Programs & Examples On #Dcu

In the Delphi domain, `DCU` stands for Delphi Compiled Unit. A `DCU` is a persistent file used by the Delphi compiler.

Flutter - The method was called on null

You have a CryptoListPresenter _presenter but you are never initializing it. You should either be doing that when you declare it or in your initState() (or another appropriate but called-before-you-need-it method).

One thing I find that helps is that if I know a member is functionally 'final', to actually set it to final as that way the analyzer complains that it hasn't been initialized.


I see diegoveloper beat me to answering this, and that the OP asked a follow up.

@Jake - it's hard for us to tell without knowing exactly what CryptoListPresenter is, but depending on what exactly CryptoListPresenter actually is, generally you'd do final CryptoListPresenter _presenter = new CryptoListPresenter(...);, or

CryptoListPresenter _presenter;

void initState() {
  _presenter = new CryptoListPresenter(...);

How to enable CORS in Core WebAPI

In my case only get request works well according to MindingData's answer. For other types of request you need to write:

app.UseCors(corsPolicyBuilder =>

Don't forget to add .AllowAnyHeader()

ERROR 1698 (28000): Access denied for user 'root'@'localhost'

step 1. sudo mysql -u root -p

step 2. USE mysql;

step 3. ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'admin';

Here 'admin' is your new password, yo can change it.

step 4. exit

Thanks. You are done.


In my case, I used the ssl module to "workaround" the certification like so:

import ssl

ssl._create_default_https_context = ssl._create_unverified_context

Then to read your link content, you can use:


Error LNK2019 unresolved external symbol _main referenced in function "int __cdecl invoke_main(void)" (?invoke_main@@YAHXZ)

Select the project. Properties->Configuration Properties->Linker->System.

My problem solved by setting below option. Under System: SubSystem = Console(/SUBSYSTEM:CONSOLE)

Or you can choose the last option as "inherite from the parent".

How to create custom view programmatically in swift having controls text field, button etc

let viewDemo = UIView()
viewDemo.frame = CGRect(x: 50, y: 50, width: 50, height: 50)

Python and JSON - TypeError list indices must be integers not str

You can simplify your code down to

url = ""
json_obj = urllib2.urlopen(url).read
player_json_list = json.loads(json_obj)
for player in readable_json_list:
    print player['firstName']

You were trying to access a list element using dictionary syntax. the equivalent of

foo = [1, 2, 3, 4]

It can be confusing when you have lists of dictionaries and keeping the nesting in order.

org.hibernate.hql.internal.ast.QuerySyntaxException: table is not mapped

In my case I just forgot to add nativeQuery = true

@Query( value = "some sql query ...", nativeQuery = true)

For Spring Boot with Spring Data JPA

Makefile: How to correctly include header file and its directory?

The preprocessor is looking for StdCUtil/split.h in

and in

  • $INC_DIR (i.e. ../StdCUtil/ = /root/Core/../StdCUtil/ = /root/StdCUtil/). So ../StdCUtil/ + StdCUtil/split.h = ../StdCUtil/StdCUtil/split.h and the file is missing

You can fix the error changing the $INC_DIR variable (best solution):

$INC_DIR = ../

or the include directive:

#include "split.h"

but in this way you lost the "path syntax" that makes it very clear what namespace or module the header file belongs to.



It should also be

CXX = g++
CXXFLAGS = -c -Wall -I$(INC_DIR)


%.o: %.cpp $(DEPS)
    $(CXX) -o $@ $< $(CXXFLAGS)

Wait on the Database Engine recovery handle failed. Check the SQL server error log for potential causes

In my case, setting SQL Server Database Engine service startup account to NT AUTHORITY\NETWORK SERVICE failed, but setting it to NT Authority\System allowed me to succesfully install my SQL Server 2016 STD instance.

Just check the following snapshot.

enter image description here

For further details, check @Shanky's answer at

Remember: you can avoid server rebooting using setup's SkipRules switch:

setup.exe /ACTION=INSTALL /SkipRules=RebootRequiredCheck

setup.exe /ACTION=UNINSTALL /SkipRules=RebootRequiredCheck

Parse String date in (yyyy-MM-dd) format

You may need to format the out put as follows.

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
Date convertedCurrentDate = sdf.parse("2013-09-18");
String date=sdf.format(convertedCurrentDate );


String convertedCurrentDate =sdf.format(sdf.parse("2013-09-18"));



Using LINQ to group a list of objects

var groupedCustomerList = CustomerList.GroupBy(u => u.GroupID)
                                      .Select(grp =>new { GroupID =grp.Key, CustomerList = grp.ToList()})

Get method arguments using Spring AOP?

you can get method parameter and its value and if annotated with a annotation with following code:

Map<String, Object> annotatedParameterValue = getAnnotatedParameterValue(MethodSignature.class.cast(jp.getSignature()).getMethod(), jp.getArgs()); ....

private Map<String, Object> getAnnotatedParameterValue(Method method, Object[] args) {
        Map<String, Object> annotatedParameters = new HashMap<>();
        Annotation[][] parameterAnnotations = method.getParameterAnnotations();
        Parameter[] parameters = method.getParameters();

        int i = 0;
        for (Annotation[] annotations : parameterAnnotations) {
            Object arg = args[i];
            String name = parameters[i++].getDeclaringExecutable().getName();
            for (Annotation annotation : annotations) {
                if (annotation instanceof AuditExpose) {
                    annotatedParameters.put(name, arg);
        return annotatedParameters;

Doctrine query builder using inner join with conditions

I'm going to answer my own question.

  1. innerJoin should use the keyword "WITH" instead of "ON" (Doctrine's documentation [13.2.6. Helper methods] is inaccurate; [13.2.5. The Expr class] is correct)
  2. no need to link foreign keys in join condition as they're already specified in the entity mapping.

Therefore, the following works for me

    ->innerJoin('c.phones', 'p', 'WITH', ' = :phone')
    ->where('c.username = :username');


    ->innerJoin('c.phones', 'p', Join::WITH, $qb->expr()->eq('', ':phone'))
    ->where('c.username = :username');

How to add new DataRow into DataTable?

You can try with this code - based on Rows.Add method

DataTable table = new DataTable();
DataRow row = table.NewRow();

Link :

adding css class to multiple elements

try this:

.button input, .button a {
//css here

That will apply the style to all a tags nested inside of <p class="button"></p>

Error 415 Unsupported Media Type: POST not reaching REST if JSON, but it does if XML

just change the content-type to application/json when you use JSON with POST/PUT, etc...

Delete cookie by name?

In my case I used blow code for different environment.

  document.cookie = name +`=; Path=/; Expires=Thu, 01 Jan 1970 00:00:01 GMT;Domain=.${document.domain.split('.').splice(1).join('.')}`;

cin and getline skipping input

I faced this issue, and resolved this issue using getchar() to catch the ('\n') new char

How do I decode a base64 encoded string?

The m000493 method seems to perform some kind of XOR encryption. This means that the same method can be used for both encrypting and decrypting the text. All you have to do is reverse m0001cd:

string p0 = Encoding.UTF8.GetString(Convert.FromBase64String("OBFZDT..."));

string result = m000493(p0, "_p0lizei.");
//    result == "gaia^unplugged^Ta..."

with return m0001cd(builder3.ToString()); changed to return builder3.ToString();.

Adding <script> to WordPress in <head> element

I believe that is your best reference to handle this task very well depends on your needs

check out these two pages on WordPress Codex:



SQL grouping by month and year

In postgresql I can write a similar query with a date-format function (to_char) and grouping just by date:

SELECT to_char (datum, 'MM-YYYY') AS mjesec 
FROM test 
GROUP BY datum 
ORDER BY datum;

Such thing is surely possible with SQL-Server too, isn't it?

what does this mean ? image/png;base64?

That data:image/png;base64 URL is cool, I’ve never run into it before. The long encrypted link is the actual image, i.e. no image call to the server. See RFC 2397 for details.

Side note: I have had trouble getting larger base64 images to render on IE8. I believe IE8 has a 32K limit that can be problematic for larger files. See this other StackOverflow thread for details.

How to parse SOAP XML?

PHP version > 5.0 has a nice SoapClient integrated. Which doesn't require to parse response xml. Here's a quick example

$client = new SoapClient("");
$res = $client->SoapFunction(array('param1'=>'value','param2'=>'value'));
echo $res->PaymentNotification->payment;

Using Linq to group a list of objects into a new grouped list of list of objects

Your group statement will group by group ID. For example, if you then write:

foreach (var group in groupedCustomerList)
    Console.WriteLine("Group {0}", group.Key);
    foreach (var user in group)
        Console.WriteLine("  {0}", user.UserName);

that should work fine. Each group has a key, but also contains an IGrouping<TKey, TElement> which is a collection that allows you to iterate over the members of the group. As Lee mentions, you can convert each group to a list if you really want to, but if you're just going to iterate over them as per the code above, there's no real benefit in doing so.

How to store custom objects in NSUserDefaults

If anybody is looking for a swift version:

1) Create a custom class for your data

class customData: NSObject, NSCoding {
let name : String
let url : String
let desc : String

init(tuple : (String,String,String)){ = tuple.0
    self.url = tuple.1
    self.desc = tuple.2
func getName() -> String {
    return name
func getURL() -> String{
    return url
func getDescription() -> String {
    return desc
func getTuple() -> (String,String,String) {
    return (,self.url,self.desc)

required init(coder aDecoder: NSCoder) { = aDecoder.decodeObjectForKey("name") as! String
    self.url = aDecoder.decodeObjectForKey("url") as! String
    self.desc = aDecoder.decodeObjectForKey("desc") as! String

func encodeWithCoder(aCoder: NSCoder) {
    aCoder.encodeObject(, forKey: "name")
    aCoder.encodeObject(self.url, forKey: "url")
    aCoder.encodeObject(self.desc, forKey: "desc")

2) To save data use following function:

func saveData()
        let data  = NSKeyedArchiver.archivedDataWithRootObject(custom)
        let defaults = NSUserDefaults.standardUserDefaults()
        defaults.setObject(data, forKey:"customArray" )

3) To retrieve:

if let data = NSUserDefaults.standardUserDefaults().objectForKey("customArray") as? NSData
             custom = NSKeyedUnarchiver.unarchiveObjectWithData(data) as! [customData]

Note: Here I am saving and retrieving an array of the custom class objects.

search in java ArrayList

I did something close to that, the compiler is seeing that your return statement is in an If() statement. If you wish to resolve this error, simply create a new local variable called customerId before the If statement, then assign a value inside of the if statement. After the if statement, call your return statement, and return cstomerId. Like this:

Customer findCustomerByid(int id)
    boolean exist=false;

    if(this.customers.isEmpty()) {
        return null;

    for(int i=0;i<this.customers.size();i++) {
        if(this.customers.get(i).getId() == id) {

        int customerId;

        if(exist) {
            customerId = this.customers.get(id);
        } else {
            customerId = this.customers.get(id);
    return customerId;

How to Concatenate Numbers and Strings to Format Numbers in T-SQL?

You need to CAST your numeric data to strings before you do string concatenation, so for example use CAST(@Actual_Dims_Lenght AS VARCHAR) instead of just @Actual_Dims_Lenght, &c.

Run a php app using tomcat?

It's quite common to run Tomcat behind Apache. In Apache you can then direct certain URLs to Tomcat, and have Apache/PHP handle the others (including the static images).

(On Unix, Tomcat itself cannot securely made to run on port 80, while Apache can. Tomcat, being a Java process, would be required to run as root, while Apache will switch to non-root privileges as soon as port 80 has been claimed. So, running Apache on port 80 and have it redirect some or all requests to Tomcat, is quite common on Unix.)

SQL Server: Query fast, but slow from procedure

I found the problem, here's the script of the slow and fast versions of the stored procedure:



CREATE PROCEDURE dbo.ViewOpener_RenamedForCruachan_Slow
    @SessionGUID uniqueidentifier

FROM Report_Opener_RenamedForCruachan
WHERE SessionGUID = @SessionGUID
ORDER BY CurrencyTypeOrder, Rank




CREATE PROCEDURE dbo.ViewOpener_RenamedForCruachan_Fast
    @SessionGUID uniqueidentifier 

FROM Report_Opener_RenamedForCruachan
WHERE SessionGUID = @SessionGUID
ORDER BY CurrencyTypeOrder, Rank


If you didn't spot the difference, I don't blame you. The difference is not in the stored procedure at all. The difference that turns a fast 0.5 cost query into one that does an eager spool of 6 million rows:



This answer also could be made to make sense, since the view does have a join clause that says:

(table.column IS NOT NULL)

So there is some NULLs involved.

The explanation is further proved by returning to Query Analizer, and running



DECLARE @SessionGUID uniqueidentifier
SET @SessionGUID = 'BCBA333C-B6A1-4155-9833-C495F22EA908'


FROM Report_Opener_RenamedForCruachan
WHERE SessionGUID = @SessionGUID
ORDER BY CurrencyTypeOrder, Rank

And the query is slow.

So the problem isn't because the query is being run from a stored procedure. The problem is that Enterprise Manager's connection default option is ANSI_NULLS off, rather than ANSI_NULLS on, which is QA's default.

Microsoft acknowledges this fact in KB296769 (BUG: Cannot use SQL Enterprise Manager to create stored procedures containing linked server objects). The workaround is include the ANSI_NULLS option in the stored procedure dialog:

Create Proc spXXXX as

SQL query question: SELECT ... NOT IN

It's always dangerous to have NULL in the IN list - it often behaves as expected for the IN but not for the NOT IN:

IF 1 NOT IN (1, 2, 3, NULL) PRINT '1 NOT IN (1, 2, 3, NULL)'
IF 1 NOT IN (2, 3, NULL) PRINT '1 NOT IN (2, 3, NULL)'
IF 1 NOT IN (2, 3) PRINT '1 NOT IN (2, 3)' -- Prints
IF 1 IN (1, 2, 3, NULL) PRINT '1 IN (1, 2, 3, NULL)' -- Prints
IF 1 IN (2, 3, NULL) PRINT '1 IN (2, 3, NULL)'
IF 1 IN (2, 3) PRINT '1 IN (2, 3)'

Python Accessing Nested JSON Data

Places is a list and not a dictionary. This line below should therefore not work:

print data['places']['latitude']

You need to select one of the items in places and then you can list the place's properties. So to get the first post code you'd do:

print data['places'][0]['post code']

Where should I put the CSS and Javascript code in an HTML webpage?

And if you have more than one .css or .js file to call, just include them one after another, or:


<link href="css/grid.css" rel="stylesheet" />

<link href="css/style.css" rel="stylesheet" />

<script src="js/jquery-1.4.4.min.js"></script>

<script src="js/jquery.animate-colors-min.js"></script>


Append a tuple to a list - what's the difference between two ways?

I believe tuple() takes a list as an argument For example,

tuple([1,2,3]) # returns (1,2,3)

see what happens if you wrap your array with brackets

Call a python function from jinja2

There's a much simpler decision.

def x():
    return render_template('test.html', foo=y)

def y(text):
    return text

Then, in test.html:

{{ foo('hi') }}

SQL Server, division returns zero

When you use only integers in a division, you will get integer division. When you use (at least one) double or float, you will get floating point division (and the answer you want to get).

So you can

  1. declare one or both of the variables as float/double
  2. cast one or both of the variables to float/double.

Do not just cast the result of the integer division to double: the division was already performed as integer division, so the numbers behind the decimal are already lost.

SQL Server: Maximum character length of object names

Yes, it is 128, except for temp tables, whose names can only be up to 116 character long. It is perfectly explained here.

And the verification can be easily made with the following script contained in the blog post before:

SELECT @i = 'CREATE TABLE #'+@i+'(i int)'

C#: New line and tab characters in strings

It depends on if you mean '\n' (linefeed) or '\r\n' (carriage return + linefeed). The former is not the Windows default and will not show properly in some text editors (like Notepad).

You can do




.keyCode vs. .which

A robust Javascript library for capturing keyboard input and key combinations entered. It has no dependencies.

hotkeys('ctrl+a,ctrl+b,r,f', function(event,handler){
        case "ctrl+a":alert('you pressed ctrl+a!');break;
        case "ctrl+b":alert('you pressed ctrl+b!');break;
        case "r":alert('you pressed r!');break;
        case "f":alert('you pressed f!');break;

hotkeys understands the following modifiers: ?, shift, option, ?, alt, ctrl, control, command, and ?.

The following special keys can be used for shortcuts: backspace, tab, clear, enter, return, esc, escape, space, up, down, left, right, home, end, pageup, pagedown, del, delete and f1 through f19.

How to define a two-dimensional array?

If you really want a matrix, you might be better off using numpy. Matrix operations in numpy most often use an array type with two dimensions. There are many ways to create a new array; one of the most useful is the zeros function, which takes a shape parameter and returns an array of the given shape, with the values initialized to zero:

>>> import numpy
>>> numpy.zeros((5, 5))
array([[ 0.,  0.,  0.,  0.,  0.],
       [ 0.,  0.,  0.,  0.,  0.],
       [ 0.,  0.,  0.,  0.,  0.],
       [ 0.,  0.,  0.,  0.,  0.],
       [ 0.,  0.,  0.,  0.,  0.]])

Here are some other ways to create 2-d arrays and matrices (with output removed for compactness):

numpy.arange(25).reshape((5, 5))         # create a 1-d range and reshape
numpy.array(range(25)).reshape((5, 5))   # pass a Python range and reshape
numpy.array([5] * 25).reshape((5, 5))    # pass a Python list and reshape
numpy.empty((5, 5))                      # allocate, but don't initialize
numpy.ones((5, 5))                       # initialize with ones

numpy provides a matrix type as well, but it is no longer recommended for any use, and may be removed from numpy in the future.

Reading NFC Tags with iPhone 6 / iOS 8

The iPhone6/6s/6+ are NOT designed to read passive NFC tags (aka Discovery Mode). There's a lot of misinformation on this topic, so I thought to provide some tangible info for developers to consider. The lack of NFC tag read support is not because of software but because of hardware. To understand why, you need to understand how NFC works. NFC works by way of Load Modulation. That means that the interrogator (PCD) emits a carrier magnetic field that energizes the passive target (PICC). With the potential generated by this carrier field, the target then is able to demodulate data coming from the interrogator and respond by modulating data over top of this very same field. The key here is that the target never creates a field of its own.

If you look at the iPhone6 teardown and parts list you will see the presence of a very small NFC loop antenna as well as the use of the AS3923 booster IC. This design was intended for custom microSD or SIM cards to enable mobile phones of old to do payments. This is the type of application where the mobile phone presents a Card Emulated credential to a high power contactless POS terminal. The POS terminal acts as the reader, energizing the iPhone6 with help from the AS3923 chip. The AS3923 block diagram clearly shows how the RX and TX modulation is boosted from a signal presented by a reader device. In other words the iPhone6 is not meant to provide a field, only to react to one. That's why it's design is only meant for NFC Card Emulation and perhaps Peer-2-Peer, but definitely not tag Discovery.

AS3923 booster IC

There are some alternatives to achieving tag Discovery with an iPhone6 using HW accessories. I talk about these integrations and how developers can architect solutions in this blog post. Our low power reader designs open interesting opportunities for mobile engagement that few developers are thinking about.

Disclosure: I'm the founder of Flomio, Inc., a TechStars company that delivers proximity ID hardware, software, and services for applications ranging from access control to payments.

Update: This rumor, if true, would open up the possibility for the iPhone to practically support NFC tag Discovery mode. An all glass design would not interfere with the NFC antenna as does the metal back of the current iPhone. We've attempted this design approach --albeit with cheaper materials-- on some of our custom reader designs with success so looking forward to this improvement.

Update: iOS11 has announced support for "NFC reader mode" for iPhone7/7+. Details here. API only supports reading NDEF messages (no ISO7816 APDUs) while an app is in the foreground (no background detection). Due out in the Fall, 2017... check the screenshot from WWDC keynote:

enter image description here

Is there any way to set environment variables in Visual Studio Code?

Assuming you mean for a debugging session(?) then you can include a env property in your launch configuration.

If you open the .vscode/launch.json file in your workspace or select Debug > Open Configurations then you should see a set of launch configurations for debugging your code. You can then add to it an env property with a dictionary of string:string.

Here is an example for an ASP.NET Core app from their standard web template setting the ASPNETCORE_ENVIRONMENT to Development :

  "version": "0.2.0",
  "configurations": [
      "name": ".NET Core Launch (web)",
      "type": "coreclr",
      "request": "launch",
      "preLaunchTask": "build",
      // If you have changed target frameworks, make sure to update the program path.
      "program": "${workspaceFolder}/bin/Debug/netcoreapp2.0/vscode-env.dll",
      "args": [],
      "cwd": "${workspaceFolder}",
      "stopAtEntry": false,
      "internalConsoleOptions": "openOnSessionStart",
      "launchBrowser": {
        "enabled": true,
        "args": "${auto-detect-url}",
        "windows": {
          "command": "cmd.exe",
          "args": "/C start ${auto-detect-url}"
        "osx": {
          "command": "open"
        "linux": {
          "command": "xdg-open"
      "env": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      "sourceFileMap": {
        "/Views": "${workspaceFolder}/Views"
      "name": ".NET Core Attach",
      "type": "coreclr",
      "request": "attach",
      "processId": "${command:pickProcess}"

How can I have linebreaks in my long LaTeX equations?

I used the \begin{matrix}

    line_1 \\ 
    line_2 \\ 

Fastest method of screen capturing on Windows

I use d3d9 to get the backbuffer, and save that to a png file using the d3dx library:

    IDirect3DSurface9 *surface ;

    // GetBackBuffer
    idirect3ddevice9->GetBackBuffer(0, 0, D3DBACKBUFFER_TYPE_MONO, &surface ) ;

    // save the surface
    D3DXSaveSurfaceToFileA( "filename.png", D3DXIFF_PNG, surface, NULL, NULL ) ;

    SAFE_RELEASE( surface ) ;

To do this you should create your swapbuffer with

d3dpps.SwapEffect = D3DSWAPEFFECT_COPY ; // for screenshots.

(So you guarantee the backbuffer isn't mangled before you take the screenshot).

How do I read text from the clipboard?

A not very direct trick:

Use pyautogui hotkey:

Import pyautogui
pyautogui.hotkey('ctrl', 'v')

Therefore, you can paste the clipboard data as you like.

Why does an image captured using camera intent gets rotated on some devices on Android?

Better try to take the picture in a specific orientation.


For best results give landscape orientation in the cameraview activity.

Add line break within tooltips

Using .html() instead of .text() worked for me. For example

.html("This is a first line." + "<br/>" + "This is a second line.")

Iterate over object keys in node.js

For simple iteration of key/values, sometimes libraries like underscorejs can be your friend.

const _ = require('underscore');

_.each(a, function (value, key) {
    // handle

just for reference

Difference between 2 dates in seconds

$timeFirst  = strtotime('2011-05-12 18:20:20');
$timeSecond = strtotime('2011-05-13 18:20:20');
$differenceInSeconds = $timeSecond - $timeFirst;

You will then be able to use the seconds to find minutes, hours, days, etc.

Is there a limit on number of tcp/ip connections between machines on linux?

When looking for the max performance you run into a lot of issue and potential bottlenecks. Running a simple hello world test is not necessarily going to find them all.

Possible limitations include:

  • Kernel socket limitations: look in /proc/sys/net for lots of kernel tuning..
  • process limits: check out ulimit as others have stated here
  • as your application grows in complexity, it may not have enough CPU power to keep up with the number of connections coming in. Use top to see if your CPU is maxed
  • number of threads? I'm not experienced with threading, but this may come into play in conjunction with the previous items.

Testing web application on Mac/Safari when I don't own a Mac

The best site to test website and see them realtime on MAC Safari is by using


They have like 25 free minutes of first time testing and then 10 free mins each day..You can even test your pages from your local PC by using their WEB TUNNEL Feature

I tested 7 to 8 pages in browserstack...And I think they have some java debugging tool in the upper right corner that is great help

Yarn: How to upgrade yarn version using terminal?

Not remembering how i've installed yarn the command that worked for me was:

yarn policies set-version

This command updates the current yarn version to the latest stable.

From the documentation:

Note that this command also is the preferred way to upgrade Yarn - it will work no matter how you originally installed it, which might sometimes prove difficult to figure out otherwise.


jQuery, simple polling example

function make_call()
  // do the request

  }, 5000);

$(document).ready(function() {

How can I solve "Either the parameter @objname is ambiguous or the claimed @objtype (COLUMN) is wrong."?

i also had this issue- very annoying and haven't found a satisfactory sql answer myself yet (aside from long-winded ones involving creating temp tables etc.) and i didn't have time to explore it to the conclusion i'd have liked.

In the end just used SQL Server Management Studio to do it by selecting the table, right-clicking on the column and hitting rename. simples!

obviously i'd rather know how to do it without a gui but sometimes you've just gotta get sh** done!

How to extract numbers from a string in Python?

To catch different patterns it is helpful to query with different patterns.

Setup all the patterns that catch different number patterns of interest:

(finds commas) 12,300 or 12,300.00


(finds floats) 0.123 or .123


(finds integers) 123


Combine with pipe ( | ) into one pattern with multiple or conditionals.

(Note: Put complex patterns first else simple patterns will return chunks of the complex catch instead of the complex catch returning the full catch).

p = '[\d]+[.,\d]+|[\d]*[.][\d]+|[\d]+'

Below, we'll confirm a pattern is present with, then return an iterable list of catches. Finally, we'll print each catch using bracket notation to subselect the match object return value from the match object.

s = 'he33llo 42 I\'m a 32 string 30 444.4 12,001'

if, s) is not None:
    for catch in re.finditer(p, s):
        print(catch[0]) # catch is a match object



removing html element styles via javascript



For native javascript

How to pass multiple parameters in thread in VB

Just create a class or structure that has two members, one List(Of OneItem) and the other Integer and send in an instance of that class.

Edit: Sorry, missed that you had problems with one parameter as well. Just look at Thread Constructor (ParameterizedThreadStart) and that page includes a simple sample.

How to convert the background to transparent?

For Photoshop you need to download Photoshop portable.... Load image e press "w" click in image e suave as png or gif....

Set CSS property in Javascript?


var element = document.createElement('select'); = "100px";

Using if(isset($_POST['submit'])) to not display echo when script is open is not working

Whats wrong in this?

<form class="navbar-form navbar-right" method="post" action="login.php">
  <div class="form-group">
    <input type="email" name="email" class="form-control" placeholder="email">
    <input type="password" name="password" class="form-control" placeholder="password">
  <input type="submit" name="submit" value="submit" class="btn btn-success">


if(isset($_POST['submit']) && !empty($_POST['submit'])) {
  // if (!logged_in()) 
  echo 'asodj';

Merging two CSV files using Python

You need to store all of the extra rows in the files in your dictionary, not just one of them:

dict1 = {row[0]: row[1:] for row in r}
dict2 = {row[0]: row[1:] for row in r}

Then, since the values in the dictionaries are lists, you need to just concatenate the lists together:

w.writerows([[key] + dict1.get(key, []) + dict2.get(key, []) for key in keys])

C# Convert List<string> to Dictionary<string, string>

You can use:

var dictionary = myList.ToDictionary(x => x);

ISO C90 forbids mixed declarations and code in C

I think you should move the variable declaration to top of block. I.e.

    int i = 0;


    int i = 0;

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

Java 8 now provides the most concise method to get current Unix Timestamp:;

Make the current commit the only (initial) commit in a Git repository?

Here you go:

# By Zibri (2019)
# Usage: gitclean username password giturl
gitclean () 
    if [ "$#" -ne 3 ]; then
        echo "Usage: gitclean username password giturl";
        return 1;
    temp=$(mktemp -d 2>/dev/null /dev/shm/git.XXX || mktemp -d 2>/dev/null /tmp/git.XXX);
    cd "$temp";
    url=$(echo "$3" |sed -e "s/[^/]*\/\/\([^@]*@\)\?\.*/\1/");
    git clone "https://$1:$2@$url" && { 
        cd *;
        for BR in "$(git branch|tr " " "\n"|grep -v '*')";
            echo working on branch $BR;
            git checkout $BR;
            git checkout --orphan $(basename "$temp"|tr -d .);
            git add -A;
            git commit -m "Initial Commit" && { 
                git branch -D $BR;
                git branch -m $BR;
                git push -f origin $BR;
                git gc --aggressive --prune=all
    cd $odir;
    rm -rf "$temp"

Also hosted here:

How to run a script file remotely using SSH

Backticks will run the command on the local shell and put the results on the command line. What you're saying is 'execute ./test/ and then pass the output as if I'd typed it on the commandline here'.

Try the following command, and make sure that thats the path from your home directory on the remote computer to your script.

ssh kev@server1 './test/'

Also, the script has to be on the remote computer. What this does is essentially log you into the remote computer with the listed command as your shell. You can't run a local script on a remote computer like this (unless theres some fun trick I don't know).

Oracle pl-sql escape character (for a " ' ")

you can use ESCAPE like given example below

The '_' wild card character is used to match exactly one character, while '%' is used to match zero or more occurrences of any characters. These characters can be escaped in SQL.

SELECT name FROM emp WHERE id LIKE '%/_%' ESCAPE '/';

The same works inside PL/SQL:

 if( id like '%/_%' ESCAPE '/' )

This applies only to like patterns, for example in an insert there is no need to escape _ or %, they are used as plain characters anyhow. In arbitrary strings only ' needs to be escaped by ''.

Simple post to Web Api

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

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

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

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

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

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

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

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

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

and your web api action will look something like below.

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

This page explains it all.

How to redirect the output of DBMS_OUTPUT.PUT_LINE to a file?

DBMS_OUTPUT is not the best tool to debug, since most environments don't use it natively. If you want to capture the output of DBMS_OUTPUT however, you would simply use the DBMS_OUTPUT.get_line procedure.

Here is a small example:

SQL> create directory tmp as '/tmp/';

Directory created

  2     l_line VARCHAR2(255);
  3     l_done NUMBER;
  4     l_file utl_file.file_type;
  5  BEGIN
  6     l_file := utl_file.fopen('TMP', 'foo.log', 'A');
  7     LOOP
  8        EXIT WHEN l_done = 1;
  9        dbms_output.get_line(l_line, l_done);
 10        utl_file.put_line(l_file, l_line);
 11     END LOOP;
 12     utl_file.fflush(l_file);
 13     utl_file.fclose(l_file);
 14  END write_log;
 15  /

Procedure created

  2     dbms_output.enable(100000);
  3     -- write something to DBMS_OUTPUT
  4     dbms_output.put_line('this is a test');
  5     -- write the content of the buffer to a file
  6     write_log;
  7  END;
  8  /

PL/SQL procedure successfully completed

SQL> host cat /tmp/foo.log

this is a test

How to set Grid row and column positions programmatically

For attached properties you can either call SetValue on the object for which you want to assign the value:

tblock.SetValue(Grid.RowProperty, 4);

Or call the static Set method (not as an instance method like you tried) for the property on the owner type, in this case SetRow:

Grid.SetRow(tblock, 4);

Haskell: Converting Int to String

The opposite of read is show.

Prelude> show 3

Prelude> read $ show 3 :: Int

Get only part of an Array in Java?

Check out copyOfRange; and example:

int[] arr2 = Arrays.copyOfRange(arr,0,3);

Django, creating a custom 500/404 error page

If all you need is to show custom pages which have some fancy error messages for your site when DEBUG = False, then add two templates named 404.html and 500.html in your templates directory and it will automatically pick up this custom pages when a 404 or 500 is raised.

Correct file permissions for WordPress

I think the below rules are recommended for a default wordpress site:

  • For folders inside wp-content, set 0755 permissions:

    chmod -R 0755 plugins

    chmod -R 0755 uploads

    chmod -R 0755 upgrade

  • Let apache user be the owner for the above directories of wp-content:

    chown apache uploads

    chown apache upgrade

    chown apache plugins

Why is the apt-get function not working in the terminal on Mac OS X v10.9 (Mavericks)?

As Homebrew is my favorite for macOS although it is possible to have apt-get on macOS using Fink.

How to re-create database for Entity Framework?

While this question is premised by not caring about the data, sometimes maintenance of the data is essential.

If so, I wrote a list of steps on how to recover from Entity Framework nightmare when the database already has tables with the same name here: How to recover from Entity Framework nightmare - database already has tables with the same name

Apparently... a moderator saw fit to delete my post so I'll paste it here:

How to recover from Entity Framework nightmare - database already has tables with the same name

Description: If you're like us when your team is new to EF, you'll end up in a state where you either can't create a new local database or you can't apply updates to your production database. You want to get back to a clean EF environment and then stick to basics, but you can't. If you get it working for production, you can't create a local db, and if you get it working for local, your production server gets out of sync. And finally, you don't want to delete any production server data.

Symptom: Can't run Update-Database because it's trying to run the creation script and the database already has tables with the same name.

Error Message: System.Data.SqlClient.SqlException (0x80131904): There is already an object named '' in the database.

Problem Background: EF understands where the current database is at compared to where the code is at based on a table in the database called dbo.__MigrationHistory. When it looks at the Migration Scripts, it tries to reconsile where it was last at with the scripts. If it can't, it just tries to apply them in order. This means, it goes back to the initial creation script and if you look at the very first part in the UP command, it'll be the CreeateTable for the table that the error was occurring on.

To understand this in more detail, I'd recommend watching both videos referenced here:

Solution: What we need to do is to trick EF into thinking that the current database is up to date while not applying these CreateTable commands. At the same time, we still want those commands to exist so we can create new local databases.

Step 1: Production DB clean First, make a backup of your production db. In SSMS, Right-Click on the database, Select "Tasks > Export Data-tier application..." and follow the prompts. Open your production database and delete/drop the dbo.__MigrationHistory table.

Step 2: Local environment clean Open your migrations folder and delete it. I'm assuming you can get this all back from git if necessary.

Step 3: Recreate Initial In the Package Manager, run "Enable-Migrations" (EF will prompt you to use -ContextTypeName if you have multiple contexts). Run "Add-Migration Initial -verbose". This will Create the initial script to create the database from scratch based on the current code. If you had any seed operations in the previous Configuration.cs, then copy that across.

Step 4: Trick EF At this point, if we ran Update-Database, we'd be getting the original error. So, we need to trick EF into thinking that it's up to date, without running these commands. So, go into the Up method in the Initial migration you just created and comment it all out.

Step 5: Update-Database With no code to execute on the Up process, EF will create the dbo.__MigrationHistory table with the correct entry to say that it ran this script correctly. Go and check it out if you like. Now, uncomment that code and save. You can run Update-Database again if you want to check that EF thinks its up to date. It won't run the Up step with all of the CreateTable commands because it thinks it's already done this.

Step 6: Confirm EF is ACTUALLY up to date If you had code that hadn't yet had migrations applied to it, this is what I did...

Run "Add-Migration MissingMigrations" This will create practically an empty script. Because the code was there already, there was actually the correct commands to create these tables in the initial migration script, so I just cut the CreateTable and equivalent drop commands into the Up and Down methods.

Now, run Update-Database again and watch it execute your new migration script, creating the appropriate tables in the database.

Step 7: Re-confirm and commit. Build, test, run. Ensure that everything is running then commit the changes.

Step 8: Let the rest of your team know how to proceed. When the next person updates, EF won't know what hit it given that the scripts it had run before don't exist. But, assuming that local databases can be blown away and re-created, this is all good. They will need to drop their local database and add create it from EF again. If they had local changes and pending migrations, I'd recommend they create their DB again on master, switch to their feature branch and re-create those migration scripts from scratch.

How can I show and hide elements based on selected option with jQuery?

    $('#colorselector').on('change', function() {
      if ( this.value == 'red')

Do like this for every value

ArrayList - How to modify a member of an object?

You can do this:

myList.get(3).setEmail("new email");

Property 'catch' does not exist on type 'Observable<any>'

In angular 8:

//for catch:
import { catchError } from 'rxjs/operators';

//for throw:
import { Observable, throwError } from 'rxjs';

//and code should be written like this.

getEmployees(): Observable<IEmployee[]> {
    return this.http.get<IEmployee[]>(this.url).pipe(catchError(this.erroHandler));

  erroHandler(error: HttpErrorResponse) {
    return throwError(error.message || 'server Error');

Where's my JSON data in my incoming Django request?

I had the same problem. I had been posting a complex JSON response, and I couldn't read my data using the request.POST dictionary.

My JSON POST data was:

//JavaScript code:
//Requires json2.js and jQuery.
var response = {data:[{"a":1, "b":2},{"a":2, "b":2}]}
json_response = JSON.stringify(response); // proper serialization method, read 

In this case you need to use method provided by aurealus. Read the request.body and deserialize it with the json stdlib.

#Django code:
import json
def save_data(request):
  if request.method == 'POST':
    json_data = json.loads(request.body) # request.raw_post_data w/ Django < 1.4
      data = json_data['data']
    except KeyError:
      HttpResponseServerError("Malformed data!")
    HttpResponse("Got json data")

IE11 Document mode defaults to IE7. How to reset?

Thanks to all the investigations of Lance, I could find a solution to my problem. It possibly had to do with my ISP.

To summarize:

  • Internet sites were displayed in the Intranet zone
  • Because of that the document mode was defaulted to 5 or 7 instead of Edge

I unchecked the "Automatically detect settings" in the Local Area Network Settings (found in "Internet Options" > Connections > LAN Settings.

Now the sites are correctly marked as Internet sites (instead of Intranet sites).

How to check for a valid Base64 encoded string

I know you said you didn't want to catch an exception. But, because catching an exception is more reliable, I will go ahead and post this answer.

public static bool IsBase64(this string base64String) {
     // Credit: oybek
     if (string.IsNullOrEmpty(base64String) || base64String.Length % 4 != 0
        || base64String.Contains(" ") || base64String.Contains("\t") || base64String.Contains("\r") || base64String.Contains("\n"))
        return false;

         return true;
     catch(Exception exception){
     // Handle the exception
     return false;

Update: I've updated the condition thanks to oybek to further improve reliability.

ssh: check if a tunnel is alive

This is my test. Hope it is useful.

# $COMMAND is the command used to create the reverse ssh tunnel

# Is the tunnel up? Perform two tests:

# 1. Check for relevant process ($COMMAND)
pgrep -f -x "$COMMAND" > /dev/null 2>&1 || $COMMAND

# 2. Test tunnel by looking at "netstat" output on $REMOTE_HOST
ssh -p $SSH_PORT $USER_NAME@$REMOTE_HOST netstat -an | egrep "tcp.*:$REMOTE_HTTP_PORT.*LISTEN" \
   > /dev/null 2>&1
if [ $? -ne 0 ] ; then
   pkill -f -x "$COMMAND"

Using scp to copy a file to Amazon EC2 instance?

I tried all the suggestions mentioned above and nothing worked. I terminated the current instance, launched another one and repeated the same exact process. This time no problems. Sometimes it might be the remote ami's fault.

How to find the day, month and year with moment.js

Just try with:

var check = moment(n.entry.date_entered, 'YYYY/MM/DD');

var month = check.format('M');
var day   = check.format('D');
var year  = check.format('YYYY');


include antiforgerytoken in ajax post ASP.NET MVC

        function DeletePersonel(id) {

                var data = new FormData();
                data.append("__RequestVerificationToken", "@HtmlHelper.GetAntiForgeryToken()");

                    type: 'POST',
                    url: '/Personel/Delete/' + id,
                    data: data,
                    cache: false,
                    processData: false,
                    contentType: false,
                    success: function (result) {



        public static class HtmlHelper
            public static string GetAntiForgeryToken()
                System.Text.RegularExpressions.Match value = System.Text.RegularExpressions.Regex.Match(System.Web.Helpers.AntiForgery.GetHtml().ToString(), "(?:value=\")(.*)(?:\")");
                if (value.Success)
                    return value.Groups[1].Value;
                return "";

How can I sort a List alphabetically?

Use the two argument for of Collections.sort. You will want a suitable Comparator that treats case appropriate (i.e. does lexical, not UTF16 ordering), such as that obtainable through java.text.Collator.getInstance.

Encoding as Base64 in Java

GZIP + Base64

The length of the string in a Base64 format is greater then original: 133% on average. So it makes sense to first compress it with GZIP, and then encode to Base64. It gives a reduction of up to 77% for strings greater than 200 characters and more. Example:

public static void main(String[] args) throws IOException {
    byte[] original = randomString(100).getBytes(StandardCharsets.UTF_8);

    byte[] base64 = encodeToBase64(original);
    byte[] gzipToBase64 = encodeToBase64(encodeToGZIP(original));

    byte[] fromBase64 = decodeFromBase64(base64);
    byte[] fromBase64Gzip = decodeFromGZIP(decodeFromBase64(gzipToBase64));

    // test
    System.out.println("Original: " + original.length + " bytes, 100%");
    System.out.println("Base64: " + base64.length + " bytes, "
            + (base64.length * 100 / original.length) + "%");
    System.out.println("GZIP+Base64: " + gzipToBase64.length + " bytes, "
            + (gzipToBase64.length * 100 / original.length) + "%");

    //Original: 3700 bytes, 100%
    //Base64: 4936 bytes, 133%
    //GZIP+Base64: 2868 bytes, 77%

    System.out.println(Arrays.equals(original, fromBase64)); // true
    System.out.println(Arrays.equals(original, fromBase64Gzip)); // true
public static byte[] decodeFromBase64(byte[] arr) {
    return Base64.getDecoder().decode(arr);

public static byte[] encodeToBase64(byte[] arr) {
    return Base64.getEncoder().encode(arr);
public static byte[] decodeFromGZIP(byte[] arr) throws IOException {
    ByteArrayInputStream bais = new ByteArrayInputStream(arr);
    GZIPInputStream gzip = new GZIPInputStream(bais);
    return gzip.readAllBytes();

public static byte[] encodeToGZIP(byte[] arr) throws IOException {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    GZIPOutputStream gzip = new GZIPOutputStream(baos);
    return baos.toByteArray();
public static String randomString(int count) {
    StringBuilder str = new StringBuilder();
    for (int i = 0; i < count; i++) {
        str.append(" ").append(UUID.randomUUID().toString());
    return str.toString();

how to hide the content of the div in css

Sorry to be 7 years late but this could be achieved by using the below:

    visibility: hidden;
    width: 0px;
    height: 0px;

This will keep the content on the page and won't occupy any space whereas display:none will completely hide the content.

Using the above code can be useful if you need to reference code in a div but don't need it to display.

How to force a WPF binding to refresh?

MultiBinding friendly version...

private void ComboBox_Loaded(object sender, RoutedEventArgs e)
    BindingOperations.GetBindingExpressionBase((ComboBox)sender, ComboBox.ItemsSourceProperty).UpdateTarget();

Using CSS to insert text

It is, but requires a CSS2 capable browser (all major browsers, IE8+).

.OwnerJoe:before {
  content: "Joe's Task:";

But I would rather recommend using Javascript for this. With jQuery:

$('.OwnerJoe').each(function() {
  $(this).before($('<span>').text("Joe's Task: "));

latex tabular width the same as the textwidth

The tabularx package gives you

  1. the total width as a first parameter, and
  2. a new column type X, all X columns will grow to fill up the total width.

For your example:

% ...    
% ...

Input & Output& Action return \\
DNF &  simulation & jsp\\

HTML: How to limit file upload to be only images?

You can only do this securely on the server-side. Using the "accept" attribute is good, but must also be validated on the server side lest users be able to cURL to your script without that limitation.

I suggest that you: discard any non-image file, warn the user, and redisplay the form.

Using Python 3 in virtualenv

Python now comes with its own implementation of virtual environment, by the name of "venv". I would suggest using that, instead of virtualenv.

Quoting from venv - docs,

Deprecated since version 3.6: pyvenv was the recommended tool for creating virtual environments for Python 3.3 and 3.4, and is deprecated in Python 3.6.

Changed in version 3.5: The use of venv is now recommended for creating virtual environments.

For windows, to initiate venv on some project, open cmd:

python -m venv "c:\path\to\myenv"

(Would suggest using double quote around directory path if it contains any spaces. Ex: "C:/My Dox/Spaced Directory/Something")

Once venv is set up, you will see some new folders inside your project directory. One of them would be "Scripts".

To activate or invoke venv you need:

C:\> <venv>\Scripts\activate.bat

You can deactivate a virtual environment by typing “deactivate” in your shell. With this, you are now ready to install your project specific libraries, which will reside under the folder "Lib".

================================ Edit 1 ==================================== The scenario which will be discussed below is not what originally asked, just adding this in case someone use vscode with python extension

In case, you use vs code with its python extension, you might face an issue with its pylint which points to the global installation. In this case, pylint won't be able to see the modules that are installed in your virtual environment and hence will show errors while importing.

Here is a simple method to get past this.

cd Workspace\Scripts
code .

We are basically activating the environment first and then invoking vs-code so that pylint starts within the environment and can see all local packages.

Rails Model find where not equal

In Rails 4.x (See

GroupUser.where.not(user_id: me)

In Rails 3.x


To shorten the length, you could store GroupUser.arel_table in a variable or if using inside the model GroupUser itself e.g., in a scope, you can use arel_table[:user_id] instead of GroupUser.arel_table[:user_id]

Rails 4.0 syntax credit to @jbearden's answer

How do I use Assert to verify that an exception has been thrown?

In case of using NUnit, try this:

Assert.That(() =>
        }, Throws.TypeOf<Your_Specific_Exception>().With.Message.EqualTo("Your_Specific_Message"));

Convert string to ASCII value python

It is not at all obvious why one would want to concatenate the (decimal) "ascii values". What is certain is that concatenating them without leading zeroes (or some other padding or a delimiter) is useless -- nothing can be reliably recovered from such an output.

>>> tests = ["hi", "Hi", "HI", '\x0A\x29\x00\x05']
>>> ["".join("%d" % ord(c) for c in s) for s in tests]
['104105', '72105', '7273', '104105']

Note that the first 3 outputs are of different length. Note that the fourth result is the same as the first.

>>> ["".join("%03d" % ord(c) for c in s) for s in tests]
['104105', '072105', '072073', '010041000005']
>>> [" ".join("%d" % ord(c) for c in s) for s in tests]
['104 105', '72 105', '72 73', '10 41 0 5']
>>> ["".join("%02x" % ord(c) for c in s) for s in tests]
['6869', '4869', '4849', '0a290005']

Note no such problems.

How can I mock an ES6 module import using Jest?

The question is already answered, but you can resolve it like this:

File dependency.js

const doSomething = (x) => x
export default doSomething;

File myModule.js

import doSomething from "./dependency";

export default (x) => doSomething(x * 2);

File myModule.spec.js

import doSomething from "../dependency";
import myModule from "../myModule";

describe('myModule', () => {
  it('calls the dependency with double the input', () => {
    doSomething.mockImplementation((x) => x * 10)


    console.log(myModule(2)) // 40

Difference between Statement and PreparedStatement

  • It's easier to read
  • You can easily make the query string a constant

An exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll

use try-catch to see real error occurred on you

  //Your insert code here
catch (System.Data.SqlClient.SqlException sqlException)

Press Enter to move to next control

Try to use:


How are ssl certificates verified?

The client has a pre-seeded store of SSL certificate authorities' public keys. There must be a chain of trust from the certificate for the server up through intermediate authorities up to one of the so-called "root" certificates in order for the server to be trusted.

You can examine and/or alter the list of trusted authorities. Often you do this to add a certificate for a local authority that you know you trust - like the company you work for or the school you attend or what not.

The pre-seeded list can vary depending on which client you use. The big SSL certificate vendors insure that their root certs are in all the major browsers ($$$).

Monkey-in-the-middle attacks are "impossible" unless the attacker has the private key of a trusted root certificate. Since the corresponding certificates are widely deployed, the exposure of such a private key would have serious implications for the security of eCommerce generally. Because of that, those private keys are very, very closely guarded.

How to define custom configuration variables in rails

Since Rails 4.2, without additional gems, you can load config/hi.yml simply by using Rails.application.config_for :hi.

For example:

  1. touch config/passwords.yml

          username: 'a'
          password: 'b'
          username: 'aa'
          password: 'bb'
  1. touch config/initializers/constants.rb

    AUTHENTICATION = Rails.application.config_for :passwords
  1. and now you can use AUTHENTICATION constant everywhere in your application:

    #rails c production
    :001> AUTHENTICATION['username'] => 'aa'
  2. then add passwords.yml to .gitignore: echo /config/passwords.yml >> .gitignore, create an example file for your comfort cp /config/passwords.yml /config/passwords.example.yml and then just edit your example file in your production console with actual production values.

Google Play Services Missing in Emulator (Android 4.4.2)

If you're using Xamarin, I found a guide on their official forum explaining how to do this:

  1. Download the package from the internet. There are many sources for this, one possible source is the CyanogenMod web site.
  2. Start up the Android Player and unlock it.
  3. Drag and drop the zip file that you downloaded onto the Android Player.
  4. Restart the Android Player.

Hereafter, you might also need to update the Google Play Services from the Google Play Store.

Hope this helps for anyone else who has troubles finding the documentation.

Angular JS - angular.forEach - How to get key of the object?

The first parameter to the iterator in forEach is the value and second is the key of the object.

angular.forEach(objectToIterate, function(value, key) {
    /* do something for all key: value pairs */

In your example, the outer forEach is actually:

angular.forEach($scope.filters, function(filterObj , filterKey)

How to select the first, second, or third element with a given class name?

This isn't so much an answer as a non-answer, i.e. an example showing why one of the highly voted answers above is actually wrong.

I thought that answer looked good. In fact, it gave me what I was looking for: :nth-of-type which, for my situation, worked. (So, thanks for that, @Bdwey.)

I initially read the comment by @BoltClock (which says that the answer is essentially wrong) and dismissed it, as I had checked my use case, and it worked. Then I realized @BoltClock had a reputation of 300,000+(!) and has a profile where he claims to be a CSS guru. Hmm, I thought, maybe I should look a little closer.

Turns out as follows: div.myclass:nth-of-type(2) does NOT mean "the 2nd instance of div.myclass". Rather, it means "the 2nd instance of div, and it must also have the 'myclass' class". That's an important distinction when there are intervening divs between your div.myclass instances.

It took me some time to get my head around this. So, to help others figure it out more quickly, I've written an example which I believe demonstrates the concept more clearly than a written description: I've hijacked the h1, h2, h3 and h4 elements to essentially be divs. I've put an A class on some of them, grouped them in 3's, and then colored the 1st, 2nd and 3rd instances blue, orange and green using h?.A:nth-of-type(?). (But, if you're reading carefully, you should be asking "the 1st, 2nd and 3rd instances of what?"). I also interjected a dissimilar (i.e. different h level) or similar (i.e. same h level) un-classed element into some of the groups.

Note, in particular, the last grouping of 3. Here, an un-classed h3 element is inserted between the first and second h3.A elements. In this case, no 2nd color (i.e. orange) appears, and the 3rd color (i.e. green) shows up on the 2nd instance of h3.A. This shows that the n in h3.A:nth-of-type(n) is counting the h3s, not the h3.As.

Well, hope that helps. And thanks, @BoltClock.

div {_x000D_
  margin-bottom: 2em;_x000D_
  border: red solid 1px;_x000D_
  background-color: lightyellow;_x000D_
h4 {_x000D_
  font-size: 12pt;_x000D_
  margin: 5px;_x000D_
h3.A:nth-of-type(1) {_x000D_
  background-color: cyan;_x000D_
h3.A:nth-of-type(2) {_x000D_
  background-color: orange;_x000D_
h3.A:nth-of-type(3) {_x000D_
  background-color: lightgreen;_x000D_
  <h1 class="A">h1.A #1</h1>_x000D_
  <h1 class="A">h1.A #2</h1>_x000D_
  <h1 class="A">h1.A #3</h1>_x000D_
  <h2 class="A">h2.A #1</h2>_x000D_
  <h4>this intervening element is a different type, i.e. h4 not h2</h4>_x000D_
  <h2 class="A">h2.A #2</h2>_x000D_
  <h2 class="A">h2.A #3</h2>_x000D_
  <h3 class="A">h3.A #1</h3>_x000D_
  <h3>this intervening element is the same type, i.e. h3, but has no class</h3>_x000D_
  <h3 class="A">h3.A #2</h3>_x000D_
  <h3 class="A">h3.A #3</h3>_x000D_

Extract MSI from EXE

7-Zip should do the trick.

With it, you can extract all the files inside the EXE (thus, also an MSI file).

Although you can do it with 7-Zip, the better way is the administrative installation as pointed out by Stein Åsmul.

Read SQL Table into C# DataTable

Here, give this a shot (this is just a pseudocode)

using System;
using System.Data;
using System.Data.SqlClient;

public class PullDataTest
    // your data table
    private DataTable dataTable = new DataTable();

    public PullDataTest()

    // your method to pull data from database to datatable   
    public void PullData()
        string connString = @"your connection string here";
        string query = "select * from table";

        SqlConnection conn = new SqlConnection(connString);        
        SqlCommand cmd = new SqlCommand(query, conn);

        // create data adapter
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        // this will query your database and return the result to your datatable

Returning a pointer to a vector element in c++

As long as your vector remains in global scope you can return:


I'll caution you that this is pretty dangerous in general. If your vector is ever moved out of global scope and is destructed, any pointers to myObject become invalid. If you're writing these functions as part of a larger project, returning a non-const pointer could lead someone to delete the return value. This will have undefined, and catastrophic, effects on the application.

I'd rewrite this as:

myObject myFunction(const vector<myObject>& objects)
    // find the object in question and return a copy
    return *iterator;

If you need to modify the returned myObject, store your values as pointers and allocate them on the heap:

myObject* myFunction(const vector<myObject*>& objects)
    return *iterator;

That way you have control over when they're destructed.

Something like this will break your app:

g_vector<tmpClass> myVector;

    tmpClass t;
    t.i = 30;

    // my function returns a pointer to a value in myVector
    std::auto_ptr<tmpClass> t2(myFunction());

Split a python list into other "sublists" i.e smaller lists

Actually I think using plain slices is the best solution in this case:

for i in range(0, len(data), 100):
    chunk = data[i:i + 100]

If you want to avoid copying the slices, you could use itertools.islice(), but it doesn't seem to be necessary here.

The itertools() documentation also contains the famous "grouper" pattern:

def grouper(n, iterable, fillvalue=None):
    "grouper(3, 'ABCDEFG', 'x') --> ABC DEF Gxx"
    args = [iter(iterable)] * n
    return izip_longest(fillvalue=fillvalue, *args)

You would need to modify it to treat the last chunk correctly, so I think the straight-forward solution using plain slices is preferable.

php/mySQL on XAMPP: password for phpMyAdmin and mysql_connect different?

if you open localhost/phpmyadmin you will find a tab called "User accounts". There you can define all your users that can access the mysql database, set their rights and even limit from where they can connect.

Why call git branch --unset-upstream to fixup?

TL;DR version: remote-tracking branch origin/master used to exist, but does not now, so local branch source is tracking something that does not exist, which is suspicious at best—it means a different Git feature is unable to do anything for you—and Git is warning you about it. You have been getting along just fine without having the "upstream tracking" feature work as intended, so it's up to you whether to change anything.

For another take on upstream settings, see Why do I have to "git push --set-upstream origin <branch>"?

This warning is a new thing in Git, appearing first in Git 1.8.5. The release notes contain just one short bullet-item about it:

  • "git branch -v -v" (and "git status") did not distinguish among a branch that is not based on any other branch, a branch that is in sync with its upstream branch, and a branch that is configured with an upstream branch that no longer exists.

To describe what it means, you first need to know about "remotes", "remote-tracking branches", and how Git handles "tracking an upstream". (Remote-tracking branches is a terribly flawed term—I've started using remote-tracking names instead, which I think is a slight improvement. Below, though, I'll use "remote-tracking branch" for consistency with Git documentation.)

Each "remote" is simply a name, like origin or octopress in this case. Their purpose is to record things like the full URL of the places from which you git fetch or git pull updates. When you use git fetch remote,1 Git goes to that remote (using the saved URL) and brings over the appropriate set of updates. It also records the updates, using "remote-tracking branches".

A "remote-tracking branch" (or remote-tracking name) is simply a recording of a branch name as-last-seen on some "remote". Each remote is itself a Git repository, so it has branches. The branches on remote "origin" are recorded in your local repository under remotes/origin/. The text you showed says that there's a branch named source on origin, and branches named 2.1, linklog, and so on on octopress.

(A "normal" or "local" branch, of course, is just a branch-name that you have created in your own repository.)

Last, you can set up a (local) branch to "track" a "remote-tracking branch". Once local branch L is set to track remote-tracking branch R, Git will call R its "upstream" and tell you whether you're "ahead" and/or "behind" the upstream (in terms of commits). It's normal (even recommend-able) for the local branch and remote-tracking branches to use the same name (except for the remote prefix part), like source and origin/source, but that's not actually necessary.

And in this case, that's not happening. You have a local branch source tracking a remote-tracking branch origin/master.

You're not supposed to need to know the exact mechanics of how Git sets up a local branch to track a remote one, but they are relevant below, so I'll show how this works. We start with your local branch name, source. There are two configuration entries using this name, spelled branch.source.remote and branch.source.merge. From the output you showed, it's clear that these are both set, so that you'd see the following if you ran the given commands:

$ git config --get branch.source.remote
$ git config --get branch.source.merge

Putting these together,2 this tells Git that your branch source tracks your "remote-tracking branch", origin/master.

But now look at the output of git branch -a, which shows all the local and remote-tracking branch names in your repository. The remote-tracking names are listed under remotes/ ... and there is no remotes/origin/master. Presumably there was, at one time, but it's gone now.

Git is telling you that you can remove the tracking information with --unset-upstream. This will clear out both branch.source.origin and branch.source.merge, and stop the warning.

It seems fairly likely that what you want, though, is to switch from tracking origin/master, to tracking something else: probably origin/source, but maybe one of the octopress/ names.

You can do this with git branch --set-upstream-to,3 e.g.:

$ git branch --set-upstream-to=origin/source

(assuming you're still on branch "source", and that origin/source is the upstream you want—there is no way for me to tell which one, if any, you actually want, though).

(See also How do you make an existing Git branch track a remote branch?)

I think the way you got here is that when you first did a git clone, the thing you cloned-from had a branch master. You also had a branch master, which was set to track origin/master (this is a normal, standard setup for git). This meant you had branch.master.remote and branch.master.merge set, to origin and refs/heads/master. But then your origin remote changed its name from master to source. To match, I believe you also changed your local name from master to source. This changed the names of your settings, from branch.master.remote to branch.source.remote and from branch.master.merge to branch.source.merge ... but it left the old values, so branch.source.merge was now wrong.

It was at this point that the "upstream" linkage broke, but in Git versions older than 1.8.5, Git never noticed the broken setting. Now that you have 1.8.5, it's pointing this out.

That covers most of the questions, but not the "do I need to fix it" one. It's likely that you have been working around the broken-ness for years now, by doing git pull remote branch (e.g., git pull origin source). If you keep doing that, it will keep working around the problem—so, no, you don't need to fix it. If you like, you can use --unset-upstream to remove the upstream and stop the complaints, and not have local branch source marked as having any upstream at all.

The point of having an upstream is to make various operations more convenient. For instance, git fetch followed by git merge will generally "do the right thing" if the upstream is set correctly, and git status after git fetch will tell you whether your repo matches the upstream one, for that branch.

If you want the convenience, re-set the upstream.

1git pull uses git fetch, and as of Git 1.8.4, this (finally!) also updates the "remote-tracking branch" information. In older versions of Git, the updates did not get recorded in remote-tracking branches with git pull, only with git fetch. Since your Git must be at least version 1.8.5 this is not an issue for you.

2Well, this plus a configuration line I'm deliberately ignoring that is found under remote.origin.fetch. Git has to map the "merge" name to figure out that the full local name for the remote-branch is refs/remotes/origin/master. The mapping almost always works just like this, though, so it's predictable that master goes to origin/master.

3Or, with git config. If you just want to set the upstream to origin/source the only part that has to change is branch.source.merge, and git config branch.source.merge refs/heads/source would do it. But --set-upstream-to says what you want done, rather than making you go do it yourself manually, so that's a "better way".

How to get the top position of an element?

If you want the position relative to the document then:


but often you will want the position relative to the closest positioned parent:


How do I run a file on localhost?

Ok, thanks for the more specific info, ppl may remove their downvotes now...

What you are proposing is a very common thing to do! You want to run your web application locally without uploading it to your host yet. That's totally fine and that's what your Apache is there for. Your Apache is a web server meaning its main purpose is to serve HTML, PHP, ASP, etc. files. Some like PHP; it first sends to the interpreter and then sends the rendered file to the browser. All in all: it's just serving pages to your browser (the client).

Your web server has a root directory which is wwwroot (IIS) or htdocs (apache, xampp) or something else like public_html, www or html, etc. It depends on your OS and web server.

Now if you type http://localhost into your browser, your browser will be directed to this webroot and the server will serve any index.html, index.php, etc. it can find there (in a customizable order).

If you have a project called "mytutorial" you can enter http://localhost/mytutorial and the server will show you the index-file of your tutorial, etc. If you look at the absolute path of this tutorial folder then it's just a subfolder of your webroot, which is itself located somewhere on your harddrive, but that doesn't matter for your localhost.

So the relative path is


while the absolute path may be




If you're working with Dreamweaver you can simplify the testing process by setting up your local server as a testing server in your project settings. Try it! It's easy. Once it's done, you can just press the browser icon with any of your files and it will open on localhost.

Powershell Get-ChildItem most recent file in directory

You could try to sort descending "sort LastWriteTime -Descending" and then "select -first 1." Not sure which one is faster

how to use php DateTime() function in Laravel 5

DateTime is not a function, but the class.

When you just reference a class like new DateTime() PHP searches for the class in your current namespace. However the DateTime class obviously doesn't exists in your controllers namespace but rather in root namespace.

You can either reference it in the root namespace by prepending a backslash:

$now = new \DateTime();

Or add an import statement at the top:

use DateTime;

$now = new DateTime();

Batch script to delete files

Consider that the files you need to delete have an extension txt and is located in the location D:\My Folder, then you could use the below code inside the bat file.

cd "D:\My Folder"
DEL *.txt 

How to run mysql command on bash?

This one worked, double quotes when $user and $password are outside single quotes. Single quotes when inside a single quote statement.

mysql --user="$user" --password="$password" --database="$user" --execute='DROP DATABASE '$user'; CREATE DATABASE '$user';'

How to get today's Date?

DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date date = new Date();

found here

Tree data structure in C#

I have added complete solution and example using NTree class above, also added "AddChild" method...

    public class NTree<T>
        public T data;
        public LinkedList<NTree<T>> children;

        public NTree(T data)
   = data;
            children = new LinkedList<NTree<T>>();

        public void AddChild(T data)
            var node = new NTree<T>(data) { Parent = this };

        public NTree<T> Parent { get; private set; }

        public NTree<T> GetChild(int i)
            foreach (NTree<T> n in children)
                if (--i == 0)
                    return n;
            return null;

        public void Traverse(NTree<T> node, TreeVisitor<T> visitor, string t, ref NTree<T> r)
            visitor(, node, t, ref r);
            foreach (NTree<T> kid in node.children)
                Traverse(kid, visitor, t, ref r);
    public static void DelegateMethod(KeyValuePair<string, string> data, NTree<KeyValuePair<string, string>> node, string t, ref NTree<KeyValuePair<string, string>> r)
        string a = string.Empty;
        if ( == t)
            r = node;


 NTree<KeyValuePair<string, string>> ret = null;
 tree.Traverse(tree, DelegateMethod, node["categoryId"].InnerText, ref ret);

Remove non-ASCII characters from CSV

sed -i 's/[^[:print:]]//' FILENAME

Also, this acts like dos2unix

Symbolicating iPhone App Crash Reports

Steps to analyze crash report from apple:

  1. Copy the release .app file which was pushed to the appstore, the .dSYM file that was created at the time of release and the crash report receive from APPLE into a FOLDER.

  2. OPEN terminal application and go to the folder created above (using cd command)

  3. Run atos -arch armv7 -o MEMORY_LOCATION_OF_CRASH. The memory location should be the one at which the app crashed as per the report.

Ex: atos -arch armv7 -o ''/'APPNAME' 0x0003b508

This would show you the exact line, method name which resulted in crash.

Ex: [classname functionName:]; -510

Symbolicating IPA

if we use IPA for symbolicating - just rename the extention .ipa with .zip , extract it then we can get a Payload Folder which contain app. In this case we don't need .dSYM file.


This can only work if the app binary does not have symbols stripped. By default release builds stripped the symbols. We can change it in project build settings "Strip Debug Symbols During Copy" to NO.

More details see this post

Parse string to date with moment.js

  • How to change any string date to object date (also with moment.js):

let startDate = "2019-01-16T20:00:00.000"; let endDate = "2019-02-11T20:00:00.000"; let sDate = new Date(startDate); let eDate = new Date(endDate);

  • with moment.js:

startDate = moment(sDate); endDate = moment(eDate);

How to randomly select rows in SQL?

Maybe this site will be of assistance.

For those who don't want to click through:

SELECT TOP 1 column FROM table

Selecting between two dates within a DateTime field - SQL Server

FROM tbl 
WHERE myDate BETWEEN #date one# AND #date two#;

XAMPP Object not found error

well, i had a similar problem, so when i entered, lets say: localhost/test.php I would got Object not found warning! I solved my problem when i realized that windows changed my test.php into this test.php.txt. I changed my extension and voila! problem solved I could finaly acceses localhost/test.php.

"Could not find a part of the path" error message

Is the drive E a mapped drive? Then, it can be created by another account other than the user account. This may be the cause of the error.

Make a div into a link

Came here in the hope of finding a better solution that mine, but I don't like any of the ones on offer here. I think some of you have misunderstood the question. The OP wants to make a div full of content behave like a link. One example of this would be facebook ads - if you look, they're actually proper markup.

For me the no-nos are: javascript (shouldn't be needed just for a link, and very bad SEO/accessibility); invalid HTML.

In essence it's this:

  • Build your panel using normal CSS techniques and valid HTML.
  • Somewhere in there put a link that you want to be the default link if the user clicks on the panel (you can have other links too).
  • Inside that link, put an empty span tag (<span></span>, not <span /> - thanks @Campey)
  • give the panel position:relative
  • apply the following CSS to the empty span:

      left: 0;
      z-index: 1;
      /* fixes overlap error in IE7/8, 
         make sure you have an empty gif */
      background-image: url('empty.gif');

    It will now cover the panel, and as it's inside an <A> tag, it's a clickable link

  • give any other links inside the panel position:relative and a suitable z-index (>1) to bring them in front of the default span link

IllegalStateException: Can not perform this action after onSaveInstanceState with ViewPager

Starting from support library version 24.0.0 you can call FragmentTransaction.commitNow() method which commits this transaction synchronously instead of calling commit() followed by executePendingTransactions(). As documentation says this approach even better:

Calling commitNow is preferable to calling commit() followed by executePendingTransactions() as the latter will have the side effect of attempting to commit all currently pending transactions whether that is the desired behavior or not.

How to read embedded resource text file

This is a class which you might find very convenient for reading embedded resource files from the current Assembly:

using System.IO;
using System.Linq;
using System.Text;

public static class EmbeddedResourceUtils
    public static string ReadFromResourceFile(string endingFileName)
        var assembly = Assembly.GetExecutingAssembly();
        var manifestResourceNames = assembly.GetManifestResourceNames();

        foreach (var resourceName in manifestResourceNames)
            var fileNameFromResourceName = _GetFileNameFromResourceName(resourceName);
            if (!fileNameFromResourceName.EndsWith(endingFileName))

            using (var manifestResourceStream = assembly.GetManifestResourceStream(resourceName))
                if (manifestResourceStream == null)

                using (var streamReader = new StreamReader(manifestResourceStream))
                    return streamReader.ReadToEnd();

        return null;
    private static string _GetFileNameFromResourceName(string resourceName)
        var stringBuilder = new StringBuilder();
        var escapeDot = false;
        var haveExtension = false;

        for (var resourceNameIndex = resourceName.Length - 1;
            resourceNameIndex >= 0;
            if (resourceName[resourceNameIndex] == '_')
                escapeDot = true;

            if (resourceName[resourceNameIndex] == '.')
                if (!escapeDot)
                    if (haveExtension)

                    haveExtension = true;
                escapeDot = false;


        var fileName = Path.GetDirectoryName(stringBuilder.ToString());
        return fileName == null ? null : new string(fileName.Reverse().ToArray());

How to add google-services.json in Android?

  1. Download the "google-service.json" file from Firebase
  2. Go to this address in windows explorer "C:\Users\Your-Username\AndroidStudioProjects" You will see a list of your Android Studio projects
  3. Open a desired project, navigate to "app" folder and paste the .json file
  4. Go to Android Studio and click on "Sync with file system", located in dropdown menu (File>Sync with file system)
  5. Now sync with Gradle and everything should be fine

Get Current Session Value in JavaScript?

I am using C# mvc Application. I have created a session in the Controller class like this

string description = accessDB.LookupSomeString(key, ImpDate);
this.Session["description"] = description;    

in the View, We access the session value and store it in a variable, like this (this is within an $.ajax, but I think it should work within any jquery)

var Sessiondescription = '@Session["description"]';

Vue.js : How to set a unique ID for each component instance?

Each component has a unique id which can be accessed as this._uid.

    <label :for="id">Label text for {{id}}</label>
    <input :id="id" type="text" />

export default {
  data () {
    return {
      id: null
  mounted () { = this._uid

If you want more control over the ids you can for example, generate them inside a parent component.

IN vs OR in the SQL WHERE Clause

The best way to find out is looking at the Execution Plan.

I tried it with Oracle, and it was exactly the same.

CREATE TABLE performance_test AS ( SELECT * FROM dba_objects );

SELECT * FROM performance_test

Even though the query uses IN, the Execution Plan says that it uses OR:

| Id  | Operation         | Name             | Rows  | Bytes | Cost (%CPU)| Time     |    
|   0 | SELECT STATEMENT  |                  |     8 |  1416 |   163   (2)| 00:00:02 |    
|*  1 |  TABLE ACCESS FULL| PERFORMANCE_TEST |     8 |  1416 |   163   (2)| 00:00:02 |    

Predicate Information (identified by operation id):                                       

   1 - filter("OBJECT_NAME"='DBMS_LOB' OR "OBJECT_NAME"='DBMS_REGISTRY' OR                

How to differ sessions in browser-tabs?

I've come up with a new solution, which has a tiny bit of overhead, but seems to be working so far as a prototype. One assumption is that you're in an honour system environment for logging in, although this could be adapted by rerequesting a password whenever you switch tabs.

Use localStorage (or equivalent) and the HTML5 storage event to detect when a new browser tab has switched which user is active. When that happens, create a ghost overlay with a message saying you can't use the current window (or otherwise disable the window temporarily, you might not want it to be this conspicuous.) When the window regains focus, send an AJAX request logging the user back in.

One caveat to this approach: you can't have any normal AJAX calls (i.e., ones that depend on your session) happen in a window that doesn't have the focus (e.g. if you had a call happening after a delay), unless you manually make an AJAX re-login call before that. So really all you need do is have your AJAX function check first to make sure localStorage.currently_logged_in_user_id === window.yourAppNameSpace.user_id, and if not, log in first via AJAX.

Another is race conditions: if you can switch windows fast enough to confuse it, you may end up with a relogin1->relogin2->ajax1->ajax2 sequence, with ajax1 being made under the wrong session. Work around this by pushing login AJAX requests onto an array, and then onstorage and before issuing a new login request, abort all current requests.

The last gotcha to look out for is window refreshes. If someone refreshes the window while you've got an AJAX login request active but not completed, it'll be refreshed in the name of the wrong person. In this case you can use the nonstandard beforeunload event to warn the user about the potential mixup and ask them to click Cancel, meanwhile reissuing an AJAX login request. Then the only way they can botch it is by clicking OK before the request completes (or by accidentally hitting enter/spacebar, because OK is--unfortunately for this case--the default.) There are other ways to handle this case, like detecting F5 and Ctrl+R/Alt+R presses, which will work in most cases but could be thwarted by user keyboard shortcut reconfiguration or alternative OS use. However, this is a bit of an edge case in reality, and the worst case scenarios are never that bad: in an honour system configuration, you'd be logged in as the wrong person (but you can make it obvious that this is the case by personalizing pages with colours, styles, prominently displayed names, etc.); in a password configuration, the onus is on the last person who entered their password to have logged out or shared their session, or if this person is actually the current user, then there's no breach.

But in the end you have a one-user-per-tab application that (hopefully) just acts as it should, without having to necessarily set up profiles, use IE, or rewrite URLs. Make sure you make it obvious in each tab who is logged into that particular tab, though...

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

>>> 2 == 2.0
>>> 2 is 2.0

Use ==

How to get an object's methods?

for me, the only reliable way to get the methods of the final extending class, was to do like this:

function getMethodsOf(obj){
  const methods = {}
  Object.getOwnPropertyNames( Object.getPrototypeOf(obj) ).forEach(methodName => {
    methods[methodName] = obj[methodName]
  return methods

What do 1.#INF00, -1.#IND00 and -1.#IND mean?

From IEEE floating-point exceptions in C++ :

This page will answer the following questions.

  • My program just printed out 1.#IND or 1.#INF (on Windows) or nan or inf (on Linux). What happened?
  • How can I tell if a number is really a number and not a NaN or an infinity?
  • How can I find out more details at runtime about kinds of NaNs and infinities?
  • Do you have any sample code to show how this works?
  • Where can I learn more?

These questions have to do with floating point exceptions. If you get some strange non-numeric output where you're expecting a number, you've either exceeded the finite limits of floating point arithmetic or you've asked for some result that is undefined. To keep things simple, I'll stick to working with the double floating point type. Similar remarks hold for float types.

Debugging 1.#IND, 1.#INF, nan, and inf

If your operation would generate a larger positive number than could be stored in a double, the operation will return 1.#INF on Windows or inf on Linux. Similarly your code will return -1.#INF or -inf if the result would be a negative number too large to store in a double. Dividing a positive number by zero produces a positive infinity and dividing a negative number by zero produces a negative infinity. Example code at the end of this page will demonstrate some operations that produce infinities.

Some operations don't make mathematical sense, such as taking the square root of a negative number. (Yes, this operation makes sense in the context of complex numbers, but a double represents a real number and so there is no double to represent the result.) The same is true for logarithms of negative numbers. Both sqrt(-1.0) and log(-1.0) would return a NaN, the generic term for a "number" that is "not a number". Windows displays a NaN as -1.#IND ("IND" for "indeterminate") while Linux displays nan. Other operations that would return a NaN include 0/0, 0*8, and 8/8. See the sample code below for examples.

In short, if you get 1.#INF or inf, look for overflow or division by zero. If you get 1.#IND or nan, look for illegal operations. Maybe you simply have a bug. If it's more subtle and you have something that is difficult to compute, see Avoiding Overflow, Underflow, and Loss of Precision. That article gives tricks for computing results that have intermediate steps overflow if computed directly.

Combining (concatenating) date and time into a datetime

I am using SQL Server 2016 and both myDate and myTime fields are strings. The below tsql statement worked in concatenating them into datetime

select cast((myDate + ' ' + myTime) as datetime) from myTable

How to implement common bash idioms in Python?

I have published a package on PyPI: ez.
Use pip install ez to install it.

It has packed common commands in shell and nicely my lib uses basically the same syntax as shell. e.g., cp(source, destination) can handle both file and folder! (wrapper of shutil.copy shutil.copytree and it decides when to use which one). Even more nicely, it can support vectorization like R!

Another example: no os.walk, use fls(path, regex) to recursively find files and filter with regular expression and it returns a list of files with or without fullpath

Final example: you can combine them to write very simply scripts:
files = fls('.','py$'); cp(files, myDir)

Definitely check it out! It has cost me hundreds of hours to write/improve it!

incompatible character encodings: ASCII-8BIT and UTF-8

The problem was the use of incorrect quotes around the iOS version. Make sure all your quotes are ' and not ‘ or ’.

Angular2 @Input to a property with get/set

If you are mainly interested in implementing logic to the setter only:

import { Component, Input, OnChanges, SimpleChanges } from '@angular/core';

// [...]

export class MyClass implements OnChanges {
  @Input() allowDay: boolean;

  ngOnChanges(changes: SimpleChanges): void {
    if(changes['allowDay']) {

The import of SimpleChanges is not needed if it doesn't matter which input property was changed or if you have only one input property.

Angular Doc: OnChanges


private _allowDay: boolean;

@Input() set allowDay(value: boolean) {
  this._allowDay = value;
get allowDay(): boolean {
  // other logic
  return this._allowDay;

How to install mysql-connector via pip

pip install mysql-connector

Last but not least,You can also install mysql-connector via source code

Download source code from:

How do I close an open port from the terminal on the Mac?

To find the process try:

sudo lsof -i :portNumber

Kill the process which is currently using the port using its PID

kill PID

and then check to see if the port closed. If not, try:

kill -9 PID

I would only do the following if the previous didnt work

sudo kill -9 PID

Just to be safe. Again depending on how you opened the port, this may not matter.

How can I return pivot table output in MySQL?

A stardard-SQL version using boolean logic:

SELECT company_name
     , COUNT(action = 'EMAIL' OR NULL) AS "Email"
     , COUNT(action = 'PRINT' AND pagecount = 1 OR NULL) AS "Print 1 pages"
     , COUNT(action = 'PRINT' AND pagecount = 2 OR NULL) AS "Print 2 pages"
     , COUNT(action = 'PRINT' AND pagecount = 3 OR NULL) AS "Print 3 pages"
FROM   tbl
GROUP  BY company_name;

SQL Fiddle.


And COUNT only counts non-null values. Voilá.

How to replace � in a string

Change the Encoding to UTF-8 while parsing .This will remove the special characters

No module named pkg_resources

It also happened to me. I think the problem will happen if the requirements.txt contains a "distribute" entry while the virtualenv uses setuptools. Pip will try to patch setuptools to make room for distribute, but unfortunately it will fail half way.

The easy solution is delete your current virtualenv then make a new virtualenv with --distribute argument.

An example if using virtualenvwrapper:

$ deactivate
$ rmvirtualenv yourenv
$ mkvirtualenv yourenv --distribute
$ workon yourenv
$ pip install -r requirements.txt

Could not load file or assembly 'System.Web.WebPages.Razor, Version=

After much pain, googling and hair pulling, I ended up uninstalling MVC 4 using nuget, deleting all references to MVC, razor and infrastructure from the web config, deleting the dlls from the bin folder - then using nuget to reinstall everything. It took less time then trying to figure out why the dlls did not match.

How to select specific columns in laravel eloquent

If you want to get a single value from Database

    Model::where('id', 1)->value('name')

Vertical align middle with Bootstrap responsive grid

Add !important rule to display: table of your .v-center class.

.v-center {
    display:table !important;
    border:2px solid gray;

Your display property is being overridden by bootstrap to display: block.


How to enable CORS on Firefox?

It's only possible when the server sends this header: Access-Control-Allow-Origin: *

If this is your code then you can setup it like this (PHP):

header('Access-Control-Allow-Origin: *');

How do I display local image in markdown?

Solution for Unix-like operating system.

  1. Create a directory named like Images and put all the images that will be rendered by the Markdown.

  2. For example, put example.png into Images.

  3. To load example.png that was located under the Images directory before.


Note : Images directory must be located under the same directory of your markdown text file which has .md extension.

SQL Server Text type vs. varchar data type

If you're using SQL Server 2005 or later, use varchar(MAX). The text datatype is deprecated and should not be used for new development work. From the docs:


ntext , text, and image data types will be removed in a future version of Microsoft SQL Server. Avoid using these data types in new development work, and plan to modify applications that currently use them. Use nvarchar(max), varchar(max), and varbinary(max) instead.

Remove a file from the list that will be committed

You want to do this:

git add -u
git reset HEAD path/to/file
git commit

Be sure and do this from the top level of the repo; add -u adds changes in the current directory (recursively).

The key line tells git to reset the version of the given path in the index (the staging area for the commit) to the version from HEAD (the currently checked-out commit).

And advance warning of a gotcha for others reading this: add -u stages all modifications, but doesn't add untracked files. This is the same as what commit -a does. If you want to add untracked files too, use add . to recursively add everything.

Purpose of returning by const value?

It could be used as a wrapper function for returning a reference to a private constant data type. For example in a linked list you have the constants tail and head, and if you want to determine if a node is a tail or head node, then you can compare it with the value returned by that function.

Though any optimizer would most likely optimize it out anyway...

Align two inline-blocks left and right on same line

give it float: right and the h1 float:left and put an element with clear:both after them.

How to insert selected columns from a CSV file to a MySQL database using LOAD DATA INFILE

For those who have the following error:

Error Code: 1290. The MySQL server is running with the --secure-file-priv option so it cannot execute this statement

You can simply run this command to see which folder can load files from:

SHOW VARIABLES LIKE "secure_file_priv";

After that, you have to copy the files in that folder and run the query with LOAD DATA LOCAL INFILE instead of LOAD DATA INFILE.

Replacing blank values (white space) with NaN in pandas

This is not an elegant solution, but what does seem to work is saving to XLSX and then importing it back. The other solutions on this page did not work for me, unsure why.

data.to_excel(filepath, index=False)
data = pd.read_excel(filepath)

How to get height of <div> in px dimension

For those looking for a plain JS solution:

let el = document.querySelector("#myElementId");

// including the element's border
let width = el.offsetWidth;
let height = el.offsetHeight;

// not including the element's border:
let width = el.clientWidth;
let height = el.clientHeight;

Check out this article for more details.

How to increase heap size for jBoss server

Edit the following entry in the run.conf file. But if you have multiple JVMs running on the same JBoss, you might want to run it via command line argument of -Xms2g -Xmx4g (or whatever your preferred start/max memory settings are.

if [ "x$JAVA_OPTS" = "x" ]; then
    JAVA_OPTS="-Xms2g -Xmx4g -XX:MaxPermSize=256m -Dorg.jboss.resolver.warning=true

select count(*) from select

You're missing a FROM and you need to give the subquery an alias.

  SELECT DISTINCT a.my_id, a.last_name, a.first_name, b.temp_val
   FROM dbo.Table_A AS a 
   INNER JOIN dbo.Table_B AS b 
   ON a.a_id = b.a_id
) AS subquery;

Add new column in Pandas DataFrame Python

The easiest way that I found for adding a column to a DataFrame was to use the "add" function. Here's a snippet of code, also with the output to a CSV file. Note that including the "columns" argument allows you to set the name of the column (which happens to be the same as the name of the np.array that I used as the source of the data).

#  now to create a PANDAS data frame
df = pd.DataFrame(data = FF_maxRSSBasal, columns=['FF_maxRSSBasal'])
# from here on, we use the trick of creating a new dataframe and then "add"ing it
df2 = pd.DataFrame(data = FF_maxRSSPrism, columns=['FF_maxRSSPrism'])
df = df.add( df2, fill_value=0 )
df2 = pd.DataFrame(data = FF_maxRSSPyramidal, columns=['FF_maxRSSPyramidal'])
df = df.add( df2, fill_value=0 )
df2 = pd.DataFrame(data = deltaFF_strainE22, columns=['deltaFF_strainE22'])
df = df.add( df2, fill_value=0 )
df2 = pd.DataFrame(data = scaled, columns=['scaled'])
df = df.add( df2, fill_value=0 )
df2 = pd.DataFrame(data = deltaFF_orientation, columns=['deltaFF_orientation'])
df = df.add( df2, fill_value=0 )

sqlite3.OperationalError: unable to open database file

I had this problem serving with Apache and found that using the absolute path to the sqlite3 db in my .env //// as opposed to using the relative path /// fixed the problem. All of the permissions and ownership mentioned above are necessary as well.

DISTINCT for only one column

This assumes SQL Server 2005+ and your definition of "last" is the max PK for a given email

FROM   Products
WHERE RowNumber = 1

Can I inject a service into a directive in AngularJS?

You can do injection on Directives, and it looks just like it does everywhere else.

app.directive('changeIt', ['myData', function(myData){
    return {
        restrict: 'C',
        link: function (scope, element, attrs) {

Excel Validation Drop Down list using VBA

You are defining your array as xlValidateList(), so when you try to assign the type, it gets confused as to what you are trying to assign to the type.

Instead, try this:

Dim MyList(5) As String
MyList(0) = 1
MyList(1) = 2
MyList(2) = 3
MyList(3) = 4
MyList(4) = 5
MyList(5) = 6

With Range("A1").Validation
    .Add Type:=xlValidateList, AlertStyle:=xlValidAlertStop, _
         Operator:=xlBetween, Formula1:=Join(MyList, ",")
End With

basic authorization command for curl

One way, provide --user flag as part of curl, as follows:

curl --user username:password

Another way is to get Base64 encoded token of "username:password" from any online website like - and pass it as Authorization header of curl as follows:

curl -i -H 'Authorization:Basic dXNlcm5hbWU6cGFzc3dvcmQ=' http://localhost:8080/

Here, dXNlcm5hbWU6cGFzc3dvcmQ= is Base64 encoded token of username:password.

No module named MySQLdb

If you are running on Vista, you may want to check out the Bitnami Django stack. It is an all-in-one stack of Apache, Python, MySQL, etc. packaged with Bitrock crossplatform installers to make it really easy to get started. It runs on Windows, Mac and Linux. Oh, and is completely free :)

Installing a specific version of angular with angular cli

Use the following command to install and downgrade the specific version.
uninstall cli

npm uninstall -g @angular/cli

clean npm cache

 npm cache clean --force

install cli

npm install -g @angular/cli@_choose_your_version

Checking if a collection is null or empty in Groovy

FYI this kind of code works (you can find it ugly, it is your right :) ) :

def list = null
list.each { println it }

In other words, this code has null/empty checks both useless:

if (members && !members.empty) {
    members.each { doAnotherThing it }

def doAnotherThing(def member) {
  // Some work

jQuery or JavaScript auto click

You are trying to make a popup work maybe? I don't know how to emulate click, maybe you can try to fire click event somehow, but I don't know if it is possible. More than likely such functionality is not implemented, because of security and privacy concerns.

You can use div with position:absolute to emulate popup at the same page. If you insist creating another page, I cannot help you. Maybe somebody else with more experience will add his 15 cents.

Convert date to another timezone in JavaScript

Got it !

Wanted to force the date shown = server date, no mattter the local settings (UTC).

My server is GMT-6 --> new Date().getTimezoneOffset() = 360.

myTZO = 360;
myNewDate=new Date(myOldDateObj.getTime() + (60000*(myOldDateObj.getTimezoneOffset()-myTZO)));

How to use Redirect in the new react-router-dom of Reactjs

The problem I run into is I have an existing IIS machine. I then deploy a static React app to it. When you use router, the URL that displays is actually virtual, not real. If you hit F5 it goes to IIS, not index.js, and your return will be 404 file not found. How I resolved it was simple. I have a public folder in my react app. In that public folder I created the same folder name as the virtual routing. In this folder, I have an index.html with the following code:

    localStorage.setItem("redirect", "/ansible/");
    location.href = "/";

Now what this does is for this session, I'm adding the "routing" path I want it to go. Then inside my App.js I do this (Note ... is other code but too much to put here for a demo):

import React, { Component } from "react";
import { Route, Link } from "react-router-dom";
import { BrowserRouter as Router } from "react-router-dom";
import { Redirect } from 'react-router';
import Ansible from "./Development/Ansible";
import Code from "./Development/Code";
import Wood from "./WoodWorking";
import "./App.css";

class App extends Component {
  render() {
    const redirect = localStorage.getItem("redirect");

    if(redirect) {

    return (
        {redirect ?<Redirect to={redirect}/> : ""}
        <div className="App">
          <Link to="/">
          <Link to="/dev">
          <Link to="/wood">
            <li>Wood Working</li>
            render={(props) => (
              <Home {...props} />
            render={(props) => (
              <Code {...props} />
            render={(props) => (
              <Wood {...props} />
            render={(props) => (
              <Ansible {...props} checked={this.state.checked} />

export default App;

Actual usage:

How to make a Java thread wait for another thread's output?

A lot of correct answers but without a simple example.. Here is an easy and simple way how to use CountDownLatch:

//inside your currentThread.. lets call it Thread_Main
final CountDownLatch latch = new CountDownLatch(1);

// launch thread#2
new Thread(new Runnable() {
    public void run() {
        //do your logic here in thread#2

        //then release the lock

try {
    //3 this method will block the thread of latch untill its released later from thread#2
} catch (InterruptedException e) {

// You reach here after  latch.countDown() is called from thread#2

Set CFLAGS and CXXFLAGS options using CMake

The easiest solution working fine for me is this:

export CFLAGS=-ggdb
export CXXFLAGS=-ggdb

CMake will append them to all configurations' flags. Just make sure to clear CMake cache.

Java Embedded Databases Comparison

I realize you mentioned SQL browsing, but everything else in your question makes me want to suggest you also consider DB4O, which is a great, simple object DB.

How to remove all duplicate items from a list

The modern way to do it that maintains the order is:

>>> from collections import OrderedDict
>>> list(OrderedDict.fromkeys(lseparatedOrbList))

as discussed by Raymond Hettinger (python core dev) in this answer. In python 3.5 and above this is also the fastest way - see the linked answer for details. However the keys must be hashable (as is the case in your list I think)

Add leading zeroes to number in Java?

Another option is to use DecimalFormat to format your numeric String. Here is one other way to do the job without having to use String.format if you are stuck in the pre 1.5 world:

static String intToString(int num, int digits) {
    assert digits > 0 : "Invalid number of digits";

    // create variable length array of zeros
    char[] zeros = new char[digits];
    Arrays.fill(zeros, '0');
    // format number as String
    DecimalFormat df = new DecimalFormat(String.valueOf(zeros));

    return df.format(num);

Insert/Update Many to Many Entity Framework . How do I do it?

I use the following way to handle the many-to-many relationship where only foreign keys are involved.

So for inserting:

public void InsertStudentClass (long studentId, long classId)
    using (var context = new DatabaseContext())
        Student student = new Student { StudentID = studentId };

        Class class = new Class { ClassID = classId };

        student.Classes = new List<Class>();


For deleting,

public void DeleteStudentClass(long studentId, long classId)
    Student student = context.Students.Include(x => x.Classes).Single(x => x.StudentID == studentId);

    using (var context = new DatabaseContext())
        Class classToDelete = student.Classes.Find(x => x.ClassID == classId);
        if (classToDelete != null)

CSS3 Continuous Rotate Animation (Just like a loading sundial)

Your issue here is that you've supplied a -webkit-TRANSITION-timing-function when you want a -webkit-ANIMATION-timing-function. Your values of 0 to 360 will work properly.

WordPress is giving me 404 page not found for all pages except the homepage

Just Navigate to Settings->Permalink in your dashboard and then Save Changes button in the last.\

How to get child element by ID in JavaScript?

Using jQuery

$('#note textarea');

or just


How do I get a list of all the duplicate items using pandas in python?

Using an element-wise logical or and setting the take_last argument of the pandas duplicated method to both True and False you can obtain a set from your dataframe that includes all of the duplicates.

df_bigdata_duplicates = 
    df_bigdata[df_bigdata.duplicated(cols='ID', take_last=False) |
               df_bigdata.duplicated(cols='ID', take_last=True)

Mean of a column in a data frame, given the column's name

I think you're asking how to compute the mean of a variable in a data frame, given the name of the column. There are two typical approaches to doing this, one indexing with [[ and the other indexing with [:

# [1] 3.758
# [1] 3.758
# [1] 3.057333
# [1] 3.057333

repaint() in Java

Simply write :


That will do .


Entity Framework and SQL Server View

The current Entity Framework EDM generator will create a composite key from all non-nullable fields in your view. In order to gain control over this, you will need to modify the view and underlying table columns setting the columns to nullable when you do not want them to be part of the primary key. The opposite is also true, as I encountered, the EDM generated key was causing data-duplication issues, so I had to define a nullable column as non-nullable to force the composite key in the EDM to include that column.

Convert from lowercase to uppercase all values in all character variables in dataframe

From the dplyr package you can also use the mutate_all() function in combination with toupper(). This will affect both character and factor classes.

df <- mutate_all(df, funs=toupper)

Determine if Android app is being used for the first time

Hi guys I am doing something like this. And its works for me

create a Boolean field in shared preference.Default value is true {isFirstTime:true} after first time set it to false. Nothing can be simple and relaiable than this in android system.

Ignore python multiple return value

The best solution probably is to name things instead of returning meaningless tuples (unless there is some logic behind the order of the returned items). You can for example use a dictionary:

def func():
    return {'lat': 1, 'lng': 2}
latitude = func()['lat']

You could even use namedtuple if you want to add extra information about what you are returning (it's not just a dictionary, it's a pair of coordinates):

from collections import namedtuple 

Coordinates = namedtuple('Coordinates', ['lat', 'lng'])

def func():
    return Coordinates(lat=1, lng=2)

latitude = func().lat

If the objects within your dictionary/tuple are strongly tied together then it may be a good idea to even define a class for it. That way you'll also be able to define more complex operations. A natural question that follows is: When should I be using classes in Python?

Most recent versions of python (= 3.7) have dataclasses which you can use to define classes with very few lines of code:

from dataclasses import dataclass

class Coordinates:
    lat: float = 0
    lng: float = 0

def func():
    return Coordinates(lat=1, lng=2)

latitude = func().lat

The primary advantage of dataclasses over namedtuple is that its easier to extend, but there are other differences. Note that by default, dataclasses are mutable, but you can use @dataclass(frozen=True) instead of @dataclass to force them being immutable.

hadoop copy a local file system folder to HDFS

In Short

hdfs dfs -put <localsrc> <dest>

In detail with example:

Checking source and target before placing files into HDFS

[cloudera@quickstart ~]$ ll files/
total 132
-rwxrwxr-x 1 cloudera cloudera  5387 Nov 14 06:33 cloudera-manager
-rwxrwxr-x 1 cloudera cloudera  9964 Nov 14 06:33
-rw-rw-r-- 1 cloudera cloudera   664 Nov 14 06:33 derby.log
-rw-rw-r-- 1 cloudera cloudera 53655 Nov 14 06:33 enterprise-deployment.json
-rw-rw-r-- 1 cloudera cloudera 50515 Nov 14 06:33 express-deployment.json

[cloudera@quickstart ~]$ hdfs dfs -ls
Found 1 items
drwxr-xr-x   - cloudera cloudera          0 2017-11-14 00:45 .sparkStaging

Copy files HDFS using -put or -copyFromLocal command

[cloudera@quickstart ~]$ hdfs dfs -put files/ files

Verify the result in HDFS

[cloudera@quickstart ~]$ hdfs dfs -ls
Found 2 items
drwxr-xr-x   - cloudera cloudera          0 2017-11-14 00:45 .sparkStaging
drwxr-xr-x   - cloudera cloudera          0 2017-11-14 06:34 files

[cloudera@quickstart ~]$ hdfs dfs -ls files
Found 5 items
-rw-r--r--   1 cloudera cloudera       5387 2017-11-14 06:34 files/cloudera-manager
-rw-r--r--   1 cloudera cloudera       9964 2017-11-14 06:34 files/
-rw-r--r--   1 cloudera cloudera        664 2017-11-14 06:34 files/derby.log
-rw-r--r--   1 cloudera cloudera      53655 2017-11-14 06:34 files/enterprise-deployment.json
-rw-r--r--   1 cloudera cloudera      50515 2017-11-14 06:34 files/express-deployment.json

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

For windows you can do it like

"scripts": {
    "start:prod" : "SET NODE_ENV=production & nodemon app.js",
    "start:dev" : "SET NODE_ENV=development & nodemon app.js"

How to get param from url in angular 4?

constructor(private activatedRoute: ActivatedRoute) {

ngOnInit() {
    this.activatedRoute.params.subscribe(paramsId => { =;

How can I programmatically freeze the top row of an Excel worksheet in Excel 2007 VBA?

ActiveWindow.FreezePanes = True

This is the easiest way to freeze the top row. The rule for FreezePanes is it will freeze the upper left corner from the cell you selected. For example, if you highlight C10, it will freeze between columns B and C, rows 9 and 10. So when you highlight Row 2, it actually freeze between Rows 1 and 2 which is the top row.

Also, the .SplitColumn or .SplitRow will split your window once you unfreeze it which is not the way I like.

What is the list of valid @SuppressWarnings warning names in Java?

I just want to add that there is a master list of IntelliJ suppress parameters at:

It looks fairly comprehensive. Partial:

Warning Description - Warning Name

"Magic character" MagicCharacter 
"Magic number" MagicNumber 
'' method does not use parameter ComparatorMethodParameterNotUsed 
'Connection.prepare*()' call with non-constant string JDBCPrepareStatementWithNonConstantString 
'Iterator.hasNext()' which calls 'next()' IteratorHasNextCallsIteratorNext 
'' which can't throw 'NoSuchElementException' IteratorNextCanNotThrowNoSuchElementException 
'Statement.execute()' call with non-constant string JDBCExecuteWithNonConstantString 
'String.equals("")' StringEqualsEmptyString 
'StringBuffer' may be 'StringBuilder' (JDK 5.0 only) StringBufferMayBeStringBuilder 
'StringBuffer.toString()' in concatenation StringBufferToStringInConcatenation 
'assert' statement AssertStatement 
'assertEquals()' between objects of inconvertible types AssertEqualsBetweenInconvertibleTypes 
'await()' not in loop AwaitNotInLoop 
'await()' without corresponding 'signal()' AwaitWithoutCorrespondingSignal 
'break' statement BreakStatement 
'break' statement with label BreakStatementWithLabel 
'catch' generic class CatchGenericClass 
'clone()' does not call 'super.clone()' CloneDoesntCallSuperClone

Load arrayList data into JTable

"The problem is that i cant find a way to set a fixed number of rows"

You don't need to set the number of rows. Use a TableModel. A DefaultTableModel in particular.

String col[] = {"Pos","Team","P", "W", "L", "D", "MP", "GF", "GA", "GD"};

DefaultTableModel tableModel = new DefaultTableModel(col, 0);
                                            // The 0 argument is number rows.

JTable table = new JTable(tableModel);

Then you can add rows to the tableModel with an Object[]

Object[] objs = {1, "Arsenal", 35, 11, 2, 2, 15, 30, 11, 19};


You can loop to add your Object[] arrays.

Note: JTable does not currently allow instantiation with the input data as an ArrayList. It must be a Vector or an array.

See JTable and DefaultTableModel. Also, How to Use JTable tutorial

"I created an arrayList from it and I somehow can't find a way to store this information into a JTable."

You can do something like this to add the data

ArrayList<FootballClub> originalLeagueList = new ArrayList<FootballClub>();

originalLeagueList.add(new FootballClub(1, "Arsenal", 35, 11, 2, 2, 15, 30, 11, 19));
originalLeagueList.add(new FootballClub(2, "Liverpool", 30, 9, 3, 3, 15, 34, 18, 16));
originalLeagueList.add(new FootballClub(3, "Chelsea", 30, 9, 2, 2, 15, 30, 11, 19));
originalLeagueList.add(new FootballClub(4, "Man City", 29, 9, 2, 4, 15, 41, 15, 26));
originalLeagueList.add(new FootballClub(5, "Everton", 28, 7, 1, 7, 15, 23, 14, 9));
originalLeagueList.add(new FootballClub(6, "Tottenham", 27, 8, 4, 3, 15, 15, 16, -1));
originalLeagueList.add(new FootballClub(7, "Newcastle", 26, 8, 5, 2, 15, 20, 21, -1));
originalLeagueList.add(new FootballClub(8, "Southampton", 23, 6, 4, 5, 15, 19, 14, 5));

for (int i = 0; i < originalLeagueList.size(); i++){
   int position = originalLeagueList.get(i).getPosition();
   String name = originalLeagueList.get(i).getName();
   int points = originalLeagueList.get(i).getPoinst();
   int wins = originalLeagueList.get(i).getWins();
   int defeats = originalLeagueList.get(i).getDefeats();
   int draws = originalLeagueList.get(i).getDraws();
   int totalMatches = originalLeagueList.get(i).getTotalMathces();
   int goalF = originalLeagueList.get(i).getGoalF();
   int goalA = originalLeagueList.get(i).getGoalA();
   in ttgoalD = originalLeagueList.get(i).getTtgoalD();

   Object[] data = {position, name, points, wins, defeats, draws, 
                               totalMatches, goalF, goalA, ttgoalD};



How to use PDO to fetch results array in PHP?

There are three ways to fetch multiple rows returned by PDO statement.

The simplest one is just to iterate over PDOStatement itself:

$stmt = $pdo->prepare("SELECT * FROM auction WHERE name LIKE ?")
// iterating over a statement
foreach($stmt as $row) {
    echo $row['name'];

another one is to fetch rows using fetch() method inside a familiar while statement:

$stmt = $pdo->prepare("SELECT * FROM auction WHERE name LIKE ?")
// using while
while($row = $stmt->fetch()) {
    echo $row['name'];

but for the modern web application we should have our datbase iteractions separated from output and thus the most convenient method would be to fetch all rows at once using fetchAll() method:

$stmt = $pdo->prepare("SELECT * FROM auction WHERE name LIKE ?")
// fetching rows into array
$data = $stmt->fetchAll();

or, if you need to preprocess some data first, use the while loop and collect the data into array manually

$result = [];
$stmt = $pdo->prepare("SELECT * FROM auction WHERE name LIKE ?")
// using while
while($row = $stmt->fetch()) {
    $result[] = [
        'newname' => $row['oldname'],
        // etc

and then output them in a template:

<?php foreach($data as $row): ?>
<?php endforeach ?>

Note that PDO supports many sophisticated fetch modes, allowing fetchAll() to return data in many different formats.

How to cast/convert pointer to reference in C++


You don't need to cast it because it's the same Object type, you just need to dereference it.

CS1617: Invalid option ‘6’ for /langversion; must be ISO-1, ISO-2, 3, 4, 5 or Default

Instead of changing the language version from 6 to 5, change the "type" attribute on the compiler tag from

Microsoft.CSharp.CSharpCodeProvider, System, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089


Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=, Culture=neutral, PublicKeyToken=31bf3856ad364e35

How to upload a file and JSON data in Postman?

If you need like Upload file in multipart using form data and send json data(Dto object) in same POST Request

Get yor JSON object as String in Controller and make it Deserialize by adding this line

ContactDto contactDto  = new ObjectMapper().readValue(yourJSONString, ContactDto.class);

Parsing PDF files (especially with tables) with PDFBox

You can use PDFBox's PDFTextStripperByArea class to extract text from a specific region of a document. You can build on this by identifying the region each cell of the table. This isn't provided out of the box, but the example DrawPrintTextLocations class demonstrates how you can parse the bounding boxes of individual characters in a document (it would be great to parse bounding boxes of strings or paragraphs, but I haven't seen support in PDFBox for this - see this question). You can use this approach to group up all touching bounding boxes to identify distinct cells of a table. One way to do this is to maintain a set boxes of Rectangle2D regions and then for each parsed character find the character's bounding box as in DrawPrintTextLocations.writeString(String string, List<TextPosition> textPositions) and merge it with the existing contents.

Rectangle2D bounds = s.getBounds2D();
// Pad sides to detect almost touching boxes
Rectangle2D hitbox = bounds.getBounds2D();
final double dx = 1.0; // This value works for me, feel free to tweak (or add setter)
final double dy = 0.000; // Rows of text tend to overlap, so no need to extend
hitbox.add(bounds.getMinX() - dx , bounds.getMinY() - dy);
hitbox.add(bounds.getMaxX() + dx , bounds.getMaxY() + dy);

// Find all overlapping boxes
List<Rectangle2D> intersectList = new ArrayList<Rectangle2D>();
for(Rectangle2D box: boxes) {
    if(box.intersects(hitbox)) {

// Combine all touching boxes and update
for(Rectangle2D box: intersectList) {

You can then pass these regions to PDFTextStripperByArea.

You can also go one further and separate out the horizontal and vertical components of these regions, and so infer regions of all the table's cells, regardless of whether then hold any content.

I have had cause to perform these steps, and eventually wrote my own PDFTableStripper class using PDFBox. I've shared my code as a gist on GitHub. The main method gives an example of how the class can be used:

try (PDDocument document = PDDocument.load(new File(args[0])))
    final double res = 72; // PDF units are at 72 DPI
    PDFTableStripper stripper = new PDFTableStripper();

    // Choose a region in which to extract a table (here a 6"wide, 9" high rectangle offset 1" from top left of page)
    stripper.setRegion(new Rectangle(
        (int) Math.round(1.0*res), 
        (int) Math.round(1*res), 
        (int) Math.round(6*res), 
        (int) Math.round(9.0*res)));

    // Repeat for each page of PDF
    for (int page = 0; page < document.getNumberOfPages(); ++page)
        System.out.println("Page " + page);
        PDPage pdPage = document.getPage(page);
        for(int c=0; c<stripper.getColumns(); ++c) {
            System.out.println("Column " + c);
            for(int r=0; r<stripper.getRows(); ++r) {
                System.out.println("Row " + r);
                System.out.println(stripper.getText(r, c));

How to toggle a boolean?

If you don't mind the boolean being converted to a number (that is either 0 or 1), you can use the Bitwise XOR Assignment Operator. Like so:

bool ^= true;   //- toggle value.

This is especially good if you use long, descriptive boolean names, EG:

var inDynamicEditMode   = true;     // Value is: true (boolean)
inDynamicEditMode      ^= true;     // Value is: 0 (number)
inDynamicEditMode      ^= true;     // Value is: 1 (number)
inDynamicEditMode      ^= true;     // Value is: 0 (number)

This is easier for me to scan than repeating the variable in each line.

This method works in all (major) browsers (and most programming languages).

How can I tell when a MySQL table was last updated?

Just grab the file date modified from file system. In my language that is:

 tbl_updated = file.update_time(
        "C:\ProgramData\MySQL\MySQL Server 5.5\data\mydb\person.frm")


1/25/2013 06:04:10 AM

SELECT data from another schema in oracle

Depending on the schema/account you are using to connect to the database, I would suspect you are missing a grant to the account you are using to connect to the database.

Connect as PCT account in the database, then grant the account you are using select access for the table.

grant select on pi_int to Account_used_to_connect

Using "&times" word in html changes to ×

You need to escape:

<div class="test">&amp;times</div>

And then read the value using text() to get the unescaped value:

alert($(".test").text()); // outputs: &times

How create table only using <div> tag and Css

I don't see any answer considering Grid-Css. I think it is a very elegant approach: grid-css even supports row span and and column spans. Here you can find a very good article:

SQL Server: Get data for only the past year

argument for DATEADD function :

DATEADD (*datepart* , *number* , *date* )

datepart can be: yy, qq, mm, dy, dd, wk, dw, hh, mi, ss, ms

number is an expression that can be resolved to an int that is added to a datepart of date

date is an expression that can be resolved to a time, date, smalldatetime, datetime, datetime2, or datetimeoffset value.

Comparing two byte arrays in .NET

There's a new built-in solution for this in .NET 4 - IStructuralEquatable

static bool ByteArrayCompare(byte[] a1, byte[] a2) 
    return StructuralComparisons.StructuralEqualityComparer.Equals(a1, a2);

Change Background color (css property) using Jquery

$("#bchange").click(function() {
    $("body, this").css("background-color","yellow");

How to Install pip for python 3.7 on Ubuntu 18?

I installed pip3 using

python3.7 -m pip install pip

But upon using pip3 to install other dependencies, it was using python3.6.
You can check the by typing pip3 --version

Hence, I used pip3 like this (stated in one of the above answers):

python3.7 -m pip install <module>

or use it like this:

python3.7 -m pip install -r requirements.txt

I made a bash alias for later use in ~/.bashrc file as alias pip3='python3.7 -m pip'. If you use alias, don't forget to source ~/.bashrc after making the changes and saving it.

How to decrypt a password from SQL server?

The SQL Server password hashing algorithm:

hashBytes = 0x0100 | fourByteSalt | SHA1(utf16EncodedPassword+fourByteSalt)

For example, to hash the password "correct horse battery staple". First we generate some random salt:

fourByteSalt = 0x9A664D79;

And then hash the password (encoded in UTF-16) along with the salt:

 SHA1("correct horse battery staple" + 0x9A66D79);
=SHA1(0x63006F007200720065006300740020006200610074007400650072007900200068006F00720073006500200073007400610070006C006500 0x9A66D79)

The value stored in the syslogins table is the concatenation of:

[header] + [salt] + [hash]
0x0100 9A664D79 6EDB2FA35E3B8FAB4DBA2FFB62F5426B67FE54A3

Which you can see in SQL Server:

   name, CAST(password AS varbinary(max)) AS PasswordHash
FROM sys.syslogins
WHERE name = 'sa'

name  PasswordHash
====  ======================================================
sa    0x01009A664D796EDB2FA35E3B8FAB4DBA2FFB62F5426B67FE54A3
  • Version header: 0100
  • Salt (four bytes): 9A664D79
  • Hash: 6EDB2FA35E3B8FAB4DBA2FFB62F5426B67FE54A3 (SHA-1 is 20 bytes; 160 bits)


You validate a password by performing the same hash:

  • grab the salt from the saved PasswordHash: 0x9A664D79

and perform the hash again:

SHA1("correct horse battery staple" + 0x9A66D79);

which will come out to the same hash, and you know the password is correct.

What once was good, but now is weak

The hashing algorithm introduced with SQL Server 7, in 1999, was good for 1999.

  • It is good that the password hash salted.
  • It is good to append the salt to the password, rather than prepend it.

But today it is out-dated. It only runs the hash once, where it should run it a few thousand times, in order to thwart brute-force attacks.

In fact, Microsoft's Baseline Security Analyzer will, as part of it's checks, attempt to bruteforce passwords. If it guesses any, it reports the passwords as weak. And it does get some.

Brute Forcing

To help you test some passwords:

DECLARE @hash varbinary(max)
SET @hash = 0x01009A664D796EDB2FA35E3B8FAB4DBA2FFB62F5426B67FE54A3
--Header: 0x0100
--Salt:   0x9A664D79
--Hash:   0x6EDB2FA35E3B8FAB4DBA2FFB62F5426B67FE54A3

DECLARE @password nvarchar(max)
SET @password = 'password'

    @password AS CandidatePassword,
    @hash AS PasswordHash,

    --SHA1 of Password + Salt
    HASHBYTES('SHA1', @password + SUBSTRING(CONVERT(NVARCHAR(MAX), @hash), 2, 2))

SQL Server 2012 and SHA-512

Starting with SQL Server 2012, Microsoft switched to using SHA-2 512-bit:

hashBytes = 0x0200 | fourByteSalt | SHA512(utf16EncodedPassword+fourByteSalt)

Changing the version prefix to 0x0200:

   name, CAST(password AS varbinary(max)) AS PasswordHash
FROM sys.syslogins

name  PasswordHash
----  --------------------------------
xkcd  0x02006A80BA229556EB280AA7818FAF63A0DA8D6B7B120C6760F0EB0CB5BB320A961B04BD0836 0C0E8CC4C326220501147D6A9ABD2A006B33DEC99FCF1A822393FC66226B7D38
  • Version: 0200 (SHA-2 256-bit)
  • Salt: 6A80BA22
  • Hash (64 bytes): 9556EB280AA7818FAF63A0DA8D6B7B120C6760F0EB0CB5BB320A961B04BD0836 0C0E8CC4C326220501147D6A9ABD2A006B33DEC99FCF1A822393FC66226B7D38

This means we hash the UTF-16 encoded password, with the salt suffix:

  • SHA512("correct horse battery staple"+6A80BA22)
  • SHA512(63006f0072007200650063007400200068006f0072007300650020006200610074007400650072007900200073007400610070006c006500 + 6A80BA22)
  • 9556EB280AA7818FAF63A0DA8D6B7B120C6760F0EB0CB5BB320A961B04BD0836 0C0E8CC4C326220501147D6A9ABD2A006B33DEC99FCF1A822393FC66226B7D38

How to populate a sub-document in mongoose after creating it?

In order to populate referenced subdocuments, you need to explicitly define the document collection to which the ID references to (like created_by: { type: Schema.Types.ObjectId, ref: 'User' }).

Given this reference is defined and your schema is otherwise well defined as well, you can now just call populate as usual (e.g. populate('comments.created_by'))

Proof of concept code:

// Schema
var mongoose = require('mongoose');
var Schema = mongoose.Schema;

var UserSchema = new Schema({
  name: String

var CommentSchema = new Schema({
  text: String,
  created_by: { type: Schema.Types.ObjectId, ref: 'User' }

var ItemSchema = new Schema({
   comments: [CommentSchema]

// Connect to DB and instantiate models    
var db = mongoose.connect('enter your database here');
var User = db.model('User', UserSchema);
var Comment = db.model('Comment', CommentSchema);
var Item = db.model('Item', ItemSchema);

// Find and populate
Item.find({}).populate('comments.created_by').exec(function(err, items) {

Finally note that populate works only for queries so you need to first pass your item into a query and then call it:, item) {
    Item.findOne(item).populate('comments.created_by').exec(function (err, item) {
            status: 'success',
            message: "You have commented on this item",

How to use PHP string in mySQL LIKE query?

You have the syntax wrong; there is no need to place a period inside a double-quoted string. Instead, it should be more like

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

You can confirm this by printing out the string to see that it turns out identical to the first case.

Of course it's not a good idea to simply inject variables into the query string like this because of the danger of SQL injection. At the very least you should manually escape the contents of the variable with mysql_real_escape_string, which would make it look perhaps like this:

$sql = sprintf("SELECT * FROM table WHERE the_number LIKE '%s%%'",
$query = mysql_query($sql);

Note that inside the first argument of sprintf the percent sign needs to be doubled to end up appearing once in the result.

Select unique or distinct values from a list in UNIX shell script

With AWK you can do, I find it faster than sort

 ./yourscript.ksh | awk '!a[$0]++'

Character reading from file in Python

Leaving aside the fact that your text file is broken (U+2018 is a left quotation mark, not an apostrophe): iconv can be used to transliterate unicode characters to ascii.

You'll have to google for "iconvcodec", since the module seems not to be supported anymore and I can't find a canonical home page for it.

>>> import iconvcodec
>>> from locale import setlocale, LC_ALL
>>> setlocale(LC_ALL, '')
>>> u'\u2018'.encode('ascii//translit')

Alternatively you can use the iconv command line utility to clean up your file:

$ xxd foo
0000000: e280 980a                                ....
$ iconv -t 'ascii//translit' foo | xxd
0000000: 270a                                     '.

Execute action when back bar button of UINavigationController is pressed

I accomplished this by calling/overriding viewWillDisappear and then accessing the stack of the navigationController like this:

override func viewWillDisappear(animated: Bool) {

    let stack = self.navigationController?.viewControllers.count

    if stack >= 2 {
        // for whatever reason, the last item on the stack is the TaskBuilderViewController (not self), so we only use -1 to access it
        if let lastitem = self.navigationController?.viewControllers[stack! - 1] as? theViewControllerYoureTryingToAccess {
            // hand over the data via public property or call a public method of theViewControllerYoureTryingToAccess, like
            lastitem.value = 5

Install Qt on Ubuntu

In Ubuntu 18.04 the QtCreator examples and API docs missing, This is my way to solve this problem, should apply to almost every Ubuntu release.

For QtCreator and Examples and API Docs:

sudo apt install `apt-cache search 5-examples | grep qt | grep example | awk '{print $1 }' | xargs `

sudo apt install `apt-cache search 5-doc | grep "Qt 5 " | awk '{print $1}' | xargs`

sudo apt-get install build-essential qtcreator qt5-default

If something is also missing, then:

sudo apt install `apt-cache search qt | grep 5- | grep ^qt | awk '{print $1}' | xargs `

Hope to be helpful.

Also posted in Ask Ubuntu:

What does a lazy val do?

A lazy val is most easily understood as a "memoized (no-arg) def".

Like a def, a lazy val is not evaluated until it is invoked. But the result is saved so that subsequent invocations return the saved value. The memoized result takes up space in your data structure, like a val.

As others have mentioned, the use cases for a lazy val are to defer expensive computations until they are needed and store their results, and to solve certain circular dependencies between values.

Lazy vals are in fact implemented more or less as memoized defs. You can read about the details of their implementation here:

What is the id( ) function used for?

id() does return the address of the object being referenced (in CPython), but your confusion comes from the fact that python lists are very different from C arrays. In a python list, every element is a reference. So what you are doing is much more similar to this C code:

int *arr[3];
arr[0] = malloc(sizeof(int));
*arr[0] = 1;
arr[1] = malloc(sizeof(int));
*arr[1] = 2;
arr[2] = malloc(sizeof(int));
*arr[2] = 3;
printf("%p %p %p", arr[0], arr[1], arr[2]);

In other words, you are printing the address from the reference and not an address relative to where your list is stored.

In my case, I have found the id() function handy for creating opaque handles to return to C code when calling python from C. Doing that, you can easily use a dictionary to look up the object from its handle and it's guaranteed to be unique.

How to generate graphs and charts from mysql database in php

I use Google Chart Tools It's well documented and the charts look great. Being javascript, you can feed it json data via ajax.

MySQL Error: #1142 - SELECT command denied to user

You need to give privileges to the particular user by giving the command mysql> GRANT ALL PRIVILEGES . To 'username'@'localhost'; and then give FLUSH PRIVILEGES; command. Then it won't give this error.., hope it helps thank you..!

How to sort by dates excel?

The problem in here is ms excel not recognizing the things which we entered as date, though is appears as date in menu bar. Select cell and type "=istext(cell ad)" then you can see it "TRUE" hence still your date ms excel thinks as a text that is why it aligns to left automatically. So we should change the type of text. There are many types of changing methods. but I think this too easy and lets do it now.

SELECT THE CELLS -> Go DATA in menu bar -> Then select "Text to Columns" object -> Select "Delimited" in first window then click next -> remove all ticks in the second window and hit next button -> last window select the "Date" and select your prefer date format then hit the finish button.(Then dates look like Wednesday, March 14, 2012) Then you can using previously used formula use and check whether our date is recognized in excel. Then you can Sort as you want. Thank you

Is it possible to use an input value attribute as a CSS selector?

You can use Css3 attribute selector or attribute value selector.

/This will make all input whose value is defined to red/


/This will make conditional selection depending on input value/

input[value="United States"]{

There are other attribute selector like attribute contains value selector,

input[value="United S"]{
color: red;

This will still make any input with United state as red text.

Than we attribute value starts with selector

color: red;

Any input text starts with 'united' will have font color red

And the last one is attribute value ends with selector


Any input value ends with 'States' will have font color red

Getting IPV4 address from a sockaddr structure

Once sockaddr cast to sockaddr_in, it becomes this:

struct sockaddr_in {
    u_short     sin_family;
    u_short     sin_port;
    struct      in_addr sin_addr;
    char        sin_zero[8];

Can I hide/show asp:Menu items based on role?

You just have to remove the parent menu in the page init event.

    Protected Sub navMenu_Init(sender As Object, e As System.EventArgs) Handles navMenu.Init
    'Remove the admin menu for the norms
    Dim cUser As Boolean = HttpContext.Current.User.IsInRole("Admin")

    'If user is not in the Admin role removes the 1st menu at index 0
    If cUser = False Then
    End If
End Sub

Validating an XML against referenced XSD in C#

The following example validates an XML file and generates the appropriate error or warning.

using System;
using System.IO;
using System.Xml;
using System.Xml.Schema;

public class Sample

    public static void Main()
        //Load the XmlSchemaSet.
        XmlSchemaSet schemaSet = new XmlSchemaSet();
        schemaSet.Add("urn:bookstore-schema", "books.xsd");

        //Validate the file using the schema stored in the schema set.
        //Any elements belonging to the namespace "urn:cd-schema" generate
        //a warning because there is no schema matching that namespace.
        Validate("store.xml", schemaSet);

    private static void Validate(String filename, XmlSchemaSet schemaSet)
        Console.WriteLine("\r\nValidating XML file {0}...", filename.ToString());

        XmlSchema compiledSchema = null;

        foreach (XmlSchema schema in schemaSet.Schemas())
            compiledSchema = schema;

        XmlReaderSettings settings = new XmlReaderSettings();
        settings.ValidationEventHandler += new ValidationEventHandler(ValidationCallBack);
        settings.ValidationType = ValidationType.Schema;

        //Create the schema validating reader.
        XmlReader vreader = XmlReader.Create(filename, settings);

        while (vreader.Read()) { }

        //Close the reader.

    //Display any warnings or errors.
    private static void ValidationCallBack(object sender, ValidationEventArgs args)
        if (args.Severity == XmlSeverityType.Warning)
            Console.WriteLine("\tWarning: Matching schema not found.  No validation occurred." + args.Message);
            Console.WriteLine("\tValidation error: " + args.Message);


The preceding example uses the following input files.

<?xml version='1.0'?>
<bookstore xmlns="urn:bookstore-schema" xmlns:cd="urn:cd-schema">
  <book genre="novel">
    <title>The Confidence Man</title>


<xsd:schema xmlns:xsd=""

 <xsd:element name="bookstore" type="bookstoreType"/>

 <xsd:complexType name="bookstoreType">
  <xsd:sequence maxOccurs="unbounded">
   <xsd:element name="book"  type="bookType"/>

 <xsd:complexType name="bookType">
   <xsd:element name="title" type="xsd:string"/>
   <xsd:element name="author" type="authorName"/>
   <xsd:element name="price"  type="xsd:decimal"/>
  <xsd:attribute name="genre" type="xsd:string"/>

 <xsd:complexType name="authorName">
   <xsd:element name="first-name"  type="xsd:string"/>
   <xsd:element name="last-name" type="xsd:string"/>


creating an array of structs in c++

Some compilers support compound literals as an extention, allowing this construct:

Customer customerRecords[2];
customerRecords[0] = (Customer){25, "Bob Jones"};
customerRecords[1] = (Customer){26, "Jim Smith"};

But it's rather unportable.

PHPMyAdmin Default login password

If it was installed with plesk (not sure if it's just that, or on the phpmyadmin side: It changes the root user to admin.

Determine what attributes were changed in Rails after_save callback?

You just add an accessor who define what you change

class Post < AR::Base
  attr_reader :what_changed

  before_filter :what_changed?

  def what_changed?
    @what_changed = changes || []

  after_filter :action_on_changes

  def action_on_changes
    @what_changed.each do |change|
      p change

Git:nothing added to commit but untracked files present

Follow all the steps.

Step 1: initialize git

$ git init

Step 2: Check files are exist or not.

$git ls

Step 3 : Add the file

$git add filename

Step 4: Add comment to show

$git commit -m "your comment"

Step 5: Link to your repository

$git remote add origin  "copy repository link  and paste here"

Step 6: Push on Git

$ git push -u origin master

Difference between return 1, return 0, return -1 and exit?

To indicate execution status.

status 0 means the program succeeded.

status different from 0 means the program exited due to error or anomaly.

return n; from your main entry function will terminate your process and report to the parent process (the one that executed your process) the result of your process. 0 means SUCCESS. Other codes usually indicates a failure and its meaning.