Programs & Examples On #Momentum

How to load a model from an HDF5 file in Keras?

load_weights only sets the weights of your network. You still need to define its architecture before calling load_weights:

def create_model():
   model = Sequential()
   model.add(Dense(64, input_dim=14, init='uniform'))
   model.add(BatchNormalization(epsilon=1e-06, mode=0, momentum=0.9, weights=None))
   model.add(Dense(64, init='uniform'))
   model.add(BatchNormalization(epsilon=1e-06, mode=0, momentum=0.9, weights=None))
   model.add(Dense(2, init='uniform'))
   return model

def train():
   model = create_model()
   sgd = SGD(lr=0.1, decay=1e-6, momentum=0.9, nesterov=True)
   model.compile(loss='binary_crossentropy', optimizer=sgd)

   checkpointer = ModelCheckpoint(filepath="/tmp/weights.hdf5", verbose=1, save_best_only=True), y_train, nb_epoch=20, batch_size=16, show_accuracy=True, validation_split=0.2, verbose=2, callbacks=[checkpointer])

def load_trained_model(weights_path):
   model = create_model()

Where do I call the BatchNormalization function in Keras?

Batch Normalization is used to normalize the input layer as well as hidden layers by adjusting mean and scaling of the activations. Because of this normalizing effect with additional layer in deep neural networks, the network can use higher learning rate without vanishing or exploding gradients. Furthermore, batch normalization regularizes the network such that it is easier to generalize, and it is thus unnecessary to use dropout to mitigate overfitting.

Right after calculating the linear function using say, the Dense() or Conv2D() in Keras, we use BatchNormalization() which calculates the linear function in a layer and then we add the non-linearity to the layer using Activation().

from keras.layers.normalization import BatchNormalization
model = Sequential()
model.add(Dense(64, input_dim=14, init='uniform'))
model.add(BatchNormalization(epsilon=1e-06, mode=0, momentum=0.9, weights=None))
model.add(Dense(64, init='uniform'))
model.add(BatchNormalization(epsilon=1e-06, mode=0, momentum=0.9, weights=None))
model.add(Dense(2, init='uniform'))
model.add(BatchNormalization(epsilon=1e-06, mode=0, momentum=0.9, weights=None))

sgd = SGD(lr=0.1, decay=1e-6, momentum=0.9, nesterov=True)
model.compile(loss='binary_crossentropy', optimizer=sgd), y_train, nb_epoch=20, batch_size=16, show_accuracy=True, 
validation_split=0.2, verbose = 2)

How is Batch Normalization applied?

Suppose we have input a[l-1] to a layer l. Also we have weights W[l] and bias unit b[l] for the layer l. Let a[l] be the activation vector calculated(i.e. after adding the non-linearity) for the layer l and z[l] be the vector before adding non-linearity

  1. Using a[l-1] and W[l] we can calculate z[l] for the layer l
  2. Usually in feed-forward propagation we will add bias unit to the z[l] at this stage like this z[l]+b[l], but in Batch Normalization this step of addition of b[l] is not required and no b[l] parameter is used.
  3. Calculate z[l] means and subtract it from each element
  4. Divide (z[l] - mean) using standard deviation. Call it Z_temp[l]
  5. Now define new parameters ? and ß that will change the scale of the hidden layer as follows:

    z_norm[l] = ?.Z_temp[l] + ß

In this code excerpt, the Dense() takes the a[l-1], uses W[l] and calculates z[l]. Then the immediate BatchNormalization() will perform the above steps to give z_norm[l]. And then the immediate Activation() will calculate tanh(z_norm[l]) to give a[l] i.e.

a[l] = tanh(z_norm[l])

Horizontal swipe slider with jQuery and touch devices support?

In my opinion iosSlider is amazing. It works in almost any device and it is well documented. It's free for personal usage, but for commercial sites license costs $20.

Also a great option is touchCarousel or RoyalSlider from same author. These two have everything you'll need, but also not free and have a price of $10-12

Good ways to manage a changelog using git?

For a GNU style changelog, I've cooked the function

gnuc() {
    printf "$(date "+%Y-%m-%d")  John Doe  <[email protected]>\n\n"
    git diff-tree --no-commit-id --name-only -r HEAD | sed 's/^/\t* /'
  } | tee /dev/tty | xsel -b

With this:

  • I commit my changes periodically to backup and rebase them before doing the final edit to the ChangeLog
  • then run: gnuc

and now my clipboard contains something like:

2015-07-24  John Doe  <[email protected]>

        * gdb/python/py-linetable.c (): .
        * gdb/python/py-symtab.c (): .

Then I use the clipboard as a starting point to update the ChangeLog.

It is not perfect (e.g. files should be relative to their ChangeLog path, so python/py-symtab.c without gdb/ since I will edit the gdb/ChangeLog), but is a good starting point.

More advanced scripts:

I have to agree with Tromey though: duplicating git commit data in the ChangeLog is useless.

If you are going to make a changelog, make it a good summary of what is going on, possibly as specified at

What's is the difference between train, validation and test set, in neural networks?

Would appreciate any thoughts on the situation with 3 data sets. Say a logistic regression model is fitted yielding the following accuracy (Gini): Train: 70%; Test 58% and Out-of-time validation: 66%.

Actually all the possible combinations of predictors bring the same results with quite a huge drop between train and test data sets. The sample size is around 8k divided into train and test 70/30. OOT sample contains a few thousands of cases. Regularization, ensembles didn't help in solving this.

I doubt whether this is something I should concern if OOT performance is acceptable and close to train sample performance?

jQuery SVG vs. Raphael

If you don't need VML and IE8 support then use Canvas (PaperJS for example). Look at latest IE10 demos for Windows 7. They have amazing animations in Canvas. SVG is not capable to do anything close to them. Overall Canvas is available at all mobile browsers. SVG is not working at early versions of Android 2.0- 2.3 (as I know)

Yes, Canvas is not scalable, but it so fast that you can redraw the whole canvas faster then browser capable to scroll view port.

From my perspective Microsoft's optimizations provides means to use Canvas as regular GDI engine and implement graphics applications like we do them for Windows now.

Ball to Ball Collision - Detection and Handling

Well, years ago I made the program like you presented here.
There is one hidden problem (or many, depends on point of view):

  • If the speed of the ball is too high, you can miss the collision.

And also, almost in 100% cases your new speeds will be wrong. Well, not speeds, but positions. You have to calculate new speeds precisely in the correct place. Otherwise you just shift balls on some small "error" amount, which is available from the previous discrete step.

The solution is obvious: you have to split the timestep so, that first you shift to correct place, then collide, then shift for the rest of the time you have.

NUnit vs. MbUnit vs. MSTest vs.

It's not a big deal, it's pretty easy to switch between them. MSTest being integrated isn't a big deal either, just grab

Like the previous person said pick a mocking framework, my favourite at the moment is Moq.

How to assign the output of a Bash command to a variable?

Here's your script...

echo $DIR
while [ "$DIR" != "/" ]; do
    cd ..
    echo $DIR

Note the spaces, use of quotes, and $ signs.

What is this date format? 2011-08-12T20:17:46.384Z

@John-Skeet gave me the clue to fix my own issue around this. As a younger programmer this small issue is easy to miss and hard to diagnose. So Im sharing it in the hopes it will help someone.

My issue was that I wanted to parse the following string contraining a time stamp from a JSON I have no influence over and put it in more useful variables. But I kept getting errors.

So given the following (pay attention to the string parameter inside ofPattern();

String str = "20190927T182730.000Z"

LocalDateTime fin;
fin = LocalDateTime.parse( str, DateTimeFormatter.ofPattern("yyyyMMdd'T'HHmmss.SSSZ") );


Exception in thread "main" java.time.format.DateTimeParseException: Text 
'20190927T182730.000Z' could not be parsed at index 19

The problem? The Z at the end of the Pattern needs to be wrapped in 'Z' just like the 'T' is. Change "yyyyMMdd'T'HHmmss.SSSZ" to "yyyyMMdd'T'HHmmss.SSS'Z'" and it works.

Removing the Z from the pattern alltogether also led to errors.

Frankly, I'd expect a Java class to have anticipated this.

Find a file with a certain extension in folder

Use this code for read file with all type of extension file.

string[] sDirectoryInfo = Directory.GetFiles(SourcePath, "*.*");

How to check Django version

Simply type python -m django --version or type pip freeze to see all the versions of installed modules including Django.

How do you automatically resize columns in a DataGridView control AND allow the user to resize the columns on that same grid?

foreach (DataGridViewColumn c in dataGridView.Columns)
    c.Width = c.GetPreferredWidth(DataGridViewAutoSizeColumnMode.AllCells, true);

This should work whether the dataGridView has been displayed or not (i.e. even if called from the class constructor).

The same method, but with DataGridViewAutoSizeColumnMode.DisplayedCells, fails in the above case for the obvious reason - no cell has been displayed yet! For some non-obvious reason, AutoResizeColumns also fails in this case.

Default string initialization: NULL or Empty?

According to MSDN:

By initializing strings with the Empty value instead of null, you can reduce the chances of a NullReferenceException occurring.

Always using IsNullOrEmpty() is good practice nevertheless.

How to send email using simple SMTP commands via Gmail?

As no one has mentioned - I would suggest to use great tool for such purpose - swaks

# yum info swaks
Installed Packages
Name        : swaks
Arch        : noarch
Version     : 20130209.0
Release     : 3.el6
Size        : 287 k
Repo        : installed
From repo   : epel
Summary     : Command-line SMTP transaction tester
URL         :
License     : GPLv2+
Description : Swiss Army Knife SMTP: A command line SMTP tester. Swaks can test
            : various aspects of your SMTP server, including TLS and AUTH.

It has a lot of options and can do almost everything you want.

GMAIL: STARTTLS, SSLv3 (and yes, in 2016 gmail still support sslv3)

$ echo "Hello world" | swaks -4 --server --from [email protected] --to [email protected] -tls --tls-protocol sslv3 --auth PLAIN --auth-user [email protected] --auth-password 7654321 --h-Subject "Test message" --body -
=== Trying
=== Connected to
<-  220 ESMTP h8sm76342lbd.48 - gsmtp
 -> EHLO
<- at your service, []
<-  250-SIZE 35882577
<-  250-8BITMIME
<-  250-STARTTLS
<-  250-CHUNKING
<-  250 SMTPUTF8
<-  220 2.0.0 Ready to start TLS
=== TLS started with cipher SSLv3:RC4-SHA:128
=== TLS no local certificate set
=== TLS peer DN="/C=US/ST=California/L=Mountain View/O=Google Inc/"
 ~> EHLO
<~ at your service, []
<~  250-SIZE 35882577
<~  250-8BITMIME
<~  250-CHUNKING
<~  250 SMTPUTF8
<~  235 2.7.0 Accepted
 ~> MAIL FROM:<[email protected]>
<~  250 2.1.0 OK h8sm76342lbd.48 - gsmtp
 ~> RCPT TO:<[email protected]>
<~  250 2.1.5 OK h8sm76342lbd.48 - gsmtp
 ~> DATA
<~  354  Go ahead h8sm76342lbd.48 - gsmtp
 ~> Date: Wed, 17 Feb 2016 09:49:03 +0000
 ~> To: [email protected]
 ~> From: [email protected]
 ~> Subject: Test message
 ~> X-Mailer: swaks v20130209.0
 ~> Hello world
 ~> .
<~  250 2.0.0 OK 1455702544 h8sm76342lbd.48 - gsmtp
 ~> QUIT
<~  221 2.0.0 closing connection h8sm76342lbd.48 - gsmtp
=== Connection closed with remote host.

YAHOO: TLS aka SMTPS, tlsv1.2

$ echo "Hello world" | swaks -4 --server --from [email protected] --to [email protected] --tlsc --tls-protocol tlsv1_2 --auth PLAIN --auth-user [email protected] --auth-password 7654321 --h-Subject "Test message" --body -
=== Trying
=== Connected to
=== TLS started with cipher TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128
=== TLS no local certificate set
=== TLS peer DN="/C=US/ST=California/L=Sunnyvale/O=Yahoo Inc./OU=Information Technology/"
<~  220 ESMTP ready
 ~> EHLO
<~  250-SIZE 41697280
<~  250-8 BITMIME
<~  235 2.0.0 OK
 ~> MAIL FROM:<[email protected]>
<~  250 OK , completed
 ~> RCPT TO:<[email protected]>
<~  250 OK , completed
 ~> DATA
<~  354 Start Mail. End with CRLF.CRLF
 ~> Date: Wed, 17 Feb 2016 10:08:28 +0000
 ~> To: [email protected]
 ~> From: [email protected]
 ~> Subject: Test message
 ~> X-Mailer: swaks v20130209.0
 ~> Hello world
 ~> .
<~  250 OK , completed
 ~> QUIT
<~  221 Service Closing transmission
=== Connection closed with remote host.

I have been using swaks to send email notifications from nagios via gmail for last 5 years without any problem.

jsPDF multi page PDF with HTML renderer

I have the same working issue. Searching in MrRio github I found this:

Basically, you have to check the actual page size always before adding new content

doc = new jsPdf();
pageHeight= doc.internal.pageSize.height;

// Before adding new content
y = 500 // Height position of new content
if (y >= pageHeight)
  y = 0 // Restart height position
doc.text(x, y, "value");

Unit Testing C Code

If you're still on the hunt for test frameworks, CUnitWin32 is one for the Win32/NT platform.

This solves one fundamental problem that I faced with other testing frameworks. Namely global/static variables are in a deterministic state because each test is executed as a separate process.

grep's at sign caught as whitespace

No -P needed; -E is sufficient:

grep -E '(^|\s)abc(\s|$)' 

or even without -E:

grep '\(^\|\s\)abc\(\s\|$\)' 

How to check if a list is empty in Python?

if not myList:
  print "Nothing here"

How to measure time in milliseconds using ANSI C?

I always use the clock_gettime() function, returning time from the CLOCK_MONOTONIC clock. The time returned is the amount of time, in seconds and nanoseconds, since some unspecified point in the past, such as system startup of the epoch.

#include <stdio.h>
#include <stdint.h>
#include <time.h>

int64_t timespecDiff(struct timespec *timeA_p, struct timespec *timeB_p)
  return ((timeA_p->tv_sec * 1000000000) + timeA_p->tv_nsec) -
           ((timeB_p->tv_sec * 1000000000) + timeB_p->tv_nsec);

int main(int argc, char **argv)
  struct timespec start, end;
  clock_gettime(CLOCK_MONOTONIC, &start);

  // Some code I am interested in measuring 

  clock_gettime(CLOCK_MONOTONIC, &end);

  uint64_t timeElapsed = timespecDiff(&end, &start);

Get first element of Series without knowing the index

Use iloc to access by position (rather than label):

In [11]: df = pd.DataFrame([[1, 2], [3, 4]], ['a', 'b'], ['A', 'B'])

In [12]: df
   A  B
a  1  2
b  3  4

In [13]: df.iloc[0]  # first row in a DataFrame
A    1
B    2
Name: a, dtype: int64

In [14]: df['A'].iloc[0]  # first item in a Series (Column)
Out[14]: 1

Fragment pressing back button

Easiest way ever:


public void onResume() {

    getView().setOnKeyListener(new View.OnKeyListener() {
        public boolean onKey(View v, int keyCode, KeyEvent event) {
            if (event.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK) {
                // handle back button's click listener
                Toast.makeText(getActivity(), "Back press", Toast.LENGTH_SHORT).show();
                return true;
            return false;


Edit 1: If fragment having EditText.

private EditText editText;


editText = (EditText) rootView.findViewById(;


public void onResume() {

    editText.setOnKeyListener(new View.OnKeyListener() {
        public boolean onKey(View v, int keyCode, KeyEvent event) {
            if (keyCode == KeyEvent.KEYCODE_BACK) {
            return false;

    getView().setOnKeyListener(new View.OnKeyListener() {
        public boolean onKey(View v, int keyCode, KeyEvent event) {
            if (event.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK) {
                // handle back button's click listener
                Toast.makeText(getActivity(), "Back press", Toast.LENGTH_SHORT).show();
                return true;
            return false;


Note: It will work if you have EditText in fragment.


Binding List<T> to DataGridView in WinForm

This isn't exactly the issue I had, but if anyone is looking to convert a BindingList of any type to List of the same type, then this is how it is done:

var list = bindingList.ToDynamicList();

Also, if you're assigning BindingLists of dynamic types to a DataGridView.DataSource, then make sure you declare it first as IBindingList so the above works.

Alternative to header("Content-type: text/xml");

Now I see what you are doing. You cannot send output to the screen then change the headers. If you are trying to create an XML file of map marker and download them to display, they should be in separate files.

Take this

function parseToXML($htmlStr)
return $xmlStr;
// Opens a connection to a MySQL server
$connection=mysql_connect (localhost, $username, $password);
if (!$connection) {
  die('Not connected : ' . mysql_error());
// Set the active MySQL database
$db_selected = mysql_select_db($database, $connection);
if (!$db_selected) {
  die ('Can\'t use db : ' . mysql_error());
// Select all the rows in the markers table
$query = "SELECT * FROM markers WHERE 1";
$result = mysql_query($query);
if (!$result) {
  die('Invalid query: ' . mysql_error());
header("Content-type: text/xml");
// Start XML file, echo parent node
echo '<markers>';
// Iterate through the rows, printing XML nodes for each
while ($row = @mysql_fetch_assoc($result)){
  echo '<marker ';
  echo 'name="' . parseToXML($row['name']) . '" ';
  echo 'address="' . parseToXML($row['address']) . '" ';
  echo 'lat="' . $row['lat'] . '" ';
  echo 'lng="' . $row['lng'] . '" ';
  echo 'type="' . $row['type'] . '" ';
  echo '/>';
// End XML file
echo '</markers>';

and place it in phpsqlajax_genxml.php so your javascript can download the XML file. You are trying to do too many things in the same file.

How can you undo the last git add?

You cannot undo the latest git add, but you can undo all adds since the last commit. git reset without a commit argument resets the index (unstages staged changes):

git reset

How do I save a stream to a file in C#?

Another option is to get the stream to a byte[] and use File.WriteAllBytes. This should do:

using (var stream = new MemoryStream())
    File.WriteAllBytes(file, stream.ToArray());

Wrapping it in an extension method gives it better naming:

public void WriteTo(this Stream input, string file)
    //your fav write method:

    using (var stream = File.Create(file))


    using (var stream = new MemoryStream())
        File.WriteAllBytes(file, stream.ToArray());

    //whatever that fits.

Bootstrap: add margin/padding space between columns

Just add 'justify-content-around' class. that would automatically add gap between 2 divs.



<div class="row justify-content-around">
    <div class="col-4">
      One of two columns
    <div class="col-4">
      One of two columns

How can I convert string date to NSDate?

Below are some string to date format converting options can be usedin swift iOS.

  1. Thursday, Dec 27, 2018 format= EEEE, MMM d, yyyy
  2. 12/27/2018 format= MM/dd/yyyy
  3. 12-27-2018 09:59 format= MM-dd-yyyy HH:mm
  4. Dec 27, 9:59 AM format= MMM d, h:mm a
  5. December 2018 format= MMMM yyyy
  6. Dec 27, 2018 format= MMM d, yyyy
  7. Thu, 27 Dec 2018 09:59:19 +0000 format= E, d MMM yyyy HH:mm:ss Z
  8. 2018-12-27T09:59:19+0000 format= yyyy-MM-dd'T'HH:mm:ssZ
  9. 27.12.18 format= dd.MM.yy
  10. 09:59:19.815 format= HH:mm:ss.SSS

Detecting EOF in C

Another issue is that you're reading with scanf("%f", &input); only. If the user types something that can't be interpreted as a C floating-point number, like "pi", the scanf() call will not assign anything to input, and won't progress from there. This means it would attempt to keep reading "pi", and failing.

Given the change to while(!feof(stdin)) which other posters are correctly recommending, if you typed "pi" in there would be an endless loop of printing out the former value of input and printing the prompt, but the program would never process any new input.

scanf() returns the number of assignments to input variables it made. If it made no assignment, that means it didn't find a floating-point number, and you should read through more input with something like char string[100];scanf("%99s", string);. This will remove the next string from the input stream (up to 99 characters, anyway - the extra char is for the null terminator on the string).

You know, this is reminding me of all the reasons I hate scanf(), and why I use fgets() instead and then maybe parse it using sscanf().

jQuery's is triggering a 404 (Not Found)

  1. Download the map file and the uncompressed version of jQuery.
    Put them with the minified version:


  2. Include minified version into your HTML:


  3. Check in Google Chrome:

    Google Chrome

  4. Read Introduction to JavaScript Source Maps

  5. Get familiar with Debugging JavaScript

Java, How to get number of messages in a topic in apache kafka


A super SQL engine, provided by Facebook, that connects on several data sources (Cassandra, Kafka, JMX, Redis ...).

PrestoDB is running as a server with optional workers (there is a standalone mode without extra workers), then you use a small executable JAR (called presto CLI) to make queries.

Once you have configured well the Presto server , you can use traditionnal SQL:


How to convert JSON to CSV format and store in a variable

Heres a way to do it for dynamically deep objects in a object oriented way for the newer js versions. you might have to change the seperatortype after region.

private ConvertToCSV(objArray) {
    let rows = typeof objArray !== "object" ? JSON.parse(objArray) : objArray;
    let  header = "";
    Object.keys(rows[0]).map(pr => (header += pr + ";"));

    let str = "";
    rows.forEach(row => {
        let line = "";
        let columns =
            typeof row !== "object" ? JSON.parse(row) : Object.values(row);
        columns.forEach(column => {
            if (line !== "") {
                line += ";";
            if (typeof column === "object") {
                line += JSON.stringify(column);
            }  else {
                line += column;
        str += line + "\r\n";
    return header + "\r\n" + str;

int value under 10 convert to string two digit number

You can also do it this way

private static string GetPaddingSequence(int padding)
      StringBuilder SB = new StringBuilder();
      for (int i = 0; i < padding; i++)

      return SB.ToString();

public static string FormatNumber(int number, int padding)
    return number.ToString(GetPaddingSequence(padding));

Finally call the function FormatNumber

string x = FormatNumber(1,2);

Output will be 01 which is based on your padding parameter. Increasing it will increase the number of 0s

How can I search (case-insensitive) in a column using LIKE wildcard?

This is the example of a simple LIKE query:

SELECT * FROM <table> WHERE <key> LIKE '%<searchpattern>%'

Now, case-insensitive using LOWER() func:

SELECT * FROM <table> WHERE LOWER(<key>) LIKE LOWER('%<searchpattern>%')

How to check if a user likes my Facebook Page or URL using Facebook's API

You can use (PHP)

$isFan = file_get_contents("" . USER_TOKEN . "&page_id=" . FB_FANPAGE_ID);

That will return one of three:

  • string true string false json
  • formatted response of error if token
  • or page_id are not valid

I guess the only not-using-token way to achieve this is with the signed_request Jason Siffring just posted. My helper using PHP SDK:

function isFan(){
    global $facebook;
    $request = $facebook->getSignedRequest();
    return $request['page']['liked'];

'sprintf': double precision in C

The problem is with sprintf


%lf says to interpet "a" as a "long double" (16 bytes) but it is actually a "double" (8 bytes). Use this instead:

sprintf(aa, "%f", a);

More details here on

Postgres FOR LOOP

I just ran into this question and, while it is old, I figured I'd add an answer for the archives. The OP asked about for loops, but their goal was to gather a random sample of rows from the table. For that task, Postgres 9.5+ offers the TABLESAMPLE clause on WHERE. Here's a good rundown:

I tend to use Bernoulli as it's row-based rather than page-based, but the original question is about a specific row count. For that, there's a built-in extension:

CREATE EXTENSION tsm_system_rows;

Then you can grab whatever number of rows you want:

select * from playtime tablesample system_rows (15);

How to remove specific value from array using jQuery

Remove Item in Array

var arr = ["jQuery", "JavaScript", "HTML", "Ajax", "Css"];
var itemtoRemove = "HTML";
arr.splice($.inArray(itemtoRemove, arr), 1);

New lines inside paragraph in

Interpreting newlines as <br /> used to be a feature of Github-flavored markdown, but the most recent help document no longer lists this feature.

Fortunately, you can do it manually. The easiest way is to ensure that each line ends with two spaces. So, change




(where _ is a blank space).

Or, you can add explicit <br /> tags.

a <br />
b <br />

500 Internal Server Error for php file not for html

500 Internal Server Error is shown if your php code has fatal errors but error displaying is switched off. You may try this to see the error itself instead of 500 error page:

In your php file:

ini_set('display_errors', 1);

In .htaccess file:

php_flag display_errors 1

How do I rename a column in a SQLite database table?

While it is true that there is no ALTER COLUMN, if you only want to rename the column, drop the NOT NULL constraint, or change the data type, you can use the following set of commands:

Note: These commands have the potential to corrupt your database, so make sure you have a backup

PRAGMA writable_schema = 1;
PRAGMA writable_schema = 0;

You will need to either close and reopen your connection or vacuum the database to reload the changes into the schema.

For example:

Y:\> sqlite3 booktest  
SQLite version 3.7.4  
Enter ".help" for instructions  
Enter SQL statements terminated with a ";"  
sqlite> create table BOOKS ( title TEXT NOT NULL, publication_date TEXT NOT NULL);  
sqlite> insert into BOOKS VALUES ("NULLTEST",null);  
Error: BOOKS.publication_date may not be NULL  
sqlite> PRAGMA writable_schema = 1; 
sqlite> PRAGMA writable_schema = 0;  
sqlite> .q  

Y:\> sqlite3 booktest  
SQLite version 3.7.4  
Enter ".help" for instructions  
Enter SQL statements terminated with a ";"  
sqlite> insert into BOOKS VALUES ("NULLTEST",null);  
sqlite> .q  


pragma writable_schema
When this pragma is on, the SQLITE_MASTER tables in which database can be changed using ordinary UPDATE, INSERT, and DELETE statements. Warning: misuse of this pragma can easily result in a corrupt database file.

alter table
SQLite supports a limited subset of ALTER TABLE. The ALTER TABLE command in SQLite allows the user to rename a table or to add a new column to an existing table. It is not possible to rename a column, remove a column, or add or remove constraints from a table.


How to set default value to all keys of a dict object in python?

Not after creating it, no. But you could use a defaultdict in the first place, which sets default values when you initialize it.

Could not load type 'XXX.Global'

Changing the address's port number (localhost:) worked for me :)

How to refresh materialized view in oracle

You can refresh a materialized view completely as follows:


Apply CSS Style to child elements

.test * {padding: 40px 100px 40px 50px;}

How to Refresh a Component in Angular

html file

<a (click)= "getcoursedetails(obj.Id)" routerLinkActive="active" class="btn btn-danger">Read more...</a>

ts file

  this._route.navigateByUrl('/RefreshComponent', { skipLocationChange: true }).then(() => {

Getting the parent div of element

Knowing the parent of an element is useful when you are trying to position them out the "real-flow" of elements.

Below given code will output the id of parent of element whose id is provided. Can be used for misalignment diagnosis.

<!-- Patch of code to find parent -->
<p id="demo">Click the button </p>
<button onclick="parentFinder()">Find Parent</button>
function parentFinder()
    var x=document.getElementById("demo"); 
    var y=document.getElementById("*id of Element you want to know parent of*");;
<!-- Patch ends -->

How to rearrange Pandas column sequence?

There may be an elegant built-in function (but I haven't found it yet). You could write one:

# reorder columns
def set_column_sequence(dataframe, seq, front=True):
    '''Takes a dataframe and a subsequence of its columns,
       returns dataframe with seq as first columns if "front" is True,
       and seq as last columns if "front" is False.
    cols = seq[:] # copy so we don't mutate seq
    for x in dataframe.columns:
        if x not in cols:
            if front: #we want "seq" to be in the front
                #so append current column to the end of the list
                #we want "seq" to be last, so insert this
                #column in the front of the new column list
                #"cols" we are building:
                cols.insert(0, x)
return dataframe[cols]

For your example: set_column_sequence(df, ['x','y']) would return the desired output.

If you want the seq at the end of the DataFrame instead simply pass in "front=False".

How to return a specific status code and no contents from Controller?

The best way to do it is:

return this.StatusCode(StatusCodes.Status418ImATeapot, "Error message");

'StatusCodes' has every kind of return status and you can see all of them in this link

Once you choose your StatusCode, return it with a message.

Getting time span between two times in C#?

Two points:

  1. Check your inputs. I can't imagine a situation where you'd get 2 hours by subtracting the time values you're talking about. If I do this:

        DateTime startTime = Convert.ToDateTime("7:00 AM");
        DateTime endtime = Convert.ToDateTime("2:00 PM");
        TimeSpan duration = startTime - endtime;

    ... I get -07:00:00 as the result. And even if I forget to provide the AM/PM value:

        DateTime startTime = Convert.ToDateTime("7:00");
        DateTime endtime = Convert.ToDateTime("2:00");
        TimeSpan duration = startTime - endtime;

    ... I get 05:00:00. So either your inputs don't contain the values you have listed or you are in a machine environment where they are begin parsed in an unexpected way. Or you're not actually getting the results you are reporting.

  2. To find the difference between a start and end time, you need to do endTime - startTime, not the other way around.

JavaScript Regular Expression Email Validation

You may be interested in having a look at this page it list regular expressions for validating email address that cover more general cases.

How to print time in format: 2009-08-10 18:17:54.811

None of the solutions on this page worked for me, I mixed them up and made them working with Windows and Visual Studio 2019, Here's How :

#include <Windows.h>
#include <time.h> 
#include <chrono>

static int gettimeofday(struct timeval* tp, struct timezone* tzp) {
    namespace sc = std::chrono;
    sc::system_clock::duration d = sc::system_clock::now().time_since_epoch();
    sc::seconds s = sc::duration_cast<sc::seconds>(d);
    tp->tv_sec = s.count();
    tp->tv_usec = sc::duration_cast<sc::microseconds>(d - s).count();
    return 0;

static char* getFormattedTime() {
    static char buffer[26];

    // For Miliseconds
    int millisec;
    struct tm* tm_info;
    struct timeval tv;

    // For Time
    time_t rawtime;
    struct tm* timeinfo;

    gettimeofday(&tv, NULL);

    millisec = lrint(tv.tv_usec / 1000.0);
    if (millisec >= 1000) 
        millisec -= 1000;

    timeinfo = localtime(&rawtime);

    strftime(buffer, 26, "%Y:%m:%d %H:%M:%S", timeinfo);
    sprintf_s(buffer, 26, "%s.%03d", buffer, millisec);

    return buffer;

Result :

2020:08:02 06:41:59.107

2020:08:02 06:41:59.196

rails simple_form - hidden field - create?

Shortest Yet !!!

=f.hidden_field :title, :value => "some value"

Shorter, DRYer and perhaps more obvious.

Of course with ruby 1.9 and the new hash format we can go 3 characters shorter with...

=f.hidden_field :title, value: "some value"

How to add a classname/id to React-Bootstrap Component?

1st way is to use props

<Row id = "someRandomID">

Wherein, in the Definition, you may just go

const Row = props  => {
 div id = {}

The same could be done with class, replacing id with className in the above example.

You might as well use react-html-id, that is an npm package. This is an npm package that allows you to use unique html IDs for components without any dependencies on other libraries.

Ref: react-html-id


Determine SQL Server Database Size


no looping needed, unlike sp_spaceused.

How to downgrade the installed version of 'pip' on windows?

well the only thing that will work is

python -m pip install pip==

you can and should run it under IDE terminal (mine was pycharm)

C - error: storage size of ‘a’ isn’t known

You define your struct as xyx, however in your main, you use struct xyz a; , which only creates a forward declaration of a differently named struct.

Try using xyx a; instead of that line.

How to sort Map values by key in Java?

Just in case you don't wanna use a TreeMap

public static Map<Integer, Integer> sortByKey(Map<Integer, Integer> map) {
        List<Map.Entry<Integer, Integer>> list = new ArrayList<>(map.entrySet());
        Map<Integer, Integer> sortedMap = new LinkedHashMap<>();
        list.forEach(e -> sortedMap.put(e.getKey(), e.getValue()));
        return sortedMap;

Also, in-case you wanted to sort your map on the basis of values just change Map.Entry::getKey to Map.Entry::getValue

How do I get the function name inside a function in PHP?


  class Test {
     function MethodA(){
         echo __FUNCTION__ ;
 $test = new Test;
 echo $test->MethodA();

Result: "MethodA";

react-native: command not found

/usr/bin/ruby -e "$(curl -fsSL"
brew install yarn
brew install node
brew install watchman
brew tap AdoptOpenJDK/openjdk
brew cask install adoptopenjdk8
npm install -g react-native-cli

Why do people use Heroku when AWS is present? What distinguishes Heroku from AWS?

There are a lot of different ways to look at this decision from development, IT, and business objectives, so don't feel bad if it seems overwhelming. But also - don't overthink scalability.

Think about your requirements.

I've engineered websites which have serviced over 8M uniques a day and delivered terabytes of video a week built on infrastructures starting at $250k in capital hardware unr by a huge $MM IT labor staff.

But I've also had smaller websites which were designed to generate $10-$20k per year, didn't have very high traffic, db or processing requirements, and I ran those off a $10/mo generic hosting account without compromise.

In the future, deployment will look more like Heroku than AWS, just because of progress. There is zero value in the IT knob-turning of scaling internet infrastructures which isn't increasingly automatable, and none of it has anything to do with the value of the product or service you are offering.

Also, keep in mind with a commercial website - scalability is what we often call a 'good problem to have' - although scalability issues with sites like Facebook and Twitter were very high-profile, they had zero negative effect on their success - the news might have even contributed to more signups (all press is good press).

If you have a service which is generating a 100k+ uniques a day and having scaling issues, I'd be glad to take it off your hands for you no matter what the language, db, platform, or infrastructure you are running on!

Scalability is a fixable implementation problem - not having customers is an existential issue.

How do I insert a drop-down menu for a simple Windows Forms app in Visual Studio 2008?

You can use a ComboBox with its ComboBoxStyle (appears as DropDownStyle in later versions) set to DropDownList. See:

Adding Jar files to IntellijIdea classpath

Go to File-> Project Structure-> Libraries and click green "+" to add the directory folder that has the JARs to CLASSPATH. Everything in that folder will be added to CLASSPATH.


It's 2018. It's a better idea to use a dependency manager like Maven and externalize your dependencies. Don't add JAR files to your project in a /lib folder anymore.


RegEx for Javascript to allow only alphanumeric


^         Start of string
[a-z0-9]  a or b or c or ... z or 0 or 1 or ... 9
+         one or more times (change to * to allow empty string)
$         end of string    
/i        case-insensitive

Update (supporting universal characters)

if you need to this regexp supports universal character you can find list of unicode characters here.

for example: /^([a-zA-Z0-9\u0600-\u06FF\u0660-\u0669\u06F0-\u06F9 _.-]+)$/

this will support persian.

Using R to download zipped data file, extract, and import data

I found that the following worked for me. These steps come from BTD's YouTube video, Managing Zipfile's in R:

zip.url <- ""

dir <- getwd()

zip.file <- ""

zip.combine <- as.character(paste(dir, zip.file, sep = "/"))

download.file(zip.url, destfile = zip.combine)


Checking for the correct number of arguments

if [ "$#" -ne 1 ] || ! [ -d "$1" ]; then
  echo "Usage: $0 DIRECTORY" >&2
  exit 1

Translation: If number of arguments is not (numerically) equal to 1 or the first argument is not a directory, output usage to stderr and exit with a failure status code.

More friendly error reporting:

if [ "$#" -ne 1 ]; then
  echo "Usage: $0 DIRECTORY" >&2
  exit 1
if ! [ -e "$1" ]; then
  echo "$1 not found" >&2
  exit 1
if ! [ -d "$1" ]; then
  echo "$1 not a directory" >&2
  exit 1

getting file size in javascript

To get the file size of pages on the web I built a javascript bookmarklet to do the trick. It alerts the size in kb's. Change the alert to a prompt if you want to copy the filesize.

Here's the bookmarklet code for the alert.

<a href="javascript:a=document.getElementsByTagName('HTML')[0].outerHTML;b=a.length/1024;c=Math.round(b);alert(c+' kb');">Doc Size</a>

Here's the bookmarklet code for the prompt.

<a href="javascript:a=document.getElementsByTagName('HTML')[0].outerHTML;b=a.length/1024;c=Math.round(b);prompt('Page Size',c+' kb');">Doc Size</a>

See it in action at

Changing the cursor in WPF sometimes works, sometimes doesn't

The following worked for me:

ForceCursor = true;
Cursor = Cursors.Wait;

Nodejs - Redirect url

Use the following code this works fine in Native Nodejs

http.createServer(function (req, res) {
var q = url.parse(req.url, true);
if (q.pathname === '/') {
  //Home page code
} else if (q.pathname === '/redirect-to-google') {
  res.writeHead(301, { "Location": "" });
  return res.end();
} else if (q.pathname === '/redirect-to-interal-page') {
  res.writeHead(301, { "Location": "/path/within/site" });
  return res.end();
} else {
    //404 page code

Use ffmpeg to add text subtitles

This is the reason why mkv is such a good container, especially now that it's mature:

mkvmerge -o output.mkv video.mp4

Does MySQL ignore null values on unique constraints?

Avoid nullable unique constraints. You can always put the column in a new table, make it non-null and unique and then populate that table only when you have a value for it. This ensures that any key dependency on the column can be correctly enforced and avoids any problems that could be caused by nulls.

IN Clause with NULL or IS NULL

The question as answered by Daniel is perfctly fine. I wanted to leave a note regarding NULLS. We should be carefull about using NOT IN operator when a column contains NULL values. You won't get any output if your column contains NULL values and you are using the NOT IN operator. This is how it's explained over here , a very good article which I came across and thought of sharing it.

How do I change the default index page in Apache?

You can also set DirectoryIndex in apache's httpd.conf file.

CentOS keeps this file in /etc/httpd/conf/httpd.conf Debian: /etc/apache2/apache2.conf

Open the file in your text editor and find the line starting with DirectoryIndex

To load landing.html as a default (but index.html if that's not found) change this line to read:

DirectoryIndex  landing.html index.html

CSS Always On Top

Ensure position is on your element and set the z-index to a value higher than the elements you want to cover.

element {
    position: fixed;
    z-index: 999;

div {
    position: relative;
    z-index: 99;

It will probably require some more work than that but it's a start since you didn't post any code.

How can I get the list of files in a directory using C or C++?

Why not use glob()?

#include <glob.h>

glob_t glob_result;
for(unsigned int i=0; i<glob_result.gl_pathc; ++i){
  cout << glob_result.gl_pathv[i] << endl;

Postgres DB Size Command

From the PostgreSQL wiki.

NOTE: Databases to which the user cannot connect are sorted as if they were infinite size.

SELECT d.datname AS Name,  pg_catalog.pg_get_userbyid(d.datdba) AS Owner,
    CASE WHEN pg_catalog.has_database_privilege(d.datname, 'CONNECT')
        THEN pg_catalog.pg_size_pretty(pg_catalog.pg_database_size(d.datname))
        ELSE 'No Access'
    END AS Size
FROM pg_catalog.pg_database d
    CASE WHEN pg_catalog.has_database_privilege(d.datname, 'CONNECT')
        THEN pg_catalog.pg_database_size(d.datname)
        ELSE NULL
    END DESC -- nulls first
    LIMIT 20

The page also has snippets for finding the size of your biggest relations and largest tables.

Split text file into smaller multiple text file using command line

My requirement was a bit different. I often work with Comma Delimited and Tab Delimited ASCII files where a single line is a single record of data. And they're really big, so I need to split them into manageable parts (whilst preserving the header row).

So, I reverted back to my classic VBScript method and bashed together a small .vbs script that can be run on any Windows computer (it gets automatically executed by the WScript.exe script host engine on Window).

The benefit of this method is that it uses Text Streams, so the underlying data isn't loaded into memory (or, at least, not all at once). The result is that it's exceptionally fast and it doesn't really need much memory to run. The test file I just split using this script on my i7 was about 1 GB in file size, had about 12 million lines of test and made 25 part files (each with about 500k lines each) – the processing took about 2 minutes and it didn’t go over 3 MB memory used at any point.

The caveat here is that it relies on the text file having "lines" (meaning each record is delimited with a CRLF) as the Text Stream object uses the "ReadLine" function to process a single line at a time. But hey, if you're working with TSV or CSV files, it's perfect.

Option Explicit

Private Const INPUT_TEXT_FILE = "c:\bigtextfile.txt"  'The full path to the big file
Private Const REPEAT_HEADER_ROW = True                'Set to True to duplicate the header row in each part file
Private Const LINES_PER_PART = 500000                 'The number of lines per part file

Dim oFileSystem, oInputFile, oOutputFile, iOutputFile, iLineCounter, sHeaderLine, sLine, sFileExt, sStart

sStart = Now()

iLineCounter = 0
iOutputFile = 1

Set oFileSystem = CreateObject("Scripting.FileSystemObject")
Set oInputFile = oFileSystem.OpenTextFile(INPUT_TEXT_FILE, 1, False)
Set oOutputFile = oFileSystem.OpenTextFile(Replace(INPUT_TEXT_FILE, sFileExt, "_" & iOutputFile & sFileExt), 2, True)

    iLineCounter = 1
    sHeaderLine = oInputFile.ReadLine()
    Call oOutputFile.WriteLine(sHeaderLine)
End If

Do While Not oInputFile.AtEndOfStream
    sLine = oInputFile.ReadLine()
    Call oOutputFile.WriteLine(sLine)
    iLineCounter = iLineCounter + 1
    If iLineCounter Mod LINES_PER_PART = 0 Then
        iOutputFile = iOutputFile + 1
        Call oOutputFile.Close()
        Set oOutputFile = oFileSystem.OpenTextFile(Replace(INPUT_TEXT_FILE, sFileExt, "_" & iOutputFile & sFileExt), 2, True)
            Call oOutputFile.WriteLine(sHeaderLine)
        End If
    End If

Call oInputFile.Close()
Call oOutputFile.Close()
Set oFileSystem = Nothing

Call MsgBox("Done" & vbCrLf & "Lines Processed:" & iLineCounter & vbCrLf & "Part Files: " & iOutputFile & vbCrLf & "Start Time: " & sStart & vbCrLf & "Finish Time: " & Now())

Unable to capture screenshot. Prevented by security policy. Galaxy S6. Android 6.0

You must have either disabled, froze or uninstalled FaceProvider in settings>applications>all
This will only happen if it's frozen, either uninstall it, or enable it.

What is a 'NoneType' object?

In the error message, instead of telling you that you can't concatenate two objects by showing their values (a string and None in this example), the Python interpreter tells you this by showing the types of the objects that you tried to concatenate. The type of every string is str while the type of the single None instance is called NoneType.

You normally do not need to concern yourself with NoneType, but in this example it is necessary to know that type(None) == NoneType.

cannot convert 'std::basic_string<char>' to 'const char*' for argument '1' to 'int system(const char*)'

std::string + const char* results in another std::string. system does not take a std::string, and you cannot concatenate char*'s with the + operator. If you want to use the code this way you will need:

std::string name = "john";
std::string tmp = 
    "quickscan.exe resolution 300 selectscanner jpg showui showprogress filename '" + 
    name + ".jpg'";

See std::string operator+(const char*)

How do you get an iPhone's device name

To get an iPhone's device name programmatically

 UIDevice *deviceInfo = [UIDevice currentDevice];

 NSLog(@"Device name:  %@",; 

// Device name: my iPod

How to change the color of an svg element?

To simply change the color of the svg :

Go to the svg file and under styles, mention the color in fill.


SUM of grouped COUNT in SQL Query

Use it as

select Name, count(Name) as Count from YourTable
group by Name
Select 'SUM' , COUNT(Name) from YourTable

Why doesn't document.addEventListener('load', function) work in a greasemonkey script?

According to HTML living standard specification, the load event is

Fired at the Window when the document has finished loading; fired at an element containing a resource (e.g. img, embed) when its resource has finished loading

I.e. load event is not fired on document object.

Credit: Why does document.addEventListener(‘load’, handler) not work?

How to make html <select> element look like "disabled", but pass values?

Wow, I had the same problem, but a line of code resolved my problem. I wrote

$last_child_topic.find( "*" ).prop( "disabled", true );
$last_child_topic.find( "option" ).prop( "disabled", false );   //This seems to work on mine

I send the form to a php script then it prints the correct value for each options while it was "null" before.

Tell me if this works out. I wonder if this only works on mine somehow.

How to include view/partial specific styling in AngularJS

I know this question is old now, but after doing a ton of research on various solutions to this problem, I think I may have come up with a better solution.

UPDATE 1: Since posting this answer, I have added all of this code to a simple service that I have posted to GitHub. The repo is located here. Feel free to check it out for more info.

UPDATE 2: This answer is great if all you need is a lightweight solution for pulling in stylesheets for your routes. If you want a more complete solution for managing on-demand stylesheets throughout your application, you may want to checkout Door3's AngularCSS project. It provides much more fine-grained functionality.

In case anyone in the future is interested, here's what I came up with:

1. Create a custom directive for the <head> element:

app.directive('head', ['$rootScope','$compile',
    function($rootScope, $compile){
        return {
            restrict: 'E',
            link: function(scope, elem){
                var html = '<link rel="stylesheet" ng-repeat="(routeCtrl, cssUrl) in routeStyles" ng-href="{{cssUrl}}" />';
                scope.routeStyles = {};
                $rootScope.$on('$routeChangeStart', function (e, next, current) {
                    if(current && current.$$route && current.$$route.css){
                            current.$$route.css = [current.$$route.css];
                        angular.forEach(current.$$route.css, function(sheet){
                            delete scope.routeStyles[sheet];
                    if(next && next.$$route && next.$$route.css){
                            next.$$route.css = [next.$$route.css];
                        angular.forEach(next.$$route.css, function(sheet){
                            scope.routeStyles[sheet] = sheet;

This directive does the following things:

  1. It compiles (using $compile) an html string that creates a set of <link /> tags for every item in the scope.routeStyles object using ng-repeat and ng-href.
  2. It appends that compiled set of <link /> elements to the <head> tag.
  3. It then uses the $rootScope to listen for '$routeChangeStart' events. For every '$routeChangeStart' event, it grabs the "current" $$route object (the route that the user is about to leave) and removes its partial-specific css file(s) from the <head> tag. It also grabs the "next" $$route object (the route that the user is about to go to) and adds any of its partial-specific css file(s) to the <head> tag.
  4. And the ng-repeat part of the compiled <link /> tag handles all of the adding and removing of the page-specific stylesheets based on what gets added to or removed from the scope.routeStyles object.

Note: this requires that your ng-app attribute is on the <html> element, not on <body> or anything inside of <html>.

2. Specify which stylesheets belong to which routes using the $routeProvider:

app.config(['$routeProvider', function($routeProvider){
        .when('/some/route/1', {
            templateUrl: 'partials/partial1.html', 
            controller: 'Partial1Ctrl',
            css: 'css/partial1.css'
        .when('/some/route/2', {
            templateUrl: 'partials/partial2.html',
            controller: 'Partial2Ctrl'
        .when('/some/route/3', {
            templateUrl: 'partials/partial3.html',
            controller: 'Partial3Ctrl',
            css: ['css/partial3_1.css','css/partial3_2.css']

This config adds a custom css property to the object that is used to setup each page's route. That object gets passed to each '$routeChangeStart' event as .$$route. So when listening to the '$routeChangeStart' event, we can grab the css property that we specified and append/remove those <link /> tags as needed. Note that specifying a css property on the route is completely optional, as it was omitted from the '/some/route/2' example. If the route doesn't have a css property, the <head> directive will simply do nothing for that route. Note also that you can even have multiple page-specific stylesheets per route, as in the '/some/route/3' example above, where the css property is an array of relative paths to the stylesheets needed for that route.

3. You're done Those two things setup everything that was needed and it does it, in my opinion, with the cleanest code possible.

Hope that helps someone else who might be struggling with this issue as much as I was.

How to "z-index" to make a menu always on top of the content

you could put the style in container div menu with:

<div style="position:relative; z-index:10">
   <!--html menu-->

before enter image description here


enter image description here

Assigning out/ref parameters in Moq

Seems like it is not possible out of the box. Looks like someone attempted a solution

See this forum post

this question Verify value of reference parameter with Moq

What is a monad?

In practice, monad is a custom implementation of function composition operator that takes care of side effects and incompatible input and return values (for chaining).

What are invalid characters in XML

In the Woodstox XML processor, invalid characters are classified by this code:

if (c == 0) {
    throw new IOException("Invalid null character in text to output");
if (c < ' ' || (c >= 0x7F && c <= 0x9F)) {
    String msg = "Invalid white space character (0x" + Integer.toHexString(c) + ") in text to output";
    if (mXml11) {
        msg += " (can only be output using character entity)";
    throw new IOException(msg);
if (c > 0x10FFFF) {
    throw new IOException("Illegal unicode character point (0x" + Integer.toHexString(c) + ") to output; max is 0x10FFFF as per RFC");
 * Surrogate pair in non-quotable (not text or attribute value) content, and non-unicode encoding (ISO-8859-x,
 * Ascii)?
if (c >= SURR1_FIRST && c <= SURR2_LAST) {
    throw new IOException("Illegal surrogate pair -- can only be output via character entities, which are not allowed in this content");
throw new IOException("Invalid XML character (0x"+Integer.toHexString(c)+") in text to output");

Source from here

Difference between JE/JNE and JZ/JNZ

  je : Jump if equal:

  399  3fb:   64 48 33 0c 25 28 00    xor    %fs:0x28,%rcx
  400  402:   00 00
  401  404:   74 05                   je     40b <sims_get_counter+0x51>

Overwriting my local branch with remote branch

git reset --hard

This is to revert all your local changes to the origin head

Generating random numbers in Objective-C

Use the arc4random_uniform(upper_bound) function to generate a random number within a range. The following will generate a number between 0 and 73 inclusive.


arc4random_uniform(upper_bound) avoids modulo bias as described in the man page:

arc4random_uniform() will return a uniformly distributed random number less than upper_bound. arc4random_uniform() is recommended over constructions like ``arc4random() % upper_bound'' as it avoids "modulo bias" when the upper bound is not a power of two.

How to insert a row in an HTML table body in JavaScript

You can try the following snippet using jQuery:


How to make a JTable non-editable

table.setDefaultEditor(Object.class, null);

How do I reload a page without a POSTDATA warning in Javascript?

To bypass POST warning you must reload page with full URL. Works fine.

window.location.href = window.location.protocol +'//'+ + window.location.pathname;

.htaccess not working apache

For Ubuntu,
First, run this command :-

sudo a2enmod rewrite

Then, edit the file /etc/apache2/sites-available/000-default.conf using nano or vim using this command :-

sudo nano /etc/apache2/sites-available/000-default.conf

Then in the 000-default.conf file, add this after the line DocumentRoot /var/www/html. If your root html directory is something other, then write that :-

<Directory "/var/www/html">
  AllowOverride All

After doing everything, restart apache using the command sudo service apache2 restart

How to check if an array value exists?

Using: in_array()

$search_array = array('user_from','lucky_draw_id','prize_id');

if (in_array('prize_id', $search_array)) {
    echo "The 'prize_id' element is in the array";

Here is output: The 'prize_id' element is in the array

Using: array_key_exists()

$search_array = array('user_from','lucky_draw_id','prize_id');

if (array_key_exists('prize_id', $search_array)) {
    echo "The 'prize_id' element is in the array";

No output

In conclusion, array_key_exists() does not work with a simple array. Its only to find whether an array key exist or not. Use in_array() instead.

Here is more example:

 * 1. example with assoc array using in_array
 * IMPORTANT NOTE: in_array is case-sensitive
 * in_array — Checks if a value exists in an array
$something = array('a' => 'bla', 'b' => 'omg');
if (in_array('omg', $something)) {
    echo "|1| The 'omg' value found in the assoc array ||";

 * 2. example with index array using in_array
 * IMPORTANT NOTE: in_array is case-sensitive
 * in_array — Checks if a value exists in an array
$something = array('bla', 'omg');
if (in_array('omg', $something)) {
    echo "|2| The 'omg' value found in the index array ||";

 * 3. trying with array_search
 * array_search — Searches the array for a given value 
 * and returns the corresponding key if successful
$something = array('a' => 'bla', 'b' => 'omg');
if (array_search('bla', $something)) {
    echo "|3| The 'bla' value found in the assoc array ||";

 * 4. trying with isset (fastest ever)
 * isset — Determine if a variable is set and 
 * is not NULL
$something = array('a' => 'bla', 'b' => 'omg');
    echo "|4| Yeah!! 'bla' found in array ||";

 * |1| The 'omg' element value found in the assoc array ||
 * |2| The 'omg' element value found in the index array ||
 * |3| The 'bla' element value found in the assoc array ||
 * |4| Yeah!! 'bla' found in array ||

Here is PHP DEMO

MVC Razor Radio Button

                                        <td align="right" style="height:26px;">Is Calender Required?:</td>
                                        <td align="left">
                                            @Html.RadioButton("rdbCalenderRequested", "True", new { id = "rdbCalenderRequested_1" })@:Yes &nbsp;&nbsp;&nbsp; 

                                            @Html.RadioButton("rdbCalenderRequested", "False", new { id = "rdbCalenderRequested_2" }) @:No

                                        <td align="right" style="height:26px;">Is Special Pooja?:</td>
                                        <td align="left">
                                            @Html.RadioButton("rdbPoojaRequested", "True", new { id = "rdbPoojaRequested_1" })@:Yes&nbsp;&nbsp;&nbsp; 

                                            @Html.RadioButton("rdbPoojaRequested", "False", new { id = "rdbPoojaRequested_2" }) @:No

Better way to sum a property value in an array

How to sum array of object using Javascript

const traveler = [
  {  description: 'Senior', Amount: 50},
  {  description: 'Senior', Amount: 50},
  {  description: 'Adult', Amount: 75},
  {  description: 'Child', Amount: 35},
  {  description: 'Infant', Amount: 25 }

const traveler = [_x000D_
    {  description: 'Senior', Amount: 50},_x000D_
    {  description: 'Senior', Amount: 50},_x000D_
    {  description: 'Adult', Amount: 75},_x000D_
    {  description: 'Child', Amount: 35},_x000D_
    {  description: 'Infant', Amount: 25 },_x000D_
function sum(arrayData, key){_x000D_
   return arrayData.reduce((a,b) => {_x000D_
  return {Amount : a.Amount + b.Amount}_x000D_
_x000D_ `

PHP date add 5 year to current date

Try with:

$end = date('Y-m-d', strtotime('+5 years'));

How to add a line break within echo in PHP?

You may want to try \r\n for carriage return / line feed

How to manually send HTTP POST requests from Firefox or Chrome browser?

Forget browser and try CLI. HTTPie is great tool!

HTTPie screenshot

CLI http clients:

If you insist on browser extension then:



Redirect output of mongo query to a csv file

Have a look at this

for outputing from mongo shell to file. There is no support for outputing csv from mongos shell. You would have to write the javascript yourself or use one of the many converters available. Google "convert json to csv" for example.

Why does "pip install" inside Python raise a SyntaxError?

pip is run from the command line, not the Python interpreter. It is a program that installs modules, so you can use them from Python. Once you have installed the module, then you can open the Python shell and do import selenium.

The Python shell is not a command line, it is an interactive interpreter. You type Python code into it, not commands.

date() method, "A non well formed numeric value encountered" does not want to format a date passed in $_POST

From the documentation for strtotime():

Dates in the m/d/y or d-m-y formats are disambiguated by looking at the separator between the various components: if the separator is a slash (/), then the American m/d/y is assumed; whereas if the separator is a dash (-) or a dot (.), then the European d-m-y format is assumed.

In your date string, you have 12-16-2013. 16 isn't a valid month, and hence strtotime() returns false.

Since you can't use DateTime class, you could manually replace the - with / using str_replace() to convert the date string into a format that strtotime() understands:

$date = '2-16-2013';
echo date('Y-m-d', strtotime(str_replace('-','/', $date))); // => 2013-02-16

How get the base URL via context path in JSF?

JSTL 1.2 variation leveraged from BalusC answer

<c:set var="baseURL" value="${pageContext.request.requestURL.substring(0, pageContext.request.requestURL.length() - pageContext.request.requestURI.length())}${pageContext.request.contextPath}/" />

  <base href="${baseURL}" />

How to clone git repository with specific revision/changeset?

$ git clone $URL
$ git reset --hard $SHA1

To again go back to the most recent commit

$ git pull

How can I print using JQuery

function printResult() {
    var DocumentContainer = document.getElementById('your_div_id');
    var WindowObject ='', "PrintWindow", "width=750,height=650,top=50,left=50,toolbars=no,scrollbars=yes,status=no,resizable=yes");

Which browser has the best support for HTML 5 currently?

Ones that are built using a recent webkit build, and Presto.

Safari 3.1 for webkit
Opera for Presto.

I'm pretty sure firefox will start supporting html5 partially in 3.1

All support is extremely partial. Check here for information on what is supported.

ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)

just enter the terminal

mysql -u root -p . than it will ask password to you

flutter run: No connected devices

If you are using mobile,

  • Turn on your developer options.

  • Turn on USB debugging option

conditional Updating a list using LINQ

If you really want to use linq, you can do something like this

li= (from tl in li
    select new Myclass
        name =,
        age = ( == "di" ? 10 : ( == "marks" ? 20 : 30))



li = li.Select(ex => new MyClass { name =, age = ( == "di" ? 10 : ( == "marks" ? 20 : 30)) }).ToList();

This assumes that there are only 3 types of name. I would externalize that part into a function to make it more manageable.

How to set JAVA_HOME path on Ubuntu?

add JAVA_HOME to the file:


for it to be available to the entire system (you would need to restart Ubuntu though)

How to catch curl errors in PHP

You can use the curl_error() function to detect if there was some error. For example:

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $your_url);
curl_setopt($ch, CURLOPT_FAILONERROR, true); // Required for HTTP error codes to be reported via our call to curl_error($ch)
if (curl_errno($ch)) {
    $error_msg = curl_error($ch);

if (isset($error_msg)) {
    // TODO - Handle cURL error accordingly

See the description of libcurl error codes here

See the description of PHP curl_errno() function here

See the description of PHP curl_error() function here

Regular expression to find URLs within a string

I use the logic of finding text between two dots or periods

the regex below works fine with python


How to manually install a pypi module without pip/easy_install?

  1. Download the package
  2. unzip it if it is zipped
  3. cd into the directory containing
  4. If there are any installation instructions contained in documentation contianed herein, read and follow the instructions OTHERWISE
  5. type in python install

You may need administrator privileges for step 5. What you do here thus depends on your operating system. For example in Ubuntu you would say sudo python install

EDIT- thanks to kwatford (see first comment)

To bypass the need for administrator privileges during step 5 above you may be able to make use of the --user flag. In this way you can install the package only for the current user.

The docs say:

Files will be installed into subdirectories of site.USER_BASE (written as userbase hereafter). This scheme installs pure Python modules and extension modules in the same location (also known as site.USER_SITE). Here are the values for UNIX, including Mac OS X:

More details can be found here:

How to force a hover state with jQuery?

I think the best solution I have come across is on this stackoverflow. This short jQuery code allows all your hover effects to show on click or touch..
No need to add anything within the function.

$('body').on('touchstart', function() {});

Hope this helps.

Create session factory in Hibernate 4

The following expresses the experience I had with hibernate 4.0.0.Final.

The javadoc (distributed under LGPL license) of org.hibernate.cfg.Configuration class states that:

NOTE : This will be replaced by use of ServiceRegistryBuilder and org.hibernate.metamodel.MetadataSources instead after the 4.0 release at which point this class will become deprecated and scheduled for removal in 5.0. See HHH-6183, HHH-2578 and HHH-6586 for details

After looking at issue 2578, i used something like this:

ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().configure().buildServiceRegistry();
MetadataSources metadataSources = new MetadataSources(serviceRegistry);
SessionFactory sessionFactory = metadataSources.buildMetadata().buildSessionFactory();

For it to start reading configuration, i had to modify my hibernate 3.2.6 configuration and mapping files to use xmlns="" and xmlns="" and also remove the dtd specifications.

I couldn't find a way for it to inspect mappings defined in hibernate.cfg.xml and hibernate. prefix for hibernate-related properties in hibernate.cfg.xml is no longer optional.

This might work for some.

I, for one, ran into some error because mapping files contained <cache usage="read-write" /> and ended up using deprecated Configuration way:

Configuration configuration = new Configuration().configure();
SessionFactoryImpl sessionFactory = (SessionFactoryImpl) configuration.buildSessionFactory();
EventListenerRegistry listenerRegistry = sessionFactory.getServiceRegistry().getService(EventListenerRegistry.class);
SolrIndexEventListener indexListener = new SolrIndexEventListener(); // a SaveOrUpdateEventListener i wanted to attach
listenerRegistry.appendListeners(EventType.SAVE_UPDATE, indexListener);

I had to programatically append event listeners because Configuration no longer looks for them in hibernate.cfg.xml

No mapping found for HTTP request with URI Spring MVC

I have the same problem.... I change my project name and i have this solution was the checking project refences and use / in my web.xml (instead of /*)

How to see the changes in a Git commit?

Another possibility:

git log -p COMMIT -1

How to make the division of 2 ints produce a float instead of another int?

You can cast the numerator or the denominator to float...

int operations usually return int, so you have to change one of the operanding numbers.

Set up Python 3 build system with Sublime Text 3

Run Python Files in Sublime Text3

For Sublime Text 3, First Install Package Control:

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

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

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

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

How to close an iframe within iframe itself

None of this solution worked for me since I'm in a cross-domain scenario creating a bookmarklet like Pinterest's Pin It.

I've found a bookmarklet template on GitHub that solved the problem of closing the Iframe sending the command from within it.

Since I can't access any element from parent window within the IFrame, this communication can only be made posting events between the two windows using window.postMessage

All these steps are on the GitHub link:

1- You have to inject a JS file on the parent page.

2- In this file injected on the parent, add a window event listner

    window.addEventListener('message', function(e) {
       var someIframe = window.parent.document.getElementById('iframeid');

This listener will handle the close and any other event you wish

3- Inside the Iframe page you send the close command via postMessage:

   $(this).trigger('post-message', [{
                    event: 'unload-bookmarklet'

Follow the template on and you'll be fine!

Hope it helps,

How do I sort a two-dimensional (rectangular) array in C#?

This code should do what you are after, I haven't generalised it for n by n, but that is straight forward. That said - I agree with MusiGenesis, using another object that is a little better suited to this (especially if you intend to do any sort of binding)

(I found the code here)

string[][] array = new string[3][];

array[0] = new string[3] { "apple", "apple", "apple" };
array[1] = new string[3] { "banana", "banana", "dog" };
array[2] = new string[3] { "cat", "hippo", "cat" };         

for (int i = 0; i < 3; i++)
   Console.WriteLine(String.Format("{0} {1} {2}", array[i][0], array[i][1], array[i][2]));

int j = 2;

Array.Sort(array, delegate(object[] x, object[] y)
    return (x[j] as IComparable).CompareTo(y[ j ]);

for (int i = 0; i < 3; i++)
  Console.WriteLine(String.Format("{0} {1} {2}", array[i][0], array[i][1], array[i][2]));

Read each line of txt file to new array element

    $file = file("links.txt");

This will be accept the txt file as array. So write anything to the links.txt file (use one line for one element) after, run this page :) your array will be $file

Can I get Unix's pthread.h to compile in Windows?

As @Ninefingers mentioned, pthreads are unix-only. Posix only, really.

That said, Microsoft does have a library that duplicates pthreads:

Microsoft Windows Services for UNIX Version 3.5

Library Download

Better way to find last used row

I preferred search last blank cell:

Il you want last empty cell of column you can do that

Dim sh as Worksheet, r as range
set sh = ActiveWorksheet 'if you want an other it's possible

'find a value 
'Columns("A:D") 'to check on multiple columns 
Set r = sh.Columns("A").Find(What:="*", SearchOrder:=xlByRows, SearchDirection:=xlPrevious)
'no value return first row
If r Is Nothing Then Set r = sh.Cells(1, "A") Else Set r = sh1.Cells(r.Row + 1, "A")

If this is to insert new row, find on multiple columns is a good choice because first column can contains less rows than next columns

JavaScript to get rows count of a HTML table

This is another option, using jQuery and getting only tbody rows (with the data) and desconsidering thead/tfoot.

$("#tableId > tbody > tr").length

console.log($("#myTableId > tbody > tr").length);
.demo {
   border:1px solid #C0C0C0;

.demo caption {

.demo th {
   border:1px solid #C0C0C0;

.demo td {
   border:1px solid #C0C0C0;
<script src=""></script>
<table id="myTableId" class="demo">
   <caption>Table 1</caption>
         <th>Header 1</th>
         <th>Header 2</th>
         <th>Header 3</th>
         <th>Header 4</th>
         <td colspan=4 style="background:#F0F0F0">&nbsp; </td>

How to handle screen orientation change when progress dialog and background thread active?

I faced the same situation. What I did was get only one instance for my progress dialog in the entire application.

First, I created a DialogSingleton class to get only one instance (Singleton pattern)

public class DialogSingleton
    private static Dialog dialog;

    private static final Object mLock = new Object();
    private static DialogSingleton instance;

    private DialogSingleton()


    public static DialogSingleton GetInstance()
        synchronized (mLock)
            if(instance == null)
                instance = new DialogSingleton();

            return instance;

    public void DialogShow(Context context, String title)
            dialog = new ProgressDialog(context, 2);




    public void DialogDismiss(Context context)
        if(!((Activity)context).isFinishing() && dialog.isShowing())

As I show in this class, I have the progress dialog as attribute. Every time I need to show a progress dialog, I get the unique instance and create a new ProgressDialog.

DialogSingleton.GetInstance().DialogShow(this, "My title here!");

When I am done with the background task, I call again the unique instance and dismiss its dialog.


I save the background task status in my shared preferences. When I rotate the screen, I ask if I have a task running for this activity: (onCreate)

if(Boolean.parseBoolean(preference.GetValue(IS_TASK_NAME_EXECUTED_KEY, "boolean").toString()))
    DialogSingleton.GetInstance().DialogShow(this, "Checking credentials!");
} // preference object gets the info from shared preferences (my own implementation to get and put data to shared preferences) and IS_TASK_NAME_EXECUTED_KEY is the key to save this flag (flag to know if this activity has a background task already running).

When I start running a background task:

preference.AddValue(IS_TASK_NAME_EXECUTED_KEY, true, "boolean");

DialogSingleton.GetInstance().DialogShow(this, "My title here!");

When I finish running a background task:

preference.AddValue(IS_TASK_NAME_EXECUTED_KEY, false, "boolean");


I hope it helps.

USB Debugging option greyed out

You have to enable USB debugging before plugging your device in to the computer. Unplug device then try to enable USB debugging. This should work. If so, you can then plug it back into the computer and it should work

How to hide Android soft keyboard on EditText

Hide the keyboard


Show Keyboard


in the parent layout


Using --add-host or extra_hosts with docker-compose

It seems like it should be made possible to say:

 - "loghost:localhost"

So if the part after the colon (normally an IP address) doesn't start with a digit, then name resolution will be performed to look up an IP for localhost, and add something like to the container's /etc/hosts: loghost

...assuming that localhost resolves to on the host system.

It looks like it'd be really easy to add in docker-compose's source code: compose/config/'s parse_extra_hosts function would likely do it.

For docker itself, this would probably be addable in opts/hosts.go's ValidateExtraHost function, though then it's not strictly validating anymore, so the function would be a little misnamed.

It might actually be a little better to add this to docker, not docker-compose - docker-compose might just get it automatically if docker gets it.

Sadly, this would probably require a container bounce to change an IP address.

Replace duplicate spaces with a single space in T-SQL

update mytable
set myfield = replace (myfield, '  ',  ' ')
where charindex('  ', myfield) > 0 

Replace will work on all the double spaces, no need to put in multiple replaces. This is the set-based solution.

How to extract text from a PDF?

The best thing I can currently think of (within the list of "simple" tools) is Ghostscript (current version is v.8.71) and the PostScript utility program Ghostscript ships it in its lib subdirectory. Try this (on Windows):

gswin32c.exe ^
   -q ^
   -sFONTPATH=c:/windows/fonts ^
   -dSAFER ^
   -dCOMPLEX ^
   -f ^
   -dFirstPage=3 ^
   -dLastPage=7 ^
   input.pdf ^
   -dQUIET ^
   -c quit

This command processes pages 3-7 of input.pdf. Read the comments in the file itself to see what the "weird" numbers and additional infos mean (they indicate strings, positions, widths, colors, pictures, rectangles, fonts and page breaks...). To get a "simple" text output, replace the -dCOMPLEX part by -dSIMPLE.

Connect multiple devices to one device via Bluetooth

Bluetooth 4.0 Allows you in a Bluetooth piconet one master can communicate up to 7 active slaves, there can be some other devices up to 248 devices which sleeping.

Also you can use some slaves as bridge to participate with more devices.

ExecJS and could not find a JavaScript runtime

Adding the following gem to my Gemfile solved the issue:

gem 'therubyracer'

Then bundle your new dependencies:

$ bundle install

jQuery count child elements

It is simply possible with childElementCount in pure javascript

var countItems = document.getElementsByTagName("ul")[0].childElementCount;_x000D_
<div id="selected">_x000D_

C++ equivalent of StringBuffer/StringBuilder?

You can use .append() for simply concatenating strings.

std::string s = "string1";

I think you might even be able to do:

std::string s = "string1";
s += "string2";

As for the formatting operations of C#'s StringBuilder, I believe snprintf (or sprintf if you want to risk writing buggy code ;-) ) into a character array and convert back to a string is about the only option.

How to convert View Model into JSON object in ASP.NET MVC?

Andrew had a great response but I wanted to tweek it a little. The way this is different is that I like my ModelViews to not have overhead data in them. Just the data for the object. It seem that ViewData fits the bill for over head data, but of course I'm new at this. I suggest doing something like this.


virtual public ActionResult DisplaySomeWidget(int id)
    SomeModelView returnData = someDataMapper.getbyid(1);
    var serializer = new JavaScriptSerializer();
    ViewData["JSON"] = serializer.Serialize(returnData);
    return View(myview, returnData);


//create base js object;
var myWidget= new Widget(); //Widget is a class with a public member variable called data. <%= ViewData["JSON"] %>;

What This does for you is it gives you the same data in your JSON as in your ModelView so you can potentially return the JSON back to your controller and it would have all the parts. This is similar to just requesting it via a JSONRequest however it requires one less call so it saves you that overhead. BTW this is funky for Dates but that seems like another thread.

Writing file to web server - ASP.NET

There are methods like WriteAllText in the File class for common operations on files.

Use the MapPath method to get the physical path for a file in your web application.

File.WriteAllText(Server.MapPath("~/data.txt"), TextBox1.Text);

What is the meaning of Bus: error 10 in C

For one, you can't modify string literals. It's undefined behavior.

To fix that you can make str a local array:

char str[] = "First string";

Now, you will have a second problem, is that str isn't large enough to hold str2. So you will need to increase the length of it. Otherwise, you will overrun str - which is also undefined behavior.

To get around this second problem, you either need to make str at least as long as str2. Or allocate it dynamically:

char *str2 = "Second string";
char *str = malloc(strlen(str2) + 1);  //  Allocate memory
//  Maybe check for NULL.

strcpy(str, str2);

//  Always remember to free it.

There are other more elegant ways to do this involving VLAs (in C99) and stack allocation, but I won't go into those as their use is somewhat questionable.

As @SangeethSaravanaraj pointed out in the comments, everyone missed the #import. It should be #include:

#include <stdio.h>
#include <string.h>

Finding blocking/locking queries in MS SQL (mssql)

You may find this query useful:

FROM sys.dm_exec_requests
WHERE DB_NAME(database_id) = 'YourDBName' 
AND blocking_session_id <> 0

JSON character encoding - is UTF-8 well-supported by browsers or should I use numeric escape sequences?

Reading the json rfc ( it is clear that the preferred encoding is utf-8.

FYI, RFC 4627 is no longer the official JSON spec. It was obsoleted in 2014 by RFC 7159, which was then obsoleted in 2017 by RFC 8259, which is the current spec.

RFC 8259 states:

8.1. Character Encoding

JSON text exchanged between systems that are not part of a closed ecosystem MUST be encoded using UTF-8 [RFC3629].

Previous specifications of JSON have not required the use of UTF-8 when transmitting JSON text. However, the vast majority of JSON-based software implementations have chosen to use the UTF-8 encoding, to the extent that it is the only encoding that achieves interoperability.

Implementations MUST NOT add a byte order mark (U+FEFF) to the beginning of a networked-transmitted JSON text. In the interests of interoperability, implementations that parse JSON texts MAY ignore the presence of a byte order mark rather than treating it as an error.

How to force NSLocalizedString to use a specific language

I had the same problem recently and I didn't want to start and patch my entire NSLocalizedString nor force the app to restart for the new language to work. I wanted everything to work as-is.

My solution was to dynamically change the main bundle's class and load the appropriate bundle there:

Header file

@interface NSBundle (Language)


#import <objc/runtime.h>

static const char _bundle=0;

@interface BundleEx : NSBundle

@implementation BundleEx
-(NSString*)localizedStringForKey:(NSString *)key value:(NSString *)value table:(NSString *)tableName
    NSBundle* bundle=objc_getAssociatedObject(self, &_bundle);
    return bundle ? [bundle localizedStringForKey:key value:value table:tableName] : [super localizedStringForKey:key value:value table:tableName];

@implementation NSBundle (Language)
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^
        object_setClass([NSBundle mainBundle],[BundleEx class]);
    objc_setAssociatedObject([NSBundle mainBundle], &_bundle, language ? [NSBundle bundleWithPath:[[NSBundle mainBundle] pathForResource:language ofType:@"lproj"]] : nil, OBJC_ASSOCIATION_RETAIN_NONATOMIC);

So basically, when your app starts and before you load your first controller, simply call:

[NSBundle setLanguage:@"en"];

When your user changes his preferred language in your setting screen, simply call it again:

[NSBundle setLanguage:@"fr"];

To reset back to system defaults, simply pass nil:

[NSBundle setLanguage:nil];


For those who need a Swift version:

var bundleKey: UInt8 = 0

class AnyLanguageBundle: Bundle {

    override func localizedString(forKey key: String,
                                  value: String?,
                                  table tableName: String?) -> String {

        guard let path = objc_getAssociatedObject(self, &bundleKey) as? String,
              let bundle = Bundle(path: path) else {

            return super.localizedString(forKey: key, value: value, table: tableName)

        return bundle.localizedString(forKey: key, value: value, table: tableName)

extension Bundle {

    class func setLanguage(_ language: String) {

        defer {

            object_setClass(Bundle.main, AnyLanguageBundle.self)

        objc_setAssociatedObject(Bundle.main, &bundleKey,    Bundle.main.path(forResource: language, ofType: "lproj"), .OBJC_ASSOCIATION_RETAIN_NONATOMIC)

Converting 'ArrayList<String> to 'String[]' in Java

An alternative in Java 8:

String[] strings =[]::new);

Java 11+:

String[] strings = list.toArray(String[]::new);

How to show loading spinner in jQuery?

Try this code How To Show Loading Spinner In JQuery?

<!DOCTYPE html>
<html lang="en">
<meta charset="utf-8">
<title>How To Show Loading Spinner In JQuery? -</title>
    display: none;
    position: fixed;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    z-index: 999;
    background: rgba(255,255,255,0.8) url("loader-img.gif") center no-repeat;
/* Turn off scrollbar when body element has the loading class */
    overflow: hidden;   
/* Make spinner image visible when body element has the loading class */
body.loading .overlay{
    display: block;
<script src=""></script>
// Initiate an Ajax request on button click
$(document).on("click", "button", function(){
    $.get("customers.php", function(data){

    ajaxStart: function(){
    ajaxStop: function(){ 
<body style="text-align: center;">
    <button type="button">Get Customers Details</button>
    <p>Click the above button to get the customers details from the web server via Ajax.</p>
    <div class="overlay"></div>

Disable browser's back button

Even I faced the same situation before...and didn't have any help. try these things maybe these will work for you

in login page <head> tag:

<script type="text/javascript">

in Logout Button I did this:

protected void Btn_Logout_Click(object sender, EventArgs e)      

and on login page I have put the focus on Username textbox like this:

protected void Page_Load(object sender, EventArgs e)

hope this helps... :) someone plz teach me how to edit this page...

PHP get dropdown value and text

you can make it using js file and ajax call. while validating data using js file we can read the text of selected dropdown

$("#dropdownid").val();   for value
$("#dropdownid").text(); for selected value

catch these into two variables and take it as inputs to ajax call for a php file

     url:"callingphpfile.php",//url of fetching php  
     method:"POST", //type 
     success:function(data) //return the data     


and in php you can get it as

    if (isset($_POST["val1"])) {
    $val1= $_POST["val1"] ;

if (isset($_POST["val2"])) {
  $selectedtext= $_POST["val1"];

Angular2 module has no exported member

I was facing same issue and I just started app with new port and everything looks good.

ng serve --port 4201

What linux shell command returns a part of a string?

expr(1) has a substr subcommand:

expr substr <string> <start-index> <length>

This may be useful if you don't have bash (perhaps embedded Linux) and you don't want the extra "echo" process you need to use cut(1).

How do I schedule a task to run at periodic intervals?

timer.scheduleAtFixedRate( new Task(), 1000,3000); 

React Native add bold or italics to single words in <Text> field

you can use

import ParsedText from 'react-native-parsed-text';_x000D_
class Example extends React.Component {_x000D_
  static displayName = 'Example';_x000D_
  handleUrlPress(url) {_x000D_
  handlePhonePress(phone) {_x000D_
    AlertIOS.alert(`${phone} has been pressed!`);_x000D_
  handleNamePress(name) {_x000D_
    AlertIOS.alert(`Hello ${name}`);_x000D_
  handleEmailPress(email) {_x000D_
    AlertIOS.alert(`send email to ${email}`);_x000D_
  renderText(matchingString, matches) {_x000D_
    // matches => ["[@michel:5455345]", "@michel", "5455345"]_x000D_
    let pattern = /\[(@[^:]+):([^\]]+)\]/i;_x000D_
    let match = matchingString.match(pattern);_x000D_
    return `^^${match[1]}^^`;_x000D_
  render() {_x000D_
    return (_x000D_
      <View style={styles.container}>_x000D_
              {type: 'url',                       style: styles.url, onPress: this.handleUrlPress},_x000D_
              {type: 'phone',                     style:, onPress: this.handlePhonePress},_x000D_
              {type: 'email',                     style:, onPress: this.handleEmailPress},_x000D_
              {pattern: /Bob|David/,              style:, onPress: this.handleNamePress},_x000D_
              {pattern: /\[(@[^:]+):([^\]]+)\]/i, style: styles.username, onPress: this.handleNamePress, renderText: this.renderText},_x000D_
              {pattern: /42/,                     style: styles.magicNumber},_x000D_
              {pattern: /#(\w+)/,                 style: styles.hashTag},_x000D_
          childrenProps={{allowFontScaling: false}}_x000D_
          Hello this is an example of the ParsedText, links like or are clickable and phone number 444-555-6666 can call too._x000D_
          But you can also do more with this package, for example Bob will change style and David too. [email protected]_x000D_
          And the magic number is 42!_x000D_
          #react #react-native_x000D_
const styles = StyleSheet.create({_x000D_
  container: {_x000D_
    flex: 1,_x000D_
    justifyContent: 'center',_x000D_
    alignItems: 'center',_x000D_
    backgroundColor: '#F5FCFF',_x000D_
  url: {_x000D_
    color: 'red',_x000D_
    textDecorationLine: 'underline',_x000D_
  email: {_x000D_
    textDecorationLine: 'underline',_x000D_
  text: {_x000D_
    color: 'black',_x000D_
    fontSize: 15,_x000D_
  phone: {_x000D_
    color: 'blue',_x000D_
    textDecorationLine: 'underline',_x000D_
  name: {_x000D_
    color: 'red',_x000D_
  username: {_x000D_
    color: 'green',_x000D_
    fontWeight: 'bold'_x000D_
  magicNumber: {_x000D_
    fontSize: 42,_x000D_
    color: 'pink',_x000D_
  hashTag: {_x000D_
    fontStyle: 'italic',_x000D_

Total memory used by Python process?

For Unix systems command time (/usr/bin/time) gives you that info if you pass -v. See Maximum resident set size below, which is the maximum (peak) real (not virtual) memory that was used during program execution:

$ /usr/bin/time -v ls /

    Command being timed: "ls /"
    User time (seconds): 0.00
    System time (seconds): 0.01
    Percent of CPU this job got: 250%
    Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.00
    Average shared text size (kbytes): 0
    Average unshared data size (kbytes): 0
    Average stack size (kbytes): 0
    Average total size (kbytes): 0
    Maximum resident set size (kbytes): 0
    Average resident set size (kbytes): 0
    Major (requiring I/O) page faults: 0
    Minor (reclaiming a frame) page faults: 315
    Voluntary context switches: 2
    Involuntary context switches: 0
    Swaps: 0
    File system inputs: 0
    File system outputs: 0
    Socket messages sent: 0
    Socket messages received: 0
    Signals delivered: 0
    Page size (bytes): 4096
    Exit status: 0

document.getElementByID is not a function

I've modified your script to work with jQuery, if you wish to do so.

    //To add a task when the user hits the return key
          if(evt.keyCode == 13)
             add_task($(this), evt);
    //To add a task when the user clicks on the submit button

function add_task(textBox, evt){
  var taskText = textBox.val();
  $("<li />").text(taskText).appendTo("#tasks");

How can I create a progress bar in Excel VBA?

In the past, with VBA projects, I've used a label control with the background colored and adjust the size based on the progress. Some examples with similar approaches can be found in the following links:


Here is one that uses Excel's Autoshapes:

Drag and drop a DLL to the GAC ("assembly") in windows server 2008 .net 4.0

In .net 4.0 Microsoft removed the ability to add DLLs to the Assembly simply by dragging and dropping.

Instead you need to use gacutil.exe, or create an installer to do it. Microsoft actually doesn’t recommend using gacutil, but I went that route anyway.

To use gacutil on a development machine go to:
Start -> programs -> Microsoft Visual studio 2010 -> Visual Studio Tools -> Visual Studio Command Prompt (2010)

Then use these commands to uninstall and Reinstall respectively. Note I did NOT include .dll in the uninstall command.
gacutil /u myDLL
gacutil /i "C:\Program Files\Custom\myDLL.dll"

To use Gacutil on a non-development machine you will have to copy the executable and config file from your dev machine to the production machine. It looks like there are a few different versions of Gacutil. The one that worked for me, I found here:
C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\Bin\NETFX 4.0 Tools\gacutil.exe C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\Bin\NETFX 4.0 Tools\gacutil.exe.config

Copy the files here or to the appropriate .net folder;

Then use these commands to uninstall and reinstall respectively
"C:\Users\BHJeremy\Desktop\Installing to the Gac in .net 4.0\gacutil.exe" /u "myDLL"

"C:\Windows\Microsoft.NET\Framework\v4.0.30319\gacutil.exe" /i "C:\Program Files\Custom\myDLL.dll"

Background color of text in SVG

Answer by Robert Longson (@RobertLongson) with modifications:

<svg width="100%" height="100%">
    <filter x="0" y="0" width="1" height="1" id="solid">
      <feFlood flood-color="yellow"/>
      <feComposite in="SourceGraphic" operator="xor"/>
  <text filter="url(#solid)" x="20" y="50" font-size="50"> solid background </text>
  <text x="20" y="50" font-size="50">solid background</text>

and we have no bluring and no heavy "getBBox" :) Padding is provided by white spaces in text-element with filter. It's worked for me

Convert integer into byte array (Java)

Here's a method that should do the job just right.

public byte[] toByteArray(int value)
    final byte[] destination = new byte[Integer.BYTES];
    for(int index = Integer.BYTES - 1; index >= 0; index--)
        destination[i] = (byte) value;
        value = value >> 8;
    return destination;

How to make sure docker's time syncs with that of the host?

Although this is not a general solution for every host, someone may find it useful. If you know where you are based (UK for me) then look at tianon's answer here.

FROM alpine:3.6
RUN apk add --no-cache tzdata
ENV TZ Europe/London

This is what I added to my Dockerfile ^ and the timezone problem was fixed.

Python read-only property

I am dissatisfied with the previous two answers to create read only properties because the first solution allows the readonly attribute to be deleted and then set and doesn't block the __dict__. The second solution could be worked around with testing - finding the value that equals what you set it two and changing it eventually.

Now, for the code.

def final(cls):
    clss = cls
    def __init_subclass__(cls, **kwargs):
        raise TypeError("type '{}' is not an acceptable base type".format(clss.__name__))
    cls.__init_subclass__ = __init_subclass__
    return cls

def methoddefiner(cls, method_name):
    for clss in cls.mro():
            getattr(clss, method_name)
            return clss
    return None
def readonlyattributes(*attrs):
    """Method to create readonly attributes in a class
    Use as a decorator for a class. This function takes in unlimited 
    string arguments for names of readonly attributes and returns a
    function to make the readonly attributes readonly. 
    The original class's __getattribute__, __setattr__, and __delattr__ methods
    are redefined so avoid defining those methods in the decorated class
    You may create setters and deleters for readonly attributes, however
    if they are overwritten by the subclass, they lose access to the readonly
    Any method which sets or deletes a readonly attribute within
    the class loses access if overwritten by the subclass besides the __new__
    or __init__ constructors.
    This decorator doesn't support subclassing of these classes
    def classrebuilder(cls):
        def __getattribute__(self, name):
            if name == '__dict__':
                    from types import MappingProxyType
                    return MappingProxyType(super(cls, self).__getattribute__('__dict__'))
            return super(cls, self).__getattribute__(name)
        def __setattr__(self, name, value): 
                if name == '__dict__' or name in attrs:
                    import inspect
                    stack = inspect.stack()
                        the_class = stack[1][0].f_locals['self'].__class__
                        the_class = None
                    the_method = stack[1][0].f_code.co_name
                    if the_class != cls: 
                         if methoddefiner(type(self), the_method) != cls:
                            raise AttributeError("Cannot set readonly attribute '{}'".format(name))                        
                return super(cls, self).__setattr__(name, value)
        def __delattr__(self, name):                
                if name == '__dict__' or name in attrs:
                    import inspect
                    stack = inspect.stack()
                        the_class = stack[1][0].f_locals['self'].__class__
                        the_class = None
                    the_method = stack[1][0].f_code.co_name
                    if the_class != cls:
                        if methoddefiner(type(self), the_method) != cls:
                            raise AttributeError("Cannot delete readonly attribute '{}'".format(name))                        
                return super(cls, self).__delattr__(name)
        clss = cls
        cls.__getattribute__ = __getattribute__
        cls.__setattr__ = __setattr__
        cls.__delattr__ = __delattr__
        #This line will be moved when this algorithm will be compatible with inheritance
        cls = final(cls)
        return cls
    return classrebuilder

def setreadonlyattributes(cls, *readonlyattrs):
    return readonlyattributes(*readonlyattrs)(cls)

if __name__ == '__main__':
    #test readonlyattributes only as an indpendent module
    class ReadonlyFieldClass(object):
        def __init__(self, a, b):
            #Prevent initalization of the internal, unmodified PrivateFieldClass
            #External PrivateFieldClass can be initalized
            self.readonlyfield = a
            self.publicfield = b

    attr = None
    def main():
        global attr
        pfi = ReadonlyFieldClass('forbidden', 'changable')
        ###---test publicfield, ensure its mutable---###
            #get publicfield
            print('__getattribute__ works')
            #set publicfield
            pfi.publicfield = 'mutable'
            print('__setattr__ seems to work')
            #get previously set publicfield
            print('__setattr__ definitely works')
            #delete publicfield
            del pfi.publicfield 
            print('__delattr__ seems to work')
            #get publicfield which was supposed to be deleted therefore should raise AttributeError
            #publicfield wasn't deleted, raise RuntimeError
            raise RuntimeError('__delattr__ doesn\'t work')
            print('__delattr__ works')
            ###---test readonly, make sure its readonly---###
            #get readonlyfield
            print('__getattribute__ works')
            #set readonlyfield, should raise AttributeError
            pfi.readonlyfield = 'readonly'
            #apparently readonlyfield was set, notify user
            raise RuntimeError('__setattr__ doesn\'t work')
            print('__setattr__ seems to work')
                #ensure readonlyfield wasn't set
                print('__setattr__ works')
                #delete readonlyfield
                del pfi.readonlyfield
                #readonlyfield was deleted, raise RuntimeError
                raise RuntimeError('__delattr__ doesn\'t work')
                print('__delattr__ works')
            print("Dict testing")
            print(pfi.__dict__, type(pfi.__dict__))
            attr = pfi.readonlyfield
            print("__getattribute__ works")
            if pfi.readonlyfield != 'forbidden':
                raise RuntimeError("__getattr__ doesn't work")
                pfi.__dict__ = {}
                raise RuntimeError("__setattr__ doesn't work")
                print("__setattr__ works")
            del pfi.__dict__
            raise RuntimeError("__delattr__ doesn't work")
            print("__delattr__ works")
            print("Basic things work")


There is no point to making read only attributes except when your writing library code, code which is being distributed to others as code to use in order to enhance their programs, not code for any other purpose, like app development. The __dict__ problem is solved, because the __dict__ is now of the immutable types.MappingProxyType, so attributes cannot be changed through the __dict__. Setting or deleting __dict__ is also blocked. The only way to change read only properties is through changing the methods of the class itself.

Though I believe my solution is better than of the previous two, it could be improved. These are this code's weaknesses:

  1. Doesn't allow adding to a method in a subclass which sets or deletes a readonly attribute. A method defined in a subclass is automatically barred from accessing a readonly attribute, even by calling the superclass' version of the method.

  2. The class' readonly methods can be changed to defeat the read only restrictions.

However, there is not way without editing the class to set or delete a read only attribute. This isn't dependent on naming conventions, which is good because Python isn't so consistent with naming conventions. This provides a way to make read only attributes that cannot be changed with hidden loopholes without editing the class itself. Simply list the attributes to be read only when calling the decorator as arguments and they will become read only.

Credit to Brice's answer for getting the caller classes and methods.

How to Sort Multi-dimensional Array by Value?

One approach to achieve this would be like this

    $new = [
                'hashtag' => 'a7e87329b5eab8578f4f1098a152d6f4',
                'title' => 'Flower',
                'order' => 3,

                'hashtag' => 'b24ce0cd392a5b0b8dedc66c25213594',
                'title' => 'Free',
                'order' => 2,

                'hashtag' => 'e7d31fc0602fb2ede144d18cdffd816b',
                'title' => 'Ready',
                'order' => 1,

    $keys = array_column($new, 'order');

    array_multisort($keys, SORT_ASC, $new);



        [0] => Array
                [hashtag] => e7d31fc0602fb2ede144d18cdffd816b
                [title] => Ready
                [order] => 1

        [1] => Array
                [hashtag] => b24ce0cd392a5b0b8dedc66c25213594
                [title] => Free
                [order] => 2

        [2] => Array
                [hashtag] => a7e87329b5eab8578f4f1098a152d6f4
                [title] => Flower
                [order] => 3


How to assign execute permission to a .sh file in windows to be executed in linux

This is possible using the Info-Zip open-source Zip utilities. If unzip is run with the -X parameter, it will attempt to preserve the original permissions. If the source filesystem was NTFS and the destination is a Unix one, it will attempt to translate from one to the other. I do not have a Windows system available right now to test the translation, so you will have to experiment with which group needs to be awarded execute permissions. It'll be something like "Users" or "Any user"

What causes signal 'SIGILL'?

Make sure that all functions with non-void return type have a return statement.

While some compilers automatically provide a default return value, others will send a SIGILL or SIGTRAP at runtime when trying to leave a function without a return value.

Passing just a type as a parameter in C#

You can do this, just wrap it in typeof()


public void GetColumnValues(Type type)

Table border left and bottom

Give a class .border-lb and give this CSS

.border-lb {border: 1px solid #ccc; border-width: 0 0 1px 1px;}

And the HTML

<table width="770">
    <td class="border-lb">picture (border only to the left and bottom ) </td>
    <td class="border-lb">picture (border only to the left and bottom) </td>



Online SQL Query Syntax Checker

SQLFiddle will let you test out your queries, while it doesn't explicitly correct syntax etc. per se it does let you play around with the script and will definitely let you know if things are working or not.

Removing time from a Date object?

You can also manually change the time part of date and format in "dd/mm/yyyy" pattern according to your requirement.

  public static Date getZeroTimeDate(Date changeDate){

        Date returnDate=new Date(changeDate.getTime()-(24*60*60*1000));
        return returnDate;

If the return value is not working then check for the context parameter in web.xml. eg.


Importing a csv into mysql via command line

You can simply import by

mysqlimport --ignore-lines=1 --lines-terminated-by='\n' --fields-terminated-by=',' --fields-enclosed-by='"' --verbose --local -uroot -proot db_name csv_import.csv

Note: Csv File name and Table name should be same

C# cannot convert method to non delegate type

getTitle is a function, so you need to put () after it.

string t = obj.getTitle();

split python source code into multiple files?

I am researching module usage in python just now and thought I would answer the question Markus asks in the comments above ("How to import variables when they are embedded in modules?") from two perspectives:

  1. variable/function, and
  2. class property/method.

Here is how I would rewrite the main program to demonstrate variable reuse for Markus:

import f2
myStorage = f2.useMyVars(0) # initialze class and properties
for i in range(0,10):
    print "Hello, "
print "Display class property myVar:", myStorage.getMyVar()
print "Display global variable gMyVar:", f2.get_gMyVar()

Here is how I would rewrite the reusable module

# Module:
# Example 1: functions to store and retrieve global variables
gMyVar = 0
def print_world():
    print "World!"
def get_gMyVar():
    return gMyVar # no need for global statement 
def inc_gMyVar():
    global gMyVar
    gMyVar += 1  

# Example 2: class methods to store and retrieve properties
class useMyVars(object):
    def __init__(self, myVar):
        self.myVar = myVar
    def getMyVar(self):
        return self.myVar
    def setMyVar(self, myVar):
        self.myVar = myVar
    def print_helloWorld(self):
        print "Hello, World!"

When is executed here is what the output would look like:

%run ""
Display class property myVar: 9
Display global variable gMyVar: 10

I think the point to Markus would be:

  • To reuse a module's code more than once, put your module's code into functions or classes,
  • To reuse variables stored as properties in modules, initialize properties within a class and add "getter" and "setter" methods so variables do not have to be copied into the main program,
  • To reuse variables stored in modules, initialize the variables and use getter and setter functions. The setter functions would declare the variables as global.

Stop on first error

Maybe you want set -e:

This tells bash that it should exit the script if any statement returns a non-true return value. The benefit of using -e is that it prevents errors snowballing into serious issues when they could have been caught earlier. Again, for readability you may want to use set -o errexit.

ORA-12505, TNS:listener does not currently know of SID given in connect descriptor

Connection con=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe","scott","tiger");

Error I got:

java.sql.SQLException: Listener refused the connection with the following error: ORA-12505, TNS:listener does not currently know of SID given in connect descriptor The Connection descriptor used by the client was: localhost:1521:xe

How I solved it:

Connection con=DriverManager.getConnection("jdbc:oracle:thin:localhost:1521:xe","scott","tiger");

(Remove @)

Don't know why, but its working now...

Android Studio - Emulator - eglSurfaceAttrib not implemented

I've found the same thing, but only on emulators that have the Use Host GPU setting ticked. Try turning that off, you'll no longer see those warnings (and the emulator will run horribly, horribly slowly..)

In my experience those warnings are harmless. Notice that the "error" is EGL_SUCCESS, which would seem to indicate no error at all!

How to disable anchor "jump" when loading a page?

There are other ways of tracking what tab you're on; perhaps setting a cookie, or a value in a hidden field, etc etc.

I would say that if you don't want the page jumping on load, you would be better off using one of these other options rather than the hash, because the main reason for using the hash in preference to them is to allow exactly what you're wanting to block.

Another point - the page won't jump if your hash links don't match the names of the tags in the document, so perhaps if you want to keep using the hash you could manipulate the content so that the tags are named differently. If you use a consistent prefix, you will still be able to use Javascript to jump between then.

Hope that helps.

Is there a way to run Bash scripts on Windows?

Install Cygwin, which includes Bash among many other GNU and Unix utilities (without whom its unlikely that bash will be very useful anyway).

Another option is MinGW's MSYS which includes bash and a smaller set of the more important utilities such as awk. Personally I would have preferred Cygwin because it includes such heavy lifting tools as Perl and Python which I find I cannot live without, while MSYS skimps on these and assumes you are going to install them yourself.

Updated: If anyone is interested in this answer and is running MS-Windows 10, please note that MS-Windows 10 has a "Windows Subsystem For Linux" feature which - once enabled - allows you to install a user-mode image of Ubuntu and then run Bash on that. This provides 100% compatibility with Ubuntu for debugging and running Bash scripts, but this setup is completely standalone from Windows and you cannot use Bash scripts to interact with Windows features (such as processes and APIs) except for limited access to files through the DrvFS feature.

How to extend available properties of User.Identity

For anyone that finds this question looking for how to access custom properties in ASP.NET Core 2.1 - it's much easier: You'll have a UserManager, e.g. in _LoginPartial.cshtml, and then you can simply do (assuming "ScreenName" is a property that you have added to your own AppUser which inherits from IdentityUser):

@using Microsoft.AspNetCore.Identity

@using <namespaceWhereYouHaveYourAppUser>

@inject SignInManager<AppUser> SignInManager
@inject UserManager<AppUser> UserManager

@if (SignInManager.IsSignedIn(User)) {
    <form asp-area="Identity" asp-page="/Account/Logout" asp-route-returnUrl="@Url.Action("Index", "Home", new { area = "" })" 
          method="post" id="logoutForm" 
          class="form-inline my-2 my-lg-0">

        <ul class="nav navbar-nav ml-auto">
            <li class="nav-item">
                <a class="nav-link" asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage">
                    Hello @((await UserManager.GetUserAsync(User)).ScreenName)!
                    <!-- Original code, shows Email-Address: @UserManager.GetUserName(User)! -->
            <li class="nav-item">
                <button type="submit" class="btn btn-link nav-item navbar-link nav-link">Logout</button>

} else {
    <ul class="navbar-nav ml-auto">
        <li class="nav-item"><a class="nav-link" asp-area="Identity" asp-page="/Account/Register">Register</a></li>
        <li class="nav-item"><a class="nav-link" asp-area="Identity" asp-page="/Account/Login">Login</a></li>

Import Certificate to Trusted Root but not to Personal [Command Line]

To print the content of Root store:

certutil -store Root

To output content to a file:

certutil -store Root > root_content.txt

To add certificate to Root store:

certutil -addstore -enterprise Root file.cer

How to use vagrant in a proxy environment?

In PowerShell, you could set the http_proxy and https_proxy environment variables like so:


What's wrong with nullable columns in composite primary keys?

NULL == NULL -> false (at least in DBMSs)

So you wouldn't be able to retrieve any relationships using a NULL value even with additional columns with real values.

Using onBlur with JSX and React

There are a few problems here.

1: onBlur expects a callback, and you are calling renderPasswordConfirmError and using the return value, which is null.

2: you need a place to render the error.

3: you need a flag to track "and I validating", which you would set to true on blur. You can set this to false on focus if you want, depending on your desired behavior.

handleBlur: function () {
  this.setState({validating: true});
render: function () {
  return <div>
        placeholder="Password (confirm)"
renderPasswordConfirmError: function() {
  if (this.state.validating && this.state.password !== this.state.password2) {
    return (
        <label className="error">Please enter the same password again.</label>
  return null;

Converting A String To Hexadecimal In Java

Here's a short way to convert it to hex:

public String toHex(String arg) {
    return String.format("%040x", new BigInteger(1, arg.getBytes(/*YOUR_CHARSET?*/)));

Java double comparison epsilon

Floating point numbers only have so many significant digits, but they can go much higher. If your app will ever handle large numbers, you will notice the epsilon value should be different.

0.001+0.001 = 0.002 BUT 12,345,678,900,000,000,000,000+1=12,345,678,900,000,000,000,000 if you are using floating point and double. It's not a good representation of money, unless you are damn sure you'll never handle more than a million dollars in this system.

Java - Check if input is a positive integer, negative integer, natural number and so on.

What about using the following:

int number = input.nextInt();
if (number < 0) {
    // negative
} else {
   // it's a positive

How to change the button text for 'Yes' and 'No' buttons in the MessageBox.Show dialog?

I didn't think it would be that simple! go to this link:

Download the source. Take the MessageBoxManager.cs file, add it to your project. Now just register it once in your code (for example in the Main() method inside your Program.cs file) and it will work every time you call MessageBox.Show():

    MessageBoxManager.OK = "Alright";
    MessageBoxManager.Yes = "Yep!";
    MessageBoxManager.No = "Nope";

See this answer for the source code here for MessageBoxManager.cs.

JavaScript Editor Plugin for Eclipse

JavaScript that allows for syntax checking


and autosuggestions for .js files in Eclipse?

  1. Use JSDoc more as JSDT has nice support for the standard, so you will get more suggestions for your own code.
  2. There is new TernIDE that provide additional hints for .js and AngulatJS .html. Get them together as Anide from

As Nodeclipse lead, I am always looking for what is available in Eclipse ecosystem. Nodeclipse site has even more links, and I am inviting to collaborate on the JavaScript tools on GitHub

Convert Linq Query Result to Dictionary

Looking at your example, I think this is what you want:

var dict = TableObj.ToDictionary(t => t.Key, t=> t.TimeStamp);

Maximum length for MD5 input/output

Append Length

A 64-bit representation of b (the length of the message before the padding bits were added) is appended to the result of the previous step. In the unlikely event that b is greater than 2^64, then only the low-order 64 bits of b are used.

  • The hash is always 128 bits. If you encode it as a hexdecimal string you can encode 4 bits per character, giving 32 characters.
  • MD5 is not encryption. You cannot in general "decrypt" an MD5 hash to get the original string.

See more here.

HTTP Status 504

CheckUpDown has a nice explanation of the 504 error:

A server (not necessarily a Web server) is acting as a gateway or proxy to fulfil the request by the client (e.g. your Web browser or our CheckUpDown robot) to access the requested URL. This server did not receive a timely response from an upstream server it accessed to deal with your HTTP request.

This usually means that the upstream server is down (no response to the gateway/proxy), rather than that the upstream server and the gateway/proxy do not agree on the protocol for exchanging data.

This problem is entirely due to slow IP communication between back-end computers, possibly including the Web server. Only the people who set up the network at the site which hosts the Web server can fix this problem.

Crystal Reports - Adding a parameter to a 'Command' query

When you are in the Command, click Create to create a new parameter; call it project_name. Once you've created it, double click its name to add it to the command's text. You query should resemble:

SELECT Projecttname, ReleaseDate, TaskName
WHERE Project_Name LIKE {?project_name} + '*'
AND ReleaseDate >= getdate() --assumes sql server

If desired, link the main report to the subreport on this ({?project_name}) field. If you don't establish a link between the main and subreport, CR will prompt you for the subreport's parameter.

In versions prior to 2008, a command's parameter was only allowed to be a scalar value.

Change string color with NSAttributedString?

There is no need for using NSAttributedString. All you need is a simple label with the proper textColor. Plus this simple solution will work with all versions of iOS, not just iOS 6.

But if you needlessly wish to use NSAttributedString, you can do something like this:

UIColor *color = [UIColor redColor]; // select needed color
NSString *string = ... // the string to colorize
NSDictionary *attrs = @{ NSForegroundColorAttributeName : color };
NSAttributedString *attrStr = [[NSAttributedString alloc] initWithString:string attributes:attrs];
self.scanLabel.attributedText = attrStr;

InputStream from a URL


final InputStream is = new URL("").openStream();

A fast way to delete all rows of a datatable at once

Here is a clean and modern way to do it using Entity FW and without SQL Injection or TSQL..

using (Entities dbe = new Entities())

Different color for each bar in a bar chart; ChartJS

If you know which colors you want, you can specify color properties in an array, like so:

    backgroundColor: [
    'rgba(75, 192, 192, 1)',
    borderColor: [
    'rgba(75, 192, 192, 1)',

How to write to a JSON file in the correct format

This question is for ruby 1.8 but it still comes on top when googling.

in ruby >= 1.9 you can use


other than what mentioned in other answers, in ruby 1.8 you can also use one liner form"public/temp.json","w"){ |f| f.write tempHash.to_json }

Changing the width of Bootstrap popover

You can change the template of your popover. Either with the data-template-attribute or with the relevant part in the function that sets it up:

    <script src=""></script>_x000D_
      <!-- Latest compiled and minified CSS -->_x000D_
      <link rel="stylesheet" href="" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">_x000D_
      <!-- Latest compiled and minified JavaScript -->_x000D_
      <script src="" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa" crossorigin="anonymous"></script>_x000D_
    <span class="text-green" data-toggle="popover" data-placement="right" data-template="<div class=&quot;popover fade top in&quot; style=&quot;max-width:none;&quot; role=&quot;tooltip&quot;><div class=&quot;arrow&quot;></div><h3 class=&quot;popover-title&quot;></h3><div class=&quot;popover-content&quot;></div></div>" data-trigger="manual" data-original-title="Some Title" data-content="<div>Some really long text and stuff. Some really long text and stuff. Some really long text and stuff. Some really long text and stuff.</div>" data-html="true" onclick="$(this).popover('show');">clickme</span>_x000D_

How do I check if a number is positive or negative in C#?


public static class AwesomeExtensions
    public static bool IsPositive(this int number)
        return number > 0;

    public static bool IsNegative(this int number)
        return number < 0;

    public static bool IsZero(this int number)
        return number == 0;

    public static bool IsAwesome(this int number)
        return IsNegative(number) && IsPositive(number) && IsZero(number);

How do I programmatically click on an element in JavaScript? is a standard method outlined by the W3C DOM specification. Mozilla's Gecko/Firefox follows the standard and only allows this method to be called on INPUT elements.

Module AppRegistry is not registered callable module (calling runApplication)

you just need to close the metro server by control + c and then restart by npm start

Note: If that too doesn't work then just restart your computer, it'll definitely work then.

Github Windows 'Failed to sync this branch'

I had the same problem. It happened to me because of some conflicting changes. I removed the local repository of my project from my desktop and then cloned it again from the github website (using clone option in my account), the error was gone.

How to break long string to multiple lines

If the long string to multiple lines confuses you. Then you may install mz-tools addin which is a freeware and has the utility which splits the line for you.

Download Mz-tools

If your string looks like below

SqlQueryString = "Insert into Employee values(" & txtEmployeeNo.Value & "','" & txtContractStartDate.Value & "','" & txtSeatNo.Value & "','" & txtFloor.Value & "','" & txtLeaves.Value & "')"

Simply select the string > right click on VBA IDE > Select MZ-tools > Split Lines

enter image description here

Install psycopg2 on Ubuntu

This works for me in Ubuntu 12.04 and 15.10

if pip not installed:

sudo apt-get install python-pip

and then:

sudo apt-get update
sudo apt-get install libpq-dev python-dev
sudo pip install psycopg2