Programs & Examples On #Interval intersection

Log record changes in SQL server in an audit table

I know this is old, but maybe this will help someone else.

Do not log "new" values. Your existing table, GUESTS, has the new values. You'll have double entry of data, plus your DB size will grow way too fast that way.

I cleaned this up and minimized it for this example, but here is the tables you'd need for logging off changes:

CREATE TABLE GUESTS (
      GuestID INT IDENTITY(1,1) PRIMARY KEY, 
      GuestName VARCHAR(50), 
      ModifiedBy INT, 
      ModifiedOn DATETIME
)

CREATE TABLE GUESTS_LOG (
      GuestLogID INT IDENTITY(1,1) PRIMARY KEY, 
      GuestID INT, 
      GuestName VARCHAR(50), 
      ModifiedBy INT, 
      ModifiedOn DATETIME
)

When a value changes in the GUESTS table (ex: Guest name), simply log off that entire row of data, as-is, to your Log/Audit table using the Trigger. Your GUESTS table has current data, the Log/Audit table has the old data.

Then use a select statement to get data from both tables:

SELECT 0 AS 'GuestLogID', GuestID, GuestName, ModifiedBy, ModifiedOn FROM [GUESTS] WHERE GuestID = 1
UNION
SELECT GuestLogID, GuestID, GuestName, ModifiedBy, ModifiedOn FROM [GUESTS_LOG] WHERE GuestID = 1
ORDER BY ModifiedOn ASC

Your data will come out with what the table looked like, from Oldest to Newest, with the first row being what was created & the last row being the current data. You can see exactly what changed, who changed it, and when they changed it.

Optionally, I used to have a function that looped through the RecordSet (in Classic ASP), and only displayed what values had changed on the web page. It made for a GREAT audit trail so that users could see what had changed over time.

MSIE and addEventListener Problem in Javascript?

Internet Explorer (IE8 and lower) doesn't support addEventListener(...). It has its own event model using the attachEvent method. You could use some code like this:

var element = document.getElementById('container');
if (document.addEventListener){
    element .addEventListener('copy', beforeCopy, false); 
} else if (el.attachEvent){
    element .attachEvent('oncopy', beforeCopy);
}

Though I recommend avoiding writing your own event handling wrapper and instead use a JavaScript framework (such as jQuery, Dojo, MooTools, YUI, Prototype, etc) and avoid having to create the fix for this on your own.

By the way, the third argument in the W3C model of events has to do with the difference between bubbling and capturing events. In almost every situation you'll want to handle events as they bubble, not when they're captured. It is useful when using event delegation on things like "focus" events for text boxes, which don't bubble.

Presenting a UIAlertController properly on an iPad using iOS 8

In Swift 2, you want to do something like this to properly show it on iPhone and iPad:

func confirmAndDelete(sender: AnyObject) {
    guard let button = sender as? UIView else {
        return
    }

    let alert = UIAlertController(title: NSLocalizedString("Delete Contact?", comment: ""), message: NSLocalizedString("This action will delete all downloaded audio files.", comment: ""), preferredStyle: .ActionSheet)
    alert.modalPresentationStyle = .Popover

    let action = UIAlertAction(title: NSLocalizedString("Delete", comment: ""), style: .Destructive) { action in
        EarPlaySDK.deleteAllResources()
    }
    let cancel = UIAlertAction(title: NSLocalizedString("Cancel", comment: ""), style: .Cancel) { action in

    }
    alert.addAction(cancel)
    alert.addAction(action)

    if let presenter = alert.popoverPresentationController {
        presenter.sourceView = button
        presenter.sourceRect = button.bounds
    }
    presentViewController(alert, animated: true, completion: nil)
}

If you don't set the presenter, you will end up with an exception on iPad in -[UIPopoverPresentationController presentationTransitionWillBegin] with the following message:

Fatal Exception: NSGenericException Your application has presented a UIAlertController (<UIAlertController: 0x17858a00>) of style UIAlertControllerStyleActionSheet. The modalPresentationStyle of a UIAlertController with this style is UIModalPresentationPopover. You must provide location information for this popover through the alert controller's popoverPresentationController. You must provide either a sourceView and sourceRect or a barButtonItem. If this information is not known when you present the alert controller, you may provide it in the UIPopoverPresentationControllerDelegate method -prepareForPopoverPresentation.

Keras, how do I predict after I trained a model?

I trained a neural network in Keras to perform non linear regression on some data. This is some part of my code for testing on new data using previously saved model configuration and weights.

fname = r"C:\Users\tauseef\Desktop\keras\tutorials\BestWeights.hdf5"
modelConfig = joblib.load('modelConfig.pkl')
recreatedModel = Sequential.from_config(modelConfig)
recreatedModel.load_weights(fname)
unseenTestData = np.genfromtxt(r"C:\Users\tauseef\Desktop\keras\arrayOf100Rows257Columns.txt",delimiter=" ")
X_test = unseenTestData
standard_scalerX = StandardScaler()
standard_scalerX.fit(X_test)
X_test_std = standard_scalerX.transform(X_test)
X_test_std = X_test_std.astype('float32')
unseenData_predictions = recreatedModel.predict(X_test_std)

How to tar certain file types in all subdirectories?

If you're using bash version > 4.0, you can exploit shopt -s globstar to make short work of this:

shopt -s globstar; tar -czvf deploy.tar.gz **/Alice*.yml **/Bob*.json

this will add all .yml files that starts with Alice from any sub-directory and add all .json files that starts with Bob from any sub-directory.

Leading zeros for Int in Swift

Assuming you want a field length of 2 with leading zeros you'd do this:

import Foundation

for myInt in 1 ... 3 {
    print(String(format: "%02d", myInt))
}

output:

01
02
03

This requires import Foundation so technically it is not a part of the Swift language but a capability provided by the Foundation framework. Note that both import UIKit and import Cocoa include Foundation so it isn't necessary to import it again if you've already imported Cocoa or UIKit.


The format string can specify the format of multiple items. For instance, if you are trying to format 3 hours, 15 minutes and 7 seconds into 03:15:07 you could do it like this:

let hours = 3
let minutes = 15
let seconds = 7
print(String(format: "%02d:%02d:%02d", hours, minutes, seconds))

output:

03:15:07

How can I prevent the backspace key from navigating back?

This solution worked very well when tested.

I did add some code to handle some input fields not tagged with input, and to integrate in an Oracle PL/SQL application that generates an input form for my job.

My "two cents":

 if (typeof window.event != ''undefined'')
    document.onkeydown = function() {
    //////////// IE //////////////
    var src = event.srcElement;
    var tag = src.tagName.toUpperCase();
    if (event.srcElement.tagName.toUpperCase() != "INPUT"
        && event.srcElement.tagName.toUpperCase() != "TEXTAREA"
        || src.readOnly || src.disabled 
        )
        return (event.keyCode != 8);
    if(src.type) {
       var type = ("" + src.type).toUpperCase();
       return type != "CHECKBOX" && type != "RADIO" && type != "BUTTON";
       }
   }
else
   document.onkeypress = function(e) {
   //////////// FireFox 
   var src = e.target;
   var tag = src.tagName.toUpperCase();
   if ( src.nodeName.toUpperCase() != "INPUT" && tag != "TEXTAREA"
      || src.readOnly || src.disabled )
      return (e.keyCode != 8);
    if(src.type) {
      var type = ("" + src.type).toUpperCase();
      return type != "CHECKBOX" && type != "RADIO" && type != "BUTTON";
      }                              
   }

How can I clear the terminal in Visual Studio Code?

For a MacBook, it might not be Cmd + K...

There's a long discussion for cases where Cmd + K wouldn't work. In my case, I made a quick fix with

cmd+K +cmd+ K

Go to menu Preferences -> Key shortcuts -> Search ('clear'). Change it from a single K to a double K...

Does WhatsApp offer an open API?

  1. is the correct answer. WhatsApp is intentionally a closed system without an API for external access.

There were several projects available that reverse engineered the WhatsApp webservice interfaces. However, to my knowledge all of them are now discontinued/defunct due to legal action against them from WhatsApp.

For mobile phone applications there is a limited URL-Scheme-API available on IPhone and Android (Android-intent possible as well).

Disable cache for some images

I know this topic is old, but it ranks very well in Google. I found out that putting this in your header works well;

<meta Http-Equiv="Cache-Control" Content="no-cache">
<meta Http-Equiv="Pragma" Content="no-cache">
<meta Http-Equiv="Expires" Content="0">
<meta Http-Equiv="Pragma-directive: no-cache">
<meta Http-Equiv="Cache-directive: no-cache">

Where are SQL Server connection attempts logged?

Another way to check on connection attempts is to look at the server's event log. On my Windows 2008 R2 Enterprise machine I opened the server manager (right-click on Computer and select Manage. Then choose Diagnostics -> Event Viewer -> Windows Logs -> Applcation. You can filter the log to isolate the MSSQLSERVER events. I found a number that looked like this

Login failed for user 'bogus'. The user is not associated with a trusted SQL Server connection. [CLIENT: 10.12.3.126]

What is the difference between vmalloc and kmalloc?

What are the advantages of having a contiguous block of memory? Specifically, why would I need to have a contiguous physical block of memory in a system call? Is there any reason I couldn't just use vmalloc?

From Google's "I'm Feeling Lucky" on vmalloc:

kmalloc is the preferred way, as long as you don't need very big areas. The trouble is, if you want to do DMA from/to some hardware device, you'll need to use kmalloc, and you'll probably need bigger chunk. The solution is to allocate memory as soon as possible, before memory gets fragmented.

ASP.NET MVC Razor render without encoding

You can also use the WriteLiteral method

Recursive Fibonacci

This is my solution to fibonacci problem with recursion.

#include <iostream>
using namespace std;

int fibonacci(int n){
    if(n<=0)
        return 0;
    else if(n==1 || n==2)
        return 1;
    else
        return (fibonacci(n-1)+fibonacci(n-2));
}

int main() {
    cout << fibonacci(8);
    return 0;
}

How to disable submit button once it has been clicked?

If you disable the button, then its name=value pair will indeed not be sent as parameter. But the remnant of the parameters should be sent (as long as their respective input elements and the parent form are not disabled). Likely you're testing the button only or the other input fields or even the form are disabled?

What's the difference between Thread start() and Runnable run()

If you directly call run() method, you are not using multi-threading feature since run() method is executed as part of caller thread.

If you call start() method on Thread, the Java Virtual Machine will call run() method and two threads will run concurrently - Current Thread (main() in your example) and Other Thread (Runnable r1 in your example).

Have a look at source code of start() method in Thread class

 /**
     * Causes this thread to begin execution; the Java Virtual Machine
     * calls the <code>run</code> method of this thread.
     * <p>
     * The result is that two threads are running concurrently: the
     * current thread (which returns from the call to the
     * <code>start</code> method) and the other thread (which executes its
     * <code>run</code> method).
     * <p>
     * It is never legal to start a thread more than once.
     * In particular, a thread may not be restarted once it has completed
     * execution.
     *
     * @exception  IllegalThreadStateException  if the thread was already
     *               started.
     * @see        #run()
     * @see        #stop()
     */
    public synchronized void start() {
        /**
         * This method is not invoked for the main method thread or "system"
         * group threads created/set up by the VM. Any new functionality added
         * to this method in the future may have to also be added to the VM.
         *
         * A zero status value corresponds to state "NEW".
         */
        if (threadStatus != 0)
            throw new IllegalThreadStateException();
        group.add(this);
        start0();
        if (stopBeforeStart) {
            stop0(throwableFromStop);
        }
    }

    private native void start0();

In above code, you can't see invocation to run() method.

private native void start0() is responsible for calling run() method. JVM executes this native method.

What causes the Broken Pipe Error?

It can take time for the network close to be observed - the total time is nominally about 2 minutes (yes, minutes!) after a close before the packets destined for the port are all assumed to be dead. The error condition is detected at some point. With a small write, you are inside the MTU of the system, so the message is queued for sending. With a big write, you are bigger than the MTU and the system spots the problem quicker. If you ignore the SIGPIPE signal, then the functions will return EPIPE error on a broken pipe - at some point when the broken-ness of the connection is detected.

How do I tell matplotlib that I am done with a plot?

As stated from David Cournapeau, use figure().

import matplotlib
import matplotlib.pyplot as plt
import matplotlib.mlab as mlab

plt.figure()
x = [1,10]
y = [30, 1000]
plt.loglog(x, y, basex=10, basey=10, ls="-")
plt.savefig("first.ps")


plt.figure()
x = [10,100]
y = [10, 10000]
plt.loglog(x, y, basex=10, basey=10, ls="-")
plt.savefig("second.ps")

Or subplot(121) / subplot(122) for the same plot, different position.

import matplotlib
import matplotlib.pyplot as plt
import matplotlib.mlab as mlab

plt.subplot(121)
x = [1,10]
y = [30, 1000]
plt.loglog(x, y, basex=10, basey=10, ls="-")

plt.subplot(122)
x = [10,100]
y = [10, 10000]
plt.loglog(x, y, basex=10, basey=10, ls="-")
plt.savefig("second.ps")

How I could add dir to $PATH in Makefile?

By design make parser executes lines in a separate shell invocations, that's why changing variable (e.g. PATH) in one line, the change may not be applied for the next lines (see this post).

One way to workaround this problem, is to convert multiple commands into a single line (separated by ;), or use One Shell special target (.ONESHELL, as of GNU Make 3.82).

Alternatively you can provide PATH variable at the time when shell is invoked. For example:

PATH  := $(PATH):$(PWD)/bin:/my/other/path
SHELL := env PATH=$(PATH) /bin/bash

Setting action for back button in navigation controller

The solution I have found so far is not very nice, but it works for me. Taking this answer, I also check whether I'm popping programmatically or not:

- (void)viewWillDisappear:(BOOL)animated {
  [super viewWillDisappear:animated];

  if ((self.isMovingFromParentViewController || self.isBeingDismissed)
      && !self.isPoppingProgrammatically) {
    // Do your stuff here
  }
}

You have to add that property to your controller and set it to YES before popping programmatically:

self.isPoppingProgrammatically = YES;
[self.navigationController popViewControllerAnimated:YES];

Ansible: copy a directory content to another directory

The simplest solution I've found to copy the contents of a folder without copying the folder itself is to use the following:

- name: Move directory contents
  command: cp -r /<source_path>/. /<dest_path>/

This resolves @surfer190's follow-up question:

Hmmm what if you want to copy the entire contents? I noticed that * doesn't work – surfer190 Jul 23 '16 at 7:29

* is a shell glob, in that it relies on your shell to enumerate all the files within the folder before running cp, while the . directly instructs cp to get the directory contents (see https://askubuntu.com/questions/86822/how-can-i-copy-the-contents-of-a-folder-to-another-folder-in-a-different-directo)

How can I create a simple message box in Python?

Not the best, here is my basic Message box using only tkinter.

#Python 3.4
from    tkinter import  messagebox  as  msg;
import  tkinter as      tk;

def MsgBox(title, text, style):
    box = [
        msg.showinfo,       msg.showwarning,    msg.showerror,
        msg.askquestion,    msg.askyesno,       msg.askokcancel,        msg.askretrycancel,
];

tk.Tk().withdraw(); #Hide Main Window.

if style in range(7):
    return box[style](title, text);

if __name__ == '__main__':

Return = MsgBox(#Use Like This.
    'Basic Error Exemple',

    ''.join( [
        'The Basic Error Exemple a problem with test',                      '\n',
        'and is unable to continue. The application must close.',           '\n\n',
        'Error code Test',                                                  '\n',
        'Would you like visit http://wwww.basic-error-exemple.com/ for',    '\n',
        'help?',
    ] ),

    2,
);

print( Return );

"""
Style   |   Type        |   Button      |   Return
------------------------------------------------------
0           Info            Ok              'ok'
1           Warning         Ok              'ok'
2           Error           Ok              'ok'
3           Question        Yes/No          'yes'/'no'
4           YesNo           Yes/No          True/False
5           OkCancel        Ok/Cancel       True/False
6           RetryCancal     Retry/Cancel    True/False
"""

Ball to Ball Collision - Detection and Handling

A good way of reducing the number of collision checks is to split the screen into different sections. You then only compare each ball to the balls in the same section.

How to clear all data in a listBox?

If it is bound to a Datasource it will throw an error using ListBox1.Items.Clear();

In that case you will have to clear the Datasource instead. e.g., if it is filled with a Datatable:

  _dt.Clear();   //<-----Here's the Listbox emptied.
  _dt = _dbHelper.dtFillDataTable(_dt, strSQL);

  lbStyles.DataSource = _dt;
  lbStyles.DisplayMember = "YourDisplayMember";
  lbStyles.ValueMember = "YourValueMember";

Converting binary to decimal integer output

You can use int and set the base to 2 (for binary):

>>> binary = raw_input('enter a number: ')
enter a number: 11001
>>> int(binary, 2)
25
>>>

However, if you cannot use int like that, then you could always do this:

binary = raw_input('enter a number: ')
decimal = 0
for digit in binary:
    decimal = decimal*2 + int(digit)
print decimal

Below is a demonstration:

>>> binary = raw_input('enter a number: ')
enter a number: 11001
>>> decimal = 0
>>> for digit in binary:
...     decimal = decimal*2 + int(digit)
...
>>> print decimal
25
>>>

How do I pass command line arguments to a Node.js program?

Most of the people have given good answers. I would also like to contribute something here. I am providing the answer using lodash library to iterate through all command line arguments we pass while starting the app:

// Lodash library
const _ = require('lodash');

// Function that goes through each CommandLine Arguments and prints it to the console.
const runApp = () => {
    _.map(process.argv, (arg) => {
        console.log(arg);
    });
};

// Calling the function.
runApp();

To run above code just run following commands:

npm install
node index.js xyz abc 123 456

The result will be:

xyz 
abc 
123
456

Laravel - Eloquent or Fluent random row

You can use:

ModelName::inRandomOrder()->first();

Getting Date or Time only from a DateTime Object

You can use Instance.ToShortDateString() for the date,
and Instance.ToShortTimeString() for the time to get date and time from the same instance.

How do I parse a YAML file in Ruby?

Here is the one liner i use, from terminal, to test the content of yml file(s):

$ ruby  -r yaml -r pp  -e 'pp YAML.load_file("/Users/za/project/application.yml")'
{"logging"=>
  {"path"=>"/var/logs/",
   "file"=>"TacoCloud.log",
   "level"=>
    {"root"=>"WARN", "org"=>{"springframework"=>{"security"=>"DEBUG"}}}}}

error: request for member '..' in '..' which is of non-class type

Foo foo2();

change to

Foo foo2;

You get the error because compiler thinks of

Foo foo2()

as of function declaration with name 'foo2' and the return type 'Foo'.

But in that case If we change to Foo foo2 , the compiler might show the error " call of overloaded ‘Foo()’ is ambiguous".

Giving multiple conditions in for loop in Java

A basic for statement includes

  • 0..n initialization statements (ForInit)
  • 0..1 expression statements that evaluate to boolean or Boolean (ForStatement) and
  • 0..n update statements (ForUpdate)

If you need multiple conditions to build your ForStatement, then use the standard logic operators (&&, ||, |, ...) but - I suggest to use a private method if it gets to complicated:

for (int i = 0, j = 0; isMatrixElement(i,j,myArray); i++, j++) { 
   // ...
}

and

private boolean isMatrixElement(i,j,myArray) {
  return (i < myArray.length) && (j < myArray[i].length);  //  stupid dummy code!
}

How to get the CUDA version?

You could also use:

nvidia-smi | grep "CUDA Version:" 

To retrieve the explicit line.

How to split a string by spaces in a Windows batch file?

set a=AAA BBB CCC DDD EEE FFF
set a=%a:~6,1%

This code finds the 5th character in the string. If I wanted to find the 9th string, I would replace the 6 with 10 (add one).

Rails formatting date

Since I18n is the Rails core feature starting from version 2.2 you can use its localize-method. By applying the forementioned strftime %-variables you can specify the desired format under config/locales/en.yml (or whatever language), in your case like this:

time:
  formats:
    default: '%FT%T'

Or if you want to use this kind of format in a few specific places you can refer it as a variable like this

time:
  formats:
    specific_format: '%FT%T'

After that you can use it in your views like this:

l(Mode.last.created_at, format: :specific_format)  

What is a None value?

This is what the Python documentation has got to say about None:

The sole value of types.NoneType. None is frequently used to represent the absence of a value, as when default arguments are not passed to a function.

Changed in version 2.4: Assignments to None are illegal and raise a SyntaxError.

Note The names None and debug cannot be reassigned (assignments to them, even as an attribute name, raise SyntaxError), so they can be considered “true” constants.

  1. Let's confirm the type of None first

    print type(None)
    print None.__class__
    

    Output

    <type 'NoneType'>
    <type 'NoneType'>
    

Basically, NoneType is a data type just like int, float, etc. You can check out the list of default types available in Python in 8.15. types — Names for built-in types.

  1. And, None is an instance of NoneType class. So we might want to create instances of None ourselves. Let's try that

    print types.IntType()
    print types.NoneType()
    

    Output

    0
    TypeError: cannot create 'NoneType' instances
    

So clearly, cannot create NoneType instances. We don't have to worry about the uniqueness of the value None.

  1. Let's check how we have implemented None internally.

    print dir(None)
    

    Output

    ['__class__', '__delattr__', '__doc__', '__format__', '__getattribute__', 
     '__hash__', '__init__', '__new__', '__reduce__', '__reduce_ex__',
     '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__']
    

Except __setattr__, all others are read-only attributes. So, there is no way we can alter the attributes of None.

  1. Let's try and add new attributes to None

    setattr(types.NoneType, 'somefield', 'somevalue')
    setattr(None, 'somefield', 'somevalue')
    None.somefield = 'somevalue'
    

    Output

    TypeError: can't set attributes of built-in/extension type 'NoneType'
    AttributeError: 'NoneType' object has no attribute 'somefield'
    AttributeError: 'NoneType' object has no attribute 'somefield'
    

The above seen statements produce these error messages, respectively. It means that, we cannot create attributes dynamically on a None instance.

  1. Let us check what happens when we assign something None. As per the documentation, it should throw a SyntaxError. It means, if we assign something to None, the program will not be executed at all.

    None = 1
    

    Output

    SyntaxError: cannot assign to None
    

We have established that

  1. None is an instance of NoneType
  2. None cannot have new attributes
  3. Existing attributes of None cannot be changed.
  4. We cannot create other instances of NoneType
  5. We cannot even change the reference to None by assigning values to it.

So, as mentioned in the documentation, None can really be considered as a true constant.

Happy knowing None :)

How can I change the font-size of a select option?

Tell the option element to be 13pt

select option{
    font-size: 13pt;
}

and then the first option element to be 7pt

select option:first-child {
    font-size: 7pt;
}

Running demo: http://jsfiddle.net/VggvD/1/

The PowerShell -and conditional operator

Try like this:

if($user_sam -ne $NULL -and $user_case -ne $NULL)

Empty variables are $null and then different from "" ([string]::empty).

How to check if a variable is set in Bash?

While most of the techniques stated here are correct, bash 4.2 supports an actual test for the presence of a variable (man bash), rather than testing the value of the variable.

[[ -v foo ]]; echo $?
# 1

foo=bar
[[ -v foo ]]; echo $?
# 0

foo=""
[[ -v foo ]]; echo $?
# 0

Notably, this approach will not cause an error when used to check for an unset variable in set -u / set -o nounset mode, unlike many other approaches, such as using [ -z.

Freemarker iterating over hashmap keys

Iterating Objects

If your map keys is an object and not an string, you can iterate it using Freemarker.

1) Convert the map into a list in the controller:

List<Map.Entry<myObjectKey, myObjectValue>> convertedMap  = new ArrayList(originalMap.entrySet());

2) Iterate the map in the Freemarker template, accessing to the object in the Key and the Object in the Value:

<#list convertedMap as item>
    <#assign myObjectKey = item.getKey()/>
    <#assign myObjectValue = item.getValue()/>
    [...]
</#list>

How to filter by object property in angularJS

You can try this. its working for me 'name' is a property in arr.

repeat="item in (tagWordOptions | filter:{ name: $select.search } ) track by $index

How to produce a range with step n in bash? (generate a sequence of numbers with increments)

$ seq 4
1
2
3
4

$ seq 2 5
2
3
4
5

$ seq 4 2 12
4
6
8
10
12

$ seq -w 4 2 12
04
06
08
10
12

$ seq -s, 4 2 12
4,6,8,10,12

How to do the equivalent of pass by reference for primitives in Java

For a quick solution, you can use AtomicInteger or any of the atomic variables which will let you change the value inside the method using the inbuilt methods. Here is sample code:

import java.util.concurrent.atomic.AtomicInteger;


public class PrimitivePassByReferenceSample {

    /**
     * @param args
     */
    public static void main(String[] args) {

        AtomicInteger myNumber = new AtomicInteger(0);
        System.out.println("MyNumber before method Call:" + myNumber.get());
        PrimitivePassByReferenceSample temp = new PrimitivePassByReferenceSample() ;
        temp.changeMyNumber(myNumber);
        System.out.println("MyNumber After method Call:" + myNumber.get());


    }

     void changeMyNumber(AtomicInteger myNumber) {
        myNumber.getAndSet(100);

    }

}

Output:

MyNumber before method Call:0

MyNumber After method Call:100

How to apply a patch generated with git format-patch?

If you want to apply it as a commit, use git am.

"Active Directory Users and Computers" MMC snap-in for Windows 7?

As @CraigHyatt mentioned in one of the comments:

"Control Panel -> Programs and Features -> Turn Windows features on or off -> Remote Server Administration Tools -> AD DS and AD LDS Tools"

This worked like a charm in Windows Server 2008. A reboot was necessary, but the Active Directory Users and Computers snap in was available after that.

How to check if "Radiobutton" is checked?

        if(jRadioButton1.isSelected()){
            jTextField1.setText("Welcome");
        }
        else if(jRadioButton2.isSelected()){
            jTextField1.setText("Hello");
        }

Calculate number of hours between 2 dates in PHP

This function helps you to calculate exact years and months between two given dates, $doj1 and $doj. It returns example 4.3 means 4 years and 3 month.

<?php
    function cal_exp($doj1)
    {
        $doj1=strtotime($doj1);
        $doj=date("m/d/Y",$doj1); //till date or any given date

        $now=date("m/d/Y");
        //$b=strtotime($b1);
        //echo $c=$b1-$a2;
        //echo date("Y-m-d H:i:s",$c);
        $year=date("Y");
        //$chk_leap=is_leapyear($year);

        //$year_diff=365.25;

        $x=explode("/",$doj);
        $y1=explode("/",$now);

        $yy=$x[2];
        $mm=$x[0];
        $dd=$x[1];

        $yy1=$y1[2];
        $mm1=$y1[0];
        $dd1=$y1[1];
        $mn=0;
        $mn1=0;
        $ye=0;
        if($mm1>$mm)
        {
            $mn=$mm1-$mm;
            if($dd1<$dd)
            {
                $mn=$mn-1;
            }
            $ye=$yy1-$yy;
        }
        else if($mm1<$mm)
        {
            $mn=12-$mm;
            //$mn=$mn;

            if($mm!=1)
            {
                $mn1=$mm1-1;
            }

            $mn+=$mn1;
            if($dd1>$dd)
            {
                $mn+=1;
            }

            $yy=$yy+1;
            $ye=$yy1-$yy;
        }
        else
        {
            $ye=$yy1-$yy;
            $ye=$ye-1;

            $mn=12-1;

            if($dd1>$dd)
            {
                $ye+=1;
                $mn=0;
            }
        }

        $to=$ye." year and ".$mn." months";
        return $ye.".".$mn;

        /*return daysDiff($x[2],$x[0],$x[1]);
         $days=dateDiff("/",$now,$doj)/$year_diff;
        $days_exp=explode(".",$days);
        return $years_exp=$days; //number of years exp*/
    }
?>

Is std::vector copying the objects with a push_back?

Why did it take a lot of valgrind investigation to find this out! Just prove it to yourself with some simple code e.g.

std::vector<std::string> vec;

{
      std::string obj("hello world");
      vec.push_pack(obj);
}

std::cout << vec[0] << std::endl;  

If "hello world" is printed, the object must have been copied

Bash script to run php script

A previous poster said..

If you have PHP installed as a command line tool… your shebang (#!) line needs to look like this: #!/usr/bin/php

While this could be true… just because you can type in php does NOT necessarily mean that's where php is going to be... /usr/bin/php is A common location… but as with any shebang… it needs to be tailored to YOUR env.

a quick way to find out WHERE YOUR particular executable is located on your $PATH, try.. ?which -a php ENTER, which for me looks like..

php is /usr/local/php5/bin/php
php is /usr/bin/php
php is /usr/local/bin/php
php is /Library/WebServer/CGI-Executables/php

The first one is the default i'd get if I just typed in php at a command prompt… but I can use any of them in a shebang, or directly… You can also combine the executable name with env, as is often seen, but I don't really know much about / trust that. XOXO.

Redirect Windows cmd stdout and stderr to a single file

There is, however, no guarantee that the output of SDTOUT and STDERR are interweaved line-by-line in timely order, using the POSIX redirect merge syntax.

If an application uses buffered output, it may happen that the text of one stream is inserted in the other at a buffer boundary, which may appear in the middle of a text line.

A dedicated console output logger (I.e. the "StdOut/StdErr Logger" by 'LoRd MuldeR') may be more reliable for such a task.

See: MuldeR's OpenSource Projects

How to Automatically Close Alerts using Twitter Bootstrap

try this one

$(function () {

 setTimeout(function () {
            if ($(".alert").is(":visible")){
                 //you may add animate.css class for fancy fadeout
                $(".alert").fadeOut("fast");
            }

        }, 3000)

});

How can getContentResolver() be called in Android?

A solution would be to get the ContentResolver from the context

ContentResolver contentResolver = getContext().getContentResolver();

Link to the documentation : ContentResolver

How to shutdown my Jenkins safely?

You can also look in the init script area (e.g. centos vi /etc/init.d/jenkins ) for details on how the service is actually started and stopped.

How do I parse a HTML page with Node.js

Use Cheerio. It isn't as strict as jsdom and is optimized for scraping. As a bonus, uses the jQuery selectors you already know.

? Familiar syntax: Cheerio implements a subset of core jQuery. Cheerio removes all the DOM inconsistencies and browser cruft from the jQuery library, revealing its truly gorgeous API.

? Blazingly fast: Cheerio works with a very simple, consistent DOM model. As a result parsing, manipulating, and rendering are incredibly efficient. Preliminary end-to-end benchmarks suggest that cheerio is about 8x faster than JSDOM.

? Insanely flexible: Cheerio wraps around @FB55's forgiving htmlparser. Cheerio can parse nearly any HTML or XML document.

What does #defining WIN32_LEAN_AND_MEAN exclude exactly?

According the to Windows Dev Center WIN32_LEAN_AND_MEAN excludes APIs such as Cryptography, DDE, RPC, Shell, and Windows Sockets.

How do you get centered content using Twitter Bootstrap?

My preferred method for centering blocks of information while maintaining responsiveness (mobile compatibility) is to place two empty span1 divs before and after the content you wish to center.

<div class="row-fluid">

    <div class="span1">
    </div>

        <div class="span10">
          <div class="hero-unit">
            <h1>Reading Resources</h1>
            <p>Read here...</p>
          </div>
        </div><!--/span-->

    <div class="span1">
    </div>

</div><!--/row-->

In OS X Lion, LANG is not set to UTF-8, how to fix it?

I recently had the same issue on OS X Sierra with bash shell, and thanks to answers above I only had to edit the file

~/.bash_profile 

and append those lines

export LC_ALL=en_US.UTF-8
export LANG=en_US.UTF-8

How to convert JSON data into a Python object

You could try this:

class User(object):
    def __init__(self, name, username, *args, **kwargs):
        self.name = name
        self.username = username

import json
j = json.loads(your_json)
u = User(**j)

Just create a new Object, and pass the parameters as a map.

Date Comparison using Java

private boolean checkDateLimit() {

    long CurrentDateInMilisecond = System.currentTimeMillis(); // Date 1
    long Date1InMilisecond = Date1.getTimeInMillis(); //Date2

    if (CurrentDateInMilisecond <= Date1InMilisecond) {
        return true;
    } else {
        return false;
    }

}

// Convert both date into milisecond value .

Simple prime number generator in Python

There are some problems:

  • Why do you print out count when it didn't divide by x? It doesn't mean it's prime, it means only that this particular x doesn't divide it
  • continue moves to the next loop iteration - but you really want to stop it using break

Here's your code with a few fixes, it prints out only primes:

import math

def main():
    count = 3
    
    while True:
        isprime = True
        
        for x in range(2, int(math.sqrt(count) + 1)):
            if count % x == 0: 
                isprime = False
                break
        
        if isprime:
            print count
        
        count += 1

For much more efficient prime generation, see the Sieve of Eratosthenes, as others have suggested. Here's a nice, optimized implementation with many comments:

# Sieve of Eratosthenes
# Code by David Eppstein, UC Irvine, 28 Feb 2002
# http://code.activestate.com/recipes/117119/

def gen_primes():
    """ Generate an infinite sequence of prime numbers.
    """
    # Maps composites to primes witnessing their compositeness.
    # This is memory efficient, as the sieve is not "run forward"
    # indefinitely, but only as long as required by the current
    # number being tested.
    #
    D = {}
    
    # The running integer that's checked for primeness
    q = 2
    
    while True:
        if q not in D:
            # q is a new prime.
            # Yield it and mark its first multiple that isn't
            # already marked in previous iterations
            # 
            yield q
            D[q * q] = [q]
        else:
            # q is composite. D[q] is the list of primes that
            # divide it. Since we've reached q, we no longer
            # need it in the map, but we'll mark the next 
            # multiples of its witnesses to prepare for larger
            # numbers
            # 
            for p in D[q]:
                D.setdefault(p + q, []).append(p)
            del D[q]
        
        q += 1

Note that it returns a generator.

Most efficient way to find smallest of 3 numbers Java?

Math.min uses a simple comparison to do its thing. The only advantage to not using Math.min is to save the extra function calls, but that is a negligible saving.

If you have more than just three numbers, having a minimum method for any number of doubles might be valuable and would look something like:

public static double min(double ... numbers) {
    double min = numbers[0];
    for (int i=1 ; i<numbers.length ; i++) {
        min = (min <= numbers[i]) ? min : numbers[i];
    }
    return min;
}

For three numbers this is the functional equivalent of Math.min(a, Math.min(b, c)); but you save one method invocation.

Can the Android drawable directory contain subdirectories?

With the advent of library system, creating a library per big set of assets could be a solution.

It is still problematic as one must avoid using the same names within all the assets but using a prefix scheme per library should help with that.

It's not as simple as being able to create folders but that helps keeping things sane...

How can JavaScript save to a local file?

If you are using FireFox you can use the File HandleAPI

https://developer.mozilla.org/en-US/docs/Web/API/File_Handle_API

I had just tested it out and it works!

What is Ad Hoc Query?

An Ad-hoc query is one created to provide a specific recordset from any or multiple merged tables available on the DB server. These queries usually serve a single-use purpose, and may not be necessary to incorporate into any stored procedure to run again in the future.

Ad-hoc scenario: You receive a request for a specific subset of data with a unique set of variables. If there is no pre-written query that can provide the necessary results, you must write an Ad-hoc query to generate the recordset results.

Beyond a single use Ad-hoc query are stored procedures; i.e. queries which are stored within the DB interface tool. These stored procedures can then be executed in sequence within a module or macro to accomplish a predefined task either on demand, on a schedule, or triggered by another event.

Stored Procedure scenario: Every month you need to generate a report from the same set of tables and with the same variables (these variables may be specific predefined values, computed values such as “end of current month”, or a user’s input values). You would created the procedure as an ad-hoc query the first time. After testing the results to ensure accuracy, you may chose to deploy this query. You would then store the query or series of queries in a module or macro to run again as needed.

How can I send JSON response in symfony2 controller

If your data is already serialized:

a) send a JSON response

public function someAction()
{
    $response = new Response();
    $response->setContent(file_get_contents('path/to/file'));
    $response->headers->set('Content-Type', 'application/json');
    return $response;
}

b) send a JSONP response (with callback)

public function someAction()
{
    $response = new Response();
    $response->setContent('/**/FUNCTION_CALLBACK_NAME(' . file_get_contents('path/to/file') . ');');
    $response->headers->set('Content-Type', 'text/javascript');
    return $response;
}

If your data needs be serialized:

c) send a JSON response

public function someAction()
{
    $response = new JsonResponse();
    $response->setData([some array]);
    return $response;
}

d) send a JSONP response (with callback)

public function someAction()
{
    $response = new JsonResponse();
    $response->setData([some array]);
    $response->setCallback('FUNCTION_CALLBACK_NAME');
    return $response;
}

e) use groups in Symfony 3.x.x

Create groups inside your Entities

<?php

namespace Mindlahus;

use Symfony\Component\Serializer\Annotation\Groups;

/**
 * Some Super Class Name
 *
 * @ORM    able("table_name")
 * @ORM\Entity(repositoryClass="SomeSuperClassNameRepository")
 * @UniqueEntity(
 *  fields={"foo", "boo"},
 *  ignoreNull=false
 * )
 */
class SomeSuperClassName
{
    /**
     * @Groups({"group1", "group2"})
     */
    public $foo;
    /**
     * @Groups({"group1"})
     */
    public $date;

    /**
     * @Groups({"group3"})
     */
    public function getBar() // is* methods are also supported
    {
        return $this->bar;
    }

    // ...
}

Normalize your Doctrine Object inside the logic of your application

<?php

use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Serializer\Mapping\Factory\ClassMetadataFactory;
// For annotations
use Doctrine\Common\Annotations\AnnotationReader;
use Symfony\Component\Serializer\Mapping\Loader\AnnotationLoader;
use Symfony\Component\Serializer\Serializer;
use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
use Symfony\Component\Serializer\Encoder\JsonEncoder;

...

$repository = $this->getDoctrine()->getRepository('Mindlahus:SomeSuperClassName');
$SomeSuperObject = $repository->findOneById($id);

$classMetadataFactory = new ClassMetadataFactory(new AnnotationLoader(new AnnotationReader()));
$encoder = new JsonEncoder();
$normalizer = new ObjectNormalizer($classMetadataFactory);
$callback = function ($dateTime) {
    return $dateTime instanceof \DateTime
        ? $dateTime->format('m-d-Y')
        : '';
};
$normalizer->setCallbacks(array('date' => $callback));
$serializer = new Serializer(array($normalizer), array($encoder));
$data = $serializer->normalize($SomeSuperObject, null, array('groups' => array('group1')));

$response = new Response();
$response->setContent($serializer->serialize($data, 'json'));
$response->headers->set('Content-Type', 'application/json');
return $response;

JTable won't show column headers

The main difference between this answer and the accepted answer is the use of setViewportView() instead of add().

How to put JTable in JScrollPane using Eclipse IDE:

  1. Create JScrollPane container via Design tab.
  2. Stretch JScrollPane to desired size (applies to Absolute Layout).
  3. Drag and drop JTable component on top of JScrollPane (Viewport area).

In Structure > Components, table should be a child of scrollPane. enter image description here

The generated code would be something like this:

JScrollPane scrollPane = new JScrollPane();
...

JTable table = new JTable();
scrollPane.setViewportView(table);

Required maven dependencies for Apache POI to work

this is the list of maven artifact id for all poi component. in this link http://poi.apache.org/overview.html#components

telnet to port 8089 correct command

I believe telnet 74.255.12.25 8089 . Why don't u try both

Relative URLs in WordPress

I solved it in my site making this in functions.php

add_action("template_redirect", "start_buffer");
add_action("shutdown", "end_buffer", 999);

function filter_buffer($buffer) {
    $buffer = replace_insecure_links($buffer);
    return $buffer;
}
function start_buffer(){
    ob_start("filter_buffer");
}

function end_buffer(){
    if (ob_get_length()) ob_end_flush();
}

function replace_insecure_links($str) {

   $str = str_replace ( array("http://www.yoursite.com/", "https://www.yoursite.com/") , array("/", "/"), $str);

   return apply_filters("rsssl_fixer_output", $str);

}

I took part of one plugin, cut it into pieces and make this. It replaced ALL links in my site (menus, css, scripts etc.) and everything was working.

Cross compile Go on OSX?

for people who need CGO enabled and cross compile from OSX targeting windows

I needed CGO enabled while compiling for windows from my mac since I had imported the https://github.com/mattn/go-sqlite3 and it needed it. Compiling according to other answers gave me and error:

/usr/local/go/src/runtime/cgo/gcc_windows_amd64.c:8:10: fatal error: 'windows.h' file not found

If you're like me and you have to compile with CGO. This is what I did:

1.We're going to cross compile for windows with a CGO dependent library. First we need a cross compiler installed like mingw-w64

brew install mingw-w64

This will probably install it here /usr/local/opt/mingw-w64/bin/.

2.Just like other answers we first need to add our windows arch to our go compiler toolchain now. Compiling a compiler needs a compiler (weird sentence) compiling go compiler needs a separate pre-built compiler. We can download a prebuilt binary or build from source in a folder eg: ~/Documents/go now we can improve our Go compiler, according to top answer but this time with CGO_ENABLED=1 and our separate prebuilt compiler GOROOT_BOOTSTRAP(Pooya is my username):

cd /usr/local/go/src
sudo GOOS=windows GOARCH=amd64 CGO_ENABLED=1 GOROOT_BOOTSTRAP=/Users/Pooya/Documents/go ./make.bash --no-clean
sudo GOOS=windows GOARCH=386 CGO_ENABLED=1 GOROOT_BOOTSTRAP=/Users/Pooya/Documents/go ./make.bash --no-clean

3.Now while compiling our Go code use mingw to compile our go file targeting windows with CGO enabled:

GOOS="windows" GOARCH="386" CGO_ENABLED="1" CC="/usr/local/opt/mingw-w64/bin/i686-w64-mingw32-gcc" go build hello.go
GOOS="windows" GOARCH="amd64" CGO_ENABLED="1" CC="/usr/local/opt/mingw-w64/bin/x86_64-w64-mingw32-gcc" go build hello.go

Node.js ES6 classes with require

Just treat the ES6 class name the same as you would have treated the constructor name in the ES5 way. They are one and the same.

The ES6 syntax is just syntactic sugar and creates exactly the same underlying prototype, constructor function and objects.

So, in your ES6 example with:

// animal.js
class Animal {
    ...
}

var a = new Animal();

module.exports = {Animal: Animal};

You can just treat Animal like the constructor of your object (the same as you would have done in ES5). You can export the constructor. You can call the constructor with new Animal(). Everything is the same for using it. Only the declaration syntax is different. There's even still an Animal.prototype that has all your methods on it. The ES6 way really does create the same coding result, just with fancier/nicer syntax.


On the import side, this would then be used like this:

const Animal = require('./animal.js').Animal;

let a = new Animal();

This scheme exports the Animal constructor as the .Animal property which allows you to export more than one thing from that module.

If you don't need to export more than one thing, you can do this:

// animal.js
class Animal {
    ...
}

module.exports = Animal;

And, then import it with:

const Animal = require('./animal.js');

let a = new Animal();

how to fix EXE4J_JAVA_HOME, No JVM could be found on your system error?

There are few steps to overcome this problem:

  1. Uninstall Java related softwares
  2. Uninstall NodeJS if installed
  3. Download java 8 update161
  4. Install it

The problem solved: The problem raised to me at the uninstallation on openfire server.

How to stop java process gracefully?

Here is a bit tricky, but portable solution:

  • In your application implement a shutdown hook
  • When you want to shut down your JVM gracefully, install a Java Agent that calls System.exit() using the Attach API.

I implemented the Java Agent. It is available on Github: https://github.com/everit-org/javaagent-shutdown

Detailed description about the solution is available here: https://everitorg.wordpress.com/2016/06/15/shutting-down-a-jvm-process/

Infinite Recursion with Jackson JSON and Hibernate JPA issue

I also met the same problem. I used @JsonIdentityInfo's ObjectIdGenerators.PropertyGenerator.class generator type.

That's my solution:

@Entity
@Table(name = "ta_trainee", uniqueConstraints = {@UniqueConstraint(columnNames = {"id"})})
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id")
public class Trainee extends BusinessObject {
...

List all virtualenv

You can use the lsvirtualenv, in which you have two options "long" or "brief":

"long" option is the default one, it searches for any hook you may have around this command and executes it, which takes more time.

"brief" just take the virtualenvs names and prints it.

brief usage:

$ lsvirtualenv -b

long usage:

$ lsvirtualenv -l

if you don't have any hooks, or don't even know what i'm talking about, just use "brief".

How do you Encrypt and Decrypt a PHP String?

Before you do anything further, seek to understand the difference between encryption and authentication, and why you probably want authenticated encryption rather than just encryption.

To implement authenticated encryption, you want to Encrypt then MAC. The order of encryption and authentication is very important! One of the existing answers to this question made this mistake; as do many cryptography libraries written in PHP.

You should avoid implementing your own cryptography, and instead use a secure library written by and reviewed by cryptography experts.

Update: PHP 7.2 now provides libsodium! For best security, update your systems to use PHP 7.2 or higher and only follow the libsodium advice in this answer.

Use libsodium if you have PECL access (or sodium_compat if you want libsodium without PECL); otherwise...
Use defuse/php-encryption; don't roll your own cryptography!

Both of the libraries linked above make it easy and painless to implement authenticated encryption into your own libraries.

If you still want to write and deploy your own cryptography library, against the conventional wisdom of every cryptography expert on the Internet, these are the steps you would have to take.

Encryption:

  1. Encrypt using AES in CTR mode. You may also use GCM (which removes the need for a separate MAC). Additionally, ChaCha20 and Salsa20 (provided by libsodium) are stream ciphers and do not need special modes.
  2. Unless you chose GCM above, you should authenticate the ciphertext with HMAC-SHA-256 (or, for the stream ciphers, Poly1305 -- most libsodium APIs do this for you). The MAC should cover the IV as well as the ciphertext!

Decryption:

  1. Unless Poly1305 or GCM is used, recalculate the MAC of the ciphertext and compare it with the MAC that was sent using hash_equals(). If it fails, abort.
  2. Decrypt the message.

Other Design Considerations:

  1. Do not compress anything ever. Ciphertext is not compressible; compressing plaintext before encryption can lead to information leaks (e.g. CRIME and BREACH on TLS).
  2. Make sure you use mb_strlen() and mb_substr(), using the '8bit' character set mode to prevent mbstring.func_overload issues.
  3. IVs should be generating using a CSPRNG; If you're using mcrypt_create_iv(), DO NOT USE MCRYPT_RAND!
  4. Unless you're using an AEAD construct, ALWAYS encrypt then MAC!
  5. bin2hex(), base64_encode(), etc. may leak information about your encryption keys via cache timing. Avoid them if possible.

Even if you follow the advice given here, a lot can go wrong with cryptography. Always have a cryptography expert review your implementation. If you are not fortunate enough to be personal friends with a cryptography student at your local university, you can always try the Cryptography Stack Exchange forum for advice.

If you need a professional analysis of your implementation, you can always hire a reputable team of security consultants to review your PHP cryptography code (disclosure: my employer).

Important: When to Not Use Encryption

Don't encrypt passwords. You want to hash them instead, using one of these password-hashing algorithms:

Never use a general-purpose hash function (MD5, SHA256) for password storage.

Don't encrypt URL Parameters. It's the wrong tool for the job.

PHP String Encryption Example with Libsodium

If you are on PHP < 7.2 or otherwise do not have libsodium installed, you can use sodium_compat to accomplish the same result (albeit slower).

<?php
declare(strict_types=1);

/**
 * Encrypt a message
 * 
 * @param string $message - message to encrypt
 * @param string $key - encryption key
 * @return string
 * @throws RangeException
 */
function safeEncrypt(string $message, string $key): string
{
    if (mb_strlen($key, '8bit') !== SODIUM_CRYPTO_SECRETBOX_KEYBYTES) {
        throw new RangeException('Key is not the correct size (must be 32 bytes).');
    }
    $nonce = random_bytes(SODIUM_CRYPTO_SECRETBOX_NONCEBYTES);
    
    $cipher = base64_encode(
        $nonce.
        sodium_crypto_secretbox(
            $message,
            $nonce,
            $key
        )
    );
    sodium_memzero($message);
    sodium_memzero($key);
    return $cipher;
}

/**
 * Decrypt a message
 * 
 * @param string $encrypted - message encrypted with safeEncrypt()
 * @param string $key - encryption key
 * @return string
 * @throws Exception
 */
function safeDecrypt(string $encrypted, string $key): string
{   
    $decoded = base64_decode($encrypted);
    $nonce = mb_substr($decoded, 0, SODIUM_CRYPTO_SECRETBOX_NONCEBYTES, '8bit');
    $ciphertext = mb_substr($decoded, SODIUM_CRYPTO_SECRETBOX_NONCEBYTES, null, '8bit');
    
    $plain = sodium_crypto_secretbox_open(
        $ciphertext,
        $nonce,
        $key
    );
    if (!is_string($plain)) {
        throw new Exception('Invalid MAC');
    }
    sodium_memzero($ciphertext);
    sodium_memzero($key);
    return $plain;
}

Then to test it out:

<?php
// This refers to the previous code block.
require "safeCrypto.php"; 

// Do this once then store it somehow:
$key = random_bytes(SODIUM_CRYPTO_SECRETBOX_KEYBYTES);
$message = 'We are all living in a yellow submarine';

$ciphertext = safeEncrypt($message, $key);
$plaintext = safeDecrypt($ciphertext, $key);

var_dump($ciphertext);
var_dump($plaintext);

Halite - Libsodium Made Easier

One of the projects I've been working on is an encryption library called Halite, which aims to make libsodium easier and more intuitive.

<?php
use \ParagonIE\Halite\KeyFactory;
use \ParagonIE\Halite\Symmetric\Crypto as SymmetricCrypto;

// Generate a new random symmetric-key encryption key. You're going to want to store this:
$key = new KeyFactory::generateEncryptionKey();
// To save your encryption key:
KeyFactory::save($key, '/path/to/secret.key');
// To load it again:
$loadedkey = KeyFactory::loadEncryptionKey('/path/to/secret.key');

$message = 'We are all living in a yellow submarine';
$ciphertext = SymmetricCrypto::encrypt($message, $key);
$plaintext = SymmetricCrypto::decrypt($ciphertext, $key);

var_dump($ciphertext);
var_dump($plaintext);

All of the underlying cryptography is handled by libsodium.

Example with defuse/php-encryption

<?php
/**
 * This requires https://github.com/defuse/php-encryption
 * php composer.phar require defuse/php-encryption
 */

use Defuse\Crypto\Crypto;
use Defuse\Crypto\Key;

require "vendor/autoload.php";

// Do this once then store it somehow:
$key = Key::createNewRandomKey();

$message = 'We are all living in a yellow submarine';

$ciphertext = Crypto::encrypt($message, $key);
$plaintext = Crypto::decrypt($ciphertext, $key);

var_dump($ciphertext);
var_dump($plaintext);

Note: Crypto::encrypt() returns hex-encoded output.

Encryption Key Management

If you're tempted to use a "password", stop right now. You need a random 128-bit encryption key, not a human memorable password.

You can store an encryption key for long-term use like so:

$storeMe = bin2hex($key);

And, on demand, you can retrieve it like so:

$key = hex2bin($storeMe);

I strongly recommend just storing a randomly generated key for long-term use instead of any sort of password as the key (or to derive the key).

If you're using Defuse's library:

"But I really want to use a password."

That's a bad idea, but okay, here's how to do it safely.

First, generate a random key and store it in a constant.

/**
 * Replace this with your own salt! 
 * Use bin2hex() then add \x before every 2 hex characters, like so:
 */
define('MY_PBKDF2_SALT', "\x2d\xb7\x68\x1a\x28\x15\xbe\x06\x33\xa0\x7e\x0e\x8f\x79\xd5\xdf");

Note that you're adding extra work and could just use this constant as the key and save yourself a lot of heartache!

Then use PBKDF2 (like so) to derive a suitable encryption key from your password rather than encrypting with your password directly.

/**
 * Get an AES key from a static password and a secret salt
 * 
 * @param string $password Your weak password here
 * @param int $keysize Number of bytes in encryption key
 */
function getKeyFromPassword($password, $keysize = 16)
{
    return hash_pbkdf2(
        'sha256',
        $password,
        MY_PBKDF2_SALT,
        100000, // Number of iterations
        $keysize,
        true
    );
}

Don't just use a 16-character password. Your encryption key will be comically broken.

Access cell value of datatable

foreach(DataRow row in dt.Rows)
{
    string value = row[3].ToString();
}

How to split a large text file into smaller files with equal number of lines?

split the file "file.txt" into 10000 lines files:

split -l 10000 file.txt

adding multiple event listeners to one element

What about something like this:

['focusout','keydown'].forEach( function(evt) {
        self.slave.addEventListener(evt, function(event) {
            // Here `this` is for the slave, i.e. `self.slave`
            if ((event.type === 'keydown' && event.which === 27) || event.type === 'focusout') {
                this.style.display = 'none';
                this.parentNode.querySelector('.master').style.display = '';
                this.parentNode.querySelector('.master').value = this.value;
                console.log('out');
            }
        }, false);
});

// The above is replacement of:
 /*   self.slave.addEventListener("focusout", function(event) { })
      self.slave.addEventListener("keydown", function(event) {
         if (event.which === 27) {  // Esc
            }
      })
*/

MySQL - force not to use cache for testing speed of query

Using a user-defined variable within a query makes the query resuts uncacheable. I found it a much better indicator than using SQL_NO_CACHE. But you should put the variable in a place where the variable setting would not seriously affect the performance:

SELECT t.*
FROM thetable t, (SELECT @a:=NULL) as init;

Sum of two input value by jquery

if in multiple class you want to change additional operation in perticular class that show in below example

$('.like').click(function(){    
var like= $(this).text();
$(this).text(+like + +1);
});

PowerShell Connect to FTP server and get files

Based on Why does FtpWebRequest download files from the root directory? Can this cause a 553 error?, I wrote a PowerShell script that enabled to download a file from a FTP-Server via explicit FTP over TLS:

# Config
$Username = "USERNAME"
$Password = "PASSWORD"
$LocalFile = "C:\PATH_TO_DIR\FILNAME.EXT"
#e.g. "C:\temp\somefile.txt"
$RemoteFile = "ftp://PATH_TO_REMOTE_FILE"
#e.g. "ftp://ftp.server.com/home/some/path/somefile.txt"

try{ 
    # Create a FTPWebRequest
    $FTPRequest = [System.Net.FtpWebRequest]::Create($RemoteFile)
    $FTPRequest.Credentials = New-Object System.Net.NetworkCredential($Username,$Password)
    $FTPRequest.Method = [System.Net.WebRequestMethods+Ftp]::DownloadFile
    $FTPRequest.UseBinary = $true
    $FTPRequest.KeepAlive = $false
    $FTPRequest.EnableSsl  = $true
    # Send the ftp request
    $FTPResponse = $FTPRequest.GetResponse()
    # Get a download stream from the server response
    $ResponseStream = $FTPResponse.GetResponseStream()
    # Create the target file on the local system and the download buffer
    $LocalFileFile = New-Object IO.FileStream ($LocalFile,[IO.FileMode]::Create)
    [byte[]]$ReadBuffer = New-Object byte[] 1024
    # Loop through the download

    do {
        $ReadLength = $ResponseStream.Read($ReadBuffer,0,1024)
        $LocalFileFile.Write($ReadBuffer,0,$ReadLength)
    }
    while ($ReadLength -ne 0)
}catch [Exception]
{
    $Request = $_.Exception
    Write-host "Exception caught: $Request"
}

Ctrl+click doesn't work in Eclipse Juno

I faced this issue several times. As described by Ashutosh Jindal, if the Hyperlinking is already enabled and still the ctrl+click doesn't work then you need to:

  1. Navigate to Java -> Editor -> Mark Occurrences in Preferences
  2. Uncheck "Mark occurrences of the selected element in the current file" if its already checked.
  3. Now, check on the above mentioned option and then check on all the items under it. Click Apply.

This should now enabled the ctrl+click functionality.

How do you compare structs for equality in C?

It depends on whether the question you are asking is:

  1. Are these two structs the same object?
  2. Do they have the same value?

To find out if they are the same object, compare pointers to the two structs for equality. If you want to find out in general if they have the same value you have to do a deep comparison. This involves comparing all the members. If the members are pointers to other structs you need to recurse into those structs too.

In the special case where the structs do not contain pointers you can do a memcmp to perform a bitwise comparison of the data contained in each without having to know what the data means.

Make sure you know what 'equals' means for each member - it is obvious for ints but more subtle when it comes to floating-point values or user-defined types.

What's the best practice for putting multiple projects in a git repository?

Solution 3

This is for using a single directory for multiple projects. I use this technique for some closely related projects where I often need to pull changes from one project into another. It's similar to the orphaned branches idea but the branches don't need to be orphaned. Simply start all the projects from the same empty directory state.

Start all projects from one committed empty directory

Don't expect wonders from this solution. As I see it, you are always going to have annoyances with untracked files. Git doesn't really have a clue what to do with them and so if there are intermediate files generated by a compiler and ignored by your .gitignore file, it is likely that they will be left hanging some of the time if you try rapidly swapping between - for example - your software project and a PH.D thesis project.

However here is the plan. Start as you ought to start any git projects, by committing the empty repository, and then start all your projects from the same empty directory state. That way you are certain that the two lots of files are fairly independent. Also, give your branches a proper name and don't lazily just use "master". Your projects need to be separate so give them appropriate names.

Git commits (and hence tags and branches) basically store the state of a directory and its subdirectories and Git has no idea whether these are parts of the same or different projects so really there is no problem for git storing different projects in the same repository. The problem is then for you clearing up the untracked files from one project when using another, or separating the projects later.

Create an empty repository

cd some_empty_directory
git init
touch .gitignore
git add .gitignore
git commit -m empty
git tag EMPTY

Start your projects from empty.

Work on one project.

git branch software EMPTY
git checkout software
echo "array board[8,8] of piece" > chess.prog

git add chess.prog 
git commit -m "chess program"

Start another project

whenever you like.

git branch thesis EMPTY
git checkout thesis
echo "the meaning of meaning" > philosophy_doctorate.txt
git add philosophy_doctorate.txt 
git commit -m "Ph.D"

Switch back and forth

Go back and forwards between projects whenever you like. This example goes back to the chess software project.

git checkout software
echo "while not end_of_game do make_move()" >> chess.prog
git add chess.prog 
git commit -m "improved chess program"

Untracked files are annoying

You will however be annoyed by untracked files when swapping between projects/branches.

touch untracked_software_file.prog
git checkout thesis 
ls
    philosophy_doctorate.txt  untracked_software_file.prog

It's not an insurmountable problem

Sort of by definition, git doesn't really know what to do with untracked files and it's up to you to deal with them. You can stop untracked files from being carried around from one branch to another as follows.

git checkout EMPTY 
ls
    untracked_software_file.prog
rm -r *
    (directory is now really empty, apart from the repository stuff!)
git checkout thesis
ls
    philosophy_doctorate.txt

By ensuring that the directory was empty before checking out our new project we made sure there were no hanging untracked files from another project.

A refinement

$ GIT_AUTHOR_DATE='2001-01-01:T01:01:01' GIT_COMMITTER_DATE='2001-01-01T01:01:01' git commit -m empty

If the same dates are specified whenever committing an empty repository, then independently created empty repository commits can have the same SHA1 code. This allows two repositories to be created independently and then merged together into a single tree with a common root in one repository later.

Example

# Create thesis repository. 
# Merge existing chess repository branch into it

mkdir single_repo_for_thesis_and_chess
cd single_repo_for_thesis_and_chess
git init
touch .gitignore
git add .gitignore
GIT_AUTHOR_DATE='2001-01-01:T01:01:01' GIT_COMMITTER_DATE='2001-01-01:T01:01:01' git commit -m empty
git tag EMPTY
echo "the meaning of meaning" > thesis.txt
git add thesis.txt
git commit -m "Wrote my PH.D"
git branch -m master thesis

# It's as simple as this ...
git remote add chess ../chessrepository/.git
git fetch chess chess:chess

Result

Diagram of merged repositories

Use subdirectories per project?

It may also help if you keep your projects in subdirectories where possible, e.g. instead of having files

chess.prog
philosophy_doctorate.txt 

have

chess/chess.prog
thesis/philosophy_doctorate.txt 

In this case your untracked software file will be chess/untracked_software_file.prog. When working in the thesis directory you should not be disturbed by untracked chess program files, and you may find occasions when you can work happily without deleting untracked files from other projects.

Also, if you want to remove untracked files from other projects, it will be quicker (and less prone to error) to dump an unwanted directory than to remove unwanted files by selecting each of them.

Branch names can include '/' characters

So you might want to name your branches something like

project1/master
project1/featureABC
project2/master
project2/featureXYZ

Check if a variable is between two numbers with Java

Assuming you are programming in Java, this works:

if (90 >= angle  &&  angle <= 180 )  {

(don't you mean 90 is less than angle? If so: 90 <= angle)

How to cast/convert pointer to reference in C++

Call it like this:

foo(*ob);

Note that there is no casting going on here, as suggested in your question title. All we have done is de-referenced the pointer to the object which we then pass to the function.

In Jinja2, how do you test if a variable is undefined?

{% if variable is defined %} is true if the variable is None.

Since not is None is not allowed, that means that

{% if variable != None %}

is really your only option.

Setting Elastic search limit to "unlimited"

Another approach is to first do a searchType: 'count', then and then do a normal search with size set to results.count.

The advantage here is it avoids depending on a magic number for UPPER_BOUND as suggested in this similar SO question, and avoids the extra overhead of building too large of a priority queue that Shay Banon describes here. It also lets you keep your results sorted, unlike scan.

The biggest disadvantage is that it requires two requests. Depending on your circumstance, this may be acceptable.

How to add minutes to current time in swift

Save this little extension:

extension Int {

 var seconds: Int {
    return self
 }

 var minutes: Int {
    return self.seconds * 60
 }

 var hours: Int {
    return self.minutes * 60
 }

 var days: Int {
    return self.hours * 24
 }

 var weeks: Int {
    return self.days * 7
 }

 var months: Int {
    return self.weeks * 4
 }

 var years: Int {
    return self.months * 12
 }
}

Then use it intuitively like:

let threeDaysLater = TimeInterval(3.days)
date.addingTimeInterval(threeDaysLater)

How to add trendline in python matplotlib dot (scatter) graphs?

as explained here

With help from numpy one can calculate for example a linear fitting.

# plot the data itself
pylab.plot(x,y,'o')

# calc the trendline
z = numpy.polyfit(x, y, 1)
p = numpy.poly1d(z)
pylab.plot(x,p(x),"r--")
# the line equation:
print "y=%.6fx+(%.6f)"%(z[0],z[1])

How do I raise the same Exception with a custom message in Python?

Either raise the new exception with your error message using

raise Exception('your error message')

or

raise ValueError('your error message')

within the place where you want to raise it OR attach (replace) error message into current exception using 'from' (Python 3.x supported only):

except ValueError as e:
  raise ValueError('your message') from e

Delete commit on gitlab

We've had similar problem and it was not enough to only remove commit and force push to GitLab.
It was still available in GitLab interface using url:

https://gitlab.example.com/<group>/<project>/commit/<commit hash>

We've had to remove project from GitLab and recreate it to get rid of this commit in GitLab UI.

Javascript ajax call on page onload

It's even easier to do without a library

window.onload = function() {
    // code
};

Order discrete x scale by frequency/value

You can use reorder:

qplot(reorder(factor(cyl),factor(cyl),length),data=mtcars,geom="bar")

Edit:

To have the tallest bar at the left, you have to use a bit of a kludge:

qplot(reorder(factor(cyl),factor(cyl),function(x) length(x)*-1),
   data=mtcars,geom="bar")

I would expect this to also have negative heights, but it doesn't, so it works!

Convert decimal to binary in python

"{0:#b}".format(my_int)

Pretty print in MongoDB shell as default

Give a try to Mongo-hacker(node module), it alway prints pretty. https://github.com/TylerBrock/mongo-hacker

More it enhances mongo shell (supports only ver>2.4, current ver is 3.0), like

  • Colorization
  • Additional shell commands (count documents/count docs/etc)
  • API Additions (db.collection.find({ ... }).last(), db.collection.find({ ... }).reverse(), etc)
  • Aggregation Framework

I am using for while in production env, no problems yet.

Python map object is not subscriptable

In Python 3, map returns an iterable object of type map, and not a subscriptible list, which would allow you to write map[i]. To force a list result, write

payIntList = list(map(int,payList))

However, in many cases, you can write out your code way nicer by not using indices. For example, with list comprehensions:

payIntList = [pi + 1000 for pi in payList]
for pi in payIntList:
    print(pi)

Arduino IDE can't find ESP8266WiFi.h file

Starting with 1.6.4, Arduino IDE can be used to program and upload the NodeMCU board by installing the ESP8266 third-party platform package (refer https://github.com/esp8266/Arduino):

  • Start Arduino, go to File > Preferences
  • Add the following link to the Additional Boards Manager URLs: http://arduino.esp8266.com/stable/package_esp8266com_index.json and press OK button
  • Click Tools > Boards menu > Boards Manager, search for ESP8266 and install ESP8266 platform from ESP8266 community (and don't forget to select your ESP8266 boards from Tools > Boards menu after installation)

To install additional ESP8266WiFi library:

  • Click Sketch > Include Library > Manage Libraries, search for ESP8266WiFi and then install with the latest version.

After above steps, you should compile the sketch normally.

Center Contents of Bootstrap row container

For Bootstrap 4, use the below code:

<div class="mx-auto" style="width: 200px;">
  Centered element
</div>

Ref: https://getbootstrap.com/docs/4.0/utilities/spacing/#horizontal-centering

What is recursion and when should I use it?

I use recursion. What does that have to do with having a CS degree... (which I don't, by the way)

Common uses I have found:

  1. sitemaps - recurse through filesystem starting at document root
  2. spiders - crawling through a website to find email address, links, etc.
  3. ?

Deployment error:Starting of Tomcat failed, the server port 8080 is already in use

Kill the previous instance of tomcat or the process that's running on 8080.

Go to terminal and do this:

lsof -i :8080

The output will be something like:

COMMAND   PID   USER      FD   TYPE  DEVICE SIZE/OFF NODE NAME
java    76746   YourName  57u  IPv6 0xd2a83c9c1e75      0t0    TCP *:http-alt (LISTEN)

Kill this process using it's PID:

kill 76746

Regarding C++ Include another class

What is the basic problem in your code?

Your code needs to be separated out in to interfaces(.h) and Implementations(.cpp).
The compiler needs to see the composition of a type when you write something like

ClassTwo obj;

This is because the compiler needs to reserve enough memory for object of type ClassTwo to do so it needs to see the definition of ClassTwo. The most common way to do this in C++ is to split your code in to header files and source files.
The class definitions go in the header file while the implementation of the class goes in to source files. This way one can easily include header files in to other source files which need to see the definition of class who's object they create.

Why can't I simply put all code in cpp files and include them in other files?

You cannot simple put all the code in source file and then include that source file in other files.C++ standard mandates that you can declare a entity as many times as you need but you can define it only once(One Definition Rule(ODR)). Including the source file would violate the ODR because a copy of the entity is created in every translation unit where the file is included.

How to solve this particular problem?

Your code should be organized as follows:

//File1.h

Define ClassOne 

//File2.h

#include <iostream>
#include <string>


class ClassTwo
{
private:
   string myType;
public:
   void setType(string);
   std::string getType();
}; 

//File1.cpp

#include"File1.h"

Implementation of ClassOne 

//File2.cpp

#include"File2.h"

void ClassTwo::setType(std::string sType)
{
    myType = sType;
}

void ClassTwo::getType(float fVal)
{
    return myType;
} 

//main.cpp

#include <iostream>
#include <string>
#include "file1.h"
#include "file2.h"
using namespace std;

int main()
{

    ClassOne cone;
    ClassTwo ctwo;

    //some codes
}

Is there any alternative means rather than including header files?

If your code only needs to create pointers and not actual objects you might as well use Forward Declarations but note that using forward declarations adds some restrictions on how that type can be used because compiler sees that type as an Incomplete type.

Extract csv file specific columns to list in Python

import csv
from sys import argv

d = open("mydata.csv", "r")

db = []

for line in csv.reader(d):
    db.append(line)

# the rest of your code with 'db' filled with your list of lists as rows and columbs of your csv file.

wait process until all subprocess finish?

A Popen object has a .wait() method exactly defined for this: to wait for the completion of a given subprocess (and, besides, for retuning its exit status).

If you use this method, you'll prevent that the process zombies are lying around for too long.

(Alternatively, you can use subprocess.call() or subprocess.check_call() for calling and waiting. If you don't need IO with the process, that might be enough. But probably this is not an option, because your if the two subprocesses seem to be supposed to run in parallel, which they won't with (check_)call().)

If you have several subprocesses to wait for, you can do

exit_codes = [p.wait() for p in p1, p2]

which returns as soon as all subprocesses have finished. You then have a list of return codes which you maybe can evaluate.

How do I replicate a \t tab space in HTML?

This simple formula should work. Give the element whose text will contain a tab the following CSS property: white-space:pre. Otherwise your html may not render tabs at all. Then, wherever you want to have a tab in your text, type &#9;.

Since you didn't mention CSS, if you want to do this without a CSS file, just use

<tag-name style="white-space:pre">text in element&#9;more text</tag-name>

in your HTML.

How to run multiple Python versions on Windows

Adding two more solutions to the problem:

  • Use pylauncher (if you have Python 3.3 or newer there's no need to install it as it comes with Python already) and either add shebang lines to your scripts;

#! c:\[path to Python 2.5]\python.exe - for scripts you want to be run with Python 2.5
#! c:\[path to Python 2.6]\python.exe - for scripts you want to be run with Python 2.6

or instead of running python command run pylauncher command (py) specyfing which version of Python you want;

py -2.6 – version 2.6
py -2 – latest installed version 2.x
py -3.4 – version 3.4
py -3 – latest installed version 3.x

virtualenv -p c:\[path to Python 2.5]\python.exe [path where you want to have virtualenv using Python 2.5 created]\[name of virtualenv]

virtualenv -p c:\[path to Python 2.6]\python.exe [path where you want to have virtualenv using Python 2.6 created]\[name of virtualenv]

for example

virtualenv -p c:\python2.5\python.exe c:\venvs\2.5

virtualenv -p c:\python2.6\python.exe c:\venvs\2.6

then you can activate the first and work with Python 2.5 like this
c:\venvs\2.5\activate
and when you want to switch to Python 2.6 you do

deactivate  
c:\venvs\2.6\activate

How to capture multiple repeated groups?

After reading Byte Commander's answer, I want to introduce a tiny possible improvement:

You can generate a regexp that will match either n words, as long as your n is predetermined. For instance, if I want to match between 1 and 3 words, the regexp:

^([A-Z]+)(?:,([A-Z]+))?(?:,([A-Z]+))?$

will match the next sentences, with one, two or three capturing groups.

HELLO,LITTLE,WORLD
HELLO,WORLD
HELLO

You can see a fully detailed explanation about this regular expression on Regex101.

As I said, it is pretty easy to generate this regexp for any groups you want using your favorite language. Since I'm not much of a swift guy, here's a ruby example:

def make_regexp(group_regexp, count: 3, delimiter: ",")
  regexp_str = "^(#{group_regexp})"
  (count - 1).times.each do
    regexp_str += "(?:#{delimiter}(#{group_regexp}))?"
  end
  regexp_str += "$"
  return regexp_str
end

puts make_regexp("[A-Z]+")

That being said, I'd suggest not using regular expression in that case, there are many other great tools from a simple split to some tokenization patterns depending on your needs. IMHO, a regular expression is not one of them. For instance in ruby I'd use something like str.split(",") or str.scan(/[A-Z]+/)

Create a Cumulative Sum Column in MySQL

Using a correlated query:


  SELECT t.id,
         t.count,
         (SELECT SUM(x.count)
            FROM TABLE x
           WHERE x.id <= t.id) AS cumulative_sum
    FROM TABLE t
ORDER BY t.id

Using MySQL variables:


  SELECT t.id,
         t.count,
         @running_total := @running_total + t.count AS cumulative_sum
    FROM TABLE t
    JOIN (SELECT @running_total := 0) r
ORDER BY t.id

Note:

  • The JOIN (SELECT @running_total := 0) r is a cross join, and allows for variable declaration without requiring a separate SET command.
  • The table alias, r, is required by MySQL for any subquery/derived table/inline view

Caveats:

  • MySQL specific; not portable to other databases
  • The ORDER BY is important; it ensures the order matches the OP and can have larger implications for more complicated variable usage (IE: psuedo ROW_NUMBER/RANK functionality, which MySQL lacks)

How to remove the border highlight on an input text element

Remove the outline when focus is on element, using below CSS property:

input:focus {
    outline: 0;
}

This CSS property removes the outline for all input fields on focus or use pseudo class to remove outline of element using below CSS property.

.className input:focus {
    outline: 0;
} 

This property removes the outline for selected element.

How to make custom error pages work in ASP.NET MVC 4

Building on the answer posted by maxspan, I've put together a minimal sample project on GitHub showing all the working parts.

Basically, we just add an Application_Error method to global.asax.cs to intercept the exception and give us an opportunity to redirect (or more correctly, transfer request) to a custom error page.

    protected void Application_Error(Object sender, EventArgs e)
    {
        // See http://stackoverflow.com/questions/13905164/how-to-make-custom-error-pages-work-in-asp-net-mvc-4
        // for additional context on use of this technique

        var exception = Server.GetLastError();
        if (exception != null)
        {
            // This would be a good place to log any relevant details about the exception.
            // Since we are going to pass exception information to our error page via querystring,
            // it will only be practical to issue a short message. Further detail would have to be logged somewhere.

            // This will invoke our error page, passing the exception message via querystring parameter
            // Note that we chose to use Server.TransferRequest, which is only supported in IIS 7 and above.
            // As an alternative, Response.Redirect could be used instead.
            // Server.Transfer does not work (see https://support.microsoft.com/en-us/kb/320439 )
            Server.TransferRequest("~/Error?Message=" + exception.Message);
        }

    }

Error Controller:

/// <summary>
/// This controller exists to provide the error page
/// </summary>
public class ErrorController : Controller
{
    /// <summary>
    /// This action represents the error page
    /// </summary>
    /// <param name="Message">Error message to be displayed (provided via querystring parameter - a design choice)</param>
    /// <returns></returns>
    public ActionResult Index(string Message)
    {
        // We choose to use the ViewBag to communicate the error message to the view
        ViewBag.Message = Message;
        return View();
    }

}

Error page View:

<!DOCTYPE html>

<html>
<head>
    <title>Error</title>
</head>
<body>

    <h2>My Error</h2>
    <p>@ViewBag.Message</p>
</body>
</html>

Nothing else is involved, other than disabling/removing filters.Add(new HandleErrorAttribute()) in FilterConfig.cs

public class FilterConfig
{
    public static void RegisterGlobalFilters(GlobalFilterCollection filters)
    {
        //filters.Add(new HandleErrorAttribute()); // <== disable/remove
    }
}

While very simple to implement, the one drawback I see in this approach is using querystring to deliver exception information to the target error page.

How to check whether a string contains a substring in Ruby

Expanding on Clint Pachl's answer:

Regex matching in Ruby returns nil when the expression doesn't match. When it does, it returns the index of the character where the match happens. For example:

"foobar" =~ /bar/  # returns 3
"foobar" =~ /foo/  # returns 0
"foobar" =~ /zzz/  # returns nil

It's important to note that in Ruby only nil and the boolean expression false evaluate to false. Everything else, including an empty Array, empty Hash, or the Integer 0, evaluates to true.

That's why the /foo/ example above works, and why.

if "string" =~ /regex/

works as expected, only entering the 'true' part of the if block if a match occurred.

How to differ sessions in browser-tabs?

I resolved this of following way:

  • I've assigned a name to window this name is the same of connection resource.
  • plus 1 to rid stored in cookie for attach connection.
  • I've created a function to capture all xmloutput response and assign sid and rid to cookie in json format. I do this for each window.name.

here the code:

var deferred = $q.defer(),
        self = this,
        onConnect = function(status){
          if (status === Strophe.Status.CONNECTING) {
            deferred.notify({status: 'connecting'});
          } else if (status === Strophe.Status.CONNFAIL) {
            self.connected = false;
            deferred.notify({status: 'fail'});
          } else if (status === Strophe.Status.DISCONNECTING) {
            deferred.notify({status: 'disconnecting'});
          } else if (status === Strophe.Status.DISCONNECTED) {
            self.connected = false;
            deferred.notify({status: 'disconnected'});
          } else if (status === Strophe.Status.CONNECTED) {
            self.connection.send($pres().tree());
            self.connected = true;
            deferred.resolve({status: 'connected'});
          } else if (status === Strophe.Status.ATTACHED) {
            deferred.resolve({status: 'attached'});
            self.connected = true;
          }
        },
        output = function(data){
          if (self.connected){
            var rid = $(data).attr('rid'),
                sid = $(data).attr('sid'),
                storage = {};

            if (localStorageService.cookie.get('day_bind')){
              storage = localStorageService.cookie.get('day_bind');
            }else{
              storage = {};
            }
            storage[$window.name] = sid + '-' + rid;
            localStorageService.cookie.set('day_bind', angular.toJson(storage));
          }
        };
    if ($window.name){
      var storage = localStorageService.cookie.get('day_bind'),
          value = storage[$window.name].split('-')
          sid = value[0],
          rid = value[1];
      self.connection = new Strophe.Connection(BoshService);
      self.connection.xmlOutput = output;
      self.connection.attach('bosh@' + BoshDomain + '/' + $window.name, sid, parseInt(rid, 10) + 1, onConnect);
    }else{
      $window.name = 'web_' + (new Date()).getTime();
      self.connection = new Strophe.Connection(BoshService);
      self.connection.xmlOutput = output;
      self.connection.connect('bosh@' + BoshDomain + '/' + $window.name, '123456', onConnect);
    }

I hope help you

how to check if a file is a directory or regular file in python?

An educational example from the stat documentation:

import os, sys
from stat import *

def walktree(top, callback):
    '''recursively descend the directory tree rooted at top,
       calling the callback function for each regular file'''

    for f in os.listdir(top):
        pathname = os.path.join(top, f)
        mode = os.stat(pathname)[ST_MODE]
        if S_ISDIR(mode):
            # It's a directory, recurse into it
            walktree(pathname, callback)
        elif S_ISREG(mode):
            # It's a file, call the callback function
            callback(pathname)
        else:
            # Unknown file type, print a message
            print 'Skipping %s' % pathname

def visitfile(file):
    print 'visiting', file

if __name__ == '__main__':
    walktree(sys.argv[1], visitfile)

Getting the last element of a split string array

And if you don't want to construct an array ...

var str = "how,are you doing, today?";
var res = str.replace(/(.*)([, ])([^, ]*$)/,"$3");

The breakdown in english is:

/(anything)(any separator once)(anything that isn't a separator 0 or more times)/

The replace just says replace the entire string with the stuff after the last separator.

So you can see how this can be applied generally. Note the original string is not modified.

How can I use a custom font in Java?

If you include a font file (otf, ttf, etc.) in your package, you can use the font in your application via the method described here:

Oracle Java SE 6: java.awt.Font

There is a tutorial available from Oracle that shows this example:

try {
     GraphicsEnvironment ge = 
         GraphicsEnvironment.getLocalGraphicsEnvironment();
     ge.registerFont(Font.createFont(Font.TRUETYPE_FONT, new File("A.ttf")));
} catch (IOException|FontFormatException e) {
     //Handle exception
}

I would probably wrap this up in some sort of resource loader though as to not reload the file from the package every time you want to use it.

An answer more closely related to your original question would be to install the font as part of your application's installation process. That process will depend on the installation method you choose. If it's not a desktop app you'll have to look into the links provided.

add a string prefix to each value in a string column using Pandas

As an alternative, you can also use an apply combined with format (or better with f-strings) which I find slightly more readable if one e.g. also wants to add a suffix or manipulate the element itself:

df = pd.DataFrame({'col':['a', 0]})

df['col'] = df['col'].apply(lambda x: "{}{}".format('str', x))

which also yields the desired output:

    col
0  stra
1  str0

If you are using Python 3.6+, you can also use f-strings:

df['col'] = df['col'].apply(lambda x: f"str{x}")

yielding the same output.

The f-string version is almost as fast as @RomanPekar's solution (python 3.6.4):

df = pd.DataFrame({'col':['a', 0]*200000})

%timeit df['col'].apply(lambda x: f"str{x}")
117 ms ± 451 µs per loop (mean ± std. dev. of 7 runs, 10 loops each)

%timeit 'str' + df['col'].astype(str)
112 ms ± 1.04 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)

Using format, however, is indeed far slower:

%timeit df['col'].apply(lambda x: "{}{}".format('str', x))
185 ms ± 1.07 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)

HTML: Select multiple as dropdown

    <select name="select_box"  multiple>
        <option>123</option>
        <option>456</option>
        <option>789</option>
     </select>

Defining lists as global variables in Python

No, you can specify the list as a keyword argument to your function.

alist = []
def fn(alist=alist):
    alist.append(1)
fn()
print alist    # [1]

I'd say it's bad practice though. Kind of too hackish. If you really need to use a globally available singleton-like data structure, I'd use the module level variable approach, i.e. put 'alist' in a module and then in your other modules import that variable:

In file foomodule.py:

alist = []

In file barmodule.py:

import foomodule
def fn():
    foomodule.alist.append(1)
print foomodule.alist    # [1]

KnockoutJs v2.3.0 : Error You cannot apply bindings multiple times to the same element

Updated Answer

Now that we can use dataFor() to check if the binding has been applied, I would prefer check the data binding, rather than cleanNode() and applyBindings().

Like this:

var koNode = document.getElementById('formEdit');
var hasDataBinding = !!ko.dataFor(koNode);
console.log('has data binding', hasDataBinding);
if (!hasDataBinding) { ko.applyBindings(vm, koNode);}

Original Answer.

A lot of answers already!

First, let's say it is fairly common that we need to do the binding multiple times in a page. Say, I have a form inside the Bootstrap modal, which will be loaded again and again. Many of the form input have two-way binding.

I usually take the easy route: clearing the binding every time before the the binding.

var koNode = document.getElementById('formEdit');
ko.cleanNode(koNode);
ko.applyBindings(vm, koNode);

Just make sure here koNode is required, for, ko.cleanNode() requires a node element, even though we can omit it in ko.applyBinding(vm).

Create local maven repository

If maven is not creating Local Repository i.e .m2/repository folder then try below step.

In your Eclipse\Spring Tool Suite, Go to Window->preferences-> maven->user settings-> click on Restore Defaults-> Apply->Apply and close

Determining if an Object is of primitive type

commons-lang ClassUtils has relevant methods.

The new version has:

boolean isPrimitiveOrWrapped = 
    ClassUtils.isPrimitiveOrWrapper(object.getClass());

The old versions have wrapperToPrimitive(clazz) method, which will return the primitive correspondence.

boolean isPrimitiveOrWrapped = 
    clazz.isPrimitive() || ClassUtils.wrapperToPrimitive(clazz) != null;

Attach Authorization header for all axios requests

Sometimes you get a case where some of the requests made with axios are pointed to endpoints that do not accept authorization headers. Thus, alternative way to set authorization header only on allowed domain is as in the example below. Place the following function in any file that gets executed each time React application runs such as in routes file.

export default () => {
    axios.interceptors.request.use(function (requestConfig) {
        if (requestConfig.url.indexOf(<ALLOWED_DOMAIN>) > -1) {
            const token = localStorage.token;
            requestConfig.headers['Authorization'] = `Bearer ${token}`;
        }

        return requestConfig;
    }, function (error) {
        return Promise.reject(error);
    });

}

Structuring online documentation for a REST API

That's a very complex question for a simple answer.

You may want to take a look at existing API frameworks, like Swagger Specification (OpenAPI), and services like apiary.io and apiblueprint.org.

Also, here's an example of the same REST API described, organized and even styled in three different ways. It may be a good start for you to learn from existing common ways.

At the very top level I think quality REST API docs require at least the following:

  • a list of all your API endpoints (base/relative URLs)
  • corresponding HTTP GET/POST/... method type for each endpoint
  • request/response MIME-type (how to encode params and parse replies)
  • a sample request/response, including HTTP headers
  • type and format specified for all params, including those in the URL, body and headers
  • a brief text description and important notes
  • a short code snippet showing the use of the endpoint in popular web programming languages

Also there are a lot of JSON/XML-based doc frameworks which can parse your API definition or schema and generate a convenient set of docs for you. But the choice for a doc generation system depends on your project, language, development environment and many other things.

SQLSTATE[HY093]: Invalid parameter number: number of bound variables does not match number of tokens on line 102

You didn't bind all your bindings here

$sql = "SELECT SQL_CALC_FOUND_ROWS *, UNIX_TIMESTAMP(publicationDate) AS publicationDate     FROM comments WHERE articleid = :art 
ORDER BY " . mysqli_escape_string($order) . " LIMIT :numRows";

$st = $conn->prepare( $sql );
$st->bindValue( ":art", $art, PDO::PARAM_INT );

You've declared a binding called :numRows but you never actually bind anything to it.

UPDATE 2019: I keep getting upvotes on this and that reminded me of another suggestion

Double quotes are string interpolation in PHP, so if you're going to use variables in a double quotes string, it's pointless to use the concat operator. On the flip side, single quotes are not string interpolation, so if you've only got like one variable at the end of a string it can make sense, or just use it for the whole string.

In fact, there's a micro op available here since the interpreter doesn't care about parsing the string for variables. The boost is nearly unnoticable and totally ignorable on a small scale. However, in a very large application, especially good old legacy monoliths, there can be a noticeable performance increase if strings are used like this. (and IMO, it's easier to read anyway)

Remove duplicates from dataframe, based on two columns A,B, keeping row with max value in another column C

I think groupby should work.

df.groupby(['A', 'B']).max()['C']

If you need a dataframe back you can chain the reset index call.

df.groupby(['A', 'B']).max()['C'].reset_index()

Aligning rotated xticklabels with their respective xticks

An easy, loop-free alternative is to use the horizontalalignment Text property as a keyword argument to xticks[1]. In the below, at the commented line, I've forced the xticks alignment to be "right".

n=5
x = np.arange(n)
y = np.sin(np.linspace(-3,3,n))
xlabels = ['Long ticklabel %i' % i for i in range(n)]
fig, ax = plt.subplots()
ax.plot(x,y, 'o-')

plt.xticks(
        [0,1,2,3,4],
        ["this label extends way past the figure's left boundary",
        "bad motorfinger", "green", "in the age of octopus diplomacy", "x"], 
        rotation=45,
        horizontalalignment="right")    # here
plt.show()

(yticks already aligns the right edge with the tick by default, but for xticks the default appears to be "center".)

[1] You find that described in the xticks documentation if you search for the phrase "Text properties".

In Java, what is the best way to determine the size of an object?

You should use jol, a tool developed as part of the OpenJDK project.

JOL (Java Object Layout) is the tiny toolbox to analyze object layout schemes in JVMs. These tools are using Unsafe, JVMTI, and Serviceability Agent (SA) heavily to decoder the actual object layout, footprint, and references. This makes JOL much more accurate than other tools relying on heap dumps, specification assumptions, etc.

To get the sizes of primitives, references and array elements, use VMSupport.vmDetails(). On Oracle JDK 1.8.0_40 running on 64-bit Windows (used for all following examples), this method returns

Running 64-bit HotSpot VM.
Using compressed oop with 0-bit shift.
Using compressed klass with 3-bit shift.
Objects are 8 bytes aligned.
Field sizes by type: 4, 1, 1, 2, 2, 4, 4, 8, 8 [bytes]
Array element sizes: 4, 1, 1, 2, 2, 4, 4, 8, 8 [bytes]

You can get the shallow size of an object instance using ClassLayout.parseClass(Foo.class).toPrintable() (optionally passing an instance to toPrintable). This is only the space consumed by a single instance of that class; it does not include any other objects referenced by that class. It does include VM overhead for the object header, field alignment and padding. For java.util.regex.Pattern:

java.util.regex.Pattern object internals:
 OFFSET  SIZE        TYPE DESCRIPTION                    VALUE
      0     4             (object header)                01 00 00 00 (0000 0001 0000 0000 0000 0000 0000 0000)
      4     4             (object header)                00 00 00 00 (0000 0000 0000 0000 0000 0000 0000 0000)
      8     4             (object header)                cb cf 00 20 (1100 1011 1100 1111 0000 0000 0010 0000)
     12     4         int Pattern.flags                  0
     16     4         int Pattern.capturingGroupCount    1
     20     4         int Pattern.localCount             0
     24     4         int Pattern.cursor                 48
     28     4         int Pattern.patternLength          0
     32     1     boolean Pattern.compiled               true
     33     1     boolean Pattern.hasSupplementary       false
     34     2             (alignment/padding gap)        N/A
     36     4      String Pattern.pattern                (object)
     40     4      String Pattern.normalizedPattern      (object)
     44     4        Node Pattern.root                   (object)
     48     4        Node Pattern.matchRoot              (object)
     52     4       int[] Pattern.buffer                 null
     56     4         Map Pattern.namedGroups            null
     60     4 GroupHead[] Pattern.groupNodes             null
     64     4       int[] Pattern.temp                   null
     68     4             (loss due to the next object alignment)
Instance size: 72 bytes (reported by Instrumentation API)
Space losses: 2 bytes internal + 4 bytes external = 6 bytes total

You can get a summary view of the deep size of an object instance using GraphLayout.parseInstance(obj).toFootprint(). Of course, some objects in the footprint might be shared (also referenced from other objects), so it is an overapproximation of the space that could be reclaimed when that object is garbage collected. For the result of Pattern.compile("^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\\.[a-zA-Z0-9-.]+$") (taken from this answer), jol reports a total footprint of 1840 bytes, of which only 72 are the Pattern instance itself.

java.util.regex.Pattern instance footprint:
     COUNT       AVG       SUM   DESCRIPTION
         1       112       112   [C
         3       272       816   [Z
         1        24        24   java.lang.String
         1        72        72   java.util.regex.Pattern
         9        24       216   java.util.regex.Pattern$1
        13        24       312   java.util.regex.Pattern$5
         1        16        16   java.util.regex.Pattern$Begin
         3        24        72   java.util.regex.Pattern$BitClass
         3        32        96   java.util.regex.Pattern$Curly
         1        24        24   java.util.regex.Pattern$Dollar
         1        16        16   java.util.regex.Pattern$LastNode
         1        16        16   java.util.regex.Pattern$Node
         2        24        48   java.util.regex.Pattern$Single
        40                1840   (total)

If you instead use GraphLayout.parseInstance(obj).toPrintable(), jol will tell you the address, size, type, value and path of field dereferences to each referenced object, though that's usually too much detail to be useful. For the ongoing pattern example, you might get the following. (Addresses will likely change between runs.)

java.util.regex.Pattern object externals:
          ADDRESS       SIZE TYPE                             PATH                           VALUE
         d5e5f290         16 java.util.regex.Pattern$Node     .root.next.atom.next           (object)
         d5e5f2a0        120 (something else)                 (somewhere else)               (something else)
         d5e5f318         16 java.util.regex.Pattern$LastNode .root.next.next.next.next.next.next.next (object)
         d5e5f328      21664 (something else)                 (somewhere else)               (something else)
         d5e647c8         24 java.lang.String                 .pattern                       (object)
         d5e647e0        112 [C                               .pattern.value                 [^, [, a, -, z, A, -, Z, 0, -, 9, _, ., +, -, ], +, @, [, a, -, z, A, -, Z, 0, -, 9, -, ], +, \, ., [, a, -, z, A, -, Z, 0, -, 9, -, ., ], +, $]
         d5e64850        448 (something else)                 (somewhere else)               (something else)
         d5e64a10         72 java.util.regex.Pattern                                         (object)
         d5e64a58        416 (something else)                 (somewhere else)               (something else)
         d5e64bf8         16 java.util.regex.Pattern$Begin    .root                          (object)
         d5e64c08         24 java.util.regex.Pattern$BitClass .root.next.atom.val$rhs        (object)
         d5e64c20        272 [Z                               .root.next.atom.val$rhs.bits   [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, true, false, true, true, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, true, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false]
         d5e64d30         24 java.util.regex.Pattern$1        .root.next.atom.val$lhs.val$lhs.val$lhs.val$lhs.val$lhs.val$lhs (object)
         d5e64d48         24 java.util.regex.Pattern$1        .root.next.atom.val$lhs.val$lhs.val$lhs.val$lhs.val$lhs.val$rhs (object)
         d5e64d60         24 java.util.regex.Pattern$5        .root.next.atom.val$lhs.val$lhs.val$lhs.val$lhs.val$lhs (object)
         d5e64d78         24 java.util.regex.Pattern$1        .root.next.atom.val$lhs.val$lhs.val$lhs.val$lhs.val$rhs (object)
         d5e64d90         24 java.util.regex.Pattern$5        .root.next.atom.val$lhs.val$lhs.val$lhs.val$lhs (object)
         d5e64da8         24 java.util.regex.Pattern$5        .root.next.atom.val$lhs.val$lhs.val$lhs (object)
         d5e64dc0         24 java.util.regex.Pattern$5        .root.next.atom.val$lhs.val$lhs (object)
         d5e64dd8         24 java.util.regex.Pattern$5        .root.next.atom.val$lhs        (object)
         d5e64df0         24 java.util.regex.Pattern$5        .root.next.atom                (object)
         d5e64e08         32 java.util.regex.Pattern$Curly    .root.next                     (object)
         d5e64e28         24 java.util.regex.Pattern$Single   .root.next.next                (object)
         d5e64e40         24 java.util.regex.Pattern$BitClass .root.next.next.next.atom.val$rhs (object)
         d5e64e58        272 [Z                               .root.next.next.next.atom.val$rhs.bits [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, true, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false]
         d5e64f68         24 java.util.regex.Pattern$1        .root.next.next.next.atom.val$lhs.val$lhs.val$lhs (object)
         d5e64f80         24 java.util.regex.Pattern$1        .root.next.next.next.atom.val$lhs.val$lhs.val$rhs (object)
         d5e64f98         24 java.util.regex.Pattern$5        .root.next.next.next.atom.val$lhs.val$lhs (object)
         d5e64fb0         24 java.util.regex.Pattern$1        .root.next.next.next.atom.val$lhs.val$rhs (object)
         d5e64fc8         24 java.util.regex.Pattern$5        .root.next.next.next.atom.val$lhs (object)
         d5e64fe0         24 java.util.regex.Pattern$5        .root.next.next.next.atom      (object)
         d5e64ff8         32 java.util.regex.Pattern$Curly    .root.next.next.next           (object)
         d5e65018         24 java.util.regex.Pattern$Single   .root.next.next.next.next      (object)
         d5e65030         24 java.util.regex.Pattern$BitClass .root.next.next.next.next.next.atom.val$rhs (object)
         d5e65048        272 [Z                               .root.next.next.next.next.next.atom.val$rhs.bits [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, true, true, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false]
         d5e65158         24 java.util.regex.Pattern$1        .root.next.next.next.next.next.atom.val$lhs.val$lhs.val$lhs.val$lhs (object)
         d5e65170         24 java.util.regex.Pattern$1        .root.next.next.next.next.next.atom.val$lhs.val$lhs.val$lhs.val$rhs (object)
         d5e65188         24 java.util.regex.Pattern$5        .root.next.next.next.next.next.atom.val$lhs.val$lhs.val$lhs (object)
         d5e651a0         24 java.util.regex.Pattern$1        .root.next.next.next.next.next.atom.val$lhs.val$lhs.val$rhs (object)
         d5e651b8         24 java.util.regex.Pattern$5        .root.next.next.next.next.next.atom.val$lhs.val$lhs (object)
         d5e651d0         24 java.util.regex.Pattern$5        .root.next.next.next.next.next.atom.val$lhs (object)
         d5e651e8         24 java.util.regex.Pattern$5        .root.next.next.next.next.next.atom (object)
         d5e65200         32 java.util.regex.Pattern$Curly    .root.next.next.next.next.next (object)
         d5e65220        120 (something else)                 (somewhere else)               (something else)
         d5e65298         24 java.util.regex.Pattern$Dollar   .root.next.next.next.next.next.next (object)

The "(something else)" entries describe other objects in the heap that are not part of this object graph.

The best jol documentation is the jol samples in the jol repository. The samples demonstrate common jol operations and show how you can use jol to analyze VM and garbage collector internals.

Hive load CSV with commas in quoted fields

The problem is that Hive doesn't handle quoted texts. You either need to pre-process the data by changing the delimiter between the fields (e.g: with a Hadoop-streaming job) or you can also give a try to use a custom CSV SerDe which uses OpenCSV to parse the files.

Delete column from pandas DataFrame

The actual question posed, missed by most answers here is:

Why can't I use del df.column_name?

At first we need to understand the problem, which requires us to dive into python magic methods.

As Wes points out in his answer del df['column'] maps to the python magic method df.__delitem__('column') which is implemented in pandas to drop the column

However, as pointed out in the link above about python magic methods:

In fact, __del__ should almost never be used because of the precarious circumstances under which it is called; use it with caution!

You could argue that del df['column_name'] should not be used or encouraged, and thereby del df.column_name should not even be considered.

However, in theory, del df.column_name could be implemeted to work in pandas using the magic method __delattr__. This does however introduce certain problems, problems which the del df['column_name'] implementation already has, but in lesser degree.

Example Problem

What if I define a column in a dataframe called "dtypes" or "columns".

Then assume I want to delete these columns.

del df.dtypes would make the __delattr__ method confused as if it should delete the "dtypes" attribute or the "dtypes" column.

Architectural questions behind this problem

  1. Is a dataframe a collection of columns?
  2. Is a dataframe a collection of rows?
  3. Is a column an attribute of a dataframe?

Pandas answers:

  1. Yes, in all ways
  2. No, but if you want it to be, you can use the .ix, .loc or .iloc methods.
  3. Maybe, do you want to read data? Then yes, unless the name of the attribute is already taken by another attribute belonging to the dataframe. Do you want to modify data? Then no.

TLDR;

You cannot do del df.column_name because pandas has a quite wildly grown architecture that needs to be reconsidered in order for this kind of cognitive dissonance not to occur to its users.

Protip:

Don't use df.column_name, It may be pretty, but it causes cognitive dissonance

Zen of Python quotes that fits in here:

There are multiple ways of deleting a column.

There should be one-- and preferably only one --obvious way to do it.

Columns are sometimes attributes but sometimes not.

Special cases aren't special enough to break the rules.

Does del df.dtypes delete the dtypes attribute or the dtypes column?

In the face of ambiguity, refuse the temptation to guess.

React eslint error missing in props validation

I ran into this issue over the past couple days. Like Omri Aharon said in their answer above, it is important to add definitions for your prop types similar to:

SomeClass.propTypes = {
    someProp: PropTypes.number,
    onTap: PropTypes.func,
};

Don't forget to add the prop definitions outside of your class. I would place it right below/above my class. If you are not sure what your variable type or suffix is for your PropType (ex: PropTypes.number), refer to this npm reference. To Use PropTypes, you must import the package:

import PropTypes from 'prop-types';

If you get the linting error:someProp is not required, but has no corresponding defaultProps declaration all you have to do is either add .isRequired to the end of your prop definition like so:

SomeClass.propTypes = {
    someProp: PropTypes.number.isRequired,
    onTap: PropTypes.func.isRequired,
};

OR add default prop values like so:

SomeClass.defaultProps = {
    someProp: 1
};

If you are anything like me, unexperienced or unfamiliar with reactjs, you may also get this error: Must use destructuring props assignment. To fix this error, define your props before they are used. For example:

const { someProp } = this.props;

How to fix request failed on channel 0

just found out, what was the problem in my case (provider strato): I had the same problem with output "shell request failed on channel 0" in the end.

I have to use the master password with the web-domain name as login. (In German www.wunschname.de, where wunschname is your web-address.)

A ssh login with sftp-user names and the corresponding passwords is without success. (Although scp and sftp works with these sftp users!)

Accessing dict_keys element by index in Python3

Not a full answer but perhaps a useful hint. If it is really the first item you want*, then

next(iter(q))

is much faster than

list(q)[0]

for large dicts, since the whole thing doesn't have to be stored in memory.

For 10.000.000 items I found it to be almost 40.000 times faster.

*The first item in case of a dict being just a pseudo-random item before Python 3.6 (after that it's ordered in the standard implementation, although it's not advised to rely on it).

Problem with SMTP authentication in PHP using PHPMailer, with Pear Mail works

strange issue that i solved by comment this line

//$mail->IsSmtp();

whit the last phpmailer version (5.2)

Does Internet Explorer 8 support HTML 5?

HTML5 is still in draft spec (and will be for a loooong time). Why bother?

Warning: mysqli_query() expects at least 2 parameters, 1 given. What?

The issue is that you're not saving the mysqli connection. Change your connect to:

$aVar = mysqli_connect('localhost','tdoylex1_dork','dorkk','tdoylex1_dork');

And then include it in your query:

$query1 = mysqli_query($aVar, "SELECT name1 FROM users
    ORDER BY RAND()
    LIMIT 1");
$aName1 = mysqli_fetch_assoc($query1);
$name1 = $aName1['name1'];

Also don't forget to enclose your connections variables as strings as I have above. This is what's causing the error but you're using the function wrong, mysqli_query returns a query object but to get the data out of this you need to use something like mysqli_fetch_assoc http://php.net/manual/en/mysqli-result.fetch-assoc.php to actually get the data out into a variable as I have above.

Java - Convert image to Base64

new String(byteArray, 0, bytesRead); does not modify the array. You need to use System.arrayCopy to trim the array to the actual data size. Otherwise you are processing all 102400 bytes most of which are zeros.

What is the best way to iterate over multiple lists at once?

You can use zip:

>>> a = [1, 2, 3]
>>> b = ['a', 'b', 'c']
>>> for x, y in zip(a, b):
...   print x, y
... 
1 a
2 b
3 c

Convert timestamp long to normal date format

Let me propose this solution for you. So in your managed bean, do this

public String convertTime(long time){
    Date date = new Date(time);
    Format format = new SimpleDateFormat("yyyy MM dd HH:mm:ss");
    return format.format(date);
}

so in your JSF page, you can do this (assuming foo is the object that contain your time)

<h:dataTable value="#{myBean.convertTime(myBean.foo.time)}" />

If you have multiple pages that want to utilize this method, you can put this in an abstract class and have your managed bean extend this abstract class.

EDIT: Return time with TimeZone

unfortunately, I think SimpleDateFormat will always format the time in local time, so we can't use SimpleDateFormat anymore. So to display time in different TimeZone, we can do this

public String convertTimeWithTimeZome(long time){
    Calendar cal = Calendar.getInstance();
    cal.setTimeZone(TimeZone.getTimeZone("UTC"));
    cal.setTimeInMillis(time);
    return (cal.get(Calendar.YEAR) + " " + (cal.get(Calendar.MONTH) + 1) + " " 
            + cal.get(Calendar.DAY_OF_MONTH) + " " + cal.get(Calendar.HOUR_OF_DAY) + ":"
            + cal.get(Calendar.MINUTE));

}

A better solution is to utilize JodaTime. In my opinion, this API is much better than Calendar (lighter weight, faster and provide more functionality). Plus Calendar.Month of January is 0, that force developer to add 1 to the result, and you have to format the time yourself. Using JodaTime, you can fix all of that. Correct me if I am wrong, but I think JodaTime is incorporated in JDK7

using sql count in a case statement

ok. I solved it

SELECT `smart_projects`.project_id, `smart_projects`.business_id, `smart_projects`.title,
 `page_pages`.`funnel_id` as `funnel_id`, count(distinct(page_pages.page_id) )as page_count, count(distinct (CASE WHEN page_pages.funnel_id != 0 then  page_pages.funnel_id ELSE NULL END ) ) as funnel_count
FROM `smart_projects`
LEFT JOIN `page_pages` ON `smart_projects`.`project_id` = `page_pages`.`project_id`
WHERE  smart_projects.status !=  0 
AND `smart_projects`.`business_id` = 'cd9412774edb11e9'
GROUP BY `smart_projects`.`project_id`
ORDER BY `title` DESC

How to get form values in Symfony2 controller

In Symfony 2 ( to be more specific, the 2.3 version ) you can get a data of an field by

$var = $form->get('yourformfieldname')->getData();

or you can get all data sent

$data = $form->getData();

where '$data' is an array containing your form fields' values.

How do I jump to a closing bracket in Visual Studio Code?

Mac Cmd+Shift+\

  • Mac with french keyboard : Ctrl+Cmd+Option+Shift+L

Windows Ctrl+Shift+\

  • Windows with spanish keyboard Ctrl+Shift+|

  • Windows with german keyboard Ctrl+Shift+^


Alternatively, you can do:

Ctrl+Shift+p

And select

Preferences: Open Keyboard Shortcuts

There you will be able to see all the shortcuts, and create your own.

How to split a list by comma not space

kent$  echo "Hello,World,Questions,Answers,bash shell,script"|awk -F, '{for (i=1;i<=NF;i++)print $i}'
Hello
World
Questions
Answers
bash shell
script

What data type to use in MySQL to store images?

Perfect answer for your question can be found on MYSQL site itself.refer their manual(without using PHP)

http://forums.mysql.com/read.php?20,17671,27914

According to them use LONGBLOB datatype. with that you can only store images less than 1MB only by default,although it can be changed by editing server config file.i would also recommend using MySQL workBench for ease of database management

How can I add a variable to console.log?

Both console.log("story" + name + "story") and console.log("story", name, "story") works just fine as mentioned in earlier answers.

I will still suggest of having a habit of console.log("story", name, "story"), because, if trying to print the object contents, like json object, having "story" + objectVariable + "story" will convert it into string.

This will have output like : "story" [object Object] "story".

Just a good practice.

How to get sp_executesql result into a variable?

Return values are generally not used to "return" a result but to return success (0) or an error number (1-65K). The above all seem to indicate that sp_executesql does not return a value, which is not correct. sp_executesql will return 0 for success and any other number for failure.

In the below, @i will return 2727

DECLARE @s NVARCHAR(500)
DECLARE @i INT;
SET @s = 'USE [Blah]; UPDATE STATISTICS [dbo].[TableName] [NonExistantStatisticsName];';
EXEC @i = sys.sp_executesql @s
SELECT @i AS 'Blah'

SSMS will show this Msg 2727, Level 11, State 1, Line 1 Cannot find index 'NonExistantStaticsName'.

Java, reading a file from current directory?

Try

System.getProperty("user.dir")

It returns the current working directory.

Insert results of a stored procedure into a temporary table

In SQL Server 2005 you can use INSERT INTO ... EXEC to insert the result of a stored procedure into a table. From MSDN's INSERT documentation (for SQL Server 2000, in fact):

--INSERT...EXECUTE procedure example
INSERT author_sales EXECUTE get_author_sales

ORA-12154: TNS:could not resolve the connect identifier specified (PLSQL Developer)

As I can't add a comment, just thought I'd post this for completion. tufy's answer is correct, it's to do with parenthesis (brackets) in the path to the application being run.

There is an existing networking bug where the networking layer is unable to parse program locations that contain parenthesis in the path to the executable which is attempting to connect to Oracle.

Filed with Oracle, Bug 3807408 refers.

Source

java.lang.UnsupportedClassVersionError Unsupported major.minor version 51.0

I encountered the same issue, when jdk 1.7 was used to compile then jre 1.4 was used for execution.

My solution was to set environment variable PATH by adding pathname C:\glassfish3\jdk7\bin in front of the existing PATH setting. The updated value is "C:\glassfish3\jdk7\bin;C:\Sun\SDK\bin". After the update, the problem was gone.

How to use *ngIf else?

ngif expression resulting value won’t just be the boolean true or false

if the expression is just a object, it still evaluate it as truthiness.

if the object is undefined, or non-exist, then ngif will evaluate it as falseness.

common use is if an object loaded, exist, then display the content of this object, otherwise display "loading.......".

 <div *ngIf="!object">
     Still loading...........
 </div>

<div *ngIf="object">
     <!-- the content of this object -->

           object.info, object.id, object.name ... etc.
 </div>

another example:

  things = {
 car: 'Honda',
 shoes: 'Nike',
 shirt: 'Tom Ford',
 watch: 'Timex'
 };

 <div *ngIf="things.car; else noCar">
  Nice car!
 </div>

<ng-template #noCar>
   Call a Uber.
</ng-template>

 <!-- Nice car ! -->

anthoer example:

<div *ngIf="things.car; let car">
   Nice {{ car }}!
 </div>
<!-- Nice Honda! -->

ngif template

ngif angular 4

How to convert Blob to String and String to Blob in java

And here is my solution, that always works for me

StringBuffer buf = new StringBuffer();
String temp;
BufferedReader bufReader = new BufferedReader(new InputStreamReader(myBlob.getBinaryStream()));
    while ((temp=bufReader.readLine())!=null) {
        bufappend(temp);
    }

Convert Xml to Table SQL Server

This is the answer, hope it helps someone :)

First there are two variations on how the xml can be written:

1

<row>
    <IdInvernadero>8</IdInvernadero>
    <IdProducto>3</IdProducto>
    <IdCaracteristica1>8</IdCaracteristica1>
    <IdCaracteristica2>8</IdCaracteristica2>
    <Cantidad>25</Cantidad>
    <Folio>4568457</Folio>
</row>
<row>
    <IdInvernadero>3</IdInvernadero>
    <IdProducto>3</IdProducto>
    <IdCaracteristica1>1</IdCaracteristica1>
    <IdCaracteristica2>2</IdCaracteristica2>
    <Cantidad>72</Cantidad>
    <Folio>4568457</Folio>
</row>

Answer:

SELECT  
       Tbl.Col.value('IdInvernadero[1]', 'smallint'),  
       Tbl.Col.value('IdProducto[1]', 'smallint'),  
       Tbl.Col.value('IdCaracteristica1[1]', 'smallint'),
       Tbl.Col.value('IdCaracteristica2[1]', 'smallint'),
       Tbl.Col.value('Cantidad[1]', 'int'),
       Tbl.Col.value('Folio[1]', 'varchar(7)')
FROM   @xml.nodes('//row') Tbl(Col)  

2.

<row IdInvernadero="8" IdProducto="3" IdCaracteristica1="8" IdCaracteristica2="8" Cantidad ="25" Folio="4568457" />                         
<row IdInvernadero="3" IdProducto="3" IdCaracteristica1="1" IdCaracteristica2="2" Cantidad ="72" Folio="4568457" />

Answer:

SELECT  
       Tbl.Col.value('@IdInvernadero', 'smallint'),  
       Tbl.Col.value('@IdProducto', 'smallint'),  
       Tbl.Col.value('@IdCaracteristica1', 'smallint'),
       Tbl.Col.value('@IdCaracteristica2', 'smallint'),
       Tbl.Col.value('@Cantidad', 'int'),
       Tbl.Col.value('@Folio', 'varchar(7)')

FROM   @xml.nodes('//row') Tbl(Col)

Taken from:

  1. http://kennyshu.blogspot.com/2007/12/convert-xml-file-to-table-in-sql-2005.html

  2. http://msdn.microsoft.com/en-us/library/ms345117(SQL.90).aspx

Matplotlib different size subplots

Another way is to use the subplots function and pass the width ratio with gridspec_kw:

import numpy as np
import matplotlib.pyplot as plt 

# generate some data
x = np.arange(0, 10, 0.2)
y = np.sin(x)

# plot it
f, (a0, a1) = plt.subplots(1, 2, gridspec_kw={'width_ratios': [3, 1]})
a0.plot(x, y)
a1.plot(y, x)

f.tight_layout()
f.savefig('grid_figure.pdf')

How does facebook, gmail send the real time notification?

According to a slideshow about Facebook's Messaging system, Facebook uses the comet technology to "push" message to web browsers. Facebook's comet server is built on the open sourced Erlang web server mochiweb.

In the picture below, the phrase "channel clusters" means "comet servers".

System overview

Many other big web sites build their own comet server, because there are differences between every company's need. But build your own comet server on a open source comet server is a good approach.

You can try icomet, a C1000K C++ comet server built with libevent. icomet also provides a JavaScript library, it is easy to use as simple as:

var comet = new iComet({
    sign_url: 'http://' + app_host + '/sign?obj=' + obj,
    sub_url: 'http://' + icomet_host + '/sub',
    callback: function(msg){
        // on server push
        alert(msg.content);
    }
});

icomet supports a wide range of Browsers and OSes, including Safari(iOS, Mac), IEs(Windows), Firefox, Chrome, etc.

ArrayBuffer to base64 encoded string

var blob = new Blob([arrayBuffer])

var reader = new FileReader();
reader.onload = function(event){
   var base64 =   event.target.result
};

reader.readAsDataURL(blob);

The container 'Maven Dependencies' references non existing library - STS

Today I had this same problem with another jar. I tried multiple things people said on Stackoverflow, but nothing worked. Eventually I did this:

  1. Close eclipse and any project-app that is running.
  2. Delete the .m2 folder (Users --> [your_username] --> .m2). It's an invisible folder, make sure you are able to view invisible folders.
  3. Restarted Eclipse (I guess it works in other IDE too) and updated my project.

Now it works again for me. Perhaps this solves the problem for someone else too.

How to loop through files matching wildcard in batch file

The code below filters filenames starting with given substring. It could be changed to fit different needs by working on subfname substring extraction and IF statement:

echo off
rem filter all files not starting with the prefix 'dat'
setlocal enabledelayedexpansion
FOR /R your-folder-fullpath %%F IN (*.*) DO (
set fname=%%~nF
set subfname=!fname:~0,3!
IF NOT "!subfname!" == "dat" echo "%%F"
)
pause

Simulate limited bandwidth from within Chrome?

Original article: https://helpdeskgeek.com/networking/simulate-slow-internet-connection-testing/

Simulate Slow Connection using Chrome Go ahead and install Chrome if you don’t already have it installed on your system. Once you do, open a new tab and then press CTRL + SHIFT + I to open the developer tools window or click on the hamburger icon, then More tools and then Developer tools.

enter image description here

This will bring up the Developer Tools window, which will probably be docked on the right side of the screen. I prefer it docked at the bottom of the screen since you can see more data. To do this, click on the three vertical dots and then click on the middle dock position.

enter image description here

Now go ahead and click on the Network tab. On the right, you should see a label called No Throttling.

enter image description here

If you click on that, you’ll get a dropdown list of a pre-configured speed that you can use to simulate a slow connection.

enter image description here

The choices range from Offline to WiFi and the numbers are shown as Latency, Download, Upload. The slowest is GPRS followed by Regular 2G, then Good 2G, then Regular 3G, Good 3G, Regular 4G, DSL and then WiFi. Pick one of the options and then reload the page you are on or type in another URL in the address bar. Just make sure you are in the same tab where the developer tools are being displayed. The throttling only works for the tab you have it enabled for.

If you want to use your own specific values, you can click the Add button under Custom. Click on the Add Custom Profile button to add a new profile.

enter image description here

When using GPRS, it took www.google.com a whopping 16 seconds to load! Overall, this is a great tool that is built right into Chrome that you can use for testing your website load time on slower connections. If you have any questions, feel free to comment. Enjoy!

JavaScript "cannot read property "bar" of undefined

Just check for it before you pass to your function. So you would pass:

thing.foo ? thing.foo.bar : undefined

How can I create 2 separate log files with one log4j config file?

Try the following configuration:

log4j.rootLogger=TRACE, stdout

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d [%24F:%t:%L] - %m%n

log4j.appender.debugLog=org.apache.log4j.FileAppender
log4j.appender.debugLog.File=logs/debug.log
log4j.appender.debugLog.layout=org.apache.log4j.PatternLayout
log4j.appender.debugLog.layout.ConversionPattern=%d [%24F:%t:%L] - %m%n

log4j.appender.reportsLog=org.apache.log4j.FileAppender
log4j.appender.reportsLog.File=logs/reports.log
log4j.appender.reportsLog.layout=org.apache.log4j.PatternLayout
log4j.appender.reportsLog.layout.ConversionPattern=%d [%24F:%t:%L] - %m%n

log4j.category.debugLogger=TRACE, debugLog
log4j.additivity.debugLogger=false

log4j.category.reportsLogger=DEBUG, reportsLog
log4j.additivity.reportsLogger=false

Then configure the loggers in the Java code accordingly:

static final Logger debugLog = Logger.getLogger("debugLogger");
static final Logger resultLog = Logger.getLogger("reportsLogger");

Do you want output to go to stdout? If not, change the first line of log4j.properties to:

log4j.rootLogger=OFF

and get rid of the stdout lines.

Forward declaration of a typedef in C++

For those of you like me, who are looking to forward declare a C-style struct that was defined using typedef, in some c++ code, I have found a solution that goes as follows...

// a.h
 typedef struct _bah {
    int a;
    int b;
 } bah;

// b.h
 struct _bah;
 typedef _bah bah;

 class foo {
   foo(bah * b);
   foo(bah b);
   bah * mBah;
 };

// b.cpp
 #include "b.h"
 #include "a.h"

 foo::foo(bah * b) {
   mBah = b;
 }

 foo::foo(bah b) {
   mBah = &b;
 }

Object comparison in JavaScript

Here is my ES3 commented solution (gory details after the code):

function object_equals( x, y ) {
  if ( x === y ) return true;
    // if both x and y are null or undefined and exactly the same

  if ( ! ( x instanceof Object ) || ! ( y instanceof Object ) ) return false;
    // if they are not strictly equal, they both need to be Objects

  if ( x.constructor !== y.constructor ) return false;
    // they must have the exact same prototype chain, the closest we can do is
    // test there constructor.

  for ( var p in x ) {
    if ( ! x.hasOwnProperty( p ) ) continue;
      // other properties were tested using x.constructor === y.constructor

    if ( ! y.hasOwnProperty( p ) ) return false;
      // allows to compare x[ p ] and y[ p ] when set to undefined

    if ( x[ p ] === y[ p ] ) continue;
      // if they have the same strict value or identity then they are equal

    if ( typeof( x[ p ] ) !== "object" ) return false;
      // Numbers, Strings, Functions, Booleans must be strictly equal

    if ( ! object_equals( x[ p ],  y[ p ] ) ) return false;
      // Objects and Arrays must be tested recursively
  }

  for ( p in y )
    if ( y.hasOwnProperty( p ) && ! x.hasOwnProperty( p ) )
      return false;
        // allows x[ p ] to be set to undefined

  return true;
}

In developing this solution, I took a particular look at corner cases, efficiency, yet trying to yield a simple solution that works, hopefully with some elegance. JavaScript allows both null and undefined properties and objects have prototypes chains that can lead to very different behaviors if not checked.

First I have chosen to not extend Object.prototype, mostly because null could not be one of the objects of the comparison and that I believe that null should be a valid object to compare with another. There are also other legitimate concerns noted by others regarding the extension of Object.prototype regarding possible side effects on other's code.

Special care must taken to deal the possibility that JavaScript allows object properties can be set to undefined, i.e. there exists properties which values are set to undefined. The above solution verifies that both objects have the same properties set to undefined to report equality. This can only be accomplished by checking the existence of properties using Object.hasOwnProperty( property_name ). Also note that JSON.stringify() removes properties that are set to undefined, and that therefore comparisons using this form will ignore properties set to the value undefined.

Functions should be considered equal only if they share the same reference, not just the same code, because this would not take into account these functions prototype. So comparing the code string does not work to guaranty that they have the same prototype object.

The two objects should have the same prototype chain, not just the same properties. This can only be tested cross-browser by comparing the constructor of both objects for strict equality. ECMAScript 5 would allow to test their actual prototype using Object.getPrototypeOf(). Some web browsers also offer a __proto__ property that does the same thing. A possible improvement of the above code would allow to use one of these methods whenever available.

The use of strict comparisons is paramount here because 2 should not be considered equal to "2.0000", nor false should be considered equal to null, undefined, or 0.

Efficiency considerations lead me to compare for equality of properties as soon as possible. Then, only if that failed, look for the typeof these properties. The speed boost could be significant on large objects with lots of scalar properties.

No more that two loops are required, the first to check properties from the left object, the second to check properties from the right and verify only existence (not value), to catch these properties which are defined with the undefined value.

Overall this code handles most corner cases in only 16 lines of code (without comments).


Update (8/13/2015). I have implemented a better version, as the function value_equals() that is faster, handles properly corner cases such as NaN and 0 different than -0, optionally enforcing objects' properties order and testing for cyclic references, backed by more than 100 automated tests as part of the Toubkal project test suite.

How can I pretty-print JSON using node.js?

JSON.stringify's third parameter defines white-space insertion for pretty-printing. It can be a string or a number (number of spaces). Node can write to your filesystem with fs. Example:

var fs = require('fs');

fs.writeFile('test.json', JSON.stringify({ a:1, b:2, c:3 }, null, 4));
/* test.json:
{
     "a": 1,
     "b": 2,
     "c": 3,
}
*/

See the JSON.stringify() docs at MDN, Node fs docs

Git: How to pull a single file from a server repository in Git?

This scenario comes up when you -- or forces greater than you -- have mangled a file in your local repo and you just want to restore a fresh copy of the latest version of it from the repo. Simply deleting the file with /bin/rm (not git rm) or renaming/hiding it and then issuing a git pull will not work: git notices the file's absence and assumes you probably want it gone from the repo (git diff will show all lines deleted from the missing file).

git pull not restoring locally missing files has always frustrated me about git, perhaps since I have been influenced by other version control systems (e.g. svn update which I believe will restore files that have been locally hidden).

git reset --hard HEAD is an alternative way to restore the file of interest as it throws away any uncommitted changes you have. However, as noted here, git reset is is a potentially dangerous command if you have any other uncommitted changes that you care about.

The git fetch ... git checkout strategy noted above by @chrismillah is a nice surgical way to restore the file in question.

How to open local files in Swagger-UI

Instead of opening swagger ui as a file - you put into browser file:///D:/swagger-ui/dist/index.html you can: create iis virtual directory which enables browsing and points to D:/swagger-ui

  1. open mmc, add iis services, expand Default Web Site add virtual directory, put alias: swagger-ui, physical path:(your path...) D:/swagger-ui
  2. in mmc in the middle pane double click on "directory browsing"
  3. in mmc in the right pane click "enable"
  4. after that in browser put url to open your local swagger-ui http://localhost/swagger-ui/dist/
  5. now you can use ../my.json if you copied file into dist folder or you can created separate forlder for samples, say D:/swagger-ui/samples and use ../samples/my.json or http://localhost/swagger-ui/samples/my.json

Java 8 lambdas, Function.identity() or t->t

From the JDK source:

static <T> Function<T, T> identity() {
    return t -> t;
}

So, no, as long as it is syntactically correct.

multiple classes on single element html

It's a good practice if you need them. It's also a good practice is they make sense, so future coders can understand what you're doing.

But generally, no it's not a good practice to attach 10 class names to an object because most likely whatever you're using them for, you could accomplish the same thing with far fewer classes. Probably just 1 or 2.

To qualify that statement, javascript plugins and scripts may append far more classnames to do whatever it is they're going to do. Modernizr for example appends anywhere from 5 - 25 classes to your body tag, and there's a very good reason for it. jQuery UI appends lots of classnames when you use one of the widgets in that library.

What is duck typing?

I try to understand the famous sentence in my way: "Python dose not care an object is a real duck or not. All it cares is whether the object, first 'quack', second 'like a duck'."

There is a good website. http://www.voidspace.org.uk/python/articles/duck_typing.shtml#id14

The author pointed that duck typing let you create your own classes that have their own internal data structure - but are accessed using normal Python syntax.

multiprocessing: How do I share a dict among multiple processes?

Maybe you can try pyshmht, sharing memory based hash table extension for Python.

Notice

  1. It's not fully tested, just for your reference.

  2. It currently lacks lock/sem mechanisms for multiprocessing.

How can I determine whether a 2D Point is within a Polygon?

David Segond's answer is pretty much the standard general answer, and Richard T's is the most common optimization, though therre are some others. Other strong optimizations are based on less general solutions. For example if you are going to check the same polygon with lots of points, triangulating the polygon can speed things up hugely as there are a number of very fast TIN searching algorithms. Another is if the polygon and points are on a limited plane at low resolution, say a screen display, you can paint the polygon onto a memory mapped display buffer in a given colour, and check the color of a given pixel to see if it lies in the polygons.

Like many optimizations, these are based on specific rather than general cases, and yield beneifits based on amortized time rather than single usage.

Working in this field, i found Joeseph O'Rourkes 'Computation Geometry in C' ISBN 0-521-44034-3 to be a great help.

Runnable with a parameter?

I would first want to know what you are trying to accomplish here to need an argument to be passed to new Runnable() or to run(). The usual way should be to have a Runnable object which passes data(str) to its threads by setting member variables before starting. The run() method then uses these member variable values to do execute someFunc()

How to reverse an animation on mouse out after hover

lol, it has a very easy solution with CSS only. Here you go

#thing { padding: 10px; border-radius: 5px;

/* HOVER OFF */ -webkit-transition: padding 2s; }

#thing:hover { padding: 20px; border-radius: 15px;

/* HOVER ON */ -webkit-transition: border-radius 2s; }

How do browser cookie domains work?

I tested all the cases in the latest Chrome, Firefox, Safari in 2019.

Response to Added:

  • Will a cookie for .example.com be available for www.example.com? YES
  • Will a cookie for .example.com be available for example.com? YES
  • Will a cookie for example.com be available for www.example.com? NO, Domain without wildcard only matches itself.
  • Will a cookie for example.com be available for anotherexample.com? NO
  • Will www.example.com be able to set cookie for example.com? NO, it will be able to set cookie for '.example.com', but not 'example.com'.
  • Will www.example.com be able to set cookie for www2.example.com? NO. But it can set cookie for .example.com, which www2.example.com can access.
  • Will www.example.com be able to set cookie for .com? NO

How do I drop a function if it already exists?

From SQL Server 2016 CTP3 you can use new DIE statements instead of big IF wrappers

Syntax :

DROP FUNCTION [ IF EXISTS ] { [ schema_name. ] function_name } [ ,...n ]

Query:

DROP Function IF EXISTS udf_name

More info here

Possible to view PHP code of a website?

A bug or security vulnerability in the server (either Apache or the PHP engine), or your own PHP code, might allow an attacker to obtain access to your code.

For instance if you have a PHP script to allow people to download files, and an attacker can trick this script into download some of your PHP files, then your code can be leaked.

Since it's impossible to eliminate all bugs from the software you're using, if someone really wants to steal your code, and they have enough resources, there's a reasonable chance they'll be able to.

However, as long as you keep your server up-to-date, someone with casual interest is not able to see the PHP source unless there are some obvious security vulnerabilities in your code.

Read the Security section of the PHP manual as a starting point to keeping your code safe.

How to test if string exists in file with Bash?

grep -E "(string)" /path/to/file || echo "no match found"

-E option makes grep use regular expressions

Is there a CSS selector for text nodes?

Text nodes cannot have margins or any other style applied to them, so anything you need style applied to must be in an element. If you want some of the text inside of your element to be styled differently, wrap it in a span or div, for example.

Owl Carousel Won't Autoplay

add this

owl.trigger('owl.play',6000);

Inline elements shifting when made bold on hover

I fixed menu when hover bold success. It support responsive, this is my code:

(function ($) {
'use strict';

$(document).ready(function () {
    customWidthMenu();
});
$(window).resize(function () {
    customWidthMenu();
});
function customWidthMenu() {
    $('ul.nav li a').each(function() {
        $(this).removeAttr('style');
        var this = $(this);
        var width = this.innerWidth();
        this.css({'width': width + 12});
    });
}})(jQuery);

Delete last char of string

There is no "quick-and-dirty" way of doing this. I usually do:

mystring= string.Concat(mystring.Take(mystring.Length-1));

Determine installed PowerShell version

The below cmdlet will return the PowerShell version.

$PSVersionTable.PSVersion.Major

How to sum a list of integers with java streams?

Most of the aspects are covered. But there could be a requirement to find the aggregation of other data types apart from Integer, Long(for which specialized stream support is already present). For e.g. stram with BigInteger For such a type we can use reduce operation like

list.stream().reduce((bigInteger1, bigInteger2) -> bigInteger1.add(bigInteger2))

Node.js/Express.js App Only Works on Port 3000

Noticed this was never resolved... You likely have a firewall in front of your machine blocking those ports, or iptables is set up to prevent the use of those ports.

Try running nmap -F localhost when you run your app (install nmap if you don't have it). If it appears that you're running the app on the correct port and you can't access it via a remote browser then there is some middleware or a physical firewall that's blocking the port.

Hope this helps!

How prevent CPU usage 100% because of worker process in iis

I was facing the same issues recently and found a solution which worked for me and reduced the memory consumption level upto a great extent.

Solution:

First of all find the application which is causing heavy memory usage.

You can find this in the Details section of the Task Manager.

Next.

  1. Open the IIS manager.
  2. Click on Application Pools. You'll find many application pools which your system is using.
  3. Now from the task manager you've found which application is causing the heavy memory consumption. There would be multiple options for that and you need to select the one which is having '1' in it's Application column of your web application.
  4. When you click on the application pool on the right hand side you'll see an option Advance settings under Edit Application pools. Go to Advanced Settings. 5.Now under General category set the Enable 32-bit Applications to True
  5. Restart the IIS server or you can see the consumption goes down in performance section of your Task Manager.

If this solution works for you please add a comment so that I can know.

Convert string to datetime in vb.net

As an alternative, if you put a space between the date and time, DateTime.Parse will recognize the format for you. That's about as simple as you can get it. (If ParseExact was still not being recognized)

Disable mouse scroll wheel zoom on embedded Google Maps

Well, for me the best solution was to simply use like this:

HTML:

<div id="google-maps">
<iframe frameborder="0" height="450" src="***embed-map***"  width="100"</iframe>
</div>

CSS:

#google-maps iframe { pointer-events:none; }

JS:

<script>
  $(function() {
    $('#google-maps').click(function(e) {
        $(this).find('iframe').css('pointer-events', 'auto');
    }).mouseleave(function(e) {
        $(this).find('iframe').css('pointer-events', 'none');
    });
  })
</script>

RESULT

Considerations:

The best would be to add an overlay with a darker transparency with a text: "Click to browse" when mouse wheel is deactivated But when it is activated (after you click on it) then the transparency with text would disappear and the user could browse the map as expected. Any clues how to do that?

What is an idempotent operation?

my 5c: In integration and networking the idempotency is very important. Several examples from real-life: Imagine, we deliver data to the target system. Data delivered by a sequence of messages. 1. What would happen if the sequence is mixed in channel? (As network packages always do :) ). If the target system is idempotent, the result will not be different. If the target system depends of the right order in the sequence, we have to implement resequencer on the target site, which would restore the right order. 2. What would happen if there are the message duplicates? If the channel of target system does not acknowledge timely, the source system (or channel itself) usually sends another copy of the message. As a result we can have duplicate message on the target system side. If the target system is idempotent, it takes care of it and result will not be different. If the target system is not idempotent, we have to implement deduplicator on the target system side of the channel.

How to validate Google reCAPTCHA v3 on server side?

Here you have simple example. Just remember to provide secretKey and siteKey from google api.

<?php
$siteKey = 'Provide element from google';
$secretKey = 'Provide element from google';

if($_POST['submit']){
    $username = $_POST['username'];
    $responseKey = $_POST['g-recaptcha-response'];
    $userIP = $_SERVER['REMOTE_ADDR'];
    $url = "https://www.google.com/recaptcha/api/siteverify?secret=$secretKey&response=$responseKey&remoteip=$userIP";
    $response = file_get_contents($url);
    $response = json_decode($response);
    if($response->success){
        echo "Verification is correct. Your name is $username";
    } else {
        echo "Verification failed";
    }
} ?>

<html>
<meta>
    <title>Google ReCaptcha</title>
</meta>
<body>
    <form action="index.php" method="post">
        <input type="text" name="username" placeholder="Write your name"/>
        <div class="g-recaptcha" data-sitekey="<?= $siteKey ?>"></div>
        <input type="submit" name="submit" value="send"/>
    </form>
    <script src='https://www.google.com/recaptcha/api.js'></script>
</body>

What is an "index out of range" exception, and how do I fix it?

Why does this error occur?

Because you tried to access an element in a collection, using a numeric index that exceeds the collection's boundaries.

The first element in a collection is generally located at index 0. The last element is at index n-1, where n is the Size of the collection (the number of elements it contains). If you attempt to use a negative number as an index, or a number that is larger than Size-1, you're going to get an error.

How indexing arrays works

When you declare an array like this:

var array = new int[6]

The first and last elements in the array are

var firstElement = array[0];
var lastElement = array[5];

So when you write:

var element = array[5];

you are retrieving the sixth element in the array, not the fifth one.

Typically, you would loop over an array like this:

for (int index = 0; index < array.Length; index++)
{
    Console.WriteLine(array[index]);
}

This works, because the loop starts at zero, and ends at Length-1 because index is no longer less than Length.

This, however, will throw an exception:

for (int index = 0; index <= array.Length; index++)
{
    Console.WriteLine(array[index]);
}

Notice the <= there? index will now be out of range in the last loop iteration, because the loop thinks that Length is a valid index, but it is not.

How other collections work

Lists work the same way, except that you generally use Count instead of Length. They still start at zero, and end at Count - 1.

for (int index = 0; i < list.Count; index++)
{
    Console.WriteLine(list[index]);
} 

However, you can also iterate through a list using foreach, avoiding the whole problem of indexing entirely:

foreach (var element in list)
{
    Console.WriteLine(element.ToString());
}

You cannot index an element that hasn't been added to a collection yet.

var list = new List<string>();
list.Add("Zero");
list.Add("One");
list.Add("Two");
Console.WriteLine(list[3]);  // Throws exception.

mysql error 1364 Field doesn't have a default values

This is caused by the STRICT_TRANS_TABLES SQL mode defined in the

%PROGRAMDATA%\MySQL\MySQL Server 5.6\my.ini

file. Removing that setting and restarting MySQL should fix the problem.

See https://www.farbeyondcode.com/Solution-for-MariaDB-Field--xxx--doesn-t-have-a-default-value-5-2720.html

If editing that file doesn't fix the issue, see http://dev.mysql.com/doc/refman/5.6/en/option-files.html for other possible locations of config files.

HEAD and ORIG_HEAD in Git

From git reset

"pull" or "merge" always leaves the original tip of the current branch in ORIG_HEAD.

git reset --hard ORIG_HEAD

Resetting hard to it brings your index file and the working tree back to that state, and resets the tip of the branch to that commit.

git reset --merge ORIG_HEAD

After inspecting the result of the merge, you may find that the change in the other branch is unsatisfactory. Running "git reset --hard ORIG_HEAD" will let you go back to where you were, but it will discard your local changes, which you do not want. "git reset --merge" keeps your local changes.


Before any patches are applied, ORIG_HEAD is set to the tip of the current branch.
This is useful if you have problems with multiple commits, like running 'git am' on the wrong branch or an error in the commits that is more easily fixed by changing the mailbox (e.g. +errors in the "From:" lines).

In addition, merge always sets '.git/ORIG_HEAD' to the original state of HEAD so a problematic merge can be removed by using 'git reset ORIG_HEAD'.


Note: from here

HEAD is a moving pointer. Sometimes it means the current branch, sometimes it doesn't.

So HEAD is NOT a synonym for "current branch" everywhere already.

HEAD means "current" everywhere in git, but it does not necessarily mean "current branch" (i.e. detached HEAD).

But it almost always means the "current commit".
It is the commit "git commit" builds on top of, and "git diff --cached" and "git status" compare against.
It means the current branch only in very limited contexts (exactly when we want a branch name to operate on --- resetting and growing the branch tip via commit/rebase/etc.).

Reflog is a vehicle to go back in time and time machines have interesting interaction with the notion of "current".

HEAD@{5.minutes.ago} could mean "dereference HEAD symref to find out what branch we are on RIGHT NOW, and then find out where the tip of that branch was 5 minutes ago".
Alternatively it could mean "what is the commit I would have referred to as HEAD 5 minutes ago, e.g. if I did "git show HEAD" back then".


git1.8.4 (July 2013) introduces introduced a new notation!
(Actually, it will be for 1.8.5, Q4 2013: reintroduced with commit 9ba89f4), by Felipe Contreras.

Instead of typing four capital letters "HEAD", you can say "@" now,
e.g. "git log @".

See commit cdfd948

Typing 'HEAD' is tedious, especially when we can use '@' instead.

The reason for choosing '@' is that it follows naturally from the ref@op syntax (e.g. HEAD@{u}), except we have no ref, and no operation, and when we don't have those, it makes sens to assume 'HEAD'.

So now we can use 'git show @~1', and all that goody goodness.

Until now '@' was a valid name, but it conflicts with this idea, so let's make it invalid. Probably very few people, if any, used this name.

How to send string from one activity to another?

Say there is EditText et1 in ur MainActivity and u wanna pass this to SecondActivity

String s=et1.getText().toString();
Bundle basket= new Bundle();
basket.putString("abc", s);
Intent a=new Intent(MainActivity.this,SecondActivity.class);
a.putExtras(basket);
startActivity(a);

now in Second Activity, say u wanna put the string passed from EditText et1 to TextView txt1 of SecondActivity

Bundle gt=getIntent().getExtras();
str=gt.getString("abc");
txt1.setText(str);

Using NOT operator in IF conditions

try like this

if (!(a | b)) {
    //blahblah
}

It's same with

if (a | b) {}
else {
    // blahblah
}

Stop handler.postDelayed()

You can use:

 Handler handler = new Handler()
 handler.postDelayed(new Runnable())

Or you can use:

 handler.removeCallbacksAndMessages(null);

Docs

public final void removeCallbacksAndMessages (Object token)

Added in API level 1 Remove any pending posts of callbacks and sent messages whose obj is token. If token is null, all callbacks and messages will be removed.

Or you could also do like the following:

Handler handler =  new Handler()
Runnable myRunnable = new Runnable() {
public void run() {
    // do something
}
};
handler.postDelayed(myRunnable,zeit_dauer2);

Then:

handler.removeCallbacks(myRunnable);

Docs

public final void removeCallbacks (Runnable r)

Added in API level 1 Remove any pending posts of Runnable r that are in the message queue.

public final void removeCallbacks (Runnable r, Object token)

Edit:

Change this:

@Override
public void onClick(View v) {
    Handler handler =  new Handler();
    Runnable myRunnable = new Runnable() {

To:

@Override
public void onClick(View v) {
    handler = new Handler();
    myRunnable = new Runnable() { /* ... */}

Because you have the below. Declared before onCreate but you re-declared and then initialized it in onClick leading to a NPE.

Handler handler; // declared before onCreate
Runnable myRunnable;

How to identify server IP address in PHP

Like this for the server ip:

$_SERVER['SERVER_ADDR'];

and this for the port

$_SERVER['SERVER_PORT'];

Creating a border like this using :before And :after Pseudo-Elements In CSS?

#footer:after
{
   content: "";
    width: 40px;
    height: 3px;
    background-color: #529600;
    left: 0;
    position: relative;
    display: block;
    top: 10px;
}

Spark difference between reduceByKey vs groupByKey vs aggregateByKey vs combineByKey

ReduceByKey reduceByKey(func, [numTasks])-

Data is combined so that at each partition there should be at least one value for each key. And then shuffle happens and it is sent over the network to some particular executor for some action such as reduce.

GroupByKey - groupByKey([numTasks])

It doesn't merge the values for the key but directly the shuffle process happens and here lot of data gets sent to each partition, almost same as the initial data.

And the merging of values for each key is done after the shuffle. Here lot of data stored on final worker node so resulting in out of memory issue.

AggregateByKey - aggregateByKey(zeroValue)(seqOp, combOp, [numTasks]) It is similar to reduceByKey but you can provide initial values when performing aggregation.

Use of reduceByKey

  • reduceByKey can be used when we run on large data set.

  • reduceByKey when the input and output value types are of same type over aggregateByKey

Moreover it recommended not to use groupByKey and prefer reduceByKey. For details you can refer here.

You can also refer this question to understand in more detail how reduceByKey and aggregateByKey.