Programs & Examples On #Tcmalloc

TCMalloc is a malloc library developed by Google. It is faster than the glibc 2.3 malloc (ptmalloc2), which takes approximately 300ns to execute a malloc/free pair on a 2.8GHz P4 (for small objects). TCMalloc takes approximately 50ns for the same operation pair. It also reduces lock contention for multi-threaded programs. For small objects, there is virtually zero contention. Another benefit is space-efficient representation of small objects.

Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured

If you have a JPA dependency in your pom.xml then just remove it. This solution worked for me.

how to set mongod --dbpath

First you will have a config file in /etc/mongodb.conf, therefore this sounds like a homebrew install which will use some more standardized paths. The whole /data/db/ thing is referenced in a lot of manual install documentation.

So basically from your log the server is not running, it's shutting down, so there is nothing for the shell to connect to. Seems like you have had some unclean shutdowns/restarts which has led to the inconsistency.

Clear the files in the journal /usr/local/var/mongodb/journal/ on your config.

Also:

sudo rm /var/lib/mongodb/mongod.lock

Just in case, even though that part looks clean. And then restart.

ECONNREFUSED error when connecting to mongodb from node.js

Use this code to setup your mongodb connection:

var mongoose = require('mongoose');

var mongoURI = "mongodb://localhost:27017/test";
var MongoDB = mongoose.connect(mongoURI).connection;
MongoDB.on('error', function(err) { console.log(err.message); });
MongoDB.once('open', function() {
  console.log("mongodb connection open");
});

Make sure mongod is running while you start the server. Are you using Express or just a simple node.js server? What is the error message you get with the above code?

What is the LD_PRELOAD trick?

You can override symbols in the stock libraries by creating a library with the same symbols and specifying the library in LD_PRELOAD.

Some people use it to specify libraries in nonstandard locations, but LD_LIBRARY_PATH is better for that purpose.

Change bootstrap datepicker date format on select

I am using Bootstrap v3.3.4 and using the code:

 $('.datepicker').datepicker({
    dateFormat: 'dd-mm-yy'
 });

Output is: 16-07-2015

Note: only need "yy" for full year.

SQL How to remove duplicates within select query?

If you want to select any random single row for particular day, then

SELECT * FROM table_name GROUP BY DAY(start_date)

If you want to select single entry for each user per day, then

SELECT * FROM table_name GROUP BY DAY(start_date),owner_name

How to call any method asynchronously in c#

public partial class MainForm : Form
{
    Image img;
    private void button1_Click(object sender, EventArgs e)
    {
        LoadImageAsynchronously("http://media1.santabanta.com/full5/Indian%20%20Celebrities(F)/Jacqueline%20Fernandez/jacqueline-fernandez-18a.jpg");
    }

    private void LoadImageAsynchronously(string url)
    {
        /*
        This is a classic example of how make a synchronous code snippet work asynchronously.
        A class implements a method synchronously like the WebClient's DownloadData(…) function for example
            (1) First wrap the method call in an Anonymous delegate.
            (2) Use BeginInvoke(…) and send the wrapped anonymous delegate object as the last parameter along with a callback function name as the first parameter.
            (3) In the callback method retrieve the ar's AsyncState as a Type (typecast) of the anonymous delegate. Along with this object comes EndInvoke(…) as free Gift
            (4) Use EndInvoke(…) to retrieve the synchronous call’s return value in our case it will be the WebClient's DownloadData(…)’s return value.
        */
        try
        {
            Func<Image> load_image_Async = delegate()
            {
                WebClient wc = new WebClient();
                Bitmap bmpLocal = new Bitmap(new MemoryStream(wc.DownloadData(url)));
                wc.Dispose();
                return bmpLocal;
            };

            Action<IAsyncResult> load_Image_call_back = delegate(IAsyncResult ar)
            {
                Func<Image> ss = (Func<Image>)ar.AsyncState;
                Bitmap myBmp = (Bitmap)ss.EndInvoke(ar);

                if (img != null) img.Dispose();
                if (myBmp != null)
                    img = myBmp;
                Invalidate();
                //timer.Enabled = true;
            };
            //load_image_Async.BeginInvoke(callback_load_Image, load_image_Async);             
            load_image_Async.BeginInvoke(new AsyncCallback(load_Image_call_back), load_image_Async);             
        }
        catch (Exception ex)
        {

        }
    }
    protected override void OnPaint(PaintEventArgs e)
    {
        if (img != null)
        {
            Graphics grfx = e.Graphics;
            grfx.DrawImage(img,new Point(0,0));
        }
    }

Correct way of getting Client's IP Addresses from http.Request

This is how I come up with the IP

func ReadUserIP(r *http.Request) string {
    IPAddress := r.Header.Get("X-Real-Ip")
    if IPAddress == "" {
        IPAddress = r.Header.Get("X-Forwarded-For")
    }
    if IPAddress == "" {
        IPAddress = r.RemoteAddr
    }
    return IPAddress
}
  • X-Real-Ip - fetches first true IP (if the requests sits behind multiple NAT sources/load balancer)

  • X-Forwarded-For - if for some reason X-Real-Ip is blank and does not return response, get from X-Forwarded-For

  • Remote Address - last resort (usually won't be reliable as this might be the last ip or if it is a naked http request to server ie no load balancer)

How can I pass variable to ansible playbook in the command line?

Reading the docs I find the section Passing Variables On The Command Line, that gives this example:

ansible-playbook release.yml --extra-vars "version=1.23.45 other_variable=foo"

Others examples demonstrate how to load from JSON string (=1.2) or file (=1.3)

How do I get the file extension of a file in Java?

In this case, use FilenameUtils.getExtension from Apache Commons IO

Here is an example of how to use it (you may specify either full path or just file name):

import org.apache.commons.io.FilenameUtils;

// ...

String ext1 = FilenameUtils.getExtension("/path/to/file/foo.txt"); // returns "txt"
String ext2 = FilenameUtils.getExtension("bar.exe"); // returns "exe"

Maven dependency:

<dependency>
  <groupId>commons-io</groupId>
  <artifactId>commons-io</artifactId>
  <version>2.6</version>
</dependency>

Gradle Groovy DSL

implementation 'commons-io:commons-io:2.6'

Gradle Kotlin DSL

implementation("commons-io:commons-io:2.6")

Others https://search.maven.org/artifact/commons-io/commons-io/2.6/jar

how to get text from textview

split with the + sign like this way

String a = tv.getText().toString();
String aa[];
if(a.contains("+"))
    aa = a.split("+");

now convert the array

Integer.parseInt(aa[0]); // and so on

Get screen width and height in Android

       @Override
        protected void onPostExecute(Drawable result) {
            Log.d("width",""+result.getIntrinsicWidth());
            urlDrawable.setBounds(0, 0, 0+result.getIntrinsicWidth(), 600);

            // change the reference of the current drawable to the result
            // from the HTTP call
            urlDrawable.drawable = result;

            // redraw the image by invalidating the container
            URLImageParser.this.container.invalidate();

            // For ICS
            URLImageParser.this.container.setHeight((400+URLImageParser.this.container.getHeight()
                    + result.getIntrinsicHeight()));

            // Pre ICS`enter code here`
            URLImageParser.this.container.setEllipsize(null);
        }

python NameError: name 'file' is not defined

To solve this error, it is enough to add from google.colab import files in your code!

How to close off a Git Branch?

We request that the developer asking for the pull request state that they would like the branch deleted. Most of the time this is the case. There are times when a branch is needed (e.g. copying the changes to another release branch).

My fingers have memorized our process:

git checkout <feature-branch>
git pull
git checkout <release-branch>
git pull
git merge --no-ff <feature-branch>
git push
git tag -a branch-<feature-branch> -m "Merge <feature-branch> into <release-branch>"
git push --tags
git branch -d <feature-branch>
git push origin :<feature-branch>

A branch is for work. A tag marks a place in time. By tagging each branch merge we can resurrect a branch if that is needed. The branch tags have been used several times to review changes.

git index.lock File exists when I try to commit, but cannot delete the file

On Linux, Unix, Git Bash, or Cygwin, try:

rm -f .git/index.lock

On Windows Command Prompt, try:

del .git\index.lock


For Windows:

  • From a PowerShell console opened as administrator, try

    rm -Force ./.git/index.lock
    
  • If that does not work, you must kill all git.exe processes

    taskkill /F /IM git.exe
    

    SUCCESS: The process "git.exe" with PID 20448 has been terminated.
    SUCCESS: The process "git.exe" with PID 11312 has been terminated.
    SUCCESS: The process "git.exe" with PID 23868 has been terminated.
    SUCCESS: The process "git.exe" with PID 27496 has been terminated.
    SUCCESS: The process "git.exe" with PID 33480 has been terminated.
    SUCCESS: The process "git.exe" with PID 28036 has been terminated. \

    rm -Force ./.git/index.lock
    

How to write to a file without overwriting current contents?

Instead of "w" use "a" (append) mode with open function:

with open("games.txt", "a") as text_file:

jQuery's .on() method combined with the submit event

You need to delegate event to the document level

$(document).on('submit','form.remember',function(){
   // code
});

$('form.remember').on('submit' work same as $('form.remember').submit( but when you use $(document).on('submit','form.remember' then it will also work for the DOM added later.

Localhost : 404 not found

I had the same problem and here is how it worked for me :

1) Open XAMPP control panel.

2)On the right top corner go to config > Service and Port setting and change the port (I did 81 from 80).

3)Open config in Apache just right(next) to Apache admin Option and click on that and select first one (httpd.conf) it will open in the notepad.

4) There you find port listen 80 and replace it with 81 in all place and save the file.

5) Now restart Apache and MYSql

6) Now type following in Browser : http://localhost:81/phpmyadmin/

I hope this works.

Count a list of cells with the same background color

Yes VBA is the way to go.

But, if you don't need to have a cell with formula that auto-counts/updates the number of cells with a particular colour, an alternative is simply to use the 'Find and Replace' function and format the cell to have the appropriate colour fill.

Hitting 'Find All' will give you the total number of cells found at the bottom left of the dialogue box.

enter image description here

This becomes especially useful if your search range is massive. The VBA script will be very slow but the 'Find and Replace' function will still be very quick.

Login with facebook android sdk app crash API 4

The official answer from Facebook (http://developers.facebook.com/bugs/282710765082535):

Mikhail,

The facebook android sdk no longer supports android 1.5 and 1.6. Please upgrade to the next api version.

Good luck with your implementation.

Possible to change where Android Virtual Devices are saved?

Go to the Android tools directory. Edit the android.bat command file. At about the end of the command file, find a line similar to

call %java_exe% -Djava.ext.dirs=%java_ext_dirs% -Dcom.android.sdkmanager.toolsdir="%tools_dir%" -Dcom.android.sdkmanager.workdir="%work_dir%" -jar %jar_path% %*

and replace

call %java_exe%

with

call %java_exe% -Duser.home={your_prefer_dir}

where {your_prefer_dire} is your preferred directory without braces but add doublequotes,

e.g.

call %java_exe% -Duser.home="E:\Program Files (x86)\android-sdk-windows"

Auto-center map with multiple markers in Google Maps API v3

To find the exact center of the map you'll need to translate the lat/lon coordinates into pixel coordinates and then find the pixel center and convert that back into lat/lon coordinates.

You might not notice or mind the drift depending how far north or south of the equator you are. You can see the drift by doing map.setCenter(map.getBounds().getCenter()) inside of a setInterval, the drift will slowly disappear as it approaches the equator.

You can use the following to translate between lat/lon and pixel coordinates. The pixel coordinates are based on a plane of the entire world fully zoomed in, but you can then find the center of that and switch it back into lat/lon.

   var HALF_WORLD_CIRCUMFERENCE = 268435456; // in pixels at zoom level 21
   var WORLD_RADIUS = HALF_WORLD_CIRCUMFERENCE / Math.PI;

   function _latToY ( lat ) {
      var sinLat = Math.sin( _toRadians( lat ) );
      return HALF_WORLD_CIRCUMFERENCE - WORLD_RADIUS * Math.log( ( 1 + sinLat ) / ( 1 - sinLat ) ) / 2;
   }

   function _lonToX ( lon ) {
      return HALF_WORLD_CIRCUMFERENCE + WORLD_RADIUS * _toRadians( lon );
   }

   function _xToLon ( x ) {
      return _toDegrees( ( x - HALF_WORLD_CIRCUMFERENCE ) / WORLD_RADIUS );
   }

   function _yToLat ( y ) {
      return _toDegrees( Math.PI / 2 - 2 * Math.atan( Math.exp( ( y - HALF_WORLD_CIRCUMFERENCE ) / WORLD_RADIUS ) ) );
   }

   function _toRadians ( degrees ) {
      return degrees * Math.PI / 180;
   }

   function _toDegrees ( radians ) {
      return radians * 180 / Math.PI;
   }

VBA vlookup reference in different sheet

The answer your question: the correct way to refer to a different sheet is by appropriately qualifying each Range you use. Please read this explanation and its conclusion, which I guess will give essential information.

The error you are getting is likely due to the sought-for value Sheet2!D2 not being found in the searched range Sheet1!A1:A65536. This may stem from two cases:

  1. The value is actually not present (pointed out by chris nielsen).

  2. You are searching the wrong Range. If the ActiveSheet is Sheet1, then using Range("D2") without qualifying it will be searching for Sheet1!D2, and it will throw the same error even if the sought-for value is present in the correct Range. Code accounting for this (and items below) follows:

    Sub srch()
        Dim ws1 As Worksheet, ws2 As Worksheet
        Dim srchres As Variant
    
        Set ws1 = Worksheets("Sheet1")
        Set ws2 = Worksheets("Sheet2")
    
        On Error Resume Next
        srchres = Application.WorksheetFunction.VLookup(ws2.Range("D2"), ws1.Range("A1:C65536"), 1, False)
        On Error GoTo 0
        If (IsEmpty(srchres)) Then
          ws2.Range("E2").Formula = CVErr(xlErrNA) ' Use whatever you want
        Else
          ws2.Range("E2").Value = srchres
        End If
    End Sub
    

I will point out a few additional notable points:

  1. Catching the error as done by chris nielsen is a good practice, probably mandatory if using Application.WorksheetFunction.VLookup (although it will not suitably handle case 2 above).

  2. This catching is actually performed by the function VLOOKUP as entered in a cell (and, if the sought-for value is not found, the result of the error is presented as #N/A in the result). That is why the first soluton by L42 does not need any extra error handling (it is taken care by =VLOOKUP...).

  3. Using =VLOOKUP... is fundamentally different from Application.WorksheetFunction.VLookup: the first leaves a formula, whose result may change if the cells referenced change; the second writes a fixed value.

  4. Both solutions by L42 qualify Ranges suitably.

  5. You are searching the first column of the range, and returning the value in that same column. Other functions are available for that (although yours works fine).

Load HTML file into WebView

probably this sample could help:

  WebView lWebView = (WebView)findViewById(R.id.webView);
  File lFile = new File(Environment.getExternalStorageDirectory() + "<FOLDER_PATH_TO_FILE>/<FILE_NAME>");
  lWebView.loadUrl("file:///" + lFile.getAbsolutePath());

What are the differences among grep, awk & sed?

I just want to mention a thing, there are many tools can do text processing, e.g. sort, cut, split, join, paste, comm, uniq, column, rev, tac, tr, nl, pr, head, tail.....

they are very handy but you have to learn their options etc.

A lazy way (not the best way) to learn text processing might be: only learn grep , sed and awk. with this three tools, you can solve almost 99% of text processing problems and don't need to memorize above different cmds and options. :)

AND, if you 've learned and used the three, you knew the difference. Actually, the difference here means which tool is good at solving what kind of problem.

a more lazy way might be learning a script language (python, perl or ruby) and do every text processing with it.

MongoDB relationships: embed or reference?

I know this is quite old but if you are looking for the answer to the OP's question on how to return only specified comment, you can use the $ (query) operator like this:

db.question.update({'comments.content': 'xxx'}, {'comments.$': true})

How to upgrade Python version to 3.7?

Try this if you are on ubuntu:

sudo apt-get update
sudo apt-get install build-essential libpq-dev libssl-dev openssl libffi-dev zlib1g-dev
sudo apt-get install python3-pip python3.7-dev
sudo apt-get install python3.7

In case you don't have the repository and so it fires a not-found package you first have to install this:

sudo apt-get install -y software-properties-common
sudo add-apt-repository ppa:deadsnakes/ppa
sudo apt-get update

more info here: http://devopspy.com/python/install-python-3-6-ubuntu-lts/

ng: command not found while creating new project using angular-cli

Same problem here running Windows 10 x64 / NodeJS 6.9.1 / npm 3.10.9.
After installation of Angular CLI via npm:

'ng' command cannot be found

Do the following:

  1. Uninstalled npm with npm uninstall -g npm
  2. Uninstalled NodeJS via control panel / programs and features
  3. Downloaded and ran 'old' NodeJS installer release 6.5.0 from https://nodejs.org/download/release/v6.5.0/ (node-v6.5.0-x64.msi).
  4. After NodeJS 6.5.0 installation completed, open powershell and npm install -g angular-cli
  5. Grab quick coffee
  6. After installation completed, ng worked OK.

HTH

How to export a CSV to Excel using Powershell

Ups, I entirely forgot this question. In the meantime I got a solution.
This Powershell script converts a CSV to XLSX in the background

Gimmicks are

  • Preserves all CSV values as plain text like =B1+B2 or 0000001.
    You don't see #Name or anything like that. No autoformating is done.
  • Automatically chooses the right delimiter (comma or semicolon) according to your regional setting
  • Autofit columns

PowerShell Code

### Set input and output path
$inputCSV = "C:\somefolder\input.csv"
$outputXLSX = "C:\somefolder\output.xlsx"

### Create a new Excel Workbook with one empty sheet
$excel = New-Object -ComObject excel.application 
$workbook = $excel.Workbooks.Add(1)
$worksheet = $workbook.worksheets.Item(1)

### Build the QueryTables.Add command
### QueryTables does the same as when clicking "Data » From Text" in Excel
$TxtConnector = ("TEXT;" + $inputCSV)
$Connector = $worksheet.QueryTables.add($TxtConnector,$worksheet.Range("A1"))
$query = $worksheet.QueryTables.item($Connector.name)

### Set the delimiter (, or ;) according to your regional settings
$query.TextFileOtherDelimiter = $Excel.Application.International(5)

### Set the format to delimited and text for every column
### A trick to create an array of 2s is used with the preceding comma
$query.TextFileParseType  = 1
$query.TextFileColumnDataTypes = ,2 * $worksheet.Cells.Columns.Count
$query.AdjustColumnWidth = 1

### Execute & delete the import query
$query.Refresh()
$query.Delete()

### Save & close the Workbook as XLSX. Change the output extension for Excel 2003
$Workbook.SaveAs($outputXLSX,51)
$excel.Quit()

Python dictionary: are keys() and values() always the same order?

Good references to the docs. Here's how you can guarantee the order regardless of the documentation / implementation:

k, v = zip(*d.iteritems())

Adding a regression line on a ggplot

As I just figured, in case you have a model fitted on multiple linear regression, the above mentioned solution won't work.

You have to create your line manually as a dataframe that contains predicted values for your original dataframe (in your case data).

It would look like this:

# read dataset
df = mtcars

# create multiple linear model
lm_fit <- lm(mpg ~ cyl + hp, data=df)
summary(lm_fit)

# save predictions of the model in the new data frame 
# together with variable you want to plot against
predicted_df <- data.frame(mpg_pred = predict(lm_fit, df), hp=df$hp)

# this is the predicted line of multiple linear regression
ggplot(data = df, aes(x = mpg, y = hp)) + 
  geom_point(color='blue') +
  geom_line(color='red',data = predicted_df, aes(x=mpg_pred, y=hp))

Multiple LR

# this is predicted line comparing only chosen variables
ggplot(data = df, aes(x = mpg, y = hp)) + 
  geom_point(color='blue') +
  geom_smooth(method = "lm", se = FALSE)

Single LR

How to comment out a block of code in Python

The only way you can do this without triple quotes is to add an:

if False:

And then indent all your code. Note that the code will still need to have proper syntax.


Many Python IDEs can add # for you on each selected line, and remove them when un-commenting too. Likewise, if you use vi or Emacs you can create a macro to do this for you for a block of code.

Grant all on a specific schema in the db to a group role in PostgreSQL

My answer is similar to this one on ServerFault.com.

To Be Conservative

If you want to be more conservative than granting "all privileges", you might want to try something more like these.

GRANT SELECT, INSERT, UPDATE, DELETE ON ALL TABLES IN SCHEMA public TO some_user_;
GRANT EXECUTE ON ALL FUNCTIONS IN SCHEMA public TO some_user_;

The use of public there refers to the name of the default schema created for every new database/catalog. Replace with your own name if you created a schema.

Access to the Schema

To access a schema at all, for any action, the user must be granted "usage" rights. Before a user can select, insert, update, or delete, a user must first be granted "usage" to a schema.

You will not notice this requirement when first using Postgres. By default every database has a first schema named public. And every user by default has been automatically been granted "usage" rights to that particular schema. When adding additional schema, then you must explicitly grant usage rights.

GRANT USAGE ON SCHEMA some_schema_ TO some_user_ ;

Excerpt from the Postgres doc:

For schemas, allows access to objects contained in the specified schema (assuming that the objects' own privilege requirements are also met). Essentially this allows the grantee to "look up" objects within the schema. Without this permission, it is still possible to see the object names, e.g. by querying the system tables. Also, after revoking this permission, existing backends might have statements that have previously performed this lookup, so this is not a completely secure way to prevent object access.

For more discussion see the Question, What GRANT USAGE ON SCHEMA exactly do?. Pay special attention to the Answer by Postgres expert Craig Ringer.

Existing Objects Versus Future

These commands only affect existing objects. Tables and such you create in the future get default privileges until you re-execute those lines above. See the other answer by Erwin Brandstetter to change the defaults thereby affecting future objects.

Iterating through a List Object in JSP

change the code to the following

<%! List eList = (ArrayList)session.getAttribute("empList");%>
....
<table>
    <%
    for(int i=0; i<eList.length;i++){%>
        <tr>
            <td><%= ((Employee)eList[i]).getEid() %></td>
            <td><%= ((Employee)eList[i]).getEname() %></td>  
        </tr>
      <%}%>
</table>

res.sendFile absolute path

res.sendFile( __dirname + "/public/" + "index1.html" );

where __dirname will manage the name of the directory that the currently executing script ( server.js ) resides in.

Is there an XSL "contains" directive?

It should be something like...

<xsl:if test="contains($hhref, '1234')">

(not tested)

See w3schools (always a good reference BTW)

System.Net.WebException: The remote name could not be resolved:

Open the hosts file located at : **C:\windows\system32\drivers\etc**.

Hosts file is for what?

Add the following at end of this file :

YourServerIP YourDNS

Example:

198.168.1.1 maps.google.com

How to return a value from a Form in C#?

delegates are the best option for sending data from one form to another.

public partial class frmImportContact : Form
{
     public delegate void callback_data(string someData);
    public event callback_data getData_CallBack;

    private void button_Click(object sender, EventArgs e)
    {
      string myData = "Top Secret Data To Share";
      getData_CallBack(myData);
    }

}

public partial class frmHireQuote : Form
{
     private void Button_Click(object sender, EventArgs e)
    {

      frmImportContact obj = new frmImportContact();
      obj.getData_CallBack += getData;
    }

    private void getData(string someData)
    {
         MessageBox.Show("someData");
    }
}

Set background image according to screen resolution

I've had this same issue but have now found the resolution for it.

The trick is to create a wallpaper image of 1920*1200. When you then apply this wallpaper to the different machines, Windows 7 automatically resizes for best fit.

Hope this helps you all

Format datetime in asp.net mvc 4

Client validation issues can occur because of MVC bug (even in MVC 5) in jquery.validate.unobtrusive.min.js which does not accept date/datetime format in any way. Unfortunately you have to solve it manually.

My finally working solution:

$(function () {
    $.validator.methods.date = function (value, element) {
        return this.optional(element) || moment(value, "DD.MM.YYYY", true).isValid();
    }
});

You have to include before:

@Scripts.Render("~/Scripts/jquery-3.1.1.js")
@Scripts.Render("~/Scripts/jquery.validate.min.js")
@Scripts.Render("~/Scripts/jquery.validate.unobtrusive.min.js")
@Scripts.Render("~/Scripts/moment.js")

You can install moment.js using:

Install-Package Moment.js

PLS-00103: Encountered the symbol "CREATE"

At line 5 there is a / missing.

There is a good answer on the differences between ; and / here.

Basically, when running a CREATE block via script, you need to use / to let SQLPlus know when the block ends, since a PL/SQL block can contain many instances of ;.

Clone private git repo with dockerfile

My key was password protected which was causing the problem, a working file is now listed below (for help of future googlers)

FROM ubuntu

MAINTAINER Luke Crooks "[email protected]"

# Update aptitude with new repo
RUN apt-get update

# Install software 
RUN apt-get install -y git
# Make ssh dir
RUN mkdir /root/.ssh/

# Copy over private key, and set permissions
# Warning! Anyone who gets their hands on this image will be able
# to retrieve this private key file from the corresponding image layer
ADD id_rsa /root/.ssh/id_rsa

# Create known_hosts
RUN touch /root/.ssh/known_hosts
# Add bitbuckets key
RUN ssh-keyscan bitbucket.org >> /root/.ssh/known_hosts

# Clone the conf files into the docker container
RUN git clone [email protected]:User/repo.git

How to check if running as root in a bash script

In this answer, let it be clear, I presume the reader is able to read bash and POSIX shell scripts like dash.

I believe there is not much to explain here since the highly voted answers do a good job of explaining much of it.

Yet, if there is anything to explain further, don't hesitate to comment, I will do my best filling the gaps.


Optimized all-round solution for performance and reliability; all shells compatible

New solution:

# bool function to test if the user is root or not
is_user_root () { [ ${EUID:-$(id -u)} -eq 0 ]; }

Benchmark (save to file is_user_root__benchmark)

#+------------------------------------------------------------------------------+
#|                           is_user_root() benchmark                           |
#|                  "Bash is fast while Dash is slow in this"                   |
#|                          Language: POSIX shell script                        |
#|                        Copyright: 2020 Vlastimil Burian                      |
#|                      M@il: info[..]vlastimilburian[..]cz                     |
#|                               License: GPL 3.0                               |
#|                                 Version: 1.1                                 |
#+------------------------------------------------------------------------------+

readonly iterations=10000

# intentionally, the file does not have executable bit, nor it has no shebang
# to use it, just call the file directly with your shell interpreter like:

# bash is_user_root__benchmark
# dash is_user_root__benchmark

is_user_root () { [ ${EUID:-$(id -u)} -eq 0 ]; }

print_time   () { date +"%T.%2N"; }
print_start  () { printf '%s' 'Start  : '; print_time; }
print_finish () { printf '%s' 'Finish : '; print_time; }

printf '%s\n' '___is_user_root()___'; print_start
                   
i=1; while [ $i -lt $iterations ]; do
    is_user_root
    i=$((i + 1))
done; print_finish

Examples of use and duration:

$ dash is_user_root__benchmark 
___is_user_root()___
Start  : 03:14:04.81
Finish : 03:14:13.29

$ bash is_user_root__benchmark 
___is_user_root()___
Start  : 03:16:22.90
Finish : 03:16:23.08


Explanation

Since it is multitude times faster to read the $EUID standard bash variable, the effective user ID number, than executing id -u command to POSIX-ly find the user ID, this solution combines both into a nicely packed function. If, and only if, the $EUID is for any reason not available, the id -u command will get executed, ensuring we get the proper return value no matter the circumstances.


Why I post this solution after so many years the OP has asked

Well, if I see correctly, there does seem to be a missing piece of code above.

You see, there are many variables which have to be taken into account, and one of them is combining performance and reliability.


Portable POSIX solution + Example of usage of the above function

#!/bin/sh

# bool function to test if the user is root or not (POSIX only)
is_user_root() { [ "$(id -u)" -eq 0 ]; }

if is_user_root; then
    echo 'You are the almighty root!'
    exit 0 # implicit, here it serves the purpose to be explicit for the reader
else
    echo 'You are just an ordinary user.' >&2
    exit 1
fi

Conclusion

As much as you possibly don't like it, the Unix / Linux environment has diversified a lot. Meaning there are people who like bash so much, they don't even think of portability (POSIX shells). Others like me prefer the POSIX shells. It is nowadays a matter of personal choice and needs.

Difference between volatile and synchronized in Java

tl;dr:

There are 3 main issues with multithreading:

1) Race Conditions

2) Caching / stale memory

3) Complier and CPU optimisations

volatile can solve 2 & 3, but can't solve 1. synchronized/explicit locks can solve 1, 2 & 3.

Elaboration:

1) Consider this thread unsafe code:

x++;

While it may look like one operation, it's actually 3: reading the current value of x from memory, adding 1 to it, and saving it back to memory. If few threads try to do it at the same time, the result of the operation is undefined. If x originally was 1, after 2 threads operating the code it may be 2 and it may be 3, depending on which thread completed which part of the operation before control was transferred to the other thread. This is a form of race condition.

Using synchronized on a block of code makes it atomic - meaning it make it as if the 3 operations happen at once, and there's no way for another thread to come in the middle and interfere. So if x was 1, and 2 threads try to preform x++ we know in the end it will be equal to 3. So it solves the race condition problem.

synchronized (this) {
   x++; // no problem now
}

Marking x as volatile does not make x++; atomic, so it doesn't solve this problem.

2) In addition, threads have their own context - i.e. they can cache values from main memory. That means that a few threads can have copies of a variable, but they operate on their working copy without sharing the new state of the variable among other threads.

Consider that on one thread, x = 10;. And somewhat later, in another thread, x = 20;. The change in value of x might not appear in the first thread, because the other thread has saved the new value to its working memory, but hasn't copied it to the main memory. Or that it did copy it to the main memory, but the first thread hasn't updated its working copy. So if now the first thread checks if (x == 20) the answer will be false.

Marking a variable as volatile basically tells all threads to do read and write operations on main memory only. synchronized tells every thread to go update their value from main memory when they enter the block, and flush the result back to main memory when they exit the block.

Note that unlike data races, stale memory is not so easy to (re)produce, as flushes to main memory occur anyway.

3) The complier and CPU can (without any form of synchronization between threads) treat all code as single threaded. Meaning it can look at some code, that is very meaningful in a multithreading aspect, and treat it as if it’s single threaded, where it’s not so meaningful. So it can look at a code and decide, in sake of optimisation, to reorder it, or even remove parts of it completely, if it doesn’t know that this code is designed to work on multiple threads.

Consider the following code:

boolean b = false;
int x = 10;

void threadA() {
    x = 20;
    b = true;
}

void threadB() {
    if (b) {
        System.out.println(x);
    }
}

You would think that threadB could only print 20 (or not print anything at all if threadB if-check is executed before setting b to true), as b is set to true only after x is set to 20, but the compiler/CPU might decide to reorder threadA, in that case threadB could also print 10. Marking b as volatile ensures that it won’t be reordered (or discarded in certain cases). Which mean threadB could only print 20 (or nothing at all). Marking the methods as syncrhonized will achieve the same result. Also marking a variable as volatile only ensures that it won’t get reordered, but everything before/after it can still be reordered, so synchronization can be more suited in some scenarios.

Note that before Java 5 New Memory Model, volatile didn’t solve this issue.

@JsonProperty annotation on field as well as getter/setter

My observations based on a few tests has been that whichever name differs from the property name is one which takes effect:

For eg. consider a slight modification of your case:

@JsonProperty("fileName")
private String fileName;

@JsonProperty("fileName")
public String getFileName()
{
    return fileName;
}

@JsonProperty("fileName1")
public void setFileName(String fileName)
{
    this.fileName = fileName;
}

Both fileName field, and method getFileName, have the correct property name of fileName and setFileName has a different one fileName1, in this case Jackson will look for a fileName1 attribute in json at the point of deserialization and will create a attribute called fileName1 at the point of serialization.

Now, coming to your case, where all the three @JsonProperty differ from the default propertyname of fileName, it would just pick one of them as the attribute(FILENAME), and had any on of the three differed, it would have thrown an exception:

java.lang.IllegalStateException: Conflicting property name definitions

How to convert base64 string to image?

You can try using open-cv to save the file since it helps with image type conversions internally. The sample code:

import cv2
import numpy as np

def save(encoded_data, filename):
    nparr = np.fromstring(encoded_data.decode('base64'), np.uint8)
    img = cv2.imdecode(nparr, cv2.IMREAD_ANYCOLOR)
    return cv2.imwrite(filename, img)

Then somewhere in your code you can use it like this:

save(base_64_string, 'testfile.png');
save(base_64_string, 'testfile.jpg');
save(base_64_string, 'testfile.bmp');

CSS align images and text on same line

In this case you can use display:inline or inline-block.

Example:

_x000D_
_x000D_
img.likeordisklike {display:inline;vertical-align:middle;  }_x000D_
h4.liketext { color:#F00; display:inline;vertical-align:top;padding-left:10px; }
_x000D_
<img class='likeordislike' src='design/like.png'/><h4 class='liketext'>$likes</h4>_x000D_
<img class='likeordislike' src='design/dislike.png'/><h4 class='liketext'>$dislikes</h4>
_x000D_
_x000D_
_x000D_

Don't use float:left because again need to write one more clear line and its old method also..

MySQL stored procedure return value

Update your SP and handle exception in it using declare handler with get diagnostics so that you will know if there is an exception. e.g.

CREATE DEFINER=`root`@`localhost` PROCEDURE `validar_egreso`(
IN codigo_producto VARCHAR(100),
IN cantidad INT,
OUT valido INT(11)
)
BEGIN
DECLARE EXIT HANDLER FOR SQLEXCEPTION
BEGIN
    GET DIAGNOSTICS CONDITION 1
    @p1 = RETURNED_SQLSTATE, @p2 = MESSAGE_TEXT;
    SELECT @p1, @p2;
END
DECLARE resta INT(11);
SET resta = 0;

SELECT (s.stock - cantidad) INTO resta
FROM stock AS s
WHERE codigo_producto = s.codigo;

IF (resta > s.stock_minimo) THEN
    SET valido = 1;
ELSE
    SET valido = -1;
END IF;
SELECT valido;
END

Add new line in text file with Windows batch file

I believe you are using the

echo Text >> Example.txt 

function?

If so the answer would be simply adding a "." (Dot) directly after the echo with nothing else there.

Example:

echo Blah
echo Blah 2
echo. #New line is added
echo Next Blah

Python class inherits object

Is there any reason for a class declaration to inherit from object?

In Python 3, apart from compatibility between Python 2 and 3, no reason. In Python 2, many reasons.


Python 2.x story:

In Python 2.x (from 2.2 onwards) there's two styles of classes depending on the presence or absence of object as a base-class:

  1. "classic" style classes: they don't have object as a base class:

    >>> class ClassicSpam:      # no base class
    ...     pass
    >>> ClassicSpam.__bases__
    ()
    
  2. "new" style classes: they have, directly or indirectly (e.g inherit from a built-in type), object as a base class:

    >>> class NewSpam(object):           # directly inherit from object
    ...    pass
    >>> NewSpam.__bases__
    (<type 'object'>,)
    >>> class IntSpam(int):              # indirectly inherit from object...
    ...    pass
    >>> IntSpam.__bases__
    (<type 'int'>,) 
    >>> IntSpam.__bases__[0].__bases__   # ... because int inherits from object  
    (<type 'object'>,)
    

Without a doubt, when writing a class you'll always want to go for new-style classes. The perks of doing so are numerous, to list some of them:

  • Support for descriptors. Specifically, the following constructs are made possible with descriptors:

    1. classmethod: A method that receives the class as an implicit argument instead of the instance.
    2. staticmethod: A method that does not receive the implicit argument self as a first argument.
    3. properties with property: Create functions for managing the getting, setting and deleting of an attribute.
    4. __slots__: Saves memory consumptions of a class and also results in faster attribute access. Of course, it does impose limitations.
  • The __new__ static method: lets you customize how new class instances are created.

  • Method resolution order (MRO): in what order the base classes of a class will be searched when trying to resolve which method to call.

  • Related to MRO, super calls. Also see, super() considered super.

If you don't inherit from object, forget these. A more exhaustive description of the previous bullet points along with other perks of "new" style classes can be found here.

One of the downsides of new-style classes is that the class itself is more memory demanding. Unless you're creating many class objects, though, I doubt this would be an issue and it's a negative sinking in a sea of positives.


Python 3.x story:

In Python 3, things are simplified. Only new-style classes exist (referred to plainly as classes) so, the only difference in adding object is requiring you to type in 8 more characters. This:

class ClassicSpam:
    pass

is completely equivalent (apart from their name :-) to this:

class NewSpam(object):
     pass

and to this:

class Spam():
    pass

All have object in their __bases__.

>>> [object in cls.__bases__ for cls in {Spam, NewSpam, ClassicSpam}]
[True, True, True]

So, what should you do?

In Python 2: always inherit from object explicitly. Get the perks.

In Python 3: inherit from object if you are writing code that tries to be Python agnostic, that is, it needs to work both in Python 2 and in Python 3. Otherwise don't, it really makes no difference since Python inserts it for you behind the scenes.

How to create a POJO?

According to Martin Fowler

The term was coined while Rebecca Parsons, Josh MacKenzie and I were preparing for a talk at a conference in September 2000. In the talk, we were pointing out the many benefits of encoding business logic into regular java objects rather than using Entity Beans. We wondered why people were so against using regular objects in their systems and concluded that it was because simple objects lacked a fancy name. So we gave them one, and it’s caught on very nicely.

Generally, a POJO is not bound to any restriction and any Java object can be called a POJO but there are some directions. A well-defined POJO should follow below directions.

  1. Each variable in a POJO should be declared as private.
  2. Default constructor should be overridden with public accessibility.
  3. Each variable should have its Setter-Getter method with public accessibility.
  4. Generally POJO should override equals(), hashCode() and toString() methods of Object (but it's not mandatory).
  5. Overriding compare() method of Comparable interface used for sorting (Preferable but not mandatory).

And according to Java Language Specification, a POJO should not have to

  1. Extend pre-specified classes
  2. Implement pre-specified interfaces
  3. Contain pre-specified annotations

However, developers and frameworks describe a POJO still requires the use prespecified annotations to implement features like persistence, declarative transaction management etc. So the idea is that if the object was a POJO before any annotations were added would return to POJO status if the annotations are removed then it can still be considered a POJO.

A JavaBean is a special kind of POJO that is Serializable, has a no-argument constructor, and allows access to properties using getter and setter methods that follow a simple naming convention.

Read more on Plain Old Java Object (POJO) Explained.

How to Convert Int to Unsigned Byte and Back

Handling bytes and unsigned integers with BigInteger:

byte[] b = ...                    // your integer in big-endian
BigInteger ui = new BigInteger(b) // let BigInteger do the work
int i = ui.intValue()             // unsigned value assigned to i

In PowerShell, how do I test whether or not a specific variable exists in global scope?

You can assign a variable to the return value of Get-Variable then check to see if it is null:

$variable = Get-Variable -Name foo -Scope Global -ErrorAction SilentlyContinue

if ($variable -eq $null)
{
    Write-Host "foo does not exist"
}

# else...

Just be aware that the variable has to be assigned to something for it to "exist". For example:

$global:foo = $null

$variable = Get-Variable -Name foo -Scope Global -ErrorAction SilentlyContinue

if ($variable -eq $null)
{
    Write-Host "foo does not exist"
}
else
{
    Write-Host "foo exists"
}

$global:bar

$variable = Get-Variable -Name bar -Scope Global -ErrorAction SilentlyContinue

if ($variable -eq $null)
{
    Write-Host "bar does not exist"
}
else
{
    Write-Host "bar exists"
}

Output:

foo exists
bar does not exist

Javascript: open new page in same window

I'd take that a slightly different way if I were you. Change the text link when the page loads, not on the click. I'll give the example in jQuery, but it could easily be done in vanilla javascript (though, jQuery is nicer)

$(function() {
    $('a[href$="url="]')    // all links whose href ends in "url="
        .each(function(i, el) {
            this.href += escape(document.location.href);
        })
    ;
});

and write your HTML like this:

<a href="http://example.com/submit.php?url=">...</a>

the benefits of this are that people can see what they're clicking on (the href is already set), and it removes the javascript from your HTML.

All this said, it looks like you're using PHP... why not add it in server-side?

Which ORM should I use for Node.js and MySQL?

First off, please note that I haven't used either of them (but have used Node.js).

Both libraries are documented quite well and have a stable API. However, persistence.js seems to be used in more projects. I don't know if all of them still use it, though.

The developer of sequelize sometimes blogs about it at blog.depold.com. When you'd like to use primary keys as foreign keys, you'll need the patch that's described in this blog post. If you'd like help for persistence.js there is a google group devoted to it.

From the examples I gather that sequelize is a bit more JavaScript-like (more sugar) than persistance.js but has support for fewer datastores (only MySQL, while persistance.js can even use in-browser stores).

I think that sequelize might be the way to go for you, as you only need MySQL support. However, if you need some convenient features (for instance search) or want to use a different database later on you'd need to use persistence.js.

Change bootstrap navbar collapse breakpoint without using LESS

In addition to @Skely answer, to make dropdown menus inside the navbar work, also add their classes to be overriden. Final code bellow:

    @media (min-width: 768px) and (max-width: 991px) {
        .navbar-nav .open .dropdown-menu {
            position: static;
            float: none;
            width: auto;
            margin-top: 0;
            background-color: transparent;
            border: 0;
            -webkit-box-shadow: none;
            box-shadow: none;
        }
        .navbar-nav .open .dropdown-menu > li > a {
            line-height: 20px;
        }
        .navbar-nav .open .dropdown-menu > li > a,
        .navbar-nav .open .dropdown-menu .dropdown-header {
            padding: 5px 15px 5px 25px;
        }
        .dropdown-menu > li > a {
            display: block;
            padding: 3px 20px;
            clear: both;
            font-weight: normal;
            line-height: 1.42857143;
            color: #333;
            white-space: nowrap;
        }
        .navbar-header {
            float: none;
        }
        .navbar-toggle {
            display: block;
        }
        .navbar-collapse {
            border-top: 1px solid transparent;
            box-shadow: inset 0 1px 0 rgba(255,255,255,0.1);
        }
        .navbar-collapse.collapse {
            display: none!important;
        }
        .navbar-nav {
            float: none!important;
            /*margin: 7.5px -15px;*/
            margin: 7.5px 50px 7.5px -15px
        }
        .navbar-nav>li {
            float: none;
        }
        .navbar-nav>li>a {
            padding-top: 10px;
            padding-bottom: 10px;
        }
        .navbar-text {
            float: none;
            margin: 15px 0;
        }
        /* since 3.1.0 */
        .navbar-collapse.collapse.in { 
            display: block!important;
        }
        .collapsing {
            overflow: hidden!important;
        }
    }

demo code

Group by month and year in MySQL

SELECT YEAR(t.summaryDateTime) as yr, GROUP_CONCAT(MONTHNAME(t.summaryDateTime)) AS month 
FROM trading_summary t GROUP BY yr

Still you would need to process it in external script to get exactly the structure you're looking for.

For example use PHP's explode to create an array from list of month names and then use json_encode()

Custom date format with jQuery validation plugin

Is Easy, Example: Valid for HTML5 automatic type="date".

<script type="text/javascript" src="//ajax.aspnetcdn.com/ajax/jquery.validate/1.14.0/jquery.validate.min.js"></script>
<script type="text/javascript" src="//ajax.aspnetcdn.com/ajax/jquery.validate/1.14.0/additional-methods.min.js"></script>
<script type="text/javascript" src="//ajax.aspnetcdn.com/ajax/jquery.validate/1.14.0/localization/messages_es.js"></script>

$(function () {

        // Overload method default "date" jquery.validate.min.js
        $.validator.addMethod(
            "date",
            function(value, element) {
                var dateReg = /^\d{2}([./-])\d{2}\1\d{4}$/;
                return value.match(dateReg);
            },
            "Invalid date"
        );

     // Form Demo jquery.validate.min.js
     $('#form-datos').validate({
        submitHandler: function(form) {
            form.submit();
        }
    });

});

How to solve this java.lang.NoClassDefFoundError: org/apache/commons/io/output/DeferredFileOutputStream?

Solution

By default, Struts is using Apache “commons-io.jar” for its file upload process. To fix it, you have to include this library into your project dependency library folder.

  1. Get Directly

Get “commons-io.jar” from official website – http://commons.apache.org/io/

  1. Get From Maven

The prefer way is get the “commons-io.jar” from Maven repository

File : pom.xml

  <dependency>
    <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
    <version>1.4</version>
  </dependency>

How to verify if nginx is running or not?

If you are on mac machine and had installed nginx using

brew install nginx

then

brew services list

is the command for you. This will return a list of services installed via brew and their corresponding status.

enter image description here

C# IPAddress from string

You've probably miss-typed something above that bit of code or created your own class called IPAddress. If you're using the .net one, that function should be available.

Have you tried using System.Net.IPAddress just in case?

System.Net.IPAddress ipaddress = System.Net.IPAddress.Parse("127.0.0.1");  //127.0.0.1 as an example

The docs on Microsoft's site have a complete example which works fine on my machine.

C++ float array initialization

No, it sets all members/elements that haven't been explicitly set to their default-initialisation value, which is zero for numeric types.

Android: long click on a button -> perform actions

To get both functions working for a clickable image that will respond to both short and long clicks, I tried the following that seems to work perfectly:

    image = (ImageView) findViewById(R.id.imageViewCompass);
    image.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            shortclick();
        }
     });

    image.setOnLongClickListener(new View.OnLongClickListener() {
    public boolean onLongClick(View v) {
        longclick();
        return true;
    }
});

//Then the functions that are called:

 public void shortclick()
{
 Toast.makeText(this, "Why did you do that? That hurts!!!", Toast.LENGTH_LONG).show();

}

 public void longclick()
{
 Toast.makeText(this, "Why did you do that? That REALLY hurts!!!", Toast.LENGTH_LONG).show();

}

It seems that the easy way of declaring the item in XML as clickable and then defining a function to call on the click only applies to short clicks - you must have a listener to differentiate between short and long clicks.

Cannot resolve method 'getSupportFragmentManager ( )' inside Fragment

getFragmentManager()

just try this.it worked for my case

Stretch and scale a CSS image in the background - with CSS only

I use this, and it works with all browsers:

<html>
    <head>
        <title>Stretched Background Image</title>
        <style type="text/css">
            /* Remove margins from the 'html' and 'body' tags, and ensure the page takes up full screen height. */
            html, body {height:100%; margin:0; padding:0;}

            /* Set the position and dimensions of the background image. */
            #page-background {position:fixed; top:0; left:0; width:100%; height:100%;}

            /* Specify the position and layering for the content that needs to appear in front of the background image. Must have a higher z-index value than the background image. Also add some padding to compensate for removing the margin from the 'html' and 'body' tags. */
            #content {position:relative; z-index:1; padding:10px;}
        </style>
        <!-- The above code doesn't work in Internet Explorer 6. To address this, we use a conditional comment to specify an alternative style sheet for IE 6. -->
        <!--[if IE 6]>
        <style type="text/css">
            html {overflow-y:hidden;}
            body {overflow-y:auto;}
            #page-background {position:absolute; z-index:-1;}
            #content {position:static;padding:10px;}
        </style>
        <![endif]-->
    </head>
    <body>
        <div id="page-background"><img src="http://www.quackit.com/pix/milford_sound/milford_sound.jpg" width="100%" height="100%" alt="Smile"></div>
        <div id="content">
            <h2>Stretch that Background Image!</h2>
            <p>This text appears in front of the background image. This is because we've used CSS to layer the content in front of the background image. The background image will stretch to fit your browser window. You can see the image grow and shrink as you resize your browser.</p>
            <p>Go on, try it - resize your browser!</p>
        </div>
    </body>
</html>

How do I select a sibling element using jQuery?

If you want to select a specific sibling:

var $sibling = $(this).siblings('.bidbutton')[index];

where 'index' is the index of the specific sibling within the parent container.

Read binary file as string in Ruby

Ruby have binary reading

data = IO.binread(path/filaname)

or if less than Ruby 1.9.2

data = IO.read(path/file)

Parse JSON from HttpURLConnection object

In addition, if you wish to parse your object in case of http error (400-5** codes), You can use the following code: (just replace 'getInputStream' with 'getErrorStream':

    BufferedReader rd = new BufferedReader(
            new InputStreamReader(conn.getErrorStream()));
    StringBuilder sb = new StringBuilder();
    String line;
    while ((line = rd.readLine()) != null) {
        sb.append(line);
    }
    rd.close();
    return sb.toString();

How to convert an integer to a character array using C

The easy way is by using sprintf. I know others have suggested itoa, but a) it isn't part of the standard library, and b) sprintf gives you formatting options that itoa doesn't.

How to upload multiple files using PHP, jQuery and AJAX

Finally I have found the solution by using the following code:

$('body').on('click', '#upload', function(e){
        e.preventDefault();
        var formData = new FormData($(this).parents('form')[0]);

        $.ajax({
            url: 'upload.php',
            type: 'POST',
            xhr: function() {
                var myXhr = $.ajaxSettings.xhr();
                return myXhr;
            },
            success: function (data) {
                alert("Data Uploaded: "+data);
            },
            data: formData,
            cache: false,
            contentType: false,
            processData: false
        });
        return false;
});

What is a handle in C++?

This appears in the context of the Handle-Body-Idiom, also called Pimpl idiom. It allows one to keep the ABI (binary interface) of a library the same, by keeping actual data into another class object, which is merely referenced by a pointer held in an "handle" object, consisting of functions that delegate to that class "Body".

It's also useful to enable constant time and exception safe swap of two objects. For this, merely the pointer pointing to the body object has to be swapped.

Find a value anywhere in a database

For Development purpose you can just export the required tables data into a single HTML and make a direct search on it.

Increase Tomcat memory settings

try setting this

CATALINA_OPTS="-Djava.awt.headless=true -Dfile.encoding=UTF-8 
-server -Xms1536m -Xmx1536m
-XX:NewSize=256m -XX:MaxNewSize=256m -XX:PermSize=256m 
-XX:MaxPermSize=256m -XX:+DisableExplicitGC"

in {$tomcat-folder}\bin\setenv.sh (create it if necessary).

See http://www.mkyong.com/tomcat/tomcat-javalangoutofmemoryerror-permgen-space/ for more details.

How to Get the HTTP Post data in C#?

You are missing a step. You need to log / store the values on your server (mailgun is a client). Then you need to retrieve those values on your server (your pc with your web browser will be a client). These will be two totally different aspx files (or the same one with different parameters).

aspx page 1 (the one that mailgun has):

var val = Request.Form["recipient"];
var file = new File(filename);
file.write(val);
close(file);

aspx page 2:

var contents = "";
if (File.exists(filename))
  var file = File.open(filename);
  contents = file.readtoend();
  file.close()

Request.write(contents);

What are passive event listeners?

Passive event listeners are an emerging web standard, new feature shipped in Chrome 51 that provide a major potential boost to scroll performance. Chrome Release Notes.

It enables developers to opt-in to better scroll performance by eliminating the need for scrolling to block on touch and wheel event listeners.

Problem: All modern browsers have a threaded scrolling feature to permit scrolling to run smoothly even when expensive JavaScript is running, but this optimization is partially defeated by the need to wait for the results of any touchstart and touchmove handlers, which may prevent the scroll entirely by calling preventDefault() on the event.

Solution: {passive: true}

By marking a touch or wheel listener as passive, the developer is promising the handler won't call preventDefault to disable scrolling. This frees the browser up to respond to scrolling immediately without waiting for JavaScript, thus ensuring a reliably smooth scrolling experience for the user.

document.addEventListener("touchstart", function(e) {
    console.log(e.defaultPrevented);  // will be false
    e.preventDefault();   // does nothing since the listener is passive
    console.log(e.defaultPrevented);  // still false
}, Modernizr.passiveeventlisteners ? {passive: true} : false);

DOM Spec , Demo Video , Explainer Doc

How do I run a Python program in the Command Prompt in Windows 7?

first make sure u enter the path environmental variable

C:\ path %path%;C:\Python27 press Enter

C:\Python27>python file_name press Enter

MySQL: is a SELECT statement case sensitive?

Marc B's answer is mostly correct.

If you are using a nonbinary string (CHAR, VARCHAR, TEXT), comparisons are case-insensitive, per the default collation.

If you are using a binary string (BINARY, VARBINARY, BLOB), comparisons are case-sensitive, so you'll need to use LOWER as described in other answers.

If you are not using the default collation and you are using a nonbinary string, case sensitivity is decided by the chosen collation.

Source: https://dev.mysql.com/doc/refman/8.0/en/case-sensitivity.html. Read closely. Some others have mistaken it to say that comparisons are necessarily case-sensitive or insensitive. This is not the case.

Deny direct access to all .php files except index.php

Allow only 2 ip , all other will block

Order Deny,Allow
Deny from all
Allow from 173.11.227.73 108.222.245.179

Does the target directory for a git clone have to match the repo name?

Yes, it is possible:

git clone https://github.com/pitosalas/st3_packages Packages 

You can specify the local root directory when using git clone.

<directory> 

The name of a new directory to clone into.
The "humanish" part of the source repository is used if no directory is explicitly given (repo for /path/to/repo.git and foo for host.xz:foo/.git).
Cloning into an existing directory is only allowed if the directory is empty.


As Chris comments, you can then rename that top directory.
Git only cares about the .git within said top folder, which you can get with various commands:

git rev-parse --show-toplevel git rev-parse --git-dir 

How can I check if given int exists in array?

You almost never have to write your own loops in C++. Here, you can use std::find.

const int toFind = 42;
int* found = std::find (myArray, std::end (myArray), toFind);
if (found != std::end (myArray))
{
  std::cout << "Found.\n"
}
else
{
  std::cout << "Not found.\n";
}

std::end requires C++11. Without it, you can find the number of elements in the array with:

const size_t numElements = sizeof (myArray) / sizeof (myArray[0]);

...and the end with:

int* end = myArray + numElements;

How to return rows from left table not found in right table?

I also like to use NOT EXISTS. When it comes to performance if index correctly it should perform the same as a LEFT JOIN or better. Plus its easier to read.

SELECT Column1
FROM TableA a
WHERE NOT EXISTS ( SELECT Column1
                   FROM Tableb b
                   WHERE a.Column1 = b.Column1
                 )

How to change visibility of layout programmatically

Have a look at View.setVisibility(View.GONE / View.VISIBLE / View.INVISIBLE).

From the API docs:

public void setVisibility(int visibility)

    Since: API Level 1

    Set the enabled state of this view.
    Related XML Attributes: android:visibility

Parameters:
visibility     One of VISIBLE, INVISIBLE, or GONE.

Note that LinearLayout is a ViewGroup which in turn is a View. That is, you may very well call, for instance, myLinearLayout.setVisibility(View.VISIBLE).

This makes sense. If you have any experience with AWT/Swing, you'll recognize it from the relation between Container and Component. (A Container is a Component.)

Msg 102, Level 15, State 1, Line 1 Incorrect syntax near ' '

For the OP's command:

select compid,2, convert(datetime, '01/01/' + CONVERT(char(4),cal_yr) ,101) ,0,  Update_dt, th1, th2, th3_pc , Update_id, Update_dt,1
from  #tmp_CTF** 

I get this error:

Msg 102, Level 15, State 1, Line 2
Incorrect syntax near '*'.

when debugging something like this split the long line up so you'll get a better row number:

select compid
,2
, convert(datetime
, '01/01/' 
+ CONVERT(char(4)
,cal_yr) 
,101) 
,0
,  Update_dt
, th1
, th2
, th3_pc 
, Update_id
, Update_dt
,1
from  #tmp_CTF** 

this now results in:

Msg 102, Level 15, State 1, Line 16
Incorrect syntax near '*'.

which is probably just from the OP not putting the entire command in the question, or use [ ] braces to signify the table name:

from [#tmp_CTF**]

if that is the table name.

How to disable <br> tags inside <div> by css?

I used it like this:

@media (max-width: 450px) {
  br {
    display: none;
  }
}

nb: media query via Foundation nb2: this is useful if one of the editor intend to use
tags in his/her copy and you need to deal with it specifically under some conditions—on mobile for example.

How can I generate an apk that can run without server with react-native?

for React Native 0.49 and over

you should go to project directory on terminal and run that command

1 - mkdir android/app/src/main/assets
2 - react-native bundle --platform android --dev false --entry-file index.js --bundle-output android/app/src/main/assets/index.android.bundle --assets-dest android/app/src/main/res

if under 0.49

  1 - mkdir android/app/src/main/assets
  2 - react-native bundle --platform android --dev false --entry-file index.android.js --bundle-output android/app/src/main/assets/index.android.bundle --assets-dest android/app/src/main/res

Then Use android studio to open the 'android' folder in you react native app directory, it will ask to upgrade gradle and some other stuff. go to build-> Generate signed APK and follow the instructions from there. That okey.

Timestamp with a millisecond precision: How to save them in MySQL

CREATE TABLE fractest( c1 TIME(3), c2 DATETIME(3), c3 TIMESTAMP(3) );

INSERT INTO fractest VALUES
('17:51:04.777', '2018-09-08 17:51:04.777', '2018-09-08 17:51:04.777');

Pandas convert string to int

You need add parameter errors='coerce' to function to_numeric:

ID = pd.to_numeric(ID, errors='coerce')

If ID is column:

df.ID = pd.to_numeric(df.ID, errors='coerce')

but non numeric are converted to NaN, so all values are float.

For int need convert NaN to some value e.g. 0 and then cast to int:

df.ID = pd.to_numeric(df.ID, errors='coerce').fillna(0).astype(np.int64)

Sample:

df = pd.DataFrame({'ID':['4806105017087','4806105017087','CN414149']})
print (df)
              ID
0  4806105017087
1  4806105017087
2       CN414149

print (pd.to_numeric(df.ID, errors='coerce'))
0    4.806105e+12
1    4.806105e+12
2             NaN
Name: ID, dtype: float64

df.ID = pd.to_numeric(df.ID, errors='coerce').fillna(0).astype(np.int64)
print (df)
              ID
0  4806105017087
1  4806105017087
2              0

EDIT: If use pandas 0.25+ then is possible use integer_na:

df.ID = pd.to_numeric(df.ID, errors='coerce').astype('Int64')
print (df)
              ID
0  4806105017087
1  4806105017087
2            NaN

How do I install g++ on MacOS X?

Download Xcode, which is free with an ADC online membership (also free):

http://developer.apple.com/technology/xcode.html

I need to get all the cookies from the browser

Modern approach.

let c = document.cookie.split(";").reduce( (ac, cv, i) => Object.assign(ac, {[cv.split('=')[0]]: cv.split('=')[1]}), {});

console.log(c);

;)

In jQuery, how do I get the value of a radio button when they all have the same name?

in your selector, you should also specify that you want the checked radiobutton:

$(function(){
    $("#submit").click(function(){      
        alert($('input[name=q12_3]:checked').val());
    });
 });

How do I set up a private Git repository on GitHub? Is it even possible?

GitHub is a great tool in-all for making repositories. However, it does not do good with private repositories.

You're forced to pay for private repositories unless you get some sort of plan. I have a couple of projects so far, and if GitHub doesn't do what I want I just go to Bitbucket. It's a bit harder to work with than GitHub, however it's unlimited free repositories.

How to compare two date values with jQuery

just use the jQuery datepicker UI library and convert both your strings into date format, then you can easily compare. following link might be useful

https://stackoverflow.com/questions/2974496/jquery-javascript-convert-date-string-to-date

cheers..!!

What does a just-in-time (JIT) compiler do?

A non-JIT compiler takes source code and transforms it into machine specific byte code at compile time. A JIT compiler takes machine agnostic byte code that was generated at compile time and transforms it into machine specific byte code at run time. The JIT compiler that Java uses is what allows a single binary to run on a multitude of platforms without modification.

How can I get the key value in a JSON object?

You can simply traverse through the object and return if a match is found.

Here is the code:

returnKeyforValue : function() {
    var JsonObj= { "one":1, "two":2, "three":3, "four":4, "five":5 };
        for (key in JsonObj) {
        if(JsonObj[key] === "Keyvalue") {
            return key;
        }
    }
}

How to open a web page from my application?

The old school way ;)

public static void openit(string x) {
   System.Diagnostics.Process.Start("cmd", "/C start" + " " + x); 
}

Use: openit("www.google.com");

Parsing a CSV file using NodeJS

I use this simple one: https://www.npmjs.com/package/csv-parser

Very simple to use:

const csv = require('csv-parser')
const fs = require('fs')
const results = [];

fs.createReadStream('./CSVs/Update 20191103C.csv')
  .pipe(csv())
  .on('data', (data) => results.push(data))
  .on('end', () => {
    console.log(results);
    console.log(results[0]['Lowest Selling Price'])
  });

xsl: how to split strings?

I. Plain XSLT 1.0 solution:

This transformation:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>

 <xsl:template match="text()" name="split">
  <xsl:param name="pText" select="."/>
  <xsl:if test="string-length($pText)">
   <xsl:if test="not($pText=.)">
    <br />
   </xsl:if>
   <xsl:value-of select=
    "substring-before(concat($pText,';'),';')"/>
   <xsl:call-template name="split">
    <xsl:with-param name="pText" select=
     "substring-after($pText, ';')"/>
   </xsl:call-template>
  </xsl:if>
 </xsl:template>
</xsl:stylesheet>

when applied on this XML document:

<t>123 Elm Street;PO Box 222;c/o James Jones</t>

produces the wanted, corrected result:

123 Elm Street<br />PO Box 222<br />c/o James Jones

II. FXSL 1 (for XSLT 1.0):

Here we just use the FXSL template str-map (and do not have to write recursive template for the 999th time):

<xsl:stylesheet version="1.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:f="http://fxsl.sf.net/"
xmlns:testmap="testmap"
exclude-result-prefixes="xsl f testmap"
>
   <xsl:import href="str-dvc-map.xsl"/>

   <testmap:testmap/>

   <xsl:output omit-xml-declaration="yes" indent="yes"/>

   <xsl:template match="/">
     <xsl:variable name="vTestMap" select="document('')/*/testmap:*[1]"/>
     <xsl:call-template name="str-map">
       <xsl:with-param name="pFun" select="$vTestMap"/>
       <xsl:with-param name="pStr" select=
       "'123 Elm Street;PO Box 222;c/o James Jones'"/>
     </xsl:call-template>
   </xsl:template>

    <xsl:template name="replace" mode="f:FXSL"
         match="*[namespace-uri() = 'testmap']">
      <xsl:param name="arg1"/>

      <xsl:choose>
       <xsl:when test="not($arg1=';')">
        <xsl:value-of select="$arg1"/>
       </xsl:when>
       <xsl:otherwise><br /></xsl:otherwise>
      </xsl:choose>
    </xsl:template>
</xsl:stylesheet>

when this transformation is applied on any XML document (not used), the same, wanted correct result is produced:

123 Elm Street<br/>PO Box 222<br/>c/o James Jones

III. Using XSLT 2.0

<xsl:stylesheet version="2.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>

 <xsl:template match="text()">
  <xsl:for-each select="tokenize(.,';')">
   <xsl:sequence select="."/>
   <xsl:if test="not(position() eq last())"><br /></xsl:if>
  </xsl:for-each>
 </xsl:template>
</xsl:stylesheet>

when this transformation is applied on this XML document:

<t>123 Elm Street;PO Box 222;c/o James Jones</t>

the wanted, correct result is produced:

123 Elm Street<br />PO Box 222<br />c/o James Jones

OSX -bash: composer: command not found

If you have to run composer with sudo, you should change the directory of composer to

/usr/bin

this was tested on Centos8.

What should main() return in C and C++?

In C, the Section 5.1.2.2.1 of the C11 standard (emphasis mine):

It shall be defined with a return type of int and with no parameters:

int main(void) { /* ... */ }

or with two parameters (referred to here as argc and argv, though any names may be used, as they are local to the function in which they are declared):

int main(int argc, char *argv[]) { /* ... */ }

However for some beginners like me, an abstract example would allow me to get a grasp on it:

When you write a method in your program, e.g. int read_file(char filename[LEN]);, then you want, as the caller of this method to know if everything went well (because failures can happen, e.g. file could not be found). By checking the return value of the method you can know if everything went well or not, it's a mechanism for the method to signal you about its successful execution (or not), and let the caller (you, e.g. in your main method) decide how to handle an unexpected failure.

So now imagine I write a C program for a micro-mechanism which is used in a more complex system. When the system calls the micro-mechanism, it wants to know if everything went as expected, so that it can handle any potential error. If the C program's main method would return void, then how would the calling-system know about the execution of its subsystem (the micro-mechanism)? It cannot, that's why main() returns int, in order to communicate to its caller a successful (or not) execution.

In other words:

The rational is that the host environment (i.e. Operating System (OS)) needs to know if the program finished correctly. Without an int-compatible type as a return type (eg. void), the "status returned to the host environment is unspecified" (i.e. undefined behavior on most OS).

Convert Dictionary to JSON in Swift

private func convertDictToJson(dict : NSDictionary) -> NSDictionary?
{
    var jsonDict : NSDictionary!

    do {
        let jsonData = try JSONSerialization.data(withJSONObject:dict, options:[])
        let jsonDataString = String(data: jsonData, encoding: String.Encoding.utf8)!
        print("Post Request Params : \(jsonDataString)")
        jsonDict = [ParameterKey : jsonDataString]
        return jsonDict
    } catch {
        print("JSON serialization failed:  \(error)")
        jsonDict = nil
    }
    return jsonDict
}

How to pass dictionary items as function arguments in python?

If you want to use them like that, define the function with the variable names as normal:

def my_function(school, standard, city, name):
    schoolName  = school
    cityName = city
    standardName = standard
    studentName = name

Now you can use ** when you call the function:

data = {'school':'DAV', 'standard': '7', 'name': 'abc', 'city': 'delhi'}

my_function(**data)

and it will work as you want.

P.S. Don't use reserved words such as class.(e.g., use klass instead)

How to get the part of a file after the first line that matches a regular expression?

Alternatives to the excellent sed answer by jfgagne, and which don't include the matching line :

How to change value for innodb_buffer_pool_size in MySQL on Mac OS?

As stated,

innodb_buffer_pool_size=50M

Following the convention on the other predefined variables, make sure there is no space either side of the equals sign.

Then run

sudo service mysqld stop
sudo service mysqld start

Note

Sometimes, e.g. on Ubuntu, the MySQL daemon is named mysql as opposed to mysqld

I find that running /etc/init.d/mysqld restart doesn't always work and you may get an error like

Stopping mysqld:                                           [FAILED]
Starting mysqld:                                           [  OK  ]

To see if the variable has been set, run show variables and see if the value has been updated.

HTTP Error 403.14 - Forbidden - The Web server is configured to not list the contents of this directory

I have one quick remedy for this. In fact I got this error because I had not set my web page as start page. When I did my web page(html /aspx) as set start page as shown below I got this error corrected.enter image description here

I don't know whether this solution will help others.

Local package.json exists, but node_modules missing

Just had the same error message, but when I was running a package.json with:

"scripts": {
    "build": "tsc -p ./src",
}

tsc is the command to run the TypeScript compiler.

I never had any issues with this project because I had TypeScript installed as a global module. As this project didn't include TypeScript as a dev dependency (and expected it to be installed as global), I had the error when testing in another machine (without TypeScript) and running npm install didn't fix the problem. So I had to include TypeScript as a dev dependency (npm install typescript --save-dev) to solve the problem.

Can I use a binary literal in C or C++?

template<unsigned long N>
struct bin {
    enum { value = (N%10)+2*bin<N/10>::value };
} ;

template<>
struct bin<0> {
    enum { value = 0 };
} ;

// ...
    std::cout << bin<1000>::value << '\n';

The leftmost digit of the literal still has to be 1, but nonetheless.

Fitting iframe inside a div

Would this CSS fix it?

iframe {
    display:block;
    width:100%;
}

From this example: http://jsfiddle.net/HNyJS/2/show/

How do I resolve git saying "Commit your changes or stash them before you can merge"?

In my case, I backed up and then deleted the file that Git was complaining about, committed, then I was able to finally check out another branch.

I then replaced the file, copied back in the contents and continued as though nothing happened.

how do I join two lists using linq or lambda expressions

It sounds like you want something like:

var query = from order in workOrders
            join plan in plans
                 on order.WorkOrderNumber equals plan.WorkOrderNumber
            select new
            {
                order.WorkOrderNumber,
                order.Description,
                plan.ScheduledDate
            };

Git error when trying to push -- pre-receive hook declined

In my case, it's because I accidentally added a giant file to my uncommitted push and I could not get rid of it no matter whatever pull or reset or rm I did after.

my dirty solution but workable solution is to rename the current directory, re-clone the directory to local and reflect the changes manually to the recloned local directory...

It does not sound good but works...

org.apache.catalina.core.StandardContext startInternal SEVERE: Error listenerStart

I faced exactly the same issue in a Spring web app. In fact, I had removed spring-security by commenting the config annotation:

// @ImportResource({"/WEB-INF/spring-security.xml"})

but I had forgotten to remove the corresponding filters in web.xml:

<!-- Filters --> 
<filter>
    <filter-name>springSecurityFilterChain</filter-name>
    <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>

<filter-mapping>
    <filter-name>springSecurityFilterChain</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

Commenting filters solved the issue.

How to install Python MySQLdb module using pip?

If you have Windows installed on your system then type the following command on cmd :

pip install mysql-connector

if the above command does not work try using:

pip install mysql-connector-python

Now,if the above commands do not get the work done, try using:

pip install mysql-connector-python-rf

That's it you are good to go now.

How do I force git pull to overwrite everything on every pull?

If you haven't commit the local changes yet since the last pull/clone, you can use:

git checkout *
git pull

checkout will clear your local changes with the last local commit, and pull will sincronize it to the remote repository

Opening a folder in explorer and selecting a file

Use this method:

Process.Start(String, String)

First argument is an application (explorer.exe), second method argument are arguments of the application you run.

For example:

in CMD:

explorer.exe -p

in C#:

Process.Start("explorer.exe", "-p")

Fixed positioning in Mobile Safari

This may interest you. It's Apple Dev support page.
http://developer.apple.com/library/ios/#technotes/tn2010/tn2262/

Read the point "4. Modify code that relies on CSS fixed positioning" and you will find out that there is very good reason why Apple made the conscious decision to handle fixed position as static.

How to add jQuery in JS file

You can use the below code to achieve loading jQuery in your JS file. I have also added a jQuery JSFiddle that is working and it's using a self-invoking function.

_x000D_
_x000D_
// Anonymous "self-invoking" function_x000D_
(function() {_x000D_
    var startingTime = new Date().getTime();_x000D_
    // Load the script_x000D_
    var script = document.createElement("SCRIPT");_x000D_
    script.src = 'https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js';_x000D_
    script.type = 'text/javascript';_x000D_
    document.getElementsByTagName("head")[0].appendChild(script);_x000D_
_x000D_
    // Poll for jQuery to come into existance_x000D_
    var checkReady = function(callback) {_x000D_
        if (window.jQuery) {_x000D_
            callback(jQuery);_x000D_
        }_x000D_
        else {_x000D_
            window.setTimeout(function() { checkReady(callback); }, 20);_x000D_
        }_x000D_
    };_x000D_
_x000D_
    // Start polling..._x000D_
    checkReady(function($) {_x000D_
        $(function() {_x000D_
            var endingTime = new Date().getTime();_x000D_
            var tookTime = endingTime - startingTime;_x000D_
            window.alert("jQuery is loaded, after " + tookTime + " milliseconds!");_x000D_
        });_x000D_
    });_x000D_
})();
_x000D_
_x000D_
_x000D_

Other Option : - You can also try Require.JS which is a JS module loader.

ASP.NET MVC: No parameterless constructor defined for this object

I had the same problem...

If your using a interface to decouple your connection against your DbContext (like me) you can use structuremap.mvc (3 or 4 - nudget package) to be able to use a constructure in your controller class. This will give you a DependencyResolution folder. Just change the commented line with your For< InterfaceClass >() and to Use< DbContextClass >().

Simple check for SELECT query empty result

I agree with Ed B. You should use EXISTS method but a more efficient way to do this is:

IF EXISTS(SELECT 1 FROM service s WHERE s.service_id = ?)
BEGIN
   --DO STUFF HERE

END

HTH

How to check if directory exist using C++ and winAPI

If linking to the shell Lightweight API (shlwapi.dll) is ok for you, you can use the PathIsDirectory function

How to scale an Image in ImageView to keep the aspect ratio

Use these properties in ImageView to keep aspect ratio:

android:adjustViewBounds="true"
android:scaleType="fitXY"

<ImageView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:adjustViewBounds="true"
    android:scaleType="fitXY"
    />

How do I check if a property exists on a dynamic anonymous type in c#?

Using reflection, this is the function i use :

public static bool doesPropertyExist(dynamic obj, string property)
{
    return ((Type)obj.GetType()).GetProperties().Where(p => p.Name.Equals(property)).Any();
}

then..

if (doesPropertyExist(myDynamicObject, "myProperty")){
    // ...
}

Generate 'n' unique random numbers within a range

You could add to a set until you reach n:

setOfNumbers = set()
while len(setOfNumbers) < n:
    setOfNumbers.add(random.randint(numLow, numHigh))

Be careful of having a smaller range than will fit in n. It will loop forever, unable to find new numbers to insert up to n

Browse files and subfolders in Python

Use newDirName = os.path.abspath(dir) to create a full directory path name for the subdirectory and then list its contents as you have done with the parent (i.e. newDirList = os.listDir(newDirName))

You can create a separate method of your code snippet and call it recursively through the subdirectory structure. The first parameter is the directory pathname. This will change for each subdirectory.

This answer is based on the 3.1.1 version documentation of the Python Library. There is a good model example of this in action on page 228 of the Python 3.1.1 Library Reference (Chapter 10 - File and Directory Access). Good Luck!

How Should I Set Default Python Version In Windows?

This worked for me:

Go to

Control Panel\System and Security\System

select

Advanced system settings from the left panel
from Advanced tab click on Environment Variables

In the System variables section search for (create if doesn't exist)

PYTHONPATH

and set

C:\Python27\;C:\Python27\Scripts;

or your desired version

You need to restart CMD.

In case it still doesn't work you might want to leave in the PATH variable only your desired version.

YouTube iframe API: how do I control an iframe player that's already in the HTML?

My own version of Kim T's code above which combines with some jQuery and allows for targeting of specific iframes.

$(function() {
    callPlayer($('#iframe')[0], 'unMute');
});

function callPlayer(iframe, func, args) {
    if ( iframe.src.indexOf('youtube.com/embed') !== -1) {
        iframe.contentWindow.postMessage( JSON.stringify({
            'event': 'command',
            'func': func,
            'args': args || []
        } ), '*');
    }
}

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

The database must have a name (example DB1), try this one:

OracleConnection con = new OracleConnection("data source=DB1;user id=fastecit;password=fastecit"); 

In case the TNS is not defined you can also try this one:

OracleConnection con = new OracleConnection("Data Source=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521)))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=DB1)));
User Id=fastecit;Password=fastecit"); 

Android: How to detect double-tap?

If you are using Kotlin then you can do it like this:

I spend a lot of time to convert this code to Kotlin hope it save someone's time

Create a gesture detector:

      val gestureDetector = GestureDetector(this, object : GestureDetector.SimpleOnGestureListener() {
            override fun onDoubleTap(e: MotionEvent): Boolean {

                Toast.makeText(this@DemoActivity,"Double Tap",Toast.LENGTH_LONG).show()

                //Show or hide Ip address on double tap
                toggleIPaddressVisibility()

                return true;
            }

            override fun onLongPress(e: MotionEvent) {
                super.onLongPress(e);

                //rotate frame on long press
                toggleFrameRotation()

                Toast.makeText(this@DemoActivity,"LongClick",Toast.LENGTH_LONG).show()
            }

            override fun onDoubleTapEvent(e: MotionEvent): Boolean {
                return true
            }

            override fun onDown(e: MotionEvent): Boolean {
                return true
            }
        })

Assign to any of your view:

        IPAddress.setOnTouchListener { v, event ->
          return@setOnTouchListener  gestureDetector.onTouchEvent(event)
        }

How to convert int to NSString?

NSString *string = [NSString stringWithFormat:@"%d", theinteger];

How can Bash execute a command in a different directory context?

(cd /path/to/your/special/place;/bin/your-special-command ARGS)

SQL keys, MUL vs PRI vs UNI

UNI: For UNIQUE:

  • It is a set of one or more columns of a table to uniquely identify the record.
  • A table can have multiple UNIQUE key.
  • It is quite like primary key to allow unique values but can accept one null value which primary key does not.

PRI: For PRIMARY:

  • It is also a set of one or more columns of a table to uniquely identify the record.
  • A table can have only one PRIMARY key.
  • It is quite like UNIQUE key to allow unique values but does not allow any null value.

MUL: For MULTIPLE:

  • It is also a set of one or more columns of a table which does not identify the record uniquely.
  • A table can have more than one MULTIPLE key.
  • It can be created in table on index or foreign key adding, it does not allow null value.
  • It allows duplicate entries in column.
  • If we do not specify MUL column type then it is quite like a normal column but can allow null entries too hence; to restrict such entries we need to specify it.
  • If we add indexes on column or add foreign key then automatically MUL key type added.

restrict edittext to single line

At XML file. Just add

android:maxLines="1"

Regex match digits, comma and semicolon?

You current regex will only match 1 character. you need either * (includes empty string) or + (at least one) to match multiple characters and numbers have a shortcut : \d (need \\ in a string).

word.matches("^[\\d,;]+$") 

The Pattern documentation is pretty good : http://download.oracle.com/javase/1.5.0/docs/api/java/util/regex/Pattern.html

Also you can try your regexps online at: http://www.regexplanet.com/simple/index.html

Multiple inputs with same name through POST in php

For anyone else finding this - its worth noting that you can set the key value in the input name. Thanks to the answer in POSTing Form Fields with same Name Attribute you also can interplay strings or integers without quoting.

The answers assume that you don't mind the key value coming back for PHP however you can set name=[yourval] (string or int) which then allows you to refer to an existing record.

How to create web service (server & Client) in Visual Studio 2012?

--- create a ws server vs2012 upd 3

  1. new project

  2. choose .net framework 3.5

  3. asp.net web service application

  4. right click on the project root

  5. choose add service reference

  6. choose wsdl

--- how can I create a ws client from a wsdl file?

I´ve a ws server Axis2 under tomcat 7 and I want to test the compatibility

How to check the gradle version in Android Studio?

  1. Create new project in Android studio;

  2. Press Ctrl+Shift+Alt+S

  3. Proceed to "Project" section

  4. You can see actual gradle version and android pluging version. Copy that to your project.

How can you get the first digit in an int (C#)?

variation on Anton's answer:

 // cut down the number of divisions (assuming i is positive & 32 bits)
if (i >= 100000000) i /= 100000000;
if (i >= 10000) i /= 10000;
if (i >= 100) i /= 100;
if (i >= 10) i /= 10;

WCF service startup error "This collection already contains an address with scheme http"

Did you see this - http://kb.discountasp.net/KB/a799/error-accessing-wcf-service-this-collection-already.aspx

You can resolve this error by changing the web.config file.

With ASP.NET 4.0, add the following lines to your web.config:

<system.serviceModel> 
     <serviceHostingEnvironment multipleSiteBindingsEnabled="true" /> 
</system.serviceModel> 

With ASP.NET 2.0/3.0/3.5, add the following lines to your web.config:

<system.serviceModel> 
     <serviceHostingEnvironment> 
          <baseAddressPrefixFilters> 
               <add prefix="http://www.YourHostedDomainName.com"/> 
          </baseAddressPrefixFilters> 
     </serviceHostingEnvironment> 
</system.serviceModel> 

How to fix nginx throws 400 bad request headers on any header testing tools?

Yes changing the error_to debug level as Emmanuel Joubaud suggested worked out (edit /etc/nginx/sites-enabled/default ):

        error_log /var/log/nginx/error.log debug;

Then after restaring nginx I got in the error log with my Python application using uwsgi:

        2017/02/08 22:32:24 [debug] 1322#1322: *1 connect to unix:///run/uwsgi/app/socket, fd:20 #2
        2017/02/08 22:32:24 [debug] 1322#1322: *1 connected
        2017/02/08 22:32:24 [debug] 1322#1322: *1 http upstream connect: 0
        2017/02/08 22:32:24 [debug] 1322#1322: *1 posix_memalign: 0000560E1F25A2A0:128 @16
        2017/02/08 22:32:24 [debug] 1322#1322: *1 http upstream send request
        2017/02/08 22:32:24 [debug] 1322#1322: *1 http upstream send request body
        2017/02/08 22:32:24 [debug] 1322#1322: *1 chain writer buf fl:0 s:454
        2017/02/08 22:32:24 [debug] 1322#1322: *1 chain writer in: 0000560E1F2A0928
        2017/02/08 22:32:24 [debug] 1322#1322: *1 writev: 454 of 454
        2017/02/08 22:32:24 [debug] 1322#1322: *1 chain writer out: 0000000000000000
        2017/02/08 22:32:24 [debug] 1322#1322: *1 event timer add: 20: 60000:1486593204249
        2017/02/08 22:32:24 [debug] 1322#1322: *1 http finalize request: -4, "/?" a:1, c:2
        2017/02/08 22:32:24 [debug] 1322#1322: *1 http request count:2 blk:0
        2017/02/08 22:32:24 [debug] 1322#1322: *1 post event 0000560E1F2E5DE0
        2017/02/08 22:32:24 [debug] 1322#1322: *1 post event 0000560E1F2E5E40
        2017/02/08 22:32:24 [debug] 1322#1322: *1 delete posted event 0000560E1F2E5DE0
        2017/02/08 22:32:24 [debug] 1322#1322: *1 http run request: "/?"
        2017/02/08 22:32:24 [debug] 1322#1322: *1 http upstream check client, write event:1, "/"
        2017/02/08 22:32:24 [debug] 1322#1322: *1 http upstream recv(): -1 (11: Resource temporarily unavailable)

Then I took a look to my uwsgi log and found out that:

        Invalid HTTP_HOST header: 'www.mysite.local'. You may need to add u'www.mysite.local' to ALLOWED_HOSTS.
        [pid: 10903|app: 0|req: 2/4] 192.168.221.2 () {38 vars in 450 bytes} [Wed Feb  8 22:32:24 2017] GET / => generated 54098 bytes in 55 msecs (HTTP/1.1 400) 4 headers in 135 bytes (1 switches on core 0)

And adding www.mysite.local to the settings.py ALLOWED_HOSTS fixed the issue :)

        ALLOWED_HOSTS = ['www.mysite.local']

Auto generate function documentation in Visual Studio

Visual Assist has a nice solution too, and is highly costumizable.

After tweaking it to generate doxygen-style comments, these two clicks would produce -

/**
* Method:    FindTheFoo
* FullName:  FindTheFoo
* Access:    private 
* Qualifier:
* @param    int numberOfFoos
* @return   bool
*/
private bool FindTheFoo(int numberOfFoos)
{

}

(Under default settings, its a bit different.)


Edit: The way to customize the 'document method' text is under VassistX->Visual Assist Options->Suggestions, select 'Edit VA Snippets', Language: C++, Type: Refactoring, then go to 'Document Method' and customize. The above example is generated by:

va_doxy

How to SUM parts of a column which have same text value in different column in the same row

This can be done by using SUMPRODUCT as well. Update the ranges as you see fit

=SUMPRODUCT(($A$2:$A$7=A2)*($B$2:$B$7=B2)*$C$2:$C$7)

A2:A7 = First name range

B2:B7 = Last Name Range

C2:C7 = Numbers Range

This will find all the names with the same first and last name and sum the numbers in your numbers column

Maven plugin in Eclipse - Settings.xml file is missing

The settings file is never created automatically, you must create it yourself, whether you use embedded or "real" maven.

Create it at the following location <your home folder>/.m2/settings.xml e.g. C:\Users\YourUserName\.m2\settings.xml on Windows or /home/YourUserName/.m2/settings.xml on Linux

Here's an empty skeleton you can use:

<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0
                      http://maven.apache.org/xsd/settings-1.0.0.xsd">
  <localRepository/>
  <interactiveMode/>
  <usePluginRegistry/>
  <offline/>
  <pluginGroups/>
  <servers/>
  <mirrors/>
  <proxies/>
  <profiles/>
  <activeProfiles/>
</settings>

If you use Eclipse to edit it, it will give you auto-completion when editing it.

And here's the Maven settings.xml Reference page

What is DOM element?

As per W3C: DOM permits programs and scripts to dynamically access and update the content, structure and style of XML or HTML documents.

DOM is composed of:

  • set of objects/elements
  • a structure of how these objects/elements can be combined
  • and an interface to access and modify them

cheers

How to hide a column (GridView) but still access its value?

You can use DataKeys for retrieving the value of such fields, because (as you said) when you set a normal BoundField as visible false you cannot get their value.

In the .aspx file set the GridView property

DataKeyNames = "Outlook_ID"

Now, in an event handler you can access the value of this key like so:

grid.DataKeys[rowIndex]["Outlook_ID"]

This will give you the id at the specified rowindex of the grid.

Two HTML tables side by side, centered on the page

Off the top of my head, you might try using the "margin: 0 auto" for #outer rather than #inner.

I often add background-color to my DIVs to see how they're laying out on the view. That might be a good way to diagnose what's going onn here.

Open files in 'rt' and 'wt' modes

The t indicates text mode, meaning that \n characters will be translated to the host OS line endings when writing to a file, and back again when reading. The flag is basically just noise, since text mode is the default.

Other than U, those mode flags come directly from the standard C library's fopen() function, a fact that is documented in the sixth paragraph of the python2 documentation for open().

As far as I know, t is not and has never been part of the C standard, so although many implementations of the C library accept it anyway, there's no guarantee that they all will, and therefore no guarantee that it will work on every build of python. That explains why the python2 docs didn't list it, and why it generally worked anyway. The python3 docs make it official.

Create numpy matrix filled with NaNs

Yet another possibility not yet mentioned here is to use NumPy tile:

a = numpy.tile(numpy.nan, (3, 3))

Also gives

array([[ NaN,  NaN,  NaN],
       [ NaN,  NaN,  NaN],
       [ NaN,  NaN,  NaN]])

I don't know about speed comparison.

Storing integer values as constants in Enum manner in java

if you want to be able to convert integer back to corresponding enum with selected value see Constants.forValue(...) in below auto generated code but if not the answer of BlairHippo is best way to do it.

public enum Constants
{
SIGN_CREATE(0),
SIGN_CREATE(1),
HOME_SCREEN(2),
REGISTER_SCREEN(3);

    public static final int SIZE = java.lang.Integer.SIZE;

    private int intValue;
    private static java.util.HashMap<Integer, Constants> mappings;
    private static java.util.HashMap<Integer, Constants> getMappings()
    {
        if (mappings == null)
        {
            synchronized (Constants.class)
            {
                if (mappings == null)
                {
                    mappings = new java.util.HashMap<Integer, Constants>();
                }
            }
        }
        return mappings;
    }

    private Constants(int value)
    {
        intValue = value;
        getMappings().put(value, this);
    }

    public int getValue()
    {
        return intValue;
    }

    public static Constants forValue(int value)
    {
        return getMappings().get(value);
    }
}

How do I add a border to an image in HTML?

border="1" ON IMAGE tag or using css border:1px solid #000;

Copy text from nano editor to shell

Nano to Shell:

1. Using mouse to mark the text.

2. Right-Click the mouse in the Shell.

Within Nano:

1. CTRL+6 (or hold Shift and move cursor) for Mark Set and mark what you want (the end could do some extra help).

2. ALT+6 for copying the marked text.

3. CTRL+u at the place you want to paste.

or

1. CTRL+6 (or hold Shift and move cursor) for Mark Set and mark what you want (the end could do some extra help).

2. CTRL+k for cutting what you want to copy

3. CTRL+u for pasting what you have just cut because you just want to copy.

4. CTRL+u at the place you want to paste.

Date in mmm yyyy format in postgresql

DateAndTime Reformat:

SELECT *, to_char( last_update, 'DD-MON-YYYY') as re_format from actor;

DEMO:

enter image description here

OVER clause in Oracle

The OVER clause specifies the partitioning, ordering and window "over which" the analytic function operates.

Example #1: calculate a moving average

AVG(amt) OVER (ORDER BY date ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING)

date   amt   avg_amt
=====  ====  =======
1-Jan  10.0  10.5
2-Jan  11.0  17.0
3-Jan  30.0  17.0
4-Jan  10.0  18.0
5-Jan  14.0  12.0

It operates over a moving window (3 rows wide) over the rows, ordered by date.

Example #2: calculate a running balance

SUM(amt) OVER (ORDER BY date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)

date   amt   sum_amt
=====  ====  =======
1-Jan  10.0  10.0
2-Jan  11.0  21.0
3-Jan  30.0  51.0
4-Jan  10.0  61.0
5-Jan  14.0  75.0

It operates over a window that includes the current row and all prior rows.

Note: for an aggregate with an OVER clause specifying a sort ORDER, the default window is UNBOUNDED PRECEDING to CURRENT ROW, so the above expression may be simplified to, with the same result:

SUM(amt) OVER (ORDER BY date)

Example #3: calculate the maximum within each group

MAX(amt) OVER (PARTITION BY dept)

dept  amt   max_amt
====  ====  =======
ACCT   5.0   7.0
ACCT   7.0   7.0
ACCT   6.0   7.0
MRKT  10.0  11.0
MRKT  11.0  11.0
SLES   2.0   2.0

It operates over a window that includes all rows for a particular dept.

SQL Fiddle: http://sqlfiddle.com/#!4/9eecb7d/122

How to use ng-if to test if a variable is defined

Try this:

item.shipping!==undefined

How to move all HTML element children to another parent using JavaScript?

If you not use - in id's names then you can do this

_x000D_
_x000D_
oldParent.id='xxx';_x000D_
newParent.id='oldParent';_x000D_
xxx.id='newParent';_x000D_
oldParent.parentNode.insertBefore(oldParent,newParent);
_x000D_
#newParent { color: red }
_x000D_
<div id="oldParent">_x000D_
    <span>Foo</span>_x000D_
    <b>Bar</b>_x000D_
    Hello World_x000D_
</div>_x000D_
<div id="newParent"></div>
_x000D_
_x000D_
_x000D_

ORA-01843 not a valid month- Comparing Dates

In a comment to one of the answers you mention that to_date with a format doesn't help. In another comment you explain that the table is accessed via DBLINK.

So obviously the other system contains an invalid date that Oracle cannot accept. Fix this in the other dbms (or whatever you dblink to) and your query will work.

Having said this, I agree with the others: always use to_date with a format to convert a string literal to a date. Also never use only two digits for a year. For example '23/04/49' means 2049 in your system (format RR), but it confuses the reader (as you see from the answers suggesting a format with YY).

Repeat each row of data.frame the number of times specified in a column

In case you have to do this operation on very large data.frames I would recommend converting it into a data.table and use the following, which should run much faster:

library(data.table)
dt <- data.table(df)
dt.expanded <- dt[ ,list(freq=rep(1,freq)),by=c("var1","var2")]
dt.expanded[ ,freq := NULL]
dt.expanded

See how much faster this solution is:

df <- data.frame(var1=1:2e3, var2=1:2e3, freq=1:2e3)
system.time(df.exp <- df[rep(row.names(df), df$freq), 1:2])
##    user  system elapsed 
##    4.57    0.00    4.56
dt <- data.table(df)
system.time(dt.expanded <- dt[ ,list(freq=rep(1,freq)),by=c("var1","var2")])
##    user  system elapsed 
##    0.05    0.01    0.06

How to remove and clear all localStorage data

Something like this should do:

function cleanLocalStorage() {
    for(key in localStorage) {
        delete localStorage[key];
    }
}

Be careful about using this, though, as the user may have other data stored in localStorage and would probably be pretty ticked if you deleted that. I'd recommend either a) not storing the user's data in localStorage or b) storing the user's account stuff in a single variable, and then clearing that instead of deleting all the keys in localStorage.


Edit: As Lyn pointed out, you'll be good with localStorage.clear(). My previous points still stand, however.

sublime text2 python error message /usr/bin/python: can't find '__main__' module in ''

You need to SAVE your code file with the ".py" extension. Then, on the 'Tools/Build System' menu, make sure your build system is set to either 'auto' or 'Python'. What that message is telling you is there is no valid Python file to 'build' (or, in this case just run).

Javascript: how to validate dates in format MM-DD-YYYY?

I would use Moment.js for this task. It makes it very easy to parse dates and it also provides support to detect a an invalid date1 in the correct format. For instance, consider this example:

var formats = ['MM-DD-YYYY', 'MM/DD/YYYY']

moment('11/28/1981', formats).isValid()  // true
moment('2-29-2003', formats).isValid()   // false (not leap year)
moment('2-29-2004', formats).isValid()   // true  (leap year)

First moment(.., formats) is used to parse the input according to the localized format supplied. Then the isValid function is called on the resulting moment object so that we can actually tell if it is a valid date.

This can be used to trivially derive the isValidDate method:

String.prototype.isValidDate = function() {
    var formats = ['MM-DD-YYYY', 'MM/DD/YYYY'];
    return moment("" + this, formats).isValid();
}

1 As I can find scarce little commentary on the matter, I would only use moment.js for dates covered by the Gregorian calendar. There may be plugins for other (including historical or scientific) calendars.

How to parse date string to Date?

A parse exception is a checked exception, so you must catch it with a try-catch when working with parsing Strings to Dates, as @miku suggested...

Getting net::ERR_UNKNOWN_URL_SCHEME while calling telephone number from HTML page in Android

I had this issue occurring with mailto: and tel: links inside an iframe (in Chrome, not a webview). Clicking the links would show the grey "page not found" page and inspecting the page showed it had a ERR_UNKNOWN_URL_SCHEME error.

Adding target="_blank", as suggested by this discussion of the issue fixed the problem for me.

Docker Error bind: address already in use

`$` sudo service redis-server stop

Does the trick.

Select unique or distinct values from a list in UNIX shell script

Unique, as requested, (but not sorted);
uses fewer system resources for less than ~70 elements (as tested with time);
written to take input from stdin,
(or modify and include in another script):
(Bash)

bag2set () {
    # Reduce a_bag to a_set.
    local -i i j n=${#a_bag[@]}
    for ((i=0; i < n; i++)); do
        if [[ -n ${a_bag[i]} ]]; then
            a_set[i]=${a_bag[i]}
            a_bag[i]=$'\0'
            for ((j=i+1; j < n; j++)); do
                [[ ${a_set[i]} == ${a_bag[j]} ]] && a_bag[j]=$'\0'
            done
        fi
    done
}
declare -a a_bag=() a_set=()
stdin="$(</dev/stdin)"
declare -i i=0
for e in $stdin; do
    a_bag[i]=$e
    i=$i+1
done
bag2set
echo "${a_set[@]}"

Datatables Select All Checkbox

You can use Checkboxes extension for jQuery Datatables.

var table = $('#example').DataTable({
   'ajax': 'https://api.myjson.com/bins/1us28',
   'columnDefs': [
      {
         'targets': 0,
         'checkboxes': {
            'selectRow': true
         }
      }
   ],
   'select': {
      'style': 'multi'
   },
   'order': [[1, 'asc']]
});

See this example for code and demonstration.

See Checkboxes project page for more examples and documentation.

Difference between "on-heap" and "off-heap"

from http://code.google.com/p/fast-serialization/wiki/QuickStartHeapOff

What is Heap-Offloading ?

Usually all non-temporary objects you allocate are managed by java's garbage collector. Although the VM does a decent job doing garbage collection, at a certain point the VM has to do a so called 'Full GC'. A full GC involves scanning the complete allocated Heap, which means GC pauses/slowdowns are proportional to an applications heap size. So don't trust any person telling you 'Memory is Cheap'. In java memory consumtion hurts performance. Additionally you may get notable pauses using heap sizes > 1 Gb. This can be nasty if you have any near-real-time stuff going on, in a cluster or grid a java process might get unresponsive and get dropped from the cluster.

However todays server applications (frequently built on top of bloaty frameworks ;-) ) easily require heaps far beyond 4Gb.

One solution to these memory requirements, is to 'offload' parts of the objects to the non-java heap (directly allocated from the OS). Fortunately java.nio provides classes to directly allocate/read and write 'unmanaged' chunks of memory (even memory mapped files).

So one can allocate large amounts of 'unmanaged' memory and use this to save objects there. In order to save arbitrary objects into unmanaged memory, the most viable solution is the use of Serialization. This means the application serializes objects into the offheap memory, later on the object can be read using deserialization.

The heap size managed by the java VM can be kept small, so GC pauses are in the millis, everybody is happy, job done.

It is clear, that the performance of such an off heap buffer depends mostly on the performance of the serialization implementation. Good news: for some reason FST-serialization is pretty fast :-).

Sample usage scenarios:

  • Session cache in a server application. Use a memory mapped file to store gigabytes of (inactive) user sessions. Once the user logs into your application, you can quickly access user-related data without having to deal with a database.
  • Caching of computational results (queries, html pages, ..) (only applicable if computation is slower than deserializing the result object ofc).
  • very simple and fast persistance using memory mapped files

Edit: For some scenarios one might choose more sophisticated Garbage Collection algorithms such as ConcurrentMarkAndSweep or G1 to support larger heaps (but this also has its limits beyond 16GB heaps). There is also a commercial JVM with improved 'pauseless' GC (Azul) available.

How does numpy.histogram() work?

A bin is range that represents the width of a single bar of the histogram along the X-axis. You could also call this the interval. (Wikipedia defines them more formally as "disjoint categories".)

The Numpy histogram function doesn't draw the histogram, but it computes the occurrences of input data that fall within each bin, which in turns determines the area (not necessarily the height if the bins aren't of equal width) of each bar.

In this example:

 np.histogram([1, 2, 1], bins=[0, 1, 2, 3])

There are 3 bins, for values ranging from 0 to 1 (excl 1.), 1 to 2 (excl. 2) and 2 to 3 (incl. 3), respectively. The way Numpy defines these bins if by giving a list of delimiters ([0, 1, 2, 3]) in this example, although it also returns the bins in the results, since it can choose them automatically from the input, if none are specified. If bins=5, for example, it will use 5 bins of equal width spread between the minimum input value and the maximum input value.

The input values are 1, 2 and 1. Therefore, bin "1 to 2" contains two occurrences (the two 1 values), and bin "2 to 3" contains one occurrence (the 2). These results are in the first item in the returned tuple: array([0, 2, 1]).

Since the bins here are of equal width, you can use the number of occurrences for the height of each bar. When drawn, you would have:

  • a bar of height 0 for range/bin [0,1] on the X-axis,
  • a bar of height 2 for range/bin [1,2],
  • a bar of height 1 for range/bin [2,3].

You can plot this directly with Matplotlib (its hist function also returns the bins and the values):

>>> import matplotlib.pyplot as plt
>>> plt.hist([1, 2, 1], bins=[0, 1, 2, 3])
(array([0, 2, 1]), array([0, 1, 2, 3]), <a list of 3 Patch objects>)
>>> plt.show()

enter image description here

Is there a way to make a DIV unselectable?

As Johannes has already suggested, a background-image is probally the best way to achieve this in CSS alone.

A JavaScript solution would also have to affect "dragstart" to be effective across all popular browsers.

JavaScript:

<div onselectstart="return false;" ondragstart="return false;">your text</div>

jQuery:

var _preventDefault = function(evt) { evt.preventDefault(); };
$("div").bind("dragstart", _preventDefault).bind("selectstart", _preventDefault);

Rich

Error message "unreported exception java.io.IOException; must be caught or declared to be thrown"

void showfile() throws java.io.IOException  <-----

Your showfile() method throws IOException, so whenever you use it you have to either catch that exception or again thorw it. Something like:

try {
  showfile();
}
catch(IOException e) {
  e.printStackTrace();
}

You should learn about exceptions in Java.

Sending emails in Node.js?

Mature, simple to use and has lots of features if simple isn't enought: Nodemailer: https://github.com/andris9/nodemailer (note correct url!)

Difference between virtual and abstract methods

an abstract method must be call override in derived class other wise it will give compile-time error and in virtual you may or may not override it's depend if it's good enough use it

Example:

abstract class twodshape
{
    public abstract void area(); // no body in base class
}

class twodshape2 : twodshape
{
    public virtual double area()
    {
        Console.WriteLine("AREA() may be or may not be override");
    }
}

Fixed size div?

.myDiv { height: 150px; width 150px; }

<div class="mainDiv">
   <div class="myDiv"></div>
   <div class="myDiv"></div>
   <div class="myDiv"></div>
</div>

XML to CSV Using XSLT

Found an XML transform stylesheet here (wayback machine link, site itself is in german)

The stylesheet added here could be helpful:

<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text" encoding="iso-8859-1"/>

<xsl:strip-space elements="*" />

<xsl:template match="/*/child::*">
<xsl:for-each select="child::*">
<xsl:if test="position() != last()">"<xsl:value-of select="normalize-space(.)"/>",    </xsl:if>
<xsl:if test="position()  = last()">"<xsl:value-of select="normalize-space(.)"/>"<xsl:text>&#xD;</xsl:text>
</xsl:if>
</xsl:for-each>
</xsl:template>

</xsl:stylesheet>

Perhaps you want to remove the quotes inside the xsl:if tags so it doesn't put your values into quotes, depending on where you want to use the CSV file.

Appending a byte[] to the end of another byte[]

Using System.arraycopy(), something like the following should work:

// create a destination array that is the size of the two arrays
byte[] destination = new byte[ciphertext.length + mac.length];

// copy ciphertext into start of destination (from pos 0, copy ciphertext.length bytes)
System.arraycopy(ciphertext, 0, destination, 0, ciphertext.length);

// copy mac into end of destination (from pos ciphertext.length, copy mac.length bytes)
System.arraycopy(mac, 0, destination, ciphertext.length, mac.length);

How can I trigger another job from a jenkins pipeline (jenkinsfile) with GitHub Org Plugin?

The command build in pipeline is there to trigger other jobs in jenkins.

Example on github

The job must exist in Jenkins and can be parametrized. As for the branch, I guess you can read it from git

What is The difference between ListBox and ListView

A ListView is basically like a ListBox (and inherits from it), but it also has a View property. This property allows you to specify a predefined way of displaying the items. The only predefined view in the BCL (Base Class Library) is GridView, but you can easily create your own.

Another difference is the default selection mode: it's Single for a ListBox, but Extended for a ListView

Why am I suddenly getting a "Blocked loading mixed active content" issue in Firefox?

Its given the error because of security. for this please use "https" not "http" in the website url.

For example :

   "https://code.jquery.com/ui/1.8.10/themes/smoothness/jquery-ui.css"
   "https://ajax.aspnetcdn.com/ajax/jquery.ui/1.8.10/jquery-ui.min.js"

Best way to do multiple constructors in PHP

Call constructors by data type:

class A 
{ 
    function __construct($argument)
    { 
       $type = gettype($argument);

       if($type == 'unknown type')
       {
            // type unknown
       }

       $this->{'__construct_'.$type}($argument);
    } 

    function __construct_boolean($argument) 
    { 
        // do something
    }
    function __construct_integer($argument) 
    { 
        // do something
    }
    function __construct_double($argument) 
    { 
        // do something
    }
    function __construct_string($argument) 
    { 
        // do something
    }
    function __construct_array($argument) 
    { 
        // do something
    }
    function __construct_object($argument) 
    { 
        // do something
    }
    function __construct_resource($argument) 
    { 
        // do something
    }

    // other functions

} 

generate random string for div id

Based on HTML 4, the id should start from letter:

ID and NAME tokens must begin with a letter ([A-Za-z]) and may be followed by any number of letters, digits ([0-9]), hyphens ("-"), underscores ("_"), colons (":"), and periods (".").

So, one of the solutions could be (alphanumeric):

  var length = 9;
  var prefix = 'my-awesome-prefix-'; // To be 100% sure id starts with letter

  // Convert it to base 36 (numbers + letters), and grab the first 9 characters
  // after the decimal.
  var id = prefix + Math.random().toString(36).substr(2, length);

Another solution - generate string with letters only:

  var length = 9;
  var id = Math.random().toString(36).replace(/[^a-z]+/g, '').substr(0, length);

How to list all dates between two dates

I made a calendar using:

http://social.technet.microsoft.com/wiki/contents/articles/22776.t-sql-calendar-table.aspx

then a Store procedure passing two dates and thats all:

USE DB_NAME;
GO

CREATE PROCEDURE [dbo].[USP_LISTAR_RANGO_FECHAS]
@FEC_INICIO date,
@FEC_FIN date
AS
Select Date from CALENDARIO where Date BETWEEN @FEC_INICIO AND @FEC_FIN;

Remove characters before character "."

Extension methods I commonly use to solve this problem:

public static string RemoveAfter(this string value, string character)
    {
        int index = value.IndexOf(character);
        if (index > 0)
        {
            value = value.Substring(0, index);
        }
        return value;
    }

    public static string RemoveBefore(this string value, string character)
    {
        int index = value.IndexOf(character);
        if (index > 0)
        {
            value = value.Substring(index + 1);
        }
        return value;
    }

Virtual Serial Port for Linux

Would you be able to use a USB->RS232 adapter? I have a few, and they just use the FTDI driver. Then, you should be able to rename /dev/ttyUSB0 (or whatever gets created) as /dev/ttyS2 .

Get Last Part of URL PHP

You can use preg_match to match the part of the URL that you want.

In this case, since the pattern is easy, we're looking for a forward slash (\/ and we have to escape it since the forward slash denotes the beginning and end of the regular expression pattern), along with one or more digits (\d+) at the very end of the string ($). The parentheses around the \d+ are used for capturing the piece that we want: namely the end. We then assign the ending that we want ($end) to $matches[1] (not $matches[0], since that is the same as $url (ie the entire string)).

$url='http://domain.com/artist/song/music-videos/song-title/9393903';

if(preg_match("/\/(\d+)$/",$url,$matches))
{
  $end=$matches[1];
}
else
{
  //Your URL didn't match.  This may or may not be a bad thing.
}

Note: You may or may not want to add some more sophistication to this regular expression. For example, if you know that your URL strings will always start with http:// then the regex can become /^http:\/\/.*\/(\d+)$/ (where .* means zero or more characters (that aren't the newline character)).

Creating a list of objects in Python

It shouldn't be necessary to recreate the SimpleClass object each time, as some are suggesting, if you're simply using it to output data based on its attributes. However, you're not actually creating an instance of the class; you're simply creating a reference to the class object itself. Therefore, you're adding a reference to the same class attribute to the list (instead of instance attribute), over and over.

Instead of:

x = SimpleClass

you need:

x = SimpleClass()

How to create a table from select query result in SQL Server 2008

Use following syntax to create new table from old table in SQL server 2008

Select * into new_table  from  old_table 

Android video streaming example

Your problem is most likely with the video file, not the code. Your video is most likely not "safe for streaming". See where to place videos to stream android for more.

fatal: could not read Username for 'https://github.com': No such file or directory

Follow the steps to setup SSH keys here: https://help.github.com/articles/generating-ssh-keys

OR

git remote add origin https://{username}:{password}@github.com/{username}/project.git

Python, how to check if a result set is empty?

if you're connecting to a postgres database, the following works:

result = cursor.execute(query)

if result.returns_rows:
    # we got rows!
    return [{k:v for k,v in zip(result.keys(), r)} for r in result.rows]
else:
    return None

Create a string of variable length, filled with a repeated character

A great ES6 option would be to padStart an empty string. Like this:

var str = ''.padStart(10, "#");

Note: this won't work in IE (without a polyfill).

How to check if function exists in JavaScript?

function js_to_as( str ){
     if (me && me.onChange)
         me.onChange(str);
}

How to use null in switch

You have to make a

if (i == null) {
   doSomething0();
} else {
   switch (i) {
   }
}

SQL Server: Importing database from .mdf?

Open SQL Management Studio Express and log in to the server to which you want to attach the database. In the 'Object Explorer' window, right-click on the 'Databases' folder and select 'Attach...' The 'Attach Databases' window will open; inside that window click 'Add...' and then navigate to your .MDF file and click 'OK'. Click 'OK' once more to finish attaching the database and you are done. The database should be available for use. best regards :)

Concat scripts in order with Gulp

Apparently you can pass in the "nosort" option to gulp.src gulp.src.

How to solve "The specified service has been marked for deletion" error

Deleting registry keys as suggested above got my service stuck in the stopping state. The following procedure worked for me:

open task manager > select services tab > select the service > right click and select "go to process" > right click on the process and select End process

Service should be gone after that

How to merge specific files from Git branches

None of the other current answers will actually "merge" the files, as if you were using the merge command. (At best they'll require you to manually pick diffs.) If you actually want to take advantage of merging using the information from a common ancestor, you can follow a procedure based on one found in the "Advanced Merging" section of the git Reference Manual.

For this protocol, I'm assuming you're wanting to merge the file 'path/to/file.txt' from origin/master into HEAD - modify as appropriate. (You don't have to be in the top directory of your repository, but it helps.)

# Find the merge base SHA1 (the common ancestor) for the two commits:
git merge-base HEAD origin/master

# Get the contents of the files at each stage
git show <merge-base SHA1>:path/to/file.txt > ./file.common.txt
git show HEAD:path/to/file.txt > ./file.ours.txt
git show origin/master:path/to/file.txt > ./file.theirs.txt

# You can pre-edit any of the files (e.g. run a formatter on it), if you want.

# Merge the files
git merge-file -p ./file.ours.txt ./file.common.txt ./file.theirs.txt > ./file.merged.txt

# Resolve merge conflicts in ./file.merged.txt
# Copy the merged version to the destination
# Clean up the intermediate files

git merge-file should use all of your default merge settings for formatting and the like.

Also note that if your "ours" is the working copy version and you don't want to be overly cautious, you can operate directly on the file:

git merge-base HEAD origin/master
git show <merge-base SHA1>:path/to/file.txt > ./file.common.txt
git show origin/master:path/to/file.txt > ./file.theirs.txt
git merge-file path/to/file.txt ./file.common.txt ./file.theirs.txt

Print a list in reverse order with range()?

Readibility aside, reversed(range(n)) seems to be faster than range(n)[::-1].

$ python -m timeit "reversed(range(1000000000))"
1000000 loops, best of 3: 0.598 usec per loop
$ python -m timeit "range(1000000000)[::-1]"
1000000 loops, best of 3: 0.945 usec per loop

Just if anyone was wondering :)

Passing on command line arguments to runnable JAR

You can pass program arguments on the command line and get them in your Java app like this:

public static void main(String[] args) {
  String pathToXml = args[0];
....
}

Alternatively you pass a system property by changing the command line to:

java -Dpath-to-xml=enwiki-20111007-pages-articles.xml -jar wiki2txt

and your main class to:

public static void main(String[] args) {
  String pathToXml = System.getProperty("path-to-xml");
....
}

how to call a function from another function in Jquery

I assume you don't want to rebind the event, but call the handler.

You can use trigger() to trigger events:

$('#billing_state_id').trigger('change');

If your handler doesn't rely on the event context and you don't want to trigger other handlers for the event, you could also name the function:

function someFunction() {
    //do stuff
}

$(document).ready(function(){
    //Load City by State
    $('#billing_state_id').live('change', someFunction);   
    $('#click_me').live('click', function() {
       //do something
       someFunction();
    });
  });

Also note that live() is deprecated, on() is the new hotness.

How to draw in JPanel? (Swing/graphics Java)

Here is a simple example. I suppose it will be easy to understand:

import java.awt.*;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Graph extends JFrame {
JFrame f = new JFrame();
JPanel jp;


public Graph() {
    f.setTitle("Simple Drawing");
    f.setSize(300, 300);
    f.setDefaultCloseOperation(EXIT_ON_CLOSE);

    jp = new GPanel();
    f.add(jp);
    f.setVisible(true);
}

public static void main(String[] args) {
    Graph g1 = new Graph();
    g1.setVisible(true);
}

class GPanel extends JPanel {
    public GPanel() {
        f.setPreferredSize(new Dimension(300, 300));
    }

    @Override
    public void paintComponent(Graphics g) {
        //rectangle originates at 10,10 and ends at 240,240
        g.drawRect(10, 10, 240, 240);
        //filled Rectangle with rounded corners.    
        g.fillRoundRect(50, 50, 100, 100, 80, 80);
    }
}

}

And the output looks like this:

Output

Exposing a port on a live Docker container

Based on Robm's answer I have created a Docker image and a Bash script called portcat.

Using portcat, you can easily map multiple ports to an existing Docker container. An example using the (optional) Bash script:

curl -sL https://raw.githubusercontent.com/archan937/portcat/master/script/install | sudo bash
portcat my-awesome-container 3456 4444:8080

And there you go! Portcat is mapping:

  • port 3456 to my-awesome-container:3456
  • port 4444 to my-awesome-container:8080

Please note that the Bash script is optional, the following commands:

ipAddress=$(docker inspect my-awesome-container | grep IPAddress | grep -o '[0-9]\{1,3\}\(\.[0-9]\{1,3\}\)\{3\}' | head -n 1)
docker run -p 3456:3456 -p 4444:4444 --name=alpine-portcat -it pmelegend/portcat:latest $ipAddress 3456 4444:8080

I hope portcat will come in handy for you guys. Cheers!

Difference between @Before, @BeforeClass, @BeforeEach and @BeforeAll

Before and BeforeClass in JUnit

The function @Before annotation will be executed before each of test function in the class having @Test annotation but the function with @BeforeClass will be execute only one time before all the test functions in the class.

Similarly function with @After annotation will be executed after each of test function in the class having @Test annotation but the function with @AfterClass will be execute only one time after all the test functions in the class.

SampleClass

public class SampleClass {
    public String initializeData(){
        return "Initialize";
    }

    public String processDate(){
        return "Process";
    }
 }

SampleTest

public class SampleTest {

    private SampleClass sampleClass;

    @BeforeClass
    public static void beforeClassFunction(){
        System.out.println("Before Class");
    }

    @Before
    public void beforeFunction(){
        sampleClass=new SampleClass();
        System.out.println("Before Function");
    }

    @After
    public void afterFunction(){
        System.out.println("After Function");
    }

    @AfterClass
    public static void afterClassFunction(){
        System.out.println("After Class");
    }

    @Test
    public void initializeTest(){
        Assert.assertEquals("Initailization check", "Initialize", sampleClass.initializeData() );
    }

    @Test
    public void processTest(){
        Assert.assertEquals("Process check", "Process", sampleClass.processDate() );
    }

}

Output

Before Class
Before Function
After Function
Before Function
After Function
After Class

In Junit 5

@Before = @BeforeEach
@BeforeClass = @BeforeAll
@After = @AfterEach
@AfterClass = @AfterAll

How can I force component to re-render with hooks in React?

Alternative to @MinhKha's answer:

It can be much cleaner with useReducer:

const [, forceUpdate] = useReducer(x => x + 1, 0);

Usage: forceUpdate() - cleaner without params

How to pass arguments to Shell Script through docker run

Use the same file.sh

#!/bin/bash
echo $1

Build the image using the existing Dockerfile:

docker build -t test .

Run the image with arguments abc or xyz or something else.

docker run -ti --rm test /file.sh abc

docker run -ti --rm test /file.sh xyz