Programs & Examples On #Double byte

What characters are forbidden in Windows and Linux directory names?

Though the only illegal Unix chars might be / and NULL, although some consideration for command line interpretation should be included.

For example, while it might be legal to name a file 1>&2 or 2>&1 in Unix, file names such as this might be misinterpreted when used on a command line.

Similarly it might be possible to name a file $PATH, but when trying to access it from the command line, the shell will translate $PATH to its variable value.

What Java ORM do you prefer, and why?

Hibernate, because it's basically the defacto standard in Java and was one of the driving forces in the creation of the JPA. It's got excellent support in Spring, and almost every Java framework supports it. Finally, GORM is a really cool wrapper around it doing dynamic finders and so on using Groovy.

It's even been ported to .NET (NHibernate) so you can use it there too.

Google Play Services Missing in Emulator (Android 4.4.2)

You will not able to test the app using the Google-Play-Service library in emulator. In order to test that app in emulator you need to install some system framework in your emulator to make it work.

Refer the above answer to install Google play service on your emulator.

How to use a FolderBrowserDialog from a WPF application

//add a reference to System.Windows.Forms.dll

public partial class MainWindow : Window, System.Windows.Forms.IWin32Window
    public MainWindow()

    private void button_Click(object sender, RoutedEventArgs e)
        var fbd = new FolderBrowserDialog();

    IntPtr System.Windows.Forms.IWin32Window.Handle
            return ((HwndSource)PresentationSource.FromVisual(this)).Handle;

In python, what is the difference between random.uniform() and random.random()?

Apart from what is being mentioned above, .uniform() can also be used for generating multiple random numbers that too with the desired shape which is not possible with .random()


#generates 0.6722785586307918

while the following code

np.random.uniform(0.0, 1.0, size = (5,2))

#generates this 
array([[0.67227856, 0.4880784 ],
       [0.82549517, 0.03144639],
       [0.80804996, 0.56561742],
       [0.2976225 , 0.04669572],
       [0.9906274 , 0.00682573]])

This can't be done with random(...), and if you're generating the random(...) numbers for ML related things, most of the time, you'll end up using .uniform(...)

Why should I use a container div in HTML?

Certain browsers (<cough> Internet Explorer) don't support certain properties on the body, notably width and max-width.

CSS strikethrough different color from text?

Here you go:

<style>body {color: #000;}</style>_x000D_
<del>&nbsp;&nbsp;<span style="color:#999">facebook</span>&nbsp;&nbsp;</del>

Return multiple values from a function, sub or type?

You can also use a variant array as the return result to return a sequence of arbitrary values:

Function f(i As Integer, s As String) As Variant()
    f = Array(i + 1, "ate my " + s, Array(1#, 2#, 3#))
End Function

Sub test()
    result = f(2, "hat")
    i1 = result(0)
    s1 = result(1)
    a1 = result(2)
End Sub

Ugly and bug prone because your caller needs to know what's being returned to use the result, but occasionally useful nonetheless.

Ternary operator in AngularJS templates

Update: Angular 1.1.5 added a ternary operator, so now we can simply write

<li ng-class="$first ? 'firstRow' : 'nonFirstRow'">

If you are using an earlier version of Angular, your two choices are:

  1. (condition && result_if_true || !condition && result_if_false)
  2. {true: 'result_if_true', false: 'result_if_false'}[condition]

item 2. above creates an object with two properties. The array syntax is used to select either the property with name true or the property with name false, and return the associated value.


<li class="{{{true: 'myClass1 myClass2', false: ''}[$first]}}">...</li>
<li ng-class="{true: 'myClass1 myClass2', false: ''}[$first]">...</li>

$first is set to true inside an ng-repeat for the first element, so the above would apply class 'myClass1' and 'myClass2' only the first time through the loop.

With ng-class there is an easier way though: ng-class takes an expression that must evaluate to one of the following:

  1. a string of space-delimited class names
  2. an array of class names
  3. a map/object of class names to boolean values.

An example of 1) was given above. Here is an example of 3, which I think reads much better:

 <li ng-class="{myClass: $first, anotherClass: $index == 2}">...</li>

The first time through an ng-repeat loop, class myClass is added. The 3rd time through ($index starts at 0), class anotherClass is added.

ng-style takes an expression that must evaluate to a map/object of CSS style names to CSS values. E.g.,

 <li ng-style="{true: {color: 'red'}, false: {}}[$first]">...</li>

How do I preserve line breaks when getting text from a textarea?

function get() {_x000D_
  var arrayOfRows = document.getElementById("ta").value.split("\n");_x000D_
  var docfrag = document.createDocumentFragment();_x000D_
  var p = document.getElementById("result");_x000D_
  while (p.firstChild) {_x000D_
  arrayOfRows.forEach(function(row, index, array) {_x000D_
    var span = document.createElement("span");_x000D_
    span.textContent = row;_x000D_
    if(index < array.length - 1) {_x000D_
<textarea id="ta" rows=3></textarea><br>_x000D_
<button onclick="get()">get</button>_x000D_
<p id="result"></p>

You can split textarea rows into array:

var arrayOfRows = postText.value.split("\n");

Then use it to generate, maybe, more p tags...

undefined offset PHP error

Undefined offset means there's an empty array key for example:

$a = array('Felix','Jon','Java');

// This will result in an "Undefined offset" because the size of the array
// is three (3), thus, 0,1,2 without 3
echo $a[3];

You can solve the problem using a loop (while):

$i = 0;
while ($row = mysqli_fetch_assoc($result)) {
    // Increase count by 1, thus, $i=1

    $groupname[$i] = base64_decode(base64_decode($row['groupname']));

    // Set the first position of the array to null or empty
    $groupname[0] = "";

ActionBarActivity cannot resolve a symbol

Follow the steps mentioned for using support ActionBar in Android Studio(0.4.2) :

Download the Android Support Repository from Android SDK Manager, SDK Manager icon will be available on Android Studio tool bar (or Tools -> Android -> SDK Manager).

enter image description here

After download you will find your Support repository here


Open your main module's build.gradle file and add following dependency for using action bar in lower API level

dependencies {
    compile ''

Sync your project with gradle using the tiny Gradle icon available in toolbar (or Tools -> Android -> Sync Project With Gradle Files).

There is some issue going on with Android Studio 0.4.2 so check this as well if you face any issue while importing classes in code.

Import Google Play Services library in Android Studio

If Required follow the steps as well :

  • Exit Android Studio
  • Delete all the .iml files and files inside .idea folder from your project
  • Relaunch Android Studio and wait till the project synced completely with gradle. If it shows an error in Event Log with import option click on Import Project.

This is bug in Android Studio 0.4.2 and fixed for Android Studio 0.4.3 release.

Classpath including JAR within a JAR

Extracting into an Uber-dir works for me as we s should all be using root:\java and have outlets code in packages with versioning. Ie ca.tecreations-1.0.0. Signing is okay because the jars are intact from their downloaded location. 3rd party signatures intact, extract to c:\java. There’s my project dir. run from launcher so java -cp c:\java Launcher

AngularJS disable partial caching on dev machine

I found that the HTTP interceptor method works pretty nicely, and allows additional flexibility & control. Additionally, you can cache-bust for each production release by using a release hash as the buster variable.

Here is what the dev cachebusting method looks like using Date.

app.factory('cachebustInjector', function(conf) {   
    var cachebustInjector = {
        request: function(config) {    
            // new timestamp will be appended to each new partial .html request to prevent caching in a dev environment               
            var buster = new Date().getTime();

            if (config.url.indexOf('static/angular_templates') > -1) {
                config.url += ['?v=', buster].join('');
            return config;
    return cachebustInjector;

app.config(['$httpProvider', function($httpProvider) {

Create GUI using Eclipse (Java)


this will allow you to create gui with html-like syntax

A regex for version number parsing

Use regex and now you have two problems. I would split the thing on dots ("."), then make sure that each part is either a wildcard or set of digits (regex is perfect now). If the thing is valid, you just return correct chunk of the split.

How to Get Element By Class in JavaScript?

var elems = document.querySelectorAll('.one');_x000D_
for (var i = 0; i < elems.length; i++) {_x000D_
    elems[i].innerHTML = 'content';_x000D_

Django DoesNotExist

This line

 except Vehicle.vehicledevice.device.DoesNotExist

means look for device instance for DoesNotExist exception, but there's none, because it's on class level, you want something like

 except Device.DoesNotExist

How to map to multiple elements with Java 8 streams?

To do this, I had to come up with an intermediate data structure:

class KeyDataPoint {
    String key;
    DateTime timestamp;
    Number data;
    // obvious constructor and getters

With this in place, the approach is to "flatten" each MultiDataPoint into a list of (timestamp, key, data) triples and stream together all such triples from the list of MultiDataPoint.

Then, we apply a groupingBy operation on the string key in order to gather the data for each key together. Note that a simple groupingBy would result in a map from each string key to a list of the corresponding KeyDataPoint triples. We don't want the triples; we want DataPoint instances, which are (timestamp, data) pairs. To do this we apply a "downstream" collector of the groupingBy which is a mapping operation that constructs a new DataPoint by getting the right values from the KeyDataPoint triple. The downstream collector of the mapping operation is simply toList which collects the DataPoint objects of the same group into a list.

Now we have a Map<String, List<DataPoint>> and we want to convert it to a collection of DataSet objects. We simply stream out the map entries and construct DataSet objects, collect them into a list, and return it.

The code ends up looking like this:

Collection<DataSet> convertMultiDataPointToDataSet(List<MultiDataPoint> multiDataPoints) {
        .flatMap(mdp -> mdp.getData().entrySet().stream()
                           .map(e -> new KeyDataPoint(e.getKey(), mdp.getTimestamp(), e.getValue())))
                    mapping(kdp -> new DataPoint(kdp.getTimestamp(), kdp.getData()), toList())))
        .map(e -> new DataSet(e.getKey(), e.getValue()))

I took some liberties with constructors and getters, but I think they should be obvious.

How to read from a file or STDIN in Bash?


if [ -p /dev/stdin ]; then
    #for FILE in "$@" /dev/stdin
    for FILE in /dev/stdin
        while IFS= read -r LINE
            echo "$@" "$LINE"   #print line argument and stdin
        done < "$FILE"
    printf "[ -p /dev/stdin ] is false\n"


echo var var2 | bash 


var var2


bash < <(cat /etc/passwd)



Display the current time and date in an Android application

To display the current date function:

Calendar c = Calendar.getInstance();

SimpleDateFormat df = new SimpleDateFormat("dd-MMM-yyyy");
String date = df.format(c.getTime());

You must want to import

import java.text.SimpleDateFormat; import java.util.Calendar;

You must want to use

TextView Date;
Date = (TextView) findViewById(;

Localhost : 404 not found

you need to stop that service running on this port .check service running on specific port by "netstat -ano".then in window search type services.exe and search that process and stop that process .to change port of that process check this

Uploading multiple files using formData()

You just have to use fileToUpload[] instead of fileToUpload :

fd.append("fileToUpload[]", document.getElementById('fileToUpload').files[0]);

And it will return an array with multiple names, sizes, etc...

Recursively look for files with a specific extension

Without using find:

du -a $directory | awk '{print $2}' | grep '\.in$'

How to query SOLR for empty fields?

If you are using SolrSharp, it does not support negative queries.

You need to change QueryParameter.cs (Create a new parameter)

private bool _negativeQuery = false;

public QueryParameter(string field, string value, ParameterJoin parameterJoin = ParameterJoin.AND, bool negativeQuery = false)
    this._field = field;
    this._value = value.Trim();
    this._parameterJoin = parameterJoin;
    this._negativeQuery = negativeQuery;

public bool NegativeQuery
    get { return _negativeQuery; }
    set { _negativeQuery = value; }

And in QueryParameterCollection.cs class, the ToString() override, looks if the Negative parameter is true

arQ[x] = (qp.NegativeQuery ? "-(" : "(") + qp.ToString() + ")" + (qp.Boost != 1 ? "^" + qp.Boost.ToString() : "");

When you call the parameter creator, if it's a negative value. Simple change the propertie

List<QueryParameter> QueryParameters = new List<QueryParameter>();
QueryParameters.Add(new QueryParameter("PartnerList", "[* TO *]", ParameterJoin.AND, true));

Docker error cannot delete docker container, conflict: unable to remove repository reference

If you want to cleanup docker images and containers

CAUTION: this will flush everything

stop all containers

docker stop $(docker ps -a -q)

remove all containers

docker rm $(docker ps -a -q)

remove all images

docker rmi -f $(docker images -a -q)

How to debug PDO database queries?

To log MySQL in WAMP, you will need to edit the my.ini (e.g. under wamp\bin\mysql\mysql5.6.17\my.ini)

and add to [mysqld]:

general_log = 1

How to Convert unsigned char* to std::string in C++?

BYTE *str1 = "Hello World";
std::string str2((char *)str1);  /* construct on the stack */


std::string *str3 = new std::string((char *)str1); /* construct on the heap */
cout << &str3;
delete str3;

Private class declaration

private modifier will make your class inaccessible from outside, so there wouldn't be any advantage of this and I think that is why it is illegal and only public, abstract & final are permitted.

Note : Even you can not make it protected.

Plot a bar using matplotlib using a dictionary

For future reference, the above code does not work with Python 3. For Python 3, the D.keys() needs to be converted to a list.

import matplotlib.pyplot as plt

D = {u'Label1':26, u'Label2': 17, u'Label3':30}, D.values(), align='center')
plt.xticks(range(len(D)), list(D.keys()))

Convert line endings

Some options:

Using tr

tr -d '\15\32' < windows.txt > unix.txt


tr -d '\r' < windows.txt > unix.txt 

Using perl

perl -p -e 's/\r$//' < windows.txt > unix.txt

Using sed

sed 's/^M$//' windows.txt > unix.txt


sed 's/\r$//' windows.txt > unix.txt

To obtain ^M, you have to type CTRL-V and then CTRL-M.

`&mdash;` or `&#8212;` is there any difference in HTML output?

From W3 web site Common HTML entities used for typography

For the sake of portability, Unicode entity references should be reserved for use in documents certain to be written in the UTF-8 or UTF-16 character sets. In all other cases, the alphanumeric references should be used.

Translation: If you are looking for widest support, go with &mdash;

CS0234: Mvc does not exist in the System.Web namespace

I had this problem, but all the applications in IIS were broken when they had been working previously. None of the marked solutions helped me. The problem ended up being an extra copy of web.config had been introduced to my root directory. I removed that file and problem solved.

Default passwords of Oracle 11g?

It is possible to connect to the database without specifying a password. Once you've done that you can then reset the passwords. I'm assuming that you've installed the database on your machine; if not you'll first need to connect to the machine the database is running on.

  1. Ensure your user account is a member of the dba group. How you do this depends on what OS you are running.

  2. Enter sqlplus / as sysdba in a Command Prompt/shell/Terminal window as appropriate. This should log you in to the database as SYS.

  3. Once you're logged in, you can then enter

    alter user SYS identified by "newpassword";

    to reset the SYS password, and similarly for SYSTEM.

(Note: I haven't tried any of this on Oracle 12c; I'm assuming they haven't changed things since Oracle 11g.)

How do I check OS with a preprocessor directive?

On MinGW, the _WIN32 define check isn't working. Here's a solution:

#if defined(_WIN32) || defined(__CYGWIN__)
    // Windows (x86 or x64)
    // ...
#elif defined(__linux__)
    // Linux
    // ...
#elif defined(__APPLE__) && defined(__MACH__)
    // Mac OS
    // ...
#elif defined(unix) || defined(__unix__) || defined(__unix)
    // Unix like OS
    // ...
    #error Unknown environment!

For more information please look:

Get all child views inside LinearLayout at once

Get all views from any type of layout

public List<View> getAllViews(ViewGroup layout){
        List<View> views = new ArrayList<>();
        for(int i =0; i< layout.getChildCount(); i++){
        return views;

Get all TextView from any type of layout

public List<TextView> getAllTextViews(ViewGroup layout){
        List<TextView> views = new ArrayList<>();
        for(int i =0; i< layout.getChildCount(); i++){
            View v =layout.getChildAt(i);
            if(v instanceof TextView){
        return views;

How to set a single, main title above all the subplots with Pyplot?

A few points I find useful when applying this to my own plots:

  • I prefer the consistency of using fig.suptitle(title) rather than plt.suptitle(title)
  • When using fig.tight_layout() the title must be shifted with fig.subplots_adjust(top=0.88)
  • See answer below about fontsizes

Example code taken from subplots demo in matplotlib docs and adjusted with a master title.

A nice 4x4 plot

import matplotlib.pyplot as plt
import numpy as np

# Simple data to display in various forms
x = np.linspace(0, 2 * np.pi, 400)
y = np.sin(x ** 2)

fig, axarr = plt.subplots(2, 2)
fig.suptitle("This Main Title is Nicely Formatted", fontsize=16)

axarr[0, 0].plot(x, y)
axarr[0, 0].set_title('Axis [0,0] Subtitle')
axarr[0, 1].scatter(x, y)
axarr[0, 1].set_title('Axis [0,1] Subtitle')
axarr[1, 0].plot(x, y ** 2)
axarr[1, 0].set_title('Axis [1,0] Subtitle')
axarr[1, 1].scatter(x, y ** 2)
axarr[1, 1].set_title('Axis [1,1] Subtitle')

# # Fine-tune figure; hide x ticks for top plots and y ticks for right plots
plt.setp([a.get_xticklabels() for a in axarr[0, :]], visible=False)
plt.setp([a.get_yticklabels() for a in axarr[:, 1]], visible=False)

# Tight layout often produces nice results
# but requires the title to be spaced accordingly

Checking that a List is not empty in Hamcrest

This is fixed in Hamcrest 1.3. The below code compiles and does not generate any warnings:

// given
List<String> list = new ArrayList<String>();
// then
assertThat(list, is(not(empty())));

But if you have to use older version - instead of bugged empty() you could use:

(import static org.hamcrest.number.OrderingComparison.greaterThan; or
import static org.hamcrest.Matchers.greaterThan;)


// given
List<String> list = new ArrayList<String>();
// then
assertThat(list, hasSize(greaterThan(0)));

The most important thing about above solutions is that it does not generate any warnings. The second solution is even more useful if you would like to estimate minimum result size.

Error handling in C code

What you could do instead of returning your error, and thus forbidding you from returning data with your function, is using a wrapper for your return type:

typedef struct {
    enum {SUCCESS, ERROR} status;
    union {
        int errCode;
        MyType value;
    } ret;
} MyTypeWrapper;

Then, in the called function:

MyTypeWrapper MYAPIFunction(MYAPIHandle h) {
    MyTypeWrapper wrapper;
    // [...]
    // If there is an error somewhere:
    wrapper.status = ERROR;
    wrapper.ret.errCode = MY_ERROR_CODE;

    // Everything went well:
    wrapper.status = SUCCESS;
    wrapper.ret.value = myProcessedData;
    return wrapper;

Please note that with the following method, the wrapper will have the size of MyType plus one byte (on most compilers), which is quite profitable; and you won't have to push another argument on the stack when you call your function (returnedSize or returnedError in both of the methods you presented).

Best way to encode text data for XML in Java?

You could use the Enterprise Security API (ESAPI) library, which provides methods like encodeForXML and encodeForXMLAttribute. Take a look at the documentation of the Encoder interface; it also contains examples of how to create an instance of DefaultEncoder.

How to automatically generate N "distinct" colors?

Here's a solution to managed your "distinct" issue, which is entirely overblown:

Create a unit sphere and drop points on it with repelling charges. Run a particle system until they no longer move (or the delta is "small enough"). At this point, each of the points are as far away from each other as possible. Convert (x, y, z) to rgb.

I mention it because for certain classes of problems, this type of solution can work better than brute force.

I originally saw this approach here for tesselating a sphere.

Again, the most obvious solutions of traversing HSL space or RGB space will probably work just fine.

How to click a link whose href has a certain substring in Selenium?

I need to click the link who's href has substring "long" in it. How can I do this?

With the beauty of CSS selectors.

your statement would be...


This means, in english,

Find me any 'a' elements, that have the href attribute, and that attribute contains 'long'

You can find a useful article about formulating your own selectors for automation effectively, as well as a list of all the other equality operators. contains, starts with, etc... You can find that at:

Doing a cleanup action just before Node.js exits

"exit" is an event that gets triggered when node finish it's event loop internally, it's not triggered when you terminate the process externally.

What you're looking for is executing something on a SIGINT.

The docs at give an example:

Example of listening for SIGINT:

// Start reading from stdin so we don't exit.

process.on('SIGINT', function () {
  console.log('Got SIGINT.  Press Control-D to exit.');

Note: this seems to interrupt the sigint and you would need to call process.exit() when you finish with your code.

JPA: how do I persist a String into a database field, type MYSQL Text

With @Lob I always end up with a LONGTEXTin MySQL.

To get TEXT I declare it that way (JPA 2.0):

@Column(columnDefinition = "TEXT")
private String text

Find this better, because I can directly choose which Text-Type the column will have in database.

For columnDefinition it is also good to read this.

EDIT: Please pay attention to Adam Siemions comment and check the database engine you are using, before applying columnDefinition = "TEXT".

How to perform a LEFT JOIN in SQL Server between two SELECT statements?

Try this:

SELECT user.userID, edge.TailUser, edge.Weight 
FROM user
LEFT JOIN edge ON edge.HeadUser = User.UserID
WHERE edge.HeadUser=5043


AND edge.HeadUser=5043

instead of WHERE clausule.

`ui-router` $stateParams vs. $state.params

An interesting observation I made while passing previous state params from one route to another is that $stateParams gets hoisted and overwrites the previous route's state params that were passed with the current state params, but using $state.params doesn't.

When using $stateParams:

var stateParams        = {};
stateParams.nextParams = $stateParams; //{item_id:123}       = $;

$state.go('app.login', stateParams);
//$stateParams.nextParams on app.login is now:
//{next:'app.details', nextParams:{next:'app.details'}}

When using $state.params:

var stateParams        = {};
stateParams.nextParams = $state.params; //{item_id:123}       = $;

$state.go('app.login', stateParams);
//$stateParams.nextParams on app.login is now:
//{next:'app.details', nextParams:{item_id:123}}

Facebook API - How do I get a Facebook user's profile image through the Facebook API (without requiring the user to "Allow" the application)

Added this as a comment to accepted answer, but felt it deserved a longer explanation. Starting around April 2015 this will probably be raised a few times.

As of V2 of the graph api the accepted answer no longer works using a username. So now you need the userid first, and you can no longer use a username to get this. To further complicate matters, for privacy reasons, Facebook is now changing userid's per app (see and ), so you will have to have some kind of proper authentication to retrieve a userid you can use. Technically the profile pic is still public and available at /userid/picture (see docs at and this example user: however figuring out a user's standard userid seems impossible based just on their profile - your app would need to get them to approve interaction with the app which for my use case (just showing a profile pic next to their FB profile link) is overkill.

If someone has figured out a way to get the profile pic based on username, or alternatively, how to get a userid (even an alternating one) to use to retrieve a profile pic, please share! In the meantime, the old graph url still works until April 2015.

Prevent multiple instances of a given app in .NET?

static void Main()                  // args are OK here, of course
    bool ok;
    m = new System.Threading.Mutex(true, "YourNameHere", out ok);

    if (! ok)
        MessageBox.Show("Another instance is already running.");

    Application.Run(new Form1());   // or whatever was there

    GC.KeepAlive(m);                // important!

From: Ensuring a single instance of .NET Application

and: Single Instance Application Mutex

Same answer as @Smink and @Imjustpondering with a twist:

Jon Skeet's FAQ on C# to find out why GC.KeepAlive matters

How to check if an excel cell is empty using Apache POI?

This is the safest and most concise way I see as of POI 3.1.7 up to POI 4:

boolean isBlankCell = CellType.BLANK == cell.getCellTypeEnum();
boolean isEmptyStringCell = CellType.STRING == cell.getCellTypeEnum() && cell.getStringCellValue().trim().isEmpty(); 

if (isBlankCell || isEmptyStringCell) {

As of POI 4 getCellTypeEnum() will be deprecated if favor of getCellType() but the return type should stay the same.

Copy Paste Values only( xlPasteValues )

If you are wanting to just copy the whole column, you can simplify the code a lot by doing something like this:

Sub CopyCol()


    Sheets("Sheet2").Columns(2).PasteSpecial xlPasteValues

End Sub


Sub CopyCol()


    Sheets("Sheet2").Columns("B").PasteSpecial xlPasteValues

End Sub

Or if you want to keep the loop

Public Sub CopyrangeA()

    Dim firstrowDB As Long, lastrow As Long
    Dim arr1, arr2, i As Integer

    firstrowDB = 1
    arr1 = Array("BJ", "BK")
    arr2 = Array("A", "B")

    For i = LBound(arr1) To UBound(arr1)


        Sheets("Sheet2").Columns(arr2(i)).PasteSpecial xlPasteValues

    Application.CutCopyMode = False

End Sub

How can I use inverse or negative wildcards when pattern matching in a unix/linux shell?

Not in bash (that I know of), but:

cp `ls | grep -v Music` /target_directory

I know this is not exactly what you were looking for, but it will solve your example.

I keep getting "Uncaught SyntaxError: Unexpected token o"

Another hints for Unexpected token errors. There are two major differences between javascript objects and json:

  1. json data must be always quoted with double quotes.
  2. keys must be quoted

Correct JSON

    "english": "bag",
    "kana": "kaban",
    "kanji": "K"

Error JSON 1

    'english': 'bag',
    'kana': 'kaban',
    'kanji': 'K'

Error JSON 2

    english: "bag",
    kana: "kaban",
    kanji: "K"


This is not a direct answer for that question. But it's an answer for Unexpected token errors. So it may be help others who stumple upon that question.

How do I force a DIV block to extend to the bottom of a page even if it has no content?

I'll try to answer the question directly in the title, rather than being hell-bent on sticking a footer to the bottom of the page.

Make div extend to the bottom of the page if there's not enough content to fill the available vertical browser viewport:

Demo at (drag the frame handle to see effect) :
(upside: clean, simple. downside: requires flexbox -



  <div class=div1>

  <div class=div2>



* { padding: 0; margin: 0; }

html, body {
  height: 100%;

  display: flex;
  flex-direction: column;

body > * {
  flex-shrink: 0;

.div1 { background-color: yellow; }

.div2 {
  background-color: orange;
  flex-grow: 1;

ta-da - or i'm just too sleepy

Add a new column to existing table in a migration

I'll add on to mike3875's answer for future readers using Laravel 5.1 and onward.

To make things quicker, you can use the flag "--table" like this:

php artisan make:migration add_paid_to_users --table="users"

This will add the up and down method content automatically:

 * Run the migrations.
 * @return void
public function up()
    Schema::table('users', function (Blueprint $table) {

Similarily, you can use the --create["table_name"] option when creating new migrations which will add more boilerplate to your migrations. Small point, but helpful when doing loads of them!

How to convert a multipart file to File?

small correction on @PetrosTsialiamanis post , new File( multipart.getOriginalFilename()) this will create file in server location where sometime you will face write permission issues for the user, its not always possible to give write permission to every user who perform action. System.getProperty("") will create temp directory where your file will be created properly. This way you are creating temp folder, where file gets created , later on you can delete file or temp folder.

public  static File multipartToFile(MultipartFile multipart, String fileName) throws IllegalStateException, IOException {
    File convFile = new File(System.getProperty("")+"/"+fileName);
    return convFile;

put this method in ur common utility and use it like for eg. Utility.multipartToFile(...)

log4j vs logback

Your decision should be based on

  • your actual need for these "more features"; and
  • your expected cost of implementing the change.

You should resist the urge to change APIs just because it's "newer, shinier, better." I follow a policy of "if it's not broken, don't kick it."

If your application requires a very sophisticated logging framework, you may want to consider why.

Error handling in Bash

I've used

die() {
        echo $1
        kill $$

before; i think because 'exit' was failing for me for some reason. The above defaults seem like a good idea, though.

Python list / sublist selection -1 weirdness

I get consistent behaviour for both instances:

>>> ls[0:10]
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> ls[10:-1]
[10, 11, 12, 13, 14, 15, 16, 17, 18]

Note, though, that tenth element of the list is at index 9, since the list is 0-indexed. That might be where your hang-up is.

In other words, [0:10] doesn't go from index 0-10, it effectively goes from 0 to the tenth element (which gets you indexes 0-9, since the 10 is not inclusive at the end of the slice).

Difference between \w and \b regular expression meta characters

@Mahender, you probably meant the difference between \W (instead of \w) and \b. If not, then I would agree with @BoltClock and @jwismar above. Otherwise continue reading.

\W would match any non-word character and so its easy to try to use it to match word boundaries. The problem is that it will not match the start or end of a line. \b is more suited for matching word boundaries as it will also match the start or end of a line. Roughly speaking (more experienced users can correct me here) \b can be thought of as (\W|^|$). [Edit: as @?mega mentions below, \b is a zero-length match so (\W|^|$) is not strictly correct, but hopefully helps explain the diff]

Quick example: For the string Hello World, .+\W would match Hello_ (with the space) but will not match World. .+\b would match both Hello and World.

How do I set up IntelliJ IDEA for Android applications?

Once I have followed all these steps, I start to receive error messages in all android classes calls like:

Cannot resolve Android Classes

I revolved that including android.jar in the SDKs Platform Settings:

SKDs Classpath

Generate fixed length Strings filled with whitespaces

The Guava Library has Strings.padStart that does exactly what you want, along with many other useful utilities.

String contains another two strings

You would be better off just calling Contains twice or making your own extension method to handle this.

string d = "You hit someone for 50 damage";
string a = "damage";
string b = "someone";
string c = "you";

if(d.Contains(a) && d.Contains(b))
   Console.WriteLine(" " + d);

As far as your other question, you could build a regular expression to parse the string to find 50 or if the string is always the same, just split it based on a space and get the 5th part.

Invalid date in safari

Best way to do it is by using the following format:

new Date(year, month, day, hours, minutes, seconds, milliseconds)
var d = new Date(2018, 11, 24, 10, 33, 30, 0);

This is supported in all browsers and will not give you any issues. Please note that the months are written from 0 to 11.

What difference between the DATE, TIME, DATETIME, and TIMESTAMP Types

Saty described the differences between them. For your practice, you can use datetime in order to keep the output of NOW().

For example:

  OrderId int NOT NULL,
  ProductName varchar(50) NOT NULL,
  OrderDate datetime NOT NULL DEFAULT NOW(),

You can read more at w3schools.

Check OS version in Swift?

I made this Singleton for simple use, created an IOSVersion.swift file and added this code :

import UIKit

public class IOSVersion {
    class func SYSTEM_VERSION_EQUAL_TO(version: NSString) -> Bool {
        return UIDevice.currentDevice(),
            options: NSStringCompareOptions.NumericSearch) == NSComparisonResult.OrderedSame

    class func SYSTEM_VERSION_GREATER_THAN(version: NSString) -> Bool {
        return UIDevice.currentDevice() as String,
            options: NSStringCompareOptions.NumericSearch) == NSComparisonResult.OrderedDescending

    class func SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(version: NSString) -> Bool {
        return UIDevice.currentDevice() as String,
            options: NSStringCompareOptions.NumericSearch) != NSComparisonResult.OrderedAscending

    class func SYSTEM_VERSION_LESS_THAN(version: NSString) -> Bool {
        return UIDevice.currentDevice() as String,
            options: NSStringCompareOptions.NumericSearch) == NSComparisonResult.OrderedAscending

    class func SYSTEM_VERSION_LESS_THAN_OR_EQUAL_TO(version: NSString) -> Bool {
        return UIDevice.currentDevice() as String,
            options: NSStringCompareOptions.NumericSearch) != NSComparisonResult.OrderedDescending



Thanks @KVISH

Edit Swift 2 :

if #available(iOS 9.0, *) {
} else {

Laravel migration table field's type change

update: 31 Oct 2018, Still usable on laravel 5.7

To make some change to existing db, you can modify column type by using change() in migration.

This is what you could do

Schema::table('orders', function ($table) {

please note you need to add doctrine/dbal dependency to composer.json for more information you can find it here

Proper way to initialize C++ structs

In C++ classes/structs are identical (in terms of initialization).

A non POD struct may as well have a constructor so it can initialize members.
If your struct is a POD then you can use an initializer.

struct C
    int x; 
    int y;

C  c = {0}; // Zero initialize POD

Alternatively you can use the default constructor.

C  c = C();      // Zero initialize using default constructor
C  c{};          // Latest versions accept this syntax.
C* c = new C();  // Zero initialize a dynamically allocated object.

// Note the difference between the above and the initialize version of the constructor.
// Note: All above comments apply to POD structures.
C  c;            // members are random
C* c = new C;    // members are random (more officially undefined).

I believe valgrind is complaining because that is how C++ used to work. (I am not exactly sure when C++ was upgraded with the zero initialization default construction). Your best bet is to add a constructor that initializes the object (structs are allowed constructors).

As a side note:
A lot of beginners try to value init:

C c(); // Unfortunately this is not a variable declaration.
C c{}; // This syntax was added to overcome this confusion.

// The correct way to do this is:
C c = C();

A quick search for the "Most Vexing Parse" will provide a better explanation than I can.

Adding headers when using httpClient.GetAsync

Following the greenhoorn's answer, you can use "Extensions" like this:

  public static class HttpClientExtensions
        public static HttpClient AddTokenToHeader(this HttpClient cl, string token)
            //int timeoutSec = 90;
            //cl.Timeout = new TimeSpan(0, 0, timeoutSec);
            string contentType = "application/json";
            cl.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue(contentType));
            cl.DefaultRequestHeaders.Add("Authorization", String.Format("Bearer {0}", token));
            var userAgent = "d-fens HttpClient";
            cl.DefaultRequestHeaders.Add("User-Agent", userAgent);
            return cl;

And use:

string _tokenUpdated = "TOKEN";
HttpClient _client;

What is the difference between smoke testing and sanity testing?

Smoke testing is about checking if the requirements are satisfied or not. Smoke testing is a general health check up.

Sanity testing is about checking if a particular module is completely working or not. Sanity testing is specialized in particular health check up.

UML class diagram enum

They are simply showed like this:

|   <<enumeration>>   |
|    DaysOfTheWeek    |
| Sunday              |
| Monday              |
| Tuesday             |
| ...                 |

And then just have an association between that and your class.

How do I remove all non alphanumeric characters from a string except dash?

If you are working in JS, here is a very terse version

myString = myString.replace(/[^A-Za-z0-9 -]/g, "");

Can HTML be embedded inside PHP "if" statement?

I know this is an old post, but I really hate that there is only one answer here that suggests not mixing html and php. Instead of mixing content one should use template systems, or create a basic template system themselves.

In the php

  $var1 = 'Alice'; $var2 = 'apples'; $var3 = 'lunch'; $var4 = 'Bob';

  if ($var1 == 'Alice') {
    $html = file_get_contents('/path/to/file.html'); //get the html template
    $template_placeholders = array('##variable1##', '##variable2##', '##variable3##', '##variable4##'); // variable placeholders inside the template
    $template_replace_variables = array($var1, $var2, $var3, $var4); // the variables to pass to the template
    $html_output = str_replace($template_placeholders, $template_replace_variables, $html); // replace the placeholders with the actual variable values.

  echo $html_output;

In the html (/path/to/file.html)

<p>##variable1## ate ##variable2## for ##variable3## with ##variable4##.</p>

The output of this would be:

Alice ate apples for lunch with Bob.

I can't delete a remote master branch on git

As explained in "Deleting your master branch" by Matthew Brett, you need to change your GitHub repo default branch.

You need to go to the GitHub page for your forked repository, and click on the “Settings” button.

Click on the "Branches" tab on the left hand side. There’s a “Default branch” dropdown list near the top of the screen.

From there, select placeholder (where placeholder is the dummy name for your new default branch).

Confirm that you want to change your default branch.

Now you can do (from the command line):

git push origin :master

Or, since 2012, you can delete that same branch directly on GitHub:

GitHub deletion

That was announced in Sept. 2013, a year after I initially wrote that answer.

For small changes like documentation fixes, typos, or if you’re just a walking software compiler, you can get a lot done in your browser without needing to clone the entire repository to your computer.

Note: for BitBucket, Tum reports in the comments:

About the same for Bitbucket

Repo -> Settings -> Repository details -> Main branch

Removing whitespace from strings in Java

How about replaceAll("\\s", ""). Refer here.

How can I get table names from an MS Access Database?

Schema information which is designed to be very close to that of the SQL-92 INFORMATION_SCHEMA may be obtained for the Jet/ACE engine (which is what I assume you mean by 'access') via the OLE DB providers.


OpenSchema Method (ADO)

Supported Schema Rowsets

Scheduled run of stored procedure on SQL server

Using Management Studio - you may create a Job (unter SQL Server Agent) One Job may include several Steps from T-SQL scripts up to SSIS Packages

Jeb was faster ;)

Setting button text via javascript

Use textContent instead of value to set the button text.

Typically the value attribute is used to associate a value with the button when it's submitted as form data.

Note that while it's possible to set the button text with innerHTML, using textContext should be preferred because it's more performant and it can prevent cross-site scripting attacks as its value is not parsed as HTML.


var b = document.createElement('button');
b.setAttribute('content', 'test content');
b.setAttribute('class', 'btn');  
b.textContent = 'test value';

var wrapper = document.getElementById("divWrapper");

Produces this in the DOM:

<div id="divWrapper">
    <button content="test content" class="btn">test value</button>


Console app arguments, how arguments are passed to Main method

in visual studio you can also do like that to pass simply or avoiding from comandline argument

 static void Main(string[] args)
        if (args == null)
            Console.WriteLine("args is null"); // Check for null array
            args=new string[2];
            args[0] = "welcome in";
            args[1] = "";
            Console.Write("args length is ");
            Console.WriteLine(args.Length); // Write array length
            for (int i = 0; i < args.Length; i++) // Loop through array
                string argument = args[i];
                Console.Write("args index ");
                Console.Write(i); // Write index
                Console.Write(" is [");
                Console.Write(argument); // Write string

Checking for a null int value from a Java ResultSet

AFAIK you can simply use

iVal = rs.getInt("ID_PARENT");
if (rs.wasNull()) {
  // do somthing interesting to handle this situation

even if it is NULL.

Oracle Trigger ORA-04098: trigger is invalid and failed re-validation

in my case, this error is raised due to sequence was not created..


Node.js connect only works on localhost


I have a NodeJS server working on Windows 10 PC, but when I put the IP address and port (example into another computer's browser on my local network nothing happened, although it worked OK on the host computer.

(To find your windows IP address run CMD, then IPCONFIG)

Bar Horing Amir's answer points to the Windows firewall settings. On My PC the Windows Firewall was turned off - as McAfee anti-virus has added its own Firewall.

My system started to work on other computers after I added port 5000 to 'Ports and Systems Services' under the McAfee Firewall settings on the computer with NodeJS on it. Other anti-virus software will have similar settings.

I would seriously suggest trying this solution first with Windows.

Replace and overwrite instead of appending

Using python3 pathlib library:

import re
from pathlib import Path
import shutil

shutil.copy2("/tmp/test.xml", "/tmp/test.xml.bak") # create backup
filepath = Path("/tmp/test.xml")
content = filepath.read_text()
filepath.write_text(re.sub(r"<string>ABC</string>(\s+)<string>(.*)</string>",r"<xyz>ABC</xyz>\1<xyz>\2</xyz>", content))

Similar method using different approach to backups:

from pathlib import Path

filepath = Path("/tmp/test.xml")
filepath.rename(filepath.with_suffix('.bak')) # different approach to backups
content = filepath.read_text()
filepath.write_text(re.sub(r"<string>ABC</string>(\s+)<string>(.*)</string>",r"<xyz>ABC</xyz>\1<xyz>\2</xyz>", content))

SQL Server CTE and recursion example

The execution process is really confusing with recursive CTE, I found the best answer at and the abstract of the CTE execution process is as below.

The semantics of the recursive execution is as follows:

  1. Split the CTE expression into anchor and recursive members.
  2. Run the anchor member(s) creating the first invocation or base result set (T0).
  3. Run the recursive member(s) with Ti as an input and Ti+1 as an output.
  4. Repeat step 3 until an empty set is returned.
  5. Return the result set. This is a UNION ALL of T0 to Tn.

How to write super-fast file-streaming code in C#?

(For future reference.)

Quite possibly the fastest way to do this would be to use memory mapped files (so primarily copying memory, and the OS handling the file reads/writes via its paging/memory management).

Memory Mapped files are supported in managed code in .NET 4.0.

But as noted, you need to profile, and expect to switch to native code for maximum performance.

How to cast int to enum in C++?

Your code

enum Test
    A, B

int a = 1;


Test castEnum = static_cast<Test>(a);

How do I open an .exe from another C++ .exe?

I've had great success with this:

#include <iostream>
#include <windows.h>

int main() {
    ShellExecute(NULL, "open", "path\\to\\file.exe", NULL, NULL, SW_SHOWDEFAULT);

If you're interested, the full documentation is here:

jQuery CSS Opacity

jQuery('#main').css('opacity') = '0.6';

should be

jQuery('#main').css('opacity', '0.6');

Update: if you type in the text box. Click away, the opacity changes.

Can't Autowire @Repository annotated interface in Spring Boot

It could be to do with the package you have it in. I had a similar problem:

Field userRepo in com.App.AppApplication required a bean of type 'repository.UserRepository' that could not be found.

The injection point has the following annotations:
    - @org.springframework.beans.factory.annotation.Autowired(required=true)


Consider defining a bean of type 'repository.UserRepository' in your configuration. "

Solved it by put the repository files into a package with standardised naming convention:

e.g. (for main domain files)

and (for repository files)

That way, spring knows where to go looking for the repositories, else things get confusing really fast. :)

Hope this helps.

What is the equivalent to getLastInsertId() in Cakephp?

After insertion of data, we can use following code to get recently added record's id:


Google Maps: Set Center, Set Center Point and Set more points

Try using this code for v3:

gMap = new google.maps.Map(document.getElementById('map')); 
gMap.setZoom(13);      // This will trigger a zoom_changed on the map
gMap.setCenter(new google.maps.LatLng(37.4419, -122.1419));

How do I convert a Python program to a runnable .exe Windows program?

There is another way to convert Python scripts to .exe files. You can compile Python programs into C++ programs, which can be natively compiled just like any other C++ program.

How to add icon inside EditText view in Android ?

You can set drawableLeft in the XML as suggested by marcos, but you might also want to set it programmatically - for example in response to an event. To do this use the method setCompoundDrawablesWithIntrincisBounds(int, int, int, int):

EditText editText = findViewById(;

// Set drawables for left, top, right, and bottom - send 0 for nothing
editTxt.setCompoundDrawablesWithIntrinsicBounds(R.drawable.myDrawable, 0, 0, 0);

Windows ignores JAVA_HOME: how to set JDK as default?

There's an additional factor here; in addition to the java executables that the java installation puts wherever you ask it to put them, on windows, the java installer also puts copies of some of those executables in your windows system32 directory, so you will likely be using which every java executable was installed most recently.

How to create a JSON object

$post_data = [
  "item" => [
    'item_type_id' => $item_type,
    'string_key' => $string_key,
    'string_value' => $string_value,
    'string_extra' => $string_extra,
    'is_public' => $public,
    'is_public_for_contacts' => $public_contacts

$post_data = json_encode(post_data);
$post_data = json_decode(post_data);
return $post_data;

What is the difference between primary, unique and foreign key constraints, and indexes?

Primary Key and Unique Key are Entity integrity constraints

Primary key allows each row in a table to be uniquely identified and ensures that no duplicate rows exist and no null values are entered.

Unique key constraint is used to prevent the duplication of key values within the rows of a table and allow null values. (In oracle one null is not equal to another null).

  • KEY or INDEX refers to a normal non-unique index. Non-distinct values for the index are allowed, so the index may contain rows with identical values in all columns of the index. These indexes don't enforce any structure on your data so they are used only for speeding up queries.
  • UNIQUE refers to an index where all rows of the index must be unique. That is, the same row may not have identical non-NULL values for all columns in this index as another row. As well as being used to speed up queries, UNIQUE indexes can be used to enforce structure on data, because the database system does not allow this distinct values rule to be broken when inserting or updating data. Your database system may allow a UNIQUE index on columns which allow NULL values, in which case two rows are allowed to be identical if they both contain a NULL value (NULL is considered not equal to itself), though this is probably undesirable depending on your application.
  • PRIMARY acts exactly like a UNIQUE index, except that it is always named 'PRIMARY', and there may be only one on a table (and there should always be one; though some database systems don't enforce this). A PRIMARY index is intended as a way to uniquely identify any row in the table, so it shouldn't be used on any columns which allow NULL values. Your PRIMARY index should always be on the smallest number of columns that are sufficient to uniquely identify a row. Often, this is just one column containing a unique auto-incremented number, but if there is anything else that can uniquely identify a row, such as "countrycode" in a list of countries, you can use that instead.
  • FULLTEXT indexes are different to all of the above, and their behaviour differs more between database systems. Unlike the above three, which are typically b-tree (allowing for selecting, sorting or ranges starting from left most column) or hash (allowing for selection starting from left most column), FULLTEXT indexes are only useful for full text searches done with the MATCH() / AGAINST() clause.

see Differences between INDEX, PRIMARY, UNIQUE, FULLTEXT in MySQL?

Difference between SET autocommit=1 and START TRANSACTION in mysql (Have I missed something?)

Being aware of the transaction (autocommit, explicit and implicit) handling for your database can save you from having to restore data from a backup.

Transactions control data manipulation statement(s) to ensure they are atomic. Being "atomic" means the transaction either occurs, or it does not. The only way to signal the completion of the transaction to database is by using either a COMMIT or ROLLBACK statement (per ANSI-92, which sadly did not include syntax for creating/beginning a transaction so it is vendor specific). COMMIT applies the changes (if any) made within the transaction. ROLLBACK disregards whatever actions took place within the transaction - highly desirable when an UPDATE/DELETE statement does something unintended.

Typically individual DML (Insert, Update, Delete) statements are performed in an autocommit transaction - they are committed as soon as the statement successfully completes. Which means there's no opportunity to roll back the database to the state prior to the statement having been run in cases like yours. When something goes wrong, the only restoration option available is to reconstruct the data from a backup (providing one exists). In MySQL, autocommit is on by default for InnoDB - MyISAM doesn't support transactions. It can be disabled by using:

SET autocommit = 0

An explicit transaction is when statement(s) are wrapped within an explicitly defined transaction code block - for MySQL, that's START TRANSACTION. It also requires an explicitly made COMMIT or ROLLBACK statement at the end of the transaction. Nested transactions is beyond the scope of this topic.

Implicit transactions are slightly different from explicit ones. Implicit transactions do not require explicity defining a transaction. However, like explicit transactions they require a COMMIT or ROLLBACK statement to be supplied.


Explicit transactions are the most ideal solution - they require a statement, COMMIT or ROLLBACK, to finalize the transaction, and what is happening is clearly stated for others to read should there be a need. Implicit transactions are OK if working with the database interactively, but COMMIT statements should only be specified once results have been tested & thoroughly determined to be valid.

That means you should use:

SET autocommit = 0;

  UPDATE ...;

...and only use COMMIT; when the results are correct.

That said, UPDATE and DELETE statements typically only return the number of rows affected, not specific details. Convert such statements into SELECT statements & review the results to ensure correctness prior to attempting the UPDATE/DELETE statement.


DDL (Data Definition Language) statements are automatically committed - they do not require a COMMIT statement. IE: Table, index, stored procedure, database, and view creation or alteration statements.

Shell script to get the process ID on Linux

If you are going to use ps and grep then you should do it this way:

ps aux|grep r[u]by

Those square brackets will cause grep to skip the line for the grep command itself. So to use this in a script do:

output=`ps aux|grep r\[u\]by`
set -- $output
kill $pid
sleep 2
kill -9 $pid >/dev/null 2>&1

The backticks allow you to capture the output of a comand in a shell variable. The set -- parses the ps output into words, and $2 is the second word on the line which happens to be the pid. Then you send a TERM signal, wait a couple of seconds for ruby to to shut itself down, then kill it mercilessly if it still exists, but throw away any output because most of the time kill -9 will complain that the process is already dead.

I know that I have used this without the backslashes before the square brackets but just now I checked it on Ubuntu 12 and it seems to require them. This probably has something to do with bash's many options and the default config on different Linux distros. Hopefully the [ and ] will work anywhere but I no longer have access to the servers where I know that it worked without backslash so I cannot be sure.

One comment suggests grep-v and that is what I used to do, but then when I learned of the [] variant, I decided it was better to spawn one fewer process in the pipeline.

How to set width to 100% in WPF

You could use HorizontalContentAlignment="Stretch" as follows:

<ListBox HorizontalContentAlignment="Stretch"/>

Change selected value of kendo ui dropdownlist

It's possible to "natively" select by value:;

What is the cleanest way to get the progress of JQuery ajax request?

I tried about three different ways of intercepting the construction of the Ajax object:

  1. My first attempt used xhrFields, but that only allows for one listener, only attaches to download (not upload) progress, and requires what seems like unnecessary copy-and-paste.
  2. My second attempt attached a progress function to the returned promise, but I had to maintain my own array of handlers. I could not find a good object to attach the handlers because one place I'd access to the XHR and another I'd have access to the jQuery XHR, but I never had access to the deferred object (only its promise).
  3. My third attempt gave me direct access to the XHR for attaching handlers, but again required to much copy-and-paste code.
  4. I wrapped up my third attempt and replaced jQuery's ajax with my own. The only potential shortcoming is you can no longer use your own xhr() setting. You can allow for that by checking to see whether options.xhr is a function.

I actually call my promise.progress function xhrProgress so I can easily find it later. You might want to name it something else to separate your upload and download listeners. I hope this helps someone even if the original poster already got what he needed.

(function extend_jQuery_ajax_with_progress( window, jQuery, undefined )
var $originalAjax = jQuery.ajax;
jQuery.ajax = function( url, options )
    if( typeof( url ) === 'object' )
    {options = url;url = undefined;}
    options = options || {};

    // Instantiate our own.
    var xmlHttpReq = $.ajaxSettings.xhr();
    // Make it use our own.
    options.xhr = function()
    {return( xmlHttpReq );};

    var $newDeferred = $.Deferred();
    var $oldPromise = $originalAjax( url, options )
    .done( function done_wrapper( response, text_status, jqXHR )
    {return( $newDeferred.resolveWith( this, arguments ));})
    .fail( function fail_wrapper( jqXHR, text_status, error )
    {return( $newDeferred.rejectWith( this, arguments ));})
    .progress( function progress_wrapper()
        window.console.warn( "Whoa, jQuery started actually using deferred progress to report Ajax progress!" );
        return( $newDeferred.notifyWith( this, arguments ));

    var $newPromise = $newDeferred.promise();
    // Extend our own.
    $newPromise.progress = function( handler )
        xmlHttpReq.addEventListener( 'progress', function download_progress( evt )
            //window.console.debug( "download_progress", evt );
            handler.apply( this, [evt]);
        }, false );
        xmlHttpReq.upload.addEventListener( 'progress', function upload_progress( evt )
            //window.console.debug( "upload_progress", evt );
            handler.apply( this, [evt]);
        }, false );
        return( this );
    return( $newPromise );
})( window, jQuery );

How to open a Bootstrap modal window using jQuery?

Try this. It's works for me well.

function clicked(item) {
<link href="" rel="stylesheet"/>
<script src=""></script>

<button onclick="clicked(this);" id="modalME">Click me</button>

<!-- Modal -->
  <div class="modal" id="modalME" aria-hidden="true">
    <div class="modal-dialog">
      <div class="modal-header">
        <h2>Modal in CSS</h2>
        <a href="#close" class="btn-close" aria-hidden="true">×</a> <!--CHANGED TO "#close"-->
      <div class="modal-body">
        <p>One modal example here.</p>
      <div class="modal-footer">
        <a href="#close" class="btn">Nice!</a>  <!--CHANGED TO "#close"-->
  <!-- /Modal -->

How to prevent long words from breaking my div?

HYPHENATOR is the right answer (given above). The real problem behind your question is that web browsers are still (in 2008) extremely primitive that they do not have a hyphenation-feature. Look, we are still on the early beginnings of computer usage - we have to be patient. As long as designers rule the web world we will have a hard time waiting for some real useful new features.

UPDATE: As of December, 2011, we now have another option, with the emerging support of these tags in FF and Safari:

p {
    -webkit-hyphens: auto;
    -moz-hyphens: auto;
    hyphens: auto;

I've done some basic testing and it seems to work on a recent version of Mobile Safari and Safari 5.1.1.

Compatibility table:

how to get data from selected row from datagridview

To get the cell value, you need to read it directly from DataGridView1 using e.RowIndex and e.ColumnIndex properties.


Private Sub DataGridView1_CellContentClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick
   Dim value As Object = DataGridView1.Rows(e.RowIndex).Cells(e.ColumnIndex).Value

   If IsDBNull(value) Then 
      TextBox1.Text = "" ' blank if dbnull values
      TextBox1.Text = CType(value, String)
   End If
End Sub

Loading PictureBox Image from resource file with path (Part 3)

It depends on your file path. For me, the current directory was [project]\bin\Debug, so I had to move to the parent folder twice.

Image image = Image.FromFile(@"..\..\Pictures\"+text+".png");
this.pictureBox1.Image = image;

To find your current directory, you can make a dummy label called label2 and write this:

this.label2.Text = System.IO.Directory.GetCurrentDirectory();

jQuery Ajax Request inside Ajax Request

Call second ajax from 'complete'

Here is the example

   var dt='';
    type: "post",
    url: "ajax/example.php",
    data: 'page='+btn_page,
    success: function(data){
        /*Do something*/
           var a=dt; // This line shows error.
           type: "post",
           url: "example.php",
           data: 'page='+a,
           success: function(data){
              /*do some thing in second function*/

relative path in require_once doesn't work



to get the current path of the script and this should fix your problem.



This will prevent cases where you can run a PHP script from a different folder and therefore the relatives paths will not work.

Edit: slash problem fixed

Unable to resolve dependency for ':app@debug/compileClasspath': Could not resolve

Invalidate Cache / Restart from File option.

Just unchecking offline mode did not work for me.

How do I bind the enter key to a function in tkinter?

I found one good thing about using bind is that you get to know the trigger event: something like: "You clicked with event = [ButtonPress event state=Mod1 num=1 x=43 y=20]" due to the code below:

self.submit.bind('<Button-1>', self.parse)
def parse(self, trigger_event):
        print("You clicked with event = {}".format(trigger_event))

Comparing the following two ways of coding a button click:

btn = Button(root, text="Click me to submit", command=(lambda: reply(ent.get())))
btn = Button(root, text="Click me to submit")
btn.bind('<Button-1>', (lambda event: reply(ent.get(), e=event)))
def reply(name, e = None):
    messagebox.showinfo(title="Reply", message = "Hello {0}!\nevent = {1}".format(name, e))

The first one is using the command function which doesn't take an argument, so no event pass-in is possible. The second one is a bind function which can take an event pass-in and print something like "Hello Charles! event = [ButtonPress event state=Mod1 num=1 x=68 y=12]"

We can left click, middle click or right click a mouse which corresponds to the event number of 1, 2 and 3, respectively. Code:

btn = Button(root, text="Click me to submit")
buttonClicks = ["<Button-1>", "<Button-2>", "<Button-3>"]
for bc in buttonClicks:
    btn.bind(bc, lambda e : print("Button clicked with event = {}".format(e.num)))


Button clicked with event = 1
Button clicked with event = 2
Button clicked with event = 3

Is there an onSelect event or equivalent for HTML <select>?

<select name="test[]" 
onchange="if(this.selectedIndex < 1){this.options[this.selectedIndex].selected = !1}">

php_network_getaddresses: getaddrinfo failed: Name or service not known

You cannot open a connection directly to a path on a remote host using fsockopen. The url contains a path, when the only valid value for that first parameter is the host,

If you are trying to access a remote URL, then file_get_contents() is your best bet. You can provide a full URL to that function, and it will fetch the content at that location using a normal HTTP request.

If you only want to send an HTTP request and ignore the response, you could use fsockopen() and manually send the HTTP request headers, ignoring any response. It might be easier with cURL though, or just plain old fopen(), which will open the connection but not necessarily read any response. If you wanted to do it with fsockopen(), it might look something like this:

$fp = fsockopen("", 80, $errno, $errstr, 30);
fputs($fp, "GET /1/file.php HTTP/1.1\n");
fputs($fp, "Host:\n");
fputs($fp, "Connection: close\n\n"); 

That leaves any error handling up to you of course, but it would mean that you wouldn't waste time reading the response.

How to extract svg as file from web page

1. Inspect the page with the svg on.

2. Click on the link that displays the imagine in full resolution.


4. You are done!

java.lang.OutOfMemoryError: Java heap space in Maven

The chances are that the problem is in one of the unit tests that you've asked Maven to run.

As such, fiddling with the heap size is the wrong approach. Instead, you should be looking at the unit test that has caused the OOME, and trying to figure out if it is the fault of the unit test or the code that it is testing.

Start by looking at the stack trace. If there isn't one, run mvn ... test again with the -e option.

How to detect Ctrl+V, Ctrl+C using JavaScript?

A hook that allows for overriding copy events, could be used for doing the same with paste events. The input element cannot be display: none; or visibility: hidden; sadly

export const useOverrideCopy = () => {
  const [copyListenerEl, setCopyListenerEl] = React.useState(
    null as HTMLInputElement | null
  const [, setCopyHandler] = React.useState<(e: ClipboardEvent) => void | null>(
    () => () => {}
  // appends a input element to the DOM, that will be focused.
  // when using copy/paste etc, it will target focused elements
  React.useEffect(() => {
    const el = document.createElement("input")  
    // cannot focus a element that is not "visible" aka cannot use display: none or visibility: hidden = "0" = "0" = "0" = "fixed" = "-20px"
    return () => {
  }, [])
  // adds a event listener for copying, and removes the old one 
  const overrideCopy = (newOverrideAction: () => any) => {
    setCopyHandler((prevCopyHandler: (e: ClipboardEvent) => void) => {
      const copyHandler = (e: ClipboardEvent) => {
      copyListenerEl?.removeEventListener("copy", prevCopyHandler)
      copyListenerEl?.addEventListener("copy", copyHandler)
      copyListenerEl?.focus() // when focused, all copy events will trigger listener above
      return copyHandler
  return { overrideCopy }

Used like this:

const customCopyEvent = () => {
    console.log("doing something")
const { overrideCopy } = useOverrideCopy()

Every time you call overrideCopy it will refocus and call your custom event on copy.

What is the difference between getText() and getAttribute() in Selenium WebDriver?

getText(): Get the visible (i.e. not hidden by CSS) innerText of this element, including sub-elements, without any leading or trailing whitespace.

getAttribute(String attrName): Get the value of a the given attribute of the element. Will return the current value, even if this has been modified after the page has been loaded. More exactly, this method will return the value of the given attribute, unless that attribute is not present, in which case the value of the property with the same name is returned (for example for the "value" property of a textarea element). If neither value is set, null is returned. The "style" attribute is converted as best can be to a text representation with a trailing semi-colon. The following are deemed to be "boolean" attributes, and will return either "true" or null: async, autofocus, autoplay, checked, compact, complete, controls, declare, defaultchecked, defaultselected, defer, disabled, draggable, ended, formnovalidate, hidden, indeterminate, iscontenteditable, ismap, itemscope, loop, multiple, muted, nohref, noresize, noshade, novalidate, nowrap, open, paused, pubdate, readonly, required, reversed, scoped, seamless, seeking, selected, spellcheck, truespeed, willvalidate Finally, the following commonly mis-capitalized attribute/property names are evaluated as expected: "class" "readonly"

getText() return the visible text of the element.

getAttribute(String attrName) returns the value of the attribute passed as parameter.

Change a Git remote HEAD to point to something besides master

Simple just log into your GitHub account and on the far right side in the navigation menu choose Settings, in the Settings Tab choose Default Branch and return back to main page of your repository that did the trick for me.

Base64 decode snippet in C++

I liked this solution on GitHub.

It is a single hpp file and it uses the vector<byte> type for raw data unlike the accepted answer.

#pragma once

#include <string>
#include <vector>
#include <stdexcept>
#include <cstdint>

namespace base64
    inline static const char kEncodeLookup[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
    inline static const char kPadCharacter = '=';

    using byte = std::uint8_t;

    inline std::string encode(const std::vector<byte>& input)
        std::string encoded;
        encoded.reserve(((input.size() / 3) + (input.size() % 3 > 0)) * 4);

        std::uint32_t temp{};
        auto it = input.begin();

        for(std::size_t i = 0; i < input.size() / 3; ++i)
            temp  = (*it++) << 16;
            temp += (*it++) << 8;
            temp += (*it++);
            encoded.append(1, kEncodeLookup[(temp & 0x00FC0000) >> 18]);
            encoded.append(1, kEncodeLookup[(temp & 0x0003F000) >> 12]);
            encoded.append(1, kEncodeLookup[(temp & 0x00000FC0) >> 6 ]);
            encoded.append(1, kEncodeLookup[(temp & 0x0000003F)      ]);

        switch(input.size() % 3)
        case 1:
            temp = (*it++) << 16;
            encoded.append(1, kEncodeLookup[(temp & 0x00FC0000) >> 18]);
            encoded.append(1, kEncodeLookup[(temp & 0x0003F000) >> 12]);
            encoded.append(2, kPadCharacter);
        case 2:
            temp  = (*it++) << 16;
            temp += (*it++) << 8;
            encoded.append(1, kEncodeLookup[(temp & 0x00FC0000) >> 18]);
            encoded.append(1, kEncodeLookup[(temp & 0x0003F000) >> 12]);
            encoded.append(1, kEncodeLookup[(temp & 0x00000FC0) >> 6 ]);
            encoded.append(1, kPadCharacter);

        return encoded;

    std::vector<byte> decode(const std::string& input)
        if(input.length() % 4)
            throw std::runtime_error("Invalid base64 length!");

        std::size_t padding{};

            if(input[input.length() - 1] == kPadCharacter) padding++;
            if(input[input.length() - 2] == kPadCharacter) padding++;

        std::vector<byte> decoded;
        decoded.reserve(((input.length() / 4) * 3) - padding);

        std::uint32_t temp{};
        auto it = input.begin();

        while(it < input.end())
            for(std::size_t i = 0; i < 4; ++i)
                temp <<= 6;
                if     (*it >= 0x41 && *it <= 0x5A) temp |= *it - 0x41;
                else if(*it >= 0x61 && *it <= 0x7A) temp |= *it - 0x47;
                else if(*it >= 0x30 && *it <= 0x39) temp |= *it + 0x04;
                else if(*it == 0x2B)                temp |= 0x3E;
                else if(*it == 0x2F)                temp |= 0x3F;
                else if(*it == kPadCharacter)
                    switch(input.end() - it)
                    case 1:
                        decoded.push_back((temp >> 16) & 0x000000FF);
                        decoded.push_back((temp >> 8 ) & 0x000000FF);
                        return decoded;
                    case 2:
                        decoded.push_back((temp >> 10) & 0x000000FF);
                        return decoded;
                        throw std::runtime_error("Invalid padding in base64!");
                else throw std::runtime_error("Invalid character in base64!");


            decoded.push_back((temp >> 16) & 0x000000FF);
            decoded.push_back((temp >> 8 ) & 0x000000FF);
            decoded.push_back((temp      ) & 0x000000FF);

        return decoded;

What is console.log in jQuery?

it will print log messages in your developer console (firebug/webkit dev tools/ie dev tools)

How to redirect docker container logs to a single file?

Since Docker merges stdout and stderr for us, we can treat the log output like any other shell stream. To redirect the current logs to a file, use a redirection operator

$ docker logs test_container > output.log
docker logs -f test_container > output.log

Instead of sending output to stderr and stdout, redirect your application’s output to a file and map the file to permanent storage outside of the container.

$ docker logs test_container> /tmp/output.log

Docker will not accept relative paths on the command line, so if you want to use a different directory, you’ll need to use the complete path.

How to set the focus for a particular field in a Bootstrap modal, once it appears

I had the same problem with the bootstrap 3 and solved like this:

$('#myModal').on('', function (e) {


Tools to get a pictorial function call graph of code

Dynamic analysis methods

Here I describe a few dynamic analysis methods.

Dynamic methods actually run the program to determine the call graph.

The opposite of dynamic methods are static methods, which try to determine it from the source alone without running the program.

Advantages of dynamic methods:

  • catches function pointers and virtual C++ calls. These are present in large numbers in any non-trivial software.

Disadvantages of dynamic methods:

  • you have to run the program, which might be slow, or require a setup that you don't have, e.g. cross-compilation
  • only functions that were actually called will show. E.g., some functions could be called or not depending on the command line arguments.


Test program:

int f2(int i) { return i + 2; }
int f1(int i) { return f2(2) + i + 1; }
int f0(int i) { return f1(1) + f2(2); }
int pointed(int i) { return i; }
int not_called(int i) { return 0; }

int main(int argc, char **argv) {
    int (*f)(int);
    f = pointed;
    if (argc == 1)
    if (argc == 2)
    return 0;


sudo apt-get install -y kcachegrind valgrind

# Compile the program as usual, no special flags.
gcc -ggdb3 -O0 -o main -std=c99 main.c

# Generate a callgrind.out.<PID> file.
valgrind --tool=callgrind ./main

# Open a GUI tool to visualize callgrind data.
kcachegrind callgrind.out.1234

You are now left inside an awesome GUI program that contains a lot of interesting performance data.

On the bottom right, select the "Call graph" tab. This shows an interactive call graph that correlates to performance metrics in other windows as you click the functions.

To export the graph, right click it and select "Export Graph". The exported PNG looks like this:

From that we can see that:

  • the root node is _start, which is the actual ELF entry point, and contains glibc initialization boilerplate
  • f0, f1 and f2 are called as expected from one another
  • pointed is also shown, even though we called it with a function pointer. It might not have been called if we had passed a command line argument.
  • not_called is not shown because it didn't get called in the run, because we didn't pass an extra command line argument.

The cool thing about valgrind is that it does not require any special compilation options.

Therefore, you could use it even if you don't have the source code, only the executable.

valgrind manages to do that by running your code through a lightweight "virtual machine". This also makes execution extremely slow compared to native execution.

As can be seen on the graph, timing information about each function call is also obtained, and this can be used to profile the program, which is likely the original use case of this setup, not just to see call graphs: How can I profile C++ code running on Linux?

Tested on Ubuntu 18.04.

gcc -finstrument-functions + etrace

-finstrument-functions adds callbacks, etrace parses the ELF file and implements all callbacks.

I couldn't get it working however unfortunately: Why doesn't `-finstrument-functions` work for me?

Claimed output is of format:

\-- main
|   \-- Crumble_make_apple_crumble
|   |   \-- Crumble_buy_stuff
|   |   |   \-- Crumble_buy
|   |   |   \-- Crumble_buy
|   |   |   \-- Crumble_buy
|   |   |   \-- Crumble_buy
|   |   |   \-- Crumble_buy
|   |   \-- Crumble_prepare_apples
|   |   |   \-- Crumble_skin_and_dice
|   |   \-- Crumble_mix
|   |   \-- Crumble_finalize
|   |   |   \-- Crumble_put
|   |   |   \-- Crumble_put
|   |   \-- Crumble_cook
|   |   |   \-- Crumble_put
|   |   |   \-- Crumble_bake

Likely the most efficient method besides specific hardware tracing support, but has the downside that you have to recompile the code.

Disable pasting text into HTML form

You could attach a "keydown" listener to the input box to detect whether or not the Ctrl + V keys are being pressed and, if so, stop the event or set the input box's value to ''.

That wouldn't handle right clicking and pasting or pasting from the Edit menu of the browser, though. You may need to add a "last length" counter to the keydown listener and use an interval to check the field's current length to see if it increase since the last keystroke.

Neither is recommended, though. Form fields with paste disabled are extremely frustrating. I'm capable of typing my email correctly the first time, so I reserve the right to paste it into the second box.

window.print() not working in IE

I was told to do document.close after document.write, I dont see how or why but this caused my script to wait until I closed the print dialog before it ran my window.close.

var printContent = document.getElementbyId('wrapper').innerHTML;
var disp_setting="toolbar=no,location=no,directories=no,menubar=no, scrollbars=no,width=600, height=825, left=100, top=25"
var printWindow ="","",disp_setting);


Insert multiple lines into a file after specified pattern using shell script

Another sed,

sed '/cdef/r add.txt' input.txt






sat:~# sed '/cdef/r add.txt' input.txt

If you want to apply the changes in input.txt file. Then, use -i with sed.

sed -i '/cdef/r add.txt' input.txt

If you want to use a regex as an expression you have to use the -E tag with sed.

sed -E '/RegexPattern/r add.txt' input.txt

How can I match multiple occurrences with a regex in JavaScript similar to PHP's preg_match_all()?

2020 edit

Use URLSearchParams, as this job no longer requires any kind of custom code. Browsers can do this for you with a single constructor:

const str = "1111342=Adam%20Franco&348572=Bob%20Jones";
const data = new URLSearchParams(str);
for (pair of data) console.log(pair)


Array [ "1111342", "Adam Franco" ]
Array [ "348572", "Bob Jones" ]

So there is no reason to use regex for this anymore.

Original answer

If you don't want to rely on the "blind matching" that comes with running exec style matching, JavaScript does come with match-all functionality built in, but it's part of the replace function call, when using a "what to do with the capture groups" handling function:

var data = {};

var getKeyValue = function(fullPattern, group1, group2, group3) {
  data[group2] = group3;

mystring.replace(/(?:&|&amp;)?([^=]+)=([^&]+)/g, getKeyValue);


Instead of using the capture group handling function to actually return replacement strings (for replace handling, the first arg is the full pattern match, and subsequent args are individual capture groups) we simply take the groups 2 and 3 captures, and cache that pair.

So, rather than writing complicated parsing functions, remember that the "matchAll" function in JavaScript is simply "replace" with a replacement handler function, and much pattern matching efficiency can be had.

Could not load file or assembly 'Microsoft.Web.Infrastructure,

On my machine the Nuget dependency wasn't downloaded correctly, the lib folder inside the nuget package didn't exist, hence the error.


enter image description here

I renamed the Nuget Package in the packages folder and Nuget redownloaded it correctly with the necessary lib folder.

After enter image description here

how to download file in react js

We can user react-download-link component to download content as File.

exportFile={() => "Client side cache data here…"}/>

Spark Dataframe distinguish columns with duplicated name

If you have a more complicated use case than described in the answer of Glennie Helles Sindholt e.g. you have other/few non-join column names that are also same and want to distinguish them while selecting it's best to use aliasses, e.g:

df3 ="a", "b").alias("left")\
   .join("a", "b").alias("right"), ["a"])\
   .select("left.a", "left.b", "right.b")

['a', 'b', 'b']

Get bottom and right position of an element

// Returns bottom offset value + or - from viewport top
function offsetBottom(el, i) { i = i || 0; return $(el)[i].getBoundingClientRect().bottom }

// Returns right offset value
function offsetRight(el, i) { i = i || 0; return $(el)[i].getBoundingClientRect().right }

var bottom = offsetBottom('#logo');
var right = offsetRight('#logo');

This will find the distance from the top and left of your viewport to your element's exact edge and nothing beyond that. So say your logo was 350px and it had a left margin of 50px, variable 'right' will hold a value of 400 because that's the actual distance in pixels it took to get to the edge of your element, no matter if you have more padding or margin to the right of it.

If your box-sizing CSS property is set to border-box it will continue to work just as if it were set as the default content-box.

How to get an Instagram Access Token

The easy way that works in 2019

Disable implicit oauth under the security auth and THEN load this:

Specify REDIRECT-URI in your account and type it exactly as specified.

Creating lowpass filter in SciPy - understanding methods and units

A few comments:

  • The Nyquist frequency is half the sampling rate.
  • You are working with regularly sampled data, so you want a digital filter, not an analog filter. This means you should not use analog=True in the call to butter, and you should use scipy.signal.freqz (not freqs) to generate the frequency response.
  • One goal of those short utility functions is to allow you to leave all your frequencies expressed in Hz. You shouldn't have to convert to rad/sec. As long as you express your frequencies with consistent units, the scaling in the utility functions takes care of the normalization for you.

Here's my modified version of your script, followed by the plot that it generates.

import numpy as np
from scipy.signal import butter, lfilter, freqz
import matplotlib.pyplot as plt

def butter_lowpass(cutoff, fs, order=5):
    nyq = 0.5 * fs
    normal_cutoff = cutoff / nyq
    b, a = butter(order, normal_cutoff, btype='low', analog=False)
    return b, a

def butter_lowpass_filter(data, cutoff, fs, order=5):
    b, a = butter_lowpass(cutoff, fs, order=order)
    y = lfilter(b, a, data)
    return y

# Filter requirements.
order = 6
fs = 30.0       # sample rate, Hz
cutoff = 3.667  # desired cutoff frequency of the filter, Hz

# Get the filter coefficients so we can check its frequency response.
b, a = butter_lowpass(cutoff, fs, order)

# Plot the frequency response.
w, h = freqz(b, a, worN=8000)
plt.subplot(2, 1, 1)
plt.plot(0.5*fs*w/np.pi, np.abs(h), 'b')
plt.plot(cutoff, 0.5*np.sqrt(2), 'ko')
plt.axvline(cutoff, color='k')
plt.xlim(0, 0.5*fs)
plt.title("Lowpass Filter Frequency Response")
plt.xlabel('Frequency [Hz]')

# Demonstrate the use of the filter.
# First make some data to be filtered.
T = 5.0         # seconds
n = int(T * fs) # total number of samples
t = np.linspace(0, T, n, endpoint=False)
# "Noisy" data.  We want to recover the 1.2 Hz signal from this.
data = np.sin(1.2*2*np.pi*t) + 1.5*np.cos(9*2*np.pi*t) + 0.5*np.sin(12.0*2*np.pi*t)

# Filter the data, and plot both the original and filtered signals.
y = butter_lowpass_filter(data, cutoff, fs, order)

plt.subplot(2, 1, 2)
plt.plot(t, data, 'b-', label='data')
plt.plot(t, y, 'g-', linewidth=2, label='filtered data')
plt.xlabel('Time [sec]')


lowpass example

Offset a background image from the right using CSS

Outdated answer: It is now implemented in major browsers, see the other answers to this question.

CSS3 has modified the specification of background-position so that it will work with different origin point. Unfortunately, I can't find any evidence that it is implemented yet in any major browsers. See example 12.

background-position: right 3em bottom 10px;

Convert PDF to image with high resolution

In ImageMagick, you can do "supersampling". You specify a large density and then resize down as much as desired for the final output size. For example with your image:

convert -density 600 test.pdf -background white -flatten -resize 25% test.png

enter image description here

Download the image to view at full resolution for comparison..

I do not recommend saving to JPG if you are expecting to do further processing.

If you want the output to be the same size as the input, then resize to the inverse of the ratio of your density to 72. For example, -density 288 and -resize 25%. 288=4*72 and 25%=1/4

The larger the density the better the resulting quality, but it will take longer to process.

How to colorize diff on the command line?

Use Vim:

diff /path/to/a /path/to/b | vim -R -

Or better still, VimDiff (or vim -d, which is shorter to type) will show differences between two, three or four files side-by-side.


vim -d /path/to/[ab]

vimdiff file1 file2 file3 file4

Get Windows version in a batch file

I know it's an old question but I thought these were useful enough to put here for people searching.

This first one is a simple batch way to get the right version. You can find out if it is Server or Workstation (if that's important) in another process. I just didn't take time to add it.

We use this structure inside code to ensure compliance with requirements. I'm sure there are many more graceful ways but this does always work.

:: -------------------------------------
:: Check Windows Version
:: 5.0 = W2K
:: 5.1 = XP
:: 5.2 = Server 2K3
:: 6.0 = Vista or Server 2K8
:: 6.1 = Win7 or Server 2K8R2
:: 6.2 = Win8 or Server 2K12
:: 6.3 = Win8.1 or Server 2K12R2
:: 0.0 = Unknown or Unable to determine
:: --------------------------------------
echo OS Detection:  Starting

ver | findstr /i "5\.0\."
echo  OS = Windows 2000
ver | findstr /i "5\.1\."
echo OS = Windows XP
ver | findstr /i "5\.2\."
echo OS = Server 2003
ver | findstr /i "6\.0\." > nul
echo OS = Vista / Server 2008
ver | findstr /i "6\.1\." > nul
echo OS = Windows 7 / Server 2008R2
ver | findstr /i "6\.2\." > nul
echo OS = Windows 8 / Server 2012
ver | findstr /i "6\.3\." > nul
echo OS = Windows 8.1 / Server 2012R2

This second one isn't what was asked for but it may be useful for someone looking.

Here is a VBscript function that provides version info, including if it is the Server (vs. workstation).

private function GetOSVer()

    dim strOsName:    strOsName = ""
    dim strOsVer:     strOsVer = ""
    dim strOsType:    strOsType = ""

    Set objWMIService = GetObject("winmgmts:" & "{impersonationLevel=impersonate}!\\.\root\cimv2") 
    Set colOSes = objWMIService.ExecQuery("Select * from Win32_OperatingSystem") 
    For Each objOS in colOSes 
        strOsName = objOS.Caption
        strOsVer = left(objOS.Version, 3)
        Select Case strOsVer
            case "5.0"    'Windows 2000
                if instr(strOsName, "Server") then
                    strOsType = "W2K Server"
                    strOsType = "W2K Workstation"
                end if
            case "5.1"    'Windows XP 32bit
                    strOsType = "XP 32bit"
            case "5.2"    'Windows 2003, 2003R2, XP 64bit
                if instr(strOsName, "XP") then
                    strOsType = "XP 64bit"
                elseif instr(strOsName, "R2") then
                    strOsType = "W2K3R2 Server"
                    strOsType = "W2K3 Server"
                end if
            case "6.0"    'Vista, Server 2008
                if instr(strOsName, "Server") then
                    strOsType = "W2K8 Server"
                    strOsType = "Vista"
                end if
            case "6.1"    'Server 2008R2, Win7
                if instr(strOsName, "Server") then
                    strOsType = "W2K8R2 Server"
                    strOsType = "Win7"
                end if
            case "6.2"    'Server 2012, Win8
                if instr(strOsName, "Server") then
                    strOsType = "W2K12 Server"
                    strOsType = "Win8"
                end if
            case "6.3"    'Server 2012R2, Win8.1
                if instr(strOsName, "Server") then
                    strOsType = "W2K12R2 Server"
                    strOsType = "Win8.1"
                end if
            case else    'Unknown OS
                strOsType = "Unknown"
        end select
    GetOSVer = strOsType
end Function     'GetOSVer

Get a file name from a path

Dont use _splitpath() and _wsplitpath(). They are not safe, and they are obsolete!

Instead, use their safe versions, namely _splitpath_s() and _wsplitpath_s()

Initializing array of structures

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

jQuery used to ONLY have the callback functions for success and error and complete.

Then, they decided to support promises with the jqXHR object and that's when they added .done(), .fail(), .always(), etc... in the spirit of the promise API. These new methods serve much the same purpose as the callbacks but in a different form. You can use whichever API style works better for your coding style.

As people get more and more familiar with promises and as more and more async operations use that concept, I suspect that more and more people will move to the promise API over time, but in the meantime jQuery supports both.

The .success() method has been deprecated in favor of the common promise object method names.

From the jQuery doc, you can see how various promise methods relate to the callback types:

jqXHR.done(function( data, textStatus, jqXHR ) {}); An alternative construct to the success callback option, the .done() method replaces the deprecated jqXHR.success() method. Refer to deferred.done() for implementation details. jqXHR, textStatus, errorThrown ) {}); An alternative construct to the error callback option, the .fail() method replaces the deprecated .error() method. Refer to for implementation details.

jqXHR.always(function( data|jqXHR, textStatus, jqXHR|errorThrown ) { }); An alternative construct to the complete callback option, the .always() method replaces the deprecated .complete() method.

In response to a successful request, the function's arguments are the same as those of .done(): data, textStatus, and the jqXHR object. For failed requests the arguments are the same as those of .fail(): the jqXHR object, textStatus, and errorThrown. Refer to deferred.always() for implementation details.

jqXHR.then(function( data, textStatus, jqXHR ) {}, function( jqXHR, textStatus, errorThrown ) {}); Incorporates the functionality of the .done() and .fail() methods, allowing (as of jQuery 1.8) the underlying Promise to be manipulated. Refer to deferred.then() for implementation details.

If you want to code in a way that is more compliant with the ES6 Promises standard, then of these four options you would only use .then().

How to wrap text using CSS?



I have taken my example from a couple different websites on google. I have tested this on ff 5.0, IE 8.0, and Chrome 10. It works on all of them.

.wrapword {
    white-space: -moz-pre-wrap !important;  /* Mozilla, since 1999 */
    white-space: -pre-wrap;      /* Opera 4-6 */
    white-space: -o-pre-wrap;    /* Opera 7 */
    white-space: pre-wrap;       /* css-3 */
    word-wrap: break-word;       /* Internet Explorer 5.5+ */
    white-space: -webkit-pre-wrap; /* Newer versions of Chrome/Safari*/
    word-break: break-all;
    white-space: normal;

<table style="table-layout:fixed; width:400px">
        <td class="wrapword"></td>

How to make a button redirect to another page using jQuery or just Javascript

You can use this simple JavaScript code to make search button to link to a sample search results page. Here I have redirected to '/search' of my home page, If you want to search from Google search engine, You can use "" in form action.

<form action="/search"> Enter your search text: 
<input type="text" id="searchtext" name="q"> &nbsp;
<input onclick="myFunction()" type="submit" value="Search It" />
<script> function myFunction() 
var search = document.getElementById("searchtext").value; 
window.location = '/search?q='+search; 

java build path problems

Here's a good discussion on this:

Basically you should

  1. Download and install the 1.5 JDK. (download link)
  2. In Eclipse, Go to Window ? Preferences ? Java ? Installed JREs.
  3. Add the 1.5 JDK to the list.
  4. Select 1.5 as Compiler Compliance Level.

Add new column with foreign key constraint in one command


With user defined foreign key name

ADD columnName dataType,
   REFERENCES pkTableName(pkTableColumnName);

Without user defined foreign key name

ADD columnName dataType,
FOREIGN KEY(fkColumnName) REFERENCES pkTableName(pkTableColumnName);

How to roundup a number to the closest ten?

Use ROUND but with num_digits = -1


Also applies to ROUNDUP and ROUNDDOWN

From Excel help:

  • If num_digits is greater than 0 (zero), then number is rounded to the specified number of decimal places.
  • If num_digits is 0, then number is rounded to the nearest integer.
  • If num_digits is less than 0, then number is rounded to the left of the decimal point.

EDIT: To get the numbers to always round up use =ROUNDUP(A1,-1)

What is the difference between "is None" and "== None"

The answer is explained here.

To quote:

A class is free to implement comparison any way it chooses, and it can choose to make comparison against None mean something (which actually makes sense; if someone told you to implement the None object from scratch, how else would you get it to compare True against itself?).

Practically-speaking, there is not much difference since custom comparison operators are rare. But you should use is None as a general rule.

How to export data from Excel spreadsheet to Sql Server 2008 table

There are several tools which can import Excel to SQL Server.

I am using DbTransfer ( to do the job. It's primarily focused on transfering data between databases and excel, xml, etc...

I have tried the openrowset method and the SQL Server Import / Export Assitant before. But I found these methods to be unnecessary complicated and error prone in constrast to doing it with one of the available dedicated tools.

How to abort an interactive rebase if --abort doesn't work?

Try to follow the advice you see on the screen, and first reset your master's HEAD to the commit it expects.

git update-ref refs/heads/master b918ac16a33881ce00799bea63d9c23bf7022d67

Then, abort the rebase again.

Convert a list to a string in C#

The direct answer to your question is String.Join as others have mentioned.

However, if you need some manipulations, you can use Aggregate:

List<string> employees = new List<string>();

string employeesString = "'" + employees.Aggregate((x, y) => x + "','" + y) + "'";

How do I 'overwrite', rather than 'merge', a branch on another branch in Git?

If you're like me and you don't want to deal with merging, you can do the above steps, except use force instead of merge, because it will create a distracting log paper trail:

git checkout email
git reset --hard staging
git push origin email --force

Note: This is only if you REALLY never want to see the stuff in email again.

How to declare a inline object with inline variables without a parent class

You can also declare 'x' with the keyword var:

var x = new
  driver = new
    firstName = "john",
    lastName = "walter"
  car = new
    brand = "BMW"

This will allow you to declare your x object inline, but you will have to name your 2 anonymous objects, in order to access them. You can have an array of "x" :

x.driver.firstName // "john" // "BMW"

var y = new[] { x, x, x, x };
y[1].car.brand; // "BMW"

More Pythonic Way to Run a Process X Times


for _ in range(50):
    print "Some thing"

if you don't need i. If you use Python < 3 and you want to repeat the loop a lot of times, use xrange as there is no need to generate the whole list beforehand.

How do I grep recursively?

Just for fun, a quick and dirty search of *.txt files if the @christangrant answer is too much to type :-)

grep -r texthere .|grep .txt

Convert char array to single int?

Long story short you have to use atoi()


If you are interested in doing this the right way :

char szNos[] = "12345";
char *pNext;
long output;
output = strtol (szNos, &pNext, 10); // input, ptr to next char in szNos (null here), base 

Can I get "&&" or "-and" to work in PowerShell?

&& and || were on the list of things to implement (still are) but did not pop up as the next most useful thing to add. The reason is that we have -AND and -OR. If you think it is important, please file a suggestion on Connect and we'll consider it for V3.

Getting value of select (dropdown) before change

Use following code,I have tested it and its working

var prev_val;
$('.dropdown').focus(function() {
    prev_val = $(this).val();
            var conf = confirm('Are you sure want to change status ?');

            if(conf == true){
                //your code
                return false;

How to serve an image using nodejs

var http = require('http');
var fs = require('fs');

http.createServer(function(req, res) {
console.log('server running at 3000');

"NODE_ENV" is not recognized as an internal or external command, operable command or batch file

For those who uses Git Bash and having issues with npm run <script>,

Just set npm to use Git Bash to run scripts

npm config set script-shell "C:\\Program Files\\git\\bin\\bash.exe" (change the path according to your installation)

And then npm will run scripts with Git Bash, so such usages like NODE_ENV= will work properly.

Setting transparent images background in IrfanView

If you are using the batch conversion, in the window click "options" in the "Batch conversion settings-output format" and tick the two boxes "save transparent color" (one under "PNG" and the other under "ICO").

Set the selected index of a Dropdown using jQuery

Just found this, it works for me and I personally find it easier to read.

This will set the actual index just like gnarf's answer number 3 option.

// sets selected index of a select box the actual index of 0 
$("select#elem").attr('selectedIndex', 0);

This didn't used to work but does now... see bug:


As recommended in the comments use :

$("select#elem").prop('selectedIndex', 0);

XXHDPI and XXXHDPI dimensions in dp for images and icons in android

it is different for different icons.(eg, diff sizes for action bar icons, laucnher icons, etc.) please follow this link icons handbook to learn more.

How to use timeit module

for me, this is the fastest way:

import timeit
def foo():
    print("here is my code to time...")

timeit.timeit(stmt=foo, number=1234567)

How to increase request timeout in IIS?

In IIS >= 7, a <webLimits> section has replaced ConnectionTimeout, HeaderWaitTimeout, MaxGlobalBandwidth, and MinFileBytesPerSec IIS 6 metabase settings.

Example Configuration:

      <webLimits connectionTimeout="00:01:00"

For reference: more information regarding these settings in IIS can be found here. Also, I was unable to add this section to the web.config via the IIS manager's "configuration editor", though it did show up once I added it and searched the configuration.

Is "delete this" allowed in C++?

Delete this is legal as long as object is in heap. You would need to require object to be heap only. The only way to do that is to make the destructor protected - this way delete may be called ONLY from class , so you would need a method that would ensure deletion

How to measure the a time-span in seconds using System.currentTimeMillis()?

long start = System.currentTimeMillis();
long end = System.currentTimeMillis();

System.out.println("Took : " + ((end - start) / 1000));


An even more accurate solution would be:

final long start = System.nanoTime();
final long end = System.nanoTime();

System.out.println("Took: " + ((end - start) / 1000000) + "ms");
System.out.println("Took: " + (end - start)/ 1000000000 + " seconds");

Creating an empty Pandas DataFrame, then filling it?

NEVER grow a DataFrame!

TLDR; (just read the bold text)

Most answers here will tell you how to create an empty DataFrame and fill it out, but no one will tell you that it is a bad thing to do.

Here is my advice: Accumulate data in a list, not a DataFrame.

Use a list to collect your data, then initialise a DataFrame when you are ready. Either a list-of-lists or list-of-dicts format will work, pd.DataFrame accepts both.

data = []
for a, b, c in some_function_that_yields_data():
    data.append([a, b, c])

df = pd.DataFrame(data, columns=['A', 'B', 'C'])

Pros of this approach:

  1. It is always cheaper to append to a list and create a DataFrame in one go than it is to create an empty DataFrame (or one of NaNs) and append to it over and over again.

  2. Lists also take up less memory and are a much lighter data structure to work with, append, and remove (if needed).

  3. dtypes are automatically inferred (rather than assigning object to all of them).

  4. A RangeIndex is automatically created for your data, instead of you having to take care to assign the correct index to the row you are appending at each iteration.

If you aren't convinced yet, this is also mentioned in the documentation:

Iteratively appending rows to a DataFrame can be more computationally intensive than a single concatenate. A better solution is to append those rows to a list and then concatenate the list with the original DataFrame all at once.

But what if my function returns smaller DataFrames that I need to combine into one large DataFrame?

That's fine, you can still do this in linear time by growing or creating a python list of smaller DataFrames, then calling pd.concat.

small_dfs = []
for small_df in some_function_that_yields_dataframes():

large_df = pd.concat(small_dfs, ignore_index=True)

or, more concisely:

large_df = pd.concat(
    list(some_function_that_yields_dataframes()), ignore_index=True)

These options are horrible

append or concat inside a loop

Here is the biggest mistake I've seen from beginners:

df = pd.DataFrame(columns=['A', 'B', 'C'])
for a, b, c in some_function_that_yields_data():
    df = df.append({'A': i, 'B': b, 'C': c}, ignore_index=True) # yuck
    # or similarly,
    # df = pd.concat([df, pd.Series({'A': i, 'B': b, 'C': c})], ignore_index=True)

Memory is re-allocated for every append or concat operation you have. Couple this with a loop and you have a quadratic complexity operation.

The other mistake associated with df.append is that users tend to forget append is not an in-place function, so the result must be assigned back. You also have to worry about the dtypes:

df = pd.DataFrame(columns=['A', 'B', 'C'])
df = df.append({'A': 1, 'B': 12.3, 'C': 'xyz'}, ignore_index=True)

A     object   # yuck!
B    float64
C     object
dtype: object

Dealing with object columns is never a good thing, because pandas cannot vectorize operations on those columns. You will need to do this to fix it:

A      int64
B    float64
C     object
dtype: object

loc inside a loop

I have also seen loc used to append to a DataFrame that was created empty:

df = pd.DataFrame(columns=['A', 'B', 'C'])
for a, b, c in some_function_that_yields_data():
    df.loc[len(df)] = [a, b, c]

As before, you have not pre-allocated the amount of memory you need each time, so the memory is re-grown each time you create a new row. It's just as bad as append, and even more ugly.

Empty DataFrame of NaNs

And then, there's creating a DataFrame of NaNs, and all the caveats associated therewith.

df = pd.DataFrame(columns=['A', 'B', 'C'], index=range(5))
     A    B    C
0  NaN  NaN  NaN
1  NaN  NaN  NaN
2  NaN  NaN  NaN
3  NaN  NaN  NaN
4  NaN  NaN  NaN

It creates a DataFrame of object columns, like the others.

A    object  # you DON'T want this
B    object
C    object
dtype: object

Appending still has all the issues as the methods above.

for i, (a, b, c) in enumerate(some_function_that_yields_data()):
    df.iloc[i] = [a, b, c]

The Proof is in the Pudding

Timing these methods is the fastest way to see just how much they differ in terms of their memory and utility.

enter image description here

Benchmarking code for reference.

How to convert Base64 String to javascript file object like as from file input form?

Heads up,


   function readMtlAtClient(){

       mtlFileContent = '';

       var mtlFile = document.getElementById('mtlFileInput').files[0];
       var readerMTL = new FileReader();

       // Closure to capture the file information.
       readerMTL.onload = (function(reader) {
           return function() {
               mtlFileContent = reader.result;
               mtlFileContent = mtlFileContent.replace('data:;base64,', '');
               mtlFileContent = window.atob(mtlFileContent);




    <input class="FullWidth" type="file" name="mtlFileInput" value="" id="mtlFileInput" 
onchange="readMtlAtClient()" accept=".mtl"/>

Then mtlFileContent has your text as a decoded string !

Can I install/update WordPress plugins without providing FTP access?

The only reason by which WordPress won't allow you to upload any plugin via WordPress admin dashboard when you don't got permission to write on the /wp-content directory. Remember that your wordpress directory /wp-content requires 0755 permission level. There are various ways to change a folder's permission level.

Changing file permissions using cPanel:

Go to File Manager at open the public HTML folder where your wordpress website is supposed to be, or open the site root directory if your website is in some other folder. In your WordPress root directory navigate towards wp-content folder; at the end of wp-content folder row the very last box carries file permissions for this folder. Make sure to edit the folder permission level to 0755, and you are done.

Changing file permissions using SSH terminal:

In your terminal locate the root of WordPress site which in my case was /var/www/html so to move into WordPress root directory enter the following command:

cd /var/www/html 

Now you are in WordPress root directory where the required folder /wp-content is located. So to change the file permissions type the following command:

sudo chmod wp-content 755 

This will change your /wp-content directory file permission to 0755.

Now you won't get error message of uploading wordpress plugins via FTP.

Regular expression to remove HTML tags from a string

You could do it with jsoup

Whitelist whitelist = Whitelist.none();
String cleanStr = Jsoup.clean(yourText, whitelist);

VBA equivalent to Excel's mod function

In vba the function is MOD. e.g

 5 MOD 2

Here is a useful link.

How to set up devices for VS Code for a Flutter emulator

you can use 'Android iOS Emulator' plugin and Add the Android Studio emulator script to your settings in Visual Studio Code:

Mac: emulator.emulatorPath": "~/Library/Android/sdk/tools/emulator

Windows: emulator.emulatorPath": "<your android home>\\Sdk\\emulator\\emulator.exe

Linux: emulator.emulatorPath": "~/Documents/SDK/tools

Your visual studio code settings are found here: File -> Preferences -> Setting -> User Setting -> Extensions -> Emulator Configuration. Open command pallete Cmd-Shift-P -> Type Emulator

How to redirect stderr to null in cmd.exe

Your DOS command 2> nul

Read page Using command redirection operators. Besides the "2>" construct mentioned by Tanuki Software, it lists some other useful combinations.

How to build x86 and/or x64 on Windows from command line with CMAKE?

This cannot be done with CMake. You have to generate two separate build folders. One for the x86 NMake build and one for the x64 NMake build. You cannot generate a single Visual Studio project covering both architectures with CMake, either.

To build Visual Studio projects from the command line for both 32-bit and 64-bit without starting a Visual Studio command prompt, use the regular Visual Studio generators.

For CMake 3.13 or newer, run the following commands:

cmake -G "Visual Studio 16 2019" -A Win32 -S \path_to_source\ -B "build32"
cmake -G "Visual Studio 16 2019" -A x64 -S \path_to_source\ -B "build64"
cmake --build build32 --config Release
cmake --build build64 --config Release

For earlier versions of CMake, run the following commands:

mkdir build32 & pushd build32
cmake -G "Visual Studio 15 2017" \path_to_source\
mkdir build64 & pushd build64
cmake -G "Visual Studio 15 2017 Win64" \path_to_source\
cmake --build build32 --config Release
cmake --build build64 --config Release

CMake generated projects that use one of the Visual Studio generators can be built from the command line with using the option --build followed by the build directory. The --config option specifies the build configuration.

How to trigger a build only if changes happen on particular set of files

The Git plugin has an option (excluded region) to use regexes to determine whether to skip building based on whether files in the commit match the excluded region regex.

Unfortunately, the stock Git plugin does not have a "included region" feature at this time (1.15). However, someone posted patches on GitHub that work on Jenkins and Hudson that implement the feature you want.

It is a little work to build, but it works as advertised and has been extremely useful since one of my Git trees has multiple independent projects.

Update: The Git plugin (1.16) now has the 'included' region feature.

exporting multiple modules in react.js

When you

import App from './App.jsx';

That means it will import whatever you export default. You can rename App class inside App.jsx to whatever you want as long as you export default it will work but you can only have one export default.

So you only need to export default App and you don't need to export the rest.

If you still want to export the rest of the components, you will need named export.

Which rows are returned when using LIMIT with OFFSET in MySQL?

It will return 18 results starting on record #9 and finishing on record #26.

Start by reading the query from offset. First you offset by 8, which means you skip the first 8 results of the query. Then you limit by 18. Which means you consider records 9, 10, 11, 12, 13, 14, 15, 16....24, 25, 26 which are a total of 18 records.

Check this out.

And also the official documentation.

How to concatenate strings in a Windows batch file?

What about:

@echo off
set myvar="the list: "
for /r %%i in (*.doc) DO call :concat %%i
echo %myvar%
goto :eof

set myvar=%myvar% %1;
goto :eof

JavaScript Infinitely Looping slideshow with delays?

try this:

window.onload = function start() {
function slide() {

setInterval is basically an 'infinite loop' and it wont black up the browser. it waits the required time, then goes again

'Operation is not valid due to the current state of the object' error during postback

Somebody posted quite a few form fields to your page. The new default max introduced by the recent security update is 1000.

Try adding the following setting in your web.config's <appsettings> block. in this block you are maximizing the MaxHttpCollection values this will override the defaults set by .net Framework. you can change the value accordingly as per your form needs

    <add key="aspnet:MaxHttpCollectionKeys" value="2001" />

For more information please read this post. For more insight into the security patch by microsoft you can read this Knowledge base article

Is iterating ConcurrentHashMap values thread safe?

It means that you should not share an iterator object among multiple threads. Creating multiple iterators and using them concurrently in separate threads is fine.

How to add buttons dynamically to my form?

It doesn't work because the list is empty. Try this:

private void button1_Click(object sender, EventArgs e)
    List<Button> buttons = new List<Button>();
    for (int i = 0; i < 10; i++)
        Button newButton = new Button();

Are table names in MySQL case sensitive?

In general:

Database and table names are not case sensitive in Windows, and case sensitive in most varieties of Unix.

In MySQL, databases correspond to directories within the data directory. Each table within a database corresponds to at least one file within the database directory. Consequently, the case sensitivity of the underlying operating system plays a part in the case sensitivity of database and table names.

One can configure how tables names are stored on the disk using the system variable lower_case_table_names (in the my.cnf configuration file under [mysqld]).

Read the section: 10.2.2 Identifier Case Sensitivity for more information.

simple Jquery hover enlarge

If you have more than 1 image on the page that you like to enlarge, name the id's for instance "content1", "content2", "content3", etc. Then extend the script with this, like so:

$(document).ready(function() {
    $("[id^=content]").hover(function() {
    }, function() {

Edit: Change the "#content" CSS to: img[id^=content] to remain having the transition effects.

How to make my font bold using css?

You'd use font-weight: bold.

Do you want to make the entire document bold? Or just parts of it?

How do you specifically order ggplot2 x axis instead of alphabetical order?

The accepted answer offers a solution which requires changing of the underlying data frame. This is not necessary. One can also simply factorise within the aes() call directly or create a vector for that instead.

This is certainly not much different than user Drew Steen's answer, but with the important difference of not changing the original data frame.

level_order <- c('virginica', 'versicolor', 'setosa') #this vector might be useful for other plots/analyses

ggplot(iris, aes(x = factor(Species, level = level_order), y = Petal.Width)) + geom_col()


level_order <- factor(iris$Species, level = c('virginica', 'versicolor', 'setosa'))

ggplot(iris, aes(x = level_order, y = Petal.Width)) + geom_col()

directly in the aes() call without a pre-created vector:

ggplot(iris, aes(x = factor(Species, level = c('virginica', 'versicolor', 'setosa')), y = Petal.Width)) + geom_col()

that's for the first version

JavaScript vs for

Be careful!!! I am using Chrome 22.0 in Mac OS and I am having problem with the for each syntax.

I do not know if this is a browser issue, javascript issue or some error in the code, but it is VERY strange. Outside of the object it works perfectly.

var MyTest = {
    a:string = "a",
    b:string = "b"

myfunction = function(dicts) {
    for (var dict in dicts) {
        alert(typeof dict); // print 'string' (incorrect)

    for (var i = 0; i < dicts.length; i++) {
        alert(typeof dicts[i]); // print 'object' (correct, it must be {abc: "xyz"})

MyObj = function() { = function() {
new MyObj().aaa(); // This does not work

myfunction([MyTest]); // This works

nano error: Error opening terminal: xterm-256color

You can add the following in your .bashrc

if [ "$TERM" = xterm ]; then TERM=xterm-256color; fi

LINQ extension methods - Any() vs. Where() vs. Exists()

Any() returns true if any of the elements in a collection meet your predicate's criteria.

Where() returns an enumerable of all elements in a collection that meet your predicate's criteria.

Exists() does the same thing as any except it's just an older implementation that was there on the IList back before Linq.

Mongodb service won't start

For me, the reason for not starting turned out to be an orphaned lock file at /var/lib/mongo/mongo.lock When I deleted that file, mongo would then start up OK. My system had had some messy crashes prior to this. [Fedora 14]

Checking if a variable is initialized

Variable that is not defined will cause compilation error.

What you're asking is about checking if it is initialized. But initialization is just a value, that you should choose and assign in the constructor.

For example:

class MyClass
    MyClass() : mCharacter('0'), mDecimal(-1.0){};
    void SomeMethod();

    char mCharacter;
    double mDecimal;

void MyClass::SomeMethod()
    if ( mCharacter != '0')
        // touched after the constructor
        // do something with mCharacter.

    if ( mDecimal != -1.0 )
        // touched after the constructor
        // define mDecimal.

You should initialize to a default value that will mean something in the context of your logic, of course.

BEGIN - END block atomic transactions in PL/SQL

The default behavior of Commit PL/SQL block:

You should explicitly commit or roll back every transaction. Whether you issue the commit or rollback in your PL/SQL program or from a client program depends on the application logic. If you do not commit or roll back a transaction explicitly, the client environment determines its final state.

For example, in the SQLPlus environment, if your PL/SQL block does not include a COMMIT or ROLLBACK statement, the final state of your transaction depends on what you do after running the block. If you execute a data definition, data control, or COMMIT statement or if you issue the EXIT, DISCONNECT, or QUIT command, Oracle commits the transaction. If you execute a ROLLBACK statement or abort the SQLPlus session, Oracle rolls back the transaction.

I am getting an "Invalid Host header" message when connecting to webpack-dev-server remotely

I found out, that I need to set the public property of devServer, to my request's host value. Being that it will be displayed at that external address.

So I needed this in my webpack.config.js

devServer: {
  compress: true,
  public: '' // That solved it

Another solution is using it on the CLI:

webpack-dev-server --public $C9_HOSTNAME <-- var for Cloud9 external IP

How to use a filter in a controller?

AngularJs lets you to use filters inside template or inside Controller, Directive etc..

in template you can use this syntax

{{ variable | MyFilter: ... : ... }}

and inside controller you can use injecting the $filter service

angular.module('MyModule').controller('MyCtrl',function($scope, $filter){
    $filter('MyFilter')(arg1, arg2);

If you need more with Demo example here is a link

AngularJs filter examples and demo

CSS display:table-row does not expand when width is set to 100%

give on .view-type class float:left; or delete the float:right; of .view-name

edit: Wrap your div <div class="view-row"> with another div for example <div class="table">

and set the following css :

.table {

You have to use the table structure for correct results.

php & mysql query not echoing in html with tags?

I can spot a few different problems with this. However, in the interest of time, try this chunk of code instead:

<?php require 'db.php'; ?>  <?php if (isset($_POST['search'])) {     $limit = $_POST['limit'];     $country = $_POST['country'];     $state = $_POST['state'];     $city = $_POST['city'];     $data = mysqli_query(         $link,         "SELECT * FROM proxies WHERE country = '{$country}' AND state = '{$state}' AND city = '{$city}' LIMIT {$limit}"     );     while ($assoc = mysqli_fetch_assoc($data)) {         $proxy = $assoc['proxy'];         ?>             <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"                 "">             <html xmlns="">                 <head>                     <title>Sock5Proxies</title>                     <meta http-equiv="Content-Type" content="text/html;charset=utf-8" />                     <link href="./style.css" rel="stylesheet" type="text/css" />                     <link href="./buttons.css" rel="stylesheet" type="text/css" />                 </head>                 <body>                     <center>                         <h1>Sock5Proxies</h1>                     </center>                     <div id="wrapper">                         <div id="header">                             <ul id="nav">                                 <li class="active"><a href="index.html"><span></span>Home</a></li>                                 <li><a href="leads.html"><span></span>Leads</a></li>                                 <li><a href="payout.php"><span></span>Pay out</a></li>                                 <li><a href="contact.html"><span></span>Contact</a></li>                                 <li><a href="logout.php"><span></span>Logout</a></li>                             </ul>                         </div>                         <div id="content">                             <div id="center">                                 <table cellpadding="0" cellspacing="0" style="width:690px">                                     <thead>                                     <tr>                                         <th width="75" class="first">Proxy</th>                                         <th width="50" class="last">Status</th>                                     </tr>                                     </thead>                                     <tbody>                                     <tr class="rowB">                                         <td class="first"> <?php echo $proxy ?> </td>                                         <td class="last">Check</td>                                     </tr>                                     </tbody>                                 </table>                             </div>                         </div>                         <div id="footer"></div>                         <span id="about">Version 1.0</span>                     </div>                 </body>             </html>         <?php     } } ?> <html> <form action="" method="POST">     <input type="text" name="limit" placeholder="10" /><br>     <input type="text" name="country" placeholder="Country" /><br>     <input type="text" name="state" placeholder="State" /><br>     <input type="text" name="city" placeholder="City" /><br>     <input type="submit" name="search" value="Search" /><br> </form> </html> vs PHP (What to choose)

There are a couple of topics that might provide you with an answer. You could also run some tests yourself. Doesn't see too hard to get some loops started and adding a timer to calculate the execution time ;-)

How to check for null in a single statement in scala?

Try to avoid using null in Scala. It's really there only for interoperability with Java. In Scala, use Option for things that might be empty. If you're calling a Java API method that might return null, wrap it in an Option immediately.

def getObject : Option[QueueObject] = {
  // Wrap the Java result in an Option (this will become a Some or a None)

Note: You don't need to put it in a val or use an explicit return statement in Scala; the result will be the value of the last expression in the block (in fact, since there's only one statement, you don't even need a block).

def getObject : Option[QueueObject] = Option(someJavaObject.getResponse)

Besides what the others have already shown (for example calling foreach on the Option, which might be slightly confusing), you could also call map on it (and ignore the result of the map operation if you don't need it):

getObject map QueueManager.add

This will do nothing if the Option is a None, and call QueueManager.add if it is a Some.

I find using a regular if however clearer and simpler than using any of these "tricks" just to avoid an indentation level. You could also just write it on one line:

if (getObject.isDefined) QueueManager.add(getObject.get)

or, if you want to deal with null instead of using Option:

if (getObject != null) QueueManager.add(getObject)

edit - Ben is right, be careful to not call getObject more than once if it has side-effects; better write it like this:

val result = getObject
if (result.isDefined) QueueManager.add(result.get)


val result = getObject
if (result != null) QueueManager.add(result)

Rollback a Git merge

If you merged the branch, then reverted the merge using a pull request and merged that pull request to revert.

The easiest way I felt was to:

  1. Take out a new branch from develop/master (where you merged)
  2. Revert the "revert" using git revert -m 1 xxxxxx (if the revert was merged using a branch) or using git revert xxxxxx if it was a simple revert
  3. The new branch should now have the changes you want to merge again.
  4. Make changes or merge this branch to develop/master

React.js create loop through Array

In CurrentGame component you need to change initial state because you are trying use loop for participants but this property is undefined that's why you get error.,

getInitialState: function(){
    return {
       data: {
          participants: [] 

also, as player in .map is Object you should get properties from it {
   return <li key={player.championId}>{player.summonerName}</li>
   // -------------------^^^^^^^^^^^---------^^^^^^^^^^^^^^