Programs & Examples On #Code analysis

Code Analysis is the process of analyzing the code of the application to discover, review, validate or verify certain properties of the application. This is useful during the process of development and for testing the application before it is put in production mode, especially for checking the security related aspects.

How do I fix PyDev "Undefined variable from import" errors?

in preferences --> PyDev --> PyLint under arguments to pass to PyLint add this line:


you will need to do this for each generated . I found this by googling, but I lost the reference.

What static analysis tools are available for C#?

Optimyth Software has just launched a static analysis service in the cloud Just securely upload your code run the analysis and get the results. No hassles.

It supports several languages including C# more info can be found at

How can I perform static code analysis in PHP?

There is a tool for static code analysis called PHP Analyzer. PHP Analyzer is now a deprecated project, but you still can access it on the legacy branch.

Among many types of static analysis it also provides basic auto-fixing functionality, see the documentation.

C# compiler error: "not all code paths return a value"

Or Simply Do this Stuff:

public static bool isTwenty(int num)
   for(int j = 1; j <= 20; j++)
      if(num % j != 0)
          return false;
      else if(num % j == 0 && num == 20)
          return true;
          return false; 


Displaying all table names in php from MySQL database

The square brackets in your code are used in the mysql documentation to indicate groups of optional parameters. They should not be in the actual query.

The only command you actually need is:

show tables;

If you want tables from a specific database, let's say the database "books", then it would be

show tables from books;

You only need the LIKE part if you want to find tables whose names match a certain pattern. e.g.,

show tables from books like '%book%';

would show you the names of tables that have "book" somewhere in the name.

Furthermore, just running the "show tables" query will not produce any output that you can see. SQL answers the query and then passes it to PHP, but you need to tell PHP to echo it to the page.

Since it sounds like you're very new to SQL, I'd recommend running the mysql client from the command line (or using phpmyadmin, if it's installed on your system). That way you can see the results of various queries without having to go through PHP's functions for sending queries and receiving results.

If you have to use PHP, here's a very simple demonstration. Try this code after connecting to your database:

$result = mysql_query("show tables"); // run the query and assign the result to $result
while($table = mysql_fetch_array($result)) { // go through each row that was returned in $result
    echo($table[0] . "<BR>");    // print the table that was returned on that row.

Is there a Boolean data type in Microsoft SQL Server like there is in MySQL?

Use the Bit datatype. It has values 1 and 0 when dealing with it in native T-SQL

How do I return a proper success/error message for JQuery .ajax() using PHP?

You need to provide the right content type if you're using JSON dataType. Before echo-ing the json, put the correct header.

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

Additional fix, you should check whether the query succeed or not.

    $response_array['status'] = 'success';  
}else {
    $response_array['status'] = 'error';  

On the client side:

success: function(data) {
    if(data.status == 'success'){
        alert("Thank you for subscribing!");
    }else if(data.status == 'error'){
        alert("Error on query!");

Hope it helps.

javascript functions to show and hide divs

You can zip the two with something like this [like jQuery does]:

function toggleMyDiv() {
 if (document.getElementById("myDiv").style.display=="block"){

..and use the same function in the two buttons - or generally in the page for both functions.

How do you Sort a DataTable given column and direction?

Actually got the same problem. For me worked this easy way:

Adding the data to a Datatable and sort it:

dt.DefaultView.Sort = "columnname";
dt = dt.DefaultView.ToTable();

How to convert String into Hashmap in java

This is one solution. If you want to make it more generic, you can use the StringUtils library.

String value = "{first_name = naresh,last_name = kumar,gender = male}";
value = value.substring(1, value.length()-1);           //remove curly brackets
String[] keyValuePairs = value.split(",");              //split the string to creat key-value pairs
Map<String,String> map = new HashMap<>();               

for(String pair : keyValuePairs)                        //iterate over the pairs
    String[] entry = pair.split("=");                   //split the pairs to get key and value 
    map.put(entry[0].trim(), entry[1].trim());          //add them to the hashmap and trim whitespaces

For example you can switch

 value = value.substring(1, value.length()-1);


 value = StringUtils.substringBetween(value, "{", "}");

if you are using StringUtils which is contained in apache.commons.lang package.

Entity Framework: One Database, Multiple DbContexts. Is this a bad idea?

I want to share a case, where I think the possibility of having multiple DBContexts in the same database makes good sense.

I have a solution with two database. One is for domain data except user information. The other is solely for user information. This division is primarily driven by the EU General Data Protection Regulation. By having two databases, I can freely move the domain data around (e.g. from Azure to my development environment) as long as the user data stays in one secure place.

Now for the user database I have implemented two schemas through EF. One is the default one provided by the AspNet Identity framework. The other is our own implementing anything else user related. I prefer this solution over extending the ApsNet schema, because I can easily handle future changes to AspNet Identity and at the same time the separation makes it clear to the programmers, that "our own user information" goes in the specific user schema we have defined.

Converting a Java Keystore into PEM Format

Well, OpenSSL should do it handily from a #12 file:

openssl pkcs12 -in pkcs-12-certificate-file -out pem-certificate-file
openssl pkcs12 -in pkcs-12-certificate-and-key-file -out pem-certificate-and-key-file

Maybe more details on what the error/failure is?

WPF Add a Border to a TextBlock

No, you need to wrap your TextBlock in a Border. Example:

<Border BorderThickness="1" BorderBrush="Black">
    <TextBlock ... />

Of course, you can set these properties (BorderThickness, BorderBrush) through styles as well:

<Style x:Key="notCalledBorder" TargetType="{x:Type Border}">
    <Setter Property="BorderThickness" Value="1" />
    <Setter Property="BorderBrush" Value="Black" />

<Border Style="{StaticResource notCalledBorder}">
    <TextBlock ... />

Get the first element of an array

Two solutions for you.

Solution 1 - Just use the key. You have not said that you can not use it. :)

    // Get the first element of this array.
    $array = array( 4 => 'apple', 7 => 'orange', 13 => 'plum' );

    // Gets the first element by key
    $result = $array[4];

    // Expected result: string apple
    assert('$result === "apple" /* Expected result: string apple. */');

Solution 2 - array_flip() + key()

    // Get first element of this array. Expected result: string apple
    $array = array( 4 => 'apple', 7 => 'orange', 13 => 'plum' );

    // Turn values to keys
    $array = array_flip($array);

    // You might thrown a reset in just to make sure
    // that the array pointer is at the first element.
    // Also, reset returns the first element.
    // reset($myArray);

    // Return the first key
    $firstKey = key($array);

    assert('$firstKey === "apple" /* Expected result: string apple. */');

Solution 3 - array_keys()

echo $array[array_keys($array)[0]];

Can't change table design in SQL Server 2008

The answer is on the MSDN site:

The Save (Not Permitted) dialog box warns you that saving changes is not permitted because the changes you have made require the listed tables to be dropped and re-created.

The following actions might require a table to be re-created:

  • Adding a new column to the middle of the table
  • Dropping a column
  • Changing column nullability
  • Changing the order of the columns
  • Changing the data type of a column


Additional useful informations from here:

To change the Prevent saving changes that require the table re-creation option, follow these steps:

  1. Open SQL Server Management Studio (SSMS).
  2. On the Tools menu, click Options.
  3. In the navigation pane of the Options window, click Designers.
  4. Select or clear the Prevent saving changes that require the table re-creation check box, and then click OK.

Note If you disable this option, you are not warned when you save the table that the changes that you made have changed the metadata structure of the table. In this case, data loss may occur when you save the table.

Risk of turning off the "Prevent saving changes that require table re-creation" option

Although turning off this option can help you avoid re-creating a table, it can also lead to changes being lost. For example, suppose that you enable the Change Tracking feature in SQL Server 2008 to track changes to the table. When you perform an operation that causes the table to be re-created, you receive the error message that is mentioned in the "Symptoms" section. However, if you turn off this option, the existing change tracking information is deleted when the table is re-created. Therefore, we recommend that you do not work around this problem by turning off the option.

Settings, screen shot

How to re-create database for Entity Framework?

Just want to add to the excellent answer of @Lin:

5) B. If you don't have SQL Management Studio, go to "SQL Server Object Explorer". If you cannot see your project db in the localdb "SQL Server Object Explorer", then click on "Add SQL server" button to add it to the list manually. Then you can delete the db from the list.

How to lock orientation of one view controller to portrait mode only in Swift

Actual tested Solution for this.In my example I need my whole app should be in portrait mode, but only one screen's orientation should be in landscape mode. Make a Portrait orientation for app , by check only portrait mode

Code in AppDelegate as above answers described.

var orientationLock = UIInterfaceOrientationMask.all

func application(_ application: UIApplication, supportedInterfaceOrientationsFor window: UIWindow?) -> UIInterfaceOrientationMask 
  return self.orientationLock
struct AppUtility {  

static func lockOrientation(_ orientation: UIInterfaceOrientationMask) {
    if let delegate = UIApplication.shared.delegate as? AppDelegate {
        delegate.orientationLock = orientation
static func lockOrientation(_ orientation: UIInterfaceOrientationMask, andRotateTo rotateOrientation:UIInterfaceOrientation) {
UIDevice.current.setValue(rotateOrientation.rawValue, forKey: "orientation")

Then write down this code before your landscape orientation viewcontroller will be presented/push.

override func viewWillAppear(_ animated: Bool) {  
AppDelegate.AppUtility.lockOrientation(UIInterfaceOrientationMask.portrait, andRotateTo: UIInterfaceOrientation.portrait)

Then write down this code in actual viewcontroller(For landscape view)

override func viewWillAppear(_ animated: Bool) {  
AppDelegate.AppUtility.lockOrientation(UIInterfaceOrientationMask.landscape, andRotateTo: UIInterfaceOrientation.landscape)

Zoom to fit: PDF Embedded in HTML

Use iframe tag do display pdf file with zoom fit

<iframe src="filename.pdf" width="" height="" border="0"></iframe>

How to prevent column break within an element?

The accepted answer is now two years old and things appear to have changed.

This article explains the use of the column-break-inside property. I can't say how or why this differs from break-inside, because only the latter appears to be documented in the W3 spec. However, the Chrome and Firefox support the following:

li {

HTML input time in 24 format

<!DOCTYPE html>_x000D_
        Time: <input type="time" id="myTime" value="16:32:55">_x000D_
 <p>Click the button to get the time of the time field.</p>_x000D_
 <button onclick="myFunction()">Try it</button>_x000D_
 <p id="demo"></p>_x000D_
     function myFunction() {_x000D_
         var x = document.getElementById("myTime").value;_x000D_
         document.getElementById("demo").innerHTML = x;_x000D_

I found that by setting value field (not just what is given below) time input will be internally converted into the 24hr format.

Regex Explanation ^.*$

  • ^ matches position just before the first character of the string
  • $ matches position just after the last character of the string
  • . matches a single character. Does not matter what character it is, except newline
  • * matches preceding match zero or more times

So, ^.*$ means - match, from beginning to end, any character that appears zero or more times. Basically, that means - match everything from start to end of the string. This regex pattern is not very useful.

Let's take a regex pattern that may be a bit useful. Let's say I have two strings The bat of Matt Jones and Matthew's last name is Jones. The pattern ^Matt.*Jones$ will match Matthew's last name is Jones. Why? The pattern says - the string should start with Matt and end with Jones and there can be zero or more characters (any characters) in between them.

Feel free to use an online tool like to test out regex patterns and strings.

How do I create a folder in a GitHub repository?

Create a new file, and then on the filename use slash. For example


JavaScript equivalent of PHP’s die

you can try with :

return 0;

that work in case of stop process.

python selenium click on button

open a website and click on button to download the file and even i want to close the pop up if it comes using python selenium

from selenium import webdriver
from import By
from import WebDriverWait
from import expected_conditions as EC
import time
from import Options 

#For Mac - If you use windows change the chromedriver location
chrome_path = '/usr/local/bin/chromedriver'
driver = webdriver.Chrome(chrome_path)

chrome_options = webdriver.ChromeOptions()


# driver.get("")
# tabName = driver.find_element_by_link_text("Investment Adviser Data")


# report1 = driver.find_element_by_xpath("//div[@class='compilation-container ng-scope layout-column flex']//div[1]//div[1]//div[1]//div[2]//button[1]")

report1 = driver.find_element_by_xpath("//button[@analytics-label='IAPD - SEC Investment Adviser Report (GZIP)']")

# print(report1)



Temporarily switch working copy to a specific Git commit

First, use git log to see the log, pick the commit you want, note down the sha1 hash that is used to identify the commit. Next, run git checkout hash. After you are done, git checkout original_branch. This has the advantage of not moving the HEAD, it simply switches the working copy to a specific commit.

How do you rename a Git tag?

You can also rename remote tags without checking them out, by duplicate the old tag/branch to a new name and delete the old one, in a single git push command.

Remote tag rename / Remote branch ? tag conversion: (Notice: :refs/tags/)

git push <remote_name> <old_branch_or_tag>:refs/tags/<new_tag> :<old_branch_or_tag>

Remote branch rename / Remote tag ? branch conversion: (Notice: :refs/heads/)

git push <remote_name> <old_branch_or_tag>:refs/heads/<new_branch> :<old_branch_or_tag>

Output renaming a remote tag:

D:\git.repo>git push gitlab App%2012.1%20v12.1.0.23:refs/tags/App_12.1_v12.1.0.23 :App%2012.1%20v12.1.0.23

Total 0 (delta 0), reused 0 (delta 0)
To https://gitlab.server/project/repository.git
 - [deleted]               App%2012.1%20v12.1.0.23
 * [new tag]               App%2012.1%20v12.1.0.23 -> App_12.1_v12.1.0.23

How to pass parameter to a promise function

Try this:

function someFunction(username, password) {
      return new Promise((resolve, reject) => {
        // Do something with the params username and password...
        if ( /* everything turned out fine */ ) {
          resolve("Stuff worked!");
        } else {
          reject(Error("It didn't work!"));
    someFunction(username, password)
      .then((result) => {
        // Do something...
      .catch((err) => {
        // Handle the error...

Why is the GETDATE() an invalid identifier

getdate() for MS-SQL, sysdate for Oracle server

MySQL: ignore errors when importing?

Use the --force (-f) flag on your mysql import. Rather than stopping on the offending statement, MySQL will continue and just log the errors to the console.

For example:

mysql -u userName -p -f -D dbName < script.sql

How do I find my host and username on mysql?

Default user for MySQL is "root", and server "localhost".

Why isn't my Pandas 'apply' function referencing multiple columns working?

I have given the comparison of all three discussed above.

Using values

%timeit df['value'] = df['a'].values % df['c'].values

139 µs ± 1.91 µs per loop (mean ± std. dev. of 7 runs, 10000 loops each)

Without values

%timeit df['value'] = df['a']%df['c'] 

216 µs ± 1.86 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)

Apply function

%timeit df['Value'] = df.apply(lambda row: row['a']%row['c'], axis=1)

474 µs ± 5.07 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)


Here's something you can try without an order by but I think it requires that each row is unique. N is the number of rows you want, L is the number of rows in the table.

select * from tbl_name except select top L-N * from tbl_name

As noted before, which rows are returned is undefined.

EDIT: this is actually dog slow. Of no value really.

How do I send an HTML email?

Since JavaMail version 1.4, there is an overload of setText method that accepts the subtype.

// Passing null for second argument in order for the method to determine
// the actual charset on-the fly.
// If you know the charset, pass it. "utf-8" should be fine
msg.setText( message, null, "html" );

IE11 prevents ActiveX from running

Here's how I got it working:

  1. Include your URL in IE Trusted Sites

  2. run gpedit.msc (as Admin) and enable the following setting:

gpedit->Local->Computer->Windows Comp->ActiveX Installer->ActiveX installation policy for sites in Trusted Zones

Enabled + Silently,Silently,Prompt

  1. Run gpupdate

  2. Relaunch your Browser

NOTES: Windows 10 EDGE don't have trusted sites, so you have to use IE 11. Lots of folk moaning about that!

JSON to pandas DataFrame

You could first import your json data in a Python dictionnary :

data = json.loads(elevations)

Then modify data on the fly :

for result in data['results']:
    del result[u'location']

Rebuild json string :

elevations = json.dumps(data)

Finally :


You can, also, probably avoid to dump data back to a string, I assume Panda can directly create a DataFrame from a dictionnary (I haven't used it since a long time :p)

C++ String array sorting

int z = sizeof(name)/sizeof(name[0]); //Get the array size

sort(name,name+z); //Use the start and end like this

for(int y = 0; y < z; y++){
    cout << name[y] << endl;

Edit :

Considering all "proper" naming conventions (as per comments) :

int N = sizeof(name)/sizeof(name[0]); //Get the array size

sort(name,name+N); //Use the start and end like this

for(int i = 0; i < N; i++){
    cout << name[i] << endl;

Note: Dietmar Kühl's answer is best in all respect, std::begin() & std::end() should be used for std::sort like functions with C++11, else they can be defined.

How do I install Eclipse with C++ in Ubuntu 12.10 (Quantal Quetzal)?

There is a package called eclipse-cdt in the Ubuntu 12.10 repositories, this is what you want. If you haven't got g++ already, you need to install that as well, so all you need is:

sudo apt-get install eclipse eclipse-cdt g++

Whether you messed up your system with your previous installation attempts depends heavily on how you did it. If you did it the safe way for trying out new packages not from repositories (i.e., only installed in your home folder, no sudos blindly copied from installation manuals...) you're definitely fine. Otherwise, you may well have thousands of stray files all over your file system now. In that case, run all uninstall scripts you can find for the things you installed, then install using apt-get and hope for the best.

Presenting modal in iOS 13 fullscreen

If you are using a UINavigationController and embed a ViewController as a root view controller, then also you would rise up with same issue. Use following code to overcome.

let vc = UIViewController()
let navController = UINavigationController(rootViewController: vc)
navController.modalPresentationStyle = .fullScreen

Keras, how do I predict after I trained a model?

I trained a neural network in Keras to perform non linear regression on some data. This is some part of my code for testing on new data using previously saved model configuration and weights.

fname = r"C:\Users\tauseef\Desktop\keras\tutorials\BestWeights.hdf5"
modelConfig = joblib.load('modelConfig.pkl')
recreatedModel = Sequential.from_config(modelConfig)
unseenTestData = np.genfromtxt(r"C:\Users\tauseef\Desktop\keras\arrayOf100Rows257Columns.txt",delimiter=" ")
X_test = unseenTestData
standard_scalerX = StandardScaler()
X_test_std = standard_scalerX.transform(X_test)
X_test_std = X_test_std.astype('float32')
unseenData_predictions = recreatedModel.predict(X_test_std)

Is it possible to forward-declare a function in Python?

One way is to create a handler function. Define the handler early on, and put the handler below all the methods you need to call.

Then when you invoke the handler method to call your functions, they will always be available.

The handler could take an argument nameOfMethodToCall. Then uses a bunch of if statements to call the right method.

This would solve your issue.

def foo():
    #take input
    nextAction=input('What would you like to do next?:')
    return nextAction

def bar():
    nextAction=input('What would you like to do next?:')
    return nextAction

def handler(action):
        nextAction = foo()
        nextAction = bar()
        print("You entered invalid input, defaulting to bar")
        nextAction = "bar"
    return nextAction

nextAction=input('What would you like to do next?:')

while 1:
    nextAction = handler(nextAction)

Upload failed You need to use a different version code for your APK because you already have one with version code 2

I received the same error while uploading a flutter app to playstore simply change the version code in pubspec.yaml worked for me. may be try changing the version code e.g from +1 to +2 and then rebuild the apk using

flutter build apk --split-per-abi 

and upload all the apk's to the playstore for your users. Next time when you want to push an update make sure to update the version code to +3 and so on.

Note: that the version code and version name are different you can see that in android/ file. e.g version: 1.0.0+2

version is 1.0.0 and verison code is +2

How can I compare a date and a datetime in Python?

I am trying to compare date which are in string format like '20110930'

benchMark = datetime.datetime.strptime('20110701', "%Y%m%d") 

actualDate = datetime.datetime.strptime('20110930', "%Y%m%d")

if <
    print True

Custom Adapter for List View

A more compact example of a custom adapter (using list array as my data):

class MyAdapter extends ArrayAdapter<Object> {
    public ArrayAdapter(Context context, List<MyObject> objectList) {
        super(context, R.layout.my_list_item,, objectList.toArray());

    public View getView(int position, View convertView, ViewGroup parent) {
        View row = super.getView(position, convertView, parent);
        TextView title = (TextView) row.findViewById(;
        ImageView icon = (ImageView) row.findViewById(;
        MyObject obj = (MyObject) getItem(position);
        icon.setImageBitmap( ... );
        return row;

And this is how to use it:

List<MyObject> objectList = ...
MyAdapter adapter = new MyAdapter(this.getActivity(), objectList);

Stop/Close webcam stream which is opened by navigator.mediaDevices.getUserMedia

Don't use stream.stop(), it's deprecated

MediaStream Deprecations

Use stream.getTracks().forEach(track => track.stop())

Grant Select on a view not base table when base table is in a different database

I also had this problem. I used information from link, mentioned above, and found quick solution. If you have different schema, lets say test, and create user utest, owner of schema test and among views in schema test you have view vTestView, based on tables from schema dbo, while selecting from it you'll get error mentioned above - no access to base objects. It was enough for me to execute statement


which means that I change an ownership of vTextView from schema it belongs to (test) to database user dbo, owner of schema dbo. After that without any other permissions required user utest will be able to access data from test.vTestView

How to amend older Git commit?

I prepared my commit that I wanted to amend with an older one and was surprised to see that rebase -i complained that I have uncommitted changes. But I didn't want to make my changes again specifying edit option of the older commit. So the solution was pretty easy and straightforward:

  1. prepare your update to older commit, add it and commit
  2. git rebase -i <commit you want to amend>^ - notice the ^ so you see the said commit in the text editor
  3. you will get sometihng like this:

    pick 8c83e24 use substitution instead of separate subsystems file to avoid jgroups.xml and jgroups-e2.xml going out of sync
    pick 799ce28 generate ec2 configuration out of subsystems-ha.xml and subsystems-full-ha.xml to avoid discrepancies
    pick e23d23a fix indentation of jgroups.xml
  4. now to combine e23d23a with 8c83e24 you can change line order and use squash like this:

    pick 8c83e24 use substitution instead of separate subsystems file to avoid jgroups.xml and jgroups-e2.xml going out of sync    
    squash e23d23a fix indentation of jgroups.xml
    pick 799ce28 generate ec2 configuration out of subsystems-ha.xml and subsystems-full-ha.xml to avoid discrepancies
  5. write and exit the file, you will be present with an editor to merge the commit messages. Do so and save/exit the text document

  6. You are done, your commits are amended

credit goes to: There's also other useful demonstrated git magic.

How to see local history changes in Visual Studio Code?

Basic Functionality

  • Automatically saved local edit history is available with the Local History extension.
  • Manually saved local edit history is available with the Checkpoints extension (this is the IntelliJ equivalent to adding tags to the local history).

Advanced Functionality

  • None of the extensions mentioned above support edit history when a file is moved or renamed.
  • The extensions above only support edit history. They do not support move/delete history, for example, like IntelliJ does.

Open Request

If you'd like to see this feature added natively, along with all of the advanced functionality, I'd suggest upvoting the open GitHub issue here.

Understanding dict.copy() - shallow or deep?

By "shallow copying" it means the content of the dictionary is not copied by value, but just creating a new reference.

>>> a = {1: [1,2,3]}
>>> b = a.copy()
>>> a, b
({1: [1, 2, 3]}, {1: [1, 2, 3]})
>>> a[1].append(4)
>>> a, b
({1: [1, 2, 3, 4]}, {1: [1, 2, 3, 4]})

In contrast, a deep copy will copy all contents by value.

>>> import copy
>>> c = copy.deepcopy(a)
>>> a, c
({1: [1, 2, 3, 4]}, {1: [1, 2, 3, 4]})
>>> a[1].append(5)
>>> a, c
({1: [1, 2, 3, 4, 5]}, {1: [1, 2, 3, 4]})


  1. b = a: Reference assignment, Make a and b points to the same object.

    Illustration of 'a = b': 'a' and 'b' both point to '{1: L}', 'L' points to '[1, 2, 3]'.

  2. b = a.copy(): Shallow copying, a and b will become two isolated objects, but their contents still share the same reference

    Illustration of 'b = a.copy()': 'a' points to '{1: L}', 'b' points to '{1: M}', 'L' and 'M' both point to '[1, 2, 3]'.

  3. b = copy.deepcopy(a): Deep copying, a and b's structure and content become completely isolated.

    Illustration of 'b = copy.deepcopy(a)': 'a' points to '{1: L}', 'L' points to '[1, 2, 3]'; 'b' points to '{1: M}', 'M' points to a different instance of '[1, 2, 3]'.

Assigning more than one class for one event

You can select multiple classes at once with jQuery like this:

$('.tag, .tag2').click(function() {
    var $this = $(this);
    if ($this.hasClass('tag')) {
        // do stuff
    } else {
        // do other stuff

Giving a 2nd parameter to the $() function, scopes the selector so $('.tag', '.tag2') looks for tag within elements with the class tag2.

How to position the div popup dialog to the center of browser screen?

I write a code in jquery. It isnt seen an easy way. But i hope it is useful for you.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">
<style type="text/css">

    border: 4px solid #6b6a63;
    width: 800px;
    border-radius :7px;
    margin : auto;
    padding : 20px;


<div id="popup" class="popup">
some lengthy text<br>
some lengthy text<br>
some lengthy text<br>
some lengthy text<br>
some lengthy text<br>
some lengthy text<br>
some lengthy text<br>
some lengthy text<br>

<script type="text/javascript" src=""></script>
    var popup_height = document.getElementById('popup').offsetHeight;
    var popup_width = document.getElementById('popup').offsetWidth;

How to delete from multiple tables in MySQL?

The syntax looks right to me ... try to change it to use INNER JOIN ...

Have a look at this.

How to convert Java String to JSON Object

@Nishit, JSONObject does not natively understand how to parse through a StringBuilder; instead you appear to be using the JSONObject(java.lang.Object bean) constructor to create the JSONObject, however passing it a StringBuilder.

See this link for more information on that particular constructor.

When a constructor calls for a java.lang.Object class, more than likely it's really telling you that you're expected to create your own class (since all Classes ultimately extend java.lang.Object) and that it will interface with that class in a specific way, albeit normally it will call for an interface instead (hence the name) OR it can accept any class and interface with it "abstractly" such as calling .toString() on it. Bottom line, you typically can't just pass it any class and expect it to work.

At any rate, this particular constructor is explained as such:

Construct a JSONObject from an Object using bean getters. It reflects on all of the public methods of the object. For each of the methods with no parameters and a name starting with "get" or "is" followed by an uppercase letter, the method is invoked, and a key and the value returned from the getter method are put into the new JSONObject. The key is formed by removing the "get" or "is" prefix. If the second remaining character is not upper case, then the first character is converted to lower case. For example, if an object has a method named "getName", and if the result of calling object.getName() is "Larry Fine", then the JSONObject will contain "name": "Larry Fine".

So, what this means is that it's expecting you to create your own class that implements get or is methods (i.e.

public String getName() {...}


public boolean isValid() {...}

So, to solve your problem, if you really want that higher level of control and want to do some manipulation (e.g. modify some values, etc.) but still use StringBuilder to dynamically generate the code, you can create a class that extends the StringBuilder class so that you can use the append feature, but implement get/is methods to allow JSONObject to pull the data out of it, however this is likely not what you want/need and depending on the JSON, you might spend a lot of time and energy creating the private fields and get/is methods (or use an IDE to do it for you) or it might be all for naught if you don't necessarily know the breakdown of the JSON string.

So, you can very simply call toString() on the StringBuilder which will provide a String representation of the StringBuilder instance and passing that to the JSONObject constructor, such as below:

StringBuilder jsonString = new StringBuilder();
while((readAPIResponse = br.readLine()) != null){
JSONObject jsonObj = new JSONObject(jsonString.toString());

Stick button to right side of div

Another solution: change margins. Depending on the siblings of the button, display should be modified.

button {
    display:      block;
    margin-left:  auto;
    margin-right: 0;

XXHDPI and XXXHDPI dimensions in dp for images and icons in android

try like this. hope it works

drawable-sw720dp-xxhdpi and values-sw720dp-xxhdpi

drawable-sw720dp-xxxhdpi and values-sw720dp-xxxhdpi

link might destroy so pasted ans

reference Android xxx-hdpi real devices

xxxhdpi was only introduced because of the way that launcher icons are scaled on the nexus 5's launcher Because the nexus 5's default launcher uses bigger icons, xxxhdpi was introduced so that icons would still look good on the nexus 5's launcher.

also check these links

Different resolution support android

Application Skeleton to support multiple screen

Is there a list of screen resolutions for all Android based phones and tablets?

"Active Directory Users and Computers" MMC snap-in for Windows 7?

I'm not allowed to use Turn Windows features on or off, but running all of these commands in an elevated command prompt (Run as Administrator) finally got Active Directory Users and Computers to show up under Administrative Tools on the start menu:

dism /online /enable-feature /featurename:RemoteServerAdministrationTools
dism /online /enable-feature /featurename:RemoteServerAdministrationTools-Roles
dism /online /enable-feature /featurename:RemoteServerAdministrationTools-Roles-AD
dism /online /enable-feature /featurename:RemoteServerAdministrationTools-Roles-AD-DS
dism /online /enable-feature /featurename:RemoteServerAdministrationTools-Roles-AD-DS-SnapIns
dism /online /enable-feature /featurename:RemoteServerAdministrationTools-Roles-AD-DS-AdministrativeCenter
dism /online /enable-feature /featurename:RemoteServerAdministrationTools-Roles-AD-DS-NIS
dism /online /enable-feature /featurename:RemoteServerAdministrationTools-Roles-AD-LDS
dism /online /enable-feature /featurename:RemoteServerAdministrationTools-Roles-AD-Powershell

I had downloaded and installed the RSAT (Windows 7 Link, Windows Vista Link) before running these commands.

It's quite likely that this is more than you features than you actually need, but at least it's not too few.

What's the difference between HEAD^ and HEAD~ in Git?

If you're wondering whether to type HEAD^ or HEAD~ in your command, just use either:

They're both names for the same commit - the first parent of the current commit.

Likewise with master~ and master^ - both names for the first parent of master.

In the same way as 2 + 2 and 2 x 2 are both 4 - they're different ways of getting there, but the answer is the same.

This answers the question: What's the difference between HEAD^ and HEAD~ in Git?

If you just did a merge (so your current commit has more than one parent), or you're still interested in how the caret and tilde work, see the other answers (which I won't duplicate here) for an in-depth explanation, as well as how to use them repeatedly (e.g.HEAD~~~), or with numbers (e.g.HEAD^2). Otherwise, I hope this answer saves you some time.

How to set header and options in axios?

You can send a get request with Headers (for authentication with jwt for example):

axios.get('', {
 headers: {
   Authorization: 'Bearer ' + token //the token is a variable which holds the token

Also you can send a post request.'', {
 email: varEmail, //varEmail is a variable which holds the email
 password: varPassword
  headers: {
    Authorization: 'Bearer ' + varToken

My way of doing it,is to set a request like this:

  method: 'post', //you can set what request you want to be
  url: '',
  data: {id: varID},
  headers: {
    Authorization: 'Bearer ' + varToken

How to check date of last change in stored procedure or function in SQL server

In latest version(2012 or more) we can get modified stored procedure detail by using this query

SELECT create_date, modify_date, name FROM sys.procedures 
ORDER BY modify_date DESC

AngularJS error: 'argument 'FirstCtrl' is not a function, got undefined'

I just did this tutorial and followed @gion_13 answer. Still did not work. Solved it by making my ng-app name in the index identical to the one in my js file. Exactly identical, even the quotes. So:

<div ng-app="myapp">
    <div ng-controller="FirstCtrl">

and the js:

 angular.module("myapp", [])
.controller('FirstCtrl',function($scope) {
    $ {message:"hello"};

Weird how the ng-app has to be identical but the ng-controller doesn't.

How to have conditional elements and keep DRY with Facebook React's JSX?

As already mentioned in the answers, JSX presents you with two options

  • Ternary operator

    { this.state.price ? <div>{this.state.price}</div> : null }

  • Logical conjunction

    { this.state.price && <div>{this.state.price}</div> }

However, those don't work for price == 0.

JSX will render the false branch in the first case and in case of logical conjunction, nothing will be rendered. If the property may be 0, just use if statements outside of your JSX.

Embedding VLC plugin on HTML page

Unfortunately, IE and VLC don't really work right now... I found this on the vlc forums:

VLC included activex support up until version 0.8.6, I believe. At that time, you could
access a cab on the videolan and therefore 'automatic' installation into IE and Firefox
family browsers was fine. Thereafter support for activex seemed to stop; no cab, no
activex component.

VLC 1.0.* once again contains activex support, and that's brilliant. A good decision in
my opinion. What's lacking is a cab installer for the latest version.

This basically means that even if you found a way to make it work, anyone trying to view the video on your site in IE would have to download and install the entire VLC player program to have it work in IE, and users probably don't want to do that. I can't get your code to work in firefox or IE8 on my boyfriends computer, although I might not have been putting the video address in properly... I get some message about no video output...

I'll take a guess and say it probably works for you locally because you have VLC installed, but your server doesn't. Unfortunately you'll probably have to use Windows media player or something similar (Microsoft is great at forcing people to use their stuff!)

And if you're wondering, it appears that the reason there is no cab file is because of the cost of having an active-x control signed.

It's rather simple to have your page use VLC for firefox and chrome users, and Windows Media Player for IE users, if that would work for you.

How to open a new file in vim in a new window

I use this subtle alias:

alias vim='gnome-terminal -- vim'

-x is deprecated now. We need to use -- instead

An unhandled exception of type 'System.IO.FileNotFoundException' occurred in Unknown Module

First check - is the working directory the directory that the application is running in:

  • Right-click on your project and select Properties.
  • Click the Debug tab.
  • Confirm that the Working directory is either empty or equal to the bin\debug directory.

If this isn't the problem, then ask if Autodesk.Navisworks.Timeliner.dll is requiring another DLL which is not there. If Timeliner.dll is not a .NET assembly, you can determine the required imports using the command utility DUMPBIN.

dumpbin /imports Autodesk.Navisworks.Timeliner.dll

If it is a .NET assembly, there are a number of tools that can check dependencies.

Reflector has already been mentioned, and I use JustDecompile from Telerik.

Also see this question

Select mySQL based only on month and year

No one seems to be talking about performance so I tested the two most popular answers on a sample database from Mysql. The table has 2.8M rows with structure

CREATE TABLE `salaries` (
  `emp_no` int(11) NOT NULL,
  `salary` int(11) NOT NULL,
  `from_date` date NOT NULL,
  `to_date` date NOT NULL

ALTER TABLE `salaries`
  ADD PRIMARY KEY (`emp_no`,`from_date`);

Here are the tests performed and results

SELECT * FROM `salaries` WHERE YEAR(from_date) = 1992 AND MONTH(from_date) = 6
12339 results
11.5 ms 
12.1 ms
09.5 ms
07.5 ms
10.2 ms
10.2 ms Avg

SELECT * FROM `salaries` WHERE from_date BETWEEN '1992-06-01' AND '1992-06-31'
10.0 ms
10.8 ms
09.5 ms
09.0 ms
08.3 ms
09.5 ms Avg

SELECT * FROM `salaries` WHERE YEAR(to_date) = 1992 AND MONTH(to_date) = 6
10887 results
10.2 ms
11.7 ms
11.8 ms
12.4 ms
09.6 ms
11.1 ms Avg

SELECT * FROM `salaries` WHERE to_date BETWEEN '1992-06-01' AND '1992-06-31'
09.0 ms
07.5 ms
10.6 ms
11.7 ms
12.0 ms
10.2 ms Avg

My Conclusions

  1. BETWEEN was slightly better on both indexed and unindexed column.
  2. The unindexed column was marginally slower than the indexed column.

How to change the name of a Django app?

Follow these steps to change an app's name in Django:

  1. Rename the folder which is in your project root
  2. Change any references to your app in their dependencies, i.e. the app's, , '' , and files.
  3. Edit the database table django_content_type with the following command: UPDATE django_content_type SET app_label='<NewAppName>' WHERE app_label='<OldAppName>'
  4. Also if you have models, you will have to rename the model tables. For postgres use ALTER TABLE <oldAppName>_modelName RENAME TO <newAppName>_modelName. For mysql too I think it is the same (as mentioned by @null_radix)
  5. (For Django >= 1.7) Update the django_migrations table to avoid having your previous migrations re-run: UPDATE django_migrations SET app='<NewAppName>' WHERE app='<OldAppName>'. Note: there is some debate (in comments) if this step is required for Django 1.8+; If someone knows for sure please update here.
  6. If your 's Meta Class has app_name listed, make sure to rename that too (mentioned by @will).
  7. If you've namespaced your static or templates folders inside your app, you'll also need to rename those. For example, rename old_app/static/old_app to new_app/static/new_app.
  8. For renaming django models, you'll need to change entry in DB. For postgreSQL use UPDATE django_content_type SET name='<newModelName>' where name='<oldModelName>' AND app_label='<OldAppName>'

Meta point (If using virtualenv): Worth noting, if you are renaming the directory that contains your virtualenv, there will likely be several files in your env that contain an absolute path and will also need to be updated. If you are getting errors such as ImportError: No module named ... this might be the culprit. (thanks to @danyamachine for providing this).

Other references: you might also want to refer the below links for a more complete picture

  1. Renaming an app with Django and South
  2. How do I migrate a model out of one django app and into a new one?
  3. How to change the name of a Django app?
  4. Backwards migration with Django South
  5. Easiest way to rename a model using Django/South?
  6. Python code (thanks to A.Raouf) to automate the above steps (Untested code. You have been warned!)
  7. Python code (thanks to rafaponieman) to automate the above steps (Untested code. You have been warned!)

error TS2339: Property 'x' does not exist on type 'Y'

The correct fix is to add the property in the type definition as explained by @Nitzan Tomer. But also you can just define property as any, if you want to write code almost as in JavaScript:

arr.filter((item:any) => {
    return item.isSelected == true;

How to convert .pfx file to keystore with private key?

Justin(above) is accurate. However, keep in mind that depending on who you get the certificate from (intermediate CA, root CA involved or not) or how the pfx is created/exported, sometimes they could be missing the certificate chain. After Import, You would have a certificate of PrivateKeyEntry type, but with a chain of length of 1.

To fix this, there are several options. The easier option in my mind is to import and export the pfx file in IE(choosing the option of Including all the certificates in the chain). The import and export process of certificates in IE should be very easy and well documented elsewhere.

Once exported, import the keystore as Justin pointed above. Now, you would have a keystore with certificate of type PrivateKeyEntry and with a certificate chain length of more than 1.

Certain .Net based Web service clients error out(unable to establish trust relationship), if you don't do the above.

How to install a specific version of a ruby gem?

for Ruby 1.9+ use colon.

gem install sinatra:1.4.4 prawn:0.13.0

How to go up a level in the src path of a URL in HTML?

Use ../:

background-image: url('../images/bg.png');

You can use that as often as you want, e.g. ../../images/ or even at different positions, e.g. ../images/../images/../images/ (same as ../images/ of course)

What is the difference between single-quoted and double-quoted strings in PHP?

' Single quoted

The simplest way to specify a string is to enclose it in single quotes. Single quote is generally faster, and everything quoted inside treated as plain string.


echo 'Start with a simple string';
echo 'String\'s apostrophe';
echo 'String with a php variable'.$name;

" Double quoted

Use double quotes in PHP to avoid having to use the period to separate code (Note: Use curly braces {} to include variables if you do not want to use concatenation (.) operator) in string.


echo "Start with a simple string";
echo "String's apostrophe";
echo "String with a php variable {$name}";

Is there a performance benefit single quote vs double quote in PHP?

Yes. It is slightly faster to use single quotes.

PHP won't use additional processing to interpret what is inside the single quote. when you use double quotes PHP has to parse to check if there are any variables within the string.

How to serialize an Object into a list of URL query parameters?

Since I made such a big deal about a recursive function, here is my own version.

function objectParametize(obj, delimeter, q) {
    var str = new Array();
    if (!delimeter) delimeter = '&';
    for (var key in obj) {
        switch (typeof obj[key]) {
            case 'string':
            case 'number':
                str[str.length] = key + '=' + obj[key];
            case 'object':
                str[str.length] = objectParametize(obj[key], delimeter);
    return (q === true ? '?' : '') + str.join(delimeter);

javascript set cookie with expire time

document.cookie = "cookie_name=cookie_value; max-age=31536000; path=/";

Will set the value for a year.

AngularJS : automatically detect change in model

In views with {{}} and/or ng-model, Angular is setting up $watch()es for you behind the scenes.

By default $watch compares by reference. If you set the third parameter to $watch to true, Angular will instead "shallow" watch the object for changes. For arrays this means comparing the array items, for object maps this means watching the properties. So this should do what you want:

$scope.$watch('myModel', function() { ... }, true);

Update: Angular v1.2 added a new method for this, `$watchCollection():

$scope.$watchCollection('myModel', function() { ... });

Note that the word "shallow" is used to describe the comparison rather than "deep" because references are not followed -- e.g., if the watched object contains a property value that is a reference to another object, that reference is not followed to compare the other object.

How to set headers in http get request?

The Header field of the Request is public. You may do this :

req.Header.Set("name", "value")

JPA - Persisting a One to Many relationship

One way to do that is to set the cascade option on you "One" side of relationship:

class Employee {

   @OneToMany(cascade = {CascadeType.PERSIST})
   private Set<Vehicles> vehicles = new HashSet<Vehicles>();


by this, when you call

Employee savedEmployee = employeeDao.persistOrMerge(newEmployee);

it will save the vehicles too.

Is there a good Valgrind substitute for Windows?

I used Insure++ which does excellent job in finding c++ memory leaks/corruptions and many other bugs like uninitialized variables, pointer errors, strings etc., It also does visual "Code coverage" and run time memory usage etc.. which give more confident on your code.. You can try it for trail version..

SqlServer: Login failed for user

For Can not connect to the SQL Server. The original error is: Login failed for user 'username'. error, port requirements on MSSQL server side need to be fulfilled.

There are other ports beyond default port 1433 needed to be configured on Windows Firewall.

Disable HttpClient logging

For log4j, add the following to (in the application's source directory):

For logback, the following logback.xml will kill the noise:

    <logger name="org.apache" level="WARN" />
    <logger name="httpclient" level="WARN" /> 

How to read an http input stream

try this code

String data = "";
InputStream iStream = httpEntity.getContent();
BufferedReader br = new BufferedReader(new InputStreamReader(iStream, "utf8"));
StringBuffer sb = new StringBuffer();
String line = "";

while ((line = br.readLine()) != null) {

data = sb.toString();

Entity Framework select distinct name

Using lambda expression..

 var result = EFContext.TestAddresses.Select(m => m.Name).Distinct();

Another variation using where,

 var result = EFContext.TestAddresses
             .Where(a => a.age > 10)//if you have any condition
             .Select(m =>;

Another variation using sql like syntax

 var result = (from recordset
              in EFContext.TestAddresses
              .where(a => = 'vijaynagar')//if you have any condition
              .select new 

How to define Gradle's home in IDEA?

If you're using MacPorts, the path is


Print multiple arguments in Python

In Python 3.6, f-string is much cleaner.

In earlier version:

print("Total score for %s is %s. " % (name, score))

In Python 3.6:

print(f'Total score for {name} is {score}.')

will do.

It is more efficient and elegant.

How can I start pagenumbers, where the first section occurs in LaTex?

To suppress the page number on the first page, add \thispagestyle{empty} after the \maketitle command.

The second page of the document will then be numbered "2". If you want this page to be numbered "1", you can add \pagenumbering{arabic} after the \clearpage command, and this will reset the page number.

Here's a complete minimal example:


\title{My Report}
\author{My Name}




\section{First Section}


Convert a PHP script into a stand-alone windows executable

I had problems with most of the tools in other answers as they are all very outdated.

If you need a solution that will "just work", pack a bare-bones version of php with your project in a WinRar SFX archive, set it to extract everything to a temporary directory and execute php your_script.php.

To run a basic script, the only files required are php.exe and php5.dll (or php5ts.dll depending on version).

To add extensions, pack them along with a php.ini file:

extension_dir = "."

Overlapping elements in CSS

You can use relative positioning to overlap your elements. However, the space they would normally occupy will still be reserved for the element:

<div style="background-color:#f00;width:200px;height:100px;">
<div style="background-color:#0f0;width:200px;height:100px;position:relative;top:-50px;left:50px;">
<div style="background-color:#00f;width:200px;height:100px;">

In the example above, there will be a block of white space between the two 'DEFAULT POSITIONED' elements. This is caused, because the 'RELATIVE POSITIONED' element still has it's space reserved.

If you use absolute positioning, your elements will not have any space reserved, so your element will actually overlap, without breaking your document:

<div style="background-color:#f00;width:200px;height:100px;">
<div style="background-color:#0f0;width:200px;height:100px;position:absolute;top:50px;left:50px;">
<div style="background-color:#00f;width:200px;height:100px;">

Finally, you can control which elements are on top of the others by using z-index:

<div style="z-index:10;background-color:#f00;width:200px;height:100px;">
<div style="z-index:5;background-color:#0f0;width:200px;height:100px;position:absolute;top:50px;left:50px;">
<div style="z-index:0;background-color:#00f;width:200px;height:100px;">

How can I merge two MySQL tables?

You could write a script to update the FK's for you.. check out this blog:

They have a clever script to use the information_schema tables to get the "id" columns:

SET @db:='id_new'; 

select @max_id:=max(AUTO_INCREMENT) from information_schema.tables;

select concat('update ',table_name,' set ', column_name,' = ',column_name,'+',@max_id,' ; ') from information_schema.columns where table_schema=@db and column_name like '%id' into outfile 'update_ids.sql';

use id_new
source update_ids.sql;

Should 'using' directives be inside or outside the namespace?

One wrinkle I ran into (that isn't covered in other answers):

Suppose you have these namespaces:

  • Something.Other
  • Parent.Something.Other

When you use using Something.Other outside of a namespace Parent, it refers to the first one (Something.Other).

However if you use it inside of that namespace declaration, it refers to the second one (Parent.Something.Other)!

There is a simple solution: add the "global::" prefix: docs

namespace Parent
   using global::Something.Other;
   // etc

Get selected value from combo box in C# WPF

This largely depends on how the box is being filled. If it is done by attaching a DataTable (or other collection) to the ItemsSource, you may find attaching a SelectionChanged event handler to your box in the XAML and then using this in the code-behind useful:

private void ComboBoxName_SelectionChanged(object sender, SelectionChangedEventArgs e)
    ComboBox cbx = (ComboBox)sender;
    string s = ((DataRowView)cbx.Items.GetItemAt(cbx.SelectedIndex)).Row.ItemArray[0].ToString();

I saw 2 other answers on here that had different parts of that - one had ComboBoxName.Items.GetItemAt(ComboBoxName.SelectedIndex).ToString();, which looks similar but doesn't cast the box to a DataRowView, something I found I needed to do, and another: ((DataRowView)comboBox1.SelectedItem).Row.ItemArray[0].ToString();, used .SelectedItem instead of .Items.GetItemAt(comboBox1.SelectedIndex). That might've worked, but what I settled on was actually the combination of the two I wrote above, and don't remember why I avoided .SelectedItem except that it must not have worked for me in this scenario.

If you are filling the box dynamically, or with ComboBoxItem items in the dropdown directly in the XAML, this is the code I use:

private void ComboBoxName_SelectionChanged(object sender, SelectionChangedEventArgs e)
    ComboBox cbx = (ComboBox)sender;
    string val = String.Empty;
    if (cbx.SelectedValue == null)
        val = cbx.SelectionBoxItem.ToString();
        val = cboParser(cbx.SelectedValue.ToString());

You'll see I have cboParser, there. This is because the output from SelectedValue looks like this: System.Windows.Controls.Control: Some Value. At least it did in my project. So you have to parse your Some Value out of that:

private static string cboParser(string controlString)
    if (controlString.Contains(':'))
        controlString = controlString.Split(':')[1].TrimStart(' ');
    return controlString;

But this is why there are so many answers on this page. It largely depends on how you are filling the box, as to how you can get the value back out of it. An answer might be right in one circumstance, and wrong in the other.

How do I POST an array of objects with $.ajax (jQuery or Zepto)

Check this example of post the array of different types

function PostArray() {
    var myObj = [
        { 'fstName': 'name 1', 'lastName': 'last name 1', 'age': 32 }
      , { 'fstName': 'name 2', 'lastName': 'last name 1', 'age': 33 }

    var postData = JSON.stringify({ lst: myObj });

        type: "POST",
        url: urlWebMethods + "/getNames",
        data: postData,
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function (response) {
        failure: function (msg) {

If using a WebMethod in C# you can retrieve the data like this

    public static string getNames(IEnumerable<object> lst)
        string names = "";
            foreach (object item in lst)
                Type myType = item.GetType();
                IList<PropertyInfo> props = new List<PropertyInfo>(myType.GetProperties());

                foreach (PropertyInfo prop in props)
                    if(prop.Name == "Values")
                        Dictionary<string, object> dic = item as Dictionary<string, object>;
                        names += dic["fstName"];
        catch (Exception ex)
             names = "-1";
        return names;

Example in POST an array of objects with $.ajax to C# WebMethod

macro for Hide rows in excel 2010

Well, you're on the right path, Benno!

There are some tips regarding VBA programming that might help you out.

  1. Use always explicit references to the sheet you want to interact with. Otherwise, Excel may 'assume' your code applies to the active sheet and eventually you'll see it screws your spreadsheet up.

  2. As lionz mentioned, get in touch with the native methods Excel offers. You might use them on most of your tricks.

  3. Explicitly declare your variables... they'll show the list of methods each object offers in VBA. It might save your time digging on the internet.

Now, let's have a draft code...

Remember this code must be within the Excel Sheet object, as explained by lionz. It only applies to Sheet 2, is up to you to adapt it to both Sheet 2 and Sheet 3 in the way you prefer.

Hope it helps!

Private Sub Worksheet_Change(ByVal Target As Range)

    Dim oSheet As Excel.Worksheet

    'We only want to do something if the changed cell is B6, right?
    If Target.Address = "$B$6" Then

        'Checks if it's a number...
        If IsNumeric(Target.Value) Then

            'Let's avoid values out of your bonds, correct?
            If Target.Value > 0 And Target.Value < 51 Then

                'Let's assign the worksheet we'll show / hide rows to one variable and then
                '   use only the reference to the variable itself instead of the sheet name.
                '   It's safer.

                'You can alternatively replace 'sheet 2' by 2 (without quotes) which will represent
                '   the sheet index within the workbook
                Set oSheet = ActiveWorkbook.Sheets("Sheet 2")

                'We'll unhide before hide, to ensure we hide the correct ones
                oSheet.Range("A7:A56").EntireRow.Hidden = False

                oSheet.Range("A" & Target.Value + 7 & ":A56").EntireRow.Hidden = True

            End If

        End If

    End If

End Sub

Using subprocess to run Python script on Windows

How about this:

import sys
import subprocess

theproc = subprocess.Popen("", shell = True)
theproc.communicate()                   # ^^^^^^^^^^^^

This tells subprocess to use the OS shell to open your script, and works on anything that you can just run in cmd.exe.

Additionally, this will search the PATH for "" - which could be desirable.

How Big can a Python List Get?

As the Python documentation says:


The largest positive integer supported by the platform’s Py_ssize_t type, and thus the maximum size lists, strings, dicts, and many other containers can have.

In my computer (Linux x86_64):

>>> import sys
>>> print sys.maxsize

Python - How to concatenate to a string in a for loop?

While "".join is more pythonic, and the correct answer for this problem, it is indeed possible to use a for loop.

If this is a homework assignment (please add a tag if this is so!), and you are required to use a for loop then what will work (although is not pythonic, and shouldn't really be done this way if you are a professional programmer writing python) is this:

endstring = ""
mylist = ['first', 'second', 'other']
for word in mylist:
  print "This is the word I am adding: " + word
  endstring = endstring + word
print "This is the answer I get: " + endstring

You don't need the 'prints', I just threw them in there so you can see what is happening.

Secure FTP using Windows batch script

    ftps -a -z -e:on -pfxfile:"S-PID.p12" -pfxpwfile:"S-PID.p12.pwd" -user:<S-PID number> -s:script <RemoteServerName> 2121

S-PID.p12 => certificate file name ;
S-PID.p12.pwd => certificate password file name ; 
RemoteServerName =>  abcd123 ; 
2121 => port number ; 
ftps => command is part of ftps client software ; 

Submit form using <a> tag

Using Jquery you can do something like this:

$(document).ready(function() {_x000D_
  $('#btnSubmit').click(function() {_x000D_
<script src=""></script>_x000D_
<form action="" id="deleteFrm" method="POST">_x000D_
  <a id="btnSubmit">Submit</a>_x000D_

Escaping Strings in JavaScript

function addslashes( str ) {
    return (str + '').replace(/[\\"']/g, '\\$&').replace(/\u0000/g, '\\0');

.prop() vs .attr()

It's just the distinction between HTML attributes and DOM objects that causes a confusion. For those that are comfortable acting on the DOM elements native properties such a this.src this.value this.checked etc, .prop is a very warm welcome to the family. For others, it's just an added layer of confusion. Let's clear that up.

The easiest way to see the difference between .attr and .prop is the following example:

<input blah="hello">
  1. $('input').attr('blah'): returns 'hello' as expected. No suprises here.
  2. $('input').prop('blah'): returns undefined -- because it's trying to do [HTMLInputElement].blah -- and no such property on that DOM object exists. It only exists in the scope as an attribute of that element i.e. [HTMLInputElement].getAttribute('blah')

Now we change a few things like so:

$('input').attr('blah', 'apple');
$('input').prop('blah', 'pear');
  1. $('input').attr('blah'): returns 'apple' eh? Why not "pear" as this was set last on that element. Because the property was changed on the input attribute, not the DOM input element itself -- they basically almost work independently of each other.
  2. $('input').prop('blah'): returns 'pear'

The thing you really need to be careful with is just do not mix the usage of these for the same property throughout your application for the above reason.

See a fiddle demonstrating the difference:

.attr vs .prop:

Round 1: style

<input style="font:arial;"/>
  • .attr('style') -- returns inline styles for the matched element i.e. "font:arial;"
  • .prop('style') -- returns an style declaration object i.e. CSSStyleDeclaration

Round 2: value

<input value="hello" type="text"/>   

$('input').prop('value', 'i changed the value');
  • .attr('value') -- returns 'hello' *
  • .prop('value') -- returns 'i changed the value'

* Note: jQuery for this reason has a .val() method, which internally is equivalent to .prop('value')

ggplot2 plot area margins?

You can adjust the plot margins with plot.margin in theme() and then move your axis labels and title with the vjust argument of element_text(). For example :

qplot(rnorm(100)) +
    ggtitle("Title") +
    theme(axis.title.x=element_text(vjust=-2)) +
    theme(axis.title.y=element_text(angle=90, vjust=-0.5)) +
    theme(plot.title=element_text(size=15, vjust=3)) +
    theme(plot.margin = unit(c(1,1,1,1), "cm"))

will give you something like this :

enter image description here

If you want more informations about the different theme() parameters and their arguments, you can just enter ?theme at the R prompt.

Getting Chrome to accept self-signed localhost certificate

I had to tweak the Chrome launcher on macosx and added below script. Saved it as below;


RealBin="Google Chrome"
AppDir="$(dirname "$0")"
exec "$AppDir/$RealBin" --ignore-certificate-errors "$@"

When I start Chrome with this script self-signed certificates are working without a problem. But don't browse the web with the browser launched with this script you will not be warned about invalid certificates!

How to encode the plus (+) symbol in a URL

The + character has a special meaning in a URL => it means whitespace - . If you want to use the literal + sign, you need to URL encode it to %2b:


Here's an example of how you could properly generate URLs in .NET:

var uriBuilder = new UriBuilder("");

var values = HttpUtility.ParseQueryString(string.Empty);
values["view"] = "cm";
values["tf"] = "0";
values["to"] = "[email protected]";
values["su"] = "some subject";
values["body"] = "Hi there+Hello there";

uriBuilder.Query = values.ToString();


The result

How to export DataTable to Excel

You can use my SwiftExcel library. It is especially good when performance and low memory usage come in place as it writes data directly to the file:

using (var ew = new ExcelWriter("C:\\temp\\test.xlsx"))
    for (var row = 1; row <= 100; row++)
        for (var col = 1; col <= 10; col++)
            ew.Write($"row:{row}-col:{col}", col, row);

Nuget command to install:

Install-Package SwiftExcel

How to get min, seconds and milliseconds from in python?

This solution is very similar to that provided by @gdw2 , only that the string formatting is correctly done to match what you asked for - "Should be as compact as possible"

>>> import datetime
>>> a =
>>> "%s:%s.%s" % (a.minute, a.second, str(a.microsecond)[:2])

Regular expression to limit number of characters to 10

It might be beneficial to add greedy matching to the end of the string, so you can accept strings > than 10 and the regex will only return up to the first 10 chars. /^[a-z0-9]{0,10}$?/

No WebApplicationContext found: no ContextLoaderListener registered?

And if you would like to use an existing context, rather than a new context which would be loaded from xml configuration by org.springframework.web.context.ContextLoaderListener, then see ->

Spring Boot Multiple Datasource

Update 2018-01-07 with Spring Boot 1.5.8.RELEASE

If you want to know how to config it, how to use it, and how to control transaction. I may have answers for you.

You can see the runnable example and some explanation in

I copied some code here.

First you have to set like this



Then define them as providers (@Bean) like this:

@Bean(name = "datasource1")
public DataSource dataSource(){
    return DataSourceBuilder.create().build();

@Bean(name = "datasource2")
public DataSource dataSource2(){
    return DataSourceBuilder.create().build();

Note that I have @Bean(name="datasource1") and @Bean(name="datasource2"), then you can use it when we need datasource as @Qualifier("datasource1") and @Qualifier("datasource2") , for example

private DataSource dataSource;

If you do care about transaction, you have to define DataSourceTransactionManager for both of them, like this:

DataSourceTransactionManager tm1(@Qualifier ("datasource1") DataSource datasource) {
    DataSourceTransactionManager txm  = new DataSourceTransactionManager(datasource);
    return txm;

DataSourceTransactionManager tm2(@Qualifier ("datasource2") DataSource datasource) {
    DataSourceTransactionManager txm  = new DataSourceTransactionManager(datasource);
    return txm;

Then you can use it like

@Transactional //this will use the first datasource because it is @primary



This should be enough. See example and detail in the link above.

How to convert an NSString into an NSNumber

NSDecimalNumber *myNumber = [NSDecimalNumber decimalNumberWithString:@"123.45"];
NSLog(@"My Number : %@",myNumber);

There are No resources that can be added or removed from the server

The issue is it is missing Dynamic Web Module facet definition. Run the following at command line

mvn eclipse:eclipse -Dwtpversion=2.0

After build is success, refresh the project and you will be add the web project to server.

How do I get the current username in .NET using C#?

If you are in a network of users, then the username will be different:

- Will Display format : 'Username'

rather than

- Will Display format : 'NetworkName\Username'

Choose the format you want.

Checking the equality of two slices

You should use reflect.DeepEqual()

DeepEqual is a recursive relaxation of Go's == operator.

DeepEqual reports whether x and y are “deeply equal,” defined as follows. Two values of identical type are deeply equal if one of the following cases applies. Values of distinct types are never deeply equal.

Array values are deeply equal when their corresponding elements are deeply equal.

Struct values are deeply equal if their corresponding fields, both exported and unexported, are deeply equal.

Func values are deeply equal if both are nil; otherwise they are not deeply equal.

Interface values are deeply equal if they hold deeply equal concrete values.

Map values are deeply equal if they are the same map object or if they have the same length and their corresponding keys (matched using Go equality) map to deeply equal values.

Pointer values are deeply equal if they are equal using Go's == operator or if they point to deeply equal values.

Slice values are deeply equal when all of the following are true: they are both nil or both non-nil, they have the same length, and either they point to the same initial entry of the same underlying array (that is, &x[0] == &y[0]) or their corresponding elements (up to length) are deeply equal. Note that a non-nil empty slice and a nil slice (for example, []byte{} and []byte(nil)) are not deeply equal.

Other values - numbers, bools, strings, and channels - are deeply equal if they are equal using Go's == operator.

File changed listener in Java

I run this snippet of code every time I go to read the properties file, only actually reading the file if it has been modified since the last time I read it. Hope this helps someone.

private long timeStamp;
private File file;

private boolean isFileUpdated( File file ) {
  this.file = file;
  this.timeStamp = file.lastModified();

  if( this.timeStamp != timeStamp ) {
    this.timeStamp = timeStamp;
    //Yes, file is updated
    return true;
  //No, file is not updated
  return false;

Similar approach is used in Log4J FileWatchdog.

How to do select from where x is equal to multiple values?

You can try using parentheses around the OR expressions to make sure your query is interpreted correctly, or more concisely, use IN:

SELECT ads.*, location.county 
FROM ads
LEFT JOIN location ON location.county = ads.county_id
WHERE ads.published = 1 
AND ads.type = 13
AND ads.county_id IN (2,5,7,9)

Converting list to *args when calling function

yes, using *arg passing args to a function will make python unpack the values in arg and pass it to the function.


>>> def printer(*args):
 print args

>>> printer(2,3,4)
(2, 3, 4)
>>> printer(*range(2, 5))
(2, 3, 4)
>>> printer(range(2, 5))
([2, 3, 4],)

DataTable, How to conditionally delete rows

I don't have a windows box handy to try this but I think you can use a DataView and do something like so:

DataView view = new DataView(ds.Tables["MyTable"]);
view.RowFilter = "MyValue = 42"; // MyValue here is a column name

// Delete these rows.
foreach (DataRowView row in view)

I haven't tested this, though. You might give it a try.

Custom CSS Scrollbar for Firefox

I thought I would share my findings in case someone is considering a JQuery plugin to do the job.

I gave JQuery Custom Scrollbar a go. It's pretty fancy and does some smooth scrolling (with scrolling inertia) and has loads of parameters you can tweak, but it ended up being a bit too CPU intensive for me (and it adds a fair amount to the DOM).

Now I'm giving Perfect Scrollbar a go. It's simple and lightweight (6KB) and it's doing a decent job so far. It's not CPU intensive at all (as far as I can tell) and adds very little to your DOM. It's only got a couple of parameters to tweak (wheelSpeed and wheelPropagation), but it's all I need and it handles updates to the scrolling content nicely (such as loading images).

P.S. I did have a quick look at JScrollPane, but @simone is right, it's a bit dated now and a PITA.

Regex to remove letters, symbols except numbers

Use /[^0-9.,]+/ if you want floats.

How to initialize weights in PyTorch?

To initialize layers you typically don't need to do anything.

PyTorch will do it for you. If you think about, this has lot of sense. Why should we initialize layers, when PyTorch can do that following the latest trends.

Check for instance the Linear layer.

In the __init__ method it will call Kaiming He init function.

    def reset_parameters(self):
        init.kaiming_uniform_(self.weight, a=math.sqrt(3))
        if self.bias is not None:
            fan_in, _ = init._calculate_fan_in_and_fan_out(self.weight)
            bound = 1 / math.sqrt(fan_in)
            init.uniform_(self.bias, -bound, bound)

The similar is for other layers types. For conv2d for instance check here.

To note : The gain of proper initialization is the faster training speed. If your problem deserves special initialization you can do it afterwords.

Border for an Image view in Android?

This is an old post I know, but I thought this might possibly help someone out there.

If you want to simulate a translucent border that doesn't overlap the shape's "solid" color, then use this in your xml. Note that I don't use the "stroke" tag here at all as it seems to always overlap the actual drawn shape.

  <?xml version="1.0" encoding="utf-8"?>
    <layer-list xmlns:android="" >

        <shape android:shape="rectangle" >
            <solid android:color="#55111111" />

                android:top="10dp" />

            <corners android:radius="5dp" />
        <shape android:shape="rectangle" >
                android:top="5dp" />

            <solid android:color="#ff252525" />

Truncate to three decimals in Python

I think the best and proper way is to use decimal module.

import decimal

a = 1324343032.324325235

decimal_val = decimal.Decimal(str(a)).quantize(
float_val = float(decimal_val)



You can use different values for rounding=decimal.ROUND_DOWN, available options are ROUND_CEILING, ROUND_DOWN, ROUND_FLOOR, ROUND_HALF_DOWN, ROUND_HALF_EVEN, ROUND_HALF_UP, ROUND_UP, and ROUND_05UP. You can find explanation of each option here in docs.

How do I center list items inside a UL element?

ul {
    width: 100%;
    background: red;
    height: 20px;
    display: flex;
    justify-content: center;
    align-items: center;

li {
    background: blue;
    color: white;
    margin-right: 10px;

How to sort by Date with DataTables jquery plugin?

About update#1, there are 2 problems :

  • Number of days = 1 (d/MM/YYYY) instead of (dd/MM/YYYY)
  • Empty date

here is the solution to avoid these problems :

jQuery.fn.dataTableExt.oSort['uk_date-asc'] = function (a, b) {
            var ukDatea = a.split('/');
            var ukDateb = b.split('/');

            //Date empty
             if (ukDatea[0] == "" || ukDateb[0] == "") return 1;

            //need to change Date (d/MM/YYYY) into Date (dd/MM/YYYY) 
            if(ukDatea[0]<10) ukDatea[0] = "0" + ukDatea[0]; 
            if(ukDateb[0]<10) ukDateb[0] = "0" + ukDateb[0];

            var x = (ukDatea[2] + ukDatea[1] + ukDatea[0]) * 1;
            var y = (ukDateb[2] + ukDateb[1] + ukDateb[0]) * 1;

            return ((x < y) ? -1 : ((x > y) ? 1 : 0));

        //Sorting by Date 
        jQuery.fn.dataTableExt.oSort['uk_date-desc'] = function (a, b) {
            var ukDatea = a.split('/');
            var ukDateb = b.split('/');

             //Date empty
             if (ukDatea[0] == "" || ukDateb[0] == "") return 1;

            //MANDATORY to change Date (d/MM/YYYY) into Date (dd/MM/YYYY) 
            if(ukDatea[0]<10) ukDatea[0] = "0" + ukDatea[0]; 
            if(ukDateb[0]<10) ukDateb[0] = "0" + ukDateb[0];

            var x = (ukDatea[2] + ukDatea[1] + ukDatea[0]) * 1;
            var y = (ukDateb[2] + ukDateb[1] + ukDateb[0]) * 1;

            return ((x < y) ? 1 : ((x > y) ? -1 : 0));

PowerShell To Set Folder Permissions

Specifying inheritance in the FileSystemAccessRule() constructor fixes this, as demonstrated by the modified code below (notice the two new constuctor parameters inserted between "FullControl" and "Allow").

$Acl = Get-Acl "\\R9N2WRN\Share"

$Ar = New-Object System.Security.AccessControl.FileSystemAccessRule("user", "FullControl", "ContainerInherit,ObjectInherit", "None", "Allow")

Set-Acl "\\R9N2WRN\Share" $Acl

According to this topic

"when you create a FileSystemAccessRule the way you have, the InheritanceFlags property is set to None. In the GUI, this corresponds to an ACE with the Apply To box set to "This Folder Only", and that type of entry has to be viewed through the Advanced settings."

I have tested the modification and it works, but of course credit is due to the MVP posting the answer in that topic.

this is error ORA-12154: TNS:could not resolve the connect identifier specified?

run the below command in command prompt

tnsping Datasource

This should give a response like below

C:>tnsping *******

TNS Ping Utility for *** Windows: Version *** - Production on *****

Copyright (c) 1997, 2014, Oracle. All rights reserved.

Used parameter files: c:\oracle*****

Used **** to resolve the alias Attempting to contact (description=(address_list=(address=(protocol=tcp)(host=)(port=)))(connect_data=(server=)(service_name=)(failover_mode=(type=)(method=)(retries=)(delay=))))** OK (**** msec)

Add the text 'Datasource=' in beginning and credentials at the end. the final string should be

Data Source=(description=(address_list=(address=(protocol=tcp)(host=)(port=)))(connect_data=(server=)(service_name=)(failover_mode=(type=)(method=)(retries=)(delay=))));User Id=;Password=;**

Use this as the connection string to connect to oracle db.

ReSharper "Cannot resolve symbol" even when project builds

As you see, the solution is what everyone has already mentioned - simply by Suspending ReSharper, then Clearing the Caches, and finally Resuming it. But, no one mentioned how to do it without closing/restarting Visual Studio.

Just follow these steps:

  1. Getting ReSharper Cache Location

    • Manually by going to ReSharper Options > Environment > General > Store Solution Caches in (Combo Box) (marked 2 in the image). Selecting Custom Folder, then Copying the location of the Caches Folder from the text box shown (marked 3 in the image). Reverting the settings back. The 1 marked shows the ClearCache Button. It's usually wouldn't work so leave it. Image showing the stuff
  2. Suspending ReSharper

    • You can do this by going to Tools > Options > ReSharper Or ReSharper Ultimate > Suspend Now (Button) ReSharper Suspend Option
  3. Clearing the Cache

    • Go to the location copied earlier in step 1 and delete everything in that folder. And yes, I do mean everything.
  4. Resuming ReSharper

    • You can do this by again going to Tools > Options > ReSharper Or ReSharper Ultimate > Resume (Button)

How to connect html pages to mysql database?

HTML are markup languages, basically they are set of tags like <html>, <body>, which is used to present a website using , and as a whole. All these, happen in the clients system or the user you will be browsing the website.

Now, Connecting to a database, happens on whole another level. It happens on server, which is where the website is hosted.

So, in order to connect to the database and perform various data related actions, you have to use server-side scripts, like , , etc.

Now, lets see a snippet of connection using MYSQLi Extension of PHP

$db = mysqli_connect('hostname','username','password','databasename');

This single line code, is enough to get you started, you can mix such code, combined with HTML tags to create a HTML page, which is show data based pages. For example:

    $db = mysqli_connect('hostname','username','password','databasename');
                $query = "SELECT * FROM `mytable`;";
                $result = mysqli_query($db, $query);
                while($row = mysqli_fetch_assoc($result)) {
                      // Display your datas on the page

In order to insert new data into the database, you can use phpMyAdmin or write a INSERT query and execute them.

Get IFrame's document, from JavaScript in main document

In case you get a cross-domain error:

If you have control over the content of the iframe - that is, if it is merely loaded in a cross-origin setup such as on Amazon Mechanical Turk - you can circumvent this problem with the <body onload='my_func(my_arg)'> attribute for the inner html.

For example, for the inner html, use the this html parameter (yes - this is defined and it refers to the parent window of the inner body element):

<body onload='changeForm(this)'>

In the inner html :

    function changeForm(window) {
        console.log('inner window loaded: do whatever you want with the inner html');
        window.document.getElementById('mturk_form').style.display = 'none';

Rails: FATAL - Peer authentication failed for user (PG::Error)

If you installed postresql on your server then just host: localhost to database.yml, I usually throw it in around where it says pool: 5. Otherwise if it's not localhost definitely tell that app where to find its database.

  adapter: postgresql
  encoding: unicode
  database: kickrstack_development
  host: localhost
  pool: 5
  username: kickrstack
  password: secret

Make sure your user credentials are set correctly by creating a database and assigning ownership to your app's user to establish the connection. To create a new user in postgresql 9 run:

sudo -u postgres psql

set the postgresql user password if you haven't, it's just backslash password.

postgres=# \password

Create a new user and password and the user's new database:

postgres=# create user "guy_on_stackoverflow" with password 'keepitonthedl';
postgres=# create database "dcaclab_development" owner "guy_on_stackoverflow"; 

Now update your database.yml file after you've confirmed creating the database, user, password and set these privileges. Don't forget host: localhost.


The first syntax is redundant - the WITH CHECK is default for new constraints, and the constraint is turned on by default as well.

This syntax is generated by the SQL management studio when generating sql scripts -- I'm assuming it's some sort of extra redundancy, possibly to ensure the constraint is enabled even if the default constraint behavior for a table is changed.

Force flushing of output to a file while bash script is still running

I found a solution to this here. Using the OP's example you basically run

stdbuf -oL /homedir/MyScript &> some_log.log

and then the buffer gets flushed after each line of output. I often combine this with nohup to run long jobs on a remote machine.

stdbuf -oL nohup /homedir/MyScript &> some_log.log

This way your process doesn't get cancelled when you log out.

Fit website background image to screen size

You can try with

.appBackground {
    position: relative;
    background-image: url(".../img/background.jpg");
    background-size:100% 100vh;

works for me :)

iPhone - Grand Central Dispatch main thread

One place where it's useful is for UI activities, like setting a spinner before a lengthy operation:

- (void) handleDoSomethingButton{

    [mySpinner startAnimating];

    (do something lengthy)
    [mySpinner stopAnimating];

will not work, because you are blocking the main thread during your lengthy thing and not letting UIKit actually start the spinner.

- (void) handleDoSomethingButton{
     [mySpinner startAnimating];

     dispatch_async (dispatch_get_main_queue(), ^{
          (do something lengthy)
          [mySpinner stopAnimating];

will return control to the run loop, which will schedule UI updating, starting the spinner, then will get the next thing off the dispatch queue, which is your actual processing. When your processing is done, the animation stop is called, and you return to the run loop, where the UI then gets updated with the stop.

How can I declare a global variable in Angular 2 / Typescript?

A shared service is the best approach

export class SharedService {

But you need to be very careful when registering it to be able to share a single instance for whole your application. You need to define it when registering your application:

bootstrap(AppComponent, [SharedService]);

But not to define it again within the providers attributes of your components:

  providers: [ SharedService ], // No

Otherwise a new instance of your service will be created for the component and its sub-components.

You can have a look at this question regarding how dependency injection and hierarchical injectors work in Angular 2:

You should notice that you can also define Observable properties in the service to notify parts of your application when your global properties change:

export class SharedService {

  constructor() {
    this.globalVarUpdate = Observable.create((observer:Observer) => {
      this.globalVarObserver = observer;

  updateGlobalVar(newValue:string) {
    this.globalVar = newValue;;

See this question for more details:

How to call a vue.js function on page load

Beware that when the mounted event is fired on a component, not all Vue components are replaced yet, so the DOM may not be final yet.

To really simulate the DOM onload event, i.e. to fire after the DOM is ready but before the page is drawn, use vm.$nextTick from inside mounted:

mounted: function () {
  this.$nextTick(function () {
    // Will be executed when the DOM is ready

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

In Chrome 72 (2019-02-09) I've discovered that the :in-range attribute is applied to empty date inputs, for some reason!

So this works for me: (I added the :not([max]):not([min]) selectors to avoid breaking date inputs that do have a range applied to them:

input[type=date]:not([max]):not([min]):in-range {
    color: blue;


enter image description here

Here's a runnable sample:

window.addEventListener( 'DOMContentLoaded', onLoad );_x000D_
function onLoad() {_x000D_
    document.getElementById( 'date4' ).value = "2019-02-09";_x000D_
    document.getElementById( 'date5' ).value = null;_x000D_
label {_x000D_
    display: block;_x000D_
    margin: 1em;_x000D_
input[type=date]:not([max]):not([min]):in-range {_x000D_
    color: blue;_x000D_
    <input type="date" id="date1" />_x000D_
    Without HTML value=""_x000D_
    <input type="date" id="date2" value="2019-02-09" />_x000D_
    With HTML value=""_x000D_
    <input type="date" id="date3" />_x000D_
    Without HTML value="" but modified by user_x000D_
    <input type="date" id="date4" />_x000D_
    Without HTML value="" but set by script_x000D_
    <input type="date" id="date5" value="2019-02-09" />_x000D_
    With HTML value="" but cleared by script_x000D_

The import cannot be resolved

Please follow these Steps:

For Eclipse:

  • Go to your Project's Properties
  • Navigate to the Java Build Path
  • Then go to the Libraries tab. There click the Add External JARs Button on the Right pane.
  • Select the android-support-v4.jar file, usually the path for the Jar file is :
  • After adding android-support-v4.jar Library, navigate to the Order and Export tab and put check mark on the android-support-v4 Library file.
  • After doing the above, Clean the Project and Build it.
  • Problem Solved.

For Android Studio:

Short Version:

  • Add the following line to your build.gradle file:
    implementation ''

Long Version:

  • Go to File -> Project Structure

  • Go to "Dependencies" Tab -> Click on the Plus sign -> Go to "Library dependency"

  • Select the support library "support-v4 ("

  • Navigate to your "build.gradle" inside your App Directory and double check if your desired Android Support Library has been added to your dependencies.

  • Rebuild your project and now everything should work.

Further reading regarding this Question:

  1. Support Library - Android Dev
  2. Recent Support Library Revisions
  3. Support Library Packages
  4. What is an Android Support Library?
  5. How Android Support Library work?

I hope this helps.

ListBox with ItemTemplate (and ScrollBar!)

I have never had any luck with any scrollable content placed inside a stackpanel (anything derived from ScrollableContainer. The stackpanel has an odd layout mechanism that confuses child controls when the measure operation is completed and I found the vertical size ends up infinite, therefore not constrained - so it goes beyond the boundaries of the container and ends up clipped. The scrollbar doesn't show because the control thinks it has all the space in the world when it doesn't.

You should always place scrollable content inside a container that can resolve to a known height during its layout operation at runtime so that the scrollbars size appropriately. The parent container up in the visual tree must be able to resolve to an actual height, and this happens in the grid if you set the height of the RowDefinition o to auto or fixed.

This also happens in Silverlight.


How to append a newline to StringBuilder

For Kotlin,

StringBuilder().appendLine("your text");

Though this is a java question, this is also the first google result for Kotlin, might come in handy.

Can we update primary key values of a table?

Primary key attributes are just as updateable as any other attributes of a table. Stability is often a desirable property of a key but definitely not an absolute requirement. If it makes sense from a business perpective to update a key then there's no fundamental reason why you shouldn't.

JavaFX Location is not set error message

FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("../view/Main.fxml")); 

in my case i just remove ..

FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("/view/Main.fxml")); 

Stuck at ".android/repositories.cfg could not be loaded."

I used mkdir -p /root/.android && touch /root/.android/repositories.cfg to make it works

What's the difference between lists enclosed by square brackets and parentheses in Python?

Square brackets are lists while parentheses are tuples.

A list is mutable, meaning you can change its contents:

>>> x = [1,2]
>>> x.append(3)
>>> x
[1, 2, 3]

while tuples are not:

>>> x = (1,2)
>>> x
(1, 2)
>>> x.append(3)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'tuple' object has no attribute 'append'

The other main difference is that a tuple is hashable, meaning that you can use it as a key to a dictionary, among other things. For example:

>>> x = (1,2)
>>> y = [1,2]
>>> z = {}
>>> z[x] = 3
>>> z
{(1, 2): 3}
>>> z[y] = 4
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'list'

Note that, as many people have pointed out, you can add tuples together. For example:

>>> x = (1,2)
>>> x += (3,)
>>> x
(1, 2, 3)

However, this does not mean tuples are mutable. In the example above, a new tuple is constructed by adding together the two tuples as arguments. The original tuple is not modified. To demonstrate this, consider the following:

>>> x = (1,2)
>>> y = x
>>> x += (3,)
>>> x
(1, 2, 3)
>>> y
(1, 2)

Whereas, if you were to construct this same example with a list, y would also be updated:

>>> x = [1, 2]
>>> y = x
>>> x += [3]
>>> x
[1, 2, 3]
>>> y
[1, 2, 3]

Could not load NIB in bundle

Every time I refactor a view controller's name that's in my appDelegate I waste time on this. Refactoring doesn't change the nib name in initWithNibName:@"MYOldViewControllerName".

How to check the version of GitLab?

The easiest way is to paste the following command:

cat /opt/gitlab/version-manifest.txt | head -n 1

and there you get the version installed. :)

LINQ: Select where object does not contain items from list

Try this simple LINQ:

//For a file list/array
var files = Directory.GetFiles(folderPath, "*.*", SearchOption.AllDirectories);

//simply use Where ! x.Contains
var notContain = files.Where(x => ! x.Contains(@"\$RECYCLE.BIN\")).ToList();

//Or use Except()
var containing = files.Where(x => x.Contains(@"\$RECYCLE.BIN\")).ToList();
    notContain = files.Except(containing).ToList();

Concatenating bits in VHDL

The concatenation operator '&' is allowed on the right side of the signal assignment operator '<=', only

Where can I find System.Web.Helpers, System.Web.WebPages, and System.Web.Razor?

As for VS2017 I didn't find it in "extensions", there's a Nuget package called "microsoft-web-helpers" that seems to be equivalent to System.Web.Helpers.

Bootstrap throws Uncaught Error: Bootstrap's JavaScript requires jQuery

In my case solution is really silly, and strange.

Below code was pre-populated by _Layout.cshtml file. (NOT written by me)

<script src="~/Scripts/jquery-1.10.2.min.js"></script>
<script src="~/Scripts/bootstrap.min.js"></script>

But, when I verified in Scripts folder, jquery-1.10.2.min.js was not even available. Hence, replaced code like below where jquery-1.9.1.min.js is an existing file:

<script src="~/Scripts/jquery-1.9.1.min.js"></script>
<script src="~/Scripts/bootstrap.min.js"></script>

jQuery Datepicker onchange event issue

On jQueryUi 1.9 I've managed to get it to work through an additional data value and a combination of beforeShow and onSelect functions:

$( ".datepicker" ).datepicker({
    beforeShow: function( el ){
        // set the current value before showing the widget
        $(this).data('previous', $(el).val() );

    onSelect: function( newText ){
        // compare the new value to the previous one
        if( $(this).data('previous') != newText ){
            // do whatever has to be done, e.g. log it to console
            console.log( 'changed to: ' + newText );

Works for me :)

check if a std::vector contains a certain object?

See question: How to find an item in a std::vector?

You'll also need to ensure you've implemented a suitable operator==() for your object, if the default one isn't sufficient for a "deep" equality test.

How to fix Ora-01427 single-row subquery returns more than one row in select?

Use the following query:

       E.I_EmpName AS EMPNAME,
              'AfterNoon') AS DURATION,
       L.I_LeaveType AS LEAVETYPE,
                         FROM T_COMPENSATION C
                        WHERE C.I_COMPENSATEDDATE = A.I_REQDATE
                          AND C.I_EMPID = A.I_EMPID),
               ' ',
               '') AS WORKDATE,
    ON A.I_EMPID = E.I_EmpID
   AND UPPER(E.I_IsActive) = 'YES'
   AND A.I_STATUS = '1'
 WHERE E.I_EMPID <> '22'

The trick is to force the inner query return only one record by adding an aggregate function (I have used max() here). This will work perfectly as far as the query is concerned, but, honestly, OP should investigate why the inner query is returning multiple records by examining the data. Are these multiple records really relevant business wise?

CodeIgniter - how to catch DB errors?

You must turn debug off for database in config/database.php ->

$db['default']['db_debug'] = FALSE;

It is better for your website security.

Package name does not correspond to the file path - IntelliJ


For those using Kotlin who are following the docs package conventions:

In pure Kotlin projects, the recommended directory structure is to follow the package structure with the common root package omitted (e.g. if all the code in the project is in the "org.example.kotlin" package and its subpackages, files with the "org.example.kotlin" package should be placed directly under the source root, and files in "" should be in the "foo/bar" subdirectory of the source root).

IntelliJ doesn't support this yet. The only thing you can do is to disable this warning, and accept that the IDE will not help you with refactorings when it comes to changing folders/files structures.

How can I get an int from stdio in C?

I'm not fully sure that this is what you're looking for, but if your question is how to read an integer using <stdio.h>, then the proper syntax is

int myInt;
scanf("%d", &myInt);

You'll need to do a lot of error-handling to ensure that this works correctly, of course, but this should be a good start. In particular, you'll need to handle the cases where

  1. The stdin file is closed or broken, so you get nothing at all.
  2. The user enters something invalid.

To check for this, you can capture the return code from scanf like this:

int result = scanf("%d", &myInt);

If stdin encounters an error while reading, result will be EOF, and you can check for errors like this:

int myInt;
int result = scanf("%d", &myInt);

if (result == EOF) {
    /* ... you're not going to get any input ... */

If, on the other hand, the user enters something invalid, like a garbage text string, then you need to read characters out of stdin until you consume all the offending input. You can do this as follows, using the fact that scanf returns 0 if nothing was read:

int myInt;
int result = scanf("%d", &myInt);

if (result == EOF) {
    /* ... you're not going to get any input ... */
if (result == 0) {
    while (fgetc(stdin) != '\n') // Read until a newline is found

Hope this helps!

EDIT: In response to the more detailed question, here's a more appropriate answer. :-)

The problem with this code is that when you write

printf("got the number: %d", scanf("%d", &x));

This is printing the return code from scanf, which is EOF on a stream error, 0 if nothing was read, and 1 otherwise. This means that, in particular, if you enter an integer, this will always print 1 because you're printing the status code from scanf, not the number you read.

To fix this, change this to

int x;
scanf("%d", &x);
/* ... error checking as above ... */
printf("got the number: %d", x);

Hope this helps!

Working Copy Locked

You can fix it with only one step.

Step 1 : Open terminal and go to your project then fire command "svn cleanup" then "svn update"


Short answer: No practical, performance, or storage, difference.

Long answer:

There is essentially no difference (in MySQL) between VARCHAR(3000) (or any other large limit) and TEXT. The former will truncate at 3000 characters; the latter will truncate at 65535 bytes. (I make a distinction between bytes and characters because a character can take multiple bytes.)

For smaller limits in VARCHAR, there are some advantages over TEXT.

  • "smaller" means 191, 255, 512, 767, or 3072, etc, depending on version, context, and CHARACTER SET.
  • INDEXes are limited in how big a column can be indexed. (767 or 3072 bytes; this is version and settings dependent)
  • Intermediate tables created by complex SELECTs are handled in two different ways -- MEMORY (faster) or MyISAM (slower). When 'large' columns are involved, the slower technique is automatically picked. (Significant changes coming in version 8.0; so this bullet item is subject to change.)
  • Related to the previous item, all TEXT datatypes (as opposed to VARCHAR) jump straight to MyISAM. That is, TINYTEXT is automatically worse for generated temp tables than the equivalent VARCHAR. (But this takes the discussion in a third direction!)
  • VARBINARY is like VARCHAR; BLOB is like TEXT.

Rebuttal to other answers

The original question asked one thing (which datatype to use); the accepted answer answered something else (off-record storage). That answer is now out of date.

When this thread was started and answered, there were only two "row formats" in InnoDB. Soon afterwards, two more formats (DYNAMIC and COMPRESSED) were introduced.

The storage location for TEXT and VARCHAR() is based on size, not on name of datatype. For an updated discussion of on/off-record storage of large text/blob columns, see this .

Change key pair for ec2 instance

This answer is useful in the case you no longer have SSH access to the existing server (i.e. you lost your private key).

If you still have SSH access, please use one of the answers below.

Here is what I did, thanks to Eric Hammond's blog post:

  1. Stop the running EC2 instance
  2. Detach its /dev/xvda1 volume (let's call it volume A) - see here
  3. Start new t1.micro EC2 instance, using my new key pair. Make sure you create it in the same subnet, otherwise you will have to terminate the instance and create it again. - see here
  4. Attach volume A to the new micro instance, as /dev/xvdf (or /dev/sdf)
  5. SSH to the new micro instance and mount volume A to /mnt/tmp
$ sudo mkdir /mnt/tmp; sudo mount /dev/xvdf1 /mnt/tmp
  1. Copy ~/.ssh/authorized_keys to /mnt/tmp/home/ubuntu/.ssh/authorized_keys
  2. Logout
  3. Terminate micro instance
  4. Detach volume A from it
  5. Attach volume A back to the main instance as /dev/xvda
  6. Start the main instance
  7. Login as before, using your new .pem file

That's it.

How to disable SSL certificate checking with Spring RestTemplate?

You can also register your keystore :

private void registerKeyStore(String keyStoreName) {
    try {
        ClassLoader classLoader = this.getClass().getClassLoader();
        InputStream keyStoreInputStream = classLoader.getResourceAsStream(keyStoreName);
        if (keyStoreInputStream == null) {
            throw new FileNotFoundException("Could not find file named '" + keyStoreName + "' in the CLASSPATH");

        //load the keystore
        KeyStore keystore = KeyStore.getInstance(KeyStore.getDefaultType());
        keystore.load(keyStoreInputStream, null);

        //add to known keystore 
        TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());

        //default SSL connections are initialized with the keystore above
        TrustManager[] trustManagers = trustManagerFactory.getTrustManagers();
        SSLContext sc = SSLContext.getInstance("SSL");
        sc.init(null, trustManagers, null);
    } catch (IOException | GeneralSecurityException e) {
        throw new RuntimeException(e);

How can I get city name from a latitude and longitude point?

Here is the latest sample of Google's geocode Web Service,-73.961452&key=YOUR_API_KEY

Simply change the YOUR_API_KEY to the API key you get from Google Geocoding API

P/S: Geocoding API is under Places NOT Maps ;)

How can I close a dropdown on click outside?

This is the Angular Bootstrap DropDowns button sample with close outside of component.

without use bootstrap.js

// .html
<div class="mx-3 dropdown" []="isTestButton">
  <button class="btn dropdown-toggle"
          (click)="isTestButton = !isTestButton">
  <div class="dropdown-menu" []="isTestButton">
    <button class="btn dropdown-item">Month</button>
    <button class="btn dropdown-item">Week</button>

// .ts
import { Component, ElementRef, HostListener } from "@angular/core";

  selector: "app-test",
  templateUrl: "./test.component.html",
  styleUrls: ["./test.component.scss"]
export class TestComponent {

  isTestButton = false;

  constructor(private eleRef: ElementRef) {

  @HostListener("document:click", ["$event"])
  docEvent($e: MouseEvent) {
    if (!this.isTestButton) {
    const paths: Array<HTMLElement> = $e["path"];
    if (!paths.some(p => p === this.eleRef.nativeElement)) {
      this.isTestButton = false;

How to get Linux console window width in Python

Starting at Python 3.3 it is straight forward:

>>> import os
>>> ts = os.get_terminal_size()
>>> ts.lines
>>> ts.columns

How to store a large (10 digits) integer?

A wrapper class java.lang.Long can store 10 digit easily.

   Long phoneNumber = 1234567890;

It can store more than that also.


public final class Long extends Number implements Comparable<Long> {
     * A constant holding the minimum value a {@code long} can
     * have, -2<sup>63</sup>.
    @Native public static final long MIN_VALUE = 0x8000000000000000L;

     * A constant holding the maximum value a {@code long} can
     * have, 2<sup>63</sup>-1.
    @Native public static final long MAX_VALUE = 0x7fffffffffffffffL;

This means it can store values of range 9,223,372,036,854,775,807 to -9,223,372,036,854,775,808.

matplotlib savefig in jpeg format

Matplotlib can handle directly and transparently jpg if you have installed PIL. You don't need to call it, it will do it by itself. If Python cannot find PIL, it will raise an error.

What is Java Servlet?

A servlet at its very core is a java class; which can handle HTTP requests. Typically the internal nitty-gritty of reading a HTTP request and response over the wire is taken care of by the containers like Tomcat. This is done so that as a server side developer you can focus on what to do with the HTTP request and responses and not bother about dealing with code that deals with networking etc. The container will take care of things like wrapping the whole thing in a HTTP response object and send it over to the client (say a browser).

Now the next logical question to ask is who decides what is a container supposed to do? And the answer is; In Java world at least It is guided (note I did not use the word controlled) by specifications. For example Servlet specifications (See resource 2) dictates what a servlet must be able to do. So if you can write an implementation for the specification, congratulations you just created a container (Technically containers like Tomcat also implement other specifications and do tricky stuff like custom class loaders etc but you get the idea).

Assuming you have a container, your servlets are now java classes whose lifecycle will be maintained by the container but their reaction to incoming HTTP requests will be decided by you. You do that by writing what-you-want-to-do in the pre-defined methods like init(), doGet(), doPost() etc. Look at Resource 3.

Here is a fun exercise for you. Create a simple servlet like in Resource 3 and write a few System.out.println() statements in it's constructor method (Yes you can have a constructor of a servlet), init(), doGet(), doPost() methods and run the servlet in tomcat. See the console logs and tomcat logs.

Hope this helps, happy learning.


  1. Look how the HTTP servlet looks here(Tomcat example).

  2. Servlet Specification.

  3. Simple Servlet example.

  4. Start reading the book online/PDF It also provides you download of the whole book. May be this will help. if you are just starting servlets may be it's a good idea to read the material along with the servlet API. it's a slower process of learning, but is way more helpful in getting the basics clear.

Add Bootstrap Glyphicon to Input Box

input {_x000D_
  border:solid 1px #ddd;_x000D_
}_x000D_ {_x000D_
 background-repeat: no-repeat;_x000D_
 background-position-y: 1px;_x000D_
 background-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABQAAAASCAYAAABb0P4QAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAADbSURBVDhP5ZI9C4MwEIb7//+BEDgICA6C4OQgBJy6dRIEB6EgCNkEJ4e3iT2oHzH9wHbpAwfyJvfkJDnhYH4kHDVKlSAigSAQoCiBKjVGXvaxFXZnxBQYkSlBICII+22K4jM63rbHSthCSdsskVX9Y6KxR5XJSSpVy6GbpbBKp6aw0BzM0ShCe1iKihMXC6EuQtMQwukzPFu3fFd4+C+/cimUNxy6WQkNnmdzL3NYPfDmLVuhZf2wZYz80qDkKX1St3CXAfVMqq4cz3hTaGEpmctxDPmB0M/fCYEbAwZYyVKYcroAAAAASUVORK5CYII=);_x000D_
<input class="search">

How to print Unicode character in Python?

Just one more thing that hasn't been added yet

In Python 2, if you want to print a variable that has unicode and use .format(), then do this (make the base string that is being formatted a unicode string with u'':

>>> text = "Université de Montréal"
>>> print(u"This is unicode: {}".format(text))
>>> This is unicode: Université de Montréal

How to create a css rule for all elements except one class?

Wouldn't setting a css rule for all tables, and then a subsequent one for tables where class="dojoxGrid" work? Or am I missing something?

Set the table column width constant regardless of the amount of text in its cells?

If you need one ore more fixed-width columns while other columns should resize, try setting both min-width and max-width to the same value.

Commenting out a set of lines in a shell script

You can also put multi-line comments using:

: '

As per the Bash Reference for Bourne Shell builtins

: (a colon)

: [arguments]

Do nothing beyond expanding arguments and performing redirections. The return status is zero.

Thanks to Ikram for pointing this out in the post Shell script put multiple line comment

How to draw a custom UIView that is just a circle - iPhone app

Here is another way by using UIBezierPath (maybe it's too late ^^) Create a circle and mask UIView with it, as follows:

UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 200, 200)];
view.backgroundColor = [UIColor blueColor];

CAShapeLayer *shape = [CAShapeLayer layer];
UIBezierPath *path = [UIBezierPath radius:(view.bounds.size.width / 2) startAngle:0 endAngle:(2 * M_PI) clockwise:YES];
shape.path = path.CGPath;
view.layer.mask = shape;

No shadow by default on Toolbar?

In my situation elevation doesn't work well because I haven't given any background to the toolbar. Try giving background color to the toolbar then set elevation and it will work well.

Execute a batch file on a remote PC using a batch file on local PC

While I would recommend against this.

But you can use shutdown as client if the target machine has remote shutdown enabled and is in the same workgroup.


shutdown.exe /s /m \\<target-computer-name> /t 00

replacing <target-computer-name> with the URI for the target machine,

Otherwise, if you want to trigger this through Apache, you'll need to configure the batch script as a CGI script by putting AddHandler cgi-script .bat and Options +ExecCGI into either a local .htaccess file or in the main configuration for your Apache install.

Then you can just call the .bat file containing the shutdown.exe command from your browser.

Spring Boot, Spring Data JPA with multiple DataSources

I have written a complete article at Spring Boot JPA Multiple Data Sources Example. In this article, we will learn how to configure multiple data sources and connect to multiple databases in a typical Spring Boot web application. We will use Spring Boot 2.0.5, JPA, Hibernate 5, Thymeleaf and H2 database to build a simple Spring Boot multiple data sources web application.

Sometimes adding a WCF Service Reference generates an empty reference.cs

I faced similar issue yesterday during development. I found out I was using same namespace in 2 different versions of contracts.

We've 2 version of contracts for example version4 and version5. I've copied all the contracts from version4 and renamed all the namespace from version4 to version5. While doing this I forgot to rename the namespace from v4 to v5 in one of the files. Due to namespace conflict, Reference.cs file was empty.

This issue is hard to troubleshoot as you don't get any error message while generating the service reference. To identify this issue I'd manually validate all the new files I'd created. There are other ways to solve this issue. This is the first step you should perform before going for other options.

Execute jar file with multiple classpath libraries from command prompt

You cannot use both -jar and -cp on the command line - see the java documentation that says that if you use -jar:

the JAR file is the source of all user classes, and other user class path settings are ignored.

You could do something like this:

java -cp lib\*.jar;. myproject.MainClass

Notice the ;. in the -cp argument, to work around a Java command-line bug. Also, please note that this is the Windows version of the command. The path separator on Unix is :.

how to load url into div tag

You need to use an iframe.

<script type="text/javascript">
<iframe id="content" src="about:blank"></iframe>

Reduce git repository size

Thanks for your replies. Here's what I did:

git gc
git gc --aggressive
git prune

That seemed to have done the trick. I started with around 10.5MB and now it's little more than 980KBs.

remove table row with specific id

Remove by id -


Also I would suggest to use better naming, like row-1, row-2

Default value in an mvc view model

Create a base class for your ViewModels with the following constructor code which will apply the DefaultValueAttributeswhen any inheriting model is created.

public abstract class BaseViewModel
    protected BaseViewModel()
        // apply any DefaultValueAttribute settings to their properties
        var propertyInfos = this.GetType().GetProperties();
        foreach (var propertyInfo in propertyInfos)
            var attributes = propertyInfo.GetCustomAttributes(typeof(DefaultValueAttribute), true);
            if (attributes.Any())
                var attribute = (DefaultValueAttribute) attributes[0];
                propertyInfo.SetValue(this, attribute.Value, null);

And inherit from this in your ViewModels:

public class SearchModel : BaseViewModel
    public bool IsMale { get; set; }
    public bool IsFemale { get; set; }

Prevent scroll-bar from adding-up to the Width of page on Chrome

All you need to do is add:

html {
    overflow-y: scroll;

In your css file as this will have the scroller whether it is needed or not though you just won't be able to scroll

This means that the viewport will have the same width for both

How to find all the tables in MySQL with specific column names in them?


Can I apply the required attribute to <select> fields in HTML5?

You can use the selected attribute for the option element to select a choice by default. You can use the required attribute for the select element to ensure that the user selects something.

In Javascript, you can check the selectedIndex property to get the index of the selected option, or you can check the value property to get the value of the selected option.

According to the HTML5 spec, selectedIndex "returns the index of the first selected item, if any, or -1 if there is no selected item. And value "returns the value of the first selected item, if any, or the empty string if there is no selected item." So if selectedIndex = -1, then you know they haven't selected anything.

<button type="button" onclick="displaySelection()">What did I pick?</button>
    function displaySelection()
        var mySelect = document.getElementById("someSelectElement");
        var mySelection = mySelect.selectedIndex;

An existing connection was forcibly closed by the remote host - WCF

I have catched the same exception and found a InnerException: SocketException. in the svclog trace.

After looking in the windows event log I saw an error coming from the System.ServiceModel.Activation.TcpWorkerProcess class.

Are you hosting your wcf service in IIS with netTcpBinding and port sharing?

It seems there is a bug in IIS port sharing feature, check the fix:

My solution is to host your WCF service in a Windows Service.

How can I create a temp file with a specific extension with .NET?

I mixed @Maxence and @Mitch Wheat answers keeping in mind I want the semantic of GetTempFileName method (the fileName is the name of a new file created) adding the extension preferred.

string GetNewTempFile(string extension)
    if (!extension.StartWith(".")) extension="." + extension;
    string fileName;
    bool bCollisions = false;
    do {
        fileName = Path.Combine(System.IO.Path.GetTempPath(), Guid.NewGuid().ToString() + extension);
            using (new FileStream(fileName, FileMode.CreateNew)) { }
            bCollisions = false;
        catch (IOException)
            bCollisions = true;
    while (bCollisions);
    return fileName;

Binding List<T> to DataGridView in WinForm

List does not implement IBindingList so the grid does not know about your new items.

Bind your DataGridView to a BindingList<T> instead.

var list = new BindingList<Person>(persons);
myGrid.DataSource = list;

But I would even go further and bind your grid to a BindingSource

var list = new List<Person>()
    new Person { Name = "Joe", },
    new Person { Name = "Misha", },
var bindingList = new BindingList<Person>(list);
var source = new BindingSource(bindingList, null);
grid.DataSource = source;

Node Multer unexpected field

In my case, I had 2 forms in differents views and differents router files. The first router used the name field with view one and its file name was "inputGroupFile02". The second view had another name for file input. For some reason Multer not allows you set differents name in different views, so I dicided to use same name for the file input in both views.

enter image description here

React proptype array with shape

There's a ES6 shorthand import, you can reference. More readable and easy to type.

import React, { Component } from 'react';
import { arrayOf, shape, number } from 'prop-types';

class ExampleComponent extends Component {
  static propTypes = {
    annotationRanges: arrayOf(shape({
      start: number,
      end: number,

  static defaultProps = {
     annotationRanges: [],

Websocket connections with Postman

It's not possible in Postman yet; But there is a new alternative for Postman, named Postwoman. it's open source and supports realtime Websocket and SSE requests.


It seems they have rebranded Postwoman to Hoppscotch and have improved the Websocket support.

How to make a HTML list appear horizontally instead of vertically using CSS only?

quite simple:

ul.yourlist li { float:left; }


ul.yourlist li { display:inline; }

Insert Data Into Temp Table with Query

This is possible. Try this way:

Create Global Temporary Table 
On Commit Preserve Rows 
select ArtistName, sum(Songs) As NumberOfSongs 
 from Spotfy 
    where ArtistName = 'BossaDoSamba'
 group by ArtistName;

TypeScript enum to object array

A tricky bit is that TypeScript will 'double' map the enum in the emitted object, so it can be accessed both by key and value.

enum MyEnum {
    Part1 = 0,
    Part2 = 1

will be emitted as

   Part1: 0,
   Part2: 1,
   0: 'Part1',
   1: 'Part2'

So you should filter the object first before mapping. So @Diullei 's solution has the right answer. Here is my implementation:

// Helper
const StringIsNumber = value => isNaN(Number(value)) === false;

// Turn enum into array
function ToArray(enumme) {
    return Object.keys(enumme)
        .map(key => enumme[key]);

Use it like this:

export enum GoalProgressMeasurements {


error: function returns address of local variable

Neither malloc or call by reference are needed. You can declare a pointer within the function and set it to the string/array you'd like to return.

Using @Gewure's code as the basis:

char *getStringNoMalloc(void){
    char string[100] = {};
    char *s_ptr = string;

    strcat(string, "bla");
    strcat(string, "/");
    strcat(string, "blub");
    //INSIDE this function "string" is OK
    printf("string : '%s'\n", string);

    return s_ptr; 

works perfectly.

With a non-loop version of the code in the original question:

char *foo(int x){    
    char a[1000];
    char *a_ptr = a;
    char *b = "blah";       

    strcpy(a, b);

    return a_ptr;

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

from IPython.display import Image

Image(filename =r'C:\user\path')

I've seen some solutions and some wont work because of the raw directory, when adding codes like the one above, just remember to add 'r' before the directory. this should avoid this kind of error: (unicode error) 'unicodeescape' codec can't decode bytes in position 2-3: truncated \UXXXXXXXX escape

Can I force a page break in HTML printing?

I was struggling this for some time, it never worked.

In the end, the solution was to put a style element in the head.

The page-break-after can't be in a linked CSS file, it must be in the HTML itself.

git pull error :error: remote ref is at but expected

After searching constantly, this is the solution that worked for me which entails unsetting/removing the Upstream

git branch --unset-upstream

Passing command line arguments from Maven as properties in pom.xml

I used the properties plugin to solve this.

Properties are defined in the pom, and written out to a file, where they can then be accessed from your Java code.

In my case it is test code that needs to access this properties file, so in the pom the properties file is written to maven's testOutputDirectory:


Use outputDirectory if you want properties to be accessible by your app code:


For those looking for a fuller example (it took me a bit of fiddling to get this working as I didn't understand how naming of properties tags affects ability to retrieve them elsewhere in the pom file), my pom looks as follows:





And on the command line:

mvn clean test -Dapp.env=LOCAL -Dapp.domain=localhost -Dapp.port=9901

So these properties can be accessed from the Java code: inputStream = Thread.currentThread().getContextClassLoader().getResourceAsStream("");
 java.util.Properties properties = new Properties();
 appPort = properties.getProperty("app.port");
 appDomain = properties.getProperty("app.domain");

Find everything between two XML tags with RegEx

In our case, we receive an XML as a String and need to get rid of the values that have some "special" characters, like &<> etc. Basically someone can provide an XML to us in this form:

     <to>jenice & carl </to>
     <from>your neighbor <; </from>

So I need to find in that String the values jenice & carl and your neighbor <; and properly escape & and < (otherwise this is an invalid xml if you later pass it to an engine that shall rename unnamed).

Doing this with regex is a rather dumb idea to begin with, but it's cheap and easy. So the brave ones that would like to do the same thing I did, here you go:

    String xml = ...
    Pattern p = Pattern.compile("<(.+)>(?!\\R<)(.+)</(\\1)>");
    Matcher m = p.matcher(xml);
    String result = m.replaceAll(mr -> {
        if ("&")) {
            return "<" + + ">" + + "+ some change" + "</" + + ">";
        return "<" + + ">" + + "</" + + ">";

PHP AES encrypt / decrypt

Few important things to note with AES encryption:

  1. Never use plain text as encryption key. Always hash the plain text key and then use for encryption.
  2. Always use Random IV (initialization vector) for encryption and decryption. True randomization is important.
  3. As mentioned above, don't use mode, use CBC instead.

Numpy first occurrence of value greater than existing value

Arrays that have a constant step between elements

In case of a range or any other linearly increasing array you can simply calculate the index programmatically, no need to actually iterate over the array at all:

def first_index_calculate_range_like(val, arr):
    if len(arr) == 0:
        raise ValueError('no value greater than {}'.format(val))
    elif len(arr) == 1:
        if arr[0] > val:
            return 0
            raise ValueError('no value greater than {}'.format(val))

    first_value = arr[0]
    step = arr[1] - first_value
    # For linearly decreasing arrays or constant arrays we only need to check
    # the first element, because if that does not satisfy the condition
    # no other element will.
    if step <= 0:
        if first_value > val:
            return 0
            raise ValueError('no value greater than {}'.format(val))

    calculated_position = (val - first_value) / step

    if calculated_position < 0:
        return 0
    elif calculated_position > len(arr) - 1:
        raise ValueError('no value greater than {}'.format(val))

    return int(calculated_position) + 1

One could probably improve that a bit. I have made sure it works correctly for a few sample arrays and values but that doesn't mean there couldn't be mistakes in there, especially considering that it uses floats...

>>> import numpy as np
>>> first_index_calculate_range_like(5, np.arange(-10, 10))
>>> np.arange(-10, 10)[16]  # double check

>>> first_index_calculate_range_like(4.8, np.arange(-10, 10))

Given that it can calculate the position without any iteration it will be constant time (O(1)) and can probably beat all other mentioned approaches. However it requires a constant step in the array, otherwise it will produce wrong results.

General solution using numba

A more general approach would be using a numba function:

def first_index_numba(val, arr):
    for idx in range(len(arr)):
        if arr[idx] > val:
            return idx
    return -1

That will work for any array but it has to iterate over the array, so in the average case it will be O(n):

>>> first_index_numba(4.8, np.arange(-10, 10))
>>> first_index_numba(5, np.arange(-10, 10))


Even though Nico Schlömer already provided some benchmarks I thought it might be useful to include my new solutions and to test for different "values".

The test setup:

import numpy as np
import math
import numba as nb

def first_index_using_argmax(val, arr):
    return np.argmax(arr > val)

def first_index_using_where(val, arr):
    return np.where(arr > val)[0][0]

def first_index_using_nonzero(val, arr):
    return np.nonzero(arr > val)[0][0]

def first_index_using_searchsorted(val, arr):
    return np.searchsorted(arr, val) + 1

def first_index_using_min(val, arr):
    return np.min(np.where(arr > val))

def first_index_calculate_range_like(val, arr):
    if len(arr) == 0:
        raise ValueError('empty array')
    elif len(arr) == 1:
        if arr[0] > val:
            return 0
            raise ValueError('no value greater than {}'.format(val))

    first_value = arr[0]
    step = arr[1] - first_value
    if step <= 0:
        if first_value > val:
            return 0
            raise ValueError('no value greater than {}'.format(val))

    calculated_position = (val - first_value) / step

    if calculated_position < 0:
        return 0
    elif calculated_position > len(arr) - 1:
        raise ValueError('no value greater than {}'.format(val))

    return int(calculated_position) + 1

def first_index_numba(val, arr):
    for idx in range(len(arr)):
        if arr[idx] > val:
            return idx
    return -1

funcs = [

from simple_benchmark import benchmark, MultiArgument

and the plots were generated using:

%matplotlib notebook

item is at the beginning

b = benchmark(
    {2**i: MultiArgument([0, np.arange(2**i)]) for i in range(2, 20)},
    argument_name="array size")

enter image description here

The numba function performs best followed by the calculate-function and the searchsorted function. The other solutions perform much worse.

item is at the end

b = benchmark(
    {2**i: MultiArgument([2**i-2, np.arange(2**i)]) for i in range(2, 20)},
    argument_name="array size")

enter image description here

For small arrays the numba function performs amazingly fast, however for bigger arrays it's outperformed by the calculate-function and the searchsorted function.

item is at sqrt(len)

b = benchmark(
    {2**i: MultiArgument([np.sqrt(2**i), np.arange(2**i)]) for i in range(2, 20)},
    argument_name="array size")

enter image description here

This is more interesting. Again numba and the calculate function perform great, however this is actually triggering the worst case of searchsorted which really doesn't work well in this case.

Comparison of the functions when no value satisfies the condition

Another interesting point is how these function behave if there is no value whose index should be returned:

arr = np.ones(100)
value = 2

for func in funcs:
        print('-->', func(value, arr))
    except Exception as e:
        print('-->', e)

With this result:

--> 0
--> zero-size array to reduction operation minimum which has no identity
--> index 0 is out of bounds for axis 0 with size 0
--> no value greater than 2
--> -1
--> 101
--> index 0 is out of bounds for axis 0 with size 0

Searchsorted, argmax, and numba simply return a wrong value. However searchsorted and numba return an index that is not a valid index for the array.

The functions where, min, nonzero and calculate throw an exception. However only the exception for calculate actually says anything helpful.

That means one actually has to wrap these calls in an appropriate wrapper function that catches exceptions or invalid return values and handle appropriately, at least if you aren't sure if the value could be in the array.

Note: The calculate and searchsorted options only work in special conditions. The "calculate" function requires a constant step and the searchsorted requires the array to be sorted. So these could be useful in the right circumstances but aren't general solutions for this problem. In case you're dealing with sorted Python lists you might want to take a look at the bisect module instead of using Numpys searchsorted.

How do I collapse a table row in Bootstrap?

You can do this without any JavaScript involved

(Using accepted answer)


<table class="table table-bordered table-striped">
        <td><button class="btn" data-target="#collapseme" data-toggle="collapse" type="button">Click to expand</button></td>
        <td class="nopadding">
            <div class="collapse" id="collapseme">
                <div class="content">
                    Show me collapsed


.nopadding {
    padding: 0 !important;

.content {
    padding: 20px;

Disable Drag and Drop on HTML elements?

This is a fiddle I always use with my Web applications:

$('body').on('dragstart drop', function(e){
    return false;

It will prevent anything on your app being dragged and dropped. Depending on tour needs, you can replace body selector with any container that childrens should not be dragged.

laravel compact() and ->with()

Route::get('/', function () {
    return view('greeting', ['name' => 'James']);
        <h1>Hello, {{ $name }}</h1>


public function index($id)
    $category = Category::find($id);
    $topics = $category->getTopicPaginator();
    $message = Message::find(1);

    // here I would just use "->with([$category, $topics, $message])"
    return View::make('category.index')->with(compact('category', 'topics', 'message'));

Correct way to quit a Qt program?

If you're using Qt Jambi, this should work:


Using stored procedure output parameters in C#

Before changing stored procedure please check what is the output of your current one. In SQL Server Management run following:

DECLARE @NewId int
EXEC    @return_value = [dbo].[usp_InsertContract]
            @NewId OUTPUT

See what it returns. This may give you some hints of why your out param is not filled.

Gaussian filter in MATLAB

In MATLAB R2015a or newer, it is no longer necessary (or advisable from a performance standpoint) to use fspecial followed by imfilter since there is a new function called imgaussfilt that performs this operation in one step and more efficiently.

The basic syntax:

B = imgaussfilt(A,sigma) filters image A with a 2-D Gaussian smoothing kernel with standard deviation specified by sigma.

The size of the filter for a given Gaussian standard deviation (sigam) is chosen automatically, but can also be specified manually:

B = imgaussfilt(A,sigma,'FilterSize',[3 3]);

The default is 2*ceil(2*sigma)+1.

Additional features of imgaussfilter are ability to operate on gpuArrays, filtering in frequency or spacial domain, and advanced image padding options. It looks a lot like IPP... hmmm. Plus, there's a 3D version called imgaussfilt3.