Programs & Examples On #Polyline

Polyline in computer graphics is a continuous line composed of one or more line segments.

How to draw interactive Polyline on route google maps v2 android

You should use options.addAll(allPoints); instead of options.add(point);

Get driving directions using Google Maps API v2

I just release my latest library for Google Maps Direction API on Android

Remove grid, background color, and top and right borders from ggplot2

EDIT Ignore this answer. There are now better answers. See the comments. Use + theme_classic()


This is a better version. The bug mentioned below in the original post remains (I think). But the axis line is drawn under the panel. Therefore, remove both the panel.border and panel.background to see the axis lines.

a <- seq(1,20)
b <- a^0.25
df <-,b))

ggplot(df, aes(x = a, y = b)) + geom_point() +
  theme_bw() +
  theme(axis.line = element_line(colour = "black"),
    panel.grid.major = element_blank(),
    panel.grid.minor = element_blank(),
    panel.border = element_blank(),
    panel.background = element_blank()) 

enter image description here

Original post This gets close. There was a bug with axis.line not working on the y-axis (see here), that appears not to be fixed yet. Therefore, after removing the panel border, the y-axis has to be drawn in separately using geom_vline.


a <- seq(1,20)
b <- a^0.25
df <-,b))

p = ggplot(df, aes(x = a, y = b)) + geom_point() +
   scale_y_continuous(expand = c(0,0)) +
   scale_x_continuous(expand = c(0,0)) +
   theme_bw() +
   opts(axis.line = theme_segment(colour = "black"),
        panel.grid.major = theme_blank(),
        panel.grid.minor = theme_blank(),
        panel.border = theme_blank()) +
    geom_vline(xintercept = 0)

The extreme points are clipped, but the clipping can be undone using code by baptiste.

gt <- ggplot_gtable(ggplot_build(p))
gt$layout$clip[gt$layout$name=="panel"] <- "off"

enter image description here

Or use limits to move the boundaries of the panel.

ggplot(df, aes(x = a, y = b)) + geom_point() +
   xlim(0,22) +  ylim(.95, 2.1) +
   scale_x_continuous(expand = c(0,0), limits = c(0,22)) +
   scale_y_continuous(expand = c(0,0), limits = c(.95, 2.2)) +   
   theme_bw() +
   opts(axis.line = theme_segment(colour = "black"),
        panel.grid.major = theme_blank(),
        panel.grid.minor = theme_blank(),
        panel.border = theme_blank()) +
    geom_vline(xintercept = 0)

Selecting last element in JavaScript array

use es6 deconstruction array with the spread operator

var last = [...yourArray].pop();

note that yourArray doesn't change.

Random color generator

var color = "#";
for (k = 0; k < 3; k++) {
    color += ("0" + (Math.random()*256|0).toString(16)).substr(-2);

A breakdown of how this works:

Math.random()*256 gets a random (floating point) number from 0 to 256 (0 to 255 inclusive)
Example result: 116.15200161933899

Adding the |0 strips off everything after the decimal point.
Ex: 116.15200161933899 -> 116

Using .toString(16) converts this number to hexadecimal (base 16).
Ex: 116 -> 74
Another ex: 228 -> e4

Adding "0" pads it with a zero. This will be important when we get the substring, since our final result must have two characters for each color.
Ex: 74 -> 074
Another ex: 8 -> 08

.substr(-2) gets just the last two characters.
Ex: 074 -> 74
Another ex: 08 -> 08 (if we hadn't added the "0", this would have produced "8" instead of "08")

The for loop runs this loop three times, adding each result to the color string, producing something like this:

How to properly set the 100% DIV height to match document/window height?

html, body {
#wrapper {

Print time in a batch file (milliseconds)

Below batch "program" should do what you want. Please note that it outputs the data in centiseconds instead of milliseconds. The precision of the used commands is only centiseconds.

Here is an example output:

STARTTIME: 13:42:52,25
ENDTIME: 13:42:56,51
STARTTIME: 4937225 centiseconds
ENDTIME: 4937651 centiseconds
DURATION: 426 in centiseconds

Here is the batch script:

@echo off

rem The format of %TIME% is HH:MM:SS,CS for example 23:59:59,99

rem here begins the command you want to measure
dir /s > nul
rem here ends the command you want to measure


rem output as time

rem convert STARTTIME and ENDTIME to centiseconds
set /A STARTTIME=(1%STARTTIME:~0,2%-100)*360000 + (1%STARTTIME:~3,2%-100)*6000 + (1%STARTTIME:~6,2%-100)*100 + (1%STARTTIME:~9,2%-100)
set /A ENDTIME=(1%ENDTIME:~0,2%-100)*360000 + (1%ENDTIME:~3,2%-100)*6000 + (1%ENDTIME:~6,2%-100)*100 + (1%ENDTIME:~9,2%-100)

rem calculating the duratyion is easy

rem we might have measured the time inbetween days

rem now break the centiseconds down to hors, minutes, seconds and the remaining centiseconds
set /A DURATIONH=%DURATION% / 360000
set /A DURATIONM=(%DURATION% - %DURATIONH%*360000) / 6000
set /A DURATIONS=(%DURATION% - %DURATIONH%*360000 - %DURATIONM%*6000) / 100

rem some formatting

rem outputing
echo STARTTIME: %STARTTIME% centiseconds
echo ENDTIME: %ENDTIME% centiseconds
echo DURATION: %DURATION% in centiseconds

goto :EOF

CSS: background-color only inside the margin

Instead of using a margin, could you use a border? You should do this with <div>, anyway.

Something like this?enter image description here

Remove padding or margins from Google Charts

I am quite late but any user searching for this can get help from it. Inside the options you can pass a new parameter called chartArea.

        var options = {

Left and top options will define the amount of padding from left and top. Hope this will help.

How can I selectively merge or pick changes from another branch in Git?

I had the exact same problem as mentioned by you above. But I found this Git blog clearer in explaining the answer.

Command from the above link:

# You are in the branch you want to merge to
git checkout <branch_you_want_to_merge_from> <file_paths...>

What are the benefits to marking a field as `readonly` in C#?

Keep in mind that readonly only applies to the value itself, so if you're using a reference type readonly only protects the reference from being change. The state of the instance is not protected by readonly.

How can you create multiple cursors in Visual Studio Code

May 2017
As of version 1.13 Add multiple cursors with Ctrl / Cmd + Click

VSCode developers have introduced a new setting, editor.multiCursorModifier, to change the modifier key for applying multiple cursors to Cmd + Click on macOS and Ctrl + Click on Windows and Linux. This lets users coming from other editors such as Sublime Text or Atom continue to use the keyboard modifier they are familiar with.

The setting can be set to:

  • ctrl/Cmd - Maps to Ctrl on Windows and Cmd on macOS.
  • alt - The existing default Alt.

There's also a new menu item Use Ctrl + Click for Multi-Cursor in the Selection menu to quickly toggle this setting. enter image description here

The Go To Definition and Open Link gestures will also respect this setting and adapt such that they do not conflict. For example, when the setting is ctrl/Cmd, multiple cursors can be added with Ctrl / Cmd + Click, and opening links or going to definition can be invoked with Alt +Click.

With fixing Issue #2106, it is now possible to also remove a cursor by using the same gesture on top of an existing selection.

Program to find largest and smallest among 5 numbers without using array

Here's my implementation: Simple and short

#include <iostream>
#include <cstdio>
using namespace std;

int max_of_five(int a, int b, int c, int d,int e){
    int large= max(max(a, b), max(c,d));
    return max(large,e);


int min_of_five(int a,int b,int c, int d,int e){
    int small=min(min(a,b),min(c,d));
    return min(small,e);

int main() {
    int a, b, c, d,e;

    scanf("%d %d %d %d %d", &a, &b, &c, &d,&e);
    int ans = max_of_five(a, b, c, d, e);
    int ans1=min_of_five(a,b,c,d,e);
    printf("Max:\t%d\n", ans);
    printf("Min:\t%d", ans1);

    return 0;

How to vertically align text inside a flexbox?

Instead of using align-self: center use align-items: center.

There's no need to change flex-direction or use text-align.

Here's your code, with one adjustment, to make it all work:

ul {
  height: 100%;

li {
  display: flex;
  justify-content: center;
  /* align-self: center;    <---- REMOVE */
  align-items: center;   /* <---- NEW    */
  background: silver;
  width: 100%;
  height: 20%; 

The align-self property applies to flex items. Except your li is not a flex item because its parent – the ul – does not have display: flex or display: inline-flex applied.

Therefore, the ul is not a flex container, the li is not a flex item, and align-self has no effect.

The align-items property is similar to align-self, except it applies to flex containers.

Since the li is a flex container, align-items can be used to vertically center the child elements.

* {_x000D_
  padding: 0;_x000D_
  margin: 0;_x000D_
html, body {_x000D_
  height: 100%;_x000D_
ul {_x000D_
  height: 100%;_x000D_
li {_x000D_
  display: flex;_x000D_
  justify-content: center;_x000D_
  /* align-self: center; */_x000D_
  align-items: center;_x000D_
  background: silver;_x000D_
  width: 100%;_x000D_
  height: 20%;_x000D_
  <li>This is the text</li>_x000D_

codepen demo

Technically, here's how align-items and align-self work...

The align-items property (on the container) sets the default value of align-self (on the items). Therefore, align-items: center means all flex items will be set to align-self: center.

But you can override this default by adjusting the align-self on individual items.

For example, you may want equal height columns, so the container is set to align-items: stretch. However, one item must be pinned to the top, so it is set to align-self: flex-start.


How is the text a flex item?

Some people may be wondering how a run of text...

<li>This is the text</li>

is a child element of the li.

The reason is that text that is not explicitly wrapped by an inline-level element is algorithmically wrapped by an inline box. This makes it an anonymous inline element and child of the parent.

From the CSS spec: Anonymous inline boxes

Any text that is directly contained inside a block container element must be treated as an anonymous inline element.

The flexbox specification provides for similar behavior.

4. Flex Items

Each in-flow child of a flex container becomes a flex item, and each contiguous run of text that is directly contained inside a flex container is wrapped in an anonymous flex item.

Hence, the text in the li is a flex item.

How to fix: /usr/lib/ version `GLIBCXX_3.4.15' not found

Up above, you mention having compiling your as part of your steps to reproduce, but then below you made an edit saying,

"is there a way to see on which distro a shared library was compiled on?"

Whether or not you compiled this on the same distro, and even a different version of the same distro is an important detail, especially for c++ applications.

Linking to c++ libraries, including libstdc++ can have mixed results, as far as I can tell. Here is a related question about recompiling with different versions of c++.

do we need to recompile libraries with c++11?

Basically, if you compiled against c++ on a different distro (and possibly different gcc version), this may be causing your trouble.

I think you have two options:

  1. Your best bet - recompile your .so if you hadn't compiled it on your current system. If there is a problem with your runtime's system environment, it might even come out in the compile.
  2. Bundle your other compiler's c++ libs along with your application. This may only be viable if it's the same distribution... But it's a useful trick if you rolled your own compiler. You will also have to set and export the LD_LIBRARY_PATH to the path containing your bundled stdc++ libs if you go that route.

Convert double to string C++?

std::string stringify(double x)
   std::ostringstream o;
   if (!(o << x))
     throw BadConversion("stringify(double)");
   return o.str();

C++ FAQ:

Editing legend (text) labels in ggplot

The legend titles can be labeled by specific aesthetic.

This can be achieved using the guides() or labs() functions from ggplot2 (more here and here). It allows you to add guide/legend properties using the aesthetic mapping.

Here's an example using the mtcars data set and labs():

ggplot(mtcars, aes(x=mpg, y=disp, size=hp, col=as.factor(cyl), shape=as.factor(gear))) +
  geom_point() +
  labs(x="miles per gallon", y="displacement", size="horsepower", 
       col="# of cylinders", shape="# of gears")

enter image description here

Answering the OP's question using guides():

# transforming the data from wide to long
dfm <- melt(df, id="TY")

# creating a scatterplot
ggplot(data = dfm, aes(x=TY, y=value, color=variable)) + 
  geom_point(size=5) +
  labs(title="Temperatures\n", x="TY [°C]", y="Txxx") +
  scale_color_manual(labels = c("T999", "T888"), values = c("blue", "red")) +
  theme_bw() +
  guides(color=guide_legend("my title"))  # add guide properties by aesthetic

enter image description here

close vs shutdown socket?


When you have finished using a socket, you can simply close its file descriptor with close; If there is still data waiting to be transmitted over the connection, normally close tries to complete this transmission. You can control this behavior using the SO_LINGER socket option to specify a timeout period; see Socket Options.


You can also shut down only reception or transmission on a connection by calling shutdown.

The shutdown function shuts down the connection of socket. Its argument how specifies what action to perform: 0 Stop receiving data for this socket. If further data arrives, reject it. 1 Stop trying to transmit data from this socket. Discard any data waiting to be sent. Stop looking for acknowledgement of data already sent; don’t retransmit it if it is lost. 2 Stop both reception and transmission.

The return value is 0 on success and -1 on failure.

What is a lambda expression in C++11?

The problem

C++ includes useful generic functions like std::for_each and std::transform, which can be very handy. Unfortunately they can also be quite cumbersome to use, particularly if the functor you would like to apply is unique to the particular function.

#include <algorithm>
#include <vector>

namespace {
  struct f {
    void operator()(int) {
      // do something

void func(std::vector<int>& v) {
  f f;
  std::for_each(v.begin(), v.end(), f);

If you only use f once and in that specific place it seems overkill to be writing a whole class just to do something trivial and one off.

In C++03 you might be tempted to write something like the following, to keep the functor local:

void func2(std::vector<int>& v) {
  struct {
    void operator()(int) {
       // do something
  } f;
  std::for_each(v.begin(), v.end(), f);

however this is not allowed, f cannot be passed to a template function in C++03.

The new solution

C++11 introduces lambdas allow you to write an inline, anonymous functor to replace the struct f. For small simple examples this can be cleaner to read (it keeps everything in one place) and potentially simpler to maintain, for example in the simplest form:

void func3(std::vector<int>& v) {
  std::for_each(v.begin(), v.end(), [](int) { /* do something here*/ });

Lambda functions are just syntactic sugar for anonymous functors.

Return types

In simple cases the return type of the lambda is deduced for you, e.g.:

void func4(std::vector<double>& v) {
  std::transform(v.begin(), v.end(), v.begin(),
                 [](double d) { return d < 0.00001 ? 0 : d; }

however when you start to write more complex lambdas you will quickly encounter cases where the return type cannot be deduced by the compiler, e.g.:

void func4(std::vector<double>& v) {
    std::transform(v.begin(), v.end(), v.begin(),
        [](double d) {
            if (d < 0.0001) {
                return 0;
            } else {
                return d;

To resolve this you are allowed to explicitly specify a return type for a lambda function, using -> T:

void func4(std::vector<double>& v) {
    std::transform(v.begin(), v.end(), v.begin(),
        [](double d) -> double {
            if (d < 0.0001) {
                return 0;
            } else {
                return d;

"Capturing" variables

So far we've not used anything other than what was passed to the lambda within it, but we can also use other variables, within the lambda. If you want to access other variables you can use the capture clause (the [] of the expression), which has so far been unused in these examples, e.g.:

void func5(std::vector<double>& v, const double& epsilon) {
    std::transform(v.begin(), v.end(), v.begin(),
        [epsilon](double d) -> double {
            if (d < epsilon) {
                return 0;
            } else {
                return d;

You can capture by both reference and value, which you can specify using & and = respectively:

  • [&epsilon] capture by reference
  • [&] captures all variables used in the lambda by reference
  • [=] captures all variables used in the lambda by value
  • [&, epsilon] captures variables like with [&], but epsilon by value
  • [=, &epsilon] captures variables like with [=], but epsilon by reference

The generated operator() is const by default, with the implication that captures will be const when you access them by default. This has the effect that each call with the same input would produce the same result, however you can mark the lambda as mutable to request that the operator() that is produced is not const.

How to convert Javascript datetime to C# datetime?

If you want to send dates to C# from JS that is actually quite simple - if sending UTC dates is acceptable.

var date = new Date("Tue Jul 12 2011 16:00:00 GMT-0700");
var dateStrToSendToServer = date.toISOString();

... send to C# side ...

var success = DateTimeOffset.TryParse(jsISOStr, CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal, out var result);

C# DateTime already understands ISO date formats and will parse it just fine.

To format from C# to JS just use DateTime.UtcNow.ToString("o").

Personally, I'm never comfortable relying on math and logic between different environments to get the milliseconds/ticks to show the EXACT same date and time a user may see on the client (especially where it matters). I would do the same when transferring currency as well (use strings instead to be safe, or separate dollars and cents between two different integers). Sending the date/time as separate values would be just a good (see accepted answer).

How to use OAuth2RestTemplate?

You can find examples for writing OAuth clients here:

In your case you can't just use default or base classes for everything, you have a multiple classes Implementing OAuth2ProtectedResourceDetails. The configuration depends of how you configured your OAuth service but assuming from your curl connections I would recommend:

class MyConfig{

    private String baseUrl;
    private String authorizeUrl;
    private String tokenUrl;

    protected OAuth2ProtectedResourceDetails resource() {
        ResourceOwnerPasswordResourceDetails resource;
        resource = new ResourceOwnerPasswordResourceDetails();

        List scopes = new ArrayList<String>(2);
        return resource;

    public OAuth2RestOperations restTemplate() {
        AccessTokenRequest atr = new DefaultAccessTokenRequest();
        return new OAuth2RestTemplate(resource(), new DefaultOAuth2ClientContext(atr));

class MyService {

    private OAuth2RestOperations restTemplate;

    public MyService() {

Do not forget about @EnableOAuth2Client on your config class, also I would suggest to try that the urls you are using are working with curl first, also try to trace it with the debugger because lot of exceptions are just consumed and never printed out due security reasons, so it gets little hard to find where the issue is. You should use logger with debug enabled set. Good luck

I uploaded sample springboot app on github to depict your situation because I could not find any samples for your scenario .

How can I find the version of php that is running on a distinct domain name?

I suggest you much easier and platform independent solution to the problem - wappalyzer for Google Chrome:

See here

How to share data between different threads In C# using AOP?

You can't beat the simplicity of a locked message queue. I say don't waste your time with anything more complex.

Read up on the lock statement.



Here is an example of the Microsoft Queue object wrapped so all actions against it are thread safe.

public class Queue<T>
    /// <summary>Used as a lock target to ensure thread safety.</summary>
    private readonly Locker _Locker = new Locker();

    private readonly System.Collections.Generic.Queue<T> _Queue = new System.Collections.Generic.Queue<T>();

    /// <summary></summary>
    public void Enqueue(T item)
        lock (_Locker)

    /// <summary>Enqueues a collection of items into this queue.</summary>
    public virtual void EnqueueRange(IEnumerable<T> items)
        lock (_Locker)
            if (items == null)

            foreach (T item in items)

    /// <summary></summary>
    public T Dequeue()
        lock (_Locker)
            return _Queue.Dequeue();

    /// <summary></summary>
    public void Clear()
        lock (_Locker)

    /// <summary></summary>
    public Int32 Count
            lock (_Locker)
                return _Queue.Count;

    /// <summary></summary>
    public Boolean TryDequeue(out T item)
        lock (_Locker)
            if (_Queue.Count > 0)
                item = _Queue.Dequeue();
                return true;
                item = default(T);
                return false;


I hope this example helps. Remember this is bare bones. Using these basic ideas you can safely harness the power of threads.

public class WorkState
    private readonly Object _Lock = new Object();
    private Int32 _State;

    public Int32 GetState()
        lock (_Lock)
            return _State;

    public void UpdateState()
        lock (_Lock)

public class Worker
    private readonly WorkState _State;
    private readonly Thread _Thread;
    private volatile Boolean _KeepWorking;

    public Worker(WorkState state)
        _State = state;
        _Thread = new Thread(DoWork);
        _KeepWorking = true;                

    public void DoWork()
        while (_KeepWorking)

    public void StartWorking()

    public void StopWorking()
        _KeepWorking = false;

private void Execute()
    WorkState state = new WorkState();
    Worker worker = new Worker(state);


    while (true)
        if (state.GetState() > 100)

Add image to left of text via css

Very simple method:

.create:before {
content: url(image.png);

Works in all modern browsers and IE8+.


Don't use this on large sites though. The :before pseudo-element is horrible in terms of performance.

Email address validation using ASP.NET MVC data type attributes

As per the above this will fix server side validation of an Email Address:

[Display(Name = "Email address")]
[Required(ErrorMessage = "The email address is required")]
[EmailAddress(ErrorMessage = "Invalid Email Address")]
public string Email { get; set; }


If you are using JQuery client side validation you should know that the Email validates differently server side (model validation) to client side (JQuery validation). In that test@example (a top level domain email address) would fail server side but would validate fine on the client side.

To fix this disparity you can override the default client side email validation as follows:

$ = function (value, element) {
    return this.optional(element) || /^[a-z0-9._]+@[a-z]+\.[a-z.]+/.test(value);

Java "user.dir" property - what exactly does it mean?

user.dir is the "User working directory" according to the Java Tutorial, System Properties

What is a "web service" in plain English?

Web services are almost like normal a web page. The difference is that they are formatted to make it very easy for a program to pull data from the page, to the point of probably not using any HTML. They generally also are more reliable as to the consistency of the format, may use a different formal process to define the content such soap or raw xml, and there is often also a descriptor document that formally defines the structure for the data.

MySQL timezone change?

Here is how to synchronize PHP (>=5.3) and MySQL timezones per session and user settings. Put this where it runs when you need set and synchronized timezones.

$n = new \DateTime();
$h = $n->getOffset()/3600;
$i = 60*($h-floor($h));
$offset = sprintf('%+d:%02d', $h, $i);
$this->db->query("SET time_zone='$offset'");

Where $my_timezone is one in the list of PHP timezones:

The PHP timezone has to be converted into the hour and minute offset for MySQL. That's what lines 1-4 do.

How can I define an interface for an array of objects with Typescript?

Use like this!

interface Iinput {
  label: string
  placeholder: string
  register: any
  type?: string
  required: boolean

// This is how it can be done

const inputs: Array<Iinput> = [
    label: "Title",
    placeholder: "Bought something",
    register: register,
    required: true,

How can I select rows by range?

Following your clarification you're looking for limit:

SELECT * FROM `table` LIMIT 0, 10 

This will display the first 10 results from the database.

SELECT * FROM `table` LIMIT 5, 5 .

Will display 5-9 (5,6,7,8,9)

The syntax follows the pattern:

SELECT * FROM `table` LIMIT [row to start at], [how many to include] .

The SQL for selecting rows where a column is between two values is:

SELECT column_name(s)
FROM table_name
WHERE column_name
BETWEEN value1 AND value2


If you want to go on the row number you can use rownum:

SELECT column_name(s)
FROM table_name
WHERE rownum 

However we need to know which database engine you are using as rownum is different for most.

IF EXISTS condition not working with PLSQL

IF EXISTS() is semantically incorrect. EXISTS condition can be used only inside a SQL statement. So you might rewrite your pl/sql block as follows:

  l_exst number(1);
  select case 
           when exists(select ce.s_regno 
                         from courseoffering co
                         join co_enrolment ce
                           on ce.co_id = co.co_id
                        where ce.s_regno=403 
                          and ce.coe_completionstatus = 'C' 
                          and ce.c_id = 803
                          and rownum = 1
           then 1
           else 0
         end  into l_exst
  from dual;

  if l_exst = 1 
    DBMS_OUTPUT.put_line('YES YOU CAN');
    DBMS_OUTPUT.put_line('YOU CANNOT'); 
  end if;

Or you can simply use count function do determine the number of rows returned by the query, and rownum=1 predicate - you only need to know if a record exists:

  l_exst number;
   select count(*) 
     into l_exst
     from courseoffering co
          join co_enrolment ce
            on ce.co_id = co.co_id
    where ce.s_regno=403 
      and ce.coe_completionstatus = 'C' 
      and ce.c_id = 803
      and rownum = 1;

  if l_exst = 0
    DBMS_OUTPUT.put_line('YOU CANNOT');
    DBMS_OUTPUT.put_line('YES YOU CAN');
  end if;

Get all validation errors from Angular 2 FormGroup

For a large FormGroup tree, you can use lodash to clean up the tree and get a tree of just the controls with errors. This is done by recurring through child controls (e.g. using allErrors(formGroup)), and pruning any fully-valid sub groups of controls:

private isFormGroup(control: AbstractControl): control is FormGroup {
  return !!(<FormGroup>control).controls;

// Returns a tree of any errors in control and children of control
allErrors(control: AbstractControl): any {
  if (this.isFormGroup(control)) {
    const childErrors = _.mapValues(control.controls, (childControl) => {
      return this.allErrors(childControl);

    const pruned = _.omitBy(childErrors, _.isEmpty);
    return _.isEmpty(pruned) ? null : pruned;
  } else {
    return control.errors;

How to convert QString to std::string?

One of the things you should remember when converting QString to std::string is the fact that QString is UTF-16 encoded while std::string... May have any encodings.

So the best would be either:

QString qs;

// Either this if you use UTF-8 anywhere
std::string utf8_text = qs.toUtf8().constData();

// or this if you're on Windows :-)
std::string current_locale_text = qs.toLocal8Bit().constData();

The suggested (accepted) method may work if you specify codec.


Angular @ViewChild() error: Expected 2 arguments, but got 1

In Angular 8, ViewChild always takes 2 param, and second params always has static: true or static: false

You can try like this:

@ViewChild('nameInput', {static: false}) component

Also,the static: false is going to be the default fallback behaviour in Angular 9.

What are static false/true: So as a rule of thumb you can go for the following:

  • { static: true } needs to be set when you want to access the ViewChild in ngOnInit.

    { static: false } can only be accessed in ngAfterViewInit. This is also what you want to go for when you have a structural directive (i.e. *ngIf) on your element in your template.

How do I increase the scrollback buffer in a running screen session?

There is a minimal amount of "default" buffer when you startup a 'screen' session within your 'putty session'. I use screens a lot in my work, so I can tell you that you will not have a combination of 'screen' buffer & 'putty' buffer within your 'screen' session.

Setting the default number of scrollback lines by adding defscrollback 10000 to your ~/.screenrc file is the correct solution.

By the way, I use "defscrollback 200000" in my ./screenrc file.

Add onClick event to document.createElement("th")

var newTH = document.createElement('th');
newTH.addEventListener( 'click', function(){
  // delete the column here
} );

How to unset a JavaScript variable?

Variables, in contrast with simple properties, have attribute [[Configurable]], meaning impossibility to remove a variable via the delete operator. However there is one execution context on which this rule does not affect. It is the eval context: there [[Configurable]] attribute is not set for variables.

How to use wait and notify in Java without IllegalMonitorStateException?

Do you need to thread this at all ? I'm wondering how big your matrices are, and whether there's any benefit in having one thread print whilst the other does the multiplication.

Perhaps it would be worth measuring this time before doing the relatively complex threading work ?

If you do need to thread it, I would create 'n' threads to perform the multiplication of the cells (perhaps 'n' is the number of cores available to you), and then use the ExecutorService and Future mechanism to dispatch multiple multiplications simultaneously.

That way you can optimise the work based on the number of cores, and you're using the higher level Java threading tools (which should make life easier). Write the results back into a receiving matrix, and then simply print this once all your Future tasks have completed.

PHP check if file is an image

The getimagesize() should be the most definite way of working out whether the file is an image:

    $image = true;
} else {
    $image = false;

because this is a sample getimagesize() output:

Array (
[0] => 800
[1] => 450
[2] => 2
[3] => width="800" height="450"
[bits] => 8
[channels] => 3
[mime] => image/jpeg)

How do you make a div follow as you scroll?

You can use the fixed CSS position property to accomplish this. There is a basic tutorial on this here.

EDIT: However, this approach is NOT supported in IE versions < IE7, and only in IE7 if it is in standards mode. This is discussed in a little more detail here.

There is also a hack, explained here, that shows how to accomplish fixed positioning in IE6 without affecting absolute positioning. What version of IE are you targeting your website for?

Show Current Location and Nearby Places and Route between two places using Google Maps API in Android

Lots of answers so far, which are all excellent pointers to API's and tutorials. One thing I'd like to add is that I work out how far the markers are from my location using something like:

float distance = (float) loc.distanceTo(loc2);

Hope this helps refine the detail for your problem. It returns a rough estimate of distance (in m) between points, and is useful for getting rid of POI that might be too far away - good to declutter your map?

How can I find which tables reference a given table in Oracle SQL Developer?

How about something like this:

SELECT c.constraint_name, c.constraint_type, c2.constraint_name, c2.constraint_type, c2.table_name
  FROM dba_constraints c JOIN dba_constraints c2 ON (c.r_constraint_name = c2.constraint_name)
 WHERE c.table_name = <TABLE_OF_INTEREST>
   AND c.constraint_TYPE = 'R';

Tomcat - maxThreads vs maxConnections

Tomcat can work in 2 modes:

  • BIO – blocking I/O (one thread per connection)
  • NIOnon-blocking I/O (many more connections than threads)

Tomcat 7 is BIO by default, although consensus seems to be "don't use Bio because Nio is better in every way". You set this using the protocol parameter in the server.xml file.

  • BIO will be HTTP/1.1 or org.apache.coyote.http11.Http11Protocol
  • NIO will be org.apache.coyote.http11.Http11NioProtocol

If you're using BIO then I believe they should be more or less the same.

If you're using NIO then actually "maxConnections=1000" and "maxThreads=10" might even be reasonable. The defaults are maxConnections=10,000 and maxThreads=200. With NIO, each thread can serve any number of connections, switching back and forth but retaining the connection so you don't need to do all the usual handshaking which is especially time-consuming with HTTPS but even an issue with HTTP. You can adjust the "keepAlive" parameter to keep connections around for longer and this should speed everything up.

CMD (command prompt) can't go to the desktop

You need to use the change directory command 'cd' to change directory

cd C:\Users\MyName\Desktop

you can use cd \d to change the drive as well.

link for additional resources

PHP code is not being executed, instead code shows on the page

i had similar problem but in my case solution was different. my file that held php code was called "somename.html" changed it to "somename.php" worked fine

What is the difference between 'my' and 'our' in Perl?

Coping with Scoping is a good overview of Perl scoping rules. It's old enough that our is not discussed in the body of the text. It is addressed in the Notes section at the end.

The article talks about package variables and dynamic scope and how that differs from lexical variables and lexical scope.

ScrollIntoView() causing the whole page to move

Adding more information to @Jesco post.

  • Element.scrollIntoViewIfNeeded() non-standard WebKit method for Chrome, Opera, Safari browsers.
    If the element is already within the visible area of the browser window, then no scrolling takes place.
  • Element.scrollIntoView() method scrolls the element on which it's called into the visible area of the browser window.

Try the below code in scrollIntoView() link. Post to identify Browser

var xpath = '//*[@id="Notes"]';

function ScrollToElement(xpath) {
    var ele = $x(xpath)[0];
    console.log( ele );

    var isChrome = !! && (!! || !!;
    if (isChrome) { // Chrome
    } else {
        var inlineCenter = { behavior: 'smooth', block: 'center', inline: 'start' };

How do I sort an observable collection?

I found a relevant blog entry that provides a better answer than the ones here:


The ObservableSortedList that @romkyns points out in the comments automatically maintains sort order.

Implements an observable collection which maintains its items in sorted order. In particular, changes to item properties that result in order changes are handled correctly.

However note also the remark

May be buggy due to the comparative complexity of the interface involved and its relatively poor documentation (see

Command to close an application of console?

So you didn't say you wanted the application to quit or exit abruptly, so as another option, perhaps just have the response loop end out elegantly. (I am assuming you have a while loop waiting for user instructions. This is some code from a project I just wrote today.

        Console.WriteLine("College File Processor");
        Console.WriteLine("Process (W)orkouts");
        Console.WriteLine("Process (I)nterviews");
        Console.WriteLine("Process (P)ro Days");
        Console.WriteLine("(S)tart Processing");

        string response = "";
        string videotype = "";
        bool starting = false;
        bool exiting = false;

        response = Console.ReadLine();

        while ( response != "" )
            switch ( response  )
                case "H":
                case "h":

                case "W":
                case "w":
                    Console.WriteLine("Video Type set to Workout");
                    videotype = "W";

                case "I":
                case "i":
                    Console.WriteLine("Video Type set to Interview");
                    videotype = "I";

                case "P":
                case "p":
                    Console.WriteLine("Video Type set to Pro Day");
                    videotype = "P";

                case "S":
                case "s":
                    if ( videotype == "" )
                        Console.WriteLine("Please Select Video Type Before Starting");
                        starting = true;

                case "E":
                case "e":
                    Console.WriteLine("Good Bye!");
                    exiting = true;

            if ( starting || exiting)
                response = Console.ReadLine();

        if ( starting )

How do I remove  from the beginning of a file?

In Notepad++, choose the "Encoding" menu, then "Encode in UTF-8 without BOM". Then save.

See Stack Overflow question How to make Notepad to save text in UTF-8 without BOM?.

Perl regular expression (using a variable as a search string with Perl operator characters included)

Use the quotemeta function:

$text_to_search = "example text with [foo] and more";
$search_string = quotemeta "[foo]";

print "wee" if ($text_to_search =~ /$search_string/);

How to get Python requests to trust a self signed SSL certificate?

With the verify parameter you can provide a custom certificate authority bundle

requests.get(url, verify=path_to_bundle_file)

From the docs:

You can pass verify the path to a CA_BUNDLE file with certificates of trusted CAs. This list of trusted CAs can also be specified through the REQUESTS_CA_BUNDLE environment variable.

How to access global variables

I suggest use the common way of import.

First I will explain the way it called "relative import" maybe this way cause of some error

Second I will explain the common way of import.


In go version >= 1.12 there is some new tips about import file and somethings changed.

1- You should put your file in another folder for example I create a file in "model" folder and the file's name is "example.go"

2- You have to use uppercase when you want to import a file!

3- Use Uppercase for variables, structures and functions that you want to import in another files

Notice: There is no way to import the main.go in another file.

file directory is:


this is a example.go:

package model

import (

var StartTime = time.Now()

and this is main.go you should use uppercase when you want to import a file. "Mod" started with uppercase

package main

import (
    Mod "./model"

func main() {


NOTE: I don't recommend this this type of import!


(normal import)

the better way import file is:

your structure should be like this:

         |                |__________Your-project-name
         |                                |________main.go
         |                                |________handlers
         |                                |________models

and this is a example:

package main

import (

func main(){
     //you can use sessions here

so you can import "" in every where that you want...just import it.

Where do I put my php files to have Xampp parse them?

in XAMPP the default root is "htdocs" inside the XAMPP folder, if you followed the instructions on the xampp homepage it would be "/opt/lampp/htdocs"

Fast way to discover the row count of a table in PostgreSQL

Counting rows in big tables is known to be slow in PostgreSQL. To get a precise number it has to do a full count of rows due to the nature of MVCC. There is a way to speed this up dramatically if the count does not have to be exact like it seems to be in your case.

Instead of getting the exact count (slow with big tables):

SELECT count(*) AS exact_count FROM myschema.mytable;

You get a close estimate like this (extremely fast):

SELECT reltuples::bigint AS estimate FROM pg_class where relname='mytable';

How close the estimate is depends on whether you run ANALYZE enough. It is usually very close.
See the PostgreSQL Wiki FAQ.
Or the dedicated wiki page for count(*) performance.

Better yet

The article in the PostgreSQL Wiki is was a bit sloppy. It ignored the possibility that there can be multiple tables of the same name in one database - in different schemas. To account for that:

SELECT c.reltuples::bigint AS estimate
FROM   pg_class c
JOIN   pg_namespace n ON n.oid = c.relnamespace
WHERE  c.relname = 'mytable'
AND    n.nspname = 'myschema'

Or better still

SELECT reltuples::bigint AS estimate
FROM   pg_class
WHERE  oid = 'myschema.mytable'::regclass;

Faster, simpler, safer, more elegant. See the manual on Object Identifier Types.

Use to_regclass('myschema.mytable') in Postgres 9.4+ to avoid exceptions for invalid table names:

TABLESAMPLE SYSTEM (n) in Postgres 9.5+

SELECT 100 * count(*) AS estimate FROM mytable TABLESAMPLE SYSTEM (1);

Like @a_horse commented, the newly added clause for the SELECT command might be useful if statistics in pg_class are not current enough for some reason. For example:

  • No autovacuum running.
  • Immediately after a big INSERT or DELETE.
  • TEMPORARY tables (which are not covered by autovacuum).

This only looks at a random n % (1 in the example) selection of blocks and counts rows in it. A bigger sample increases the cost and reduces the error, your pick. Accuracy depends on more factors:

  • Distribution of row size. If a given block happens to hold wider than usual rows, the count is lower than usual etc.
  • Dead tuples or a FILLFACTOR occupy space per block. If unevenly distributed across the table, the estimate may be off.
  • General rounding errors.

In most cases the estimate from pg_class will be faster and more accurate.

Answer to actual question

First, I need to know the number of rows in that table, if the total count is greater than some predefined constant,

And whether it ...

... is possible at the moment the count pass my constant value, it will stop the counting (and not wait to finish the counting to inform the row count is greater).

Yes. You can use a subquery with LIMIT:

SELECT count(*) FROM (SELECT 1 FROM token LIMIT 500000) t;

Postgres actually stops counting beyond the given limit, you get an exact and current count for up to n rows (500000 in the example), and n otherwise. Not nearly as fast as the estimate in pg_class, though.

Using ng-if as a switch inside ng-repeat?

I will suggest move all templates to separate files, and don't do spagetti inside repeat

take a look here:


<div ng-repeat = "data in comments">
    <div ng-include src="buildUrl(data.type)"></div>


var app = angular.module('plunker', []);
app.controller('MainCtrl', function($scope) {

  $scope.comments = [

  $scope.buildUrl = function(type) {
    return type + '.html';

How to implement my very own URI scheme on Android

As the question is asked years ago, and Android is evolved a lot on this URI scheme.
From original URI scheme, to deep link, and now Android App Links.

Android now recommends to use HTTP URLs, not define your own URI scheme. Because Android App Links use HTTP URLs that link to a website domain you own, so no other app can use your links. You can check the comparison of deep link and Android App links from here

Now you can easily add a URI scheme by using Android Studio option: Tools > App Links Assistant. Please refer the detail to Android document:

How to declare a global variable in C++

Declare extern int x; in file.h. And define int x; only in one cpp file.cpp.

Delete column from pandas DataFrame

A nice addition is the ability to drop columns only if they exist. This way you can cover more use cases, and it will only drop the existing columns from the labels passed to it:

Simply add errors='ignore', for example.:

df.drop(['col_name_1', 'col_name_2', ..., 'col_name_N'], inplace=True, axis=1, errors='ignore')
  • This is new from pandas 0.16.1 onward. Documentation is here.

How to make layout with rounded corners..?

For API 21+, Use Clip Views

Rounded outline clipping was added to the View class in API 21. See this training doc or this reference for more info.

This in-built feature makes rounded corners very easy to implement. It works on any view or layout and supports proper clipping.

Here's What To Do:

  • Create a rounded shape drawable and set it as your view's background: android:background="@drawable/round_outline"
  • Clip to outline in code: setClipToOutline(true)

The documentation used to say that you can set android:clipToOutline="true" the XML, but this bug is now finally resolved and the documentation now correctly states that you can only do this in code.

What It Looks Like:

examples with and without clipToOutline

Special Note About ImageViews

setClipToOutline() only works when the View's background is set to a shape drawable. If this background shape exists, View treats the background's outline as the borders for clipping and shadowing purposes.

This means that if you want to round the corners on an ImageView with setClipToOutline(), your image must come from android:src instead of android:background (since background is used for the rounded shape). If you MUST use background to set your image instead of src, you can use this nested views workaround:

  • Create an outer layout with its background set to your shape drawable
  • Wrap that layout around your ImageView (with no padding)
  • The ImageView (including anything else in the layout) will now be clipped to the outer layout's rounded shape.

Modifying list while iterating

This slice syntax makes a copy of the list and does what you want:

l  = range(100)  
for i in l[:]:  
    print i,  
    print l.pop(0),  
    print l.pop(0)

What's the fastest way to delete a large folder in Windows?

use the command prompt, as suggested. I figured out why explorer is so slow a while ago, it gives you an estimate of how long it will take to delete the files/folders. To do this, it has to scan the number of items and the size. This takes ages, hence the ridiculous wait with large folders.

Also, explorer will stop if there is a particular problem with a file,

How to check programmatically if an application is installed or not in Android?

I think using try/catch pattern is not very well for performance. I advice to use this:

public static boolean appInstalledOrNot(Context context, String uri) {
    PackageManager pm = context.getPackageManager();
    List<PackageInfo> packageInfoList = pm.getInstalledPackages(PackageManager.GET_ACTIVITIES);
    if (packageInfoList != null) {
        for (PackageInfo packageInfo : packageInfoList) {
            String packageName = packageInfo.packageName;
            if (packageName != null && packageName.equals(uri)) {
                return true;
    return false;

MySQL compare now() (only date, not time) with a datetime field

Compare date only instead of date + time (NOW) with:


How can I align text directly beneath an image?

I am not an expert in HTML but here is what worked for me:

<div class="img-with-text-below">
    <img src="your-image.jpg" alt="alt-text" />
    <p><center>Your text</center></p>

Error creating bean with name 'entityManagerFactory' defined in class path resource : Invocation of init method failed

Try to annotate the class with @EnableTransactionManagement. I was facing the same issue and it got resolved by adding this.

public class ConfigurationBean {

Posting a File and Associated Data to a RESTful WebService preferably as JSON

I know that this thread is quite old, however, I am missing here one option. If you have metadata (in any format) that you want to send along with the data to upload, you can make a single multipart/related request.

The Multipart/Related media type is intended for compound objects consisting of several inter-related body parts.

You can check RFC 2387 specification for more in-depth details.

Basically each part of such a request can have content with different type and all parts are somehow related (e.g. an image and it metadata). The parts are identified by a boundary string, and the final boundary string is followed by two hyphens.


POST /upload HTTP/1.1
Content-Type: multipart/related; boundary=xyz
Content-Length: [actual-content-length]

Content-Type: application/json; charset=UTF-8

    "name": "Sample image",
    "desc": "...",

Content-Type: image/jpeg

[image data]
[image data]
[image data]

Remove duplicate values from JS array

For anyone looking to flatten arrays with duplicate elements into one unique array:

function flattenUniq(arrays) {
  var args =;

  var array = [].concat.apply([], args)

  var result = array.reduce(function(prev, curr){
    if (prev.indexOf(curr) < 0) prev.push(curr);
    return prev;

  return result;

Hide options in a select list using jQuery

Having tested, the solutions posted above by various, including chaos, to hide elements do now work in the latest versions of Firefox (66.0.4), Chrome (74.0.3729.169) and Edge (42.17134.1.0)

$("#edit-field-service-sub-cat-value option[value=" + title + "]").hide();
$("#edit-field-service-sub-cat-value option[value=" + title + "]").show();

For IE, this does not work, however you can disable the option

$("#edit-field-service-sub-cat-value option[value=" + title + "]").attr("disabled", "disabled");
$("#edit-field-service-sub-cat-value option[value=" + title + "]").removeAttr("disabled");

and then force the selection of a different value.


Note, for a disabled option, the val of the drop down will now be null, not the value of the selected option if it is disabled.

How to split a string after specific character in SQL Server and update this value to specific column

Try this:

UPDATE YourTable
SET Col2 = RIGHT(Col1,LEN(Col1)-CHARINDEX('/',Col1))

AJAX Mailchimp signup form integration

You should use the server-side code in order to secure your MailChimp account.

The following is an updated version of this answer which uses PHP:

The PHP files are "secured" on the server where the user never sees them yet the jQuery can still access & use.

1) Download the PHP 5 jQuery example here...

If you only have PHP 4, simply download version 1.2 of the MCAPI and replace the corresponding MCAPI.class.php file above.

2) Follow the directions in the Readme file by adding your API key and List ID to the store-address.php file at the proper locations.

3) You may also want to gather your users' name and/or other information. You have to add an array to the store-address.php file using the corresponding Merge Variables.

Here is what my store-address.php file looks like where I also gather the first name, last name, and email type:


function storeAddress(){

    require_once('MCAPI.class.php');  // same directory as store-address.php

    // grab an API Key from
    $api = new MCAPI('123456789-us2');

    $merge_vars = Array( 
        'EMAIL' => $_GET['email'],
        'FNAME' => $_GET['fname'], 
        'LNAME' => $_GET['lname']

    // grab your List's Unique Id by going to
    // Click the "settings" link for the list - the Unique Id is at the bottom of that page. 
    $list_id = "123456a";

    if($api->listSubscribe($list_id, $_GET['email'], $merge_vars , $_GET['emailtype']) === true) {
        // It worked!   
        return 'Success!&nbsp; Check your inbox or spam folder for a message containing a confirmation link.';
        // An error ocurred, return error message   
        return '<b>Error:</b>&nbsp; ' . $api->errorMessage;


// If being called via ajax, autorun the function
if($_GET['ajax']){ echo storeAddress(); }

4) Create your HTML/CSS/jQuery form. It is not required to be on a PHP page.

Here is something like what my index.html file looks like:

<form id="signup" action="index.html" method="get">
    <input type="hidden" name="ajax" value="true" />
    First Name: <input type="text" name="fname" id="fname" />
    Last Name: <input type="text" name="lname" id="lname" />
    email Address (required): <input type="email" name="email" id="email" />
    HTML: <input type="radio" name="emailtype" value="html" checked="checked" />
    Text: <input type="radio" name="emailtype" value="text" />
    <input type="submit" id="SendButton" name="submit" value="Submit" />
<div id="message"></div>

<script src="jquery.min.js" type="text/javascript"></script>
<script type="text/javascript"> 
$(document).ready(function() {
    $('#signup').submit(function() {
        $("#message").html("<span class='error'>Adding your email address...</span>");
            url: 'inc/store-address.php', // proper url to your "store-address.php" file
            data: $('#signup').serialize(),
            success: function(msg) {
        return false;

Required pieces...

  • index.html constructed as above or similar. With jQuery, the appearance and options are endless.

  • store-address.php file downloaded as part of PHP examples on Mailchimp site and modified with your API KEY and LIST ID. You need to add your other optional fields to the array.

  • MCAPI.class.php file downloaded from Mailchimp site (version 1.3 for PHP 5 or version 1.2 for PHP 4). Place it in the same directory as your store-address.php or you must update the url path within store-address.php so it can find it.

How to create a data file for gnuplot?

Just go to the properties of your cmd.exe shortcut and change the 'start in' by adding the file name where you put all your '.txt' files.I had same problems and i put the whole file mane as 'D:\photon' in the 'start in' of the properties and it worked.Remember you have to put all your files in that folder otherwise you have to create many shortcuts for each data files.Sorry for late reply

ld cannot find -l<library>

I had a similar problem with another library and the reason why it didn't found it, was that I didn't run the make install (after running ./configure and make) for that library. The make install may require root privileges (in this case use: sudo make install). After running the make install you should have the so files in the correct folder, i.e. here /usr/local/lib and not in the folder mentioned by you.

What are the uses of the exec command in shell scripts?

The exec built-in command mirrors functions in the kernel, there are a family of them based on execve, which is usually called from C.

exec replaces the current program in the current process, without forking a new process. It is not something you would use in every script you write, but it comes in handy on occasion. Here are some scenarios I have used it;

  1. We want the user to run a specific application program without access to the shell. We could change the sign-in program in /etc/passwd, but maybe we want environment setting to be used from start-up files. So, in (say) .profile, the last statement says something like:

     exec appln-program

    so now there is no shell to go back to. Even if appln-program crashes, the end-user cannot get to a shell, because it is not there - the exec replaced it.

  2. We want to use a different shell to the one in /etc/passwd. Stupid as it may seem, some sites do not allow users to alter their sign-in shell. One site I know had everyone start with csh, and everyone just put into their .login (csh start-up file) a call to ksh. While that worked, it left a stray csh process running, and the logout was two stage which could get confusing. So we changed it to exec ksh which just replaced the c-shell program with the korn shell, and made everything simpler (there are other issues with this, such as the fact that the ksh is not a login-shell).

  3. Just to save processes. If we call prog1 -> prog2 -> prog3 -> prog4 etc. and never go back, then make each call an exec. It saves resources (not much, admittedly, unless repeated) and makes shutdown simplier.

You have obviously seen exec used somewhere, perhaps if you showed the code that's bugging you we could justify its use.

Edit: I realised that my answer above is incomplete. There are two uses of exec in shells like ksh and bash - used for opening file descriptors. Here are some examples:

exec 3< thisfile          # open "thisfile" for reading on file descriptor 3
exec 4> thatfile          # open "thatfile" for writing on file descriptor 4
exec 8<> tother           # open "tother" for reading and writing on fd 8
exec 6>> other            # open "other" for appending on file descriptor 6
exec 5<&0                 # copy read file descriptor 0 onto file descriptor 5
exec 7>&4                 # copy write file descriptor 4 onto 7
exec 3<&-                 # close the read file descriptor 3
exec 6>&-                 # close the write file descriptor 6

Note that spacing is very important here. If you place a space between the fd number and the redirection symbol then exec reverts to the original meaning:

  exec 3 < thisfile       # oops, overwrite the current program with command "3"

There are several ways you can use these, on ksh use read -u or print -u, on bash, for example:

read <&3
echo stuff >&4

Access to Image from origin 'null' has been blocked by CORS policy

The problem was actually solved by providing crossOrigin: null to OpenLayers OSM source:

var newLayer = new ol.layer.Tile({
source: new ol.source.OSM({
    url: 'E:/Maperitive/Tiles/vychod/{z}/{x}/{y}.png',
    crossOrigin: null

Commenting code in Notepad++

In your n++ editor, you can go to Setting > Shortcut mapper and find all shortcut information as well as you can edit them :)

React JS - Uncaught TypeError: is not a function

If you're using react hooks you have to make sure that data was initialized as an array. Here's is how it must look like:

const[data, setData] = useState([])

Get value of a merged cell of an excel from its cell address in vba

Even if it is really discouraged to use merge cells in Excel (use Center Across Selection for instance if needed), the cell that "contains" the value is the one on the top left (at least, that's a way to express it).

Hence, you can get the value of merged cells in range B4:B11 in several ways:

  • Range("B4").Value
  • Range("B4:B11").Cells(1).Value
  • Range("B4:B11").Cells(1,1).Value

You can also note that all the other cells have no value in them. While debugging, you can see that the value is empty.

Also note that Range("B4:B11").Value won't work (raises an execution error number 13 if you try to Debug.Print it) because it returns an array.

How to throw an exception in C?

If you write code with Happy path design pattern (i.e. for embedded device) you may simulate exception error processing (aka deffering or finally emulation) with operator "goto".

int process(int port)
    int rc;
    int fd1;
    int fd2;

    fd1 = open("/dev/...", ...);
    if (fd1 == -1) {
      rc = -1;
      goto out;

    fd2 = open("/dev/...", ...);
    if (fd2 == -1) {
      rc = -1;
      goto out;

    // Do some with fd1 and fd2 for example write(f2, read(fd1))

    rc = 0;


    //if (rc != 0) {

    return rc;

It does not actually exception handler but it take you a way to handle error at fucntion exit.

P.S. You should be careful use goto only from same or more deep scopes and never jump variable declaration.

java.lang.NullPointerException: Attempt to invoke virtual method on a null object reference

Your app is crashing at:

welcomePlayer.setText("Welcome Back, " + String.valueOf(mPlayer.getName(this)) + " !");

because mPlayer=null.

You forgot to initialize Player mPlayer in your PlayGame Activity.

mPlayer = new Player(context,"");

Bin size in Matplotlib (Histogram)

For N bins, the bin edges are specified by list of N+1 values where the first N give the lower bin edges and the +1 gives the upper edge of the last bin.


from numpy import np; from pylab import *

bin_size = 0.1; min_edge = 0; max_edge = 2.5
N = (max_edge-min_edge)/bin_size; Nplus1 = N + 1
bin_list = np.linspace(min_edge, max_edge, Nplus1)

Note that linspace produces array from min_edge to max_edge broken into N+1 values or N bins

Ruby value of a hash key?

As an addition to e.g. @Intrepidd s answer, in certain situations you want to use fetch instead of []. For fetch not to throw an exception when the key is not found, pass it a default value.

puts "ok" if hash.fetch('key', nil) == 'X'

Reference: .

Scrolling a div with jQuery

I don't know if this is exactly what you want, but did you know you can use the CSS overflow property to create scrollbars?

  width: 200px;
  height: 200px;
  overflow: scroll;


<div class="box">
  All your text content...

How to get a barplot with several variables side by side grouped by a factor

You can plot the means without resorting to external calculations and additional tables using stat_summary(...). In fact, stat_summary(...) was designed for exactly what you are doing.

library(reshape2)            # for melt(...)
gg <- melt(df,id="gender")   # df is your original table
ggplot(gg, aes(x=variable, y=value, fill=factor(gender))) + 
  stat_summary(fun.y=mean, geom="bar",position=position_dodge(1)) + 
               color="grey80",position=position_dodge(1), width=.2)

To add "error bars" you cna also use stat_summary(...) (here, I'm using the min and max value rather than sd because you have so little data).

ggplot(gg, aes(x=variable, y=value, fill=factor(gender))) + 
  stat_summary(fun.y=mean, geom="bar",position=position_dodge(1)) + 
               color="grey40",position=position_dodge(1), width=.2) +

Error 6 (net::ERR_FILE_NOT_FOUND): The files c or directory could not be found

I have solved this issue as follows:

removed from chrome extension and install ext again. It will work ISA

Exposing the current state name with ui router

In my current project the solution looks like this:

I created an abstract Language State

$stateProvider.state('language', {
    abstract: true,
    url: '/:language',
    template: '<div ui-view class="lang-{{language}}"></div>'

Every state in the project has to depend on this state

$stateProvider.state('language.dashboard', {
    url: '/dashboard'

The language switch buttons calls a custom function:

<a ng-click="footer.setLanguage('de')">de</a>

And the corresponding function looks like this (inside a controller of course):

this.setLanguage = function(lang) {
    FooterLog.log('switch to language', lang);
    $state.go($state.current, { language: lang }, {
        location: true,
        reload: true,
        inherit: true
    }).then(function() {
        FooterLog.log('transition successfull');

This works, but there is a nicer solution just changing a value in the state params from html:

<a ui-sref="{ language: 'de' }">de</a>

Unfortunately this does not work, see

SQL Query - SUM(CASE WHEN x THEN 1 ELSE 0) for multiple columns

I would change the query in the following ways:

  1. Do the aggregation in subqueries. This can take advantage of more information about the table for optimizing the group by.
  2. Combine the second and third subqueries. They are aggregating on the same column. This requires using a left outer join to ensure that all data is available.
  3. By using count(<fieldname>) you can eliminate the comparisons to is null. This is important for the second and third calculated values.
  4. To combine the second and third queries, it needs to count an id from the mde table. These use mde.mdeid.

The following version follows your example by using union all:

SELECT CAST(Detail.ReceiptDate AS DATE) AS "Date",
       SUM(TOTALMAILED) as TotalMailed,
FROM ((select SentDate AS "ReceiptDate", COUNT(*) as TotalMailed,
       from MailDataExtract
       where SentDate is not null
       group by SentDate
      ) union all
      (select MDE.ReturnMailDate AS ReceiptDate, 0,
              COUNT(distinct mde.mdeid) as TOTALUNDELINOTICESRECEIVED,
              SUM(case when sd.ReturnMailTypeId = 1 then 1 else 0 end) as TRACEUNDELNOTICESRECEIVED
       from MailDataExtract MDE left outer join
            DTSharedData.dbo.ScanData SD
            ON SD.ScanDataID = MDE.ReturnScanDataID
       group by MDE.ReturnMailDate;
     ) detail
GROUP BY CAST(Detail.ReceiptDate AS DATE)

The following does something similar using full outer join:

SELECT coalesce(sd.ReceiptDate, mde.ReceiptDate) AS "Date",
FROM (select cast(SentDate as date) AS "ReceiptDate", COUNT(*) as TotalMailed
      from MailDataExtract
      where SentDate is not null
      group by cast(SentDate as date)
     ) sd full outer join
    (select cast(MDE.ReturnMailDate as date) AS ReceiptDate,
            COUNT(distinct mde.mdeID) as TOTALUNDELINOTICESRECEIVED,
            SUM(case when sd.ReturnMailTypeId = 1 then 1 else 0 end) as TRACEUNDELNOTICESRECEIVED
     from MailDataExtract MDE left outer join
          DTSharedData.dbo.ScanData SD
          ON SD.ScanDataID = MDE.ReturnScanDataID
     group by cast(MDE.ReturnMailDate as date)
    ) mde
    on sd.ReceiptDate = mde.ReceiptDate

How can I use querySelector on to pick an input element by name?

1- you need to close the block of the function with '}', which is missing.

2- the argument of querySelector may not be an empty string '' or ' '... Use '*' for all.

3- those arguments will return the needed value:





Metadata file '.dll' could not be found

aaaaaand six years later during an upgrade to Visual Studio 2015 the same problem. Because this particular solution is not in this list I'm adding to it.

Two referenced dll's were in the c:\windows\system32... folder. Moving them to a non system folder and adding a reference to the new folder fixed it finally. The rest of the issues was indeed what others have said here already

Lookup City and State by Zip Google Geocode Api

couple of months back, I had the same requirement for one of my projects. I searched a bit for it and found out the following solution. This is not the only solution but I found it to one of the simpler one.

Use the webservice at
Specifically GetInfoByZIP() method.

You will be able to query by any zipcode (ex: 40220) and you will have a response back as the following...

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

Hope this helps...

Cannot open solution file in Visual Studio Code

VSCode is a code editor, not a full IDE. Think of VSCode as a notepad on steroids with IntelliSense code completion, richer semantic code understanding of multiple languages, code refactoring, including navigation, keyboard support with customizable bindings, syntax highlighting, bracket matching, auto indentation, and snippets.

It's not meant to replace Visual Studio, but making "Visual Studio" part of the name in VSCode will of course confuse some people at first.

HTML: how to make 2 tables with different CSS

You need to assign different classes to each table.

Create a class in CSS with the dot '.' operator and write your properties inside each class. For example,

.table1 {
//some properties

.table2 {
//Some other properties

and use them in your html code.

INSERT INTO TABLE from comma separated varchar-list

Since there's no way to just pass this "comma-separated list of varchars", I assume some other system is generating them. If you can modify your generator slightly, it should be workable. Rather than separating by commas, you separate by union all select, and need to prepend a select also to the list. Finally, you need to provide aliases for the table and column in you subselect:

Create Table #IMEIS(
    imei varchar(15)
    SELECT * FROM (select '012251000362843' union all select '012251001084784' union all select '012251001168744' union all
                   select '012273007269862' union all select '012291000080227' union all select '012291000383084' union all
                   select '012291000448515') t(Col)

But noting your comment to another answer, about having 5000 entries to add. I believe the 256 tables per select limitation may kick in with the above "union all" pattern, so you'll still need to do some splitting of these values into separate statements.

Nested JSON: How to add (push) new items to an object?

You can achieve this using Lodash _.assign function.

library[title] = _.assign({}, {'foregrounds': foregrounds }, {'backgrounds': backgrounds });

// This is my JSON object generated from a database_x000D_
var library = {_x000D_
  "Gold Rush": {_x000D_
    "foregrounds": ["Slide 1", "Slide 2", "Slide 3"],_x000D_
    "backgrounds": ["1.jpg", "", "2.jpg"]_x000D_
  "California": {_x000D_
    "foregrounds": ["Slide 1", "Slide 2", "Slide 3"],_x000D_
    "backgrounds": ["3.jpg", "4.jpg", "5.jpg"]_x000D_
// These will be dynamically generated vars from editor_x000D_
var title = "Gold Rush";_x000D_
var foregrounds = ["Howdy", "Slide 2"];_x000D_
var backgrounds = ["1.jpg", ""];_x000D_
function save() {_x000D_
  // If title already exists, modify item_x000D_
  if (library[title]) {_x000D_
    // override one Object with the values of another (lodash)_x000D_
    library[title] = _.assign({}, {_x000D_
      'foregrounds': foregrounds_x000D_
    }, {_x000D_
      'backgrounds': backgrounds_x000D_
    // Save to Database. Then on callback..._x000D_
    // console.log('Changes Saved to <b>' + title + '</b>');_x000D_
  // If title does not exist, add new item_x000D_
  else {_x000D_
    // Format it for the JSON object_x000D_
    var item = ('"' + title + '" : {"foregrounds" : ' + foregrounds + ',"backgrounds" : ' + backgrounds + '}');_x000D_
    // Error: "Result of expression 'library.push' [undefined] is not a function"_x000D_
    // Save to Database. Then on callback..._x000D_
    console.log('Added: <b>' + title + '</b>');_x000D_
<script src="[email protected]/lodash.min.js"></script>

Accessing Session Using ASP.NET Web API

Yes, session doesn't go hand in hand with Rest API and also we should avoid this practices. But as per requirements we need to maintain session somehow such that in every request client server can exchange or maintain state or data. So, the best way to achieve this without breaking the REST protocols is communicate through token like JWT.

HTML form with two submit buttons and two "target" attributes

It is more appropriate to approach this problem with the mentality that a form will have a default action tied to one submit button, and then an alternative action bound to a plain button. The difference here is that whichever one goes under the submit will be the one used when a user submits the form by pressing enter, while the other one will only be fired when a user explicitly clicks on the button.

Anyhow, with that in mind, this should do it:

<form id='myform' action='jquery.php' method='GET'>
    <input type='submit' id='btn1' value='Normal Submit'>
    <input type='button' id='btn2' value='New Window'>

With this javascript:

var form = document.getElementById('myform');
form.onsubmit = function() { = '_self';

document.getElementById('btn2').onclick = function() { = '_blank';

Approaches that bind code to the submit button's click event will not work on IE.

Creating NSData from NSString in Swift

Swift 4 & 3

Creating Data object from String object has been changed in Swift 3. Correct version now is:

let data = "any string".data(using: .utf8)

Why is Dictionary preferred over Hashtable in C#?

Collections & Generics are useful for handling group of objects. In .NET, all the collections objects comes under the interface IEnumerable, which in turn has ArrayList(Index-Value)) & HashTable(Key-Value). After .NET framework 2.0, ArrayList & HashTable were replaced with List & Dictionary. Now, the Arraylist & HashTable are no more used in nowadays projects.

Coming to the difference between HashTable & Dictionary, Dictionary is generic where as Hastable is not Generic. We can add any type of object to HashTable, but while retrieving we need to cast it to the required type. So, it is not type safe. But to dictionary, while declaring itself we can specify the type of key and value, so there is no need to cast while retrieving.

Let's look at an example:


class HashTableProgram
    static void Main(string[] args)
        Hashtable ht = new Hashtable();
        ht.Add(1, "One");
        ht.Add(2, "Two");
        ht.Add(3, "Three");
        foreach (DictionaryEntry de in ht)
            int Key = (int)de.Key; //Casting
            string value = de.Value.ToString(); //Casting
            Console.WriteLine(Key + " " + value);



class DictionaryProgram
    static void Main(string[] args)
        Dictionary<int, string> dt = new Dictionary<int, string>();
        dt.Add(1, "One");
        dt.Add(2, "Two");
        dt.Add(3, "Three");
        foreach (KeyValuePair<int, String> kv in dt)
            Console.WriteLine(kv.Key + " " + kv.Value);

CSS Equivalent of the "if" statement

Your stylesheet should be thought of as a static table of available variables that your html document can call on based on what you need to display. The logic should be in your javascript and html, use javascript to dynamically apply attributes based on conditions if you really need to. Stylesheets are not the place for logic.

How to enable C++17 compiling in Visual Studio?

If bringing existing Visual Studio 2015 solution into Visual Studio 2017 and you want to build it with c++17 native compiler, you should first Retarget the solution/projects to v141 , THEN the dropdown will appear as described above ( Configuration Properties -> C/C++ -> Language -> Language Standard)

How to create a simple http proxy in node.js?

Your code doesn't work for binary files because they can't be cast to strings in the data event handler. If you need to manipulate binary files you'll need to use a buffer. Sorry, I do not have an example of using a buffer because in my case I needed to manipulate HTML files. I just check the content type and then for text/html files update them as needed:

app.get('/*', function(clientRequest, clientResponse) {
  var options = { 
    hostname: '',
    port: 80, 
    path: clientRequest.url,
    method: 'GET'

  var googleRequest = http.request(options, function(googleResponse) { 
    var body = ''; 

    if (String(googleResponse.headers['content-type']).indexOf('text/html') !== -1) {
      googleResponse.on('data', function(chunk) {
        body += chunk;

      googleResponse.on('end', function() {
        // Make changes to HTML files when they're done being read.
        body = body.replace(/, host + ':' + port);
        body = body.replace(
          '<script src="http://localhost:3000/new-script.js" type="text/javascript"></script></body>'

        clientResponse.writeHead(googleResponse.statusCode, googleResponse.headers);
    else {
      googleResponse.pipe(clientResponse, {
        end: true


Create table in SQLite only if it doesn't exist already

Am going to try and add value to this very good question and to build on @BrittonKerin's question in one of the comments under @David Wolever's fantastic answer. Wanted to share here because I had the same challenge as @BrittonKerin and I got something working (i.e. just want to run a piece of code only IF the table doesn't exist).

        # for completeness lets do the routine thing of connections and cursors
        conn = sqlite3.connect(db_file, timeout=1000) 

        cursor = conn.cursor() 

        # get the count of tables with the name  
        tablename = 'KABOOM' 
        cursor.execute("SELECT count(name) FROM sqlite_master WHERE type='table' AND name=? ", (tablename, ))

        print(cursor.fetchone()) # this SHOULD BE in a tuple containing count(name) integer.

        # check if the db has existing table named KABOOM
        # if the count is 1, then table exists 
        if cursor.fetchone()[0] ==1 : 
            print('Table exists. I can do my custom stuff here now.... ')
           # then table doesn't exist. 
           custRET = myCustFunc(foo,bar) # replace this with your custom logic

How to make an image center (vertically & horizontally) inside a bigger div

The best way to center an image both vertically and horizontally, is to use two containers, and apply the following properties :

The outher container

  • should have display: table;

The inner container

  • should have display: table-cell;
  • should have vertical-align: middle;
  • should have text-align: center;

A demo

.outer-container {_x000D_
    display: table;_x000D_
    width: 80%; /* can be any width */_x000D_
    height: 120px; /* can be any height */_x000D_
    background: #ccc;_x000D_
.inner-container {_x000D_
    display: table-cell;_x000D_
    vertical-align: middle;_x000D_
    text-align: center;_x000D_
.inner-container img {_x000D_
    background: #fff;_x000D_
    padding : 10px;_x000D_
    border : 1px solid #000;_x000D_
<div class="outer-container">_x000D_
   <div class="inner-container">_x000D_
     <img src="" />_x000D_

Convert StreamReader to byte[]

A StreamReader is for text, not plain bytes. Don't use a StreamReader, and instead read directly from the underlying stream.

HTML.HiddenFor value set

Strange but, Try with @Value , capital "V"

e.g. (working on MVC4)

@Html.HiddenFor(m => m.Id, new { @Value = Model.Id })


Found that @Value (capital V) is creating another attribute with "Value" along with "value", using small @value seems to be working too!

Need to check the MVC source code to find more.

Update, After going through how it works internally:

First of all forget all these workarounds (I have kept in for the sake of continuity here), now looks silly :)

Basically, it happens when a model is posted and the model is returned back to same page.

The value is accessed (and formed into html) in InputHelper method (InputExtensions.cs) using following code fragment

string attemptedValue = (string)htmlHelper.GetModelStateValue(fullName, typeof(string));

The GetModelStateValue method (in Htmlelper.cs) retrieves the value as

ViewData.ModelState.TryGetValue(key, out modelState)

Here is the issue, since the value is accessed from ViewData.ModelState dictionary. This returns the value posted from the page instead of modified value!!

i.e. If your posted value of the variable (e.g. Person.Id) is 0 but you set the value inside httpPost action (e.g. Person.Id = 2), the ModelState still retains the old value "0" and the attemptedValue contains "0" ! so the field in rendered page will contain "0" as value!!

Workaround if you are returning model to same page : Clear the item from ModelState,



This will remove the item from dictionary and the ViewData.ModelState.TryGetValue(key, out modelState) returns null, and the next statement (inside InputExtensions.cs) takes the actual value (valueParameter) passed to HiddenFor(m => m.Id)

this is done in the following line in InputExtensions.cs

tagBuilder.MergeAttribute("value", attemptedValue ?? ((useViewData) ? htmlHelper.EvalString(fullName, format) : valueParameter), isExplicitValue);


Clear the item in ModelState using:


Hope this is helpful.

PHPExcel set border and format for all sheets in spreadsheet

To answer your extra question:

You can set which rows should be repeated on every page using:

$objPHPExcel->getActiveSheet()->getPageSetup()->setRowsToRepeatAtTopByStartAndEnd(1, 5);

Now, row 1, 2, 3, 4 and 5 will be repeated.

Git: How to rebase to a specific commit?

You can even take a direct approach:

git checkout topic
git rebase <commitB>

EditText request focus

>>you can write your code like

  if (TextUtils.isEmpty(username)) {
            editTextUserName.setError("Please enter username");

        if (TextUtils.isEmpty(password)) {
            editTextPassword.setError("Enter a password");

Integrate ZXing in Android Studio

From version 4.x, only Android SDK 24+ is supported by default, and androidx is required.

Add the following to your build.gradle file:

repositories {

dependencies {
    implementation 'com.journeyapps:zxing-android-embedded:4.1.0'
    implementation 'androidx.appcompat:appcompat:1.0.2'

android {
    buildToolsVersion '28.0.3' // Older versions may give compile errors

Older SDK versions

For Android SDK versions < 24, you can downgrade zxing:core to 3.3.0 or earlier for Android 14+ support:

repositories {

dependencies {
    implementation('com.journeyapps:zxing-android-embedded:4.1.0') { transitive = false }
    implementation 'androidx.appcompat:appcompat:1.0.2'
    implementation ''

android {
    buildToolsVersion '28.0.3'

You'll also need this in your Android manifest:

<uses-sdk tools:overrideLibrary="" />

Source :

If '<selector>' is an Angular component, then verify that it is part of this module

  1. Declare your MyComponentComponent in MyComponentModule
  2. Add your MyComponentComponent to exports attribute of MyComponentModule


   imports: [],
   exports: [MyComponentComponent],
   declarations: [MyComponentComponent],
   providers: [],

export class MyComponentModule {
  1. Add your MyComponentModule to your AppModule imports attribute


       imports: [MyComponentModule]
       declarations: [AppComponent],
       providers: [],
       bootstrap: [AppComponent]
    export class AppModule {} 

Important If your still have that error, Stop your server ctrl+c from terminal, and run it again ng serve -o

Adding n hours to a date in Java?

Something like:

Date oldDate = new Date(); // oldDate == current time
final long hoursInMillis = 60L * 60L * 1000L;
Date newDate = new Date(oldDate().getTime() + 
                        (2L * hoursInMillis)); // Adds 2 hours

Unable to run Java GUI programs with Ubuntu

I would check with another Java implementation/vendor. Preferrably Oracle/Sun Java: . The open-source implementations unfortunately differ in weird ways.

SQL Server - Create a copy of a database table and place it in the same database?

This is another option:

select top 0 * into <new_table> from <original_table>

PHP array value passes to next row

Change the checkboxes so that the name includes the index inside the brackets:

<input type="checkbox" class="checkbox_veh" id="checkbox_addveh<?php echo $i; ?>" <?php if ($vehicle_feature[$i]->check) echo "checked"; ?> name="feature[<?php echo $i; ?>]" value="<?php echo $vehicle_feature[$i]->id; ?>"> 

The checkboxes that aren't checked are never submitted. The boxes that are checked get submitted, but they get numbered consecutively from 0, and won't have the same indexes as the other corresponding input fields.

How to change the name of a Django app?

In case you are using PyCharm and project stops working after rename:

  1. Edit Run/Debug configuration and change environment variable DJANGO_SETTINGS_MODULE, since it includes your project name.
  2. Go to Settings / Languages & Frameworks / Django and update the settings file location.

How to modify existing XML file with XmlDocument and XmlNode in C#

You need to do something like this:

// instantiate XmlDocument and load XML from file
XmlDocument doc = new XmlDocument();

// get a list of nodes - in this case, I'm selecting all <AID> nodes under
// the <GroupAIDs> node - change to suit your needs
XmlNodeList aNodes = doc.SelectNodes("/Equipment/DataCollections/GroupAIDs/AID");

// loop through all AID nodes
foreach (XmlNode aNode in aNodes)
   // grab the "id" attribute
   XmlAttribute idAttribute = aNode.Attributes["id"];

   // check if that attribute even exists...
   if (idAttribute != null)
      // if yes - read its current value
      string currentValue = idAttribute.Value;

      // here, you can now decide what to do - for demo purposes,
      // I just set the ID value to a fixed value if it was empty before
      if (string.IsNullOrEmpty(currentValue))
         idAttribute.Value = "515";

// save the XmlDocument back to disk

What does java:comp/env/ do?

After several attempts and going deep in Tomcat's source code I found out that the simple property useNaming="false" did the trick!! Now Tomcat resolves names java:/liferay instead of java:comp/env/liferay

Custom checkbox image android

Another option is to use a ToggleButton with null background and a custom button.

Bellow an example that includes a selector to the text color as well.

    android:textOn="My on state"
    android:textOff="My off state" />


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

        android:drawable="@drawable/state_on" />

        android:drawable="@drawable/state_off" />



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

        android:color="@color/app_color" />

        android:color="@android:color/darker_gray" />


Hide Spinner in Input Number - Firefox 29

/* for chrome */
    input[type=number]::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;}             

/* for mozilla */  
   input[type=number] {-moz-appearance: textfield;}

Android - Get value from HashMap

this work for me:

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

Iterator iterator = meMap.keySet().iterator();
while( iterator. hasNext() )
    Toast.makeText(getBaseContext(), meMap.get(, 

Using ping in c#

private void button26_Click(object sender, EventArgs e)
    System.Diagnostics.ProcessStartInfo proc = new System.Diagnostics.ProcessStartInfo();
    proc.FileName = @"C:\windows\system32\cmd.exe";
    proc.Arguments = "/c ping -t " + tx1.Text + " ";

private void button27_Click(object sender, EventArgs e)
    System.Diagnostics.ProcessStartInfo proc = new System.Diagnostics.ProcessStartInfo();
    proc.FileName = @"C:\windows\system32\cmd.exe";
    proc.Arguments = "/c ping  " + tx2.Text + " ";

How to return a part of an array in Ruby?

I like ranges for this:

def first_half(list)
  list[0...(list.length / 2)]

def last_half(list)
  list[(list.length / 2)..list.length]

However, be very careful about whether the endpoint is included in your range. This becomes critical on an odd-length list where you need to choose where you're going to break the middle. Otherwise you'll end up double-counting the middle element.

The above example will consistently put the middle element in the last half.

Ifelse statement in R with multiple conditions

Based on suggestions from @jaimedash and @Old_Mortality I found a solution:

DF$Den <- ifelse(DF$Denial1 < 1 & !$Denial1) | DF$Denial2 < 1 &  
!$Denial2) | DF$Denial3 < 1 & !$Denial3), "0", "1")

Then to ensure a value of NA if all values of the conditional variables are NA:

DF$Den <- ifelse($Denial1) &$Denial2) &$Denial3), 
NA, DF$Den)

PHP - remove all non-numeric characters from a string

You can use preg_replace in this case;

$res = preg_replace("/[^0-9]/", "", "Every 6 Months" );

$res return 6 in this case.

If want also to include decimal separator or thousand separator check this example:

$res = preg_replace("/[^0-9.]/", "", "$ 123.099");

$res returns "123.099" in this case

Include period as decimal separator or thousand separator: "/[^0-9.]/"

Include coma as decimal separator or thousand separator: "/[^0-9,]/"

Include period and coma as decimal separator and thousand separator: "/[^0-9,.]/"

javascript check for not null

There are 3 ways to check for "not null". My recommendation is to use the Strict Not Version.

1. Strict Not Version

if (val !== null) { ... }

The Strict Not Version uses the "Strict Equality Comparison Algorithm" The !== has faster performance, than the != operator because the Strict Equality Comparison Algorithm doesn't typecast values.

2. Non-strict Not Version

if (val != 'null') { ... }

The Non-strict version uses the "Abstract Equality Comparison Algorithm" The != has slower performance, than the !== operator because the Abstract Equality Comparison Algorithm typecasts values.

3. Double Not Version

if (!!val) { ... }

The Double Not Version !! has faster performance, than both the Strict Not Version !== and the Non-Strict Not Version != ( However, it will typecast "Falsey" values like undefined and NaN into False ( which may lead to unexpected results, and it has worse readability because null isn't explicitly stated.

How to Call VBA Function from Excel Cells?

Here's the answer

Steps to follow:

  1. Open the Visual Basic Editor. In Excel, hit Alt+F11 if on Windows, Fn+Option+F11 if on a Mac.

  2. Insert a new module. From the menu: Insert -> Module (Don't skip this!).

  3. Create a Public function. Example:

    Public Function findArea(ByVal width as Double, _
                             ByVal height as Double) As Double
        ' Return the area
        findArea = width * height
    End Function
  4. Then use it in any cell like you would any other function: =findArea(B12,C12).

How to delete a file via PHP?

AIO solution, handles everything, It's not my work but I just improved myself. Enjoy!

 * Unlink a file, which handles symlinks.
 * @see
 * @param string $filename The file path to the file to delete.
 * @return boolean Whether the file has been removed or not.
function unlinkFile ( $filename ) {
    // try to force symlinks
    if ( is_link ($filename) ) {
        $sym = @readlink ($filename);
        if ( $sym ) {
            return is_writable ($filename) && @unlink ($filename);

    // try to use real path
    if ( realpath ($filename) && realpath ($filename) !== $filename ) {
        return is_writable ($filename) && @unlink (realpath ($filename));

    // default unlink
    return is_writable ($filename) && @unlink ($filename);

Group by multiple field names in java 8

Here look at the code:

You can simply create a Function and let it do the work for you, kind of functional Style!

Function<Person, List<Object>> compositeKey = personRecord ->
    Arrays.<Object>asList(personRecord.getName(), personRecord.getAge());

Now you can use it as a map:

Map<Object, List<Person>> map =
people.collect(Collectors.groupingBy(compositeKey, Collectors.toList()));


For div to extend full height

This might be of some help:

A relevant quote:

Most attempts to accomplish this were made by assigning the property and value: div{height:100%} - this alone will not work. The reason is that without a parent defined height, the div{height:100%;} has nothing to factor 100% percent of, and will default to a value of div{height:auto;} - auto is an "as needed value" which is governed by the actual content, so that the div{height:100%} will a=only extend as far as the content demands.

The solution to the problem is found by assigning a height value to the parent container, in this case, the body element. Writing your body stlye to include height 100% supplies the needed value.

html, body { 

Python sys.argv lists and indexes

sys.argv is the list of arguments passed to the Python program. The first argument, sys.argv[0], is actually the name of the program as it was invoked. That's not a Python thing, but how most operating systems work. The reason sys.argv[0] exists is so you can change your program's behaviour depending on how it was invoked. sys.argv[1] is thus the first argument you actually pass to the program.

Because lists (like most sequences) in Python start indexing at 0, and because indexing past the end of the list is an error, you need to check if the list has length 2 or longer before you can access sys.argv[1].

SCRIPT7002: XMLHttpRequest: Network Error 0x2ef3, Could not complete the operation due to error 00002ef3

I had this problem, a an AJAX Post request that returned some JSON would fail, eventually returning abort, with the:

SCRIPT7002: XMLHttpRequest: Network Error 0x2ef3

error in the console. On other browsers (Chrome, Firefox, Safari) the exact same AJAX request was fine.

Tracked my issue down - investigation revealed that the response was missing the status code. In this case it should have been 500 internal error. This was being generated as part of a C# web application using service stack that requires an error code to be explicitly set.

IE seemed to leave the connection open to the server, eventually it timed out and it 'aborted' the request; despite receiving the content and other headers.

Perhaps there is an issue with how IE is handling the headers in posts.

Updating the web application to correctly return the status code fixed the issue.

Hope this helps someone!

Replace all occurrences of a string in a data frame

If you are only looking to replace all occurrences of "< " (with space) with "<" (no space), then you can do an lapply over the data frame, with a gsub for replacement:

> data <- data.frame(lapply(data, function(x) {
+                  gsub("< ", "<", x)
+              }))
> data
  name var1 var2
1    a   <2   <3
2    a   <2   <3
3    a   <2   <3
4    b   <2   <3
5    b   <2   <3
6    b   <2   <3
7    c   <2   <3
8    c   <2   <3
9    c   <2   <3

Adding hours to JavaScript Date object?

Check if its not already defined, otherwise defines it on the Date prototype:

if (!Date.prototype.addHours) {
    Date.prototype.addHours = function(h) {
        this.setHours(this.getHours() + h);
        return this;

How to avoid "RuntimeError: dictionary changed size during iteration" error?

For situations like this, i like to make a deep copy and loop through that copy while modifying the original dict.

If the lookup field is within a list, you can enumerate in the for loop of the list and then specify the position as index to access the field in the original dict.

Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect)

First check your imports, when you use session, transaction it should be org.hibernate and remove @Transactinal annotation. and most important in Entity class if you have used @GeneratedValue(strategy=GenerationType.AUTO) or any other then at the time of model object creation/entity object creation should not create id. final conclusion is if you want pass id filed i.e PK then remove @GeneratedValue from entity class.

Difference between subprocess.Popen and os.system

os.system is equivalent to Unix system command, while subprocess was a helper module created to provide many of the facilities provided by the Popen commands with an easier and controllable interface. Those were designed similar to the Unix Popen command.

system() executes a command specified in command by calling /bin/sh -c command, and returns after the command has been completed


The popen() function opens a process by creating a pipe, forking, and invoking the shell.

If you are thinking which one to use, then use subprocess definitely because you have all the facilities for execution, plus additional control over the process.

MS Excel showing the formula in a cell instead of the resulting value

Try this if the above solution aren't working, worked for me

Cut the whole contents in the worksheet using "Ctrl + A" followed by "Ctrl + X" and paste it to a new sheet. Your reference to formulas will remain intact when you cut paste.

MVC Redirect to View from jQuery with parameters

redirect with query string

 $('#results').on('click', '.item', function () {
                    var NestId = $(this).data('id');
                   // var url = '@Url.Action("Details", "Artists",new { NestId = '+NestId+'  })'; 
                    var url = '@ Url.Content("~/Artists/Details?NestId =' + NestId + '")'
                    window.location.href = url; 

Java 8: Lambda-Streams, Filter by Method with Exception

Keeping this issue in mind I developed a small library for dealing with checked exceptions and lambdas. Custom adapters allow you to integrate with existing functional types:

stream().map(unchecked(URI::new)) //with a static import

CSS hide scroll bar, but have element scrollable

Hope this helps

/* Hide scrollbar for Chrome, Safari and Opera */
::-webkit-scrollbar {
  display: none;

/* Hide scrollbar for IE, Edge and Firefox */
html {
  -ms-overflow-style: none;  /* IE and Edge */
  scrollbar-width: none;  /* Firefox */

Add A Year To Today's Date

In Angular, This is how you Calculate Date

today = new Date();
year =;
month =;
day =;
//To go 18 years back
yearsBack18= new Date(this.year - 18, this.month,;

//To go to same day next year
nextYear= new Date(this.year + 1, this.month,;

What is meant by immutable?

"immutable" means you cannot change value. If you have an instance of String class, any method you call which seems to modify the value, will actually create another String.

String foo = "Hello";
<-- foo here still has the same value "Hello"

To preserve changes you should do something like this foo = foo.sustring(3);

Immutable vs mutable can be funny when you work with collections. Think about what will happen if you use mutable object as a key for map and then change the value (tip: think about equals and hashCode).

Print "\n" or newline characters as part of the output on terminal

Another suggestion is to do that way:

string = "abcd\n"

But be aware that the print function actually print to the terminal the "\n", your terminal interpret that as a newline, that's it. So, my solution just change the newline in \ + n

Removing App ID from Developer Connection

In the iOS Dev Center developer navigate to "Certificates, Identifiers & Profiles > iOS Apps > Identifiers > App IDs"

Find the app id you wish to delete, highlight it and select "Settings". At the bottom of the resulting screen there is a "Delete" button.

Previously the only way to do this was to use a Safari & Chrome extension written by Simon Whitaker

app-id-sanity downloads

It gives you an "Active" checkbox next to all your App IDs and allows you to relabel them to alter how they appear in the App ID drop-down when creating new provisioning profiles.

How do I restore a dump file from mysqldump?

How to Restore MySQL Database with MySQLWorkbench

You can run the drop and create commands in a query tab.

Drop the Schema if it Currently Exists

DROP DATABASE `your_db_name`;

Create a New Schema

CREATE SCHEMA `your_db_name`;

Open Your Dump File

MySQLWorkbench open sql file

  1. Click the Open an SQL script in a new query tab icon and choose your db dump file.
  2. Then Click Run SQL Script...
  3. It will then let you preview the first lines of the SQL dump script.
  4. You will then choose the Default Schema Name
  5. Next choose the Default Character Set utf8 is normally a safe bet, but you may be able to discern it from looking at the preview lines for something like character_set.
  6. Click Run
  7. Be patient for large DB restore scripts and watch as your drive space melts away!

How to connect from windows command prompt to mysql command line

first type cmd then the windows command prompt will appear:

mysql -u root -p


  • -u is the user id
  • -p is the password, if you will not using a password just leave it blank.

What's the difference between the atomic and nonatomic attributes?

There is no such keyword "atomic"

@property(atomic, retain) UITextField *userName;

We can use the above like

@property(retain) UITextField *userName;

See Stack Overflow question I am getting issues if I use @property(atomic,retain)NSString *myString.

Node.js: Difference between req.query[] and req.params

Given this route

app.get('/hi/:param1', function(req,res){} );

and given this URL

You will have:


  qs1: 'you',
  qs2: 'tube'


  param1: 'there'

Express req.params >>

Business logic in MVC

Why don't you introduce a service layer. then your controller will be lean and more readable, then your all controller functions will be pure actions. you can decompose business logic as you much as you need within service layer . code reusability is hight . no impact on models and repositories.

Getting the ID of the element that fired an event

In case of Angular 7.x you can get the native element and its id or properties.

myClickHandler($event) {
    this.selectedElement = <Element>$;


<div class="list-item" (click)="myClickHandler($event)">...</div>

How to loop in excel without VBA or macros?

Add more columns when you have variable loops that repeat at different rates. I'm not sure explicitly what you're trying to do, but I think I've done something that could apply.

Creating a single loop in Excel is prettty simple. It actually does the work for you. Try this on a new workbook

  1. Enter "1" in A1
  2. Enter "=A1+1" in A2

A3 will automatically be "=A2+1" as you drag down. The first steps don't have to be that explicit. Excel will automatically recognize the pattern and count if you just put "2" in A2, but if we want B1-B5 to be "100" and B5-B10 to be "200" (counting up the same way) you can see why knowing how to do it explicitly matters. In this scenario, You just enter:

  1. "100" in B1, drag through to B5 and
  2. "=B1+100" in B6

B7 will automatically be "=B2+100" etc. as you drag down, so basically it increases every 5 rows infinitely. To make a loop of numbers 1-5 in column A:

  1. Enter "=A1" in cell A6. As you drag down, it will automatically be "=A2" in cell A7, etc. because of the way that Excel does things.

So, now we have column A repeating numbers 1-5 while column B is increasing by 100 every 5 cells.You could make column B repeat, for instance, the numbers 100-900 in using the same method as you did with column A as a way to produce, for instance, each possible combination with multiple variables. Drag down the columns and they'll do it infinitely. I'm not explicitly addressing the scenario given, but if you follow the steps and understand them, the concept should give you an answer to the problem that involves adding more columns and concactinating or using them as your variables.

Android check internet connection

This is the another option to handle all situation:

public void isNetworkAvailable() {
    ConnectivityManager connectivityManager = (ConnectivityManager) ctx.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
    if (activeNetworkInfo != null && activeNetworkInfo.isConnected()) {
    } else {
        Toast.makeText(ctx, "Internet Connection Is Required", Toast.LENGTH_LONG).show();


What bitrate is used for each of the youtube video qualities (360p - 1080p), in regards to flowplayer?

Looking at this official google link: Youtube Live encoder settings, bitrates and resolutions they have this table:

                   240p       360p        480p        720p        1080p
Resolution      426 x 240   640 x 360   854x480     1280x720    1920x1080
Video Bitrates                   
Maximum         700 Kbps    1000 Kbps   2000 Kbps   4000 Kbps   6000 Kbps
Recommended     400 Kbps    750 Kbps    1000 Kbps   2500 Kbps   4500 Kbps
Minimum         300 Kbps    400 Kbps    500 Kbps    1500 Kbps   3000 Kbps

It would appear as though this is the case, although the numbers dont sync up to the google table above:

// the bitrates, video width and file names for this clip
      bitrates: [
        { url: "bbb-800.mp4", width: 480, bitrate: 800 }, //360p video
        { url: "bbb-1200.mp4", width: 720, bitrate: 1200 }, //480p video
        { url: "bbb-1600.mp4", width: 1080, bitrate: 1600 } //720p video

How do you launch the JavaScript debugger in Google Chrome?

To open the dedicated ‘Console’ panel, either:

  • Use the keyboard shortcuts
    • On Windows and Linux: Ctrl + Shift + J
    • On Mac: Cmd + Option + J
  • Select the Chrome Menu icon, menu -> More Tools -> JavaScript Console. Or if the Chrome Developer Tools are already open, press the ‘Console’ tab.

Please refer here

SQL WHERE.. IN clause multiple columns

Concatenating the columns together in some form is a "hack", but when the product doesn't support semi-joins for more than one column, sometimes you have no choice.

Example of where inner/outer join solution would not work:

select * from T1 
 where <boolean expression>
   and (<boolean expression> OR (ColA, ColB) in (select A, B ...))
   and <boolean expression>

When the queries aren't trivial in nature sometimes you don't have access to the base table set to perform regular inner/outer joins.

If you do use this "hack", when you combine fields just be sure to add enough of a delimiter in between them to avoid misinterpretations, e.g. ColA + ":-:" + ColB

Reading a file character by character in C

Here's one simple way to ignore everything but valid brainfuck characters:

#define BF_VALID "+-><[].,"

if (strchr(BF_VALID, c))
    code[n++] = c;

How does one add keyboard languages and switch between them in Linux Mint 16?

Mint 18.2 (Cinnamon)
Menu > Keyboard Preferences > Layouts > Options > Switching to another layout:

Menu > Keyboard Preferences > Layouts > Options > Switching to another layout

How to find if directory exists in Python

#You can also check it get help for you

if not os.path.isdir('mydir'):
    print('new directry has been created')
    os.system('mkdir mydir')

How to get POST data in WebAPI?

After spending a good bit of time today trying to wrap my brain around the (significant but powerful) paradigm shift between old ways of processing web form data and how it is done with WebAPI, I thought I'd add my 2 cents to this discussion.

What I wanted to do (which is pretty common for web form processing of a POST) is to be able to grab any of the form values I want, in any order. Say like you can do if you have your data in a System.Collections.Specialized.NameValueCollection. But turns out, in WebAPI, the data from a POST comes back at you as a stream. So you can't directly do that.

But there is a cool little class named FormDataCollection (in System.Net.Http.Formatting) and what it will let you do is iterate through your collection once.

So I wrote a simple utility method that will run through the FormDataCollection once and stick all the values into a NameValueCollection. Once this is done, you can jump all around the data to your hearts content.

So in my ApiController derived class, I have a post method like this:

    public void Post(FormDataCollection formData)
        NameValueCollection valueMap = WebAPIUtils.Convert(formData);

        ... my code that uses the data in the NameValueCollection

The Convert method in my static WebAPIUtils class looks like this:

    /// <summary>
    /// Copy the values contained in the given FormDataCollection into 
    /// a NameValueCollection instance.
    /// </summary>
    /// <param name="formDataCollection">The FormDataCollection instance. (required, but can be empty)</param>
    /// <returns>The NameValueCollection. Never returned null, but may be empty.</returns>
    public static NameValueCollection Convert(FormDataCollection formDataCollection)
        Validate.IsNotNull("formDataCollection", formDataCollection);

        IEnumerator<KeyValuePair<string, string>> pairs = formDataCollection.GetEnumerator();

        NameValueCollection collection = new NameValueCollection();

        while (pairs.MoveNext())
            KeyValuePair<string, string> pair = pairs.Current;

            collection.Add(pair.Key, pair.Value);

        return collection;

Hope this helps!

SVN "Already Locked Error"

I had the same problem: I can't commit a lot of files at once.

The commit works by:

  1. Running a "clean up" from Tortoise SVN

  2. Commit each file separate. Create new root folder and commit each file or folder.

** If the error returns you should repeat action no.1-2 **

Shortcuts in Objective-C to concatenate NSStrings

NSString *result=[NSString stringWithFormat:@"%@ %@", @"Hello", @"World"];

Script not served by static file handler on IIS7.5

There is a chance that application pool created for you application by default is version 2. So although you see a handler for .svc extension in the list it does not work and treat it as static file. All you need is to open application pool properties and switch it to version 4.

Does functional programming replace GoF design patterns?

I think only two GoF Design Patterns are designed to introduce the functional programming logic into natural OO language. I think about Strategy and Command. Some of the other GoF design patterns can be modified by functional programming to simplify the design and keep the purpose.

How to serialize an object to XML without getting xmlns="..."?

Ahh... nevermind. It's always the search after the question is posed that yields the answer. My object that is being serialized is obj and has already been defined. Adding an XMLSerializerNamespace with a single empty namespace to the collection does the trick.

In VB like this:

Dim xs As New XmlSerializer(GetType(cEmploymentDetail))
Dim ns As New XmlSerializerNamespaces()
ns.Add("", "")

Dim settings As New XmlWriterSettings()
settings.OmitXmlDeclaration = True

Using ms As New MemoryStream(), _
    sw As XmlWriter = XmlWriter.Create(ms, settings), _
    sr As New StreamReader(ms)
xs.Serialize(sw, obj, ns)
ms.Position = 0
End Using

in C# like this:

//Create our own namespaces for the output
XmlSerializerNamespaces ns = new XmlSerializerNamespaces();

//Add an empty namespace and empty value
ns.Add("", "");

//Create the serializer
XmlSerializer slz = new XmlSerializer(someType);

//Serialize the object with our own namespaces (notice the overload)
slz.Serialize(myXmlTextWriter, someObject, ns);

How do I script a "yes" response for installing programs?

If you want to just accept defaults you can use:

\n | ./shell_being_run

Using a dispatch_once singleton model in Swift

There is a better way to do it. You can declare a global variable in your class above the class declaration like this:

var tpScopeManagerSharedInstance = TPScopeManager()

This just calls your default init or whichever init and global variables are dispatch_once by default in Swift. Then in whichever class you want to get a reference, you just do this:

var refrence = tpScopeManagerSharedInstance
// or you can just access properties and call methods directly

So basically you can get rid of the entire block of shared instance code.

Import data into Google Colaboratory

  1. You can mount to google drive by running following

    from google.colab import drive drive.mount('/content/drive')

  2. Afterwards For training copy data from gdrive to colab root folder.

!cp -r '/content/drive/My Drive/Project_data' '/content'

where first path is gdrive path and second is colab root folder.

This way training is faster for large data.

Prevent any form of page refresh using jQuery/Javascript

Back in the ole days of CGI we had many forms that would trigger various backend actions. Such as text notifications to groups, print jobs, farming of data, etc.

If the user was on a page that was saying "Please wait... Performing some HUGE job that could take some time.". They were more likely to hit REFRESH and this would be BAD!

WHY? Because it would trigger more slow jobs and eventually bog down the whole thing.

The solution? Allow them to do their form. When they submit their form... Start your job and then direct them to another page that tells them to wait.

Where the page in the middle actually held the form data that was needed to start the job. The WAIT page however contains a javascript history destroy. So they can RELOAD that wait page all they want and it will never trigger the original job to start in the background as that WAIT page only contains the form data needed for the WAIT itself.

Hope that makes sense.

The history destroy function also prevented them from clicking BACK and then refreshing as well.

It was very seamless and worked great for MANY MANY years until the non-profit was wound down.

Example: FORM ENTRY - Collect all their info and when submitted, this triggers your backend job.

RESPONSE from form entry - Returns HTML that performs a redirect to your static wait page and/or POST/GET to another form (the WAIT page).

WAIT PAGE - Only contains FORM data related to wait page as well as javascript to destroy the most recent history. Like (-1 OR -2) to only destroy the most recent pages, but still allows them to go back to their original FORM entry page.

Once they are at your WAIT page, they can click REFRESH as much as they want and it will never spawn the original FORM job on the backend. Instead, your WAIT page should embrace a META timed refresh itself so it can always check on the status of their job. When their job is completed, they are redirected away from the wait page to whereever you wish.

If they do manually REFRESH... They are simply adding one more check of their job status in there.

Hope that helps. Good luck.

jQuery preventDefault() not triggered

If e.preventDefault(); is not working you must use e.stopImmediatePropagation(); instead.

For further informations take a look at : What's the difference between event.stopPropagation and event.preventDefault?

$("div.subtab_left li.notebook a").click(function(e) {
    return false;

Hive query output to file

This command will redirect the output to a text file of your choice:

$hive -e "select * from table where id > 10" > ~/sample_output.txt

How to get DateTime.Now() in YYYY-MM-DDThh:mm:ssTZD format using C#

use zzz instead of TZD





Scala check if element is present in a list

this should work also with different predicate

myFunction(strings.find( _ == mystring ).isDefined)

ToList()-- does it create a new list?

ToList will create a brand new list.

If the items in the list are value types, they will be directly updated, if they are reference types, any changes will be reflected back in the referenced objects.

What is the difference between atan and atan2 in C++?

Mehrwolf below is correct, but here is a heuristic which may help:

If you are working in a 2-dimensional coordinate system, which is often the case for programming the inverse tangent, you should use definitely use atan2. It will give the full 2 pi range of angles and take care of zeros in the x coordinate for you.

Another way of saying this is that atan(y/x) is virtually always wrong. Only use atan if the argument cannot be thought of as y/x.

How do I represent a time only value in .NET?

I think Rubens' class is a good idea so thought to make an immutable sample of his Time class with basic validation.

class Time
    public int Hours   { get; private set; }
    public int Minutes { get; private set; }
    public int Seconds { get; private set; }

    public Time(uint h, uint m, uint s)
        if(h > 23 || m > 59 || s > 59)
            throw new ArgumentException("Invalid time specified");
        Hours = (int)h; Minutes = (int)m; Seconds = (int)s;

    public Time(DateTime dt)
        Hours = dt.Hour;
        Minutes = dt.Minute;
        Seconds = dt.Second;

    public override string ToString()
        return String.Format(
            this.Hours, this.Minutes, this.Seconds);

Unable to set default python version to python3 in ubuntu

get python path from

ls /usr/bin/python*

then set your python version

alias python="/usr/bin/python3"

Python not working in the command line of git bash

I know this is an old post, but I just came across this problem on Windows 10 running Python 3.8.5 and Git

Somehow I had several different 2.7x versions of Python installed as well. I removed every version of Python (3x and 2x), downloaded the official installer here, installed 3.8.5 fresh (just used the defaults) which installed Python 3.8.5 at this location:

C:\Users\(my username)\AppData\Local\Programs\Python\Python38

Then to get the command python to work in my git bash shell, I had to manually add the path to Python38 to my path variable following the instructions listed here. This is important to note because on the python installer at the bottom of the first modal that comes up it asks if you want to add the python path to your PATH environment variable. I clicked the checkbox next to this but it didn't actually add the path, hence the need to manually add the path to my PATH environment variable.

Now using my gitbash shell I can browse to a directory with a python script in it and just type python and it runs no problem.

I wanted to post this because this is all I had to do to get my gitbash shell to allow me to run python scripts. I think there might have been some updates so I didn't need to do any of the other solutions listed here. At any rate, this is another thing to try if you are having issues running python scripts in your gitbash shell on a Windows 10 machine.


how to view the contents of a .pem certificate

Use the -printcert command like this:

keytool -printcert -file certificate.pem

jQuery, simple polling example

I created a tiny JQuery plugin for this. You may try it:

$.poll('http://my/url', 100, (xhr, status, data) => {
    return data.hello === 'world';

Is < faster than <=?

You should not be able to notice the difference even if there is any. Besides, in practice, you'll have to do an additional a + 1 or a - 1 to make the condition stand unless you're going to use some magic constants, which is a very bad practice by all means.

Bootstrap 3 with remote Modal

I did this:

$('#myModal').on '', (e) ->  

jQuery fade out then fade in

With async functions and promises, it now can work as simply as this:

async function foobar() {
  await $("#example").fadeOut().promise();
  await $("#example").fadeIn().promise();

Remove files from Git commit

Do a sequence of the following commands:

//to remove the last commit, but preserve changes  
git reset --soft HEAD~1

//to remove unneded file from the staging area  
git reset HEAD `<your file>` 

//finally make a new commit  
git commit -m 'Your message'

Create a batch file to copy and rename file

type C:\temp\test.bat>C:\temp\test.log

psql: FATAL: Ident authentication failed for user "postgres"

Edit the file /etc/postgresql/8.4/main/pg_hba.conf and replace ident or peer by either md5 or trust, depending on whether you want it to ask for a password on your own computer or not. Then reload the configuration file with:

/etc/init.d/postgresql reload

Retrieve list of tasks in a queue in Celery

The celery inspect module appears to only be aware of the tasks from the workers perspective. If you want to view the messages that are in the queue (yet to be pulled by the workers) I suggest to use pyrabbit, which can interface with the rabbitmq http api to retrieve all kinds of information from the queue.

An example can be found here: Retrieve queue length with Celery (RabbitMQ, Django)

Input and Output binary streams using JERSEY?

Another sample code where you can upload a file to the REST service, the REST service zips the file, and the client downloads the zip file from the server. This is a good example of using binary input and output streams using Jersey.

This answer was posted by me in another thread. Hope this helps.

Compare a date string to datetime in SQL Server?


CONVERT(VARCHAR(2),DATEPART("dd",Date)) +'/'+                                                              
             CONVERT(VARCHAR(2),DATEPART("mm",Date)) +'/'+              
                     CONVERT(VARCHAR(4), DATEPART("yy",Date)) = @Dat

How to drop unique in MySQL?

DROP INDEX column_name ON table_name

Select the database and query form the sql tab.This removes the index of the particular column. It worked for me in PHP MyADMIN

Serializing PHP object to JSON

json_encode() will only encode public member variables. so if you want to include the private once you have to do it by yourself (as the others suggested)

How to set adaptive learning rate for GradientDescentOptimizer?

From tensorflow official docs

global_step = tf.Variable(0, trainable=False)
starter_learning_rate = 0.1
learning_rate = tf.train.exponential_decay(starter_learning_rate, global_step,
                                       100000, 0.96, staircase=True)

# Passing global_step to minimize() will increment it at each step.
learning_step = (
.minimize( loss..., global_step=global_step))

SQL Query - how do filter by null or not null

Just like you said

select * from tbl where statusid is null


select * from tbl where statusid is not null

If your statusid is not null, then it will be selected just fine when you have an actual value, no need for any "if" logic if that is what you were thinking

select * from tbl where statusid = 123 -- the record(s) returned will not have null statusid

if you want to select where it is null or a value, try

select * from tbl where statusid = 123 or statusid is null

Action bar navigation modes are deprecated in Android L

I think a suitable replacement for when you have three to five screens of equal importance is the BottomNavigationActivity,this can be used to switch fragments.

You will notice a wizard exists for this in Android Studio, take care however as Android Studio has a tendency to produce overly complex boiler plate code.

A tutorial can be found here:

Another quality tutorial can be found at Android Hive here:

"Bitmap too large to be uploaded into a texture"

I used Picasso and had the same problem. image was too large at least in on size, width or height. finally I found the solution here. you can scale the large image down according to display size and also keep the aspect ratio:

    public Point getDisplaySize(Display display) {
    Point size = new Point();

    } else {
        int width = display.getWidth();
        int height = display.getHeight();
        size = new Point(width, height);

    return size;

and use this method for loading image by Picasso:

    final Point displySize = getDisplaySize(getWindowManager().getDefaultDisplay());
        final int size = (int) Math.ceil(Math.sqrt(displySize.x * displySize.y));
                .resize(size, size)

also for better performance you can download the image according to width and height of the display screen, not whole the image:

    public String reviseImageUrl(final Integer displayWidth,     final Integer displayHeight,
        final String originalImageUrl) {
    final String revisedImageUrl;

    if (displayWidth == null && displayHeight == null) {
        revisedImageUrl = originalImageUrl;
    } else {
        final Uri.Builder uriBuilder = Uri.parse(originalImageUrl).buildUpon();

        if (displayWidth != null && displayWidth > 0) {
            uriBuilder.appendQueryParameter(QUERY_KEY_DISPLAY_WIDTH, String.valueOf(displayWidth));

        if (displayHeight != null && displayHeight > 0) {
            uriBuilder.appendQueryParameter(QUERY_KEY_DISPLAY_HEIGHT, String.valueOf(displayHeight));

        revisedImageUrl = uriBuilder.toString();

    return revisedImageUrl;

    final String newImageUlr = reviseImageUrl(displySize.x, displySize.y, urlSource);

and then:

                .resize(size, size)

EDIT: getDisplaySize()

display.getWidth()/getHeight() is deprecated. Instead of Display use DisplayMetrics.

public Point getDisplaySize(DisplayMetrics displayMetrics) {
        int width = displayMetrics.widthPixels;
        int height = displayMetrics.heightPixels;
        return new Point(width, height);

How do you update Xcode on OSX to the latest version?

  1. Open up App Store

    enter image description here

  2. Look in the top right for the updates section (may also be in lefthand column "Updates"..)

    enter image description here

  3. Find Xcode & click Update enter image description here

Delete specific line from a text file?

No rocket scien code require .Hope this simple and short code will help.

List linesList = File.ReadAllLines("myFile.txt").ToList();            
File.WriteAllLines("myFile.txt"), linesList.ToArray());

OR use this

public void DeleteLinesFromFile(string strLineToDelete)
        string strFilePath = "Provide the path of the text file";
        string strSearchText = strLineToDelete;
        string strOldText;
        string n = "";
        StreamReader sr = File.OpenText(strFilePath);
        while ((strOldText = sr.ReadLine()) != null)
            if (!strOldText.Contains(strSearchText))
                n += strOldText + Environment.NewLine;
        File.WriteAllText(strFilePath, n);

How to uninstall Jenkins?

On Mac; these two below commands completely remove Jenkins from your machine. just open your Terminal and execute them:

  1. '/Library/Application Support/Jenkins/Uninstall.command' and
  2. sudo rm -rf /var/root/.jenkins ~/.jenkins


Fixed height and width for bootstrap carousel

Apply following style to carousel listbox.

<div class="carousel-inner" role="listbox" style=" width:100%; height: 500px !important;">_x000D_

MySQL ON DUPLICATE KEY UPDATE for multiple rows insert in single query

INSERT INTO ... ON DUPLICATE KEY UPDATE will only work for MYSQL, not for SQL Server.

for SQL server, the way to work around this is to first declare a temp table, insert value to that temp table, and then use MERGE

Like this:

declare @Source table
name varchar(30),
age decimal(23,0)

insert into @Source VALUES
('Helen', 24),
('Katrina', 21),
('Samia', 22),
('Hui Ling', 25),
('Yumie', 29);

MERGE beautiful  AS Tg
using  @source as Sc

when matched then update 
set tg.age=sc.age

when not matched then 
insert (name, age) VALUES
(, sc.age);

1114 (HY000): The table is full

Unless you enabled innodb_file_per_table option, InnoDB keeps all data in one file, usually called ibdata1.

Check the size of that file and check you have enough disk space in the drive it resides on.

Two-way SSL clarification

In two way ssl the client asks for servers digital certificate and server ask for the same from the client. It is more secured as it is both ways, although its bit slow. Generally we dont follow it as the server doesnt care about the identity of the client, but a client needs to make sure about the integrity of server it is connecting to.

Can local storage ever be considered secure?


localStorage is accessible by any webpage, and if you have the key, you can change whatever data you want.

That being said, if you can devise a way to safely encrypt the keys, it doesn't matter how you transfer the data, if you can contain the data within a closure, then the data is (somewhat) safe.

How can I change the color of a Google Maps marker?

The simplest way I found is to use BitmapDescriptorFactory.defaultMarker() the documentation even has an example of setting the color. From my own code:

MarkerOptions marker = new MarkerOptions()
            .position(new LatLng(data.getLatitude(), data.getLongitude()))