Programs & Examples On #Inputbinding

'Invalid update: invalid number of rows in section 0

Here is some code from above added with actual action code (point 1 and 2);

func tableView(_ tableView: UITableView, trailingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration? {
    let deleteAction = UIContextualAction(style: .destructive, title: "Delete") { _, _, completionHandler in

        // 1. remove object from your array
        scannedItems.remove(at: indexPath.row)
        // 2. reload the table, otherwise you get an index out of bounds crash

    deleteAction.backgroundColor = .systemOrange
    let configuration = UISwipeActionsConfiguration(actions: [deleteAction])
    configuration.performsFirstActionWithFullSwipe = true
    return configuration

No connection string named 'MyEntities' could be found in the application config file

It is because your context class is being inherited from DbContext. I guess your ctor is like this:

public MyEntities()
    : base("name=MyEntities")

name=... should be changed to your connectionString's name

How can I avoid getting this MySQL error Incorrect column specifier for column COLUMN NAME?

Quoting the doc:

Some attributes do not apply to all data types. AUTO_INCREMENT applies only to integer and floating-point types. DEFAULT does not apply to the BLOB or TEXT types.

In your case, you're trying to apply AUTO_INCREMENT modifier to char column. To solve this, either drop AUTO_INCREMENT altogether (that means you'll have to generate a unique id on the application level) or just change topic_id type to the relevant integer one.

As a sidenote, it makes little sense using char(36) to store the posts count, so that column's type probably has to be changed as well. It looks like you're going this way to prevent integer overflow - but if you're dealing with more than 18446744073709551615 posts (the biggest number that can be stored in BIGINT UNSIGNED column) in a single topic, you have far bigger problem on your side probably. )

How to use "svn export" command to get a single file from the repository?

I know the OP was asking about doing the export from the command line, but just in case this is helpful to anyone else out there...

You could just let Eclipse (plus one of the plugins discussed here) do the work for you.

Obviously, downloading Eclipse just for doing a single export is overkill, but if you are already using it for development, you can also do an svn export simply from your IDE's context menu when browsing an SVN repository.


  • easier for those not so familiar with using SVN at the command-line level (but you can learn about what happens at the command-line level by looking at the SVN console with a range of commands)
  • you'd already have your SVN details set up and wouldn't have to worry about authenticating, etc.
  • you don't have to worry about mistyping the URL, or remembering the order of parameters
  • you can specify in a dialog which directory you'd like to export to
  • you can specify in a dialog whether you'd like to export from TRUNK/HEAD or use a specific revision

bash: mkvirtualenv: command not found

On Windows 10, to create the virtual environment, I replace "pip mkvirtualenv myproject" by "mkvirtualenv myproject" and that works well.

AngularJS $watch window resize inside directive

You shouldn't need a $watch. Just bind to resize event on window:


'use strict';

var app = angular.module('plunker', []);

app.directive('myDirective', ['$window', function ($window) {

     return {
        link: link,
        restrict: 'E',
        template: '<div>window size: {{width}}px</div>'

     function link(scope, element, attrs){

       scope.width = $window.innerWidth;

       angular.element($window).bind('resize', function(){

         scope.width = $window.innerWidth;

         // manuall $digest required as resize event
         // is outside of angular



Please add a @Pipe/@Directive/@Component annotation. Error

If you are exporting another class in that module, make sure that it is not in between @Component and your ClassComponent. For example:

@Component({ ... })

export class ExampleClass{}

export class ComponentClass{}  --> this will give this error.


export class ExampleClass{}

@Component ({ ... })

export class ComponentClass{}

How to add text to a WPF Label in code?

Label myLabel = new Label (); myLabel.Content = "Hello World!";

How do I connect to a specific Wi-Fi network in Android programmatically?

You need to create WifiConfiguration instance like this:

String networkSSID = "test";
String networkPass = "pass";

WifiConfiguration conf = new WifiConfiguration();
conf.SSID = "\"" + networkSSID + "\"";   // Please note the quotes. String should contain ssid in quotes

Then, for WEP network you need to do this:

conf.wepKeys[0] = "\"" + networkPass + "\""; 
conf.wepTxKeyIndex = 0;

For WPA network you need to add passphrase like this:

conf.preSharedKey = "\""+ networkPass +"\"";

For Open network you need to do this:


Then, you need to add it to Android wifi manager settings:

WifiManager wifiManager = (WifiManager)context.getSystemService(Context.WIFI_SERVICE); 

And finally, you might need to enable it, so Android connects to it:

List<WifiConfiguration> list = wifiManager.getConfiguredNetworks();
for( WifiConfiguration i : list ) {
    if(i.SSID != null && i.SSID.equals("\"" + networkSSID + "\"")) {
         wifiManager.enableNetwork(i.networkId, true);


UPD: In case of WEP, if your password is in hex, you do not need to surround it with quotes.

How to print Two-Dimensional Array like table

If you don't mind the commas and the brackets you can simply use:

System.out.println(Arrays.deepToString(twoDm).replace("], ", "]\n"));

Group dataframe and get sum AND count?

If you have lots of columns and only one is different you could do:

In[1]: grouper = df.groupby('Company Name')
In[2]: res = grouper.count()
In[3]: res['Amount'] = grouper.Amount.sum()
In[4]: res
                      Organisation Name   Amount
Company Name                                   
Vifor Pharma UK Ltd                  5  4207.93

Note you can then rename the Organisation Name column as you wish.

How to specify jdk path in eclipse.ini on windows 8 when path contains space

Windows-vm "C:\Program Files\Java\jdk1.6.0_07\jre\bin\javaw.exe" the system cannot find the file specified

Make sure when you create a txt file you don't type in the name "name.txt", just type in "name". If you type "name.txt" Eclipse will see it as "name.txt.txt". This solved it for me. Also save the file in the src folder, not the folder were the .java resides, one folder up.

WebForms UnobtrusiveValidationMode requires a ScriptResourceMapping for 'jquery'. Please add a ScriptResourceMapping named jquery(case-sensitive)

You need a web.config key to enable the pre 4.5 validation mode.

More Info on ValidationSettings:UnobtrusiveValidationMode:

Specifies how ASP.NET globally enables the built-in validator controls to use unobtrusive JavaScript for client-side validation logic.

Type: UnobtrusiveValidationMode

Default value: None

Remarks: If this key value is set to "None" [default], the ASP.NET application will use the pre-4.5 behavior (JavaScript inline in the pages) for client-side validation logic. If this key value is set to "WebForms", ASP.NET uses HTML5 data-attributes and late bound JavaScript from an added script reference for client-side validation logic.


      <add key="ValidationSettings:UnobtrusiveValidationMode" value="None" />

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

Just give the individual button elements a unique name. When pressed, the button's name is available as a request parameter the usual way like as with input elements.

You only need to make sure that the button inputs have type="submit" as in <input type="submit"> and <button type="submit"> and not type="button", which only renders a "dead" button purely for onclick stuff and all.


<form action="${pageContext.request.contextPath}/myservlet" method="post">
    <input type="submit" name="button1" value="Button 1" />
    <input type="submit" name="button2" value="Button 2" />
    <input type="submit" name="button3" value="Button 3" />


public class MyServlet extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        MyClass myClass = new MyClass();

        if (request.getParameter("button1") != null) {
        } else if (request.getParameter("button2") != null) {
        } else if (request.getParameter("button3") != null) {
        } else {
            // ???

        request.getRequestDispatcher("/WEB-INF/some-result.jsp").forward(request, response);


Alternatively, use <button type="submit"> instead of <input type="submit">, then you can give them all the same name, but an unique value. The value of the <button> won't be used as label, you can just specify that yourself as child.


<form action="${pageContext.request.contextPath}/myservlet" method="post">
    <button type="submit" name="button" value="button1">Button 1</button>
    <button type="submit" name="button" value="button2">Button 2</button>
    <button type="submit" name="button" value="button3">Button 3</button>


public class MyServlet extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        MyClass myClass = new MyClass();
        String button = request.getParameter("button");

        if ("button1".equals(button)) {
        } else if ("button2".equals(button)) {
        } else if ("button3".equals(button)) {
        } else {
            // ???

        request.getRequestDispatcher("/WEB-INF/some-result.jsp").forward(request, response);


See also:

What is the difference between JavaScript and ECMAScript?

ECMAScript = ES:

  • ECMAScript is a Standard for scripting languages.

  • Languages like Javascript are based on the ECMAScript standard.

  • ECMA Standard is based on several originating technologies, the most well known being JavaScript (Netscape) and JScript (Microsoft).

  • ECMA means European Computer Manufacturer’s Association

JavaScript = JS:

  • JavaScript is the most popular implementation of the ECMAScript Standard.

  • The core features of Javascript are based on the ECMAScript standard,  but Javascript also has other additional features that are not in the ECMA specifications/standard.

  • ActionScript and JScript are other languages that implement the ECMAScript.

  • JavaScript was submitted to ECMA for standardization but due to trademark issues with the name Javascript the standard became called ECMAScript.

  • Every browser has a JavaScript interpreter.

ES5 = ECMAScript 5:

  • ES5 is a version of the ECMAScript (old/current one).

  • ES5 is the JavaScript you know and use in the browser today.

  • ES5 does not require a build step (transpilers) to transform it into something that will run in today's browsers.

  • ECMAScript version 5 was finished in December 2009,  the latest versions of all major browsers (Chrome, Safari, Firefox, and IE)  have implemented version 5.

  • Version 5.1 was finished in June, 2011.

ES6 = ECMAScript 6 = ES2015 = ECMAScript 2015:

  • ES2015 is a version of the ECMAScript (new/future one).

  • Officially the name ES2015 should be used instead of ES6.

  • ES6 will tackle many of the core language shortcomings addressed in  TypeScript and CoffeeScript.

  • ES6 is the next iteration of JavaScript, but it does not run in today's browsers.

  • There are quite a few transpilers that will export ES5 for running in browsers.


  • BabelJS is the most popular transpiler that transforms new JavaScript ES6 to Old JavaScript ES5.

  • BabelJS makes it possible for writing the next generation of JavaScript today (means ES2015).

  • BabelJS simply takes ES2015 file and transform it into ES5 file.

  • Current browsers versions can now understand the new JavaScript code (ES2015), even if they don't yet support it.

TypeScript and CoffeeScript:

  • Both provides syntactic sugar on top of ES5  and then are transcompiled into ES5 compliant JavaScript. 

  • You write TypeScript or CoffeeScript then the transpiler transforms it into ES5 JavaScript.

Receiver not registered exception error?

The root of your problem is located here:


If the receiver was already unregistered (probably in the code that you didn't include in this post) or was not registered, then call to unregisterReceiver throws IllegalArgumentException. In your case you need to just put special try/catch for this exception and ignore it (assuming you can't or don't want to control number of times you call unregisterReceiver on the same recevier).

Applying CSS styles to all elements inside a DIV

I do not understand why it does not work for you, it works for me :


<div id="pagina-page" data-role="page">
    <div id="applyCSS">
    <!--all the elements here must follow a concrete CSS rules-->
        <a class="ui-bar-a">This "a" element text should be red
            <span class="ui-link-inherit">This span text in "a" element should be red too</span>


#applyCSS * {color:red;display:block;margin:20px;}

Maybe you have some special rules that you did not share with us...

pandas GroupBy columns with NaN (missing) values

I am not able to add a comment to M. Kiewisch since I do not have enough reputation points (only have 41 but need more than 50 to comment).

Anyway, just want to point out that M. Kiewisch solution does not work as is and may need more tweaking. Consider for example

>>> df = pd.DataFrame({'a': [1, 2, 3, 5], 'b': [4, np.NaN, 6, 4]})
>>> df
   a    b
0  1  4.0
1  2  NaN
2  3  6.0
3  5  4.0
>>> df.groupby(['b']).sum()
4.0  6
6.0  3
>>> df.astype(str).groupby(['b']).sum()
4.0  15
6.0   3
nan   2

which shows that for group b=4.0, the corresponding value is 15 instead of 6. Here it is just concatenating 1 and 5 as strings instead of adding it as numbers.

How to justify a single flexbox item (override justify-content)

AFAIK there is no property for that in the specs, but here is a trick I’ve been using: set the container element ( the one with display:flex ) to justify-content:space-around Then add an extra element between the first and second item and set it to flex-grow:10 (or some other value that works with your setup)

Edit: if the items are tightly aligned it's a good idea to add flex-shrink: 10; to the extra element as well, so the layout will be properly responsive on smaller devices.

How to set selected value on select using selectpicker plugin from bootstrap


in place of selector you can give you selector either class or id for example: $('#mySelect').selectpicker('val',your_value)

Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost."

I have this issue also, running on an iOS 8 device. It is detailed some more here and seems to be a case of iOS trying to use connections that have already timed out. My issue isn't the same as the Keep-Alive problem explained in that link, however it seems to be the same end result.

I have corrected my problem by running a recursive block whenever I receive an error -1005 and this makes the connection eventually get through even though sometimes the recursion can loop for 100+ times before the connection works, however it only adds a mere second onto run times and I bet that is just the time it takes the debugger to print the NSLog's for me.

Here's how I run a recursive block with AFNetworking: Add this code to your connection class file

// From Mike Ash's recursive block fixed-point-combinator strategy
dispatch_block_t recursiveBlockVehicle(void (^block)(dispatch_block_t recurse))
    // assuming ARC, so no explicit copy
    return ^{ block(recursiveBlockVehicle(block)); };
typedef void (^OneParameterBlock)(id parameter);
OneParameterBlock recursiveOneParameterBlockVehicle(void (^block)(OneParameterBlock recurse, id parameter))
    return ^(id parameter){ block(recursiveOneParameterBlockVehicle(block), parameter); };

Then use it likes this:

+ (void)runOperationWithURLPath:(NSString *)urlPath
            andStringDataToSend:(NSString *)stringData
                    withTimeOut:(NSString *)timeOut
     completionBlockWithSuccess:(void (^)(AFHTTPRequestOperation *operation, id responseObject))success
                        failure:(void (^)(AFHTTPRequestOperation *operation, NSError *error))failure
    OneParameterBlock run = recursiveOneParameterBlockVehicle(^(OneParameterBlock recurse, id parameter) {
        // Put the request operation here that you want to keep trying
        NSNumber *offset = parameter;
        NSLog(@"--------------- Attempt number: %@ ---------------", offset);

        MyAFHTTPRequestOperation *operation =
            [[MyAFHTTPRequestOperation alloc] initWithURLPath:urlPath

        [operation setCompletionBlockWithSuccess:
            ^(AFHTTPRequestOperation *operation, id responseObject) {
                success(operation, responseObject);
            failure:^(AFHTTPRequestOperation *operation2, NSError *error) {
                if (error.code == -1005) {
                    if (offset.intValue >= numberOfRetryAttempts) {
                        // Tried too many times, so fail
                        NSLog(@"Error during connection: %@",error.description);
                        failure(operation2, error);
                    } else {
                        // Failed because of an iOS bug using timed out connections, so try again
                } else {
                    NSLog(@"Error during connection: %@",error.description);
                    failure(operation2, error);
        [[NSOperationQueue mainQueue] addOperation:operation];

You'll see that I use a AFHTTPRequestOperation subclass but add your own request code. The important part is calling recurse(@offset.intValue+1)); to make the block be called again.

How to select distinct rows in a datatable and store into an array

objds.Table1.Select(r => r.ProcessName).AsEnumerable().Distinct();

MySQL InnoDB not releasing disk space after deleting data rows from table

Year back i also faced same problem on mysql5.7 version and ibdata1 occupied 150 Gb. so i added undo tablespaces

Take Mysqldump backup
Stop mysql service
Remove all data from data dir
Add below undo tablespace parameter in current my.cnf

 #undo tablespace
  innodb_undo_directory =  /var/lib/mysql/
  innodb_rollback_segments = 128 
  innodb_undo_tablespaces = 3
  innodb_undo_logs = 128  
  innodb_undo_log_truncate = ON

Start mysql service
store mysqldump backup

Problem resolved !!


I think your INSERT statement is wrong, see correct syntax:

edit: as Andrew already pointed out...

Checking if an object is a given type in Swift

If you don't know that you will get an array of dictionaries or single dictionary in the response from server you need to check whether the result contains an array or not.
In my case always receiving an array of dictionaries except once. So, to handle that I used the below code for swift 3.

if let str = strDict["item"] as? Array<Any>

Here as? Array checks whether the obtained value is array (of dictionary items). In else case you can handle if it is single dictionary item which is not kept inside an array.

How to get first and last day of previous month (with timestamp) in SQL Server

I've not seen this solution presented yet; this is my preference for its simpler readability:

select dateadd(month,-1,format(getutcdate(),'yyyy-MM-01'))

ImportError: cannot open shared object file: No such file or directory

You need to add sudo . I did the following to get it installed :

sudo apt-get install libsm6 libxrender1 libfontconfig1

and then did that (optional! maybe you won't need it)

sudo python3 -m pip install opencv-contrib-python

FINALLY got it done !

How to enable CORS in Core WebAPI



will allow you to do CORS with built-in features, but it does not handle OPTIONS request. The best workaround so far is creating a new Middleware as suggested in a previous post. Check the answer marked as correct in the following post:

Enable OPTIONS header for CORS on .NET Core Web API

ASP.NET MVC Html.ValidationSummary(true) does not display model errors

I know this is kind of old and has been marked as answers with 147 up votes, but there is something else to consider.

You can have all the model errors, the property named and string.Empty keys alike, be shown in the ValidationSummary if you need to. There is an overload in the ValidationSummary that will do this.

    //   excludePropertyErrors:
    //   true to have the summary display model-level errors only, or false to have
    //   the summary display all errors.
    public static MvcHtmlString ValidationSummary(this HtmlHelper htmlHelper, bool excludePropertyErrors);

enter image description here

How to find Oracle Service Name

Overview of the services used by all sessions provides the distionary view v$session(or gv$session for RAC databases) in the column SERVICE_NAME.

To limit the information to the connected session use the SID from the view V$MYSTAT:

select SERVICE_NAME from gv$session where sid in (
select sid from V$MYSTAT)

If the name is SYS$USERS the session is connected to a default service, i.e. in the connection string no explicit service_name was specified.

To see what services are available in the database use following queries:

select name from V$SERVICES;
select name from V$ACTIVE_SERVICES;

How to set session attribute in java?

Java file :

package Jclasspackage

public class Jclass {

    public String uname ;
     * @return the uname
    public String getUname() {
        return uname;

     * @param uname the uname to set
    public void setUname(String uname) {
        this.uname = uname;

    public Jclass() {
        this.uname = null;

    public static void main(String[] args) {


JSP file: sample.jsp

    <%@ page language="java"

< import="" />   
<% Jclass jc = new Jclass();
String username = (String)request.getAttribute("un")


In this way you can access the username in the java file using "this.username" in the class

Floating point vs integer calculations on modern hardware

TIL This varies (a lot). Here are some results using gnu compiler (btw I also checked by compiling on machines, gnu g++ 5.4 from xenial is a hell of a lot faster than 4.6.3 from linaro on precise)

Intel i7 4700MQ xenial

short add: 0.822491
short sub: 0.832757
short mul: 1.007533
short div: 3.459642
long add: 0.824088
long sub: 0.867495
long mul: 1.017164
long div: 5.662498
long long add: 0.873705
long long sub: 0.873177
long long mul: 1.019648
long long div: 5.657374
float add: 1.137084
float sub: 1.140690
float mul: 1.410767
float div: 2.093982
double add: 1.139156
double sub: 1.146221
double mul: 1.405541
double div: 2.093173

Intel i3 2370M has similar results

short add: 1.369983
short sub: 1.235122
short mul: 1.345993
short div: 4.198790
long add: 1.224552
long sub: 1.223314
long mul: 1.346309
long div: 7.275912
long long add: 1.235526
long long sub: 1.223865
long long mul: 1.346409
long long div: 7.271491
float add: 1.507352
float sub: 1.506573
float mul: 2.006751
float div: 2.762262
double add: 1.507561
double sub: 1.506817
double mul: 1.843164
double div: 2.877484

Intel(R) Celeron(R) 2955U (Acer C720 Chromebook running xenial)

short add: 1.999639
short sub: 1.919501
short mul: 2.292759
short div: 7.801453
long add: 1.987842
long sub: 1.933746
long mul: 2.292715
long div: 12.797286
long long add: 1.920429
long long sub: 1.987339
long long mul: 2.292952
long long div: 12.795385
float add: 2.580141
float sub: 2.579344
float mul: 3.152459
float div: 4.716983
double add: 2.579279
double sub: 2.579290
double mul: 3.152649
double div: 4.691226

DigitalOcean 1GB Droplet Intel(R) Xeon(R) CPU E5-2630L v2 (running trusty)

short add: 1.094323
short sub: 1.095886
short mul: 1.356369
short div: 4.256722
long add: 1.111328
long sub: 1.079420
long mul: 1.356105
long div: 7.422517
long long add: 1.057854
long long sub: 1.099414
long long mul: 1.368913
long long div: 7.424180
float add: 1.516550
float sub: 1.544005
float mul: 1.879592
float div: 2.798318
double add: 1.534624
double sub: 1.533405
double mul: 1.866442
double div: 2.777649

AMD Opteron(tm) Processor 4122 (precise)

short add: 3.396932
short sub: 3.530665
short mul: 3.524118
short div: 15.226630
long add: 3.522978
long sub: 3.439746
long mul: 5.051004
long div: 15.125845
long long add: 4.008773
long long sub: 4.138124
long long mul: 5.090263
long long div: 14.769520
float add: 6.357209
float sub: 6.393084
float mul: 6.303037
float div: 17.541792
double add: 6.415921
double sub: 6.342832
double mul: 6.321899
double div: 15.362536

This uses code from as benchmark-pc.c

g++ -fpermissive -O3 -o benchmark-pc benchmark-pc.c

I've run multiple passes, but this seems to be the case that general numbers are the same.

One notable exception seems to be ALU mul vs FPU mul. Addition and subtraction seem trivially different.

Here is the above in chart form (click for full size, lower is faster and preferable):

Chart of above data

Update to accomodate @Peter Cordes

i7 4700MQ Linux Ubuntu Xenial 64-bit (all patches to 2018-03-13 applied)
    short add: 0.773049
    short sub: 0.789793
    short mul: 0.960152
    short div: 3.273668
      int add: 0.837695
      int sub: 0.804066
      int mul: 0.960840
      int div: 3.281113
     long add: 0.829946
     long sub: 0.829168
     long mul: 0.960717
     long div: 5.363420
long long add: 0.828654
long long sub: 0.805897
long long mul: 0.964164
long long div: 5.359342
    float add: 1.081649
    float sub: 1.080351
    float mul: 1.323401
    float div: 1.984582
   double add: 1.081079
   double sub: 1.082572
   double mul: 1.323857
   double div: 1.968488
AMD Opteron(tm) Processor 4122 (precise, DreamHost shared-hosting)
    short add: 1.235603
    short sub: 1.235017
    short mul: 1.280661
    short div: 5.535520
      int add: 1.233110
      int sub: 1.232561
      int mul: 1.280593
      int div: 5.350998
     long add: 1.281022
     long sub: 1.251045
     long mul: 1.834241
     long div: 5.350325
long long add: 1.279738
long long sub: 1.249189
long long mul: 1.841852
long long div: 5.351960
    float add: 2.307852
    float sub: 2.305122
    float mul: 2.298346
    float div: 4.833562
   double add: 2.305454
   double sub: 2.307195
   double mul: 2.302797
   double div: 5.485736
Intel Xeon E5-2630L v2 @ 2.4GHz (Trusty 64-bit, DigitalOcean VPS)
    short add: 1.040745
    short sub: 0.998255
    short mul: 1.240751
    short div: 3.900671
      int add: 1.054430
      int sub: 1.000328
      int mul: 1.250496
      int div: 3.904415
     long add: 0.995786
     long sub: 1.021743
     long mul: 1.335557
     long div: 7.693886
long long add: 1.139643
long long sub: 1.103039
long long mul: 1.409939
long long div: 7.652080
    float add: 1.572640
    float sub: 1.532714
    float mul: 1.864489
    float div: 2.825330
   double add: 1.535827
   double sub: 1.535055
   double mul: 1.881584
   double div: 2.777245

Python: How to remove empty lists from a list?

Calling filter with None will filter out all falsey values from the list (which an empty list is)

list2 = filter(None, list1)

Way to get number of digits in an int?

I see people using String libraries or even using the Integer class. Nothing wrong with that but the algorithm for getting the number of digits is not that complicated. I am using a long in this example but it works just as fine with an int.

 private static int getLength(long num) {

    int count = 1;

    while (num >= 10) {
        num = num / 10;

    return count;

How can I set a custom date time format in Oracle SQL Developer?

I have a related issue which I solved and wanted to let folks know about my solution. Using SQL Developer I exported from one database to csv, then tried to import it into another database. I kept getting an error in my date fields. My date fields were in the Timestamp format:

28-JAN-11 PM

The above solution (changing the NLS preferences) did not work for me when I imported, but I finally got the following to work:

In the Import Wizard Column Definition screen, I entered "DD-MON-RR HH.MI.SSXFF AM" in the Format box, and it finally imported successfully. Unfortunately I have dozens of date fields and to my knowledge there is no way to systematically apply this format to all date fields so I had to do it manually....sigh. If anyone knows a better way I'd be happy to hear it!

In Subversion can I be a user other than my login name?

If you are using svn+ssh to connect to the repository then the only thing that authenticates you and authorizes you is your ssh credentials. EVERYTHING else is ignored. Your username will be logged in subversion exactly as it is established in your ssh connection. An excellent explanation of this is at

Listen to port via a Java socket

Try this piece of code, rather than ObjectInputStream.

BufferedReader in = new BufferedReader (new InputStreamReader (socket.getInputStream ()));
while (true)
    String cominginText = "";
        cominginText = in.readLine ();
        System.out.println (cominginText);
    catch (IOException e)
        //error ("System: " + "Connection to server lost!");
        System.exit (1);

How to install node.js as windows service?

From this blog

Next up, I wanted to host node as a service, just like IIS. This way it’d start up with my machine, run in the background, restart automatically if it crashes and so forth.

This is where nssm, the non-sucking service manager, enters the picture. This tool lets you host a normal .exe as a Windows service.

Here are the commands I used to setup an instance of the your node application as a service, open your cmd like administrator and type following commands:

nssm.exe install service_name c:\your_nodejs_directory\node.exe c:\your_application_directory\server.js
net start service_name

Is Safari on iOS 6 caching $.ajax results?

This JavaScript snippet works great with jQuery and jQuery Mobile:

    cache: false,
    headers: {
        'Cache-Control': 'no-cache'

Just place it somewhere in your JavaScript code (after jQuery is loaded, and best before you do AJAX requests) and it should help.

How to make a gap between two DIV within the same column

I know this was an old answer, but i would like to share my simple solution.

give style="margin-top:5px"

<div style="margin-top:5px">
  div 1
<div style="margin-top:5px">
  div2 elements
div3 elements

How to display an image stored as byte array in HTML/JavaScript?

Try putting this HTML snippet into your served document:

<img id="ItemPreview" src="">

Then, on JavaScript side, you can dynamically modify image's src attribute with so-called Data URL.

document.getElementById("ItemPreview").src = "data:image/png;base64," + yourByteArrayAsBase64;

Alternatively, using jQuery:

$('#ItemPreview').attr('src', `data:image/png;base64,${yourByteArrayAsBase64}`);

This assumes that your image is stored in PNG format, which is quite popular. If you use some other image format (e.g. JPEG), modify the MIME type ("image/..." part) in the URL accordingly.

Similar Questions:

Delete all nodes and relationships in neo4j 1.8

As of 2.3.0 and up to 3.3.0



Pre 2.3.0



Parse a URI String into Name-Value Collection

Kotlin's Answer with initial reference from, but with improved version by tidying up codes and provides 2 versions of it, and use immutable collection operations

Use to extract the Query. Then use the below provided extension functions

  1. Assuming you only want the last value of query i.e. page2&page3 will get {page=3}, use the below extension function
    fun URI.getQueryMap(): Map<String, String> {
        if (query == null) return emptyMap()

        return query.split("&")
                .mapNotNull { element -> element.split("=")
                        .takeIf { it.size == 2 && it.none { it.isBlank() } } }
                .associateBy({ it[0].decodeUTF8() }, { it[1].decodeUTF8() })

    private fun String.decodeUTF8() = URLDecoder.decode(this, "UTF-8") // decode page=%22ABC%22 to page="ABC"
  1. Assuming you want a list of all value for the query i.e. page2&page3 will get {page=[2, 3]}
    fun URI.getQueryMapList(): Map<String, List<String>> {
        if (query == null) return emptyMap()

        return query.split("&")
                .mapNotNull { element -> element.split("=")
                        .takeIf { it.size == 2 && it.none { it.isBlank() } } }
                .groupBy({ it[0].decodeUTF8() }, { it[1].decodeUTF8() })

    private fun String.decodeUTF8() = URLDecoder.decode(this, "UTF-8") // decode page=%22ABC%22 to page="ABC"

The way to use it as below

    val uri = URI("schema://host/path/?page=&page=2&page=2&page=3")
    println(uri.getQueryMapList()) // Result is {page=[2, 3]}
    println(uri.getQueryMap()) // Result is {page=3}

How to get full path of a file?

the easiest way I found is

for i in `ls`; do echo "`pwd`/$i"; done

it works well for me

Python Requests throwing SSLError

$ pip install -U requests[security]

  • Tested on Python 2.7.6 @ Ubuntu 14.04.4 LTS
  • Tested on Python 2.7.5 @ MacOSX 10.9.5 (Mavericks)

When this question was opened (2012-05) the Requests version was 0.13.1. On version 2.4.1 (2014-09) the "security" extras were introduced, using certifi package if available.

Right now (2016-09) the main version is 2.11.1, that works good without verify=False. No need to use requests.get(url, verify=False), if installed with requests[security] extras.

String to decimal conversion: dot separation instead of comma

Instead of replace we can force culture like

var x = decimal.Parse("18,285", new NumberFormatInfo() { NumberDecimalSeparator = "," });

it will give output 18.285

How do I declare a namespace in JavaScript?

I normally build it in a closure:

var MYNS = MYNS || {};

MYNS.subns = (function() {

    function privateMethod() {
        // Do private stuff, or build internal.
        return "Message";

    return {
        someProperty: 'prop value',
        publicMethod: function() {
            return privateMethod() + " stuff";

My style over the years has had a subtle change since writing this, and I now find myself writing the closure like this:

var MYNS = MYNS || {};

MYNS.subns = (function() {
    var internalState = "Message";

    var privateMethod = function() {
        // Do private stuff, or build internal.
        return internalState;
    var publicMethod = function() {
        return privateMethod() + " stuff";

    return {
        someProperty: 'prop value',
        publicMethod: publicMethod

In this way I find the public API and implementation easier to understand. Think of the return statement as being a public interface to the implementation.

Change event on select with knockout binding, how can I know if it is a real change?

This is just a guess, but I think it's happening because level is a number. In that case, the value binding will trigger a change event to update level with the string value. You can fix this, therefore, by making sure level is a string to start with.

Additionally, the more "Knockout" way of doing this is to not use event handlers, but to use observables and subscriptions. Make level an observable and then add a subscription to it, which will get run whenever level changes.

Intellij IDEA Java classes not auto compiling on save

Not enough points to comment on an existing answer, but similar to some people above, I wound up just adding a macro & keymap to Organize Imports / Format / SaveAll / FastReload(F9) / Synchronize.

The synchronize is added as it seems to be the only way I can also see updates in resources modified by external build tools / watchers (i.e., webpack).

The process is slower than eclipse - and for the external file refresh often have to run the command multiple times - but suppose I can live with it.

How to encrypt a large file in openssl using public key

Encrypting a very large file using smime is not advised since you might be able to encrypt large files using the -stream option, but not decrypt the resulting file due to hardware limitations see: problem decrypting big files

As mentioned above Public-key crypto is not for encrypting arbitrarily long files. Therefore the following commands will generate a pass phrase, encrypt the file using symmetric encryption and then encrypt the pass phrase using the asymmetric (public key). Note: the smime includes the use of a primary public key and a backup key to encrypt the pass phrase. A backup public/private key pair would be prudent.

Random Password Generation

Set up the RANDFILE value to a file accessible by the current user, generate the passwd.txt file and clean up the settings

openssl rand -base64 2048 > passwd.txt
rm ~/rand1


Use the commands below to encrypt the file using the passwd.txt contents as the password and AES256 to a base64 (-a option) file. Encrypt the passwd.txt using asymetric encryption into the file XXLarge.crypt.pass using a primary public key and a backup key.

openssl enc -aes-256-cbc -a -salt -in -out XXLarge.crypt -pass file:passwd.txt
openssl smime -encrypt -binary -in passwd.txt -out XXLarge.crypt.pass -aes256 PublicKey1.pem PublicBackupKey.pem
rm passwd.txt


Decryption simply decrypts the XXLarge.crypt.pass to passwd.tmp, decrypts the XXLarge.crypt to, and deletes the passwd.tmp file.

openssl smime -decrypt -binary -in XXLarge.crypt.pass -out passwd.tmp -aes256 -recip PublicKey1.pem -inkey PublicKey1.key
openssl enc -d -aes-256-cbc -a -in XXLarge.crypt -out -pass file:passwd.tmp
rm passwd.tmp

This has been tested against >5GB files..

5365295400 Nov 17 10:07
7265504220 Nov 17 10:03 XXLarge.crypt
      5673 Nov 17 10:03 XXLarge.crypt.pass
5365295400 Nov 17 10:07

Difference between EXISTS and IN in SQL?

I think,

  • EXISTS is when you need to match the results of query with another subquery. Query#1 results need to be retrieved where SubQuery results match. Kind of a Join.. E.g. select customers table#1 who have placed orders table#2 too

  • IN is to retrieve if the value of a specific column lies IN a list (1,2,3,4,5) E.g. Select customers who lie in the following zipcodes i.e. zip_code values lies in (....) list.

When to use one over the other... when you feel it reads appropriately (Communicates intent better).

Using Linq select list inside list

After my previous answer disaster, I'm going to try something else.

List<Model> usrList  = 
(list.Where(n => n.application == "applicationame").ToList());
usrList.ForEach(n => n.users.RemoveAll(n => n.surname != "surname"));

Eclipse Intellisense?

I've get closer to VisualStudio-like behaviour by setting the "Autocomplete Trigger for Java" to


and setting delay to 0.

Now I'd like to realize how to make it autocomplete method name when I press ( as VS's Intellisense does.

Java equivalent to #region in C#

I usually need this for commented code so I use curly brackets at start and end of that.

// Code
// Code
// Code
// Code

It could be used for code snippets but can create problems in some code because it changes the scope of variable.

Two arrays in foreach loop

Use array_combine() to fuse the arrays together and iterate over the result.

$countries = array_combine($codes, $names);

In Bash, how to add "Are you sure [Y/n]" to any command or alias?

read -r -p "Are you sure? [Y/n]" response
  response=${response,,} # tolower
  if [[ $response =~ ^(yes|y| ) ]] || [[ -z $response ]]; then

How do I create a new line in Javascript?

your solution is

var i;
for(i=10; i>=0; i= i-1){
   var s;
   for(s=0; s<i; s = s+1){
   //printing new line

log4j logging hierarchy order

This table might be helpful for you:

Log Level

Going down the first column, you will see how the log works in each level. i.e for WARN, (FATAL, ERROR and WARN) will be visible. For OFF, nothing will be visible.

Truncate (not round off) decimal numbers in javascript

@Dogbert's answer can be improved with Math.trunc, which truncates instead of rounding.

There is a difference between rounding and truncating. Truncating is clearly the behaviour this question is seeking. If I call truncate(-3.14) and receive -4 back, I would definitely call that undesirable. – @NickKnowlson

var a = 5.467;
var truncated = Math.trunc(a * 100) / 100; // = 5.46
var a = -5.467;
var truncated = Math.trunc(a * 100) / 100; // = -5.46

How to create a new file in unix?

The command is lowercase: touch filename.

Keep in mind that touch will only create a new file if it does not exist! Here's some docs for good measure:

If you always want an empty file, one way to do so would be to use:

echo "" > filename

WebSockets and Apache proxy : how to configure mod_proxy_wstunnel?

For me it works after adding only one line in httpd.conf as below (bold line).

<VirtualHost *:80>
    ServerName: xxxxx

    #ProxyPassReverse is not needed
    ProxyPass /log4j ws://localhost:4711/logs
<VirtualHost *:80>

Apache version is 2.4.6 on CentOS.

xml.LoadData - Data at the root level is invalid. Line 1, position 1

The issue here was that myString had that header line. Either there was some hidden character at the beginning of the first line or the line itself was causing the error. I sliced off the first line like so:


This solved my problem.

How can I remove specific rules from iptables?

Use -D command, this is how man page explains it:

-D, --delete chain rule-specification
-D, --delete chain rulenum
    Delete  one  or more rules from the selected chain.  
    There are two versions of this command: 
    the rule can be specified as a number in the chain (starting at 1 for the first rule) or a rule to match.

Do realize this command, like all other command(-A, -I) works on certain table. If you'are not working on the default table(filter table), use -t TABLENAME to specify that target table.

Delete a rule to match

iptables -D INPUT -i eth0 -p tcp --dport 443 -j ACCEPT

Note: This only deletes the first rule matched. If you have many rules matched(this can happen in iptables), run this several times.

Delete a rule specified as a number

iptables -D INPUT 2

Other than counting the number you can list the line-number with --line-number parameter, for example:

iptables -t nat -nL --line-number

How to embed a PDF?

<iframe src="" 
style="width:600px; height:500px;" frameborder="0"></iframe>

Google docs allows you to embed PDFs, Microsoft Office Docs, and other applications by just linking to their services with an iframe. Its user-friendly, versatile, and attractive.

How do I check if I'm running on Windows in Python?

import platform
is_windows = any(platform.win32_ver())


import sys
is_windows = hasattr(sys, 'getwindowsversion')

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

In my opinion the best practice is to place the CSS file in the header

  <link rel="stylesheet" href="css/layout.css" type="text/css">

and the Javascript file before the closing </body> tag

  <script type="text/javascript" src="script.js"></script>

Also if you have, like you said two CSS files. The browser would use both. If there were any selectors, ie. .content {} that were the same in both CSS files the browser would overwrite the similar properties of the first one with the second one's properties. If that makes sense.

Initializing a struct to 0

If the data is a static or global variable, it is zero-filled by default, so just declare it myStruct _m;

If the data is a local variable or a heap-allocated zone, clear it with memset like:

memset(&m, 0, sizeof(myStruct));

Current compilers (e.g. recent versions of gcc) optimize that quite well in practice. This works only if all zero values (include null pointers and floating point zero) are represented as all zero bits, which is true on all platforms I know about (but the C standard permits implementations where this is false; I know no such implementation).

You could perhaps code myStruct m = {}; or myStruct m = {0}; (even if the first member of myStruct is not a scalar).

My feeling is that using memset for local structures is the best, and it conveys better the fact that at runtime, something has to be done (while usually, global and static data can be understood as initialized at compile time, without any cost at runtime).

Repeat each row of data.frame the number of times specified in a column

in fact. use the methods of vector and index. we can also achieve the same result, and more easier to understand:

rawdata <- data.frame('time' = 1:3, 
           'x1' = 4:6,
           'x2' = 7:9,
           'x3' = 10:12)

rawdata[rep(1, time=2), ] %>% remove_rownames()
#  time x1 x2 x3
# 1    1  4  7 10
# 2    1  4  7 10

mailto link multiple body lines

To get body lines use escape()

body_line =  escape("\n");


href = "mailto:[email protected]?body=hello,"+body_line+"I like this.";

HashMap(key: String, value: ArrayList) returns an Object instead of ArrayList?

Using generics (as in the above answers) is your best bet here. I've just double checked and:

test.put("test", arraylistone); 
ArrayList current = new ArrayList();
current = (ArrayList) test.get("test");

will work as well, through I wouldn't recommend it as the generics ensure that only the correct data is added, rather than trying to do the handling at retrieval time.

Error: No module named psycopg2.extensions

I encountered the No module named psycopg2.extensions error when trying to run pip2 install psycopg2 on a Mac running Mavericks (10.9). I don't think my stack trace included a message about gcc, and it also included a hint:

Error: pg_config executable not found.

Please add the directory containing pg_config to the PATH
or specify the full executable path with the option:

    python build_ext --pg-config /path/to/pg_config build ...

or with the pg_config option in 'setup.cfg'.

I looked for the pg_config file in my Postgres install and added the folder containing it to my path: /Applications/ Your path may be different, especially if you have a different version of Postgres installed - I would just poke around until you find the bin/ folder. After doing this, the installation worked.

Invert colors of an image in CSS or JavaScript

CSS3 has a new filter attribute which will only work in webkit browsers supported in webkit browsers and in Firefox. It does not have support in IE or Opera mini:

img {_x000D_
   -webkit-filter: invert(1);_x000D_
   filter: invert(1);_x000D_
<img src="">

how to use python2.7 pip instead of default pip

An alternative is to call the pip module by using python2.7, as below:

python2.7 -m pip <commands>

For example, you could run python2.7 -m pip install <package> to install your favorite python modules. Here is a reference:

In case the pip module has not yet been installed for this version of python, you can run the following:

python2.7 -m ensurepip

Running this command will "bootstrap the pip installer". Note that running this may require administrative privileges (i.e. sudo). Here is a reference: and another reference

Visual Studio SignTool.exe Not Found

The SignTool is available as part of the Windows SDK (which comes with Visual Studio Community 2015). Make sure to select the "ClickOnce Publishing Tools" from the feature list during the installation of Visual Studio 2015 to get the SignTool.

Once Visual Studio is installed you can run the signtool command from the Visual Studio Command Prompt. By default (on Windows 10) the SignTool will be installed at C:\Program Files (x86)\Windows Kits\10\bin\x86\signtool.exe.

ClickOnce Publishing Tools Installation:

enter image description here

SignTool Location:

enter image description here

CSS flexbox vertically/horizontally center image WITHOUT explicitely defining parent height

Just add the following rules to the parent element:

display: flex;
justify-content: center; /* align horizontal */
align-items: center; /* align vertical */

Here's a sample demo (Resize window to see the image align)

Browser support for Flexbox nowadays is quite good.

For cross-browser compatibility for display: flex and align-items, you can add the older flexbox syntax as well:

display: -webkit-box;
display: -webkit-flex;
display: -moz-box;
display: -ms-flexbox;
display: flex;
-webkit-flex-align: center;
-ms-flex-align: center;
-webkit-align-items: center;
align-items: center;

stdcall and cdecl

The caller and the callee need to use the same convention at the point of invokation - that's the only way it could reliably work. Both the caller and the callee follow a predefined protocol - for example, who needs to clean up the stack. If conventions mismatch your program runs into undefined behavior - likely just crashes spectacularly.

This is only required per invokation site - the calling code itself can be a function with any calling convention.

You shouldn't notice any real difference in performance between those conventions. If that becomes a problem you usually need to make less calls - for example, change the algorithm.

Breaking up long strings on multiple lines in Ruby without stripping newlines

Three years later, there is now a solution in Ruby 2.3: The squiggly heredoc.

class Subscription
  def warning_message
      Subscription expiring soon!
      Your free trial will expire in #{days_until_expiration} days.
      Please update your billing information.

Blog post link:

The indentation of the least-indented line will be removed from each line of the content.

R adding days to a date

In addition to the simple addition shown by others, you can also use seq.Date or seq.POSIXt to find other increments or decrements (the POSIXt version does seconds, minutes, hours, etc.):

> seq.Date( Sys.Date(), length=2, by='3 months' )[2]
[1] "2012-07-25"

Unable to find velocity template resources

I faced the similar problem with intellij IDEA. you can use this

 VelocityEngine ve = new VelocityEngine();
    Properties props = new Properties();
    props.put("file.resource.loader.path", "/Users/Projects/Comparator/src/main/resources/");

    Template t = ve.getTemplate("helloworld.vm");
    VelocityContext context = new VelocityContext();

Copy array items into another array

Here's the ES6 way

var newArray = [];_x000D_
let dataArray1 = [1,2,3,4]_x000D_
let dataArray2 = [5,6,7,8]_x000D_
newArray = [...dataArray1, ...dataArray2]_x000D_

The above method is good to go for most of the cases and the cases it is not please consider concat, like you have hundred thousands of items in arrays.

    let dataArray1 = [1,2,3,4]_x000D_
    let dataArray2 = [5,6,7,8]_x000D_
    let newArray = dataArray1.concat(dataArray2);_x000D_

Interfaces — What's the point?

The simplest way to think about interfaces is to recognize what inheritance means. If class CC inherits class C, it means both that:

  1. Class CC can use any public or protected members of class C as though they were its own, and thus only needs to implement things which do not exist in the parent class.
  2. A reference to a CC can be passed or assigned to a routine or variable that expects a reference to a C.

Those two function of inheritance are in some sense independent; although inheritance applies both simultaneously, it is also possible to apply the second without the first. This is useful because allowing an object to inherit members from two or more unrelated classes is much more complicated than allowing one type of thing to be substitutable for multiple types.

An interface is somewhat like an abstract base class, but with a key difference: an object which inherits a base class cannot inherit any other class. By contrast, an object may implement an interface without affecting its ability to inherit any desired class or implement any other interfaces.

One nice feature of this (underutilized in the .net framework, IMHO) is that they make it possible to indicate declaratively the things an object can do. Some objects, for example, will want data-source object from which they can retrieve things by index (as is possible with a List), but they won't need to store anything there. Other routines will need a data-depository object where they can store things not by index (as with Collection.Add), but they won't need to read anything back. Some data types will allow access by index, but won't allow writing; others will allow writing, but won't allow access by index. Some, of course, will allow both.

If ReadableByIndex and Appendable were unrelated base classes, it would be impossible to define a type which could be passed both to things expecting a ReadableByIndex and things expecting an Appendable. One could try to mitigate this by having ReadableByIndex or Appendable derive from the other; the derived class would have to make available public members for both purposes, but warn that some public members might not actually work. Some of Microsoft's classes and interfaces do that, but that's rather icky. A cleaner approach is to have interfaces for the different purposes, and then have objects implement interfaces for the things they can actually do. If one had an interface IReadableByIndex and another interface IAppendable, classes which could do one or the other could implement the appropriate interfaces for the things they can do.

How to make an "alias" for a long path?

Maybe it's better to use links

Soft Link

Symbolic or soft link (files or directories, more flexible and self documenting)

#      Source                            Link
ln -s /home/jake/doc/test/2000/something /home/jake/xxx

Hard Link

Hard link (files only, less flexible and not self documenting)

#    Source                            Link
ln /home/jake/doc/test/2000/something /home/jake/xxx

How to create a link to a directory

Hint: If you need not to see the link in your home you can start it with a dot . ; then it will be hidden by default then you can access it like

cd ~/.myHiddelLongDirLink

Change SVN repository URL

If U want commit to a new empty Repo ,You can checkout the new empty Repo and commit to new remote repo.
chekout a new empty Repo won't delete your local files.
try this: for example, remote repo url : cd [YOUR PROJECT PATH] rm -rf .svn svn co ../[YOUR PROJECT DIR NAME] svn add ./* svn ci -m"changed repo url"

Update data on a page without refreshing

Suppose you want to display some live feed content (say livefeed.txt) on you web page without any page refresh then the following simplified example is for you.

In the below html file, the live data gets updated on the div element of id "liveData"


<!DOCTYPE html>
    <title>Live Update</title>
    <meta charset="UTF-8">
    <script type="text/javascript" src="autoUpdate.js"></script>
<div id="liveData">
    <p>Loading Data...</p>

Below autoUpdate.js reads the live data using XMLHttpRequest object and updates the html div element on every 1 second. I have given comments on most part of the code for better understanding.


window.addEventListener('load', function()
    var xhr = null;

    getXmlHttpRequestObject = function()
            // Create a new XMLHttpRequest object 
            xhr = new XMLHttpRequest();
        return xhr;

    updateLiveData = function()
        var now = new Date();
        // Date string is appended as a query with live data 
        // for not to use the cached version 
        var url = 'livefeed.txt?' + now.getTime();
        xhr = getXmlHttpRequestObject();
        xhr.onreadystatechange = evenHandler;
        // asynchronous requests"GET", url, true);
        // Send the request over the network


    function evenHandler()
        // Check response is ready or not
        if(xhr.readyState == 4 && xhr.status == 200)
            dataDiv = document.getElementById('liveData');
            // Set current data text
            dataDiv.innerHTML = xhr.responseText;
            // Update the live data every 1 sec
            setTimeout(updateLiveData(), 1000);

For testing purpose: Just write some thing in the livefeed.txt - You will get updated the same in index.html without any refresh.



Note: You need to run the above code on the web server (ex: http://localhost:1234/index.html) not as a client html file (ex: file:///C:/index.html).

To get specific part of a string in c#

Your question is vague (are you always looking for the first part?), but you can get the exact output you asked for with string.Split:

string[] substrings = a.Split(',');
b = substrings[0];



Comparing two NumPy arrays for equality, element-wise

Usually two arrays will have some small numeric errors,

You can use numpy.allclose(A,B), instead of (A==B).all(). This returns a bool True/False

How do I remove the "extended attributes" on a file in Mac OS X?

Removing a Single Attribute on a Single File

See Bavarious's answer.

To Remove All Extended Attributes On a Single File

Use xattr with the -c flag to "clear" the attributes:

xattr -c yourfile.txt

To Remove All Extended Attributes On Many Files

To recursively remove extended attributes on all files in a directory, combine the -c "clear" flag with the -r recursive flag:

xattr -rc /path/to/directory

A Tip for Mac OS X Users

Have a long path with spaces or special characters?

Open and start typing xattr -rc, include a trailing space, and then then drag the file or folder to the window and it will automatically add the full path with proper escaping.

Set form backcolor to custom color

With Winforms you can use Form.BackColor to do this.
From within the Form's code:

BackColor = Color.LightPink;

If you mean a WPF Window you can use the Background property.
From within the Window's code:

Background = Brushes.LightPink;

CSS class for pointer cursor

Unfortunately there is no such class in Bootstrap as of now (27th Jan 2019).

I scanned through bootstrap code and discovered following classes that use cursor: pointer. Seems like it is not a good idea to use any of them specifically for cursor: pointer.

summary {
  display: list-item;
  cursor: pointer;
.btn:not(:disabled):not(.disabled) {
  cursor: pointer;
.custom-range::-webkit-slider-runnable-track {
  width: 100%;
  height: 0.5rem;
  color: transparent;
  cursor: pointer;
  background-color: #dee2e6;
  border-color: transparent;
  border-radius: 1rem;
.custom-range::-moz-range-track {
  width: 100%;
  height: 0.5rem;
  color: transparent;
  cursor: pointer;
  background-color: #dee2e6;
  border-color: transparent;
  border-radius: 1rem;
.custom-range::-ms-track {
  width: 100%;
  height: 0.5rem;
  color: transparent;
  cursor: pointer;
  background-color: transparent;
  border-color: transparent;
  border-width: 0.5rem;
.navbar-toggler:not(:disabled):not(.disabled) {
  cursor: pointer;
.page-link:not(:disabled):not(.disabled) {
  cursor: pointer;
.close:not(:disabled):not(.disabled) {
  cursor: pointer;
.carousel-indicators li {
  box-sizing: content-box;
  -ms-flex: 0 1 auto;
  flex: 0 1 auto;
  width: 30px;
  height: 3px;
  margin-right: 3px;
  margin-left: 3px;
  text-indent: -999px;
  cursor: pointer;
  background-color: #fff;
  background-clip: padding-box;
  border-top: 10px solid transparent;
  border-bottom: 10px solid transparent;
  opacity: .5;
  transition: opacity 0.6s ease;


What I would suggest you is just to create a class in your common css as cursor-pointer. That is simple and elegant as of now.

  cursor: pointer;_x000D_
<div class="cursor-pointer">Hover on  me</div>

Convert to absolute value in Objective-C

You can use this function to get the absolute value:

+(NSNumber *)absoluteValue:(NSNumber *)input {
  return [NSNumber numberWithDouble:fabs([input doubleValue])];

How to keep :active css style after click a button


:active denotes the interaction state (so for a button will be applied during press), :focus may be a better choice here. However, the styling will be lost once another element gains focus.

The final potential alternative using CSS would be to use :target, assuming the items being clicked are setting routes (e.g. anchors) within the page- however this can be interrupted if you are using routing (e.g. Angular), however this doesnt seem the case here.

.active:active {_x000D_
  color: red;_x000D_
.focus:focus {_x000D_
  color: red;_x000D_
:target {_x000D_
  color: red;_x000D_
<button class='active'>Active</button>_x000D_
<button class='focus'>Focus</button>_x000D_
<a href='#target1' id='target1' class='target'>Target 1</a>_x000D_
<a href='#target2' id='target2' class='target'>Target 2</a>_x000D_
<a href='#target3' id='target3' class='target'>Target 3</a>

Javascript / jQuery

As such, there is no way in CSS to absolutely toggle a styled state- if none of the above work for you, you will either need to combine with a change in your HTML (e.g. based on a checkbox) or programatically apply/remove a class using e.g. jQuery

$('button').on('click', function(){_x000D_
<script src=""></script>_x000D_

Getting byte array through input type = file


As noted in comments above, while still on some UA implementations, readAsBinaryString method didn't made its way to the specs and should not be used in production. Instead, use readAsArrayBuffer and loop through it's buffer to get back the binary string :

document.querySelector('input').addEventListener('change', function() {_x000D_
  var reader = new FileReader();_x000D_
  reader.onload = function() {_x000D_
    var arrayBuffer = this.result,_x000D_
      array = new Uint8Array(arrayBuffer),_x000D_
      binaryString = String.fromCharCode.apply(null, array);_x000D_
}, false);
<input type="file" />_x000D_
<div id="result"></div>

For a more robust way to convert your arrayBuffer in binary string, you can refer to this answer.

[old answer] (modified)

Yes, the file API does provide a way to convert your File, in the <input type="file"/> to a binary string, thanks to the FileReader Object and its method readAsBinaryString.
[But don't use it in production !]

document.querySelector('input').addEventListener('change', function(){_x000D_
    var reader = new FileReader();_x000D_
    reader.onload = function(){_x000D_
        var binaryString = this.result;_x000D_
        document.querySelector('#result').innerHTML = binaryString;_x000D_
  }, false);
<input type="file"/>_x000D_
<div id="result"></div>

If you want an array buffer, then you can use the readAsArrayBuffer() method :

document.querySelector('input').addEventListener('change', function(){_x000D_
    var reader = new FileReader();_x000D_
    reader.onload = function(){_x000D_
        var arrayBuffer = this.result;_x000D_
        document.querySelector('#result').innerHTML = arrayBuffer + '  '+arrayBuffer.byteLength;_x000D_
  }, false);
<input type="file"/>_x000D_
<div id="result"></div>

Conditional operator in Python?

simple is the best and works in every version.

if a>10: 

long long in C/C++


num3 = 100000000000LL;

And BTW, in C++ this is a compiler extension, the standard does not define long long, thats part of C99.

How can I pause setInterval() functions?

While @Jonas Giuro is right when saying that:

You cannot PAUSE the setInterval function, you can either STOP it (clearInterval), or let it run

On the other hand this behavior can be simulated with approach @VitaliyG suggested:

You shouldn't measure time in interval function. Instead just save time when timer was started and measure difference when timer was stopped/paused. Use setInterval only to update displayed value.

var output = $('h1');_x000D_
var isPaused = false;_x000D_
var time = new Date();_x000D_
var offset = 0;_x000D_
var t = window.setInterval(function() {_x000D_
  if(!isPaused) {_x000D_
    var milisec = offset + (new Date()).getTime() - time.getTime();_x000D_
    output.text(parseInt(milisec / 1000) + "s " + (milisec % 1000));_x000D_
}, 10);_x000D_
//with jquery_x000D_
$('.toggle').on('click', function(e) {_x000D_
  isPaused = !isPaused;_x000D_
  if (isPaused) {_x000D_
    offset += (new Date()).getTime() - time.getTime();_x000D_
  } else {_x000D_
    time = new Date();_x000D_
h1 {_x000D_
    font-family: Helvetica, Verdana, sans-serif;_x000D_
    font-size: 12px;_x000D_
<script src=""></script>_x000D_
<h1>Seconds: 0</h1>_x000D_
<button class="toggle">Toggle</button>

How can I make an EXE file from a Python program?


py2exe is a Python Distutils extension which converts Python scripts into executable Windows programs, able to run without requiring a Python installation.

Maven : error in opening zip file when running maven

This issue is a pain in my a$$, I have this issue in my Mac, if I run

mvn clean install | grep "error reading"
[ERROR] error reading /Users/ducnguyen/.m2/repository/org/apache/velocity/velocity/1.7/velocity-1.7.jar; error in opening zip file
[ERROR] error reading /Users/ducnguyen/.m2/repository/commons-net/commons-net/3.3/commons-net-3.3.jar; error in opening zip file
[ERROR] error reading /Users/ducnguyen/.m2/repository/org/apache/commons/commons-lang3/3.0/commons-lang3-3.0.jar; error in opening zip file
[ERROR] error reading /Users/ducnguyen/.m2/repository/org/bouncycastle/bcprov-jdk15on/1.54/bcprov-jdk15on-1.54.jar; error in opening zip file
[ERROR] error reading /Users/ducnguyen/.m2/repository/javax/mail/mail/1.4/mail-1.4.jar; error in opening zip file
[ERROR] error reading /Users/ducnguyen/.m2/repository/org/apache/pdfbox/pdfbox/2.0.0/pdfbox-2.0.0.jar; error in opening zip file
[ERROR] error reading /Users/ducnguyen/.m2/repository/com/itextpdf/itextpdf/5.5.10/itextpdf-5.5.10.jar; error in opening zip file
[ERROR] error reading /Users/ducnguyen/.m2/repository/org/slf4j/slf4j-api/1.7.24/slf4j-api-1.7.24.jar; error in opening zip file
[ERROR] error reading /Users/ducnguyen/.m2/repository/com/aspose/aspose-pdf/11.5.0/aspose-pdf-11.5.0.jar; error in opening zip file
[ERROR] error reading /Users/ducnguyen/.m2/repository/org/apache/velocity/velocity/1.7/velocity-1.7.jar; error in opening zip file
[ERROR] error reading /Users/ducnguyen/.m2/repository/commons-net/commons-net/3.3/commons-net-3.3.jar; error in opening zip file
[ERROR] error reading /Users/ducnguyen/.m2/repository/org/apache/commons/commons-lang3/3.0/commons-lang3-3.0.jar; error in opening zip file
[ERROR] error reading /Users/ducnguyen/.m2/repository/org/bouncycastle/bcprov-jdk15on/1.54/bcprov-jdk15on-1.54.jar; error in opening zip file
[ERROR] error reading /Users/ducnguyen/.m2/repository/javax/mail/mail/1.4/mail-1.4.jar; error in opening zip file
[ERROR] error reading /Users/ducnguyen/.m2/repository/org/apache/pdfbox/pdfbox/2.0.0/pdfbox-2.0.0.jar; error in opening zip file
[ERROR] error reading /Users/ducnguyen/.m2/repository/com/itextpdf/itextpdf/5.5.10/itextpdf-5.5.10.jar; error in opening zip file
[ERROR] error reading /Users/ducnguyen/.m2/repository/org/slf4j/slf4j-api/1.7.24/slf4j-api-1.7.24.jar; error in opening zip file

Removing all corrupted libs is the only solution

So I want to remove all of them at once.

mvn clean install | grep "error reading" | awk '{print "rm " $4 | "/bin/sh"  }'

The command needs AWK to take libPath string from column $4

Then rerun

mvn clean install

How to open a web server port on EC2 instance

Follow the steps that are described on this answer just instead of using the drop down, type the port (8787) in "port range" an then "Add rule".

Go to the "Network & Security" -> Security Group settings in the left hand navigation

enter image description here Find the Security Group that your instance is apart of Click on Inbound Rules enter image description here Use the drop down and add HTTP (port 80) enter image description here Click Apply and enjoy

How Stuff and 'For Xml Path' work in SQL Server?

PATH mode is used in generating XML from a SELECT query

1. SELECT   
FROM temp1






The Output is element-centric XML where each column value in the resulting rowset is wrapped in an row element. Because the SELECT clause does not specify any aliases for the column names, the child element names generated are the same as the corresponding column names in the SELECT clause.

For each row in the rowset a tag is added.

FROM temp1


For Step 2: If you specify a zero-length string, the wrapping element is not produced.



    FROM temp1
    FOR XML PATH('');


4. SELECT   
        ',' +Name  
FROM temp1


In Step 4 we are concatenating the values.

    abc = (SELECT   
            ',' +Name  
    FROM temp1
    FOR XML PATH('') )
FROM temp1

1   ,aaa,bbb,ccc,ddd,eee
1   ,aaa,bbb,ccc,ddd,eee
1   ,aaa,bbb,ccc,ddd,eee
1   ,aaa,bbb,ccc,ddd,eee
1   ,aaa,bbb,ccc,ddd,eee

    abc = (SELECT   
            ',' +Name  
    FROM temp1
    FOR XML PATH('') )
FROM temp1 GROUP by iD

ID  abc
1   ,aaa,bbb,ccc,ddd,eee

In Step 6 we are grouping the date by ID.

STUFF( source_string, start, length, add_string ) Parameters or Arguments source_string The source string to modify. start The position in the source_string to delete length characters and then insert add_string. length The number of characters to delete from source_string. add_string The sequence of characters to insert into the source_string at the start position.

    abc = 
    STUFF (
                ',' +Name  
        FROM temp1
        FOR XML PATH('')), 1, 1, ''
FROM temp1 GROUP by iD

| Id        | Name                |
| 1         | aaa,bbb,ccc,ddd,eee |

How do I see active SQL Server connections?

Apart from sp_who, you can also use the "undocumented" sp_who2 system stored procedure which gives you more detailed information. See Difference between sp_who and sp_who2.

Declare an empty two-dimensional array in Javascript?


Matrix m with size 3 rows and 5 columns (remove .fill(0) to not init by zero)


let Array2D = (r,c) => [...Array(r)].map(x=>Array(c).fill(0));

let m = Array2D(3,5);

m[1][0] = 2;  // second row, first column
m[2][4] = 8;  // last row, last column

// print formated array
  .replace(/(\[\[)(.*)(\]\])/g,'[\n  [$2]\n]').replace(/],/g,'],\n  ')

Turn off iPhone/Safari input element rounding

If you use normalize.css, that stylesheet will do something like input[type="search"] { -webkit-appearance: textfield; }.

This has a higher specificity than a single class selector like .foo, so be aware that you then can't do just .my-field { -webkit-appearance: none; }. If you have no better way to achieve the right specificity, this will help:

.my-field { -webkit-appearance: none !important; }

How to plot a 2D FFT in Matlab?

Here is an example from my HOW TO Matlab page:

close all; clear all;

img   = imread('lena.tif','tif');
img   = fftshift(img(:,:,2));
F     = fft2(img);


imagesc(100*log(1+abs(fftshift(F)))); colormap(gray); 
title('magnitude spectrum');

imagesc(angle(F));  colormap(gray);
title('phase spectrum');

This gives the magnitude spectrum and phase spectrum of the image. I used a color image, but you can easily adjust it to use gray image as well.

ps. I just noticed that on Matlab 2012a the above image is no longer included. So, just replace the first line above with say

img = imread('ngc6543a.jpg');

and it will work. I used an older version of Matlab to make the above example and just copied it here.

On the scaling factor

When we plot the 2D Fourier transform magnitude, we need to scale the pixel values using log transform to expand the range of the dark pixels into the bright region so we can better see the transform. We use a c value in the equation

s = c log(1+r) 

There is no known way to pre detrmine this scale that I know. Just need to try different values to get on you like. I used 100 in the above example.

enter image description here

Using Pandas to pd.read_excel() for multiple worksheets of the same workbook

If you are interested in reading all sheets and merging them together. The best and fastest way to do it

sheet_to_df_map = pd.read_excel('path_to_file.xls', sheet_name=None)
mdf = pd.concat(sheet_to_df_map, axis=0, ignore_index=True)

This will convert all the sheet into a single data frame m_df

Batch: Remove file extension

Using cygwin bash to do the chopping

  :: e.g. FILE=basename.mp4 => FILE_NO_EXT=basename
  set FILE=%1
  for /f "delims=" %%a in ('bash -c "FILE=%FILE%; echo ${FILE/.*/}" ') do set FILE_NO_EXT=%%a

Find object by id in an array of JavaScript objects

As long as the browser supports ECMA-262, 5th edition (December 2009), this should work, almost one-liner:

var bFound = myArray.some(function (obj) {
    return === 45;

How to get values and keys from HashMap?

Map is internally made up of Map.Entry objects. Each Entry contains key and value. To get key and value from the entry you use accessor and modifier methods.

If you want to get values with given key, use get() method and to insert value, use put() method.

#Define and initialize map;
Map map = new HashMap();

map.get("Germany") // returns 4

If you want to get the set of keys from map, you can use keySet() method

Set keys = map.keySet();
System.out.println("All keys are: " + keys);
// To get all key: value
for(String key: keys){
    System.out.println(key + ": " + map.get(key));

Generally, To get all keys and values from the map, you have to follow the sequence in the following order:

  • Convert Hashmap to MapSet to get set of entries in Map with entryset() method.:
    Set st = map.entrySet();
  • Get the iterator of this set:
    Iterator it = st.iterator();
  • Get Map.Entry from the iterator:
    Map.Entry entry =;
  • use getKey() and getValue() methods of the Map.Entry to get keys and values.
// Now access it
Set st = (Set) map.entrySet();
Iterator it = st.iterator();
    Map.Entry entry =;
    System.out.print(entry.getKey() + " : " + entry.getValue());

In short, use iterator directly in for

for(Map.Entry entry:map.entrySet()){
    System.out.print(entry.getKey() + " : " + entry.getValue());

Regex to remove letters, symbols except numbers


var removedText = self.val().replace(/[^0-9]+/, '');

^ - means NOT

The name 'controlname' does not exist in the current context

Check your code behind file name and Inherits property on the @Page directive, make sure they both match.

Why doesn't adding CORS headers to an OPTIONS route allow browsers to access my API?

The easiest answer is to just use the cors package.

const cors = require('cors');

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

That will enable CORS across the board. If you want to learn how to enable CORS without outside modules, all you really need is some Express middleware that sets the 'Access-Control-Allow-Origin' header. That's the minimum you need to allow cross-request domains from a browser to your server.

app.options('*', (req, res) => {
  res.set('Access-Control-Allow-Origin', '*');

app.use((req, res) => {
  res.set('Access-Control-Allow-Origin', '*');

Laravel 5 - redirect to HTTPS

You can make it works with a Middleware class. Let me give you an idea.

namespace MyApp\Http\Middleware;

use Closure;
use Illuminate\Support\Facades\App;

class HttpsProtocol {

    public function handle($request, Closure $next)
            if (!$request->secure() && App::environment() === 'production') {
                return redirect()->secure($request->getRequestUri());

            return $next($request); 

Then, apply this middleware to every request adding setting the rule at Kernel.php file, like so:

protected $middleware = [

    // appending custom middleware 


At sample above, the middleware will redirect every request to https if:

  1. The current request comes with no secure protocol (http)
  2. If your environment is equals to production. So, just adjust the settings according to your preferences.


I am using this code in production environment with a WildCard SSL and the code works correctly. If I remove && App::environment() === 'production' and test it in localhost, the redirection also works. So, having or not a installed SSL is not the problem. Looks like you need to keep a very hard attention to your Cloudflare layer in order to get redirected to Https protocol.

Edit 23/03/2015

Thanks to @Adam Link's suggestion: it is likely caused by the headers that Cloudflare is passing. CloudFlare likely hits your server via HTTP and passes a X-Forwarded-Proto header that declares it is forwarding a HTTPS request. You need add another line in your Middleware that say...

$request->setTrustedProxies( [ $request->getClientIp() ] ); trust the headers CloudFlare is sending. This will stop the redirect loop

Edit 27/09/2016 - Laravel v5.3

Just need to add the middleware class into web group in kernel.php file:

protected $middlewareGroups = [
    'web' => [

        // here


Remember that web group is applied to every route by default, so you do not need to set web explicitly in routes nor controllers.

Edit 23/08/2018 - Laravel v5.7

  • To redirect a request depending the environment you can use App::environment() === 'production'. For previous version was env('APP_ENV') === 'production'.
  • Using \URL::forceScheme('https'); actually does not redirect. It just builds links with https:// once the website is rendered.

PowerShell script to check the status of a URL

I recently set up a script that does this.

As David Brabant pointed out, you can use the System.Net.WebRequest class to do an HTTP request.

To check whether it is operational, you should use the following example code:

# First we create the request.
$HTTP_Request = [System.Net.WebRequest]::Create('')

# We then get a response from the site.
$HTTP_Response = $HTTP_Request.GetResponse()

# We then get the HTTP code as an integer.
$HTTP_Status = [int]$HTTP_Response.StatusCode

If ($HTTP_Status -eq 200) {
    Write-Host "Site is OK!"
Else {
    Write-Host "The Site may be down, please check!"

# Finally, we clean up the http request by closing it.
If ($HTTP_Response -eq $null) { } 
Else { $HTTP_Response.Close() }

How to right-align form input boxes?

Try this:

<!DOCTYPE html>
    <style type="text/css">
    p {
        text-align: right;
    input {
        width: 100px;

            <input name="declared_first" value="above" />
            <input name="declared_second" value="below" />

How to add composite primary key to table

You don't need to create the table first and then add the keys in subsequent steps. You can add both primary key and foreign key while creating the table:

This example assumes the existence of a table (Codes) that we would want to reference with our foreign key.

id [numeric](1),
code [varchar](2),
PRIMARY KEY (id, code),
CONSTRAINT fk_d_codes FOREIGN KEY (code) REFERENCES Codes (code)

If you don't have a table that we can reference, add one like this so that the example will work:

    Code [varchar](2) PRIMARY KEY   

NOTE: you must have a table to reference before creating the foreign key.

How to check certificate name and alias in keystore files?

This will list all certificates:

keytool -list -keystore "$JAVA_HOME/jre/lib/security/cacerts"

How to clear gradle cache?

Gradle cache is located at

  • On Windows: %USERPROFILE%\.gradle\caches
  • On Mac / UNIX: ~/.gradle/caches/

You can browse to these directory and manually delete it or run

rm -rf $HOME/.gradle/caches/

on UNIX system. Run this command will also force to download dependencies.


Clear the Android build cache of current project

NOTE: Android Studio's File > Invalidate Caches / Restart doesn't clear the Android build cache, so you'll have to clean it separately.

On Windows:

gradlew cleanBuildCache

On Mac or UNIX:

./gradlew cleanBuildCache

RegEx to parse or validate Base64 data

The best regexp which I could find up till now is in here

which is in the current version looks like:

module.exports = function (opts) {
  opts = opts || {};
  var regex = '(?:[A-Za-z0-9+\/]{4}\\n?)*(?:[A-Za-z0-9+\/]{2}==|[A-Za-z0-9+\/]{3}=)';

  return opts.exact ? new RegExp('(?:^' + regex + '$)') :
                    new RegExp('(?:^|\\s)' + regex, 'g');

How to check if string contains Latin characters only?

Ahh, found the answer myself:

if (/[a-zA-Z]/.test(num)) {
  alert('Letter Found')

error LNK2001: unresolved external symbol (C++)

That means that the definition of your function is not present in your program. You forgot to add that one.cpp to your program.

What "to add" means in this case depends on your build environment and its terminology. In MSVC (since you are apparently use MSVC) you'd have to add one.cpp to the project.

In more practical terms, applicable to all typical build methodologies, when you link you program, the object file created form one.cpp is missing.

Python: Removing list element while iterating over list

You can still use filter, moving to an outside function the element modification (iterating just once)

def do_the_magic(x):
    return check(x)

# you can get a different filtered list

# or have it modified in place (as suggested by Steven Rumbalski, see comment)
yourList[:] = itertools.ifilter(do_the_magic, yourList)

How do I install a Python package with a .whl file?

First, make sure you have updated pip to enable wheel support:

pip install --upgrade pip

Then, to install from wheel, give it the directory where the wheel is downloaded. For example, to install package_name.whl:

pip install --use-wheel --no-index --find-links=/where/its/downloaded package_name

HRESULT: 0x800A03EC on Worksheet.range

I agree with Hugh W post "I conclude that the same error code is used to indicate multiple unrelated problems"

Other posts have not mentioned that this error occurs frequently if the worksheet is locked. While I haven't tested every scenario, it seems that anything that you can not do in excel when a worksheet is locked with throw this error if you attempt to do it via VSTO/Com while the sheet is locked. E.G. Changing any style artifact (font, font size, colour, underline), changing the Excel Validation, changing the column widths, row heights, formulas

How do I use Comparator to define a custom sort order?

Define one Enum Type as

public enum Colors {

Change data type of color from String to Colors Change return type and argument type of getter and setter method of color to Colors

Define comparator type as follows

static class ColorComparator implements Comparator<CarSort>
    public int compare(CarSort c1, CarSort c2)
        return c1.getColor().compareTo(c2.getColor());

after adding elements to List, call sort method of Collection by passing list and comparator objects as arguments

i.e, Collections.sort(carList, new ColorComparator()); then print using ListIterator.

full class implementation is as follows:

package test;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;    
import java.util.ListIterator;

public class CarSort implements Comparable<CarSort>{

    String name;
    Colors color;

    public CarSort(String name, Colors color){ = name;
        this.color = color;

    public String getName() {
        return name;
    public void setName(String name) { = name;
    public Colors getColor() {
        return color;
    public void setColor(Colors color) {
        this.color = color;

    //Implement the natural order for this class
    public int compareTo(CarSort c)
        return getName().compareTo(c.getName());

    static class ColorComparator implements Comparator<CarSort>
        public int compare(CarSort c1, CarSort c2)
            return c1.getColor().compareTo(c2.getColor());

    public enum Colors {

     public static void main(String[] args)
         List<CarSort> carList = new ArrayList<CarSort>();
         List<String> sortOrder = new ArrayList<String>();

         carList.add(new CarSort("Ford Figo",Colors.SILVER));
         carList.add(new CarSort("Santro",Colors.BLUE));
         carList.add(new CarSort("Honda Jazz",Colors.MAGENTA));
         carList.add(new CarSort("Indigo V2",Colors.RED));
         Collections.sort(carList, new ColorComparator());

         ListIterator<CarSort> itr=carList.listIterator();
         while (itr.hasNext()) {
            CarSort carSort = (CarSort);
            System.out.println("Car colors: "+carSort.getColor());

How do I create a multiline Python string with inline variables?

If anyone came here from python-graphql client looking for a solution to pass an object as variable here's what I used:

query = """
  pairs(block: {block} first: 200, orderBy: trackedReserveETH, orderDirection: desc) {{
""".format(block=''.join(['{number: ', str(block), '}']))

 query = gql(query)

Make sure to escape all curly braces like I did: "{{", "}}"

How to get evaluated attributes inside a custom directive

Notice: I do update this answer as I find better solutions. I also keep the old answers for future reference as long as they remain related. Latest and best answer comes first.

Better answer:

Directives in angularjs are very powerful, but it takes time to comprehend which processes lie behind them.

While creating directives, angularjs allows you to create an isolated scope with some bindings to the parent scope. These bindings are specified by the attribute you attach the element in DOM and how you define scope property in the directive definition object.

There are 3 types of binding options which you can define in scope and you write those as prefixes related attribute.

angular.module("myApp", []).directive("myDirective", function () {
    return {
        restrict: "A",
        scope: {
            text: "@myText",
            twoWayBind: "=myTwoWayBind",
            oneWayBind: "&myOneWayBind"
}).controller("myController", function ($scope) {
    $ = {name: "Umur"};
    $ = "qwe";


<div ng-controller="myController">
    <div my-directive my-text="hello {{ bar }}" my-two-way-bind="foo" my-one-way-bind="bar">

In that case, in the scope of directive (whether it's in linking function or controller), we can access these properties like this:

/* Directive scope */

in: $scope.text
out: "hello qwe"
// this would automatically update the changes of value in digest
// this is always string as dom attributes values are always strings

in: $scope.twoWayBind
out: {name:"Umur"}
// this would automatically update the changes of value in digest
// changes in this will be reflected in parent scope

// in directive's scope
in: $ = "John"

//in parent scope
in: $
out: "John"

in: $scope.oneWayBind() // notice the function call, this binding is read only
out: "qwe"
// any changes here will not reflect in parent, as this only a getter .

"Still OK" Answer:

Since this answer got accepted, but has some issues, I'm going to update it to a better one. Apparently, $parse is a service which does not lie in properties of the current scope, which means it only takes angular expressions and cannot reach scope. {{,}} expressions are compiled while angularjs initiating which means when we try to access them in our directives postlink method, they are already compiled. ({{1+1}} is 2 in directive already).

This is how you would want to use:

var myApp = angular.module('myApp',[]);

myApp.directive('myDirective', function ($parse) {
    return function (scope, element, attr) {
        element.val("value=" + $parse(attr.myDirective)(scope));

function MyCtrl($scope) {
    $ = 3432;


<div ng-controller="MyCtrl">
    <input my-directive="123">
    <input my-directive="1+1">
    <input my-directive="'1+1'">
    <input my-directive="aaa">

One thing you should notice here is that, if you want set the value string, you should wrap it in quotes. (See 3rd input)

Here is the fiddle to play with:

Old Answer:

I'm not removing this for folks who can be misled like me, note that using $eval is perfectly fine the correct way to do it, but $parse has a different behavior, you probably won't need this to use in most of the cases.

The way to do it is, once again, using scope.$eval. Not only it compiles the angular expression, it has also access to the current scope's properties.

var myApp = angular.module('myApp',[]);

myApp.directive('myDirective', function () {
    return function (scope, element, attr) {
        element.val("value = "+ scope.$eval(attr.value));

function MyCtrl($scope) {

What you are missing was $eval.$rootScope.Scope#$eval

Executes the expression on the current scope returning the result. Any exceptions in the expression are propagated (uncaught). This is useful when evaluating angular expressions.

"%%" and "%/%" for the remainder and the quotient

Have a look at the examples below for a clearer understanding of the differences between the different operators:

> # Floating Division:
> 5/2
[1] 2.5
> # Integer Division:
> 5%/%2
[1] 2
> # Remainder:
> 5%%2
[1] 1

error: ‘NULL’ was not declared in this scope

NULL isn't a keyword; it's a macro substitution for 0, and comes in stddef.h or cstddef, I believe. You haven't #included an appropriate header file, so g++ sees NULL as a regular variable name, and you haven't declared it.

Open web in new tab Selenium + Python

Opening the new empty tab within same window in chrome browser is not possible up to my knowledge but you can open the new tab with web-link.

So far I surfed net and I got good working content on this question. Please try to follow the steps without missing.

import selenium.webdriver as webdriver
from selenium.webdriver.common.keys import Keys

driver = webdriver.Chrome()
first_link = driver.find_element_by_class_name('l')

# Use: Keys.CONTROL + Keys.SHIFT + Keys.RETURN to open tab on top of the stack 
first_link.send_keys(Keys.CONTROL + Keys.RETURN)

# Switch tab to the new tab, which we will assume is the next one on the right
driver.find_element_by_tag_name('body').send_keys(Keys.CONTROL + Keys.TAB)


I think this is better solution so far.


Getting "unixtime" in Java

Avoid the Date object creation w/ System.currentTimeMillis(). A divide by 1000 gets you to Unix epoch.

As mentioned in a comment, you typically want a primitive long (lower-case-l long) not a boxed object long (capital-L Long) for the unixTime variable's type.

long unixTime = System.currentTimeMillis() / 1000L;

jQuery AJAX form using mail() PHP script sends email, but POST data from HTML form is undefined

You're using the wrong post parameters:

    var dataString = 'name='+ name + '&email=' + email + '&text=' + text;

The javascript/html IDs are irrelevant to the actual POST, especially when you're building your own data string and don't use those same IDs.

SQL - How to find the highest number in a column?

You can do


laravel foreach loop in controller

Is sku just a property of the Product model? If so:

$products = Product::whereOwnerAndStatus($owner, 0)->take($count)->get();

foreach ($products as $product ) {
  // Access $product->sku here...

Or is sku a relationship to another model? If that is the case, then, as long as your relationship is setup properly, you code should work.

How to convert a PNG image to a SVG?

I'm assuming that you wish to write software to do this. To do it naively you would just find lines and set the vectors. To do it intelligently, you attempt to fit shapes onto the drawing (model fitting). Additionally, you should attempt to ascertain bitmaped regions (regions you can't model through shames or applying textures. I would not recommend going this route as that it will take quite a bit of time and require a bit of graphics and computer vision knowledge. However, the output will much and scale much better than your original output.

What is the use of the JavaScript 'bind' method?

Simple Explanation:

bind() create a new function, a new reference at a function it returns to you.

In parameter after this keyword, you pass in the parameter you want to preconfigure. Actually it does not execute immediately, just prepares for execution.

You can preconfigure as many parameters as you want.

Simple Example to understand bind:

function calculate(operation) {
  if (operation === 'ADD') {
   alert('The Operation is Addition');
  } else if (operation === 'SUBTRACT') {
   alert('The Operation is Subtraction');

addBtn.addEventListener('click', calculate.bind(this, 'ADD'));
subtractBtn.addEventListener('click', calculate.bind(this, 'SUBTRACT'));

How to exclude particular class name in CSS selector?

One way is to use the multiple class selector (no space as that is the descendant selector):

.reMode_hover:not(.reMode_selected):hover _x000D_
   background-color: #f0ac00;_x000D_
<a href="" title="Design" class="reMode_design  reMode_hover">_x000D_
<a href="" title="Design" _x000D_
 class="reMode_design  reMode_hover reMode_selected">_x000D_

How do you pass a function as a parameter in C?

Since C++11 you can use the functional library to do this in a succinct and generic fashion. The syntax is, e.g.,

std::function<bool (int)>

where bool is the return type here of a one-argument function whose first argument is of type int.

I have included an example program below:

// g++ test.cpp --std=c++11
#include <functional>

double Combiner(double a, double b, std::function<double (double,double)> func){
  return func(a,b);

double Add(double a, double b){
  return a+b;

double Mult(double a, double b){
  return a*b;

int main(){

Sometimes, though, it is more convenient to use a template function:

// g++ test.cpp --std=c++11

template<class T>
double Combiner(double a, double b, T func){
  return func(a,b);

double Add(double a, double b){
  return a+b;

double Mult(double a, double b){
  return a*b;

int main(){

SASS and @font-face

For those looking for an SCSS mixin instead, including woff2:

@mixin fface($path, $family, $type: '', $weight: 400, $svg: '', $style: normal) {
  @font-face {
    font-family: $family;
    @if $svg == '' {
      // with OTF without SVG and EOT
      src: url('#{$path}#{$type}.otf') format('opentype'), url('#{$path}#{$type}.woff2') format('woff2'), url('#{$path}#{$type}.woff') format('woff'), url('#{$path}#{$type}.ttf') format('truetype');
    } @else {
      // traditional src inclusions
      src: url('#{$path}#{$type}.eot');
      src: url('#{$path}#{$type}.eot?#iefix') format('embedded-opentype'), url('#{$path}#{$type}.woff2') format('woff2'), url('#{$path}#{$type}.woff') format('woff'), url('#{$path}#{$type}.ttf') format('truetype'), url('#{$path}#{$type}.svg##{$svg}') format('svg');
    font-weight: $weight;
    font-style: $style;
// ========================================================importing
$dir: '/assets/fonts/';
$famatic: 'AmaticSC';
@include fface('#{$dir}amatic-sc-v11-latin-regular', $famatic, '', 400, $famatic);

$finter: 'Inter';
// adding specific types of font-weights
@include fface('#{$dir}#{$finter}', $finter, '-Thin-BETA', 100);
@include fface('#{$dir}#{$finter}', $finter, '-Regular', 400);
@include fface('#{$dir}#{$finter}', $finter, '-Medium', 500);
@include fface('#{$dir}#{$finter}', $finter, '-Bold', 700);
// ========================================================usage
.title {
  font-family: Inter;
  font-weight: 700; // Inter-Bold font is loaded
.special-title {
  font-family: AmaticSC;
  font-weight: 700; // default font is loaded

The $type parameter is useful for stacking related families with different weights.

The @if is due to the need of supporting the Inter font (similar to Roboto), which has OTF but doesn't have SVG and EOT types at this time.

If you get a can't resolve error, remember to double check your fonts directory ($dir).

How can I change Eclipse theme?

Update December 2012 (19 months later):

The blog post "Jin Mingjian: Eclipse Darker Theme" mentions this GitHub repo "eclipse themes - darker":

enter image description here

The big fun is that, the codes are minimized by using Eclipse4 platform technologies like dependency injection.
It proves that again, the concise codes and advanced features could be achieved by contributing or extending with the external form (like library, framework).
New language is not necessary just for this kind of purpose.

Update July 2012 (14 months later):

With the latest Eclipse4.2 (June 2012, "Juno") release, you can implement what I originally described below: a CSS-based fully dark theme for Eclipse.
See the article by Lars Vogel in "Eclipse 4 is beautiful – Create your own Eclipse 4 theme":

Eclipse fully dark theme

If you want to play with it, you only need to write a plug-in, create a CSS file and use the org.eclipse.e4.ui.css.swt.theme extension point to point to your file.
If you export your plug-in, place it in the “dropins” folder of your Eclipse installation and your styling is available.

Original answer: August 2011

With Eclipse 3.x, theme is only for the editors, as you can see in the site "Eclipse Color Themes".
Anything around that is managed by windows system colors.
That is what you need to change to have any influence on Eclipse global colors around editors.

Eclipse 4 will provide much advance theme options: See "Eclipse 4.0 – So you can theme me Part 1" and "Eclipse 4.0 RCP: Dynamic CSS Theme Switching".

dark theme

How to compare types

If your instance is a Type:

Type typeFiled;
if (typeField == typeof(string))

but if your instance is an object and not a Type use the as operator:

object value;
string text = value as string;
if (text != null)
    // value is a string and you can do your work here

this has the advantage to convert value only once into the specified type.

How to display databases in Oracle 11g using SQL*Plus

SELECT NAME FROM v$database; shows the database name in oracle

How to change the integrated terminal in visual studio code or VSCode

To change the integrated terminal on Windows, you just need to change the line:

  1. Open VS User Settings (Preferences > User Settings). This will open two side-by-side documents.
  2. Add a new "": "C:\\Bin\\Cmder\\Cmder.exe" setting to the User Settings document on the right if it's not already there. This is so you aren't editing the Default Setting directly, but instead adding to it.
  3. Save the User Settings file.

You can then access it with keys Ctrl+backtick by default.

how to access parent window object using jquery?

or you can use another approach:

$( "#serverMsg", window.opener.document )

Convert Char to String in C

To answer the question without reading too much else into it i would

char str[2] = "\0"; /* gives {\0, \0} */
str[0] = fgetc(fp);

You could use the second line in a loop with what ever other string operations you want to keep using char's as strings.

Git log to get commits only for a specific branch

I finally found the way to do what the OP wanted. It's as simple as:

git log --graph [branchname]

The command will display all commits that are reachable from the provided branch in the format of graph. But, you can easily filter all commits on that branch by looking at the commits graph whose * is the first character in the commit line.

For example, let's look at the excerpt of git log --graph master on cakephp GitHub repo below:

D:\Web Folder\cakephp>git log --graph master
*   commit 8314c2ff833280bbc7102cb6d4fcf62240cd3ac4
|\  Merge: c3f45e8 0459a35
| | Author: José Lorenzo Rodríguez <[email protected]>
| | Date:   Tue Aug 30 08:01:59 2016 +0200
| |
| |     Merge pull request #9367 from cakephp/fewer-allocations
| |
| |     Do fewer allocations for simple default values.
| |
| * commit 0459a35689fec80bd8dca41e31d244a126d9e15e
| | Author: Mark Story <[email protected]>
| | Date:   Mon Aug 29 22:21:16 2016 -0400
| |
| |     The action should only be defaulted when there are no patterns
| |
| |     Only default the action name when there is no default & no pattern
| |     defined.
| |
| * commit 80c123b9dbd1c1b3301ec1270adc6c07824aeb5c
| | Author: Mark Story <[email protected]>
| | Date:   Sun Aug 28 22:35:20 2016 -0400
| |
| |     Do fewer allocations for simple default values.
| |
| |     Don't allocate arrays when we are only assigning a single array key
| |     value.
| |
* |   commit c3f45e811e4b49fe27624b57c3eb8f4721a4323b
|\ \  Merge: 10e5734 43178fd
| |/  Author: Mark Story <[email protected]>
|/|   Date:   Mon Aug 29 22:15:30 2016 -0400
| |
| |       Merge pull request #9322 from cakephp/add-email-assertions
| |
| |       Add email assertions trait
| |
| * commit 43178fd55d7ef9a42706279fa275bb783063cf34
| | Author: Jad Bitar <[email protected]>
| | Date:   Mon Aug 29 17:43:29 2016 -0400
| |
| |     Fix `@since` in new files docblocks
| |

As you can see, only commits 8314c2ff833280bbc7102cb6d4fcf62240cd3ac4 and c3f45e811e4b49fe27624b57c3eb8f4721a4323b have the * being the first character in the commit lines. Those commits are from the master branch while the other four are from some other branches.

How to iterate over a std::map full of strings in C++

Change your append calls to say



... append(iter->second)

Additionally, the line

std::string* strToReturn = new std::string("");

allocates a string on the heap. If you intend to actually return a pointer to this dynamically allocated string, the return should be changed to std::string*.

Alternatively, if you don't want to worry about managing that object on the heap, change the local declaration to

std::string strToReturn("");

and change the 'append' calls to use reference syntax...


instead of


Be aware that this will construct the string on the stack, then copy it into the return variable. This has performance implications.

How can I display an image from a file in Jupyter Notebook?

If you are trying to display an Image in this way inside a loop, then you need to wrap the Image constructor in a display method.

from IPython.display import Image, display

listOfImageNames = ['/path/to/images/1.png',

for imageName in listOfImageNames:

How can I pass POST parameters in a URL?

This could work if the PHP script generates a form for each entry with hidden fields and the href uses JavaScript to post the form.

How Many Seconds Between Two Dates?

Just subtract:

var a = new Date();
alert("Wait a few seconds, then click OK");

var b = new Date();
var difference = (b - a) / 1000;

alert("You waited: " + difference + " seconds");

How to replace all strings to numbers contained in each string in Notepad++?

I have Notepad++ v6.8.8

Find: [([a-zA-Z])]

Replace: [\'\1\']

Will produce: $array[XYZ] => $array['XYZ']

How to copy from CSV file to PostgreSQL table with headers in CSV file?

With the Python library pandas, you can easily create column names and infer data types from a csv file.

from sqlalchemy import create_engine
import pandas as pd

engine = create_engine('postgresql://user:pass@localhost/db_name')
df = pd.read_csv('/path/to/csv_file')
df.to_sql('pandas_db', engine)

The if_exists parameter can be set to replace or append to an existing table, e.g. df.to_sql('pandas_db', engine, if_exists='replace'). This works for additional input file types as well, docs here and here.

How do I add a border to an image in HTML?

The answers above are very good I'm sure. But for dim-wits, like me, I recommend Snagit 10. You can give an image a border in any width, style, and color before inserting it into your webpage. They do a full working program on 30 day trial.

Javascript to open popup window and disable parent window

The key term is modal-dialog.

As such there is no built in modal-dialog offered.

But you can use many others available e.g. this

Node.js on multi-core machines

You can use cluster module. Check this.

var cluster = require('cluster');
var http = require('http');
var numCPUs = require('os').cpus().length;

if (cluster.isMaster) {
    // Fork workers.
    for (var i = 0; i < numCPUs; i++) {

    cluster.on('exit', function(worker, code, signal) {
        console.log('worker ' + + ' died');
} else {
    // Workers can share any TCP connection
    // In this case its a HTTP server
    http.createServer(function(req, res) {
        res.end("hello world\n");

Calling a class method raises a TypeError in Python

You never created an instance.

You've defined average as an instance method, thus, in order to use average you need to create an instance first.

How to get CRON to call in the correct PATHs

The default environment for cron jobs is very sparse and may be very different from the environment you develop your python scripts in. For a script that might be run in cron, any environment that you depend on should be set explicitly. In the cron file itself, include full paths to python executables and to your python scripts.

javascript: get a function's variable's value within another function

the OOP way to do this in ES5 is to make that variable into a property using the this keyword.

function first(){

function second() {
    y=new first();

Connection to SQL Server Works Sometimes

I had the same problem, manage to solve it by opening/enabling the port 1433 and tcp/ip in SQL Server Configuration Manager and then Restarted the Server

enter image description here

Cannot send a content-body with this verb-type

Because you didn't specify the Header.

I've added an extended example:

var request = (HttpWebRequest)WebRequest.Create(strServer + strURL.Split('&')[1].ToString());

Header(ref request, p_Method);

And the method Header:

private void Header(ref HttpWebRequest p_request, string p_Method)
    p_request.ContentType = "application/x-www-form-urlencoded";
    p_request.Method = p_Method;
    p_request.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows CE)";
    p_request.Host = strServer.Split('/')[2].ToString();
    p_request.Accept = "*/*";
    if (String.IsNullOrEmpty(strURLReferer))
        p_request.Referer = strServer;
        p_request.Referer = strURLReferer;
    p_request.Headers.Add("Accept-Language", "en-us\r\n");
    p_request.Headers.Add("UA-CPU", "x86 \r\n");
    p_request.Headers.Add("Cache-Control", "no-cache\r\n");
    p_request.KeepAlive = true;

Cannot find the declaration of element 'beans'

Add this code ..It helped me

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="" 

Where does application data file actually stored on android device?

Application Private Data files are stored within <internal_storage>/data/data/<package>

Files being stored in the internal storage can be accessed with openFileOutput() and openFileInput()

When those files are created as MODE_PRIVATE it is not possible to see/access them within another application such as a FileManager.

Sending XML data using HTTP POST with PHP

you can use cURL library for posting data:

$ch = curl_init();
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch, CURLOPT_URL, "http://websiteURL");
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, "XML=".$xmlcontent."&password=".$password."&etc=etc");

where postfield contains XML you need to send - you will need to name the postfield the API service (Clickatell I guess) expects

How to execute a raw update sql with dynamic binding in rails

In Rails 3.1, you should use the query interface:

  • new(attributes)
  • create(attributes)
  • create!(attributes)
  • find(id_or_array)
  • destroy(id_or_array)
  • destroy_all
  • delete(id_or_array)
  • delete_all
  • update(ids, updates)
  • update_all(updates)
  • exists?

update and update_all are the operation you need.

See details here:

Number of days between two dates in Joda-Time

DateTime  dt  = new DateTime(laterDate);        

DateTime newDate = dt.minus( new  DateTime ( previousDate ).getMillis());

System.out.println("No of days : " + newDate.getDayOfYear() - 1 );    

Subtract days from a DateTime

The dateTime.AddDays(-1) does not subtract that one day from the dateTime reference. It will return a new instance, with that one day subtracted from the original reference.

DateTime dateTime = DateTime.Now;
DateTime otherDateTime = dateTime.AddDays(-1);

How do I generate a constructor from class fields using Visual Studio (and/or ReSharper)?

I'm using the following trick:

I select the declaration of the class with the data-members and press:

Ctrl+C, Shift+Ctrl+C, Ctrl+V.

  • The first command copies the declaration to the clipboard,
  • The second command is a shortcut that invokes the PROGRAM
  • The last command overwrites the selection by text from the clipboard.

The PROGRAM gets the declaration from the clipboard, finds the name of the class, finds all members and their types, generates constructor and copies it all back into the clipboard.

We are doing it with freshmen on my "Programming-I" practice (Charles University, Prague) and most of students gets it done till the end of the hour.

If you want to see the source code, let me know.

How to correctly link php-fpm and Nginx Docker containers?

I think we also need to give the fpm container the volume, dont we? So =>

    image: php:fpm
        - ./:/var/www/test/

If i dont do this, i run into this exception when firing a request, as fpm cannot find requested file:

[error] 6#6: *4 FastCGI sent in stderr: "Primary script unknown" while reading response header from upstream, client:, server: localhost, request: "GET / HTTP/1.1", upstream: "fastcgi://", host: "localhost"

Mocking a function to raise an Exception to test an except block

Your mock is raising the exception just fine, but the error.resp.status value is missing. Rather than use return_value, just tell Mock that status is an attribute:

barMock.side_effect = HttpError(mock.Mock(status=404), 'not found')

Additional keyword arguments to Mock() are set as attributes on the resulting object.

I put your foo and bar definitions in a my_tests module, added in the HttpError class so I could use it too, and your test then can be ran to success:

>>> from my_tests import foo, HttpError
>>> import mock
>>> with mock.patch('') as barMock:
...     barMock.side_effect = HttpError(mock.Mock(status=404), 'not found')
...     result =
404 - 
>>> result is None

You can even see the print '404 - %s' % error.message line run, but I think you wanted to use error.content there instead; that's the attribute HttpError() sets from the second argument, at any rate.

How do I change the android actionbar title and icon

The action bar title will, by default, use the label of the current activity, but you can also set it programmatically via ActionBar.setTitle().

To implement the "Back" (more precisely, "Up") button functionality you're talking about, read the "Using the App Icon for Navigation" section of the Action Bar developer guide.

Finally, to change the icon, the guide covers that as well. In short, the action bar will display the image supplied in android:icon in your manifest's application or activity element, if there is one. The typical practice is to create an application icon (in all of the various densities you'll need) named ic_launcher.png, and place it in your drawable-* directories.

What do column flags mean in MySQL Workbench?

PK - Primary Key

NN - Not Null

BIN - Binary (stores data as binary strings. There is no character set so sorting and comparison is based on the numeric values of the bytes in the values.)

UN - Unsigned (non-negative numbers only. so if the range is -500 to 500, instead its 0 - 1000, the range is the same but it starts at 0)

UQ - Create/remove Unique Key

ZF - Zero-Filled (if the length is 5 like INT(5) then every field is filled with 0’s to the 5th digit. 12 = 00012, 400 = 00400, etc. )

AI - Auto Increment

G - Generated column. i.e. value generated by a formula based on the other columns

The type List is not generic; it cannot be parameterized with arguments [HTTPClient]

I got the same error, but when i did as below, it resolved the issue.
Instead of writing like this:

List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(1);

use the below one:

ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(1);

SQL Query to add a new column after an existing column in SQL Server 2005

According to my research there is no way to do this exactly the way you want. You can manually re-create the table and copy the data, or SSMS can (and will) do this for you (when you drag and drop a column to a different order, it does this). In fact it souldn't matter what order the columns are... As an alternative solution you can select the data you want in the order you desired. For example, instead of using asterisk (*) in select, specify the column names in some order... Lets say MyTable has col1, col2, col3, colNew columns.

Instead of:


You can use:

SELECT col1, colNew, col2, col3 FROM MyTable

How to replace unicode characters in string with something else python?

  1. Decode the string to Unicode. Assuming it's UTF-8-encoded:

  2. Call the replace method and be sure to pass it a Unicode string as its first argument:

    str.decode("utf-8").replace(u"\u2022", "*")
  3. Encode back to UTF-8, if needed:

    str.decode("utf-8").replace(u"\u2022", "*").encode("utf-8")

(Fortunately, Python 3 puts a stop to this mess. Step 3 should really only be performed just prior to I/O. Also, mind you that calling a string str shadows the built-in type str.)

REST API Best practices: Where to put parameters?

As per the REST Implementation,

1) Path variables are used for the direct action on the resources, like a contact or a song ex..
GET etc /api/resource/{songid} or
GET etc /api/resource/{contactid} will return respective data.

2) Query perms/argument are used for the in-direct resources like metadata of a song ex.., GET /api/resource/{songid}?metadata=genres it will return the genres data for that particular song.

PyCharm shows unresolved references error for valid code

In my case it was the directories structure. My project looks like this:


So right click on dir_b > "mark directory as" > "project root"

Select all where [first letter starts with B]

SQL Statement:

 SELECT * FROM employee WHERE employeeName LIKE 'A%';


Number of Records: 4

employeeID  employeeName    employeeName    Address City    PostalCode  Country

1           Alam             Wipro          Delhi   Delhi   11005      India

2           Aditya           Wipro          Delhi   Delhi   11005      India

3           Alok             HCL            Delhi   Delhi   11005      India

4           Ashok            IBM            Delhi   Delhi   11005      India

How to inject a Map using the @Value Spring Annotation?

Following worked for me:

SpingBoot 2.1.7.RELEASE

YAML Property (Notice value sourrounded by single quotes)

   name: '{"key1": false, "key2": false, "key3": true}'

In Java/Kotlin annotate field with (Notice use of #) (For java no need to escape '$' with '\')


SQL Not Like Statement not working

If WPP.COMMENT contains NULL, the condition will not match.

This query:


will return nothing.

On a NULL column, both LIKE and NOT LIKE against any search string will return NULL.

Could you please post relevant values of a row which in your opinion should be returned but it isn't?

How can I specify a display?

I through vnc to understand the X11 more. To specify the display to get a many-displayed program, export DISPLAY=IP:DisplayNum.ScreenNum

For example,

vncserver :2
vncserver -list
export DISPLAY=:2  # export DISPLAY=IP:DisplayNum or export DISPLAY=:DisplayNum for localhost; So that can vnc connect and see the vnc desktop :2 if $DISPLAY is not :2.

SQL Error: ORA-00913: too many values

The 00947 message indicates that the record which you are trying to send to Oracle lacks one or more of the columns which was included at the time the table was created. The 00913 message indicates that the record which you are trying to send to Oracle includes more columns than were included at the time the table was created. You just need to check the number of columns and its type in both the tables ie the tables that are involved in the sql.

Vue is not defined

I got this error but as undefined due to the way I included js files

Initailly i had

<script src="~/vue/blade-account-update-credit-card-vue.js" asp-append-version="true"></script>
<script src="~/lib/vue/vue_v2.5.16.js"></script>

in the end of my .cshtml page GOT Error Vue not Defined but later I changed it to

<script src="~/lib/vue/vue_v2.5.16.js"></script> 
<script src="~/vue/blade-account-update-credit-card-vue.js" asp-append-version="true"></script>

and magically it worked. So i assume that vue js needs to be loaded on top of the .vue

How to link to part of the same document in Markdown?

Since MultiMarkdown was mentioned as an option in comments.

In MultiMarkdown the syntax for an internal link is simple.

For any heading in the document simply give the heading name in this format [heading][] to create an internal link.

Read more here: MultiMarkdown-5 Cross-references.


An oft-requested feature was the ability to have Markdown automatically handle within-document links as easily as it handled external links. To this aim, I added the ability to interpret [Some Text][] as a cross-link, if a header named “Some Text” exists.

As an example, [Metadata][] will take you to # Metadata (or any of ## Metadata, ### Metadata, #### Metadata, ##### Metadata, ###### Metadata).

Alternatively, you can include an optional label of your choosing to help disambiguate cases where multiple headers have the same title:

### Overview [MultiMarkdownOverview] ##

This allows you to use [MultiMarkdownOverview] to refer to this section specifically, and not another section named Overview. This works with atx- or settext-style headers.

If you have already defined an anchor using the same id that is used by a header, then the defined anchor takes precedence.

In addition to headers within the document, you can provide labels for images and tables which can then be used for cross-references as well.

JavaScript TypeError: Cannot read property 'style' of null

In your script, this part:


must be returning null and you are also attempting to set the display property to an invalid value. There are a couple of possible reasons for this first part to be null.

  1. You are running the script too early before the document has been loaded and thus the Noite item can't be found.

  2. There is no Noite item in your HTML.

I should point out that your use of document.write() in this case code probably signifies a problem. If the document has already loaded, then a new document.write() will clear the old content and start a new fresh document so no Noite item would be found.

If your document has not yet been loaded and thus you're doing document.write() inline to add HTML inline to the current document, then your document has not yet been fully loaded so that's probably why it can't find the Noite item.

The solution is probably to put this part of your script at the very end of your document so everything before it has already been loaded. So move this to the end of your body:


And, make sure that there are no document.write() statements in javascript after the document has been loaded (because they will clear the previous document and start a new one).

In addition, setting the display property to "display" doesn't make sense to me. The valid options for that are "block", "inline", "none", "table", etc... I'm not aware of any option named "display" for that style property. See here for valid options for teh display property.

You can see the fixed code work here in this demo: That jsFiddle is configured to have the javascript placed at the end of the document body so it runs after the document has been loaded.

P.S. I should point out that your lack of braces for your if statements and your inclusion of multiple statements on the same line makes your code very misleading and unclear.

I'm having a really hard time figuring out what you're asking, but here's a cleaned up version of your code that works which you can also see working here: Here's a list of the changes I made:

  1. The script is located in the body, but after the content that it is referencing.
  2. I've added var declarations to your variables (a good habit to always use).
  3. The if statement was changed into an if/else which is a lot more efficient and more self-documenting as to what you're doing.
  4. I've added braces for every if statement so it absolutely clear which statements are part of the if/else and which are not.
  5. I've properly closed the </dd> tag you were inserting.
  6. I've changed style.display = ''; to style.display = 'block';.
  7. I've added semicolons at the end of every statement (another good habit to follow).

The code:

<div id="Night" style="display: none;">
    <img src="Img/night.png" style="position: fixed; top: 0px; left: 5%; height: auto; width: 100%; z-index: -2147483640;">
    <img src="Img/moon.gif" style="position: fixed; top: 0px; left: 5%; height: 100%; width: auto; z-index: -2147483639;">
var day = new Date();
var hr = day.getHours();
if (hr == 0) {
    document.write("Meia-noite!<br>Já é amanhã!");
} else if (hr <=5 ) {
    document.write("&nbsp;&nbsp;Você não<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;devia<br>&nbsp;&nbsp;&nbsp;&nbsp;estar<br>dormindo?");
} else if (hr <= 11) {         
    document.write("Bom dia!");
} else if (hr == 12) {
} else if (hr <= 17) {
    document.write("Boa Tarde");
} else if (hr <= 19) {
    document.write("&nbsp;Bom final<br>&nbsp;de tarde!");
} else if (hr == 20) {
    document.write("&nbsp;Boa Noite"); 
} else if (hr == 21) {
    document.write("&nbsp;Boa Noite"); 
} else if (hr == 22) {
    document.write("&nbsp;Boa Noite");
} else if (hr == 23) {
    document.write("Ó Meu! Já é quase meia-noite!");

How to parse JSON using Node.js?

Use this to be on the safe side

var data = JSON.parse(Buffer.concat(arr).toString());

MySQL search and replace some text in a field

Change table_name and field to match your table name and field in question:

UPDATE table_name SET field = REPLACE(field, 'foo', 'bar') WHERE INSTR(field, 'foo') > 0;

What are the best practices for using a GUID as a primary key, specifically regarding performance?

GUIDs may seem to be a natural choice for your primary key - and if you really must, you could probably argue to use it for the PRIMARY KEY of the table. What I'd strongly recommend not to do is use the GUID column as the clustering key, which SQL Server does by default, unless you specifically tell it not to.

You really need to keep two issues apart:

  1. the primary key is a logical construct - one of the candidate keys that uniquely and reliably identifies every row in your table. This can be anything, really - an INT, a GUID, a string - pick what makes most sense for your scenario.

  2. the clustering key (the column or columns that define the "clustered index" on the table) - this is a physical storage-related thing, and here, a small, stable, ever-increasing data type is your best pick - INT or BIGINT as your default option.

By default, the primary key on a SQL Server table is also used as the clustering key - but that doesn't need to be that way! I've personally seen massive performance gains when breaking up the previous GUID-based Primary / Clustered Key into two separate key - the primary (logical) key on the GUID, and the clustering (ordering) key on a separate INT IDENTITY(1,1) column.

As Kimberly Tripp - the Queen of Indexing - and others have stated a great many times - a GUID as the clustering key isn't optimal, since due to its randomness, it will lead to massive page and index fragmentation and to generally bad performance.

Yes, I know - there's newsequentialid() in SQL Server 2005 and up - but even that is not truly and fully sequential and thus also suffers from the same problems as the GUID - just a bit less prominently so.

Then there's another issue to consider: the clustering key on a table will be added to each and every entry on each and every non-clustered index on your table as well - thus you really want to make sure it's as small as possible. Typically, an INT with 2+ billion rows should be sufficient for the vast majority of tables - and compared to a GUID as the clustering key, you can save yourself hundreds of megabytes of storage on disk and in server memory.

Quick calculation - using INT vs. GUID as Primary and Clustering Key:

  • Base Table with 1'000'000 rows (3.8 MB vs. 15.26 MB)
  • 6 nonclustered indexes (22.89 MB vs. 91.55 MB)

TOTAL: 25 MB vs. 106 MB - and that's just on a single table!

Some more food for thought - excellent stuff by Kimberly Tripp - read it, read it again, digest it! It's the SQL Server indexing gospel, really.

PS: of course, if you're dealing with just a few hundred or a few thousand rows - most of these arguments won't really have much of an impact on you. However: if you get into the tens or hundreds of thousands of rows, or you start counting in millions - then those points become very crucial and very important to understand.

Update: if you want to have your PKGUID column as your primary key (but not your clustering key), and another column MYINT (INT IDENTITY) as your clustering key - use this:

 .... add more columns as needed ...... )



Basically: you just have to explicitly tell the PRIMARY KEY constraint that it's NONCLUSTERED (otherwise it's created as your clustered index, by default) - and then you create a second index that's defined as CLUSTERED

This will work - and it's a valid option if you have an existing system that needs to be "re-engineered" for performance. For a new system, if you start from scratch, and you're not in a replication scenario, then I'd always pick ID INT IDENTITY(1,1) as my clustered primary key - much more efficient than anything else!

Authentication plugin 'caching_sha2_password' cannot be loaded

Here is the solution which worked for me after MySQL 8.0 Installation on Windows 10.

Suppose MySQL username is root and password is admin

Open command prompt and enter the following commands:

cd C:\Program Files\MySQL\MySQL Server 8.0\bin

mysql_upgrade -uroot -padmin

mysql -uroot -padmin

ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'admin'

Create File If File Does Not Exist

You can simply call

using (StreamWriter w = File.AppendText("log.txt"))

It will create the file if it doesn't exist and open the file for appending.


This is sufficient:

string path = txtFilePath.Text;               
using(StreamWriter sw = File.AppendText(path))
  foreach (var line in employeeList.Items)                 
    Employee e = (Employee)line; // unbox once

But if you insist on checking first, you can do something like this, but I don't see the point.

string path = txtFilePath.Text;               

using (StreamWriter sw = (File.Exists(path)) ? File.AppendText(path) : File.CreateText(path))                 
    foreach (var line in employeeList.Items)                     

Also, one thing to point out with your code is that you're doing a lot of unnecessary unboxing. If you have to use a plain (non-generic) collection like ArrayList, then unbox the object once and use the reference.

However, I perfer to use List<> for my collections:

public class EmployeeList : List<Employee>

ES6 map an array of objects, to return an array of objects with new keys

You just need to wrap object in ()

var arr = [{_x000D_
  id: 1,_x000D_
  name: 'bill'_x000D_
}, {_x000D_
  id: 2,_x000D_
  name: 'ted'_x000D_
var result = => ({ value:, text: }));_x000D_

Create a 3D matrix

If you want to define a 3D matrix containing all zeros, you write

A = zeros(8,4,20);

All ones uses ones, all NaN's uses NaN, all false uses false instead of zeros.

If you have an existing 2D matrix, you can assign an element in the "3rd dimension" and the matrix is augmented to contain the new element. All other new matrix elements that have to be added to do that are set to zero.

For example

B = magic(3); %# creates a 3x3 magic square
B(2,1,2) = 1; %# and you have a 3x3x2 array

How to convert answer into two decimal point

Ran into this problem today and I wrote a function for it. In my particular case, I needed to make sure all values were at least 0 (hence the "LT0" name) and were rounded to two decimal places.

        Private Function LT0(ByVal Input As Decimal, Optional ByVal Precision As Int16 = 2) As Decimal

            ' returns 0 for all values less than 0, the decimal rounded to (Precision) decimal places otherwise.
            If Input < 0 Then Input = 0
            if Precision < 0 then Precision = 0 ' just in case someone does something stupid.
            Return Decimal.Round(Input, Precision) ' this is the line everyone's probably looking for.

        End Function

css display table cell requires percentage width

Note also that vertical-align:top; is often necessary for correct table cell appearance.

css table-cell, contents have unnecessary top margin

How do I serialize a Python dictionary into a string, and then back to a dictionary?

It depends on what you're wanting to use it for. If you're just trying to save it, you should use pickle (or, if you’re using CPython 2.x, cPickle, which is faster).

>>> import pickle
>>> pickle.dumps({'foo': 'bar'})
>>> pickle.loads(_)
{'foo': 'bar'}

If you want it to be readable, you could use json:

>>> import json
>>> json.dumps({'foo': 'bar'})
'{"foo": "bar"}'
>>> json.loads(_)
{'foo': 'bar'}

json is, however, very limited in what it will support, while pickle can be used for arbitrary objects (if it doesn't work automatically, the class can define __getstate__ to specify precisely how it should be pickled).

>>> pickle.dumps(object())
>>> json.dumps(object())
Traceback (most recent call last):
TypeError: <object object at 0x7fa0348230c0> is not JSON serializable

How to check which PHP extensions have been enabled/disabled in Ubuntu Linux 12.04 LTS?

You can view which modules (compiled in) are available via terminal through php -m

Run batch file as a Windows service

On Windows 2019 Server, you can run a Minecraft java server with these commands:

sc create minecraft-server DisplayName= "minecraft-server" binpath= "cmd.exe /C C:\Users\Administrator\Desktop\rungui1151.lnk" type= own start= auto

The .lnk file is a standard windows shortcut to a batch file.

--- .bat file begins ---

java -Xmx40960M -Xms40960M -d64 -jar minecraft_server.1.15.1.jar

--- .bat file ends ---

All this because:

service does not know how to start in a folder,

cmd.exe does not know how to start in a folder

Starting the service will produce "timely manner" error, but the log file reveals the server is running.

If you need to shut down the server, just go into task manager and find the server java in background processes and end it, or terminate the server from in the game using the /stop command, or for other programs/servers, use the methods relevant to the server.

How to use Utilities.sleep() function

Some Google services do not like to be used to much. Quite recently my account was locked because of script, which was sending two e-mails per second to the same user. Google considered it as a spam. So using sleep here is also justified to prevent such situations.

"Uncaught TypeError: a.indexOf is not a function" error when opening new foundation project

Please add below jQuery Migrate Plugin

<script src=""></script>
<script src=""></script>

How to dynamically add rows to a table in ASP.NET?

Have you attempted the Asp:Table?

<asp:Table ID="myTable" runat="server" Width="100%"> 

You can then add rows as you need to in the script by creating them and adding them to myTable.Rows

TableRow row = new TableRow();
TableCell cell1 = new TableCell();
cell1.Text = "blah blah blah";

Given your question description though, I'd say you'd be better off using a GridView or Repeater as mentioned by @Kirk Woll.

EDIT - Also, if you want to learn without buying books here are a few sites you absolutely need to become familiar with:

Scott Guthrie's Blog
4 Guys from Rolla
Code Project Asp.Net