Programs & Examples On #Design time

In opposition to the run-time of a software, its design-time represents the time where it's being created.

Any easy way to use icons from resources?

in visual studio for, go to the project properties, click Add Resource > Existing File, select your Icon.

in your code: Me.Icon = My.Resources.IconResourceName

User Control - Custom Properties

Just add public properties to the user control.

You can add [Category("MyCategory")] and [Description("A property that controls the wossname")] attributes to make it nicer, but as long as it's a public property it should show up in the property panel.

Best way to access a control on another form in Windows Forms?

After reading the additional details, I agree with robcthegeek: raise an event. Create a custom EventArgs and pass the neccessary parameters through it.

Detecting when a div's height changes using jQuery

In response to user007:

If the height of your element is changing due to items being appended to it using .append() you shouldn't need to detect the change in height. Simply add the reposition of your second element in the same function where you are appending the new content to your first element.

As in:

Working Example

$('.class1').click(function () {
    $('.class1').append("<div class='newClass'><h1>This is some content</h1></div>");
    $('.class2').css('top', $('.class1').offset().top + $('.class1').outerHeight());

How to remove all characters after a specific character in python?

The method find will return the character position in a string. Then, if you want remove every thing from the character, do this:

mystring = "123?567"
mystring[ 0 : mystring.index("?")]

>> '123'

If you want to keep the character, add 1 to the character position.

find_spec_for_exe': can't find gem bundler (>= 0.a) (Gem::GemNotFoundException)

Adding to the many answers, my problem stemmed from wanting to use the docker's ruby as a base, but then using rbenv on top. This screws up a lot of things.

I fixed it in this case by:

  • The Gemfile.lock version did need updating - changing the "BUNDLED WITH" to the latest version did at one point change the error message, so may have been required
  • in .bash_profile or .bashrc, unsetting the environment variables:
unset GEM_HOME

After that, rbenv worked fine. Not sure how those env vars were getting loaded in the first place...

Where and why do I have to put the "template" and "typename" keywords?

I am placing JLBorges's excellent response to a similar question verbatim from, as it is the most succinct explanation I've read on the subject.

In a template that we write, there are two kinds of names that could be used - dependant names and non- dependant names. A dependant name is a name that depends on a template parameter; a non-dependant name has the same meaning irrespective of what the template parameters are.

For example:

template< typename T > void foo( T& x, std::string str, int count )
    // these names are looked up during the second phase
    // when foo is instantiated and the type T is known
    x.size(); // dependant name (non-type)
    T::instance_count ; // dependant name (non-type)
    typename T::iterator i ; // dependant name (type)
    // during the first phase, 
    // T::instance_count is treated as a non-type (this is the default)
    // the typename keyword specifies that T::iterator is to be treated as a type.

    // these names are looked up during the first phase
    std::string::size_type s ; // non-dependant name (type)
    std::string::npos ; // non-dependant name (non-type)
    str.empty() ; // non-dependant name (non-type)
    count ; // non-dependant name (non-type)

What a dependant name refers to could be something different for each different instantiation of the template. As a consequence, C++ templates are subject to "two-phase name lookup". When a template is initially parsed (before any instantiation takes place) the compiler looks up the non-dependent names. When a particular instantiation of the template takes place, the template parameters are known by then, and the compiler looks up dependent names.

During the first phase, the parser needs to know if a dependant name is the name of a type or the name of a non-type. By default, a dependant name is assumed to be the name of a non-type. The typename keyword before a dependant name specifies that it is the name of a type.


Use the keyword typename only in template declarations and definitions provided you have a qualified name that refers to a type and depends on a template parameter.

How to use the read command in Bash?

The read in your script command is fine. However, you execute it in the pipeline, which means it is in a subshell, therefore, the variables it reads to are not visible in the parent shell. You can either

  • move the rest of the script in the subshell, too:

    echo hello | { read str
      echo $str
  • or use command substitution to get the value of the variable out of the subshell

    str=$(echo hello)
    echo $str

    or a slightly more complicated example (Grabbing the 2nd element of ls)

    str=$(ls | { read a; read a; echo $a; })
    echo $str

How to change colors of a Drawable in Android?

It works for some simple drawables. I used it on a simple solid color rect shape with rounded corners and needed to change that color with different layouts.

Try this


Show a PDF files in users browser via PHP/Perl

I assume you want the PDF to display in the browser, rather than forcing a download. If that is the case, try setting the Content-Disposition header with a value of inline.

Also remember that this will also be affected by browser settings - some browsers may be configured to always download PDF files or open them in a different application (e.g. Adobe Reader)

Postgres: How to convert a json string to text?

->> works for me.

postgres version:



select object_details->'valuationDate' as asofJson, object_details->>'valuationDate' as asofText from MyJsonbTable;


  asofJson       asofText
"2020-06-26"    2020-06-26
"2020-06-25"    2020-06-25
"2020-06-25"    2020-06-25
"2020-06-25"    2020-06-25

How can I get System variable value in Java?

Use the System.getenv(String) method, passing the name of the variable to read.

How can I use the MS JDBC driver with MS SQL Server 2008 Express?

Named instances?

URL: jdbc:sqlserver://[serverName][\instanceName][:portNumber][;property=value]

Note: backward slash

How to Use UTF-8 Collation in SQL Server database?

Note that as of Microsoft SQL Server 2016, UTF-8 is supported by bcp, BULK_INSERT, and OPENROWSET.

Addendum 2016-12-21: SQL Server 2016 SP1 now enables Unicode Compression (and most other previously Enterprise-only features) for all versions of MS SQL including Standard and Express. This is not the same as UTF-8 support, but it yields a similar benefit if the goal is disk space reduction for Western alphabets.

How to create an instance of System.IO.Stream stream

System.IO.Stream stream = new System.IO.MemoryStream();

Make Font Awesome icons in a circle?

Update: Rather use flex.

If you want precision this is the way to go.

Fiddle. Go Play ->

Here is the HTML

<div class="sosial-links">
    <a href="#"><i class="fa fa-facebook fa-lg"></i></a>
    <a href="#"><i class="fa fa-twitter fa-lg"></i></a>
    <a href="#"><i class="fa fa-google-plus fa-lg"></i></a>
    <a href="#"><i class="fa fa-pinterest fa-lg"></i></a>

Here is the CSS

.sosial-links a{
    display: block;
    float: left;
    width: 36px;
    height: 36px;
    border: 2px solid #909090;
    border-radius: 20px;
    margin-right: 7px; /*space between*/

.sosial-links a i{
    padding: 12px 11px;
    font-size: 20px;
    color: #909090;

Have Fun

Named placeholders in string formatting

I tried in just a quick way

public static void main(String[] args) 
    String rowString = "replace the value ${var1} with ${var2}";
    Map<String,String> mappedValues = new HashMap<>();
    mappedValues.put("var1", "Value 1");
    mappedValues.put("var2", "Value 2");
    System.out.println(replaceOccurence(rowString, mappedValues));

private static  String replaceOccurence(String baseStr ,Map<String,String> mappedValues)
    for(String key :mappedValues.keySet())
        baseStr = baseStr.replace("${"+key+"}", mappedValues.get(key));
    return baseStr;

The type or namespace cannot be found (are you missing a using directive or an assembly reference?)

You don't have the namespace the Login class is in as a reference.

Add the following to the form that uses the Login class:

using FootballLeagueSystem;

When you want to use a class in another namespace, you have to tell the compiler where to find it. In this case, Login is inside the FootballLeagueSystem namespace, or : FootballLeagueSystem.Login is the fully qualified namespace.

As a commenter pointed out, you declare the Login class inside the FootballLeagueSystem namespace, but you're using it in the FootballLeague namespace.

ffmpeg usage to encode a video to H264 codec format

I have a Centos 5 system that I wasn't able to get this working on. So I built a new Fedora 17 system (actually a VM in VMware), and followed the steps at the ffmpeg site to build the latest and greatest ffmpeg.

I took some shortcuts - I skipped all the yum erase commands, added freshrpms according to their instructions:

rpm -ivh rpmfusion-free-release-stable.noarch.rpm

Then I loaded the stuff that was already readily available:

yum install lame libogg libtheora libvorbis lame-devel libtheora-devel

Afterwards, I only built the following from scratch: libvpx vo-aacenc-0.1.2 x264 yasm-1.2.0 ffmpeg

Then this command encoded with no problems (the audio was already in AAC, so I didn't recode it):

ffmpeg -i -c:v libx264 -preset slow -crf 22 -c:a copy output.mp4

The result looks just as good as the original to me, and is about 1/4 of the size!

Passing 'this' to an onclick event

You can always call funciton differently:; in this way you will be able to use this context inside the function.


<button onclick="" id="bar">Button</button>?

var foo = function()
    this.innerHTML = "Not a button";

Job for httpd.service failed because the control process exited with error code. See "systemctl status httpd.service" and "journalctl -xe" for details

Some other service may be using port 80: try to stop the other services: HTTPD, SSL, NGINX, PHP, with the command sudo systemctl stop and then use the command sudo systemctl start httpd

Setting a Sheet and cell as variable

Yes, set the cell as a RANGE object one time and then use that RANGE object in your code:

Sub RangeExample()
Dim MyRNG As Range

Set MyRNG = Sheets("Sheet1").Cells(23, 4)

Debug.Print MyRNG.Value

End Sub

Alternately you can simply store the value of that cell in memory and reference the actual value, if that's all you really need. That variable can be Long or Double or Single if numeric, or String:

Sub ValueExample()
Dim MyVal As String

MyVal = Sheets("Sheet1").Cells(23, 4).Value

Debug.Print MyVal

End Sub

Arrays vs Vectors: Introductory Similarities and Differences

Those reference pretty much answered your question. Simply put, vectors' lengths are dynamic while arrays have a fixed size. when using an array, you specify its size upon declaration:

int myArray[100];

for vectors, you just declare it and add elements

vector<int> myVector;

at times you wont know the number of elements needed so a vector would be ideal for such a situation.

Python module for converting PDF to text

I needed to convert a specific PDF to plain text within a python module. I used PDFMiner 20110515, after reading through their tool I wrote this simple snippet:

from cStringIO import StringIO
from pdfminer.pdfinterp import PDFResourceManager, process_pdf
from pdfminer.converter import TextConverter
from pdfminer.layout import LAParams

def to_txt(pdf_path):
    input_ = file(pdf_path, 'rb')
    output = StringIO()

    manager = PDFResourceManager()
    converter = TextConverter(manager, output, laparams=LAParams())
    process_pdf(manager, converter, input_)

    return output.getvalue() 

How to add hours to current date in SQL Server?

SELECT GETDATE() + (hours / 24.00000000000000000)

Adding to GETDATE() defaults to additional days, but it will also convert down to hours/seconds/milliseconds using decimal.

How to get number of rows using SqlDataReader in C#

Per above, a dataset or typed dataset might be a good temorary structure which you could use to do your filtering. A SqlDataReader is meant to read the data very quickly. While you are in the while() loop you are still connected to the DB and it is waiting for you to do whatever you are doing in order to read/process the next result before it moves on. In this case you might get better performance if you pull in all of the data, close the connection to the DB and process the results "offline".

People seem to hate datasets, so the above could be done wiht a collection of strongly typed objects as well.

HTML table with fixed headers and a fixed column?

I know you can do it for MSIE and this limited example seems to work for firefox (not sure how extensible the technique is).

standard size for html newsletter template


I would recommend that you read this link

You will see that Newsletters can have different widths, There seems to be no major standard, What is recommended is that the width will be about 95% of the page width, as different browsers use the extra margins differently. You will also find that email readers have problems when reading css so applying the guide lines in this tutorial might help you save some time and trouble-shooting down the road.

Be happy, Julian

Python name 'os' is not defined

The problem is that you forgot to import os. Add this line of code:

import os

And everything should be fine. Hope this helps!

How to Parse JSON Array with Gson

in Kotlin :

val jsonArrayString = "['A','B','C']"

val gson = Gson()

val listType: Type = object : TypeToken<List<String?>?>() {}.getType()

val stringList : List<String> = gson.fromJson(

Delimiter must not be alphanumeric or backslash and preg_match

You must specify a delimiter for your expression. A delimiter is a special character used at the start and end of your expression to denote which part is the expression. This allows you to use modifiers and the interpreter to know which is an expression and which are modifiers. As the error message states, the delimiter cannot be a backslash because the backslash is the escape character.

$pattern = "/My name is '(.*)' and im fine/";

and below the same example but with the i modifier to match without being case sensitive.

$pattern = "/My name is '(.*)' and im fine/i";

As you can see, the i is outside of the slashes and therefore is interpreted as a modifier.

Also bear in mind that if you use a forward slash character (/) as a delimiter you must then escape further uses of / in the regular expression, if present.

Get int value from enum in C#

In Visual Basic, it should be:

Public Enum Question
    Role = 2
    ProjectFunding = 3
    TotalEmployee = 4
    NumberOfServers = 5
    TopBusinessConcern = 6
End Enum

Private value As Integer = CInt(Question.Role)

How to delete node from XML file using C#

You can use Linq to XML to do this:

XDocument doc = XDocument.Load("input.xml");
var q = from node in doc.Descendants("Setting")
        let attr = node.Attribute("name")
        where attr != null && attr.Value == "File1"
        select node;
q.ToList().ForEach(x => x.Remove());

Is there an easy way to check the .NET Framework version?

Try this one:

string GetFrameWorkVersion()
        return System.Runtime.InteropServices.RuntimeEnvironment.GetSystemVersion();

How to convert a DataFrame back to normal RDD in pyspark?

Answer given by kennyut/Kistian works very well but to get exact RDD like output when RDD consist of list of attributes e.g. [1,2,3,4] we can use flatmap command as below,

rdd = df.rdd.flatMap(list)
rdd = df.rdd.flatmap(lambda x: list(x))

Postgres: clear entire database before re-creating / re-populating from bash script

To dump:

pg_dump -Fc mydb > db.dump

To restore:

pg_restore --verbose --clean --no-acl --no-owner -h localhost -U myuser -d my_db db/latest.dump

VueJs get url query

Current route properties are present in this.$route, this.$router is the instance of router object which gives the configuration of the router. You can get the current route query using this.$route.query

cout is not a member of std

Also remember that it must be:

#include "stdafx.h"
#include <iostream>

and not the other way around

#include <iostream>
#include "stdafx.h"

Best practice for instantiating a new Android Fragment

The only benefit in using the newInstance() that I see are the following:

  1. You will have a single place where all the arguments used by the fragment could be bundled up and you don't have to write the code below everytime you instantiate a fragment.

    Bundle args = new Bundle();
    args.putInt("someInt", someInt);
    args.putString("someString", someString);
    // Put any other arguments
  2. Its a good way to tell other classes what arguments it expects to work faithfully(though you should be able to handle cases if no arguments are bundled in the fragment instance).

So, my take is that using a static newInstance() to instantiate a fragment is a good practice.

The term 'Get-ADUser' is not recognized as the name of a cmdlet

If you don't see the Active Directory, it's because you did not install AD LS Users and Computer Feature. Go to Manage - Add Roles & Features. Within Add Roles and Features Wizard, on Features tab, select Remote Server Administration Tools, select - Role Admininistration Tools - Select AD DS and DF LDS Tools.

After that, you can see the PS Active Directory package.

filter: progid:DXImageTransform.Microsoft.gradient is not working in ie7

This should work:

background: -moz-linear-gradient(center top , #fad59f, #fa9907) repeat scroll 0 0 transparent;
 /* For WebKit (Safari, Google Chrome etc) */
background: -webkit-gradient(linear, left top, left bottom, from(#fad59f), to(#fa9907));
/* For Mozilla/Gecko (Firefox etc) */
background: -moz-linear-gradient(top, #fad59f, #fa9907);
/* For Internet Explorer 5.5 - 7 */
filter: progid:DXImageTransform.Microsoft.gradient(startColorstr=#fad59f, endColorstr=#fa9907);
/* For Internet Explorer 8 */
-ms-filter: "progid:DXImageTransform.Microsoft.gradient(startColorstr=#fad59f, endColorstr=#fa9907)";

Otherwise generate using the following link and get the code.

Is it possible to see more than 65536 rows in Excel 2007?

Here is an interesting blog entry about numbers / limitations of Excel 2007. According to the author the new limit is approximately one million rows.

Sounds like you have a pre-Excel 2007 workbook open in Excel 2007 in compatibility mode (look in the title bar and see if it says compatibility mode). If so, the workbook has 65,536 rows, not 1,048,576. You can save the workbook as an Excel workbook which will be in Excel 2007 format, close the workbook and re-open it.

How to implement authenticated routes in React Router 4?

The accepted answer is good, but it does NOT solve the problem when we need our component to reflect changes in URL.

Say, your component's code is something like:

export const Customer = (props) => {

   const history = useHistory();


And you change URL:

const handleGoToPrev = () => {

The component will not reload!

A better solution:

import React from 'react';
import { Redirect, Route } from 'react-router-dom';
import store from '../store/store';

export const PrivateRoute = ({ component: Component, }) => {

  let isLoggedIn = !!store.getState().data.user;

  return (
    <Route {} render={props => isLoggedIn
      ? (
        <Component key={ || 'empty'} {...props} />
      ) : (
        <Redirect to={{ pathname: '/login', state: { from: props.location } }} />
    } />


<PrivateRoute exact path="/app/customer/:id" component={Customer} />

How to align a div inside td element using CSS class

div { margin: auto; }

This will center your div.

Div by itself is a blockelement. Therefor you need to define the style to the div how to behave.

Android - Adding at least one Activity with an ACTION-VIEW intent-filter after Updating SDK version 23

Adding this intent filter to one of the activities declared in app manifest fixed this for me.



       <action android:name="android.intent.action.VIEW" />



Limit the size of a file upload (html input element)

var uploadField = document.getElementById("file");

uploadField.onchange = function() {
    if(this.files[0].size > 2097152){
       alert("File is too big!");
       this.value = "";

This example should work fine. I set it up for roughly 2MB, 1MB in Bytes is 1,048,576 so you can multiply it by the limit you need.

Here is the jsfiddle example for more clearence:

How do I dynamically assign properties to an object in TypeScript?

Try this:

export interface QueryParams {
    page?: number,
    limit?: number,
    name?: string,
    sort?: string,
    direction?: string

Then use it

const query = {
    name: 'abc'
} = 1

Parsing JSON from URL

public static TargetClassJson downloadPaletteJson(String url) throws IOException {
        if (StringUtils.isBlank(url)) {
            return null;
        String genreJson = IOUtils.toString(new URL(url).openStream());
        return new Gson().fromJson(genreJson, TargetClassJson.class);

What's the best way to send a signal to all members of a process group?

In sh the jobs command will list the background processes. In some cases it might be better to kill the newest process first, e.g. the older one created a shared socket. In those cases sort the PIDs in reverse order. Sometimes you want to wait moment for the jobs to write something on disk or stuff like that before they stop.

And don't kill if you don't have to!

  for CHILD in $(jobs -s|sort -r); do
    kill -s $SIGNAL $CHILD
    sleep $MOMENT

Firebase onMessageReceived not called when app in background

There are 2 types of Firebase push-notifications:

1- Notification message(Display message) -> -- 1.1 If you choose this variant, the OS will create it self a notification if app is in Background and will pass the data in the intent. Then it's up to the client to handle this data.

-- 1.2 If the app is in Foreground then the notification it will be received via callback-function in the FirebaseMessagingService and it's up to the client to handle it.

2- Data messages(up to 4k data) -> These messages are used to send only data to the client(silently) and it's up to the client to handle it for both cases background/foreground via callback-function in FirebaseMessagingService

This is according official docs:

How to select rows for a specific date, ignoring time in SQL Server

Try this:

select cast(salesDate as date) [date] from sales where salesDate = '2010/11/11'
select cast(salesDate as date) [date] from sales where salesDate = '11/11/2010'

Should switch statements always contain a default clause?

If the switch value (switch(variable)) can't reach the default case, then default case is not at all needed. Even if we keep the default case, it is not at all executed. It is dead code.

How do I install pip on macOS or OS X?

The simplest solution is to follow the installation instruction from pip's home site.

Basically, this consists in:

  • downloading Be sure to do this by following a trusted link since you will have to run the script as root.
  • call sudo python

The main advantage of that solution is that it install pip for the python version that has been used to run, which means that if you use the default OS X installation of python to run you will install pip for the python install from the system.

Most solutions that use a package manager (homebrew or macport) on OS X create a redundant installation of python in the environment of the package manager which can create inconsistencies in your system since, depending on what you are doing, you may call one installation of python instead of another.

Import Excel Spreadsheet Data to an EXISTING sql table?

If you would like a software tool to do this, you might like to check out this step-by-step guide:

"How to Validate and Import Excel spreadsheet to SQL Server database" /storage/emulated/0/New file.txt: open failed: EACCES (Permission denied)

Implement runtime permission for running your app on Android 6.0 Marshmallow (API 23) or later.

or you can manually enable the storage permission-

goto settings>apps> "your_app_name" >click on it >then click permissions> then enable the storage. Thats it.

But i suggest go the for first one which is, Implement runtime permissions in your code.

How to avoid variable substitution in Oracle SQL Developer with 'trinidad & tobago'

Call this before the query:

set define off;

Alternatively, hacky:

update t set country = 'Trinidad and Tobago' where country = 'trinidad &' || ' tobago';

From Tuning SQL*Plus:

SET DEFINE OFF disables the parsing of commands to replace substitution variables with their values.

How does DateTime.Now.Ticks exactly work?

Not really an answer to your question as asked, but thought I'd chip in about your general objective.

There already is a method to generate random file names in .NET.

See System.Path.GetTempFileName and GetRandomFileName.

Alternatively, it is a common practice to use a GUID to name random files.

Control the dashed border stroke length and distance between strokes

The native dashed border property value does not offer control over the dashes themselves... so bring on the border-image property!

Brew your own border with border-image

Compatibility: It offers great browser support (IE 11 and all modern browsers). A normal border can be set as a fallback for older browsers.

Let's create these

These borders will display exactly the same cross-browser!

Goal example Goal example with wider gaps

Step 1 - Create a suitable image

This example is 15 pixels wide by 15 pixels high and the gaps are currently 5px wide. It is a .png with transparency.

This is what it looks like in photoshop when zoomed in:

Example Border Image Background Blown Up

This is what it looks like to scale:

Example Border Image Background Actual Size

Controlling gap and stroke length

To create wider / shorter gaps or strokes, widen / shorten the gaps or strokes in the image.

Here is an image with wider 10px gaps:

Larger gaps correctly scaled = Larger gaps to scale

Step 2 - Create the CSS — this example requires 4 basic steps

  1. Define the border-image-source:

  2. Optional - Define the border-image-width:

    border-image-width: 1;

    The default value is 1. It can also be set with a pixel value, percentage value, or as another multiple (1x, 2x, 3x etc). This overrides any border-width set.

  3. Define the border-image-slice:

    In this example, the thickness of the images top, right, bottom and left borders is 2px, and there is no gap outside of them, so our slice value is 2:

    border-image-slice: 2; 

    The slices look like this, 2 pixels from the top, right, bottom and left:

    Slices example

  4. Define the border-image-repeat:

    In this example, we want the pattern to repeat itself evenly around our div. So we choose:

    border-image-repeat: round;

Writing shorthand

The properties above can be set individually, or in shorthand using border-image:

border-image: url("") 2 round;

Complete example

Note the border: dashed 4px #000 fallback. Non-supporting browsers will receive this border.

.bordered {_x000D_
  display: inline-block;_x000D_
  padding: 20px;_x000D_
  /* Fallback dashed border_x000D_
     - the 4px width here is overwritten with the border-image-width (if set)_x000D_
     - the border-image-width can be omitted below if it is the same as the 4px here_x000D_
  border: dashed 4px #000;_x000D_
  /* Individual border image properties */_x000D_
  border-image-source: url("");_x000D_
  border-image-slice: 2;_x000D_
  border-image-repeat: round;  _x000D_
  /* or use the shorthand border-image */_x000D_
  border-image: url("") 2 round;_x000D_
/*The border image of this one creates wider gaps*/_x000D_
.largeGaps {_x000D_
  border-image-source: url("");_x000D_
  margin: 0 20px;_x000D_
<div class="bordered">This is bordered!</div>_x000D_
<div class="bordered largeGaps">This is bordered and has larger gaps!</div>

What is inf and nan?

inf is infinity - a value that is greater than any other value. -inf is therefore smaller than any other value.

nan stands for Not A Number, and this is not equal to 0.

Although positive and negative infinity can be said to be symmetric about 0, the same can be said for any value n, meaning that the result of adding the two yields nan. This idea is discussed in this question.

Because nan is (literally) not a number, you can't do arithmetic with it, so the result of the second operation is also not a number (nan)

tar: file changed as we read it

If you want help debugging a problem like this you need to provide the make rule or at least the tar command you invoked. How can we see what's wrong with the command if there's no command to see?

However, 99% of the time an error like this means that you're creating the tar file inside a directory that you're trying to put into the tar file. So, when tar tries to read the directory it finds the tar file as a member of the directory, starts to read it and write it out to the tar file, and so between the time it starts to read the tar file and when it finishes reading the tar file, the tar file has changed.

So for example something like:

tar cf ./foo.tar .

There's no way to "stop" this, because it's not wrong. Just put your tar file somewhere else when you create it, or find another way (using --exclude or whatever) to omit the tar file.

What are the differences between "=" and "<-" assignment operators in R?

x = y = 5 is equivalent to x = (y = 5), because the assignment operators "group" right to left, which works. Meaning: assign 5 to y, leaving the number 5; and then assign that 5 to x.

This is not the same as (x = y) = 5, which doesn't work! Meaning: assign the value of y to x, leaving the value of y; and then assign 5 to, umm..., what exactly?

When you mix the different kinds of assignment operators, <- binds tighter than =. So x = y <- 5 is interpreted as x = (y <- 5), which is the case that makes sense.

Unfortunately, x <- y = 5 is interpreted as (x <- y) = 5, which is the case that doesn't work!

See ?Syntax and ?assignOps for the precedence (binding) and grouping rules.

How is the java memory pool divided?

The new keyword allocates memory on the Java heap. The heap is the main pool of memory, accessible to the whole of the application. If there is not enough memory available to allocate for that object, the JVM attempts to reclaim some memory from the heap with a garbage collection. If it still cannot obtain enough memory, an OutOfMemoryError is thrown, and the JVM exits.

The heap is split into several different sections, called generations. As objects survive more garbage collections, they are promoted into different generations. The older generations are not garbage collected as often. Because these objects have already proven to be longer lived, they are less likely to be garbage collected.

When objects are first constructed, they are allocated in the Eden Space. If they survive a garbage collection, they are promoted to Survivor Space, and should they live long enough there, they are allocated to the Tenured Generation. This generation is garbage collected much less frequently.

There is also a fourth generation, called the Permanent Generation, or PermGen. The objects that reside here are not eligible to be garbage collected, and usually contain an immutable state necessary for the JVM to run, such as class definitions and the String constant pool. Note that the PermGen space is planned to be removed from Java 8, and will be replaced with a new space called Metaspace, which will be held in native memory. reference:

Diagram of Java memory for several threads Diagram of Java memory distribution

How to detect orientation change?

For Swift 3

override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
    if UIDevice.current.orientation.isLandscape {
    else if UIDevice.current.orientation.isFlat {
    else {

module.exports vs. export default in Node.js and ES6

You need to configure babel correctly in your project to use export default and export const foo

npm install --save-dev @babel/plugin-proposal-export-default-from

then add below configration in .babelrc

"plugins": [ 

What is the best way to find the users home directory in Java?

Others have answered the question before me but a useful program to print out all available properties is:

for (Map.Entry<?,?> e : System.getProperties().entrySet()) {
    System.out.println(String.format("%s = %s", e.getKey(), e.getValue())); 

How to change the blue highlight color of a UITableViewCell?

You can change the highlight color in several ways.

  1. Change the selectionStyle property of your cell. If you change it to UITableViewCellSelectionStyleGray, it will be gray.

  2. Change the selectedBackgroundView property. Actually what creates the blue gradient is a view. You can create a view and draw what ever you like, and use the view as the background of your table view cells.

PHP AES encrypt / decrypt

Few important things to note with AES encryption:

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

Error: 10 $digest() iterations reached. Aborting! with dynamic sortby predicate

This happened to me right after upgrading Firefox to version 51. After clearing the cache, the problem has gone.

Shell command to sum integers, one per line?

sed 's/^/.+/' infile | bc | tail -1

Error in plot.window(...) : need finite 'xlim' values

The problem is that you're (probably) trying to plot a vector that consists exclusively of missing (NA) values. Here's an example:

> x=rep(NA,100)
> y=rnorm(100)
> plot(x,y)
Error in plot.window(...) : need finite 'xlim' values
In addition: Warning messages:
1: In min(x) : no non-missing arguments to min; returning Inf
2: In max(x) : no non-missing arguments to max; returning -Inf

In your example this means that in your line plot(costs,pseudor2,type="l"), costs is completely NA. You have to figure out why this is, but that's the explanation of your error.

From comments:

Scott C Wilson: Another possible cause of this message (not in this case, but in others) is attempting to use character values as X or Y data. You can use the class function to check your x and Y values to be sure if you think this might be your issue.

stevec: Here is a quick and easy solution to that problem (basically wrap x in as.factor(x))

Why Would I Ever Need to Use C# Nested Classes

There is good uses of public nested members too...

Nested classes have access to the private members of the outer class. So a scenario where this is the right way would be when creating a Comparer (ie. implementing the IComparer interface).

In this example, the FirstNameComparer has access to the private _firstName member, which it wouldn't if the class was a separate class...

public class Person
    private string _firstName;
    private string _lastName;
    private DateTime _birthday;

    public class FirstNameComparer : IComparer<Person>
        public int Compare(Person x, Person y)
            return x._firstName.CompareTo(y._firstName);

Manually Triggering Form Validation using jQuery

TL;DR: Not caring about old browsers? Use form.reportValidity().

Need legacy browser support? Read on.

It actually is possible to trigger validation manually.

I'll use plain JavaScript in my answer to improve reusability, no jQuery is needed.

Assume the following HTML form:

  <input required>
  <button type="button">Trigger validation</button>

And let's grab our UI elements in JavaScript:

var form = document.querySelector('form')
var triggerButton = document.querySelector('button')

Don't need support for legacy browsers like Internet Explorer? This is for you.

All modern browsers support the reportValidity() method on form elements.

triggerButton.onclick = function () {

That's it, we're done. Also, here's a simple CodePen using this approach.

Approach for older browsers

Below is a detailed explanation how reportValidity() can be emulated in older browsers.

However, you don't need to copy&paste those code blocks into your project yourself — there is a ponyfill/polyfill readily available for you.

Where reportValidity() is not supported, we need to trick the browser a little bit. So, what will we do?

  1. Check validity of the form by calling form.checkValidity(). This will tell us if the form is valid, but not show the validation UI.
  2. If the form is invalid, we create a temporary submit button and trigger a click on it. Since the form is not valid, we know it won't actually submit, however, it will show validation hints to the user. We'll remove the temporary submit button immedtiately, so it will never be visible to the user.
  3. If the form is valid, we don't need to interfere at all and let the user proceed.

In code:

triggerButton.onclick = function () {
  // Form is invalid!
  if (!form.checkValidity()) {
    // Create the temporary button, click and remove it
    var tmpSubmit = document.createElement('button')

  } else {
    // Form is valid, let the user proceed or do whatever we need to

This code will work in pretty much any common browser (I've tested it successfully down to IE11).

Here's a working CodePen example.

How to install pandas from pip on windows cmd?

Reply to abccd and Question to anyone:

The command: C:\Python34\Scripts>py -3 -m pip install pandas executed just fine. Unfortunately, I can't import Pandas.

Directory path: C:\users\myname\downloads\miniconda3\lib\site-packages

My Question: How is it that Pandas' dependency packages(numpy, python-dateutil, pytz, six) also having the same above directory path are able to import just fine but Pandas does not?

import pandas

Traceback (most recent call last):
  File "<pyshell#9>", line 1, in <module>
    import pandas
ImportError: No module named 'pandas'

I finally got Pandas reinstalled and imported with the help of the following web pages: * (Pages 403 and 404 of 2215 ... 2.2.2 Installing Pandas with Miniconda) * *

After installing Miniconda, I created a new environment area to get Pandas reinstalled and imported. This new environment included the current Python version 3.6.3. I could not import Pandas using Python 3.4.4.

How to use setArguments() and getArguments() methods in Fragments?

in Frag1:

Bundle b = new Bundle();

b.putStringArray("arrayname that use to retrive in frag2",StringArrayObject);


in Frag2:

Bundle b = getArguments();

String[] stringArray = b.getStringArray("arrayname that passed in frag1");

It's that simple.

How can I exclude $(this) from a jQuery selector?

You can also use the jQuery .siblings() method:


<div class="content">
  <a href="#">A</a>
  <a href="#">B</a>
  <a href="#">C</a>


$(".content").on('click', 'a', function(e) {

Working demo:

Python NoneType object is not callable (beginner)

You should not pass the call function hi() to the loop() function, This will give the result.

def hi():     

def loop(f, n):         #f repeats n times
  if n<=0:
    loop(f, n-1)    

loop(hi, 5)            # Do not use hi() function inside loop() function

Disable single warning error

#pragma warning( push )
#pragma warning( disable : 4101)
// Your function
#pragma warning( pop ) 

How to put wildcard entry into /etc/hosts?

use dnsmasq

pretending you're using a debian-based dist(ubuntu,mint..), check if it's installed with

(sudo) systemctl status dnsmasq

If it is just disabled start it with

(sudo) systemctl start dnsmasq

If you have to install it, write

(sudo) apt-get install dnsmasq

To define domains to resolve edit /etc/dnsmasq.conf like this


to resolve *

! You need to reload dnsmasq to take effect for the changes !

systemctl reload dnsmasq

How to download file from database/folder using php

here is the code to download file with how much % it is downloaded

$ch = curl_init();
$downloadFile = fopen( 'file name here', 'w' );
curl_setopt($ch, CURLOPT_URL, "file link here");
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_BUFFERSIZE, 65536);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($ch, CURLOPT_PROGRESSFUNCTION, 'downloadProgress'); 
curl_setopt($ch, CURLOPT_NOPROGRESS, false);
curl_setopt( $ch, CURLOPT_FILE, $downloadFile );

function downloadProgress ($resource, $download_size, $downloaded_size, $upload_size, $uploaded_size) {

    $percen= (($downloaded_size/$download_size)*100);
    echo $percen."<br>";



jQuery .val change doesn't change input value

Changing the value property does not change the defaultValue. In the code (retrieved with .html() or innerHTML) the value attribute will contain the defaultValue, not the value property.

Save file/open file dialog box, using Swing & Netbeans GUI editor

I have created a sample UI which shows the save and open file dialog. Click on save button to open save dialog and click on open button to open file dialog.

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class FileChooserEx {
    public static void main(String[] args) {
        Runnable r = new Runnable() {

            public void run() {
                new FileChooserEx().createUI();


    private void createUI() {
        JFrame frame = new JFrame();
        frame.setLayout(new BorderLayout());

        JButton saveBtn = new JButton("Save");
        JButton openBtn = new JButton("Open");

        saveBtn.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent arg0) {
                JFileChooser saveFile = new JFileChooser();

        openBtn.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent arg0) {
                JFileChooser openFile = new JFileChooser();

        frame.add(new JLabel("File Chooser"), BorderLayout.NORTH);
        frame.add(saveBtn, BorderLayout.CENTER);
        frame.add(openBtn, BorderLayout.SOUTH);
        frame.setTitle("File Chooser");

Why do I need an IoC container as opposed to straightforward DI code?

As you continue to decouple your classes and invert your dependencies, the classes continue to stay small and the "dependency graph" continues to grow in size. (This isn't bad.) Using basic features of an IoC container makes wiring up all these objects trivial, but doing it manually can get very burdensome. For example, what if I want to create a new instance of "Foo" but it needs a "Bar". And a "Bar" needs an "A", "B", and "C". And each of those need 3 other things, etc etc. (yes, I can't come up with good fake names :) ).

Using an IoC container to build your object graph for you reduces complexity a ton and pushes it out into one-time configuration. I simply say "create me a 'Foo'" and it figures out what's needed to build one.

Some people use the IoC containers for much more infrastructure, which is fine for advanced scenarios but in those cases I agree it can obfuscate and make code hard to read and debug for new devs.

Downcasting in Java

Consider the below example

public class ClastingDemo {

 * @param args
public static void main(String[] args) {
    AOne obj = new Bone();
    ((Bone) obj).method2();

class AOne {
public void method1() {
    System.out.println("this is superclass");

 class Bone extends AOne {

public void method2() {
    System.out.println("this is subclass");

here we create the object of subclass Bone and assigned it to super class AOne reference and now superclass reference does not know about the method method2 in the subclass i.e Bone during compile time.therefore we need to downcast this reference of superclass to subclass reference so as the resultant reference can know about the presence of methods in the subclass i.e Bone

How to get element value in jQuery

  <div class="inter">
      <p>Liste des Produits</p>
          <li><a href="#1">P1</a></li>
          <li><a href="#2">P2</a></li>
          <li><a href="#3">P3</a></li>

            $(".inter li").bind(
            "click", function(){

Default interface methods are only supported starting with Android N

This also happened to me but using Dynamic Features. I already had Java 8 compatibility enabled in the app module but I had to add this compatibility lines to the Dynamic Feature module and then it worked.

Embed YouTube video - Refused to display in a frame because it set 'X-Frame-Options' to 'SAMEORIGIN'

If embed no longer works for you, try with /v instead:

<iframe width="420" height="315" src="" frameborder="0" allowfullscreen></iframe>


Try the following:

SELECT 'A string', 5, idTable2 idTable2 FROM table2 WHERE ...

How to break lines at a specific character in Notepad++?

Let's assume ], is the character where we wanted to break at

  1. Open notePad++
  2. Open Find window Ctrl+F
  3. Switch to Replace Tab
  4. Choose Search Mode to Extended
  5. Type ], in Find What field
  6. Type \nin Replace with field
  7. Hit Replace All
  8. Boom

Merge, update, and pull Git branches without using checkouts

It is absolutely possible to do any merge, even non-fast forward merges, without git checkout. The worktree answer by @grego is a good hint. To expand on that:

cd local_repo
git worktree add _master_wt master
cd _master_wt
git pull origin master:master
git merge --no-ff -m "merging workbranch" my_work_branch
cd ..
git worktree remove _master_wt

You have now merged the local work branch to the local master branch without switching your checkout.

Get difference between 2 dates in JavaScript?

I tried lots of ways, and found that using datepicker was the best, but the date format causes problems with JavaScript....

So here's my answer and can be run out of the box.

<input type="text" id="startdate">
<input type="text" id="enddate">
<input type="text" id="days">

<script src=""></script>
<script src=""></script>
<link rel="stylesheet" href="" />
$(document).ready(function() {

$( "#startdate,#enddate" ).datepicker({
changeMonth: true,
changeYear: true,
firstDay: 1,
dateFormat: 'dd/mm/yy',

$( "#startdate" ).datepicker({ dateFormat: 'dd-mm-yy' });
$( "#enddate" ).datepicker({ dateFormat: 'dd-mm-yy' });

$('#enddate').change(function() {
var start = $('#startdate').datepicker('getDate');
var end   = $('#enddate').datepicker('getDate');

if (start<end) {
var days   = (end - start)/1000/60/60/24;
else {
alert ("You cant come back before you have been!");
}); //end change function
}); //end ready

a Fiddle can be seen here DEMO

cast a List to a Collection

Casting never needs a new:

Collection<T> collection = myList;

You don't even make the cast explicit, because Collection is a super-type of List, so it will work just like this.

Java 256-bit AES Password-Based Encryption

Consider using the Spring Security Crypto Module

The Spring Security Crypto module provides support for symmetric encryption, key generation, and password encoding. The code is distributed as part of the core module but has no dependencies on any other Spring Security (or Spring) code.

It's provides a simple abstraction for encryption and seems to match what's required here,

The "standard" encryption method is 256-bit AES using PKCS #5's PBKDF2 (Password-Based Key Derivation Function #2). This method requires Java 6. The password used to generate the SecretKey should be kept in a secure place and not be shared. The salt is used to prevent dictionary attacks against the key in the event your encrypted data is compromised. A 16-byte random initialization vector is also applied so each encrypted message is unique.

A look at the internals reveals a structure similar to erickson's answer.

As noted in the question, this also requires the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy (else you'll encounter InvalidKeyException: Illegal Key Size). It's downloadable for Java 6, Java 7 and Java 8.

Example usage


public class CryptoExample {
    public static void main(String[] args) {
        final String password = "I AM SHERLOCKED";  
        final String salt = KeyGenerators.string().generateKey();
        TextEncryptor encryptor = Encryptors.text(password, salt);      
        System.out.println("Salt: \"" + salt + "\"");
        String textToEncrypt = "*royal secrets*";
        System.out.println("Original text: \"" + textToEncrypt + "\"");
        String encryptedText = encryptor.encrypt(textToEncrypt);
        System.out.println("Encrypted text: \"" + encryptedText + "\"");
        // Could reuse encryptor but wanted to show reconstructing TextEncryptor
        TextEncryptor decryptor = Encryptors.text(password, salt);
        String decryptedText = decryptor.decrypt(encryptedText);
        System.out.println("Decrypted text: \"" + decryptedText + "\"");
        if(textToEncrypt.equals(decryptedText)) {
            System.out.println("Success: decrypted text matches");
        } else {
            System.out.println("Failed: decrypted text does not match");

And sample output,

Salt: "feacbc02a3a697b0"
Original text: "*royal secrets*"
Encrypted text: "7c73c5a83fa580b5d6f8208768adc931ef3123291ac8bc335a1277a39d256d9a" 
Decrypted text: "*royal secrets*"
Success: decrypted text matches

How to replace <span style="font-weight: bold;">foo</span> by <strong>foo</strong> using PHP and regex?

$text='<span style="font-weight: bold;">Foo</span>';
$text=preg_replace( '/<span style="font-weight: bold;">(.*?)<\/span>/', '<strong>$1</strong>',$text);

Note: only work for your example.

Is it possible to have placeholders in strings.xml for runtime values?

A Direct Kotlin Solution to the problem:


<string name="customer_message">Hello, %1$s!\nYou have %2$d Products in your cart.</string>


val username = "Andrew"
val products = 1000
val text: String = String.format(
      resources.getString(R.string.customer_message), username, products )

Writing a dictionary to a text file?

exDict = {1:1, 2:2, 3:3}
with open('file.txt', 'w+') as file:

Javascript call() & apply() vs bind()?

call/apply executes function immediately:, arguments);
func.apply(context, [argument1,argument2,..]);

bind doesn't execute function immediately, but returns wrapped apply function (for later execution):

function bind(func, context) {
    return function() {
        return func.apply(context, arguments);

How to run DOS/CMD/Command Prompt commands from VB.NET?

Imports System.IO
Public Class Form1
    Public line, counter As String
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        counter += 1
        If TextBox1.Text = "" Then
            MsgBox("Enter a DNS address to ping")
            'line = ":start" + vbNewLine
            'line += "ping " + TextBox1.Text
            Dim StreamToWrite As StreamWriter
            StreamToWrite = New StreamWriter("C:\Desktop\Ping" + counter + ".bat")
            StreamToWrite.Write(":start" + vbNewLine + _
                                "Ping -t " + TextBox1.Text)
            Dim p As New System.Diagnostics.Process()
            p.StartInfo.FileName = "C:\Desktop\Ping" + counter + ".bat"
        End If
    End Sub
End Class

This works as well

Finding local maxima/minima with Numpy in a 1D numpy array

Why not use Scipy built-in function signal.find_peaks_cwt to do the job ?

from scipy import signal
import numpy as np

#generate junk data (numpy 1D arr)
xs = np.arange(0, np.pi, 0.05)
data = np.sin(xs)

# maxima : use builtin function to find (max) peaks
max_peakind = signal.find_peaks_cwt(data, np.arange(1,10))

# inverse  (in order to find minima)
inv_data = 1/data
# minima : use builtin function fo find (min) peaks (use inversed data)
min_peakind = signal.find_peaks_cwt(inv_data, np.arange(1,10))

#show results
print "maxima",  data[max_peakind]
print "minima",  data[min_peakind]


maxima [ 0.9995736]
minima [ 0.09146464]


How do I use the Simple HTTP client in Android?

You can use this code:

int count;
            try {
                URL url = new URL(f_url[0]);
                URLConnection conection = url.openConnection();
                // Getting file length
                int lenghtOfFile = conection.getContentLength();
                // Create a Input stream to read file - with 8k buffer
                InputStream input = new BufferedInputStream(url.openStream(),
                // Output stream to write file
                OutputStream output = new FileOutputStream(

                byte data[] = new byte[1024];
                long total = 0;
                while ((count = != -1) {
                    total += count;
                    // publishing the progress....
                    // After this onProgressUpdate will be called
                    publishProgress("" + (int) ((total * 100) / lenghtOfFile));
                    // writing data to file
                    output.write(data, 0, count);
                // flushing output
                // closing streams
            } catch (SocketTimeoutException e) {
            } catch (Exception e) {
                Log.e("Error: ", e.getMessage());

How to find the highest value of a column in a data frame in R?

To get the max of any column you want something like:

max(ozone$Ozone, na.rm = TRUE)

To get the max of all columns, you want:

apply(ozone, 2, function(x) max(x, na.rm = TRUE))

And to sort:


Or to sort the other direction:


Implements vs extends: When to use? What's the difference?


  • class extends only one class
  • interface extends one or more interfaces


  • class implements one or more interfaces
  • interfaces 'can not' implements anything

abstract classes also act like class, with extends and implements

Stop mouse event propagation

Disable href link with JavaScript

<a href="#" onclick="return yes_js_login();">link</a>

yes_js_login = function() {
     // Your code here
     return false;

How it should also work in TypeScript with Angular (My Version: 4.1.2)

<a class="list-group-item list-group-item-action" (click)="employeesService.selectEmployeeFromList($event); false" [routerLinkActive]="['active']" [routerLink]="['/employees', 1]">
public selectEmployeeFromList(e) {


    console.log("This onClick method should prevent routerLink from executing.");

    return false;

But it does not disable the executing of routerLink!

How do you rename a MongoDB database?

There is no mechanism to re-name databases. The currently accepted answer at time of writing is factually correct and offers some interesting background detail as to the excuse upstream, but offers no suggestions for replicating the behavior. Other answers point at copyDatabase, which is no longer an option as the functionality has been removed in 4.0. I've updated SERVER-701 with my notes and incredulity.

Equivalent behavior involves mongodump and mongorestore in a bit of a dance:

  1. Export your data, making note of the "namespaces" in use. For example, on one of my datasets, I have a collection with the namespace byzmcbehoomrfjcs9vlj.Analytics — that prefix (actually the database name) will be needed in the next step.

  2. Import your data, supplying --nsFrom and --nsTo arguments. (Documentation.) Continuing with my above hypothetical (and extremely unreadable) example, to restore to a more sensical name, I invoke:

mongorestore --archive=backup.agz --gzip --drop \
    --nsFrom 'byzmcbehoomrfjcs9vlj.*' --nsTo 'rita.*'

Some may also point at the --db argument to mongorestore, however this, too, is deprecated and triggers a warning against use on non-BSON folder backups with a completely erroneous suggestion to "use --nsInclude instead". The above namespace translation is equivalent to use of the --db option, and is the correct namespace manipulation setup to use as we are not attempting to filter what is being restored.

Find objects between two dates MongoDB

use $gte and $lte to find between date data's in mongodb

var tomorrowDate = moment(new Date()).add(1, 'days').format("YYYY-MM-DD");
db.collection.find({"plannedDeliveryDate":{ $gte: new Date(tomorrowDate +"T00:00:00.000Z"),$lte: new Date(tomorrowDate + "T23:59:59.999Z")}})

Object cannot be cast from DBNull to other types

TryParse is usually the most elegant way to handle this type of thing:

long temp = 0;
if (Int64.TryParse(dataAccCom.GetParameterValue(IDbCmd, "op_Id").ToString(), out temp))
   DataTO.Id = temp;

Convert floating point number to a certain precision, and then copy to string

The str function has a bug. Please try the following. You will see '0,196553' but the right output is '0,196554'. Because the str function's default value is ROUND_HALF_UP.

>>> value=0.196553500000 
>>> str("%f" % value).replace(".", ",")

What special characters must be escaped in regular expressions?

Maybe an old thread, but this code might be useful to visitors who want to create without regex

def listToString(s):  
    # initialize an empty string 
    str1 = "" 
    # return string   
    return (str1.join(s))

r = "Hello! How are you? *Smiling_Face* *Heart* erwer"
r1 = list(r)
i = 0
r2 = list()
start = True

for string in r1:
    if string == "*":
            start = False
            start = True
            print("skipped" + string)

How can I do DNS lookups in Python, including referring to /etc/hosts?

Sounds like you don't want to resolve dns yourself (this might be the wrong nomenclature) dnspython appears to be a standalone dns client that will understandably ignore your operating system because its bypassing the operating system's utillities.

We can look at a shell utility named getent to understand how the (debian 11 alike) operating system resolves dns for programs, this is likely the standard for all *nix like systems that use a socket implementation.

see man getent's "hosts" section, which mentions the use of getaddrinfo, which we can see as man getaddrinfo

and to use it in python, we have to extract some info from the data structures


import socket

def get_ipv4_by_hostname(hostname):
    # see `man getent` `/ hosts `
    # see `man getaddrinfo`

    return list(
        i        # raw socket structure
            [4]  # internet protocol info
            [0]  # address
        for i in 
            0  # port, required
        if i[0] is socket.AddressFamily.AF_INET  # ipv4

        # ignore duplicate addresses with other socket types
        and i[1] is socket.SocketKind.SOCK_RAW  


Byte Array and Int conversion in Java

You can also use BigInteger for variable length bytes. You can convert it to Long, Integer or Short, whichever suits your needs.

new BigInteger(bytes).intValue();

or to denote polarity:

new BigInteger(1, bytes).intValue();

To get bytes back just:

new BigInteger(bytes).toByteArray()

How can I get a Unicode character's code?

In Java, char is technically a "16-bit integer", so you can simply cast it to int and you'll get it's code. From Oracle:

The char data type is a single 16-bit Unicode character. It has a minimum value of '\u0000' (or 0) and a maximum value of '\uffff' (or 65,535 inclusive).

So you can simply cast it to int.

char registered = '®';
System.out.println(String.format("This is an int-code: %d", (int) registered));
System.out.println(String.format("And this is an hexa code: %x", (int) registered));

How to check if array is not empty?

An easy way is to use Boolean expressions:

if not self.table[5]:
    print('list is empty')
    print('list is not empty')

Or you can use another Boolean expression :

if self.table[5] == []:
    print('list is empty')
    print('list is not empty')

How do I get the total Json record count using JQuery?

The OP is trying to count the number of properties in a JSON object. This could be done with an incremented temp variable in the iterator, but he seems to want to know the count before the iteration begins. A simple function that meets the need is provided at the bottom of this page.

Here's a cut and paste of the code, which worked for me:

function countProperties(obj) {
  var prop;
  var propCount = 0;

  for (prop in obj) {
  return propCount;

This should work well for a JSON object. For other objects, which may derive properties from their prototype chain, you would need to add a hasOwnProperty() test.

Reading a registry key in C#

using Microsoft.Win32;

  string chkRegVC = "NO";
   private void checkReg_vcredist() {

        string regKey = @"SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall";
        using (Microsoft.Win32.RegistryKey uninstallKey = Registry.LocalMachine.OpenSubKey(regKey))
            if (uninstallKey != null)
                string[] productKeys = uninstallKey.GetSubKeyNames();
                foreach (var keyName in productKeys)

                    if (keyName == "{196BB40D-1578-3D01-B289-BEFC77A11A1E}" ||//Visual C++ 2010 Redistributable Package (x86) 
                        keyName == "{DA5E371C-6333-3D8A-93A4-6FD5B20BCC6E}" ||//Visual C++ 2010 Redistributable Package (x64) 
                        keyName == "{C1A35166-4301-38E9-BA67-02823AD72A1B}" ||//Visual C++ 2010 Redistributable Package (ia64) 
                        keyName == "{F0C3E5D1-1ADE-321E-8167-68EF0DE699A5}" ||//Visual C++ 2010 SP1 Redistributable Package (x86) 
                        keyName == "{1D8E6291-B0D5-35EC-8441-6616F567A0F7}" ||//Visual C++ 2010 SP1 Redistributable Package (x64) 
                        keyName == "{88C73C1C-2DE5-3B01-AFB8-B46EF4AB41CD}"   //Visual C++ 2010 SP1 Redistributable Package (ia64) 
                        ) { chkRegVC = "OK"; break; }
                    else { chkRegVC = "NO"; }

How to window.scrollTo() with a smooth effect

2018 Update

Now you can use just window.scrollTo({ top: 0, behavior: 'smooth' }) to get the page scrolled with a smooth effect.

const btn = document.getElementById('elem');_x000D_
btn.addEventListener('click', () => window.scrollTo({_x000D_
  top: 400,_x000D_
  behavior: 'smooth',_x000D_
#x {_x000D_
  height: 1000px;_x000D_
  background: lightblue;_x000D_
<div id='x'>_x000D_
  <button id='elem'>Click to scroll</button>_x000D_

Older solutions

You can do something like this:

var btn = document.getElementById('x');_x000D_
btn.addEventListener("click", function() {_x000D_
  var i = 10;_x000D_
  var int = setInterval(function() {_x000D_
    window.scrollTo(0, i);_x000D_
    i += 10;_x000D_
    if (i >= 200) clearInterval(int);_x000D_
  }, 20);_x000D_
body {_x000D_
  background: #3a2613;_x000D_
  height: 600px;_x000D_
<button id='x'>click</button>

ES6 recursive approach:

const btn = document.getElementById('elem');_x000D_
const smoothScroll = (h) => {_x000D_
  let i = h || 0;_x000D_
  if (i < 200) {_x000D_
    setTimeout(() => {_x000D_
      window.scrollTo(0, i);_x000D_
      smoothScroll(i + 10);_x000D_
    }, 10);_x000D_
btn.addEventListener('click', () => smoothScroll());
body {_x000D_
  background: #9a6432;_x000D_
  height: 600px;_x000D_
<button id='elem'>click</button>

Replacing a fragment with another fragment inside activity group

Please see this Question

You can only replace a "dynamically added fragment".

So, if you want to add a dynamic fragment, see this example.

How to add new DataRow into DataTable?

    GRV.DataSource = Class1.DataTable;

        GRV.DataSource = Class1.DataTable;

How can I enable cURL for an installed Ubuntu LAMP stack?

Try this:

sudo apt-get install -y curl

Integrating Dropzone.js into existing HTML form with other fields

I have a more automated solution for this.


<form role="form" enctype="multipart/form-data" action="{{ $url }}" method="{{ $method }}">
    {{ csrf_field() }}

    <!-- You can add extra form fields here -->

    <input hidden id="file" name="file"/>

    <!-- You can add extra form fields here -->

    <div class="dropzone dropzone-file-area" id="fileUpload">
        <div class="dz-default dz-message">
            <h3 class="sbold">Drop files here to upload</h3>
            <span>You can also click to open file browser</span>

    <!-- You can add extra form fields here -->

    <button type="submit">Submit</button>


Dropzone.options.fileUpload = {
    url: 'blackHole.php',
    addRemoveLinks: true,
    accept: function(file) {
        let fileReader = new FileReader();

        fileReader.onloadend = function() {

            let content = fileReader.result;


// Get file content
$file = base64_decode(request('file'));

No need to disable DropZone Discovery and the normal form submit will be able to send the file with any other form fields through standard form serialization.

This mechanism stores the file contents as base64 string in the hidden input field when it gets processed. You can decode it back to binary string in PHP through the standard base64_decode() method.

I don't know whether this method will get compromised with large files but it works with ~40MB files.

How to view UTF-8 Characters in VIM or Gvim

Is this problem solved meanwhile?

I had the problem that gvim didn't display all unicode characters (but only a subset, including the umlauts and accented characters), while :set guifont? was empty; see my question. After reading here, setting the guifont to a sensible value fixed it for me. However, I don't need characters beyond 2 bytes.

How do the major C# DI/IoC frameworks compare?

See for a comparison of net-ioc-frameworks on google code including linfu and that are not on your list while i write this text.

I worked with It has many features (aop, libraries , docu, ...) and there is a lot of experience with it in the dotnet and the java-world. The features are modularized so you donot have to take all features. The features are abstractions of common issues like databaseabstraction, loggingabstraction. however it is difficuilt to do and debug the IoC-configuration.

From what i have read so far: If i had to chooseh for a small or medium project i would use ninject since ioc-configuration is done and debuggable in c#. But i havent worked with it yet. for large modular system i would stay with because of abstraction-libraries.

Refresh an page on button click

Add one unique session or cookie in button click event then redirect page on same URL using Request.RawUrl Now add code in Page_Load event to grab that session or coockie. If session/cookie matches then you can knows that page redirected using refresh button. So decrease hit counter by 1 to keep it on same number do hitcountr -= hitconter

Else increase the hit counter.

How do you get git to always pull from a specific branch?

There is also a way of configuring Git so, it always pulls and pushes the equivalent remote branch to the branch currently checked out to the working copy. It's called a tracking branch which git ready recommends setting by default.

For the next repository above the present working directory:

git config branch.autosetupmerge true

For all Git repositories, that are not configured otherwise:

git config --global branch.autosetupmerge true

Kind of magic, IMHO but this might help in cases where the specific branch is always the current branch.

When you have branch.autosetupmerge set to true and checkout a branch for the first time, Git will tell you about tracking the corresponding remote branch:

(master)$ git checkout gh-pages
Branch gh-pages set up to track remote branch gh-pages from origin.
Switched to a new branch 'gh-pages'

Git will then push to that corresponding branch automatically:

(gh-pages)$ git push
Counting objects: 8, done.
Delta compression using up to 2 threads.
Compressing objects: 100% (6/6), done.
Writing objects: 100% (6/6), 1003 bytes, done.
Total 6 (delta 2), reused 0 (delta 0)
To [email protected]:bigben87/webbit.git
   1bf578c..268fb60  gh-pages -> gh-pages

How to convert JSONObjects to JSONArray?

Something like this:

JSONObject songs= json.getJSONObject("songs");
Iterator x = songs.keys();
JSONArray jsonArray = new JSONArray();

while (x.hasNext()){
    String key = (String);

Cocoa Touch: How To Change UIView's Border Color And Thickness?

If you didn't want to edit the layer of a UIView, you could always embed the view within another view. The parent view would have its background color set to the border color. It would also be slightly larger, depending upon how wide you want the border to be.

Of course, this only works if your view isn't transparent and you only want a single border color. The OP wanted the border in the view itself, but this may be a viable alternative.

Execute specified function every X seconds

You can do this easily by adding a Timer to your form (from the designer) and setting it's Tick-function to run your isonline-function.

jquery-ui-dialog - How to hook into dialog close event

I believe you can also do it while creating the dialog (copied from a project I did):

dialog = $('#dialog').dialog({
    modal: true,
    autoOpen: false,
    width: 700,
    height: 500,
    minWidth: 700,
    minHeight: 500,
    position: ["center", 200],
    close: CloseFunction,
    overlay: {
        opacity: 0.5,
        background: "black"

Note close: CloseFunction

Using CMake to generate Visual Studio C++ project files

Not sure if it's directly related to the question, but I was looking for an answer for how to generate *.sln from cmake projects I've discovered that one can use something like this:

cmake -G "Visual Studio 10"

The example generates needed VS 2010 files from an input CMakeLists.txt file

input type="submit" Vs button tag are they interchangeable?

<input type='submit' /> doesn't support HTML inside of it, since it's a single self-closing tag. <button>, on the other hand, supports HTML, images, etc. inside because it's a tag pair: <button><img src='myimage.gif' /></button>. <button> is also more flexible when it comes to CSS styling.

The disadvantage of <button> is that it's not fully supported by older browsers. IE6/7, for example, don't display it correctly.

Unless you have some specific reason, it's probably best to stick to <input type='submit' />.

Adding click event handler to iframe

iframe doesn't have onclick event but we can implement this by using iframe's onload event and javascript like this...

function iframeclick() {
document.getElementById("theiframe").contentWindow.document.body.onclick = function() {

<iframe id="theiframe" src="youriframe.html" style="width: 100px; height: 100px;" onload="iframeclick()"></iframe>

I hope it will helpful to you....

android.content.res.Resources$NotFoundException: String resource ID #0x0





There are different versions of setText - one takes a String and one takes an int resource id. If you pass it an integer it will try to look for the corresponding string resource id - which it can't find, which is your error.

I guess app.getTotalDl() returns an int. You need to specifically tell setText to set it to the String value of this int.

setText (int resid) vs setText (CharSequence text)

SQL to Query text in access with an apostrophe in it

You escape ' by doubling it, so:

Select * from tblStudents where name like 'Daniel O''Neal' 

Note that if you're accepting "Daniel O'Neal" from user input, the broken quotation is a serious security issue. You should always sanitize the string or use parametrized queries.

How to count duplicate rows in pandas dataframe?


   one  two  records
0    1    1        2
1    1    2        1

Event system in Python

I created an EventManager class (code at the end). The syntax is the following:

#Create an event with no listeners assigned to it
EventManager.addEvent( eventName = [] )

#Create an event with listeners assigned to it
EventManager.addEvent( eventName = [fun1, fun2,...] )

#Create any number event with listeners assigned to them
EventManager.addEvent( eventName1 = [e1fun1, e1fun2,...], eventName2 = [e2fun1, e2fun2,...], ... )

#Add or remove listener to an existing event
EventManager.eventName += extra_fun
EventManager.eventName -= removed_fun

#Delete an event
del EventManager.eventName

#Fire the event

Here is an Example:

def hello(name):
    print "Hello {}".format(name)
def greetings(name):
    print "Greetings {}".format(name)

EventManager.addEvent( salute = [greetings] )
EventManager.salute += hello

print "\nInitial salute"

print "\nNow remove greetings"
EventManager.salute -= greetings


Initial salute
Greetings Oscar
Hello Oscar

Now remove greetings
Hello Oscar

EventManger Code:

class EventManager:
    class Event:
        def __init__(self,functions):
            if type(functions) is not list:
                raise ValueError("functions parameter has to be a list")
            self.functions = functions
        def __iadd__(self,func):
            return self
        def __isub__(self,func):
            return self
        def __call__(self,*args,**kvargs):
            for func in self.functions : func(*args,**kvargs)
    def addEvent(cls,**kvargs):
        addEvent( event1 = [f1,f2,...], event2 = [g1,g2,...], ... )
        creates events using **kvargs to create any number of events. Each event recieves a list of functions,
        where every function in the list recieves the same parameters.
        def hello(): print "Hello ",
        def world(): print "World"
        EventManager.addEvent( salute = [hello] )
        EventManager.salute += world
        Hello World
        for key in kvargs.keys():
            if type(kvargs[key]) is not list:
                raise ValueError("value has to be a list")
                kvargs[key] = cls.Event(kvargs[key])

How can I reorder my divs using only CSS?

This can be done using Flexbox.

Create a container that applies both display:flex and flex-flow:column-reverse.

/* -- Where the Magic Happens -- */_x000D_
.container {_x000D_
  /* Setup Flexbox */_x000D_
  display: -webkit-box;_x000D_
  display: -moz-box;_x000D_
  display: -ms-flexbox;_x000D_
  display: -webkit-flex;_x000D_
  display: flex;_x000D_
  /* Reverse Column Order */_x000D_
  -webkit-flex-flow: column-reverse;_x000D_
  flex-flow: column-reverse;_x000D_
/* -- Styling Only -- */_x000D_
.container > div {_x000D_
  background: red;_x000D_
  color: white;_x000D_
  padding: 10px;_x000D_
.container > div:last-of-type {_x000D_
  background: blue;_x000D_
<div class="container">_x000D_
  <div class="first">_x000D_
  <div class="second">_x000D_


Difference between Visual Basic 6.0 and VBA

Do you want compare VBA with VB-Classic (VB6..) or VB.NET?

VBA (Visual Basic for Applications) is a vb-classic-based script language embedded in Microsoft Office applications. I think it's language features are similar to those of VB5 (it just lacks some few builtin functions), but:

You have access to the office document you wrote the VBA-script for and so you can e.g.

  • Write macros (=automated routines for little recurring tasks in your office-work)
  • Define new functions for excel-cell-formula
  • Process office data

Example: Set the value of an excel-cell

ActiveSheet.Cells("A1").Value = "Foo"

VBC and -.NET are no script languages. You use them to write standalone-applications with separate IDE's which you can't do with VBA (VBA-scripts just "exist" in Office)

VBA has nothing to do with VB.NET (they just have a similar syntax).

Android: How do bluetooth UUIDs work?

To sum up: UUid is used to uniquely identify applications. Each application has a unique UUid

So, use the same UUid for each device

CSS to prevent child element from inheriting parent styles

CSS rules are inherited by default - hence the "cascading" name. To get what you want you need to use !important:

form div
    font-size: 12px;
    font-weight: bold;

    // any rule you want here, followed by !important

android download pdf from url then open it with a pdf reader

This is the best method to download and view PDF file.You can just call it from anywhere as like

PDFTools.showPDFUrl(context, url);

here below put the code. It will works fine

public class PDFTools {
private static final String TAG = "PDFTools";
private static final String GOOGLE_DRIVE_PDF_READER_PREFIX = "";
private static final String PDF_MIME_TYPE = "application/pdf";
private static final String HTML_MIME_TYPE = "text/html";

public static void showPDFUrl(final Context context, final String pdfUrl ) {
    if ( isPDFSupported( context ) ) {
        downloadAndOpenPDF(context, pdfUrl);
    } else {
        askToOpenPDFThroughGoogleDrive( context, pdfUrl );

public static void downloadAndOpenPDF(final Context context, final String pdfUrl) {
    // Get filename
    //final String filename = pdfUrl.substring( pdfUrl.lastIndexOf( "/" ) + 1 );
    String filename = "";
    try {
        filename = new GetFileInfo().execute(pdfUrl).get();
    } catch (InterruptedException e) {
    } catch (ExecutionException e) {
    // The place where the downloaded PDF file will be put
    final File tempFile = new File( context.getExternalFilesDir( Environment.DIRECTORY_DOWNLOADS ), filename );
    Log.e(TAG,"File Path:"+tempFile);
    if ( tempFile.exists() ) {
        // If we have downloaded the file before, just go ahead and show it.
        openPDF( context, Uri.fromFile( tempFile ) );

    // Show progress dialog while downloading
    final ProgressDialog progress = context, context.getString( R.string.pdf_show_local_progress_title ), context.getString( R.string.pdf_show_local_progress_content ), true );

    // Create the download request
    DownloadManager.Request r = new DownloadManager.Request( Uri.parse( pdfUrl ) );
    r.setDestinationInExternalFilesDir( context, Environment.DIRECTORY_DOWNLOADS, filename );
    final DownloadManager dm = (DownloadManager) context.getSystemService( Context.DOWNLOAD_SERVICE );
    BroadcastReceiver onComplete = new BroadcastReceiver() {
        public void onReceive(Context context, Intent intent) {
            if ( !progress.isShowing() ) {
            context.unregisterReceiver( this );

            long downloadId = intent.getLongExtra( DownloadManager.EXTRA_DOWNLOAD_ID, -1 );
            Cursor c = dm.query( new DownloadManager.Query().setFilterById( downloadId ) );

            if ( c.moveToFirst() ) {
                int status = c.getInt( c.getColumnIndex( DownloadManager.COLUMN_STATUS ) );
                if ( status == DownloadManager.STATUS_SUCCESSFUL ) {
                    openPDF( context, Uri.fromFile( tempFile ) );
    context.registerReceiver( onComplete, new IntentFilter( DownloadManager.ACTION_DOWNLOAD_COMPLETE ) );

    // Enqueue the request
    dm.enqueue( r );

public static void askToOpenPDFThroughGoogleDrive( final Context context, final String pdfUrl ) {
    new AlertDialog.Builder( context )
            .setTitle( R.string.pdf_show_online_dialog_title )
            .setMessage( R.string.pdf_show_online_dialog_question )
            .setNegativeButton( R.string.pdf_show_online_dialog_button_no, null )
            .setPositiveButton( R.string.pdf_show_online_dialog_button_yes, new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    openPDFThroughGoogleDrive(context, pdfUrl);

public static void openPDFThroughGoogleDrive(final Context context, final String pdfUrl) {
    Intent i = new Intent( Intent.ACTION_VIEW );
    i.setDataAndType(Uri.parse(GOOGLE_DRIVE_PDF_READER_PREFIX + pdfUrl ), HTML_MIME_TYPE );
    context.startActivity( i );

public static final void openPDF(Context context, Uri localUri ) {
    Intent i = new Intent( Intent.ACTION_VIEW );
    i.setDataAndType( localUri, PDF_MIME_TYPE );
    context.startActivity( i );

public static boolean isPDFSupported( Context context ) {
    Intent i = new Intent( Intent.ACTION_VIEW );
    final File tempFile = new File( context.getExternalFilesDir( Environment.DIRECTORY_DOWNLOADS ), "test.pdf" );
    i.setDataAndType( Uri.fromFile( tempFile ), PDF_MIME_TYPE );
    return context.getPackageManager().queryIntentActivities( i, PackageManager.MATCH_DEFAULT_ONLY ).size() > 0;

// get File name from url
static class GetFileInfo extends AsyncTask<String, Integer, String>
    protected String doInBackground(String... urls)
        URL url;
        String filename = null;
        try {
            url = new URL(urls[0]);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                String depo = conn.getHeaderField("Content-Disposition");

                String depoSplit[] = depo.split("filename=");
                filename = depoSplit[1].replace("filename=", "").replace("\"", "").trim();
                filename = "download.pdf";
        } catch (MalformedURLException e1) {
        } catch (IOException e) {
        return filename;

    protected void onPreExecute() {
    protected void onPostExecute(String result) {
        // use result as file name


try it. it will works, enjoy

What is the 'override' keyword in C++ used for?

Wikipedia says:

Method overriding, in object oriented programming, is a language feature that allows a subclass or child class to provide a specific implementation of a method that is already provided by one of its superclasses or parent classes.

In detail, when you have an object foo that has a void hello() function:

class foo {
    virtual void hello(); // Code : printf("Hello!");

A child of foo, will also have a hello() function:

class bar : foo {
    // no functions in here but yet, you can call
    // bar.hello()

However, you may want to print "Hello Bar!" when hello() function is being called from a bar object. You can do this using override

class bar : foo {
    virtual void hello() override; // Code : printf("Hello Bar!");

java calling a method from another class

You're very close. What you need to remember is when you're calling a method from another class you need to tell the compiler where to find that method.

So, instead of simply calling addWord("someWord"), you will need to initialise an instance of the WordList class (e.g. WordList list = new WordList();), and then call the method using that (i.e. list.addWord("someWord");.

However, your code at the moment will still throw an error there, because that would be trying to call a non-static method from a static one. So, you could either make addWord() static, or change the methods in the Words class so that they're not static.

My bad with the above paragraph - however you might want to reconsider ProcessInput() being a static method - does it really need to be?

Where can I set environment variables that crontab will use?

Have 'cron' run a shell script that sets the environment before running the command.


#   @(#)$Id: crontab,v 4.2 2007/09/17 02:41:00 jleffler Exp $
#   Crontab file for Home Directory for Jonathan Leffler (JL)
#Min     Hour    Day     Month   Weekday Command
0        *       *       *       *       /usr/bin/ksh /work1/jleffler/bin/Cron/hourly
1        1       *       *       *       /usr/bin/ksh /work1/jleffler/bin/Cron/daily
23       1       *       *       1-5     /usr/bin/ksh /work1/jleffler/bin/Cron/weekday
2        3       *       *       0       /usr/bin/ksh /work1/jleffler/bin/Cron/weekly
21       3       1       *       *       /usr/bin/ksh /work1/jleffler/bin/Cron/monthly

The scripts in ~/bin/Cron are all links to a single script, 'runcron', which looks like:

:       "$Id:,v 2.1 2001/02/27 00:53:22 jleffler Exp $"
#       Commands to be performed by Cron (no debugging options)

#       Set environment -- not done by cron (usually switches HOME)
. $HOME/.cronfile

base=`basename $0`

if [ ! -x $cmd ]
then cmd=${HOME}/bin/$base

exec $cmd ${@:+"$@"}

(Written using an older coding standard - nowadays, I'd use a shebang '#!' at the start.)

The '~/.cronfile' is a variation on my profile for use by cron - rigorously non-interactive and no echoing for the sake of being noisy. You could arrange to execute the .profile and so on instead. (The REAL_HOME stuff is an artefact of my environment - you can pretend it is the same as $HOME.)

So, this code reads the appropriate environment and then executes the non-Cron version of the command from my home directory. So, for example, my 'weekday' command looks like:

:       "@(#)$Id:,v 1.10 2007/09/17 02:42:03 jleffler Exp $"
#       Commands to be done each weekday

# Update ICSCOPE

The 'daily' command is simpler:

:       "@(#)$Id:,v 1.5 1997/06/02 22:04:21 johnl Exp $"
#       Commands to be done daily

# Nothing -- most things are done on weekdays only

exit 0

How to compare objects by multiple fields

You can implement a Comparator which compares two Person objects, and you can examine as many of the fields as you like. You can put in a variable in your comparator that tells it which field to compare to, although it would probably be simpler to just write multiple comparators.

Adding minutes to date time in PHP

Without using a variable:

 $yourDate->modify("15 minutes");
 echo $yourDate->format( "Y-m-d H:i");

With using a variable:

 $interval= 15;
 $yourDate->modify("+{$interval } minutes");  
 echo $yourDate->format( "Y-m-d H:i");

Add all files to a commit except a single file?

Try this:

git checkout -- main/dontcheckmein.txt

How do I install cygwin components from the command line?

First, download installer at: (Windows 64bit), then:

# move installer to cygwin folder
mv C:/Users/<you>/Downloads/setup-x86_64.exe C:/cygwin64/

# add alias to bash_aliases
echo "alias cygwin='C:/cygwin64/setup-x86_64.exe -q -P'" >> ~/.bash_aliases
source ~/.bash_aliases

# add bash_aliases to bashrc if missing
echo "source ~/.bash_aliases" >> ~/.profile


# install vim
cygwin vim

# see other options
cygwin --help

Display a jpg image on a JPanel

I would use a Canvas that I add to the JPanel, and draw the image on the Canvas. But Canvas is a quite heavy object, sine it is from awt.

Send json post using php

Beware that file_get_contents solution doesn't close the connection as it should when a server returns Connection: close in the HTTP header.

CURL solution, on the other hand, terminates the connection so the PHP script is not blocked by waiting for a response.

How do I set a checkbox in razor view?

You should set the AllowRating property to true, preferably in the controller or model.
Like other inputs, the checkbox's state reflects the value of the property.

How can I print out just the index of a pandas dataframe?

You can use lamba function:

index = df.index[lambda x : for x in df.index() ]

How to debug JavaScript / jQuery event bindings with Firebug or similar tools?

ev icon next to elements

Within the Firefox Developer Tools' Inspector panel lists all events bound to an element.

First select an element with Ctrl + Shift + C, e.g. Stack Overflow's upvote arrow.

Click on the ev icon to the right of the element, and a dialogue opens:

events tooltip

Click on the pause sign || symbol for the event you want, and this opens the debugger on the line of the handler.

You can now place a breakpoint there as usual in the debugger, by clicking on the left margin of the line.

This is mentioned at:

Unfortunately, I couldn't find a way for this to play nicely with prettyfication, it just seems to open at the minified line: How to beautify Javascript and CSS in Firefox / Firebug?

Tested on Firefox 42.

How to install an APK file on an Android phone?

If you dont have SDK or you are setting up 3rd party app here is another way:

  1. Copy the .APK file to your device.
  2. Use file manager to locate the file.
  3. Then click on it.
  4. Android App installer should be one of the options in pop-up.
  5. Select it and it installs.

How to convert an iterator to a stream?

Create Spliterator from Iterator using Spliterators class contains more than one function for creating spliterator, for example here am using spliteratorUnknownSize which is getting iterator as parameter, then create Stream using StreamSupport

Spliterator<Model> spliterator = Spliterators.spliteratorUnknownSize(
        iterator, Spliterator.NONNULL);
Stream<Model> stream =, false);

Detect click outside Angular component

u can call event function like (focusout) or (blur) then u put your code

<div tabindex=0 (blur)="outsideClick()">raw data </div>

 outsideClick() {
  alert('put your condition here');

How to make a Bootstrap accordion collapse when clicking the header div?

Actually my panel had this collapse state arrow icon and I tried other answers in this post , but icon position changed, so here is the solution with collapse state arrow icon.

Add this Custom CSS

   cursor: pointer;
   padding: 0;

  display: block;
  padding: 10px  15px;

Credit's goes to this post answerer.

Hope helps.

Static extension methods

In short, no, you can't.

Long answer, extension methods are just syntactic sugar. IE:

If you have an extension method on string let's say:

public static string SomeStringExtension(this string s)

When you then call it:


The compiler just turns it into:


So as you can see, there's no way to do that for static methods.

And another thing just dawned on me: what would really be the point of being able to add static methods on existing classes? You can just have your own helper class that does the same thing, so what's really the benefit in being able to do:




Doesn't really bring much to the table...

How can I get column names from a table in SQL Server?

Some SQL Generating SQL:

  col001 INTEGER
, col002 INTEGER
, col003 INTEGER
, col004 INTEGER
, col005 INTEGER
, col006 INTEGER
, col007 INTEGER
, col008 INTEGER
, col009 INTEGER
, col010 INTEGER
INSERT INTO test(col001) VALUES(1);
INSERT INTO test(col002) VALUES(1);
INSERT INTO test(col005) VALUES(1);
INSERT INTO test(col009) VALUES(1);

  CASE ROW_NUMBER() OVER(ORDER BY ordinal_position)
    'SELECT'+CHAR(10)+'  *'+CHAR(10)+'FROM test'
   +CHAR(10)+'WHERE '
    '   OR '
+ column_name +' IS NOT NULL'
+ CASE ROW_NUMBER() OVER(ORDER BY ordinal_position DESC)
  FROM information_schema.columns
  WHERE table_schema='dbo'
    AND table_name = 'test'

-- the whole scenario. Works for 10 , will work for 100, too:

-- out -----------------------------------------------
-- out  SELECT
-- out   *
-- out FROM test
-- out WHERE col001 IS NOT NULL
-- out     OR col002 IS NOT NULL
-- out     OR col003 IS NOT NULL
-- out     OR col004 IS NOT NULL
-- out     OR col005 IS NOT NULL
-- out     OR col006 IS NOT NULL
-- out     OR col007 IS NOT NULL
-- out     OR col008 IS NOT NULL
-- out     OR col009 IS NOT NULL
-- out     OR col010 IS NOT NULL
-- out ;

passing several arguments to FUN of lapply (and others *apply)

myfun <- function(x, arg1) {
 # doing something here with x and arg1

x is a vector or a list and myfun in lapply(x, myfun) is called for each element of x separately.

Option 1

If you'd like to use whole arg1 in each myfun call (myfun(x[1], arg1), myfun(x[2], arg1) etc.), use lapply(x, myfun, arg1) (as stated above).

Option 2

If you'd however like to call myfun to each element of arg1 separately alongside elements of x (myfun(x[1], arg1[1]), myfun(x[2], arg1[2]) etc.), it's not possible to use lapply. Instead, use mapply(myfun, x, arg1) (as stated above) or apply:

 apply(cbind(x,arg1), 1, myfun)


 apply(rbind(x,arg1), 2, myfun).

How to filter specific apps for ACTION_SEND intent (and set a different text for each app)

To my knowledge, StackOverflow has lots of people asking this question in various ways, but nobody has answered it completely yet.

My spec called for the user to be able to choose email, twitter, facebook, or SMS, with custom text for each one. Here is how I accomplished that:

public void onShareClick(View v) {
    Resources resources = getResources();

    Intent emailIntent = new Intent();
    // Native email client doesn't currently support HTML, but it doesn't hurt to try in case they fix it
    emailIntent.putExtra(Intent.EXTRA_TEXT, Html.fromHtml(resources.getString(R.string.share_email_native)));
    emailIntent.putExtra(Intent.EXTRA_SUBJECT, resources.getString(R.string.share_email_subject));

    PackageManager pm = getPackageManager();
    Intent sendIntent = new Intent(Intent.ACTION_SEND);     

    Intent openInChooser = Intent.createChooser(emailIntent, resources.getString(R.string.share_chooser_text));

    List<ResolveInfo> resInfo = pm.queryIntentActivities(sendIntent, 0);
    List<LabeledIntent> intentList = new ArrayList<LabeledIntent>();        
    for (int i = 0; i < resInfo.size(); i++) {
        // Extract the label, append it, and repackage it in a LabeledIntent
        ResolveInfo ri = resInfo.get(i);
        String packageName = ri.activityInfo.packageName;
        if(packageName.contains("")) {
        } else if(packageName.contains("twitter") || packageName.contains("facebook") || packageName.contains("mms") || packageName.contains("")) {
            Intent intent = new Intent();
            intent.setComponent(new ComponentName(packageName,;
            if(packageName.contains("twitter")) {
                intent.putExtra(Intent.EXTRA_TEXT, resources.getString(R.string.share_twitter));
            } else if(packageName.contains("facebook")) {
                // Warning: Facebook IGNORES our text. They say "These fields are intended for users to express themselves. Pre-filling these fields erodes the authenticity of the user voice."
                // One workaround is to use the Facebook SDK to post, but that doesn't allow the user to choose how they want to share. We can also make a custom landing page, and the link
                // will show the <meta content ="..."> text from that page with our link in Facebook.
                intent.putExtra(Intent.EXTRA_TEXT, resources.getString(R.string.share_facebook));
            } else if(packageName.contains("mms")) {
                intent.putExtra(Intent.EXTRA_TEXT, resources.getString(R.string.share_sms));
            } else if(packageName.contains("")) { // If Gmail shows up twice, try removing this else-if clause and the reference to "" above
                intent.putExtra(Intent.EXTRA_TEXT, Html.fromHtml(resources.getString(R.string.share_email_gmail)));
                intent.putExtra(Intent.EXTRA_SUBJECT, resources.getString(R.string.share_email_subject));               

            intentList.add(new LabeledIntent(intent, packageName, ri.loadLabel(pm), ri.icon));

    // convert intentList to array
    LabeledIntent[] extraIntents = intentList.toArray( new LabeledIntent[ intentList.size() ]);

    openInChooser.putExtra(Intent.EXTRA_INITIAL_INTENTS, extraIntents);

I found bits of how to do this in various places, but I haven't seen all of it in one place anywhere else.

Note that this method also hides all the silly options that I don't want, like sharing over wifi and bluetooth.

Hope this helps someone.

Edit: In a comment, I was asked to explain what this code is doing. Basically, it's creating an ACTION_SEND intent for the native email client ONLY, then tacking other intents onto the chooser. Making the original intent email-specific gets rid of all the extra junk like wifi and bluetooth, then I grab the other intents I want from a generic ACTION_SEND of type plain-text, and tack them on before showing the chooser.

When I grab the additional intents, I set custom text for each one.

Edit2: It's been awhile since I posted this, and things have changed a bit. If you are seeing gmail twice in the list of options, try removing the special handling for "" as suggested in a comment by @h_k below.

Since this one answer is the source of nearly all my stackoverflow reputation points, I have to at least try to keep it up to date.

Roblox Admin Command Script

for i=1,#target do[i].Character:BreakJoints()

Is incorrect, if "target" contains "FakeNameHereSoNoStalkers" then the run code would be:

Which is completely incorrect.

c = game.Players:GetChildren()

Never use "Players:GetChildren()", it is not guaranteed to return only players.

Instead use:

c = Game.Players:GetPlayers()

if msg:lower()=="me" then
    table.insert(people, source)
    return people

Here you add the player's name in the list "people", where you in the other places adds the player object.

Fixed code:

local Admins = {"FakeNameHereSoNoStalkers"}

function Kill(Players)
    for i,Player in ipairs(Players) do
        if Player.Character then

function IsAdmin(Player)
    for i,AdminName in ipairs(Admins) do
        if Player.Name:lower() == AdminName:lower() then return true end
    return false

function GetPlayers(Player,Msg)
    local Targets = {}
    local Players = Game.Players:GetPlayers()

    if Msg:lower() == "me" then
        Targets = { Player }
    elseif Msg:lower() == "all" then
        Targets = Players
    elseif Msg:lower() == "others" then
        for i,Plr in ipairs(Players) do
            if Plr ~= Player then
        for i,Plr in ipairs(Players) do
            if Plr.Name:lower():sub(1,Msg:len()) == Msg then
    return Targets

    if IsAdmin(Player) then
            if Msg:lower():sub(1,6) == ":kill " then

How to install Android SDK Build Tools on the command line?

By default, the SDK Manager from the command line does not include the build tools in the list. They're in the "obsolete" category. To see all available downloads, use

android list sdk --all

And then to get one of the packages in that list from the command line, use:

android update sdk -u -a -t <package no.>

Where -u stands for --no-ui, -a stands for --all and -t stands for --filter.

If you need to install multiple packages do:

android update sdk -u -a -t 1,2,3,4,..,n 

Where 1,2,..,n is the package number listed with the list command above

How should I load files into my Java application?

public byte[] loadBinaryFile (String name) {
    try {

        DataInputStream dis = new DataInputStream(new FileInputStream(name));
        byte[] theBytes = new byte[dis.available()];, 0, dis.available());
        return theBytes;
    } catch (IOException ex) {
    return null;
} // ()

C++ Redefinition Header Files (winsock2.h)

I ran into this problem when trying to pull a third party package which was apparently including windows.h somewhere in it's mess of headers. Defining _WINSOCKAPI_ at the project level was much easier (not to mention more maintainable) than wading through their soup and fixing the problematic include.

Gradients in Internet Explorer 9

Use an Gradient Generator - and everything will be perfect ;)

Code for printf function in C

Here's the GNU version of printf... you can see it passing in stdout to vfprintf:

__printf (const char *format, ...)
   va_list arg;
   int done;

   va_start (arg, format);
   done = vfprintf (stdout, format, arg);
   va_end (arg);

   return done;

See here.

Here's a link to vfprintf... all the formatting 'magic' happens here.

The only thing that's truly 'different' about these functions is that they use varargs to get at arguments in a variable length argument list. Other than that, they're just traditional C. (This is in contrast to Pascal's printf equivalent, which is implemented with specific support in the compiler... at least it was back in the day.)

How to copy text programmatically in my Android app?

For Kotlin use the below code inside the activity.

import android.content.ClipboardManager

 val clipBoard = getSystemService(Context.CLIPBOARD_SERVICE) as ClipboardManager
 val clipData = ClipData.newPlainText("label","Message to be Copied")

java.sql.SQLException: - ORA-01000: maximum open cursors exceeded

In our case, we were using Hibernate and we had many variables referencing the same Hibernate mapped entity. We were creating and saving these references in a loop. Each reference opened a cursor and kept it open.

We discovered this by using a query to check the number of open cursors while running our code, stepping through with a debugger and selectively commenting things out.

As to why each new reference opened another cursor - the entity in question had collections of other entities mapped to it and I think this had something to do with it (perhaps not just this alone but in combination with how we had configured the fetch mode and cache settings). Hibernate itself has had bugs around failing to close open cursors, though it looks like these have been fixed in later versions.

Since we didn't really need to have so many duplicate references to the same entity anyway, the solution was to stop creating and holding onto all those redundant references. Once we did that the problem when away.

fill an array in C#

int[] arr = Enumerable.Repeat(42, 10000).ToArray();

I believe that this does the job :)

When to use static classes in C#

For C# 3.0, extension methods may only exist in top-level static classes.

if-else statement inside jsx: ReactJS

There's a Babel plugin that allows you to write conditional statements inside JSX without needing to escape them with JavaScript or write a wrapper class. It's called JSX Control Statements:

<View style={styles.container}>
  <If condition={ this.state == 'news' }>

It takes a bit of setting up depending on your Babel configuration, but you don't have to import anything and it has all the advantages of conditional rendering without leaving JSX which leaves your code looking very clean.

is there a post render callback for Angular JS directive?

May be am late to answer this question. But still someone may get benefit out of my answer.

I had similar issue and in my case I can not change the directive since, it is a library and change a code of the library is not a good practice. So what I did was use a variable to wait for page load and use ng-if inside my html to wait render the particular element.

In my controller:


//this will fire after load the the page

angular.element(document).ready(function() {

In my html (in my case html component is a canvas)

<canvas ng-if="render"> </canvas>

onchange equivalent in angular2

You can use:

<input (input)="saverange()>

Associating existing Eclipse project with existing SVN repository

Team->Share project is exactly what you need to do. Select SVN from the list, then click "Next". Subclipse will notice the presence of .svn directories that will ask you to confirm that the information is correct, and associate the project with subclipse.

How to check if div element is empty

You can use .is().

if( $('#leftmenu').is(':empty') ) {

Or you could just test the length property to see if one was found:

if( $('#leftmenu:empty').length ) {

You can use $.trim() to remove whitespace (if that's what you want) and check for the length of the content.

if( !$.trim( $('#leftmenu').html() ).length ) {

Batch files: How to read a file?

Under NT-style cmd.exe, you can loop through the lines of a text file with

FOR /F %i IN (file.txt) DO @echo %i

Type "help for" on the command prompt for more information. (don't know if that works in whatever "DOS" you are using)

Is it possible in Java to access private fields via reflection

Yes, it absolutely is - assuming you've got the appropriate security permissions. Use Field.setAccessible(true) first if you're accessing it from a different class.

import java.lang.reflect.*;

class Other
    private String str;
    public void setStr(String value)
        str = value;

class Test
    public static void main(String[] args)
        // Just for the ease of a throwaway test. Don't
        // do this normally!
        throws Exception
        Other t = new Other();
        Field field = Other.class.getDeclaredField("str");
        Object value = field.get(t);

And no, you shouldn't normally do this... it's subverting the intentions of the original author of the class. For example, there may well be validation applied in any situation where the field can normally be set, or other fields may be changed at the same time. You're effectively violating the intended level of encapsulation.

How to read from stdin line by line in Node

if you want to ask the user number of lines first:

    //array to save line by line 
    let xInputs = [];

    const getInput = async (resolve)=>{
            const readline = require('readline').createInterface({
                input: process.stdin,
                output: process.stdout,

    const getMultiInput = (numberOfInputLines,callback)=>{
        let i = 0;
        let p = Promise.resolve(); 
        for (; i < numberOfInputLines; i++) {
            p = p.then(_ => new Promise(resolve => getInput(resolve)));

    //get number of lines 
    const readline = require('readline').createInterface({
        input: process.stdin,
        output: process.stdout,
        terminal: false
           //get here the inputs from xinputs array 

How to test android apps in a real device with Android Studio?

You have to Download the driver for your Device just go to device manager-->> your device-->update driver-->choose the usb driver path from sdk extras folder and click next. You can get the correct driver and you can run on real device

Sorting by date & time in descending order?

Following Query works for me. Database Tabel t_sonde_results has domain d_date (datatype DATE) and d_time (datatype TIME) The intention is to query for last entry in t_sonde_results sorted by Date and Time

select * from (select * from (SELECT * FROM t_sonde_results WHERE d_user_name = 'kenis' and d_smartbox_id = 6 order by d_time asc) AS tmp order by d_date and d_time limit 1) as tmp1

WPF binding to Listbox selectedItem

For me, I usually use DataContext together in order to bind two-depth property such as this question.

<TextBlock DataContext="{Binding SelectedRule}" Text="{Binding Name}" />

Or, I prefer to use ElementName because it achieves bindings only with view controls.

<TextBlock DataContext="{Binding ElementName=lbRules, Path=SelectedItem}" Text="{Binding Name}" />

Check if a string is null or empty in XSLT

Use simple categoryName/text() Such test works fine on <categoryName/> and also <categoryName></categoryName>.

    <xsl:when test="categoryName/text()">
        <xsl:value-of select="categoryName" />
        <xsl:value-of select="other" />

Detect if Visual C++ Redistributable for Visual Studio 2012 is installed

I've succeded doing this with InnoSetup.

I checked the existence of registry key:


If uninstalled, it does not exist. If installed, it exists.

By the way, it could also be in the Wow6432Node:


Export data to Excel file with ASP.NET MVC 4 C# is rendering into view

I used a list in my controller class to set data into grid view. The code works fine for me:

public ActionResult ExpExcl()
  List<PersonModel> person= new List<PersonModel>
    new PersonModel() {FirstName= "Jenny", LastName="Mathew", Age= 23},
    new PersonModel() {FirstName= "Paul", LastName="Meehan", Age=25}
   var grid= new GridView();
   grid.DataSource= person;

   Response.AddHeader("content-disposition","attachement; filename=data.xls");
   StringWriter sw= new StringWriter();
   HtmlTextWriter htw= new HtmlTextWriter(sw); 
   return View();

Configuring user and password with Git Bash

add remote as:

git remote add https://username:[email protected]/repodir/myrepo.git

Gradle - Move a folder from ABC to XYZ

Your task declaration is incorrectly combining the Copy task type and project.copy method, resulting in a task that has nothing to copy and thus never runs. Besides, Copy isn't the right choice for renaming a directory. There is no Gradle API for renaming, but a bit of Groovy code (leveraging Java's File API) will do. Assuming Project1 is the project directory:

task renABCToXYZ {     doLast {         file("ABC").renameTo(file("XYZ"))     } } 

Looking at the bigger picture, it's probably better to add the renaming logic (i.e. the doLast task action) to the task that produces ABC.

Current Subversion revision command

REV=svn info svn:// | grep 'Revision:' | cut -d\ -f2

Java generating non-repeating random numbers

public class RandomNum {
    public static void main(String[] args) {
        Random rn = new Random();
        HashSet<Integer> hSet = new HashSet<>();
        while(hSet.size() != 1000) {

Adding a Time to a DateTime in C#

You can use the DateTime.Add() method to add the time to the date.

DateTime date = DateTime.Now;
TimeSpan time = new TimeSpan(36, 0, 0, 0);
DateTime combined = date.Add(time);
Console.WriteLine("{0:dddd}", combined);

You can also create your timespan by parsing a String, if that is what you need to do.

Alternatively, you could look at using other controls. You didn't mention if you are using winforms, wpf or, but there are various date and time picker controls that support selection of both date and time.

CSS table layout: why does table-row not accept a margin?

The closest thing I've seen would be to set border-spacing: 0 30px; to the container div. However, this just leaves me with space on the upper edge of the table, which defeats the purpose, since you wanted margin-bottom.

htaccess - How to force the client's browser to clear the cache?

As other answers have said, changing the URL is a good cache busting technique, however it is alot of work to go through a bigger site, change all the URLs and also move the files.

A similar technique is to just add a version parameter to the URL string which is either a random string / number or a version number, and target the changed files only.

For instance if you change your sites CSS and it looks wonky until you do a force refresh, simply add ?ver=1.1 to the CSS import at the head of the file. This to the browser is a different file, but you only need to change the import, not the actual location or name of the file.


<link href="assets/css/style.css" rel="stylesheet" type="text/css" />


<link href="assets/css/style.css?ver=1.1" rel="stylesheet" type="text/css" />

Works great for javascript files also.

How to set custom favicon in Express?

No extra middlewares required. Just use:

app.use('/favicon.ico', express.static('images/favicon.ico'));

How to design RESTful search/filtering?

It seems that resource filtering/searching can be implemented in a RESTful way. The idea is to introduce a new endpoint called /filters/ or /api/filters/.

Using this endpoint filter can be considered as a resource and hence created via POST method. This way - of course - body can be used to carry all the parameters as well as complex search/filter structures can be created.

After creating such filter there are two possibilities to get the search/filter result.

  1. A new resource with unique ID will be returned along with 201 Created status code. Then using this ID a GET request can be made to /api/users/ like:

    GET /api/users/?filterId=1234-abcd
  2. After new filter is created via POST it won't reply with 201 Created but at once with 303 SeeOther along with Location header pointing to /api/users/?filterId=1234-abcd. This redirect will be automatically handled via underlying library.

In both scenarios two requests need to be made to get the filtered results - this may be considered as a drawback, especially for mobile applications. For mobile applications I'd use single POST call to /api/users/filter/.

How to keep created filters?

They can be stored in DB and used later on. They can also be stored in some temporary storage e.g. redis and have some TTL after which they will expire and will be removed.

What are the advantages of this idea?

Filters, filtered results are cacheable and can be even bookmarked.

QR Code encoding and decoding using zxing

So, for future reference for anybody who doesn't want to spend two days searching the internet to figure this out, when you encode byte arrays into QR Codes, you have to use the ISO-8859-1character set, not UTF-8.

How do I get the name of the current executable in C#?

To get the path and the name


How to make a gap between two DIV within the same column

You can make use of the first-child selector

<div class="sidebar">
    <div class="box">
            Text is here
    <div class="box">
            Text is here

and in CSS

.box {
    padding: 10px;
    text-align: justify;
    margin-top: 20px;
.box:first-child {
    margin-top: none;


How do I force detach Screen from another SSH session?

Short answer

  1. Reattach without ejecting others: screen -x
  2. Get list of displays: ^A *, select the one to disconnect, press d

Explained answer

Background: When I was looking for the solution with same problem description, I have always landed on this answer. I would like to provide more sensible solution. (For example: the other attached screen has a different size and a I cannot force resize it in my terminal.)

Note: PREFIX is usually ^A = ctrl+a

Note: the display may also be called:

  • "user front-end" (in at command manual in screen)
  • "client" (tmux vocabulary where this functionality is detach-client)
  • "terminal" (as we call the window in our user interface) /depending on

1. Reattach a session: screen -x

-x attach to a not detached screen session without detaching it

2. List displays of this session: PREFIX *

It is the default key binding for: PREFIX :displays. Performing it within the screen, identify the other display we want to disconnect (e.g. smaller size). (Your current display is displayed in brighter color/bold when not selected).

term-type   size         user interface           window       Perms
---------- ------- ---------- ----------------- ----------     -----
 screen     240x60         you@/dev/pts/2      nb  0(zsh)        rwx
 screen      78x40         you@/dev/pts/0      nb  0(zsh)        rwx

Using arrows ? ?, select the targeted display, press d If nothing happens, you tried to detach your own display and screen will not detach it. If it was another one, within a second or two, the entry will disappear.

Press ENTER to quit the listing.

Optionally: in order to make the content fit your screen, reflow: PREFIX F (uppercase F)

Excerpt from man page of screen:


Shows a tabular listing of all currently connected user front-ends (displays). This is most useful for multiuser sessions. The following keys can be used in displays list:

  • mouseclick Move to the selected line. Available when "mousetrack" is set to on.
  • space Refresh the list
  • d Detach that display
  • D Power detach that display
  • C-g, enter, or escape Exit the list

Numpy Resize/Rescale Image

SciPy's imresize() method was another resize method, but it will be removed starting with SciPy v 1.3.0 . SciPy refers to PIL image resize method: Image.resize(size, resample=0)

size – The requested size in pixels, as a 2-tuple: (width, height).
resample – An optional resampling filter. This can be one of PIL.Image.NEAREST (use nearest neighbour), PIL.Image.BILINEAR (linear interpolation), PIL.Image.BICUBIC (cubic spline interpolation), or PIL.Image.LANCZOS (a high-quality downsampling filter). If omitted, or if the image has mode “1” or “P”, it is set PIL.Image.NEAREST.

Link here:

How to Find And Replace Text In A File With C#

It is likely you will have to pull the text file into memory and then do the replacements. You will then have to overwrite the file using the method you clearly know about. So you would first:

// Read lines from source file.
string[] arr = File.ReadAllLines(file);

YOu can then loop through and replace the text in the array.

var writer = new StreamWriter(GetFileName(baseFolder, prefix, num));
for (int i = 0; i < arr.Length; i++)
    string line = arr[i];
    line.Replace("match", "new value");

this method gives you some control on the manipulations you can do. Or, you can merely do the replace in one line

File.WriteAllText("test.txt", text.Replace("match", "new value"));

I hope this helps.

How do I create a multiline Python string with inline variables?

You can use Python 3.6's f-strings for variables inside multi-line or lengthy single-line strings. You can manually specify newline characters using \n.

Variables in a multi-line string

string1 = "go"
string2 = "now"
string3 = "great"

multiline_string = (f"I will {string1} there\n"
                    f"I will go {string2}.\n"


I will go there
I will go now

Variables in a lengthy single-line string

string1 = "go"
string2 = "now"
string3 = "great"

singleline_string = (f"I will {string1} there. "
                     f"I will go {string2}. "


I will go there. I will go now. great.

Alternatively, you can also create a multiline f-string with triple quotes.

multiline_string = f"""I will {string1} there.
I will go {string2}.

Oracle: SQL query that returns rows with only numeric values

You can use the REGEXP_LIKE function as:

FROM myTable 
WHERE REGEXP_LIKE(X, '^[[:digit:]]+$');

Sample run:






Is there a way to ignore a single FindBugs warning?

The FindBugs initial approach involves XML configuration files aka filters. This is really less convenient than the PMD solution but FindBugs works on bytecode, not on the source code, so comments are obviously not an option. Example:

   <Class name="com.mycompany.Foo" />
   <Method name="bar" />

However, to solve this issue, FindBugs later introduced another solution based on annotations (see SuppressFBWarnings) that you can use at the class or at the method level (more convenient than XML in my opinion). Example (maybe not the best one but, well, it's just an example):

    justification="I know what I'm doing")

Note that since FindBugs 3.0.0 SuppressWarnings has been deprecated in favor of @SuppressFBWarnings because of the name clash with Java's SuppressWarnings.

jQuery trigger file input

Just for the sake of curiosity, you can do something like you want by dynamically creating an upload form and input file, without adding it to the DOM tree:

$('.your-button').on('click', function() {
    var uploadForm = document.createElement('form');
    var fileInput = uploadForm.appendChild(document.createElement('input'));

    fileInput.type = 'file'; = 'images';
    fileInput.multiple = true;;

No need to add the uploadForm to the DOM.

How do I prevent and/or handle a StackOverflowException?

You can read up this property every few calls, Environment.StackTrace , and if the stacktrace exceded a specific threshold that you preset, you can return the function.

You should also try to replace some recursive functions with loops.