMode As VbCompareMethod
Dim Area As Range
Dim MaxRow As Long
Dim MaxCol As Long
Dim BeginB As Boolean
Dim EndB As Boolean
CompMode = BeginEndCompare
If BeginsWith <> vbNullString Or EndsWith <> vbNullString Then
    XLookAt = xlPart
    XLookAt = LookAt
End If
' this loop in Areas is to find the last cell
' of all the areas. That is, the cell whose row
' and column are greater than or equal to any cell
' in any Area.

For Each Area In SearchRange.Areas
    With Area
        If .Cells(.Cells.Count).Row > MaxRow Then
            MaxRow = .Cells(.Cells.Count).Row
        End If
        If .Cells(.Cells.Count).Column > MaxCol Then
            MaxCol = .Cells(.Cells.Count).Column
        End If
    End With
Next Area
Set LastCell = SearchRange.Worksheet.Cells(MaxRow, MaxCol)
On Error GoTo 0
Set FoundCell = SearchRange.Find(what:=FindWhat, _
        after:=LastCell, _
        LookIn:=LookIn, _
        LookAt:=XLookAt, _
        SearchOrder:=SearchOrder, _
If Not FoundCell Is Nothing Then
    Set FirstFound = FoundCell
    Do Until False ' Loop forever. We'll "Exit Do" when necessary.
        Include = False
        If BeginsWith = vbNullString And EndsWith = vbNullString Then
            Include = True
            If BeginsWith <> vbNullString Then
                If StrComp(Left(FoundCell.Text, Len(BeginsWith)), BeginsWith, BeginEndCompare) = 0 Then
                    Include = True
                End If
            End If
            If EndsWith <> vbNullString Then
                If StrComp(Right(FoundCell.Text, Len(EndsWith)), EndsWith, BeginEndCompare) = 0 Then
                    Include = True
                End If
            End If
        End If
        If Include = True Then
            If ResultRange Is Nothing Then
                Set ResultRange = FoundCell
                Set ResultRange = Application.Union(ResultRange, FoundCell)
            End If
        End If
        Set FoundCell = SearchRange.FindNext(after:=FoundCell)
        If (FoundCell Is Nothing) Then
            Exit Do
        End If
        If (FoundCell.Address = FirstFound.Address) Then
            Exit Do
        End If
End If
Set FindAll = ResultRange
End Function

How to inject window into a service?

Angular 4 introduce InjectToken, and they also create a token for document called DOCUMENT. I think this is the official solution and it works in AoT.

I use the same logic to create a small library called ngx-window-token to prevent doing this over and over.

I have used it in other project and build in AoT without issues.

Here is how I used it in other package

Here is the plunker

In your module

imports: [ BrowserModule, WindowTokenModule ] In your component

constructor(@Inject(WINDOW) _window) { }

React - How to force a function component to render?

This can be done without explicitly using hooks provided you add a prop to your component and a state to the stateless component's parent component:

const ParentComponent = props => {
  const [updateNow, setUpdateNow] = useState(true)

  const updateFunc = () => {

  const MyComponent = props => {
    return (<div> .... </div>)

  const MyButtonComponent = props => {
    return (<div> <input type="button" onClick={props.updateFunc} />.... </div>)

  return (
      <MyComponent updateMe={updateNow} />
      <MyButtonComponent updateFunc={updateFunc}/>

How to move the cursor word by word in the OS X Terminal

If you check Use option as meta key in the keyboard tab of the preferences, then the default emacs style commands for forward- and backward-word and ?F (Alt+F) and ?B (Alt+B) respectively.

I'd recommend reading From Bash to Z-Shell. If you want to increase your bash/zsh prowess!

htons() function in socket programing

htons is host-to-network short

This means it works on 16-bit short integers. i.e. 2 bytes.

This function swaps the endianness of a short.

Your number starts out at:

0001 0011 1000 1001 = 5001

When the endianness is changed, it swaps the two bytes:

1000 1001 0001 0011 = 35091

iterate through a map in javascript

An answer to your Question from 2019:

It depends on what version of ECMAScript you use.

Pre ES6:

Use any of the answers below, e.g.:

for (var m in myMap){
    for (var i=0;i<myMap[m].length;i++){
    ... do something with myMap[m][i] ...

For ES6 (ES 2015):

You should use a Map object, which has the entries() function:

var myMap = new Map();
myMap.set("0", "foo");
myMap.set(1, "bar");
myMap.set({}, "baz");

for (const [key, value] of myMap.entries()) {
  console.log(key, value);

For ES8 (ES 2017):

Object.entries() was introduced:

const object = {'a': 1, 'b': 2, 'c' : 3};
for (const [key, value] of Object.entries(object)) {
  console.log(key, value);

Arduino IDE can't find ESP8266WiFi.h file

When programming the NODEMCU card with the Arduino IDE, you need to customize it and you must have selected the correct card.

Open Arduino IDE and go to files and click on the preference in the Arduino IDE.

Add the following link to the Additional Manager URLS section: "" and press the OK button.

Then click Tools> Board Manager. Type "ESP8266" in the text box to search and install the ESP8266 software for Arduino IDE.

You will be successful when you try to program again by selecting the NodeMCU card after these operations. I hope I could help.

Default string initialization: NULL or Empty?

It depends on the situation. In most cases I use String.Empty because I don't want to be doing null checks every time I attempt to use a string. It makes the code a lot simpler and you are less likely to introduce unwanted NullReferenceException crashes.

I only set the string to null when I need to know if it has been set or not and where an empty string is something valid to set it to. In practice, I find these situations rare.

ListBox with ItemTemplate (and ScrollBar!)

ListBox will try to expand in height that is available.. When you set the Height property of ListBox you get a scrollviewer that actually works...

If you wish your ListBox to accodate the height available, you might want to try to regulate the Height from your parent controls.. In a Grid for example, setting the Height to Auto in your RowDefinition might do the trick...


XDocument or XmlDocument

I believe that XDocument makes a lot more object creation calls. I suspect that for when you're handling a lot of XML documents, XMLDocument will be faster.

One place this happens is in managing scan data. Many scan tools output their data in XML (for obvious reasons). If you have to process a lot of these scan files, I think you'll have better performance with XMLDocument.

Node.js res.setHeader('content-type', 'text/javascript'); pushing the response javascript as file download

You can directly set the content type like below:

res.writeHead(200, {'Content-Type': 'text/plain'});

For reference go through the nodejs Docs link.

Is null check needed before calling instanceof?

No. Java literal null is not an instance of any class. Therefore it can not be an instanceof any class. instanceof will return either false or true therefore the <referenceVariable> instanceof <SomeClass> returns false when referenceVariable value is null.

Adjust icon size of Floating action button (fab)

There are three key XML attributes for custom FABs:

  • app:fabSize: Either "mini" (40dp), "normal"(56dp)(default) or "auto"
  • app:fabCustomSize: This will decide the overall FAB size.
  • app:maxImageSize: This will decide the icon size.



The FAB padding (the space between the icon and the background circle, aka ripple) is calculated implicitly by:

4-edge padding = (fabCustomSize - maxImageSize) / 2.0 = 16

Note that the margins of the fab can be set by the usual android:margin xml tag properties.

Unable to connect to SQL Express "Error: 26-Error Locating Server/Instance Specified)

I had a similar problem which was solved by going to the "SQL Server Configuration Manager" and making sure that the "SQL Server Browser" was configured to start automatically and was started.

I came across this solution in the answer of this forum post:

I hope this helps somebody out there.

How to reshape data from long to wide format

much easier way!

devtools::install_github("yikeshu0611/onetree") #install onetree package

widedata=reshape_toWide(data = dat1,id = "name",j = "numbers",value.var.prefix = "value")

        name     value1     value2     value3     value4
   firstName  0.3407997 -0.7033403 -0.3795377 -0.7460474
  secondName -0.8981073 -0.3347941 -0.5013782 -0.1745357

if you want to go back from wide to long, only change Wide to Long, and no changes in objects.

reshape_toLong(data = widedata,id = "name",j = "numbers",value.var.prefix = "value")

        name numbers      value
   firstName       1  0.3407997
  secondName       1 -0.8981073
   firstName       2 -0.7033403
  secondName       2 -0.3347941
   firstName       3 -0.3795377
  secondName       3 -0.5013782
   firstName       4 -0.7460474
  secondName       4 -0.1745357

Converting time stamps in excel to dates

The answer of @NeplatnyUdaj is right but consider that Excel want the function name in the set language, in my case German. Then you need to use "DATUM" instead of "DATE":


JavaScript string encryption and decryption?

crypt.subtle AES-GCM, self-contained, tested:

async function aesGcmEncrypt(plaintext, password)

async function aesGcmDecrypt(ciphertext, password)

Basic http file downloading and saving to disk in python?

Exotic Windows Solution

import subprocess"powershell Invoke-WebRequest {} -OutFile {}".format(your_url, filename), shell=True)

PHP - concatenate or directly insert variables in string

From the point of view of making thinks simple, readable, consistent and easy to understand (since performance doesn't matter here):

  • Using embedded vars in double quotes can lead to complex and confusing situations when you want to embed object properties, multidimentional arrays etc. That is, generally when reading embedded vars, you cannot be instantly 100% sure of the final behavior of what you are reading.

  • You frequently need add crutches such as {} and \, which IMO adds confusion and makes concatenation readability nearly equivalent, if not better.

  • As soon as you need to wrap a function call around the var, for example htmlspecialchars($var), you have to switch to concatenation.

  • AFAIK, you cannot embed constants.

In some specific cases, "double quotes with vars embedding" can be useful, but generally speaking, I would go for concatenation (using single or double quotes when convenient)

How to run SUDO command in WinSCP to transfer files from Windows to linux

Tagging this answer which helped me, might not answer the actual question

If you are using password instead of private key, please refer to this answer for tested working solution on Ubuntu 16.04.5 and 20.04.1

What's the best way to build a string of delimited items in Java?

You can generalize it, but there's no join in Java, as you well say.

This might work better.

public static String join(Iterable<? extends CharSequence> s, String delimiter) {
    Iterator<? extends CharSequence> iter = s.iterator();
    if (!iter.hasNext()) return "";
    StringBuilder buffer = new StringBuilder(;
    while (iter.hasNext()) buffer.append(delimiter).append(;
    return buffer.toString();

Get last 30 day records from today date in SQL Server

You can use DateDiff for this. The where clause in your query would look like:

where DATEDIFF(day,pdate,GETDATE()) < 31

Close popup window

Your web_window variable must have gone out of scope when you tried to close the window. Add this line into your _openpageview function to test:


Error sending json in POST to web API service

I had all my settings covered in the accepted answer. The problem I had was that I was trying to update the Entity Framework entity type "Task" like:

public IHttpActionResult Post(Task task)

What worked for me was to create my own entity "DTOTask" like:

public IHttpActionResult Post(DTOTask task)

Bulk Record Update with SQL

Your way is correct, and here is another way you can do it:

update      Table1
set         Description = t2.Description
from        Table1 t1
inner join  Table2 t2
on          t1.DescriptionID = t2.ID

The nested select is the long way of just doing a join.

How to convert .pfx file to keystore with private key?

If you work with JDK 1.5 or below the keytool utility will not have the -importkeystore option (see JDK 1.5 keytool documentation) and the solution by MikeD will be available only by transferring the .pfx on a machine with a newer JDK (1.6 or above).

Another option in JDK 1.5 or below (if you have Oracle WebLogic product), is to follow the instructions from this Oracle document: Using PFX and PEM Certificate Formats with Keystores. It describes the conversion into .pem format, how to extract certificates information from this textual format, and import it into .jks format with java utils.ImportPrivateKey utility (this is an utility included with WebLogic product).

Clear MySQL query cache without restarting server

according the documentation, this should do it...


Uncaught ReferenceError: jQuery is not defined

set this jquery min js

script src=""

in wp-admin/admin-header.php

How to put a UserControl into Visual Studio toolBox

I found that the user control must have a parameterless constructor or it won't show up in the list. at least that was true in vs2005.

Python 3 sort a dict by its values

To sort a dictionary and keep it functioning as a dictionary afterwards, you could use OrderedDict from the standard library.

If that's not what you need, then I encourage you to reconsider the sort functions that leave you with a list of tuples. What output did you want, if not an ordered list of key-value pairs (tuples)?

How to delete files/subfolders in a specific directory at the command prompt in Windows

Use Notepad to create a text document and copy/paste this:

rmdir /s/q "%temp%"
mkdir "%temp%"

Select Save As and file name:


Save as type: All files and click the Save button.

It works on any kind of account (administrator or a standard user). Just run it!

I use a temporary variable in this example, but you can use any other! PS: For Windows OS only!

How to fix: fatal error: openssl/opensslv.h: No such file or directory in RedHat 7

To fix this problem, you have to install OpenSSL development package, which is available in standard repositories of all modern Linux distributions.

To install OpenSSL development package on Debian, Ubuntu or their derivatives:

$ sudo apt-get install libssl-dev

To install OpenSSL development package on Fedora, CentOS or RHEL:

$ sudo yum install openssl-devel 

Edit : As @isapir has pointed out, for Fedora version>=22 use the DNF package manager :

dnf install openssl-devel

How do I turn a String into a InputStreamReader in java?

Are you trying to get a) Reader functionality out of InputStreamReader, or b) InputStream functionality out of InputStreamReader? You won't get b). InputStreamReader is not an InputStream.

The purpose of InputStreamReader is to take an InputStream - a source of bytes - and decode the bytes to chars in the form of a Reader. You already have your data as chars (your original String). Encoding your String into bytes and decoding the bytes back to chars would be a redundant operation.

If you are trying to get a Reader out of your source, use StringReader.

If you are trying to get an InputStream (which only gives you bytes), use apache commons IOUtils.toInputStream(..) as suggested by other answers here.

How to set xlim and ylim for a subplot in matplotlib

You should use the OO interface to matplotlib, rather than the state machine interface. Almost all of the plt.* function are thin wrappers that basically do gca().*.

plt.subplot returns an axes object. Once you have a reference to the axes object you can plot directly to it, change its limits, etc.

import matplotlib.pyplot as plt

ax1 = plt.subplot(131)
ax1.scatter([1, 2], [3, 4])
ax1.set_xlim([0, 5])
ax1.set_ylim([0, 5])

ax2 = plt.subplot(132)
ax2.scatter([1, 2],[3, 4])
ax2.set_xlim([0, 5])
ax2.set_ylim([0, 5])

and so on for as many axes as you want.

or better, wrap it all up in a loop:

import matplotlib.pyplot as plt

DATA_x = ([1, 2],
          [2, 3],
          [3, 4])

DATA_y = DATA_x[::-1]

XLIMS = [[0, 10]] * 3
YLIMS = [[0, 10]] * 3

for j, (x, y, xlim, ylim) in enumerate(zip(DATA_x, DATA_y, XLIMS, YLIMS)):
    ax = plt.subplot(1, 3, j + 1)
    ax.scatter(x, y)

Matplotlib connect scatterplot points with line - Python

In addition to what provided in the other answers, the keyword "zorder" allows one to decide the order in which different objects are plotted vertically. E.g.:


plots the scatter symbols on top of the line, while


plots the line over the scatter symbols.

See, e.g., the zorder demo

What is the meaning of the word logits in TensorFlow?


In context of deep learning the logits layer means the layer that feeds in to softmax (or other such normalization). The output of the softmax are the probabilities for the classification task and its input is logits layer. The logits layer typically produces values from -infinity to +infinity and the softmax layer transforms it to values from 0 to 1.

Historical Context

Where does this term comes from? In 1930s and 40s, several people were trying to adapt linear regression to the problem of predicting probabilities. However linear regression produces output from -infinity to +infinity while for probabilities our desired output is 0 to 1. One way to do this is by somehow mapping the probabilities 0 to 1 to -infinity to +infinity and then use linear regression as usual. One such mapping is cumulative normal distribution that was used by Chester Ittner Bliss in 1934 and he called this "probit" model, short for "probability unit". However this function is computationally expensive while lacking some of the desirable properties for multi-class classification. In 1944 Joseph Berkson used the function log(p/(1-p)) to do this mapping and called it logit, short for "logistic unit". The term logistic regression derived from this as well.

The Confusion

Unfortunately the term logits is abused in deep learning. From pure mathematical perspective logit is a function that performs above mapping. In deep learning people started calling the layer "logits layer" that feeds in to logit function. Then people started calling the output values of this layer "logit" creating the confusion with logit the function.

TensorFlow Code

Unfortunately TensorFlow code further adds in to confusion by names like tf.nn.softmax_cross_entropy_with_logits. What does logits mean here? It just means the input of the function is supposed to be the output of last neuron layer as described above. The _with_logits suffix is redundant, confusing and pointless. Functions should be named without regards to such very specific contexts because they are simply mathematical operations that can be performed on values derived from many other domains. In fact TensorFlow has another similar function sparse_softmax_cross_entropy where they fortunately forgot to add _with_logits suffix creating inconsistency and adding in to confusion. PyTorch on the other hand simply names its function without these kind of suffixes.


The Logit/Probit lecture slides is one of the best resource to understand logit. I have also updated Wikipedia article with some of above information.

Fixing npm path in Windows 8 and 10

change the path for nodejs in environment varibale.

setting environment variable

How to tell 'PowerShell' Copy-Item to unconditionally copy files

From the documentation (help copy-item -full):

-force <SwitchParameter>
    Allows cmdlet to override restrictions such as renaming existing files as long as security is not compromised.

    Required?                    false
    Position?                    named
    Default value                False
    Accept pipeline input?       false
    Accept wildcard characters?  false

How exactly does <script defer="defer"> work?

The defer attribute is a boolean attribute.

When present, it specifies that the script is executed when the page has finished parsing.

Note: The defer attribute is only for external scripts (should only be used if the src attribute is present).

Note: There are several ways an external script can be executed:

If async is present: The script is executed asynchronously with the rest of the page (the script will be executed while the page continues the parsing) If async is not present and defer is present: The script is executed when the page has finished parsing If neither async or defer is present: The script is fetched and executed immediately, before the browser continues parsing the page

Get name of currently executing test in JUnit 4

JUnit 4.9.x and higher

Since JUnit 4.9, the TestWatchman class has been deprecated in favour of the TestWatcher class, which has invocation:

public TestRule watcher = new TestWatcher() {
   protected void starting(Description description) {
      System.out.println("Starting test: " + description.getMethodName());

Note: The containing class must be declared public.

JUnit 4.7.x - 4.8.x

The following approach will print method names for all tests in a class:

public MethodRule watchman = new TestWatchman() {
   public void starting(FrameworkMethod method) {
      System.out.println("Starting test: " + method.getName());

Should switch statements always contain a default clause?

You should have a default to catch un-expected values coming in.

However, I disagree with the Adrian Smith that your error message for default should be something totally meaningless. There may be an un-handled case you didn't forsee (which is kind of the point) that your user will end up seeing and a message like "unreachable" is entirely pointless and doesn't help anyone in that situation.

Case in point, how many times have you had an utterly meaningless BSOD? Or a fatal exception @ 0x352FBB3C32342?

Insert current date in datetime format mySQL

It depends on what datatype you set for your db table.

DATETIME (datatype)

INSERT INTO t1 (dateposted) VALUES ( NOW() )
// This will insert date and time into the col. Do not use quote around the val
$dt = date('Y-m-d h:i:s');
INSERT INTO t1 (dateposted) VALUES ( '$dt' )
// This will insert date into the col using php var. Wrap with quote.

DATE (datatype)

INSERT INTO t1 (dateposted) VALUES ( NOW() )
// Yes, you use the same NOW() without the quotes.
// Because your datatype is set to DATE it will insert only the date
$dt = date('Y-m-d');
INSERT INTO t1 (dateposted) VALUES ( '$dt' )
// This will insert date into the col using php var.

TIME (datatype)

INSERT INTO t1 (dateposted) VALUES ( NOW() )
// Yes, you use the same NOW() as well. 
// Because your datatype is set to TIME it will insert only the time
$dt = date('h:i:s');
INSERT INTO t1 (dateposted) VALUES ( '$dt' )
// This will insert time.

How to export JavaScript array info to csv (on client side)?

Download CSV File

  let csvContent = "data:text/csv;charset=utf-8,";
  rows.forEach(function (rowArray) {
    for (var i = 0, len = rowArray.length; i < len; i++) {
      if (typeof (rowArray[i]) == 'string')
        rowArray[i] = rowArray[i].replace(/<(?:.|\n)*?>/gm, '');
      rowArray[i] = rowArray[i].replace(/,/g, '');

    let row = rowArray.join(",");
    csvContent += row + "\r\n"; // add carriage return
  var encodedUri = encodeURI(csvContent);
  var link = document.createElement("a");
  link.setAttribute("href", encodedUri);
  link.setAttribute("download", "fileName.csv");

See line breaks and carriage returns in editor

I suggest you to edit your .vimrc file, for running a list of commands. Edit your .vimrc file, like this :

cat >> ~/.vimrc <<EOF
set ffs=unix
set encoding=utf-8
set fileencoding=utf-8
set listchars=eol:¶
set list

When you're executing vim, the commands into .vimrc are executed, and you can see this example :

My line with CRLF eol here ^M¶

How to represent matrices in python

Take a look at this answer:

from numpy import matrix
from numpy import linalg
A = matrix( [[1,2,3],[11,12,13],[21,22,23]]) # Creates a matrix.
x = matrix( [[1],[2],[3]] )                  # Creates a matrix (like a column vector).
y = matrix( [[1,2,3]] )                      # Creates a matrix (like a row vector).
print A.T                                    # Transpose of A.
print A*x                                    # Matrix multiplication of A and x.
print A.I                                    # Inverse of A.
print linalg.solve(A, x)     # Solve the linear equation system.

How to know if two arrays have the same values

Try this

function arraysEqual(arr1, arr2){
    if (!Array.isArray(arr1) || !Array.isArray(arr2) || arr1.length!=arr2.length)
        return false;

    return arr1.length==arr1.filter(word => arr2.includes(word)).length;

How to randomize (shuffle) a JavaScript array?

Though there are a number of implementations already advised but I feel we can make it shorter and easier using forEach loop, so we don't need to worry about calculating array length and also we can safely avoid using a temporary variable.

var myArr = ["a", "b", "c", "d"];

myArr.forEach((val, key) => {
  randomIndex = Math.ceil(Math.random()*(key + 1));
  myArr[key] = myArr[randomIndex];
  myArr[randomIndex] = val;
// see the values
console.log('Shuffled Array: ', myArr)

How set background drawable programmatically in Android

I'm using a minSdkVersion 16 and targetSdkVersion 23.
The following is working for me, it uses

ContextCompat.getDrawable(context, R.drawable.drawable);

Instead of using:


Rather use:

layout.setBackground(ContextCompat.getDrawable(this, R.drawable.ready));

getActivity() is used in a fragment, if calling from a activity use this.

How to move an element into another element?

I noticed huge memory leak & performance difference between insertAfter & after or insertBefore & before .. If you have tons of DOM elements, or you need to use after() or before() inside a MouseMove event, the browser memory will probably increase and next operations will run really slow.

The solution I've just experienced is to use inserBefore instead before() and insertAfter instead after().

How to scroll to bottom in a ScrollView on activity startup

Put the following code after your data is added:

final ScrollView scrollview = ((ScrollView) findViewById(; Runnable() {
    public void run() {


We had the same problem on a CentOS7 machine. Disabling the VERIFYHOST VERIFYPEER did not solve the problem, we did not have the cURL error anymore but the response still was invalid. Doing a wget to the same link as the cURL was doing also resulted in a certificate error.

-> Our solution also was to reboot the VPS, this solved it and we were able to complete the request again.

For us this seemed to be a memory corruption problem. Rebooting the VPS reloaded the libary in the memory again and now it works. So if the above solution from @clover does not work try to reboot your machine.

Regular Expression to select everything before and up to a particular text

After executing the below regex, your answer is in the first capture.


checked = "checked" vs checked = true

document.getElementById('myRadio') returns you the DOM element, i'll reference it as elem in this answer.

elem.checked accesses the property named checked of the DOM element. This property is always a boolean.

When writing HTML you use checked="checked" in XHTML; in HTML you can simply use checked. When setting the attribute (this is done via .setAttribute('checked', 'checked')) you need to provide a value since some browsers consider an empty value being non-existent.

However, since you have the DOM element you have no reason to set the attribute since you can simply use the - much more comfortable - boolean property for it. Since non-empty strings are considered true in a boolean context, setting elem.checked to 'checked' or anything else that is not a falsy value (even 'false' or '0') will check the checkbox. There is not reason not to use true and false though so you should stick with the proper values.

Regular expression to get a string between two strings in Javascript

Here's a regex which will grab what's between cow and milk (without leading/trailing space):

srctext = "My cow always gives milk.";
var re = /(.*cow\s+)(.*)(\s+milk.*)/;
var newtext = srctext.replace(re, "$2");

An example:

"Submit is not a function" error in JavaScript

submit is not a function

means that you named your submit button or some other element submit. Rename the button to btnSubmit and your call will magically work.

When you name the button submit, you override the submit() function on the form.

How to access the GET parameters after "?" in Express?

So, after checking out the express reference, I found that req.query.color would return me the value I'm looking for.

req.params refers to items with a ':' in the URL and req.query refers to items associated with the '?'


GET /something?color1=red&color2=blue

Then in express, the handler:

app.get('/something', (req, res) => {
    req.query.color1 === 'red'  // true
    req.query.color2 === 'blue' // true

How to change line width in ggplot?

Whilst @Didzis has the correct answer, I will expand on a few points

Aesthetics can be set or mapped within a ggplot call.

  • An aesthetic defined within aes(...) is mapped from the data, and a legend created.

  • An aesthetic may also be set to a single value, by defining it outside aes().

As far as I can tell, what you want is to set size to a single value, not map within the call to aes()

When you call aes(size = 2) it creates a variable called `2` and uses that to create the size, mapping it from a constant value as it is within a call to aes (thus it appears in your legend).

Using size = 1 (and without reg_labeller which is perhaps defined somewhere in your script)

Figure29 +
    geom_line(aes(group=factor(tradlib)),size=1) +
    facet_grid(regionsFull~., scales="free_y") +
    scale_colour_brewer(type = "div") +
    theme(axis.text.x = element_text(
          colour = 'black', angle = 90, size = 13,
          hjust = 0.5, vjust = 0.5),axis.title.x=element_blank()) +
    ylab("FSI (%Change)") +
    theme(axis.text.y = element_text(colour = 'black', size = 12), 
          axis.title.y = element_text(size = 12, 
          hjust = 0.5, vjust = 0.2)) + 
    theme(strip.text.y = element_text(size = 11, hjust = 0.5,
          vjust =    0.5, face = 'bold'))

enter image description here

and with size = 2

 Figure29 + 
     geom_line(aes(group=factor(tradlib)),size=2) +
     facet_grid(regionsFull~., scales="free_y") + 
     scale_colour_brewer(type = "div") +
     theme(axis.text.x = element_text(colour = 'black', angle = 90,
          size = 13, hjust = 0.5, vjust = 
          0.5),axis.title.x=element_blank()) + 
     ylab("FSI (%Change)") +
     theme(axis.text.y = element_text(colour = 'black', size = 12),
          axis.title.y = element_text(size = 12,
          hjust = 0.5, vjust = 0.2)) + 
      theme(strip.text.y = element_text(size = 11, hjust = 0.5,
          vjust = 0.5, face = 'bold'))

enter image description here

You can now define the size to work appropriately with the final image size and device type.

how do you filter pandas dataframes by multiple columns

Start from pandas 0.13, this is the most efficient way.

df.query('Gender=="Male" & Year=="2014" ')

Neither BindingResult nor plain target object for bean name available as request attr

Make sure that your Spring form mentions the modelAttribute="<Model Name".


public class GreetingController {

 public Greeting getGreetingObject() {
  return new Greeting();

  * GET
 @RequestMapping(method = RequestMethod.GET)
 public String handleRequest() {
  return "greeting";

  * POST
 @RequestMapping(method = RequestMethod.POST)
 public ModelAndView processSubmit(@ModelAttribute("greeting") Greeting greeting, BindingResult result){
  ModelAndView mv = new ModelAndView();
  mv.addObject("greeting", greeting);  
  return mv;

In your JSP :

<form:form  modelAttribute="greeting" method="POST" action="greeting.html">

how to call a method in another Activity from Activity

The startActivityForResult pattern is much better suited for what you're trying to achieve :

Try below code

public class MainActivity extends Activity {  

    Button button1;  
    protected void onCreate(Bundle savedInstanceState) {  
        button1.setOnClickListener(new OnClickListener() {  
            public void onClick(View arg0) {  
                Intent intent=new Intent(MainActivity.this,SecondActivity.class);  
                startActivityForResult(intent, 2);// Activity is started with requestCode 2  
 // Call Back method  to get the Message form other Activity  
       protected void onActivityResult(int requestCode, int resultCode, Intent data)  
                 super.onActivityResult(requestCode, resultCode, data);  
                  // check if the request code is same as what is passed  here it is 2  
                          //do the things u wanted 



public class SecondActivity extends Activity {  

    Button button1;  
    protected void onCreate(Bundle savedInstanceState) {  

            button1.setOnClickListener(new OnClickListener() {  
                public void onClick(View arg0) {  
                    String message="hello ";  
                    Intent intent=new Intent();  
                    finish();//finishing activity  


Let me know if it helped...

How to use Visual Studio C++ Compiler?

In Visual Studio, you can't just open a .cpp file and expect it to run. You must create a project first, or open the .cpp in some existing project.

In your case, there is no project, so there is no project to build.

Go to File --> New --> Project --> Visual C++ --> Win32 Console Application. You can uncheck "create a directory for solution". On the next page, be sure to check "Empty project".

Then, You can add .cpp files you created outside the Visual Studio by right clicking in the Solution explorer on folder icon "Source" and Add->Existing Item.

Obviously You can create new .cpp this way too (Add --> New). The .cpp file will be created in your project directory.

Then you can press ctrl+F5 to compile without debugging and can see output on console window.

How to add a new row to datagridview programmatically

You can do:

DataGridViewRow row = (DataGridViewRow)yourDataGridView.Rows[0].Clone();
row.Cells[0].Value = "XYZ";
row.Cells[1].Value = 50.2;


DataGridViewRow row = (DataGridViewRow)yourDataGridView.Rows[0].Clone();
row.Cells["Column2"].Value = "XYZ";
row.Cells["Column6"].Value = 50.2;

Another way:

this.dataGridView1.Rows.Add("five", "six", "seven","eight");
this.dataGridView1.Rows.Insert(0, "one", "two", "three", "four");


ScrollIntoView() causing the whole page to move

i had the same problem, i fixed it by removing the transform:translateY CSS i placed on the footer of the page.

Android Studio Image Asset Launcher Icon Background Color

With "Asset Type" set to "Image", try setting the same image for the foreground and background layers, keeping the same "Resize" percentage.

What exactly does the .join() method do?

join() is for concatenating all list elements. For concatenating just two strings "+" would make more sense:

strid = repr(595)
print array.array('c', random.sample(string.ascii_letters, 20 - len(strid)))
    .tostring() + strid

AngularJS format JSON string output

If you want to format the JSON and also do some syntax highlighting, you can use the ng-prettyjson directive. See the npm package.

Here is how to use it: <pre pretty-json="jsonObject"></pre>

node.js require all files in a folder?

I'm using node modules copy-to module to create a single file to require all the files in our NodeJS-based system.

The code for our utility file looks like this:

 * Module dependencies.

var copy = require('copy-to');

In all of the files, most functions are written as exports, like so:

exports.function1 = function () { // function contents };
exports.function2 = function () { // function contents };
exports.function3 = function () { // function contents };

So, then to use any function from a file, you just call:

var utility = require('./utility');

var response = utility.function2(); // or whatever the name of the function is

Matplotlib make tick labels font size smaller

Alternatively, you can just do:

import matplotlib as mpl
label_size = 8
mpl.rcParams['xtick.labelsize'] = label_size 

Namespace for [DataContract]

I solved this problem by adding C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Runtime.Serialization.dll in the reference

Handle JSON Decode Error when nothing returned

If you don't mind importing the json module, then the best way to handle it is through json.JSONDecodeError (or json.decoder.JSONDecodeError as they are the same) as using default errors like ValueError could catch also other exceptions not necessarily connected to the json decode one.

from json.decoder import JSONDecodeError

    qByUser =
    qUserData = json.loads(qByUser).decode('utf-8')
    questionSubjs = qUserData["all"]["questions"]
except JSONDecodeError as e:
    # do whatever you want

//EDIT (Oct 2020):

As @Jacob Lee noted in the comment, there could be the basic common TypeError raised when the JSON object is not a str, bytes, or bytearray. Your question is about JSONDecodeError, but still it is worth mentioning here as a note; to handle also this situation, but differentiate between different issues, the following could be used:

from json.decoder import JSONDecodeError

    qByUser =
    qUserData = json.loads(qByUser).decode('utf-8')
    questionSubjs = qUserData["all"]["questions"]
except JSONDecodeError as e:
    # do whatever you want
except TypeError as e:
    # do whatever you want in this case

Why maven settings.xml file is not there?

The settings.xml file is not created by itself, you need to manually create it. Here is a sample:

  <settings xmlns=""

What is the difference between dynamic programming and greedy approach?

Difference between greedy method and dynamic programming are given below :

  1. Greedy method never reconsiders its choices whereas Dynamic programming may consider the previous state.

  2. Greedy algorithm is less efficient whereas Dynamic programming is more efficient.

  3. Greedy algorithm have a local choice of the sub-problems whereas Dynamic programming would solve the all sub-problems and then select one that would lead to an optimal solution.

  4. Greedy algorithm take decision in one time whereas Dynamic programming take decision at every stage.

Git:nothing added to commit but untracked files present

In case someone cares just about the error nothing added to commit but untracked files present (use "git add" to track) and not about Please move or remove them before you can merge.. You might have a look at the answers on Git - Won't add files?

There you find at least 2 good candidates for the issue in question here: that you either are in a subfolder or in a parent folder, but not in the actual repo folder. If you are in the directory one level too high, this will definitely raise that message "nothing added to commit…", see my answer in the link for details. I do not know if the same message occurs when you are in a subfolder, but it is likely. That could fit to your explanations.

What's the best three-way merge tool?

Just checked out P4merge since I heard about it in another blog article:

enter image description here

Very slick interface, and FREE! I've been a faithful Araxis Merge user, but considering this is free and awesome, I'd encourage you to check it out.

Use of "this" keyword in formal parameters for static methods in C#

"this" extends the next class in the parameter list

So in the method signature below "this" extends "String". Line is passed to the function as a normal argument to the method. public static string[] SplitCsvLine(this String line)

In the above example "this" class is extending the built in "String" class.

eslint: error Parsing error: The keyword 'const' is reserved

If using Visual Code one option is to add this to the settings.json file:

"eslint.options": {
    "useEslintrc": false,
    "parserOptions": {
        "ecmaVersion": 2017
    "env": {
        "es6": true

Adding placeholder text to textbox

Very effective solution here for WindowsForms TextBox control. (not sure about XAML).

This will work in Multliline mode also.

Probably it may be extended for other controls, like ComboBox control (not checked)

Can I call curl_setopt with CURLOPT_HTTPHEADER multiple times to set multiple headers?

Following what curl does internally for the request (via the method outlined in this answer to "Php - Debugging Curl") answers the question: No, it is not possible to use the curl_setopt call with CURLOPT_HTTPHEADER. The second call will overwrite the headers of the first call.

Instead the function needs to be called once with all headers:

$headers = array(
    'Content-type: application/xml',
    'Authorization: gfhjui',
curl_setopt($curlHandle, CURLOPT_HTTPHEADER, $headers);

Related (but different) questions are:

SQL query for finding records where count > 1

I wouldn't recommend the HAVING keyword for newbies, it is essentially for legacy purposes.

I am not clear on what is the key for this table (is it fully normalized, I wonder?), consequently I find it difficult to follow your specification:

I would like to find all records for all users that have more than one payment per day with the same account number... Additionally, there should be a filter than only counts the records whose ZIP code is different.

So I've taken a literal interpretation.

The following is more verbose but could be easier to understand and therefore maintain (I've used a CTE for the table PAYMENT_TALLIES but it could be a VIEW:

WITH PAYMENT_TALLIES (user_id, zip, tally)
      SELECT user_id, zip, COUNT(*) AS tally
          BY user_id, zip
               SELECT * 
                WHERE P.user_id = PT.user_id
                      AND PT.tally > 1

Does Java have a path joining method?


String path1 = "path1";
String path2 = "path2";

String joinedPath = new File(path1, path2).toString();

Using boolean values in C

Conditional expressions are considered to be true if they are non-zero, but the C standard requires that logical operators themselves return either 0 or 1.

@Tom: #define TRUE !FALSE is bad and is completely pointless. If the header file makes its way into compiled C++ code, then it can lead to problems:

void foo(bool flag);


int flag = TRUE;

Some compilers will generate a warning about the int => bool conversion. Sometimes people avoid this by doing:

foo(flag == TRUE);

to force the expression to be a C++ bool. But if you #define TRUE !FALSE, you end up with:

foo(flag == !0);

which ends up doing an int-to-bool comparison that can trigger the warning anyway.

UIView bottom border?

If you use constraints (and so don't have the frame sizes) then you can add a border view with the required constraints

// MARK: - Add a border to one side of a view

public enum BorderSide {
    case top, bottom, left, right

extension UIView {
    public func addBorder(side: BorderSide, color: UIColor, width: CGFloat) {
        let border = UIView()
        border.translatesAutoresizingMaskIntoConstraints = false
        border.backgroundColor = color

        let topConstraint = topAnchor.constraint(equalTo: border.topAnchor)
        let rightConstraint = trailingAnchor.constraint(equalTo: border.trailingAnchor)
        let bottomConstraint = bottomAnchor.constraint(equalTo: border.bottomAnchor)
        let leftConstraint = leadingAnchor.constraint(equalTo: border.leadingAnchor)
        let heightConstraint = border.heightAnchor.constraint(equalToConstant: width)
        let widthConstraint = border.widthAnchor.constraint(equalToConstant: width)

        switch side {
        case .top:
            NSLayoutConstraint.activate([leftConstraint, topConstraint, rightConstraint, heightConstraint])
        case .right:
            NSLayoutConstraint.activate([topConstraint, rightConstraint, bottomConstraint, widthConstraint])
        case .bottom:
            NSLayoutConstraint.activate([rightConstraint, bottomConstraint, leftConstraint, heightConstraint])
        case .left:
            NSLayoutConstraint.activate([bottomConstraint, leftConstraint, topConstraint, widthConstraint])

Then set it something like the below

myButton.addBorder(side: .left, color: UIColor.lightGray, width: 1)

(inspired by this answer)

error: No resource identifier found for attribute 'adSize' in package '' main.xml

I also faced the same problem, I was using GoogleAdMobAdsSDK-4.1.0.jar then I tried with GoogleAdMobAdsSDK-4.0.4.jar now it is working fine, It is problem with jar file as per my experience.

How to embed YouTube videos in PHP?

You can do this simple with Joomla. Let me assume a sample YouTube URL -

$youtubeUrl =  JUri::getInstance('');
$videoId = $youtubeUrl->getVar('v'); ?>

<iframe id="ytplayer" type="text/html" width="640" height="390"  src="<?php echo $videoId; ?>"  frameborder="0"/>

How can I check Drupal log files?

To view entries in Drupal's own internal log system (the watchdog database table), go to These can include Drupal-specific errors as well as general PHP or MySQL errors that have been thrown.

Use the watchdog() function to add an entry to this log from your own custom module.

When Drupal bootstraps it uses the PHP function set_error_handler() to set its own error handler for PHP errors. Therefore, whenever a PHP error occurs within Drupal it will be logged through the watchdog() call at admin/reports/dblog. If you look for PHP fatal errors, for example, in /var/log/apache/error.log and don't see them, this is why. Other errors, e.g. Apache errors, should still be logged in /var/log, or wherever you have it configured to log to.

How to write to the Output window in Visual Studio?

Use OutputDebugString instead of afxDump.


#define _TRACE_MAXLEN 500

#if _MSC_VER >= 1900
#define _PRINT_DEBUG_STRING(text) OutputDebugString(text)
#else // _MSC_VER >= 1900
#define _PRINT_DEBUG_STRING(text) afxDump << text
#endif // _MSC_VER >= 1900

void MyTrace(LPCTSTR sFormat, ...)
    TCHAR text[_TRACE_MAXLEN + 1];
    memset(text, 0, _TRACE_MAXLEN + 1);
    va_list args;
    va_start(args, sFormat);
    int n = _vsntprintf(text, _TRACE_MAXLEN, sFormat, args);
    if(n <= 0)

Fullscreen Activity in Android?

If your using AppCompat and ActionBarActivity, then use this


getting JRE system library unbound error in build path

I too faced the same issue. I followed the following steps to resolve my issue -

  • Right click on your project -> Properties
  • Select Java Build Path in the left menu
  • Select Libraries tab
  • Under the module path, select the troublesome JRE entry
  • Click on Edit button
  • Select Workspace default JRE.
  • Click on Finish button

If the above steps don't work for you, instead of Workspace default JRE, you can choose an Alternate JRE and give the path to the JRE that you want to point.

How do I call a specific Java method on a click/submit event of a specific button in JSP?

If you have web.xml then


<form action="${pageContext.request.contextPath}/myservlet" method="post">
    <input type="submit" name="button1" value="Button 1" />


        <display-name>Servlet Name</display-name>


public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("Write your code below");

FailedPreconditionError: Attempting to use uninitialized in Tensorflow

Tensorflow 2.0 Compatible Answer: In Tensorflow Version >= 2.0, the command for Initializing all the Variables if we use Graph Mode, to fix the FailedPreconditionError is shown below:


This is just a shortcut for variables_initializer(global_variables())

It returns an Op that initializes global variables in the graph.

How do I solve the "server DNS address could not be found" error on Windows 10?

There might be a problem with your DNS servers of the ISP. A computer by default uses the ISP's DNS servers. You can manually configure your DNS servers. It is free and usually better than your ISP.

  1. Go to Control Panel ? Network and Internet ? Network and Sharing Centre
  2. Click on Change Adapter settings.
  3. Right click on your connection icon (Wireless Network Connection or Local Area Connection) and select properties.
  4. Select Internet protocol version 4.
  5. Click on "Use the following DNS server address" and type either of the two DNS given below.

Google Public DNS

Preferred DNS server :
Alternate DNS server :


Preferred DNS server :
Alternate DNS server :

Slidedown and slideup layout with animation

This doesn't work for me, I want to to like jquery slideUp / slideDown function, I tried this code, but it only move the content wich stay at the same place after animation end, the view should have a 0dp height at start of slideDown and the view height (with wrap_content) after the end of the animation.

How to add a custom right-click menu to a webpage?

Simplest jump start function, create a context menu at the cursor position, that destroys itself on mouse leave.

oncontextmenu = (e) => {
  let menu = document.createElement("div") = "ctxmenu" = `top:${e.pageY-10}px;left:${e.pageX-40}px`
  menu.onmouseleave = () => ctxmenu.outerHTML = ''
  menu.innerHTML = "<p>Option1</p><p>Option2</p><p>Option3</p><p>Option4</p><p onclick='alert(`Thank you!`)'>Upvote</p>"
#ctxmenu {
  position: fixed;
  color: black;
  cursor: pointer;
  border: 1px black solid

#ctxmenu > p {
  padding: 0 1rem;
  margin: 0

#ctxmenu > p:hover {
  background: black;
  color: ghostwhite

Delete worksheet in Excel using VBA


Sub SheetKiller()
    Dim s As Worksheet, t As String
    Dim i As Long, K As Long
    K = Sheets.Count

    For i = K To 1 Step -1
        t = Sheets(i).Name
        If t = "ID Sheet" Or t = "Summary" Then
            Application.DisplayAlerts = False
            Application.DisplayAlerts = True
        End If
    Next i
End Sub


Because we are deleting, we run the loop backwards.

Vector of Vectors to create matrix

You have to initialize the vector of vectors to the appropriate size before accessing any elements. You can do it like this:

// assumes using std::vector for brevity
vector<vector<int>> matrix(RR, vector<int>(CC));

This creates a vector of RR size CC vectors, filled with 0.

TortoiseSVN icons not showing up under Windows 7

Changing the registry worked for me.

If its helpful to anyone, I initially prefixed "z_" to the entries in "ShellIconOverlayIdentifiers" that I wanted to move down. However that didn't seem to bring up the TortoiseSVN entries. It might be due to case sensitivity wherein lowercase "z" still precedes uppercase "T". Finally, prefixing with "Z_" instead did the trick.

Pull request vs Merge request

There is a subtle difference in terms of conflict management. In case of conflicts, a pull request in Github will result in a merge commit on the destination branch. In Gitlab, when a conflict is found, the modifications made will be on a merge commit on the source branch.


"GitLab resolves conflicts by creating a merge commit in the source branch that is not automatically merged into the target branch. This allows the merge commit to be reviewed and tested before the changes are merged, preventing unintended changes entering the target branch without review or breaking the build."

CUSTOM_ELEMENTS_SCHEMA added to NgModule.schemas still showing Error

Add the following under @NgModule({})in 'app.module.ts' :

import {CUSTOM_ELEMENTS_SCHEMA} from `@angular/core`;

and then

schemas: [

Your 'app.module.ts' should look like this:

import { NgModule, CUSTOM_ELEMENTS_SCHEMA } from '@angular/core';

  declarations: [],
  imports: [],
  providers: [],
  bootstrap: [AppComponent]

export class AppModule { }

Maven and Spring Boot - non resolvable parent pom - (Unknown host)

For anyone stumbling upon this question, I'll post the solution to a similar problem (same error message except for the uknown host part).

Since January 15, 2020 maven central no longer supports HTTP, in favour of HTTPS. Consequently, spring repositories switched to HTTPS as well

The solution is therefore to change the urls from to

Can not run Java Applets in Internet Explorer 11 using JRE 7u51

Try this. It worked for me.

Go to RUN and type gpedit.msc then completely disable Onedrive. Have you noticed that the problem only existed after the last large download from Microsoft? It contained this package. I also removed it from the Start menu.

This appears to be the cause of the issue. Something to do with downloading temporary files, which of course an applet is.

Once done everything went back to normal.

How can I switch language in google play?

Answer below the dotted line below is the original that's now outdated.

Here is the latest information ( Thank you @deadfish ):

add &hl=<language> like &hl=pl or &hl=en

example: or

All available languages and abbreviations can be looked up here:


To change the actual local market:

Basically the market is determined automatically based on your IP. You can change some local country settings from your Gmail account settings but still IP of the country you're browsing from is more important. To go around it you'd have to Proxy-cheat. Check out some ways/sites:

To do it from an Android phone you'd need to find an app. I don't have my Droid anymore but give this a try:

How do I add a new class to an element dynamically?

Short answer no :)

But you could just use the same CSS for the hover like so:

a:hover, .hoverclass {

Maybe if you explain why you need the class added, there may be a better solution?

Hide vertical scrollbar in <select> element

Change padding-bottom , i.e may be the simplest possible way .

How to use not contains() in xpath?

XPath queries are case sensitive. Having looked at your example (which, by the way, is awesome, nobody seems to provide examples anymore!), I can get the result you want just by changing "business", to "Business"


I have tested this by opening the XML file in Chrome, and using the Developer tools to execute that XPath queries, and it gave me just the Film category back.

What is object slicing?

These are all good answers. I would just like to add an execution example when passing objects by value vs by reference:

#include <iostream>

using namespace std;

// Base class
class A {
    A() {}
    A(const A& a) {
        cout << "'A' copy constructor" << endl;
    virtual void run() const { cout << "I am an 'A'" << endl; }

// Derived class
class B: public A {
    B():A() {}
    B(const B& a):A(a) {
        cout << "'B' copy constructor" << endl;
    virtual void run() const { cout << "I am a 'B'" << endl; }

void g(const A & a) {;

void h(const A a) {;

int main() {
    cout << "Call by reference" << endl;
    cout << endl << "Call by copy" << endl;

The output is:

Call by reference
I am a 'B'

Call by copy
'A' copy constructor
I am an 'A'

How to fit in an image inside span tag?

Try this.

<span style="padding-right:3px; padding-top: 3px; display:inline-block;">

<img class="manImg" src="images/ico_mandatory.gif"></img>


Understanding Chrome network log "Stalled" state

This comes from the official site of Chome-devtools and it helps. Here i quote:

  • Queuing If a request is queued it indicated that:
    • The request was postponed by the rendering engine because it's considered lower priority than critical resources (such as scripts/styles). This often happens with images.
    • The request was put on hold to wait for an unavailable TCP socket that's about to free up.
    • The request was put on hold because the browser only allows six TCP connections per origin on HTTP 1. Time spent making disk cache entries (typically very quick.)
  • Stalled/Blocking Time the request spent waiting before it could be sent. It can be waiting for any of the reasons described for Queueing. Additionally, this time is inclusive of any time spent in proxy negotiation.

Setting an image button in CSS - image:active

This is what worked for me.

<!DOCTYPE html> 
<form action="desired Link">
  <button>  <img src="desired image URL"/>


Define a struct inside a class in C++

Something like this:

class Class {
    // visibility will default to private unless you specify it
    struct Struct {
        //specify members here;

how to automatically scroll down a html page?

You can use two different techniques to achieve this.

The first one is with javascript: set the scrollTop property of the scrollable element (e.g. document.body.scrollTop = 1000;).

The second is setting the link to point to a specific id in the page e.g.

<a href="mypage.html#sectionOne">section one</a>

Then if in your target page you'll have that ID the page will be scrolled automatically.

Append text using StreamWriter

Also look at log4net, which makes logging to 1 or more event stores — whether it's the console, the Windows event log, a text file, a network pipe, a SQL database, etc. — pretty trivial. You can even filter stuff in its configuration, for instance, so that only log records of a particular severity (say ERROR or FATAL) from a single component or assembly are directed to a particular event store.

When should I use curly braces for ES6 import?

The curly braces are used only for import when export is named. If the export is default then curly braces are not used for import.

Shell script to capture Process ID and kill it if exist

Kill -9 PID

should be

kill -9 $PID

see the difference?

How to create a inset box-shadow only on one side?

This might not be the exact thing you are looking for, but you can create a very similar effect by using rgba in combination with linear-gradient:

  background: linear-gradient(rgba(0,0,0,.5) 0%, rgba(0,0,0,0) 30%);

This creates a linear-gradient from black with 50% opacity (rgba(0,0,0,.5)) to transparent (rgba(0,0,0,0)) which starts being competently transparent 30% from the top. You can play with those values to create your desired effect. You can have it on a different side by adding a deg-value (linear-gradient(90deg, rgba(0,0,0,.5) 0%, rgba(0,0,0,0) 30%)) or switching the colors around. If you want really complex shadows like different angles on different sides you could even start layering linear-gradient.

Here is a snippet to see it in action:

.box {_x000D_
  background: linear-gradient(rgba(0,0,0,.5) 0%, rgba(0,0,0,0) 30%);_x000D_
.text {_x000D_
  padding: 20px;_x000D_
<div class="box">_x000D_
  <div class="text">_x000D_
    Lorem ipsum ...._x000D_

Android: how do I check if activity is running?

This work if you don't have the same activity in foreground. If you open from notification don't work i made some adjustments and came with this:

public static boolean ativo = false;
public static int counter = 0;

protected void onCreate(Bundle savedInstanceState) {

protected void onStart() {
    ativo = true;

protected void onStop() {
    if (counter==1) ativo = false;

protected void onDestroy() {

That works for me with several activitys open at the same time.

How to enable C++11/C++0x support in Eclipse CDT?

For the latest (Juno) eclipse cdt the following worked for me, no need to declare __GXX_EXPERIMENTAL_CXX0X__ on myself. This works for the the CDT indexer and as parameter for the compiler:

"your project name" -> right click -> properties:

C/C++ General -> Preprocessor Include Paths, Macros etc. -> switch to the tab named "Providers":

  • for "Configuration" select "Release" (and afterwards "debug")

  • switch off all providers and just select "CDT GCC Built-in Compiler Settings"

  • uncheck "Share setting entries between projects (global provider)"

  • in the "Command to get compiler specs:" add "-std=c++11" without the quotes (may work with quotes too)

  • hit apply and close the options

  • rebuild the index

Now all the c++11 related stuff should be resolved correctly by the indexer.

win7 x64, latest official eclipse with cdt mingw-w64 gcc 4.7.2 from the mingwbuilds project on sourceforge

Determining the current foreground application from a background task or service

This is how I am checking if my app is in foreground. Note I am using AsyncTask as suggested by official Android documentation.`


    private class CheckIfForeground extends AsyncTask<Void, Void, Void> {
    protected Void doInBackground(Void... voids) {

        ActivityManager activityManager = (ActivityManager) mContext.getSystemService(Context.ACTIVITY_SERVICE);
        List<ActivityManager.RunningAppProcessInfo> appProcesses = activityManager.getRunningAppProcesses();
        for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {
            if (appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
                Log.i("Foreground App", appProcess.processName);

                if (mContext.getPackageName().equalsIgnoreCase(appProcess.processName)) {
                    Log.i(Constants.TAG, "foreground true:" + appProcess.processName);
                    foreground = true;
                    // close_app();
        Log.d(Constants.TAG, "foreground value:" + foreground);
        if (foreground) {
            foreground = false;
            Log.i(Constants.TAG, "Close App and start Activity:");

        } else {
            //if not foreground
            foreground = false;
            Log.i(Constants.TAG, "Close App");


        return null;

and execute AsyncTask like this. new CheckIfForeground().execute();

Difference between core and processor

CPU is a central processing unit. Since 2002 we have only single core processor i.e. we will only perform a single task or a program at a time.

For having multiple programs run at a time we have to use the multiple processor for executing multi processes at a time so we required another motherboard for that and that is very expensive.

So, Intel introduced the concept of hyper threading i.e. it will convert the single CPU into two virtual CPUs i.e we have two cores for our task. Now the CPU is single, but it is only pretending (masqueraded) that it has a dual CPU and performs multiple tasks. But having real multiple cores will be better than that so people develop making multi-core processor i.e. multiple processors on a single box i.e. grabbing a multiple CPU on single big CPU. I.e. multiple cores.

Repository Pattern Step by Step Explanation

As a summary, I would describe the wider impact of the repository pattern. It allows all of your code to use objects without having to know how the objects are persisted. All of the knowledge of persistence, including mapping from tables to objects, is safely contained in the repository.

Very often, you will find SQL queries scattered in the codebase and when you come to add a column to a table you have to search code files to try and find usages of a table. The impact of the change is far-reaching.

With the repository pattern, you would only need to change one object and one repository. The impact is very small.

Perhaps it would help to think about why you would use the repository pattern. Here are some reasons:

  • You have a single place to make changes to your data access

  • You have a single place responsible for a set of tables (usually)

  • It is easy to replace a repository with a fake implementation for testing - so you don't need to have a database available to your unit tests

There are other benefits too, for example, if you were using MySQL and wanted to switch to SQL Server - but I have never actually seen this in practice!

disable editing default value of text input

I don't think all the other answerers understood the question correctly. The question requires disabling editing part of the text. One solution I can think of is simulating a textbox with a fixed prefix which is not part of the textarea or input.

An example of this approach is:

<div style="border:1px solid gray; color:#999999; font-family:arial; font-size:10pt; width:200px; white-space:nowrap;">Default Notes<br/>
<textarea style="border:0px solid black;" cols="39" rows="5"></textarea></div>

The other approach, which I end up using is using JS and JQuery to simulate "Disable" feature. Example with pseudo-code (cannot be specific cause of legal issue):

  // disable existing notes by preventing keystroke
  document.getElementById("txtNotes").addEventListener('keydown', function (e) {
    if (cursorLocation < defaultNoteLength ) {

    // disable existing notes by preventing right click
    document.addEventListener('contextmenu', function (e) {
        if (cursorLocation < defaultNoteLength )

Thanks, Carsten, for mentioning that this question is old, but I found that the solution might help other people in the future.

How to get instance variables in Python?

built on dmark's answer to get the following, which is useful if you want the equiv of sprintf and hopefully will help someone...

def sprint(object):
    result = ''
    for i in [v for v in dir(object) if not callable(getattr(object, v)) and v[0] != '_']:
        result += '\n%s:' % i + str(getattr(object, i, ''))
    return result

Why Response.Redirect causes System.Threading.ThreadAbortException?

Here's the official line on the problem (I couldn't find the latest, but I don't think the situation has changed for later versions of .net)

There isn't anything to compare. Nothing to compare, branches are entirely different commit histories

I got this error message, because I was migrating an application from SVN to GitHub and it's not enough to invoke a git init in the location of the source code checked out from SVN, but you need to invoke a git svn clone in order to have all the commit history. This way the two source codes on GitHub will have a mutual history and I was able to open pull requests.

How do I remove a specific element from a JSONArray?

We can use iterator to filter out the array entries instead of creating a new  Array. 

'public static void removeNullsFrom(JSONArray array) throws JSONException {
                if (array != null) {
                    Iterator<Object> iterator = array.iterator();
                    while (iterator.hasNext()) {
                        Object o =;
                        if (o == null || o == JSONObject.NULL) {

Set the layout weight of a TextView programmatically

There is another way to do this. In case you need to set only one parameter, for example 'height':

TextView textView = (TextView)findViewById(;
ViewGroup.LayoutParams params = textView.getLayoutParams();
params.height = ViewGroup.LayoutParams.WRAP_CONTENT;

The equivalent of wrap_content and match_parent in flutter?

Use this line of codes inside the Column. For wrap_content : mainAxisSize: MainAxisSize.min For match_parent : mainAxisSize: MainAxisSize.max

How to replace special characters in a string?

You can get unicode for that junk character from charactermap tool in window pc and add \u e.g. \u00a9 for copyright symbol. Now you can use that string with that particular junk caharacter, don't remove any junk character but replace with proper unicode.

Extract file basename without path and extension in bash

Here is another (more complex) way of getting either the filename or extension, first use the rev command to invert the file path, cut from the first . and then invert the file path again, like this:

filename=`rev <<< "$1" | cut -d"." -f2- | rev`
fileext=`rev <<< "$1" | cut -d"." -f1 | rev`

How to set a variable to current date and date-1 in linux?


today="$(date '+%Y-%m-%d')"
yesterday="$(date -d yesterday '+%Y-%m-%d')"

"The Controls collection cannot be modified because the control contains code blocks"

In my case, I have replaced <%= %> with <%# %>, and it worked!

Detect rotation of Android phone in the browser with JavaScript

I had the same problem. I am using Phonegap and Jquery mobile, for Adroid devices. To resize properly I had to set a timeout:

$(window).bind('orientationchange',function(e) {

$(window).bind('resize',function(e) {

function fixOrientation() {

    setTimeout(function() {

        var windowWidth = window.innerWidth;



How to execute multiple commands in a single line

Googling gives me this:

Command A & Command B

Execute Command A, then execute Command B (no evaluation of anything)

Command A | Command B

Execute Command A, and redirect all its output into the input of Command B

Command A && Command B

Execute Command A, evaluate the errorlevel after running and if the exit code (errorlevel) is 0, only then execute Command B

Command A || Command B

Execute Command A, evaluate the exit code of this command and if it's anything but 0, only then execute Command B

What do >> and << mean in Python?

These are the shift operators

x << y Returns x with the bits shifted to the left by y places (and new bits on the right-hand-side are zeros). This is the same as multiplying x by 2**y.

x >> y Returns x with the bits shifted to the right by y places. This is the same as //'ing x by 2**y.

CSS - center two images in css side by side

Flexbox can do this with just two css rules on a surrounding div.

    display: flex;_x000D_
    justify-content: center;_x000D_
<div class="social-media">_x000D_
<a href="mailto:[email protected]">_x000D_
<img class="fblogo" border="0" alt="Mail" src=""/></a>_x000D_
<a href="" target="_blank">_x000D_
<img class="fblogo" border="0" alt="Facebook" src=""/></a>_x000D_


Okay, so if later on down the line the issue is that you have a query that's greater than the allowable size (which may happen if it keeps growing) you're going to have to break it into chunks and execute the string values. So, let's say you have a stored procedure like the following:

    @SQL VARCHAR(MAX) -- 2GB size limit as stated by Martin Smith
    -- Now, if the length is greater than some arbitrary value
    -- Let's say 2000 for this example
    -- Let's chunk it
    -- Let's also assume we won't allow anything larger than 8000 total
    DECLARE @len INT
    SELECT @len = LEN(@SQL)

    IF (@len > 8000)
        RAISERROR ('The query cannot be larger than 8000 characters total.',

    -- Let's declare our possible chunks
    DECLARE @Chunk1 VARCHAR(2000),
            @Chunk2 VARCHAR(2000),
            @Chunk3 VARCHAR(2000),
            @Chunk4 VARCHAR(2000)

    SELECT @Chunk1 = '',
           @Chunk2 = '',
           @Chunk3 = '',
           @Chunk4 = ''

    IF (@len > 2000)
        -- Let's set the right chunks
        -- We already know we need two chunks so let's set the first
        SELECT @Chunk1 = SUBSTRING(@SQL, 1, 2000)

        -- Let's see if we need three chunks
        IF (@len > 4000)
            SELECT @Chunk2 = SUBSTRING(@SQL, 2001, 2000)

            -- Let's see if we need four chunks
            IF (@len > 6000)
                SELECT @Chunk3 = SUBSTRING(@SQL, 4001, 2000)
                SELECT @Chunk4 = SUBSTRING(@SQL, 6001, (@len - 6001))
                SELECT @Chunk3 = SUBSTRING(@SQL, 4001, (@len - 4001))
            SELECT @Chunk2 = SUBSTRING(@SQL, 2001, (@len - 2001))

    -- Alright, now that we've broken it down, let's execute it
    EXEC (@Chunk1 + @Chunk2 + @Chunk3 + @Chunk4)

ng-if check if array is empty

In my experience, doing this on the HTML template proved difficult so I decided to use an event to call a function on TS and then check the condition. If true make condition equals to true and then use that variable on the ngIf on HTML

    emptyClause(array:any) {

        if (array.length === 0) {
            // array empty or does not exist





        <div class="row">

            <div class="col-md-1 col-sm-1 col-xs-1"></div>
            <div class="col-md-10 col-sm-10 col-xs-10">
        <div [hidden]="emptyMessage" class="alert alert-danger">

            No Clauses Have Been Identified For the Search Criteria

            <div class="col-md-1 col-sm-1 col-xs-1"></div>

How to open select file dialog via js?

Using jQuery

I would create a button and an invisible input like so:

<button id="button">Open</button>
<input id="file-input" type="file" name="name" style="display: none;" />

and add some jQuery to trigger it:

$('#button').on('click', function() {

Using Vanilla JS

Same idea, without jQuery (credits to @Pascale):

<button onclick="document.getElementById('file-input').click();">Open</button>
<input id="file-input" type="file" name="name" style="display: none;" />

Xcode 12, building for iOS Simulator, but linking in object file built for iOS, for architecture arm64

I believe I found the answer. Per the Xcode 12 beta 6 release notes:

"The Build Settings editor no longer includes the Valid Architectures build setting (VALID_ARCHS), and its use is discouraged. Instead, there is a new Excluded Architectures build setting (EXCLUDED_ARCHS). If a project includes VALID_ARCHS, the setting is displayed in the User-Defined section of the Build Settings editor. (15145028)"

I was able to resolve this issue by manually editing the project file (I could not figure out how to remove the item from the project file using Xcode) and removing all lines referring to VALID_ARCHS. After that, I am able to build for the simulator fine.

pandas: filter rows of DataFrame with operator chaining

If you set your columns to search as indexes, then you can use DataFrame.xs() to take a cross section. This is not as versatile as the query answers, but it might be useful in some situations.

import pandas as pd
import numpy as np

df = pd.DataFrame(
    np.random.randint(3, size=(10, 5)),

# Out[55]: 
#    A  B  C  D  E
# 0  0  2  2  2  2
# 1  1  1  2  0  2
# 2  0  2  0  0  2
# 3  0  2  2  0  1
# 4  0  1  1  2  0
# 5  0  0  0  1  2
# 6  1  0  1  1  1
# 7  0  0  2  0  2
# 8  2  2  2  2  2
# 9  1  2  0  2  1

df.set_index(['A', 'D']).xs([0, 2]).reset_index()
# Out[57]: 
#    A  D  B  C  E
# 0  0  2  2  2  2
# 1  0  2  1  1  0

The Eclipse executable launcher was unable to locate its companion launcher jar windows

Windows 8 follow these 3 steps:

  1. Locate eclipse file.
  2. create shortcut on desktop.
  3. Double click on the eclipse shortcut to open the application.

How can I run multiple curl requests processed sequentially?

This will do what you want, uses an input file and is super fast

lines=$(cat ${file})
for line in ${lines}; do
   curl "${line}"
exit ${?}

one entry per line on your input file, it will follow the order of your input file

save it as and make it executable

How to list only the file names that changed between two commits?

This will show the changes in files:

git diff --word-diff SHA1 SHA2

Disable keyboard on EditText

Just set:


or in the constructor:

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

String or binary data would be truncated. The statement has been terminated

Specify a size for the item and warehouse like in the [dbo].[testing1] FUNCTION

@trackingItems1 TABLE (
item       nvarchar(25)  NULL, -- 25 OR equal size of your item column
warehouse   nvarchar(25) NULL, -- same as above
price int   NULL


Since in MSSQL only saying only nvarchar is equal to nvarchar(1) hence the values of the column from the stock table are truncated

Manifest Merger failed with multiple errors in Android Studio

After seeing CLIFFORD's answer to see the error, what helped me to solve this issue was renaming 'android:namex' to 'android:name' in the intent-filter action tag. In case if the same solution helps someone else .

    <activity android:name=".MainActivity">
            <action android:namex="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />

Synchronizing a local Git repository with a remote one

You can use git hooks for that. Just create a hook that pushes changed to the other repo after an update.

Of course you might get merge conflicts so you have to figure how to deal with them.

Cannot find control with name: formControlName in angular reactive form

I tried to generate a form dynamically because the amount of questions depend on an object and for me the error was fixed when I added ngDefaultControl to my mat-form-field.

    <form [formGroup]="questionsForm">
        <ng-container *ngFor="let question of questions">
            <mat-form-field [formControlName]="" ngDefaultControl>
                <textarea matInput rows="3" required></textarea>
        <button mat-raised-button (click)="sendFeedback()">Submit all questions</button>

In sendFeedback() I get the value from my dynamic form by selecting the formgroup's value as such

  sendFeedbackAsAgent():void {
    if (this.questionsForm.valid) {

How can I add "href" attribute to a link dynamically using JavaScript?

document.getElementById('link-id').href = "new-href";

I know this is an old post, but here's a one-liner that might be more suitable for some folks.

Javascript Audio Play on click

That worked

<audio src="${ song.url }" id="audio"></audio>
<i class="glyphicon glyphicon-play-circle b-play" id="play" onclick="play()"></i>

    function play() {
        var audio = document.getElementById('audio');
        if (audio.paused) {
            audio.currentTime = 0

How to pass command line argument to gnuplot?

You could even do some shell magic, e.g. like this:

inputfile="${1}" #you could even do some getopt magic here...

## generate a gnuplotscript, strip off bash header
gnuplotscript=$(mktemp /tmp/gnuplot_cmd_$(basename "${0}").XXXXXX.gnuplot)

firstline=$(grep -m 1 -n "^#!/usr/bin/gnuplot" "${0}")
firstline=${firstline%%:*} #remove everything after the colon
sed -e "1,${firstline}d" < "${0}" > "${gnuplotscript}"

## run gnuplot
/usr/bin/gnuplot -e "inputfile=\"${inputfile}\"" "${gnuplotscript}"
if [[ ${status} -ne 0 ]] ; then
  echo "ERROR: gnuplot returned with exit status $?"

## cleanup and exit
rm -f "${gnuplotscript}"
exit ${status}

plot inputfile using 1:4 with linespoints
#... or whatever you want

My implementation is a bit more complex (e.g. replacing some magic tokens in the sed call, while I am already at it...), but I simplified this example for better understanding. You could also make it even simpler.... YMMV.

How to Auto resize HTML table cell to fit the text size

Well, me also I was struggling with this issue: this is how I solved it: apply table-layout: auto; to the <table> element.

Fail to create Android virtual Device, "No system image installed for this Target"

As a workaround, go to sdk installation directory and perform the following steps:

  • Navigate to system-images/android-19/default
  • Move everything in there to system-images/android-19/

The directory structure should look like this: enter image description here

And it should work!

How to create a new figure in MATLAB?



plot(something else);


Python 3 Float Decimal Points/Precision

Try this:

num = input("Please input your number: ")

num = float("%0.2f" % (num))


I believe this is a lot simpler. For 1 decimal place use %0.1f. For 2 decimal places use %0.2f and so on.

Or, if you want to reduce it all to 2 lines:

num = float("%0.2f" % (float(input("Please input your number: "))))

How do I write a Python dictionary to a csv file?

You are using DictWriter.writerows() which expects a list of dicts, not a dict. You want DictWriter.writerow() to write a single row.

You will also want to use DictWriter.writeheader() if you want a header for you csv file.

You also might want to check out the with statement for opening files. It's not only more pythonic and readable but handles closing for you, even when exceptions occur.

Example with these changes made:

import csv

my_dict = {"test": 1, "testing": 2}

with open('mycsvfile.csv', 'w') as f:  # You will need 'wb' mode in Python 2.x
    w = csv.DictWriter(f, my_dict.keys())

Which produces:


Excel - Combine multiple columns into one column

Function Concat(myRange As Range, Optional myDelimiter As String) As String 
  Dim r As Range 
  For Each r In myRange 
    If Len(r.Text) Then 
      Concat = Concat & IIf(Concat <> "", myDelimiter, "") & r.Text 
    End If 
End Function

How to run a .jar in mac?

You don't need JDK to run Java based programs. JDK is for development which stands for Java Development Kit.

You need JRE which should be there in Mac.

Try: java -jar Myjar_file.jar

EDIT: According to this article, for Mac OS 10

The Java runtime is no longer installed automatically as part of the OS installation.

Then, you need to install JRE to your machine.

Make TextBox uneditable

Use the ReadOnly property on the TextBox.

myTextBox.ReadOnly = true;

But Remember: TextBoxBase.ReadOnly Property

When this property is set to true, the contents of the control cannot be changed by the user at runtime. With this property set to true, you can still set the value of the Text property in code. You can use this feature instead of disabling the control with the Enabled property to allow the contents to be copied and ToolTips to be shown.

Blue and Purple Default links, how to remove?

<a href="https://www." style="color: inherit;"target="_blank">

For CSS inline style, this worked best for me.

Securing a password in a properties file

What about providing a custom N-Factor authentication mechanism?

Before combining available methods, let's assume we can perform the following:

1) Hard-code inside the Java program

2) Store in a .properties file

3) Ask user to type password from command line

4) Ask user to type password from a form

5) Ask user to load a password-file from command line or a form

6) Provide the password through network

7) many alternatives (eg Draw A Secret, Fingerprint, IP-specific, bla bla bla)

1st option: We could make things more complicated for an attacker by using obfuscation, but this is not considered a good countermeasure. A good coder can easily understand how it works if he/she can access the file. We could even export a per-user binary (or just the obfuscation part or key-part), so an attacker must have access to this user-specific file, not another distro. Again, we should find a way to change passwords, eg by recompiling or using reflection to on-the-fly change class behavior.

2nd option: We can store the password in the .properties file in an encrypted format, so it's not directly visible from an attacker (just like jasypt does). If we need a password manager we'll need a master password too which again should be stored somewhere - inside a .class file, the keystore, kernel, another file or even in memory - all have their pros and cons.
But, now users will just edit the .properties file for password change.

3rd option: type the password when running from command line e.g. java -jar /myprogram.jar -p sdflhjkiweHIUHIU8976hyd.

This doesn't require the password to be stored and will stay in memory. However, history commands and OS logs, may be your worst enemy here. To change passwords on-the-fly, you will need to implement some methods (eg listen for console inputs, RMI, sockets, REST bla bla bla), but the password will always stay in memory.

One can even temporarily decrypt it only when required -> then delete the decrypted, but always keep the encrypted password in memory. Unfortunately, the aforementioned method does not increase security against unauthorized in-memory access, because the person who achieves that, will probably have access to the algorithm, salt and any other secrets being used.

4th option: provide the password from a custom form, rather than the command line. This will circumvent the problem of logging exposure.

5th option: provide a file as a password stored previously on a another medium -> then hard delete file. This will again circumvent the problem of logging exposure, plus no typing is required that could be shoulder-surfing stolen. When a change is required, provide another file, then delete again.

6th option: again to avoid shoulder-surfing, one can implement an RMI method call, to provide the password (through an encrypted channel) from another device, eg via a mobile phone. However, you now need to protect your network channel and access to the other device.

I would choose a combination of the above methods to achieve maximum security so one would have to access the .class files, the property file, logs, network channel, shoulder surfing, man in the middle, other files bla bla bla. This can be easily implemented using a XOR operation between all sub_passwords to produce the actual password.

We can't be protected from unauthorized in-memory access though, this can only be achieved by using some access-restricted hardware (eg smartcards, HSMs, SGX), where everything is computed into them, without anyone, even the legitimate owner being able to access decryption keys or algorithms. Again, one can steal this hardware too, there are reported side-channel attacks that may help attackers in key extraction and in some cases you need to trust another party (eg with SGX you trust Intel). Of course, situation may worsen when secure-enclave cloning (de-assembling) will be possible, but I guess this will take some years to be practical.

Also, one may consider a key sharing solution where the full key is split between different servers. However, upon reconstruction, the full key can be stolen. The only way to mitigate the aforementioned issue is by secure multiparty computation.

We should always keep in mind that whatever the input method, we need to ensure we are not vulnerable from network sniffing (MITM attacks) and/or key-loggers.

Select a Dictionary<T1, T2> with LINQ

A more explicit option is to project collection to an IEnumerable of KeyValuePair and then convert it to a Dictionary.

Dictionary<int, string> dictionary = objects
    .Select(x=> new KeyValuePair<int, string>(x.Id, x.Name))
    .ToDictionary(x=>x.Key, x=>x.Value);

javascript filter array of objects

For those who want to filter from an array of objects using any key:

function filterItems(items, searchVal) {_x000D_
  return items.filter((item) => Object.values(item).includes(searchVal));_x000D_
let data = [_x000D_
  { "name": "apple", "type": "fruit", "id": 123234 },_x000D_
  { "name": "cat", "type": "animal", "id": 98989 },_x000D_
  { "name": "something", "type": "other", "id": 656565 }]_x000D_
console.log("Filtered by name: ", filterItems(data, "apple"));_x000D_
console.log("Filtered by type: ", filterItems(data, "animal"));_x000D_
console.log("Filtered by id: ", filterItems(data, 656565));

filter from an array of the JSON objects:**

What is the difference between Unidirectional and Bidirectional JPA and Hibernate associations?

The main differenece is that bidirectional relationship provides navigational access in both directions, so that you can access the other side without explicit queries. Also it allows you to apply cascading options to both directions.

Note that navigational access is not always good, especially for "one-to-very-many" and "many-to-very-many" relationships. Imagine a Group that contains thousands of Users:

  • How would you access them? With so many Users, you usually need to apply some filtering and/or pagination, so that you need to execute a query anyway (unless you use collection filtering, which looks like a hack for me). Some developers may tend to apply filtering in memory in such cases, which is obviously not good for performance. Note that having such a relationship can encourage this kind of developers to use it without considering performance implications.

  • How would you add new Users to the Group? Fortunately, Hibernate looks at the owning side of relationship when persisting it, so you can only set However, if you want to keep objects in memory consistent, you also need to add User to Group.users. But it would make Hibernate to fetch all elements of Group.users from the database!

So, I can't agree with the recommendation from the Best Practices. You need to design bidirectional relationships carefully, considering use cases (do you need navigational access in both directions?) and possible performance implications.

See also:

How do I access an access array item by index in handlebars?

If you want to use dynamic variables

This won't work:

{{#each obj[key]}}

You need to do:

{{#each (lookup obj key)}}

see handlebars lookup helper and handlebars subexpressions.

How do I query for all dates greater than a certain date in SQL Server?

To sum it all up, the correct answer is :

select * from db where Date >= '20100401'  (Format of date yyyymmdd)

This will avoid any problem with other language systems and will use the index.

How do ACID and database transactions work?

ACID are desirable properties of any transaction processing engine.

A DBMS is (if it is any good) a particular kind of transaction processing engine that exposes, usually to a very large extent but not quite entirely, those properties.

But other engines exist that can also expose those properties. The kind of software that used to be called "TP monitors" being a case in point (nowadays' equivalent mostly being web servers).

Such TP monitors can access resources other than a DBMS (e.g. a printer), and still guarantee ACID toward their users. As an example of what ACID might mean when a printer is involved in a transaction:

  • Atomicity: an entire document gets printed or nothing at all
  • Consistency: at end-of-transaction, the paper feed is positioned at top-of-page
  • Isolation: no two documents get mixed up while printing
  • Durability: the printer can guarantee that it was not "printing" with empty cartridges.

Javascript: open new page in same window

The second parameter of is a string representing the name of the target window.

Set it to: "_self".

<a href="javascript:q=(document.location.href);void(open(''+escape(q),'_self','resizable,location,menubar,toolbar,scrollbars,status'));">click here</a>

Sidenote: The following question gives an overview of an arguably better way to bind event handlers to HTML links.

What's the best way to replace links with js functions?

Dictionary with list of strings as value

Just create a new array in your dictionary

Dictionary<string, List<string>> myDic = new Dictionary<string, List<string>>();
myDic.Add(newKey, new List<string>(existingList));

Regular Expression usage with ls

You don't say what shell you are using, but they generally don't support regular expressions that way, although there are common *nix CLI tools (grep, sed, etc) that do.

What shells like bash do support is globbing, which uses some similiar characters (eg, *) but is not the same thing.

Newer versions of bash do have a regular expression operator, =~:

for x in `ls`; do 
    if [[ $x =~ .+\..* ]]; then 
        echo $x; 

Show div on scrollDown after 800px

You've got a few things going on there. One, why a class? Do you actually have multiple of these on the page? The CSS suggests you can't. If not you should use an ID - it's faster to select both in CSS and jQuery:

<div id=bottomMenu>You read it all.</div>

Second you've got a few crazy things going on in that CSS - in particular the z-index is supposed to just be a number, not measured in pixels. It specifies what layer this tag is on, where each higher number is closer to the user (or put another way, on top of/occluding tags with lower z-indexes).

The animation you're trying to do is basically .fadeIn(), so just set the div to display: none; initially and use .fadeIn() to animate it:


.fadeIn() works by first doing display: (whatever the proper display property is for the tag), opacity: 0, then gradually ratcheting up the opacity.

Full working example:


#bottomMenu {
    display: none;
    position: fixed;
    left: 0; bottom: 0;
    width: 100%; height: 60px;
    border-top: 1px solid #000;
    background: #fff;
    z-index: 1;


var $win = $(window);

function checkScroll() {
    if ($win.scrollTop() > 100) {
        $'scroll', checkScroll);


Convert string to integer type in Go?

For example,

package main

import (

func main() {
    s := flag.Arg(0)
    // string to int
    i, err := strconv.Atoi(s)
    if err != nil {
        // handle error
    fmt.Println(s, i)

How can I pass a file argument to my bash script using a Terminal command in Linux?

It'll be easier (and more "proper", see below) if you just run your script as

myprogram /path/to/file

Then you can access the path within the script as $1 (for argument #1, similarly $2 is argument #2, etc.)

externalprogram "$file" [other parameters]

Or just

externalprogram "$1" [otherparameters]

If you want to extract the path from something like --file=/path/to/file, that's usually done with the getopts shell function. But that's more complicated than just referencing $1, and besides, switches like --file= are intended to be optional. I'm guessing your script requires a file name to be provided, so it doesn't make sense to pass it in an option.

Importing Pandas gives error AttributeError: module 'pandas' has no attribute 'core' in iPython Notebook

  1. Press Ctrl+C to shut down the jupyter notebook, close all jupyter notebook windows
  2. Reopen it by typing jupyter notebook in cmd prompt.

How to write log to file

I prefer the simplicity and flexibility of the 12 factor app recommendation for logging. To append to a log file you can use shell redirection. The default logger in Go writes to stderr (2).

./app 2>> logfile

See also:

Can two or more people edit an Excel document at the same time?

No, sadly:

The Excel 2010 client application does not support co-authoring workbooks in SharePoint Server 2010. However, the Excel client application does support non-real-time co-authoring workbooks stored locally or on network (UNC) paths by using the Shared Workbook feature. Co-authoring workbooks in SharePoint is supported by using the Microsoft Excel Web App, included with Office Web Apps

From Co-authoring overview (SharePoint Server 2010)

...and not for SharePoint 2013 either. Though it works for pretty much all other Office documents. Go figure.

Get checkbox values using checkbox name using jquery

Like it has been said few times, you need to change your selector to


But I want to add, you have to use single or double quotes when using [] in selector.

How to disable all <input > inside a form with jQuery?

With this one line you can disable any input field in a form

$('form *').prop('disabled', true);

How to check if a column exists in a SQL Server table?

Below query can be used to check whether searched column exists or not in the table. We can take decision based on the searched result also as shown below.

    SELECT 'Column Already Exists.'
    ALTER TABLE <YourTableName> ADD <YourColumnName> <DataType>[Size]

What is a monad?

The two things that helped me best when learning about there were:

Chapter 8, "Functional Parsers," from Graham Hutton's book Programming in Haskell. This doesn't mention monads at all, actually, but if you can work through chapter and really understand everything in it, particularly how a sequence of bind operations is evaluated, you'll understand the internals of monads. Expect this to take several tries.

The tutorial All About Monads. This gives several good examples of their use, and I have to say that the analogy in Appendex I worked for me.

Does overflow:hidden applied to <body> work on iPhone Safari?

Why not wrap the content you don't want shown in an element with a class and set that class to display:none in a stylesheet meant only for the iphone and other handheld devices?

<!--[if !IE]>-->
<link media="only screen and (max-device-width: 480px)" href="small-device.css" type= "text/css" rel="stylesheet">

How do I convert certain columns of a data frame to become factors?

Given the following sample

myData <- data.frame(A=rep(1:2, 3), B=rep(1:3, 2), Pulse=20:25)  


myData$A <-as.factor(myData$A)
myData$B <-as.factor(myData$B)

or you could select your columns altogether and wrap it up nicely:

# select columns
cols <- c("A", "B")
myData[,cols] <- data.frame(apply(myData[cols], 2, as.factor))

levels(myData$A) <- c("long", "short")
levels(myData$B) <- c("1kg", "2kg", "3kg")

To obtain

> myData
      A   B Pulse
1  long 1kg    20
2 short 2kg    21
3  long 3kg    22
4 short 1kg    23
5  long 2kg    24
6 short 3kg    25

Defining a variable with or without export

As you might already know, UNIX allows processes to have a set of environment variables, which are key/value pairs, both key and value being strings. Operating system is responsible for keeping these pairs for each process separately.

Program can access its environment variables through this UNIX API:

  • char *getenv(const char *name);
  • int setenv(const char *name, const char *value, int override);
  • int unsetenv(const char *name);

Processes also inherit environment variables from parent processes. Operating system is responsible for creating a copy of all "envars" at the moment the child process is created.

Bash, among other shells, is capable of setting its environment variables on user request. This is what export exists for.

export is a Bash command to set environment variable for Bash. All variables set with this command would be inherited by all processes that this Bash would create.

More on Environment in Bash

Another kind of variable in Bash is internal variable. Since Bash is not just interactive shell, it is in fact a script interpreter, as any other interpreter (e.g. Python) it is capable of keeping its own set of variables. It should be mentioned that Bash (unlike Python) supports only string variables.

Notation for defining Bash variables is name=value. These variables stay inside Bash and have nothing to do with environment variables kept by operating system.

More on Shell Parameters (including variables)

Also worth noting that, according to Bash reference manual:

The environment for any simple command or function may be augmented temporarily by prefixing it with parameter assignments, as described in Shell Parameters. These assignment statements affect only the environment seen by that command.

To sum things up:

  • export is used to set environment variable in operating system. This variable will be available to all child processes created by current Bash process ever after.
  • Bash variable notation (name=value) is used to set local variables available only to current process of bash
  • Bash variable notation prefixing another command creates environment variable only for scope of that command.

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

We had this case where an .html file was seen as binary whenever we tried to make changes in it. Very uncool to not see diffs. To be honest, I didn't checked all the solutions here but what worked for us was the following:

  1. Removed the file (actually moved it to my Desktop) and commited the git deletion. Git says Deleted file with mode 100644 (Regular) Binary file differs
  2. Re-added the file (actually moved it from my Desktop back into the project). Git says New file with mode 100644 (Regular) 1 chunk, 135 insertions, 0 deletions The file is now added as a regular text file

From now on, any changes I made in the file is seen as a regular text diff. You could also squash these commits (1, 2, and 3 being the actual change you make) but I prefer to be able to see in the future what I did. Squashing 1 & 2 will show a binary change.

How to remove from a map while iterating it?

The C++20 draft contains the convenience function std::erase_if.

So you can use that function to do it as a one-liner.

std::map<K, V> map_obj;
//calls needs_removing for each element and erases it, if true was reuturned
//if you need to pass only part of the key/value pair
std::erase_if(map_obj,[](auto& kv){return needs_removing(kv.first);});

How do I setup the dotenv file in Node.js?

For React apps created with the create-react-app template, you don't need to use dotenv directly. react-scripts does that for you.

Simply creates a .env file in the top level directory of your project and add all your envs there, but notice that they MUST start with REACT_APP prefix, otherwise they will be ignored.

More details in their documentation. I just spent a couple of hours dealing with this and hope it will save you some time.