Programs & Examples On #String aggregation

Simulating group_concat MySQL function in Microsoft SQL Server 2005?

Possibly too late to be of benefit now, but is this not the easiest way to do things?

SELECT     empName, projIDs = replace
                          ((SELECT Surname AS [data()]
                              FROM project_members
                              WHERE  empName = a.empName
                              ORDER BY empName FOR xml path('')), ' ', REQUIRED SEPERATOR)
FROM         project_members a
GROUP BY empName

How do I create a comma-separated list using a SQL query?

To be agnostic, drop back and punt.

Select as a_name, as r_name
  from ApplicationsResource ar, Applications a, Resources r
 where = ar.app_id
   and = ar.resource_id
 order by,;

Now user your server programming language to concatenate a_names while r_name is the same as the last time.

How to concatenate strings of a string field in a PostgreSQL 'group by' query?

If you are on Amazon Redshift, where string_agg is not supported, try using listagg.

SELECT company_id, listagg(EMPLOYEE, ', ') as employees
GROUP BY company_id;

How can I combine multiple rows into a comma-delimited list in Oracle?

In this example we are creating a function to bring a comma delineated list of distinct line level AP invoice hold reasons into one field for header level query:

 FUNCTION getHoldReasonsByInvoiceId (p_InvoiceId IN NUMBER) RETURN VARCHAR2


  v_HoldReasons   VARCHAR2 (1000);

  v_Count         NUMBER := 0;

  CURSOR v_HoldsCusror (p2_InvoiceId IN NUMBER)
     SELECT DISTINCT hold_reason
      WHERE status_flag NOT IN ('R') AND invoice_id = p2_InvoiceId;

  v_HoldReasons := ' ';

  FOR rHR IN v_HoldsCusror (p_InvoiceId)
     v_Count := v_COunt + 1;

     IF (v_Count = 1)
        v_HoldReasons := rHR.hold_reason;
        v_HoldReasons := v_HoldReasons || ', ' || rHR.hold_reason;
     END IF;

  RETURN v_HoldReasons;

How can multiple rows be concatenated into one in Oracle without creating a stored procedure?

From Oracle 11gR2, the LISTAGG clause should do the trick:

SELECT question_id,
       LISTAGG(element_id, ',') WITHIN GROUP (ORDER BY element_id)
GROUP BY question_id;

Beware if the resulting string is too big (more than 4000 chars for a VARCHAR2, for instance): from version 12cR2, we can use ON OVERFLOW TRUNCATE/ERROR to deal with this issue.

How to make a query with group_concat in sql server

Please run the below query, it doesn't requires STUFF and GROUP BY in your case:

    , A.maskname
    , A.schoolid
    , B.schoolname
    , CAST((
          SELECT  T.maskdetail+','
          FROM dbo.maskdetails T
          WHERE A.maskid = T.maskid
          FOR XML PATH(''))as varchar(max)) as maskdetail 
FROM dbo.tblmask A
JOIN B ON B.ID = A.schoolid

Postgresql GROUP_CONCAT equivalent?

Since 9.0 this is even easier:

       string_agg(some_column, ',')
FROM the_table

SQL Query to concatenate column values from multiple rows in Oracle

Try this code:

 SELECT XMLAGG(XMLELEMENT(E,fieldname||',')).EXTRACT('//text()') "FieldNames"

How to control the line spacing in UILabel

This should help with it. You can then assign your label to this custom class within the storyboard and use it's parameters directly within the properties:

open class SpacingLabel : UILabel {

    @IBInspectable open var lineHeight:CGFloat = 1 {
        didSet {
            let paragraphStyle = NSMutableParagraphStyle()
            paragraphStyle.lineSpacing = 1.0
            paragraphStyle.lineHeightMultiple = self.lineHeight
            paragraphStyle.alignment = self.textAlignment

            let attrString = NSMutableAttributedString(string: self.text!)
            attrString.addAttribute(NSAttributedStringKey.font, value: self.font, range: NSMakeRange(0, attrString.length))
            attrString.addAttribute(NSAttributedStringKey.paragraphStyle, value:paragraphStyle, range:NSMakeRange(0, attrString.length))
            self.attributedText = attrString

What is the easiest way to initialize a std::vector with hardcoded elements?

If you don't want to use boost, but want to enjoy syntax like

std::vector<int> v;

just include this chunk of code

template <class T> class vector_inserter{
    std::vector<T>& v;
    vector_inserter(std::vector<T>& v):v(v){}
    vector_inserter& operator,(const T& val){v.push_back(val);return *this;}
template <class T> vector_inserter<T> operator+=(std::vector<T>& v,const T& x){
    return vector_inserter<T>(v),x;

How do I link object files in C? Fails with "Undefined symbols for architecture x86_64"

I assume you are using gcc, to simply link object files do:

$ gcc -o output file1.o file2.o

To get the object-files simply compile using

$ gcc -c file1.c

this yields file1.o and so on.

If you want to link your files to an executable do

$ gcc -o output file1.c file2.c

“Unable to find manifest signing certificate in the certificate store” - even when add new key

Go to your project's "Properties" within visual studio. Then go to signing tab.

Then make sure Sign the Click Once manifests is turned off.

Updated Instructions:

Within your Solution Explorer:

  1. right click on your project
  2. click on properties
  3. usually on the left-hand side, select the "Signing" tab
  4. check off the Sign the ClickOnce manifests
  5. Make sure you save!

enter image description here

How do I use the built in password reset/change views with my own templates

You just need to wrap the existing functions and pass in the template you want. For example:

from django.contrib.auth.views import password_reset

def my_password_reset(request, template_name='path/to/my/template'):
    return password_reset(request, template_name)

To see this just have a look at the function declartion of the built in views:

Using File.listFiles with FileNameExtensionFilter

One-liner in java 8 syntax:

pdfTestDir.listFiles((dir, name) -> name.toLowerCase().endsWith(".txt"));

JavaScript associative array to JSON

I posted a fix for this here

You can use this function to modify JSON.stringify to encode arrays, just post it near the beginning of your script (check the link above for more detail):

// Upgrade for JSON.stringify, updated to allow arrays
    // Convert array to object
    var convArrToObj = function(array){
        var thisEleObj = new Object();
        if(typeof array == "object"){
            for(var i in array){
                var thisEle = convArrToObj(array[i]);
                thisEleObj[i] = thisEle;
        }else {
            thisEleObj = array;
        return thisEleObj;
    var oldJSONStringify = JSON.stringify;
    JSON.stringify = function(input){
        if(oldJSONStringify(input) == '[]')
            return oldJSONStringify(convArrToObj(input));
            return oldJSONStringify(input);

Javascript Regular Expression Remove Spaces

I would recommend you use the literal notation, and the \s character class:

return str.replace(/\s/g, '');

There's a difference between using the character class \s and just ' ', this will match a lot more white-space characters, for example '\t\r\n' etc.., looking for ' ' will replace only the ASCII 32 blank space.

The RegExp constructor is useful when you want to build a dynamic pattern, in this case you don't need it.

Moreover, as you said, "[\s]+" didn't work with the RegExp constructor, that's because you are passing a string, and you should "double escape" the back-slashes, otherwise they will be interpreted as character escapes inside the string (e.g.: "\s" === "s" (unknown escape)).

Check if a value exists in pandas dataframe index

df = pandas.DataFrame({'g':[1]}, index=['isStop'])


if 'g' in df.index:
    print("find g")

if 'isStop' in df.index:
    print("find a") 

"Exception has been thrown by the target of an invocation" error (mscorlib)

This is may have 2 reasons

1.I found the connection string error in my web.config file i had changed the connection string and its working.

  1. Connection string is proper then check with the control panel>services> SQL Server Browser > start or not

What does it mean if a Python object is "subscriptable" or not?

I had this same issue. I was doing

arr = []

So using [ was causing error. It should be arr.append("HI")

how to add values to an array of objects dynamically in javascript?

In Year 2019, we can use Javascript's ES6 Spread syntax to do it concisely and efficiently

data = [, {"label": 2, "value": 13}]


var data = [_x000D_
      {"label" : "1", "value" : 12},_x000D_
      {"label" : "1", "value" : 12},_x000D_
      {"label" : "1", "value" : 12},_x000D_
data = [, {"label" : "2", "value" : 14}] _x000D_

For your case (i know it was in 2011), we can do it with map() & forEach() like below

var lab = ["1","2","3","4"];_x000D_
var val = [42,55,51,22];_x000D_
//Using forEach()_x000D_
var data = [];_x000D_
val.forEach((v,i) => _x000D_
   data= [, {"label": lab[i], "value":v}]_x000D_
//Using map()_x000D_
var dataMap =,i) => _x000D_
 ({"label": lab[i], "value":v})_x000D_
console.log('data: ', data);_x000D_
console.log('dataMap : ', dataMap);

Can there be an apostrophe in an email address?

Yes, according to RFC 3696 apostrophes are valid as long as they come before the @ symbol.

"Least Astonishment" and the Mutable Default Argument

This "bug" gave me a lot of overtime work hours! But I'm beginning to see a potential use of it (but I would have liked it to be at the execution time, still)

I'm gonna give you what I see as a useful example.

def example(errors=[]):
    # statements
    # Something went wrong
    mistake = True
    if mistake:
        # Didn't work.. let's try again
        # This time it worked
    return errors

def tryToFixIt(err):
    err.append('Attempt to fix it')

def tryToFixItAnotherway(err):
    err.append('Attempt to fix it by another way')

def main():
    for item in range(2):
        errors = example()
    print '\n'.join(errors)


prints the following

Attempt to fix it
Attempt to fix it by another way
Attempt to fix it
Attempt to fix it by another way

How do I instantiate a Queue object in java?

Queue<String> qe=new LinkedList<String>();


Since Queue is an interface, you can't create an instance of it as you illustrated

strdup() - what does it do in C?

The most valuable thing it does is give you another string identical to the first, without requiring you to allocate memory (location and size) yourself. But, as noted, you still need to free it (but which doesn't require a quantity calculation, either.)

Converting string format to datetime in mm/dd/yyyy

You can change the format too by doing this

string fecha = DateTime.Now.ToString(format:"dd-MM-yyyy");

// this change the "/" for the "-"

Copy rows from one Datatable to another DataTable?

Copy Specified Rows from Table to another

// here dttablenew is a new Table  and dttableOld is table Which having the data 

dttableNew  = dttableOld.Clone();  

foreach (DataRow drtableOld in dttableOld.Rows)
   if (/*put some Condition */)

Get URL query string parameters

Here is my function to rebuild parts of the REFERRER's query string.

If the calling page already had a query string in its own URL, and you must go back to that page and want to send back some, not all, of that $_GET vars (e.g. a page number).

Example: Referrer's query string was ?foo=1&bar=2&baz=3 calling refererQueryString( 'foo' , 'baz' ) returns foo=1&baz=3":

function refererQueryString(/* var args */) {

    //Return empty string if no referer or no $_GET vars in referer available:
    if (!isset($_SERVER['HTTP_REFERER']) ||
        empty( $_SERVER['HTTP_REFERER']) ||
        empty(parse_url($_SERVER['HTTP_REFERER'], PHP_URL_QUERY ))) {

        return '';

    //Get URL query of referer (something like "threadID=7&page=8")
    $refererQueryString = parse_url(urldecode($_SERVER['HTTP_REFERER']), PHP_URL_QUERY);

    //Which values do you want to extract? (You passed their names as variables.)
    $args = func_get_args();

    //Get '[key=name]' strings out of referer's URL:
    $pairs = explode('&',$refererQueryString);

    //String you will return later:
    $return = '';

    //Analyze retrieved strings and look for the ones of interest:
    foreach ($pairs as $pair) {
        $keyVal = explode('=',$pair);
        $key = &$keyVal[0];
        $val = urlencode($keyVal[1]);
        //If you passed the name as arg, attach current pair to return string:
        if(in_array($key,$args)) {
            $return .= '&'. $key . '=' .$val;

    //Here are your returned 'key=value' pairs glued together with "&":
    return ltrim($return,'&');

//If your referer was 'page.php?foo=1&bar=2&baz=3'
//and you want to header() back to 'page.php?foo=1&baz=3'
//(no 'bar', only foo and baz), then apply:

header('Location: page.php?'.refererQueryString('foo','baz'));

Triggering a checkbox value changed event in DataGridView

I found a combination of the first two answers gave me what I needed. I used the CurrentCellDirtyStateChanged event and inspected the EditedFormattedValue.

private void dgv_CurrentCellDirtyStateChanged(object sender, EventArgs e)
   DataGridView dgv = (DataGridView)sender;
   DataGridViewCell cell = dgv.CurrentCell;
   if (cell.RowIndex >= 0 && cell.ColumnIndex == 3) // My checkbox column
        // If checkbox checked, copy value from col 1 to col 2
        if (dgv.Rows[cell.RowIndex].Cells[cell.ColumnIndex].EditedFormattedValue != null && dgv.Rows[cell.RowIndex].Cells[cell.ColumnIndex].EditedFormattedValue.Equals(true))
           dgv.Rows[cell.RowIndex].Cells[1].Value = dgv.Rows[cell.RowIndex].Cells[2].Value;

Get int value from enum in C#

Since enums can be declared with multiple primitive types, a generic extension method to cast any enum type can be useful.

enum Box

public static void UseEnum()
    int height = Box.HEIGHT.GetEnumValue<int>();
    int width = Box.WIDTH.GetEnumValue<int>();
    int depth = Box.DEPTH.GetEnumValue<int>();

public static T GetEnumValue<T>(this object e) => (T)e;

Create an instance of a class from a string

Probably my question should have been more specific. I actually know a base class for the string so solved it by:

ReportClass report = (ReportClass)Activator.CreateInstance(Type.GetType(reportClass));

The Activator.CreateInstance class has various methods to achieve the same thing in different ways. I could have cast it to an object but the above is of the most use to my situation.

Using reCAPTCHA on localhost

localhost works now. However, remember that after adding localhost to list of domain names, it takes up to 30 minutes to take effect (according to the help tip shown against the domain names list).

What is the meaning of @_ in Perl?

The question was what @_ means in Perl. The answer to that question is that, insofar as $_ means it in Perl, @_ similarly means they.

No one seems to have mentioned this critical aspect of its meaning — as well as theirs.

They’re consequently both used as pronouns, or sometimes as topicalizers.

They typically have nominal antecedents, although not always.

Convert string to variable name in JavaScript

You can access the window object as an associative array and set it that way

window["onlyVideo"] = "TEST";

Get last 30 day records from today date in SQL Server

I dont know why all these complicated answers are on here but this is what I would do

where pdate >= CURRENT_TIMESTAMP -30


addClass and removeClass in jQuery - not removing class

why not simplify it?


$('.clickable').on('click', function() {//on parent click
    $(this).removeClass('spot').addClass('grown');//use remove/add Class here because it needs to perform the same action every time, you don't want a toggle
}).children('.close_button').on('click', function(e) {//on close click
    e.stopPropagation();//stops click from triggering on parent
    $(this).parent().toggleClass('spot grown');//since this only appears when .grown is present, toggling will work great instead of add/remove Class and save some space

This way it's much easier to maintain.

made a fiddle:

How to use local docker images with Minikube?

To add to the previous answers, if you have a tarball image, you can simply load it to you local docker set of images docker image load -i /path/image.tar .Please remember to run it after eval $(minikube docker-env), since minikube does not share images with the locally installed docker engine.

jQuery .attr("disabled", "disabled") not working in Chrome

For me, none of these answers worked, but I finally found one that did.

I needed this for IE-

$('input:text').attr("disabled", 'disabled');

I also had to add this for Chrome and Firefox -


and this -

<style type="text/css">
    .notactive {
        pointer-events: none;
        cursor: default;

What's the use of "enum" in Java?

An enum type is a type whose fields consist of a fixed set of constants. Common examples include compass directions (values of NORTH, SOUTH, EAST, and WEST) and the days of the week.

public enum Day {

You should use enum types any time you need to represent a fixed set of constants. That includes natural enum types such as the planets in our solar system and data sets where you know all possible values at compile time—for example, the choices on a menu, command line flags, and so on.

Here is some code that shows you how to use the Day enum defined above:

public class EnumTest {
    Day day;

    public EnumTest(Day day) { = day;

    public void tellItLikeItIs() {
        switch (day) {
            case MONDAY:
                System.out.println("Mondays are bad.");

            case FRIDAY:
                System.out.println("Fridays are better.");

            case SATURDAY: case SUNDAY:
                System.out.println("Weekends are best.");

                System.out.println("Midweek days are so-so.");

    public static void main(String[] args) {
        EnumTest firstDay = new EnumTest(Day.MONDAY);
        EnumTest thirdDay = new EnumTest(Day.WEDNESDAY);
        EnumTest fifthDay = new EnumTest(Day.FRIDAY);
        EnumTest sixthDay = new EnumTest(Day.SATURDAY);
        EnumTest seventhDay = new EnumTest(Day.SUNDAY);

The output is:

Mondays are bad.
Midweek days are so-so.
Fridays are better.
Weekends are best.
Weekends are best.

Java programming language enum types are much more powerful than their counterparts in other languages. The enum declaration defines a class (called an enum type). The enum class body can include methods and other fields. The compiler automatically adds some special methods when it creates an enum. For example, they have a static values method that returns an array containing all of the values of the enum in the order they are declared. This method is commonly used in combination with the for-each construct to iterate over the values of an enum type. For example, this code from the Planet class example below iterates over all the planets in the solar system.

for (Planet p : Planet.values()) {
    System.out.printf("Your weight on %s is %f%n",
                      p, p.surfaceWeight(mass));

In addition to its properties and constructor, Planet has methods that allow you to retrieve the surface gravity and weight of an object on each planet. Here is a sample program that takes your weight on earth (in any unit) and calculates and prints your weight on all of the planets (in the same unit):

public enum Planet {
    MERCURY (3.303e+23, 2.4397e6),
    VENUS   (4.869e+24, 6.0518e6),
    EARTH   (5.976e+24, 6.37814e6),
    MARS    (6.421e+23, 3.3972e6),
    JUPITER (1.9e+27,   7.1492e7),
    SATURN  (5.688e+26, 6.0268e7),
    URANUS  (8.686e+25, 2.5559e7),
    NEPTUNE (1.024e+26, 2.4746e7);

    private final double mass;   // in kilograms
    private final double radius; // in meters
    Planet(double mass, double radius) {
        this.mass = mass;
        this.radius = radius;
    private double mass() { return mass; }
    private double radius() { return radius; }

    // universal gravitational constant  (m3 kg-1 s-2)
    public static final double G = 6.67300E-11;

    double surfaceGravity() {
        return G * mass / (radius * radius);
    double surfaceWeight(double otherMass) {
        return otherMass * surfaceGravity();
    public static void main(String[] args) {
        if (args.length != 1) {
            System.err.println("Usage: java Planet <earth_weight>");
        double earthWeight = Double.parseDouble(args[0]);
        double mass = earthWeight/EARTH.surfaceGravity();
        for (Planet p : Planet.values())
           System.out.printf("Your weight on %s is %f%n",
                             p, p.surfaceWeight(mass));

If you run Planet.class from the command line with an argument of 175, you get this output:

$ java Planet 175
Your weight on MERCURY is 66.107583
Your weight on VENUS is 158.374842
Your weight on EARTH is 175.000000
Your weight on MARS is 66.279007
Your weight on JUPITER is 442.847567
Your weight on SATURN is 186.552719
Your weight on URANUS is 158.397260
Your weight on NEPTUNE is 199.207413


How to remove duplicate white spaces in string using Java?

Try this - You have to import java.util.regex.*;

    Pattern pattern = Pattern.compile("\\s+");
    Matcher matcher = pattern.matcher(string);
    boolean check = matcher.find();
    String str = matcher.replaceAll(" ");

Where string is your string on which you need to remove duplicate white spaces

ASP.NET MVC 3 Razor - Adding class to EditorFor

No need to create custom template for MVC 4. Use TextBox instead of EditFor here special html attributes are not supported, it is only supported from MVC 5. TextBox is should support for MVC 4, I don't know about other version.

@Html.TextBox("test", "", new { @id = "signupform", @class = "form-control", @role = "form",@placeholder="Name" })

How to create an integer-for-loop in Ruby?

If you're doing this in your erb view (for Rails), be mindful of the <% and <%= differences. What you'd want is:

<% (1..x).each do |i| %>
  Code to display using <%= stuff %> that you want to display    
<% end %>

For plain Ruby, you can refer to:

How to get the type of a variable in MATLAB?

class() function is the equivalent of typeof()

You can also use isa() to check if a variable is of a particular type. If you want to be even more specific, you can use ischar(), isfloat(), iscell(), etc.

Casting a number to a string in TypeScript

"Casting" is different than conversion. In this case, window.location.hash will auto-convert a number to a string. But to avoid a TypeScript compile error, you can do the string conversion yourself:

window.location.hash = ""+page_number; 
window.location.hash = String(page_number); 

These conversions are ideal if you don't want an error to be thrown when page_number is null or undefined. Whereas page_number.toString() and page_number.toLocaleString() will throw when page_number is null or undefined.

When you only need to cast, not convert, this is how to cast to a string in TypeScript:

window.location.hash = <string>page_number; 
// or 
window.location.hash = page_number as string;

The <string> or as string cast annotations tell the TypeScript compiler to treat page_number as a string at compile time; it doesn't convert at run time.

However, the compiler will complain that you can't assign a number to a string. You would have to first cast to <any>, then to <string>:

window.location.hash = <string><any>page_number;
// or
window.location.hash = page_number as any as string;

So it's easier to just convert, which handles the type at run time and compile time:

window.location.hash = String(page_number); 

(Thanks to @RuslanPolutsygan for catching the string-number casting issue.)

Dynamically Add Variable Name Value Pairs to JSON Object

That's not JSON. It's just Javascript objects, and has nothing at all to do with JSON.

You can use brackets to set the properties dynamically. Example:

var obj = {};
obj['name'] = value;
obj['anotherName'] = anotherValue;

This gives exactly the same as creating the object with an object literal like this:

var obj = { name : value, anotherName : anotherValue };

If you have already added the object to the ips collection, you use one pair of brackets to access the object in the collection, and another pair to access the propery in the object:

ips[ipId] = {};
ips[ipId]['name'] = value;
ips[ipId]['anotherName'] = anotherValue;

Notice similarity with the code above, but that you are just using ips[ipId] instead of obj.

You can also get a reference to the object back from the collection, and use that to access the object while it remains in the collection:

ips[ipId] = {};
var obj = ips[ipId];
obj['name'] = value;
obj['anotherName'] = anotherValue;

You can use string variables to specify the names of the properties:

var name = 'name';
obj[name] = value;
name = 'anotherName';
obj[name] = anotherValue;

It's value of the variable (the string) that identifies the property, so while you use obj[name] for both properties in the code above, it's the string in the variable at the moment that you access it that determines what property will be accessed.

How to check for an undefined or null variable in JavaScript?

Since there is no single complete and correct answer, I will try to summarize:

In general, the expression:

if (typeof(variable) != "undefined" && variable != null)

cannot be simplified, because the variable might be undeclared so omitting the typeof(variable) != "undefined" would result in ReferenceError. But, you can simplify the expression according to the context:

If the variable is global, you can simplify to:

if (window.variable != null)

If it is local, you can probably avoid situations when this variable is undeclared, and also simplify to:

if (variable != null)

If it is object property, you don't have to worry about ReferenceError:

if ( != null)

What is the yield keyword used for in C#?

Intuitively, the keyword returns a value from the function without leaving it, i.e. in your code example it returns the current item value and then resumes the loop. More formally, it is used by the compiler to generate code for an iterator. Iterators are functions that return IEnumerable objects. The MSDN has several articles about them.

jquery draggable: how to limit the draggable area?

See excerpt from official documentation for containment option:


Default: false

Constrains dragging to within the bounds of the specified element or region.
Multiple types supported:

  • Selector: The draggable element will be contained to the bounding box of the first element found by the selector. If no element is found, no containment will be set.
  • Element: The draggable element will be contained to the bounding box of this element.
  • String: Possible values: "parent", "document", "window".
  • Array: An array defining a bounding box in the form [ x1, y1, x2, y2 ].

Code examples:
Initialize the draggable with the containment option specified:

$( ".selector" ).draggable({
    containment: "parent" 

Get or set the containment option, after initialization:

// Getter
var containment = $( ".selector" ).draggable( "option", "containment" );
// Setter
$( ".selector" ).draggable( "option", "containment", "parent" );

How to disable GCC warnings for a few lines of code

Rather than silencing the warnings, gcc style is usually to use either standard C constructs or the __attribute__ extension to tell the compiler more about your intention. For instance, the warning about assignment used as a condition is suppressed by putting the assignment in parentheses, i.e. if ((p=malloc(cnt))) instead of if (p=malloc(cnt)). Warnings about unused function arguments can be suppressed by some odd __attribute__ I can never remember, or by self-assignment, etc. But generally I prefer just globally disabling any warning option that generates warnings for things that will occur in correct code.

How to determine MIME type of file in android?

MimeTypeMap may not recognize some file extensions like flv,mpeg,3gpp,cpp. So you need to think how to expand the MimeTypeMap for maintaining your code. Here is such an example.

Plus, here is a complete list of mime types

http: //

Solving "adb server version doesn't match this client" error

It seems there are 2 adb version in your system. Please find them out and keep the adb in your Android SDK folder only, delete all others folders that including adb file. You can find out which adb you are using from Application Monitor:

enter image description here

It might be a problem if the adb is not the one in you Android SDK folder.

In my case, I found I was running adb from here:

/Library/Application Support/RSupport/Mobizen2

after deleting the Mobizen2 folder, then all adb commands work fine.

Why Response.Redirect causes System.Threading.ThreadAbortException?

i even tryed to avoid this, just in case doing the Abort on the thread manually, but i rather leave it with the "CompleteRequest" and move on - my code has return commands after redirects anyway. So this can be done

public static void Redirect(string VPathRedirect, global::System.Web.UI.Page Sender)
    Sender.Response.Redirect(VPathRedirect, false);

Mapping many-to-many association table with extra column(s)

Since the SERVICE_USER table is not a pure join table, but has additional functional fields (blocked), you must map it as an entity, and decompose the many to many association between User and Service into two OneToMany associations : One User has many UserServices, and one Service has many UserServices.

You haven't shown us the most important part : the mapping and initialization of the relationships between your entities (i.e. the part you have problems with). So I'll show you how it should look like.

If you make the relationships bidirectional, you should thus have

class User {
    @OneToMany(mappedBy = "user")
    private Set<UserService> userServices = new HashSet<UserService>();

class UserService {
    @JoinColumn(name = "user_id")
    private User user;

    @JoinColumn(name = "service_code")
    private Service service;

    @Column(name = "blocked")
    private boolean blocked;

class Service {
    @OneToMany(mappedBy = "service")
    private Set<UserService> userServices = new HashSet<UserService>();

If you don't put any cascade on your relationships, then you must persist/save all the entities. Although only the owning side of the relationship (here, the UserService side) must be initialized, it's also a good practice to make sure both sides are in coherence.

User user = new User();
Service service = new Service();
UserService userService = new UserService();



How to resolve the "EVP_DecryptFInal_ex: bad decrypt" during file decryption

My case, the server was encrypting with padding disabled. But the client was trying to decrypt with the padding enabled.

While using EVP_CIPHER*, by default the padding is enabled. To disable explicitly we need to do

EVP_CIPHER_CTX_set_padding(context, 0);

So non matching padding options can be one reason.

Multiple cases in switch statement

In C# 7 (available by default in Visual Studio 2017/.NET Framework 4.6.2), range-based switching is now possible with the switch statement and would help with the OP's problem.


int i = 5;

switch (i)
    case int n when (n >= 7):
        Console.WriteLine($"I am 7 or above: {n}");

    case int n when (n >= 4 && n <= 6 ):
        Console.WriteLine($"I am between 4 and 6: {n}");

    case int n when (n <= 3):
        Console.WriteLine($"I am 3 or less: {n}");

// Output: I am between 4 and 6: 5


  • The parentheses ( and ) are not required in the when condition, but are used in this example to highlight the comparison(s).
  • var may also be used in lieu of int. For example: case var n when n >= 7:.

How to prevent form resubmission when page is refreshed (F5 / CTRL+R)

You can prevent form resubmission via a session variable.

First you have to set rand() in a textbox and $_SESSION['rand'] on the form page:

<form action="" method="post">
 <input type="hidden" value="<?php echo $rand; ?>" name="randcheck" />
   Your Form's Other Field 
 <input type="submit" name="submitbtn" value="submit" />

After that check $_SESSION['rand'] with textbox $_POST['randcheck'] value like this:

if(isset($_POST['submitbtn']) && $_POST['randcheck']==$_SESSION['rand'])
    // Your code here

Make sure you start the session on every file you are using it with session_start()

How do I implement JQuery.noConflict() ?

It's typically used if you are using another library that uses $.

In order to still use the $ symbol for jQuery, I typically use:

  // jQuery code here
}); Connection refused

In my case, I had to put a check mark near Expose daemon on tcp://localhost:2375 without TLS in docker setting (on the right side of the task bar, right click on docker, select setting)

ORA-12170: TNS:Connect timeout occurred


Connection Timeout errors ORA-3135 and ORA-3136 A connection timeout error can be issued when an attempt to connect to the database does not complete its connection and authentication phases within the time period allowed by the following: SQLNET.INBOUND_CONNECT_TIMEOUT and/or INBOUND_CONNECT_TIMEOUT_ server-side parameters.

Starting with Oracle 10.2, the default for these parameters is 60 seconds where in previous releases it was 0, meaning no timeout.

On a timeout, the client program will receive the ORA-3135 (or possibly TNS-3135) error:

ORA-3135 connection lost contact

and the database will log the ORA-3136 error in its alert.log:

... Sat May 10 02:21:38 2008 WARNING: inbound connection timed out (ORA-3136) ...

  • Authentication SQL

When a database session is in the authentication phase, it will issue a sequence of SQL statements. The authentication is not complete until all these are parsed, executed, fetched completely. Some of the SQL statements in this list e.g. on 10.2 are:

select value$ from props$ where name = 'GLOBAL_DB_NAME'

select privilege#,level from sysauth$ connect by grantee#=prior privilege# 
and privilege#>0 start with grantee#=:1 and privilege#>0


select privilege# from sysauth$ where (grantee#=:1 or grantee#=1) and privilege#>0


NOTE: The list of SQL above is not complete and does not represent the ordering of the authentication SQL . Differences may also exist from release to release.

  • Hangs during Authentication

The above SQL statements need to be Parsed, Executed and Fetched as happens for all SQL inside an Oracle Database. It follows that any problem encountered during these phases which appears as a hang or severe slow performance may result in a timeout.

Symptoms of such hangs will be seen by the authenticating session as waits for: • cursor: pin S wait on X • latch: row cache objects • row cache lock Other types of wait events are possible; this list may not be complete.

The issue here is that the authenticating session is blocked waiting to get a shared resource which is held by another session inside the database. That blocker session is itself occupied in a long-running activity (or its own hang) which prevents it from releasing the shared resource needed by the authenticating session in a timely fashion. This results in the timeout being eventually reported to the authenticating session.

  • Troubleshooting of Authentication hangs

In such situations, we need to find out the blocker process holding the shared resource needed by the authenticating session in order to see what is happening to it.

Typical diagnostics used in such cases are the following:

  1. Three consecutive systemstate dumps at level 266 during the time that one or more authenticating sessions are blocked. It is likely that the blocking session will have caused timeouts to more than one connection attempt. Hence, systemstate dumps can be useful even when the time needed to generate them exceeds the period of a single timeout e.g. 60 sec:
      $ sqlplus -prelim '/ as sysdba' 

       oradebug setmypid 
       oradebug unlimit 
       oradebug dump systemstate 266 
       ...wait 90 seconds 
       oradebug dump systemstate 266 
       ...wait 90 seconds 
       oradebug dump systemstate 266 
  • ASH reports covering e.g. 10-15 minutes of a time period during which several timeout errors were seen.
  • If possible, Two consecutive queries on V$LATCHHOLDER view for the case where the shared resource being waited for is a latch. select * from v$latchholder; The systemstate dumps should help in identifying the blocker session. Level 266 will show us in what code it is executing which may help in locating any existing bug as the root cause.

Examples of issues which can result in Authentication hangs

  • Unpublished Bug 6879763 shared pool simulator bug fixed by patch for unpublished Bug 6966286 see Note 563149.1
  • Unpublished Bug 7039896 workaround parameter _enable_shared_pool_durations=false see Note 7039896.8

  • Other approaches to avoid the problem

In some cases, it may be possible to avoid problems with Authentication SQL by pinning such statements in the Shared Pool soon after the instance is started and they are freshly loaded. You can use the following artcile to advise on this: Document 726780.1 How to Pin a Cursor in the Shared Pool using DBMS_SHARED_POOL.KEEP

Pinning will prevent them from being flushed out due to inactivity and aging and will therefore prevent them for needing to be reloaded in the future i.e. needing to be reparsed and becoming susceptible to Authentication hang issues.

Mask for an Input to allow phone numbers?

Combining Günter Zöchbauer's answer with good-old vanilla-JS, here is a directive with two lines of logic that supports (123) 456-7890 format.

Reactive Forms: Plunk

import { Directive, Output, EventEmitter } from "@angular/core";
import { NgControl } from "@angular/forms";

  selector: '[formControlName][phone]',
  host: {
    '(ngModelChange)': 'onInputChange($event)'
export class PhoneMaskDirective {

  @Output() rawChange:EventEmitter<string> = new EventEmitter<string>();

  constructor(public model: NgControl) {}

  onInputChange(value) {
        var x = value.replace(/\D/g, '').match(/(\d{0,3})(\d{0,3})(\d{0,4})/);
        var y = !x[2] ? x[1] : '(' + x[1] + ') ' + x[2] + (x[3] ? '-' + x[3] : '');


Template-driven Forms: Plunk

import { Directive } from "@angular/core";
import { NgControl } from "@angular/forms";

  selector: '[ngModel][phone]',
  host: {
    '(ngModelChange)': 'onInputChange($event)'
export class PhoneMaskDirective {

  constructor(public model: NgControl) {}

  onInputChange(value) {
        var x = value.replace(/\D/g, '').match(/(\d{0,3})(\d{0,3})(\d{0,4})/);
        value = !x[2] ? x[1] : '(' + x[1] + ') ' + x[2] + (x[3] ? '-' + x[3] : '');


How to center an element horizontally and vertically

Source Link

Method 1) Display type flex

     display: flex;
     justify-content: center;
     align-items: center;

Method 2) 2D Transform

.child-element {
   top: 50%;
   left: 50%;
   transform: translate(-50% , -50%);
   position: absolute;

See other methods here

MySQL Data Source not appearing in Visual Studio

I tried to install to VS 2015 using the Web installer. It seemed to work, but there was still no MySQL entry for Data Connections. I ended up going to, using it to uninstall then re-install the connector. Not it works as expected.

how to open .mat file without using MATLAB?

There's a really nice easy way to do this in Macintosh OsX. A fellow has made a quicklook plugin (command-space) that renders .mat formats so you can view the variables inside etc. Quite useful!

How to Maximize a firefox browser window using Selenium WebDriver with node.js

Try this:

self.ff_driver = Firefox()

Error when trying to access XAMPP from a network

This answer is for XAMPP on Ubuntu.

The manual for installation and download is on (site official)

After to start XAMPP simply call this command:

sudo /opt/lampp/lampp start

You should now see something like this on your screen:

Starting XAMPP 1.8.1...
LAMPP: Starting Apache...
LAMPP: Starting MySQL...
LAMPP started.

If you have this

Starting XAMPP for Linux 1.8.1...                                                             
XAMPP: Another web server daemon is already running.                                          
XAMPP: Another MySQL daemon is already running.                                               
XAMPP: Starting ProFTPD...                                                                    
XAMPP for Linux started

. The solution is

sudo /etc/init.d/apache2 stop
sudo /etc/init.d/mysql stop

And the restast with sudo //opt/lampp/lampp restart

You to fix most of the security weaknesses simply call the following command:

/opt/lampp/lampp security

After the change this file

sudo kate //opt/lampp/etc/extra/httpd-xampp.conf

Find and replace on

# New XAMPP security concept
<LocationMatch "^/(?i:(?:xampp|security|licenses|phpmyadmin|webalizer|server-status|server-info))">
    Order deny,allow
    Deny from all
    Allow from ::1 
    Allow from all
    #   fc00::/7 \
    #   fe80::/10

    ErrorDocument 403 /error/XAMPP_FORBIDDEN.html.var

Access IP Camera in Python OpenCV

First find out your IP camera's streaming url, like whether it's RTSP/HTTP etc.

Code changes will be as follows:

cap = cv2.VideoCapture("ipcam_streaming_url")

For example:

cap = cv2.VideoCapture("")

sudo service mongodb restart gives "unrecognized service error" in ubuntu 14.0.4

You can use mongod command instead of mongodb, if you find any issue regarding dbpath in mongo you can use my answer in the link below.

How to escape indicator characters (i.e. : or - ) in YAML

I came here trying to get my Azure DevOps Command Line task working. The thing that worked for me was using the pipe (|) character. Using > did not work.


- task: CmdLine@2
    script: |
      echo "Selecting Mono version..."
      /bin/bash -c "sudo $AGENT_HOMEDIRECTORY/scripts/ 5_18_1"
      echo "Selecting Xcode version..."
      /bin/bash -c "echo '##vso[task.setvariable variable=MD_APPLE_SDK_ROOT;]'/Applications/;sudo xcode-select --switch /Applications/"

Loop through columns and add string lengths as new columns

You need to use [[, the programmatic equivalent of $. Otherwise, for example, when i is col1, R will look for df$i instead of df$col1.

for(i in names(df)){
  df[[paste(i, 'length', sep="_")]] <- str_length(df[[i]])

What is the difference between functional and non-functional requirements?

A functional requirement describes what a software system should do, while non-functional requirements place constraints on how the system will do so.

Let me elaborate.

An example of a functional requirement would be:

  • A system must send an email whenever a certain condition is met (e.g. an order is placed, a customer signs up, etc).

A related non-functional requirement for the system may be:

  • Emails should be sent with a latency of no greater than 12 hours from such an activity.

The functional requirement is describing the behavior of the system as it relates to the system's functionality. The non-functional requirement elaborates a performance characteristic of the system.

Typically non-functional requirements fall into areas such as:

  • Accessibility
  • Capacity, current and forecast
  • Compliance
  • Documentation
  • Disaster recovery
  • Efficiency
  • Effectiveness
  • Extensibility
  • Fault tolerance
  • Interoperability
  • Maintainability
  • Privacy
  • Portability
  • Quality
  • Reliability
  • Resilience
  • Response time
  • Robustness
  • Scalability
  • Security
  • Stability
  • Supportability
  • Testability

A more complete list is available at Wikipedia's entry for non-functional requirements.

Non-functional requirements are sometimes defined in terms of metrics (i.e. something that can be measured about the system) to make them more tangible. Non-functional requirements may also describe aspects of the system that don't relate to its execution, but rather to its evolution over time (e.g. maintainability, extensibility, documentation, etc.).

Having services in React application

Same situation: Having done multiple Angular projects and moving to React, not having a simple way to provide services through DI seems like a missing piece (the particulars of the service aside).

Using context and ES7 decorators we can come close:

Seems these guys have taken it a step further / in a different direction:

Still feels like working against the grain. Will revisit this answer in 6 months time after undertaking a major React project.

EDIT: Back 6 months later with some more React experience. Consider the nature of the logic:

  1. Is it tied (only) to UI? Move it into a component (accepted answer).
  2. Is it tied (only) to state management? Move it into a thunk.
  3. Tied to both? Move to separate file, consume in component through a selector and in thunks.

Some also reach for HOCs for reuse but for me the above covers almost all use cases. Also, consider scaling state management using ducks to keep concerns separate and state UI-centric.

Get text of the selected option with jQuery

You could actually put the value = to the text and then do

        val = $j("#select_2 option:selected").html();

Or what I did on a similar case was

<select name="options[2]" id="select_2" onChange="JavascriptMethod()">
  with you're options here

With this second option you should have a undefined. Give me feedback if it worked :)


Authenticated HTTP proxy with Java

But, setting only that parameters, the authentication don't works.

Are necessary to add to that code the following:

final String authUser = "myuser";
final String authPassword = "secret";

System.setProperty("http.proxyHost", "hostAddress");
System.setProperty("http.proxyPort", "portNumber");
System.setProperty("http.proxyUser", authUser);
System.setProperty("http.proxyPassword", authPassword);

  new Authenticator() {
    public PasswordAuthentication getPasswordAuthentication() {
      return new PasswordAuthentication(authUser, authPassword.toCharArray());

How do I force git to use LF instead of CR+LF under windows?

You can find the solution to this problem at:

Simplified description of how you can solve this problem on windows:

Global settings for line endings The git config core.autocrlf command is used to change how Git handles line endings. It takes a single argument.

On Windows, you simply pass true to the configuration. For example: C:>git config --global core.autocrlf true

Good luck, I hope I helped.

Storing Data in MySQL as JSON

CouchDB and MySQL are two very different beasts. JSON is the native way to store stuff in CouchDB. In MySQL, the best you could do is store JSON data as text in a single field. This would entirely defeat the purpose of storing it in an RDBMS and would greatly complicate every database transaction.


Having said that, FriendFeed seemed to use an extremely custom schema on top of MySQL. It really depends on what exactly you want to store, there's hardly one definite answer on how to abuse a database system so it makes sense for you. Given that the article is very old and their main reason against Mongo and Couch was immaturity, I'd re-evaluate these two if MySQL doesn't cut it for you. They should have grown a lot by now.

How to add facebook share button on my website?

For your own specific server or different pages & image button you could use something like this (PHP only)

<a href="'.$_SERVER['SERVER_NAME'].'" target="_blank"><img src="" /></a>

I cannot share the snippet with this but you will get the idea...

How can I create an array with key value pairs?

You can create the single value array key-value as

$new_row = array($row["datasource_id"]=>$row["title"]);

inside while loop, and then use array_merge function in loop to combine the each new $new_row array.

What is monkey patching?

First: monkey patching is an evil hack (in my opinion).

It is often used to replace a method on the module or class level with a custom implementation.

The most common usecase is adding a workaround for a bug in a module or class when you can't replace the original code. In this case you replace the "wrong" code through monkey patching with an implementation inside your own module/package.

How to share my Docker-Image without using the Docker-Hub?


More recently, there is Amazon AWS ECR (Elastic Container Registry), which provides a Docker image registry to which you can control access by means of the AWS IAM access management service. ECR can also run a CVE (vulnerabilities) check on your image when you push it.

Once you create your ECR, and obtain the "URL" you can push and pull as required, subject to the permissions you create: hence making it private or public as you wish.

Pricing is by amount of data stored, and data transfer costs.

[Original answer]

If you do not want to use the Docker Hub itself, you can host your own Docker repository under Artifactory by JFrog:

which will then run on your own server(s).

Other hosting suppliers are available, eg CoreOS:

which bought

Set 4 Space Indent in Emacs in Text Mode

Have you tried

(setq  tab-width  4)

Split string on whitespace in Python

Using split() will be the most Pythonic way of splitting on a string.

It's also useful to remember that if you use split() on a string that does not have a whitespace then that string will be returned to you in a list.


>>> "ark".split()

How to use Tomcat 8 in Eclipse?

Alternatively we can use eclipse update site (Help -> Install New Features -> Add Site (urls below) -> Select desired Features).

For Luna:

For Kepler:

For Helios:

For older version:

Passing an Object from an Activity to a Fragment

In your activity class:

public class BasicActivity extends Activity {

private ComplexObject co;

protected void onCreate(Bundle savedInstanceState) {

    co=new ComplexObject();
    getIntent().putExtra("complexObject", co);

    FragmentManager fragmentManager = getFragmentManager();
    Fragment1 f1 = new Fragment1();
            .replace(, f1).commit();


Note: Your object should implement Serializable interface

Then in your fragment :

public class Fragment1 extends Fragment {

ComplexObject co;

public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    Intent i = getActivity().getIntent();

    co = (ComplexObject) i.getSerializableExtra("complexObject");

    View view = inflater.inflate(R.layout.test_page, container, false);
    TextView textView = (TextView) view.findViewById(;

    return view;

Nested attributes unpermitted parameters

If you use a JSONB field, you must convert it to JSON with .to_json (ROR)

Test if characters are in a string

Use the grepl function

grepl( needle, haystack, fixed = TRUE)

like so:

grepl(value, chars, fixed = TRUE)

Use ?grepl to find out more.

Boolean Field in Oracle

In our databases we use an enum that ensures we pass it either TRUE or FALSE. If you do it either of the first two ways it is too easy to either start adding new meaning to the integer without going through a proper design, or ending up with that char field having Y, y, N, n, T, t, F, f values and having to remember which section of code uses which table and which version of true it is using.

How to read Excel cell having Date with Apache POI?

Yes, I understood your problem. If is difficult to identify cell has Numeric or Data value.

If you want data in format that shows in Excel, you just need to format cell using DataFormatter class.

DataFormatter dataFormatter = new DataFormatter();
String cellStringValue = dataFormatter.formatCellValue(row.getCell(0));
System.out.println ("Is shows data as show in Excel file" + cellStringValue);  // Here it automcatically format data based on that cell format.
// No need for extra efforts 

Converting .NET DateTime to JSON

What is returned is milliseconds since epoch. You could do:

var d = new Date();

On how to format the date exactly as you want, see full Date reference at

You could strip the non-digits by either parsing the integer (as suggested here):

var date = new Date(parseInt(jsonDate.substr(6)));

Or applying the following regular expression (from Tominator in the comments):

var jsonDate = jqueryCall();  // returns "/Date(1245398693390)/"; 
var re = /-?\d+/; 
var m = re.exec(jsonDate); 
var d = new Date(parseInt(m[0]));

Fastest way to flatten / un-flatten nested JSON objects

ES6 version:

const flatten = (obj, path = '') => {        
    if (!(obj instanceof Object)) return {[path.replace(/\.$/g, '')]:obj};

    return Object.keys(obj).reduce((output, key) => {
        return obj instanceof Array ? 
             {...output, ...flatten(obj[key], path +  '[' + key + '].')}:
             {...output, ...flatten(obj[key], path + key + '.')};
    }, {});



Getting the Username from the HKEY_USERS values

It is possible to query this information from WMI. The following command will output a table with a row for every user along with the SID for each user.

wmic useraccount get name,sid

You can also export this information to CSV:

wmic useraccount get name,sid /format:csv > output.csv

I have used this on Vista and 7. For more information see WMIC - Take Command-line Control over WMI.

When do you use Git rebase instead of Git merge?

TLDR: It depends on what is most important - a tidy history or a true representation of the sequence of development

If a tidy history is the most important, then you would rebase first and then merge your changes, so it is clear exactly what the new code is. If you have already pushed your branch, don't rebase unless you can deal with the consequences.

If true representation of sequence is the most important, you would merge without rebasing.

Merge means: Create a single new commit that merges my changes into the destination. Note: This new commit will have two parents - the latest commit from your string of commits and the latest commit of the other branch you're merging.

Rebase means: Create a whole new series of commits, using my current set of commits as hints. In other words, calculate what my changes would have looked like if I had started making them from the point I'm rebasing on to. After the rebase, therefore, you might need to re-test your changes and during the rebase, you would possibly have a few conflicts.

Given this, why would you rebase? Just to keep the development history clear. Let's say you're working on feature X and when you're done, you merge your changes in. The destination will now have a single commit that would say something along the lines of "Added feature X". Now, instead of merging, if you rebased and then merged, the destination development history would contain all the individual commits in a single logical progression. This makes reviewing changes later on much easier. Imagine how hard you'd find it to review the development history if 50 developers were merging various features all the time.

That said, if you have already pushed the branch you're working on upstream, you should not rebase, but merge instead. For branches that have not been pushed upstream, rebase, test and merge.

Another time you might want to rebase is when you want to get rid of commits from your branch before pushing upstream. For example: Commits that introduce some debugging code early on and other commits further on that clean that code up. The only way to do this is by performing an interactive rebase: git rebase -i <branch/commit/tag>

UPDATE: You also want to use rebase when you're using Git to interface to a version control system that doesn't support non-linear history (Subversion for example). When using the git-svn bridge, it is very important that the changes you merge back into Subversion are a sequential list of changes on top of the most recent changes in trunk. There are only two ways to do that: (1) Manually re-create the changes and (2) Using the rebase command, which is a lot faster.

UPDATE 2: One additional way to think of a rebase is that it enables a sort of mapping from your development style to the style accepted in the repository you're committing to. Let's say you like to commit in small, tiny chunks. You have one commit to fix a typo, one commit to get rid of unused code and so on. By the time you've finished what you need to do, you have a long series of commits. Now let's say the repository you're committing to encourages large commits, so for the work you're doing, one would expect one or maybe two commits. How do you take your string of commits and compress them to what is expected? You would use an interactive rebase and squash your tiny commits into fewer larger chunks. The same is true if the reverse was needed - if your style was a few large commits, but the repository demanded long strings of small commits. You would use a rebase to do that as well. If you had merged instead, you have now grafted your commit style onto the main repository. If there are a lot of developers, you can imagine how hard it would be to follow a history with several different commit styles after some time.

UPDATE 3: Does one still need to merge after a successful rebase? Yes, you do. The reason is that a rebase essentially involves a "shifting" of commits. As I've said above, these commits are calculated, but if you had 14 commits from the point of branching, then assuming nothing goes wrong with your rebase, you will be 14 commits ahead (of the point you're rebasing onto) after the rebase is done. You had a branch before a rebase. You will have a branch of the same length after. You still need to merge before you publish your changes. In other words, rebase as many times as you want (again, only if you have not pushed your changes upstream). Merge only after you rebase.

Difference between object and class in Scala

In scala, there is no static concept. So scala creates a singleton object to provide entry point for your program execution. If you don't create singleton object, your code will compile successfully but will not produce any output. Methods declared inside Singleton Object are accessible globally. A singleton object can extend classes and traits.

Scala Singleton Object Example

object Singleton{  
    def main(args:Array[String]){  
        SingletonObject.hello()         // No need to create object.  

object SingletonObject{  
    def hello(){  
        println("Hello, This is Singleton Object")  


Hello, This is Singleton Object

In scala, when you have a class with same name as singleton object, it is called companion class and the singleton object is called companion object.

The companion class and its companion object both must be defined in the same source file.

Scala Companion Object Example

class ComapanionClass{  
    def hello(){  
        println("Hello, this is Companion Class.")  
object CompanoinObject{  
    def main(args:Array[String]){  
        new ComapanionClass().hello()  
        println("And this is Companion Object.")  


Hello, this is Companion Class.
And this is Companion Object.

In scala, a class can contain:

1. Data member

2. Member method

3. Constructor Block

4. Nested class

5. Super class information etc.

You must initialize all instance variables in the class. There is no default scope. If you don't specify access scope, it is public. There must be an object in which main method is defined. It provides starting point for your program. Here, we have created an example of class.

Scala Sample Example of Class

class Student{  
    var id:Int = 0;                         // All fields must be initialized  
    var name:String = null;  
object MainObject{  
    def main(args:Array[String]){  
        var s = new Student()               // Creating an object  
        println(" ";  

I am sorry, I am too late but I hope it will help you.

Get counts of all tables in a schema

This can be done with a single statement and some XML magic:

select table_name, 
       to_number(extractvalue(xmltype(dbms_xmlgen.getxml('select count(*) c from '||owner||'.'||table_name)),'/ROWSET/ROW/C')) as count
from all_tables
where owner = 'FOOBAR'

Preventing console window from closing on Visual Studio C/C++ Console application

Right click on your project

Properties > Configuration Properties > Linker > System

Select Console (/SUBSYSTEM:CONSOLE) in SubSystem option or you can just type Console in the text field!

Now try should work

Get the last item in an array

To prevent removing last item from origin array you could use


Mostly supported of all browsers (ES6)

Best way to strip punctuation from a string

A one-liner might be helpful in not very strict cases:

''.join([c for c in s if c.isalnum() or c.isspace()])

Programmatically create a UIView with color gradient

This is my recommended approach.

To promote reusability, I'd say create a category of CAGradientLayer and add your desired gradients as class methods. Specify them in the header file like this :

#import <QuartzCore/QuartzCore.h>

@interface CAGradientLayer (SJSGradients)

+ (CAGradientLayer *)redGradientLayer;
+ (CAGradientLayer *)blueGradientLayer;
+ (CAGradientLayer *)turquoiseGradientLayer;
+ (CAGradientLayer *)flavescentGradientLayer;
+ (CAGradientLayer *)whiteGradientLayer;
+ (CAGradientLayer *)chocolateGradientLayer;
+ (CAGradientLayer *)tangerineGradientLayer;
+ (CAGradientLayer *)pastelBlueGradientLayer;
+ (CAGradientLayer *)yellowGradientLayer;
+ (CAGradientLayer *)purpleGradientLayer;
+ (CAGradientLayer *)greenGradientLayer;


Then in your implementation file, specify each gradient with this syntax :

+ (CAGradientLayer *)flavescentGradientLayer
    UIColor *topColor = [UIColor colorWithRed:1 green:0.92 blue:0.56 alpha:1];
    UIColor *bottomColor = [UIColor colorWithRed:0.18 green:0.18 blue:0.18 alpha:1];

    NSArray *gradientColors = [NSArray arrayWithObjects:(id)topColor.CGColor, (id)bottomColor.CGColor, nil];
    NSArray *gradientLocations = [NSArray arrayWithObjects:[NSNumber numberWithInt:0.0],[NSNumber numberWithInt:1.0], nil];

    CAGradientLayer *gradientLayer = [CAGradientLayer layer];
    gradientLayer.colors = gradientColors;
    gradientLayer.locations = gradientLocations;

    return gradientLayer;

Then simply import this category in your ViewController or any other required subclass, and use it like this :

CAGradientLayer *backgroundLayer = [CAGradientLayer purpleGradientLayer];
backgroundLayer.frame = self.view.frame;
[self.view.layer insertSublayer:backgroundLayer atIndex:0];

How do I select elements of an array given condition?

Actually I would do it this way:

L1 is the index list of elements satisfying condition 1;(maybe you can use somelist.index(condition1) or np.where(condition1) to get L1.)

Similarly, you get L2, a list of elements satisfying condition 2;

Then you find intersection using intersect(L1,L2).

You can also find intersection of multiple lists if you get multiple conditions to satisfy.

Then you can apply index in any other array, for example, x.

AngularJS directive does not update on scope variable changes

I know this an old subject but in case any finds this like myself:

I used the following code when i needed my directive to update values when the "parent scope" updated. Please by all means correct me if am doing something wrong as i am still learning angular, but this did what i needed;


directive('dateRangePrint', function(){
    return {
        restrict: 'E',
        //still using the single dir binding
            From: '@rangeFrom',
            To: '@rangeTo',
            format: '@format'
        controller: function($scope, $element){

            $scope.viewFrom = function(){
                    return formatDate($scope.From, $scope.format);

            $scope.viewTo = function(){
                    return formatDate($scope.To, $scope.format);

            function formatDate(date, format){
                format = format || 'DD-MM-YYYY';

                //do stuff to date...

                return date.format(format);

        replace: true,
        // note the parenthesis after scope var
        template: '<span>{{ viewFrom() }} - {{ viewTo() }}</span>'

How to enable Logger.debug() in Log4j

Here's a quick one-line hack that I occasionally use to temporarily turn on log4j debug logging in a JUnit test:


or if you want to avoid adding imports:


Note: this hack doesn't work in log4j2 because setLevel has been removed from the API, and there doesn't appear to be equivalent functionality.

popup form using html/javascript/css

Live Demo

Sounds like you might want a light box,and since you didnt tag your question with jQuery included is a pure JS example of how to make one.


var opener = document.getElementById("opener");

opener.onclick = function(){

    var lightbox = document.getElementById("lightbox"),
        dimmer = document.createElement("div"); =  window.innerWidth + 'px'; = window.innerHeight + 'px';
    dimmer.className = 'dimmer';

    dimmer.onclick = function(){
        document.body.removeChild(this);   = 'hidden';

    document.body.appendChild(dimmer); = 'visible'; = window.innerHeight/2 - 50 + 'px'; = window.innerWidth/2 - 100 + 'px';
    return false;


<div id="lightbox">Testing out the lightbox</div>
<a href="#" id="opener">Click me</a>


    border:2px solid #3c3c3c;
    width: 200px;

    background: #000;
    position: absolute;
    opacity: .5;
    top: 0;

Download text/csv content as files from server in Angular

Using angular 1.5.9

I made it working like this by setting the window.location to the csv file download url. Tested and its working with the latest version of Chrome and IE11.


   $scope.downloadStats = function downloadStats{
        var csvFileRoute = '/stats/download';
        $window.location = url;


<a target="_self" ng-click="downloadStats()"><i class="fa fa-download"></i> CSV</a>

In php set the below headers for the response:

$headers = [
    'content-type'              => 'text/csv',
    'Content-Disposition'       => 'attachment; filename="export.csv"',
    'Cache-control'             => 'private, must-revalidate, post-check=0, pre-check=0',
    'Content-transfer-encoding' => 'binary',
    'Expires' => '0',
    'Pragma' => 'public',

pandas dataframe groupby datetime month

Managed to do it:

b = pd.read_csv('b.dat')
b.index = pd.to_datetime(b['date'],format='%m/%d/%y %I:%M%p')
b.groupby(by=[b.index.month, b.index.year])


b.groupby(pd.Grouper(freq='M'))  # update for v0.21+

How to add a filter class in Spring Boot?

Here is an example of my custom Filter class:

package com.dawson.controller.filter;

import org.springframework.stereotype.Component;
import org.springframework.web.filter.GenericFilterBean;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class DawsonApiFilter extends GenericFilterBean {

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        if (req.getHeader("x-dawson-nonce") == null || req.getHeader("x-dawson-signature") == null) {
            HttpServletResponse httpResponse = (HttpServletResponse) response;
            httpResponse.sendError(HttpServletResponse.SC_BAD_REQUEST, "Required headers not specified in the request");
        chain.doFilter(request, response);

And I added it to the Spring boot configuration by adding it to Configuration class as follows:

package com.dawson.configuration;

import com.fasterxml.jackson.datatype.hibernate5.Hibernate5Module;
import com.dawson.controller.filter.DawsonApiFilter;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;

public class ApplicationConfiguration {
    public FilterRegistrationBean dawsonApiFilter() {
        FilterRegistrationBean registration = new FilterRegistrationBean();
        registration.setFilter(new DawsonApiFilter());
// In case you want the filter to apply to specific URL patterns only
        return registration;

How do I make an asynchronous GET request in PHP?

I found this interesting link to do asynchronous processing(get request).


Furthermore you could do asynchronous processing by using a message queue like for instance beanstalkd.

.NET unique object identifier

You can develop your own thing in a second. For instance:

   class Program
        static void Main(string[] args)
            var a = new object();
            var b = new object();
            Console.WriteLine("", a.GetId(), b.GetId());

    public static class MyExtensions
        //this dictionary should use weak key references
        static Dictionary<object, int> d = new Dictionary<object,int>();
        static int gid = 0;

        public static int GetId(this object o)
            if (d.ContainsKey(o)) return d[o];
            return d[o] = gid++;

You can choose what you will like to have as unique ID on your own, for instance, System.Guid.NewGuid() or simply integer for fastest access.

What is boilerplate code?

Boilerplate is what good programmers avoid: repetition.

How to check if a string contains a substring in Bash

I like sed.

nonsub="$(echo "$string" | sed "s/$substr//")"
hassub=0 ; [ "$string" != "$nonsub" ] && hassub=1

Edit, Logic:

  • Use sed to remove instance of substring from string

  • If new string differs from old string, substring exists

How do I speed up the gwt compiler?

Although this entry is quite old and most of you probably already know, I think it's worth mention that GWT 2.x includes a new compile flag which speeds up compiles by skipping optimizations. You definitely shouldn't deploy JavaScript compiled that way, but it can be a time saver during non-production continuous builds.

Just include the flag: -draftCompile to your GWT compiler line.

How to create Windows EventLog source from command line?

you can create your own custom event by using diagnostics.Event log class. Open a windows application and on a button click do the following code.

System.Diagnostics.EventLog.CreateEventSource("ApplicationName", "MyNewLog");

"MyNewLog" means the name you want to give to your log in event viewer.

for more information check this link []

Oracle client ORA-12541: TNS:no listener

Check out your TNS Names, this must not have spaces at the left side of the ALIAS

Best regards

Generating PDF files with JavaScript

I maintain PDFKit, which also powers pdfmake (already mentioned here). It works in both Node and the browser, and supports a bunch of stuff that other libraries do not:

  • Embedding subsetted fonts, with support for unicode.
  • Lots of advanced text layout stuff (columns, page breaking, full unicode line breaking, basic rich text, etc.).
  • Working on even more font stuff for advanced typography (OpenType/AAT ligatures, contextual substitution, etc.). Coming soon: see the fontkit branch if you're interested.
  • More graphics stuff: gradients, etc.
  • Built with modern tools like browserify and streams. Usable both in the browser and node.

Check out for a full tutorial to see for yourself what PDFKit can do. And for an example of what kinds of documents can be produced, check out the docs as a PDF generated from some Markdown files using PDFKit itself:

You can also try it out interactively in the browser here:

CSS rotation cross browser with jquery.animate()

To do this cross browser including IE7+, you will need to expand the plugin with a transformation matrix. Since vendor prefix is done in jQuery from jquery-1.8+ I will leave that out for the transform property.

$.fn.animateRotate = function(endAngle, options, startAngle)
    return this.each(function()
        var elem = $(this), rad, costheta, sintheta, matrixValues, noTransform = !('transform' in || 'webkitTransform' in || 'msTransform' in || 'mozTransform' in || 'oTransform' in,
            anims = {}, animsEnd = {};
        if(typeof options !== 'object')
            options = {};
        else if(typeof options.extra === 'object')
            anims = options.extra;
            animsEnd = options.extra;
        anims.deg = startAngle;
        animsEnd.deg = endAngle;
        options.step = function(now, fx)
            if(fx.prop === 'deg')
                    rad = now * (Math.PI * 2 / 360);
                    costheta = Math.cos(rad);
                    sintheta = Math.sin(rad);
                    matrixValues = 'M11=' + costheta + ', M12=-'+ sintheta +', M21='+ sintheta +', M22='+ costheta;
                    $('body').append('Test ' + matrixValues + '<br />');
                        'filter': 'progid:DXImageTransform.Microsoft.Matrix(sizingMethod=\'auto expand\','+matrixValues+')',
                        '-ms-filter': 'progid:DXImageTransform.Microsoft.Matrix(sizingMethod=\'auto expand\','+matrixValues+')'
                        //webkitTransform: 'rotate('+now+'deg)',
                        //mozTransform: 'rotate('+now+'deg)',
                        //msTransform: 'rotate('+now+'deg)',
                        //oTransform: 'rotate('+now+'deg)',
                        transform: 'rotate('+now+'deg)'
            $(anims).animate(animsEnd, options);
            elem.animate(animsEnd, options);

Note: The parameters options and startAngle are optional, if you only need to set startAngle use {} or null for options.

Example usage:

var obj = $(document.createElement('div'));
obj.on("click", function(){
    obj.stop().animateRotate(180, {
        duration: 250,
        complete: function()
            obj.animateRotate(0, {
                duration: 250
obj.text('Click me!');
obj.css({cursor: 'pointer', position: 'absolute'});

See also this jsfiddle for a demo.

Update: You can now also pass extra: {} in the options. This will make you able to execute other animations simultaneously. For example:

obj.animateRotate(90, {extra: {marginLeft: '100px', opacity: 0.5}});

This will rotate the element 90 degrees, and move it to the right with 100px and make it semi-transparent all at the same time during the animation.

cvc-elt.1: Cannot find the declaration of element 'MyElement'

I had this error for my XXX element and it was because my XSD was wrongly formatted according to javax.xml.bind v2.2.11 . I think it's using an older XSD format but I didn't bother to confirm.

My initial wrong XSD was alike the following:

<xs:element name="Document" type="Document"/>
<xs:complexType name="Document">
        <xs:element name="XXX" type="XXX_TYPE"/>

The good XSD format for my migration to succeed was the following:

<xs:element name="Document">
            <xs:element ref="XXX"/>
<xs:element name="XXX" type="XXX_TYPE"/>

And so on for every similar XSD nodes.

how to get the last character of a string?

Try this...

const str = ""

How to revert initial git commit?

git reset --hard make changes, then do

git add -A
git commit --amend --no-edit 


git add -A
git commit --amend -m "commit_message"

and then

git push origin master --force

--force will rewrite that commit you've reseted to in the first step.

Don't do this, because you're about to go against the whole idea of VCS systems and git in particular. The only good method is to create new and delete unneeded branch. See git help branch for info.

Set background image in CSS using jquery

You have to remove the semicolon in the css rule string:

$(this).parent().css("background", "url(/images/r-srchbg_white.png) no-repeat");

NSOperation vs Grand Central Dispatch

In line with my answer to a related question, I'm going to disagree with BJ and suggest you first look at GCD over NSOperation / NSOperationQueue, unless the latter provides something you need that GCD doesn't.

Before GCD, I used a lot of NSOperations / NSOperationQueues within my applications for managing concurrency. However, since I started using GCD on a regular basis, I've almost entirely replaced NSOperations and NSOperationQueues with blocks and dispatch queues. This has come from how I've used both technologies in practice, and from the profiling I've performed on them.

First, there is a nontrivial amount of overhead when using NSOperations and NSOperationQueues. These are Cocoa objects, and they need to be allocated and deallocated. In an iOS application that I wrote which renders a 3-D scene at 60 FPS, I was using NSOperations to encapsulate each rendered frame. When I profiled this, the creation and teardown of these NSOperations was accounting for a significant portion of the CPU cycles in the running application, and was slowing things down. I replaced these with simple blocks and a GCD serial queue, and that overhead disappeared, leading to noticeably better rendering performance. This wasn't the only place where I noticed overhead from using NSOperations, and I've seen this on both Mac and iOS.

Second, there's an elegance to block-based dispatch code that is hard to match when using NSOperations. It's so incredibly convenient to wrap a few lines of code in a block and dispatch it to be performed on a serial or concurrent queue, where creating a custom NSOperation or NSInvocationOperation to do this requires a lot more supporting code. I know that you can use an NSBlockOperation, but you might as well be dispatching something to GCD then. Wrapping this code in blocks inline with related processing in your application leads in my opinion to better code organization than having separate methods or custom NSOperations which encapsulate these tasks.

NSOperations and NSOperationQueues still have very good uses. GCD has no real concept of dependencies, where NSOperationQueues can set up pretty complex dependency graphs. I use NSOperationQueues for this in a handful of cases.

Overall, while I usually advocate for using the highest level of abstraction that accomplishes the task, this is one case where I argue for the lower-level API of GCD. Among the iOS and Mac developers I've talked with about this, the vast majority choose to use GCD over NSOperations unless they are targeting OS versions without support for it (those before iOS 4.0 and Snow Leopard).

Is Constructor Overriding Possible?

Cannot override constructor. Constructor can be regarded as static, subclass cannot override its super constructor.

Of course, you could call protected-method in super class constructor, then overide it in subclass to change super class constructor. However, many persons suggest not to use the trick, in order to protect super class constructor behavior. For instance, FindBugs will warn you that a constructor calls a non-final method.

Convert double to Int, rounded down

Another option either using Double or double is use Double.valueOf(double d).intValue();. Simple and clean

Count the number of occurrences of a character in a string in Javascript

And there is:

function character_count(string, char, ptr = 0, count = 0) {
    while (ptr = string.indexOf(char, ptr) + 1) {count ++}
    return count

Works with integers too!

How can I get all sequences in an Oracle database?

You may not have permission to dba_sequences. So you can always just do:

select * from user_sequences;

window.history.pushState refreshing the browser


Only works after page is loaded, and when you will click on refresh it doesn't mean that there is any real URL.

What you should do here is knowing to which URL you are getting redirected when you reload this page. And on that page you can get the conditions by getting the current URL and making all of your conditions.

How to re-sync the Mysql DB if Master and slave have different database incase of Mysql replication?

We are using master-master replication technique of MySQL and if one MySQL server say 1 is removed from the network it reconnects itself after the connection are restored and all the records that were committed in the in the server 2 which was in the network are transferred to the server 1 which has lost the connection after restoration. Slave thread in the MySQL retries to connect to its master after every 60 sec by default. This property can be changed as MySQL ha a flag "master_connect_retry=5" where 5 is in sec. This means that we want a retry after every 5 sec.

But you need to make sure that the server which lost the connection show not make any commit in the database as you get duplicate Key error Error code: 1062


Join on one-to-many relation in JPQL looks as follows:

select b.fname, b.lname from Users b JOIN b.groups c where c.groupName = :groupName 

When several properties are specified in select clause, result is returned as Object[]:

Object[] temp = (Object[]) em.createNamedQuery("...")
    .setParameter("groupName", groupName)
String fname = (String) temp[0];
String lname = (String) temp[1];

By the way, why your entities are named in plural form, it's confusing. If you want to have table names in plural, you may use @Table to specify the table name for the entity explicitly, so it doesn't interfere with reserved words:

@Entity @Table(name = "Users")     
public class User implements Serializable { ... } 

Safely remove migration In Laravel

You likely need to delete the entry from the migrations table too.

How to force table cell <td> content to wrap?

Use table-layout:fixed in the table and word-wrap:break-word in the td.

See this example:

   table {border-collapse:collapse; table-layout:fixed; width:310px;}
   table td {border:solid 1px #fab; width:100px; word-wrap:break-word;}

         <td>Lorem Ipsum</td>
         <td>Lorem Ipsum is simply dummy text of the printing and typesetting industry. </td>
         <td>Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.</td>
         <td>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna...</td>


table {border-collapse:collapse; table-layout:fixed; width:310px;}_x000D_
       table td {border:solid 1px #fab; width:100px; word-wrap:break-word;}
             <td>Lorem Ipsum</td>_x000D_
             <td>Lorem Ipsum is simply dummy text of the printing and typesetting industry. </td>_x000D_
             <td>Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.</td>_x000D_
             <td>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna...</td>_x000D_

How do I create a file AND any folders, if the folders don't exist?

Use Directory.CreateDirectory before you create the file. It creates the folder recursively for you.

What should be in my .gitignore for an Android Studio project?

As of Android Studio 0.8.4 .gitignore file is generated automatically when starting new project. By default it contains:


How can I de-install a Perl module installed via `cpan`?

  1. Install App::cpanminus from CPAN (use: cpan App::cpanminus for this).
  2. Type cpanm --uninstall Module::Name (note the "m") to uninstall the module with cpanminus.

This should work.


Hai sridhar, I found an answer for your prob

ClientScript.RegisterClientScriptBlock(GetType(), "sas", "<script> alert('Inserted successfully');</script>", true);

change false to true

or try this

ScriptManager.RegisterClientScriptBlock(ursavebuttonID, typeof(LinkButton or button), "sas", "<script> alert('Inserted successfully');</script>", true);

How do I update pip itself from inside my virtual environment?

I had a similar problem on a raspberry pi.

The problem was that http requires SSL and so I needed to force it to use https to get around this requirement.

sudo pip install --upgrade pip --index-url=


sudo pip-3.2 --upgrade pip --index-url=

How to un-commit last un-pushed git commit without losing the changes

For the case: "This has not been pushed, only committed." - if you use IntelliJ (or another JetBrains IDE) and you haven't pushed changes yet you can do next.

  1. Go to Version control window (Alt + 9/Command + 9) - "Log" tab.
  2. Right-click on a commit before your last one.
  3. Reset current branch to here
  4. pick Soft (!!!)
  5. push the Reset button in the bottom of the dialog window.


This will "uncommit" your changes and return your git status to the point before your last local commit. You will not lose any changes you made.

Get input type="file" value when it has multiple files selected

You use input.files property. It's a collection of File objects and each file has a name property:

onmouseout="for (var i = 0; i < this.files.length; i++) alert(this.files[i].name);"

Route.get() requires callback functions but got a "object Undefined"

Make sure that


exports.yourFunction = function(a,b){
  //your code



var express = require('express');
var app = express();
var yourModule = require('yourFile');
app.get('/your_path', yourModule.yourFunction);

For me, I ran into this issue when copy pasting a module into another module for testing, needed to change the exports. xxxx at the top of the file

jQuery .load() call doesn't execute JavaScript in loaded HTML file

A other version of John Pick's solution just before, this works fine for me :

   success: function(data, textStatus, jqXHR) {
       var reponse = jQuery(jqXHR.responseText);
       var reponseScript = reponse.filter("script");
       jQuery.each(reponseScript, function(idx, val) { eval(val.text); } );

Python SQL query string formatting

To avoid formatting entirely, I think a great solution is to use procedures.

Calling a procedure gives you the result of whatever query you want to put in this procedure. You can actually process multiple queries within a procedure. The call will just return the last query that was called.


   SELECT 2+222+2222+222+222+2222+2222 AS this_is_a_really_long_string_test;
   END //

#calling the procedure gives you the result of whatever query you want to put in this procedure. You can actually process multiple queries within a procedure. The call just returns the last query result
 call example;


sql =('call example;')

Installing a local module using npm?

From the npm-link documentation:

In the local module directory:

$ cd ./package-dir
$ npm link

In the directory of the project to use the module:

$ cd ./project-dir
$ npm link package-name

Or in one go using relative paths:

$ cd ./project-dir
$ npm link ../package-dir

This is equivalent to using two commands above under the hood.

Finding the index of an item in a list

>>> ["foo", "bar", "baz"].index("bar")

Reference: Data Structures > More on Lists

Caveats follow

Note that while this is perhaps the cleanest way to answer the question as asked, index is a rather weak component of the list API, and I can't remember the last time I used it in anger. It's been pointed out to me in the comments that because this answer is heavily referenced, it should be made more complete. Some caveats about list.index follow. It is probably worth initially taking a look at the documentation for it:

list.index(x[, start[, end]])

Return zero-based index in the list of the first item whose value is equal to x. Raises a ValueError if there is no such item.

The optional arguments start and end are interpreted as in the slice notation and are used to limit the search to a particular subsequence of the list. The returned index is computed relative to the beginning of the full sequence rather than the start argument.

Linear time-complexity in list length

An index call checks every element of the list in order, until it finds a match. If your list is long, and you don't know roughly where in the list it occurs, this search could become a bottleneck. In that case, you should consider a different data structure. Note that if you know roughly where to find the match, you can give index a hint. For instance, in this snippet, l.index(999_999, 999_990, 1_000_000) is roughly five orders of magnitude faster than straight l.index(999_999), because the former only has to search 10 entries, while the latter searches a million:

>>> import timeit
>>> timeit.timeit('l.index(999_999)', setup='l = list(range(0, 1_000_000))', number=1000)
>>> timeit.timeit('l.index(999_999, 999_990, 1_000_000)', setup='l = list(range(0, 1_000_000))', number=1000)

Only returns the index of the first match to its argument

A call to index searches through the list in order until it finds a match, and stops there. If you expect to need indices of more matches, you should use a list comprehension, or generator expression.

>>> [1, 1].index(1)
>>> [i for i, e in enumerate([1, 2, 1]) if e == 1]
[0, 2]
>>> g = (i for i, e in enumerate([1, 2, 1]) if e == 1)
>>> next(g)
>>> next(g)

Most places where I once would have used index, I now use a list comprehension or generator expression because they're more generalizable. So if you're considering reaching for index, take a look at these excellent Python features.

Throws if element not present in list

A call to index results in a ValueError if the item's not present.

>>> [1, 1].index(2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: 2 is not in list

If the item might not be present in the list, you should either

  1. Check for it first with item in my_list (clean, readable approach), or
  2. Wrap the index call in a try/except block which catches ValueError (probably faster, at least when the list to search is long, and the item is usually present.)

jQuery Show-Hide DIV based on Checkbox Value

Try this

    $('.yourbutton').toggle($('.yourchkboxes:checked').length > 0);

So it will check for at least one checkbox is checked or not.

Passing arguments to an interactive program non-interactively

Many ways

pipe your input

echo "yes
maybe" | your_program

redirect from a file

your_program < answers.txt

use a here document (this can be very readable)

your_program << ANSWERS

use a here string

your_program <<< $'yes\nno\nmaybe\n'

How to Use -confirm in PowerShell

This is a simple loop that keeps prompting unless the user selects 'y' or 'n'

$confirmation = Read-Host "Ready? [y/n]"
while($confirmation -ne "y")
    if ($confirmation -eq 'n') {exit}
    $confirmation = Read-Host "Ready? [y/n]"

JUnit test for System.out.println()

You can set the System.out print stream via setOut() (and for in and err). Can you redirect this to a print stream that records to a string, and then inspect that ? That would appear to be the simplest mechanism.

(I would advocate, at some stage, convert the app to some logging framework - but I suspect you already are aware of this!)

ORA-12528: TNS Listener: all appropriate instances are blocking new connections. Instance "CLRExtProc", status UNKNOWN

I had this error message with boot2docker on windows with the docker-oracle-xe-11g image (

The reason was that the virtual box disk was full (check with boot2docker.exe ssh df). Deleting old images and restarting the container solved the problem.

Image Processing: Algorithm Improvement for 'Coca-Cola Can' Recognition

I would detect red rectangles: RGB -> HSV, filter red -> binary image, close (dilate then erode, known as imclose in matlab)

Then look through rectangles from largest to smallest. Rectangles that have smaller rectangles in a known position/scale can both be removed (assuming bottle proportions are constant, the smaller rectangle would be a bottle cap).

This would leave you with red rectangles, then you'll need to somehow detect the logos to tell if they're a red rectangle or a coke can. Like OCR, but with a known logo?

jQuery remove options from select

Try this:

$(".ct option[value='X']").each(function() {

Or to be more terse, this will work just as well:

$(".ct option[value='X']").remove();

How to set Android camera orientation properly?

From the Javadocs for setDisplayOrientation(int) (Requires API level 9):

 public static void setCameraDisplayOrientation(Activity activity,
         int cameraId, android.hardware.Camera camera) {
     android.hardware.Camera.CameraInfo info =
             new android.hardware.Camera.CameraInfo();
     android.hardware.Camera.getCameraInfo(cameraId, info);
     int rotation = activity.getWindowManager().getDefaultDisplay()
     int degrees = 0;
     switch (rotation) {
         case Surface.ROTATION_0: degrees = 0; break;
         case Surface.ROTATION_90: degrees = 90; break;
         case Surface.ROTATION_180: degrees = 180; break;
         case Surface.ROTATION_270: degrees = 270; break;

     int result;
     if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
         result = (info.orientation + degrees) % 360;
         result = (360 - result) % 360;  // compensate the mirror
     } else {  // back-facing
         result = (info.orientation - degrees + 360) % 360;

How to make the webpack dev server run on port 80 and on to make it publicly accessible?

I tried the solutions above, but had no luck. I noticed this line in my project's package.json:

 "bin": {
"webpack-dev-server": "bin/webpack-dev-server.js"


I looked at bin/webpack-dev-server.js and found this line:

.describe("port", "The port").default("port", 8080)

I changed the port to 3000. A bit of a brute force approach, but it worked for me.

Return anonymous type results?

You must use ToList() method first to take rows from database and then select items as a class. Try this:

public partial class Dog {
    public string BreedName  { get; set; }}

List<Dog> GetDogsWithBreedNames(){
    var db = new DogDataContext(ConnectString);
    var result = (from d in db.Dogs
                  join b in db.Breeds on d.BreedId equals b.BreedId
                  select new
                      Name = d.Name,
                      BreedName = b.BreedName
                          new Dog{
                              Name = x.Name,
                              BreedName = x.BreedName,
return result;}

So, the trick is first ToList(). It is immediately makes the query and gets the data from database. Second trick is Selecting items and using object initializer to generate new objects with items loaded.

Hope this helps.

tmux status bar configuration

I used tmux-powerline to fully pimp my tmux status bar. I was googling for a way to change to background of the status bar when your typing a tmux command. When I stumbled on this post I thought I should mention it for completeness.

Update: This project is in a maintenance mode and no future functionality is likely to be added. tmux-powerline, with all other powerline projects, is replaced by the new unifying powerline. However this project is still functional and can serve as a lightweight alternative for non-python users.

An invalid form control with name='' is not focusable

Its because there is a hidden input with required attribute in the form.

In my case, I had a select box and it is hidden by jquery tokenizer using inline style. If I dont select any token, browser throws the above error on form submission.

So, I fixed it using the below css technique :

     display: block !important;//because otherwise, its throwing error An invalid form control with name='download_tag[0][]' is not focusable.
    //So, instead set opacity
    opacity: 0;
    height: 0px;


File is universal (three slices), but it does not contain a(n) ARMv7-s slice error for static libraries on iOS, anyway to bypass?

If you want to remove the support for any architecture, for example, ARMv7-s in your case, use menu Project -> Build Settings -> remove the architecture from "valid architectures".

You can use this as a temporary solution until the library has been updated. You have to remove the architecture from your main project, not from the library.

Alternatively, you can set the flag for your debug configuration's "Build Active Architecture Only" to Yes. Leave the release configuration's "Build Active Architecture Only" to No, just so you'll get a reminder before releasing that you ought to upgrade any third-party libraries you're using.

SASS and @font-face

I’ve been struggling with this for a while now. Dycey’s solution is correct in that specifying the src multiple times outputs the same thing in your css file. However, this seems to break in OSX Firefox 23 (probably other versions too, but I don’t have time to test).

The cross-browser @font-face solution from Font Squirrel looks like this:

@font-face {
    font-family: 'fontname';
    src: url('fontname.eot');
    src: url('fontname.eot?#iefix') format('embedded-opentype'),
         url('fontname.woff') format('woff'),
         url('fontname.ttf') format('truetype'),
         url('fontname.svg#fontname') format('svg');
    font-weight: normal;
    font-style: normal;

To produce the src property with the comma-separated values, you need to write all of the values on one line, since line-breaks are not supported in Sass. To produce the above declaration, you would write the following Sass:

  font-family: 'fontname'
  src: url('fontname.eot')
  src: url('fontname.eot?#iefix') format('embedded-opentype'), url('fontname.woff') format('woff'), url('fontname.ttf') format('truetype'), url('fontname.svg#fontname') format('svg')
  font-weight: normal
  font-style: normal

I think it seems silly to write out the path a bunch of times, and I don’t like overly long lines in my code, so I worked around it by writing this mixin:

=font-face($family, $path, $svg, $weight: normal, $style: normal)
    font-family: $family
    src: url('#{$path}.eot')
    src: url('#{$path}.eot?#iefix') format('embedded-opentype'), url('#{$path}.woff') format('woff'), url('#{$path}.ttf') format('truetype'), url('#{$path}.svg##{$svg}') format('svg')
    font-weight: $weight
    font-style: $style

Usage: For example, I can use the previous mixin to setup up the Frutiger Light font like this:

+font-face('frutigerlight', '../fonts/frutilig-webfont', 'frutigerlight')

Add a "sort" to a =QUERY statement in Google Spreadsheets

Sorting by C and D needs to be put into number form for the corresponding column, ie 3 and 4, respectively. Eg Order By 2 asc")

How to embed images in html email

You have to encode your email as multipart mime and then you can attach emails as attachments basically. You reference them by cid in the email.

Alternatively you could not attach them to the email and use URLs directly but most mail programs will block this as spammers use the trick to detect the liveness of email addresses.

You don't say what language but here is one example.

Fastest Way to Find Distance Between Two Lat/Long Points

Have a read of Geo Distance Search with MySQL, a solution based on implementation of Haversine Formula to MySQL. This is a complete solution description with theory, implementation and further performance optimization. Although the spatial optimization part didn't work correctly in my case.

I noticed two mistakes in this:

  1. the use of abs in the select statement on p8. I just omitted abs and it worked.

  2. the spatial search distance function on p27 does not convert to radians or multiply longitude by cos(latitude), unless his spatial data is loaded with this in consideration (cannot tell from context of article), but his example on p26 indicates that his spatial data POINT is not loaded with radians or degrees.

What are the differences between Pandas and NumPy+SciPy in Python?

Pandas offer a great way to manipulate tables, as you can make binning easy (binning a dataframe in pandas in Python) and calculate statistics. Other thing that is great in pandas is the Panel class that you can join series of layers with different properties and combine it using groupby function.

New line in JavaScript alert box

\n will put a new line in - \n being a control code for new line.

alert("Line 1\nLine 2");

Unit Testing C Code

Minunit is an incredibly simple unit testing framework. I'm using it to unit test c microcontroller code for avr.

docker error: /var/run/docker.sock: no such file or directory

You can quickly setup your environment using shellinit

At your command prompt execute:

$(boot2docker shellinit)  

That will populate and export the environment variables and initialize other features.

VBA Excel - Insert row below with same format including borders and frames

When inserting a row, regardless of the CopyOrigin, Excel will only put vertical borders on the inserted cells if the borders above and below the insert position are the same.

I'm running into a similar (but rotated) situation with inserting columns, but Copy/Paste is too slow for my workbook (tens of thousands of rows, many columns, and complex formatting).

I've found three workarounds that don't require copying the formatting from the source row:

  1. Ensure the vertical borders are the same weight, color, and pattern above and below the insert position so Excel will replicate them in your new row. (This is the "It hurts when I do this," "Stop doing that!" answer.)

  2. Use conditional formatting to establish the border (with a Formula of "=TRUE"). The conditional formatting will be copied to the new row, so you still end up with a border.Caveats:

    • Conditional formatting borders are limited to the thin-weight lines.
    • Works best for sheets where borders are relatively consistent so you don't have to create a bunch of conditional formatting rules.
  3. Set the border on the inserted row in VBA after inserting the row. Setting a border on a range is much faster than copying and pasting all of the formatting just to get a border (assuming you know ahead of time what the border should be or can sample it from the row above without losing performance).

Trying to load local JSON file to show data in a html page using JQuery

Due to security issues (same origin policy), javascript access to local files is restricted if without user interaction.

According to

A file can read another file only if the parent directory of the originating file is an ancestor directory of the target file.

Imagine a situation when javascript from a website tries to steal your files anywhere in your system without you being aware of. You have to deploy it to a web server. Or try to load it with a script tag. Like this:

<script type="text/javascript" language="javascript" src="jquery-1.8.2.min.js"></script>        
<script type="text/javascript" language="javascript" src="priorities.json"></script> 

<script type="text/javascript">
   $(document).ready(function(e) {

Your priorities.json file:

var jsonObject = {
"start": {
    "count": "5",
    "title": "start",
    "priorities": [
            "txt": "Work"
            "txt": "Time Sense"
            "txt": "Dicipline"
            "txt": "Confidence"
            "txt": "CrossFunctional"

Or declare a callback function on your page and wrap it like jsonp technique:

<script type="text/javascript" language="javascript" src="jquery-1.8.2.min.js">    </script> 
     <script type="text/javascript">
           $(document).ready(function(e) {


           function jsonCallback(jsonObject){

 <script type="text/javascript" language="javascript" src="priorities.json"></script> 

Your priorities.json file:

    "start": {
        "count": "5",
        "title": "start",
        "priorities": [
                "txt": "Work"
                "txt": "Time Sense"
                "txt": "Dicipline"
                "txt": "Confidence"
                "txt": "CrossFunctional"

Using script tag is a similar technique to JSONP, but with this approach it's not so flexible. I recommend deploying it on a web server.

With user interaction, javascript is allowed access to files. That's the case of File API. Using file api, javascript can access files selected by the user from <input type="file"/> or dropped from the desktop to the browser.

Python: Passing variables between functions

passing variable from one function as argument to other functions can be done like this

define functions like this

def function1():
global a
a=input("Enter any number\t")

def function2(argument):
print ("this is the entered number - ",argument)

call the functions like this


how to convert string into dictionary in python 3.*?

  1. literal_eval, a somewhat safer version of eval (will only evaluate literals ie strings, lists etc):

    from ast import literal_eval
    python_dict = literal_eval("{'a': 1}")
  2. json.loads but it would require your string to use double quotes:

    import json
    python_dict = json.loads('{"a": 1}')

Getting msbuild.exe without installing Visual Studio

The latest (as of Jan 2019) stand-alone MSBuild installers can be found here:

Scroll down to "Tools for Visual Studio 2019" and choose "Build Tools for Visual Studio 2019" (despite the name, it's for users who don't want the full IDE)

See this question for additional information.

Creating pdf files at runtime in c#

I have used (iTextSharp) in the past with nice results.

Unlink of file Failed. Should I try again?

On Windows 8: I ran git gc and it said git gc was already running, I ran git gc --force and the garbage collector ran.

I could then switch branches and merge without any issues, try git gc --force.

Perhaps the gc process didn't stop gracefully for one reason or another.

Plot width settings in ipython notebook

If you use %pylab inline you can (on a new line) insert the following command:

%pylab inline
pylab.rcParams['figure.figsize'] = (10, 6)

This will set all figures in your document (unless otherwise specified) to be of the size (10, 6), where the first entry is the width and the second is the height.

See this SO post for more details.

Displaying the Indian currency symbol on a website

WebRupee is a web API for the Indian currency symbol. It provides a simple, cross browser method for using the Rrupee symbol on your webpage, blog or anywhere on the web.

Here is a method for printing the Indian currency symbol:

    <link rel="stylesheet" type="text/css" href="">
    <script src= type=”text/javascript”></script>
    Rupee Symbol: <span class="WebRupee">Rs.</span> 200

This means if somebody copies text from your site and pastes it somewhere else, he will see Rs and not some other or blank character.

You can now also use the new Rupee unicode symbol — U+20B9 INDIAN RUPEE SIGN. It can be used in this manner:

<span class="WebRupee">&#x20B9;</span> 500

Just include the following script and it will update all the "Rs" / "Rs." for you:

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

Insert some string into given string at given index in Python

There are several ways to do this:

One way is to use slicing:

>>> a="line=Name Age Group Class Profession"
>>> b=a.split()
>>> b[2:2]=[b[2]]*3
>>> b
['line=Name', 'Age', 'Group', 'Group', 'Group', 'Group', 'Class', 'Profession']
>>> a=" ".join(b)
>>> a
'line=Name Age Group Group Group Group Class Profession'

Another would be to use regular expressions:

>>> import re
>>> a=re.sub(r"(\S+\s+\S+\s+)(\S+\s+)(.*)", r"\1\2\2\2\2\3", a)
>>> a
'line=Name Age Group Group Group Group Class Profession'

Git for Windows: .bashrc or equivalent configuration files for Git Bash shell

In your home directory, you should edit .bash_profile if you have Git for Windows 2.21.0 or later (as of this writing).

You could direct .bash_profile to just source .bashrc, but if something happens to your .bash_profile, then it will be unclear why your .bashrc is again not working.

I put all my aliases and other environment stuff in .bash_profile, and I also added this line:

echo "Sourcing ~/.bash_profile - this version of Git Bash doesn't use .bashrc"

And THEN, in .bashrc I have

echo "This version of Git Bash doesn't use .bashrc. Use .bash_profile instead"

(Building on @harsel's response. I woulda commented, but I have no points yet.)

How to wrap text using CSS?

The better option if you cannot control user input, it is to establish the css property, overflow:hidden, so if the string is superior to the width, it will not deform the design.


I like the answer: "word-wrap: break-word", and for those browsers that do not support it, for example, IE6 or IE7, I would use my solution.

Including a css file in a blade template?

in your main layout put this in the head at the bottom of everything


and in your view put this


    <link rel="stylesheet" href="{{ asset('css/app.css') }}">


basically a placeholder so the links will appear on your main layout, and you can see custom css files on different pages

How to execute a remote command over ssh with arguments?

Do it this way instead:

function mycommand {
    ssh [email protected] "cd testdir;./ \"$1\""

You still have to pass the whole command as a single string, yet in that single string you need to have $1 expanded before it is sent to ssh so you need to use "" for it.


Another proper way to do this actually is to use printf %q to properly quote the argument. This would make the argument safe to parse even if it has spaces, single quotes, double quotes, or any other character that may have a special meaning to the shell:

function mycommand {
    printf -v __ %q "$1"
    ssh [email protected] "cd testdir;./ $__"
  • When declaring a function with function, () is not necessary.
  • Don't comment back about it just because you're a POSIXist.

unsigned APK can not be installed

You could also send your testers the apk that is signed with your debug key. You can find that in the bin folder of your project after building in debug mode.

No matching bean of type ... found for dependency

Multiple things can cause this, I didn't bother to check your entire repository, so I'm going out on a limb here.

First off, you could be missing an annotation (@Service or @Component) from the implementation of, if you're using annotations for configuration. If you're using (only) xml, you're probably missing the <bean> -definition for the UserService-implementation.

If you're using annotations and the implementation is annotated correctly, check that the package where the implementation is located in is scanned (check your <context:component-scan base-package= -value).

How can VBA connect to MySQL database in Excel?

This piece of vba worked for me:

Sub connect()
    Dim Password As String
    Dim SQLStr As String
    'OMIT Dim Cn statement
    Dim Server_Name As String
    Dim User_ID As String
    Dim Database_Name As String
    'OMIT Dim rs statement

    Set rs = CreateObject("ADODB.Recordset") 'EBGen-Daily
    Server_Name = Range("b2").Value
    Database_name = Range("b3").Value ' Name of database
    User_ID = Range("b4").Value 'id user or username
    Password = Range("b5").Value 'Password

    SQLStr = "SELECT * FROM ComputingNotesTable"

    Set Cn = CreateObject("ADODB.Connection") 'NEW STATEMENT
    Cn.Open "Driver={MySQL ODBC 5.2.2 Driver};Server=" & _ 
            Server_Name & ";Database=" & Database_Name & _
            ";Uid=" & User_ID & ";Pwd=" & Password & ";"

    rs.Open SQLStr, Cn, adOpenStatic

    Dim myArray()

    myArray = rs.GetRows()

    kolumner = UBound(myArray, 1)
    rader = UBound(myArray, 2)

    For K = 0 To kolumner ' Using For loop data are displayed
        Range("a5").Offset(0, K).Value = rs.Fields(K).Name
        For R = 0 To rader
           Range("A5").Offset(R + 1, K).Value = myArray(K, R)

    Set rs = Nothing
    Set Cn = Nothing
End Sub

How to stop a vb script running in windows

I can think of at least 2 different ways:

  1. using Task Manager (Ctrl-Shift-Esc), select the process tab, look for a process name cscript.exe or wscript.exe and use End Process.

  2. From the command line you could use taskkill /fi "imagename eq cscript.exe" (change to wscript.exe as needed)

Another way is using scripting and WMI. Here are some hints: look for the Win32_Process class and the Terminate method.

Better solution without exluding fields from Binding

You should not use your domain models in your views. ViewModels are the correct way to do it.

You need to map your domain model's necessary fields to viewmodel and then use this viewmodel in your controllers. This way you will have the necessery abstraction in your application.

If you never heard of viewmodels, take a look at this.

R memory management / cannot allocate vector of size n Mb

I followed to the help page of memory.limit and found out that on my computer R by default can use up to ~ 1.5 GB of RAM and that the user can increase this limit. Using the following code,

[1] 1535.875
> memory.limit(size=1800)

helped me to solve my problem.

Change all files and folders permissions of a directory to 644/755

This can work too:

chmod -R 755 *  // All files and folders to 755.

chmod -R 644 *.*  // All files will be 644.

How do you test a public/private DSA keypair?

For DSA keys, use

 openssl dsa -pubin -in -modulus -noout

to print the public keys, then

 openssl dsa -in dsa.key -modulus -noout

to display the public keys corresponding to a private key, then compare them.

How do I download code using SVN/Tortoise from Google Code?

Create a folder where you want to keep the code, and right click on it. Choose SVN Checkout... and type into the URL of repository field.

You can also run

svn checkout

from the command line in the folder you want to keep it (svn.exe has to be in your path, of course).

How can I get a List from some class properties with Java 8 Stream?

You can use map :

List<String> names =


In order to combine the Lists of friend names, you need to use flatMap :

List<String> friendNames =

How to add a named sheet at the end of all Excel sheets?

ThisWorkbook.Sheets.Add After:=Sheets(Sheets.Count)
ActiveSheet.Name = "XYZ"

(when you add a worksheet, anyway it'll be the active sheet)

What is the purpose for using OPTION(MAXDOP 1) in SQL Server?

As something of an aside, MAXDOP can apparently be used as a workaround to a potentially nasty bug:

Returned identity values not always correct

Javascript - Open a given URL in a new tab by clicking a button

Use this:

<input type="button" value="button name" onclick="'')" />

Worked for me and it will open an actual new 'popup' window rather than a new full browser or tab. You can also add variables to it to stop it from showing specific browser traits as follows:

onclick=",'popUpWindow','height=400,width=600,left=10,top=10,,scrollbars=yes,menubar=no'); return false;"

How do a send an HTTPS request through a proxy in Java?

Try the Apache Commons HttpClient library instead of trying to roll your own:

From their sample code:

  HttpClient httpclient = new HttpClient();
  httpclient.getHostConfiguration().setProxy("myproxyhost", 8080);

  /* Optional if authentication is required.
  httpclient.getState().setProxyCredentials("my-proxy-realm", " myproxyhost",
   new UsernamePasswordCredentials("my-proxy-username", "my-proxy-password"));

  PostMethod post = new PostMethod("https://someurl");
  NameValuePair[] data = {
     new NameValuePair("user", "joe"),
     new NameValuePair("password", "bloggs")
  // execute method and handle any error responses.
  // ...
  InputStream in = post.getResponseBodyAsStream();
  // handle response.

  /* Example for a GET reqeust
  GetMethod httpget = new GetMethod("https://someurl");
  try { 
  } finally {

Checkbox Check Event Listener

Short answer: Use the change event. Here's a couple of practical examples. Since I misread the question, I'll include jQuery examples along with plain JavaScript. You're not gaining much, if anything, by using jQuery though.

Single checkbox

Using querySelector.

var checkbox = document.querySelector("input[name=checkbox]");

checkbox.addEventListener('change', function() {
  if (this.checked) {
    console.log("Checkbox is checked..");
  } else {
    console.log("Checkbox is not checked..");
<input type="checkbox" name="checkbox" />

Single checkbox with jQuery

$('input[name=checkbox]').change(function() {
  if ($(this).is(':checked')) {
    console.log("Checkbox is checked..")
  } else {
    console.log("Checkbox is not checked..")
<script src=""></script>

<input type="checkbox" name="checkbox" />

Multiple checkboxes

Here's an example of a list of checkboxes. To select multiple elements we use querySelectorAll instead of querySelector. Then use Array.filter and to extract checked values.

// Select all checkboxes with the name 'settings' using querySelectorAll.
var checkboxes = document.querySelectorAll("input[type=checkbox][name=settings]");
let enabledSettings = []

For IE11 support, replace arrow functions with normal functions and
use a polyfill for Array.forEach:

// Use Array.forEach to add an event listener to each checkbox.
checkboxes.forEach(function(checkbox) {
  checkbox.addEventListener('change', function() {
    enabledSettings = 
      Array.from(checkboxes) // Convert checkboxes to an array to use filter and map.
      .filter(i => i.checked) // Use Array.filter to remove unchecked checkboxes.
      .map(i => i.value) // Use to extract only the checkbox values from the array of objects.
   <input type="checkbox" name="settings" value="forcefield">
   Enable forcefield
  <input type="checkbox" name="settings" value="invisibilitycloak">
  Enable invisibility cloak
  <input type="checkbox" name="settings" value="warpspeed">
  Enable warp speed

Multiple checkboxes with jQuery

let checkboxes = $("input[type=checkbox][name=settings]")
let enabledSettings = [];

// Attach a change event handler to the checkboxes.
checkboxes.change(function() {
  enabledSettings = checkboxes
    .filter(":checked") // Filter out unchecked boxes.
    .map(function() { // Extract values using jQuery map.
      return this.value;
    .get() // Get array.
<script src=""></script>
   <input type="checkbox" name="settings" value="forcefield">
   Enable forcefield
  <input type="checkbox" name="settings" value="invisibilitycloak">
  Enable invisibility cloak
  <input type="checkbox" name="settings" value="warpspeed">
  Enable warp speed

Call break in nested if statements

Javascript will throw an exception if you attempt to use a break; statement inside an if else. It is used mainly for loops. You can "break" out of an if else statement with a condition, which does not make sense to include a "break" statement.


Benefits of using the conditional ?: (ternary) operator

One thing to recognize when using the ternary operator that it is an expression not a statement.

In functional languages like scheme the distinction doesn't exists:

(if (> a b) a b)

Conditional ?: Operator "Doesn't seem to be as flexible as the if/else construct"

In functional languages it is.

When programming in imperative languages I apply the ternary operator in situations where I typically would use expressions (assignment, conditional statements, etc).

How do you remove a Cookie in a Java Servlet

This is code that I have effectively used before, passing "/" as the strPath parameter.

public static Cookie eraseCookie(String strCookieName, String strPath) {
    Cookie cookie = new Cookie(strCookieName, "");

    return cookie;

C# Switch-case string starting with

Short answer: No.

The switch statement takes an expression that is only evaluated once. Based on the result, another piece of code is executed.

So what? => String.StartsWith is a function. Together with a given parameter, it is an expression. However, for your case you need to pass a different parameter for each case, so it cannot be evaluated only once.

Long answer #1 has been given by others.

Long answer #2:

Depending on what you're trying to achieve, you might be interested in the Command Pattern/Chain-of-responsibility pattern. Applied to your case, each piece of code would be represented by an implementation of a Command. In addition to the execute method, the command can provide a boolean Accept method, which checks whether the given string starts with the respective parameter.

Advantage: Instead of your hardcoded switch statement, hardcoded StartsWith evaluations and hardcoded strings, you'd have lot more flexibility.

The example you gave in your question would then look like this:

var commandList = new List<Command>() { new MyABCCommand() };

foreach (Command c in commandList)
    if (c.Accept(mystring))

class MyABCCommand : Command
    override bool Accept(string mystring)
        return mystring.StartsWith("abc");

What's the most elegant way to cap a number to a segment?

In the spirit of arrow sexiness, you could create a micro clamp/constrain/gate/&c. function using rest parameters

var clamp = (...v) => v.sort((a,b) => a-b)[1];

Then just pass in three values


That is, again, if by sexy, you mean 'short'

Creating a segue programmatically

Storyboard Segues are not to be created outside of the storyboard. You will need to wire it up, despite the drawbacks.

UIStoryboardSegue Reference clearly states:

You do not create segue objects directly. Instead, the storyboard runtime creates them when it must perform a segue between two view controllers. You can still initiate a segue programmatically using the performSegueWithIdentifier:sender: method of UIViewController if you want. You might do so to initiate a segue from a source that was added programmatically and therefore not available in Interface Builder.

You can still programmatically tell the storyboard to present a view controller using a segue using presentModalViewController: or pushViewController:animated: calls, but you'll need a storyboard instance.

You can call UIStoryboards class method to get a named storyboard with bundle nil for the main bundle.


How to get integer values from a string in Python?

>>> import itertools
>>> int(''.join(itertools.takewhile(lambda s: s.isdigit(), string1)))

Add Keypair to existing EC2 instance

Once an instance has been started, there is no way to change the keypair associated with the instance at a meta data level, but you can change what ssh key you use to connect to the instance.

Is there a way to set background-image as a base64 encoded image?

I tried this (and worked for me):

var img = 'data:image/png;base64, ...'; //place ur base64 encoded img here = 'url(\'' + img + '\')';

ES6 syntax:

let img = 'data:image/png;base64, ...' = `url('${img}')`

A bit better:

let setBackground = src => { = `url('${src}')`

let node = nodeIGotFromDOM, img = imageBase64EncodedFromMyGF;, img);

(.text+0x20): undefined reference to `main' and undefined reference to function

This error means that, while linking, compiler is not able to find the definition of main() function anywhere.

In your makefile, the main rule will expand to something like this.

main: producer.o consumer.o AddRemove.o
   gcc -pthread -Wall -o producer.o consumer.o AddRemove.o

As per the gcc manual page, the use of -o switch is as below

-o file     Place output in file file. This applies regardless to whatever sort of output is being produced, whether it be an executable file, an object file, an assembler file or preprocessed C code. If -o is not specified, the default is to put an executable file in a.out.

It means, gcc will put the output in the filename provided immediate next to -o switch. So, here instead of linking all the .o files together and creating the binary [main, in your case], its creating the binary as producer.o, linking the other .o files. Please correct that.

Count cells that contain any text

Sample file

enter image description here


  • Tried to find the formula for counting non-blank cells (="" is a blank cell) without a need to use data twice. The solution for : =ARRAYFORMULA(SUM(IFERROR(IF(data="",0,1),1))). For ={SUM(IFERROR(IF(data="",0,1),1))} should work (press Ctrl+Shift+Enter in the formula).

How to remove item from a python list in a loop?

You can't remove items from a list while iterating over it. It's much easier to build a new list based on the old one:

y = [s for s in x if len(s) == 2]

How to include() all PHP files from a directory?

If you want include all in a directory AND its subdirectories:

$dir = "classes/";
$dh  = opendir($dir);
$dir_list = array($dir);
while (false !== ($filename = readdir($dh))) {
        array_push($dir_list, $dir.$filename."/");
foreach ($dir_list as $dir) {
    foreach (glob($dir."*.php") as $filename)
        require_once $filename;

Don't forget that it will use alphabetic order to include your files.

cannot find zip-align when publishing app

In my case SDK Build Tools 20 were already installed. I copied zipalign.exe in Tools folder but without success.

After that I noticed that I updated Eclipse without removing or renaming the old folder.

So I did:

1) Renamed old Eclipse folder 2) Restarted Eclipse

Eclipse asked to correct Android preferences because problem was Eclipse, that was still trying to use the old folder

How can I subset rows in a data frame in R based on a vector of values?

This will give you what you want:

eg2011cleaned <- eg2011[!eg2011$ID %in% bg2011missingFromBeg, ]

The error in your second attempt is because you forgot the ,

In general, for convenience, the specification object[index] subsets columns for a 2d object. If you want to subset rows and keep all columns you have to use the specification object[index_rows, index_columns], while index_cols can be left blank, which will use all columns by default.

However, you still need to include the , to indicate that you want to get a subset of rows instead of a subset of columns.

Iterating through map in template

Check the Variables section in the Go template docs. A range may declare two variables, separated by a comma. The following should work:

{{ range $key, $value := . }}
   <li><strong>{{ $key }}</strong>: {{ $value }}</li>
{{ end }}

Receive JSON POST with PHP

Use $HTTP_RAW_POST_DATA instead of $_POST.

It will give you POST data as is.

You will be able to decode it using json_decode() later.

QR Code encoding and decoding using zxing

Maybe worth looking at QRGen, which is built on top of ZXing and supports UTF-8 with this kind of syntax:

// if using special characters don't forget to supply the encoding
VCard johnSpecial = new VCard("Jöhn D?e")
                        .setAdress("ëåäö? Sträät 1, 1234 Döestüwn");