Programs & Examples On #Returnurl

Is the URL where a user is redirected after being authenticated.

Facebook Callback appends '#_=_' to Return URL

I do not see how this problem is related to facebook AJAX. In fact the issue also occurs with JavaScript disabled and purely redirect based logins.

An example exchange with facebook:

1. GET <> RESPONSE 302 Found Location: <[...]>  
2. GET <[...]> RESPONSE 302 Found MY_REDIRECT_URL?code=FB_CODE#_  

Happens only with Firefox for me too.

Adding an identity to an existing column

You can't alter the existing columns for identity.

You have 2 options,

  1. Create a new table with identity & drop the existing table

  2. Create a new column with identity & drop the existing column

Approach 1. (New table) Here you can retain the existing data values on the newly created identity column. Note that you will lose all data if 'if not exists' is not satisfied, so make sure you put the condition on the drop as well!

CREATE TABLE dbo.Tmp_Names
      Id int NOT NULL
             IDENTITY(1, 1),
      Name varchar(50) NULL


            FROM    dbo.Names ) 
    INSERT  INTO dbo.Tmp_Names ( Id, Name )
            SELECT  Id,
            FROM    dbo.Names TABLOCKX


DROP TABLE dbo.Names

Exec sp_rename 'Tmp_Names', 'Names'

Approach 2 (New column) You can’t retain the existing data values on the newly created identity column, The identity column will hold the sequence of number.

Alter Table Names
Add Id_new Int Identity(1, 1)

Alter Table Names Drop Column ID

Exec sp_rename 'Names.Id_new', 'ID', 'Column'

See the following Microsoft SQL Server Forum post for more details:

How to alter column to identity(1,1)

error while loading shared libraries:

If you are absolutely sure that libncurses, aka ncurses, is installed, as in you've done a successful 'ls' of the library, then perhaps you are running a 64 bit Linux operating system and only have the 64 bit libncurses installed, when the program that is running (adb) is 32 bit.

If so, a 32 bit program can't link to a 64 bit library (and won't located it anyway), so you might have to install libcurses, or ncurses (32 bit version). Likewise, if you are running a 64 bit adb, perhaps your ncurses is 32 bit (a possible but less likely scenario).

How to set 24-hours format for date on java?


The modern approach uses java.time classes.                                        // Capture current moment in UTC.
       .truncatedTo( ChronoUnit.SECONDS )            // Lop off any fractional second.
       .plus( 8 , ChronoUnit.HOURS )                 // Add eight hours.
       .atZone( ZoneId.of( "America/Montreal" ) )    // Adjust from UTC to the wall-clock time used by the people of a certain region (a time zone). Returns a `ZonedDateTime` object.
       .format(                                      // Generate a `String` object representing textually the value of the `ZonedDateTime` object.
           DateTimeFormatter.ofPattern( "dd/MM/uuuu HH:mm:ss" )
                            .withLocale( Locale.US ) // Specify a `Locale` to determine the human language and cultural norms used in localizing the text being generated. 
       )                                             // Returns a `String` object.

23/01/2017 15:34:56


FYI, the old Calendar and Date classes are now legacy. Supplanted by the java.time classes. Much of java.time is back-ported to Java 6, Java 7, and Android (see below).


Capture the current moment in UTC with the Instant class.

Instant instantNow =;

instant.toString(): 2017-01-23T12:34:56.789Z

If you want only whole seconds, without any fraction of a second, truncate.

Instant instant = instantNow.truncatedTo( ChronoUnit.SECONDS );

instant.toString(): 2017-01-23T12:34:56Z


The Instant class can do math, adding an amount of time. Specify the amount of time to add by the ChronoUnit enum, an implementation of TemporalUnit.

instant = 8 , ChronoUnit.HOURS );

instant.toString(): 2017-01-23T20:34:56Z


To see that same moment through the lens of a particular region’s wall-clock time, apply a ZoneId to get a ZonedDateTime.

Specify a proper time zone name in the format of continent/region, such as America/Montreal, Africa/Casablanca, or Pacific/Auckland. Never use the 3-4 letter abbreviation such as EST or IST as they are not true time zones, not standardized, and not even unique(!).

ZoneId z = ZoneId.of( "America/Montreal" );
ZonedDateTime zdt = instant.atZone( z );

zdt.toString(): 2017-01-23T15:34:56-05:00[America/Montreal]

Generate string

You can generate a String in your desired format by specifying a formatting pattern in a DateTimeFormatter object.

Note that case matters in the letters of your formatting pattern. The Question’s code had hh which is for 12-hour time while uppercase HH is 24-hour time (0-23) in both java.time.DateTimeFormatter as well as the legacy java.text.SimpleDateFormat.

The formatting codes in java.time are similar to those in the legacy SimpleDateFormat but not exactly the same. Carefully study the class doc. Here, HH happens to work identically.

DateTimeFormatter f = DateTimeFormatter.ofPattern( "dd/MM/uuuu HH:mm:ss" ).withLocale( Locale.US );
String output = zdt.format( f );

Automatic localization

Rather than hard-coding a formatting pattern, consider letting java.time fully localize the generation of the String text by calling DateTimeFormatter.ofLocalizedDateTime.

And, by the way, be aware that time zone and Locale have nothing to do with one another; orthogonal issues. One is about content, the meaning (the wall-clock time). The other is about presentation, determining the human language and cultural norms used in presenting that meaning to the user.

Instant instant = Instant.parse( "2017-01-23T12:34:56Z" );
ZoneId z = ZoneId.of( "Pacific/Auckland" );  // Notice that time zone is unrelated to the `Locale` used in localizing.
ZonedDateTime zdt = instant.atZone( z );

DateTimeFormatter f = DateTimeFormatter.ofLocalizedDateTime( FormatStyle.FULL )
                                       .withLocale( Locale.CANADA_FRENCH );  // The locale determines human language and cultural norms used in generating the text representing this date-time object.
String output = zdt.format( f );

instant.toString(): 2017-01-23T12:34:56Z

zdt.toString(): 2017-01-24T01:34:56+13:00[Pacific/Auckland]

output: mardi 24 janvier 2017 à 01:34:56 heure avancée de la Nouvelle-Zélande

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.

Where to obtain the java.time classes?


Update: The Joda-Time project is now in maintenance mode, with the team advising migration to the java.time classes.

Joda-Time makes this kind of work much easier.

// © 2013 Basil Bourque. This source code may be used freely forever by anyone taking full responsibility for doing so.
// import org.joda.time.*;
// import org.joda.time.format.*;

DateTime later = 8 );
DateTimeFormatter formatter = DateTimeFormat.forPattern( "dd/MM/yyyy HH:mm:ss" );
String laterAsText = formatter.print( later );

System.out.println( "laterAsText: " + laterAsText );

When run…

laterAsText: 19/12/2013 02:50:18

Beware that this syntax uses default time zone. A better practice is to use an explicit DateTimeZone instance.

Flexbox not giving equal width to elements

There is an important bit that is not mentioned in the article to which you linked and that is flex-basis. By default flex-basis is auto.

From the spec:

If the specified flex-basis is auto, the used flex basis is the value of the flex item’s main size property. (This can itself be the keyword auto, which sizes the flex item based on its contents.)

Each flex item has a flex-basis which is sort of like its initial size. Then from there, any remaining free space is distributed proportionally (based on flex-grow) among the items. With auto, that basis is the contents size (or defined size with width, etc.). As a result, items with bigger text within are being given more space overall in your example.

If you want your elements to be completely even, you can set flex-basis: 0. This will set the flex basis to 0 and then any remaining space (which will be all space since all basises are 0) will be proportionally distributed based on flex-grow.

li {
    flex-grow: 1;
    flex-basis: 0;
    /* ... */

This diagram from the spec does a pretty good job of illustrating the point.

And here is a working example with your fiddle.

New lines (\r\n) are not working in email body

You need to use a <br> because your Content-Type is text/html.

It works without the Content-Type header because then your e-mail will be interpreted as plain text. If you really want to use \n you should use Content-Type: text/plain but then you'll lose any markup.

Also check out similar question here.

How do I find the index of a character within a string in C?

What about:

char *string = "qwerty";
char *e = string;
int idx = 0;
while (*e++ != 'e') idx++;

copying to e to preserve the original string, I suppose if you don't care you could just operate over *string

How do I correctly setup and teardown for my pytest class with tests?

When you write "tests defined as class methods", do you really mean class methods (methods which receive its class as first parameter) or just regular methods (methods which receive an instance as first parameter)?

Since your example uses self for the test methods I'm assuming the latter, so you just need to use setup_method instead:

class Test:

    def setup_method(self, test_method):
        # configure self.attribute

    def teardown_method(self, test_method):
        # tear down self.attribute

    def test_buttons(self):
        # use self.attribute for test

The test method instance is passed to setup_method and teardown_method, but can be ignored if your setup/teardown code doesn't need to know the testing context. More information can be found here.

I also recommend that you familiarize yourself with py.test's fixtures, as they are a more powerful concept.

How to keep the local file or the remote file during merge using Git and the command line?

git checkout {branch-name} -- {file-name}

This will use the file from the branch of choice.

I like this because posh-git autocomplete works great with this. It also removes any ambiguity as to which branch is remote and which is local. And --theirs didn't work for me anyways. cannot open shared object file: No such file or directory

/usr/local/cilk/bin/../lib32/pinbin is dynamically linked to a library which is not present anymore. You need to recompile Cilk

What's the difference between JavaScript and JScript?

As far as I can tell, two things:

  1. ActiveXObject constructor
  2. The idiom f(x) = y, which is roughly equivalent to f[x] = y.

How to find minimum value from vector?

std::min_element(vec.begin(), vec.end()) - for std::vector
std::min_element(v, v+n) - for array
std::min_element( std::begin(v), std::end(v) ) - added C++11 version from comment by @JamesKanze

POSTing JsonObject With HttpClient From Web API

With the new version of HttpClient and without the WebApi package it would be:

var content = new StringContent(jsonObject.ToString(), Encoding.UTF8, "application/json");
var result = client.PostAsync(url, content).Result;

Or if you want it async:

var result = await client.PostAsync(url, content);

ArrayList of int array in java

For the more inexperienced, I have decided to add an example to demonstrate how to input and output an ArrayList of Integer arrays based on this question here.

    ArrayList<Integer[]> arrayList = new ArrayList<Integer[]>();
    while(n > 0)
        int d = scan.nextInt();
       Integer temp[] = new Integer[d];
        for (int i = 0 ; i < d ; i++)
            int t = scan.nextInt();
    }//n is the size of the ArrayList that has been taken as a user input & d is the size 
    //of each individual array.

     //to print something  out from this ArrayList, we take in two 
    // values,index and index1 which is the number of the line we want and 
    // and the position of the element within that line (since the question
    // followed a 1-based numbering scheme, I did not change it here)


Thanks to this answer on this question here, I got the correct answer. I believe this satisfactorily answers OP's question, albeit a little late and can serve as an explanation for those with less experience.

How to list all functions in a Python module?

This will do the trick:


However, if you find it annoying to read the returned list, just use the following loop to get one name per line.

for i in dir(module): print i

How do you programmatically set an attribute?

Usually, we define classes for this.

class XClass( object ):
   def __init__( self ):
       self.myAttr= None

x= XClass()
x.myAttr= 'magic'

However, you can, to an extent, do this with the setattr and getattr built-in functions. However, they don't work on instances of object directly.

>>> a= object()
>>> setattr( a, 'hi', 'mom' )
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'object' object has no attribute 'hi'

They do, however, work on all kinds of simple classes.

class YClass( object ):

y= YClass()
setattr( y, 'myAttr', 'magic' )

npm ERR! network getaddrinfo ENOTFOUND

does your proxy require you to authenticate? because if it does, you might want you configure your proxy like this.

placeholder names. username is a placeholder for your actual username. password is a placeholder for your actual password. is a placeholder for your actualy proxy *port" is your actualy port the proxy goes through. its usualy 8080

npm config set proxy "http://username:[email protected]:port"
npm config set https-proxy "http://username:[email protected]:port"

How can I split and parse a string in Python?

"2.7.0_bf4fda703454".split("_") gives a list of strings:

In [1]: "2.7.0_bf4fda703454".split("_")
Out[1]: ['2.7.0', 'bf4fda703454']

This splits the string at every underscore. If you want it to stop after the first split, use "2.7.0_bf4fda703454".split("_", 1).

If you know for a fact that the string contains an underscore, you can even unpack the LHS and RHS into separate variables:

In [8]: lhs, rhs = "2.7.0_bf4fda703454".split("_", 1)

In [9]: lhs
Out[9]: '2.7.0'

In [10]: rhs
Out[10]: 'bf4fda703454'

An alternative is to use partition(). The usage is similar to the last example, except that it returns three components instead of two. The principal advantage is that this method doesn't fail if the string doesn't contain the separator.

iptables block access to port 8000 except from IP address

You can always use iptables to delete the rules. If you have a lot of rules, just output them using the following command.

iptables-save > myfile

vi to edit them from the commend line. Just use the "dd" to delete the lines you no longer want.

iptables-restore < myfile and you're good to go.  


Get push notification while App in foreground iOS

Xcode 10 Swift 4.2

To show Push Notification when your app is in the foreground -

Step 1 : add delegate UNUserNotificationCenterDelegate in AppDelegate class.

class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterDelegate {

Step 2 : Set the UNUserNotificationCenter delegate

let notificationCenter = UNUserNotificationCenter.current()
notificationCenter.delegate = self

Step 3 : This step will allow your app to show Push Notification even when your app is in foreground

func userNotificationCenter(_ center: UNUserNotificationCenter,
                                willPresent notification: UNNotification,
                                withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
        completionHandler([.alert, .sound])


Step 4 : This step is optional. Check if your app is in the foreground and if it is in foreground then show Local PushNotification.

func application(_ application: UIApplication,didReceiveRemoteNotification userInfo: [AnyHashable: Any],fetchCompletionHandler completionHandler:@escaping (UIBackgroundFetchResult) -> Void) {

        let state : UIApplicationState = application.applicationState
        if (state == .inactive || state == .background) {
            // go to screen relevant to Notification content
        } else {
            // App is in UIApplicationStateActive (running in foreground)

Local Notification function -

fileprivate func showLocalNotification() {

        //creating the notification content
        let content = UNMutableNotificationContent()

        //adding title, subtitle, body and badge
        content.title = "App Update"
        //content.subtitle = "local notification"
        content.body = "New version of app update is available."
        //content.badge = 1
        content.sound = UNNotificationSound.default()

        //getting the notification trigger
        //it will be called after 5 seconds
        let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 1, repeats: false)

        //getting the notification request
        let request = UNNotificationRequest(identifier: "SimplifiedIOSNotification", content: content, trigger: trigger)

        //adding the notification to notification center
        notificationCenter.add(request, withCompletionHandler: nil)

How to select a specific node with LINQ-to-XML

Assuming the ID is unique:

var result = xmldoc.Element("Customers")
                   .Single(x => (int?)x.Attribute("ID") == 2);

You could also use First, FirstOrDefault, SingleOrDefault or Where, instead of Single for different circumstances.

How do I 'svn add' all unversioned files to SVN?

svn add --force .

This will add any unversioned file in the current directory and all versioned child directories.

Show special characters in Unix while using 'less' Command

In the same spirit as

cat -A

-A, --show-all
       equivalent to -vET
-v, --show-nonprinting
       use ^ and M- notation, except for LFD and TAB
-E, --show-ends
       display $ at end of each line
-T, --show-tabs
       display TAB characters as ^I

Alternatively, or at the same time, you can pipe to tr to substitute arbitrary characters to the desired ones for display, before piping to a pager like less if desired.

How to hide Bootstrap modal with javascript?

I had better luck making the call after the "shown" callback occurred:

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

This ensured the modal was done loading before the hide() call was made.

Where is nodejs log file?

If you use docker in your dev you can do this in another shell: docker attach running_node_app_container_name

That will show you STDOUT and STDERR.

UICollectionView - dynamic cell height?

Here is a Ray Wenderlich tutorial that shows you how to use AutoLayout to dynamically size UITableViewCells. I would think it would be the same for UICollectionViewCell.

Basically, though, you end up dequeueing and configuring a prototype cell and grabbing its height. After reading this article, I decided to NOT implement this method and just write some clear, explicit sizing code.

Here's what I consider the "secret sauce" for the entire article:

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
    return [self heightForBasicCellAtIndexPath:indexPath];

- (CGFloat)heightForBasicCellAtIndexPath:(NSIndexPath *)indexPath {
    static RWBasicCell *sizingCell = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        sizingCell = [self.tableView dequeueReusableCellWithIdentifier:RWBasicCellIdentifier];

    [self configureBasicCell:sizingCell atIndexPath:indexPath];
    return [self calculateHeightForConfiguredSizingCell:sizingCell];

- (CGFloat)calculateHeightForConfiguredSizingCell:(UITableViewCell *)sizingCell {
    [sizingCell setNeedsLayout];
    [sizingCell layoutIfNeeded];

    CGSize size = [sizingCell.contentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize];
    return size.height + 1.0f; // Add 1.0f for the cell separator height

EDIT: I did some research into your crash and decided that there is no way to get this done without a custom XIB. While that is a bit frustrating, you should be able to cut and paste from your Storyboard to a custom, empty XIB.

Once you've done that, code like the following will get you going:

//  ViewController.m
#import "ViewController.h"
#import "CollectionViewCell.h"
@interface ViewController () <UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout> {

@property (weak, nonatomic) IBOutlet CollectionViewCell *cell;
@property (weak, nonatomic) IBOutlet UICollectionView   *collectionView;
@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor lightGrayColor];
    [self.collectionView registerNib:[UINib nibWithNibName:@"CollectionViewCell" bundle:nil] forCellWithReuseIdentifier:@"cell"];
- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
    return 1;
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    return 50;
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section {
    return 10.0f;
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section {
    return 10.0f;
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
    return [self sizingForRowAtIndexPath:indexPath];
- (CGSize)sizingForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *title                  = @"This is a long title that will cause some wrapping to occur. This is a long title that will cause some wrapping to occur.";
    static NSString *subtitle               = @"This is a long subtitle that will cause some wrapping to occur. This is a long subtitle that will cause some wrapping to occur.";
    static NSString *buttonTitle            = @"This is a really long button title that will cause some wrapping to occur.";
    static CollectionViewCell *sizingCell   = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        sizingCell                          = [[NSBundle mainBundle] loadNibNamed:@"CollectionViewCell" owner:self options:nil][0];
    [sizingCell configureWithTitle:title subtitle:[NSString stringWithFormat:@"%@: Number %d.", subtitle, (int)indexPath.row] buttonTitle:buttonTitle];
    [sizingCell setNeedsLayout];
    [sizingCell layoutIfNeeded];
    CGSize cellSize = [sizingCell.contentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize];
    NSLog(@"cellSize: %@", NSStringFromCGSize(cellSize));
    return cellSize;
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *title                  = @"This is a long title that will cause some wrapping to occur. This is a long title that will cause some wrapping to occur.";
    static NSString *subtitle               = @"This is a long subtitle that will cause some wrapping to occur. This is a long subtitle that will cause some wrapping to occur.";
    static NSString *buttonTitle            = @"This is a really long button title that will cause some wrapping to occur.";
    CollectionViewCell *cell                = [collectionView dequeueReusableCellWithReuseIdentifier:@"cell" forIndexPath:indexPath];
    [cell configureWithTitle:title subtitle:[NSString stringWithFormat:@"%@: Number %d.", subtitle, (int)indexPath.row] buttonTitle:buttonTitle];
    return cell;

The code above (along with a very basic UICollectionViewCell subclass and associated XIB) gives me this:

enter image description here

How do I move a redis database from one server to another?

If you have the connectivity between servers it is better to set up replication (which is trivial, unlike with SQL) with the new instance as a slave node - then you can switch the new node to master with a single command and do the move with zero downtime.

If REST applications are supposed to be stateless, how do you manage sessions?

Historical view of user application state management

Sessions in the traditional sense keep the user's state in the application inside the server. This may be the current page in a flow or what has been previously entered but not persisted to the main database yet.

The reason for this need was the lack of standards on the client side to effectively maintain the state without making client specific (i.e. browser specific) applications or plug-ins.

HTML5 and XML Header Request has over time standardized the notion of storing complex data including application state in standard way on the client (i.e. browser) side without resorting to going back and forth between the server.

General usage of REST services

REST services are generally called when there is a transaction that needs to be performed or if it needs to retrieve data.

REST services are meant to be called by the client-side application and not the end user directly.


For any request to the server, part of the request should contain the authorization token. How it is implemented is application specific, but in general is either a BASIC or CERTIFICATE form of authentication.

Form based authentication is not used by REST services. However, as noted above REST services are not meant to be called by the user, but by the application. The application needs to manage getting the authentication token. In my case I used cookies with JASPIC with OAuth 2.0 to connect to Google for authentication and simple HTTP Authentication for automated testing. I also used HTTP Header authentication via JASPIC for local testing as well (though the same approach can be performed in SiteMinder)

As per those examples, the authentication is managed on the client side (though SiteMinder or Google would store the authentication session on their end), there's nothing that can be done about that state, but it is not part of the REST service application.

Retrieval requests

Retrieval requests in REST are GET operations where a specific resource is requested and is cacheable. There is no need for server sessions because the request has everything it would need to retrieve the data: authentication and the URI.

Transaction scripts

As noted above, the client-side application itself calls the REST services along with the authentication that it manages on the client side as well.

What this means for REST services [if done correctly] is to take a single request to the REST server will contain everything that is needed for a single user operation that does everything that is needed in a single transaction, a Transaction Script is what the pattern is called.

This is done through a POST request usually, but others such as PUT can also be used.

A lot of contrived examples of REST (I myself did this) tried to follow as much of what has been defined in the HTTP protocol, after going through that I decided to be more pragmatic and left it to GET and POST only. The POST method does not even have to implement the POST-REDIRECT-GET pattern.

Regardless though, as I had noted above, the client-side application will be the one calling the service and it will only call the POST request with all the data when it needs to (not every time). This prevents constant requests to the server.


Though REST can be used for polling as well, I won't recommend it unless you have to use it because of browser compatibility. For that I would use WebSockets which I had designed an API contract for as well. Another alternative for older browsers is CometD.

How to specify the download location with wget?

-O is the option to specify the path of the file you want to download to:

wget <uri> -O /path/to/file.ext

-P is prefix where it will download the file in the directory:

wget <uri> -P /path/to/folder

'was not declared in this scope' error

The scope of a variable is always the block it is inside. For example if you do something like

     int y = 5; //y is created
} //y leaves scope, since the block ends.
     int y = 8; //y is created
} //y leaves scope, since the block ends.

cout << y << endl; //Gives error since y is not defined.

The solution is to define y outside of the if blocks

int y; //y is created

     y = 5;
     y = 8;

cout << y << endl; //Ok

In your program you have to move the definition of y and c out of the if blocks into the higher scope. Your Function then would look like this:

//Using the Gaussian algorithm
int dayofweek(int date, int month, int year )
    int y, c;
    int d=date;

    if (month==1||month==2)
int m=(month+9)%12+1;
int product=(d+(2.6*m-0.2)+y+y/4+c/4-2*c);
return product%7;

How do I create a transparent Activity on Android?

Declare your activity in the manifest like this:


And add a transparent background to your layout.

Best practice for localization and globalization of strings and labels

When you’re faced with a problem to solve (and frankly, who isn’t these days?), the basic strategy usually taken by we computer people is called “divide and conquer.” It goes like this:

  • Conceptualize the specific problem as a set of smaller sub-problems.
  • Solve each smaller problem.
  • Combine the results into a solution of the specific problem.

But “divide and conquer” is not the only possible strategy. We can also take a more generalist approach:

  • Conceptualize the specific problem as a special case of a more general problem.
  • Somehow solve the general problem.
  • Adapt the solution of the general problem to the specific problem.

- Eric Lippert

I believe many solutions already exist for this problem in server-side languages such as ASP.Net/C#.

I've outlined some of the major aspects of the problem

  • Issue: We need to load data only for the desired language

    Solution: For this purpose we save data to a separate files for each language

ex.,, res.en.js, res.js(for default language)

  • Issue: Resource files for each page should be separated so we only get the data we need

    Solution: We can use some tools that already exist like

  • Issue: We need a key/value pair structure to save our data

    Solution: I suggest a javascript object instead of string/string air. We can benefit from the intellisense from an IDE

  • Issue: General members should be stored in a public file and all pages should access them

    Solution: For this purpose I make a folder in the root of web application called Global_Resources and a folder to store global file for each sub folders we named it 'Local_Resources'

  • Issue: Each subsystems/subfolders/modules member should override the Global_Resources members on their scope

    Solution: I considered a file for each

Application Structure


The corresponding code for the files:


var res = {
    Create : "Create",
    Update : "Save Changes",
    Delete : "Delete"


var res = {
    Create : "créer",
    Update : "Enregistrer les modifications",
    Delete : "effacer"

The resource file for the desired language should be loaded on the page selected from Global_Resource - This should be the first file that is loaded on all the pages.


res.Name = "Name";
res.UserName = "UserName";
res.Password = "Password";


res.Name = "nom";
res.UserName = "Nom d'utilisateur";
res.Password = "Mot de passe";


// Override res.Create on Global_Resources/default.js
res.Create = "Create User"; 


// Override Global_Resources/
res.Create = "Créer un utilisateur";

manager.js file (this file should be load last)

res.lang = "fr";

var globalResourcePath = "Global_Resources";
var resourceFiles = [];

var currentFile = globalResourcePath + "\\default" + res.lang + ".js" ;

    currentFile = globalResourcePath + "\\default.js" ;
if(!IsFileExist(currentFile)) throw new Exception("File Not Found");


// Push parent folder on folder into folder
foreach(var folder in parent folder of current page)
    currentFile = folder + "\\Local_Resource\\default." + res.lang + ".js";

        currentFile = folder + "\\Local_Resource\\default.js";
    if(!IsExist(currentFile)) throw new Exception("File Not Found");


for(int i = 0; i < resourceFiles.length; i++) { Load.js(resourceFiles[i]); }

// Get current page name
var pageNameWithoutExtension = "SomePage";

currentFile = currentPageFolderPath + pageNameWithoutExtension + res.lang + ".js" ;

    currentFile = currentPageFolderPath + pageNameWithoutExtension + ".js" ;
if(!IsExist(currentFile)) throw new Exception("File Not Found");

Hope it helps :)

Which Android phones out there do have a gyroscope?

Since I have recently developed an Android application using gyroscope data (steady compass), I tried to collect a list with such devices. This is not an exhaustive list at all, but it is what I have so far:

*** Phones:

  • HTC Sensation
  • HTC Sensation XL
  • HTC Evo 3D
  • HTC One S
  • HTC One X
  • Huawei Ascend P1
  • Huawei Ascend X (U9000)
  • Huawei Honor (U8860)
  • LG Nitro HD (P930)
  • LG Optimus 2x (P990)
  • LG Optimus Black (P970)
  • LG Optimus 3D (P920)
  • Samsung Galaxy S II (i9100)
  • Samsung Galaxy S III (i9300)
  • Samsung Galaxy R (i9103)
  • Samsung Google Nexus S (i9020)
  • Samsung Galaxy Nexus (i9250)
  • Samsung Galaxy J3 (2017) model
  • Samsung Galaxy Note (n7000)
  • Sony Xperia P (LT22i)
  • Sony Xperia S (LT26i)

*** Tablets:

  • Acer Iconia Tab A100 (7")
  • Acer Iconia Tab A500 (10.1")
  • Asus Eee Pad Transformer (TF101)
  • Asus Eee Pad Transformer Prime (TF201)
  • Motorola Xoom (mz604)
  • Samsung Galaxy Tab (p1000)
  • Samsung Galaxy Tab 7 plus (p6200)
  • Samsung Galaxy Tab 10.1 (p7100)
  • Sony Tablet P
  • Sony Tablet S
  • Toshiba Thrive 7"
  • Toshiba Trhive 10"

Hope the list keeps growing and hope that gyros will be soon available on mid and low price smartphones.

Read file line by line in PowerShell

Get-Content has bad performance; it tries to read the file into memory all at once.

C# (.NET) file reader reads each line one by one

Best Performace

foreach($line in [System.IO.File]::ReadLines("C:\path\to\file.txt"))

Or slightly less performant

[System.IO.File]::ReadLines("C:\path\to\file.txt") | ForEach-Object {

The foreach statement will likely be slightly faster than ForEach-Object (see comments below for more information).

What Makes a Method Thread-safe? What are the rules?

There is no hard and fast rule.

Here are some rules to make code thread safe in .NET and why these are not good rules:

  1. Function and all functions it calls must be pure (no side effects) and use local variables. Although this will make your code thread-safe, there is also very little amount of interesting things you can do with this restriction in .NET.
  2. Every function that operates on a common object must lock on a common thing. All locks must be done in same order. This will make the code thread safe, but it will be incredibly slow, and you might as well not use multiple threads.
  3. ...

There is no rule that makes the code thread safe, the only thing you can do is make sure that your code will work no matter how many times is it being actively executed, each thread can be interrupted at any point, with each thread being in its own state/location, and this for each function (static or otherwise) that is accessing common objects.

How to subtract 30 days from the current date using SQL Server


Cast your VARCHAR value to DATETIME and add -30 for subtraction. Also, In sql-server the format Fri, 14 Nov 2014 23:03:35 GMT was not converted to DATETIME. Try substring for it:

       CAST(SUBSTRING ('Fri, 14 Nov 2014 23:03:35 GMT', 6, 21) 
       AS DATETIME))

Jquery .on('scroll') not firing the event while scrolling

I know that this is quite old thing, but I solved issue like that: I had parent and child element was scrollable.

   if ($('#parent > *').length == 0 ){
        var wait = setInterval(function() {
            if($('#parent > *').length != 0 ) {
                $('#parent .child').bind('scroll',function() {
                  //do staff

The issue I had is that I didn't know when the child is loaded to DOM, but I kept checking for it every second.

NOTE:this is useful if it happens soon but not right after document load, otherwise it will use clients computing power for no reason.

jQuery issue - #<an Object> has no method

This problem can also arise if you include jQuery more than once.

Python Request Post with param data

Assign the response to a value and test the attributes of it. These should tell you something useful.

response =,params=data,headers=headers)
  • status_code should just reconfirm the code you were given before, of course

react-router (v4) how to go back?

For use with React Router v4 and a functional component anywhere in the dom-tree.

import React from 'react';
import { withRouter } from 'react-router-dom';

const GoBack = ({ history }) => <img src="./images/back.png" onClick={() => history.goBack()} alt="Go back" />;

export default withRouter(GoBack);

Can I add a custom attribute to an HTML tag?

You can amend your !DOCTYPE declaration (i.e. DTD) to allow it, so that the [XML] document will still be valid:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"

#IMPLIED means it is an optional attribute, or you could use #REQUIRED, etc.

More information is in DTD - Attributes.

curl.h no such file or directory

To those who use centos and have stumbled upon this post :

 $ yum install curl-devel

and when compiling your program example.cpp, link to the curl library:

 $ g++ example.cpp -lcurl -o example

"-o example" creates the executable example instead of the default a.out.

The next line runs example:

 $ ./example

Vertical align middle with Bootstrap responsive grid

.row {
    letter-spacing: -.31em;
    word-spacing: -.43em;
.col-md-4 {
    float: none;
    display: inline-block;
    vertical-align: middle;

Note: .col-md-4 could be any grid column, its just an example here.

How can I quickly and easily convert spreadsheet data to JSON?

Assuming you really mean easiest and are not necessarily looking for a way to do this programmatically, you can do this:

  1. Add, if not already there, a row of "column Musicians" to the spreadsheet. That is, if you have data in columns such as:

    Rory Gallagher      Guitar
    Gerry McAvoy        Bass
    Rod de'Ath          Drums
    Lou Martin          Keyboards
    Donkey Kong Sioux   Self-Appointed Semi-official Stomper

    Note: you might want to add "Musician" and "Instrument" in row 0 (you might have to insert a row there)

  2. Save the file as a CSV file.

  3. Copy the contents of the CSV file to the clipboard

  4. Go to

  5. Verify that the "First row is column names" checkbox is checked

  6. Paste the CSV data into the content area

  7. Mash the "Convert CSV to JSON" button

    With the data shown above, you will now have:

        "MUSICIAN":"Rory Gallagher",
        "MUSICIAN":"Gerry McAvoy",
        "MUSICIAN":"Rod D'Ath",
        "MUSICIAN":"Lou Martin",
        "MUSICIAN":"Donkey Kong Sioux",
        "INSTRUMENT":"Self-Appointed Semi-Official Stomper"

    With this simple/minimalistic data, it's probably not required, but with large sets of data, it can save you time and headache in the proverbial long run by checking this data for aberrations and abnormalcy.

  8. Go here:

  9. Paste the JSON into the content area

  10. Pres the "Validate" button.

If the JSON is good, you will see a "Valid JSON" remark in the Results section below; if not, it will tell you where the problem[s] lie so that you can fix it/them.

How to use variables in SQL statement in Python?

cursor.execute("INSERT INTO table VALUES (%s, %s, %s)", (var1, var2, var3))

Note that the parameters are passed as a tuple.

The database API does proper escaping and quoting of variables. Be careful not to use the string formatting operator (%), because

  1. it does not do any escaping or quoting.
  2. it is prone to Uncontrolled string format attacks e.g. SQL injection.

Node.js Error: connect ECONNREFUSED

People run into this error when the Node.js process is still running and they are attempting to start the server again. Try this:

ps aux | grep node

This will print something along the lines of:

user    7668  4.3  1.0  42060 10708 pts/1    Sl+  20:36   0:00 node server
user    7749  0.0  0.0   4384   832 pts/8    S+   20:37   0:00 grep --color=auto node

In this case, the process will be the one with the pid 7668. To kill it and restart the server, run kill -9 7668.

Plotting time in Python with Matplotlib

You must first convert your timestamps to Python datetime objects (use datetime.strptime). Then use date2num to convert the dates to matplotlib format.

Plot the dates and values using plot_date:

dates = matplotlib.dates.date2num(list_of_datetimes)
matplotlib.pyplot.plot_date(dates, values)

Remove all files in a directory

Please see my answer here:

It's a long and ugly, but reliable and efficient solution.

It resolves a few problems which are not addressed by the other answerers:

  • It correctly handles symbolic links, including not calling shutil.rmtree() on a symbolic link (which will pass the os.path.isdir() test if it links to a directory).
  • It handles read-only files nicely.

Wrapping long text without white space inside of a div

You can't wrap that text as it's unbroken without any spaces. You need a JavaScript or server side solution which splits the string after a few characters.


You need to add this property in CSS.

word-wrap: break-word;

How can I disable an <option> in a <select> based on its value in JavaScript?

Pure Javascript

With pure Javascript, you'd have to cycle through each option, and check the value of it individually.

// Get all options within <select id='foo'>...</select>
var op = document.getElementById("foo").getElementsByTagName("option");
for (var i = 0; i < op.length; i++) {
  // lowercase comparison for case-insensitivity
  (op[i].value.toLowerCase() == "stackoverflow") 
    ? op[i].disabled = true 
    : op[i].disabled = false ;

Without enabling non-targeted elements:

// Get all options within <select id='foo'>...</select>
var op = document.getElementById("foo").getElementsByTagName("option");
for (var i = 0; i < op.length; i++) {
  // lowercase comparison for case-insensitivity
  if (op[i].value.toLowerCase() == "stackoverflow") {
    op[i].disabled = true;


With jQuery you can do this with a single line:

  .attr("disabled", "disabled")

Without enabling non-targeted elements:

$("option[value='stackoverflow']").attr("disabled", "disabled");

? Note that this is not case insensitive. "StackOverflow" will not equal "stackoverflow". To get a case-insensitive match, you'd have to cycle through each, converting the value to a lower case, and then check against that:

  if ($(this).val().toLowerCase() == "stackoverflow") {
    $(this).attr("disabled", "disabled").siblings().removeAttr("disabled");

Without enabling non-targeted elements:

  if ($(this).val().toLowerCase() == "stackoverflow") {
    $(this).attr("disabled", "disabled");

How do I get a PHP class constructor to call its parent's parent's constructor?

    class Grandpa 
    public function __construct()
        echo"Hello Kiddo";

class Papa extends Grandpa
    public function __construct()
    public function CallGranddad()

class Kiddo extends Papa
    public function __construct()

    public function needSomethingFromGrandDad

Combining node.js and Python

I've had a lot of success using thoonk.js along with Thoonk leverages Redis (in-memory key-value store) to give you feed (think publish/subscribe), queue and job patterns for communication.

Why is this better than unix sockets or direct tcp sockets? Overall performance may be decreased a little, however Thoonk provides a really simple API that simplifies having to manually deal with a socket. Thoonk also helps make it really trivial to implement a distributed computing model that allows you to scale your python workers to increase performance, since you just spin up new instances of your python workers and connect them to the same redis server.

How to access to the parent object in c#

I would give the parent an ID, and store the parentID in the child object, so that you can pull information about the parent as needed without creating a parent-owns-child/child-owns-parent loop.

How to remove trailing whitespace in code, using another script?

Save as

#!/usr/bin/env python
Fix trailing whitespace and line endings (to Unix) in a file.
Usage: python

import os
import sys

def main():
    """ Parse arguments, then fix whitespace in the given file """
    if len(sys.argv) == 2:
        fname = sys.argv[1]
        if not os.path.exists(fname):
            print("Python file not found: %s" % sys.argv[1])
        print("Invalid arguments. Usage: python")

def fix_whitespace(fname):
    """ Fix whitespace in a file """
    with open(fname, "rb") as fo:
        original_contents =
    # "rU" Universal line endings to Unix
    with open(fname, "rU") as fo:
        contents =
    lines = contents.split("\n")
    fixed = 0
    for k, line in enumerate(lines):
        new_line = line.rstrip()
        if len(line) != len(new_line):
            lines[k] = new_line
            fixed += 1
    with open(fname, "wb") as fo:
    if fixed or contents != original_contents:
        print("************* %s" % os.path.basename(fname))
    if fixed:
        slines = "lines" if fixed > 1 else "line"
        print("Fixed trailing whitespace on %d %s" \
              % (fixed, slines))
    if contents != original_contents:
        print("Fixed line endings to Unix (\\n)")

if __name__ == "__main__":

How to resize image automatically on browser width resize but keep same height?

changing the width of the image will automatically change the height...

how many pictures do you want to have this functionality? If it's a lot and they all have DIFFERENT Heights you should probably just let the height change as well.

Lets say you have 5 images that have height 400px , in your html give those five tags the class of fixed

.fixed { width: 100%; height: 500px !important }

This should let the width change but keep the height the same.

How to efficiently use try...catch blocks in PHP

There is no any problem to write multiple lines of execution withing a single try catch block like below

catch(Exception $e){

The moment any execption occure either in install_engine or install_break function the control will be passed to catch function. One more recommendation is to eat your exception properly. Which means instead of writing die('Message') it is always advisable to have exception process properly. You may think of using die() function in error handling but not in exception handling.

When you should use multiple try catch block You can think about multiple try catch block if you want the different code block exception to display different type of exception or you are trying to throw any exception from your catch block like below:

    catch(Exception $e){
catch(Exception $e){
throw new exception('Body Makeover faield')

How to display Wordpress search results?

Basically, you need to include the Wordpress loop in your search.php template to loop through the search results and show them as part of the template.

Below is a very basic example from The WordPress Theme Search Template and Page Template over at ThemeShaper.

 * The template for displaying Search Results pages.
 * @package Shape
 * @since Shape 1.0

get_header(); ?>

        <section id="primary" class="content-area">
            <div id="content" class="site-content" role="main">

            <?php if ( have_posts() ) : ?>

                <header class="page-header">
                    <h1 class="page-title"><?php printf( __( 'Search Results for: %s', 'shape' ), '<span>' . get_search_query() . '</span>' ); ?></h1>
                </header><!-- .page-header -->

                <?php shape_content_nav( 'nav-above' ); ?>

                <?php /* Start the Loop */ ?>
                <?php while ( have_posts() ) : the_post(); ?>

                    <?php get_template_part( 'content', 'search' ); ?>

                <?php endwhile; ?>

                <?php shape_content_nav( 'nav-below' ); ?>

            <?php else : ?>

                <?php get_template_part( 'no-results', 'search' ); ?>

            <?php endif; ?>

            </div><!-- #content .site-content -->
        </section><!-- #primary .content-area -->

<?php get_sidebar(); ?>
<?php get_footer(); ?>

How to log Apache CXF Soap Request and Soap Response using Log4j?

Try this code:

EndpointImpl impl = (EndpointImpl)Endpoint.publish(address, implementor);
    impl.getServer().getEndpoint().getInInterceptors().add(new LoggingInInterceptor());
    impl.getServer().getEndpoint().getOutInterceptors().add(new LoggingOutInterceptor());

Inside the logback.xml you need to put the interface name for webservice:

<appender name="FILE" class="ch.qos.logback.classic.sift.SiftingAppender">
    <filter class="ch.qos.logback.core.filter.EvaluatorFilter">
    <filter class="ch.qos.logback.classic.filter.ThresholdFilter">
        <appender name="FILE-${threadName}"
            <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
                <Pattern>%date{dd-MM-yyyy HH:mm:ss.SSS} | %5level | %-60([%logger{53}:%line]): %msg %ex{full} %n</Pattern>

    <level value="ALL" />
    <appender-ref ref="FILE" />

Difference between using Makefile and CMake to compile the code

The statement about CMake being a "build generator" is a common misconception.

It's not technically wrong; it just describes HOW it works, but not WHAT it does.

In the context of the question, they do the same thing: take a bunch of C/C++ files and turn them into a binary.

So, what is the real difference?

  • CMake is much more high-level. It's tailored to compile C++, for which you write much less build code, but can be also used for general purpose build. make has some built-in C/C++ rules as well, but they are useless at best.

  • CMake does a two-step build: it generates a low-level build script in ninja or make or many other generators, and then you run it. All the shell script pieces that are normally piled into Makefile are only executed at the generation stage. Thus, CMake build can be orders of magnitude faster.

  • The grammar of CMake is much easier to support for external tools than make's.

  • Once make builds an artifact, it forgets how it was built. What sources it was built from, what compiler flags? CMake tracks it, make leaves it up to you. If one of library sources was removed since the previous version of Makefile, make won't rebuild it.

  • Modern CMake (starting with version 3.something) works in terms of dependencies between "targets". A target is still a single output file, but it can have transitive ("public"/"interface" in CMake terms) dependencies. These transitive dependencies can be exposed to or hidden from the dependent packages. CMake will manage directories for you. With make, you're stuck on a file-by-file and manage-directories-by-hand level.

You could code up something in make using intermediate files to cover the last two gaps, but you're on your own. make does contain a Turing complete language (even two, sometimes three counting Guile); the first two are horrible and the Guile is practically never used.

To be honest, this is what CMake and make have in common -- their languages are pretty horrible. Here's what comes to mind:

  • They have no user-defined types;
  • CMake has three data types: string, list, and a target with properties. make has one: string;
  • you normally pass arguments to functions by setting global variables.
    • This is partially dealt with in modern CMake - you can set a target's properties: set_property(TARGET helloworld APPEND PROPERTY INCLUDE_DIRECTORIES "${CMAKE_CURRENT_SOURCE_DIR}");
  • referring to an undefined variable is silently ignored by default;

Correct MIME Type for favicon.ico?

When you're serving an .ico file to be used as a favicon, it doesn't matter. All major browsers recognize both mime types correctly. So you could put:

<!-- IE -->
<link rel="shortcut icon" type="image/x-icon" href="favicon.ico" />
<!-- other browsers -->
<link rel="icon" type="image/x-icon" href="favicon.ico" />

or the same with image/, and it will work with all browsers.

Note: There is no IANA specification for the MIME-type image/x-icon, so it does appear that it is a little more unofficial than image/

The only case in which there is a difference is if you were trying to use an .ico file in an <img> tag (which is pretty unusual). Based on previous testing, some browsers would only display .ico files as images when they were served with the MIME-type image/x-icon. More recent tests show: Chromium, Firefox and Edge are fine with both content types, IE11 is not. If you can, just avoid using ico files as images, use png.

No ConcurrentList<T> in .Net 4.0?

System.Collections.Generic.List<t> is already thread safe for multiple readers. Trying to make it thread safe for multiple writers wouldn't make sense. (For reasons Henk and Stephen already mentioned)

how to pass data in an hidden field from one jsp page to another?

The code from Alex works great. Just note that when you use request.getParameter you must use a request dispatcher

//Pass results back to the client
RequestDispatcher dispatcher =   getServletContext().getRequestDispatcher("TestPages/ServiceServlet.jsp");
dispatcher.forward(request, response);

How can I install a package with go get?

Command go

Download and install packages and dependencies


go get [-d] [-f] [-t] [-u] [-v] [-fix] [-insecure] [build flags] [packages]

Get downloads the packages named by the import paths, along with their dependencies. It then installs the named packages, like 'go install'.

The -d flag instructs get to stop after downloading the packages; that is, it instructs get not to install the packages.

The -f flag, valid only when -u is set, forces get -u not to verify that each package has been checked out from the source control repository implied by its import path. This can be useful if the source is a local fork of the original.

The -fix flag instructs get to run the fix tool on the downloaded packages before resolving dependencies or building the code.

The -insecure flag permits fetching from repositories and resolving custom domains using insecure schemes such as HTTP. Use with caution.

The -t flag instructs get to also download the packages required to build the tests for the specified packages.

The -u flag instructs get to use the network to update the named packages and their dependencies. By default, get uses the network to check out missing packages but does not use it to look for updates to existing packages.

The -v flag enables verbose progress and debug output.

Get also accepts build flags to control the installation. See 'go help build'.

When checking out a new package, get creates the target directory GOPATH/src/. If the GOPATH contains multiple entries, get uses the first one. For more details see: 'go help gopath'.

When checking out or updating a package, get looks for a branch or tag that matches the locally installed version of Go. The most important rule is that if the local installation is running version "go1", get searches for a branch or tag named "go1". If no such version exists it retrieves the default branch of the package.

When go get checks out or updates a Git repository, it also updates any git submodules referenced by the repository.

Get never checks out or updates code stored in vendor directories.

For more about specifying packages, see 'go help packages'.

For more about how 'go get' finds source code to download, see 'go help importpath'.

This text describes the behavior of get when using GOPATH to manage source code and dependencies. If instead the go command is running in module-aware mode, the details of get's flags and effects change, as does 'go help get'. See 'go help modules' and 'go help module-get'.

See also: go build, go install, go clean.

For example, showing verbose output,

$ go get -v (download) (download) (download)

How can I convert an integer to a hexadecimal string in C?

To convert an integer to a string also involves char array or memory management.

To handle that part for such short arrays, code could use a compound literal, since C99, to create array space, on the fly. The string is valid until the end of the block.

#define UNS_HEX_STR_SIZE ((sizeof (unsigned)*CHAR_BIT + 3)/4 + 1)
//                         compound literal v--------------------------v
#define U2HS(x) unsigned_to_hex_string((x), (char[UNS_HEX_STR_SIZE]) {0}, UNS_HEX_STR_SIZE)

char *unsigned_to_hex_string(unsigned x, char *dest, size_t size) {
  snprintf(dest, size, "%X", x);
  return dest;

int main(void) {
  // 3 array are formed v               v        v
  printf("%s %s %s\n", U2HS(UINT_MAX), U2HS(0), U2HS(0x12345678));
  char *hs = U2HS(rand());
  // `hs` is valid until the end of the block


FFFFFFFF 0 12345678

How to send a “multipart/form-data” POST in Android with Volley

First answer on SO.

I have encountered the same problem and found @alex 's code very helpful. I have made some simple modifications in order to pass in as many parameters as needed through HashMap, and have basically copied parseNetworkResponse() from StringRequest. I have searched online and so surprised to find out that such a common task is so rarely answered. Anyway, I wish the code could help:

public class MultipartRequest extends Request<String> {

private MultipartEntity entity = new MultipartEntity();

private static final String FILE_PART_NAME = "image";

private final Response.Listener<String> mListener;
private final File file;
private final HashMap<String, String> params;

public MultipartRequest(String url, Response.Listener<String> listener, Response.ErrorListener errorListener, File file, HashMap<String, String> params)
    super(Method.POST, url, errorListener);

    mListener = listener;
    this.file = file;
    this.params = params;

private void buildMultipartEntity()
    entity.addPart(FILE_PART_NAME, new FileBody(file));
        for ( String key : params.keySet() ) {
            entity.addPart(key, new StringBody(params.get(key)));
    catch (UnsupportedEncodingException e)

public String getBodyContentType()
    return entity.getContentType().getValue();

public byte[] getBody() throws AuthFailureError
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    catch (IOException e)
        VolleyLog.e("IOException writing to ByteArrayOutputStream");
    return bos.toByteArray();

 * copied from Android StringRequest class
protected Response<String> parseNetworkResponse(NetworkResponse response) {
    String parsed;
    try {
        parsed = new String(, HttpHeaderParser.parseCharset(response.headers));
    } catch (UnsupportedEncodingException e) {
        parsed = new String(;
    return Response.success(parsed, HttpHeaderParser.parseCacheHeaders(response));

protected void deliverResponse(String response)

And you may use the class as following:

    HashMap<String, String> params = new HashMap<String, String>();

    params.put("type", "Some Param");
    params.put("location", "Some Param");
    params.put("contact",  "Some Param");

    MultipartRequest mr = new MultipartRequest(url, new Response.Listener<String>(){

        public void onResponse(String response) {
            Log.d("response", response);

    }, new Response.ErrorListener(){

        public void onErrorResponse(VolleyError error) {
            Log.e("Volley Request Error", error.getLocalizedMessage());

    }, f, params);


openpyxl - adjust column width size

A slight improvement of the above accepted answer, that I think is more pythonic (asking for forgiveness is better than asking for permission)

column_widths = []
for row in workSheet.iter_rows():
    for i, cell in enumerate(row):
            column_widths[i] = max(column_widths[i], len(str(cell.value)))
        except IndexError:

for i, column_width in enumerate(column_widths):
    workSheet.column_dimensions[get_column_letter(i + 1)].width = column_width

Summing radio input values

Your javascript is executed before the HTML is generated, so it doesn't "see" the ungenerated INPUT elements. For jQuery, you would either stick the Javascript at the end of the HTML or wrap it like this:

<script type="text/javascript">   $(function() { //jQuery trick to say after all the HTML is parsed.     $("input[type=radio]").click(function() {       var total = 0;       $("input[type=radio]:checked").each(function() {         total += parseFloat($(this).val());       });        $("#totalSum").val(total);     });   }); </script> 

EDIT: This code works for me

<!DOCTYPE html> <html> <head> <meta charset="utf-8"> </head> <body>   <strong>Choose a base package:</strong>   <input id="item_0" type="radio" name="pkg" value="1942" />Base Package 1 - $1942   <input id="item_1" type="radio" name="pkg" value="2313" />Base Package 2 - $2313   <input id="item_2" type="radio" name="pkg" value="2829" />Base Package 3 - $2829   <strong>Choose an add on:</strong>   <input id="item_10" type="radio" name="ext" value="0" />No add-on - +$0   <input id="item_12" type="radio" name="ext" value="2146" />Add-on 1 - (+$2146)   <input id="item_13" type="radio" name="ext" value="2455" />Add-on 2 - (+$2455)   <input id="item_14" type="radio" name="ext" value="2764" />Add-on 3 - (+$2764)   <input id="item_15" type="radio" name="ext" value="3073" />Add-on 4 - (+$3073)   <input id="item_16" type="radio" name="ext" value="3382" />Add-on 5 - (+$3382)   <input id="item_17" type="radio" name="ext" value="3691" />Add-on 6 - (+$3691)   <strong>Your total is:</strong>   <input id="totalSum" type="text" name="totalSum" readonly="readonly" size="5" value="" />   <script src=""></script>   <script type="text/javascript">       $("input[type=radio]").click(function() {         var total = 0;         $("input[type=radio]:checked").each(function() {           total += parseFloat($(this).val());         });          $("#totalSum").val(total);       });     </script> </body> </html> 

Programmatically getting the MAC of an Android device

You can no longer get the hardware MAC address of a android device. WifiInfo.getMacAddress() and BluetoothAdapter.getAddress() methods will return 02:00:00:00:00:00. This restriction was introduced in Android 6.0.

But Rob Anderson found a solution which is working for < Marshmallow :

UITableView - scroll to the top

If you don't want scrolling, you can start and stop the scrolling animation as soon as you start it.

    $('document').ready(function() {
    $("html, body").animate({ scrollTop: 0 }, 500);
    return true;

Also, to animate put values for 'x' and 'y', passing in 0,0 will scroll the page to the top left instantly.

window.scrollTo(x, y);

How to add buttons dynamically to my form?

I had the same doubt and came up with the following contribution:

 int height = this.Size.Height;
 int width = this.Size.Width;

 int widthOffset = 10;
 int heightOffset = 10;

 int btnWidth = 100;  // Button Widht
 int btnHeight = 40;  // Button Height

 for (int i = 0; i < 50; ++i)
     if ((widthOffset + btnWidth) >= width)
         widthOffset = 10;
         heightOffset = heightOffset + btnHeight

         var button = new Button();
         button.Size = new Size(btnWidth, btnHeight);
         button.Name = "" + i + "";
         button.Text = "" + i + "";
         //button.Click += button_Click; // Button Click Event
         button.Location = new Point(widthOffset, heightOffset);


         widthOffset = widthOffset + (btnWidth);

         var button = new Button();
         button.Size = new Size(btnWidth, btnHeight);
         button.Name = "" + i + "";
         button.Text = "" + i + "";
         //button.Click += button_Click; // Button Click Event
         button.Location = new Point(widthOffset, heightOffset);


         widthOffset = widthOffset + (btnWidth);

Expected Behaviour:
This will generate the buttons dinamically and using the current window size, "break a line" when the button exceeds the right margin of your window.

Python: Importing urllib.quote

urllib went through some changes in Python3 and can now be imported from the parse submodule

>>> from urllib.parse import quote  
>>> quote('"')                      

AngularJS Uploading An Image With ng-upload

In my case above mentioned methods work fine with php but when i try to upload files with these methods in node.js then i have some problem. So instead of using $http({..,..,...}) use the normal jquery ajax.

For select file use this

<input type="file" name="file" onchange="angular.element(this).scope().uploadFile(this)"/>

And in controller

$scope.uploadFile = function(element) {   
var data = new FormData();
data.append('file', $(element)[0].files[0]);
      url: 'brand/upload',
      data: data,
      contentType: false,
      processData: false,
      success: function(response) {
      error: function(jqXHR, textStatus, errorMessage) {
      alert('Error uploading: ' + errorMessage);

How to validate phone numbers using regex

Have you had a look over at RegExLib?

Entering US phone number brought back quite a list of possibilities.

Double precision - decimal places

It is because it's being converted from a binary representation. Just because it has printed all those decimal digits doesn't mean it can represent all decimal values to that precision. Take, for example, this in Python:

>>> 0.14285714285714285
>>> 0.14285714285714286

Notice how I changed the last digit, but it printed out the same number anyway.

scale Image in an UIButton to AspectFit?

Swift 5.0

 myButton2.contentMode = .scaleAspectFit
 myButton2.contentHorizontalAlignment = .fill
 myButton2.contentVerticalAlignment = .fill

How to access ssis package variables inside script component

  • On the front properties page of the variable script, amend the ReadOnlyVariables (or ReadWriteVariables) property and select the variables you are interested in. This will enable the selected variables within the script task
  • Within code you will now have access to read the variable as

    string myString = Variables.MyVariableName.ToString();

jQuery checkbox event handling

There are several useful answers, but none seem to cover all the latest options. To that end all my examples also cater for the presence of matching label elements and also allow you to dynamically add checkboxes and see the results in a side-panel (by redirecting console.log).

  • Listening for click events on checkboxes is not a good idea as that will not allow for keyboard toggling or for changes made where a matching label element was clicked. Always listen for the change event.

  • Use the jQuery :checkbox pseudo-selector, rather than input[type=checkbox]. :checkbox is shorter and more readable.

  • Use is() with the jQuery :checked pseudo-selector to test for whether a checkbox is checked. This is guaranteed to work across all browsers.

Basic event handler attached to existing elements:

$('#myform :checkbox').change(function () {
    if ($(this).is(':checked')) {
        console.log($(this).val() + ' is now checked');
    } else {
        console.log($(this).val() + ' is now unchecked');



  • Uses the :checkbox selector, which is preferable to using input[type=checkbox]
  • This connects only to matching elements that exist at the time the event was registered.

Delegated event handler attached to ancestor element:

Delegated event handlers are designed for situations where the elements may not yet exist (dynamically loaded or created) and is very useful. They delegate responsibility to an ancestor element (hence the term).

$('#myform').on('change', ':checkbox', function () {
    if ($(this).is(':checked')) {
        console.log($(this).val() + ' is now checked');
    } else {
        console.log($(this).val() + ' is now unchecked');



  • This works by listening for events (in this case change) to bubble up to a non-changing ancestor element (in this case #myform).
  • It then applies the jQuery selector (':checkbox' in this case) to only the elements in the bubble chain.
  • It then applies the event handler function to only those matching elements that caused the event.
  • Use document as the default to connect the delegated event handler, if nothing else is closer/convenient.
  • Do not use body to attach delegated events as it has a bug (to do with styling) that can stop it getting mouse events.

The upshot of delegated handlers is that the matching elements only need to exist at event time and not when the event handler was registered. This allows for dynamically added content to generate the events.

Q: Is it slower?

A: So long as the events are at user-interaction speeds, you do not need to worry about the negligible difference in speed between a delegated event handler and a directly connected handler. The benefits of delegation far outweigh any minor downside. Delegated event handlers are actually faster to register as they typically connect to a single matching element.

Why doesn't prop('checked', true) fire the change event?

This is actually by design. If it did fire the event you would easily get into a situation of endless updates. Instead, after changing the checked property, send a change event to the same element using trigger (not triggerHandler):

e.g. without trigger no event occurs

$cb.prop('checked', !$cb.prop('checked'));


e.g. with trigger the normal change event is caught

$cb.prop('checked', !$cb.prop('checked')).trigger('change');



  • Do not use triggerHandler as was suggested by one user, as it will not bubble events to a delegated event handler.


although it will work for an event handler directly connected to the element:


Events triggered with .triggerHandler() do not bubble up the DOM hierarchy; if they are not handled by the target element directly, they do nothing.


If anyone has additional features they feel are not covered by this, please do suggest additions.

How to remove an item from an array in Vue.js

Why not just omit the method all together like:

v-for="(event, index) in events"
<button ... @click="$delete(events, index)">

How to format DateTime to 24 hours time?

Use upper-case HH for 24h format:

String s = curr.ToString("HH:mm");

See DateTime.ToString Method.

How to transform numpy.matrix or array to scipy sparse matrix

As for the inverse, the function is inv(A), but I won't recommend using it, since for huge matrices it is very computationally costly and unstable. Instead, you should use an approximation to the inverse, or if you want to solve Ax = b you don't really need A-1.

A JOIN With Additional Conditions Using Query Builder or Eloquent

$results = DB::table('rooms')
                     ->leftJoin('bookings', function($join)
                             $join->on('', '=', 'bookings.room_type_id');
                     ->where('bookings.room_type_id', '=', NULL)

Not quite sure if the between clause can be added to the join in laravel.


  • DB::raw() instructs Laravel not to put back quotes.
  • By passing a closure to join methods you can add more join conditions to it, on() will add AND condition and orOn() will add OR condition.

Angular 2 beta.17: Property 'map' does not exist on type 'Observable<Response>'

I was facing the similar error. It was solved when I did these three things:

  1. Update to the latest rxjs:

    npm install rxjs@6 rxjs-compat@6 --save
  2. Import map and promise:

    import 'rxjs/add/operator/map';
    import 'rxjs/add/operator/toPromise';
  3. Added a new import statement:

    import { Observable, Subject, asapScheduler, pipe, of, from, interval, merge, fromEvent } from 'rxjs';

PHP XML Extension: Not installed

If you are working with php in windows, you can just access to the file "php.ini" located in your php instalation folder and uncomment the ";extension=xmlrpc" line deleting the ";" ("extension=xmlrpc")

How to make the checkbox unchecked by default always

No, there is no way in simple HTML. Javascript might be your only solution at this time..

Loop through all checkboxes in javascript and set them to unchecked:

var checkboxes = document.getElementsByTagName('input');

for (var i=0; i<checkboxes.length; i++)  {
  if (checkboxes[i].type == 'checkbox')   {
    checkboxes[i].checked = false;

wrap it up in a onload listener and you should be fine then :)

How to overload functions in javascript?

Overloading a function in JavaScript can be done in many ways. All of them involve a single master function that either performs all the processes, or delegates to sub-functions/processes.

One of the most common simple techniques involves a simple switch:

function foo(a, b) {
    switch (arguments.length) {
    case 0:
        //do basic code
    case 1:
        //do code with `a`
    case 2:
        //do code with `a` & `b`

A more elegant technique would be to use an array (or object if you're not making overloads for every argument count):

fooArr = [
    function () {
    function (a) {
    function (a,b) {
function foo(a, b) {
    return fooArr[arguments.length](a, b);

That previous example isn't very elegant, anyone could modify fooArr, and it would fail if someone passes in more than 2 arguments to foo, so a better form would be to use a module pattern and a few checks:

var foo = (function () {
    var fns;
    fns = [
        function () {
        function (a) {
        function (a, b) {
    function foo(a, b) {
        var fnIndex;
        fnIndex = arguments.length;
        if (fnIndex > foo.length) {
            fnIndex = foo.length;
        return fns[fnIndex].call(this, a, b);
    return foo;

Of course your overloads might want to use a dynamic number of parameters, so you could use an object for the fns collection.

var foo = (function () {
    var fns;
    fns = {};
    fns[0] = function () {
    fns[1] = function (a) {
    fns[2] = function (a, b) {
    fns.params = function (a, b /*, params */) {
    function foo(a, b) {
        var fnIndex;
        fnIndex = arguments.length;
        if (fnIndex > foo.length) {
            fnIndex = 'params';
        return fns[fnIndex].apply(this,;
    return foo;

My personal preference tends to be the switch, although it does bulk up the master function. A common example of where I'd use this technique would be a accessor/mutator method:

function Foo() {} //constructor
Foo.prototype = {
    bar: function (val) {
        switch (arguments.length) {
        case 0:
            return this._bar;
        case 1:
            this._bar = val;
            return this;

Ruby value of a hash key?

It seems that your question is maybe a bit ambiguous.

If “values” in the first sentence means any generic value (i.e. object, since everything in Ruby can be viewed as an object), then one of the other answers probably tells you what you need to know (i.e. use Hash#[] (e.g. hash[some_key]) to find the value associated with a key).

If, however, “values” in first sentence is taken to mean the value part of the “key, value pairs” (as are stored in hashes), then your question seems like it might be about working in the other direction (key for a given value).

You can find a key that leads to a certain value with Hash#key.

ruby-1.9.2-head :001 > hash = { :a => '1', :b => :two, :c => 3, 'bee' => :two }
 => {:a=>"1", :b=>:two, :c=>3, "bee"=>:two} 
ruby-1.9.2-head :002 > a_value = :two
 => :two 
ruby-1.9.2-head :003 > hash.key(a_value)
 => :b 

If you are using a Ruby earlier than 1.9, you can use Hash#index.

When there are multiple keys with the desired value, the method will only return one of them. If you want all the keys with a given value, you may have to iterate a bit:

ruby-1.9.2-head :004 > hash[:b] == hash['bee']
 => true 
ruby-1.9.2-head :005 > keys = hash.inject([]) do # all keys with value a_value
ruby-1.9.2-head :006 >       |l,kv| kv[1] == a_value ? l << kv[0] : l
ruby-1.9.2-head :007?>   end
 => [:b, "bee"] 

Once you have a key (the keys) that lead to the value, you can compare them and act on them with if/unless/case expressions, custom methods that take blocks, et cetera. Just how you compare them depends on the kind of objects you are using for keys (people often use strings and symbols, but Ruby hashes can use any kind of object as keys (as long as they are not modified while they serve as keys)).

Can promises have multiple arguments to onFulfilled?

De-structuring Assignment in ES6 would help here.For Ex:

let [arg1, arg2] = new Promise((resolve, reject) => {
    resolve([argument1, argument2]);

How can I get npm start at a different directory?

Below Command where project is a folder which contains package.json file

npm run --prefix project ${COMMAND}

is working as well. Useful in Docker based applications.

How to add hyperlink in JLabel?

If <a href="link"> doesn't work, then:

  1. Create a JLabel and add a MouseListener (decorate the label to look like a hyperlink)
  2. Implement mouseClicked() event
  3. In the implementation of mouseClicked() event, perform your action

Have a look at java.awt.Desktop API for opening a link using the default browser (this API is available only from Java6).

How can I select the row with the highest ID in MySQL?


Remove a folder from git tracking

I came across this question while Googling for "git remove folder from tracking". The OP's question lead me to the answer. I am summarizing it here for future generations.


How do I remove a folder from my git repository without deleting it from my local machine (i.e., development environment)?


Step 1. Add the folder path to your repo's root .gitignore file.


Step 2. Remove the folder from your local git tracking, but keep it on your disk.

git rm -r --cached path_to_your_folder/

Step 3. Push your changes to your git repo.

The folder will be considered "deleted" from Git's point of view (i.e. they are in past history, but not in the latest commit, and people pulling from this repo will get the files removed from their trees), but stay on your working directory because you've used --cached.

How to search through all Git and Mercurial commits in the repository for a certain string?

Building on rq's answer, I found this line does what I want:

git grep "search for something" $(git log -g --pretty=format:%h -S"search for something")

Which will report the commit ID, filename, and display the matching line, like this:

91ba969:testFile:this is a test

... Does anyone agree that this would be a nice option to be included in the standard git grep command?

How Long Does it Take to Learn Java for a Complete Newbie?

I wouldn't say I had "no programming experience" but prior to learning J2ME, most of what I'd done was in assembler more than 10 years prior.

I skipped learning "JAVA" and learned J2ME, which appears to be a small subset of java. It's small enough (if you ignore the extensions) that it's very digestable and easily explained in a moderately sized book. From that standpoint, it was a little bit like assembler (somewhat limited amount of stuff to know) although I did need to learn about OOP.

I bought a few J2ME books, but the one I found most helpful was: "Programming Wireless Devices with the Java 2 Platform" by Riggs, et al.

I don't recall exactly how long it took me, but I'm pretty sure I was writting deployable code (it was a mobile time sheet application) in 12 weeks or so.

Comparing two strings, ignoring case in C#

If you're looking for efficiency, use this:

string.Equals(val, "astringvalue", StringComparison.OrdinalIgnoreCase)

Ordinal comparisons can be significantly faster than culture-aware comparisons.

ToLowerCase can be the better option if you're doing a lot of comparisons against the same string, however.

As with any performance optimization: measure it, then decide!

How do I use typedef and typedef enum in C?

typedef enum state {DEAD,ALIVE} State;
|     | |                     | |   |^ terminating semicolon, required! 
|     | |   type specifier    | |   |
|     | |                     | ^^^^^  declarator (simple name)
|     | |                     |    
|     | ^^^^^^^^^^^^^^^^^^^^^^^  
|     |
^^^^^^^-- storage class specifier (in this case typedef)

The typedef keyword is a pseudo-storage-class specifier. Syntactically, it is used in the same place where a storage class specifier like extern or static is used. It doesn't have anything to do with storage. It means that the declaration doesn't introduce the existence of named objects, but rather, it introduces names which are type aliases.

After the above declaration, the State identifier becomes an alias for the type enum state {DEAD,ALIVE}. The declaration also provides that type itself. However that isn't typedef doing it. Any declaration in which enum state {DEAD,ALIVE} appears as a type specifier introduces that type into the scope:

enum state {DEAD, ALIVE} stateVariable;

If enum state has previously been introduced the typedef has to be written like this:

typedef enum state State;

otherwise the enum is being redefined, which is an error.

Like other declarations (except function parameter declarations), the typedef declaration can have multiple declarators, separated by a comma. Moreover, they can be derived declarators, not only simple names:

typedef unsigned long ulong, *ulongptr;
|     | |           | |  1 | |   2   |
|     | |           | |    | ^^^^^^^^^--- "pointer to" declarator
|     | |           | ^^^^^^------------- simple declarator
|     | ^^^^^^^^^^^^^-------------------- specifier-qualifier list
^^^^^^^---------------------------------- storage class specifier

This typedef introduces two type names ulong and ulongptr, based on the unsigned long type given in the specifier-qualifier list. ulong is just a straight alias for that type. ulongptr is declared as a pointer to unsigned long, thanks to the * syntax, which in this role is a kind of type construction operator which deliberately mimics the unary * for pointer dereferencing used in expressions. In other words ulongptr is an alias for the "pointer to unsigned long" type.

Alias means that ulongptr is not a distinct type from unsigned long *. This is valid code, requiring no diagnostic:

unsigned long *p = 0;
ulongptr q = p;

The variables q and p have exactly the same type.

The aliasing of typedef isn't textual. For instance if user_id_t is a typedef name for the type int, we may not simply do this:

unsigned user_id_t uid;  // error! programmer hoped for "unsigned int uid". 

This is an invalid type specifier list, combining unsigned with a typedef name. The above can be done using the C preprocessor:

#define user_id_t int
unsigned user_id_t uid;

whereby user_id_t is macro-expanded to the token int prior to syntax analysis and translation. While this may seem like an advantage, it is a false one; avoid this in new programs.

Among the disadvantages that it doesn't work well for derived types:

 #define silly_macro int *

 silly_macro not, what, you, think;

This declaration doesn't declare what, you and think as being of type "pointer to int" because the macro-expansion is:

 int * not, what, you, think;

The type specifier is int, and the declarators are *not, what, you and think. So not has the expected pointer type, but the remaining identifiers do not.

And that's probably 99% of everything about typedef and type aliasing in C.

remove empty lines from text file with PowerShell

(Get-Content c:\FileWithEmptyLines.txt) | 
    Foreach { $_ -Replace  "Old content", " New content" } | 
    Set-Content c:\FileWithEmptyLines.txt;

Moment JS - check if a date is today or in the future

i wanted it for something else but eventually found a trick which you can try

somedate.calendar(compareDate, { sameDay: '[Today]'})=='Today'

var d = moment();_x000D_
 var today = moment();_x000D_
 console.log("Usign today's date, is Date is Today? ",d.calendar(today, {_x000D_
    sameDay: '[Today]'})=='Today');_x000D_
 var someRondomDate = moment("2012/07/13","YYYY/MM/DD");_x000D_
 console.log("Usign Some Random Date, is Today ?",someRondomDate.calendar(today, {_x000D_
    sameDay: '[Today]'})=='Today');_x000D_
 var anotherRandomDate =  moment("2012/07/13","YYYY/MM/DD");_x000D_
 console.log("Two Random Date are same date ? ",someRondomDate.calendar(anotherRandomDate, {_x000D_
    sameDay: '[Today]'})=='Today');
<script src=""></script>

What is the difference between a heuristic and an algorithm?

A heuristic is usually an optimization or a strategy that usually provides a good enough answer, but not always and rarely the best answer. For example, if you were to solve the traveling salesman problem with brute force, discarding a partial solution once its cost exceeds that of the current best solution is a heuristic: sometimes it helps, other times it doesn't, and it definitely doesn't improve the theoretical (big-oh notation) run time of the algorithm

String comparison in Objective-C

You can use case-sensitive or case-insensitive comparison, depending what you need. Case-sensitive is like this:

if ([category isEqualToString:@"Some String"])
   // Both strings are equal without respect to their case.

Case-insensitive is like this:

if ([category compare:@"Some String" options:NSCaseInsensitiveSearch] == NSOrderedSame)
   // Both strings are equal with respect to their case.

Change <br> height using CSS

The line height of the br tag can be different from the line height of the rest of the text inside a paragraph text by setting font-size for br tag.

Example: br { font-size: 200%; }

Is there a mechanism to loop x times in ES6 (ECMAScript 6) without mutable variables?

Advantages of this solution

  • Simplest to read / use (imo)
  • Return value can be used as a sum, or just ignored
  • Plain es6 version, also link to TypeScript version of the code

Disadvantages - Mutation. Being internal only I don't care, maybe some others will not either.

Examples and Code

times(5, 3)                       // 15    (3+3+3+3+3)

times(5, (i) => Math.pow(2,i) )   // 31    (1+2+4+8+16)

times(5, '<br/>')                 // <br/><br/><br/><br/><br/>

times(3, (i, count) => {          // name[0], name[1], name[2]
    let n = 'name[' + i + ']'
    if (i < count-1)
        n += ', '
    return n

function times(count, callbackOrScalar) {
    let type = typeof callbackOrScalar
    let sum
    if (type === 'number') sum = 0
    else if (type === 'string') sum = ''

    for (let j = 0; j < count; j++) {
        if (type === 'function') {
            const callback = callbackOrScalar
            const result = callback(j, count)
            if (typeof result === 'number' || typeof result === 'string')
                sum = sum === undefined ? result : sum + result
        else if (type === 'number' || type === 'string') {
            const scalar = callbackOrScalar
            sum = sum === undefined ? scalar : sum + scalar
    return sum

TypeScipt version

.net Core 2.0 - Package was restored using .NetFramework 4.6.1 instead of target framework .netCore 2.0. The package may not be fully compatible

For me, I had ~6 different Nuget packages to update and when I selected Microsoft.AspNetCore.All first, I got the referenced error.

I started at the bottom and updated others first (EF Core, EF Design Tools, etc), then when the only one that was left was Microsoft.AspNetCore.All it worked fine.

Import text file as single character string

It seems your solution is not much ugly. You can use functions and make it proffesional like these ways

  • first way
new.function <- function(filename){

  • second way
new.function <- function(){
  filename <- 'foo.txt'
  return (readChar(filename,$size))


How to match a line not containing a word

This should work:


If you only wanted to exclude it from the beginning of the line (I know you don't, but just FYI), you could use this:


Edit (by request): Why this pattern works

The (?!...) syntax is a negative lookahead, which I've always found tough to explain. Basically, it means "whatever follows this point must not match the regular expression /PART/." The site I've linked explains this far better than I can, but I'll try to break this down:

^         #Start matching from the beginning of the string.    
(?!PART)  #This position must not be followed by the string "PART".
.         #Matches any character except line breaks (it will include those in single-line mode).
$         #Match all the way until the end of the string.

The ((?!xxx).)* idiom is probably hardest to understand. As we saw, (?!PART) looks at the string ahead and says that whatever comes next can't match the subpattern /PART/. So what we're doing with ((?!xxx).)* is going through the string letter by letter and applying the rule to all of them. Each character can be anything, but if you take that character and the next few characters after it, you'd better not get the word PART.

The ^ and $ anchors are there to demand that the rule be applied to the entire string, from beginning to end. Without those anchors, any piece of the string that didn't begin with PART would be a match. Even PART itself would have matches in it, because (for example) the letter A isn't followed by the exact string PART.

Since we do have ^ and $, if PART were anywhere in the string, one of the characters would match (?=PART). and the overall match would fail. Hope that's clear enough to be helpful.

Skipping Incompatible Libraries at compile

Normally, that is not an error per se; it is a warning that the first file it found that matches the -lPI-Http argument to the compiler/linker is not valid. The error occurs when no other library can be found with the right content.

So, you need to look to see whether /dvlpmnt/libPI-Http.a is a library of 32-bit object files or of 64-bit object files - it will likely be 64-bit if you are compiling with the -m32 option. Then you need to establish whether there is an alternative libPI-Http.a or file somewhere else that is 32-bit. If so, ensure that the directory that contains it is listed in a -L/some/where argument to the linker. If not, then you will need to obtain or build a 32-bit version of the library from somewhere.

To establish what is in that library, you may need to do:

mkdir junk
cd junk
ar x /dvlpmnt/libPI-Http.a
file *.o
cd ..
rm -fr junk

The 'file' step tells you what type of object files are in the archive. The rest just makes sure you don't make a mess that can't be easily cleaned up.

How to initialize log4j properly?

Log4j by default looks for a file called or log4j.xml on the classpath.

You can control which file it uses to initialize itself by setting system properties as described here (Look for the "Default Initialization Procedure" section).

For example:

java -Dlog4j.configuration=customName ....

Will cause log4j to look for a file called customName on the classpath.

If you are having problems I find it helpful to turn on the log4j.debug:


It will print to System.out lots of helpful information about which file it used to initialize itself, which loggers / appenders got configured and how etc.

The configuration file can be a java properties file or an xml file. Here is a sample of the properties file format taken from the log4j intro documentation page:

log4j.rootLogger=debug, stdout, R


# Pattern to output the caller's file name and line number.
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] (%F:%L) - %m%n


# Keep one backup file

log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n

Compute row average in pandas

We can find the the mean of a row using the range function, i.e in your case, from the Y1961 column to the Y1965

df['mean'] = df.iloc[:, 0:4].mean(axis=1)

And if you want to select individual columns

df['mean'] = df.iloc[:, [0,1,2,3,4].mean(axis=1)

Regular expression to stop at first match

Use of Lazy quantifiers ? with no global flag is the answer.


enter image description here

If you had global flag /g then, it would have matched all the lowest length matches as below. enter image description here

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

All of these are kinds of indices.

primary: must be unique, is an index, is (likely) the physical index, can be only one per table.

unique: as it says. You can't have more than one row with a tuple of this value. Note that since a unique key can be over more than one column, this doesn't necessarily mean that each individual column in the index is unique, but that each combination of values across these columns is unique.

index: if it's not primary or unique, it doesn't constrain values inserted into the table, but it does allow them to be looked up more efficiently.

fulltext: a more specialized form of indexing that allows full text search. Think of it as (essentially) creating an "index" for each "word" in the specified column.

How to remove all callbacks from a Handler?

In my experience calling this worked great!


In the docs for removeCallbacksAndMessages it says...

Remove any pending posts of callbacks and sent messages whose obj is token. If token is null, all callbacks and messages will be removed.

How to obtain Telegram chat_id for a specific user?

There is a bot that echoes your chat id upon starting a conversation.

Just search for @chatid_echo_bot and tap /start. It will echo your chat id.

Chat id bot screenshot

Another option is @getidsbot which gives you much more information. This bot also gives information about a forwarded message (from user, to user, chad ids, etc) if you forward the message to the bot.

Representational state transfer (REST) and Simple Object Access Protocol (SOAP)

Both methods are used by many of the large players. It's a matter of preference. My preference is REST because it's simpler to use and understand.

Simple Object Access Protocol (SOAP):

  • SOAP builds an XML protocol on top of HTTP or sometimes TCP/IP.
  • SOAP describes functions, and types of data.
  • SOAP is a successor of XML-RPC and is very similar, but describes a standard way to communicate.
  • Several programming languages have native support for SOAP, you typically feed it a web service URL and you can call its web service functions without the need of specific code.
  • Binary data that is sent must be encoded first into a format such as base64 encoded.
  • Has several protocols and technologies relating to it: WSDL, XSDs, SOAP, WS-Addressing

Representational state transfer (REST):

  • REST need not be over HTTP but most of my points below will have an HTTP bias.
  • REST is very lightweight, it says wait a minute, we don't need all of this complexity that SOAP created.
  • Typically uses normal HTTP methods instead of a big XML format describing everything. For example to obtain a resource you use HTTP GET, to put a resource on the server you use HTTP PUT. To delete a resource on the server you use HTTP DELETE.
  • REST is a very simple in that it uses HTTP GET, POST and PUT methods to update resources on the server.
  • REST typically is best used with Resource Oriented Architecture (ROA). In this mode of thinking everything is a resource, and you would operate on these resources.
  • As long as your programming language has an HTTP library, and most do, you can consume a REST HTTP protocol very easily.
  • Binary data or binary resources can simply be delivered upon their request.

There are endless debates on REST vs SOAP on google.

My favorite is this one. Update 27 Nov 2013: Paul Prescod's site appears to have gone offline and this article is no longer available, copies though can be found on the Wayback Machine or as a PDF at CiteSeerX.

Finding the index of elements based on a condition using python list comprehension

Maybe another question is, "what are you going to do with those indices once you get them?" If you are going to use them to create another list, then in Python, they are an unnecessary middle step. If you want all the values that match a given condition, just use the builtin filter:

matchingVals = filter(lambda x : x>2, a)

Or write your own list comprhension:

matchingVals = [x for x in a if x > 2]

If you want to remove them from the list, then the Pythonic way is not to necessarily remove from the list, but write a list comprehension as if you were creating a new list, and assigning back in-place using the listvar[:] on the left-hand-side:

a[:] = [x for x in a if x <= 2]

Matlab supplies find because its array-centric model works by selecting items using their array indices. You can do this in Python, certainly, but the more Pythonic way is using iterators and generators, as already mentioned by @EliBendersky.

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

Lots of people are running into it, so I wanted to post here .

Found a crazy easy workaround thanks to this guy: Expertdebugger.

Simply downgrade your language version from C# 6 to C# 5, like so:

      <compiler language="c#;cs;csharp" extension=".cs" type="Microsoft.CSharp.CSharpCodeProvider, System, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089" warningLevel="4" compilerOptions="/langversion:6 /nowarn:1659;1699;1701">
        <providerOption name="CompilerVersion" value="v4.0"/>
      <compiler language="vb;vbs;visualbasic;vbscript" extension=".vb" type="Microsoft.VisualBasic.VBCodeProvider, System, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089" warningLevel="4" compilerOptions="/langversion:14 /nowarn:41008 /define:_MYTYPE=\&quot;Web\&quot; /optionInfer+">
          <providerOption name="CompilerVersion" value="v4.0"/>

Change the langversion:6 towards the bottom from 6 to 5 - langversion:5

Fixed it for me. Thank him.

Dump Mongo Collection into JSON format

Here's mine command for reference:

mongoexport --db AppDB --collection files --pretty --out output.json

On Windows 7 (MongoDB 3.4), one has to move the cmd to the place where mongod.exe and mongo.exe file resides => C:\MongoDB\Server\3.4\bin else it won't work saying it does not recongnize mongoexport command.

standard_init_linux.go:190: exec user process caused "no such file or directory" - Docker

There are multiple right answers here. I don't see the VIM version of it so here it is. Open your file in VIM, check the bottom status line for example, execute set ff=dos (for CRLF) or set ff=unix (for LF).

How to reset a select element with jQuery

if none of those solutions didn't work for you, try adding after

.trigger( "change" );


$("#baba").val("").trigger( "change" );


$("#baba").val(false).trigger( "change" );


$("#baba option").prop("selected", false).trigger( "change" );


$('#baba').prop('selectedIndex',-1).trigger( "change" );


$('#baba option:first').prop('selected',true).trigger( "change" );

Implement a loading indicator for a jQuery AJAX call

This is how I got it working with loading remote content that needs to be refreshed:

$(document).ready(function () {
    var loadingContent = '<div class="modal-header"><h1>Processing...</h1></div><div class="modal-body"><div class="progress progress-striped active"><div class="bar" style="width: 100%;"></div></div></div>';

    // This is need so the content gets replaced correctly.
    $("#myModal").on("", function (e) {
        var link = $(e.relatedTarget);

    $("#myModal2").on("", function (e) {

Basically, just replace the modal content while it's loading with a loading message. The content will then be replaced once it's finished loading.

Iterate a list with indexes in Python

Here's another using the zip function.

>>> a = [3, 7, 19]
>>> zip(range(len(a)), a)
[(0, 3), (1, 7), (2, 19)]

Clearing an HTML file upload field via JavaScript

try this its work fine

document.getElementById('fileUpload').parentNode.innerHTML = document.getElementById('fileUpload').parentNode.innerHTML;

Graphical user interface Tutorial in C

You can also have a look at FLTK (C++ and not plain C though)

FLTK (pronounced "fulltick") is a cross-platform C++ GUI toolkit for UNIX®/Linux® (X11), Microsoft® Windows®, and MacOS® X. FLTK provides modern GUI functionality without the bloat and supports 3D graphics via OpenGL® and its built-in GLUT emulation.

FLTK is designed to be small and modular enough to be statically linked, but works fine as a shared library. FLTK also includes an excellent UI builder called FLUID that can be used to create applications in minutes.

Here are some quickstart screencasts

[Happy New Year!]

ImportError: Cannot import name X

If you are importing from and used this:

if __name__ == '__main__':
    # etc

Variables below that in cannot be imported to because __name__ does not equal __main__!

If you want to import something from to, you need to use this in

if __name__ == 'file1':
    # etc

In case of doubt, make an assert statement to determine if __name__=='__main__'

Styling the arrow on bootstrap tooltips

You can use this to change tooltip-arrow color

.tooltip.bottom .tooltip-arrow {
  top: 0;
  left: 50%;
  margin-left: -5px;
  border-bottom-color: #000000; /* black */
  border-width: 0 5px 5px;

File Not Found when running PHP with Nginx

In my case, it was because the permissions on the root web directory were not set correctly. To do this, you need to be in the parent folder when you run this in terminal:

sudo chmod -R 755 htmlfoldername

This will chmod all files in your html folder, which is not recommended for production for security reasons, but should let you see the files in that folder, to be sure that isn't the issue while troubleshooting.

What ports does RabbitMQ use?

To find out what ports rabbitmq uses:

$ epmd -names


epmd: up and running on port 4369 with data:
name rabbit at port 25672

Run these as root:

lsof -i :4369
lsof -i :25672

More about epmd options.

Running vbscript from batch file

You can use %~dp0 to get the path of the currently running batch file.

Edited to change directory to the VBS location before running

If you want the VBS to synchronously run in the same window, then

@echo off
pushd %~dp0
cscript necdaily.vbs

If you want the VBS to synchronously run in a new window, then

@echo off
pushd %~dp0
start /wait "" cmd /c cscript necdaily.vbs

If you want the VBS to asynchronously run in the same window, then

@echo off
pushd %~dp0
start /b "" cscript necdaily.vbs

If you want the VBS to asynchronously run in a new window, then

@echo off
pushd %~dp0
start "" cmd /c cscript necdaily.vbs

Steps to upload an iPhone application to the AppStore

This arstechnica article describes the basic steps:

Start by visiting the program portal and make sure that your developer certificate is up to date. It expires every six months and, if you haven't requested that a new one be issued, you cannot submit software to App Store. For most people experiencing the "pink upload of doom," though, their certificates are already valid. What next?

Open your Xcode project and check that you've set the active SDK to one of the device choices, like Device - 2.2. Accidentally leaving the build settings to Simulator can be a big reason for the pink rejection. And that happens more often than many developers would care to admit.

Next, make sure that you've chosen a build configuration that uses your distribution (not your developer) certificate. Check this by double-clicking on your target in the Groups & Files column on the left of the project window. The Target Info window will open. Click the Build tab and review your Code Signing Identity. It should be iPhone Distribution: followed by your name or company name.

You may also want to confirm your application identifier in the Properties tab. Most likely, you'll have set the identifier properly when debugging with your developer certificate, but it never hurts to check.

The top-left of your project window also confirms your settings and configuration. It should read something like "Device - 2.2 | Distribution". This shows you the active SDK and configuration.

If your settings are correct but you still aren't getting that upload finished properly, clean your builds. Choose Build > Clean (Command-Shift-K) and click Clean. Alternatively, you can manually trash the build folder in your Project from Finder. Once you've cleaned, build again fresh.

If this does not produce an app that when zipped properly loads to iTunes Connect, quit and relaunch Xcode. I'm not kidding. This one simple trick solves more signing problems and "pink rejections of doom" than any other solution already mentioned.

How to use systemctl in Ubuntu 14.04

So you want to remove dangling images? Am I correct?

systemctl enable docker-container-cleanup.timer
systemctl start docker-container-cleanup.timer
systemctl enable docker-image-cleanup.timer 
systemctl start docker-image-cleanup.timer

how to implement Pagination in reactJs

   Sample pagination react js working code 
    import React, { Component } from 'react';
    import {
    } from "reactstrap";

    let prev  = 0;
    let next  = 0;
    let last  = 0;
    let first = 0;
    export default class SamplePagination extends Component {
       constructor() {
         this.state = {
           todos: ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','T','v','u','w','x','y','z'],
           currentPage: 1,
           todosPerPage: 3,

         this.handleClick = this.handleClick.bind(this);
         this.handleLastClick = this.handleLastClick.bind(this);
         this.handleFirstClick = this.handleFirstClick.bind(this);

       handleClick(event) {
           currentPage: Number(

       handleLastClick(event) {
       handleFirstClick(event) {
       render() {
         let { todos, currentPage, todosPerPage } = this.state;

         // Logic for displaying current todos
         let indexOfLastTodo = currentPage * todosPerPage;
         let indexOfFirstTodo = indexOfLastTodo - todosPerPage;
         let currentTodos = todos.slice(indexOfFirstTodo, indexOfLastTodo);
          prev  = currentPage > 0 ? (currentPage -1) :0;
          last = Math.ceil(todos.length/todosPerPage);
          next  = (last === currentPage) ?currentPage: currentPage +1;

         // Logic for displaying page numbers
         let pageNumbers = [];
         for (let i = 1; i <=last; i++) {

          return (
      ,index) =>{
                  return <li key={index}>{todo}</li>;
             </ul><ul id="page-numbers">
              { prev === 0 ? <PaginationLink disabled>First</PaginationLink> :
                  <PaginationLink onClick={this.handleFirstClick} id={prev} href={prev}>First</PaginationLink>
              { prev === 0 ? <PaginationLink disabled>Prev</PaginationLink> :
                  <PaginationLink onClick={this.handleClick} id={prev} href={prev}>Prev</PaginationLink>
        ,i) =>
                  <Pagination key= {i}>
                  <PaginationItem active = {pageNumbers[currentPage-1] === (number) ? true : false} >
                   <PaginationLink onClick={this.handleClick} href={number} key={number} id={number}>

               currentPage === last ? <PaginationLink disabled>Next</PaginationLink> :
               <PaginationLink onClick={this.handleClick} id={pageNumbers[currentPage]} href={pageNumbers[currentPage]}>Next</PaginationLink>

               currentPage === last ? <PaginationLink disabled>Last</PaginationLink> :
               <PaginationLink onClick={this.handleLastClick} id={pageNumbers[currentPage]} href={pageNumbers[currentPage]}>Last</PaginationLink>

      <SamplePagination />,

Matplotlib different size subplots

Another way is to use the subplots function and pass the width ratio with gridspec_kw:

import numpy as np
import matplotlib.pyplot as plt 

# generate some data
x = np.arange(0, 10, 0.2)
y = np.sin(x)

# plot it
f, (a0, a1) = plt.subplots(1, 2, gridspec_kw={'width_ratios': [3, 1]})
a0.plot(x, y)
a1.plot(y, x)


How do I export an Android Studio project?

In the Android Studio go to File then Close Project. Then take the folder (in the workspace folder) of the project and copy it to a flash memory or whatever. Then when you get comfortable at home, copy this folder in the workspace folder you've already created, open the Android Studio and go to File then Open and import this project into your workspace.

The problem you have with this is that you're searching for the wrong term here, because in Android, exporting a project means compiling it to .apk file (not exporting the project). Import/Export is used for the .apk management, what you need is Open/Close project, the other thing is just copy/paste.

How to use PHP with Visual Studio

Try Visual Studio Code. Very good support for PHP and other languages directly or via extensions. It can not replace power of Visual Studio but it is powerful addition to Visual Studio. And you can run it on all OS (Windows, Linux, Mac...).

Is there a way to run Bash scripts on Windows?

In order to run natively, you will likely need to use Cygwin (which I cannot live without when using Windows). So right off the bat, +1 for Cygwin. Anything else would be uncivilized.

HOWEVER, that being said, I have recently begun using a combination of utilities to easily PORT Bash scripts to Windows so that my anti-Linux coworkers can easily run complex tasks that are better handled by GNU utilities.

I can usually port a Bash script to Batch in a very short time by opening the original script in one pane and writing a Batch file in the other pane. The tools that I use are as follows:

I prefer UnxUtils to GnuWin32 because of the fact that [someone please correct me if I'm wrong] GnuWin utils normally have to be installed, whereas UnxUtils are standalone binaries that just work out-of-the-box.

However, the CoreUtils do not include some familiar *NIX utilities such as cURL, which is also available for Windows (

I create a folder for the projects, and always SET PATH=. in the .bat file so that no other commands other than the basic CMD shell commands are referenced (as well as the particular UnxUtils required in the project folder for the Batch script to function as expected).

Then I copy the needed CoreUtils .exe files into the project folder and reference them in the .bat file such as ".\curl.exe -s", etc.

The Bat2Exe program is where the magic happens. Once your Batch file is complete and has been tested successfully, launch Bat2Exe.exe, and specify the path to the project folder. Bat2Exe will then create a Windows binary containing all of the files in that specific folder, and will use the first .bat that it comes across to use as the main executable. You can even include a .ico file to use as the icon for the final .exe file that is generated.

I have tried a few of these type of programs, and many of the generated binaries get flagged as malware, but the Bat2Exe version that I referenced works perfectly and the generated .exe files scan completely clean.

The resulting executable can be run interactively by double-clicking, or run from the command line with parameters, etc., just like a regular Batch file, except you will be able to utilize the functionality of many of the tools that you will normally use in Bash.

I realize this is getting quite long, but if I may digress a bit, I have also written a Batch script that I call PortaBashy that my coworkers can launch from a network share that contains a portable Cygwin installation. It then sets the %PATH% variable to the normal *NIX format (/usr/bin:/usr/sbin:/bin:/sbin), etc. and can either launch into the Bash shell itself or launch the more-powerful and pretty MinTTY terminal emulator.

There are always numerous ways to accomplish what you are trying to set out to do; it's just a matter of combining the right tools for the job, and many times it boils down to personal preference.

shuffling/permutating a DataFrame in pandas

I resorted to adapting @root 's answer slightly and using the raw values directly. Of course, this means you lose the ability to do fancy indexing but it works perfectly for just shuffling the data.

In [1]: import numpy

In [2]: import pandas

In [3]: df = pandas.DataFrame({"A": range(10), "B": range(10)})    

In [4]: %timeit df.apply(numpy.random.shuffle, axis=0)
1000 loops, best of 3: 406 µs per loop

In [5]: %%timeit
   ...: for view in numpy.rollaxis(df.values, 1):
   ...:     numpy.random.shuffle(view)
10000 loops, best of 3: 22.8 µs per loop

In [6]: %timeit df.apply(numpy.random.shuffle, axis=1)
1000 loops, best of 3: 746 µs per loop

In [7]: %%timeit                                      
for view in numpy.rollaxis(df.values, 0):
10000 loops, best of 3: 23.4 µs per loop

Note that numpy.rollaxis brings the specified axis to the first dimension and then let's us iterate over arrays with the remaining dimensions, i.e., if we want to shuffle along the first dimension (columns), we need to roll the second dimension to the front, so that we apply the shuffling to views over the first dimension.

In [8]: numpy.rollaxis(df, 0).shape
Out[8]: (10, 2) # we can iterate over 10 arrays with shape (2,) (rows)

In [9]: numpy.rollaxis(df, 1).shape
Out[9]: (2, 10) # we can iterate over 2 arrays with shape (10,) (columns)

Your final function then uses a trick to bring the result in line with the expectation for applying a function to an axis:

def shuffle(df, n=1, axis=0):     
    df = df.copy()
    axis = int(not axis) # pandas.DataFrame is always 2D
    for _ in range(n):
        for view in numpy.rollaxis(df.values, axis):
    return df

Set a cookie to HttpOnly via Javascript

An HttpOnly cookie means that it's not available to scripting languages like JavaScript. So in JavaScript, there's absolutely no API available to get/set the HttpOnly attribute of the cookie, as that would otherwise defeat the meaning of HttpOnly.

Just set it as such on the server side using whatever server side language the server side is using. If JavaScript is absolutely necessary for this, you could consider to just let it send some (ajax) request with e.g. some specific request parameter which triggers the server side language to create an HttpOnly cookie. But, that would still make it easy for hackers to change the HttpOnly by just XSS and still have access to the cookie via JS and thus make the HttpOnly on your cookie completely useless.

Python one-line "for" expression

Even array2.extend(array1) will work.

javascript regular expression to not match a word

if (!s.match(/abc|def/g)) {
else {
    alert("no match");

char initial value in Java

As you will see in linked discussion there is no need for initializing char with special character as it's done for us and is represented by '\u0000' character code.

So if we want simply to check if specified char was initialized just write:

if(charVariable != '\u0000'){

Link to question: what's the default value of char?

how to loop through each row of dataFrame in pyspark

To "loop" and take advantage of Spark's parallel computation framework, you could define a custom function and use map.

def customFunction(row):

   return (, row.age,

sample2 =


sample2 = x: (, x.age,

The custom function would then be applied to every row of the dataframe. Note that sample2 will be a RDD, not a dataframe.

Map may be needed if you are going to perform more complex computations. If you just need to add a simple derived column, you can use the withColumn, with returns a dataframe.

sample3 = sample.withColumn('age2', sample.age + 2)

Checking if an object is null in C#

Here are some extensions I use:

/// <summary>
/// Extensions to the object class
/// </summary>
public static class ObjectExtensions
    /// <summary>
    /// True if the object is null, else false
    /// </summary>
    public static bool IsNull(this object input) => input is null;

    /// <summary>
    /// False if the object is null, else true
    /// </summary>
    public static bool NotNull(this object input) => !IsNull(input);

sh: react-scripts: command not found after running npm start

I ran into this error after renaming the directory with the @/ symbol on macOS to match the name of my NPM package namespace.

When the NPM command looked for installed packages in my local node_modules, it couldn't find it due to the way macOS was rewriting the directory path. After renaming the directory without @/ I was up and running again.

Quick easy way to migrate SQLite3 to MySQL?

Ha... I wish I had found this first! My response was to this post... script to convert mysql dump sql file into format that can be imported into sqlite3 db

Combining the two would be exactly what I needed:

When the sqlite3 database is going to be used with ruby you may want to change:



sed 's/ tinyint(1*) / boolean/g ' |
sed 's/ tinyint([0|2-9]*) / integer /g' |

alas, this only half works because even though you are inserting 1's and 0's into a field marked boolean, sqlite3 stores them as 1's and 0's so you have to go through and do something like:

Table.find(:all, :conditions => {:column => 1 }).each { |t| t.column = true }.each(&:save)
Table.find(:all, :conditions => {:column => 0 }).each { |t| t.column = false}.each(&:save)

but it was helpful to have the sql file to look at to find all the booleans.

foreach vs someList.ForEach(){}

The second way you showed uses an extension method to execute the delegate method for each of the elements in the list.

This way, you have another delegate (=method) call.

Additionally, there is the possibility to iterate the list with a for loop.

"Content is not allowed in prolog" when parsing perfectly valid XML on GAE

I was facing the same problem called "Content is not allowed in prolog" in my xml file.


Initially my root folder was '#Filename'.

When i removed the first character '#' ,the error got resolved.

No need of removing the #filename... Try in this way..

Instead of passing a File or URL object to the unmarshaller method, use a FileInputStream.

File myFile = new File("........");
Object obj = unmarshaller.unmarshal(new FileInputStream(myFile));

How To Inject AuthenticationManager using Java Configuration in a Custom Filter

Override method authenticationManagerBean in WebSecurityConfigurerAdapter to expose the AuthenticationManager built using configure(AuthenticationManagerBuilder) as a Spring bean:

For example:

   public AuthenticationManager authenticationManagerBean() throws Exception {
       return super.authenticationManagerBean();

Using Jasmine to spy on a function without an object

My answer differs slightly to @FlavorScape in that I had a single (default export) function in the imported module, I did the following:

import * as functionToTest from 'whatever-lib';

const fooSpy = spyOn(functionToTest, 'default');

Restful API service

Lets say I want to start the service on an event - onItemClicked() of a button. The Receiver mechanism would not work in that case because :-
a) I passed the Receiver to the service (as in Intent extra) from onItemClicked()
b) Activity moves to the background. In onPause() I set the receiver reference within the ResultReceiver to null to avoid leaking the Activity.
c) Activity gets destroyed.
d) Activity gets created again. However at this point the Service will not be able to make a callback to the Activity as that receiver reference is lost.
The mechanism of a limited broadcast or a PendingIntent seems to be more usefull in such scenarios- refer to Notify activity from service

json: cannot unmarshal object into Go value of type

You JSON doesn't match your struct fields: E.g. "district" in JSON and "District" as the field.

Also: Your Item is a slice type but your JSON is a dict value. Do not mix this up. Slices decode from arrays.

How to present popover properly in iOS 8

I made an Objective-C version of Imagine Digitals swift answer above. I don't think I missed anything as it seems to work under preliminary testing, if you spot something let me know, and I'll update it

-(void) presentPopover
    YourViewController* popoverContent = [[YourViewController alloc] init]; //this will be a subclass of UIViewController
    UINavigationController* nav =  [[UINavigationController alloc] initWithRootViewController:popoverContent];
    nav.modalPresentationStyle = UIModalPresentationPopover;
    UIPopoverPresentationController* popover = nav.popoverPresentationController;
    popoverContent.preferredContentSize = CGSizeMake(500,600);
    popover.delegate = self;
    popover.sourceRect = CGRectMake(100,100,0,0); //I actually used popover.barButtonItem = self.myBarButton;

    [self presentViewController:nav animated:YES completion:nil];

val() vs. text() for textarea

.val() always works with textarea elements.

.text() works sometimes and fails other times! It's not reliable (tested in Chrome 33)

What's best is that .val() works seamlessly with other form elements too (like input) whereas .text() fails.

Add items in array angular 4

Yes there is a way to do it.

First declare a class.

export class Custom
  name: string, 
  empoloyeeID: number

Then in your component import the class

import {Custom} from '../path/to/anyfile.ts'
export class FormComponent implements OnInit {
 name: string;
 empoloyeeID : number;
 empList: Array<Custom> = [];
 constructor() {


 ngOnInit() {
   let customObj = new Custom(); = "something";
   customObj.employeeId = 12; 
   this.empList.push(customObj); ="";
   this.empoloyeeID = 0; 

Another way would be to interfaces read the documentation once -

Also checkout this question, it is very interesting - When to use Interface and Model in TypeScript / Angular2

Run-time error '1004' - Method 'Range' of object'_Global' failed


Range(DataImportColumn & DataImportRow).Offset(0, 2).Value



When you just have the row and the column then you can use the cells() object. The syntax is Cells(Row,Column)

Also one more tip. You might want to fully qualify your Cells object. for example


Floating point exception( core dump

Floating Point Exception happens because of an unexpected infinity or NaN. You can track that using gdb, which allows you to see what is going on inside your C program while it runs. For more details:

In a nutshell, these commands might be useful...

gcc -g myprog.c

gdb a.out

gdb core a.out

ddd a.out

Using Chrome's Element Inspector in Print Preview Mode?

Chrome v50:

Way 1:

  1. Menu > More Tools > Rendering settings (see image)
  2. Down: Rendering Tab > Emulate media "print"

Way 2:

  1. Open Console [esc]
  2. Console Menu > rendering

Basic Authentication Using JavaScript

After Spending quite a bit of time looking into this, i came up with the solution for this; In this solution i am not using the Basic authentication but instead went with the oAuth authentication protocol. But to use Basic authentication you should be able to specify this in the "setHeaderRequest" with minimal changes to the rest of the code example. I hope this will be able to help someone else in the future:

var token_ // variable will store the token
var userName = "clientID"; // app clientID
var passWord = "secretKey"; // app clientSecret
var caspioTokenUrl = ""; // Your application token endpoint  
var request = new XMLHttpRequest(); 

function getToken(url, clientID, clientSecret) {
    var key;      "POST", url, true); 
    request.setRequestHeader("Content-type", "application/json");
    request.send("grant_type=client_credentials&client_id="+clientID+"&"+"client_secret="+clientSecret); // specify the credentials to receive the token on request
    request.onreadystatechange = function () {
        if (request.readyState == request.DONE) {
            var response = request.responseText;
            var obj = JSON.parse(response); 
            key = obj.access_token; //store the value of the accesstoken
            token_ = key; // store token in your global variable "token_" or you could simply return the value of the access token from the function
// Get the token
getToken(caspioTokenUrl, userName, passWord);

If you are using the Caspio REST API on some request it may be imperative that you to encode the paramaters for certain request to your endpoint; see the Caspio documentation on this issue;

NOTE: encodedParams is NOT used in this example but was used in my solution.

Now that you have the token stored from the token endpoint you should be able to successfully authenticate for subsequent request from the caspio resource endpoint for your application

function CallWebAPI() {
    var request_ = new XMLHttpRequest();        
    var encodedParams = encodeURIComponent(params);"GET", "", true);
    request_.setRequestHeader("Authorization", "Bearer "+ token_);
    request_.onreadystatechange = function () {
        if (request_.readyState == 4 && request_.status == 200) {
            var response = request_.responseText;
            var obj = JSON.parse(response); 
            // handle data as needed... 


This solution does only considers how to successfully make the authenticated request using the Caspio API in pure javascript. There are still many flaws i am sure...

How do you set the title color for the new Toolbar?

Very simple, this worked for me (title and icon white):

    android:elevation="4dp" />

Changing the selected option of an HTML Select element

None of the examples using jquery in here are actually correct as they will leave the select displaying the first entry even though value has been changed.

The right way to select Alaska and have the select show the right item as selected using:

<select id="state">
    <option value="AL">Alabama</option>
    <option value="AK">Alaska</option>
    <option value="AZ">Arizona</option>

With jquery would be:


No Such Element Exception?

I Know this question was aked 3 years ago, but I just had the same problem, and what solved it was instead of putting:

 while (i.hasNext()) {
    // code goes here 

I did one iteration at the start, and then checked for condition using:

do {
   // code goes here
} while (i.hasNext());

I hope this will help some people at some stage.

How Do I Uninstall Yarn

If you installed with brew, try brew uninstall yarn at terminal prompt. Also remember to remove yarn path info in your .bash_profile.

Where can I find free WPF controls and control templates?

I strongly recommend the MahApps it's simply awesome!

Best way to test exceptions with Assert to ensure they will be thrown

I'm new here and don't have the reputation to comment or downvote, but wanted to point out a flaw in the example in Andy White's reply:

    Assert.Fail("Should have exceptioned above!");
catch (Exception ex)
    // whatever logging code

In all unit testing frameworks I am familiar with, Assert.Fail works by throwing an exception, so the generic catch will actually mask the failure of the test. If SomethingThatCausesAnException() does not throw, the Assert.Fail will, but that will never bubble out to the test runner to indicate failure.

If you need to catch the expected exception (i.e., to assert certain details, like the message / properties on the exception), it's important to catch the specific expected type, and not the base Exception class. That would allow the Assert.Fail exception to bubble out (assuming you aren't throwing the same type of exception that your unit testing framework does), but still allow validation on the exception that was thrown by your SomethingThatCausesAnException() method.

React prevent event bubbling in nested components on click

This is not 100% ideal, but if it is either too much of a pain to pass down props in children -> children fashion or create a Context.Provider/Context.Consumer just for this purpose), and you are dealing with another library which has it's own handler it runs before yours, you can also try:

   function myHandler(e) { 

From what I understand, the event.persist method prevents an object from immediately being thrown back into React's SyntheticEvent pool. So because of that, the event passed in React actually doesn't exist by the time you reach for it! This happens in grandchildren because of the way React handle's things internally by first checking parent on down for SyntheticEvent handlers (especially if the parent had a callback).

As long as you are not calling persist on something which would create significant memory to keep creating events such as onMouseMove (and you are not creating some kind of Cookie Clicker game like Grandma's Cookies), it should be perfectly fine!

Also note: from reading around their GitHub occasionally, we should keep our eyes out for future versions of React as they may eventually resolve some of the pain with this as they seem to be going towards making folding React code in a compiler/transpiler.

Eclipse CDT project built but "Launch Failed. Binary Not Found"

This happened to me and I found a solution, see if this works for you:

Once you have built your project with the hammer icon:

  1. select "Run".
  2. Run Configurations.
  3. Choose "C++ Application".
  4. Click on the "New Launch Configuration" icon on the top left of the open window.
  5. Select "Browse" under the C/C++ Application.
  6. Browse to the folder where you made your project initially.
  7. Enter the Debug folder.
  8. Click on the binary file with the same name as the project.
  9. Select "OK".
  10. Click "Apply" to confirm the link you just set.
  11. Close that window.

Afterwards you should be able to run the project as much as you'd like.

Hopefully this works for you.

Copy directory to another directory using ADD command

You can use COPY. You need to specify the directory explicitly. It won't be created by itself

COPY go /usr/local/go

Reference: Docker CP reference

What EXACTLY is meant by "de-referencing a NULL pointer"?

A NULL pointer points to memory that doesn't exist, and will raise Segmentation fault. There's an easier way to de-reference a NULL pointer, take a look.

int main(int argc, char const *argv[])
    *(int *)0 = 0; // Segmentation fault (core dumped)
    return 0;

Since 0 is never a valid pointer value, a fault occurs.

SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=NULL}

PopupWindow $BadTokenException: Unable to add window -- token null is not valid

you are showing your popup too early. You may post a delayed runnable for showatlocation in Onresume , Give it a try

Edit: This post seems to have the same problem answered Problems creating a Popup Window in Android Activity

Can I update a component's props in React.js?

Trick to update props if they are array :

import React, { Component } from 'react';
import {
} from 'react-native';

class Counter extends Component {
  constructor(props) {
      this.state = {
        count: this.props.count
    let count = this.state.count
    count.push("new element");
    this.setState({ count: count})
  render() {

    return (
      <View style={styles.container}>
        <Text>{ this.state.count.length }</Text>
          title={ "Increase" }

Counter.defaultProps = {
 count: []

export default Counter
const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#F5FCFF',
  welcome: {
    fontSize: 20,
    textAlign: 'center',
    margin: 10,
  instructions: {
    textAlign: 'center',
    color: '#333333',
    marginBottom: 5,

Select 50 items from list at random to write to file

One easy way to select random items is to shuffle then slice.

import random
a = [1,2,3,4,5,6,7,8,9]
print a[:4] # prints 4 random variables

numpy matrix vector multiplication

Simplest solution

Use or See the documentation here.

>>> a = np.array([[ 5, 1 ,3], 
                  [ 1, 1 ,1], 
                  [ 1, 2 ,1]])
>>> b = np.array([1, 2, 3])
>>> print
array([16, 6, 8])

This occurs because numpy arrays are not matrices, and the standard operations *, +, -, / work element-wise on arrays. Instead, you could try using numpy.matrix, and * will be treated like matrix multiplication.

Other Solutions

Also know there are other options:

  • As noted below, if using python3.5+ the @ operator works as you'd expect:

    >>> print(a @ b)
    array([16, 6, 8])
  • If you want overkill, you can use numpy.einsum. The documentation will give you a flavor for how it works, but honestly, I didn't fully understand how to use it until reading this answer and just playing around with it on my own.

    >>> np.einsum('ji,i->j', a, b)
    array([16, 6, 8])
  • As of mid 2016 (numpy 1.10.1), you can try the experimental numpy.matmul, which works like with two major exceptions: no scalar multiplication but it works with stacks of matrices.

    >>> np.matmul(a, b)
    array([16, 6, 8])
  • numpy.inner functions the same way as for matrix-vector multiplication but behaves differently for matrix-matrix and tensor multiplication (see Wikipedia regarding the differences between the inner product and dot product in general or see this SO answer regarding numpy's implementations).

    >>> np.inner(a, b)
    array([16, 6, 8])
    # Beware using for matrix-matrix multiplication though!
    >>> b = a.T
    >>>, b)
    array([[35,  9, 10],
           [ 9,  3,  4],
           [10,  4,  6]])
    >>> np.inner(a, b) 
    array([[29, 12, 19],
           [ 7,  4,  5],
           [ 8,  5,  6]])

Rarer options for edge cases

  • If you have tensors (arrays of dimension greater than or equal to one), you can use numpy.tensordot with the optional argument axes=1:

    >>> np.tensordot(a, b, axes=1)
    array([16,  6,  8])
  • Don't use numpy.vdot if you have a matrix of complex numbers, as the matrix will be flattened to a 1D array, then it will try to find the complex conjugate dot product between your flattened matrix and vector (which will fail due to a size mismatch n*m vs n).

jQuery event is triggered twice

I've found that binding an in a function that happens more than once will queue it so next time you click it, it will trigger as many times as the binding function was executed. Newcomer mistake probably on my end but I hope it helps. TL,DR: Make sure you bind all clicks on a setup function that only happens once.

Is it possible to get multiple values from a subquery?

Here are two methods to get more than 1 column in a scalar subquery (or inline subquery) and querying the lookup table only once. This is a bit convoluted but can be the very efficient in some special cases.

  1. You can use concatenation to get several columns at once:

    SELECT x, 
           regexp_substr(yz, '[^^]+', 1, 1) y,
           regexp_substr(yz, '[^^]+', 1, 2) z
      FROM (SELECT a.x,
                   (SELECT b.y || '^' || b.z yz
                      FROM b
                     WHERE b.v = a.v)
              FROM a)

    You would need to make sure that no column in the list contain the separator character.

  2. You could also use SQL objects:

    CREATE OR REPLACE TYPE b_obj AS OBJECT (y number, z number);
    SELECT x, 
           v.yz.y y,
           v.yz.z z
      FROM (SELECT a.x,
                   (SELECT b_obj(y, z) yz
                      FROM b
                     WHERE b.v = a.v)
              FROM a) v

Prompt Dialog in Windows Forms

Here's an example in VB.NET

Public Function ShowtheDialog(caption As String, text As String, selStr As String) As String
    Dim prompt As New Form()
    prompt.Width = 280
    prompt.Height = 160
    prompt.Text = caption
    Dim textLabel As New Label() With { _
         .Left = 16, _
         .Top = 20, _
         .Width = 240, _
         .Text = text _
    Dim textBox As New TextBox() With { _
         .Left = 16, _
         .Top = 40, _
         .Width = 240, _
         .TabIndex = 0, _
         .TabStop = True _
    Dim selLabel As New Label() With { _
         .Left = 16, _
         .Top = 66, _
         .Width = 88, _
         .Text = selStr _
    Dim cmbx As New ComboBox() With { _
         .Left = 112, _
         .Top = 64, _
         .Width = 144 _
    cmbx.Items.Add("Dark Grey")
    cmbx.SelectedIndex = 0
    Dim confirmation As New Button() With { _
         .Text = "In Ordnung!", _
         .Left = 16, _
         .Width = 80, _
         .Top = 88, _
         .TabIndex = 1, _
         .TabStop = True _
    AddHandler confirmation.Click, Sub(sender, e) prompt.Close()
    prompt.AcceptButton = confirmation
    prompt.StartPosition = FormStartPosition.CenterScreen
    Return String.Format("{0};{1}", textBox.Text, cmbx.SelectedItem.ToString())
End Function

How to get an HTML element's style values in javascript?

In jQuery, you can do alert($("#theid").css("width")).

-- if you haven't taken a look at jQuery, I highly recommend it; it makes many simple javascript tasks effortless.


for the record, this post is 5 years old. The web has developed, moved on, etc. There are ways to do this with Plain Old Javascript, which is better.

Why do I get the error "Unsafe code may only appear if compiling with /unsafe"?

For everybody who uses Rider you have to select your project>Right Click>Properties>Configurations Then select Debug and Release and check "Allow unsafe code" for both.Screenshot

Check if input is integer type in C

First ask yourself how you would ever expect this code to NOT return an integer:

int num; 

You specified the variable as type integer, then you scanf, but only for an integer (%d).

What else could it possibly contain at this point?

How do I change Eclipse to use spaces instead of tabs?

I found the solution this problem very simple and which works always. It is change the eclipse setting file.

For example (change HTML indentation size):

  1. Found org.eclipse.wst.html.core.prefs file which should be in your_workspace/.metadata/.plugins/org.eclipse.core.runtime/.settings/
  2. Add/Change to line in file:


What is an ORM, how does it work, and how should I use one?


Object-Relational Mapping (ORM) is a technique that lets you query and manipulate data from a database using an object-oriented paradigm. When talking about ORM, most people are referring to a library that implements the Object-Relational Mapping technique, hence the phrase "an ORM".

An ORM library is a completely ordinary library written in your language of choice that encapsulates the code needed to manipulate the data, so you don't use SQL anymore; you interact directly with an object in the same language you're using.

For example, here is a completely imaginary case with a pseudo language:

You have a book class, you want to retrieve all the books of which the author is "Linus". Manually, you would do something like that:

book_list = new List();
sql = "SELECT book FROM library WHERE author = 'Linus'";
data = query(sql); // I over simplify ...
while (row =
     book = new Book();

With an ORM library, it would look like this:

book_list = BookTable.query(author="Linus");

The mechanical part is taken care of automatically via the ORM library.

Pros and Cons

Using ORM saves a lot of time because:

  • DRY: You write your data model in only one place, and it's easier to update, maintain, and reuse the code.
  • A lot of stuff is done automatically, from database handling to I18N.
  • It forces you to write MVC code, which, in the end, makes your code a little cleaner.
  • You don't have to write poorly-formed SQL (most Web programmers really suck at it, because SQL is treated like a "sub" language, when in reality it's a very powerful and complex one).
  • Sanitizing; using prepared statements or transactions are as easy as calling a method.

Using an ORM library is more flexible because:

  • It fits in your natural way of coding (it's your language!).
  • It abstracts the DB system, so you can change it whenever you want.
  • The model is weakly bound to the rest of the application, so you can change it or use it anywhere else.
  • It lets you use OOP goodness like data inheritance without a headache.

But ORM can be a pain:

  • You have to learn it, and ORM libraries are not lightweight tools;
  • You have to set it up. Same problem.
  • Performance is OK for usual queries, but a SQL master will always do better with his own SQL for big projects.
  • It abstracts the DB. While it's OK if you know what's happening behind the scene, it's a trap for new programmers that can write very greedy statements, like a heavy hit in a for loop.

How to learn about ORM?

Well, use one. Whichever ORM library you choose, they all use the same principles. There are a lot of ORM libraries around here:

If you want to try an ORM library in Web programming, you'd be better off using an entire framework stack like:

  • Symfony (PHP, using Propel or Doctrine).
  • Django (Python, using a internal ORM).

Do not try to write your own ORM, unless you are trying to learn something. This is a gigantic piece of work, and the old ones took a lot of time and work before they became reliable.

Open file in a relative location in Python

It depends on what operating system you're using. If you want a solution that is compatible with both Windows and *nix something like:

from os import path

file_path = path.relpath("2091/data.txt")
with open(file_path) as f:
    <do stuff>

should work fine.

The path module is able to format a path for whatever operating system it's running on. Also, python handles relative paths just fine, so long as you have correct permissions.


As mentioned by kindall in the comments, python can convert between unix-style and windows-style paths anyway, so even simpler code will work:

with open("2091/data/txt") as f:
    <do stuff>

That being said, the path module still has some useful functions.

How to check if a string array contains one string in JavaScript?

var stringArray = ["String1", "String2", "String3"];

return (stringArray.indexOf(searchStr) > -1)

Clone an image in cv2 python

The first answer is correct but you say that you are using cv2 which inherently uses numpy arrays. So, to make a complete different copy of say "myImage":

newImage = myImage.copy()

The above is enough. No need to import numpy.

How do I generate a stream from a string?

I think you can benefit from using a MemoryStream. You can fill it with the string bytes that you obtain by using the GetBytes method of the Encoding class.

jquery remove "selected" attribute of option?

Similar to @radiak's response, but with jQuery (see this API document and comment on how to change the selectedIndex).


The benefits to this approach are:

  • You can stay within jQuery
  • You can limit the scope using jQuery selectors (#mySelectParent in the example)
  • More explicitly defined code
  • Works in IE8, Chrome, FF

How to run single test method with phpunit?

  • Run this inside your project root directory i am using in laravel root directory.

vendor/bin/phpunit --filter 'Your method name'

Example with custom method name.

 /** @test //Initilize this for custom method name, without test keyword
  * Test case For Dashboard When User Not logged In it will redirect To login page
  public function only_logged_in_user_see_dashboard()
    $response = $this->get('/dashboard')

Example with test keyword

* A basic test example.
* @return void
 public function testBasicTest()

A better way to check if a path exists or not in PowerShell

Add the following aliases. I think these should be made available in PowerShell by default:

function not-exist { -not (Test-Path $args) }
Set-Alias !exist not-exist -Option "Constant, AllScope"
Set-Alias exist Test-Path -Option "Constant, AllScope"

With that, the conditional statements will change to:

if (exist $path) { ... }


if (not-exist $path) { ... }
if (!exist $path) { ... }

How to validate an Email in PHP?


var_dump(filter_var('[email protected]', FILTER_VALIDATE_EMAIL));
$validator = new EmailValidator();
$multipleValidations = new MultipleValidationWithAnd([
    new RFCValidation(),
    new DNSCheckValidation()
$validator->isValid("[email protected]", $multipleValidations); //true

Ubuntu - Run command on start-up with "sudo"

Edit the tty configuration in /etc/init/tty*.conf with a shellscript as a parameter :

exec /sbin/getty -n -l -8 38400 tty1

This is assuming that we're editing tty1 and the script that reads input is

A word of warning this script is run as root, so when you are inputing stuff to it you have root priviliges. Also append a path to the location of the script.

Important: the script when it finishes, has to invoke the /sbin/login otherwise you wont be able to login in the terminal.

firefox proxy settings via command line

user.js is better for customizations as you can include only the lines you want to manipulate, i.e. instead of find-replace you can just overwrite the entire file. Also, prefs.js (at least on Firefox 65.0.1 for Mac) starts with a warning:

// If you make changes to this file while the application is running,
// the changes will be overwritten when the application exits.
// To change a preference value, you can either:
// - modify it via the UI (e.g. via about:config in the browser); or
// - set it within a user.js file in your profile.

In my case, user.js didn't exist, so I created it and included the line to switch between "No proxy" and "Manual proxy configuration" (I'm using only one SOCKS proxy all the time, so no need to change port number or any other details, just flip 0 to 1 in the following line):

user_pref("network.proxy.type", 1);

I ended up with a bash script that I placed at /usr/local/bin/firefox:

if [ $# -eq 0 ]; then
  echo 'user_pref("network.proxy.type", 0);' > ~/Library/Application\ Support/Firefox/Profiles/t5rvw47o.default/user.js
  open -a Firefox
  case $1 in
      echo 'user_pref("network.proxy.type", 1);' > ~/Library/Application\ Support/Firefox/Profiles/t5rvw47o.default/user.js
      open -a Firefox

To use it, I make sure no Firefox is running and then run firefox to have a straight connection and firefox vpn to use proxy.

C++: Print out enum value as text

Use an array or vector of strings with matching values:

char *ErrorTypes[] =

cout << ErrorTypes[anError];

EDIT: The solution above is applicable when the enum is contiguous, i.e. starts from 0 and there are no assigned values. It will work perfectly with the enum in the question.

To further proof it for the case that enum doesn't start from 0, use:

cout << ErrorTypes[anError - ErrorA];

How do I fix the multiple-step OLE DB operation errors in SSIS?

This error is common when the source table contains a TEXT column and the target is anything other than a TEXT column. It can be a real time-eater if you have not encountered (or forgot!) this before.

Convert the text column to string and set the error condition on truncation to ignore. this will usually serve as a solution for this error.

How to print a number with commas as thousands separators in JavaScript

Let me try to improve uKolka's answer and maybe help others save some time.

Use Numeral.js.

document.body.textContent = numeral(1234567).format('0,0');
<script src="//"></script>

You should go with Number.prototype.toLocaleString() only if its browser compatibilty is not an issue.

Maven Jacoco Configuration - Exclude classes/packages from report not working

you can configure the coverage exclusion in the sonar properties, outside of the configuration of the jacoco plugin:


and remember to remove the exclusion settings from the plugin

Converting a factor to numeric without losing information R (as.numeric() doesn't seem to work)

First, factor consists of indices and levels. This fact is very very important when you are struggling with factor.

For example,

> z <- factor(letters[c(3, 2, 3, 4)])

# human-friendly display, but internal structure is invisible
> z
[1] c b c d
Levels: b c d

# internal structure of factor
> unclass(z)
[1] 2 1 2 3
[1] "b" "c" "d"

here, z has 4 elements.
The index is 2, 1, 2, 3 in that order.
The level is associated with each index: 1 -> b, 2 -> c, 3 -> d.

Then, as.numeric converts simply the index part of factor into numeric.
as.character handles the index and levels, and generates character vector expressed by its level.

?as.numeric says that Factors are handled by the default method.

Free tool to Create/Edit PNG Images?

Inkscape is a vector drawing program that exports PNG images. So, you end up editing SVG documents and exporting them to PNGs. Inkscape is good if you're starting from scratch, but wouldn't be ideal if you just want to edit existing PNGs.

Note--Inkscape is open source and available for free on multiple platforms.

VBA Print to PDF and Save with Automatic File Name

Hopefully this is self explanatory enough. Use the comments in the code to help understand what is happening. Pass a single cell to this function. The value of that cell will be the base file name. If the cell contains "AwesomeData" then we will try and create a file in the current users desktop called AwesomeData.pdf. If that already exists then try AwesomeData2.pdf and so on. In your code you could just replace the lines filename = Application..... with filename = GetFileName(Range("A1"))

Function GetFileName(rngNamedCell As Range) As String
    Dim strSaveDirectory As String: strSaveDirectory = ""
    Dim strFileName As String: strFileName = ""
    Dim strTestPath As String: strTestPath = ""
    Dim strFileBaseName As String: strFileBaseName = ""
    Dim strFilePath As String: strFilePath = ""
    Dim intFileCounterIndex As Integer: intFileCounterIndex = 1

    ' Get the users desktop directory.
    strSaveDirectory = Environ("USERPROFILE") & "\Desktop\"
    Debug.Print "Saving to: " & strSaveDirectory

    ' Base file name
    strFileBaseName = Trim(rngNamedCell.Value)
    Debug.Print "File Name will contain: " & strFileBaseName

    ' Loop until we find a free file number
        If intFileCounterIndex > 1 Then
            ' Build test path base on current counter exists.
            strTestPath = strSaveDirectory & strFileBaseName & Trim(Str(intFileCounterIndex)) & ".pdf"
            ' Build test path base just on base name to see if it exists.
            strTestPath = strSaveDirectory & strFileBaseName & ".pdf"
        End If

        If (Dir(strTestPath) = "") Then
            ' This file path does not currently exist. Use that.
            strFileName = strTestPath
            ' Increase the counter as we have not found a free file yet.
            intFileCounterIndex = intFileCounterIndex + 1
        End If

    Loop Until strFileName <> ""

    ' Found useable filename
    Debug.Print "Free file name: " & strFileName
    GetFileName = strFileName

End Function

The debug lines will help you figure out what is happening if you need to step through the code. Remove them as you see fit. I went a little crazy with the variables but it was to make this as clear as possible.

In Action

My cell O1 contained the string "FileName" without the quotes. Used this sub to call my function and it saved a file.

Sub Testing()
    Dim filename As String: filename = GetFileName(Range("o1"))

    ActiveWorkbook.Worksheets("Sheet1").Range("A1:N24").ExportAsFixedFormat Type:=xlTypePDF, _
                                              filename:=filename, _
                                              Quality:=xlQualityStandard, _
                                              IncludeDocProperties:=True, _
                                              IgnorePrintAreas:=False, _
End Sub

Where is your code located in reference to everything else? Perhaps you need to make a module if you have not already and move your existing code into there.

Please explain about insertable=false and updatable=false in reference to the JPA @Column annotation

Defining insertable=false, updatable=false is useful when you need to map a field more than once in an entity, typically:

This is IMO not a semantical thing, but definitely a technical one.

What type of hash does WordPress use?

Start phpMyAdmin and access wp_users from your wordpress instance. Edit record and select user_pass function to match MD5. Write the string that will be your new password in VALUE. Click, GO. Go to your wordpress website and enter your new password. Back to phpMyAdmin you will see that WP changed the HASH to something like $P$B... enjoy!