Programs & Examples On #Copy protection

Copy protection, also known as content protection, copy obstruction, copy prevention and copy restriction, is any effort designed to prevent the reproduction of software, films, music, and other media, usually for copyright reasons.

How do I protect Python code?

I have looked at software protection in general for my own projects and the general philosophy is that complete protection is impossible. The only thing that you can hope to achieve is to add protection to a level that would cost your customer more to bypass than it would to purchase another license.

With that said I was just checking google for python obsfucation and not turning up a lot of anything. In a .Net solution, obsfucation would be a first approach to your problem on a windows platform, but I am not sure if anyone has solutions on Linux that work with Mono.

The next thing would be to write your code in a compiled language, or if you really want to go all the way, then in assembler. A stripped out executable would be a lot harder to decompile than an interpreted language.

It all comes down to tradeoffs. On one end you have ease of software development in python, in which it is also very hard to hide secrets. On the other end you have software written in assembler which is much harder to write, but is much easier to hide secrets.

Your boss has to choose a point somewhere along that continuum that supports his requirements. And then he has to give you the tools and time so you can build what he wants. However my bet is that he will object to real development costs versus potential monetary losses.

Get the Last Inserted Id Using Laravel Eloquent

Optional method will be:

$lastID = DB::table('EXAMPLE-TABLE')
                ->orderBy('id', 'desc')

$lastId = $lastProduct->id;

Source from Laravel 5.8 version

RS256 vs HS256: What's the difference?

In cryptography there are two types of algorithms used:

Symmetric algorithms

A single key is used to encrypt data. When encrypted with the key, the data can be decrypted using the same key. If, for example, Mary encrypts a message using the key "my-secret" and sends it to John, he will be able to decrypt the message correctly with the same key "my-secret".

Asymmetric algorithms

Two keys are used to encrypt and decrypt messages. While one key(public) is used to encrypt the message, the other key(private) can only be used to decrypt it. So, John can generate both public and private keys, then send only the public key to Mary to encrypt her message. The message can only be decrypted using the private key.

HS256 and RS256 Scenario

These algorithms are NOT used to encrypt/decryt data. Rather they are used to verify the origin or the authenticity of the data. When Mary needs to send an open message to Jhon and he needs to verify that the message is surely from Mary, HS256 or RS256 can be used.

HS256 can create a signature for a given sample of data using a single key. When the message is transmitted along with the signature, the receiving party can use the same key to verify that the signature matches the message.

RS256 uses pair of keys to do the same. A signature can only be generated using the private key. And the public key has to be used to verify the signature. In this scenario, even if Jack finds the public key, he cannot create a spoof message with a signature to impersonate Mary.

When using .net MVC RadioButtonFor(), how do you group so only one selection can be made?

In cases where the name attribute is different it is easiest to control the radio group via JQuery. When an option is selected use JQuery to un-select the other options.

What does <> mean?

"Does not equal"

How to write a caption under an image?

<tr><td><img ...><td><img ...>

Style as desired.

What is the "Upgrade-Insecure-Requests" HTTP header?

This explains the whole thing:

The HTTP Content-Security-Policy (CSP) upgrade-insecure-requests directive instructs user agents to treat all of a site's insecure URLs (those served over HTTP) as though they have been replaced with secure URLs (those served over HTTPS). This directive is intended for web sites with large numbers of insecure legacy URLs that need to be rewritten.

The upgrade-insecure-requests directive is evaluated before block-all-mixed-content and if it is set, the latter is effectively a no-op. It is recommended to set one directive or the other, but not both.

The upgrade-insecure-requests directive will not ensure that users visiting your site via links on third-party sites will be upgraded to HTTPS for the top-level navigation and thus does not replace the Strict-Transport-Security (HSTS) header, which should still be set with an appropriate max-age to ensure that users are not subject to SSL stripping attacks.


LINQ: "contains" and a Lambda query

If I understand correctly, you need to convert the type (char value) that you store in Building list to the type (enum) that you store in buildingStatus list.

(For each status in the Building list//character value//, does the status exists in the buildingStatus list//enum value//)

public static IQueryable<Building> WithStatus(this IQueryable<Building> qry,  
IList<BuildingStatuses> buildingStatus) 
    return from v in qry
           where ContainsStatus(v.Status)
           select v;

private bool ContainsStatus(v.Status)
    foreach(Enum value in Enum.GetValues(typeof(buildingStatus)))
        If v.Status == value.GetCharValue();
            return true;

    return false;

How to set default font family for entire Android app

to merely set typeface of app to normal, sans, serif or monospace(not to a custom font!), you can do this.

define a theme and set the android:typeface attribute to the typeface you want to use in styles.xml:


    <!-- custom normal activity theme -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
        <!-- other elements -->
        <item name="android:typeface">monospace</item>


apply the theme to the whole app in the AndroidManifest.xml file:

<?xml version="1.0" encoding="utf-8"?>
<manifest ... >
        android:theme="@style/AppTheme" >

android reference

Convert and format a Date in JSP

<%@page import="java.text.SimpleDateFormat"%>
<%@page import="java.util.Date"%>
<%@page import="java.util.Locale"%>

<title>Date Format</title>
String stringDate = "Fri May 13 2011 19:59:09 GMT 0530";
Date stringDate1 = new SimpleDateFormat("EEE MMM dd yyyy HH:mm:ss Z", Locale.ENGLISH).parse(stringDate);
String stringDate2 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(stringDate1);


c# datatable insert column at position 0

Just to improve Wael's answer and put it on a single line:

dt.Columns.Add("Better", typeof(Boolean)).SetOrdinal(0);

UPDATE: Note that this works when you don't need to do anything else with the DataColumn. Add() returns the column in question, SetOrdinal() returns nothing.

hash keys / values as array

Here is a good example of array_keys from PHP.js library:

function array_keys (input, search_value, argStrict) {
    // Return just the keys from the input array, optionally only for the specified search_value

    var search = typeof search_value !== 'undefined',
        tmp_arr = [],
        strict = !!argStrict,
        include = true,
        key = '';

    for (key in input) {
        if (input.hasOwnProperty(key)) {
            include = true;
            if (search) {
                if (strict && input[key] !== search_value) {
                    include = false;
                else if (input[key] != search_value) {
                    include = false;

            if (include) {
                tmp_arr[tmp_arr.length] = key;

    return tmp_arr;

The same goes for array_values (from the same PHP.js library):

function array_values (input) {
    // Return just the values from the input array  

    var tmp_arr = [],
        key = '';

    for (key in input) {
        tmp_arr[tmp_arr.length] = input[key];

    return tmp_arr;

EDIT: Removed unnecessary clauses from the code.

Android Studio Emulator and "Process finished with exit code 0"

You can try to delete the emulator and reinstall it this usually does the trick for me. Sometimes you also run into hiccups on your computer so try restarting your computer. Your computer may not be able to handle android studio if so there is nothing you can do. Consequently, you may not have the right ram requirements. Finally, If all else fails you can try to delete then reinstall android studio.

How to check if an object is a list or tuple (but not string)?

In "duck typing" manner, how about

    lst = lst + []
except TypeError:
    #it's not a list


    lst = lst + ()
except TypeError:
    #it's not a tuple

respectively. This avoids the isinstance / hasattr introspection stuff.

You could also check vice versa:

    lst = lst + ''
except TypeError:
    #it's not (base)string

All variants do not actually change the content of the variable, but imply a reassignment. I'm unsure whether this might be undesirable under some circumstances.

Interestingly, with the "in place" assignment += no TypeError would be raised in any case if lst is a list (not a tuple). That's why the assignment is done this way. Maybe someone can shed light on why that is.

How to randomly select rows in SQL?

I have found this to work best for big data.


TABLESAMPLE(n ROWS) or TABLESAMPLE(n PERCENT) is random but need to add the TOP n to get the correct sample size.

Using NEWID() is very slow on large tables.

How to get HttpRequestMessage data

From this answer:

public void Confirmation(HttpRequestMessage request)
    var content = request.Content;
    string jsonContent = content.ReadAsStringAsync().Result;

Note: As seen in the comments, this code could cause a deadlock and should not be used. See this blog post for more detail.

Read values into a shell variable from a pipe


IFS= read var << EOF

You can trick read into accepting from a pipe like this:

echo "hello world" | { read test; echo test=$test; }

or even write a function like this:

read_from_pipe() { read "$@" <&0; }

But there's no point - your variable assignments may not last! A pipeline may spawn a subshell, where the environment is inherited by value, not by reference. This is why read doesn't bother with input from a pipe - it's undefined.

FYI, is a nifty collection of the cruft necessary to fight the oddities and incompatibilities of bourne shells, sh.

Create a pointer to two-dimensional array


int *ptr= l_matrix[0];

you can access like


after all 2 dimensional arrays are also stored as 1-d.

Rails: select unique values from a column

If anyone is looking for the same with Mongoid, that is


Dealing with nginx 400 "The plain HTTP request was sent to HTTPS port" error

I ran into a similar problem. It works on one server and does not on another server with same Nginx configuration. Found the the solution which is answered by Igor here,1612,1627#msg-1627

Yes. Or you may combine SSL/non-SSL servers in one server:

server {
  listen 80;
  listen 443 default ssl;

  # ssl on   - remember to comment this out


How might I force a floating DIV to match the height of another floating DIV?

The correct solution for this problem is to use display: table-cell

Important: This solution doesn't need float since table-cell already turns the div into an element that lines up with the others in the same container. That also means you don't have to worry about clearing floats, overflow, background shining through and all the other nasty surprises that the float hack brings along to the party.


.container {
  display: table;
.column {
  display: table-cell;
  width: 100px;


<div class="container">
    <div class="column">Column 1.</div>
    <div class="column">Column 2 is a bit longer.</div>
    <div class="column">Column 3 is longer with lots of text in it.</div>


How to Run the Procedure?

In SQL Plus:

EXEC gokul_proc(1,'GOKUL', :rc);
print rc

Proper way to handle multiple forms on one page in Django

Django's class based views provide a generic FormView but for all intents and purposes it is designed to only handle one form.

One way to handle multiple forms with same target action url using Django's generic views is to extend the 'TemplateView' as shown below; I use this approach often enough that I have made it into an Eclipse IDE template.

class NegotiationGroupMultifacetedView(TemplateView):
    ### TemplateResponseMixin
    template_name = 'offers/offer_detail.html'

    ### ContextMixin 
    def get_context_data(self, **kwargs):
        """ Adds extra content to our template """
        context = super(NegotiationGroupDetailView, self).get_context_data(**kwargs)


        context['negotiation_bid_form'] = NegotiationBidForm(
            # Multiple 'submit' button paths should be handled in form's .save()/clean()
            data = self.request.POST if bool(set(['NegotiationBidForm-submit-counter-bid',
                                                    self.request.POST)) else None,
        context['offer_attachment_form'] = NegotiationAttachmentForm(
            data = self.request.POST if 'NegotiationAttachment-submit' in self.request.POST else None,
            files = self.request.FILES if 'NegotiationAttachment-submit' in self.request.POST else None
        context['offer_contact_form'] = NegotiationContactForm()
        return context

    ### NegotiationGroupDetailView 
    def post(self, request, *args, **kwargs):
        context = self.get_context_data(**kwargs)

        if context['negotiation_bid_form'].is_valid():
            instance = context['negotiation_bid_form'].save()
            messages.success(request, 'Your offer bid #{0} has been submitted.'.format(
        elif context['offer_attachment_form'].is_valid():
            instance = context['offer_attachment_form'].save()
            messages.success(request, 'Your offer attachment #{0} has been submitted.'.format(
                # advise of any errors

            messages.error('Error(s) encountered during form processing, please review below and re-submit')

        return self.render_to_response(context)

The html template is to the following effect:


<form id='offer_negotiation_form' class="content-form" action='./' enctype="multipart/form-data" method="post" accept-charset="utf-8">
    {% csrf_token %}
    {{ negotiation_bid_form.as_p }}
    <input type="submit" name="{{ negotiation_bid_form.prefix }}-submit-counter-bid" 
    title="Submit a counter bid"
    value="Counter Bid" />


<form id='offer-attachment-form' class="content-form" action='./' enctype="multipart/form-data" method="post" accept-charset="utf-8">
    {% csrf_token %}
    {{ offer_attachment_form.as_p }}

    <input name="{{ offer_attachment_form.prefix }}-submit" type="submit" value="Submit" />


Authentication issues with WWW-Authenticate: Negotiate

The web server is prompting you for a SPNEGO (Simple and Protected GSSAPI Negotiation Mechanism) token.

This is a Microsoft invention for negotiating a type of authentication to use for Web SSO (single-sign-on):

  • either NTLM
  • or Kerberos.


Android ClassNotFoundException: Didn't find class on path

I had this issue, raised by several causes, but i see this in your stacktrace "**Unable to instantiate activity ComponentInfo{...}: java.lang.ClassNotFoundException: Didn't find class "..." on path: DexPathList[[**", I found a diference in my .classpath before it stop working.

 <?xml version="1.0" encoding="UTF-8"?>
    <classpathentry kind="src" path="src"/>
    <classpathentry kind="con" path=""/>
    <classpathentry kind="con" path=""/>
    <classpathentry kind="src" path="gen"/>
    <classpathentry kind="output" path="bin/classes"/>

I've ADDED the line:

<classpathentry exported="true" kind="con" path=""/>

this is the final version:

  <?xml version="1.0" encoding="UTF-8"?>
    <classpathentry kind="src" path="src"/>
    <classpathentry kind="con" path=""/>
    <classpathentry kind="con" path=""/>
    <classpathentry exported="true" kind="con" path=""/>
    <classpathentry kind="src" path="gen"/>
    <classpathentry kind="output" path="bin/classes"/>

Now it works! =)

Git Diff with Beyond Compare

For MAC after doing lot of research it worked for me..! 1. Install the beyond compare and this will be installed in below location


Please follow these steps to make bc as diff/merge tool in git

How to access the elements of a function's return array?

function give_array(){

    $a = "abc";
    $b = "def";
    $c = "ghi";

    return compact('a','b','c');

$my_array = give_array();

Make a bucket public in Amazon S3

You can set a bucket policy as detailed in this blog post:

As per @robbyt's suggestion, create a bucket policy with the following JSON:

  "Version": "2008-10-17",
  "Statement": [{
    "Sid": "AllowPublicRead",
    "Effect": "Allow",
    "Principal": { "AWS": "*" },
    "Action": ["s3:GetObject"],
    "Resource": ["arn:aws:s3:::bucket/*" ]

Important: replace bucket in the Resource line with the name of your bucket.

How can I get a uitableViewCell by indexPath?

For Swift 4

    let indexPath = IndexPath(row: 0, section: 0)
    let cell = tableView.cellForRow(at: indexPath)

FORCE INDEX in MySQL - where do I put it?

FORCE_INDEX is going to be deprecated after MySQL 8:

Thus, you should expect USE INDEX, FORCE INDEX, and IGNORE INDEX to be deprecated in 
a future release of MySQL, and at some time thereafter to be removed altogether.

You should be using JOIN_INDEX, GROUP_INDEX, ORDER_INDEX, and INDEX instead, for v8.

Convert HTML string to image

Thanks all for your responses. I used HtmlRenderer external dll (library) to achieve the same and found below code for the same.

Here is the code for this

public void ConvertHtmlToImage()
   Bitmap m_Bitmap = new Bitmap(400, 600);
   PointF point = new PointF(0, 0);
   SizeF maxSize = new System.Drawing.SizeF(500, 500);
                                           "<html><body><p>This is some html code</p>"
                                           + "<p>This is another html line</p></body>",
                                            point, maxSize);

   m_Bitmap.Save(@"C:\Test.png", ImageFormat.Png);

Copy file from source directory to binary directory using CMake

if you want to copy folder from currant directory to binary (build folder) folder


then the syntexe is :

file(COPY pathSource DESTINATION pathDistination)

Error inflating class fragment

As hdemirchian said, make sure to use:


And also make sure that the Activity that is using the fragment(s) extends FragmentActivity instead of the regular Activity,


to get the FragmentActivity class.


Try this

UPDATE `table` SET `uid` = CASE
    WHEN id = 1 THEN 2952
    WHEN id = 2 THEN 4925
    WHEN id = 3 THEN 1592
    ELSE `uid`
WHERE id  in (1,2,3)

how to run python files in windows command prompt?

First set path of python

and run python file


command line argument with python

python command-line argument

Remove HTML Tags from an NSString on the iPhone

#import "RegexKitLite.h"

string text = [html stringByReplacingOccurrencesOfRegex:@"<[^>]+>" withString:@""]

Why does the C++ STL not provide any "tree" containers?

In a way, std::map is a tree (it is required to have the same performance characteristics as a balanced binary tree) but it doesn't expose other tree functionality. The likely reasoning behind not including a real tree data structure was probably just a matter of not including everything in the stl. The stl can be looked as a framework to use in implementing your own algorithms and data structures.

In general, if there's a basic library functionality that you want, that's not in the stl, the fix is to look at BOOST.

Otherwise, there's a bunch of libraries out there, depending on the needs of your tree.

sort dict by value python

Sort the values:




Is ncurses available for windows?

Such a thing probably does not exist "as-is". It doesn't really exist on Linux or other UNIX-like operating systems either though.

ncurses is only a library that helps you manage interactions with the underlying terminal environment. But it doesn't provide a terminal emulator itself.

The thing that actually displays stuff on the screen (which in your requirement is listed as "native resizable win32 windows") is usually called a Terminal Emulator. If you don't like the one that comes with Windows (you aren't alone; no person on Earth does) there are a few alternatives. There is Console, which in my experience works sometimes and appears to just wrap an underlying Windows terminal emulator (I don't know for sure, but I'm guessing, since there is a menu option to actually get access to that underlying terminal emulator, and sure enough an old crusty Windows/DOS box appears which mirrors everything in the Console window).

A better option

Another option, which may be more appealing is puttycyg. It hooks in to Putty (which, coming from a Linux background, is pretty close to what I'm used to, and free) but actually accesses an underlying cygwin instead of the Windows command interpreter (CMD.EXE). So you get all the benefits of Putty's awesome terminal emulator, as well as nice ncurses (and many other) libraries provided by cygwin. Add a couple command line arguments to the Shortcut that launches Putty (or the Batch file) and your app can be automatically launched without going through Putty's UI.

Regex to validate password strength

Another solution:

import re

passwordRegex = re.compile(r'''(
    ^(?=.*[A-Z].*[A-Z])                # at least two capital letters
    (?=.*[!@#$&*])                     # at least one of these special c-er
    (?=.*[0-9].*[0-9])                 # at least two numeric digits
    (?=.*[a-z].*[a-z].*[a-z])          # at least three lower case letters
    .{8,}                              # at least 8 total digits
    )''', re.VERBOSE)

def userInputPasswordCheck():
    print('Enter a potential password:')
    while True:
        m = input()
        mo = 
        if (not mo):
Your password should have at least one special charachter,
two digits, two uppercase and three lowercase charachter. Length: 8+ ch-ers.

Enter another password:''')          
           print('Password is strong')

Remove items from one list in another

Solution 1 : You can do like this :

List<car> result = GetSomeOtherList().Except(GetTheList()).ToList();

But in some cases may this solution not work. if it is not work you can use my second solution .

Solution 2 :

List<car> list1 = GetTheList();
List<car> list2 = GetSomeOtherList();

we pretend that list1 is your main list and list2 is your secondry list and you want to get items of list1 without items of list2.

 var result =  list1.Where(p => !list2.Any(x => x.ID == p.ID && x.property1 == p.property1)).ToList();

How to get current language code with Swift?

Swift 5.3:

let languagePrefix = Locale.preferredLanguages[0]

Is there a way to use PhantomJS in Python?

Here's how I test javascript using PhantomJS and Django:


var page = require('webpage').create(),
    system = require('system'),
    url = system.args[1],

page.onError = function (msg, trace) {
    trace.forEach(function(item) {
        console.log('  ', item.file, ':', item.line);

page.onResourceReceived = function(resource) {
    if (resource.url == url) {
        status_code = resource.status;
};, function (status) {
    if (status == "fail" || status_code != 200) {
        console.log("Error: " + status_code + " for url: " + url);


import subprocess
from django.test import LiveServerTestCase

class MobileTest(LiveServerTestCase):
    def test_mobile_js(self):
        args = ["phantomjs", "mobile/test_no_js_errors.js", self.live_server_url]
        result = subprocess.check_output(args)
        self.assertEqual(result, "")  # No result means no error

Run tests: test mobile

Getting Excel to refresh data on sheet from within VBA

I had an issue with turning off a background image (a DRAFT watermark) in VBA. My change wasn't showing up (which was performed with the Sheets(1).PageSetup.CenterHeader = "" method) - so I needed a way to refresh. The ActiveSheet.EnableCalculation approach partly did the trick, but didn't cover unused cells.

In the end I found what I needed with a one liner that made the image vanish when it was no longer set :-

Application.ScreenUpdating = True

can you add HTTPS functionality to a python flask web server?

Deploy Flask on a real web server, rather than with the built-in (development) server.

See the Deployment Options chapter of the Flask documentation. Servers like Nginx and Apache both can handle setting up HTTPS servers rather than HTTP servers for your site.

The standalone WSGI servers listed would typically be deployed behind Nginx and Apache in a proxy-forwarding configuration, where the front-end server handles the SSL encryption for you still.

How to get primary key column in Oracle?

Same as the answer from 'Richie' but a bit more concise.

  1. Query for user constraints only

    SELECT column_name FROM all_cons_columns WHERE constraint_name = (
      SELECT constraint_name FROM user_constraints 
      WHERE UPPER(table_name) = UPPER('tableName') AND CONSTRAINT_TYPE = 'P'
  2. Query for all constraints

    SELECT column_name FROM all_cons_columns WHERE constraint_name = (
      SELECT constraint_name FROM all_constraints 
      WHERE UPPER(table_name) = UPPER('tableName') AND CONSTRAINT_TYPE = 'P'

Simple If/Else Razor Syntax

Just use this for the closing tag:


And leave your if/else as is.

Seems like the if statement doesn't wanna' work.

It works fine. You're working in 2 language-spaces here, it seems only proper not to split open/close sandwiches over the border.

How to style the <option> with only CSS?

There is no cross-browser way of styling option elements, certainly not to the extent of your second screenshot. You might be able to make them bold, and set the font-size, but that will be about it...

Java current machine name and logged in user?

To get the currently logged in user:

System.getProperty(""); //platform independent 

and the hostname of the machine: localMachine =;
System.out.println("Hostname of local machine: " + localMachine.getHostName());

I cannot access tomcat admin console?

Notice that the http code response status you are getting is an HTTP 404. The 404 or Not Found error message is a response code indicating that the client was able to communicate with a given server, but the server could not find what was requested.

If you have got an 403 Forbidden vs 401 Unauthorized HTTP responses then it might make a sense to review your tomcat-users.xml.

Resuming: check the manager resources and files of your server installation, some file/directory might be missing, or the path to the manager resources has been changed.

Python: How exactly can you take a string, split it, reverse it and join it back together again?

Do you mean like this?

import string

deleter=string.maketrans('()[]','    ')
# a b c  d
# ['a', 'b', 'c', 'd']
# ['d', 'c', 'b', 'a']
print(' '.join(reversed(astr.translate(deleter).split())))
# d c b a

Laravel Eloquent Join vs Inner Join?

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

You could build it like this:


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

Build the feed model like so:


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

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

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

Then keep it up to date with something like:


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

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

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

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


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

Capturing multiple line output into a Bash variable

In addition to the answer given by @l0b0 I just had the situation where I needed to both keep any trailing newlines output by the script and check the script's return code. And the problem with l0b0's answer is that the 'echo x' was resetting $? back to zero... so I managed to come up with this very cunning solution:

RESULTX="$(./myscript; echo x$?)"

MySQL - UPDATE multiple rows with different values in one query

You can do it this way:

UPDATE table_users
    SET cod_user = (case when user_role = 'student' then '622057'
                         when user_role = 'assistant' then '2913659'
                         when user_role = 'admin' then '6160230'
        date = '12082014'
    WHERE user_role in ('student', 'assistant', 'admin') AND
          cod_office = '17389551';

I don't understand your date format. Dates should be stored in the database using native date and time types.

android: data binding error: cannot find symbol class

I have got the same error, but with Kotlin usage.

To resolve it, i make some changes in gradles files :

In project's Gradle file :

dependencies {
    classpath ""
    classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.2.40"

In app's Gradle file :

dependencies {

    implementation "android.arch.lifecycle:extensions:1.1.1"
    compile "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.2.30"
    kapt ''

kapt {
    generateStubs = true

//used to resolve annotation conflicts
configurations.all {
    resolutionStrategy {
        force ''

How can building a heap be O(n) time complexity?

It would be O(n log n) if you built the heap by repeatedly inserting elements. However, you can create a new heap more efficiently by inserting the elements in arbitrary order and then applying an algorithm to "heapify" them into the proper order (depending on the type of heap of course).

See, "Building a heap" for an example. In this case you essentially work up from the bottom level of the tree, swapping parent and child nodes until the heap conditions are satisfied.

PostgreSQL IF statement

Just to help if anyone stumble on this question like me, if you want to use if in PostgreSQL, you use "CASE"

        when stage = 1 then 'running'
        when stage = 2 then 'done'
        when stage = 3 then 'stopped'
        'not running'
    end as run_status from processes

How to parse a String containing XML in Java and retrieve the value of the root node?

There is doing XML reading right, or doing the dodgy just to get by. Doing it right would be using proper document parsing.

Or... dodgy would be using custom text parsing with either wisuzu's response or using regular expressions with matchers.

How to use a SQL SELECT statement with Access VBA

If you wish to use the bound column value, you can simply refer to the combo:

sSQL = "SELECT * FROM MyTable WHERE ID = " & Me.MyCombo

You can also refer to the column property:

sSQL = "SELECT * FROM MyTable WHERE AText = '" & Me.MyCombo.Column(1) & "'"

Dim rs As DAO.Recordset     
Set rs = CurrentDB.OpenRecordset(sSQL)

strText = rs!AText
strText = rs.Fields(1)

In a textbox:

= DlookUp("AText","MyTable","ID=" & MyCombo)


How to change root logging level programmatically for logback

I seem to be having success doing

org.jboss.logmanager.Logger logger = org.jboss.logmanager.Logger.getLogger("");

Then to get detailed logging from netty, the following has done it


Center a H1 tag inside a DIV

There is a new way using transforms. Apply this to the element to centre. It nudges down by half the container height and then 'corrects' by half the element height.

position: relative;
top: 50%;
transform: translateY(-50%);
-webkit-transform: translateY(-50%);
-ms-transform: translateY(-50%);

It works most of the time. I did have a problem where a div was in a div in a li. The list item had a height set and the outer divs made up 3 columns (Foundation). The 2nd and 3rd column divs contained images, and they centered just fine with this technique, however the heading in the first column needed a wrapping div with an explicit height set.

Now, does anyone know if the CSS people are working on a way to align stuff, like, easily? Seeing that its 2014 and even some of my friends are regularly using the internet, I wondered if anyone had considered that centering would be a useful styling feature yet. Just us then?

Are members of a C++ struct initialized to 0 by default?

Since this is a POD (essentially a C struct) there is little harm in initialising it the C way:

Snapshot s;
memset(&s, 0, sizeof (s));

or similarly

Snapshot *sp = new Snapshot;
memset(sp, 0, sizeof (*sp));

I wouldn't go so far as to use calloc() in a C++ program though.

AttributeError: 'datetime' module has no attribute 'strptime'

If I had to guess, you did this:

import datetime

at the top of your code. This means that you have to do this:

datetime.datetime.strptime(date, "%Y-%m-%d")

to access the strptime method. Or, you could change the import statement to this:

from datetime import datetime

and access it as you are.

The people who made the datetime module also named their class datetime:

#module  class    method
datetime.datetime.strptime(date, "%Y-%m-%d")

How to pass html string to webview on android

I was using some buttons with some events, converted image file coming from server. Loading normal data wasn't working for me, converting into Base64 working just fine.

String unencodedHtml ="<html><body>'%28' is the code for '('</body></html>";
tring encodedHtml = Base64.encodeToString(unencodedHtml.getBytes(), Base64.NO_PADDING);
webView.loadData(encodedHtml, "text/html", "base64");

Find details on WebView

Write lines of text to a file in R

I would use the cat() command as in this example:

> cat("Hello",file="outfile.txt",sep="\n")
> cat("World",file="outfile.txt",append=TRUE)

You can then view the results from with R with


How can I have grep not print out 'No such file or directory' errors?

Have you tried the -0 option in xargs? Something like this:

ls -r1 | xargs -0 grep 'some text'

Laravel Advanced Wheres how to pass variable into function?

@kajetons' answer is fully functional.

You can also pass multiple variables by passing them like: use($var1, $var2)

DB::table('users')->where(function ($query) use ($activated,$var2) {
    $query->where('activated', '=', $activated);
    $query->where('var2', '>', $var2);

Randomize numbers with jQuery?

Javascript has a random() available. Take a look at Math.random().

How do I associate file types with an iPhone application?

BIG WARNING: Make ONE HUNDRED PERCENT sure that your extension is not already tied to some mime type.

We used the extension '.icz' for our custom files for, basically, ever, and Safari just never would let you open them saying "Safari cannot open this file." no matter what we did or tried with the UT stuff above.

Eventually I realized that there are some UT* C functions you can use to explore various things, and while .icz gives the right answer (our app):

In app did load at top, just do this...

NSString * UTI = (NSString *)UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, 
CFURLRef ur =UTTypeCopyDeclaringBundleURL(UTI);

and put break after that line and see what UTI and ur are -- in our case, it was our identifier as we wanted), and the bundle url (ur) was pointing to our app's folder.

But the MIME type that Dropbox gives us back for our link, which you can check by doing e.g.

$ curl -D headers THEURLGOESHERE > /dev/null
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 27393  100 27393    0     0  24983      0  0:00:01  0:00:01 --:--:-- 28926
$ cat headers
HTTP/1.1 200 OK
accept-ranges: bytes
cache-control: max-age=0
content-disposition: attachment; filename="123.icz"
Content-Type: text/calendar
Date: Fri, 24 May 2013 17:41:28 GMT
etag: 872926d
pragma: public
Server: nginx
x-dropbox-request-id: 13bd327248d90fde
X-RequestId: bf9adc56934eff0bfb68a01d526eba1f
x-server-response-time: 379
Content-Length: 27393
Connection: keep-alive

The Content-Type is what we want. Dropbox claims this is a text/calendar entry. Great. But in my case, I've ALREADY TRIED PUTTING text/calendar into my app's mime types, and it still doesn't work. Instead, when I try to get the UTI and bundle url for the text/calendar mimetype,

NSString * UTI = (NSString *)UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType,

CFURLRef ur =UTTypeCopyDeclaringBundleURL(UTI);

I see "" as the UTI and ".../MobileCoreTypes.bundle/" as the bundle URL. Not our app, but Apple. So I try putting into the LSItemContentTypes alongside my own, and into UTConformsTo in the export, but no go.

So basically, if Apple thinks they want to at some point handle some form of file type (that could be created 10 years after your app is live, mind you), you will have to change extension cause they'll simply not let you handle the file type.

select data up to a space?

select left(col, charindex(' ', col) - 1)

Finding element's position relative to the document

You can get top and left without traversing DOM like this:

function getCoords(elem) { // crossbrowser version
    var box = elem.getBoundingClientRect();

    var body = document.body;
    var docEl = document.documentElement;

    var scrollTop = window.pageYOffset || docEl.scrollTop || body.scrollTop;
    var scrollLeft = window.pageXOffset || docEl.scrollLeft || body.scrollLeft;

    var clientTop = docEl.clientTop || body.clientTop || 0;
    var clientLeft = docEl.clientLeft || body.clientLeft || 0;

    var top  = +  scrollTop - clientTop;
    var left = box.left + scrollLeft - clientLeft;

    return { top: Math.round(top), left: Math.round(left) };

Which programming language for cloud computing?

As for what programming languages, any browser-based or server-based language is likely to be used. Javascript, PHP, ASP, AJAX, Perl, Java, SQL.

Let's say you need to implement a new programming language and BCL designed specifically for operating in the cloud (it won't be used on client machines ever). It should be optimized for cloud computing; easy to learn, fast, efficient, powerful, modern.

The biggest way i’ve seen cloud hosting products help out developers is the ability to launch and increase the size of a server, without having any kind of delay. Developers are able to create the application in a completely customized environment, and then expand it into a production machine with a significant hassle. If things don’t work as wanted, they can then destroy that machine with relative ease.

Most of the Cloud Computing Providers used JAVA and C-Sharp, to make cloud server.

ORA-12154: TNS:could not resolve the connect identifier specified (PLSQL Developer)

As I can't add a comment, just thought I'd post this for completion. tufy's answer is correct, it's to do with parenthesis (brackets) in the path to the application being run.

There is an existing networking bug where the networking layer is unable to parse program locations that contain parenthesis in the path to the executable which is attempting to connect to Oracle.

Filed with Oracle, Bug 3807408 refers.


Is it better to use "is" or "==" for number comparison in Python?

That will only work for small numbers and I'm guessing it's also implementation-dependent. Python uses the same object instance for small numbers (iirc <256), but this changes for bigger numbers.

>>> a = 2104214124
>>> b = 2104214124
>>> a == b
>>> a is b

So you should always use == to compare numbers.

Concatenate two JSON objects

You can use Object.assign() method. The Object.assign() method is used to copy the values of all enumerable own properties from one or more source objects to a target object. It will return the target object.[1]

var o1 = { a: 1 }, o2 = { b: 2 }, o3 = { c: 3 };

var obj = Object.assign(o1, o2, o3);
console.log(obj); // { a: 1, b: 2, c: 3 }

What are major differences between C# and Java?

The following is a great in depth reference by Dare Obasanjo on the differences between C# and Java. I always find myself referring to this article when switching between the two.

Node.js EACCES error when listening on most ports

The same issue happened to me. You need to check out your server.js file where you are setting your listening port. Change port number wisely in all places, and it will solve your issue hopefully.

How to get GET (query string) variables in Express.js on Node.js?

you can use url module to collect parameters by using url.parse

var url = require('url');
var url_data = url.parse(request.url, true);
var query = url_data.query;

In expressjs it's done by,

var id =;


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

app.get('/login', function (req, res, next) {
    console.log(; //Give parameter id

Difference between 'struct' and 'typedef struct' in C++?

There is no difference in C++, but I believe in C it would allow you to declare instances of the struct Foo without explicitly doing:

struct Foo bar;

What is the => assignment in C# in a property signature

You can even write this:

    private string foo = "foo";

    private string bar
        get => $"{foo}bar";
            foo = value;

Execute PowerShell Script from C# with Commandline Arguments

I had trouble passing parameters to the Commands.AddScript method.

C:\Foo1.PS1 Hello World Hunger
C:\Foo2.PS1 Hello World

scriptFile = "C:\Foo1.PS1"

parameters = "parm1 parm2 parm3" ... variable length of params

I Resolved this by passing null as the name and the param as value into a collection of CommandParameters

Here is my function:

private static void RunPowershellScript(string scriptFile, string scriptParameters)
    RunspaceConfiguration runspaceConfiguration = RunspaceConfiguration.Create();
    Runspace runspace = RunspaceFactory.CreateRunspace(runspaceConfiguration);
    RunspaceInvoke scriptInvoker = new RunspaceInvoke(runspace);
    Pipeline pipeline = runspace.CreatePipeline();
    Command scriptCommand = new Command(scriptFile);
    Collection<CommandParameter> commandParameters = new Collection<CommandParameter>();
    foreach (string scriptParameter in scriptParameters.Split(' '))
        CommandParameter commandParm = new CommandParameter(null, scriptParameter);
    Collection<PSObject> psObjects;
    psObjects = pipeline.Invoke();

What's "tools:context" in Android layout files?

That attribute is basically the persistence for the "Associated Activity" selection above the layout. At runtime, a layout is always associated with an activity. It can of course be associated with more than one, but at least one. In the tool, we need to know about this mapping (which at runtime happens in the other direction; an activity can call setContentView(layout) to display a layout) in order to drive certain features.

Right now, we're using it for one thing only: Picking the right theme to show for a layout (since the manifest file can register themes to use for an activity, and once we know the activity associated with the layout, we can pick the right theme to show for the layout). In the future, we'll use this to drive additional features - such as rendering the action bar (which is associated with the activity), a place to add onClick handlers, etc.

The reason this is a tools: namespace attribute is that this is only a designtime mapping for use by the tool. The layout itself can be used by multiple activities/fragments etc. We just want to give you a way to pick a designtime binding such that we can for example show the right theme; you can change it at any time, just like you can change our listview and fragment bindings, etc.

(Here's the full changeset which has more details on this)

And yeah, the link Nikolay listed above shows how the new configuration chooser looks and works

One more thing: The "tools" namespace is special. The android packaging tool knows to ignore it, so none of those attributes will be packaged into the APK. We're using it for extra metadata in the layout. It's also where for example the attributes to suppress lint warnings are stored -- as tools:ignore.

What's the difference between .bashrc, .bash_profile, and .environment?

I found information about .bashrc and .bash_profile here to sum it up:

.bash_profile is executed when you login. Stuff you put in there might be your PATH and other important environment variables.

.bashrc is used for non login shells. I'm not sure what that means. I know that RedHat executes it everytime you start another shell (su to this user or simply calling bash again) You might want to put aliases in there but again I am not sure what that means. I simply ignore it myself.

.profile is the equivalent of .bash_profile for the root. I think the name is changed to let other shells (csh, sh, tcsh) use it as well. (you don't need one as a user)

There is also .bash_logout wich executes at, yeah good guess...logout. You might want to stop deamons or even make a little housekeeping . You can also add "clear" there if you want to clear the screen when you log out.

Also there is a complete follow up on each of the configurations files here

These are probably even distro.-dependant, not all distros choose to have each configuraton with them and some have even more. But when they have the same name, they usualy include the same content.

How to compare type of an object in Python?

isinstance works:

if isinstance(obj, MyClass): do_foo(obj)

but, keep in mind: if it looks like a duck, and if it sounds like a duck, it is a duck.

EDIT: For the None type, you can simply do:

if obj is None: obj = MyClass()

Call a PHP function after onClick HTML event

There are two ways. the first is to completely refresh the page using typical form submission



$saveSuccess = null;
$saveMessage = null;

  // if form has been posted process data

  // you dont need the addContact function you jsut need to put it in a new array
  // and it doesnt make sense in this context so jsut do it here
  // then used json_decode and json_decode to read/save your json in
  // saveContact()
  $data = array(
    'fullname' = $_POST['fullname'],
    'email' => $_POST['email'],
    'phone' => $_POST['phone']

  // always return true if you save the contact data ok or false if it fails
  if(($saveSuccess = saveContact($data)) {
     $saveMessage = 'Your submission has been saved!';     
  } else {
     $saveMessage = 'There was a problem saving your submission.';

<!-- your other html -->

<?php if($saveSuccess !== null): ?>
   <p class="flash_message"><?php echo $saveMessage ?></p>
<?php endif; ?>

<form action="your_page.php" method="post">
        <legend>Add New Contact</legend>
        <input type="text" name="fullname" placeholder="First name and last name" required /> <br />
        <input type="email" name="email" placeholder="[email protected]" required /> <br />
        <input type="text" name="phone" placeholder="Personal phone number: mobile, home phone etc." required /> <br />
        <input type="submit" name="submit" class="button" value="Add Contact" onClick="" />
        <input type="button" name="cancel" class="button" value="Reset" />

<!-- the rest of your HTML -->

The second way would be to use AJAX. to do that youll want to completely seprate the form processing into a separate file:

// process.php

$response = array();

  // if form has been posted process data

  // you dont need the addContact function you jsut need to put it in a new array
  // and it doesnt make sense in this context so jsut do it here
  // then used json_decode and json_decode to read/save your json in
  // saveContact()
  $data = array(
    'fullname' => $_POST['fullname'],
    'email' => $_POST['email'],
    'phone' => $_POST['phone']

  // always return true if you save the contact data ok or false if it fails
  $response['status'] = saveContact($data) ? 'success' : 'error';
  $response['message'] = $response['status']
      ? 'Your submission has been saved!'
      : 'There was a problem saving your submission.';

  header('Content-type: application/json');
  echo json_encode($response);

And then in your html/js

<form id="add_contact" action="process.php" method="post">
            <legend>Add New Contact</legend>
            <input type="text" name="fullname" placeholder="First name and last name" required /> <br />
            <input type="email" name="email" placeholder="[email protected]" required /> <br />
            <input type="text" name="phone" placeholder="Personal phone number: mobile, home phone etc." required /> <br />
            <input id="add_contact_submit" type="submit" name="submit" class="button" value="Add Contact" onClick="" />
            <input type="button" name="cancel" class="button" value="Reset" />
    <script type="text/javascript">
            $form = $(this).closest('form');

            // if you need to then wrap this ajax call in conditional logic

              url: $form.attr('action'),
              type: $form.attr('method'),
              dataType: 'json',
              success: function(responseJson) {
              error: function() {
                 $form.before("<p>There was an error processing your request.</p>");

MySQL - how to front pad zip code with "0"?




The first takes 5 bytes per zip code.

The second takes only 3 bytes per zip code. The ZEROFILL option is necessary for zip codes with leading zeros.

Handling optional parameters in javascript

Can you override the function? Will this not work:

function doSomething(id){}
function doSomething(id,parameters){}
function doSomething(id,parameters,callback){}

Force hide address bar in Chrome on Android

Check this has everything you need

The Chrome team has recently implemented a feature that tells the browser to launch the page fullscreen when the user has added it to the home screen. It is similar to the iOS Safari model.

<meta name="mobile-web-app-capable" content="yes">

Http post and get request in angular 6

For reading full response in Angular you should add the observe option:

{ observe: 'response' }
    return this.http.get(`${environment.serverUrl}/api/posts/${postId}/comments/?page=${page}&size=${size}`, { observe: 'response' });

Best way to run scheduled tasks

We use console applications also. If you use logging tools like Log4net you can properly monitor their execution. Also, I'm not sure how they are more difficult to maintain than a web page, given you may be sharing some of the same code libraries between the two if it is designed properly.

If you are against having those tasks run on a timed basis, you could have a web page in your administrative section of your website that acts as a queue. User puts in a request to run the task, it in turn inserts a blank datestamp record on MyProcessQueue table and your scheduled task is checking every X minutes for a new record in MyProcessQueue. That way, it only runs when the customer wants it to run.

Hope those suggestions help.

MATLAB, Filling in the area between two sets of data, lines in one figure

You can accomplish this using the function FILL to create filled polygons under the sections of your plots. You will want to plot the lines and polygons in the order you want them to be stacked on the screen, starting with the bottom-most one. Here's an example with some sample data:

x = 1:100;             %# X range
y1 = rand(1,100)+1.5;  %# One set of data ranging from 1.5 to 2.5
y2 = rand(1,100)+0.5;  %# Another set of data ranging from 0.5 to 1.5
baseLine = 0.2;        %# Baseline value for filling under the curves
index = 30:70;         %# Indices of points to fill under

plot(x,y1,'b');                              %# Plot the first line
hold on;                                     %# Add to the plot
h1 = fill(x(index([1 1:end end])),...        %# Plot the first filled polygon
          [baseLine y1(index) baseLine],...
plot(x,y2,'g');                              %# Plot the second line
h2 = fill(x(index([1 1:end end])),...        %# Plot the second filled polygon
          [baseLine y2(index) baseLine],...
plot(x(index),baseLine.*ones(size(index)),'r');  %# Plot the red line

And here's the resulting figure:

enter image description here

You can also change the stacking order of the objects in the figure after you've plotted them by modifying the order of handles in the 'Children' property of the axes object. For example, this code reverses the stacking order, hiding the green polygon behind the blue polygon:

kids = get(gca,'Children');        %# Get the child object handles
set(gca,'Children',flipud(kids));  %# Set them to the reverse order

Finally, if you don't know exactly what order you want to stack your polygons ahead of time (i.e. either one could be the smaller polygon, which you probably want on top), then you could adjust the 'FaceAlpha' property so that one or both polygons will appear partially transparent and show the other beneath it. For example, the following will make the green polygon partially transparent:


Reading a string with spaces with sscanf

Since you want the trailing string from the input, you can use %n (number of characters consumed thus far) to get the position at which the trailing string starts. This avoids memory copies and buffer sizing issues, but comes at the cost that you may need to do them explicitly if you wanted a copy.

const char *input = "19  cool kid";
int age;
int nameStart = 0;
sscanf(input, "%d %n", &age, &nameStart);
printf("%s is %d years old\n", input + nameStart, age);


cool kid is 19 years old

Add class to an element in Angular 4

Use [ngClass] and conditionally apply class based on the id.

In your HTML file:

    <img [ngClass]="{'this-is-a-class': id === 1 }" id="1"  
         src="../../assets/images/1.jpg" (click)="addClass(id=1)"/>
    <img [ngClass]="{'this-is-a-class': id === 2 }" id="2"  
         src="../../assets/images/2.png" (click)="addClass(id=2)"/>

In your TypeScript file:

addClass(id: any) { = id;

Differences between key, superkey, minimal superkey, candidate key and primary key

Super Key : Super key is a set of one or more attributes whose values identify tuple in the relation uniquely.

Candidate Key : Candidate key can be defined as a minimal subset of super key. In some cases , candidate key can not alone since there is alone one attribute is the minimal subset. Example,

Employee(id, ssn, name, addrress)

Here Candidate key is (id, ssn) because we can easily identify the tuple using either id or ssn . Althrough, minimal subset of super key is either id or ssn. but both of them can be considered as candidate key.

Primary Key : Primary key is a one of the candidate key.

Example : Student(Id, Name, Dept, Result)


Super Key : {Id, Id+Name, Id+Name+Dept} because super key is set of attributes .

Candidate Key : Id because Id alone is the minimal subset of super key.

Primary Key : Id because Id is one of the candidate key

Why isn't sizeof for a struct equal to the sum of sizeof of each member?

Among the other well-explained answers about memory alignment and structure padding/packing, there is something which I have discovered in the question itself by reading it carefully.

"Why isn't sizeof for a struct equal to the sum of sizeof of each member?"

"Why does the sizeof operator return a size larger for a structure than the total sizes of the structure's members"?

Both questions suggest something what is plain wrong. At least in a generic, non-example focused view, which is the case here.

The result of the sizeof operand applied to a structure object can be equal to the sum of sizeof applied to each member separately. It doesn't have to be larger/different.

If there is no reason for padding, no memory will be padded.

One most implementations, if the structure contains only members of the same type:

struct foo {
   int a;   
   int b;
   int c;     
} bar;

Assuming sizeof(int) == 4, the size of the structure bar will be equal to the sum of the sizes of all members together, sizeof(bar) == 12. No padding done here.

Same goes for example here:

struct foo {
   short int a;   
   short int b;
   int c;     
} bar;

Assuming sizeof(short int) == 2 and sizeof(int) == 4. The sum of allocated bytes for a and b is equal to the allocated bytes for c, the largest member and with that everything is perfectly aligned. Thus, sizeof(bar) == 8.

This is also object of the second most popular question regarding structure padding, here:

How to build query string with Javascript

Is is probably too late to answer your question.
I had the same question and I didn't like to keep appending strings to create a URL. So, I started using $.param as techhouse explained.
I also found a URI.js library that creates the URLs easily for you. There are several examples that will help you: URI.js Documentation.
Here is one of them:

var uri = new URI("?hello=world");
uri.setSearch("hello", "mars"); // returns the URI instance for chaining
// uri == "?hello=mars"

uri.setSearch({ foo: "bar", goodbye : ["world", "mars"] });
// uri == "?hello=mars&foo=bar&goodbye=world&goodbye=mars"

uri.setSearch("goodbye", "sun");
// uri == "?hello=mars&foo=bar&goodbye=sun"

// CAUTION: beware of arrays, the following are not quite the same
// If you're dealing with PHP, you probably want the latter…
uri.setSearch("foo", ["bar", "baz"]);
uri.setSearch("foo[]", ["bar", "baz"]);`

Combine two columns and add into one new column

Generally, I agree with @kgrittn's advice. Go for it.

But to address your basic question about concat(): The new function concat() is useful if you need to deal with null values - and null has neither been ruled out in your question nor in the one you refer to.

If you can rule out null values, the good old (SQL standard) concatenation operator || is still the best choice, and @luis' answer is just fine:

SELECT col_a || col_b;

If either of your columns can be null, the result would be null in that case. You could defend with COALESCE:

SELECT COALESCE(col_a, '') || COALESCE(col_b, '');

But that get tedious quickly with more arguments. That's where concat() comes in, which never returns null, not even if all arguments are null. Per documentation:

NULL arguments are ignored.

SELECT concat(col_a, col_b);

The remaining corner case for both alternatives is where all input columns are null in which case we still get an empty string '', but one might want null instead (at least I would). One possible way:

          WHEN col_a IS NULL THEN col_b
          WHEN col_b IS NULL THEN col_a
          ELSE col_a || col_b

This gets more complex with more columns quickly. Again, use concat() but add a check for the special condition:

            ELSE concat(col_a, col_b) END;

How does this work?
(col_a, col_b) is shorthand notation for a row type expression ROW (col_a, col_b). And a row type is only null if all columns are null. Detailed explanation:

Also, use concat_ws() to add separators between elements (ws for "with separator").

An expression like the one in Kevin's answer:

SELECT $1.zipcode || ' - ' || $ || ', ' || $1.state;

is tedious to prepare for null values in PostgreSQL 8.3 (without concat()). One way (of many):

            WHEN $1.zipcode IS NULL THEN $
            WHEN $    IS NULL THEN $1.zipcode
            ELSE $1.zipcode || ' - ' || $
         END, '')
       || COALESCE(', ' || $1.state, '');

Function volatility is only STABLE

concat() and concat_ws() are STABLE functions, not IMMUTABLE because they can invoke datatype output functions (like timestamptz_out) that depend on locale settings.
Explanation by Tom Lane.

This prohibits their direct use in index expressions. If you know that the result is actually immutable in your case, you can work around this with an IMMUTABLE function wrapper. Example here:

Copying one structure to another

Since C90, you can simply use:

dest_struct = source_struct;

as long as the string is memorized inside an array:

struct xxx {
    char theString[100];

Otherwise, if it's a pointer, you'll need to copy it by hand.

struct xxx {
    char* theString;

dest_struct = source_struct;
dest_struct.theString = malloc(strlen(source_struct.theString) + 1);
strcpy(dest_struct.theString, source_struct.theString);

How can I get date in application run by node.js?

To create a new Date object in node.js, or JavaScript in general, just call it’s initializer

var d = new Date();

var d = new Date(dateString);

var d = new Date(jsonDate);

var d = new Date(year, month, day);

var d = new Date(year, month, day, hour, minute, second, millisecond);

Remember that Date objects can only be instantiated by calling Date or using it as a constructor; unlike other JavaScript object types, Date objects have no literal syntax

Check if character is number?

Just use isFinite

const number = "1";
if (isFinite(number)) {
    // do something

Is there a pure CSS way to make an input transparent?

The two methods previously described are not enough today. I personnally use :

    background-color: transparent;
    border: 0px;
    outline: none;
    -webkit-box-shadow: none;
    -moz-box-shadow: none;
    box-shadow: none;

It also removes the shadow set on some browsers, hide the text that could be input and make the cursor behave as if the input was not there.

You may want to set width to 0px also.

How does collections.defaultdict work?

Dictionaries are a convenient way to store data for later retrieval by name (key). Keys must be unique, immutable objects, and are typically strings. The values in a dictionary can be anything. For many applications, the values are simple types such as integers and strings.

It gets more interesting when the values in a dictionary are collections (lists, dicts, etc.) In this case, the value (an empty list or dict) must be initialized the first time a given key is used. While this is relatively easy to do manually, the defaultdict type automates and simplifies these kinds of operations. A defaultdict works exactly like a normal dict, but it is initialized with a function (“default factory”) that takes no arguments and provides the default value for a nonexistent key.

A defaultdict will never raise a KeyError. Any key that does not exist gets the value returned by the default factory.

from collections import defaultdict
ice_cream = defaultdict(lambda: 'Vanilla')

ice_cream['Sarah'] = 'Chunky Monkey'
ice_cream['Abdul'] = 'Butter Pecan'

>>>Chunky Monkey


Here is another example on How using defaultdict, we can reduce complexity

from collections import defaultdict
# Time complexity O(n^2)
def delete_nth_naive(array, n):
    ans = []
    for num in array:
        if ans.count(num) < n:
    return ans

# Time Complexity O(n), using hash tables.
def delete_nth(array,n):
    result = []
    counts = defaultdict(int)

    for i in array:
        if counts[i] < n:
            counts[i] += 1
    return result

x = [1,2,3,1,2,1,2,3]
print(delete_nth(x, n=2))
print(delete_nth_naive(x, n=2))

In conclusion, whenever you need a dictionary, and each element’s value should start with a default value, use a defaultdict.

Using media breakpoints in Bootstrap 4-alpha

Bootstrap has a way of using media queries to define the different task for different sites. It uses four breakpoints.

we have extra small screen sizes which are less than 576 pixels that small in which I mean it's size from 576 to 768 pixels.

medium screen sizes take up screen size from 768 pixels up to 992 pixels large screen size from 992 pixels up to 1200 pixels.

E.g Small Text

This means that at the small screen between 576px and 768px, center the text For medium screen, change "sm" to "md" and same goes to large "lg"

How can get the text of a div tag using only javascript (no jQuery)

Because textContent is not supported in IE8 and older, here is a workaround:

var node = document.getElementById('test'),
var text  = node.textContent || node.innerText;

innerText does work in IE.

Get current date in DD-Mon-YYY format in JavaScript/Jquery

the DD-MM-YYYY is just one of the formats. The format of the jquery plugin, is based on this list:

Tested following code in chrome console:

test = new Date()

Troubleshooting "Warning: session_start(): Cannot send session cache limiter - headers already sent"

I had the same issue, but my solution wasn't as obvious as the suggested ones. It turned out that my php-file was written in UTF-8, which caused issues. I copy/pasted the content of the entire file into a new php-file (Notepad++ tells me this is written in ANSI rather than UTF-8), and now it work flawlessly.

reactjs - how to set inline style of backgroundcolor?

You don't need the quotes.

<a style={{backgroundColor: bgColors.Yellow}}>yellow</a>

Pandas sort by group aggregate and column

Groupby A:

In [0]: grp = df.groupby('A')

Within each group, sum over B and broadcast the values using transform. Then sort by B:

In [1]: grp[['B']].transform(sum).sort('B')
2 -2.829710
5 -2.829710
1  0.253651
4  0.253651
0  0.551377
3  0.551377

Index the original df by passing the index from above. This will re-order the A values by the aggregate sum of the B values:

In [2]: sort1 = df.ix[grp[['B']].transform(sum).sort('B').index]

In [3]: sort1
     A         B      C
2  baz -0.528172  False
5  baz -2.301539   True
1  bar -0.611756   True
4  bar  0.865408  False
0  foo  1.624345  False
3  foo -1.072969   True

Finally, sort the 'C' values within groups of 'A' using the sort=False option to preserve the A sort order from step 1:

In [4]: f = lambda x: x.sort('C', ascending=False)

In [5]: sort2 = sort1.groupby('A', sort=False).apply(f)

In [6]: sort2
         A         B      C
baz 5  baz -2.301539   True
    2  baz -0.528172  False
bar 1  bar -0.611756   True
    4  bar  0.865408  False
foo 3  foo -1.072969   True
    0  foo  1.624345  False

Clean up the df index by using reset_index with drop=True:

In [7]: sort2.reset_index(0, drop=True)
     A         B      C
5  baz -2.301539   True
2  baz -0.528172  False
1  bar -0.611756   True
4  bar  0.865408  False
3  foo -1.072969   True
0  foo  1.624345  False

Add button to a layout programmatically

If you just have included a layout file at the beginning of onCreate() inside setContentView and want to get this layout to add new elements programmatically try this:

ViewGroup linearLayout = (ViewGroup) findViewById(;

then you can create a new Button for example and just add it:

Button bt = new Button(this);
bt.setText("A Button");
bt.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, 

UIView Infinite 360 degree rotation animation?

I has developed a shiny animation framework which can save you tone of time! Using it this animation can be created very easily:

private var endlessRotater: EndlessAnimator!
override func viewDidAppear(animated: Bool) 
    let rotationAnimation = AdditiveRotateAnimator(M_PI).to(targetView).duration(2.0).baseAnimation(.CurveLinear)
    endlessRotater = EndlessAnimator(rotationAnimation)

to stop this animation simply set nil to endlessRotater.

If you are interested, please take a look:

std::wstring VS std::string

  1. When you want to store 'wide' (Unicode) characters.
  2. Yes: 255 of them (excluding 0).
  3. Yes.
  4. Here's an introductory article:

Case insensitive regular expression without re.compile?

Pass re.IGNORECASE to the flags param of search, match, or sub:'test', 'TeSt', re.IGNORECASE)
re.match('test', 'TeSt', re.IGNORECASE)
re.sub('test', 'xxxx', 'Testing', flags=re.IGNORECASE)

Python - List of unique dictionaries

Well all the answers mentioned here are good, but in some answers one can face error if the dictionary items have nested list or dictionary, so I propose simple answer

a = [str(i) for i in a]
a = list(set(a))
a = [eval(i) for i in a]

regex to match a single character that is anything but a space

  • \s matches any white-space character
  • \S matches any non-white-space character
  • You can match a space character with just the space character;
  • [^ ] matches anything but a space character.

Pick whichever is most appropriate.

Python re.sub replace with matched content

Use \1 instead of $1.

\number Matches the contents of the group of the same number.

Convert boolean result into number/integer

I just came across this shortcut today.



People much smarter than I can explain:

Differences in boolean operators: & vs && and | vs ||

& and | are bitwise operators on integral types (e.g. int):

&& and || operate on booleans only (and short-circuit, as other answers have already said).

Object creation on the stack/heap?

In both your examples, local variables of Object* type are allocated on the stack. The compiler is free to produce the same code from both snippets if there is no way for your program to detect a difference.

The memory area for global variables is the same as the memory area for static variables - it's neither on the stack nor on the heap. You can place variables in that area by declaring them static inside the function. The consequence of doing so is that the instance becomes shared among concurrent invocations of your function, so you need to carefully consider synchronization when you use statics.

Here is a link to a discussion of the memory layout of a running C program.

How do I get a python program to do nothing?

The pass command is what you are looking for. Use pass for any construct that you want to "ignore". Your example uses a conditional expression but you can do the same for almost anything.

For your specific use case, perhaps you'd want to test the opposite condition and only perform an action if the condition is false:

if num2 != num5:

This will be the same as this:

if num2 == num5:

That way you won't even have to use pass and you'll also be closer to adhering to the "Flatter is better than nested" convention in PEP20.

You can read more about the pass statement in the documentation:

The pass statement does nothing. It can be used when a statement is required syntactically but the program requires no action.

if condition:
except Exception:
    pass # do nothing
class Foo():
    pass # an empty class definition
def bar():
    pass # an empty function definition

WebAPI Multiple Put/Post parameters

We passed Json object by HttpPost method, and parse it in dynamic object. it works fine. this is sample code:


public string DoJson2(dynamic data)
   var c = JsonConvert.DeserializeObject<YourObjectTypeHere>(data.ToString()); 

   var c1 = JsonConvert.DeserializeObject< ComplexObject1 >(data.c1.ToString());

   var c2 = JsonConvert.DeserializeObject< ComplexObject2 >(data.c2.ToString());

   string appName = data.AppName;
   int appInstanceID = data.AppInstanceID;
   string processGUID = data.ProcessGUID;
   int userID = data.UserID;
   string userName = data.UserName;
   var performer = JsonConvert.DeserializeObject< NextActivityPerformers >(data.NextActivityPerformers.ToString());


The complex object type could be object, array and dictionary.

Content-Type: application/json,
data: {"AppName":"SamplePrice",

Is there any way to specify a suggested filename when using data: URI?

According to RFC 2397, no, there isn't.

Nor does there appear to be any attribute of the <a> element that you can use either.

However HTML5 has subsequently introduced the download attribute on the <a> element, although at the time of writing support is not universal (no MSIE support, for example)

How to put an image next to each other

You don't need the div's.


<div class="nav3" style="height:705px;">
    <a href="" class="icons"><img src="images/facebook.png"></a>
    <a href="" class="icons"><img src="images/twitter.png"></a>


.nav3 {
    background-color: #E9E8C7;
    height: auto;
    width: 150px;
    float: left;
    padding-left: 20px;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 12px;
    color: #333333;
    padding-top: 20px;
    padding-right: 20px;

    width: 64px; 
    height: 64px; 

 a.icons:hover {
     background: #C93;

See this fiddle

How to remove CocoaPods from a project?

I was able to remove my pods in the project using the CocoaPods app (Version 1.5.2). Afterwards I only deleted the podfile, podfile.lock and xcworkspace files in the folder.

Centering elements in jQuery Mobile

jQuery Mobile doesn't seem to have a css class to center elements (I searched through its css).

But you can write your own additional css.

Try creating your own:

  margin: 0 auto;

example HTML:

<div data-role="button" class="center-button">button text</div>

and see what happens. You might need to set text-align to center in the wrapping tag, so this might work better:

  text-align: center;
.center-wrapper * {
  margin: 0 auto;

example HTML:

<div class="center-wrapper">
  <div data-role="button">button text</div>

How to show image using ImageView in Android

Drag image from your hard drive to Drawable folder in your project and in code use it like this:

ImageView image;

image = (ImageView) findViewById(;

Get current value selected in dropdown using jQuery

In case you want the index of the current selected value.

$selIndex = $("select#myselectid").prop('selectedIndex'));

"Rate This App"-link in Google Play store app on the phone

This is if you publish your app in both Google Play Store and Amazon Appstore. I also handle the case that users (especially in China) don't have both app store and browser.

public void goToMyApp(boolean googlePlay) {//true if Google Play, false if Amazone Store
    try {
       startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse((googlePlay ? "market://details?id=" : "amzn://apps/android?p=") +getPackageName())));
    } catch (ActivityNotFoundException e1) {
        try {
            startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse((googlePlay ? "" : "") +getPackageName())));
        } catch (ActivityNotFoundException e2) {
            Toast.makeText(this, "You don't have any app that can open this link", Toast.LENGTH_SHORT).show();

Remove all the elements that occur in one list from another

Alternate Solution :

reduce(lambda x,y : filter(lambda z: z!=y,x) ,[2,3,5,8],[1,2,6,8])

How to split a string in Java

I used a string called stringValue and is in the form of something like this "Those who had coins, enjoyed in the rain, those who had notes were busy looking for the shelter".

I will split up the stringValue using the "," as the colon.

And then I would simply like to SetText() of three different TextViews to display that string.

String stringValue = "Those who had coins, enjoyed in the rain, those who had notes were busy looking for the shelter";
String ValueSplitByColon[] = stringValue.split(",");

String firstValue = ValueSplitByColon[0];
String secondValue = ValueSplitByColon[1];
String thirdValue = ValueSplitByColon[2];


It gives the output as:

  1. The txtV1 value is: Those who had coins

  2. The txtV2 value is: enjoyed in the rain

  3. The txtV3 value is: those who had notes were busy looking for the shelter

application/x-www-form-urlencoded or multipart/form-data?

If you need to use Content-Type=x-www-urlencoded-form then DO NOT use FormDataCollection as parameter: In Core 2+ FormDataCollection has no default constructors which is required by Formatters. Use IFormCollection instead:

 public IActionResult Search([FromForm]IFormCollection type)
        return Ok();

Unknown version of Tomcat was specified in Eclipse

You are specifying tomcat source directory.

You need to specify tomcat binary installation root directory, also known as CATALINA_HOME.

Usually, this is where you untar apache-tomcat-7.0.42.tar.gz file.

Find ALL tweets from a user (not just the first 3,200)

I can confirm that the maximum can be slightly over 3200. I'm getting up to 3231 right now.

FIX CSS <!--[if lt IE 8]> in IE

Use <!-- [if lt IE 9] > exact this code for IE9.The spaces are very Important.

Font scaling based on width of container

For dynamic text, this plugin is quite useful:

Simply add CSS:

.slabtexted .slabtext
    display: -moz-inline-box;
    display: inline-block;
    white-space: nowrap;
.slabtextinactive .slabtext
    display: inline;
    white-space: normal;
    font-size: 1em !important;
    letter-spacing: inherit !important;
    word-spacing: inherit !important;
    *letter-spacing: normal !important;
    *word-spacing: normal !important;
.slabtextdone .slabtext
    display: block;

And the script:


Set up Python 3 build system with Sublime Text 3

Run Python Files in Sublime Text3

For Sublime Text 3, First Install Package Control:

  • Press Ctrl + Shift + P, a search bar will open
  • Type Install package and then press enter Click here to see Install Package Search Pic

  • After the package got installed. It may prompt to restart SublimeText

  • After completing the above step
  • Just again repeat the 1st and 2nd step, it will open the repositories this time
  • Search for Python 3 and Hit enter.
  • There you go.
  • Just press Ctrl + B in your python file and you'll get the output. Click here to see Python 3 repo pic

It perfectly worked for me. Hopefully, it helped you too. For any left requirements, visit here.

Swift - iOS - Dates and times in different format

If you want to use protocol oriented programming (Swift 3)

1) Create a Dateable protocol

protocol Dateable {
    func userFriendlyFullDate() -> String
    func userFriendlyHours() -> String

2) Extend Date class and implement the Dateable protocol

extension Date: Dateable {
    var  formatter: DateFormatter { return DateFormatter() }

    /** Return a user friendly hour */
    func userFriendlyFullDate() -> String {
        // Customize a date formatter
        formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"
        formatter.timeZone = TimeZone(abbreviation: "UTC")

        return formatter.string(from: self)

    /** Return a user friendly hour */
    func userFriendlyHours() -> String {
        // Customize a date formatter
        formatter.dateFormat = "HH:mm"
        formatter.timeZone = TimeZone(abbreviation: "UTC")

        return formatter.string(from: self)
    // You can add many cases you need like string to date formatter


3) Use it

let currentDate: Date = Date()
let stringDate: String = currentDate.userFriendlyHours()
// Print 15:16

Is there a way to detect if a browser window is not currently active?

u can use :

(function () {

    var requiredResolution = 10; // ms
    var checkInterval = 1000; // ms
    var tolerance = 20; // percent

    var counter = 0;
    var expected = checkInterval / requiredResolution;
    //console.log('expected:', expected);

    window.setInterval(function () {
    }, requiredResolution);

    window.setInterval(function () {
        var deviation = 100 * Math.abs(1 - counter / expected);
        // console.log('is:', counter, '(off by', deviation , '%)');
        if (deviation > tolerance) {
            console.warn('Timer resolution not sufficient!');
        counter = 0;
    }, checkInterval);


Notice: Trying to get property of non-object error

@Balamanigandan your Original Post :- PHP Notice: Trying to get property of non-object error

Your are trying to access the Null Object. From AngularJS your are not passing any Objects instead you are passing the $_GET element. Try by using $_GET['uid'] instead of $objData->token

Passing variable from Form to Module in VBA

Siddharth's answer is nice, but relies on globally-scoped variables. There's a better, more OOP-friendly way.

A UserForm is a class module like any other - the only difference is that it has a hidden VB_PredeclaredId attribute set to True, which makes VB create a global-scope object variable named after the class - that's how you can write UserForm1.Show without creating a new instance of the class.

Step away from this, and treat your form as an object instead - expose Property Get members and abstract away the form's controls - the calling code doesn't care about controls anyway:

Option Explicit
Private cancelling As Boolean

Public Property Get UserId() As String
    UserId = txtUserId.Text
End Property

Public Property Get Password() As String
    Password = txtPassword.Text
End Property

Public Property Get IsCancelled() As Boolean
    IsCancelled = cancelling
End Property

Private Sub OkButton_Click()
End Sub

Private Sub CancelButton_Click()
    cancelling = True
End Sub

Private Sub UserForm_QueryClose(Cancel As Integer, CloseMode As Integer)
    If CloseMode = VbQueryClose.vbFormControlMenu Then
        cancelling = True
        Cancel = True
    End If
End Sub

Now the calling code can do this (assuming the UserForm was named LoginPrompt):

With New LoginPrompt
    .Show vbModal
    If .IsCancelled Then Exit Sub
    DoSomething .UserId, .Password
End With

Where DoSomething would be some procedure that requires the two string parameters:

Private Sub DoSomething(ByVal uid As String, ByVal pwd As String)
    'work with the parameter values, regardless of where they came from
End Sub

Add/remove HTML inside div using JavaScript

make a class for that button lets say :

`<input type="button" value="+" class="b1" onclick="addRow()">`

your js should look like this :

      $('div').append('<input type="text"..etc ');

Creating a class object in c++

Example example;

Here example is an object on the stack.

Example* example=new Example();

This could be broken into:

Example* example;
example=new Example();

Here the first statement creates a variable example which is a "pointer to Example". When the constructor is called, memory is allocated for it on the heap (dynamic allocation). It is the programmer's responsibility to free this memory when it is no longer needed. (C++ does not have garbage collection like java).

Getting and removing the first character of a string

There is also str_sub from the stringr package

x <- 'hello stackoverflow'
str_sub(x, 2) # or
str_sub(x, 2, str_length(x))
[1] "ello stackoverflow"

Store mysql query output into a shell variable

To read the data line-by-line into a Bash array you can do this:

while read -a row
    echo "..${row[0]}..${row[1]}..${row[2]}.."
done < <(echo "SELECT A, B, C FROM table_a" | mysql database -u $user -p $password)

Or into individual variables:

while read a b c
    echo "..${a}..${b}..${c}.."
done < <(echo "SELECT A, B, C FROM table_a" | mysql database -u $user -p $password)

JsonMappingException: No suitable constructor found for type [simple type, class ]: can not instantiate from JSON object

For me, this used to work, but upgrading libraries caused this issue to appear. Problem was having a class like this:

package example.counter;

import javax.validation.constraints.NotNull;

import lombok.Data;

public class CounterRequest {
    private final Integer int1;

    private final Integer int2;

Using lombok:


Falling back to


Fixed the issue. Not sure why, but wanted to document it for future.

How to empty a file using Python

Opening a file creates it and (unless append ('a') is set) overwrites it with emptyness, such as this:

open(filename, 'w').close()

insert datetime value in sql database with c#

This is an older question with a proper answer (please use parameterized queries) which I'd like to extend with some timezone discussion. For my current project I was interested in how do the datetime columns handle timezones and this question is the one I found.

Turns out, they do not, at all.

datetime column stores the given DateTime as is, without any conversion. It does not matter if the given datetime is UTC or local.

You can see for yourself:

using (var connection = new SqlConnection(connectionString))
    using (var command = connection.CreateCommand())
        command.CommandText = "SELECT * FROM (VALUES (@a, @b, @c)) example(a, b, c);";

        var local = DateTime.Now;
        var utc = local.ToUniversalTime();

        command.Parameters.AddWithValue("@a", utc);
        command.Parameters.AddWithValue("@b", local);
        command.Parameters.AddWithValue("@c", utc.ToLocalTime());

        using (var reader = command.ExecuteReader())

            var localRendered = local.ToString("o");

            Console.WriteLine($"a = {utc.ToString("o").PadRight(localRendered.Length, ' ')} read = {reader.GetDateTime(0):o}, {reader.GetDateTime(0).Kind}");
            Console.WriteLine($"b = {local:o} read = {reader.GetDateTime(1):o}, {reader.GetDateTime(1).Kind}");
            Console.WriteLine($"{"".PadRight(localRendered.Length + 4, ' ')} read = {reader.GetDateTime(2):o}, {reader.GetDateTime(2).Kind}");

What this will print will of course depend on your time zone but most importantly the read values will all have Kind = Unspecified. The first and second output line will be different by your timezone offset. Second and third will be the same. Using the "o" format string (roundtrip) will not show any timezone specifiers for the read values.

Example output from GMT+02:00:

a = 2018-11-20T10:17:56.8710881Z      read = 2018-11-20T10:17:56.8700000, Unspecified
b = 2018-11-20T12:17:56.8710881+02:00 read = 2018-11-20T12:17:56.8700000, Unspecified
                                      read = 2018-11-20T12:17:56.8700000, Unspecified

Also note of how the data gets truncated (or rounded) to what seems like 10ms.

How do I configure the proxy settings so that Eclipse can download new plugins?

finally work for me !

In Eclipse, Window > Preferences > General > Network Connections,
set Active Provider to Native
add to eclipse.ini :

How do I use variables in Oracle SQL Developer?

In sql developer define properties by default "ON". If it is "OFF" any case, use below steps.

set define on; define batchNo='123'; update TABLE_NAME SET IND1 = 'Y', IND2 = 'Y' WHERE BATCH_NO = '&batchNo';

Switch statement for string matching in JavaScript

var token = 'spo';

    case ( (token.match(/spo/) )? token : undefined ) :
       console.log('NO MATCH')

--> If the match is made the ternary expression returns the original token
----> The original token is evaluated by case

--> If the match is not made the ternary returns undefined
----> Case evaluates the token against undefined which hopefully your token is not.

The ternary test can be anything for instance in your case

( !!~ base_url_string.indexOf('') )? : undefined 


(token.match(/spo/) )? token : undefined ) 

is a ternary expression.

The test in this case is token.match(/spo/) which states the match the string held in token against the regex expression /spo/ ( which is the literal string spo in this case ).

If the expression and the string match it results in true and returns token ( which is the string the switch statement is operating on ).

Obviously token === token so the switch statement is matched and the case evaluated

It is easier to understand if you look at it in layers and understand that the turnery test is evaluated "BEFORE" the switch statement so that the switch statement only sees the results of the test.

Hide text using css

Jeffrey Zeldman suggests the following solution:

.hide-text {
  text-indent: 100%;
  white-space: nowrap;
  overflow: hidden;

It should be less resource intensive than -9999px;

Please read all about it here:

Find size of Git repository

If you use git LFS, git count-objects does not count your binaries, but only the pointers to them.

If your LFS files are managed by Artifactorys, you should use the REST API:

  • Get the API from any search engine
  • Look at Get Storage Summary Info

How to return a specific element of an array?

I want to return odd numbers of an array

If i read that correctly, you want something like this?

List<Integer> getOddNumbers(int[] integers) {
  List<Integer> oddNumbers = new ArrayList<Integer>();
  for (int i : integers)
    if (i % 2 != 0)
  return oddNumbers;

Get top most UIViewController

  var topViewController: UIViewController? {
        guard var topViewController = UIApplication.shared.keyWindow?.rootViewController else { return nil }
        while let presentedViewController = topViewController.presentedViewController {
            topViewController = presentedViewController
        return topViewController

Copying files to a container with Docker Compose


      - /dir/on/host:/var/www/html

if /dir/on/host doesn't exist, it is created on the host and the empty content is mounted in the container at /var/www/html. Whatever content you had before in /var/www/html inside the container is inaccessible, until you unmount the volume; the new mount is hiding the old content.

How to find EOF through fscanf?

fscanf - "On success, the function returns the number of items successfully read. This count can match the expected number of readings or be less -even zero- in the case of a matching failure. In the case of an input failure before any data could be successfully read, EOF is returned."

So, instead of doing nothing with the return value like you are right now, you can check to see if it is == EOF.

You should check for EOF when you call fscanf, not check the array slot for EOF.

adding child nodes in treeview

I needed to do something similar and came across the same issues. I used the AfterSelect event to make sure I wasn't getting the previously selected node.

It's actually really easy to reference the correct node to receive the new child node.

private void TreeView1_AfterSelect(object sender, System.Windows.Forms.TreeViewEventArgs e)
   //show dialogbox to let user name the new node
   frmDialogInput f = new frmDialogInput();

    //find the node that was selected
    TreeNode myNode = TreeView1.SelectedNode;
    //create the new node to add
    TreeNode newNode = new TreeNode(f.EnteredText);
    //add the new child to the selected node

Copy data from one existing row to another existing row in SQL?

Try this:

UPDATE barang
SET ID FROM(SELECT tblkatalog.tblkatalog_id FROM tblkatalog 
WHERE tblkatalog.tblkatalog_nomor = barang.NO_CAT) WHERE barang.NO_CAT <>'';

The RPC server is unavailable. (Exception from HRESULT: 0x800706BA)

I had the same problem when trying to run a PowerShell script that only looked at a remote server to read the size of a hard disk.

I turned off the Firewall (Domain networks, Private networks, and Guest or public network) on the remote server and the script worked.

I then turned the Firewall for Domain networks back on, and it worked.

I then turned the Firewall for Private network back on, and it also worked.

I then turned the Firewall for Guest or public networks, and it also worked.

Read Content from Files which are inside Zip file

Because of the condition in while, the loop might never break:

while (entry != null) {
  // If entry never becomes null here, loop will never break.

Instead of the null check there, you can try this:

ZipEntry entry = null;
while ((entry = zip.getNextEntry()) != null) {
  // Rest of your code

how to fix java.lang.IndexOutOfBoundsException

You are trying to access the first element lstpp.get(0) of an empty array. Just add an element to your array and check for !lstpp.isEmpty() before accessing an element

react native get TextInput value

Simply do it.


textChangeHandler = async (key, val) => {
    await this.setState({ [key]: val });

<Textfield onChangeText={val => this.textChangeHandler('f_name', val)}>

Break or return from Java 8 stream forEach?

Either you need to use a method which uses a predicate indicating whether to keep going (so it has the break instead) or you need to throw an exception - which is a very ugly approach, of course.

So you could write a forEachConditional method like this:

public static <T> void forEachConditional(Iterable<T> source,
                                          Predicate<T> action) {
    for (T item : source) {
        if (!action.test(item)) {

Rather than Predicate<T>, you might want to define your own functional interface with the same general method (something taking a T and returning a bool) but with names that indicate the expectation more clearly - Predicate<T> isn't ideal here.

java howto ArrayList push, pop, shift, and unshift

Underscore-java library contains methods push(values), pop(), shift() and unshift(values).

Code example:

import com.github.underscore.U:

List<String> strings = Arrays.asList("one", "two", " three");
List<String> newStrings = U.push(strings, "four", "five");
// ["one", " two", "three", " four", "five"]
String newPopString = U.pop(strings).fst();
// " three"
String newShiftString = U.shift(strings).fst();
// "one"
List<String> newUnshiftStrings = U.unshift(strings, "four", "five");
// ["four", " five", "one", " two", "three"]

Google Spreadsheet, Count IF contains a string

It will likely have been solved by now, but I ran accross this and figured to give my input


The important thing is that separating parameters in google docs is using a ; and not a ,

How can I send JSON response in symfony2 controller

Since Symfony 3.1 you can use JSON Helper

public function indexAction()
// returns '{"username":"jane.doe"}' and sets the proper Content-Type header
return $this->json(array('username' => 'jane.doe'));

// the shortcut defines three optional arguments
// return $this->json($data, $status = 200, $headers = array(), $context = array());

css with background image without repeating the image

Instead of

background-repeat-x: no-repeat;
background-repeat-y: no-repeat;

which is not correct, use

background-repeat: no-repeat;

Plot Normal distribution with Matplotlib

Note: This solution is using pylab, not matplotlib.pyplot

You may try using hist to put your data info along with the fitted curve as below:

import numpy as np
import scipy.stats as stats
import pylab as pl

h = sorted([186, 176, 158, 180, 186, 168, 168, 164, 178, 170, 189, 195, 172,
     187, 180, 186, 185, 168, 179, 178, 183, 179, 170, 175, 186, 159,
     161, 178, 175, 185, 175, 162, 173, 172, 177, 175, 172, 177, 180])  #sorted

fit = stats.norm.pdf(h, np.mean(h), np.std(h))  #this is a fitting indeed


pl.hist(h,normed=True)      #use this to draw histogram of your data                   #use may also need add this 

enter image description here

How can I convert spaces to tabs in Vim or Linux?

Changes all spaces to tab :%s/\s/\t/g

How to use comparison operators like >, =, < on BigDecimal

Here is an example for all six boolean comparison operators (<, ==, >, >=, !=, <=):

BigDecimal big10 = new BigDecimal(10);
BigDecimal big20 = new BigDecimal(20);

System.out.println(big10.compareTo(big20) < -1);  // false
System.out.println(big10.compareTo(big20) <= -1); // true
System.out.println(big10.compareTo(big20) == -1); // true
System.out.println(big10.compareTo(big20) >= -1); // true
System.out.println(big10.compareTo(big20) > -1);  // false
System.out.println(big10.compareTo(big20) != -1); // false

System.out.println(big10.compareTo(big20) < 0);   // true
System.out.println(big10.compareTo(big20) <= 0);  // true
System.out.println(big10.compareTo(big20) == 0);  // false
System.out.println(big10.compareTo(big20) >= 0);  // false
System.out.println(big10.compareTo(big20) > 0);   // false
System.out.println(big10.compareTo(big20) != 0);  // true

System.out.println(big10.compareTo(big20) < 1);   // true
System.out.println(big10.compareTo(big20) <= 1);  // true
System.out.println(big10.compareTo(big20) == 1);  // false
System.out.println(big10.compareTo(big20) >= 1);  // false
System.out.println(big10.compareTo(big20) > 1);   // false
System.out.println(big10.compareTo(big20) != 1);  // true

Android ListView Selector Color

The list selector drawable is a StateListDrawable — it contains reference to multiple drawables for each state the list can be, like selected, focused, pressed, disabled...

While you can retrieve the drawable using getSelector(), I don't believe you can retrieve a specific Drawable from a StateListDrawable, nor does it seem possible to programmatically retrieve the colour directly from a ColorDrawable anyway.

As for setting the colour, you need a StateListDrawable as described above. You can set this on your list using the android:listSelector attribute, defining the drawable in XML like this:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="">
  <item android:state_enabled="false" android:state_focused="true"
        android:drawable="@drawable/item_disabled" />
  <item android:state_pressed="true"
        android:drawable="@drawable/item_pressed" />
  <item android:state_focused="true"
        android:drawable="@drawable/item_focused" />

How to import XML file into MySQL database table using XML_LOAD(); function

Since ID is auto increment, you can also specify ID=NULL as,

LOAD XML LOCAL INFILE '/pathtofile/file.xml' INTO TABLE my_tablename SET ID=NULL;

Why use String.Format?

There's interesting stuff on the performance aspects in this question

However I personally would still recommend string.Format unless performance is critical for readability reasons.

string.Format("{0}: {1}", key, value);

Is more readable than

key + ": " + value

For instance. Also provides a nice separation of concerns. Means you can have

string.Format(GetConfigValue("KeyValueFormat"), key, value);

And then changing your key value format from "{0}: {1}" to "{0} - {1}" becomes a config change rather than a code change.

string.Format also has a bunch of format provision built into it, integers, date formatting, etc.

Laravel 5 Clear Views Cache

Right now there is no view:clear command. For laravel 4 this can probably help you:

Disabling caching can be done by skipping blade. View caching is done because blade compiling each time is a waste of time.

Route [login] not defined

Replace in your views (blade files) all

{{route('/')}} ----- by ----> {{url('/')}}

SQL Order By Count

SELECT * FROM table 
group by `Group`

Remove NA values from a vector

The na.omit function is what a lot of the regression routines use internally:

vec <- 1:1000
vec[runif(200, 1, 1000)] <- NA
#[1] NA
max( na.omit(vec) )
#[1] 1000

How does Java handle integer underflows and overflows and how would you check for it?

It wraps around.


public class Test {

    public static void main(String[] args) {
        int i = Integer.MAX_VALUE;
        int j = Integer.MIN_VALUE;




How to POST a FORM from HTML to ASPX page

You sure can. Create an HTML page with the form in it that will contain the necessary components from the login.aspx page (i.e. username, etc), and make sure they have the same IDs. For you action, make sure it's a post.

You might have to do some code on the login.aspx page in the Page_Load function to read the form (in the Request.Form object) and call the appropriate functions to log the user in, but other than that, you should have access to the form, and can do what you want with it.

Android marshmallow request permission?

  if (CommonMethod.isNetworkAvailable(MainActivity.this)) {
                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                        int permissionCheck = ContextCompat.checkSelfPermission(MainActivity.this,
                        if (permissionCheck == PackageManager.PERMISSION_GRANTED) {
                            //showing dialog to select image
                            Log.e("permission", "granted MarshMallow");
                        } else {
                                    new String[]{android.Manifest.permission.READ_EXTERNAL_STORAGE,
                                            android.Manifest.permission.WRITE_EXTERNAL_STORAGE, android.Manifest.permission.CAMERA}, 1);
                    } else {
                        Log.e("permission", "Not Required Less than MarshMallow Version");
                } else {
                    CommonMethod.showAlert("Internet Connectivity Failure", MainActivity.this);

What precisely does 'Run as administrator' do?

Okay, let's re-iterate...

The actual question (and an excellent one at that)

"What does 'run as admin' do that being a member of the administrators group does not?"

(Answer)1. It allows you to call on administrator rights while under a user session.

Note: The question is wrongly put; one is a command and the other is a group object to apply policies.

Open a command prompt and type runas /?.

This will list all the switches the runas command line can use.

As for the Administrators Group this is based on GPEDIT or SECPOL and whether or not a Domain administrator is present or not or a network is present or not.

Usually these things will apply restrictions on computers that the administrators group is not affected by.

The question should be

What does runas admin do that run as user does not?


What does the Administrator group do that a customized user group can't?

You are mixing apples and oranges.

python: how to check if a line is an empty line

line.strip() == ''

Or, if you don't want to "eat up" lines consisting of spaces:

line in ('\n', '\r\n')

Using Apache httpclient for https

When I used Apache HTTP Client 4.3, I was using the Pooled or Basic Connection Managers to the HTTP Client. I noticed, from using java SSL debugging, that these classes loaded the cacerts trust store and not the one I had specified programmatically.

PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager();
BasicHttpClientConnectionManager cm = new BasicHttpClientConnectionManager();
builder.setConnectionManager( cm );

I wanted to use them but ended up removing them and creating an HTTP Client without them. Note that builder is an HttpClientBuilder.

I confirmed when running my program with the Java SSL debug flags, and stopped in the debugger. I used as a VM argument. I stopped my code in the debugger and when either of the above *ClientConnectionManager were constructed, the cacerts file would be loaded.

Pythonic way to check if a file exists?

It seems to me that all other answers here (so far) fail to address the race-condition that occurs with their proposed solutions.

Any code where you first check for the files existence, and then, a few lines later in your program, you create it, runs the risk of the file being created while you weren't looking and causing you problems (or you causing the owner of "that other file" problems).

If you want to avoid this sort of thing, I would suggest something like the following (untested):

import os

def open_if_not_exists(filename):
        fd =, os.O_CREAT | os.O_EXCL | os.O_WRONLY)
    except OSError, e:
        if e.errno == 17:
            print e
            return None
        return os.fdopen(fd, 'w')

This should open your file for writing if it doesn't exist already, and return a file-object. If it does exists, it will print "Ooops" and return None (untested, and based solely on reading the python documentation, so might not be 100% correct).

Checking if a list is empty with LINQ

You could do this:

public static Boolean IsEmpty<T>(this IEnumerable<T> source)
    if (source == null)
        return true; // or throw an exception
    return !source.Any();

Edit: Note that simply using the .Count method will be fast if the underlying source actually has a fast Count property. A valid optimization above would be to detect a few base types and simply use the .Count property of those, instead of the .Any() approach, but then fall back to .Any() if no guarantee can be made.

Render HTML string as real HTML in a React component

Check if the text you're trying to append to the node is not escaped like this:

var prop = {
    match: {
        description: '&lt;h1&gt;Hi there!&lt;/h1&gt;'

Instead of this:

var prop = {
    match: {
        description: '<h1>Hi there!</h1>'

if is escaped you should convert it from your server-side.

The node is text because is escaped

The node is text because is escaped

The node is a dom node because isn't escaped

The node is a dom node because isn't escaped

Programmatically add new column to DataGridView

Here's a sample method that adds two extra columns programmatically to the grid view:

    private void AddColumnsProgrammatically()
        // I created these columns at function scope but if you want to access 
        // easily from other parts of your class, just move them to class scope.
        // E.g. Declare them outside of the function...
        var col3 = new DataGridViewTextBoxColumn();
        var col4 = new DataGridViewCheckBoxColumn();

        col3.HeaderText = "Column3";
        col3.Name = "Column3";

        col4.HeaderText = "Column4";
        col4.Name = "Column4";

        dataGridView1.Columns.AddRange(new DataGridViewColumn[] {col3,col4});

A great way to figure out how to do this kind of process is to create a form, add a grid view control and add some columns. (This process will actually work for ANY kind of form control. All instantiation and initialization happens in the Designer.) Then examine the form's Designer.cs file to see how the construction takes place. (Visual Studio does everything programmatically but hides it in the Form Designer.)

For this example I created two columns for the view named Column1 and Column2 and then searched Form1.Designer.cs for Column1 to see everywhere it was referenced. The following information is what I gleaned and, copied and modified to create two more columns dynamically:

// Note that this info scattered throughout the designer but can easily collected.

        System.Windows.Forms.DataGridViewTextBoxColumn Column1;
        System.Windows.Forms.DataGridViewCheckBoxColumn Column2;

        this.Column1 = new System.Windows.Forms.DataGridViewTextBoxColumn();
        this.Column2 = new System.Windows.Forms.DataGridViewCheckBoxColumn();

        this.dataGridView1.Columns.AddRange(new System.Windows.Forms.DataGridViewColumn[] {

        this.Column1.HeaderText = "Column1";
        this.Column1.Name = "Column1";

        this.Column2.HeaderText = "Column2";
        this.Column2.Name = "Column2";

How to re-sign the ipa file?

  1. Unzip the .ipa file by changing its extension with .zip
  2. Go to Payload. You will find .app file
  3. Right click the .app file and click Show package contents
  4. Delete the _CodeSigned folder
  5. Replace the embedded.mobileprovision file with the new provision profile
  6. Go to KeyChain Access and make sure the certificate associated with the provisional profile is present
  7. Execute the below mentioned command: /usr/bin/codesign -f -s "iPhone Distribution: Certificate Name" --resource-rules "Payload/" "Payload/"

  8. Now zip the Payload folder again and change the .zip extension with .ipa

Hope this helpful.

For reference follow below mentioned link:

How do I get the entity that represents the current user in Symfony2?

In symfony >= 3.2, documentation states that:

An alternative way to get the current user in a controller is to type-hint the controller argument with UserInterface (and default it to null if being logged-in is optional):

use Symfony\Component\Security\Core\User\UserInterface\UserInterface;

public function indexAction(UserInterface $user = null)
    // $user is null when not logged-in or anon.

This is only recommended for experienced developers who don't extend from the Symfony base controller and don't use the ControllerTrait either. Otherwise, it's recommended to keep using the getUser() shortcut.

Blog post about it

Get value (String) of ArrayList<ArrayList<String>>(); in Java


You are clearing the list here and adding one element ("first"), the 1st reference of listOfSomething is updated as well sonce both reference the same object, so when you access the second element myList.get(1) (which does not exist anymore) you get the null.

Notice both collection.Add(listOfSomething); save two references to the same arraylist object.

You need to create two different instances for two elements:

ArrayList<ArrayList<String>> collection = new ArrayList<ArrayList<String>>();

ArrayList<String> listOfSomething1 = new ArrayList<String>();

ArrayList<String> listOfSomething2 = new ArrayList<String>();


How to tune Tomcat 5.5 JVM Memory settings without using the configuration program

Not sure that it will be applicable solution for you. But the only way for monitoring tomcat memory settings as well as number of connections etc. that actually works for us is Lambda Probe.

It shows most of informations that we need for Tomcat tunning. We tested it with Tomcat 5.5 and 6.0 and it works fine despite beta status and date of last update in end of 2006.

How can I hide an HTML table row <tr> so that it takes up no space?

I was having same problem and I resolved the issue. Earlier css was overflow:hidden; z-index:999999;

I change it to overflow:visible;

Insert a row to pandas dataframe

One way to achieve this is

>>> pd.DataFrame(np.array([[2, 3, 4]]), columns=['A', 'B', 'C']).append(df, ignore_index=True)
   A  B  C
0  2  3  4
1  5  6  7
2  7  8  9

Generally, it's easiest to append dataframes, not series. In your case, since you want the new row to be "on top" (with starting id), and there is no function pd.prepend(), I first create the new dataframe and then append your old one.

ignore_index will ignore the old ongoing index in your dataframe and ensure that the first row actually starts with index 1 instead of restarting with index 0.

Typical Disclaimer: Cetero censeo ... appending rows is a quite inefficient operation. If you care about performance and can somehow ensure to first create a dataframe with the correct (longer) index and then just inserting the additional row into the dataframe, you should definitely do that. See:

>>> index = np.array([0, 1, 2])
>>> df2 = pd.DataFrame(columns=['A', 'B', 'C'], index=index)
>>> df2.loc[0:1] = [list(s1), list(s2)]
>>> df2
     A    B    C
0    5    6    7
1    7    8    9
2  NaN  NaN  NaN
>>> df2 = pd.DataFrame(columns=['A', 'B', 'C'], index=index)
>>> df2.loc[1:] = [list(s1), list(s2)]

So far, we have what you had as df:

>>> df2
     A    B    C
0  NaN  NaN  NaN
1    5    6    7
2    7    8    9

But now you can easily insert the row as follows. Since the space was preallocated, this is more efficient.

>>> df2.loc[0] = np.array([2, 3, 4])
>>> df2
   A  B  C
0  2  3  4
1  5  6  7
2  7  8  9

Java enum with multiple value types

First, the enum methods shouldn't be in all caps. They are methods just like other methods, with the same naming convention.

Second, what you are doing is not the best possible way to set up your enum. Instead of using an array of values for the values, you should use separate variables for each value. You can then implement the constructor like you would any other class.

Here's how you should do it with all the suggestions above:

public enum States {
    MASSACHUSETTS("Massachusetts",  "MA",   true),
    MICHIGAN     ("Michigan",       "MI",   false),
    ...; // all 50 of those

    private final String full;
    private final String abbr;
    private final boolean originalColony;

    private States(String full, String abbr, boolean originalColony) {
        this.full = full;
        this.abbr = abbr;
        this.originalColony = originalColony;

    public String getFullName() {
        return full;

    public String getAbbreviatedName() {
        return abbr;

    public boolean isOriginalColony(){
        return originalColony;

how to open a url in python

On window

import os
os.system("start \"\"")

On macOS

import os
os.system("open \"\"")

On Linux

import os
os.system("xdg-open \"\"")


import webbrowser'')

Best way to represent a fraction in Java?

Please make it an immutable type! The value of a fraction doesn't change - a half doesn't become a third, for example. Instead of setDenominator, you could have withDenominator which returns a new fraction which has the same numerator but the specified denominator.

Life is much easier with immutable types.

Overriding equals and hashcode would be sensible too, so it can be used in maps and sets. Outlaw Programmer's points about arithmetic operators and string formatting are good too.

As a general guide, have a look at BigInteger and BigDecimal. They're not doing the same thing, but they're similar enough to give you good ideas.

Java 8 Distinct by property

I recommend using Vavr, if you can. With this library you can do the following:

                       .toJavaSet() // or any another Java 8 Collection

Javascript: Easier way to format numbers?

Here's the YUI version if anyone's interested:

var str = YAHOO.util.Number.format(12345, { thousandsSeparator: ',' } );

How can I add a table of contents to a Jupyter / JupyterLab notebook?

There is an ipython nbextension that constructs a table of contents for a notebook. It seems to only provide navigation, not section folding.

CMake does not find Visual C++ compiler

I had a related problem: the Visual C++ generators were not even on the list when running cmake --help.

I ran where cmake in console and found that cygwin also provides its own cmake.exe file, which was being used. Changing the order of directories in PATH fixed the problem.

Check if a string contains an element from a list (of strings)

The drawback of Contains method is that it doesn't allow to specify comparison type which is often important when comparing strings. It is always culture-sensitive and case-sensitive. So I think the answer of WhoIsRich is valuable, I just want to show a simpler alternative:

listOfStrings.Any(s => s.Equals(myString, StringComparison.OrdinalIgnoreCase))