Programs & Examples On #Sqlcommandbuilder

Automatically generates single-table commands that are used to reconcile changes made to a DataSet with the associated SQL Server database.

How to refresh or show immediately in datagridview after inserting?

In the form designer add a new timer using the toolbox. In properties set "Enabled" equal to "True".

enter image description here

The set the DataGridView to equal your new data in the timer

enter image description here

Populate a datagridview with sql query results

You may get a blank data grid if you set the data Source to a Dataset that you added to the form but is not being used. Set this to None if you are programatically setting your dataSource based on the above codes.

Passing an array using an HTML form hidden element

It's better to encode first to a JSON string and then encode with Base64, for example, on the server side in reverse order: use first the base64_decode and then json_decode functions. So you will restore your PHP array.

Delimiters in MySQL

The DELIMITER statement changes the standard delimiter which is semicolon ( ;) to another. The delimiter is changed from the semicolon( ;) to double-slashes //.

Why do we have to change the delimiter?

Because we want to pass the stored procedure, custom functions etc. to the server as a whole rather than letting mysql tool to interpret each statement at a time.

Get first date of current month in java

import java.util.Date;
import java.text.SimpleDateFormat;

Date currentMonth = new Date();
String yyyyMM = new SimpleDateFormat("yyyyMM").format(currentMonth);
Date firstDateOfMonth = new SimpleDateFormat("yyyyMM").parse(yyyyMM);

my stupid solution. but it's work for me :D

What is the difference between MySQL, MySQLi and PDO?

Those are different APIs to access a MySQL backend

  • The mysql is the historical API
  • The mysqli is a new version of the historical API. It should perform better and have a better set of function. Also, the API is object-oriented.
  • PDO_MySQL, is the MySQL for PDO. PDO has been introduced in PHP, and the project aims to make a common API for all the databases access, so in theory you should be able to migrate between RDMS without changing any code (if you don't use specific RDBM function in your queries), also object-oriented.

So it depends on what kind of code you want to produce. If you prefer object-oriented layers or plain functions...

My advice would be

  1. PDO
  2. MySQLi
  3. mysql

Also my feeling, the mysql API would probably being deleted in future releases of PHP.

Print "hello world" every X seconds

For small applications it is fine to use Timer and TimerTask as Rohit mentioned but in web applications I would use Quartz Scheduler to schedule jobs and to perform such periodic jobs.

See tutorials for Quartz scheduling.

How to specify test directory for mocha?

Edit : This option is deprecated :

If you want to do it by still just running mocha on the command line, but wanted to run the tests in a folder ./server-tests instead of ./test, create a file at ./test/mocha.opts with just this in the file:


If you wanted to run everything in that folder and subdirectories, put this into test/mocha.opts


mocha.opts are the arguments passed in via the command line, so making the first line just the directory you want to change the tests too will redirect from ./test/

How to remove last n characters from every element in the R vector

The same may be achieved with the stringi package:

char_array <- c("foo_bar","bar_foo","apple","beer")
a <- data.frame("data"=char_array, "data2"=1:4)
(a$data <- stri_sub(a$data, 1, -4)) # from the first to the last but 4th char
## [1] "foo_" "bar_" "ap"   "b" 

Leaflet - How to find existing markers, and delete markers?

Here is the code and demo for Adding the marker, deleting any of the marker and also getting all the present/added markers :

Here is the entire JSFiddle code . Also here is the full page demo.

Adding the marker :

// Script for adding marker on map click
map.on('click', onMapClick);

function onMapClick(e) {

    var geojsonFeature = {

        "type": "Feature",
        "properties": {},
        "geometry": {
                "type": "Point",
                "coordinates": [, e.latlng.lng]

    var marker;

    L.geoJson(geojsonFeature, {

        pointToLayer: function(feature, latlng){

            marker = L.marker(e.latlng, {

                title: "Resource Location",
                alt: "Resource Location",
                riseOnHover: true,
                draggable: true,

            }).bindPopup("<input type='button' value='Delete this marker' class='marker-delete-button'/>");

            marker.on("popupopen", onPopupOpen);

            return marker;

Deleting the Marker :

// Function to handle delete as well as other events on marker popup open

function onPopupOpen() {

    var tempMarker = this;

    // To remove marker on click of delete button in the popup of marker
    $(".marker-delete-button:visible").click(function () {

Getting all the markers in the map :

// getting all the markers at once
function getAllMarkers() {

    var allMarkersObjArray = []; // for marker objects
    var allMarkersGeoJsonArray = []; // for readable geoJson markers

    $.each(map._layers, function (ml) {

        if (map._layers[ml].feature) {



// any html element such as button, div to call the function()
$(".get-markers").on("click", getAllMarkers);

Return positions of a regex match() in Javascript?

Here is a cool feature I discovered recently, I tried this on the console and it seems to work:

var text = "border-bottom-left-radius";

var newText = text.replace(/-/g,function(match, index){
    return " " + index + " ";

Which returned: "border 6 bottom 13 left 18 radius"

So this seems to be what you are looking for.

Show a popup/message box from a Windows batch file

Following on @Fowl's answer, you can improve it with a timeout to only appear for 10 seconds using the following:

mshta "javascript:var sh=new ActiveXObject( 'WScript.Shell' ); sh.Popup( 'Message!', 10, 'Title!', 64 );close()"

See here for more details.

Execution failed for task ':app:compileDebugJavaWithJavac' Android Studio 3.1 Update

I had similar issue and no errors shown in Compilation. I have tried to clean and rebuild without any success. I managed to find the issue by using Invalidate Caches/Restart from file Menu, after the restart I managed to see the compilation error.

enter image description here

How to know that a string starts/ends with a specific string in jQuery?

One option is to use regular expressions:

if (str.match("^Hello")) {
   // do this if begins with Hello

if (str.match("World$")) {
   // do this if ends in world

Singleton with Arguments in Java

You can add a configurable initialization method in order to separate instantiation from getting.

public class Singleton {
    private static Singleton singleton = null;
    private final int x;

    private Singleton(int x) {
        this.x = x;

    public static Singleton getInstance() {
        if(singleton == null) {
            throw new AssertionError("You have to call init first");

        return singleton;

    public synchronized static Singleton init(int x) {
        if (singleton != null)
            // in my opinion this is optional, but for the purists it ensures
            // that you only ever get the same instance when you call getInstance
            throw new AssertionError("You already initialized me");

        singleton = new Singleton(x);
        return singleton;


Then you can call Singleton.init(123) once to configure it, for example in your app startup.

What USB driver should we use for the Nexus 5?

The one from Google USB Driver worked fine for me on two machines (Windows 7 x64 on both). Once Windows failed to auto-install the driver, I just right-clicked on the phone in Device Manager, chose "update driver" and gave it the path that I'd unzipped that driver into.

How to loop through an array of objects in swift

You can try using the simple NSArray in syntax for iterating over the array in swift which makes for shorter code. The following is working for me:

class ModelAttachment {
    var id: String?
    var url: String?
    var thumb: String?

var modelAttachementObj = ModelAttachment() = "1"
modelAttachementObj.url = ""
modelAttachementObj.thumb = "thumb"

var imgs: Array<ModelAttachment> = [modelAttachementObj]

for img in imgs  {
    let url = img.url

See docs here

How to position the form in the center screen?

Actually, you dont really have to code to make the form get to centerscreen.

Just modify the properties of the jframe
Follow below steps to modify:

  • right click on the form
  • change FormSize policy to - generate resize code
  • then edit the form position X -200 Y- 200

You're done. Why take the pain of coding. :)

List files ONLY in the current directory

instead of os.walk, just use os.listdir

Creating a selector from a method name with parameters

SEL is a type that represents a selector in Objective-C. The @selector() keyword returns a SEL that you describe. It's not a function pointer and you can't pass it any objects or references of any kind. For each variable in the selector (method), you have to represent that in the call to @selector. For example:

SEL noParameterSelector = @selector(methodWithNoParameters);

SEL oneParameterSelector = @selector(methodWithOneParameter:); // notice the colon here

-(void)methodWIthTwoParameters:(id)parameterOne and:(id)parameterTwo;
SEL twoParameterSelector = @selector(methodWithTwoParameters:and:); // notice the parameter names are omitted

Selectors are generally passed to delegate methods and to callbacks to specify which method should be called on a specific object during a callback. For instance, when you create a timer, the callback method is specifically defined as:


So when you schedule the timer you would use @selector to specify which method on your object will actually be responsible for the callback:

@implementation MyObject

    // do some computations
    if( timerShouldEnd ) {
      [timer invalidate];


// ...

int main(int argc, const char **argv)
    // do setup stuff
    MyObject* obj = [[MyObject alloc] init];
    SEL mySelector = @selector(myTimerCallback:);
    [NSTimer scheduledTimerWithTimeInterval:30.0 target:obj selector:mySelector userInfo:nil repeats:YES];
    // do some tear-down
    return 0;

In this case you are specifying that the object obj be messaged with myTimerCallback every 30 seconds.

Excel formula to remove space between words in a cell

Steps (1) Just Select your range, rows or column or array , (2) Press ctrl+H , (3 a) then in the find type a space (3 b) in the replace do not enter anything, (4)then just click on replace all..... you are done.

Ignore Typescript Errors "property does not exist on value of type"

Had a problem in Angular2, I was using the local storage to save something and it would not let me.


I had -> error -> Property 'city' does not exist on type 'Storage'.

How to fix it:



(localStorage as any).city

Add st, nd, rd and th (ordinal) suffix to a number

Minimal one-line approach for ordinal suffixes

function nth(n){return["st","nd","rd"][((n+90)%100-10)%10-1]||"th"}

(this is for positive integers, see below for other variations)


Start with an array with the suffixes ["st", "nd", "rd"]. We want to map integers ending in 1, 2, 3 (but not ending in 11, 12, 13) to the indexes 0, 1, 2.

Other integers (including those ending in 11, 12, 13) can be mapped to anything else—indexes not found in the array will evaluate to undefined. This is falsy in javascript and with the use of logical or (|| "th") the expression will return "th" for these integers, which is exactly what we want.

The expression ((n + 90) % 100 - 10) % 10 - 1 does the mapping. Breaking it down:

  • (n + 90) % 100: This expression takes the input integer − 10 mod 100, mapping 10 to 0, ... 99 to 89, 0 to 90, ..., 9 to 99. Now the integers ending in 11, 12, 13 are at the lower end (mapped to 1, 2, 3).
  • - 10: Now 10 is mapped to −10, 19 to −1, 99 to 79, 0 to 80, ... 9 to 89. The integers ending in 11, 12, 13 are mapped to negative integers (−9, −8, −7).
  • % 10: Now all integers ending in 1, 2, or 3 are mapped to 1, 2, 3. All other integers are mapped to something else (11, 12, 13 are still mapped to −9, −8, −7).
  • - 1: Subtracting one gives the final mapping of 1, 2, 3 to 0, 1, 2.

Verifying that it works

function nth(n){return["st","nd","rd"][((n+90)%100-10)%10-1]||"th"}_x000D_
//test integers from 1 to 124_x000D_
for(var r = [], i = 1; i < 125; i++) r.push(i + nth(i));_x000D_
//output result_x000D_
document.getElementById('result').innerHTML = r.join('<br>');
<div id="result"></div>


Allowing negative integers:

function nth(n){return["st","nd","rd"][(((n<0?-n:n)+90)%100-10)%10-1]||"th"}

In ES6 fat arrow syntax (anonymous function):



An even shorter alternative for positive integers is the expression


See this post for explanation.

Update 2


How to get xdebug var_dump to show full object/array

I know this is late but it might be of some use:

echo "<pre>";
echo "</pre>";

Convert string to JSON Object

Combining Saurabh Chandra Patel's answer with Molecular Man's observation, you should have something like this:

JSON.parse('{"TeamList" : [{"teamid" : "1","teamname" : "Barcelona"}]}');

Android Color Picker

We have just uploaded AmbilWarna color picker to Maven:

It can be used either as a dialog or as a Preference entry.

enter image description here

How to create JNDI context in Spring Boot with Embedded Tomcat Container

In SpringBoot 2.1, I found another solution. Extend standard factory class method getTomcatWebServer. And then return it as a bean from anywhere.

public class CustomTomcatServletWebServerFactory extends TomcatServletWebServerFactory {

    protected TomcatWebServer getTomcatWebServer(Tomcat tomcat) {
        System.setProperty("catalina.useNaming", "true");
        return new TomcatWebServer(tomcat, getPort() >= 0);

public class TomcatConfiguration {
    public ConfigurableServletWebServerFactory webServerFactory() {
        TomcatServletWebServerFactory factory = new CustomTomcatServletWebServerFactory();

        return factory;

Loading resources from context.xml doesn't work though. Will try to find out.

How can I open a .db file generated by eclipse(android) form DDMS-->File explorer-->data--->data-->packagename-->database?

Depending on your platform you can use: sqlite3 file_name.db from the terminal. .tables will list the tables, .schema is full layout. SQLite commands like: select * from table_name; and such will print out the full contents. Type: ".exit" to exit. No need to download a GUI application.Use a semi-colon if you want it to execute a single command. Decent SQLite usage tutorial

How to iterate std::set?

You must dereference the iterator in order to retrieve the member of your set.

std::set<unsigned long>::iterator it;
for (it = SERVER_IPS.begin(); it != SERVER_IPS.end(); ++it) {
    u_long f = *it; // Note the "*" here

If you have C++11 features, you can use a range-based for loop:

for(auto f : SERVER_IPS) {
  // use f here

Detecting value change of input[type=text] in jQuery

Try this:

Basically, just account for each event:


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


$("#textbox").keyup(function() { 

$("#textbox").change(function() { 

"java.lang.OutOfMemoryError: PermGen space" in Maven build

We face this error when permanent generation heap is full and some of us we use command prompt to build our maven project in windows. since we need to increase heap size, we could set our environment variable @ControlPanel/System and Security/System and there you click on Change setting and select Advanced and set Environment variable as below

  • Variable-name : MAVEN_OPTS
  • Variable-value : -XX:MaxPermSize=128m

How can I run Android emulator for Intel x86 Atom without hardware acceleration on Windows 8 for API 21 and 19?

Short Answer: No. Until recently(about 1 month ago), you could do that but with the latest updates, it is not possible. (see Update to Android SDK Tools 23.0.5 and avd doesn't start).

I was doing something similar: Doing development in a virtual machine and hence couldn't use the Hardware acceleration features as they are available only in the host machine. I was using Intel x86 images with Use Host GPU option; as they were much faster than the ARM version even without hardware acceleration. But then, after this update, my emulator AVDs which were working earlier are no longer starting with the same exact error message. Also, both genymotion and Xamarin Android emulators can't be used as they also need hardware acceleration(they are actually VMs which use Hardware acceleration for speed, and hence can't be run inside another VM).

I have found this solution but haven't tried it yet. The basic idea is that to still develop inside a VM; but for testing connect to an Emulator running on the host machine(and this Emulator VM can now use the hardware acceleration feature).

jquery ajax function not working

For the sake of documentation. I spent two days working out an ajax problem and this afternoon when I started testing, my PHP ajax handler wasn't getting called....

Extraordinarily frustrating.

The solution to my problem (which might help others) is the priority of the add_action.

add_action ('wp_ajax_(my handler), array('class_name', 'static_function'), 1);

recalling that the default priority = 10

I was getting a return code of zero and none of my code was being called.

...noting that this wasn't a WordPress problem, I probably misspoke on this question. My apologies.

"element.dispatchEvent is not a function" js error caught in firebug of FF3.0

Change the following line

$(document).ready(function() {


jQuery(document).ready(function($) {

Which HTML elements can receive focus?

There isn't a definite list, it's up to the browser. The only standard we have is DOM Level 2 HTML, according to which the only elements that have a focus() method are HTMLInputElement, HTMLSelectElement, HTMLTextAreaElement and HTMLAnchorElement. This notably omits HTMLButtonElement and HTMLAreaElement.

Today's browsers define focus() on HTMLElement, but an element won't actually take focus unless it's one of:

  • HTMLAnchorElement/HTMLAreaElement with an href
  • HTMLInputElement/HTMLSelectElement/HTMLTextAreaElement/HTMLButtonElement but not with disabled (IE actually gives you an error if you try), and file uploads have unusual behaviour for security reasons
  • HTMLIFrameElement (though focusing it doesn't do anything useful). Other embedding elements also, maybe, I haven't tested them all.
  • Any element with a tabindex

There are likely to be other subtle exceptions and additions to this behaviour depending on browser.

Padding characters in printf

This one is even simpler and execs no external commands.

$ printf "%-.20s [%s]\n" "${PROC_NAME}................................" "$PROC_STATUS"

JBoss............... [UP]

How to count the NaN values in a column in pandas DataFrame

import pandas as pd
import numpy as np

# example DataFrame
df = pd.DataFrame({'a':[1,2,np.nan], 'b':[np.nan,1,np.nan]})

# count the NaNs in a column
num_nan_a = df.loc[ (pd.isna(df['a'])) , 'a' ].shape[0]
num_nan_b = df.loc[ (pd.isna(df['b'])) , 'b' ].shape[0]

# summarize the num_nan_b
print(' ')
print(f"There are {num_nan_a} NaNs in column a")
print(f"There are {num_nan_b} NaNs in column b")

Gives as output:

     a    b
0  1.0  NaN
1  2.0  1.0
2  NaN  NaN

There are 1 NaNs in column a
There are 2 NaNs in column b

How to add elements to an empty array in PHP?

Based on my experience, solution which is fine(the best) when keys are not important:

$cart = [];
$cart[] = 13;
$cart[] = "foo";
$cart[] = obj;

load Js file in HTML

If this is your detail.html I don't see where do you load detail.js? Maybe this

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

should be this

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


How can I remove the gloss on a select element in Safari on Mac?

i have used this and solved my


google console error `OR-IEH-01`

It looks like your Google Play registration payment didn’t process. This can happen sometimes if a card has expired, the credit card or credit card verification (CVC) number was entered incorrectly, or if your billing address doesn't match the address in your Google Payments account.

Here’s how you can find the details of your transaction:

  1. Sign in to your Google Payments account at

  2. On the left menu, select the “Subscriptions and services” page.

  3. On the “Other purchase activity” card, click View purchases.

  4. Click the “Google Play” registration transaction to see your payment method.

  5. You can click “Payment methods” on the left menu if you need to edit the addresses on your Google Payments account.

To add a new credit or debit card to your account, you can follow the instructions on the Google Payments Help Center (

What is meant with "const" at end of function declaration?

Function can't change its parameters via the pointer/reference you gave it.

I go to this page every time I need to think about it:

I believe there's also a good chapter in Meyers' "More Effective C++".

How to join (merge) data frames (inner, outer, left, right)

New in 2014:

Especially if you're also interested in data manipulation in general (including sorting, filtering, subsetting, summarizing etc.), you should definitely take a look at dplyr, which comes with a variety of functions all designed to facilitate your work specifically with data frames and certain other database types. It even offers quite an elaborate SQL interface, and even a function to convert (most) SQL code directly into R.

The four joining-related functions in the dplyr package are (to quote):

  • inner_join(x, y, by = NULL, copy = FALSE, ...): return all rows from x where there are matching values in y, and all columns from x and y
  • left_join(x, y, by = NULL, copy = FALSE, ...): return all rows from x, and all columns from x and y
  • semi_join(x, y, by = NULL, copy = FALSE, ...): return all rows from x where there are matching values in y, keeping just columns from x.
  • anti_join(x, y, by = NULL, copy = FALSE, ...): return all rows from x where there are not matching values in y, keeping just columns from x

It's all here in great detail.

Selecting columns can be done by select(df,"column"). If that's not SQL-ish enough for you, then there's the sql() function, into which you can enter SQL code as-is, and it will do the operation you specified just like you were writing in R all along (for more information, please refer to the dplyr/databases vignette). For example, if applied correctly, sql("SELECT * FROM hflights") will select all the columns from the "hflights" dplyr table (a "tbl").

bootstrap initially collapsed element

another solution is to add toggle=false to the collapse target, this will stop it randomly opening and closing which happens if you just remove the "in"


<div class="accordion-heading">
    <a class="accordion-toggle"
    class="accordion-body collapse"
    <div class="span6">
        <div class="well well-small">
            <div class="accordion-toggle">
                ...some text...
    <div class="span2"></div>                            

What characters are valid in a URL?

All the gory details can be found in the current RFC on the topic: RFC 3986 (Uniform Resource Identifier (URI): Generic Syntax)

Based on this related answer, you are looking at a list that looks like: A-Z, a-z, 0-9, -, ., _, ~, :, /, ?, #, [, ], @, !, $, &, ', (, ), *, +, ,, ;, %, and =. Everything else must be url-encoded. Also, some of these characters can only exist in very specific spots in a URI and outside of those spots must be url-encoded (e.g. % can only be used in conjunction with url encoding as in %20), the RFC has all of these specifics.

How to make a div with a circular shape?



div {
    width: 100px;
    height: 100px;
    border-radius: 50%;
    background: red;



String.strip() in Python

In this case, you might get some differences. Consider a line like:

"foo\tbar "

In this case, if you strip, then you'll get {"foo":"bar"} as the dictionary entry. If you don't strip, you'll get {"foo":"bar "} (note the extra space at the end)

Note that if you use line.split() instead of line.split('\t'), you'll split on every whitespace character and the "striping" will be done during splitting automatically. In other words:


is always identical to:




Is not necessarily equivalent to:


C++ compile time error: expected identifier before numeric constant

Since your compiler probably doesn't support all of C++11 yet, which supports similar syntax, you're getting these errors because you have to initialize your class members in constructors:

Attribute() : name(5),val(5,0) {}

Actual meaning of 'shell=True' in subprocess

let's assume you are using shell=False and providing the command as a list. And some malicious user tried injecting an 'rm' command. You will see, that 'rm' will be interpreted as an argument and effectively 'ls' will try to find a file called 'rm'

ls: rm: No such file or directory
-rw-r--r--    1 root     root          1172 May 28  2020 /etc/passwd
drwxr-xr-x    2 root     root          4096 May 29  2020 /home
CompletedProcess(args=['ls', '-ld', '/home', 'rm', '/etc/passwd'], returncode=1)

shell=False is not a secure by default, if you don't control the input properly. You can still execute dangerous commands.

CompletedProcess(args=['rm', '-rf', '/home'], returncode=0)
ls: /home: No such file or directory
CompletedProcess(args=['ls', '-ld', '/home'], returncode=1)

I am writing most of my applications in container environments, I know which shell is being invoked and i am not taking any user input.

So in my use case, I see no security risk. And it is much easier creating long string of commands. Hope I am not wrong.

AWS CLI S3 A client error (403) occurred when calling the HeadObject operation: Forbidden

Trying to solve this problem myself, I discovered that there is no HeadBucket permission. It looks like there is, because that's what the error message tells you, but actually the HEAD operation requires the ListBucket permission. I also discovered that my IAM policy and my bucket policy were conflicting. Make sure you check both.

Styling mat-select in Angular Material

Working solution is by using in-build: panelClass attribute and set styles in global style.css (with !important):

/* style.css */
.matRole .mat-option-text {
  height: 4em !important;
<mat-select panelClass="matRole">...

Android emulator failed to allocate memory 8

Changing the ramSize in config.ini file didnt work for me.

I changed the SD Card size to 1000 MiB in Edit Android Virtual Device window ...It worked! :)

What is the difference between Sprint and Iteration in Scrum and length of each Sprint?

Iteration is synonymous with sprint, sprint is just the Scrum terminology.

On the question about sprint length, the only caution I would note is that in Scrum you are using the past sprints to gain a level of predictability on your teams ability to deliver on their commitments for the sprint. They do this by developing a velocity over a number of sprints. A change in the team members or the length of the sprint are factors that will affect the velocity for a sprint, over past sprints.

Just as background, velocity is the sum of estimation points assigned to the backlog items, or stories, that were completely finished during that sprint. Most Agile proponents (Mike Cohn, Ken Schwaber and Jeff Sutherland for instance), recommend that teams use "the recent weather" to base their future estimations on how much they think they can commit to in a sprint. This means using the average from the last few sprints as the basis for an estimate in the upcoming sprint planning session.

Once again, varying the sprint length reduces your teams ability to provide that velocity statistic which the team uses for sprint planning, and the product owner uses for release planning (i.e. predicting when the project will end or what will be in the project at the end).

I recommend Mike Cohn's book on Agile Estimating and Planning to provide an overview of the way sprints, estimation and planning all can fit together.

What is Persistence Context?

Taken from this page:

Here's a quick cheat sheet of the JPA world:

  • A Cache is a copy of data, copy meaning pulled from but living outside the database.
  • Flushing a Cache is the act of putting modified data back into the database.
  • A PersistenceContext is essentially a Cache. It also tends to have it's own non-shared database connection.
  • An EntityManager represents a PersistenceContext (and therefore a Cache)
  • An EntityManagerFactory creates an EntityManager (and therefore a PersistenceContext/Cache)

Show red border for all invalid fields after submitting form angularjs

I have created a working CodePen example to demonstrate how you might accomplish your goals.

I added ng-click to the <form> and removed the logic from your button:

<form name="addRelation" data-ng-click="save(model)">
<input class="btn" type="submit" value="SAVE" />

Here's the updated template:

<section ng-app="app" ng-controller="MainCtrl">
  <form class="well" name="addRelation" data-ng-click="save(model)">
    <label>First Name</label>
    <input type="text" placeholder="First Name" data-ng-model="model.firstName" id="FirstName" name="FirstName" required/><br/>
    <span class="text-error" data-ng-show="addRelation.submitted && addRelation.FirstName.$invalid">First Name is required</span><br/>
    <label>Last Name</label>
    <input type="text" placeholder="Last Name" data-ng-model="model.lastName" id="LastName" name="LastName" required/><br/>
    <span class="text-error" data-ng-show="addRelation.submitted && addRelation.LastName.$invalid">Last Name is required</span><br/>
    <input type="email" placeholder="Email" data-ng-model="" id="Email" name="Email" required/><br/>
    <span class="text-error" data-ng-show="addRelation.submitted && addRelation.Email.$error.required">Email address is required</span>
    <span class="text-error" data-ng-show="addRelation.submitted && addRelation.Email.$">Email address is not valid</span><br/>
    <input class="btn" type="submit" value="SAVE" />  

and controller code:

app.controller('MainCtrl', function($scope) {  
  $ = function(model) {
    $scope.addRelation.submitted = true;

    if($scope.addRelation.$valid) {
      // submit to db
    } else {
      console.log('Errors in form data');

I hope this helps.

JS how to cache a variable

You have three options:

  1. Cookies:
  2. DOMStorage (sessionStorage or localStorage):
  3. If your users are logged in, you could persist data in your server's DB that is keyed to a user (or group)

Are there .NET implementation of TLS 1.2?

as mentioned here you can just add this line

ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072;

How to open CSV file in R when R says "no such file or directory"?

I had the same problem and when I checked the properties of the file on file explorer, it shows me the next message:

"Security: This file came from another computer and might be blocked to help protect this computer"

You click on the "Unblock" button and... you can access to the file from R without any problem, just using read.csv() function and from the directory specified as your working directory, even if is not the same as the file’s directory you are accessing to.

How do you declare string constants in C?

Their are a few differences.

#define HELLO "Hello World"

The statement above can be used with preprocessor and can only be change in the preprocessor.

const char *HELLO2 = "Howdy";

The statement above can be changed with c code. Now you can't change the each individual character around like the statement below because its constant.

HELLO2[0] = 'a'

But you what you can do is have it point to a different string like the statement below


It really depends on how you want to be able to change the variable around. With the preprocessor or c code.

How to iterate a table rows with JQuery and access some cell values?

try this

var value = iterate('tr.item span.value');
var quantity = iterate('tr.item span.quantity');

function iterate(selector)
  var result = '';
  if ($(selector))
    $(selector).each(function ()
      if (result == '')
        result = $(this).html();
        result = result + "," + $(this).html();

Difference between / and /* in servlet mapping url pattern

Perhaps you need to know how urls are mapped too, since I suffered 404 for hours. There are two kinds of handlers handling requests. BeanNameUrlHandlerMapping and SimpleUrlHandlerMapping. When we defined a servlet-mapping, we are using SimpleUrlHandlerMapping. One thing we need to know is these two handlers share a common property called alwaysUseFullPath which defaults to false.

false here means Spring will not use the full path to mapp a url to a controller. What does it mean? It means when you define a servlet-mapping:


the handler will actually use the * part to find the controller. For example, the following controller will face a 404 error when you request it using /perfix/api/feature/doSomething

public class MyController {
    @RequestMapping(value = "/doSomething", method = RequestMethod.GET) 
    public String doSomething(HttpServletRequest request) {

It is a perfect match, right? But why 404. As mentioned before, default value of alwaysUseFullPath is false, which means in your request, only /api/feature/doSomething is used to find a corresponding Controller, but there is no Controller cares about that path. You need to either change your url to /perfix/perfix/api/feature/doSomething or remove perfix from MyController base @RequestingMapping.

What is the purpose of using -pedantic in GCC/G++ compiler?

<-ansi is an obsolete switch that requests the compiler to compile according to the 30-year-old obsolete revision of C standard, ISO/IEC 9899:1990, which is essentially a rebranding of the ANSI standard X3.159-1989 "Programming Language C. Why obsolete? Because after C90 was published by ISO, ISO has been in charge of the C standardization, and any technical corrigenda to C90 have been standardized by ISO. Thus it is more apt to use the -std=c90.

Without this switch, the recent GCC C compilers will conform to the C language standardized in ISO/IEC 9899:2011, or the newest 2018 revision.

Unfortunately there are some lazy compiler vendors that believe it is acceptable to stick to an older obsolete standard revision, for which the standardization document is not even available from standard bodies.

Using the switch helps ensuring that the code should compile in these obsolete compilers.

The -pedantic is an interesting one. In absence of -pedantic, even when a specific standard is requested, GCC will still allow some extensions that are not acceptable in the C standard. Consider for example the program

struct test {
    int zero_size_array[0];

The C11 draft n1570 paragraph says:

In addition to optional type qualifiers and the keyword static, the [ and ] may delimit an expression or *. If they delimit an expression (which specifies the size of an array), the expression shall have an integer type. If the expression is a constant expression, it shall have a value greater than zero.[...]

The C standard requires that the array length be greater than zero; and this paragraph is in the constraints; the standard says the following

A conforming implementation shall produce at least one diagnostic message (identified in an implementation-defined manner) if a preprocessing translation unit or translation unit contains a violation of any syntax rule or constraint, even if the behavior is also explicitly specified as undefined or implementation-defined. Diagnostic messages need not be produced in other circumstances.9)

However, if you compile the program with gcc -c -std=c90 pedantic_test.c, no warning is produced.

-pedantic causes the compiler to actually comply to the C standard; so now it will produce a diagnostic message, as is required by the standard:

gcc -c -pedantic -std=c90 pedantic_test.c
pedantic_test.c:2:9: warning: ISO C forbids zero-size array ‘zero_size_array’ [-Wpedantic]
     int zero_size_array[0];

Thus for maximal portability, specifying the standard revision is not enough, you must also use -pedantic (or -pedantic-errors) to ensure that GCC actually does comply to the letter of the standard.

The last part of the question was about using -ansi with C++. ANSI never standardized the C++ language - only adopting it from ISO, so this makes about as much sense as saying "English as standardized by France". However GCC still seems to accept it for C++, as stupid as it sounds.

How to upload a file from Windows machine to Linux machine using command lines via PuTTy?

Better and quicker approach without any software to download.

  • Open command prompt and follow steps mentioned below
  • cd path/from/where/file/istobe/copied
  • ftp (serverip or name)
  • It will ask for Server(AIX) User: (username)
  • It will ask for password : (password)
  • cd path/where/file/istobe/copied
  • pwd (to check current path)
  • mput (directory name which is to be copied)

This should work.

Use python requests to download CSV

To simplify these answers, and increase performance when downloading a large file, the below may work a bit more efficiently.

import requests
from contextlib import closing
import csv

url = "http://download-and-process-csv-efficiently/python.csv"

with closing(requests.get(url, stream=True)) as r:
    reader = csv.reader(r.iter_lines(), delimiter=',', quotechar='"')
    for row in reader:
        print row   

By setting stream=True in the GET request, when we pass r.iter_lines() to csv.reader(), we are passing a generator to csv.reader(). By doing so, we enable csv.reader() to lazily iterate over each line in the response with for row in reader.

This avoids loading the entire file into memory before we start processing it, drastically reducing memory overhead for large files.

Shell script to capture Process ID and kill it if exist

PID=`ps -ef | grep syncapp 'awk {print $2}'`

if [[ -z "$PID" ]] then
**Kill -9 $PID**

Styling of Select2 dropdown select boxes

Here is a working example of above. Now select2 has been updated the classes have change may be why you cannot get it to work. Here is the css....

    width: 148px !important;

.select2-container--default .select2-selection--single{
    height: 37px;
    width: 148px; 
    font-size: 1.2em;  
    position: relative;

.select2-container--default .select2-selection--single .select2-selection__arrow {
    background-image: -khtml-gradient(linear, left top, left bottom, from(#424242), to(#030303));
    background-image: -moz-linear-gradient(top, #424242, #030303);
    background-image: -ms-linear-gradient(top, #424242, #030303);
    background-image: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #424242), color-stop(100%, #030303));
    background-image: -webkit-linear-gradient(top, #424242, #030303);
    background-image: -o-linear-gradient(top, #424242, #030303);
    background-image: linear-gradient(#424242, #030303);
    width: 40px;
    color: #fff;
    font-size: 1.3em;
    padding: 4px 12px;
    height: 27px;
    position: absolute;
    top: 0px;
    right: 0px;
    width: 20px;

How to add headers to a multicolumn listbox in an Excel userform using VBA

Here's one approach which automates creating labels above each column of a listbox (on a worksheet).

It will work (though not super-pretty!) as long as there's no horizontal scrollbar on your listbox.

Sub Tester()
Dim i As Long

With Me.lbTest
    .ColumnCount = 5
    'must do this next step!
    .ColumnWidths = "70;60;100;60;60"
    .ListStyle = fmListStylePlain
    Debug.Print .ColumnWidths
    For i = 0 To 10
        .List(i, 0) = "blah" & i
        .List(i, 1) = "blah"
        .List(i, 2) = "blah"
        .List(i, 3) = "blah"
        .List(i, 4) = "blah"
    Next i

End With

LabelHeaders Me.lbTest, Array("Header1", "Header2", _
                     "Header3", "Header4", "Header5")

End Sub

Sub LabelHeaders(lb, arrHeaders)

    Const LBL_HT As Long = 15
    Dim T, L, shp As Shape, cw As String, arr
    Dim i As Long, w

    'delete any previous headers for this listbox
    For i = lb.Parent.Shapes.Count To 1 Step -1
        If lb.Parent.Shapes(i).Name Like lb.Name & "_*" Then
        End If
    Next i

    'get an array of column widths
    cw = lb.ColumnWidths
    If Len(cw) = 0 Then Exit Sub
    cw = Replace(cw, " pt", "")
    arr = Split(cw, ";")

    'start points for labels
    T = lb.Top - LBL_HT
    L = lb.Left

    For i = LBound(arr) To UBound(arr)
        w = CLng(arr(i))
        If i = UBound(arr) And (L + w) < lb.Width Then w = lb.Width - L
        Set shp = ActiveSheet.Shapes.AddShape(msoShapeRectangle, _
                                         L, T, w, LBL_HT)
        With shp
            .Name = lb.Name & "_" & i
            'do some formatting
            .Line.ForeColor.RGB = vbBlack
            .Line.Weight = 1
            .Fill.ForeColor.RGB = RGB(220, 220, 220)
            .TextFrame2.TextRange.Characters.Text = arrHeaders(i)
            .TextFrame2.TextRange.Font.Size = 9
            .TextFrame2.TextRange.Font.Fill.ForeColor.RGB = vbBlack
        End With
        L = L + w
    Next i
End Sub

Reading serial data in realtime in Python

You need to set the timeout to "None" when you open the serial port:

ser = serial.Serial(**bco_port**, timeout=None, baudrate=115000, xonxoff=False, rtscts=False, dsrdtr=False) 

This is a blocking command, so you are waiting until you receive data that has newline (\n or \r\n) at the end: line = ser.readline()

Once you have the data, it will return ASAP.

Vertical Alignment of text in a table cell

CSS {vertical-align: top;} or html Attribute {valign="top"}

.table td, 
.table th {
    border: 1px solid #161b21;
    text-align: left;
    padding: 8px;
    width: 250px;
    height: 100px;
    /* style for table */

.table-body-text {
  vertical-align: top;
<table class="table">
      <th valign="top">Title 1</th>
      <th valign="top">Title 2</th>
      <td class="table-body-text">text</td>
      <td class="table-body-text">text</td>

For table vertical-align we have 2 options.

  1. is to use css {vertical-align: top;}
  1. another way is to user attribute "valign" and the property should be "top" {valign="top"}

Converting Swagger specification JSON to HTML documentation

Try to use redoc-cli.

I was using bootprint-openapi by which I was generating a bunch of files (bundle.js,, index.html, main.css and and then you can convert it into a single .html file using html-inline to generate a simple index.html file.

Then I found redoc-cli very easy to to use and output is really-2 awesome, a single and beautiful index.html file.


npm install -g redoc-cli


redoc-cli bundle -o index.html swagger.json

How do I rotate a picture in WinForms

Old question but I had to address MrFox's comment in the accepted answer. Rotating an image when the size changes cuts off the edges of the image. One solution is to redraw the original on a larger image, centered, where the larger image's dimensions compensate for the need of not clipping the edges. For example, I wanted to be able to design a game's tiles at a normal angle but re-draw them at a 45-degree angle for an isometric view.

Here are example images (yellow borders are to make it easier to see here).

The original image: water tile

The centered tile in a larger image: enter image description here

The rotated image (where you rotate the larger image, not the original): enter image description here

The code (based in part on this answer in another question):

private Bitmap RotateImage(Bitmap rotateMe, float angle)
    //First, re-center the image in a larger image that has a margin/frame
    //to compensate for the rotated image's increased size

    var bmp = new Bitmap(rotateMe.Width + (rotateMe.Width / 2), rotateMe.Height + (rotateMe.Height / 2));

    using (Graphics g = Graphics.FromImage(bmp))
        g.DrawImageUnscaled(rotateMe, (rotateMe.Width / 4), (rotateMe.Height / 4), bmp.Width, bmp.Height);

    rotateMe = bmp;

    //Now, actually rotate the image
    Bitmap rotatedImage = new Bitmap(rotateMe.Width, rotateMe.Height);

    using (Graphics g = Graphics.FromImage(rotatedImage))
        g.TranslateTransform(rotateMe.Width / 2, rotateMe.Height / 2);   //set the rotation point as the center into the matrix
        g.RotateTransform(angle);                                        //rotate
        g.TranslateTransform(-rotateMe.Width / 2, -rotateMe.Height / 2); //restore rotation point into the matrix
        g.DrawImage(rotateMe, new Point(0, 0));                          //draw the image on the new bitmap

    return rotatedImage;

Firefox and SSL: sec_error_unknown_issuer

If anyone else is experiencing this issue with an Ubuntu LAMP and "COMODO Positive SSL" try to build your own bundle from the certs in the compressed file.

cat AddTrustExternalCARoot.crt COMODORSAAddTrustCA.crt COMODORSADomainValidationSecureServerCA.crt >

How to get form values in Symfony2 controller

In Symfony forms, there are two different types of transformers and three different types of underlying data: enter image description here In any form, the three different types of data are:

  • Model data

    This is the data in the format used in your application (e.g. an Issue object). If you call Form::getData() or Form::setData(), you're dealing with the "model" data.

  • Norm Data

    This is a normalized version of your data and is commonly the same as your "model" data (though not in our example). It's not commonly used directly.

  • View Data

    This is the format that's used to fill in the form fields themselves. It's also the format in which the user will submit the data. When you call Form::submit($data), the $data is in the "view" data format.

The two different types of transformers help convert to and from each of these types of data:

  • Model transformers:

    transform(): "model data" => "norm data"
    reverseTransform(): "norm data" => "model data"

  • View transformers:

    transform(): "norm data" => "view data"
    reverseTransform(): "view data" => "norm data"

Which transformer you need depends on your situation.

To use the view transformer, call addViewTransformer().

If you want to get all form data:


If you are after a specific form field (for example first_name):


Opening the Settings app from another app

UIApplicationOpenSettingsURLString this will only work if you have previously allowed for any permission. For example Location, Photo, Contact, Push notification access. So if you have not such permission(s) from the user:

If iOS 10 or above,

It will open the Settings but then crash it. The reason, there's nothing in settings for your app.

Below code will open your application settings inside the iOS Setting.

NSURL *url = [NSURL URLWithString:UIApplicationOpenSettingsURLString];
if ([[UIApplication sharedApplication] canOpenURL:url]) {
    [[UIApplication sharedApplication] openURL:url];

Due to device unavailability, I couldn't check this on iOS < 10.

Also, I could find below code from some gist and it works fine on iOS 10 as well. But I am not sure if this will approve by Apple review team or not.

How to make certain text not selectable with CSS

Use a simple background image for the textarea suffice.


<div onselectstart="return false">your text</div>

jquery remove "selected" attribute of option?

The question is asked in a misleading manner. "Removing the selected attribute" and "deselecting all options" are entirely different things.

To deselect all options in a documented, cross-browser manner use either



// Note the use of .prop instead of .attr
$("select option").prop("selected", false);

Uninstall all installed gems, in OSX?

The only command helped me to cleanup all gems and ignores default gems, which can't be uninstalled

for x in `gem list --no-versions`; do gem uninstall $x -a -x -I; done

Spring Boot Remove Whitelabel Error Page


Include the above line to the Resources folders

More Error Issue resolve please refer

Move SQL data from one table to another

Yes it is. First INSERT + SELECT and then DELETE orginals.

INSERT INTO Table2 (UserName,Password)
SELECT UserName,Password FROM Table1 WHERE UserName='X' AND Password='X'

then delete orginals

DELETE FROM Table1 WHERE UserName='X' AND Password='X'

you may want to preserve UserID or someother primary key, then you can use IDENTITY INSERT to preserve the key.


Get the closest number out of an array

A simpler way with O(n) time complexity is to do this in one iteration of the array. This method is intended for unsorted arrays.

Following is a javascript example, here from the array we find the number which is nearest to "58".

var inputArr = [150, 5, 200, 50, 30];
var search = 58;
var min = Math.min();
var result = 0;
for(i=0;i<inputArr.length;i++) {
  let absVal = Math.abs(search - inputArr[i])
  if(min > absVal) {
    result = inputArr[i];
console.log(result); //expected output 50 if input is 58

This will work for positive, negative, decimal numbers as well.

Math.min() will return Infinity.

The result will store the value nearest to the search element.

How to use PHP string in mySQL LIKE query?

DO it like

$query = mysql_query("SELECT * FROM table WHERE the_number LIKE '$yourPHPVAR%'");

Do not forget the % at the end

How to show another window from mainwindow in QT

  1. Implement a slot in your QMainWindow where you will open your new Window,
  2. Place a widget on your QMainWindow,
  3. Connect a signal from this widget to a slot from the QMainWindow (for example: if the widget is a QPushButton connect the signal click() to the QMainWindow custom slot you have created).

Code example:


// ...
include "newwindow.h"
// ...
public slots:
   void openNewWindow();
// ...
   NewWindow *mMyNewWindow;
// ...


// ...
      // ...
      connect(mMyButton, SIGNAL(click()), this, SLOT(openNewWindow()));
      // ...
// ...
void MainWindow::openNewWindow()
   mMyNewWindow = new NewWindow(); // Be sure to destroy your window somewhere
   // ...

This is an example on how display a custom new window. There are a lot of ways to do this.

Display encoded html with razor

this is pretty simple:


Another Solution, you could also return a HTMLString, Razor will output the correct formatting:

in the view itself:


in controller:

public static HtmlString GetSomeHtml()
    var Data = "abc<br/>123";
    return new HtmlString(Data);

How to pass variable number of arguments to a PHP function

In a new Php 5.6, you can use ... operator instead of using func_get_args().

So, using this, you can get all the parameters you pass:

function manyVars(...$params) {

Useful example of a shutdown hook in Java?

You could do the following:

  • Let the shutdown hook set some AtomicBoolean (or volatile boolean) "keepRunning" to false
  • (Optionally, .interrupt the working threads if they wait for data in some blocking call)
  • Wait for the working threads (executing writeBatch in your case) to finish, by calling the Thread.join() method on the working threads.
  • Terminate the program

Some sketchy code:

  • Add a static volatile boolean keepRunning = true;
  • In run() you change to

    for (int i = 0; i < N && keepRunning; ++i)
        writeBatch(pw, i);
  • In main() you add:

    final Thread mainThread = Thread.currentThread();
    Runtime.getRuntime().addShutdownHook(new Thread() {
        public void run() {
            keepRunning = false;

That's roughly how I do a graceful "reject all clients upon hitting Control-C" in terminal.

From the docs:

When the virtual machine begins its shutdown sequence it will start all registered shutdown hooks in some unspecified order and let them run concurrently. When all the hooks have finished it will then run all uninvoked finalizers if finalization-on-exit has been enabled. Finally, the virtual machine will halt.

That is, a shutdown hook keeps the JVM running until the hook has terminated (returned from the run()-method.

Failed to resolve: android

compile '' 

This should pull the most recent version, and allow it to compile.

Sort a list of Class Instances Python

import operator
sorted_x = sorted(x, key=operator.attrgetter('score'))

if you want to sort x in-place, you can also:


how to Call super constructor in Lombok

Lombok does not support that also indicated by making any @Value annotated class final (as you know by using @NonFinal).

The only workaround I found is to declare all members final yourself and use the @Data annotation instead. Those subclasses need to be annotated by @EqualsAndHashCode and need an explicit all args constructor as Lombok doesn't know how to create one using the all args one of the super class:

public class A {
    private final int x;
    private final int y;

@EqualsAndHashCode(callSuper = true)
public class B extends A {
    private final int z;

    public B(int x, int y, int z) {
        super(x, y);
        this.z = z;

Especially the constructors of the subclasses make the solution a little untidy for superclasses with many members, sorry.

How can I autoformat/indent C code in vim?

I wanted to add, that in order to prevent it from being messed up in the first place you can type :set paste before pasting. After pasting, you can type :set nopaste for things like js-beautify and indenting to work again.

Django Model() vs Model.objects.create()

The two syntaxes are not equivalent and it can lead to unexpected errors. Here is a simple example showing the differences. If you have a model:

from django.db import models

class Test(models.Model):

    added = models.DateTimeField(auto_now_add=True)

And you create a first object:

foo = Test.objects.create(pk=1)

Then you try to create an object with the same primary key:

foo_duplicate = Test.objects.create(pk=1)
# returns the error:
# django.db.utils.IntegrityError: (1062, "Duplicate entry '1' for key 'PRIMARY'")

foo_duplicate = Test(pk=1).save()
# returns the error:
# django.db.utils.IntegrityError: (1048, "Column 'added' cannot be null")

Displaying standard DataTables in MVC

This is not "wrong" at all, it's just not what the cool guys typically do with MVC. As an aside, I wish some of the early demos of ASP.NET MVC didn't try to cram in Linq-to-Sql at the same time. It's pretty awesome and well suited for MVC, sure, but it's not required. There is nothing about MVC that prevents you from using ADO.NET. For example:

Controller action:

public ActionResult Index()
    ViewData["Message"] = "Welcome to ASP.NET MVC!";

    DataTable dt = new DataTable("MyTable");
    dt.Columns.Add(new DataColumn("Col1", typeof(string)));
    dt.Columns.Add(new DataColumn("Col2", typeof(string)));
    dt.Columns.Add(new DataColumn("Col3", typeof(string)));

    for (int i = 0; i < 3; i++)
        DataRow row = dt.NewRow();
        row["Col1"] = "col 1, row " + i;
        row["Col2"] = "col 2, row " + i;
        row["Col3"] = "col 3, row " + i;

    return View(dt); //passing the DataTable as my Model

View: (w/ Model strongly typed as System.Data.DataTable)

<table border="1">
            <%foreach (System.Data.DataColumn col in Model.Columns) { %>
                <th><%=col.Caption %></th>
            <%} %>
    <% foreach(System.Data.DataRow row in Model.Rows) { %>
            <% foreach (var cell in row.ItemArray) {%>
                <td><%=cell.ToString() %></td>
            <%} %>
    <%} %>         

Now, I'm violating a whole lot of principles and "best-practices" of ASP.NET MVC here, so please understand this is just a simple demonstration. The code creating the DataTable should reside somewhere outside of the controller, and the code in the View might be better isolated to a partial, or html helper, to name a few ways you should do things.

You absolutely are supposed to pass objects to the View, if the view is supposed to present them. (Separation of concerns dictates the view shouldn't be responsible for creating them.) In this case I passed the DataTable as the actual view Model, but you could just as well have put it in ViewData collection. Alternatively you might make a specific IndexViewModel class that contains the DataTable and other objects, such as the welcome message.

I hope this helps!

How do I send a POST request with PHP?

The better way of sending GET or POST requests with PHP is as below:

    $r = new HttpRequest('', HttpRequest::METH_POST);
    $r->setOptions(array('cookies' => array('lang' => 'de')));
    $r->addPostFields(array('user' => 'mike', 'pass' => 's3c|r3t'));

    try {
        echo $r->send()->getBody();
    } catch (HttpException $ex) {
        echo $ex;

The code is taken from official documentation here

No 'Access-Control-Allow-Origin' header is present on the requested resource—when trying to get data from a REST API

In case you are using NodeJS/Express as back-end and ReactJS/axios as front-end within a development environment in MacOS, you need to run both sides under https. Below is what it finally worked for me (after many hours of deep dive & testing):

Step 1: Create an SSL certificate

Just follow the steps from How to get HTTPS working on your local development environment in 5 minutes

You will end up with a couple of files to be used as credentials to run the https server and ReactJS web:

server.key & server.crt

You need to copy them in the root folders of both the front and back ends (in a Production environment, you might consider copying them in ./ssh for the back-end).

Step 2: Back-end setup

I read a lot of answers proposing the use of 'cors' package or even setting ('Access-Control-Allow-Origin', '*'), which is like saying: "Hackers are welcome to my website". Just do like this:

import express from 'express';
const emailRouter = require('./routes/email');  // in my case, I was sending an email through a form in ReactJS
const fs = require('fs');
const https = require('https');

const app = express();
const port = 8000;

// CORS (Cross-Origin Resource Sharing) headers to support Cross-site HTTP requests
app.all('*', (req, res, next) => {
    res.header("Access-Control-Allow-Origin", "https://localhost:3000");

// Routes definition
app.use('/email', emailRouter);

// HTTPS server
const credentials = {
  key: fs.readFileSync('server.key'),
  cert: fs.readFileSync('server.crt')

const httpsServer = https.createServer(credentials, app);
httpsServer.listen(port, () => {
    console.log(`Back-end running on port ${port}`);

In case you want to test if the https is OK, you can replace the httpsServer constant by the one below:

https.createServer(credentials, (req: any, res: any) => {
  res.end("hello world from SSL\n");
}).listen(port, () => {
  console.log(`HTTPS server listening on port ${port}...`);

And then access it from a web browser: https://localhost:8000/

Step 3: Front-end setup

This is the axios request from the ReactJS front-end:

    await axios.get(`https://localhost:8000/email/send`, {
        params: {/* whatever data you want to send */ },
        headers: {
            'Content-Type': 'application/json',

And now, you need to launch your ReactJS web in https mode using the credentials for SSL we already created. Type this in your MacOS terminal:

HTTPS=true SSL_CRT_FILE=server.crt SSL_KEY_FILE=server.key npm start

At this point, you are sending a request from an https connection at port 3000 from your front-end, to be received by an https connection at port 8000 by your back-end. CORS should be happy with this ;)

What are the obj and bin folders (created by Visual Studio) used for?

The obj directory is for intermediate object files and other transient data files that are generated by the compiler or build system during a build. The bin directory is the directory that final output binaries (and any dependencies or other deployable files) will be written to.

You can change the actual directories used for both purposes within the project settings, if you like.

No Persistence provider for EntityManager named

Faced the same issue and couldn't find solution for quite a long time. In my case it helped to replace




Took solution from here

How to check if PHP array is associative or sequential?

I've come up with next method:

function isSequential(array $list): bool
    $i = 0;
    $count = count($list);
    while (array_key_exists($i, $list)) {
        $i += 1;
        if ($i === $count) {
            return true;

    return false;

var_dump(isSequential(array())); // false
var_dump(isSequential(array('a', 'b', 'c'))); // true
var_dump(isSequential(array("0" => 'a', "1" => 'b', "2" => 'c'))); // true
var_dump(isSequential(array("1" => 'a', "0" => 'b', "2" => 'c'))); // true
var_dump(isSequential(array("1a" => 'a', "0b" => 'b', "2c" => 'c'))); // false
var_dump(isSequential(array("a" => 'a', "b" => 'b', "c" => 'c'))); // false

*Note empty array is not considered a sequential array, but I think it's fine since empty arrays is like 0 - doesn't matter it's plus or minus, it's empty.

Here are the advantages of this method compared to some listed above:

  • It does not involve copying of arrays (someone mentioned in this gist that array_values does not involve copying - what!?? It certainly does - as will be seen below)
  • It's faster for bigger arrays and more memory friendly at the same time

I've used benchmark kindly provided by Artur Bodera, where I changed one of the arrays to 1M elements (array_fill(0, 1000000, uniqid()), // big numeric array).

Here are the results for 100 iterations:

PHP 7.1.16 (cli) (built: Mar 31 2018 02:59:59) ( NTS )

Initial memory: 32.42 MB
Testing my_method (isset check) - 100 iterations
  Total time: 2.57942 s
  Total memory: 32.48 MB

Testing method3 (array_filter of keys) - 100 iterations
  Total time: 5.10964 s
  Total memory: 64.42 MB

Testing method1 (array_values check) - 100 iterations
  Total time: 3.07591 s
  Total memory: 64.42 MB

Testing method2 (array_keys comparison) - 100 iterations
  Total time: 5.62937 s
  Total memory: 96.43 MB

*Methods are ordered based on their memory consumption

**I used echo " Total memory: " . number_format(memory_get_peak_usage()/1024/1024, 2) . " MB\n"; to display memory usage

How to check if String value is Boolean type in Java?

return "true".equals(value) || "false".equals(value);

Unable to auto-detect email address

Try the following steps,

  1. Open command prompt and then run
  2. git config --global "[email protected]" // put your email address press enter
  3. git config --global "YOUR NAME" // put your name

Calculating a directory's size using Python?

This script tells you which file is the biggest in the CWD and also tells you in which folder the file is. This script works for me on win8 and python 3.3.3 shell

import os



for root, dirs, files in os.walk(folder):
    for file in files:
##        print (pathname)
##        print (os.path.getsize(pathname)/1024/1024)
        if number < os.path.getsize(pathname):
            number = os.path.getsize(pathname)

##        print ()

print (string)
print ()
print (number)
print ("Number in bytes")

How to substring in jquery

Standard javascript will do that using the following syntax:

string.substring(from, to)

var name = "nameGorge";
var output = name.substring(4);

Read more here:

DataGridView - Focus a specific cell

Set the Current Cell like:

DataGridView1.CurrentCell = DataGridView1.Rows[rowindex].Cells[columnindex]


DataGridView1.CurrentCell = DataGridView1.Item("ColumnName", 5)

and you can directly focus with Editing by:


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

WordPress will only prompt you for your FTP connection information while trying to install plugins or a WordPress update if it cannot write to /wp-content directly. Otherwise, if your web server has write access to the necessary files, it will take care of the updates and installation automatically. This method does not require you to have FTP/SFTP or SSH access, but it does require your to have specific file permissions set up on your webserver.

It will try various methods in order, and fall back on FTP if Direct and SSH methods are unavailable.

WordPress will try to write a temporary file to your /wp-content directory. If this succeeds, it compares the ownership of the file with its own uid, and if there is a match it will allow you to use the 'direct' method of installing plugins, themes, or updates.

Now, if for some reason you do not want to rely on the automatic check for which filesystem method to use, you can define a constant, 'FS_METHOD' in your wp-config.php file, that is either 'direct', 'ssh', 'ftpext' or 'ftpsockets' and it will use that method. Keep in mind that if you set this to 'direct', but your web user (the username under which your web server runs) does not have proper write permissions, you will receive an error.

In summary, if you do not want to (or you cannot) change permissions on wp-content so your web server has write permissions, then add this to your wp-config.php file:

define('FS_METHOD', 'direct');

Permissions explained here:

What is the best way to extract the first word from a string in Java?

The simple one I used to do is

str.contains(" ") ? str.split(" ")[0] : str

Where str is your string or text bla bla :). So, if

  1. str is having empty value it returns as it is.
  2. str is having one word, it returns as it is.
  3. str is multiple words, it extract the first word and return.

Hope this is helpful.

Get time difference between two dates in seconds

You can use new Date().getTime() for getting timestamps. Then you can calculate the difference between end and start and finally transform the timestamp which is ms into s.

const start = new Date().getTime();
const end = new Date().getTime();

const diff = end - start;
const seconds = Math.floor(diff / 1000 % 60);

Interface vs Abstract Class (general OO)


Does not contain Impleamentations Interface can inherit from a number of interfaces(Multiple inheritance supported) Members are automatically public May contain properties, methods, events and indexers

Abstract Class:

May/mayn't contain Implementations; At least one member will not be implemented. A Class may inherit from a single Base class; multiple inheritance not allowed. Members have access modifiers May contain fields, properties, constructors, destructors, methods, events and indexers

These are the key differences between Abstract Class and Interfaces.

Operator overloading on class templates

You need to say the following (since you befriend a whole template instead of just a specialization of it, in which case you would just need to add a <> after the operator<<):

template<typename T>
friend std::ostream& operator<<(std::ostream& out, const MyClass<T>& classObj);

Actually, there is no need to declare it as a friend unless it accesses private or protected members. Since you just get a warning, it appears your declaration of friendship is not a good idea. If you just want to declare a single specialization of it as a friend, you can do that like shown below, with a forward declaration of the template before your class, so that operator<< is regognized as a template.

// before class definition ...
template <class T>
class MyClass;

// note that this "T" is unrelated to the T of MyClass !
template<typename T>
std::ostream& operator<<(std::ostream& out, const MyClass<T>& classObj);

// in class definition ...
friend std::ostream& operator<< <>(std::ostream& out, const MyClass<T>& classObj);

Both the above and this way declare specializations of it as friends, but the first declares all specializations as friends, while the second only declares the specialization of operator<< as a friend whose T is equal to the T of the class granting friendship.

And in the other case, your declaration looks OK, but note that you cannot += a MyClass<T> to a MyClass<U> when T and U are different type with that declaration (unless you have an implicit conversion between those types). You can make your += a member template

// In MyClass.h
template<typename U>
MyClass<T>& operator+=(const MyClass<U>& classObj);

// In MyClass.cpp
template <class T> template<typename U>
MyClass<T>& MyClass<T>::operator+=(const MyClass<U>& classObj) {
  // ...
  return *this;

Data binding for TextBox

You can't databind to a property and then explictly assign a value to the databound property.

IE throws JavaScript Error: The value of the property 'googleMapsQuery' is null or undefined, not a Function object (works in other browsers)

Have you tried adding the semicolon to onclick="googleMapsQuery(422111);". I don't have enough of your code to test if the missing semicolon would cause the error, but ie is more picky about syntax.

Generate an integer that is not among four billion given ones

Check the size of the input file, then output any number which is too large to be represented by a file that size. This may seem like a cheap trick, but it's a creative solution to an interview problem, it neatly sidesteps the memory issue, and it's technically O(n).

void maxNum(ulong filesize)
    ulong bitcount = filesize * 8; //number of bits in file

    for (ulong i = 0; i < bitcount; i++)

Should print 10 bitcount - 1, which will always be greater than 2 bitcount. Technically, the number you have to beat is 2 bitcount - (4 * 109 - 1), since you know there are (4 billion - 1) other integers in the file, and even with perfect compression they'll take up at least one bit each.

Specify multiple attribute selectors in CSS

For concatenating it's:

input[name="Sex"][value="M"] {}

And for taking union it's:

input[name="Sex"], input[value="M"] {}

Convert an enum to List<string>

I want to add another solution: In my case, I need to use a Enum group in a drop down button list items. So they might have space, i.e. more user friendly descriptions needed:

  public enum CancelReasonsEnum
    [Description("In rush")]
    [Description("Need more coffee")]
    [Description("Call me back in 5 minutes!")]

In a helper class (HelperMethods) I created the following method:

 public static List<string> GetListOfDescription<T>() where T : struct
        Type t = typeof(T);
        return !t.IsEnum ? null : Enum.GetValues(t).Cast<Enum>().Select(x => x.GetDescription()).ToList();

When you call this helper you will get the list of item descriptions.

 List<string> items = HelperMethods.GetListOfDescription<CancelReasonEnum>();

ADDITION: In any case, if you want to implement this method you need :GetDescription extension for enum. This is what I use.

 public static string GetDescription(this Enum value)
        Type type = value.GetType();
        string name = Enum.GetName(type, value);
        if (name != null)
            FieldInfo field = type.GetField(name);
            if (field != null)
                DescriptionAttribute attr =Attribute.GetCustomAttribute(field,typeof(DescriptionAttribute)) as DescriptionAttribute;
                if (attr != null)
                    return attr.Description;
        return null;
        /* how to use
            MyEnum x = MyEnum.NeedMoreCoffee;
            string description = x.GetDescription();


What's the name for hyphen-separated case?

There is no standardized name.

Libraries like jquery and lodash refer it as kebab-case. So does Vuejs javascript framework. However, I am not sure whether it's safe to declare that it's referred as kebab-case in javascript world.

Best method for reading newline delimited files and discarding the newlines?

I use this

def cleaned( aFile ):
    for line in aFile:
        yield line.strip()

Then I can do things like this.

lines = list( cleaned( open("file","r") ) )

Or, I can extend cleaned with extra functions to, for example, drop blank lines or skip comment lines or whatever.

What are file descriptors, explained in simple terms?

As an addition to other answers, unix considers everything as a file system. Your keyboard is a file that is read only from the perspective of the kernel. The screen is a write only file. Similarly, folders, input-output devices etc are also considered to be files. Whenever a file is opened, say when the device drivers[for device files] requests an open(), or a process opens an user file the kernel allocates a file descriptor, an integer that specifies the access to that file such it being read only, write only etc. [for reference : ]

How to hide 'Back' button on navigation bar on iPhone?

In the function viewDidLoad of the UIViewController use the code:

self.navigationItem.hidesBackButton = YES;

Find size of an array in Perl


my @a = (undef, undef);
my $size = @a;

warn "Size: " . $#a;   # Size: 1. It's not the size
warn "Size: " . $size; # Size: 2

How to set session attribute in java?

I am try to catch your point.I hope it is helpful.....

if (session.isNew()){
     title = "Welcome to my website";
     session.setAttribute(userIDKey, userID);

How do I push to GitHub under a different username?

If under Windows and user Git for Windows and the manager for managing the credentials (aka Git-Credential-Manager-for-Windows Link) the problem is that there is no easy way to switch amongst users when pushing to GitHub over https using OAuth tokens.

The reason is that the token is stored as:

  • Internet Address: git:
  • Username: Personal Access Token
  • Password: OAuth_Token

Variations of the URL in Internet Address don't work, for example:

The solution: namespaces. This is found in the details for the configuration of the Git-Credential-Manager-for-Windows:

Quoting from it:


Sets the namespace for stored credentials.

By default the GCM uses the 'git' namespace for all stored credentials, setting this configuration value allows for control of the namespace used globally, or per host.

git config --global credential.namespace name

Now, store your credential in the Windows Credential Manager as:

  • Internet Address: git.username:
  • Username: Personal Access Token
  • Password: OAuth_Token

Notice that we have changed: git -> git.username (where you change username to your actual username or for the sake of it, to whatever you may want as unique identifier)

Now, inside the repository where you want to use the specific entry, execute:

git config credential.namespace git.username

(Again ... replace username with your desired value)

Your .git/config will now contain:

    namespace = git.username

Et voilá! The right credential will be pulled from the Windows Credential Store.

This, of course, doesn't change which user/e-mail is pushing. For that you have to configure the usual and

What do >> and << mean in Python?

These are the shift operators

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

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

C string append

man page of strcat says that arg1 and arg2 are appended to arg1.. and returns the pointer of s1. If you dont want disturb str1,str2 then you have write your own function.

char * my_strcat(const char * str1, const char * str2)
   char * ret = malloc(strlen(str1)+strlen(str2));

     sprintf(ret, "%s%s", str1, str2);
     return ret;
   return NULL;    

Hope this solves your purpose

How to copy file from HDFS to the local file system

you can accomplish in both these ways.

1.hadoop fs -get <HDFS file path> <Local system directory path>
2.hadoop fs -copyToLocal <HDFS file path> <Local system directory path>


My files are located in /sourcedata/mydata.txt I want to copy file to Local file system in this path /user/ravi/mydata

hadoop fs -get /sourcedata/mydata.txt /user/ravi/mydata/

forEach is not a function error with JavaScript array

If you are trying to loop over a NodeList like this:

const allParagraphs = document.querySelectorAll("p");

I highly recommend loop it this way: , function(el) {
    // Write your code here

Personally, I've tried several ways but most of them didn't work as I wanted to loop over a NodeList, but this one works like a charm, give it a try!

The NodeList isn't an Array, but we treat it as an Array, using Array. So, you need to know that it is not supported in older browsers!

Need more information about NodeList? Please read its documentation on MDN.

How to make a phone call using intent in Android?

Permission in AndroidManifest.xml

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

Complete code:

private void onCallBtnClick(){
    if (Build.VERSION.SDK_INT < 23) {
    }else {

        if (ActivityCompat.checkSelfPermission(mActivity,
                Manifest.permission.CALL_PHONE) == PackageManager.PERMISSION_GRANTED) {

        }else {
            final String[] PERMISSIONS_STORAGE = {Manifest.permission.CALL_PHONE};
            //Asking request Permissions
            ActivityCompat.requestPermissions(mActivity, PERMISSIONS_STORAGE, 9);

public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
    boolean permissionGranted = false;
        case 9:
            permissionGranted = grantResults[0]== PackageManager.PERMISSION_GRANTED;
    }else {
        Toast.makeText(mActivity, "You don't assign permission.", Toast.LENGTH_SHORT).show();

private void phoneCall(){
    if (ActivityCompat.checkSelfPermission(mActivity,
            Manifest.permission.CALL_PHONE) == PackageManager.PERMISSION_GRANTED) {
        Intent callIntent = new Intent(Intent.ACTION_CALL);
        Toast.makeText(mActivity, "You don't assign permission.", Toast.LENGTH_SHORT).show();

How to launch an application from a browser?

You can't really "launch an application" in the true sense. You can as you indicated ask the user to open a document (ie a PDF) and windows will attempt to use the default app for that file type. Many applications have a way to do this.

For example you can save RDP connections as a .rdp file. Putting a link on your site to something like this should allow the user to launch right into an RDP session:

<a href="MyServer1.rdp">Server 1</a>

What is a predicate in c#?

Predicate<T> is a functional construct providing a convenient way of basically testing if something is true of a given T object.

For example suppose I have a class:

class Person {
    public string Name { get; set; }
    public int Age { get; set; }

Now let's say I have a List<Person> people and I want to know if there's anyone named Oscar in the list.

Without using a Predicate<Person> (or Linq, or any of that fancy stuff), I could always accomplish this by doing the following:

Person oscar = null;
foreach (Person person in people) {
    if (person.Name == "Oscar") {
        oscar = person;

if (oscar != null) {
    // Oscar exists!

This is fine, but then let's say I want to check if there's a person named "Ruth"? Or a person whose age is 17?

Using a Predicate<Person>, I can find these things using a LOT less code:

Predicate<Person> oscarFinder = (Person p) => { return p.Name == "Oscar"; };
Predicate<Person> ruthFinder = (Person p) => { return p.Name == "Ruth"; };
Predicate<Person> seventeenYearOldFinder = (Person p) => { return p.Age == 17; };

Person oscar = people.Find(oscarFinder);
Person ruth = people.Find(ruthFinder);
Person seventeenYearOld = people.Find(seventeenYearOldFinder);

Notice I said a lot less code, not a lot faster. A common misconception developers have is that if something takes one line, it must perform better than something that takes ten lines. But behind the scenes, the Find method, which takes a Predicate<T>, is just enumerating after all. The same is true for a lot of Linq's functionality.

So let's take a look at the specific code in your question:

Predicate<int> pre = delegate(int a){ return a % 2 == 0; };

Here we have a Predicate<int> pre that takes an int a and returns a % 2 == 0. This is essentially testing for an even number. What that means is:

pre(1) == false;
pre(2) == true;

And so on. This also means, if you have a List<int> ints and you want to find the first even number, you can just do this:

int firstEven = ints.Find(pre);

Of course, as with any other type that you can use in code, it's a good idea to give your variables descriptive names; so I would advise changing the above pre to something like evenFinder or isEven -- something along those lines. Then the above code is a lot clearer:

int firstEven = ints.Find(evenFinder);

How to see local history changes in Visual Studio Code?

Basic Functionality

  • Automatically saved local edit history is available with the Local History extension.
  • Manually saved local edit history is available with the Checkpoints extension (this is the IntelliJ equivalent to adding tags to the local history).

Advanced Functionality

  • None of the extensions mentioned above support edit history when a file is moved or renamed.
  • The extensions above only support edit history. They do not support move/delete history, for example, like IntelliJ does.

Open Request

If you'd like to see this feature added natively, along with all of the advanced functionality, I'd suggest upvoting the open GitHub issue here.

Mask output of `The following objects are masked from....:` after calling attach() function

You actually don't need to use the attach at all. I had the same problem and it was resolved by removing the attach statement.

What are the lengths of Location Coordinates, latitude and longitude?

If the latitude coordinate is reported as -6.3572375290155 or -63.572375290155 in decimal degrees then you could round-off and store up to 6 decimal places for 10 cm (or 0.1 meters) precision.


The valid range of latitude in degrees is -90 and +90 for the southern and northern hemisphere respectively. Longitude is in the range -180 and +180 specifying coordinates west and east of the Prime Meridian, respectively.

For reference, the Equator has a latitude of 0°, the North pole has a latitude of 90° north (written 90° N or +90°), and the South pole has a latitude of -90°.

The Prime Meridian has a longitude of 0° that goes through Greenwich, England. The International Date Line (IDL) roughly follows the 180° longitude. A longitude with a positive value falls in the eastern hemisphere and the negative value falls in the western hemisphere.

Decimal degrees precision

Six (6) decimal places precision in coordinates using decimal degrees notation is at a 10 cm (or 0.1 meters) resolution. Each .000001 difference in coordinate decimal degree is approximately 10 cm in length. For example, the imagery of Google Earth and Google Maps is typically at the 1-meter resolution, and some places have a higher resolution of 1 inch per pixel. One meter resolution can be represented using 5 decimal places so more than 6 decimal places are extraneous for that resolution. The distance between longitudes at the equator is the same as latitude, but the distance between longitudes reaches zero at the poles as the lines of meridian converge at that point.

For millimeter (mm) precision then represent lat/lon with 8 decimal places in decimal degrees format. Since most applications don't need that level of precision 6 decimal places is sufficient for most cases.

In the other direction, whole decimal degrees represent a distance of ~111 km (or 60 nautical miles) and a 0.1 decimal degree difference represents a ~11 km distance.

Here is a table of # decimal places difference in latitude with the delta degrees and the estimated distance in meters using 0,0 as the starting point.

Decimal places Decimal degrees Distance (meters)
1 0.10000000 11,057.43 11 km
2 0.01000000 1,105.74 1 km
3 0.00100000 110.57
4 0.00010000 11.06
5 0.00001000 1.11
6 0.00000100 0.11 11 cm
7 0.00000010 0.01 1 cm
8 0.00000001 0.001 1 mm

Degrees-minute-second (DMS) representation

For DMS notation 1 arc second = 1/60/60 degree = ~30 meter length and 0.1 arc sec delta is ~3 meters.


  • 0° 0' 0" W, 0° 0' 0" N ? 0° 0' 0" W, 0° 0' 1" N ? 30.715 meters
  • 0° 0' 0" W, 0° 0' 0" N ? 0° 0' 0" W, 0° 0' 0.1" N ? 3.0715 meters

1 arc minute = 1/60 degree = ~2000m (2km)


Here is an amusing comic strip about coordinate precision.

convert strtotime to date time format in php

Here is exp.

$date_search_strtotime = strtotime(date("Y-m-d"));
echo 'Now strtotime date : '.$date_search_strtotime;
echo '<br>';
echo 'Now date from strtotime : '.date('Y-m-d',$date_search_strtotime);

Example of Named Pipes

For someone who is new to IPC and Named Pipes, I found the following NuGet package to be a great help.

GitHub: Named Pipe Wrapper for .NET 4.0

To use first install the package:

PS> Install-Package NamedPipeWrapper

Then an example server (copied from the link):

var server = new NamedPipeServer<SomeClass>("MyServerPipe");
server.ClientConnected += delegate(NamedPipeConnection<SomeClass> conn)
        Console.WriteLine("Client {0} is now connected!", conn.Id);
        conn.PushMessage(new SomeClass { Text: "Welcome!" });

server.ClientMessage += delegate(NamedPipeConnection<SomeClass> conn, SomeClass message)
        Console.WriteLine("Client {0} says: {1}", conn.Id, message.Text);


Example client:

var client = new NamedPipeClient<SomeClass>("MyServerPipe");
client.ServerMessage += delegate(NamedPipeConnection<SomeClass> conn, SomeClass message)
        Console.WriteLine("Server says: {0}", message.Text);


Best thing about it for me is that unlike the accepted answer here it supports multiple clients talking to a single server.

Best way to store password in database

You are correct that storing the password in a plain-text field is a horrible idea. However, as far as location goes, for most of the cases you're going to encounter (and I honestly can't think of any counter-examples) storing the representation of a password in the database is the proper thing to do. By representation I mean that you want to hash the password using a salt (which should be different for every user) and a secure 1-way algorithm and store that, throwing away the original password. Then, when you want to verify a password, you hash the value (using the same hashing algorithm and salt) and compare it to the hashed value in the database.

So, while it is a good thing you are thinking about this and it is a good question, this is actually a duplicate of these questions (at least):

To clarify a bit further on the salting bit, the danger with simply hashing a password and storing that is that if a trespasser gets a hold of your database, they can still use what are known as rainbow tables to be able to "decrypt" the password (at least those that show up in the rainbow table). To get around this, developers add a salt to passwords which, when properly done, makes rainbow attacks simply infeasible to do. Do note that a common misconception is to simply add the same unique and long string to all passwords; while this is not horrible, it is best to add unique salts to every password. Read this for more.

How to have click event ONLY fire on parent DIV, not children?

I had the same problem and came up with this solution (based on the other answers)

 $( ".newsletter_background" ).click(function(e) {
    if ( == this) {

Basically it says if the target is the div then run the code otherwise do nothing (don't hide it)

What is the --save option for npm install?

Update as of npm 5:

As of npm 5.0.0, installed modules are added as a dependency by default, so the --save option is no longer needed. The other save options still exist and are listed in the documentation for npm install.

Original answer:

It won't do anything if you don't have a package.json file. Start by running npm init to create one. Then calls to npm install --save or npm install --save-dev or npm install --save-optional will update the package.json to list your dependencies.

Replace specific text with a redacted version using Python

You can do it using named-entity recognition (NER). It's fairly simple and there are out-of-the-shelf tools out there to do it, such as spaCy.

NER is an NLP task where a neural network (or other method) is trained to detect certain entities, such as names, places, dates and organizations.


Sponge Bob went to South beach, he payed a ticket of $200!
I know, Michael is a good person, he goes to McDonalds, but donates to charity at St. Louis street.


NER with spacy

Just be aware that this is not 100%!

Here are a little snippet for you to try out:

import spacy

phrases = ['Sponge Bob went to South beach, he payed a ticket of $200!', 'I know, Michael is a good person, he goes to McDonalds, but donates to charity at St. Louis street.']
nlp = spacy.load('en')
for phrase in phrases:
   doc = nlp(phrase)
   replaced = ""
   for token in doc:
      if token in doc.ents:
         replaced+="XXXX "
         replaced+=token.text+" "

Read more here:

You could, instead of replacing with XXXX, replace based on the entity type, like:

if ent.label_ == "PERSON":
   replaced += "<PERSON> "


import re, random

personames = ["Jack", "Mike", "Bob", "Dylan"]

phrase = re.replace("<PERSON>", random.choice(personames), phrase)

How to get a complete list of ticker symbols from Yahoo Finance?

Complete list of yahoo symbols/tickers/stocks is available for download(excel format) at below website.

List updated to january 2016:

Powershell command to hide user from exchange address lists

For Office 365 users or Hybrid exchange, go to using Internet Explorer or Edge, go to the exchange admin center, choose hybrid, setup, chose the right button for hybrid or exchange online.

To connect:


To see the relevant mailboxes:

Get-mailbox -filter {ExchangeUserAccountControl -eq 'AccountDisabled' -and RecipientType -eq 'UserMailbox' -and RecipientTypeDetails -ne 'SharedMailbox' }

To block based on the above idea of 0KB size:

Get-mailbox -filter {ExchangeUserAccountControl -eq 'AccountDisabled' -and RecipientTypeDetails -ne 'SharedMailbox' -and RecipientType -eq 'UserMailbox' } | Set-Mailbox -MaxReceiveSize 0KB -HiddenFromAddressListsEnabled $true

How to create .ipa file using Xcode?

Easiest way, follow the steps :

step 1: After Archive project, right click on project and select show in finder

step 2: Right click on that project and select show as Show package contents, in that go to Products>Applications

step 3: Right click on

step 4: Copy into a empty folder and zip the folder(

step 5: Change the zipfolder extension to .ipa( -> foldername.ipa)

step 6: Now you have the final .ipa file

Draggable div without jQuery UI

here's another way of making a draggable object that is centered to the click

function endMove() {

function startMove() {
    $('.movable').on('mousemove', function(event) {
        var thisX = event.pageX - $(this).width() / 2,
            thisY = event.pageY - $(this).height() / 2;

            left: thisX,
            top: thisY
$(document).ready(function() {
    $("#containerDiv").on('mousedown', function() {
    }).on('mouseup', function() {



#containerDiv {

Are static class variables possible in Python?

You could also enforce a class to be static using metaclass.

class StaticClassError(Exception):

class StaticClass:
    __metaclass__ = abc.ABCMeta

    def __new__(cls, *args, **kw):
        raise StaticClassError("%s is a static class and cannot be initiated."
                                % cls)

class MyClass(StaticClass):
    a = 1
    b = 3

    def add(x, y):
        return x+y

Then whenever by accident you try to initialize MyClass you'll get an StaticClassError.

header location not working in my php code

It should be Location not location:

header('Location: index.php');

Cannot implicitly convert type 'string' to 'System.Threading.Tasks.Task<string>'

    public async Task<string> methodName()
             return Data;


Hope this helps :)

How to work with complex numbers in C?

The notion of complex numbers was introduced in mathematics, from the need of calculating negative quadratic roots. Complex number concept was taken by a variety of engineering fields.

Today that complex numbers are widely used in advanced engineering domains such as physics, electronics, mechanics, astronomy, etc...

Real and imaginary part, of a negative square root example:

#include <stdio.h>   
#include <complex.h>

int main() 
    int negNum;

    printf("Calculate negative square roots:\n"
           "Enter negative number:");

    scanf("%d", &negNum);

    double complex negSqrt = csqrt(negNum);

    double pReal = creal(negSqrt);
    double pImag = cimag(negSqrt);

    printf("\nReal part %f, imaginary part %f"
           ", for negative square root.(%d)",
           pReal, pImag, negNum);

    return 0;

HashMaps and Null values?

Its a good programming practice to avoid having null values in a Map.

If you have an entry with null value, then it is not possible to tell whether an entry is present in the map or has a null value associated with it.

You can either define a constant for such cases (Example: String NOT_VALID = "#NA"), or you can have another collection storing keys which have null values.

Please check this link for more details.

How do I stop/start a scheduled task on a remote computer programmatically?

What about /disable, and /enable switch for a /change command?

schtasks.exe /change /s <machine name> /tn <task name> /disable
schtasks.exe /change /s <machine name> /tn <task name> /enable

How to change to an older version of Node.js

For some reason Brew installs node 5 into a separate directory called node5.

The steps I took to get back to version 5 were: (You will need to look up standard brew installation/uninstallation, but otherwise this process is more straightforward than it looks.)

  1. Install node5 using Brew standard installation, BUT don't brew link, yet.
  2. Uninstall all other versions of node using brew unlink node and brew uninstall node. You might need to use --force to remove one of the versions.
  3. Find the cellar folder on your computer
  4. Delete the node folder in the cellar.
  5. Rename the node5 folder to node.
  6. Then, brew link node

You should be all set with node 5.

How do I find out which keystore was used to sign an app?

To build on Paul Lammertsma's answer, this command will print the names and signatures of all APKs in the current dir (I'm using sh because later I need to pipe the output to grep):

find . -name "*.apk" -exec echo "APK: {}" \; -exec sh -c 'keytool -printcert -jarfile "{}"' \;

Sample output:

APK: ./
Signer #1:


Owner: CN=Unknown, OU="Google, Inc", O="Google, Inc", L=Mountain View, ST=CA, C=US
Issuer: CN=Unknown, OU="Google, Inc", O="Google, Inc", L=Mountain View, ST=CA, C=US
Serial number: 4934987e
Valid from: Mon Dec 01 18:07:58 PST 2008 until: Fri Apr 18 19:07:58 PDT 2036
Certificate fingerprints:
         MD5:  D0:46:FC:5D:1F:C3:CD:0E:57:C5:44:40:97:CD:54:49
         SHA1: 24:BB:24:C0:5E:47:E0:AE:FA:68:A5:8A:76:61:79:D9:B6:13:A6:00
         SHA256: 3D:7A:12:23:01:9A:A3:9D:9E:A0:E3:43:6A:B7:C0:89:6B:FB:4F:B6:79:F4:DE:5F:E7:C2:3F:32:6C:8F:99:4A
         Signature algorithm name: MD5withRSA
         Version: 1

APK: ./
Signer #1:


Owner: CN=Unknown, OU="Google, Inc", O="Google, Inc", L=Mountain View, ST=CA, C=US
Issuer: CN=Unknown, OU="Google, Inc", O="Google, Inc", L=Mountain View, ST=CA, C=US
Serial number: 4934987e
Valid from: Mon Dec 01 18:07:58 PST 2008 until: Fri Apr 18 19:07:58 PDT 2036
Certificate fingerprints:
         MD5:  D0:46:FC:5D:1F:C3:CD:0E:57:C5:44:40:97:CD:54:49
         SHA1: 24:BB:24:C0:5E:47:E0:AE:FA:68:A5:8A:76:61:79:D9:B6:13:A6:00
         SHA256: 3D:7A:12:23:01:9A:A3:9D:9E:A0:E3:43:6A:B7:C0:89:6B:FB:4F:B6:79:F4:DE:5F:E7:C2:3F:32:6C:8F:99:4A
         Signature algorithm name: MD5withRSA
         Version: 1

Or if you just care about SHA1:

find . -name "*.apk" -exec echo "APK: {}" \; -exec sh -c 'keytool -printcert -jarfile "{}" | grep SHA1' \;

Sample output:

APK: ./
         SHA1: 24:BB:24:C0:5E:47:E0:AE:FA:68:A5:8A:76:61:79:D9:B6:13:A6:00
APK: ./
         SHA1: 24:BB:24:C0:5E:47:E0:AE:FA:68:A5:8A:76:61:79:D9:B6:13:A6:00

Equal sized table cells to fill the entire width of the containing table

Using table-layout: fixed as a property for table and width: calc(100%/3); for td (assuming there are 3 td's). With these two properties set, the table cells will be equal in size.

Refer to the demo.

How do I find the length of an array?

For C++/CX (when writing e.g. UWP apps using C++ in Visual Studio) we can find the number of values in an array by simply using the size() function.

Source Code:

string myArray[] = { "Example1", "Example2", "Example3", "Example4" };
int size_of_array=size(myArray);

If you cout the size_of_array the output will be:

>>> 4

How to make full screen background in a web page

um why not just set an image to the bottom layer and forgo all the annoyances

<img src='yourmom.png' style='position:fixed;top:0px;left:0px;width:100%;height:100%;z-index:-1;'>

Correct way to push into state array

Here you can not push the object to a state array like this. You can push like your way in normal array. Here you have to set the state,

     myArray: [...this.state.myArray, 'new value'] 

What is the shortest function for reading a cookie by name in JavaScript?

this in an object that you can read, write, overWrite and delete cookies.

var cookie = {
    write : function (cname, cvalue, exdays) {
        var d = new Date();
        d.setTime(d.getTime() + (exdays*24*60*60*1000));
        var expires = "expires="+d.toUTCString();
        document.cookie = cname + "=" + cvalue + "; " + expires;
    read : function (name) {
        if (document.cookie.indexOf(name) > -1) {
            return document.cookie.split(name)[1].split("; ")[0].substr(1)
        } else {
            return "";
    delete : function (cname) {
        var d = new Date();
        d.setTime(d.getTime() - 1000);
        var expires = "expires="+d.toUTCString();
        document.cookie = cname + "=; " + expires;

Using a custom typeface in Android

Although I am upvoting Manish's answer as the fastest and most targeted method, I have also seen naive solutions which just recursively iterate through a view hierarchy and update all elements' typefaces in turn. Something like this:

public static void applyFonts(final View v, Typeface fontToSet)
    try {
        if (v instanceof ViewGroup) {
            ViewGroup vg = (ViewGroup) v;
            for (int i = 0; i < vg.getChildCount(); i++) {
                View child = vg.getChildAt(i);
                applyFonts(child, fontToSet);
        } else if (v instanceof TextView) {
    } catch (Exception e) {
        // ignore

You would need to call this function on your views both after inflating layout and in your Activity's onContentChanged() methods.

Find size of Git repository

Note that, since git 1.8.3 (April, 22d 2013):

"git count-objects" learned "--human-readable" aka "-H" option to show various large numbers in Ki/Mi/GiB scaled as necessary.

That could be combined with the -v option mentioned by Jack Morrison in his answer.

git gc
git count-objects -vH

(git gc is important, as mentioned by A-B-B's answer)

Plus (still git 1.8.3), the output is more complete:

"git count-objects -v" learned to report leftover temporary packfiles and other garbage in the object store.

Understanding "VOLUME" instruction in DockerFile

To better understand the volume instruction in dockerfile, let us learn the typical volume usage in mysql official docker file implementation.

VOLUME /var/lib/mysql


The /var/lib/mysql is the default location of MySQL that store data files.

When you run test container for test purpose only, you may not specify its mounting point,e.g.

docker run mysql:8

then the mysql container instance will use the default mount path which is specified by the volume instruction in dockerfile. the volumes is created with a very long ID-like name inside the Docker root, this is called "unnamed" or "anonymous" volume. In the folder of underlying host system /var/lib/docker/volumes.


This is very convenient for quick test purposes without the need to specify the mounting point, but still can get best performance by using Volume for data store, not the container layer.

For a formal use, you will need to specify the mount path by using named volume or bind mount, e.g.

docker run  -v /my/own/datadir:/var/lib/mysql mysql:8

The command mounts the /my/own/datadir directory from the underlying host system as /var/lib/mysql inside the container.The data directory /my/own/datadir won't be automatically deleted, even the container is deleted.

Usage of the mysql official image (Please check the "Where to Store Data" section):


ldap query for group members

The good way to get all the members from a group is to, make the DN of the group as the searchDN and pass the "member" as attribute to get in the search function. All of the members of the group can now be found by going through the attribute values returned by the search. The filter can be made generic like (objectclass=*).

How to get ip address of a server on Centos 7 in bash

Something like this - a riff on @maarten-vanlinthout's answer

ip  -f inet a show eth0| grep inet| awk '{ print $2}' | cut -d/ -f1

Ternary operator ?: vs if...else

You are not forced to put it all on one line:-

x = y==1 ?
    :// else

It is much clearer than if/else because you can see immediately that both branches lead to x being assigned to.

How would I get everything before a : in a string Python

Just use the split function. It returns a list, so you can keep the first element:

>>> s1.split(':')
['Username', ' How are you today?']
>>> s1.split(':')[0]

Docker error : no space left on device

1. Remove Containers:

$ docker rm $(docker ps -aq)

2. Remove Images:

$ docker rmi $(docker images -q)

Instead of perform steps 1 and 2 you can do:

docker system prune

This command will remove:

  • All stopped containers
  • All volumes not used by at least one container
  • All networks not used by at least one container
  • All dangling images

Get value from SimpleXMLElement Object

try current($xml->code[0]->lat)

it returns element under current pointer of array, which is 0, so you will get value

Getting the index of a particular item in array

try Array.FindIndex(myArray, x => x.Contains("author"));

How To Save Canvas As An Image With canvas.toDataURL()?

You cannot use the methods previously mentioned to download an image when running in Cordova. You will need to use the Cordova File Plugin. This will allow you to pick where to save it and leverage different persistence settings. Details here:

Alternatively, you can convert the image to base64 then store the string in localStorage but this will fill your quota pretty quickly if you have many images or high-res.

Make columns of equal width in <table>

Use following property same as table and its fully dynamic:

ul {_x000D_
    width: 100%;_x000D_
    display: table;_x000D_
    table-layout: fixed; /* optional, for equal spacing */_x000D_
    border-collapse: collapse;_x000D_
li {_x000D_
    display: table-cell;_x000D_
    text-align: center;_x000D_
    border: 1px solid pink;_x000D_
    vertical-align: middle;_x000D_
  <li>baz klxjgkldjklg </li>_x000D_
  <li>baz lds.jklklds</li>_x000D_

May be its solve your issue.

JSON find in JavaScript

Ok. So, I know this is an old post, but perhaps this can help someone else. This is not backwards compatible, but that's almost irrelevant since Internet Explorer is being made redundant.

Easiest way to do exactly what is wanted:

function findInJson(objJsonResp, key, value, aType){        
        return objJsonResp.find(x=> x[key] == value);
         var a =objJsonResp.find(x=> x[key] == value);

It will return the item you want to edit if you supply 'edit' as the type. Supply anything else, or nothing, and it assumes delete. You can flip the conditionals if you'd prefer.

Difference between virtual and abstract methods

Abstract Method:

  • If an abstract method is defined in a class, then the class should declare as an abstract class.

  • An abstract method should contain only method definition, should not Contain the method body/implementation.

  • An abstract method must be over ride in the derived class.

Virtual Method:

  • Virtual methods can be over ride in the derived class but not mandatory.
  • Virtual methods must have the method body/implementation along with the definition.


public abstract class baseclass
            public abstract decimal getarea(decimal Radius);

            public virtual decimal interestpermonth(decimal amount)
                return amount*12/100;

            public virtual decimal totalamount(decimal Amount,decimal principleAmount)
                return Amount + principleAmount;

        public class derivedclass:baseclass
            public override decimal getarea(decimal Radius)
                return 2 * (22 / 7) * Radius;

            public override decimal interestpermonth(decimal amount)
                return amount * 14 / 100;

Automatically size JPanel inside JFrame

If the BorderLayout option provided by our friends doesnot work, try adding ComponentListerner to the JFrame and implement the componentResized(event) method. When the JFrame object will be resized, this method will be called. So if you write the the code to set the size of the JPanel in this method, you will achieve the intended result.

Ya, I know this 'solution' is not good but use it as a safety net. ;)

Python: Number of rows affected by cursor.execute("SELECT ...)

when using count(*) the result is {'count(*)': 9}

-- where 9 represents the number of rows in the table, for the instance.

So, in order to fetch the just the number, this worked in my case, using mysql 8.


Is this how you define a function in jQuery?

You can extend jQuery prototype and use your function as a jQuery method.

    $.fn.MyBlah = function(blah)
        console.log('blah class added');


More info on extending jQuery prototype here:

How do I hide anchor text without hiding the anchor?

a { text-indent:-9999px; }

Tends to work well from my exprience.

Uploading a file in Rails

In your intiallizer/carrierwave.rb

if Rails.env.development? || Rails.env.test? = :file
    config.root = "#{Rails.root}/public"
    if Rails.env.test?
      CarrierWave.configure do |config| = :file
        config.enable_processing = false

use this to store in a file while running on local

How to prevent "The play() request was interrupted by a call to pause()" error?

Chrome returns a Promise in newest versions. Otherwise, simply:

        n.currentTime = 0;
        setTimeout(function() {}, 0);

Select All distinct values in a column using LINQ

Interestingly enough I tried both of these in LinqPad and the variant using group from Dmitry Gribkov by appears to be quicker. (also the final distinct is not required as the result is already distinct.

My (somewhat simple) code was:

public class Pair 
    public int id {get;set;}
    public string Arb {get;set;}

void Main()

    var theList = new List<Pair>();
    var randomiser = new Random();
    for (int count = 1; count < 10000; count++)
        theList.Add(new Pair 
            id = randomiser.Next(1, 50),
            Arb = "not used"

    var timer = new Stopwatch();
    var distinct = theList.GroupBy(c => => p.First().id);

    var otherDistinct = theList.Select(p =>;

Why does dividing two int not yield the right value when assigned to double?

When you divide two integers, the result will be an integer, irrespective of the fact that you store it in a double.

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

Have a look at this excellent article Deep dive into the murky waters of script loading by the Google developer Jake Archibald written in 2013.

Quoting the relevant section from that article:


<script src="//" defer></script>
<script src="2.js" defer></script>

Spec says: Download together, execute in order just before DOMContentLoaded. Ignore “defer” on scripts without “src”.

IE < 10 says: I might execute 2.js halfway through the execution of 1.js. Isn’t that fun??

The browsers in red say: I have no idea what this “defer” thing is, I’m going to load the scripts as if it weren’t there.

Other browsers say: Ok, but I might not ignore “defer” on scripts without “src”.

(I'll add that early versions of Firefox trigger DOMContentLoaded before the defer scripts finish running, according to this comment.)

Modern browsers seem to support async properly, but you need to be OK with scripts running out of order and possibly before DOMContentLoaded.

Background image jumps when address bar hides iOS/Android/Mobile Chrome

Simple answer if your background allows, why not set background-size: to something just covering device width with media queries and use alongside the :after position: fixed; hack here.

IE: background-size: 901px; for any screens <900px? Not perfect or responsive but worked a charm for me on mobile <480px as i'm using an abstract BG.

How to set Sqlite3 to be case insensitive when string comparing?

This is not specific to sqlite but you can just do

SELECT * FROM ... WHERE UPPER(name) = UPPER('someone')

Which .NET Dependency Injection frameworks are worth looking into?

I can recommend Ninject. It's incredibly fast and easy to use but only if you don't need XML configuration, else you should use Windsor.

PHP Function with Optional Parameters

If you are commonly just passing in the 8th value, you can reorder your parameters so it is first. You only need to specify parameters up until the last one you want to set.

If you are using different values, you have 2 options.

One would be to create a set of wrapper functions that take different parameters and set the defaults on the others. This is useful if you only use a few combinations, but can get very messy quickly.

The other option is to pass an array where the keys are the names of the parameters. You can then just check if there is a value in the array with a key, and if not use the default. But again, this can get messy and add a lot of extra code if you have a lot of parameters.

Android Studio update -Error:Could not run build action using Gradle distribution

Try updating gradle dependency to 2.4. For that you need to go to File -> Project Structure -> Project -> Gradle version.

There you need to change from 2.2.1 to 2.4. Wait for new gradle version to be downloaded.

And you are ready to go.

Style bottom Line in Android

A Simple solution :

Create a drawable file as edittext_stroke.xml in drawable folder. Add the below code:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android=""
        android:color="@android:color/white" >

In layout file , add the drawable to edittext as



Saving an Excel sheet in a current directory with VBA

VBA has a CurDir keyword that will return the "current directory" as stored in Excel. I'm not sure all the things that affect the current directory, but definitely opening or saving a workbook will change it.

MyWorkbook.SaveAs CurDir & Application.PathSeparator & "MySavedWorkbook.xls"

This assumes that the sheet you want to save has never been saved and you want to define the file name in code.

Passing multiple parameters to function in Python

You could use a map function that allows multiple arguments, as does the fork of multiprocessing found in pathos.

>>> from pathos.multiprocessing import ProcessingPool as Pool
>>> def add_and_subtract(x,y):
...   return x+y, x-y
>>> res = Pool().map(add_and_subtract, range(0,20,2), range(-5,5,1))
>>> res
[(-5, 5), (-2, 6), (1, 7), (4, 8), (7, 9), (10, 10), (13, 11), (16, 12), (19, 13), (22, 14)]
>>> Pool().map(add_and_subtract, *zip(*res))
[(0, -10), (4, -8), (8, -6), (12, -4), (16, -2), (20, 0), (24, 2), (28, 4), (32, 6), (36, 8)]

pathos enables you to easily nest hierarchical parallel maps with multiple inputs, so we can extend our example to demonstrate that.

>>> from pathos.multiprocessing import ThreadingPool as TPool
>>> res = TPool().amap(add_and_subtract, *zip(*Pool().map(add_and_subtract, range(0,20,2), range(-5,5,1))))
>>> res.get()
[(0, -10), (4, -8), (8, -6), (12, -4), (16, -2), (20, 0), (24, 2), (28, 4), (32, 6), (36, 8)]

Even more fun, is to build a nested function that we can pass into the Pool. This is possible because pathos uses dill, which can serialize almost anything in python.

>>> def build_fun_things(f, g):
...   def do_fun_things(x, y):
...     return f(x,y), g(x,y)
...   return do_fun_things
>>> def add(x,y):
...   return x+y
>>> def sub(x,y):
...   return x-y
>>> neato = build_fun_things(add, sub)
>>> res = TPool().imap(neato, *zip(*Pool().map(neato, range(0,20,2), range(-5,5,1))))
>>> list(res)
[(0, -10), (4, -8), (8, -6), (12, -4), (16, -2), (20, 0), (24, 2), (28, 4), (32, 6), (36, 8)]

If you are not able to go outside of the standard library, however, you will have to do this another way. Your best bet in that case is to use multiprocessing.starmap as seen here: Python multiprocessing for multiple arguments (noted by @Roberto in the comments on the OP's post)

Get pathos here:

convert UIImage to NSData

Solution in Swift 4

extension UIImage {
    var data : Data? {
      return cgImage?.dataProvider?.data as Data?

Is there a short cut for going back to the beginning of a file by vi editor?

Typing in 0% takes you to the beginning.

100% takes you to the end.

50% takes you half way.

Changing Font Size For UITableView Section Headers

Swift 3:

Simplest way to adjust only size:

func tableView(_ tableView: UITableView, willDisplayHeaderView view: UIView, forSection section: Int) {

    let header = view as! UITableViewHeaderFooterView

    if let textlabel = header.textLabel {
        textlabel.font = textlabel.font.withSize(15)

Using the rJava package on Win7 64 bit with R

Sorry for necro. I have too run into the same issue and found out that rJava expects JAVA_HOME to point to JRE. If you have JDK installed, most probably your JAVA_HOME points to JDK. My quick solution:

Sys.setenv(JAVA_HOME=paste(Sys.getenv("JAVA_HOME"), "jre", sep="\\"))

HTML-5 date field shows as "mm/dd/yyyy" in Chrome, even when valid date is set

Had the same problem. A colleague solved this with jQuery.Globalize.

<script src="/Scripts/jquery.validate.js" type="text/javascript"></script>
<script src="/Scripts/jquery.globalize/globalize.js" type="text/javascript"></script>
<script src="/Scripts/jquery.globalize/cultures/"></script>
<script type="text/javascript">
    var lang = 'nl';

    $(function () {

    // fixing a weird validation issue with dates (nl date notation) and Google Chrome
    $ = function(value, element) {
        var d = Globalize.parseDate(value);
        return this.optional(element) || !/Invalid|NaN/.test(d);

I am using jQuery Datepicker for selecting the date.

How to convert string date to Timestamp in java?

Use below code to convert String Date to Epoc Timestamp. Note : - Your input Date format should match with SimpleDateFormat.

String inputDateInString= "8/15/2017 12:00:00 AM";
SimpleDateFormat dateFormat = new SimpleDateFormat("MM/dd/yyy hh:mm:ss");

Date parsedDate = dateFormat.parse("inputDateInString");

Timestamp timestamp = new java.sql.Timestamp(parsedDate.getTime());

System.out.println("Timestamp "+ timestamp.getTime());

iPad Web App: Detect Virtual Keyboard Using JavaScript in Safari?

During the focus event you can scroll past the document height and magically the window.innerHeight is reduced by the height of the virtual keyboard. Note that the size of the virtual keyboard is different for landscape vs. portrait orientations so you'll need to redetect it when it changes. I would advise against remembering these values as the user could connect/disconnect a bluetooth keyboard at any time.

var element = document.getElementById("element"); // the input field
var focused = false;

var virtualKeyboardHeight = function () {
    var sx = document.body.scrollLeft, sy = document.body.scrollTop;
    var naturalHeight = window.innerHeight;
    window.scrollTo(sx, document.body.scrollHeight);
    var keyboardHeight = naturalHeight - window.innerHeight;
    window.scrollTo(sx, sy);
    return keyboardHeight;

element.onfocus = function () {
    focused = true;
    setTimeout(function() { 
        element.value = "keyboardHeight = " + virtualKeyboardHeight() 
    }, 1); // to allow for orientation scrolling

window.onresize = function () {
    if (focused) {
        element.value = "keyboardHeight = " + virtualKeyboardHeight();

element.onblur = function () {
    focused = false;

Note that when the user is using a bluetooth keyboard, the keyboardHeight is 44 which is the height of the [previous][next] toolbar.

There is a tiny bit of flicker when you do this detection, but it doesn't seem possible to avoid it.

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

 Add jar files mail.jar,activation.jar,additionnal.jar

 String sub="Thank you for your online registration" ; 
 Mail m = new Mail("emailid", "password"); 

 String[] toArr = {"[email protected]",sEmailId};
 m.setFrom("[email protected]"); 



                            if(m.send()) { 

                            } else { 

                          } catch(Exception e) { 

                            Log.e("MailApp", "Could not send email", e); 

  package com.example.ekktra;

   import java.util.Date;
   import java.util.Properties;

   import javax.activation.CommandMap;
   import javax.activation.DataHandler;
   import javax.activation.DataSource;
   import javax.activation.FileDataSource;
   import javax.activation.MailcapCommandMap;
   import javax.mail.BodyPart;
   import javax.mail.Multipart;
   import javax.mail.PasswordAuthentication;
   import javax.mail.Session;
   import javax.mail.Transport;
   import javax.mail.internet.InternetAddress;
   import javax.mail.internet.MimeBodyPart;
   import javax.mail.internet.MimeMessage;
   import javax.mail.internet.MimeMultipart;

   public class Mail extends javax.mail.Authenticator { 
     private String _user; 
     private String _pass; 

     private String[] _to; 

     private String _from; 

     private String _port; 
     private String _sport; 

     private String _host; 

     private String _subject; 
     private String _body; 

     private boolean _auth; 

     private boolean _debuggable; 

     private Multipart _multipart; 

   public Mail() { 
      _host = ""; // default smtp server 
      _port = "465"; // default smtp port 
      _sport = "465"; // default socketfactory port 

      _user = ""; // username 
      _pass = ""; // password 
      _from = ""; // email sent from 
      _subject = ""; // email subject 
      _body = ""; // email body 

      _debuggable = false; // debug mode on or off - default off 
      _auth = true; // smtp authentication - default on 

      _multipart = new MimeMultipart(); 

      // There is something wrong with MailCap, javamail can not find a handler for the        multipart/mixed part, so this bit needs to be added. 
      MailcapCommandMap mc = (MailcapCommandMap) CommandMap.getDefaultCommandMap(); 
   mc.addMailcap("text/html;; x-java-content-handler=com.sun.mail.handlers.text_html"); 
   mc.addMailcap("text/xml;; x-java-content-handler=com.sun.mail.handlers.text_xml"); 
   mc.addMailcap("text/plain;; x-java-content-  handler=com.sun.mail.handlers.text_plain"); 
   mc.addMailcap("multipart/*;; x-java-content-handler=com.sun.mail.handlers.multipart_mixed"); 
   mc.addMailcap("message/rfc822;; x-java-content- handler=com.sun.mail.handlers.message_rfc822"); 

 public Mail(String user, String pass) { 

  _user = user; 
   _pass = pass; 

public boolean send() throws Exception { 
   Properties props = _setProperties(); 

  if(!_user.equals("") && !_pass.equals("") && _to.length > 0 && !_from.equals("") &&   !_subject.equals("") /*&& !_body.equals("")*/) { 
    Session session = Session.getInstance(props, this); 

    MimeMessage msg = new MimeMessage(session); 

     msg.setFrom(new InternetAddress(_from)); 

    InternetAddress[] addressTo = new InternetAddress[_to.length]; 
     for (int i = 0; i < _to.length; i++) { 
      addressTo[i] = new InternetAddress(_to[i]); 
      msg.setRecipients(MimeMessage.RecipientType.TO, addressTo); 

    msg.setSentDate(new Date()); 

  // setup message body 
  BodyPart messageBodyPart = new MimeBodyPart(); 

     // Put parts in message 

    // send email 

    return true; 
   } else { 
     return false; 

   public void addAttachment(String filename) throws Exception { 
    BodyPart messageBodyPart = new MimeBodyPart(); 
    DataSource source = new FileDataSource(filename); 
      messageBodyPart.setDataHandler(new DataHandler(source)); 


  public PasswordAuthentication getPasswordAuthentication() { 
     return new PasswordAuthentication(_user, _pass); 

   private Properties _setProperties() { 
   Properties props = new Properties(); 

    props.put("", _host); 

  if(_debuggable) { 
    props.put("mail.debug", "true"); 

  if(_auth) { 
    props.put("mail.smtp.auth", "true"); 

    props.put("mail.smtp.port", _port); 
    props.put("mail.smtp.socketFactory.port", _sport); 
    props.put("mail.smtp.socketFactory.class", ""); 
    props.put("mail.smtp.socketFactory.fallback", "false"); 

    return props; 

   // the getters and setters 
  public String getBody() { 
   return _body; 

 public void setBody(String _body) { 
  this._body = _body; 

  public void setTo(String[] toArr) {
     // TODO Auto-generated method stub

public void setFrom(String string) {
    // TODO Auto-generated method stub

 public void setSubject(String string) {
    // TODO Auto-generated method stub


Finding the average of an array using JS

The MacGyver way,just for lulz

var a = [80, 77, 88, 95, 68];_x000D_

Multi-line string with extra space (preserved indentation)

I've found more solutions since I wanted to have every line properly indented:

  1. You may use echo:

    echo    "this is line one"   \
        "\n""this is line two"   \
        "\n""this is line three" \
        > filename

    It does not work if you put "\n" just before \ on the end of a line.

  2. Alternatively, you can use printf for better portability (I happened to have a lot of problems with echo):

    printf '%s\n' \
        "this is line one"   \
        "this is line two"   \
        "this is line three" \
        > filename
  3. Yet another solution might be:

    text="${text}this is line one\n"
    text="${text}this is line two\n"
    text="${text}this is line three\n"
    printf "%b" "$text" > filename


    text+="this is line one\n"
    text+="this is line two\n"
    text+="this is line three\n"
    printf "%b" "$text" > filename
  4. Another solution is achieved by mixing printf and sed.

    if something
        printf '%s' '
        this is line one
        this is line two
        this is line three
        ' | sed '1d;$d;s/^    //g'

    It is not easy to refactor code formatted like this as you hardcode the indentation level into the code.

  5. It is possible to use a helper function and some variable substitution tricks:

    unset text
    _() { text="${text}${text+
    }${*}"; }
    # That's an empty line which demonstrates the reasoning behind 
    # the usage of "+" instead of ":+" in the variable substitution 
    # above.
    _ ""
    _ "this is line one"
    _ "this is line two"
    _ "this is line three"
    unset -f _
    printf '%s' "$text"

2D Euclidean vector rotations

You're calculating the y-part of your new coordinate based on the 'new' x-part of the new coordinate. Basically this means your calculating the new output in terms of the new output...

Try to rewrite in terms of input and output:

vector2<double> multiply( vector2<double> input, double cs, double sn ) {
  vector2<double> result;
  result.x = input.x * cs - input.y * sn;
  result.y = input.x * sn + input.y * cs;
  return result;

Then you can do this:

vector2<double> input(0,1);
vector2<double> transformed = multiply( input, cs, sn );

Note how choosing proper names for your variables can avoid this problem alltogether!

LINQ Orderby Descending Query

I think the second one should be

var itemList = (from t in ctn.Items
                where !t.Items && t.DeliverySelection
                select t).OrderByDescending(c => c.Delivery.SubmissionDate);

Calculate execution time of a SQL query?

We monitor this from the application code, just to include the time required to establish/close the connection and transmit data across the network. It's pretty straight-forward...

Dim Duration as TimeSpan
Dim StartTime as DateTime = DateTime.Now

'Call the database here and execute your SQL statement

Duration = DateTime.Now.Subtract(StartTime)
Console.WriteLine(String.Format("Query took {0} seconds", Duration.TotalSeconds.ToString()))

What is the difference between Swing and AWT?

Swing vs AWT. Basically AWT came first and is a set of heavyweight UI components (meaning they are wrappers for operating system objects) whereas Swing built on top of AWT with a richer set of lightweight components.

Any serious Java UI work is done in Swing not AWT, which was primarily used for applets.

How do I concatenate a boolean to a string in Python?

answer = True
myvar = "the answer is " + str(answer)

Python does not do implicit casting, as implicit casting can mask critical logic errors. Just cast answer to a string itself to get its string representation ("True"), or use string formatting like so:

myvar = "the answer is %s" % answer

Note that answer must be set to True (capitalization is important).

Use placeholders in yaml

I suppose would be an acceptable solution to your problem

How to round up value C# to the nearest integer?

Math.Round(0.5) returns zero due to floating point rounding errors, so you'll need to add a rounding error amount to the original value to ensure it doesn't round down, eg.

Console.WriteLine(Math.Round(0.5, 0).ToString()); // outputs 0 (!!)
Console.WriteLine(Math.Round(1.5, 0).ToString()); // outputs 2
Console.WriteLine(Math.Round(0.5 + 0.00000001, 0).ToString()); // outputs 1
Console.WriteLine(Math.Round(1.5 + 0.00000001, 0).ToString()); // outputs 2