Programs & Examples On #Executives

Google maps API V3 - multiple markers on exact same spot

Adding to Matthew Fox's sneaky genius answer, I have added a small random offset to each lat and lng when setting the marker object. For example:

new LatLng(getLat()+getMarkerOffset(), getLng()+getMarkerOffset()),

private static double getMarkerOffset(){
    //add tiny random offset to keep markers from dropping on top of themselves
    double offset =Math.random()/4000;
    boolean isEven = ((int)(offset *400000)) %2 ==0;
    if (isEven) return  offset;
    else        return -offset;
}

Getting mouse position in c#

You must also have the following imports in order to import the DLL

using System.Runtime.InteropServices;
using System.Diagnostics;

Can I display the value of an enum with printf()?

enum MyEnum
{  A_ENUM_VALUE=0,
   B_ENUM_VALUE,
   C_ENUM_VALUE
};


int main()
{
 printf("My enum Value : %d\n", (int)C_ENUM_VALUE);
 return 0;
}

You have just to cast enum to int !
Output : My enum Value : 2

Convert JSON to Map

I like google gson library.
When you don't know structure of json. You can use

JsonElement root = new JsonParser().parse(jsonString);

and then you can work with json. e.g. how to get "value1" from your gson:

String value1 = root.getAsJsonObject().get("data").getAsJsonObject().get("field1").getAsString();

On npm install: Unhandled rejection Error: EACCES: permission denied

sudo chown -R $(whoami) ~/.npm

sudo chown -R $(whoami) ~/.config

Content Security Policy "data" not working for base64 Images in Chrome 28

According to the grammar in the CSP spec, you need to specify schemes as scheme:, not just scheme. So, you need to change the image source directive to:

img-src 'self' data:;

Excel: Can I create a Conditional Formula based on the Color of a Cell?

You can use this function (I found it here: http://excelribbon.tips.net/T010780_Colors_in_an_IF_Function.html):

Function GetFillColor(Rng As Range) As Long
    GetFillColor = Rng.Interior.ColorIndex
End Function

Here is an explanation, how to create user-defined functions: http://www.wikihow.com/Create-a-User-Defined-Function-in-Microsoft-Excel

In your worksheet, you can use the following: =GetFillColor(B5)

How to use ArgumentCaptor for stubbing?

Assuming the following method to test:

public boolean doSomething(SomeClass arg);

Mockito documentation says that you should not use captor in this way:

when(someObject.doSomething(argumentCaptor.capture())).thenReturn(true);
assertThat(argumentCaptor.getValue(), equalTo(expected));

Because you can just use matcher during stubbing:

when(someObject.doSomething(eq(expected))).thenReturn(true);

But verification is a different story. If your test needs to ensure that this method was called with a specific argument, use ArgumentCaptor and this is the case for which it is designed:

ArgumentCaptor<SomeClass> argumentCaptor = ArgumentCaptor.forClass(SomeClass.class);
verify(someObject).doSomething(argumentCaptor.capture());
assertThat(argumentCaptor.getValue(), equalTo(expected));

How to select lines between two marker patterns which may occur multiple times with awk/sed

I tried to use awk to print lines between two patterns while pattern2 also match pattern1. And the pattern1 line should also be printed.

e.g. source

package AAA
aaa
bbb
ccc
package BBB
ddd
eee
package CCC
fff
ggg
hhh
iii
package DDD
jjj

should has an ouput of

package BBB
ddd
eee

Where pattern1 is package BBB, pattern2 is package \w*. Note that CCC isn't a known value so can't be literally matched.

In this case, neither @scai 's awk '/abc/{a=1}/mno/{print;a=0}a' file nor @fedorqui 's awk '/abc/{a=1} a; /mno/{a=0}' file works for me.

Finally, I managed to solve it by awk '/package BBB/{flag=1;print;next}/package \w*/{flag=0}flag' file, haha

A little more effort result in awk '/package BBB/{flag=1;print;next}flag;/package \w*/{flag=0}' file, to print pattern2 line also, that is,

package BBB
ddd
eee
package CCC

Using find command in bash script

If you want to loop over what you "find", you should use this:

find . -type f -name '*.*' -print0 | while IFS= read -r -d '' file; do
    printf '%s\n' "$file"
done

Source: https://askubuntu.com/questions/343727/filenames-with-spaces-breaking-for-loop-find-command

How to run multiple DOS commands in parallel?

I suggest you to see "How do I run a bat file in the background from another bat file?"

Also, good answer (of using start command) was given in "Parallel execution of shell processes" question page here;

But my recommendation is to use PowerShell. I believe it will perfectly suit your needs.

Change image size with JavaScript

If you want to resize an image after it is loaded, you can attach to the onload event of the <img> tag. Note that it may not be supported in all browsers (Microsoft's reference claims it is part of the HTML 4.0 spec, but the HTML 4.0 spec doesn't list the onload event for <img>).

The code below is tested and working in: IE 6, 7 & 8, Firefox 2, 3 & 3.5, Opera 9 & 10, Safari 3 & 4 and Google Chrome:

<img src="yourImage.jpg" border="0" height="real_height" width="real_width"
    onload="resizeImg(this, 200, 100);">

<script type="text/javascript">
function resizeImg(img, height, width) {
    img.height = height;
    img.width = width;
}
</script>

How to define custom exception class in Java, the easiest way?

Reason for this is explained in the Inheritance article of the Java Platform which says:

"A subclass inherits all the members (fields, methods, and nested classes) from its superclass. Constructors are not members, so they are not inherited by subclasses, but the constructor of the superclass can be invoked from the subclass."

How do I display a ratio in Excel in the format A:B?

Try this formula:

=SUBSTITUTE(TEXT(A1/B1,"?/?"),"/",":")

Result:

A   B   C
33  11  3:1
25  5   5:1
6   4   3:2

Explanation:

  • TEXT(A1/B1,"?/?") turns A/B into an improper fraction
  • SUBSTITUTE(...) replaces the "/" in the fraction with a colon

This doesn't require any special toolkits or macros. The only downside might be that the result is considered text--not a number--so you can easily use it for further calculations.


Note: as @Robin Day suggested, increase the number of question marks (?) as desired to reduce rounding (thanks Robin!).

CSS /JS to prevent dragging of ghost image?

You can set the image that is shown when an item is dragged. Tested with Chrome.

setDragImage

use

onclick = myFunction();
myFunction(e) {
    e.dataTransfer.setDragImage(someImage, xOffset, yOffset);
}

Alternatively, as already mentioned in the answers, you can set draggable="false" on the HTML element, if not being able to drag the element at all is no issue.

Measuring Query Performance : "Execution Plan Query Cost" vs "Time Taken"

SET STATISTICS TIME ON

SELECT * 

FROM Production.ProductCostHistory
WHERE StandardCost < 500.00;

SET STATISTICS TIME OFF;

And see the message tab it will look like this:

SQL Server Execution Times:

   CPU time = 0 ms,  elapsed time = 10 ms.

(778 row(s) affected)

SQL Server parse and compile time: 

   CPU time = 0 ms, elapsed time = 0 ms.

CodeIgniter Select Query

Here is the example of the code:

public function getItemName()
{
    $this->db->select('Id,Name');
    $this->db->from('item');
    $this->db->where(array('Active' => 1));
    return $this->db->get()->result();
}

INSTALL_FAILED_USER_RESTRICTED : android studio using redmi 4 device

With Xiaomi Redmi note 8 pro (MIUI 10.4.4), Android 9 -

While connecting to Vysor (2.1.2) from Windows PC (via USB cable), received the error message:

"Error installing APK: Failure [INSTALL_FAILED_USER_RESTRICTED]"

even after turning "USB Debugging" On.

So the following settings were required -

  • Developer options (On)
  • USB debugging (On)
  • Install via USB (On)

Leave the following,

  • Turn on MIUI optimization (On)
  • Verify apps over USB (On)

Check if process returns 0 with batch file

To check whether a process/command returned 0 or not, use the operators && == 0 or not == 0 ||:

Just add operator to your script:

execute_command && (

       echo\Return 0, with no execution error
) || (
        echo\Return non 0, something went wrong
     )

command && echo\Return 0 || echo\Return non 0

Close window automatically after printing dialog closes

This works for me perfectly @holger, however, i have modified it and suit me better, the window now pops up and close immediately you hit the print or cancel button.

function printcontent()
{ 
var disp_setting="toolbar=yes,location=no,directories=yes,menubar=yes,"; 
disp_setting+="scrollbars=yes,width=300, height=350, left=50, top=25"; 
var content_vlue = document.getElementById("content").innerHTML; 
var w = window.open("","", disp_setting);
w.document.write(content_vlue); //only part of the page to print, using jquery
w.document.close(); //this seems to be the thing doing the trick
w.focus();
w.print();
w.close();
}"

javax.crypto.IllegalBlockSizeException : Input length must be multiple of 16 when decrypting with padded cipher

A few comments:

import sun.misc.*; Don't do this. It is non-standard and not guaranteed to be the same between implementations. There are other libraries with Base64 conversion available.

byte[] encVal = c.doFinal(Data.getBytes()); You are relying on the default character encoding here. Always specify what character encoding you are using: byte[] encVal = c.doFinal(Data.getBytes("UTF-8")); Defaults might be different in different places.

As @thegrinner pointed out, you need to explicitly check the length of your byte arrays. If there is a discrepancy, then compare them byte by byte to see where the difference is creeping in.

Check whether a string contains a substring

Another possibility is to use regular expressions which is what Perl is famous for:

if ($mystring =~ /s1\.domain\.com/) {
   print qq("$mystring" contains "s1.domain.com"\n);
}

The backslashes are needed because a . can match any character. You can get around this by using the \Q and \E operators.

my $substring = "s1.domain.com";
    if ($mystring =~ /\Q$substring\E/) {
   print qq("$mystring" contains "$substring"\n);
}

Or, you can do as eugene y stated and use the index function. Just a word of warning: Index returns a -1 when it can't find a match instead of an undef or 0.

Thus, this is an error:

my $substring = "s1.domain.com";
if (not index($mystring, $substr)) {
    print qq("$mystring" doesn't contains "$substring"\n";
} 

This will be wrong if s1.domain.com is at the beginning of your string. I've personally been burned on this more than once.

Rethrowing exceptions in Java without losing the stack trace

public int read(byte[] a) throws IOException {
    try {
        return in.read(a);
    } catch (final Throwable t) {
        /* can do something here, like  in=null;  */
        throw t;
    }
}

This is a concrete example where the method throws an IOException. The final means t can only hold an exception thrown from the try block. Additional reading material can be found here and here.

Limit on the WHERE col IN (...) condition

There is a limit, but you can split your values into separate blocks of in()

Select * 
From table 
Where Col IN (123,123,222,....)
or Col IN (456,878,888,....)

Animate scroll to ID on page load

try with following code. make elements with class name page-scroll and keep id name to href of corresponding links

$('a.page-scroll').bind('click', function(event) {
        var $anchor = $(this);
        $('html, body').stop().animate({
            scrollTop: ($($anchor.attr('href')).offset().top - 50)
        }, 1250, 'easeInOutExpo');
        event.preventDefault();
    });

Add "Are you sure?" to my excel button, how can I?

Just make a custom userform that is shown when the "delete" button is pressed, then link the continue button to the actual code that does the deleting. Make the cancel button hide the userform.

Convert a number range to another range, maintaining ratio

Here's some short Python functions for your copy and paste ease, including a function to scale an entire list.

def scale_number(unscaled, to_min, to_max, from_min, from_max):
    return (to_max-to_min)*(unscaled-from_min)/(from_max-from_min)+to_min

def scale_list(l, to_min, to_max):
    return [scale_number(i, to_min, to_max, min(l), max(l)) for i in l]

Which can be used like so:

scale_list([1,3,4,5], 0, 100)

[0.0, 50.0, 75.0, 100.0]

In my case I wanted to scale a logarithmic curve, like so:

scale_list([math.log(i+1) for i in range(5)], 0, 50)

[0.0, 21.533827903669653, 34.130309724299266, 43.06765580733931, 50.0]

How do I ignore files in a directory in Git?

If you want to put a .gitignore file at the top level and make it work for any folder below it use /**/.

E.g. to ignore all *.map files in a /src/main/ folder and sub-folders use:

/src/main/**/*.map

Eslint: How to disable "unexpected console statement" in Node.js?

The following works with ESLint in VSCode if you want to disable the rule for just one line.

To disable the next line:

// eslint-disable-next-line no-console
console.log('hello world');

To disable the current line:

console.log('hello world'); // eslint-disable-line no-console

Registry key for global proxy settings for Internet Explorer 10 on Windows 8

Create a .reg file containing your proxy settings for your users. Create a batch file setting it to setting it to run the .reg file with the extension /s

On a server using a logon script, tell the logon to run the batch file. Jason

Simple way to copy or clone a DataRow?

You can use ImportRow method to copy Row from DataTable to DataTable with the same schema:

var row = SourceTable.Rows[RowNum];
DestinationTable.ImportRow(row);

Update:

With your new Edit, I believe:

var desRow = dataTable.NewRow();
var sourceRow = dataTable.Rows[rowNum];
desRow.ItemArray = sourceRow.ItemArray.Clone() as object[];

will work

Import functions from another js file. Javascript

By default, scripts can't handle imports like that directly. You're probably getting another error about not being able to get Course or not doing the import.

If you add type="module" to your <script> tag, and change the import to ./course.js (because browsers won't auto-append the .js portion), then the browser will pull down course for you and it'll probably work.

import './course.js';

function Student() {
    this.firstName = '';
    this.lastName = '';
    this.course = new Course();
}

<html>
    <head>
        <script src="./models/student.js" type="module"></script>
    </head>
    <body>
        <div id="myDiv">
        </div>
        <script>
        window.onload= function() {
            var x = new Student();
            x.course.id = 1;
            document.getElementById('myDiv').innerHTML = x.course.id;
        }
        </script>
    </body>
</html>

If you're serving files over file://, it likely won't work. Some IDEs have a way to run a quick sever.

You can also write a quick express server to serve your files (install Node if you don't have it):

//package.json
{
  "scripts": { "start": "node server" },
  "dependencies": { "express": "latest" }
}

// server/index.js
const express = require('express');
const app = express();

app.use('/', express.static('PATH_TO_YOUR_FILES_HERE');
app.listen(8000);

With those two files, run npm install, then npm start and you'll have a server running over http://localhost:8000 which should point to your files.

Static methods in Python?

You don't really need to use the @staticmethod decorator. Just declaring a method (that doesn't expect the self parameter) and call it from the class. The decorator is only there in case you want to be able to call it from an instance as well (which was not what you wanted to do)

Mostly, you just use functions though...

Use CSS to automatically add 'required field' asterisk to form inputs

It is 2019 and previous answers to this problem are not using

  1. CSS grid
  2. CSS variables
  3. HTML5 form elements
  4. SVG in CSS

CSS grid is the way to do forms in 2019 as you can have your labels preceding your inputs without having extra divs, spans, spans with asterisks in and other relics.

Here is where we are going with minimal CSS:

Example screenshot

The HTML for the above:

<form action="https://www.example.com/register/" method="post" id="form-validate" enctype="multipart/form-data">
    <p class="form-instructions">Please enter the following information to create your account.</p>
    <label for="firstname">First name</label>
    <input type="text" id="firstname" name="firstname" value="" title="First name" maxlength="255" required="">
    <label for="lastname">Last name</label>
    <input type="text" id="lastname" name="lastname" value="" title="Last name" maxlength="255" required="">
    <label for="email_address">Email address</label>
    <input type="email" autocapitalize="off" autocorrect="off" spellcheck="false" name="email" id="email_address" value="" title="Email address" size="30" required="">
    <label for="password">Password</label>
    <input type="password" name="password" id="password" title="Password" required="">
    <label for="confirmation">Confirm password</label>
    <input type="password" name="confirmation" title="Confirm password" id="confirmation" required="">
    <input type="checkbox" name="is_subscribed" title="Subscribe to our newsletter" value="1" id="is_subscribed" class="checkbox">
    <label for="is_subscribed">Subscribe to the newsletter</label>
    <input type="checkbox" name="persistent_remember_me" id="remember_meGCJiRe0GbJ" checked="checked" title="Remember me">
    <label for="remember_meGCJiRe0GbJ">Remember me</label>
    <p class="required">* Required</p>
    <button type="submit" title="Register">Register</button>
</form>

Placeholder text can be added too and is highly recommended. (I am just answering this mid-form).

Now for the CSS variables:

--icon-required: url('data:image/svg+xml,\
<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100" viewBox="-10 -6 16 16"> \
  <line id="line" y1="-3" y2="3" stroke="%23df0000" stroke-linecap="butt" transform="rotate(15)"></line> \
  <line id="line" y1="-3" y2="3" stroke="%23df0000" stroke-linecap="butt" transform="rotate(75)"></line> \
  <line id="line" y1="-3" y2="3" stroke="%23df0000" stroke-linecap="butt" transform="rotate(-45)"></line> \
</svg>');

--icon-tick: url('data:image/svg+xml,\
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="100" height="100" viewBox="-2 -2 16 16"> \
            <path fill="green" stroke-linejoin="round" d="M2 6L1 7l3 4 7-10h-1L4 8z"/> \
</svg>');

The CSS for the form elements:

input[type=text][required],
input[type=email][required],
input[type=password][required],
input[type=tel][required] {
    background-image: var(--icon-required);
    background-position-x: right;
    background-repeat: no-repeat;
    background-size: contain;
}

input:valid {
    --icon-required: var(--icon-tick);
}

The form itself should be in CSS grid:

form {
    align-items: center;
    display: grid;
    grid-gap: var(--form-grid-gap);
    grid-template-columns: var(--form-grid-template-columns);
    margin: auto;
}

The values for the columns can be set to 1fr auto or 1fr with anything such as <p> tags in the form set to span 1/-1. You change the variables in your media queries so that you have the input boxes going full width on mobile and as per above on desktop. You can also change your grid gap on mobile if you wish by using the CSS variables approach.

When the boxes are valid then you should get a green tick instead of the asterisk.

The SVG in CSS is a way of saving the browser from having to do a round trip to the server to get an image of the asterisk. In this way you can fine tune the asterisks, the examples here are at an unusual angle, you can edit this out as the SVG icon above is entirely readable. The viewbox can also be amended to place the asterisk above or below the centre.

matplotlib does not show my drawings although I call pyplot.show()

For future reference,

I have encountered the same problem -- pylab was not showing under ipython. The problem was fixed by changing ipython's config file {ipython_config.py}. In the config file

c.InteractiveShellApp.pylab = 'auto'

I changed 'auto' to 'qt' and now I see graphs

Find the maximum value in a list of tuples in Python

In addition to max, you can also sort:

>>> lis
[(101, 153), (255, 827), (361, 961)]
>>> sorted(lis,key=lambda x: x[1], reverse=True)[0]
(361, 961)

Convert JSON string to dict using Python

use simplejson or cjson for speedups

import simplejson as json

json.loads(obj)

or 

cjson.decode(obj)

UTF-8 output from PowerShell

Not an expert on encoding, but after reading these...

... it seems fairly clear that the $OutputEncoding variable only affects data piped to native applications.

If sending to a file from withing PowerShell, the encoding can be controlled by the -encoding parameter on the out-file cmdlet e.g.

write-output "hello" | out-file "enctest.txt" -encoding utf8

Nothing else you can do on the PowerShell front then, but the following post may well help you:.

How can I check for IsPostBack in JavaScript?

Here is one way (put this in Page_Load):

if (this.IsPostBack)
{
    Page.ClientScript.RegisterStartupScript(this.GetType(),"PostbackKey","<script type='text/javascript'>var isPostBack = true;</script>");
}

Then just check that variable in the JS.

Change windows hostname from command line

cmd (command):

netdom renamecomputer %COMPUTERNAME% /Newname "NEW-NAME"

powershell (windows 2008/2012):

netdom renamecomputer "$env:COMPUTERNAME" /Newname "NEW-NAME"

after that, you need to reboot your computer.

adding css class to multiple elements

Try using:

.button input, .button a {
    // css stuff
}

Also, read up on CSS.

Edit: If it were me, I'd add the button class to the element, not to the parent tag. Like so:

HTML:

<a href="#" class='button'>BUTTON TEXT</a>
<input type="submit" class='button' value='buttontext' />

CSS:

.button {
    // css stuff
}

For specific css stuff use:

input.button {
    // css stuff
}
a.button {
    // css stuff
}

How to open a web page automatically in full screen mode

Only works in IE:

window.open ("mapage.html","","fullscreen=yes");  
window.open('','_parent','');  
window.close();

Difference between Subquery and Correlated Subquery

Correlated Subquery is a sub-query that uses values from the outer query. In this case the inner query has to be executed for every row of outer query.

See example here http://en.wikipedia.org/wiki/Correlated_subquery

Simple subquery doesn't use values from the outer query and is being calculated only once:

SELECT id, first_name 
FROM student_details 
WHERE id IN (SELECT student_id
FROM student_subjects 
WHERE subject= 'Science'); 

CoRelated Subquery Example -

Query To Find all employees whose salary is above average for their department

 SELECT employee_number, name
       FROM employees emp
       WHERE salary > (
         SELECT AVG(salary)
           FROM employees
           WHERE department = emp.department);

Saving and loading objects and using pickle

Always open in binary mode, in this case

file = open("Fruits.obj",'rb')

How do you modify the web.config appSettings at runtime?

Try This:

using System;
using System.Configuration;
using System.Web.Configuration;

namespace SampleApplication.WebConfig
{
    public partial class webConfigFile : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            //Helps to open the Root level web.config file.
            Configuration webConfigApp = WebConfigurationManager.OpenWebConfiguration("~");
            //Modifying the AppKey from AppValue to AppValue1
            webConfigApp.AppSettings.Settings["ConnectionString"].Value = "ConnectionString";
            //Save the Modified settings of AppSettings.
            webConfigApp.Save();
        }
    }
}

store return json value in input hidden field

You can use input.value = JSON.stringify(obj) to transform the object to a string.
And when you need it back you can use obj = JSON.parse(input.value)

The JSON object is available on modern browsers or you can use the json2.js library from json.org

How do you run multiple programs in parallel from a bash script?

Here is a function I use in order to run at max n process in parallel (n=4 in the example):

max_children=4

function parallel {
  local time1=$(date +"%H:%M:%S")
  local time2=""

  # for the sake of the example, I'm using $2 as a description, you may be interested in other description
  echo "starting $2 ($time1)..."
  "$@" && time2=$(date +"%H:%M:%S") && echo "finishing $2 ($time1 -- $time2)..." &

  local my_pid=$$
  local children=$(ps -eo ppid | grep -w $my_pid | wc -w)
  children=$((children-1))
  if [[ $children -ge $max_children ]]; then
    wait -n
  fi
}

parallel sleep 5
parallel sleep 6
parallel sleep 7
parallel sleep 8
parallel sleep 9
wait

If max_children is set to the number of cores, this function will try to avoid idle cores.

href around input type submit

You can do do it. The input type submit should be inside of a form. Then all you have to do is write the link you want to redirect to inside the action attribute that is inside the form tag.

How do I import an SQL file using the command line in MySQL?

Add the --force option:

mysql -u username -p database_name --force < file.sql

Handling urllib2's timeout? - Python

There are very few cases where you want to use except:. Doing this captures any exception, which can be hard to debug, and it captures exceptions including SystemExit and KeyboardInterupt, which can make your program annoying to use..

At the very simplest, you would catch urllib2.URLError:

try:
    urllib2.urlopen("http://example.com", timeout = 1)
except urllib2.URLError, e:
    raise MyException("There was an error: %r" % e)

The following should capture the specific error raised when the connection times out:

import urllib2
import socket

class MyException(Exception):
    pass

try:
    urllib2.urlopen("http://example.com", timeout = 1)
except urllib2.URLError, e:
    # For Python 2.6
    if isinstance(e.reason, socket.timeout):
        raise MyException("There was an error: %r" % e)
    else:
        # reraise the original error
        raise
except socket.timeout, e:
    # For Python 2.7
    raise MyException("There was an error: %r" % e)

Jquery Open in new Tab (_blank)

Replace this line:

$(this).target = "_blank";

With:

$( this ).attr( 'target', '_blank' );

That will set its HREF to _blank.

linux shell script: split string, put them in an array then loop through them

If you don't wish to mess with IFS (perhaps for the code within the loop) this might help.

If know that your string will not have whitespace, you can substitute the ';' with a space and use the for/in construct:

#local str
for str in ${STR//;/ } ; do 
   echo "+ \"$str\""
done

But if you might have whitespace, then for this approach you will need to use a temp variable to hold the "rest" like this:

#local str rest
rest=$STR
while [ -n "$rest" ] ; do
   str=${rest%%;*}  # Everything up to the first ';'
   # Trim up to the first ';' -- and handle final case, too.
   [ "$rest" = "${rest/;/}" ] && rest= || rest=${rest#*;}
   echo "+ \"$str\""
done

What is the standard Python docstring format?

It's Python; anything goes. Consider how to publish your documentation. Docstrings are invisible except to readers of your source code.

People really like to browse and search documentation on the web. To achieve that, use the documentation tool Sphinx. It's the de-facto standard for documenting Python projects. The product is beautiful - take a look at https://python-guide.readthedocs.org/en/latest/ . The website Read the Docs will host your docs for free.

Vue-router redirect on page not found (404)

@mani's response is now slightly outdated as using catch-all '*' routes is no longer supported when using Vue 3 onward. If this is no longer working for you, try replacing the old catch-all path with

{ path: '/:pathMatch(.*)*', component: PathNotFound },

Essentially, you should be able to replace the '*' path with '/:pathMatch(.*)*' and be good to go!

Reason: Vue Router doesn't use path-to-regexp anymore, instead it implements its own parsing system that allows route ranking and enables dynamic routing. Since we usually add one single catch-all route per project, there is no big benefit in supporting a special syntax for *.

(from https://next.router.vuejs.org/guide/migration/#removed-star-or-catch-all-routes)

How to display and hide a div with CSS?

To hide an element, use:

display: none;
visibility: hidden;

To show an element, use:

display: block;
visibility: visible;

The difference is:

Visibility handles the visibility of the tag, the display handles space it occupies on the page.

If you set the visibility and do not change the display, even if the tags are not seen, it still occupies space.

How to properly compare two Integers in Java?

== will still test object equality. It is easy to be fooled, however:

Integer a = 10;
Integer b = 10;

System.out.println(a == b); //prints true

Integer c = new Integer(10);
Integer d = new Integer(10);

System.out.println(c == d); //prints false

Your examples with inequalities will work since they are not defined on Objects. However, with the == comparison, object equality will still be checked. In this case, when you initialize the objects from a boxed primitive, the same object is used (for both a and b). This is an okay optimization since the primitive box classes are immutable.

Pull new updates from original GitHub repository into forked GitHub repository

If you want to do it without cli, you can do it fully on Github website.

  1. Go to your fork repository.
  2. Click on New pull request.
  3. Make sure to set your fork as the base repository, and the original (upstream) repository as head repository. Usually you only want to sync the master branch.
  4. Create new pull request.
  5. Select the arrow to the right of the merging button, and make sure to choose rebase instead of merge. Then click the button. This way, it will not produce unnecessary merge commit.
  6. Done.

Struct Constructor in C++?

Yes it possible to have constructor in structure here is one example:

#include<iostream.h> 
struct a {
  int x;
  a(){x=100;}
};

int main() {
  struct a a1;
  getch();
}

How to find if div with specific id exists in jQuery?

The most simple way is..

if(window["myId"]){
    // ..
}

This is also part of HTML5 specs: https://www.w3.org/TR/html5/single-page.html#accessing-other-browsing-contexts#named-access-on-the-window-object

window[name]
    Returns the indicated element or collection of elements.

Python re.sub replace with matched content

Simply use \1 instead of $1:

In [1]: import re

In [2]: method = 'images/:id/huge'

In [3]: re.sub(r'(:[a-z]+)', r'<span>\1</span>', method)
Out[3]: 'images/<span>:id</span>/huge'

Also note the use of raw strings (r'...') for regular expressions. It is not mandatory but removes the need to escape backslashes, arguably making the code slightly more readable.

How do I get the browser scroll position in jQuery?

It's better to use $(window).scroll() rather than $('#Eframe').on("mousewheel")

$('#Eframe').on("mousewheel") will not trigger if people manually scroll using up and down arrows on the scroll bar or grabbing and dragging the scroll bar itself.

$(window).scroll(function(){
    var scrollPos = $(document).scrollTop();
    console.log(scrollPos);
});

If #Eframe is an element with overflow:scroll on it and you want it's scroll position. I think this should work (I haven't tested it though).

$('#Eframe').scroll(function(){
    var scrollPos = $('#Eframe').scrollTop();
    console.log(scrollPos);
});

Passing variables in remote ssh command

Escape the variable in order to access variables outside of the ssh session: ssh [email protected] "~/tools/myScript.pl \$BUILD_NUMBER"

How does Zalgo text work?

The text uses combining characters, also known as combining marks. See section 2.11 of Combining Characters in the Unicode Standard (PDF).

In Unicode, character rendering does not use a simple character cell model where each glyph fits into a box with given height. Combining marks may be rendered above, below, or inside a base character

So you can easily construct a character sequence, consisting of a base character and “combining above” marks, of any length, to reach any desired visual height, assuming that the rendering software conforms to the Unicode rendering model. Such a sequence has no meaning of course, and even a monkey could produce it (e.g., given a keyboard with suitable driver).

And you can mix “combining above” and “combining below” marks.

The sample text in the question starts with:

How to check if an Object is a Collection Type in Java?

Test if the object implements either java.util.Collection or java.util.Map. (Map has to be tested separately because it isn't a sub-interface of Collection.)

Is there a way to make mv create the directory to be moved to if it doesn't exist?

The simpliest way to do that is:

mkdir [directory name] && mv [filename] $_

Let's suppose I downloaded pdf files located in my download directory (~/download) and I want to move all of them into a directory that doesn't exist (let's say my_PDF).

I'll type the following command (making sure my current working directory is ~/download):

mkdir my_PDF && mv *.pdf $_

You can add -p option to mkdir if you want to create subdirectories just like this: (supposed I want to create a subdirectory named python):

mkdir -p my_PDF/python && mv *.pdf $_

The infamous java.sql.SQLException: No suitable driver found

Run java with CLASSPATH environmental variable pointing to driver's JAR file, e.g.

CLASSPATH='.:drivers/mssql-jdbc-6.2.1.jre8.jar' java ConnectURL

Where drivers/mssql-jdbc-6.2.1.jre8.jar is the path to driver file (e.g. JDBC for for SQL Server).

The ConnectURL is the sample app from that driver (samples/connections/ConnectURL.java), compiled via javac ConnectURL.java.

Flutter Countdown Timer

You can use this plugin timer_builder

timer_builder widget that rebuilds itself on scheduled, periodic, or dynamically generated time events.

Examples

Periodic rebuild

import 'package:timer_builder/timer_builder.dart';

class ClockWidget extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return TimerBuilder.periodic(Duration(seconds: 1),
      builder: (context) {
        return Text("${DateTime.now()}");
      }
    );
  }
  
}

Rebuild on a schedule

import 'package:timer_builder/timer_builder.dart';

class StatusIndicator extends StatelessWidget {

  final DateTime startTime;
  final DateTime endTime;
  
  StatusIndicator(this.startTime, this.endTime);
  
  @override
  Widget build(BuildContext context) {
    return TimerBuilder.scheduled([startTime, endTime],
      builder: (context) {
        final now = DateTime.now();
        final started = now.compareTo(startTime) >= 0;
        final ended = now.compareTo(endTime) >= 0;
        return Text(started ? ended ? "Ended": "Started": "Not Started");
      }
    );
  }
  
}

enter image description here

Ruby on Rails 3 Can't connect to local MySQL server through socket '/tmp/mysql.sock' on OSX

These are options to fix this problem:

Option 1: change you host into 127.0.0.1

staging:
  adapter: mysql2
  host: 127.0.0.1
  username: root
  password: xxxx
  database: xxxx
  socket: your-location-socket

Option 2: It seems like you have 2 connections into you server MySql. To find your socket file location do this:

mysqladmin variables | grep socket

for me gives:

mysqladmin: connect to server at 'localhost' failed
error: 'Can't connect to local MySQL server through socket '/Applications/XAMPP/xamppfiles/var/mysql/mysql.sock' (2)'
Check that mysqld is running and that the socket: '/Applications/XAMPP/xamppfiles/var/mysql/mysql.sock' exists!

or

mysql --help 

I get this error because I installed XAMPP in my OS X Version 10.9.5 for PHP application. Choose one of the default socket location here.

I choose for default rails apps:

socket: /tmp/mysql.sock

For my PHP apps, I install XAMPP so I set my socket here:

socket: /Applications/XAMPP/xamppfiles/var/mysql/mysql.sock

OTHERS Socket Location in OS X

For MAMPP:

socket: /Applications/MAMP/tmp/mysql/mysql.sock

For Package Installer from MySQL:

socket: /tmp/mysql.sock

For MySQL Bundled with Mac OS X Server:

socket: /var/mysql/mysql.sock

For Ubuntu:

socket: /var/run/mysqld/mysql.sock

Option 3: If all those setting doesn't work you can remove your socket location:

staging:
  # socket: /var/run/mysqld/mysql.sock

I hope this help you.

Get combobox value in Java swing

Method Object JComboBox.getSelectedItem() returns a value that is wrapped by Object type so you have to cast it accordingly.

Syntax:

YourType varName = (YourType)comboBox.getSelectedItem();`
String value = comboBox.getSelectedItem().toString();

What is the difference between JavaScript and jQuery?

Javascript is base of jQuery.

jQuery is a wrapper of JavaScript, with much pre-written functionality and DOM traversing.

How do I get the current date in Cocoa

Original poster - the way you're determining seconds until midnight won't work on a day when daylight savings starts or ends. Here's a chunk of code which shows how to do it... It'll be in number of seconds (an NSTimeInterval); you can do the division/modulus/etc to get down to whatever you need.

NSDateComponents *dc = [[NSCalendar currentCalendar] components:NSDayCalendarUnit|NSMonthCalendarUnit|NSYearCalendarUnit fromDate:[NSDate date]];
[dc setDay:dc.day + 1];
NSDate *midnightDate = [[NSCalendar currentCalendar] dateFromComponents:dc];
NSLog(@"Now: %@, Tonight Midnight: %@, Hours until midnight: %.1f", [NSDate date], midnightDate, [midnightDate timeIntervalSinceDate:[NSDate date]] / 60.0 / 60.0);

How to set a value of a variable inside a template code?

The best solution for this is to write a custom assignment_tag. This solution is more clean than using a with tag because it achieves a very clear separation between logic and styling.

Start by creating a template tag file (eg. appname/templatetags/hello_world.py):

from django import template

register = template.Library()

@register.assignment_tag
def get_addressee():
    return "World"

Now you may use the get_addressee template tag in your templates:

{% load hello_world %}

{% get_addressee as addressee %}

<html>
    <body>
        <h1>hello {{addressee}}</h1>
    </body>
</html>

Reading a huge .csv file

For someone who lands to this question. Using pandas with ‘chunksize’ and ‘usecols’ helped me to read a huge zip file faster than the other proposed options.

import pandas as pd

sample_cols_to_keep =['col_1', 'col_2', 'col_3', 'col_4','col_5']

# First setup dataframe iterator, ‘usecols’ parameter filters the columns, and 'chunksize' sets the number of rows per chunk in the csv. (you can change these parameters as you wish)
df_iter = pd.read_csv('../data/huge_csv_file.csv.gz', compression='gzip', chunksize=20000, usecols=sample_cols_to_keep) 

# this list will store the filtered dataframes for later concatenation 
df_lst = [] 

# Iterate over the file based on the criteria and append to the list
for df_ in df_iter: 
        tmp_df = (df_.rename(columns={col: col.lower() for col in df_.columns}) # filter eg. rows where 'col_1' value grater than one
                                  .pipe(lambda x:  x[x.col_1 > 0] ))
        df_lst += [tmp_df.copy()] 

# And finally combine filtered df_lst into the final lareger output say 'df_final' dataframe 
df_final = pd.concat(df_lst)

Turning off hibernate logging console output

Important notice: the property (part of hibernate configuration, NOT part of logging framework config!)

hibernate.show_sql

controls the logging directly to STDOUT bypassing any logging framework (which you can recognize by the missing output formatting of the messages). If you use a logging framework like log4j, you should always set that property to false because it gives you no benefit at all.

That circumstance irritated me quite a long time because I never really cared about it until I tried to write some benchmark regarding Hibernate.

PostgreSQL JOIN data from 3 tables

Something like:

select t1.name, t2.image_id, t3.path
from table1 t1 inner join table2 t2 on t1.person_id = t2.person_id
inner join table3 t3 on t2.image_id=t3.image_id

Error: Selection does not contain a main type

I hope you are trying to run the main class in this way, see screenshot:
screenshot of Eclipse file context menu

If not, then try this way. If yes, then please make sure that your class you are trying to run has a main method, that is, the same method definition as below:

public static void main(String[] args) {
    // some code here
}

I hope this will help you.

What does ON [PRIMARY] mean?

ON [PRIMARY] will create the structures on the "Primary" filegroup. In this case the primary key index and the table will be placed on the "Primary" filegroup within the database.

How to delete all instances of a character in a string in python?

Strings are immutable in Python, which means once a string is created, you cannot alter the contents of the strings. If at all, you need to change it, a new instance of the string will be created with the alterations.

Having that in mind, we have so many ways to solve this

  1. Using str.replace,

    >>> "it is icy".replace("i", "")
    't s cy'
    
  2. Using str.translate,

    >>> "it is icy".translate(None, "i")
    't s cy'
    
  3. Using Regular Expression,

    >>> import re
    >>> re.sub(r'i', "", "it is icy")
    't s cy'
    
  4. Using comprehension as a filter,

    >>> "".join([char for char in "it is icy" if char != "i"])
    't s cy'
    
  5. Using filter function

    >>> "".join(filter(lambda char: char != "i", "it is icy"))
    't s cy'
    

Timing comparison

def findreplace(m_string, char):
    m_string = list(m_string)
    for k in m_string:
        if k == char:
            del(m_string[m_string.index(k)])
    return "".join(m_string)

def replace(m_string, char):
    return m_string.replace("i", "")

def translate(m_string, char):
    return m_string.translate(None, "i")

from timeit import timeit

print timeit("findreplace('it is icy','i')", "from __main__ import findreplace")
print timeit("replace('it is icy','i')", "from __main__ import replace")
print timeit("translate('it is icy','i')", "from __main__ import translate")

Result

1.64474582672
0.29278588295
0.311302900314

str.replace and str.translate methods are 8 and 5 times faster than the accepted answer.

Note: Comprehension method and filter methods are expected to be slower, for this case, since they have to create list and then they have to be traversed again to construct a string. And re is a bit overkill for a single character replacement. So, they all are excluded from the timing comparison.

Difference between size and length methods?

length variable:

In Java, array (not java.util.Array) is a predefined class in the language itself. To find the elements of an array, designers used length variable (length is a field member in the predefined class). They must have given length() itself to have uniformity in Java; but did not. The reason is by performance, executing length variable is speedier than calling the method length(). It is like comparing two strings with == and equals(). equals() is a method call which takes more time than executing == operator.

size() method:

It is used to find the number of elements present in collection classes. It is defined in java.util.Collection interface.

Style child element when hover on parent

you can use this too

_x000D_
_x000D_
.parent:hover * {
   /* ... */
}
_x000D_
_x000D_
_x000D_

Quick Sort Vs Merge Sort

I personally wanted to test the difference between Quick sort and merge sort myself and saw the running times for a sample of 1,000,000 elements.

Quick sort was able to do it in 156 milliseconds whereas Merge sort did the same in 247 milliseconds

The Quick sort data, however, was random and quick sort performs well if the data is random where as its not the case with merge sort i.e. merge sort performs the same, irrespective of whether data is sorted or not. But merge sort requires one full extra space and quick sort does not as its an in-place sort

I have written comprehensive working program for them will illustrative pictures too.

How to force R to use a specified factor level as reference in a regression?

You can also manually tag the column with a contrasts attribute, which seems to be respected by the regression functions:

contrasts(df$factorcol) <- contr.treatment(levels(df$factorcol),
   base=which(levels(df$factorcol) == 'RefLevel'))

how to change text box value with jQuery?

Document ready function was missing thats why the code was not working. For example:

$(function(){

 $('#button1').click(function(){
   $('#txtbox1').val('Changed Value');
 });

});

git pull displays "fatal: Couldn't find remote ref refs/heads/xxxx" and hangs up

I just ran into a similar issue when I tried to commit to a newly created repo with a "." in it's name. I've seen several others have different issues with putting a "." in the repo name.

I just re-created the repo and

replaced "." with "-"

There may be other ways to resolve this, but this was a quick fix for me since it was a new repo.

How to get the top 10 values in postgresql?

(SELECT <some columns>
FROM mytable
<maybe some joins here>
WHERE <various conditions>
ORDER BY date DESC
LIMIT 10)

UNION ALL

(SELECT <some columns>
FROM mytable
<maybe some joins here>
WHERE <various conditions>
ORDER BY date ASC    
LIMIT 10)

nginx: send all requests to a single html page

Using just try_files didn't work for me - it caused a rewrite or internal redirection cycle error in my logs.

The Nginx docs had some additional details:

http://nginx.org/en/docs/http/ngx_http_core_module.html#try_files

So I ended up using the following:

root /var/www/mysite;

location / {
    try_files $uri /base.html;
}

location = /base.html {
    expires 30s;
}

How can I get log4j to delete old rotating log files?

You can achieve it using custom log4j appender.
MaxNumberOfDays - possibility to set amount of days of rotated log files.
CompressBackups - possibility to archive old logs with zip extension.

package com.example.package;

import org.apache.log4j.FileAppender;
import org.apache.log4j.Layout;
import org.apache.log4j.helpers.LogLog;
import org.apache.log4j.spi.LoggingEvent;

import java.io.File;
import java.io.FileFilter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.file.Files;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;
import java.util.Optional;
import java.util.TimeZone;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

public class CustomLog4jAppender extends FileAppender {

    private static final int TOP_OF_TROUBLE = -1;
    private static final int TOP_OF_MINUTE = 0;
    private static final int TOP_OF_HOUR = 1;
    private static final int HALF_DAY = 2;
    private static final int TOP_OF_DAY = 3;
    private static final int TOP_OF_WEEK = 4;
    private static final int TOP_OF_MONTH = 5;

    private String datePattern = "'.'yyyy-MM-dd";
    private String compressBackups = "false";
    private String maxNumberOfDays = "7";
    private String scheduledFilename;
    private long nextCheck = System.currentTimeMillis() - 1;
    private Date now = new Date();
    private SimpleDateFormat sdf;
    private RollingCalendar rc = new RollingCalendar();

    private static final TimeZone gmtTimeZone = TimeZone.getTimeZone("GMT");

    public CustomLog4jAppender() {
    }

    public CustomLog4jAppender(Layout layout, String filename, String datePattern) throws IOException {
        super(layout, filename, true);
        this.datePattern = datePattern;
        activateOptions();
    }

    public void setDatePattern(String pattern) {
        datePattern = pattern;
    }

    public String getDatePattern() {
        return datePattern;
    }

    @Override
    public void activateOptions() {
        super.activateOptions();
        if (datePattern != null && fileName != null) {
            now.setTime(System.currentTimeMillis());
            sdf = new SimpleDateFormat(datePattern);
            int type = computeCheckPeriod();
            printPeriodicity(type);
            rc.setType(type);
            File file = new File(fileName);
            scheduledFilename = fileName + sdf.format(new Date(file.lastModified()));
        } else {
            LogLog.error("Either File or DatePattern options are not set for appender [" + name + "].");
        }
    }

    private void printPeriodicity(int type) {
        String appender = "Log4J Appender: ";
        switch (type) {
            case TOP_OF_MINUTE:
                LogLog.debug(appender + name + " to be rolled every minute.");
                break;
            case TOP_OF_HOUR:
                LogLog.debug(appender + name + " to be rolled on top of every hour.");
                break;
            case HALF_DAY:
                LogLog.debug(appender + name + " to be rolled at midday and midnight.");
                break;
            case TOP_OF_DAY:
                LogLog.debug(appender + name + " to be rolled at midnight.");
                break;
            case TOP_OF_WEEK:
                LogLog.debug(appender + name + " to be rolled at start of week.");
                break;
            case TOP_OF_MONTH:
                LogLog.debug(appender + name + " to be rolled at start of every month.");
                break;
            default:
                LogLog.warn("Unknown periodicity for appender [" + name + "].");
        }
    }

    private int computeCheckPeriod() {
        RollingCalendar rollingCalendar = new RollingCalendar(gmtTimeZone, Locale.ENGLISH);
        Date epoch = new Date(0);
        if (datePattern != null) {
            for (int i = TOP_OF_MINUTE; i <= TOP_OF_MONTH; i++) {
                SimpleDateFormat simpleDateFormat = new SimpleDateFormat(datePattern);
                simpleDateFormat.setTimeZone(gmtTimeZone);
                String r0 = simpleDateFormat.format(epoch);
                rollingCalendar.setType(i);
                Date next = new Date(rollingCalendar.getNextCheckMillis(epoch));
                String r1 = simpleDateFormat.format(next);
                if (!r0.equals(r1)) {
                    return i;
                }
            }
        }
        return TOP_OF_TROUBLE;
    }

    private void rollOver() throws IOException {
        if (datePattern == null) {
            errorHandler.error("Missing DatePattern option in rollOver().");
            return;
        }
        String datedFilename = fileName + sdf.format(now);
        if (scheduledFilename.equals(datedFilename)) {
            return;
        }
        this.closeFile();
        File target = new File(scheduledFilename);
        if (target.exists()) {
            Files.delete(target.toPath());
        }
        File file = new File(fileName);
        boolean result = file.renameTo(target);
        if (result) {
            LogLog.debug(fileName + " -> " + scheduledFilename);
        } else {
            LogLog.error("Failed to rename [" + fileName + "] to [" + scheduledFilename + "].");
        }
        try {
            this.setFile(fileName, false, this.bufferedIO, this.bufferSize);
        } catch (IOException e) {
            errorHandler.error("setFile(" + fileName + ", false) call failed.");
        }
        scheduledFilename = datedFilename;
    }

    @Override
    protected void subAppend(LoggingEvent event) {
        long n = System.currentTimeMillis();
        if (n >= nextCheck) {
            now.setTime(n);
            nextCheck = rc.getNextCheckMillis(now);
            try {
                cleanupAndRollOver();
            } catch (IOException ioe) {
                LogLog.error("cleanupAndRollover() failed.", ioe);
            }
        }
        super.subAppend(event);
    }

    public String getCompressBackups() {
        return compressBackups;
    }

    public void setCompressBackups(String compressBackups) {
        this.compressBackups = compressBackups;
    }

    public String getMaxNumberOfDays() {
        return maxNumberOfDays;
    }

    public void setMaxNumberOfDays(String maxNumberOfDays) {
        this.maxNumberOfDays = maxNumberOfDays;
    }

    protected void cleanupAndRollOver() throws IOException {
        File file = new File(fileName);
        Calendar cal = Calendar.getInstance();
        int maxDays = 7;
        try {
            maxDays = Integer.parseInt(getMaxNumberOfDays());
        } catch (Exception e) {
            // just leave it at 7.
        }
        cal.add(Calendar.DATE, -maxDays);
        Date cutoffDate = cal.getTime();
        if (file.getParentFile().exists()) {
            File[] files = file.getParentFile().listFiles(new StartsWithFileFilter(file.getName(), false));
            int nameLength = file.getName().length();
            for (File value : Optional.ofNullable(files).orElse(new File[0])) {
                String datePart;
                try {
                    datePart = value.getName().substring(nameLength);
                    Date date = sdf.parse(datePart);
                    if (date.before(cutoffDate)) {
                        Files.delete(value.toPath());
                    } else if (getCompressBackups().equalsIgnoreCase("YES") || getCompressBackups().equalsIgnoreCase("TRUE")) {
                        zipAndDelete(value);
                    }
                } catch (Exception pe) {
                    // This isn't a file we should touch (it isn't named correctly)
                }
            }
        }
        rollOver();
    }

    private void zipAndDelete(File file) throws IOException {
        if (!file.getName().endsWith(".zip")) {
            File zipFile = new File(file.getParent(), file.getName() + ".zip");
            try (FileInputStream fis = new FileInputStream(file);
                 FileOutputStream fos = new FileOutputStream(zipFile);
                 ZipOutputStream zos = new ZipOutputStream(fos)) {
                ZipEntry zipEntry = new ZipEntry(file.getName());
                zos.putNextEntry(zipEntry);
                byte[] buffer = new byte[4096];
                while (true) {
                    int bytesRead = fis.read(buffer);
                    if (bytesRead == -1) {
                        break;
                    } else {
                        zos.write(buffer, 0, bytesRead);
                    }
                }
                zos.closeEntry();
            }
            Files.delete(file.toPath());
        }
    }

    class StartsWithFileFilter implements FileFilter {
        private String startsWith;
        private boolean inclDirs;

        StartsWithFileFilter(String startsWith, boolean includeDirectories) {
            super();
            this.startsWith = startsWith.toUpperCase();
            inclDirs = includeDirectories;
        }

        public boolean accept(File pathname) {
            if (!inclDirs && pathname.isDirectory()) {
                return false;
            } else {
                return pathname.getName().toUpperCase().startsWith(startsWith);
            }
        }
    }

    class RollingCalendar extends GregorianCalendar {
        private static final long serialVersionUID = -3560331770601814177L;

        int type = CustomLog4jAppender.TOP_OF_TROUBLE;

        RollingCalendar() {
            super();
        }

        RollingCalendar(TimeZone tz, Locale locale) {
            super(tz, locale);
        }

        void setType(int type) {
            this.type = type;
        }

        long getNextCheckMillis(Date now) {
            return getNextCheckDate(now).getTime();
        }

        Date getNextCheckDate(Date now) {
            this.setTime(now);

            switch (type) {
                case CustomLog4jAppender.TOP_OF_MINUTE:
                    this.set(Calendar.SECOND, 0);
                    this.set(Calendar.MILLISECOND, 0);
                    this.add(Calendar.MINUTE, 1);
                    break;
                case CustomLog4jAppender.TOP_OF_HOUR:
                    this.set(Calendar.MINUTE, 0);
                    this.set(Calendar.SECOND, 0);
                    this.set(Calendar.MILLISECOND, 0);
                    this.add(Calendar.HOUR_OF_DAY, 1);
                    break;
                case CustomLog4jAppender.HALF_DAY:
                    this.set(Calendar.MINUTE, 0);
                    this.set(Calendar.SECOND, 0);
                    this.set(Calendar.MILLISECOND, 0);
                    int hour = get(Calendar.HOUR_OF_DAY);
                    if (hour < 12) {
                        this.set(Calendar.HOUR_OF_DAY, 12);
                    } else {
                        this.set(Calendar.HOUR_OF_DAY, 0);
                        this.add(Calendar.DAY_OF_MONTH, 1);
                    }
                    break;
                case CustomLog4jAppender.TOP_OF_DAY:
                    this.set(Calendar.HOUR_OF_DAY, 0);
                    this.set(Calendar.MINUTE, 0);
                    this.set(Calendar.SECOND, 0);
                    this.set(Calendar.MILLISECOND, 0);
                    this.add(Calendar.DATE, 1);
                    break;
                case CustomLog4jAppender.TOP_OF_WEEK:
                    this.set(Calendar.DAY_OF_WEEK, getFirstDayOfWeek());
                    this.set(Calendar.HOUR_OF_DAY, 0);
                    this.set(Calendar.MINUTE, 0);
                    this.set(Calendar.SECOND, 0);
                    this.set(Calendar.MILLISECOND, 0);
                    this.add(Calendar.WEEK_OF_YEAR, 1);
                    break;
                case CustomLog4jAppender.TOP_OF_MONTH:
                    this.set(Calendar.DATE, 1);
                    this.set(Calendar.HOUR_OF_DAY, 0);
                    this.set(Calendar.MINUTE, 0);
                    this.set(Calendar.SECOND, 0);
                    this.set(Calendar.MILLISECOND, 0);
                    this.add(Calendar.MONTH, 1);
                    break;
                default:
                    throw new IllegalStateException("Unknown periodicity type.");
            }
            return getTime();
        }
    }    
}

And use this properties in your log4j config file:

log4j.appender.[appenderName]=com.example.package.CustomLog4jAppender
log4j.appender.[appenderName].File=/logs/app-daily.log
log4j.appender.[appenderName].Append=true
log4j.appender.[appenderName].encoding=UTF-8
log4j.appender.[appenderName].layout=org.apache.log4j.EnhancedPatternLayout
log4j.appender.[appenderName].layout.ConversionPattern=%-5.5p %d %C{1.} - %m%n
log4j.appender.[appenderName].DatePattern='.'yyyy-MM-dd
log4j.appender.[appenderName].MaxNumberOfDays=7
log4j.appender.[appenderName].CompressBackups=true

DLL and LIB files - what and why?

One important reason for creating a DLL/LIB rather than just compiling the code into an executable is reuse and relocation. The average Java or .NET application (for example) will most likely use several 3rd party (or framework) libraries. It is much easier and faster to just compile against a pre-built library, rather than having to compile all of the 3rd party code into your application. Compiling your code into libraries also encourages good design practices, e.g. designing your classes to be used in different types of applications.

Not unique table/alias

Your query contains columns which could be present with the same name in more than one table you are referencing, hence the not unique error. It's best if you make the references explicit and/or use table aliases when joining.

Try

    SELECT pa.ProjectID, p.Project_Title, a.Account_ID, a.Username, a.Access_Type, c.First_Name, c.Last_Name
      FROM Project_Assigned pa
INNER JOIN Account a
        ON pa.AccountID = a.Account_ID
INNER JOIN Project p
        ON pa.ProjectID = p.Project_ID
INNER JOIN Clients c
        ON a.Account_ID = c.Account_ID
     WHERE a.Access_Type = 'Client';

Passing data to a jQuery UI Dialog

I have now tried your suggestions and found that it kinda works,

  1. The dialog div is alsways written out in plaintext
  2. With the $.post version it actually works in terms that the controller gets called and actually cancels the booking, but the dialog stays open and page doesn't refresh. With the get version window.location = h.ref works great.

Se my "new" script below:

$('a.cancel').click(function() {
        var a = this;               
        $("#dialog").dialog({
            autoOpen: false,
            buttons: {
                "Ja": function() {
                    $.post(a.href);                     
                },
                "Nej": function() { $(this).dialog("close"); }
            },
            modal: true,
            overlay: {
                opacity: 0.5,

            background: "black"
        }
    });
    $("#dialog").dialog('open');
    return false;
});

});

Any clues?

oh and my Action link now looks like this:

<%= Html.ActionLink("Cancel", "Cancel", new { id = v.BookingId }, new  { @class = "cancel" })%>

Getting assembly name

I use the Assembly to set the form's title as such:

private String BuildFormTitle()
{
    String AppName = System.Reflection.Assembly.GetEntryAssembly().GetName().Name;
    String FormTitle = String.Format("{0} {1} ({2})", 
                                     AppName, 
                                     Application.ProductName, 
                                     Application.ProductVersion);
    return FormTitle;
}

Android and setting width and height programmatically in dp units

Looking at your requirement, there is alternate solution as well. It seems you know the dimensions in dp at compile time, so you can add a dimen entry in the resources. Then you can query the dimen entry and it will be automatically converted to pixels in this call:

final float inPixels= mActivity.getResources().getDimension(R.dimen.dimen_entry_in_dp);

And your dimens.xml will have:

<dimen name="dimen_entry_in_dp">72dp</dimen>

Extending this idea, you can simply store the value of 1dp or 1sp as a dimen entry and query the value and use it as a multiplier. Using this approach you will insulate the code from the math stuff and rely on the library to perform the calculations.

pandas get column average/mean

Mean for each column in df :

    A   B   C
0   5   3   8
1   5   3   9
2   8   4   9

df.mean()

A    6.000000
B    3.333333
C    8.666667
dtype: float64

and if you want average of all columns:

df.stack().mean()
6.0

How to make the checkbox unchecked by default always

jQuery

$('input[type=checkbox]').removeAttr('checked');

Or

<!-- checked -->
<input type='checkbox' name='foo' value='bar' checked=''/> 

<!-- unchecked -->
<input type='checkbox' class='inputUncheck' name='foo' value='bar' checked=''/> 
<input type='checkbox' class='inputUncheck' name='foo' value='bar'/> 

+

$('input.inputUncheck').removeAttr('checked');

How to check if a Ruby object is a Boolean

I find this to be concise and self-documenting:

[true, false].include? foo

If using Rails or ActiveSupport, you can even do a direct query using in?

foo.in? [true, false]

Checking against all possible values isn't something I'd recommend for floats, but feasible when there are only two possible values!

Bootstrap full-width text-input within inline-form

Try something like below to achieve your desired result

input {
    max-width: 100%;
}

Programmatic equivalent of default(Type)

Equivalent to Dror's answer but as an extension method:

namespace System
{
    public static class TypeExtensions
    {
        public static object Default(this Type type)
        {
            object output = null;

            if (type.IsValueType)
            {
                output = Activator.CreateInstance(type);
            }

            return output;
        }
    }
}

How to convert DateTime to/from specific string format (both ways, e.g. given Format is "yyyyMMdd")?

If you want to have DATE as string with TIME as well. We can do like this:

    //Date and Time is taking as current system Date-Time    
    DateTime.Now.ToString("yyyyMMdd-HHmmss");

Convert NSArray to NSString in Objective-C

NSString * str = [componentsJoinedByString:@""];

and you have dic or multiple array then used bellow

NSString * result = [[array valueForKey:@"description"] componentsJoinedByString:@""];   

Append file contents to the bottom of existing file in Bash

This should work:

 cat "$API" >> "$CONFIG"

You need to use the >> operator to append to a file. Redirecting with > causes the file to be overwritten. (truncated).

Ignore fields from Java object dynamically while sending as JSON from Spring MVC

Add @JsonInclude(JsonInclude.Include.NON_NULL) (forces Jackson to serialize null values) to the class as well as @JsonIgnore to the password field.

You could of course set @JsonIgnore on createdBy and updatedBy as well if you always want to ignore then and not just in this specific case.

UPDATE

In the event that you do not want to add the annotation to the POJO itself, a great option is Jackson's Mixin Annotations. Check out the documentation

How to create a collapsing tree table in html/css/js?

SlickGrid has this functionality, see the tree demo.

If you want to build your own, here is an example (jsFiddle demo): Build your table with a data-depth attribute to indicate the depth of the item in the tree (the levelX CSS classes are just for styling indentation): 

<table id="mytable">
    <tr data-depth="0" class="collapse level0">
        <td><span class="toggle collapse"></span>Item 1</td>
        <td>123</td>
    </tr>
    <tr data-depth="1" class="collapse level1">
        <td><span class="toggle"></span>Item 2</td>
        <td>123</td>
    </tr>
</table>

Then when a toggle link is clicked, use Javascript to hide all <tr> elements until a <tr> of equal or less depth is found (excluding those already collapsed):

$(function() {
    $('#mytable').on('click', '.toggle', function () {
        //Gets all <tr>'s  of greater depth below element in the table
        var findChildren = function (tr) {
            var depth = tr.data('depth');
            return tr.nextUntil($('tr').filter(function () {
                return $(this).data('depth') <= depth;
            }));
        };

        var el = $(this);
        var tr = el.closest('tr'); //Get <tr> parent of toggle button
        var children = findChildren(tr);

        //Remove already collapsed nodes from children so that we don't
        //make them visible. 
        //(Confused? Remove this code and close Item 2, close Item 1 
        //then open Item 1 again, then you will understand)
        var subnodes = children.filter('.expand');
        subnodes.each(function () {
            var subnode = $(this);
            var subnodeChildren = findChildren(subnode);
            children = children.not(subnodeChildren);
        });

        //Change icon and hide/show children
        if (tr.hasClass('collapse')) {
            tr.removeClass('collapse').addClass('expand');
            children.hide();
        } else {
            tr.removeClass('expand').addClass('collapse');
            children.show();
        }
        return children;
    });
});

Server unable to read htaccess file, denying access to be safe

As for Apache running on Ubuntu, the solution was to check error log, which showed that the error was related with folder and file permission.

First, check Apache error log

nano /var/log/apache2/error.log

Then set folder permission to be executable

sudo chmod 755 /var/www/html/

Also set file permission to be readable

sudo chmod 644 /var/www/html/.htaccess

Read and Write CSV files including unicode with Python 2.7

I couldn't respond to Mark above, but I just made one modification which fixed the error which was caused if data in the cells was not unicode, i.e. float or int data. I replaced this line into the UnicodeWriter function: "self.writer.writerow([s.encode("utf-8") if type(s)==types.UnicodeType else s for s in row])" so that it became:

class UnicodeWriter:
    def __init__(self, f, dialect=csv.excel, encoding="utf-8-sig", **kwds):
       self.queue = cStringIO.StringIO()
        self.writer = csv.writer(self.queue, dialect=dialect, **kwds)
        self.stream = f
        self.encoder = codecs.getincrementalencoder(encoding)()
    def writerow(self, row):
        '''writerow(unicode) -> None
        This function takes a Unicode string and encodes it to the output.
        '''
        self.writer.writerow([s.encode("utf-8") if type(s)==types.UnicodeType else s for s in row])
        data = self.queue.getvalue()
        data = data.decode("utf-8")
        data = self.encoder.encode(data)
        self.stream.write(data)
        self.queue.truncate(0)

    def writerows(self, rows):
        for row in rows:
            self.writerow(row)

You will also need to "import types".

Scheduling Python Script to run every hour accurately

The Python standard library does provide sched and threading for this task. But this means your scheduler script will have be running all the time instead of leaving its execution to the OS, which may or may not be what you want.

Adding files to java classpath at runtime

yes, you can. it will need to be in its package structure in a separate directory from the rest of your compiled code if you want to isolate it. you will then just put its base dir in the front of the classpath on the command line.

How to delete a module in Android Studio

To delete a module in Android Studio 2.3.3,

  • Open File -> Project Structure
  • On Project Structure window, list of modules of the current project gets displayed on left panel. Select the module which needs to be deleted.
  • Then click - button on top left, that means just above left panel.

ExpressJS How to structure an application?

OK, it's been a while and this is a popular question, so I've gone ahead and created a scaffolding github repository with JavaScript code and a long README about how I like to structure a medium-sized express.js application.

focusaurus/express_code_structure is the repo with the latest code for this. Pull requests welcome.

Here's a snapshot of the README since stackoverflow doesn't like just-a-link answers. I'll make some updates as this is a new project that I'll continue updating, but ultimately the github repo will be the up-to-date place for this information.


Express Code Structure

This project is an example of how to organize a medium-sized express.js web application.

Current to at least express v4.14 December 2016

Build Status

js-standard-style

How big is your application?

Web applications are not all the same, and there's not, in my opinion, a single code structure that should be applied to all express.js applications.

If your application is small, you don't need such a deep directory structure as exemplified here. Just keep it simple and stick a handful of .js files in the root of your repository and you're done. Voilà.

If your application is huge, at some point you need to break it up into distinct npm packages. In general the node.js approach seems to favor many small packages, at least for libraries, and you should build your application up by using several npm packages as that starts to make sense and justify the overhead. So as your application grows and some portion of the code becomes clearly reusable outside of your application or is a clear subsystem, move it to it's own git repository and make it into a standalone npm package.

So the focus of this project is to illustrate a workable structure for a medium-sized application.

What is your overall architecture

There are many approaches to building a web application, such as

  • Server Side MVC a la Ruby on Rails
  • Single Page Application style a la MongoDB/Express/Angular/Node (MEAN)
  • Basic web site with some forms
  • Models/Operations/Views/Events style a la MVC is dead, it's time to MOVE on
  • and many others both current and historical

Each of these fits nicely into a different directory structure. For the purposes of this example, it's just scaffolding and not a fully working app, but I'm assuming the following key architecture points:

  • The site has some traditional static pages/templates
  • The "application" portion of the site is developed as a Single Page Application style
  • The application exposes a REST/JSON style API to the browser
  • The app models a simple business domain, in this case, it's a car dealership application

And what about Ruby on Rails?

It will be a theme throughout this project that many of the ideas embodied in Ruby on Rails and the "Convention over Configuration" decisions they have adopted, though widely accepted and used, are not actually very helpful and sometimes are the opposite of what this repository recommends.

My main point here is that there are underlying principles to organizing code, and based on those principles, the Ruby on Rails conventions make sense (mostly) for the Ruby on Rails community. However, just thoughtlessly aping those conventions misses the point. Once you grok the basic principles, ALL of your projects will be well-organized and clear: shell scripts, games, mobile apps, enterprise projects, even your home directory.

For the Rails community, they want to be able to have a single Rails developer switch from app to app to app and be familiar and comfortable with it each time. This makes great sense if you are 37 signals or Pivotal Labs, and has benefits. In the server-side JavaScript world, the overall ethos is just way more wild west anything goes and we don't really have a problem with that. That's how we roll. We're used to it. Even within express.js, it's a close kin of Sinatra, not Rails, and taking conventions from Rails is usually not helping anything. I'd even say Principles over Convention over Configuration.

Underlying Principles and Motivations

  • Be mentally manageable
    • The brain can only deal with and think about a small number of related things at once. That's why we use directories. It helps us deal with complexity by focusing on small portions.
  • Be size-appropriate
    • Don't create "Mansion Directories" where there's just 1 file all alone 3 directories down. You can see this happening in the Ansible Best Practices that shames small projects into creating 10+ directories to hold 10+ files when 1 directory with 3 files would be much more appropriate. You don't drive a bus to work (unless you're a bus driver, but even then your driving a bus AT work not TO work), so don't create filesystem structures that aren't justified by the actual files inside them.
  • Be modular but pragmatic
    • The node community overall favors small modules. Anything that can cleanly be separated out from your app entirely should be extracted into a module either for internal use or publicly published on npm. However, for the medium-sized applications that are the scope here, the overhead of this can add tedium to your workflow without commensurate value. So for the time when you have some code that is factored out but not enough to justify a completely separate npm module, just consider it a "proto-module" with the expectation that when it crosses some size threshold, it would be extracted out.
    • Some folks such as @hij1nx even include an app/node_modules directory and have package.json files in the proto-module directories to facilitate that transition and act as a reminder.
  • Be easy to locate code
    • Given a feature to build or a bug to fix, our goal is that a developer has no struggle locating the source files involved.
    • Names are meaningful and accurate
    • crufty code is fully removed, not left around in an orphan file or just commented out
  • Be search-friendly
    • all first-party source code is in the app directory so you can cd there are run find/grep/xargs/ag/ack/etc and not be distracted by third party matches
  • Use simple and obvious naming
    • npm now seems to require all-lowercase package names. I find this mostly terrible but I must follow the herd, thus filenames should use kebab-case even though the variable name for that in JavaScript must be camelCase because - is a minus sign in JavaScript.
    • variable name matches the basename of the module path, but with kebab-case transformed to camelCase
  • Group by Coupling, Not by Function
    • This is a major departure from the Ruby on Rails convention of app/views, app/controllers, app/models, etc
    • Features get added to a full stack, so I want to focus on a full stack of files that are relevant to my feature. When I'm adding a telephone number field to the user model, I don't care about any controller other than the user controller, and I don't care about any model other than the user model.
    • So instead of editing 6 files that are each in their own directory and ignoring tons of other files in those directories, this repository is organized such that all the files I need to build a feature are colocated
    • By the nature of MVC, the user view is coupled to the user controller which is coupled to the user model. So when I change the user model, those 3 files will often change together, but the deals controller or customer controller are decoupled and thus not involved. Same applies to non-MVC designs usually as well.
    • MVC or MOVE style decoupling in terms of which code goes in which module is still encouraged, but spreading the MVC files out into sibling directories is just annoying.
    • Thus each of my routes files has the portion of the routes it owns. A rails-style routes.rb file is handy if you want an overview of all routes in the app, but when actually building features and fixing bugs, you only care about the routes relevant to the piece you are changing.
  • Store tests next to the code
    • This is just an instance of "group by coupling", but I wanted to call it out specifically. I've written many projects where the tests live under a parallel filesystem called "tests" and now that I've started putting my tests in the same directory as their corresponding code, I'm never going back. This is more modular and much easier to work with in text editors and alleviates a lot of the "../../.." path nonsense. If you are in doubt, try it on a few projects and decide for yourself. I'm not going to do anything beyond this to convince you that it's better.
  • Reduce cross-cutting coupling with Events
    • It's easy to think "OK, whenever a new Deal is created, I want to send an email to all the Salespeople", and then just put the code to send those emails in the route that creates deals.
    • However, this coupling will eventually turn your app into a giant ball of mud.
    • Instead, the DealModel should just fire a "create" event and be entirely unaware of what else the system might do in response to that.
    • When you code this way, it becomes much more possible to put all the user related code into app/users because there's not a rat's nest of coupled business logic all over the place polluting the purity of the user code base.
  • Code flow is followable
    • Don't do magic things. Don't autoload files from magic directories in the filesystem. Don't be Rails. The app starts at app/server.js:1 and you can see everything it loads and executes by following the code.
    • Don't make DSLs for your routes. Don't do silly metaprogramming when it is not called for.
    • If your app is so big that doing magicRESTRouter.route(somecontroller, {except: 'POST'}) is a big win for you over 3 basic app.get, app.put, app.del, calls, you're probably building a monolithic app that is too big to effectively work on. Get fancy for BIG wins, not for converting 3 simple lines to 1 complex line.
  • Use lower-kebab-case filenames

    • This format avoids filesystem case sensitivity issues across platforms
    • npm forbids uppercase in new package names, and this works well with that

      express.js specifics

  • Don't use app.configure. It's almost entirely useless and you just don't need it. It is in lots of boilerplate due to mindless copypasta.

  • THE ORDER OF MIDDLEWARE AND ROUTES IN EXPRESS MATTERS!!!
    • Almost every routing problem I see on stackoverflow is out-of-order express middleware
    • In general, you want your routes decoupled and not relying on order that much
    • Don't use app.use for your entire application if you really only need that middleware for 2 routes (I'm looking at you, body-parser)
    • Make sure when all is said and done you have EXACTLY this order:
      1. Any super-important application-wide middleware
      2. All your routes and assorted route middlewares
      3. THEN error handlers
  • Sadly, being sinatra-inspired, express.js mostly assumes all your routes will be in server.js and it will be clear how they are ordered. For a medium-sized application, breaking things out into separate routes modules is nice, but it does introduce peril of out-of-order middleware

The app symlink trick

There are many approaches outlined and discussed at length by the community in the great gist Better local require() paths for Node.js. I may soon decide to prefer either "just deal with lots of ../../../.." or use the requireFrom modlue. However, at the moment, I've been using the symlink trick detailed below.

So one way to avoid intra-project requires with annoying relative paths like require("../../../config") is to use the following trick:

  • create a symlink under node_modules for your app
    • cd node_modules && ln -nsf ../app
  • add just the node_modules/app symlink itself, not the entire node_modules folder, to git
    • git add -f node_modules/app
    • Yes, you should still have "node_modules" in your .gitignore file
    • No, you should not put "node_modules" into your git repository. Some people will recommend you do this. They are incorrect.
  • Now you can require intra-project modules using this prefix
    • var config = require("app/config");
    • var DealModel = require("app/deals/deal-model");
  • Basically, this makes intra-project requires work very similarly to requires for external npm modules.
  • Sorry, Windows users, you need to stick with parent directory relative paths.

Configuration

Generally code modules and classes to expect only a basic JavaScript options object passed in. Only app/server.js should load the app/config.js module. From there it can synthesize small options objects to configure subsystems as needed, but coupling every subsystem to a big global config module full of extra information is bad coupling.

Try to centralize creation of DB connections and pass those into subsystems as opposed to passing connection parameters and having subsystems make outgoing connections themselves.

NODE_ENV

This is another enticing but terrible idea carried over from Rails. There should be exactly 1 place in your app, app/config.js that looks at the NODE_ENV environment variable. Everything else should take an explicit option as a class constructor argument or module configuration parameter.

If the email module has an option as to how to deliver emails (SMTP, log to stdout, put in queue etc), it should take an option like {deliver: 'stdout'} but it should absolutely not check NODE_ENV.

Tests

I now keep my test files in the same directory as their corresponding code and use filename extension naming conventions to distinguish tests from production code.

  • foo.js has the module "foo"'s code
  • foo.tape.js has the node-based tests for foo and lives in the same dir
  • foo.btape.js can be used for tests that need to execute in a browser environment

I use filesystem globs and the find . -name '*.tape.js' command to get access to all my tests as necessary.

How to organize code within each .js module file

This project's scope is mostly about where files and directories go, and I don't want to add much other scope, but I'll just mention that I organize my code into 3 distinct sections.

  1. Opening block of CommonJS require calls to state dependencies
  2. Main code block of pure-JavaScript. No CommonJS pollution in here. Don't reference exports, module, or require.
  3. Closing block of CommonJS to set up exports

Java ArrayList of Arrays?

Should be

private ArrayList<String[]> action = new ArrayList<String[]>();
action.add(new String[2]);
...

You can't specify the size of the array within the generic parameter, only add arrays of specific size to the list later. This also means that the compiler can't guarantee that all sub-arrays be of the same size, it must be ensured by you.

A better solution might be to encapsulate this within a class, where you can ensure the uniform size of the arrays as a type invariant.

What's wrong with foreign keys?

This is an issue of upbringing. If somewhere in your educational or professional career you spent time feeding and caring for databases (or worked closely with talented folks who did), then the fundamental tenets of entities and relationships are well-ingrained in your thought process. Among those rudiments is how/when/why to specify keys in your database (primary, foreign and perhaps alternate). It's second nature.

If, however, you've not had such a thorough or positive experience in your past with RDBMS-related endeavors, then you've likely not been exposed to such information. Or perhaps your past includes immersion in an environment that was vociferously anti-database (e.g., "those DBAs are idiots - we few, we chosen few java/c# code slingers will save the day"), in which case you might be vehemently opposed to the arcane babblings of some dweeb telling you that FKs (and the constraints they can imply) really are important if you'd just listen.

Most everyone was taught when they were kids that brushing your teeth was important. Can you get by without it? Sure, but somewhere down the line you'll have less teeth available than you could have if you had brushed after every meal. If moms and dads were responsible enough to cover database design as well as oral hygiene, we wouldn't be having this conversation. :-)

What is the difference between HTTP_HOST and SERVER_NAME in PHP?

Assuming one has a simple setup (CentOS 7, Apache 2.4.x, and PHP 5.6.20) and only one website (not assuming virtual hosting) ...

In the PHP sense, $_SERVER['SERVER_NAME'] is an element PHP registers in the $_SERVER superglobal based on your Apache configuration (**ServerName** directive with UseCanonicalName On ) in httpd.conf (be it from an included virtual host configuration file, whatever, etc ...). HTTP_HOST is derived from the HTTP host header. Treat this as user input. Filter and validate before using.

Here is an example of where I use $_SERVER['SERVER_NAME'] as the basis for a comparison. The following method is from a concrete child class I made named ServerValidator (child of Validator). ServerValidator checks six or seven elements in $_SERVER before using them.

In determining if the HTTP request is POST, I use this method.

public function isPOST()
{
    return (($this->requestMethod === 'POST')    &&  // Ignore
            $this->hasTokenTimeLeft()            &&  // Ignore
            $this->hasSameGETandPOSTIdentities() &&  // Ingore
            ($this->httpHost === filter_input(INPUT_SERVER, 'SERVER_NAME')));
}

By the time this method is called, all filtering and validating of relevant $_SERVER elements would have occurred (and relevant properties set).

The line ...

($this->httpHost === filter_input(INPUT_SERVER, 'SERVER_NAME')

... checks that the $_SERVER['HTTP_HOST'] value (ultimately derived from the requested host HTTP header) matches $_SERVER['SERVER_NAME'].

Now, I am using superglobal speak to explain my example, but that is just because some people are unfamiliar with INPUT_GET, INPUT_POST, and INPUT_SERVER in regards to filter_input_array().

The bottom line is, I do not handle POST requests on my server unless all four conditions are met. Hence, in terms of POST requests, failure to provide an HTTP host header (presence tested for earlier) spells doom for strict HTTP 1.0 browsers. Moreover, the requested host must match the value for ServerName in the httpd.conf, and, by extention, the value for $_SERVER('SERVER_NAME') in the $_SERVER superglobal. Again, I would be using INPUT_SERVER with the PHP filter functions, but you catch my drift.

Keep in mind that Apache frequently uses ServerName in standard redirects (such as leaving the trailing slash off a URL: Example, http://www.example.com becoming http://www.example.com/), even if you are not using URL rewriting.

I use $_SERVER['SERVER_NAME'] as the standard, not $_SERVER['HTTP_HOST']. There is a lot of back and forth on this issue. $_SERVER['HTTP_HOST'] could be empty, so this should not be the basis for creating code conventions such as my public method above. But, just because both may be set does not guarantee they will be equal. Testing is the best way to know for sure (bearing in mind Apache version and PHP version).

UnicodeDecodeError when reading CSV file in Pandas with Python

In my case, a file has USC-2 LE BOM encoding, according to Notepad++. It is encoding="utf_16_le" for python.

Hope, it helps to find an answer a bit faster for someone.

Add objects to an array of objects in Powershell

To append to an array, just use the += operator.

$Target += $TargetObject

Also, you need to declare $Target = @() before your loop because otherwise, it will empty the array every loop.

Bootstrap Carousel image doesn't align properly

In Bootstrap 4, you can add mx-auto class to your img tag.

For instance, if your image has a width of 75%, it should look like this:

<img class="d-block w-75 mx-auto" src="image.jpg" alt="First slide">

Bootstrap will automatically translate mx-auto to:

ml-auto, .mx-auto {
    margin-left: auto !important;
}

.mr-auto, .mx-auto {
    margin-right: auto !important;
}

java.io.StreamCorruptedException: invalid stream header: 7371007E

If you are sending multiple objects, it's often simplest to put them some kind of holder/collection like an Object[] or List. It saves you having to explicitly check for end of stream and takes care of transmitting explicitly how many objects are in the stream.

EDIT: Now that I formatted the code, I see you already have the messages in an array. Simply write the array to the object stream, and read the array on the server side.

Your "server read method" is only reading one object. If it is called multiple times, you will get an error since it is trying to open several object streams from the same input stream. This will not work, since all objects were written to the same object stream on the client side, so you have to mirror this arrangement on the server side. That is, use one object input stream and read multiple objects from that.

(The error you get is because the objectOutputStream writes a header, which is expected by objectIutputStream. As you are not writing multiple streams, but simply multiple objects, then the next objectInputStream created on the socket input fails to find a second header, and throws an exception.)

To fix it, create the objectInputStream when you accept the socket connection. Pass this objectInputStream to your server read method and read Object from that.

How to make/get a multi size .ico file?

What i do is to prepare a 512x512 PNG, the Alpha Channel is good for rounded corners or drop shadows, then I upload it to this site http://convertico.com/, and for free then it returns me a 6 sizes .ico file with 256x256, 128x128, 64x64, 48x48, 32x32 and 16x16 sizes.

How do I select last 5 rows in a table without sorting?

Well, the "last five rows" are actually the last five rows depending on your clustered index. Your clustered index, by definition, is the way that he rows are ordered. So you really can't get the "last five rows" without some order. You can, however, get the last five rows as it pertains to the clustered index.

SELECT TOP 5 * FROM MyTable
ORDER BY MyCLusteredIndexColumn1, MyCLusteredIndexColumnq, ..., MyCLusteredIndexColumnN DESC

Webclient / HttpWebRequest with Basic Authentication returns 404 not found for valid URL

If its working when you are using a browser and then passing on your username and password for the first time - then this means that once authentication is done Request header of your browser is set with required authentication values, which is then passed on each time a request is made to hosting server.

So start with inspecting Request Header (this could be done using Web Developers tools), Once you established whats required in header then you could pass this within your HttpWebRequest Header.

Example with Digest Authentication:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;
using System.Text.RegularExpressions;
using System.Net;
using System.IO;

namespace NUI
{
    public class DigestAuthFixer
    {
        private static string _host;
        private static string _user;
        private static string _password;
        private static string _realm;
        private static string _nonce;
        private static string _qop;
        private static string _cnonce;
        private static DateTime _cnonceDate;
        private static int _nc;

public DigestAuthFixer(string host, string user, string password)
{
    // TODO: Complete member initialization
    _host = host;
    _user = user;
    _password = password;
}

private string CalculateMd5Hash(
    string input)
{
    var inputBytes = Encoding.ASCII.GetBytes(input);
    var hash = MD5.Create().ComputeHash(inputBytes);
    var sb = new StringBuilder();
    foreach (var b in hash)
        sb.Append(b.ToString("x2"));
    return sb.ToString();
}

private string GrabHeaderVar(
    string varName,
    string header)
{
    var regHeader = new Regex(string.Format(@"{0}=""([^""]*)""", varName));
    var matchHeader = regHeader.Match(header);
    if (matchHeader.Success)
        return matchHeader.Groups[1].Value;
    throw new ApplicationException(string.Format("Header {0} not found", varName));
}

private string GetDigestHeader(
    string dir)
{
    _nc = _nc + 1;

    var ha1 = CalculateMd5Hash(string.Format("{0}:{1}:{2}", _user, _realm, _password));
    var ha2 = CalculateMd5Hash(string.Format("{0}:{1}", "GET", dir));
    var digestResponse =
        CalculateMd5Hash(string.Format("{0}:{1}:{2:00000000}:{3}:{4}:{5}", ha1, _nonce, _nc, _cnonce, _qop, ha2));

    return string.Format("Digest username=\"{0}\", realm=\"{1}\", nonce=\"{2}\", uri=\"{3}\", " +
        "algorithm=MD5, response=\"{4}\", qop={5}, nc={6:00000000}, cnonce=\"{7}\"",
        _user, _realm, _nonce, dir, digestResponse, _qop, _nc, _cnonce);
}

public string GrabResponse(
    string dir)
{
    var url = _host + dir;
    var uri = new Uri(url);

    var request = (HttpWebRequest)WebRequest.Create(uri);

    // If we've got a recent Auth header, re-use it!
    if (!string.IsNullOrEmpty(_cnonce) &&
        DateTime.Now.Subtract(_cnonceDate).TotalHours < 1.0)
    {
        request.Headers.Add("Authorization", GetDigestHeader(dir));
    }

    HttpWebResponse response;
    try
    {
        response = (HttpWebResponse)request.GetResponse();
    }
    catch (WebException ex)
    {
        // Try to fix a 401 exception by adding a Authorization header
        if (ex.Response == null || ((HttpWebResponse)ex.Response).StatusCode != HttpStatusCode.Unauthorized)
            throw;

        var wwwAuthenticateHeader = ex.Response.Headers["WWW-Authenticate"];
        _realm = GrabHeaderVar("realm", wwwAuthenticateHeader);
        _nonce = GrabHeaderVar("nonce", wwwAuthenticateHeader);
        _qop = GrabHeaderVar("qop", wwwAuthenticateHeader);

        _nc = 0;
        _cnonce = new Random().Next(123400, 9999999).ToString();
        _cnonceDate = DateTime.Now;

        var request2 = (HttpWebRequest)WebRequest.Create(uri);
        request2.Headers.Add("Authorization", GetDigestHeader(dir));
        response = (HttpWebResponse)request2.GetResponse();
    }
    var reader = new StreamReader(response.GetResponseStream());
    return reader.ReadToEnd();
}

}

Then you could call it:

DigestAuthFixer digest = new DigestAuthFixer(domain, username, password);
string strReturn = digest.GrabResponse(dir);

if Url is: http://xyz.rss.com/folder/rss then domain: http://xyz.rss.com (domain part) dir: /folder/rss (rest of the url)

you could also return it as stream and use XmlDocument Load() method.

How to create a simple checkbox in iOS?

On iOS there is the switch UI component instead of a checkbox, look into the UISwitch class. The property on (boolean) can be used to determine the state of the slider and about the saving of its state: That depends on how you save your other stuff already, its just saving a boolean value.

Object passed as parameter to another class, by value or reference?

"Objects" are NEVER passed in C# -- "objects" are not values in the language. The only types in the language are primitive types, struct types, etc. and reference types. No "object types".

The types Object, MyClass, etc. are reference types. Their values are "references" -- pointers to objects. Objects can only be manipulated through references -- when you do new on them, you get a reference, the . operator operates on a reference; etc. There is no way to get a variable whose value "is" an object, because there are no object types.

All types, including reference types, can be passed by value or by reference. A parameter is passed by reference if it has a keyword like ref or out. The SetObject method's obj parameter (which is of a reference type) does not have such a keyword, so it is passed by value -- the reference is passed by value.

Styling HTML5 input type number

I have been looking for the same solution and this worked for me...add an inline css tag to control the width of the input.

For example:

<input type="number" min="1" max="5" style="width: 2em;">

Combined with the min and max attributes you can control the width of the input.

Hide Text with CSS, Best Practice?

As of September of 2015, the most common practice is to use the following CSS:

.sr-only{
    clip: rect(1px, 1px, 1px, 1px);
    height: 1px;
    overflow: hidden;
    position: absolute !important;
    width: 1px;
}

Solving Quadratic Equation

<code>
import cmath
import math
print(" we are going to programming second grade equation in python")
print(" a^2 x + b x + c =0")

num1 = int(input(" enter A please : "))
num2 = int(input(" enter B please : "))
num3 = int(input(" enter c please : "))
v = num2*num2 - 4 *num1 * num3
print(v)
if v < 0 :
    print("wrong values")
else:
    print("root of delta =", v)
    k= math.sqrt(v)

def two_sol(x,y) :
    x_f= (-y + v)/(4*x)
    x_s =(-y - v)/(4*x)
    return x_f , x_s

def one_sol(x):
    x_f = (-y + v) / (4 * x)

if v >0 :
    print("we have two solution :" ,two_sol(num1,num2)) 
elif v == 0:
    print( "we have one solution :" , one_sol(y)) 
else:
    print(" there is no solution !!")
</code>

Generating random numbers with Swift

Another option is to use the xorshift128plus algorithm:

func xorshift128plus(seed0 : UInt64, _ seed1 : UInt64) -> () -> UInt64 {
    var state0 : UInt64 = seed0
    var state1 : UInt64 = seed1
    if state0 == 0 && state1 == 0 {
        state0 = 1 // both state variables cannot be 0
    }

    func rand() -> UInt64 {
        var s1 : UInt64 = state0
        let s0 : UInt64 = state1
        state0 = s0
        s1 ^= s1 << 23
        s1 ^= s1 >> 17
        s1 ^= s0
        s1 ^= s0 >> 26
        state1 = s1
        return UInt64.addWithOverflow(state0, state1).0
    }

    return rand
}

This algorithm has a period of 2^128 - 1 and passes all the tests of the BigCrush test suite. Note that while this is a high-quality pseudo-random number generator with a long period, it is not a cryptographically secure random number generator.

You could seed it from the current time or any other random source of entropy. For example, if you had a function called urand64() that read a UInt64 from /dev/urandom, you could use it like this:

let rand = xorshift128plus(urand64(), urand64())
for _ in 1...10 {
    print(rand())
}

Bootstrap: Position of dropdown menu relative to navbar item

If you want to display the menu up, just add the class "dropup"
and remove the class "dropdown" if exists from the same div.

<div class="btn-group dropup">

enter image description here

Counting the number of occurences of characters in a string

if this is a real program and not a study project, then look at using the Apache Commons StringUtils class - particularly the countMatches method.

If it is a study project then keep at it and learn from your exploring :)

how to access the command line for xampp on windows

In case some one wants to know how to set up Environment variables

  1. Click on the windows button on the bottom left and go to System
  2. Click the Advanced System Settings link in the left column
  3. In the System Properties window, click on the Advanced tab, then click the Environment Variables button near the bottom of that tab.
  4. In the Environment Variables window , highlight the Path variable in the "System variables" section and click the Edit button. Add the path lines with the paths you want the computer to access.

Once you have done that you can run using the command from the start->command line as below

php <path to file location>

How do I implement basic "Long Polling"?

I used this to get to grips with Comet, I have also set up Comet using the Java Glassfish server and found lots of other examples by subscribing to cometdaily.com

Mocking python function based on input arguments

As indicated at Python Mock object with method called multiple times

A solution is to write my own side_effect

def my_side_effect(*args, **kwargs):
    if args[0] == 42:
        return "Called with 42"
    elif args[0] == 43:
        return "Called with 43"
    elif kwargs['foo'] == 7:
        return "Foo is seven"

mockobj.mockmethod.side_effect = my_side_effect

That does the trick

php & mysql query not echoing in html with tags?

I can spot a few different problems with this. However, in the interest of time, try this chunk of code instead:

<?php require 'db.php'; ?>  <?php if (isset($_POST['search'])) {     $limit = $_POST['limit'];     $country = $_POST['country'];     $state = $_POST['state'];     $city = $_POST['city'];     $data = mysqli_query(         $link,         "SELECT * FROM proxies WHERE country = '{$country}' AND state = '{$state}' AND city = '{$city}' LIMIT {$limit}"     );     while ($assoc = mysqli_fetch_assoc($data)) {         $proxy = $assoc['proxy'];         ?>             <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"                 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">             <html xmlns="http://www.w3.org/1999/xhtml">                 <head>                     <title>Sock5Proxies</title>                     <meta http-equiv="Content-Type" content="text/html;charset=utf-8" />                     <link href="./style.css" rel="stylesheet" type="text/css" />                     <link href="./buttons.css" rel="stylesheet" type="text/css" />                 </head>                 <body>                     <center>                         <h1>Sock5Proxies</h1>                     </center>                     <div id="wrapper">                         <div id="header">                             <ul id="nav">                                 <li class="active"><a href="index.html"><span></span>Home</a></li>                                 <li><a href="leads.html"><span></span>Leads</a></li>                                 <li><a href="payout.php"><span></span>Pay out</a></li>                                 <li><a href="contact.html"><span></span>Contact</a></li>                                 <li><a href="logout.php"><span></span>Logout</a></li>                             </ul>                         </div>                         <div id="content">                             <div id="center">                                 <table cellpadding="0" cellspacing="0" style="width:690px">                                     <thead>                                     <tr>                                         <th width="75" class="first">Proxy</th>                                         <th width="50" class="last">Status</th>                                     </tr>                                     </thead>                                     <tbody>                                     <tr class="rowB">                                         <td class="first"> <?php echo $proxy ?> </td>                                         <td class="last">Check</td>                                     </tr>                                     </tbody>                                 </table>                             </div>                         </div>                         <div id="footer"></div>                         <span id="about">Version 1.0</span>                     </div>                 </body>             </html>         <?php     } } ?> <html> <form action="" method="POST">     <input type="text" name="limit" placeholder="10" /><br>     <input type="text" name="country" placeholder="Country" /><br>     <input type="text" name="state" placeholder="State" /><br>     <input type="text" name="city" placeholder="City" /><br>     <input type="submit" name="search" value="Search" /><br> </form> </html> 

Better way to remove specific characters from a Perl string

Well if you're using the randomly-generated string so that it has a low probability of being matched by some intentional string that you might normally find in the data, then you probably want one string per file.

You take that string, call it $place_older say. And then when you want to eliminate the text, you call quotemeta, and you use that value to substitute:

my $subs = quotemeta $place_holder;
s/$subs//g;

Use a LIKE statement on SQL Server XML Datatype

Yet another option is to cast the XML as nvarchar, and then search for the given string as if the XML vas a nvarchar field.

SELECT * 
FROM Table
WHERE CAST(Column as nvarchar(max)) LIKE '%TEST%'

I love this solution as it is clean, easy to remember, hard to mess up, and can be used as a part of a where clause.

EDIT: As Cliff mentions it, you could use:

...nvarchar if there's characters that don't convert to varchar

How to give environmental variable path for file appender in configuration file in log4j

Log4j entry

#- File to log to and log format

log4j.appender.file.File=${LOG_PATH}/mylogfile.log

Java program
String log4jConfPath        = "path/log4j.properties";
File log4jFile              = new File(log4jConfPath);
if (log4jFile.exists()) {
    System.setProperty("LOG_PATH", "c:/temp/");
    PropertyConfigurator.configure(log4jFile.getAbsolutePath());
    logger.trace("test123");
}

Convert UTF-8 with BOM to UTF-8 with no BOM in Python

In Python 3 it's quite easy: read the file and rewrite it with utf-8 encoding:

s = open(bom_file, mode='r', encoding='utf-8-sig').read()
open(bom_file, mode='w', encoding='utf-8').write(s)

Sending XML data using HTTP POST with PHP

you can use cURL library for posting data: http://www.php.net/curl

$ch = curl_init();
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch, CURLOPT_URL, "http://websiteURL");
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, "XML=".$xmlcontent."&password=".$password."&etc=etc");
$content=curl_exec($ch);

where postfield contains XML you need to send - you will need to name the postfield the API service (Clickatell I guess) expects

Python: fastest way to create a list of n lists

The list comprehensions actually are implemented more efficiently than explicit looping (see the dis output for example functions) and the map way has to invoke an ophaque callable object on every iteration, which incurs considerable overhead overhead.

Regardless, [[] for _dummy in xrange(n)] is the right way to do it and none of the tiny (if existent at all) speed differences between various other ways should matter. Unless of course you spend most of your time doing this - but in that case, you should work on your algorithms instead. How often do you create these lists?

How to enter quotes in a Java string?

This tiny java method will help you produce standard CSV text of a specific column.

public static String getStandardizedCsv(String columnText){

    //contains line feed ?
    boolean containsLineFeed = false;
    if(columnText.contains("\n")){
        containsLineFeed = true;
    }

    boolean containsCommas = false;
    if(columnText.contains(",")){
        containsCommas = true;
    }

    boolean containsDoubleQuotes = false;
    if(columnText.contains("\"")){
        containsDoubleQuotes = true;
    }

    columnText.replaceAll("\"", "\"\"");

    if(containsLineFeed || containsCommas || containsDoubleQuotes){
        columnText = "\"" + columnText + "\"";
    }

    return columnText;
}

multiple ways of calling parent method in php

Unless I am misunderstanding the question, I would almost always use $this->get_species because the subclass (in this case dog) could overwrite that method since it does extend it. If the class dog doesn't redefine the method then both ways are functionally equivalent but if at some point in the future you decide you want the get_species method in dog should print "dog" then you would have to go back through all the code and change it.

When you use $this it is actually part of the object which you created and so will always be the most up-to-date as well (if the property being used has changed somehow in the lifetime of the object) whereas using the parent class is calling the static class method.

how to draw directed graphs using networkx in python?

import networkx as nx
import matplotlib.pyplot as plt

G = nx.DiGraph()
G.add_node("A")
G.add_node("B")
G.add_node("C")
G.add_node("D")
G.add_node("E")
G.add_node("F")
G.add_node("G")
G.add_edge("A","B")
G.add_edge("B","C")
G.add_edge("C","E")
G.add_edge("C","F")
G.add_edge("D","E")
G.add_edge("F","G")

print(G.nodes())
print(G.edges())

pos = nx.spring_layout(G)

nx.draw_networkx_nodes(G, pos)
nx.draw_networkx_labels(G, pos)
nx.draw_networkx_edges(G, pos, edge_color='r', arrows = True)

plt.show()

Windows 7, 64 bit, DLL problems

I just resolved the same problem with C++ Qt 5 and Windows 7 64 bits with MSCVC 2012.

In the beginning I thought it was a MSVC/Windows DLL file problem, but as BorisP said, the problem was in my project dependencies. The key is "How to know your project dependencies in Qt 5?".

As I didn't find any clear way to know it (Dependency Walker didn't help me a lot...), I followed next the "inverse procedure" that takes no more than 5 minutes and avoid a lot of headaches with DLL file dependencies:

  1. Compile your project and take the executable file to an empty folder: myproject.exe
  2. Try to execute it, It will retrieve an error (missing DLL files...).
  3. Now, copy all the DLL files from Qt (in my case they were in C:\Qt\Qt5.1.1\5.1.1\msvc2012_64_opengl\bin) to this folder.
  4. Try to execute again, it will probably works fine.
  5. Start to delete progressively and try every time your executable still works, trying to leave the minimum necessary DLL files.

When you have all the DLL files in the same folder it is easier to find which of them are not valid (XML, WebKit, ... whatever..), and consequently this method doesn't take more than five minutes.

How to use lifecycle method getDerivedStateFromProps as opposed to componentWillReceiveProps

As mentioned by Dan Abramov

Do it right inside render

We actually use that approach with memoise one for any kind of proxying props to state calculations.

Our code looks this way

// ./decorators/memoized.js  
import memoizeOne from 'memoize-one';

export function memoized(target, key, descriptor) {
  descriptor.value = memoizeOne(descriptor.value);
  return descriptor;
}

// ./components/exampleComponent.js
import React from 'react';
import { memoized } from 'src/decorators';

class ExampleComponent extends React.Component {
  buildValuesFromProps() {
    const {
      watchedProp1,
      watchedProp2,
      watchedProp3,
      watchedProp4,
      watchedProp5,
    } = this.props
    return {
      value1: buildValue1(watchedProp1, watchedProp2),
      value2: buildValue2(watchedProp1, watchedProp3, watchedProp5),
      value3: buildValue3(watchedProp3, watchedProp4, watchedProp5),
    }
  }

  @memoized
  buildValue1(watchedProp1, watchedProp2) {
    return ...;
  }

  @memoized
  buildValue2(watchedProp1, watchedProp3, watchedProp5) {
    return ...;
  }

  @memoized
  buildValue3(watchedProp3, watchedProp4, watchedProp5) {
    return ...;
  }

  render() {
    const {
      value1,
      value2,
      value3
    } = this.buildValuesFromProps();

    return (
      <div>
        <Component1 value={value1}>
        <Component2 value={value2}>
        <Component3 value={value3}>
      </div>
    );
  }
}

The benefits of it are that you don't need to code tons of comparison boilerplate inside getDerivedStateFromProps or componentWillReceiveProps and you can skip copy-paste initialization inside a constructor.

NOTE:

This approach is used only for proxying the props to state, in case you have some inner state logic it still needs to be handled in component lifecycles.

How to add System.Windows.Interactivity to project?

I have had the exact same problem with a solution, that System.Windows.Interactivity was required for one of the project in Visual Studio 2019, and I tried to install Blend for Visual Studio SDK for .NET from Visual Studio 2019 Individual components, but it did not exist in it.

The consequence of that, I was not able to build the project in my solution with repetitive of following similar error on different XAML parts of the project:

The tag 'Interaction.Behaviors' does not exist in XML namespace 'clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity'.

Image with all errors The above mentioned errors snapshot example

The solution, the way I solved it, is by installing Microsoft Expression Blend Software Development Kit (SDK) for .NET 4 from Microsoft.

Thanks to my colleague @felza, mentioned that System.Windows.Interactivity requires this sdk, that is suppose to be located in this folder:

C:\Program Files (x86)\Microsoft SDKs\Expression\Blend\.NETFramework\v4.0

In my case it was not installed. I have had this folder C:\Program Files (x86)\Microsoft SDKs with out Expression\Blend\.NETFramework\v4.0 folder inside it.

After installing it, all errors disappeared.

How can I apply styles to multiple classes at once?

You can have multiple CSS declarations for the same properties by separating them with commas:

.abc, .xyz {
   margin-left: 20px;
}

What is the correct way of reading from a TCP socket in C/C++?

If you actually create the buffer as per dirks suggestion, then:

  int readResult = read(socketFileDescriptor, buffer, BUFFER_SIZE);

may completely fill the buffer, possibly overwriting the terminating zero character which you depend on when extracting to a stringstream. You need:

  int readResult = read(socketFileDescriptor, buffer, BUFFER_SIZE - 1 );

C++ Returning reference to local variable

A good thing to remember are these simple rules, and they apply to both parameters and return types...

  • Value - makes a copy of the item in question.
  • Pointer - refers to the address of the item in question.
  • Reference - is literally the item in question.

There is a time and place for each, so make sure you get to know them. Local variables, as you've shown here, are just that, limited to the time they are locally alive in the function scope. In your example having a return type of int* and returning &i would have been equally incorrect. You would be better off in that case doing this...

void func1(int& oValue)
{
    oValue = 1;
}

Doing so would directly change the value of your passed in parameter. Whereas this code...

void func1(int oValue)
{
    oValue = 1;
}

would not. It would just change the value of oValue local to the function call. The reason for this is because you'd actually be changing just a "local" copy of oValue, and not oValue itself.

IF... OR IF... in a windows batch file

The zmbq solution is good, but cannot be used in all situations, such as inside a block of code like a FOR DO(...) loop.

An alternative is to use an indicator variable. Initialize it to be undefined, and then define it only if any one of the OR conditions is true. Then use IF DEFINED as a final test - no need to use delayed expansion.

FOR ..... DO (
  set "TRUE="
  IF cond1 set TRUE=1
  IF cond2 set TRUE=1
  IF defined TRUE (
    ...
  ) else (
    ...
  )
)

You could add the ELSE IF logic that arasmussen uses on the grounds that it might perform a wee bit faster if the 1st condition is true, but I never bother.

Addendum - This is a duplicate question with nearly identical answers to Using an OR in an IF statement WinXP Batch Script

Final addendum - I almost forgot my favorite technique to test if a variable is any one of a list of case insensitive values. Initialize a test variable containing a delimitted list of acceptable values, and then use search and replace to test if your variable is within the list. This is very fast and uses minimal code for an arbitrarily long list. It does require delayed expansion (or else the CALL %%VAR%% trick). Also the test is CASE INSENSITIVE.

set "TEST=;val1;val2;val3;val4;val5;"
if "!TEST:;%VAR%;=!" neq "!TEST!" (echo true) else (echo false)

The above can fail if VAR contains =, so the test is not fool-proof.

If doing the test within a block where delayed expansion is needed to access current value of VAR then

for ... do (
  set "TEST=;val1;val2;val3;val4;val5;"
  for /f %%A in (";!VAR!;") do if "!TEST:%%A=!" neq "!TEST!" (echo true) else (echo false)
)

FOR options like "delims=" might be needed depending on expected values within VAR

The above strategy can be made reliable even with = in VAR by adding a bit more code.

set "TEST=;val1;val2;val3;val4;val5;"
if "!TEST:;%VAR%;=!" neq "!TEST!" if "!TEST:;%VAR%;=;%VAR%;"=="!TEST!" echo true

But now we have lost the ability of providing an ELSE clause unless we add an indicator variable. The code has begun to look a bit "ugly", but I think it is the best performing reliable method for testing if VAR is any one of an arbitrary number of case-insensitive options.

Finally there is a simpler version that I think is slightly slower because it must perform one IF for each value. Aacini provided this solution in a comment to the accepted answer in the before mentioned link

for %%A in ("val1" "val2" "val3" "val4" "val5") do if "%VAR%"==%%A echo true

The list of values cannot include the * or ? characters, and the values and %VAR% should not contain quotes. Quotes lead to problems if the %VAR% also contains spaces or special characters like ^, & etc. One other limitation with this solution is it does not provide the option for an ELSE clause unless you add an indicator variable. Advantages are it can be case sensitive or insensitive depending on presence or absence of IF /I option.

Resource interpreted as stylesheet but transferred with MIME type text/html (seems not related with web server)

I was facing similar issue. And Exploring solutions in this fantastic Stack Overflow page.

user54861 's response (mismatching names in case sensetivity) makes me curious to inspect my code again and realized that "I didnt upload two js files that I loaded them in head tag". :-)

When I uploaded them the issue runs away ! And code runs and page rendered without any another error!

So, moral of the story is don't forget to make sure that all of your js files are uploaded where the page is looking for them.

Flash CS4 refuses to let go

I have found one related behaviour that may help (sounds like your specific problem runs deeper though):

Flash checks whether a source file needs recompiling by looking at timestamps. If its compiled version is older than the source file, it will recompile. But it doesn't check whether the compiled version was generated from the same source file or not.

Specifically, if you have your actionscript files under version control, and you Revert a change, the reverted file will usually have an older timestamp, and Flash will ignore it.

AngularJS: how to enable $locationProvider.html5Mode with deeplinking

This was the best solution I found after more time than I care to admit. Basically, add target="_self" to each link that you need to insure a page reload.

http://blog.panjiesw.com/posts/2013/09/angularjs-normal-links-with-html5mode/

XPath selecting a node with some attribute value equals to some other node's attribute value

I think this is what you want:

/grand/parent/child[@id="#grand"]

Failed to build gem native extension — Rails install

mkmf is part of the ruby1.9.1-dev package. This package contains the header files needed for extension libraries for Ruby 1.9.1. You need to install the ruby1.9.1-dev package by doing:

sudo apt-get install ruby1.9.1-dev

Then you can install Rails as per normal.

Generally it's easier to just do:

sudo apt-get install ruby-dev

How to get all keys with their values in redis

There is no native way of doing this.

The Redis command documentation contains no native commands for getting the key and value of multiple keys.

The most native way of doing this would be to load a lua script into your redis using the SCRIPT LOAD command or the EVAL command.

Bash Haxx solution

A workaround would be to use some bash magic, like this:

echo 'keys YOURKEY*' | redis-cli | sed 's/^/get /' | redis-cli 

This will output the data from all the keys which begin with YOURKEY

Note that the keys command is a blocking operation and should be used with care.

Importing JSON into an Eclipse project

Download json from java2s website then include in your project. In your class add these package java_basic;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Iterator;

import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;

How to use JQuery with ReactJS

You should try and avoid jQuery in ReactJS. But if you really want to use it, you'd put it in componentDidMount() lifecycle function of the component.

e.g.

class App extends React.Component {
  componentDidMount() {
    // Jquery here $(...)...
  }

  // ...
}

Ideally, you'd want to create a reusable Accordion component. For this you could use Jquery, or just use plain javascript + CSS.

class Accordion extends React.Component {
  constructor() {
    super();
    this._handleClick = this._handleClick.bind(this);
  }

  componentDidMount() {
    this._handleClick();
  }

  _handleClick() {
    const acc = this._acc.children;
    for (let i = 0; i < acc.length; i++) {
      let a = acc[i];
      a.onclick = () => a.classList.toggle("active");
    }
  }

  render() {
    return (
      <div 
        ref={a => this._acc = a} 
        onClick={this._handleClick}>
        {this.props.children}
      </div>
    )
  }
}

Then you can use it in any component like so:

class App extends React.Component {
  render() {
    return (
      <div>
        <Accordion>
          <div className="accor">
            <div className="head">Head 1</div>
            <div className="body"></div>
          </div>
        </Accordion>
      </div>
    );
  }
}

Codepen link here: https://codepen.io/jzmmm/pen/JKLwEA?editors=0110 (I changed this link to https ^)

Getting a list item by index

You can use the ElementAt extension method on the list.

For example:

// Get the first item from the list

using System.Linq;

var myList = new List<string>{ "Yes", "No", "Maybe"};
var firstItem = myList.ElementAt(0);

// Do something with firstItem

C++11 reverse range-based for-loop

If you can use range v3 , you can use the reverse range adapter ranges::view::reverse which allows you to view the container in reverse.

A minimal working example:

#include <iostream>
#include <vector>
#include <range/v3/view.hpp>

int main()
{
    std::vector<int> intVec = {1, 2, 3, 4, 5, 6, 7, 8, 9};

    for (auto const& e : ranges::view::reverse(intVec)) {
        std::cout << e << " ";   
    }
    std::cout << std::endl;

    for (auto const& e : intVec) {
        std::cout << e << " ";   
    }
    std::cout << std::endl;
}

See DEMO 1.

Note: As per Eric Niebler, this feature will be available in C++20. This can be used with the <experimental/ranges/range> header. Then the for statement will look like this:

for (auto const& e : view::reverse(intVec)) {
       std::cout << e << " ";   
}

See DEMO 2

How to determine the first and last iteration in a foreach loop?

foreach ($arquivos as $key => $item) {
   reset($arquivos);
   // FIRST AHEAD
   if ($key === key($arquivos) || $key !== end(array_keys($arquivos)))
       $pdf->cat(null, null, $key);

   // LAST
   if ($key === end(array_keys($arquivos))) {
       $pdf->cat(null, null, $key)
           ->execute();
   }
}

Android ImageView Fixing Image Size

Fix ImageView's size with dp or fill_parent and set android:scaleType to fitXY.

How to specify jackson to only use fields - preferably globally

You can configure individual ObjectMappers like this:

ObjectMapper mapper  = new ObjectMapper();
mapper.setVisibility(mapper.getSerializationConfig().getDefaultVisibilityChecker()
                .withFieldVisibility(JsonAutoDetect.Visibility.ANY)
                .withGetterVisibility(JsonAutoDetect.Visibility.NONE)
                .withSetterVisibility(JsonAutoDetect.Visibility.NONE)
                .withCreatorVisibility(JsonAutoDetect.Visibility.NONE));

If you want it set globally, I usually access a configured mapper through a wrapper class.

Why my $.ajax showing "preflight is invalid redirect error"?

My problem was caused by the exact opposite of @ehacinom. My Laravel generated API didn't like the trailing '/' on POST requests. Worked fine on localhost but didn't work when uploaded to server.

Google MAP API Uncaught TypeError: Cannot read property 'offsetWidth' of null

Year, geocodezip's answer is correct. So change your code like this: (if you still in trouble, or maybe somebody else in the future)

<script type="text/javascript">

function initialize() {
    var latlng = new google.maps.LatLng(-34.397, 150.644);
    var myOptions = {
        zoom: 8,
        center: latlng,
        mapTypeId: google.maps.MapTypeId.ROADMAP
    };
    var map = new google.maps.Map(document.getElementById("map_canvas"),
            myOptions);
}
google.maps.event.addDomListener(window, "load", initialize);

</script>

Should I use the datetime or timestamp data type in MySQL?

The main difference is that DATETIME is constant while TIMESTAMP is affected by the time_zone setting.

So it only matters when you have — or may in the future have — synchronized clusters across time zones.

In simpler words: If I have a database in Australia, and take a dump of that database to synchronize/populate a database in America, then the TIMESTAMP would update to reflect the real time of the event in the new time zone, while DATETIME would still reflect the time of the event in the au time zone.

A great example of DATETIME being used where TIMESTAMP should have been used is in Facebook, where their servers are never quite sure what time stuff happened across time zones. Once I was having a conversation in which the time said I was replying to messages before the message was actually sent. (This, of course, could also have been caused by bad time zone translation in the messaging software if the times were being posted rather than synchronized.)

Fatal error: Call to undefined function mysqli_connect()

On Ubuntu I had to install php5 mysql extension:

apt-get install php5-mysql

How to check if a String is numeric in Java

I have illustrated some conditions to check numbers and decimals without using any API,

Check Fix Length 1 digit number

Character.isDigit(char)

Check Fix Length number (Assume length is 6)

String number = "132452";
if(number.matches("([0-9]{6})"))
System.out.println("6 digits number identified");

Check Varying Length number between (Assume 4 to 6 length)

//  {n,m}  n <= length <= m
String number = "132452";
if(number.matches("([0-9]{4,6})"))
System.out.println("Number Identified between 4 to 6 length");

String number = "132";
if(!number.matches("([0-9]{4,6})"))
System.out.println("Number not in length range or different format");

Check Varying Length decimal number between (Assume 4 to 7 length)

//  It will not count the '.' (Period) in length
String decimal = "132.45";
if(decimal.matches("(-?[0-9]+(\.)?[0-9]*){4,6}"))
System.out.println("Numbers Identified between 4 to 7");

String decimal = "1.12";
if(decimal.matches("(-?[0-9]+(\.)?[0-9]*){4,6}"))
System.out.println("Numbers Identified between 4 to 7");

String decimal = "1234";
if(decimal.matches("(-?[0-9]+(\.)?[0-9]*){4,6}"))
System.out.println("Numbers Identified between 4 to 7");

String decimal = "-10.123";
if(decimal.matches("(-?[0-9]+(\.)?[0-9]*){4,6}"))
System.out.println("Numbers Identified between 4 to 7");

String decimal = "123..4";
if(!decimal.matches("(-?[0-9]+(\.)?[0-9]*){4,6}"))
System.out.println("Decimal not in range or different format");

String decimal = "132";
if(!decimal.matches("(-?[0-9]+(\.)?[0-9]*){4,6}"))
System.out.println("Decimal not in range or different format");

String decimal = "1.1";
if(!decimal.matches("(-?[0-9]+(\.)?[0-9]*){4,6}"))
System.out.println("Decimal not in range or different format");

Hope it will help manyone.

Beginner Python: AttributeError: 'list' object has no attribute

Consider:

class Bike(object):
    def __init__(self, name, weight, cost):
        self.name = name
        self.weight = weight
        self.cost = cost

bikes = {
    # Bike designed for children"
    "Trike": Bike("Trike", 20, 100),      # <--
    # Bike designed for everyone"
    "Kruzer": Bike("Kruzer", 50, 165),    # <--
    }

# Markup of 20% on all sales
margin = .2
# Revenue minus cost after sale
for bike in bikes.values():
    profit = bike.cost * margin
    print(profit)

Output:

33.0
20.0

The difference is that in your bikes dictionary, you're initializing the values as lists [...]. Instead, it looks like the rest of your code wants Bike instances. So create Bike instances: Bike(...).

As for your error

AttributeError: 'list' object has no attribute 'cost'

this will occur when you try to call .cost on a list object. Pretty straightforward, but we can figure out what happened by looking at where you call .cost -- in this line:

profit = bike.cost * margin

This indicates that at least one bike (that is, a member of bikes.values() is a list). If you look at where you defined bikes you can see that the values were, in fact, lists. So this error makes sense.

But since your class has a cost attribute, it looked like you were trying to use Bike instances as values, so I made that little change:

[...] -> Bike(...)

and you're all set.

How to run a subprocess with Python, wait for it to exit and get the full stdout as a string?

subprocess.check_output(...)

calls the process, raises if its error code is nonzero, and otherwise returns its stdout. It's just a quick shorthand so you don't have to worry about PIPEs and things.

How do you pass a function as a parameter in C?

Since C++11 you can use the functional library to do this in a succinct and generic fashion. The syntax is, e.g.,

std::function<bool (int)>

where bool is the return type here of a one-argument function whose first argument is of type int.

I have included an example program below:

// g++ test.cpp --std=c++11
#include <functional>

double Combiner(double a, double b, std::function<double (double,double)> func){
  return func(a,b);
}

double Add(double a, double b){
  return a+b;
}

double Mult(double a, double b){
  return a*b;
}

int main(){
  Combiner(12,13,Add);
  Combiner(12,13,Mult);
}

Sometimes, though, it is more convenient to use a template function:

// g++ test.cpp --std=c++11

template<class T>
double Combiner(double a, double b, T func){
  return func(a,b);
}

double Add(double a, double b){
  return a+b;
}

double Mult(double a, double b){
  return a*b;
}

int main(){
  Combiner(12,13,Add);
  Combiner(12,13,Mult);
}

How to format x-axis time scale values in Chart.js v2

as per the Chart js documentation page tick configuration section. you can format the value of each tick using the callback function. for example I wanted to change locale of displayed dates to be always German. in the ticks parts of the axis options

ticks: {
    callback: function(value) { 
        return new Date(value).toLocaleDateString('de-DE', {month:'short', year:'numeric'}); 
    },
},

Apache is downloading php files instead of displaying them

If you have virtualmin try to comment out these lines in your apache configuration in /etc/apache2/sites-available

  #RemoveHandler .php
  #RemoveHandler .php7.0
  #php_admin_value engine Off

Convert a string to integer with decimal in Python

The expression int(float(s)) mentioned by others is the best if you want to truncate the value. If you want rounding, using int(round(float(s)) if the round algorithm matches what you want (see the round documentation), otherwise you should use Decimal and one if its rounding algorithms.

Datepicker: How to popup datepicker when click on edittext

My class for show DatePicker. I can use for EditText, TextView or Button

import android.app.DatePickerDialog;
import android.content.Context;
import android.view.View;
import android.widget.DatePicker;
import android.widget.TextView;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;

public class TextViewDatePicker
        implements View.OnClickListener, DatePickerDialog.OnDateSetListener {
    public static final String DATE_SERVER_PATTERN = "yyyy-MM-dd";
    private DatePickerDialog mDatePickerDialog;
    private TextView mView;
    private Context mContext;
    private long mMinDate;
    private long mMaxDate;

    public TextViewDatePicker(Context context, TextView view) {
        this(context, view, 0, 0);
    }

    public TextViewDatePicker(Context context, TextView view, long minDate, long maxDate) {
        mView = view;
        mView.setOnClickListener(this);
        mView.setFocusable(false);

        mContext = context;
        mMinDate = minDate;
        mMaxDate = maxDate;
    }

    @Override
    public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.YEAR, year);
        calendar.set(Calendar.MONTH, monthOfYear);
        calendar.set(Calendar.DAY_OF_MONTH, dayOfMonth);
        Date date = calendar.getTime();

        SimpleDateFormat formatter = new SimpleDateFormat(DATE_SERVER_PATTERN);
        mView.setText(formatter.format(date));
    }

    @Override
    public void onClick(View v) {
        Calendar calendar = Calendar.getInstance(TimeZone.getDefault());
        mDatePickerDialog = new DatePickerDialog(mContext, this, calendar.get(Calendar.YEAR),
                calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH));
        if (mMinDate != 0) {
            mDatePickerDialog.getDatePicker().setMinDate(mMinDate);
        }
        if (mMaxDate != 0) {
            mDatePickerDialog.getDatePicker().setMaxDate(mMaxDate);
        }
        mDatePickerDialog.show();
    }

    public DatePickerDialog getDatePickerDialog() {
        return mDatePickerDialog;
    }

    public void setMinDate(long minDate) {
        mMinDate = minDate;
    }

    public void setMaxDate(long maxDate) {
        mMaxDate = maxDate;
    }
}

Using

EditText myEditText = findViewById(R.id.myEditText);
TextViewDatePicker editTextDatePicker = new TextViewDatePicker(context, myEditText, minDate, maxDate);
//TextViewDatePicker editTextDatePicker = new TextViewDatePicker(context, myEditText); //without min date, max date

SQL Server Pivot Table with multiple column aggregates

I would do this slightly different by applying both the UNPIVOT and the PIVOT functions to get the final result. The unpivot takes the values from both the totalcount and totalamount columns and places them into one column with multiple rows. You can then pivot on those results.:

select chardate,
  Australia_totalcount as [Australia # of Transactions], 
  Australia_totalamount as [Australia Total $ Amount],
  Austria_totalcount as [Austria # of Transactions], 
  Austria_totalamount as [Austria Total $ Amount]
from
(
  select 
    numericmonth, 
    chardate,
    country +'_'+col col, 
    value
  from
  (
    select numericmonth, 
      country, 
      chardate,
      cast(totalcount as numeric(10, 2)) totalcount,
      cast(totalamount as numeric(10, 2)) totalamount
    from mytransactions
  ) src
  unpivot
  (
    value
    for col in (totalcount, totalamount)
  ) unpiv
) s
pivot
(
  sum(value)
  for col in (Australia_totalcount, Australia_totalamount,
              Austria_totalcount, Austria_totalamount)
) piv
order by numericmonth

See SQL Fiddle with Demo.

If you have an unknown number of country names, then you can use dynamic SQL:

DECLARE @cols AS NVARCHAR(MAX),
    @colsName AS NVARCHAR(MAX),
    @query  AS NVARCHAR(MAX)

select @cols = STUFF((SELECT distinct ',' + QUOTENAME(country +'_'+c.col) 
                      from mytransactions
                      cross apply 
                      (
                        select 'TotalCount' col
                        union all
                        select 'TotalAmount'
                      ) c
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

select @colsName 
    = STUFF((SELECT distinct ', ' + QUOTENAME(country +'_'+c.col) 
               +' as ['
               + country + case when c.col = 'TotalCount' then ' # of Transactions]' else 'Total $ Amount]' end
             from mytransactions
             cross apply 
             (
                select 'TotalCount' col
                union all
                select 'TotalAmount'
             ) c
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query 
  = 'SELECT chardate, ' + @colsName + ' 
     from 
     (
      select 
        numericmonth, 
        chardate,
        country +''_''+col col, 
        value
      from
      (
        select numericmonth, 
          country, 
          chardate,
          cast(totalcount as numeric(10, 2)) totalcount,
          cast(totalamount as numeric(10, 2)) totalamount
        from mytransactions
      ) src
      unpivot
      (
        value
        for col in (totalcount, totalamount)
      ) unpiv
     ) s
     pivot 
     (
       sum(value)
       for col in (' + @cols + ')
     ) p 
     order by numericmonth'

execute(@query)

See SQL Fiddle with Demo

Both give the result:

|             CHARDATE | AUSTRALIA # OF TRANSACTIONS | AUSTRALIA TOTAL $ AMOUNT | AUSTRIA # OF TRANSACTIONS | AUSTRIA TOTAL $ AMOUNT |
--------------------------------------------------------------------------------------------------------------------------------------
| Jul-12               |                          36 |                   699.96 |                        11 |                 257.82 |
| Aug-12               |                          44 |                  1368.71 |                         5 |                 126.55 |
| Sep-12               |                          52 |                  1161.33 |                         7 |                  92.11 |
| Oct-12               |                          50 |                  1099.84 |                        12 |                 103.56 |
| Nov-12               |                          38 |                  1078.94 |                        21 |                 377.68 |
| Dec-12               |                          63 |                  1668.23 |                         3 |                  14.35 |

How to use confirm using sweet alert?

I have been having this issue with SweetAlert2 as well. SA2 differs from 1 and puts everything inside the result object. The following above can be accomplished with the following code.

Swal.fire({
    title: 'A cool title',
    icon: 'info',
    confirmButtonText: 'Log in'
  }).then((result) => {
    if (result['isConfirmed']){
      // Put your function here
    }
  })

Everything placed inside the then result will run. Result holds a couple of parameters which can be used to do the trick. Pretty simple technique. Not sure if it works the same on SweetAlert1 but I really wouldn't know why you would choose that one above the newer version.

Method to find string inside of the text file. Then getting the following lines up to a certain limit

Here is the code of TextScanner

public class TextScanner {

        private static void readFile(String fileName) {
            try {
              File file = new File("/opt/pol/data22/ds_data118/0001/0025090290/2014/12/12/0029057983.ds");
              Scanner scanner = new Scanner(file);
              while (scanner.hasNext()) {
                System.out.println(scanner.next());
              }
              scanner.close();
            } catch (FileNotFoundException e) {
              e.printStackTrace();
            }
          }

          public static void main(String[] args) {
            if (args.length != 1) {
              System.err.println("usage: java TextScanner1"
                + "file location");
              System.exit(0);
            }
            readFile(args[0]);
      }
}

It will print text with delimeters

When to use reinterpret_cast?

One use of reinterpret_cast is if you want to apply bitwise operations to (IEEE 754) floats. One example of this was the Fast Inverse Square-Root trick:

https://en.wikipedia.org/wiki/Fast_inverse_square_root#Overview_of_the_code

It treats the binary representation of the float as an integer, shifts it right and subtracts it from a constant, thereby halving and negating the exponent. After converting back to a float, it's subjected to a Newton-Raphson iteration to make this approximation more exact:

float Q_rsqrt( float number )
{
    long i;
    float x2, y;
    const float threehalfs = 1.5F;

    x2 = number * 0.5F;
    y  = number;
    i  = * ( long * ) &y;                       // evil floating point bit level hacking
    i  = 0x5f3759df - ( i >> 1 );               // what the deuce? 
    y  = * ( float * ) &i;
    y  = y * ( threehalfs - ( x2 * y * y ) );   // 1st iteration
//  y  = y * ( threehalfs - ( x2 * y * y ) );   // 2nd iteration, this can be removed

    return y;
}

This was originally written in C, so uses C casts, but the analogous C++ cast is the reinterpret_cast.

Difference between timestamps with/without time zone in PostgreSQL

I try to explain it more understandably than the referred PostgreSQL documentation.

Neither TIMESTAMP variants store a time zone (or an offset), despite what the names suggest. The difference is in the interpretation of the stored data (and in the intended application), not in the storage format itself:

  • TIMESTAMP WITHOUT TIME ZONE stores local date-time (aka. wall calendar date and wall clock time). Its time zone is unspecified as far as PostgreSQL can tell (though your application may knows what it is). Hence, PostgreSQL does no time zone related conversion on input or output. If the value was entered into the database as '2011-07-01 06:30:30', then no mater in what time zone you display it later, it will still say year 2011, month 07, day 01, 06 hours, 30 minutes, and 30 seconds (in some format). Also, any offset or time zone you specify in the input is ignored by PostgreSQL, so '2011-07-01 06:30:30+00' and '2011-07-01 06:30:30+05' are the same as just '2011-07-01 06:30:30'. For Java developers: it's analogous to java.time.LocalDateTime.

  • TIMESTAMP WITH TIME ZONE stores a point on the UTC time line. How it looks (how many hours, minutes, etc.) depends on your time zone, but it always refers to the same "physical" instant (like the moment of an actual physical event). The input is internally converted to UTC, and that's how it's stored. For that, the offset of the input must be known, so when the input contains no explicit offset or time zone (like '2011-07-01 06:30:30') it's assumed to be in the current time zone of the PostgreSQL session, otherwise the explicitly specified offset or time zone is used (as in '2011-07-01 06:30:30+05'). The output is displayed converted to the current time zone of the PostgreSQL session. For Java developers: It's analogous to java.time.Instant (with lower resolution though), but with JDBC and JPA 2.2 you are supposed to map it to java.time.OffsetDateTime (or to java.util.Date or java.sql.Timestamp of course).

Some say that both TIMESTAMP variations store UTC date-time. Kind of, but it's confusing to put it that way in my opinion. TIMESTAMP WITHOUT TIME ZONE is stored like a TIMESTAMP WITH TIME ZONE, which rendered with UTC time zone happens to give the same year, month, day, hours, minutes, seconds, and microseconds as they are in the local date-time. But it's not meant to represent the point on the time line that the UTC interpretation says, it's just the way the local date-time fields are encoded. (It's some cluster of dots on the time line, as the real time zone is not UTC; we don't know what it is.)

How to enumerate an enum

This question appears in Chapter 10 of "C# Step by Step 2013"

The author uses a double for-loop to iterate through a pair of Enumerators (to create a full deck of cards):

class Pack
{
    public const int NumSuits = 4;
    public const int CardsPerSuit = 13;
    private PlayingCard[,] cardPack;

    public Pack()
    {
        this.cardPack = new PlayingCard[NumSuits, CardsPerSuit];
        for (Suit suit = Suit.Clubs; suit <= Suit.Spades; suit++)
        {
            for (Value value = Value.Two; value <= Value.Ace; value++)
            {
                cardPack[(int)suit, (int)value] = new PlayingCard(suit, value);
            }
        }
    }
}

In this case, Suit and Value are both enumerations:

enum Suit { Clubs, Diamonds, Hearts, Spades }
enum Value { Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King, Ace}

and PlayingCard is a card object with a defined Suit and Value:

class PlayingCard
{
    private readonly Suit suit;
    private readonly Value value;

    public PlayingCard(Suit s, Value v)
    {
        this.suit = s;
        this.value = v;
    }
}

How to generate random positive and negative numbers in Java

public static int generatRandomPositiveNegitiveValue(int max , int min) {
    //Random rand = new Random();
    int ii = -min + (int) (Math.random() * ((max - (-min)) + 1));
    return ii;
}

How do I create a constant in Python?

You can do it with collections.namedtuple and itertools:

import collections
import itertools
def Constants(Name, *Args, **Kwargs):
  t = collections.namedtuple(Name, itertools.chain(Args, Kwargs.keys()))
  return t(*itertools.chain(Args, Kwargs.values()))

>>> myConstants = Constants('MyConstants', 'One', 'Two', Three = 'Four')
>>> print myConstants.One
One
>>> print myConstants.Two
Two
>>> print myConstants.Three
Four
>>> myConstants.One = 'Two'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: can't set attribute

How to set host_key_checking=false in ansible inventory file?

I could not use:

ansible_ssh_common_args='-o StrictHostKeyChecking=no'

in inventory file. It seems ansible does not consider this option in my case (ansible 2.0.1.0 from pip in ubuntu 14.04)

I decided to use:

server ansible_host=192.168.1.1 ansible_ssh_common_args= '-o UserKnownHostsFile=/dev/null'

It helped me.

Also you could set this variable in group instead for each host:

[servers_group:vars]
ansible_ssh_common_args='-o UserKnownHostsFile=/dev/null'

How to close a JavaFX application on window close?

Using Java 8 this worked for me:

@Override
public void start(Stage stage) {
    Scene scene = new Scene(new Region());
    stage.setScene(scene);

    /* ... OTHER STUFF ... */

    stage.setOnCloseRequest(e -> {
        Platform.exit();
        System.exit(0);
    });
}

Paging UICollectionView by cells, not screen

You can use the following library: https://github.com/ink-spot/UPCarouselFlowLayout

It's very simple and ofc you do not need to think about details like other answers contain.

ffmpeg - Converting MOV files to MP4

The command to just stream it to a new container (mp4) needed by some applications like Adobe Premiere Pro without encoding (fast) is:

ffmpeg -i input.mov -qscale 0 output.mp4

Alternative as mentioned in the comments, which re-encodes with best quaility (-qscale 0):

ffmpeg -i input.mov -q:v 0 output.mp4

How to read data From *.CSV file using javascript?

Here's a JavaScript function that parses CSV data, accounting for commas found inside quotes.

// Parse a CSV row, accounting for commas inside quotes                   
function parse(row){
  var insideQuote = false,                                             
      entries = [],                                                    
      entry = [];
  row.split('').forEach(function (character) {                         
    if(character === '"') {
      insideQuote = !insideQuote;                                      
    } else {
      if(character == "," && !insideQuote) {                           
        entries.push(entry.join(''));                                  
        entry = [];                                                    
      } else {
        entry.push(character);                                         
      }                                                                
    }                                                                  
  });
  entries.push(entry.join(''));                                        
  return entries;                                                      
}

Example use of the function to parse a CSV file that looks like this:

"foo, the column",bar
2,3
"4, the value",5

into arrays:

// csv could contain the content read from a csv file
var csv = '"foo, the column",bar\n2,3\n"4, the value",5',

    // Split the input into lines
    lines = csv.split('\n'),

    // Extract column names from the first line
    columnNamesLine = lines[0],
    columnNames = parse(columnNamesLine),

    // Extract data from subsequent lines
    dataLines = lines.slice(1),
    data = dataLines.map(parse);

// Prints ["foo, the column","bar"]
console.log(JSON.stringify(columnNames));

// Prints [["2","3"],["4, the value","5"]]
console.log(JSON.stringify(data));

Here's how you can transform the data into objects, like D3's csv parser (which is a solid third party solution):

var dataObjects = data.map(function (arr) {
  var dataObject = {};
  columnNames.forEach(function(columnName, i){
    dataObject[columnName] = arr[i];
  });
  return dataObject;
});

// Prints [{"foo":"2","bar":"3"},{"foo":"4","bar":"5"}]
console.log(JSON.stringify(dataObjects));

Here's a working fiddle of this code.

Enjoy! --Curran

HTML Button Close Window

This site: http://www.computerhope.com/issues/ch000178.htm answers it with the script below

< input type="button" value="Close this window" onclick="self.close()">

How to disable back swipe gesture in UINavigationController on iOS 7

This works in viewDidLoad: for iOS 8:

  dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
      self.navigationController.interactivePopGestureRecognizer.enabled = false;
  });

Lots of the problems could be solved with help of the good ol' dispatch_after.

Though please note that this solution is potentially unsafe, please use your own reasoning.

Update

For iOS 8.1 delay time should be 0.5 seconds

On iOS 9.3 no delay needed anymore, it works just by placing this in your viewDidLoad:
(TBD if works on iOS 9.0-9.3)

navigationController?.interactivePopGestureRecognizer?.enabled = false

extract column value based on another column pandas dataframe

Use df[df['B']==3]['A'].values if you just want item itself without the brackets

Rmi connection refused with localhost

had a simliar problem with that connection exception. it is thrown either when the registry is not started yet (like in your case) or when the registry is already unexported (like in my case).

but a short comment to the difference between the 2 ways to start the registry:

Runtime.getRuntime().exec("rmiregistry 2020");

runs the rmiregistry.exe in javas bin-directory in a new process and continues parallel with your java code.

LocateRegistry.createRegistry(2020);

the rmi method call starts the registry, returns the reference to that registry remote object and then continues with the next statement.

in your case the registry is not started in time when you try to bind your object

How can I define an array of objects?

Array<T>

person: Array<{
  name: string;
  age: number;
}>

How can I generate a unique ID in Python?

You might want Python's UUID functions:

21.15. uuid — UUID objects according to RFC 4122

eg:

import uuid
print uuid.uuid4()

7d529dd4-548b-4258-aa8e-23e34dc8d43d

How do I use Maven through a proxy?

To set Maven Proxy :

Edit the proxies session in your ~/.m2/settings.xml file. If you cant find the file, create one.

<settings>
<proxies>
    <proxy>
        <id>httpproxy</id>
        <active>true</active>
        <protocol>http</protocol>
        <host>your-proxy-host</host>
        <port>your-proxy-port</port>
        <nonProxyHosts>local.net|some.host.com</nonProxyHosts>
    </proxy>
<proxy>
        <id>httpsproxy</id>
        <active>true</active>
        <protocol>https</protocol>
        <host>your-proxy-host</host>
        <port>your-proxy-port</port>
        <nonProxyHosts>local.net|some.host.com</nonProxyHosts>
    </proxy>

</proxies>
</settings>

or

Edit the proxies session in your {M2_HOME}/conf/settings.xml

Hope it Helps.. :)

In c# what does 'where T : class' mean?

That restricts T to reference types. You won't be able to put value types (structs and primitive types except string) there.

Fastest way to determine if an integer's square root is an integer

Don't know about fastest, but the simplest is to take the square root in the normal fashion, multiply the result by itself, and see if it matches your original value.

Since we're talking integers here, the fasted would probably involve a collection where you can just make a lookup.

Python Matplotlib figure title overlaps axes label when using twiny

ax.set_title('My Title\n', fontsize="15", color="red")
plt.imshow(myfile, origin="upper")

If you put '\n' right after your title string, the plot is drawn just below the title. That might be a fast solution too.

How to top, left justify text in a <td> cell that spans multiple rows

 <td rowspan="2" style="text-align:left;vertical-align:top;padding:0">Save a lot</td>

That should do it.

Take nth column in a text file

For the sake of completeness:

while read _ _ one _ two _; do
    echo "$one $two"
done < file.txt

Instead of _ an arbitrary variable (such as junk) can be used as well. The point is just to extract the columns.

Demo:

$ while read _ _ one _ two _; do echo "$one $two"; done < /tmp/file.txt
1657 19.6117
1410 18.8302
3078 18.6695
2434 14.0508
3129 13.5495

List of zeros in python

zlists = [[0] * i for i in range(10)]

zlists[0] is a list of 0 zeroes, zlists[1] is a list of 1 zero, zlists[2] is a list of 2 zeroes, etc.

How to get the timezone offset in GMT(Like GMT+7:00) from android device?

Here is a solution to get timezone offset in GMT+05:30 this format

public String getCurrentTimezoneOffset() {

    TimeZone tz = TimeZone.getDefault();  
    Calendar cal = GregorianCalendar.getInstance(tz);
    int offsetInMillis = tz.getOffset(cal.getTimeInMillis());

    String offset = String.format("%02d:%02d", Math.abs(offsetInMillis / 3600000), Math.abs((offsetInMillis / 60000) % 60));
    offset = "GMT"+(offsetInMillis >= 0 ? "+" : "-") + offset;

    return offset;
}