Programs & Examples On #Xxtea

LinkButton Send Value to Code Behind OnClick

Add a CommandName attribute, and optionally a CommandArgument attribute, to your LinkButton control. Then set the OnCommand attribute to the name of your Command event handler.

<asp:LinkButton ID="ENameLinkBtn" runat="server" CommandName="MyValueGoesHere" CommandArgument="OtherValueHere" 
          style="font-weight: 700; font-size: 8pt;" OnCommand="ENameLinkBtn_Command" ><%# Eval("EName") %></asp:LinkButton>

<asp:Label id="Label1" runat="server"/>

Then it will be available when in your handler:

protected void ENameLinkBtn_Command (object sender, CommandEventArgs e)
{
   Label1.Text = "You chose: " + e.CommandName + " Item " + e.CommandArgument;
}

More info on MSDN

Using Apache POI how to read a specific excel column

Please be aware, that iterating through the columns using row cell iterator ( Iterator<Cell> cellIterator = row.cellIterator();) may lead to silent skipping columns. I have just encountered a document that was exposing such behaviour.

Iterating using indexes in a for loop and using row.getCell(i) was not skipping columns and was returning values at the correct column indexes.

jQuery click events not working in iOS

Recently when working on a web app for a client, I noticed that any click events added to a non-anchor element didn't work on the iPad or iPhone. All desktop and other mobile devices worked fine - but as the Apple products are the most popular mobile devices, it was important to get it fixed.

Turns out that any non-anchor element assigned a click handler in jQuery must either have an onClick attribute (can be empty like below):

onClick=""

OR

The element css needs to have the following declaration:

cursor:pointer

Strange, but that's what it took to get things working again!
source:http://www.mitch-solutions.com/blog/17-ipad-jquery-live-click-events-not-working

TypeError: method() takes 1 positional argument but 2 were given

In Python, this:

my_object.method("foo")

...is syntactic sugar, which the interpreter translates behind the scenes into:

MyClass.method(my_object, "foo")

...which, as you can see, does indeed have two arguments - it's just that the first one is implicit, from the point of view of the caller.

This is because most methods do some work with the object they're called on, so there needs to be some way for that object to be referred to inside the method. By convention, this first argument is called self inside the method definition:

class MyNewClass:

    def method(self, arg):
        print(self)
        print(arg)

If you call method("foo") on an instance of MyNewClass, it works as expected:

>>> my_new_object = MyNewClass()
>>> my_new_object.method("foo")
<__main__.MyNewClass object at 0x29045d0>
foo

Occasionally (but not often), you really don't care about the object that your method is bound to, and in that circumstance, you can decorate the method with the builtin staticmethod() function to say so:

class MyOtherClass:

    @staticmethod
    def method(arg):
        print(arg)

...in which case you don't need to add a self argument to the method definition, and it still works:

>>> my_other_object = MyOtherClass()
>>> my_other_object.method("foo")
foo

How to install Anaconda on RaspBerry Pi 3 Model B

I was trying to run this on a pi zero. Turns out the pi zero has an armv6l architecture so the above won't work for pi zero or pi one. Alternatively here I learned that miniconda doesn't have a recent version of miniconda. Instead I used the same instructions posted here to install berryconda3

Conda is now working. Hope this helps those of you interested in running conda on the pi zero!

http://localhost:50070 does not work HADOOP

Try

namenode -format
start-all.sh
stop-all.sh
jps

see namenode and datanode are running and browse

localhost:50070

If localhost:50070 is still not working, then you need to allows ports. So, check

netstat -anp | grep 50070

How to execute mongo commands through shell scripts?

--shell flag can also be used for javascript files

 mongo --shell /path/to/jsfile/test.js 

PL/SQL, how to escape single quote in a string?

You can use literal quoting:

stmt := q'[insert into MY_TBL (Col) values('ER0002')]';

Documentation for literals can be found here.

Alternatively, you can use two quotes to denote a single quote:

stmt := 'insert into MY_TBL (Col) values(''ER0002'')';

The literal quoting mechanism with the Q syntax is more flexible and readable, IMO.

Mockito verify order / sequence of method calls

With BDD it's

@Test
public void testOrderWithBDD() {


    // Given
    ServiceClassA firstMock = mock(ServiceClassA.class);
    ServiceClassB secondMock = mock(ServiceClassB.class);

    //create inOrder object passing any mocks that need to be verified in order
    InOrder inOrder = inOrder(firstMock, secondMock);

    willDoNothing().given(firstMock).methodOne();
    willDoNothing().given(secondMock).methodTwo();

    // When
    firstMock.methodOne();
    secondMock.methodTwo();

    // Then
    then(firstMock).should(inOrder).methodOne();
    then(secondMock).should(inOrder).methodTwo();


}

awk without printing newline

The ORS (output record separator) variable in AWK defaults to "\n" and is printed after every line. You can change it to " " in the BEGIN section if you want everything printed consecutively.

Which data type for latitude and longitude?

In PostGIS Geometry is preferred over Geography (round earth model) because the computations are much simpler therefore faster. It also has MANY more available functions but is less accurate over very long distances.

Import your CSV long and lat fields to DECIMAL(10,6) columns. 6 digits is 10cm precision, should be plenty for most use cases. Then cast your imported data to the correct SRID

The wrong way!

/* try what seems the obvious solution */
DROP TABLE IF EXISTS public.test_geom_bad;
-- Big Ben, London
SELECT ST_SetSRID(ST_MakePoint(-0.116773, 51.510357),4326) AS geom
INTO public.test_geom_bad;

The CORRECT way

/* add the necessary CAST to make it work */
DROP TABLE IF EXISTS public.test_geom_correct;
SELECT ST_SetSRID(ST_MakePoint(-0.116773, 51.510357),4326)::geometry(Geometry, 4326) AS geom
INTO public.test_geom_correct;

Verify SRID is not zero!

/* now observe the incorrect SRID 0 */
SELECT * FROM public.geometry_columns
WHERE f_table_name IN ('test_geom_bad','test_geom_correct');

Validate the order of your long lat parameter using a WKT viewer and

SELECT ST_AsEWKT(geom) FROM public.test_geom_correct

Then index it for best performance

CREATE INDEX idx_target_table_geom_gist
    ON target_table USING gist(geom);

How to create a static library with g++?

You can create a .a file using the ar utility, like so:

ar crf lib/libHeader.a header.o

lib is a directory that contains all your libraries. it is good practice to organise your code this way and separate the code and the object files. Having everything in one directory generally looks ugly. The above line creates libHeader.a in the directory lib. So, in your current directory, do:

mkdir lib

Then run the above ar command.

When linking all libraries, you can do it like so:

g++ test.o -L./lib -lHeader -o test  

The -L flag will get g++ to add the lib/ directory to the path. This way, g++ knows what directory to search when looking for libHeader. -llibHeader flags the specific library to link.

where test.o is created like so:

g++ -c test.cpp -o test.o 

How to float a div over Google Maps?

Just set the position of the div and you may have to set the z-index.

ex.

div#map-div {
    position: absolute;
    left: 10px;
    top: 10px;
}
div#cover-div {
    position:absolute;
    left:10px;
    top: 10px;
    z-index:3;
}

Get list of data-* attributes using javascript / jQuery

you could access the data using $('#prod')[0].dataset

How to insert an object in an ArrayList at a specific position

This method Appends the specified element to the end of this list.

add(E e) //append element to the end of the arraylist.

This method Inserts the specified element at the specified position in this list.

void add(int index, E element) //inserts element at the given position in the array list.

This method Replaces the element at the specified position in this list with the specified element.

set(int index, E element) //Replaces the element at the specified position in this list with the specified element.
      

      

How can I use random numbers in groovy?

If you want to generate random numbers in range including '0' , use the following while 'max' is the maximum number in the range.

Random rand = new Random()
random_num = rand.nextInt(max+1)

How to copy an object by value, not by reference

what language is this? If you're using a language that passes everything by reference like Java (except for native types), typically you can call .clone() method. The .clone() method is typically implemented by copying/cloning all relevant instance fields into the new object.

How do I launch a program from command line without opening a new cmd window?

20190907

OS: Win 10

I'm making an exe in c++, for some reason usting START make my program fail.

So, just use quotes:

"c:\folder\program.exe"

How to use a Bootstrap 3 glyphicon in an html select

I ended up using the bootstrap 3 dropdown button, I'm posting my solution here in case it helps someone in future. Adding the bootstrap 3 list-inline to the class for the ul causes it to display in a nicely compact format as well.

<div class="btn-group">
    <button type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown">
        Select icon <span class="caret"></span>
    </button>
    <ul class="dropdown-menu list-inline" role="menu">
        <li><span class="glyphicon glyphicon-cutlery"></span></li>
        <li><span class="glyphicon glyphicon-fire"></span></li>
        <li><span class="glyphicon glyphicon-glass"></span></li>
        <li><span class="glyphicon glyphicon-heart"></span></li>          
    </ul>
</div>

I'm using Angular.js so this is the actual code I used:

<div class="btn-group">
            <button type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown">
                Avatar <span class="caret"></span>
            </button>
            <ul class="dropdown-menu list-inline" role="menu">
                <li ng-repeat="avatar in avatars" ng-click="avatarSelected(avatar)">
                    <span ng-class="getAvatar(avatar)"></span>
                </li>
            </ul>
        </div>

And in my controller:

$scope.avatars=['cutlery','eye-open','flag','flash','glass','fire','hand-right','heart','heart-empty','leaf','music','send','star','star-empty','tint','tower','tree-conifer','tree-deciduous','usd','user','wrench','time','road','cloud'];

$scope.getAvatar=function(avatar){
     return 'glyphicon glyphicon-'+avatar;
};

How do I 'git diff' on a certain directory?

Provide a path (myfolder in this case) and just run:

git diff myfolder/

Fill DataTable from SQL Server database

Try with following:

public DataTable fillDataTable(string table)
    {
        string query = "SELECT * FROM dstut.dbo." +table;

        SqlConnection sqlConn = new SqlConnection(conSTR);
        sqlConn.Open();
        SqlCommand cmd = new SqlCommand(query, sqlConn);
        SqlDataAdapter da=new SqlDataAdapter(cmd);
        DataTable dt = new DataTable();
        da.Fill(dt);
        sqlConn.Close();
        return dt;
    }

Hope it is helpful.

Xpath for href element

Below works fine.

//a[@id='oldcontent']

If you've tried certain ones and they haven't worked, then let us know, otherwise something simple like this should work.

Storing and Retrieving ArrayList values from hashmap

for (Map.Entry<String, ArrayList<Integer>> entry : map.entrySet()) {
 System.out.println( entry.getKey());     
 System.out.println( entry.getValue());//Returns the list of values
}

How to set the background image of a html 5 canvas to .png image

As shown in this example, you can apply a background to a canvas element through CSS and this background will not be considered part the image, e.g. when fetching the contents through toDataURL().

Here are the contents of the example, for Stack Overflow posterity:

<!DOCTYPE HTML>
<html><head>
  <meta charset="utf-8">
  <title>Canvas Background through CSS</title>
  <style type="text/css" media="screen">
    canvas, img { display:block; margin:1em auto; border:1px solid black; }
    canvas { background:url(lotsalasers.jpg) }
  </style>
</head><body>
<canvas width="800" height="300"></canvas>
<img>
<script type="text/javascript" charset="utf-8">
  var can = document.getElementsByTagName('canvas')[0];
  var ctx = can.getContext('2d');
  ctx.strokeStyle = '#f00';
  ctx.lineWidth   = 6;
  ctx.lineJoin    = 'round';
  ctx.strokeRect(140,60,40,40);
  var img = document.getElementsByTagName('img')[0];
  img.src = can.toDataURL();
</script>
</body></html>

Create a SQL query to retrieve most recent records

Another easy way:

SELECT Date, User, Status, Notes  
FROM Test_Most_Recent 
WHERE Date in ( SELECT MAX(Date) from Test_Most_Recent group by User)

How do you push just a single Git branch (and no other branches)?

Minor update on top of Karthik Bose's answer - you can configure git globally, to affect all of your workspaces to behave that way:

git config --global push.default upstream

"No such file or directory" but it exists

Below command worked on 16.4 Ubuntu

This issue comes when your .sh file is corrupt or not formatted as per unix protocols.

dos2unix converts the .sh file to Unix format!

sudo apt-get install dos2unix -y
dos2unix test.sh
sudo chmod u+x test.sh 
sudo ./test.sh

Is it valid to define functions in JSON results?

It is not standard as far as I know. A quick look at http://json.org/ confirms this.

Getting ssh to execute a command in the background on target machine

It appeared quite convenient for me to have a remote tmux session using the tmux new -d <shell cmd> syntax like this:

ssh someone@elsewhere 'tmux new -d sleep 600'

This will launch new session on elsewhere host and ssh command on local machine will return to shell almost instantly. You can then ssh to the remote host and tmux attach to that session. Note that there's nothing about local tmux running, only remote!

Also, if you want your session to persist after the job is done, simply add a shell launcher after your command, but don't forget to enclose in quotes:

ssh someone@elsewhere 'tmux new -d "~/myscript.sh; bash"'

Capturing mobile phone traffic on Wireshark

For Android phone I used tPacketCapture: https://play.google.com/store/apps/details?id=jp.co.taosoftware.android.packetcapture&hl=en

This app was a lifesaver I was debugging a problem with failure of SSL/TLS handshake on my Android app. Tried to setup ad hoc networking so I could use wireshark on my laptop. It did not work for me. This app quickly allowed me to capture network traffic, share it on my Google Drive so I could download on my laptop where I could examine it with Wireshark! Awesome and no root required!

Unable to read repository at http://download.eclipse.org/releases/indigo

For eclipse, there are normally different options available:

  • If you want to use the PHP development environment (only), you should go with the corresponding distro of eclipse. There is a distro for PHP provided by Zend.
  • You may add PDT to an indigo release by doing the following steps:
    • Check if an update site for PDT is included in your eclipse installation:
      1. Open the Help > Install New Software dialog.
      2. Click there on the link Available Software Sites.
      3. In the list, the URL http://download.eclipse.org/releases/indigo should be marked.
      4. Close the dialog.
    • Select from the Work with list the site with the right URL.
    • Enter in the filter box PDT and search in the list for the PDT tooling you want to install. enter image description here
    • Install the PDT tooling.
  • If that does not work, you may download a complete update site from the PDT project site.
    1. Visit the site (URL above).
    2. Click on downloads.
    3. Search there for the string "all in one update site".
    4. Download the zip file.
    5. Install it in your Indigo installation. Help > Install New Software > Add... > Enter name and select from button Archive the zip file

I hope some of the installation instructions will work for you.

possibly undefined macro: AC_MSG_ERROR

I have experienced this same problem under CentOS 7

In may case, the problem went off after installation of libcurl-devel (libcurl was already installed on this machine)

What is the difference between active and passive FTP?

Active mode: -server initiates the connection.

Passive mode: -client initiates the connection.

Read only file system on Android

Here is what worked for me. I was running an emulated Android 7.1.1 (Nougat) device.

On a terminal, I hit the following command. One thing to be noticed is the -writable-system flag

./emulator -writable-system -avd Nexus_6_API_25  -partition-size 280

On another tab

./adb shell
su
mount -o rw,remount -t ext4 /dev/block/vda /system

All the changes that you do on the /system contents will survive a restart.

Find index of last occurrence of a substring in a string

Try this:

s = 'hello plombier pantin'
print (s.find('p'))
6
print (s.index('p'))
6
print (s.rindex('p'))
15
print (s.rfind('p'))

Limit characters displayed in span

You can use css ellipsis; but you have to give fixed width and overflow:hidden: to that element.

_x000D_
_x000D_
<span style="display:block;text-overflow: ellipsis;width: 200px;overflow: hidden; white-space: nowrap;">_x000D_
 Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat._x000D_
 </span>
_x000D_
_x000D_
_x000D_

AWS ssh access 'Permission denied (publickey)' issue

For my ubuntu images, it is actually ubuntu user and NOT the ec2-user ;)

Mounting multiple volumes on a docker container?

You can use -v option multiple times in docker run command to mount multiple directory in container:

docker run -t -i \
  -v '/on/my/host/test1:/on/the/container/test1' \
  -v '/on/my/host/test2:/on/the/container/test2' \
  ubuntu /bin/bash

What is the proper REST response code for a valid request but an empty data?

In previous projects, I've used 404. If there's no user 9, then the object was not found. Therefore 404 Not Found is appropriate.

For object exists, but there is no data, 204 No Content would be appropriate. I think in your case, the object does not exist though.

Remove part of string after "."

You just need to escape the period:

a <- c("NM_020506.1","NM_020519.1","NM_001030297.2","NM_010281.2","NM_011419.3", "NM_053155.2")

gsub("\\..*","",a)
[1] "NM_020506"    "NM_020519"    "NM_001030297" "NM_010281"    "NM_011419"    "NM_053155" 

SQL Server IF NOT EXISTS Usage?

Have you verified that there is in fact a row where Staff_Id = @PersonID? What you've posted works fine in a test script, assuming the row exists. If you comment out the insert statement, then the error is raised.

set nocount on

create table Timesheet_Hours (Staff_Id int, BookedHours int, Posted_Flag bit)

insert into Timesheet_Hours (Staff_Id, BookedHours, Posted_Flag) values (1, 5.5, 0)

declare @PersonID int
set @PersonID = 1

IF EXISTS    
    (
    SELECT 1    
    FROM Timesheet_Hours    
    WHERE Posted_Flag = 1    
        AND Staff_Id = @PersonID    
    )    
    BEGIN
        RAISERROR('Timesheets have already been posted!', 16, 1)
        ROLLBACK TRAN
    END
ELSE
    IF NOT EXISTS
        (
        SELECT 1
        FROM Timesheet_Hours
        WHERE Staff_Id = @PersonID
        )
        BEGIN
            RAISERROR('Default list has not been loaded!', 16, 1)
            ROLLBACK TRAN
        END
    ELSE
        print 'No problems here'

drop table Timesheet_Hours

How to communicate between iframe and the parent site?

the window.top property should be able to give what you need.

E.g.

alert(top.location.href)

See http://cross-browser.com/talk/inter-frame_comm.html

Exposing the current state name with ui router

Its just because of the load time angular takes to give you the current state.

If you try to get the current state by using $timeout function then it will give you correct result in $state.current.name

$timeout(function(){
    $rootScope.currState = $state.current.name;
})

Failed to allocate memory: 8

In my case:

  • Using built in WXGA720 to simulate 720p device, always got this error
  • Manually set AVD resolution to 720 x 1280, works for me

hope it helps~

Storing Form Data as a Session Variable

Yes this is possible. kizzie is correct with the session_start(); having to go first.

another observation I made is that you need to filter your form data using:

strip_tags($value);

and/or

stripslashes($value);

How to concatenate variables into SQL strings

You could make use of Prepared Stements like this.

set @query = concat( "select name from " );
set @query = concat( "table_name"," [where condition] " );

prepare stmt from @like_q;
execute stmt;

Using JQuery to open a popup window and print

Are you sure you can't alter the HTML in the popup window?

If you can, add a <script> tag at the end of the popup's HTML, and call window.print() inside it. Then it won't be called until the HTML has loaded.

How to unnest a nested list

Use itertools.chain:

itertools.chain(*iterables):

Make an iterator that returns elements from the first iterable until it is exhausted, then proceeds to the next iterable, until all of the iterables are exhausted. Used for treating consecutive sequences as a single sequence.

Example:

from itertools import chain

A = [[1,2], [3,4]]

print list(chain(*A))
# or better: (available since Python 2.6)
print list(chain.from_iterable(A))

The output is:

[1, 2, 3, 4]
[1, 2, 3, 4]

How to delete a record in Django models?

you can delete the objects directly from the admin panel or else there is also an option to delete specific or selected id from an interactive shell by typing in python3 manage.py shell (python3 in Linux). If you want the user to delete the objects through the browser (with provided visual interface) e.g. of an employee whose ID is 6 from the database, we can achieve this with the following code, emp = employee.objects.get(id=6).delete()

THIS WILL DELETE THE EMPLOYEE WITH THE ID is 6.

If you wish to delete the all of the employees exist in the DB instead of get(), specify all() as follows: employee.objects.all().delete()

Convert Base64 string to an image file?

You need to remove the part that says data:image/png;base64, at the beginning of the image data. The actual base64 data comes after that.

Just strip everything up to and including base64, (before calling base64_decode() on the data) and you'll be fine.

Access to the path is denied

I had exactly the same problem.

The solution was that the file I was trying to access was readonly, as it was copied from a template file that was readonly.

<facepalm />

Split string into list in jinja?

After coming back to my own question after 5 year and seeing so many people found this useful, a little update.

A string variable can be split into a list by using the split function (it can contain similar values, set is for the assignment) . I haven't found this function in the official documentation but it works similar to normal Python. The items can be called via an index, used in a loop or like Dave suggested if you know the values, it can set variables like a tuple.

{% set list1 = variable1.split(';') %}
The grass is {{ list1[0] }} and the boat is {{ list1[1] }}

or

{% set list1 = variable1.split(';') %}
{% for item in list1 %}
    <p>{{ item }}<p/>
{% endfor %} 

or

{% set item1, item2 = variable1.split(';') %}
The grass is {{ item1 }} and the boat is {{ item2 }}

ggplot2 plot without axes, legends, etc

Re: changing opts to theme etc (for lazy folks):

theme(axis.line=element_blank(),
      axis.text.x=element_blank(),
      axis.text.y=element_blank(),
      axis.ticks=element_blank(),
      axis.title.x=element_blank(),
      axis.title.y=element_blank(),
      legend.position="none",
      panel.background=element_blank(),
      panel.border=element_blank(),
      panel.grid.major=element_blank(),
      panel.grid.minor=element_blank(),
      plot.background=element_blank())

Convert a string to a datetime

Nobody mentioned this, but in some cases the other method fails to recognize the datetime...

You can try this instead, which will convert the specified string representation of a date and time to an equivalent date and time value

string iDate = "05/05/2005";
DateTime oDate = Convert.ToDateTime(iDate);
MessageBox.Show(oDate.Day + " " + oDate.Month + "  " + oDate.Year );

Fail to create Android virtual Device, "No system image installed for this Target"

I had android sdk and android studio installed separately in my system. Android studio had installed its own sdk. After I deleted the stand-alone android sdk, the issue of "“No system image installed for this Target” was gone.

Is there way to use two PHP versions in XAMPP?

Unless it has to be absolutely and definitely XAMPP, you can try to get what you want with WAMP. WAMP is pretty much the same thing in different package.

Once you have it installed, you can just switch between php versions here:

enter image description here

You can install as many versions of PHP as you need.

Here's how it is done in detail.

Just go here: WAMP download

Then select your base server, e.g. latest with php7.

Then, when WAMP 3 is installed, go to folder: addons and select php version (or versions) you are after. They offer php flavors starting from php 5.3.29, which should work with mysql_connect.

To install addon, during installation (double click exe file) just point to folder where you have your WAMP 3 installed.

Then you can use content of other folders, like: applications etc. to add more functionality

Everything's interfaced, so you can concentrate on coding and not hacking your environment.

How do I specify unique constraint for multiple columns in MySQL?

I do it like this:

CREATE UNIQUE INDEX index_name ON TableName (Column1, Column2, Column3);

My convention for a unique index_name is TableName_Column1_Column2_Column3_uindex.

Bulk Insert into Oracle database: Which is better: FOR Cursor loop or a simple Select?

If your rollback segment/undo segment can accomodate the size of the transaction then option 2 is better. Option 1 is useful if you do not have the rollback capacity needed and have to break the large insert into smaller commits so you don't get rollback/undo segment too small errors.

How to delete a workspace in Perforce (using p4v)?

It could also be done without a visual client with the following small script.

$ cat ~/bin/pdel

#!/bin/sh

#Todo: add error handling

( p4 -c $1 client -o | perl -pne 's/\blocked\s//' | p4 -c $1  client -i ) && p4 client -d $1

Find largest and smallest number in an array

You can initialize after filling the array or you can write:

 small =~ unsigned(0)/2; // Using the bit-wise complement to flip 0's bits and dividing by 2 because unsigned can hold twice the +ve value an

integer can hold.

 big =- 1*(small) - 1;

instead of:

big = small = values[0]

because when you write this line before filling the array, big and small values will equal to a random leftover value (as integer is a POD) from the memory and if those numbers are either bigger or smaller than any other value in you array, you will get them as an output.

ZIP file content type for HTTP request

The standard MIME type for ZIP files is application/zip. The types for the files inside the ZIP does not matter for the MIME type.

As always, it ultimately depends on your server setup.

Why would anybody use C over C++?

Joel's answer is good for reasons you might have to use C, though there are a few others:

  • You must meet industry guidelines, which are easier to prove and test for in C
  • You have tools to work with C, but not C++ (think not just about the compiler, but all the support tools, coverage, analysis, etc)
  • Your target developers are C gurus
  • You're writing drivers, kernels, or other low-level code
  • You know the C++ compiler isn't good at optimizing the kind of code you need to write
  • Your app not only doesn't lend itself to be object-oriented but would be harder to write in that form

In some cases, though, you might want to use C rather than C++:

  • You want the performance of assembler without the trouble of coding in assembler (C++ is, in theory, capable of 'perfect' performance, but the compilers aren't as good at seeing optimizations a good C programmer will see)

  • The software you're writing is trivial, or nearly so - whip out the tiny C compiler, write a few lines of code, compile and you're all set - no need to open a huge editor with helpers, no need to write practically empty and useless classes, deal with namespaces, etc. You can do nearly the same thing with a C++ compiler and simply use the C subset, but the C++ compiler is slower, even for tiny programs.

  • You need extreme performance or small code size and know the C++ compiler will actually make it harder to accomplish due to the size and performance of the libraries.

You contend that you could just use the C subset and compile with a C++ compiler, but you'll find that if you do that you'll get slightly different results depending on the compiler.

Regardless, if you're doing that, you're using C. Is your question really "Why don't C programmers use C++ compilers?" If it is, then you either don't understand the language differences, or you don't understand the compiler theory.

how do I make a single legend for many subplots with matplotlib?

I have noticed that no answer display an image with a single legend referencing many curves in different subplots, so I have to show you one... to make you curious...

enter image description here

Now, you want to look at the code, don't you?

from numpy import linspace
import matplotlib.pyplot as plt

# Calling the axes.prop_cycle returns an itertoools.cycle

color_cycle = plt.rcParams['axes.prop_cycle']()

# I need some curves to plot

x = linspace(0, 1, 51)
f1 = x*(1-x)   ; lab1 = 'x - x x'
f2 = 0.25-f1   ; lab2 = '1/4 - x + x x' 
f3 = x*x*(1-x) ; lab3 = 'x x - x x x'
f4 = 0.25-f3   ; lab4 = '1/4 - x x + x x x'

# let's plot our curves (note the use of color cycle, otherwise the curves colors in
# the two subplots will be repeated and a single legend becomes difficult to read)
fig, (a13, a24) = plt.subplots(2)

a13.plot(x, f1, label=lab1, **next(color_cycle))
a13.plot(x, f3, label=lab3, **next(color_cycle))
a24.plot(x, f2, label=lab2, **next(color_cycle))
a24.plot(x, f4, label=lab4, **next(color_cycle))

# so far so good, now the trick

lines_labels = [ax.get_legend_handles_labels() for ax in fig.axes]
lines, labels = [sum(lol, []) for lol in zip(*lines_labels)]

# finally we invoke the legend (that you probably would like to customize...)

fig.legend(lines, labels)
plt.show()

The two lines

lines_labels = [ax.get_legend_handles_labels() for ax in fig.axes]
lines, labels = [sum(lol, []) for lol in zip(*lines_labels)]

deserve an explanation — to this aim I have encapsulated the tricky part in a function, just 4 lines of code but heavily commented

def fig_legend(fig, **kwdargs):

    # generate a sequence of tuples, each contains
    #  - a list of handles (lohand) and
    #  - a list of labels (lolbl)
    tuples_lohand_lolbl = (ax.get_legend_handles_labels() for ax in fig.axes)
    # e.g. a figure with two axes, ax0 with two curves, ax1 with one curve
    # yields:   ([ax0h0, ax0h1], [ax0l0, ax0l1]) and ([ax1h0], [ax1l0])
    
    # legend needs a list of handles and a list of labels, 
    # so our first step is to transpose our data,
    # generating two tuples of lists of homogeneous stuff(tolohs), i.e
    # we yield ([ax0h0, ax0h1], [ax1h0]) and ([ax0l0, ax0l1], [ax1l0])
    tolohs = zip(*tuples_lohand_lolbl)

    # finally we need to concatenate the individual lists in the two
    # lists of lists: [ax0h0, ax0h1, ax1h0] and [ax0l0, ax0l1, ax1l0]
    # a possible solution is to sum the sublists - we use unpacking
    handles, labels = (sum(list_of_lists, []) for list_of_lists in tolohs)

    # call fig.legend with the keyword arguments, return the legend object

    return fig.legend(handles, labels, **kwdargs)

PS I recognize that sum(list_of_lists, []) is a really inefficient method to flatten a list of lists but ? I love its compactness, ? usually is a few curves in a few subplots and ? Matplotlib and efficiency? ;-)


Important Update

If you want to stick with the official Matplotlib API my answer above is perfect, really.

On the other hand, if you don't mind using a private method of the matplotlib.legend module ... it's really much much much easier

from matplotlib.legend import _get_legend_handles_labels
...

fig.legend(*_get_legend_handles_and_labels(fig.axes), ...)

A complete explanation can be found in the source code of Axes.get_legend_handles_labels in .../matplotlib/axes/_axes.py

Sending Email in Android using JavaMail API without using the default/built-in app

In case that you are demanded to keep the jar library as small as possible, you can include the SMTP/POP3/IMAP function separately to avoid the "too many methods in the dex" problem.

You can choose the wanted jar libraries from the javanet web page, for example, mailapi.jar + imap.jar can enable you to access icloud, hotmail mail server in IMAP protocol. (with the help of additional.jar and activation.jar)

Access files in /var/mobile/Containers/Data/Application without jailbreaking iPhone

If this is your app, if you connect the device to your computer, you can use the "Devices" option on Xcode's "Window" menu and then download the app's data container to your computer. Just select your app from the list of installed apps, and click on the "gear" icon and choose "Download Container".

enter image description here

Once you've downloaded it, right click on the file in the Finder and choose "Show Package Contents".

Is it possible to wait until all javascript files are loaded before executing javascript code?

Thats work for me:

var jsScripts = [];

jsScripts.push("/js/script1.js" );
jsScripts.push("/js/script2.js" );
jsScripts.push("/js/script3.js" );

$(jsScripts).each(function( index, value ) {
    $.holdReady( true );
    $.getScript( value ).done(function(script, status) {
        console.log('Loaded ' + index + ' : ' + value + ' (' + status + ')');                
        $.holdReady( false );
    });
});

How can I make a CSS table fit the screen width?

Instead of using the % unit – the width/height of another element – you should use vh and vw.
Your code would be:

your table {
  width: 100vw;
  height: 100vh;
}

But, if the document is smaller than 100vh or 100vw, then you need to set the size to the document's size.

(table).style.width = window.innerWidth;
(table).style.height = window.innerHeight;

How to Validate on Max File Size in Laravel?

According to the documentation:

$validator = Validator::make($request->all(), [
    'file' => 'max:500000',
]);

The value is in kilobytes. I.e. max:10240 = max 10 MB.

Why doesn't file_get_contents work?

Check file_get_contents PHP Manual return value. If the value is FALSE then it could not read the file. If the value is NULL then the function itself is disabled.

To learn more what might gone wrong with the file_get_contents operation you must enable error reporting and the display of errors to actually read them.

# Enable Error Reporting and Display:
error_reporting(~0);
ini_set('display_errors', 1);

You can get more details about the why the call is failing by checking the INI values on your server. One value the directly effects the file_get_contents function is allow_url_fopen. You can do this by running the following code. You should note, that if it reports that fopen is not allowed, then you'll have to ask your provider to change this setting on your server in order for any code that require this function to work with URLs.

<html>
    <head>        
        <title>Test File</title>
        <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false">
        </script>
    </head>
    <body>
<?php

# Enable Error Reporting and Display:
error_reporting(~0);
ini_set('display_errors', 1);

$adr = 'Sydney+NSW';
echo $adr;
$url = "http://maps.googleapis.com/maps/api/geocode/json?address=$adr&sensor=false";
echo '<p>'.$url.'</p>';

$jsonData = file_get_contents($url);

print '<p>', var_dump($jsonData), '</p>';

# Output information about allow_url_fopen:
if (ini_get('allow_url_fopen') == 1) {
    echo '<p style="color: #0A0;">fopen is allowed on this host.</p>';
} else {
    echo '<p style="color: #A00;">fopen is not allowed on this host.</p>';
}


# Decide what to do based on return value:
if ($jsonData === FALSE) {
    echo "Failed to open the URL ", htmlspecialchars($url);
} elseif ($jsonData === NULL) {
    echo "Function is disabled.";
} else {
   echo $jsonData;
}

?>
    </body>
</html>

If all of this fails, it might be due to the use of short open tags, <?. The example code in this answer has been therefore changed to make use of <?php to work correctly as this is guaranteed to work on in all version of PHP, no matter what configuration options are set. To do so for your own script, just replace <? or <?php.

Drawing Isometric game worlds

You could use euclidean distance from the point highest and nearest the viewer, except that is not quite right. It results in spherical sort order. You can straighten that out by looking from further away. Further away the curvature becomes flattened out. So just add say 1000 to each of the x,y and z components to give x',y' and z'. The sort on x'*x'+y'*y'+z'*z'.

URLEncoder not able to translate space character

use character-set "ISO-8859-1" for URLEncoder

Python Pandas : pivot table with aggfunc = count unique distinct

For best performance I recommend doing DataFrame.drop_duplicates followed up aggfunc='count'.

Others are correct that aggfunc=pd.Series.nunique will work. This can be slow, however, if the number of index groups you have is large (>1000).

So instead of (to quote @Javier)

df2.pivot_table('X', 'Y', 'Z', aggfunc=pd.Series.nunique)

I suggest

df2.drop_duplicates(['X', 'Y', 'Z']).pivot_table('X', 'Y', 'Z', aggfunc='count')

This works because it guarantees that every subgroup (each combination of ('Y', 'Z')) will have unique (non-duplicate) values of 'X'.

How do I apply CSS3 transition to all properties except background-position?

Hope not to be late. It is accomplished using only one line!

-webkit-transition: all 0.2s ease-in-out, width 0, height 0, top 0, left 0;
-moz-transition: all 0.2s ease-in-out, width 0, height 0, top 0, left 0;
-o-transition: all 0.2s ease-in-out, width 0, height 0, top 0, left 0;
transition: all 0.2s ease-in-out, width 0, height 0, top 0, left 0; 

That works on Chrome. You have to separate the CSS properties with a comma.

Here is a working example: http://jsfiddle.net/H2jet/

Conditional formatting based on another cell's value

Note: when it says "B5" in the explanation below, it actually means "B{current_row}", so for C5 it's B5, for C6 it's B6 and so on. Unless you specify $B$5 - then you refer to one specific cell.


This is supported in Google Sheets as of 2015: https://support.google.com/drive/answer/78413#formulas

In your case, you will need to set conditional formatting on B5.

  • Use the "Custom formula is" option and set it to =B5>0.8*C5.
  • set the "Range" option to B5.
  • set the desired color

You can repeat this process to add more colors for the background or text or a color scale.

Even better, make a single rule apply to all rows by using ranges in "Range". Example assuming the first row is a header:

  • On B2 conditional formatting, set the "Custom formula is" to =B2>0.8*C2.
  • set the "Range" option to B2:B.
  • set the desired color

Will be like the previous example but works on all rows, not just row 5.

Ranges can also be used in the "Custom formula is" so you can color an entire row based on their column values.

How do I import/include MATLAB functions?

You should be able to put them in your ~/matlab on unix.

I'm not sure which directory matlab looks in for windows, but you should be able to figure it out by executing userpath from the matlab command line.

Specifing width of a flexbox flex item: width or basis?

The bottom statement is equivalent to:

.half {
   flex-grow: 0;
   flex-shrink: 0;
   flex-basis: 50%;
}

Which, in this case, would be equivalent as the box is not allowed to flex and therefore retains the initial width set by flex-basis.

Flex-basis defines the default size of an element before the remaining space is distributed so if the element were allowed to flex (grow/shrink) it may not be 50% of the width of the page.

I've found that I regularly return to https://css-tricks.com/snippets/css/a-guide-to-flexbox/ for help regarding flexbox :)

Check if element is in the list (contains)

You can use std::find

bool found = (std::find(my_list.begin(), my_list.end(), my_var) != my_list.end());

You need to include <algorithm>. It should work on standard containers, vectors lists, etc...

Passing a string array as a parameter to a function java

Feel free to use this how ever you like.

/*
 * The extendStrArray() method will takes a number "n" and
 * a String Array "strArray" and will return a new array
 * containing 'n' new positions. This new returned array
 * can then be assigned to a new array, or the existing
 * one to "extend" it, it contain the old value in the 
 * new array with the addition n empty positions.
 */
private String[] extendStrArray(int n, String[] strArray){
    String[] old_str_array = strArray;
    String[] new_str_array = new String[(old_str_array.length + n)];
    for(int i = 0; i < old_str_array.length; i++ ){
        new_str_array[i] = old_str_array[i];
    }//end for loop

    return new_str_array;

}//end extendStrArray()

Basically I would use it like this:

String[] students = {"Tom", "Jeff", "Ashley", "Mary"};
// 4 new students enter the class so we need to extend the string array
students = extendStrArray(4, students); //this will effectively add 4 new empty positions to the "students" array.

Git Checkout warning: unable to unlink files, permission denied

To those who are using Intellij, as @rtconner said this problem is not caused by git. Since your IDE is locked a file(s) git cannot un-link it. So, you need to close your IDE and then try to merge (or whatever you like) it via command line.

Attach (open) mdf file database with SQL Server Management Studio

I don't know about the older versions but for SSMS 2016 you can go to the Object Explorer and right click on the Databases entry. Then select Attach... in the context menu. Here you can browse to the .mdf file and open it. screenshot

When does a cookie with expiration time 'At end of session' expire?

Just to correct mingos' answer:

If you set the expiration time to 0, the cookie won't be created at all. I've tested this on Google Chrome at least, and when set to 0 that was the result. The cookie, I guess, expires immediately after creation.

To set a cookie so it expires at the end of the browsing session, simply OMIT the expiration parameter altogether.

Example:

Instead of:

document.cookie = "cookie_name=cookie_value; 0; path=/";

Just write:

document.cookie = "cookie_name=cookie_value; path=/";

How to properly express JPQL "join fetch" with "where" clause as JPA 2 CriteriaQuery?

I will show visually the problem, using the great example from James answer and adding the alternative solution.

When you do the follow query, without the FETCH:

Select e from Employee e 
join e.phones p 
where p.areaCode = '613'

You will have the follow results from Employee as you expected:

EmployeeId EmployeeName PhoneId PhoneAreaCode
1 James 5 613
1 James 6 416

But when you add the FETCH word on JOIN, this is what happens:

EmployeeId EmployeeName PhoneId PhoneAreaCode
1 James 5 613

The generated SQL is the same for the two queries, but the Hibernate removes on memory the 416 register when you use WHERE on the FETCH join.

So, to bring all phones and apply the WHERE correctly, you need to have two JOINs: one for the WHERE and another for the FETCH. Like:

Select e from Employee e 
join e.phones p 
join fetch e.phones      //no alias, to not commit the mistake
where p.areaCode = '613'

How to do a join in linq to sql with method syntax?

Justin has correctly shown the expansion in the case where the join is just followed by a select. If you've got something else, it becomes more tricky due to transparent identifiers - the mechanism the C# compiler uses to propagate the scope of both halves of the join.

So to change Justin's example slightly:

var result = from sc in enumerableOfSomeClass
             join soc in enumerableOfSomeOtherClass
             on sc.Property1 equals soc.Property2
             where sc.X + sc.Y == 10
             select new { SomeClass = sc, SomeOtherClass = soc }

would be converted into something like this:

var result = enumerableOfSomeClass
    .Join(enumerableOfSomeOtherClass,
          sc => sc.Property1,
          soc => soc.Property2,
          (sc, soc) => new { sc, soc })
    .Where(z => z.sc.X + z.sc.Y == 10)
    .Select(z => new { SomeClass = z.sc, SomeOtherClass = z.soc });

The z here is the transparent identifier - but because it's transparent, you can't see it in the original query :)

Declaring a variable and setting its value from a SELECT query in Oracle

Not entirely sure what you are after but in PL/SQL you would simply

DECLARE
  v_variable INTEGER;
BEGIN
  SELECT mycolumn
    INTO v_variable
    FROM myTable;
END;

Ollie.

Angular 2 Date Input not binding to date value

In Typescript - app.component.ts file

export class AppComponent implements OnInit {
    currentDate = new Date();
}

In HTML Input field

<input id="form21_1" type="text" tabindex="28" title="DATE" [ngModel]="currentDate | date:'MM/dd/yyyy'" />

It will display the current date inside the input field.

Ruby: character to ascii from a string

puts "string".split('').map(&:ord).to_s

Get a timestamp in C in microseconds?

timespec_get from C11 returns up to nanoseconds, rounded to the resolution of the implementation.

#include <time.h>
struct timespec ts;
timespec_get(&ts, TIME_UTC);
struct timespec {
    time_t   tv_sec;        /* seconds */
    long     tv_nsec;       /* nanoseconds */
};

More details here: https://stackoverflow.com/a/36095407/895245

How to jquery alert confirm box "yes" & "no"

I won't write your code but what you looking for is something like a jquery dialog

take a look here

jQuery modal-confirmation

$(function() {
    $( "#dialog-confirm" ).dialog({
      resizable: false,
      height:140,
      modal: true,
      buttons: {
        "Delete all items": function() {
          $( this ).dialog( "close" );
        },
        Cancel: function() {
          $( this ).dialog( "close" );
        }
      }
    });
  });

<div id="dialog-confirm" title="Empty the recycle bin?">
  <p>
    <span class="ui-icon ui-icon-alert" style="float:left; margin:0 7px 20px 0;"></span>
    These items will be permanently deleted and cannot be recovered. Are you sure?
  </p>
</div>

How do I concatenate strings in Swift?

In Swift 5 apple has introduces Raw Strings using # symbols.

Example:

print(#"My name is "XXX" and I'm "28"."#)
let name = "XXX"
print(#"My name is \#(name)."#)

symbol # is necessary after \. A regular \(name) will be interpreted as characters in the string.

Turning off eslint rule for a specific line

You can add the files which give error to .eslintignore file in your project.Like for all the .vue files just add /*.vue

Hibernate: hbm2ddl.auto=update in production?

It's not safe, not recommended, but it's possible.

I have experience in an application using the auto-update option in production.

Well, the main problems and risks found in this solution are:

  • Deploy in the wrong database. If you commit the mistake to run the application server with a old version of the application (EAR/WAR/etc) in the wrong database... You will have a lot of new columns, tables, foreign keys and errors. The same problem can occur with a simple mistake in the datasource file, (copy/paste file and forgot to change the database). In resume, the situation can be a disaster in your database.
  • Application server takes too long to start. This occur because the Hibernate try to find all created tables/columns/etc every time you start the application. He needs to know what (table, column, etc) needs to be created. This problem will only gets worse as the database tables grows up.
  • Database tools it's almost impossible to use. To create database DDL or DML scripts to run with a new version, you need to think about what will be created by the auto-update after you start the application server. Per example, If you need to fill a new column with some data, you need to start the application server, wait to Hibernate crete the new column and run the SQL script only after that. As can you see, database migration tools (like Flyway, Liquibase, etc) it's almost impossible to use with auto-update enabled.
  • Database changes is not centralized. With the possibility of the Hibernate create tables and everything else, it's hard to watch the changes on database in each version of the application, because most of them are made automatically.
  • Encourages garbage on database. Because of the "easy" use of auto-update, there is a chance your team neglecting to drop old columns and old tables, because the hibernate auto-update can't do that.
  • Imminent disaster. The imminent risk of some disaster to occur in production (like some people mentioned in other answers). Even with an application running and being updated for years, I don't think it's a safe choice. I never felt safe with this option being used.

So, I will not recommend to use auto-update in production.

If you really want to use auto-update in production, I recommend:

  • Separated networks. Your test environment cannot access the homolog environment. This helps prevent a deployment that was supposed to be in the Test environment change the Homologation database.
  • Manage scripts order. You need to organize your scripts to run before your deploy (structure table change, drop table/columns) and script after the deploy (fill information for the new columns/tables).

And, different of the another posts, I don't think the auto-update enabled it's related with "very well paid" DBAs (as mentioned in other posts). DBAs have more important things to do than write SQL statements to create/change/delete tables and columns. These simple everyday tasks can be done and automated by developers and only passed for DBA team to review, not needing Hibernate and DBAs "very well paid" to write them.

Change event on select with knockout binding, how can I know if it is a real change?

I had a similar problem and I just modified the event handler to check the type of the variable. The type is only set after the user selects a value, not when the page is first loaded.

self.permissionChanged = function (l) {
    if (typeof l != 'undefined') {
        ...
    }
}

This seems to work for me.

How to change the default message of the required field in the popover of form-control in bootstrap?

You can use setCustomValidity function when oninvalid event occurs.

Like below:-

<input class="form-control" type="email" required="" 
    placeholder="username" oninvalid="this.setCustomValidity('Please Enter valid email')">
</input>

Update:-

To clear the message once you start entering use oninput="setCustomValidity('') attribute to clear the message.

<input class="form-control" type="email"  required="" placeholder="username"
 oninvalid="this.setCustomValidity('Please Enter valid email')"
 oninput="setCustomValidity('')"></input>

Performing a Stress Test on Web Application?

I had good results with FunkLoad :

  • easy to script user interaction
  • reports are clear
  • can monitor server load

How do I display a decimal value to 2 decimal places?

If you just need this for display use string.Format

String.Format("{0:0.00}", 123.4567m);      // "123.46"

http://www.csharp-examples.net/string-format-double/

The "m" is a decimal suffix. About the decimal suffix:

http://msdn.microsoft.com/en-us/library/364x0z75.aspx

Get full path without filename from path that includes filename

Path.GetDirectoryName() returns the directory name, so for what you want (with the trailing reverse solidus character) you could call Path.GetDirectoryName(filePath) + Path.DirectorySeparatorChar.

Python: how can I check whether an object is of type datetime.date?

import datetime
d = datetime.date(2012, 9, 1)
print type(d) is datetime.date

> True

How do I make a transparent canvas in html5?

I believe you are trying to do exactly what I just tried to do: I want two stacked canvases... the bottom one has a static image and the top one contains animated sprites. Because of the animation, you need to clear the background of the top layer to transparent at the start of rendering every new frame. I finally found the answer: it's not using globalAlpha, and it's not using a rgba() color. The simple, effective answer is:

context.clearRect(0,0,width,height);

How can I change NULL to 0 when getting a single value from a SQL function?

The easiest way to do this is just to add zero to your result.

i.e.

$A=($row['SUM'Price']+0);
echo $A;

hope this helps!!

Generator expressions vs. list comprehensions

Use list comprehensions when the result needs to be iterated over multiple times, or where speed is paramount. Use generator expressions where the range is large or infinite.

See Generator expressions and list comprehensions for more info.

Difference between onStart() and onResume()

Reference to http://developer.android.com/training/basics/activity-lifecycle/starting.html

onResume() Called just before the activity starts interacting with the user. At this point the activity is at the top of the activity stack, with user input going to it. Always followed by onPause().

onPause() Called when the system is about to start resuming another activity. This method is typically used to commit unsaved changes to persistent data, stop animations and other things that may be consuming CPU, and so on. It should do whatever it does very quickly, because the next activity will not be resumed until it returns. Followed either by onResume() if the activity returns back to the front, or by onStop() if it becomes invisible to the user.

How to create named and latest tag in Docker?

Variation of Aaron's answer. Using sed without temporary files

#!/bin/bash
VERSION=1.0.0
IMAGE=company/image
ID=$(docker build  -t ${IMAGE}  .  | tail -1 | sed 's/.*Successfully built \(.*\)$/\1/')

docker tag ${ID} ${IMAGE}:${VERSION}
docker tag -f ${ID} ${IMAGE}:latest

How can I solve "Non-static method xxx:xxx() should not be called statically in PHP 5.4?

You can either remove E_STRICT from error_reporting(), or you can simply make your method static, if you need to call it statically. As far as I know, there is no (strict) way to have a method that can be invoked both as static and non-static method. Also, which is more annoying, you cannot have two methods with the same name, one being static and the other non-static.

.bashrc at ssh login

For an excellent resource on how bash invocation works, what dotfiles do what, and how you should use/configure them, read this:

How to select the row with the maximum value in each group

Here's another data.table solution, since which.max does not work on characters

library(data.table)
group <- data.table(Subject=ID, pt=Value, Event=Event)

group[, .SD[order(pt, decreasing = TRUE) == 1], by = Subject]

String.equals() with multiple conditions (and one action on result)

if (Arrays.asList("John", "Mary", "Peter").contains(name)) {
}
  • This is not as fast as using a prepared Set, but it performs no worse than using OR.
  • This doesn't crash when name is NULL (same with Set).
  • I like it because it looks clean

Explaining the 'find -mtime' command

+1 means 2 days ago. It's rounded.

Creating a div element inside a div element in javascript

Your code works well you just mistyped this line of code:

document.getElementbyId('lc').appendChild(element);

change it with this: (The "B" should be capitalized.)

document.getElementById('lc').appendChild(element);  

HERE IS MY EXAMPLE:

_x000D_
_x000D_
<html>_x000D_
<head>_x000D_
_x000D_
<script>_x000D_
_x000D_
function test() {_x000D_
_x000D_
    var element = document.createElement("div");_x000D_
    element.appendChild(document.createTextNode('The man who mistook his wife for a hat'));_x000D_
    document.getElementById('lc').appendChild(element);_x000D_
_x000D_
}_x000D_
_x000D_
</script>_x000D_
_x000D_
</head>_x000D_
<body>_x000D_
<input id="filter" type="text" placeholder="Enter your filter text here.." onkeyup = "test()" />_x000D_
_x000D_
<div id="lc" style="background: blue; height: 150px; width: 150px;_x000D_
}" onclick="test();">  _x000D_
</div>_x000D_
</body>_x000D_
_x000D_
</html>
_x000D_
_x000D_
_x000D_

Why are empty catch blocks a bad idea?

An empty catch block is essentially saying "I don't want to know what errors are thrown, I'm just going to ignore them."

It's similar to VB6's On Error Resume Next, except that anything in the try block after the exception is thrown will be skipped.

Which doesn't help when something then breaks.

Git merge error "commit is not possible because you have unmerged files"

If you have fixed the conflicts you need to add the files to the stage with git add [filename], then commit as normal.

What are invalid characters in XML

For XSL (on really lazy days) I use:

capture="&amp;(?!amp;)" capturereplace="&amp;amp;"

to translate all &-signs that aren't follwed på amp; to proper ones.

We have cases where the input is in CDATA but the system which uses the XML doesn't take it into account. It's a sloppy fix, beware...

Best way to combine two or more byte arrays in C#

Here's a generalization of the answer provided by @Jon Skeet. It is basically the same, only it is usable for any type of array, not only bytes:

public static T[] Combine<T>(T[] first, T[] second)
{
    T[] ret = new T[first.Length + second.Length];
    Buffer.BlockCopy(first, 0, ret, 0, first.Length);
    Buffer.BlockCopy(second, 0, ret, first.Length, second.Length);
    return ret;
}

public static T[] Combine<T>(T[] first, T[] second, T[] third)
{
    T[] ret = new T[first.Length + second.Length + third.Length];
    Buffer.BlockCopy(first, 0, ret, 0, first.Length);
    Buffer.BlockCopy(second, 0, ret, first.Length, second.Length);
    Buffer.BlockCopy(third, 0, ret, first.Length + second.Length,
                     third.Length);
    return ret;
}

public static T[] Combine<T>(params T[][] arrays)
{
    T[] ret = new T[arrays.Sum(x => x.Length)];
    int offset = 0;
    foreach (T[] data in arrays)
    {
        Buffer.BlockCopy(data, 0, ret, offset, data.Length);
        offset += data.Length;
    }
    return ret;
}

A regex for version number parsing

I had a requirement to search/match for version numbers, that follows maven convention or even just single digit. But no qualifier in any case. It was peculiar, it took me time then I came up with this:

'^[0-9][0-9.]*$'

This makes sure the version,

  1. Starts with a digit
  2. Can have any number of digit
  3. Only digits and '.' are allowed

One drawback is that version can even end with '.' But it can handle indefinite length of version (crazy versioning if you want to call it that)

Matches:

  • 1.2.3
  • 1.09.5
  • 3.4.4.5.7.8.8.
  • 23.6.209.234.3

If you are not unhappy with '.' ending, may be you can combine with endswith logic

Convert Bitmap to File

Hope it will help u:

//create a file to write bitmap data
File f = new File(context.getCacheDir(), filename);
f.createNewFile();

//Convert bitmap to byte array
Bitmap bitmap = your bitmap;
ByteArrayOutputStream bos = new ByteArrayOutputStream();
bitmap.compress(CompressFormat.PNG, 0 /*ignored for PNG*/, bos);
byte[] bitmapdata = bos.toByteArray();

//write the bytes in file
FileOutputStream fos = new FileOutputStream(f);
fos.write(bitmapdata);
fos.flush();
fos.close();

Hide header in stack navigator React navigation

You can hide StackNavigator header like this:

const Stack = createStackNavigator();
function StackScreen() {
    return (
        <Stack.Navigator
            screenOptions={{ headerShown: false }}>
            <Stack.Screen name="Login" component={Login} />
            <Stack.Screen name="Training" component={Training} />
            <Stack.Screen name="Course" component={Course} />
            <Stack.Screen name="Signup" component={Signup} />
        </Stack.Navigator>
    );
}

Deleting folders in python recursively

The default behavior of os.walk() is to walk from root to leaf. Set topdown=False in os.walk() to walk from leaf to root.

Any way to replace characters on Swift String?

Swift 3, Swift 4, Swift 5 Solution

let exampleString = "Example string"

//Solution suggested above in Swift 3.0
let stringToArray = exampleString.components(separatedBy: " ")
let stringFromArray = stringToArray.joined(separator: "+")

//Swiftiest solution
let swiftyString = exampleString.replacingOccurrences(of: " ", with: "+")

Maven Unable to locate the Javac Compiler in:

It depends on of Maven version. When you will install newer version of Maven, this error would not appear. You may also add another directory with tools.jar file lib/tools.jar - it also solve this problem.

ls command: how can I get a recursive full-path listing, one line per file?

The easiest way for all you future people is simply:

du

This however, also shows the size of whats contained in each folder You can use awk to output only the folder name:

du | awk '{print $2}'

Edit- Sorry sorry, my bad. I thought it was only folders that were needed. Ill leave this here in case anyone in the future needs it anyways...

npm start error with create-react-app

I fix this using this following command:

npm install -g react-scripts

What is the difference between venv, pyvenv, pyenv, virtualenv, virtualenvwrapper, pipenv, etc?

UPDATE 20200825:

Added below "Conclusion" paragraph

I've went down the pipenv rabbit hole (it's a deep and dark hole indeed...) and since the last answer is over 2 years ago, felt it was useful to update the discussion with the latest developments on the Python virtual envelopes topic I've found.

DISCLAIMER:

This answer is NOT about continuing the raging debate about the merits of pipenv versus venv as envelope solutions- I make no endorsement of either. It's about PyPA endorsing conflicting standards and how future development of virtualenv promises to negate making an either/or choice between them at all. I focused on these two tools precisely because they are the anointed ones by PyPA.

venv

As the OP notes, venv is a tool for virtualizing environments. NOT a third party solution, but native tool. PyPA endorses venv for creating VIRTUAL ENVELOPES: "Changed in version 3.5: The use of venv is now recommended for creating virtual environments".

pipenv

pipenv- like venv - can be used to create virtual envelopes but additionally rolls-in package management and vulnerability checking functionality. Instead of using requirements.txt, pipenv delivers package management via Pipfile. As PyPA endorses pipenv for PACKAGE MANAGEMENT, that would seem to imply pipfile is to supplant requirements.txt.

HOWEVER: pipenv uses virtualenv as its tool for creating virtual envelopes, NOT venv which is endorsed by PyPA as the go-to tool for creating virtual envelopes.

Conflicting Standards:

So if settling on a virtual envelope solution wasn't difficult enough, we now have PyPA endorsing two different tools which use different virtual envelope solutions. The raging Github debate on venv vs virtualenv which highlights this conflict can be found here.

Conflict Resolution:

The Github debate referenced in above link has steered virtualenv development in the direction of accommodating venv in future releases:

prefer built-in venv: if the target python has venv we'll create the environment using that (and then perform subsequent operations on that to facilitate other guarantees we offer)

Conclusion:

So it looks like there will be some future convergence between the two rival virtual envelope solutions, but as of now pipenv- which uses virtualenv - varies materially from venv.

Given the problems pipenv solves and the fact that PyPA has given its blessing, it appears to have a bright future. And if virtualenv delivers on its proposed development objectives, choosing a virtual envelope solution should no longer be a case of either pipenv OR venv.

Update 20200825:

An oft repeated criticism of Pipenv I saw when producing this analysis was that it was not actively maintained. Indeed, what's the point of using a solution whose future could be seen questionable due to lack of continuous development? After a dry spell of about 18 months, Pipenv is once again being actively developed. Indeed, large and material updates have since been released.

Bootstrap Columns Not Working

While this does not address the OP's question, I had trouble with my bootstrap rows / columns while trying to use them in conjunction with Kendo ListView (even with the bootstrap-kendo css).

Adding the following css fixed the problem for me:

#myListView.k-widget, #catalog-items.k-widget * {
    -webkit-box-sizing: border-box;
    box-sizing: border-box;
}

ConnectionTimeout versus SocketTimeout

A connection timeout occurs only upon starting the TCP connection. This usually happens if the remote machine does not answer. This means that the server has been shut down, you used the wrong IP/DNS name, wrong port or the network connection to the server is down.

A socket timeout is dedicated to monitor the continuous incoming data flow. If the data flow is interrupted for the specified timeout the connection is regarded as stalled/broken. Of course this only works with connections where data is received all the time.

By setting socket timeout to 1 this would require that every millisecond new data is received (assuming that you read the data block wise and the block is large enough)!

If only the incoming stream stalls for more than a millisecond you are running into a timeout.

Spark SQL: apply aggregate functions to a list of columns

Current answers are perfectly correct on how to create the aggregations, but none actually address the column alias/renaming that is also requested in the question.

Typically, this is how I handle this case:

val dimensionFields = List("col1")
val metrics = List("col2", "col3", "col4")
val columnOfInterests = dimensions ++ metrics

val df = spark.read.table("some_table"). 
    .select(columnOfInterests.map(c => col(c)):_*)
    .groupBy(dimensions.map(d => col(d)): _*)
    .agg(metrics.map( m => m -> "sum").toMap)
    .toDF(columnOfInterests:_*)    // that's the interesting part

The last line essentially renames every columns of the aggregated dataframe to the original fields, essentially changing sum(col2) and sum(col3) to simply col2 and col3.

jQuery bind/unbind 'scroll' event on $(window)

try this:

$(window).unbind('scroll');

it works in my project

How can I get the current screen orientation?

int rotation =  getWindowManager().getDefaultDisplay().getRotation();

this will gives all orientation like normal and reverse

and handle it like

int angle = 0;
switch (rotation) {
    case Surface.ROTATION_90:
        angle = -90;
        break;
    case Surface.ROTATION_180:
        angle = 180;
        break;
    case Surface.ROTATION_270:
        angle = 90;
        break;
    default:
        angle = 0;
        break;
}

Insert string at specified position

str_replace($sub_str, $insert_str.$sub_str, $org_str);

Cannot insert explicit value for identity column in table 'table' when IDENTITY_INSERT is set to OFF

don't put value to OperationID because it will be automatically generated. try this:

Insert table(OpDescription,FilterID) values ('Hierachy Update',1)

Simple CSS Animation Loop – Fading In & Out "Loading" Text

To make more than one element fade in/out sequentially such as 5 elements fade each 4s,

1- make unique animation for each element with animation-duration equal to [ 4s (duration for each element) * 5 (number of elements) ] = 20s

animation-name: anim1 , anim2, anim3 ... 
animation-duration : 20s, 20s, 20s ... 

2- get animation keyframe for each element.

100% (keyframes percentage) / 5 (elements) = 20% (frame for each element)

3- define starting and ending point for each animation:

each animation has 20% frame length and @keyframes percentage always starts from 0%, so first animation will start from 0% and end in his frame(20%), and each next animation will starts from previous animation ending point and end when it reach his frame (+20% ),

@keyframes animation1 { 0% {}, 20% {}}
@keyframes animation2 { 20% {}, 40% {}}
@keyframes animation3 { 40% {}, 60% {}}
and so on

now we need to make each animation fade in from 0 to 1 opacity and fade out from 1 to 0,

so we will add another 2 points (steps) for each animation after starting and before ending point to handle the full opacity(1)

enter image description here

http://codepen.io/El-Oz/pen/WwPPZQ

.slide1 {
    animation: fadeInOut1 24s ease reverse forwards infinite
}

.slide2 {
    animation: fadeInOut2 24s ease reverse forwards infinite
}

.slide3 {
    animation: fadeInOut3 24s ease reverse forwards infinite
}

.slide4 {
    animation: fadeInOut4 24s ease reverse forwards infinite
}

.slide5 {
    animation: fadeInOut5 24s ease reverse forwards infinite
}

.slide6 {
    animation: fadeInOut6 24s ease reverse forwards infinite
}

@keyframes fadeInOut1 {
    0% { opacity: 0 }
    1% { opacity: 1 }
    14% {opacity: 1 }
    16% { opacity: 0 }
}

@keyframes fadeInOut2 {
    0% { opacity: 0 }
    14% {opacity: 0 }
    16% { opacity: 1 }
    30% { opacity: 1 }
    33% { opacity: 0 }
}

@keyframes fadeInOut3 {
    0% { opacity: 0 }
    30% {opacity: 0 }
    33% {opacity: 1 }
    46% { opacity: 1 }
    48% { opacity: 0 }
}

@keyframes fadeInOut4 {
    0% { opacity: 0 }
    46% { opacity: 0 }
    48% { opacity: 1 }
    64% { opacity: 1 }
    65% { opacity: 0 }
}

@keyframes fadeInOut5 {
    0% { opacity: 0 }
    64% { opacity: 0 }
    66% { opacity: 1 }
    80% { opacity: 1 }
    83% { opacity: 0 }
}

@keyframes fadeInOut6 {
    80% { opacity: 0 }
    83% { opacity: 1 }
    99% { opacity: 1 }
    100% { opacity: 0 }
}

navigator.geolocation.getCurrentPosition sometimes works sometimes doesn't

I'm still getting spotty results in 2017, and I have a theory: the API documentation says that the call is now only available "in a secure context", i.e. over HTTPS. I'm having trouble getting a result in my development environment (http on localhost) and I believe this is why.

Code formatting shortcuts in Android Studio for Operation Systems

Really, I went to this thread because of my Ubuntu locks screen after this shortcut Ctrl + Alt + L. So if you are have the same problem just go to the Settings - Keyboard - Shortcuts - System and change the default shortcut for the "Lock screen".

MySQL load NULL values from CSV data

show variables

Show variables like "`secure_file_priv`";

Note: keep your csv file in location given by the above command.

create table assessments (course_code varchar(5),batch_code varchar(7),id_assessment int, assessment_type varchar(10), date int , weight int);

Note: here the 'date' column has some blank values in the csv file.

LOAD DATA INFILE 'C:/ProgramData/MySQL/MySQL Server 8.0/Uploads/assessments.csv' 
INTO TABLE assessments
FIELDS TERMINATED BY ',' 
OPTIONALLY ENCLOSED BY '' 
LINES TERMINATED BY '\n' 
IGNORE 1 ROWS 
(course_code,batch_code,id_assessment,assessment_type,@date,weight)
SET date = IF(@date = '', NULL, @date);

How can I get a uitableViewCell by indexPath?

You can use the following code to get last cell.

UITableViewCell *cell = [tableView cellForRowAtIndexPath:lastIndexPath];

Escaping regex string

Use the re.escape() function for this:

4.2.3 re Module Contents

escape(string)

Return string with all non-alphanumerics backslashed; this is useful if you want to match an arbitrary literal string that may have regular expression metacharacters in it.

A simplistic example, search any occurence of the provided string optionally followed by 's', and return the match object.

def simplistic_plural(word, text):
    word_or_plural = re.escape(word) + 's?'
    return re.match(word_or_plural, text)

ImportError: No module named win32com.client

Try this command:

pip install pywin32

Note

If it gives the following error:

Could not find a version that satisfies the requirement pywin32>=223 (from pypiwin32) (from versions:)
No matching distribution found for pywin32>=223 (from pypiwin32)

upgrade 'pip', using:

pip install --upgrade pip

Python & Matplotlib: Make 3D plot interactive in Jupyter Notebook

For 3-D visualization pythreejs is the best way to go probably in the notebook. It leverages the interactive widget infrastructure of the notebook, so connection between the JS and python is seamless.

A more advanced library is bqplot which is a d3-based interactive viz library for the iPython notebook, but it only does 2D

CSS Select box arrow style

Please follow the way like below:

_x000D_
_x000D_
.selectParent {_x000D_
 width:120px;_x000D_
 overflow:hidden;   _x000D_
}_x000D_
.selectParent select { _x000D_
 display: block;_x000D_
 width: 100%;_x000D_
 padding: 2px 25px 2px 2px; _x000D_
 border: none; _x000D_
 background: url("http://cdn1.iconfinder.com/data/icons/cc_mono_icon_set/blacks/16x16/br_down.png") right center no-repeat; _x000D_
 appearance: none; _x000D_
 -webkit-appearance: none;_x000D_
 -moz-appearance: none; _x000D_
}_x000D_
.selectParent.left select {_x000D_
 direction: rtl;_x000D_
 padding: 2px 2px 2px 25px;_x000D_
 background-position: left center;_x000D_
}_x000D_
/* for IE and Edge */ _x000D_
select::-ms-expand { _x000D_
 display: none; _x000D_
}
_x000D_
<div class="selectParent">_x000D_
  <select>_x000D_
    <option value="1">Option 1</option>_x000D_
    <option value="2">Option 2</option>           _x000D_
   </select>_x000D_
</div>_x000D_
<br />_x000D_
<div class="selectParent left">_x000D_
  <select>_x000D_
    <option value="1">Option 1</option>_x000D_
    <option value="2">Option 2</option>           _x000D_
   </select>_x000D_
</div>
_x000D_
_x000D_
_x000D_

How to get the 'height' of the screen using jquery

use with responsive website (view in mobile or ipad)

jQuery(window).height();   // return height of browser viewport
jQuery(window).width();    // return width of browser viewport

rarely use

jQuery(document).height(); // return height of HTML document
jQuery(document).width();  // return width of HTML document

Understanding Matlab FFT example

1) Why does the x-axis (frequency) end at 500? How do I know that there aren't more frequencies or are they just ignored?

It ends at 500Hz because that is the Nyquist frequency of the signal when sampled at 1000Hz. Look at this line in the Mathworks example:

f = Fs/2*linspace(0,1,NFFT/2+1);

The frequency axis of the second plot goes from 0 to Fs/2, or half the sampling frequency. The Nyquist frequency is always half the sampling frequency, because above that, aliasing occurs: Aliasing illustration

The signal would "fold" back on itself, and appear to be some frequency at or below 500Hz.

2) How do I know the frequencies are between 0 and 500? Shouldn't the FFT tell me, in which limits the frequencies are?

Due to "folding" described above (the Nyquist frequency is also commonly known as the "folding frequency"), it is physically impossible for frequencies above 500Hz to appear in the FFT; higher frequencies will "fold" back and appear as lower frequencies.

Does the FFT only return the amplitude value without the frequency?

Yes, the MATLAB FFT function only returns one vector of amplitudes. However, they map to the frequency points you pass to it.

Let me know what needs clarification so I can help you further.

Column order manipulation using col-lg-push and col-lg-pull in Twitter Bootstrap 3

I just felt like I'll add my $0.2 to those 2 good answers. I had a case when I had to move the last column all the way to the top in a 3-column situation.

[A][B][C]

to

[C]

[A]

[B]

Boostrap's class .col-xx-push-Xdoes nothing else but pushes a column to the right with left: XX%; so all you have to do to push a column right is to add the number of pseudo columns going left.

In this case:

  • two columns (col-md-5 and col-md-3) are going left, each with the value of the one that is going right;

  • one(col-md-4) is going right by the sum of the first two going left (5+3=8);


<div class="row">
    <div class="col-md-4 col-md-push-8 ">
        C
    </div>
    <div class="col-md-5 col-md-pull-4">
        A
    </div>
    <div class="col-md-3 col-md-pull-4">
        B
    </div>
</div>

enter image description here

How do I install Keras and Theano in Anaconda Python on Windows?

In windows environment with Anconda. Go to anconda prompt from start. Then if you are behind proxy then .copndarc file needs to eb updated with the proxy details.

ssl_verify: false channels: - defaults proxy_servers: http: http://xx.xx.xx.xx:xxxx https: https://xx.xx.xx.xx:xxxx

I had ssl_verify initially marked as 'True' then I was getting ssl error. So i turned it to false as above and then ran the below commands

conda update conda conda update --all conda install --channel https://conda.anaconda.org/conda-forge keras conda install --channel https://conda.anaconda.org/conda-forge tensorflow

My python version is 3.6.7

jquery: animate scrollLeft

You'll want something like this:


$("#next").click(function(){
      var currentElement = currentElement.next();
      $('html, body').animate({scrollLeft: $(currentElement).offset().left}, 800);
      return false;
   }); 
I believe this should work, it's adopted from a scrollTop function.

Groovy executing shell commands

"ls".execute() returns a Process object which is why "ls".execute().text works. You should be able to just read the error stream to determine if there were any errors.

There is a extra method on Process that allow you to pass a StringBuffer to retrieve the text: consumeProcessErrorStream(StringBuffer error).

Example:

def proc = "ls".execute()
def b = new StringBuffer()
proc.consumeProcessErrorStream(b)

println proc.text
println b.toString()

Show div when radio button selected

var switchData = $('#show-me');
switchData.hide();
$('input[type="radio"]').change(function(){ var inputData = $(this).attr("value");if(inputData == 'b') { switchData.show();}else{switchData.hide();}});

JSFIDDLE

INNER JOIN vs INNER JOIN (SELECT . FROM)

You are correct. You did exactly the right thing, checking the query plan rather than trying to second-guess the optimiser. :-)

Invalid length for a Base-64 char array

I'm not Reputable enough to upvote or comment yet, but LukeH's answer was spot on for me.

As AES encryption is the standard to use now, it produces a base64 string (at least all the encrypt/decrypt implementations I've seen). This string has a length in multiples of 4 (string.length % 4 = 0)

The strings I was getting contained + and = on the beginning or end, and when you just concatenate that into a URL's querystring, it will look right (for instance, in an email you generate), but when the the link is followed and the .NET page recieves it and puts it into this.Page.Request.QueryString, those special characters will be gone and your string length will not be in a multiple of 4.

As the are special characters at the FRONT of the string (ex: +), as well as = at the end, you can't just add some = to make up the difference as you are altering the cypher text in a way that doesn't match what was actually in the original querystring.

So, wrapping the cypher text with HttpUtility.URLEncode (not HtmlEncode) transforms the non-alphanumeric characters in a way that ensures .NET parses them back into their original state when it is intepreted into the querystring collection.

The good thing is, we only need to do the URLEncode when generating the querystring for the URL. On the incoming side, it's automatically translated back into the original string value.

Here's some example code

string cryptostring = MyAESEncrypt(MySecretString);
string URL = WebFunctions.ToAbsoluteUrl("~/ResetPassword.aspx?RPC=" + HttpUtility.UrlEncode(cryptostring));

Converting RGB to grayscale/intensity

Check out the Color FAQ for information on this. These values come from the standardization of RGB values that we use in our displays. Actually, according to the Color FAQ, the values you are using are outdated, as they are the values used for the original NTSC standard and not modern monitors.

Finding version of Microsoft C++ compiler from command-line (for makefiles)

Have a look at C++11 Features (Modern C++)

and section "Quick Reference Guide to Visual C++ Version Numbers" ...

RESTful API methods; HEAD & OPTIONS

OPTIONS method returns info about API (methods/content type)

HEAD method returns info about resource (version/length/type)

Server response

OPTIONS

HTTP/1.1 200 OK
Allow: GET,HEAD,POST,OPTIONS,TRACE
Content-Type: text/html; charset=UTF-8
Date: Wed, 08 May 2013 10:24:43 GMT
Content-Length: 0

HEAD

HTTP/1.1 200 OK
Accept-Ranges: bytes
Content-Type: text/html; charset=UTF-8
Date: Wed, 08 May 2013 10:12:29 GMT
ETag: "780602-4f6-4db31b2978ec0"
Last-Modified: Thu, 25 Apr 2013 16:13:23 GMT
Content-Length: 1270
  • OPTIONS Identifying which HTTP methods a resource supports, e.g. can we DELETE it or update it via a PUT?
  • HEAD Checking whether a resource has changed. This is useful when maintaining a cached version of a resource
  • HEAD Retrieving metadata about the resource, e.g. its media type or its size, before making a possibly costly retrieval
  • HEAD, OPTIONS Testing whether a resource exists and is accessible. For example, validating user-submitted links in an application

Here is nice and concise article about how HEAD and OPTIONS fit into RESTful architecture.

Check variable equality against a list of values

This is easily extendable and readable:

switch (foo) {
    case 1:
    case 3:
    case 12:
        // ...
        break

    case 4:
    case 5:
    case 6:
        // something else
        break
}

But not necessarily easier :)

How to do parallel programming in Python?

CPython uses the Global Interpreter Lock which makes parallel programing a bit more interesting than C++

This topic has several useful examples and descriptions of the challenge:

Python Global Interpreter Lock (GIL) workaround on multi-core systems using taskset on Linux?

Error creating bean with name

I think it comes from this line in your XML file:

<context:component-scan base-package="org.assessme.com.controller." />

Replace it by:

<context:component-scan base-package="org.assessme.com." />

It is because your Autowired service is not scanned by Spring since it is not in the right package.

"%%" and "%/%" for the remainder and the quotient

I think it is because % has often be associated with the modulus operator in many programming languages.

It is the case, e.g., in C, C++, C# and Java, and many other languages which derive their syntax from C (C itself took it from B).

How do I use arrays in C++?

5. Common pitfalls when using arrays.

5.1 Pitfall: Trusting type-unsafe linking.

OK, you’ve been told, or have found out yourself, that globals (namespace scope variables that can be accessed outside the translation unit) are Evil™. But did you know how truly Evil™ they are? Consider the program below, consisting of two files [main.cpp] and [numbers.cpp]:

// [main.cpp]
#include <iostream>

extern int* numbers;

int main()
{
    using namespace std;
    for( int i = 0;  i < 42;  ++i )
    {
        cout << (i > 0? ", " : "") << numbers[i];
    }
    cout << endl;
}

// [numbers.cpp]
int numbers[42] = {1, 2, 3, 4, 5, 6, 7, 8, 9};

In Windows 7 this compiles and links fine with both MinGW g++ 4.4.1 and Visual C++ 10.0.

Since the types don't match, the program crashes when you run it.

The Windows 7 crash dialog

In-the-formal explanation: the program has Undefined Behavior (UB), and instead of crashing it can therefore just hang, or perhaps do nothing, or it can send threating e-mails to the presidents of the USA, Russia, India, China and Switzerland, and make Nasal Daemons fly out of your nose.

In-practice explanation: in main.cpp the array is treated as a pointer, placed at the same address as the array. For 32-bit executable this means that the first int value in the array, is treated as a pointer. I.e., in main.cpp the numbers variable contains, or appears to contain, (int*)1. This causes the program to access memory down at very bottom of the address space, which is conventionally reserved and trap-causing. Result: you get a crash.

The compilers are fully within their rights to not diagnose this error, because C++11 §3.5/10 says, about the requirement of compatible types for the declarations,

[N3290 §3.5/10]
A violation of this rule on type identity does not require a diagnostic.

The same paragraph details the variation that is allowed:

… declarations for an array object can specify array types that differ by the presence or absence of a major array bound (8.3.4).

This allowed variation does not include declaring a name as an array in one translation unit, and as a pointer in another translation unit.

5.2 Pitfall: Doing premature optimization (memset & friends).

Not written yet

5.3 Pitfall: Using the C idiom to get number of elements.

With deep C experience it’s natural to write …

#define N_ITEMS( array )   (sizeof( array )/sizeof( array[0] ))

Since an array decays to pointer to first element where needed, the expression sizeof(a)/sizeof(a[0]) can also be written as sizeof(a)/sizeof(*a). It means the same, and no matter how it’s written it is the C idiom for finding the number elements of array.

Main pitfall: the C idiom is not typesafe. For example, the code …

#include <stdio.h>

#define N_ITEMS( array ) (sizeof( array )/sizeof( *array ))

void display( int const a[7] )
{
    int const   n = N_ITEMS( a );          // Oops.
    printf( "%d elements.\n", n );
}

int main()
{
    int const   moohaha[]   = {1, 2, 3, 4, 5, 6, 7};

    printf( "%d elements, calling display...\n", N_ITEMS( moohaha ) );
    display( moohaha );
}

passes a pointer to N_ITEMS, and therefore most likely produces a wrong result. Compiled as a 32-bit executable in Windows 7 it produces …

7 elements, calling display...
1 elements.

  1. The compiler rewrites int const a[7] to just int const a[].
  2. The compiler rewrites int const a[] to int const* a.
  3. N_ITEMS is therefore invoked with a pointer.
  4. For a 32-bit executable sizeof(array) (size of a pointer) is then 4.
  5. sizeof(*array) is equivalent to sizeof(int), which for a 32-bit executable is also 4.

In order to detect this error at run time you can do …

#include <assert.h>
#include <typeinfo>

#define N_ITEMS( array )       (                               \
    assert((                                                    \
        "N_ITEMS requires an actual array as argument",        \
        typeid( array ) != typeid( &*array )                    \
        )),                                                     \
    sizeof( array )/sizeof( *array )                            \
    )

7 elements, calling display...
Assertion failed: ( "N_ITEMS requires an actual array as argument", typeid( a ) != typeid( &*a ) ), file runtime_detect ion.cpp, line 16

This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.

The runtime error detection is better than no detection, but it wastes a little processor time, and perhaps much more programmer time. Better with detection at compile time! And if you're happy to not support arrays of local types with C++98, then you can do that:

#include <stddef.h>

typedef ptrdiff_t   Size;

template< class Type, Size n >
Size n_items( Type (&)[n] ) { return n; }

#define N_ITEMS( array )       n_items( array )

Compiling this definition substituted into the first complete program, with g++, I got …

M:\count> g++ compile_time_detection.cpp
compile_time_detection.cpp: In function 'void display(const int*)':
compile_time_detection.cpp:14: error: no matching function for call to 'n_items(const int*&)'

M:\count> _

How it works: the array is passed by reference to n_items, and so it does not decay to pointer to first element, and the function can just return the number of elements specified by the type.

With C++11 you can use this also for arrays of local type, and it's the type safe C++ idiom for finding the number of elements of an array.

5.4 C++11 & C++14 pitfall: Using a constexpr array size function.

With C++11 and later it's natural, but as you'll see dangerous!, to replace the C++03 function

typedef ptrdiff_t   Size;

template< class Type, Size n >
Size n_items( Type (&)[n] ) { return n; }

with

using Size = ptrdiff_t;

template< class Type, Size n >
constexpr auto n_items( Type (&)[n] ) -> Size { return n; }

where the significant change is the use of constexpr, which allows this function to produce a compile time constant.

For example, in contrast to the C++03 function, such a compile time constant can be used to declare an array of the same size as another:

// Example 1
void foo()
{
    int const x[] = {3, 1, 4, 1, 5, 9, 2, 6, 5, 4};
    constexpr Size n = n_items( x );
    int y[n] = {};
    // Using y here.
}

But consider this code using the constexpr version:

// Example 2
template< class Collection >
void foo( Collection const& c )
{
    constexpr int n = n_items( c );     // Not in C++14!
    // Use c here
}

auto main() -> int
{
    int x[42];
    foo( x );
}

The pitfall: as of July 2015 the above compiles with MinGW-64 5.1.0 with -pedantic-errors, and, testing with the online compilers at gcc.godbolt.org/, also with clang 3.0 and clang 3.2, but not with clang 3.3, 3.4.1, 3.5.0, 3.5.1, 3.6 (rc1) or 3.7 (experimental). And important for the Windows platform, it does not compile with Visual C++ 2015. The reason is a C++11/C++14 statement about use of references in constexpr expressions:

C++11 C++14 $5.19/2 nineth dash

A conditional-expression e is a core constant expression unless the evaluation of e, following the rules of the abstract machine (1.9), would evaluate one of the following expressions:
        ?

  • an id-expression that refers to a variable or data member of reference type unless the reference has a preceding initialization and either
    • it is initialized with a constant expression or
    • it is a non-static data member of an object whose lifetime began within the evaluation of e;

One can always write the more verbose

// Example 3  --  limited

using Size = ptrdiff_t;

template< class Collection >
void foo( Collection const& c )
{
    constexpr Size n = std::extent< decltype( c ) >::value;
    // Use c here
}

… but this fails when Collection is not a raw array.

To deal with collections that can be non-arrays one needs the overloadability of an n_items function, but also, for compile time use one needs a compile time representation of the array size. And the classic C++03 solution, which works fine also in C++11 and C++14, is to let the function report its result not as a value but via its function result type. For example like this:

// Example 4 - OK (not ideal, but portable and safe)

#include <array>
#include <stddef.h>

using Size = ptrdiff_t;

template< Size n >
struct Size_carrier
{
    char sizer[n];
};

template< class Type, Size n >
auto static_n_items( Type (&)[n] )
    -> Size_carrier<n>;
// No implementation, is used only at compile time.

template< class Type, size_t n >        // size_t for g++
auto static_n_items( std::array<Type, n> const& )
    -> Size_carrier<n>;
// No implementation, is used only at compile time.

#define STATIC_N_ITEMS( c ) \
    static_cast<Size>( sizeof( static_n_items( c ).sizer ) )

template< class Collection >
void foo( Collection const& c )
{
    constexpr Size n = STATIC_N_ITEMS( c );
    // Use c here
    (void) c;
}

auto main() -> int
{
    int x[42];
    std::array<int, 43> y;
    foo( x );
    foo( y );
}

About the choice of return type for static_n_items: this code doesn't use std::integral_constant because with std::integral_constant the result is represented directly as a constexpr value, reintroducing the original problem. Instead of a Size_carrier class one can let the function directly return a reference to an array. However, not everybody is familiar with that syntax.

About the naming: part of this solution to the constexpr-invalid-due-to-reference problem is to make the choice of compile time constant explicit.

Hopefully the oops-there-was-a-reference-involved-in-your-constexpr issue will be fixed with C++17, but until then a macro like the STATIC_N_ITEMS above yields portability, e.g. to the clang and Visual C++ compilers, retaining type safety.

Related: macros do not respect scopes, so to avoid name collisions it can be a good idea to use a name prefix, e.g. MYLIB_STATIC_N_ITEMS.

How to add and remove item from array in components in Vue 2

You can use Array.push() for appending elements to an array.

For deleting, it is best to use this.$delete(array, index) for reactive objects.

Vue.delete( target, key ): Delete a property on an object. If the object is reactive, ensure the deletion triggers view updates. This is primarily used to get around the limitation that Vue cannot detect property deletions, but you should rarely need to use it.

https://vuejs.org/v2/api/#Vue-delete

Decoding JSON String in Java

This is the best and easiest code:

public class test
{
    public static void main(String str[])
    {
        String jsonString = "{\"stat\": { \"sdr\": \"aa:bb:cc:dd:ee:ff\", \"rcv\": \"aa:bb:cc:dd:ee:ff\", \"time\": \"UTC in millis\", \"type\": 1, \"subt\": 1, \"argv\": [{\"type\": 1, \"val\":\"stackoverflow\"}]}}";
        JSONObject jsonObject = new JSONObject(jsonString);
        JSONObject newJSON = jsonObject.getJSONObject("stat");
        System.out.println(newJSON.toString());
        jsonObject = new JSONObject(newJSON.toString());
        System.out.println(jsonObject.getString("rcv"));
       System.out.println(jsonObject.getJSONArray("argv"));
    }
}

The library definition of the json files are given here. And it is not same libraries as posted here, i.e. posted by you. What you had posted was simple json library I have used this library.

You can download the zip. And then create a package in your project with org.json as name. and paste all the downloaded codes there, and have fun.

I feel this to be the best and the most easiest JSON Decoding.

Memory address of variables in Java

That is the class name and System.identityHashCode() separated by the '@' character. What the identity hash code represents is implementation-specific. It often is the initial memory address of the object, but the object can be moved in memory by the VM over time. So (briefly) you can't rely on it being anything.

Getting the memory addresses of variables is meaningless within Java, since the JVM is at liberty to implement objects and move them as it seems fit (your objects may/will move around during garbage collection etc.)

Integer.toBinaryString() will give you an integer in binary form.

How can I override Bootstrap CSS styles?

Link your custom.css file as the last entry below the bootstrap.css. Custom.css style definitions will override bootstrap.css

Html

<link href="css/bootstrap.min.css" rel="stylesheet">
<link href="css/custom.css" rel="stylesheet">

Copy all style definitions of legend in custom.css and make changes in it (like margin-bottom:5px; -- This will overrider margin-bottom:20px; )

How to pass parameters to the DbContext.Database.ExecuteSqlCommand method?

Stored procedures can be executed like below

 string cmd = Constants.StoredProcs.usp_AddRoles.ToString() + " @userId, @roleIdList";
                        int result = db.Database
                                       .ExecuteSqlCommand
                                       (
                                          cmd,
                                           new SqlParameter("@userId", userId),
                                           new SqlParameter("@roleIdList", roleId)
                                       );

Regex to check if valid URL that ends in .jpg, .png, or .gif

Here's the basic idea in Perl. Salt to taste.

#!/usr/bin/perl

use LWP::UserAgent;

my $ua = LWP::UserAgent->new;

@ARGV = qw(http://www.example.com/logo.png);

my $response = $ua->head( $ARGV[0] );

my( $class, $type ) = split m|/|, lc $response->content_type;

print "It's an image!\n" if $class eq 'image';

If you need to inspect the URL, use a solid library for it rather than trying to handle all the odd situations yourself:

use URI;

my $uri = URI->new( $ARGV[0] );

my $last = ( $uri->path_segments )[-1];

my( $extension ) = $last =~ m/\.([^.]+)$/g;

print "My extension is $extension\n";

Good luck, :)

How to convert NSData to byte array in iPhone?

Here's what I believe is the Swift equivalent:

if let data = NSData(contentsOfFile: filePath) {
   let length = data.length
   let byteData = malloc(length)
   memcmp(byteData, data.bytes, length)
}

How to stop app that node.js express 'npm start'

All (3) solotion is :

1- ctlr + C

2- in json file wreite a script that stop

"scripts": { "stop": "killall -SIGINT this-name-can-be-as-long-as-it-needs-to-be" },

*than in command write // npm stop //

3- Restart the pc

CAST DECIMAL to INT

From the article you linked to:

The type can be one of the following values:

BINARY[(N)]

CHAR[(N)]

DATE

DATETIME

DECIMAL[(M[,D])]

SIGNED [INTEGER]

TIME

UNSIGNED [INTEGER]

Try SIGNED instead of INT

Assign variable in if condition statement, good practice or not?

I see no proof that it is not good practice. Yes, it may look like a mistake but that is easily remedied by judicious commenting. Take for instance:

if (x = processorIntensiveFunction()) { // declaration inside if intended
    alert(x);
}

Why should that function be allowed to run a 2nd time with:

alert(processorIntensiveFunction());

Because the first version LOOKS bad? I cannot agree with that logic.

How do I do a bulk insert in mySQL using node.js

I was having similar problem. It was just inserting one from the list of arrays. It worked after making the below changes.

  1. Passed [params] to the query method.
  2. Changed the query from insert (a,b) into table1 values (?) ==> insert (a,b) into table1 values ? . ie. Removed the paranthesis around the question mark.

Hope this helps. I am using mysql npm.

Secure FTP using Windows batch script

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

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

Subtract two variables in Bash

You can use:

((count = FIRSTV - SECONDV))

to avoid invoking a separate process, as per the following transcript:

pax:~$ FIRSTV=7
pax:~$ SECONDV=2
pax:~$ ((count = FIRSTV - SECONDV))
pax:~$ echo $count
5

make script execution to unlimited

You'll have to set it to zero. Zero means the script can run forever. Add the following at the start of your script:

ini_set('max_execution_time', 0);

Refer to the PHP documentation of max_execution_time

Note that:

set_time_limit(0);

will have the same effect.

How do I get logs from all pods of a Kubernetes replication controller?

If the pods are named meaningfully one could use simple Plain Old Bash:

keyword=nodejs
command="cat <("
for line in $(kubectl get pods | \
  grep $keyword | grep Running | awk '{print $1}'); do 
    command="$command (kubectl logs --tail=2 -f $line &) && "
  done
command="$command echo)"
eval $command

Explanation: Loop through running pods with name containing "nodejs". Tail the log for each of them in parallel (single ampersand runs in background) ensuring that if any of the pods fail the whole command exits (double ampersand). Cat the streams from each of the tail commands into a unique stream. Eval is needed to run this dynamically built command.

The type java.lang.CharSequence cannot be resolved in package declaration

Java 8 supports default methods in interfaces. And in JDK 8 a lot of old interfaces now have new default methods. For example, now in CharSequence we have chars and codePoints methods.
If source level of your project is lower than 1.8, then compiler doesn't allow you to use default methods in interfaces. So it cannot compile classes that directly on indirectly depend on this interfaces.
If I get your problem right, then you have two solutions. First solution is to rollback to JDK 7, then you will use old CharSequence interface without default methods. Second solution is to set source level of your project to 1.8, then your compiler will not complain about default methods in interfaces.

How to pass a datetime parameter?

As a matter of fact, specifying parameters explicitly as ?date='fulldatetime' worked like a charm. So this will be a solution for now: don't use commas, but use old GET approach.

Mockito How to mock only the call of a method of the superclass

The reason is your base class is not public-ed, then Mockito cannot intercept it due to visibility, if you change base class as public, or @Override in sub class (as public), then Mockito can mock it correctly.

public class BaseService{
  public boolean foo(){
    return true;
  }
}

public ChildService extends BaseService{
}

@Test
@Mock ChildService childService;
public void testSave() {
  Mockito.when(childService.foo()).thenReturn(false);

  // When
  assertFalse(childService.foo());
}

One-liner if statements, how to convert this if-else-statement

return (expression) ? value1 : value2;

If value1 and value2 are actually true and false like in your example, you may as well just

return expression;

Laravel 5 not finding css files

I was having the same problem, until just now.

Removing the / from before /css/app.css so that its css.app.css worked for me.

How to include view/partial specific styling in AngularJS

I know this question is old now, but after doing a ton of research on various solutions to this problem, I think I may have come up with a better solution.

UPDATE 1: Since posting this answer, I have added all of this code to a simple service that I have posted to GitHub. The repo is located here. Feel free to check it out for more info.

UPDATE 2: This answer is great if all you need is a lightweight solution for pulling in stylesheets for your routes. If you want a more complete solution for managing on-demand stylesheets throughout your application, you may want to checkout Door3's AngularCSS project. It provides much more fine-grained functionality.

In case anyone in the future is interested, here's what I came up with:

1. Create a custom directive for the <head> element:

app.directive('head', ['$rootScope','$compile',
    function($rootScope, $compile){
        return {
            restrict: 'E',
            link: function(scope, elem){
                var html = '<link rel="stylesheet" ng-repeat="(routeCtrl, cssUrl) in routeStyles" ng-href="{{cssUrl}}" />';
                elem.append($compile(html)(scope));
                scope.routeStyles = {};
                $rootScope.$on('$routeChangeStart', function (e, next, current) {
                    if(current && current.$$route && current.$$route.css){
                        if(!angular.isArray(current.$$route.css)){
                            current.$$route.css = [current.$$route.css];
                        }
                        angular.forEach(current.$$route.css, function(sheet){
                            delete scope.routeStyles[sheet];
                        });
                    }
                    if(next && next.$$route && next.$$route.css){
                        if(!angular.isArray(next.$$route.css)){
                            next.$$route.css = [next.$$route.css];
                        }
                        angular.forEach(next.$$route.css, function(sheet){
                            scope.routeStyles[sheet] = sheet;
                        });
                    }
                });
            }
        };
    }
]);

This directive does the following things:

  1. It compiles (using $compile) an html string that creates a set of <link /> tags for every item in the scope.routeStyles object using ng-repeat and ng-href.
  2. It appends that compiled set of <link /> elements to the <head> tag.
  3. It then uses the $rootScope to listen for '$routeChangeStart' events. For every '$routeChangeStart' event, it grabs the "current" $$route object (the route that the user is about to leave) and removes its partial-specific css file(s) from the <head> tag. It also grabs the "next" $$route object (the route that the user is about to go to) and adds any of its partial-specific css file(s) to the <head> tag.
  4. And the ng-repeat part of the compiled <link /> tag handles all of the adding and removing of the page-specific stylesheets based on what gets added to or removed from the scope.routeStyles object.

Note: this requires that your ng-app attribute is on the <html> element, not on <body> or anything inside of <html>.

2. Specify which stylesheets belong to which routes using the $routeProvider:

app.config(['$routeProvider', function($routeProvider){
    $routeProvider
        .when('/some/route/1', {
            templateUrl: 'partials/partial1.html', 
            controller: 'Partial1Ctrl',
            css: 'css/partial1.css'
        })
        .when('/some/route/2', {
            templateUrl: 'partials/partial2.html',
            controller: 'Partial2Ctrl'
        })
        .when('/some/route/3', {
            templateUrl: 'partials/partial3.html',
            controller: 'Partial3Ctrl',
            css: ['css/partial3_1.css','css/partial3_2.css']
        })
}]);

This config adds a custom css property to the object that is used to setup each page's route. That object gets passed to each '$routeChangeStart' event as .$$route. So when listening to the '$routeChangeStart' event, we can grab the css property that we specified and append/remove those <link /> tags as needed. Note that specifying a css property on the route is completely optional, as it was omitted from the '/some/route/2' example. If the route doesn't have a css property, the <head> directive will simply do nothing for that route. Note also that you can even have multiple page-specific stylesheets per route, as in the '/some/route/3' example above, where the css property is an array of relative paths to the stylesheets needed for that route.

3. You're done Those two things setup everything that was needed and it does it, in my opinion, with the cleanest code possible.

Hope that helps someone else who might be struggling with this issue as much as I was.

Setting up Vim for Python

Re: the dead "Turning Vim Into A Modern Python IDE" link, back in 2013 I saved a copy, that I converted to a HTML page as well as a PDF copy:

http://persagen.com/files/misc/Turning_vim_into_a_modern_Python_IDE.html

http://persagen.com/files/misc/Turning_vim_into_a_modern_Python_IDE.pdf

Edit (Sep 08, 2017) updated URLs.

Including dependencies in a jar with Maven

Putting Maven aside, you can put JAR libraries inside the Main Jar but you will need to use your own classloader.

Check this project: One-JAR link text

Generate signed apk android studio

I dont think anyone has answered the question correctly.So, for anyone else who has the same question, this should help :

Step 1 Go to Build>Generate Signed APK>Next (module selected would be your module , most often called "app")

Step 2 Click on create new

Step 3 Basically, fill in the form with the required details. The confusing bit it is where it asks for a Key Store Path. Click on the icon on the right with the 3 dots ("..."), which will open up a navigator window asking you to navigate and select a .jks file.Navigate to a folder where you want your keystore file saved and then at the File Name box at the bottom of that window, simply enter a name of your liking and the OK button will be clickable now. What is happening is that the window isnt really asking you chose a .jks file but rather it wants you to give it the location and name that you want it to have.

Step 4 Click on Next and then select Release and Voila ! you are done.

Keep SSH session alive

I wanted a one-time solution:

ssh -o ServerAliveInterval=60 [email protected]

Stored it in an alias:

alias sshprod='ssh -v -o ServerAliveInterval=60 [email protected]'

Now can connect like this:

me@MyMachine:~$ sshprod

Calculating moving average

Or you can simply calculate it using filter, here's the function I use:

ma <- function(x, n = 5){filter(x, rep(1 / n, n), sides = 2)}

If you use dplyr, be careful to specify stats::filter in the function above.

Permission denied (publickey) when SSH Access to Amazon EC2 instance

This error message means you failed to authenticate.

These are common reasons that can cause that:

  1. Trying to connect with the wrong key. Are you sure this instance is using this keypair?
  2. Trying to connect with the wrong username. ubuntu is the username for the ubuntu based AWS distribution, but on some others it's ec2-user (or admin on some Debians, according to Bogdan Kulbida's answer)(can also be root, fedora, see below)
  3. Trying to connect the wrong host. Is that the right host you are trying to log in to?

Note that 1. will also happen if you have messed up the /home/<username>/.ssh/authorized_keys file on your EC2 instance.

About 2., the information about which username you should use is often lacking from the AMI Image description. But you can find some in AWS EC2 documentation, bullet point 4. : http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AccessingInstancesLinux.html

Use the ssh command to connect to the instance. You'll specify the private key (.pem) file and user_name@public_dns_name. For Amazon Linux, the user name is ec2-user. For RHEL5, the user name is either root or ec2-user. For Ubuntu, the user name is ubuntu. For Fedora, the user name is either fedora or ec2-user. For SUSE Linux, the user name is root. Otherwise, if ec2-user and root don't work, check with your AMI provider.

Finally, be aware that there are many other reasons why authentication would fail. SSH is usually pretty explicit about what went wrong if you care to add the -v option to your SSH command and read the output, as explained in many other answers to this question.

Print number of keys in Redis

WARNING: Do not run this on a production machine.

On a Linux box:

redis-cli KEYS "*" | wc -l

Note: As mentioned in comments below, this is an O(N) operation, so on a large DB with many keys you should not use this. For smaller deployments, it should be fine.

Is it possible to play music during calls so that the partner can hear it ? Android

No, It is not possible. But if you want to dig it more, then you can visit Using Android phone as GSM Gateway for VoIP where author has concluded that

It's not possible to use Android as a GSM Gateway in its current form. Even after flashing custom ROM because they also depends on proprietary RIL (Radio Interface Layer) firmwares. Hurdles 1 and 2 (API limitation) can be removed because the source code is available for the open source community to make it possible. However, the hurdle 3 (proprietary RIL) is dependent on the hardware vendors. Hardware vendors do not usually make their device drivers code available.

Should I size a textarea with CSS width / height or HTML cols / rows attributes?

A major feature of textareas is that they are expandable. On a web page this can result in scroll bars appearing on the text area if the text length overfills the space you set (be that using rows, or be that using CSS. That can be a problem when a user decides to print, particularly with 'printing' to PDF - so set a comfortably large min-height for printed textareas with a conditional CSS rule:

@media print { 
textarea {
min-height: 900px;  
}
}

Getting Date or Time only from a DateTime Object

var currentDateTime = dateTime.Now();
var date=currentDateTime.Date;

How can I hide a checkbox in html?

You need to add the element type to the class, otherwise it will not work.

_x000D_
_x000D_
.hide-checkbox { display: none }        /* This will not work! */_x000D_
input.hide-checkbox { display: none }   /* But this will. */ 
_x000D_
<input class="hide-checkbox" id="checkbox" />_x000D_
<label for="checkbox">Checkbox</label>
_x000D_
_x000D_
_x000D_

It looks too simple, but try it out!

Understanding dict.copy() - shallow or deep?

Adding to kennytm's answer. When you do a shallow copy parent.copy() a new dictionary is created with same keys,but the values are not copied they are referenced.If you add a new value to parent_copy it won't effect parent because parent_copy is a new dictionary not reference.

parent = {1: [1,2,3]}
parent_copy = parent.copy()
parent_reference = parent

print id(parent),id(parent_copy),id(parent_reference)
#140690938288400 140690938290536 140690938288400

print id(parent[1]),id(parent_copy[1]),id(parent_reference[1])
#140690938137128 140690938137128 140690938137128

parent_copy[1].append(4)
parent_copy[2] = ['new']

print parent, parent_copy, parent_reference
#{1: [1, 2, 3, 4]} {1: [1, 2, 3, 4], 2: ['new']} {1: [1, 2, 3, 4]}

The hash(id) value of parent[1], parent_copy[1] are identical which implies [1,2,3] of parent[1] and parent_copy[1] stored at id 140690938288400.

But hash of parent and parent_copy are different which implies They are different dictionaries and parent_copy is a new dictionary having values reference to values of parent

Access a JavaScript variable from PHP

_GET accesses query string variables, test is not a querystring variable (PHP does not process the JS in any way). You need to rethink. You could make a php variable $test, and do something like:

<?php
$test = "tester";
?>
<script type="text/javascript" charset="utf-8">
    var test = "<?php echo $test?>";
</script>

<?php
    echo $test;
?>

Of course, I don't know why you want this, so I'm not sure the best solution.

EDIT: As others have noted, if the JavaScript variable is really generated on the client, you will need AJAX or a form to send it to the server.

Finding the average of an array using JS

answer to your 1. question:

for ( var i = 0; i < grades.length; i ++){
    var avg = (grades[i] / grades.length) * grades.length
}

avg is declared in each loop. Thus, at the end of the loop, avg has the value of the last item in the array : 68 *5 / 5

document.getElementById('btnid').disabled is not working in firefox and chrome

I've tried all the possibilities. Nothing worked for me except the following. var element = document.querySelectorAll("input[id=btn1]"); element[0].setAttribute("disabled",true);

jQuery: how to scroll to certain anchor/div on page load?

i achieve it like this..

if(location.pathname == '/registration')
{
$('html, body').animate({ scrollTop: $('#registration').offset().top - 40}, 1000);
}

TypeError: a bytes-like object is required, not 'str' when writing to a file in Python3

why not try opening your file as text?

with open(fname, 'rt') as f:
    lines = [x.strip() for x in f.readlines()]

Additionally here is a link for python 3.x on the official page: https://docs.python.org/3/library/io.html And this is the open function: https://docs.python.org/3/library/functions.html#open

If you are really trying to handle it as a binary then consider encoding your string.

Get the position of a div/span tag

For anyone needing just top or left position, slight modifications to @Nickf's readable code does the trick.

function getTopPos(el) {
    for (var topPos = 0;
        el != null;
        topPos += el.offsetTop, el = el.offsetParent);
    return topPos;
}

and

function getLeftPos(el) {
    for (var leftPos = 0;
        el != null;
        leftPos += el.offsetLeft, el = el.offsetParent);
    return leftPos;
}

Run JavaScript when an element loses focus

You're looking for the onblur event. Look here, for more details.

Best practice for instantiating a new Android Fragment

Best practice to instance fragments with arguments in android is to have static factory method in your fragment.

public static MyFragment newInstance(String name, int age) {
    Bundle bundle = new Bundle();
    bundle.putString("name", name);
    bundle.putInt("age", age);

    MyFragment fragment = new MyFragment();
    fragment.setArguments(bundle);

    return fragment;
}

You should avoid setting your fields with the instance of a fragment. Because whenever android system recreate your fragment, if it feels that the system needs more memory, than it will recreate your fragment by using constructor with no arguments.

You can find more info about best practice to instantiate fragments with arguments here.

Standard concise way to copy a file in Java?

Three possible problems with the above code:

  1. If getChannel throws an exception, you might leak an open stream.
  2. For large files, you might be trying to transfer more at once than the OS can handle.
  3. You are ignoring the return value of transferFrom, so it might be copying just part of the file.

This is why org.apache.tools.ant.util.ResourceUtils.copyResource is so complicated. Also note that while transferFrom is OK, transferTo breaks on JDK 1.4 on Linux (see Bug ID:5056395) – Jesse Glick Jan