Programs & Examples On #Mobile robots

A mobile robot is an automatic machine that is capable of movement in a given environment. You may also consider asking your question on [*robotics* stack exchange](http://robotics.stackexchange.com/).

How to click on hidden element in Selenium WebDriver?

I did it with jQuery:

page.execute_script %Q{ $('#some_id').prop('checked', true) }

How to escape double quotes in JSON

For those who would like to use developer powershell. Here are the lines to add to your settings.json:

"terminal.integrated.automationShell.windows": "C:\\Windows\\SysWOW64\\WindowsPowerShell\\v1.0\\powershell.exe",
"terminal.integrated.shellArgs.windows": [
    "-noe",
    "-c",
    " &{Import-Module 'C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\BuildTools\\Common7\\Tools\\Microsoft.VisualStudio.DevShell.dll'; Enter-VsDevShell b7c50c8d} ",
    ],

Splitting a continuous variable into equal sized groups

equal_freq from funModeling takes a vector and the number of bins (based on equal frequency):

das <- data.frame(anim=1:15,
                  wt=c(181,179,180.5,201,201.5,245,246.4,
                       189.3,301,354,369,205,199,394,231.3))

das$wt_bin=funModeling::equal_freq(das$wt, 3)

table(das$wt_bin)

#[179,201) [201,246) [246,394] 
#        5         5         5 

ReferenceError: fetch is not defined

You should add this import in your file:

import * as fetch from 'node-fetch';

And then, run this code to add the node-fetch:

yarn add node-fetch

Show image using file_get_contents

You can use readfile and output the image headers which you can get from getimagesize like this:

$remoteImage = "http://www.example.com/gifs/logo.gif";
$imginfo = getimagesize($remoteImage);
header("Content-type: {$imginfo['mime']}");
readfile($remoteImage);

The reason you should use readfile here is that it outputs the file directly to the output buffer where as file_get_contents will read the file into memory which is unnecessary in this content and potentially intensive for large files.

Viewing full version tree in git

You can try the following:

gitk --all

You can tell gitk what to display using anything that git rev-list understands, so if you just want a few branches, you can do:

gitk master origin/master origin/experiment

... or more exotic things like:

gitk --simplify-by-decoration --all

JQuery window scrolling event?

See jQuery.scroll(). You can bind this to the window element to get your desired event hook.

On scroll, then simply check your scroll position:

$(window).scroll(function() {
  var scrollTop = $(window).scrollTop();
  if ( scrollTop > $(headerElem).offset().top ) { 
    // display add
  }
});

How do I change column default value in PostgreSQL?

If you want to remove the default value constraint, you can do:

ALTER TABLE <table> ALTER COLUMN <column> DROP DEFAULT;

Using print statements only to debug

A better way to debug the code is, by using module clrprint

It prints a color full output only when pass parameter debug=True

from clrprint import *
clrprint('ERROR:', information,clr=['r','y'], debug=True)

Apache - MySQL Service detected with wrong path. / Ports already in use

its because you probaly installed wamp server and uninstall it but wampmysql.exe still running and using the default mysql port go to msconfig under services tab uncheck wampmysqld to deactivate it reboot the computer should work

CSS container div not getting height

You are floating the children which means they "float" in front of the container. In order to take the correct height, you must "clear" the float

The div style="clear: both" clears the floating an gives the correct height to the container. see http://css.maxdesign.com.au/floatutorial/clear.htm for more info on floats.

eg.

<div class="c">
    <div class="l">

    </div>
    <div class="m">
        World
    </div>
    <div style="clear: both" />
</div>

How to delete and recreate from scratch an existing EF Code First database

Take these steps:

  1. Delete those object which should be deleted from the context // Dbset<Item> Items{get;set;} and in Nuget Console run these commands
  2. add-migration [contextName]
  3. update-database -verbose

It will drop table(s) that not exist in Context, but already created in database

Generate a unique id

Why can't we make a unique id as below.

We can use DateTime.Now.Ticks and Guid.NewGuid().ToString() to combine together and make a unique id.

As the DateTime.Now.Ticks is added, we can find out the Date and Time in seconds at which the unique id is created.

Please see the code.

var ticks = DateTime.Now.Ticks;
var guid = Guid.NewGuid().ToString();
var uniqueSessionId = ticks.ToString() +'-'+ guid; //guid created by combining ticks and guid

var datetime = new DateTime(ticks);//for checking purpose
var datetimenow = DateTime.Now;    //both these date times are different.

We can even take the part of ticks in unique id and check for the date and time later for future reference.

How to select option in drop down using Capybara

To add yet another answer to the pile (because apparently there's so many ways of doing it depending on your setup) - I did it by selecting the literal option element and clicking it

find(".some-selector-for-dropdown option[value='1234']").select_option

It's not very pretty, but it works :/

Reflection: How to Invoke Method with parameters

The provided solution does not work for instances of types loaded from a remote assembly. To do that, here is a solution that works in all situations, which involves an explicit type re-mapping of the type returned through the CreateInstance call.

This is how I need to create my classInstance, as it was located in a remote assembly.

// sample of my CreateInstance call with an explicit assembly reference
object classInstance = Activator.CreateInstance(assemblyName, type.FullName); 

However, even with the answer provided above, you'd still get the same error. Here is how to go about:

// first, create a handle instead of the actual object
ObjectHandle classInstanceHandle = Activator.CreateInstance(assemblyName, type.FullName);
// unwrap the real slim-shady
object classInstance = classInstanceHandle.Unwrap(); 
// re-map the type to that of the object we retrieved
type = classInstace.GetType(); 

Then do as the other users mentioned here.

Create a custom event in Java

You probably want to look into the observer pattern.

Here's some sample code to get yourself started:

import java.util.*;

// An interface to be implemented by everyone interested in "Hello" events
interface HelloListener {
    void someoneSaidHello();
}

// Someone who says "Hello"
class Initiater {
    private List<HelloListener> listeners = new ArrayList<HelloListener>();

    public void addListener(HelloListener toAdd) {
        listeners.add(toAdd);
    }

    public void sayHello() {
        System.out.println("Hello!!");

        // Notify everybody that may be interested.
        for (HelloListener hl : listeners)
            hl.someoneSaidHello();
    }
}

// Someone interested in "Hello" events
class Responder implements HelloListener {
    @Override
    public void someoneSaidHello() {
        System.out.println("Hello there...");
    }
}

class Test {
    public static void main(String[] args) {
        Initiater initiater = new Initiater();
        Responder responder = new Responder();

        initiater.addListener(responder);

        initiater.sayHello();  // Prints "Hello!!!" and "Hello there..."
    }
}

Related article: Java: Creating a custom event

New features in java 7

Using Diamond(<>) operator for generic instance creation

Map<String, List<Trade>> trades = new TreeMap <> ();

Using strings in switch statements

String status=  “something”;
   switch(statue){
     case1: 
     case2: 
     default:
    }

Underscore in numeric literals

int val 12_15; long phoneNo = 01917_999_720L;

Using single catch statement for throwing multiple exception by using “|” operator

catch(IOException | NullPointerException ex){
          ex.printStackTrace();   
    }

No need to close() resources because Java 7 provides try-with-resources statement

try(FileOutputStream fos = new FileOutputStream("movies.txt");
      DataOutputStream dos = new DataOutputStream(fos)) {
              dos.writeUTF("Java 7 Block Buster");
  } catch(IOException e) {
        // log the exception
  }

binary literals with prefix “0b” or “0B”

How can I use interface as a C# generic type constraint?

What you have settled for is the best you can do:

public bool Foo<T>() where T : IBase;

How can I switch views programmatically in a view controller? (Xcode, iPhone)

If you're in a Navigation Controller:

ViewController *viewController = [[ViewController alloc] init];
[self.navigationController pushViewController:viewController animated:YES];

or if you just want to present a new view:

ViewController *viewController = [[ViewController alloc] init];    
[self presentViewController:viewController animated:YES completion:nil];

IPhone/IPad: How to get screen width programmatically?

Here is a Swift way to get screen sizes, this also takes current interface orientation into account:

var screenWidth: CGFloat {
    if UIInterfaceOrientationIsPortrait(screenOrientation) {
        return UIScreen.mainScreen().bounds.size.width
    } else {
        return UIScreen.mainScreen().bounds.size.height
    }
}
var screenHeight: CGFloat {
    if UIInterfaceOrientationIsPortrait(screenOrientation) {
        return UIScreen.mainScreen().bounds.size.height
    } else {
        return UIScreen.mainScreen().bounds.size.width
    }
}
var screenOrientation: UIInterfaceOrientation {
    return UIApplication.sharedApplication().statusBarOrientation
}

These are included as a standard function in:

https://github.com/goktugyil/EZSwiftExtensions

500 internal server error, how to debug

You can turn on your PHP errors with error_reporting:

error_reporting(E_ALL);
ini_set('display_errors', 'on');

Edit: It's possible that even after putting this, errors still don't show up. This can be caused if there is a fatal error in the script. From PHP Runtime Configuration:

Although display_errors may be set at runtime (with ini_set()), it won't have any affect if the script has fatal errors. This is because the desired runtime action does not get executed.

You should set display_errors = 1 in your php.ini file and restart the server.

Why isn't sizeof for a struct equal to the sum of sizeof of each member?

It can do so if you have implicitly or explicitly set the alignment of the struct. A struct that is aligned 4 will always be a multiple of 4 bytes even if the size of its members would be something that's not a multiple of 4 bytes.

Also a library may be compiled under x86 with 32-bit ints and you may be comparing its components on a 64-bit process would would give you a different result if you were doing this by hand.

Visual Studio debugger error: Unable to start program Specified file cannot be found

I had the same problem :) Verify the "Source code" folder on the "Solution Explorer", if it doesn't contain any "source code" file then :

Right click on "Source code" > Add > Existing Item > Choose the file You want to build and run.

Good luck ;)

Visual Studio 2015 or 2017 does not discover unit tests

Disable Windows Defender Service. Turning this off immediately caused all of my unit tests to show up in Test Explorer.

window.open with target "_blank" in Chrome

window.open(skey, "_blank", "toolbar=1, scrollbars=1, resizable=1, width=" + 1015 + ", height=" + 800);

How to get Database Name from Connection String using SqlConnectionStringBuilder

You can use InitialCatalog Property or builder["Database"] works as well. I tested it with different case and it still works.

What is the Python 3 equivalent of "python -m SimpleHTTPServer"

In addition to Petr's answer, if you want to bind to a specific interface instead of all the interfaces you can use -b or --bind flag.

python -m http.server 8000 --bind 127.0.0.1

The above snippet should do the trick. 8000 is the port number. 80 is used as the standard port for HTTP communications.

Calling virtual functions inside constructors

Firstly,Object is created and then we assign it 's address to pointers.Constructors are called at the time of object creation and used to initializ the value of data members. Pointer to object comes into scenario after object creation. Thats why, C++ do not allows us to make constructors as virtual . .another reason is that, There is nothing like pointer to constructor , which can point to virtual constructor,because one of the property of virtual function is that it can be used by pointers only.

  1. Virtual functions are used to assign value dynamically,as constructors are static,so we can not make them virtual.

Checkbox for nullable boolean

This is an old question, and the existing answers describe most of the alternatives. But there's one simple option, if you have bool? in your viewmodel, and you don't care about null in your UI:

@Html.CheckBoxFor(m => m.boolValue ?? false);

Executing multi-line statements in the one-line command-line?

this style can be used in makefiles too (and in fact it is used quite often).

python - <<EOF
import sys
for r in range(3): print 'rob'
EOF

or

python - <<-EOF
    import sys
    for r in range(3): print 'rob'
EOF

in latter case leading tab characters are removed too (and some structured outlook can be achieved)

instead of EOF can stand any marker word not appearing in the here document at a beginning of a line (see also here documents in the bash manpage or here).

Finding the 'type' of an input element

If you are using jQuery you can easily check the type of any element.

    function(elementID){    
    var type = $(elementId).attr('type');
    if(type == "text") //inputBox
     console.log("input text" + $(elementId).val().size());
   }

similarly you can check the other types and take appropriate action.

Strange Characters in database text: Ã, Ã, ¢, â‚ €,

The error usually gets introduced while creation of CSV. Try using Linux for saving the CSV as a TextCSV. Libre Office in Ubuntu can enforce the encoding to be UTF-8, worked for me. I wasted a lot of time trying this on Mac OS. Linux is the key. I've tested on Ubuntu.

Good Luck

Java Replace Character At Specific Position Of String?

Use StringBuilder:

StringBuilder sb = new StringBuilder(str);
sb.setCharAt(i - 1, 'k');
str = sb.toString();

How do you determine a processing time in Python?

I also got a requirement to calculate the process time of some code lines. So I tried the approved answer and I got this warning.

DeprecationWarning: time.clock has been deprecated in Python 3.3 and will be removed from Python 3.8: use time.perf_counter or time.process_time instead

So python will remove time.clock() from Python 3.8. You can see more about it from issue #13270. This warning suggest two function instead of time.clock(). In the documentation also mention about this warning in-detail in time.clock() section.

Deprecated since version 3.3, will be removed in version 3.8: The behaviour of this function depends on the platform: use perf_counter() or process_time() instead, depending on your requirements, to have a well defined behaviour.

Let's look at in-detail both functions.


Return the value (in fractional seconds) of a performance counter, i.e. a clock with the highest available resolution to measure a short duration. It does include time elapsed during sleep and is system-wide. The reference point of the returned value is undefined, so that only the difference between the results of consecutive calls is valid.

New in version 3.3.

So if you want it as nanoseconds, you can use time.perf_counter_ns() and if your code consist with time.sleep(secs), it will also count. Ex:-

import time


def func(x):
    time.sleep(5)
    return x * x


lst = [1, 2, 3]
tic = time.perf_counter()
print([func(x) for x in lst])
toc = time.perf_counter()
print(toc - tic)

# [1, 4, 9]
# 15.0041916 --> output including 5 seconds sleep time

Return the value (in fractional seconds) of the sum of the system and user CPU time of the current process. It does not include time elapsed during sleep. It is process-wide by definition. The reference point of the returned value is undefined, so that only the difference between the results of consecutive calls is valid.

New in version 3.3.

So if you want it as nanoseconds, you can use time.process_time_ns() and if your code consist with time.sleep(secs), it won't count. Ex:-

import time


def func(x):
    time.sleep(5)
    return x * x


lst = [1, 2, 3]
tic = time.process_time()
print([func(x) for x in lst])
toc = time.process_time()
print(toc - tic)

# [1, 4, 9]
# 0.0 --> output excluding 5 seconds sleep time

Please note both time.perf_counter_ns() and time.process_time_ns() come up with Python 3.7 onward.

Where are Magento's log files located?

You can find them in /var/log within your root Magento installation

There will usually be two files by default, exception.log and system.log.

If the directories or files don't exist, create them and give them the correct permissions, then enable logging within Magento by going to System > Configuration > Developer > Log Settings > Enabled = Yes

^[A-Za-Z ][A-Za-z0-9 ]* regular expression?

First must be Alphabet and then dot not allowed in target string. below is code.

        string input = "A_aaA";

        // B
        // The regular expression we use to match
        Regex r1 = new Regex("^[A-Za-z][^.]*$"); //[\t\0x0020] tab and spaces.

        // C
        // Match the input and write results
        Match match = r1.Match(input);
        if (match.Success)
        {
            Console.WriteLine("Valid: {0}", match.Value);

        }
        else
        {
            Console.WriteLine("Not Match");
        }


        Console.ReadLine();

git is not installed or not in the PATH

Go to Environmental Variables you will find this in Computer Properties->Advance system Setting->Environmental Variables -> Path

Add the path of your git installed int the system. eg: "C:\Program Files\Git\cmd"

Save it. Good to go now!!

Align labels in form next to input

Answered a question such as this before, you can take a look at the results here:

Creating form to have fields and text next to each other - what is the semantic way to do it?

So to apply the same rules to your fiddle you can use display:inline-block to display your label and input groups side by side, like so:

CSS

input {
    margin-top: 5px;
    margin-bottom: 5px;
    display:inline-block;
    *display: inline;     /* for IE7*/
    zoom:1;              /* for IE7*/
    vertical-align:middle;
    margin-left:20px
}

label {
    display:inline-block;
    *display: inline;     /* for IE7*/
    zoom:1;              /* for IE7*/
    float: left;
    padding-top: 5px;
    text-align: right;
    width: 140px;
}

updated fiddle

How to generate a random alpha-numeric string

You can use the UUID class with its getLeastSignificantBits() message to get 64 bit of random data, and then convert it to a radix 36 number (i.e. a string consisting of 0-9,A-Z):

Long.toString(Math.abs( UUID.randomUUID().getLeastSignificantBits(), 36));

This yields a string up to 13 characters long. We use Math.abs() to make sure there isn't a minus sign sneaking in.

What is the .idea folder?

There is no problem in deleting this. It's not only the WebStorm IDE creating this file, but also PhpStorm and all other of JetBrains' IDEs.

It is safe to delete it but if your project is from GitLab or GitHub then you will see a warning.

MySQL - Replace Character in Columns

maybe I'd go by this.

 SQL = SELECT REPLACE(myColumn, '""', '\'') FROM myTable

I used singlequotes because that's the one that registers string expressions in MySQL, or so I believe.

Hope that helps.

Secure random token in Node.js

Random URL and filename string safe (1 liner)

Crypto.randomBytes(48).toString('base64').replace(/\+/g, '-').replace(/\//g, '_').replace(/\=/g, '');

How to set a background image in Xcode using swift?

I am beginner to iOS development so I would like to share whole info I got in this section.

First from image assets (images.xcassets) create image set .

According to Documentation here is all sizes need to create background image.

For iPhone 5:
   640 x 1136

   For iPhone 6:
   750 x 1334 (@2x) for portrait
   1334 x 750 (@2x) for landscape

   For iPhone 6 Plus:
   1242 x 2208 (@3x) for portrait
   2208 x 1242 (@3x) for landscape

   iPhone 4s (@2x)      
   640 x 960

   iPad and iPad mini (@2x) 
   1536 x 2048 (portrait)
   2048 x 1536 (landscape)

   iPad 2 and iPad mini (@1x)
   768 x 1024 (portrait)
   1024 x 768 (landscape)

   iPad Pro (@2x)
   2048 x 2732 (portrait)
   2732 x 2048 (landscape)

call the image background we can call image from image assets by using this method UIImage(named: "background") here is full code example

  override func viewDidLoad() {
          super.viewDidLoad()
             assignbackground()
            // Do any additional setup after loading the view.
        }

  func assignbackground(){
        let background = UIImage(named: "background")

        var imageView : UIImageView!
        imageView = UIImageView(frame: view.bounds)
        imageView.contentMode =  UIViewContentMode.ScaleAspectFill
        imageView.clipsToBounds = true
        imageView.image = background
        imageView.center = view.center
        view.addSubview(imageView)
        self.view.sendSubviewToBack(imageView)
    }

How can I get the current date and time in UTC or GMT in Java?

this is my implementation:

public static String GetCurrentTimeStamp()
{
    Calendar cal=Calendar.getInstance();
    long offset = cal.getTimeZone().getOffset(System.currentTimeMillis());//if you want in UTC else remove it .
    return new java.sql.Timestamp(System.currentTimeMillis()+offset).toString();    
}

Why did I get the compile error "Use of unassigned local variable"?

A very dummy mistake, but you can get this with a class too if you didn't instantiate it.

BankAccount account;
account.addMoney(5);

The above will produce the same error whereas:

class BankAccount
{
    int balance = 0;
    public void addMoney(int amount)
    {
        balance += amount;
    }
}

Do the following to eliminate the error:

BankAccount account = new BankAccount();
account.addMoney(5);

What to use now Google News API is deprecated?

I'm running into the same issue with one of my own apps. So far I've found the only non-deprecated way to access Google News data is through their RSS feeds. They have a feed for each section and also a useful search function. However, these are only for noncommercial use.

As for viable alternatives I'll be trying out these two services: Feedzilla, Daylife

Error 5 : Access Denied when starting windows service

I realize this post is old, but there's no marked solution and I just wanted to throw in how I resolved this.

The first Error 5: Access Denied error was resolved by giving permissions to the output directory to the NETWORK SERVICE account.

The second Started and then stopped error seems to be a generic message when something faulted the service. Check the Event Viewer (specifically the 'Windows Logs > Application') for the real error message.

In my case, it was a bad service configuration setting in app.config.

The HTTP request is unauthorized with client authentication scheme 'Ntlm' The authentication header received from the server was 'NTLM'

I would try to connect to your Sharepoint site with this tool here. If that works you can be sure that the problem is in your code / configuration. That maybe does not solve your problem immediately but it rules out that there is something wrong with the server. Assuming that it does not work I would investigate the following:

  • Does your user really have enough rights on the site?
  • Is there a proxy that interferes? (Your configuration looks a bit like there is a proxy. Can you bypass it?)

I think there is nothing wrong with using security mode Transport, but I am not so sure about the proxyCredentialType="Ntlm", maybe this should be set to None.

How to diff one file to an arbitrary version in Git?

For comparing to 5 commit to the current one, both on master, just simply do:

git diff master~5:pom.xml master:pom.xml

Also you can refer to commit hash number, for example if the hash number is x110bd64, you can do something like this to see the difference:

git diff x110bd64 pom.xml

Regex to Match Symbols: !$%^&*()_+|~-=`{}[]:";'<>?,./

Answer

/[\W\S_]/

Explanation

This creates a character class removing the word characters, space characters, and adding back the underscore character (as underscore is a "word" character). All that is left is the special characters. Capital letters represent the negation of their lowercase counterparts.

\W will select all non "word" characters equivalent to [^a-zA-Z0-9_]
\S will select all non "whitespace" characters equivalent to [ \t\n\r\f\v]
_ will select "_" because we negate it when using the \W and need to add it back in

How can I overwrite file contents with new content in PHP?

Use file_put_contents()

file_put_contents('file.txt', 'bar');
echo file_get_contents('file.txt'); // bar
file_put_contents('file.txt', 'foo');
echo file_get_contents('file.txt'); // foo

Alternatively, if you're stuck with fopen() you can use the w or w+ modes:

'w' Open for writing only; place the file pointer at the beginning of the file and truncate the file to zero length. If the file does not exist, attempt to create it.

'w+' Open for reading and writing; place the file pointer at the beginning of the file and truncate the file to zero length. If the file does not exist, attempt to create it.

How to concatenate multiple column values into a single column in Panda dataframe

@derchambers I found one more solution:

import pandas as pd

# make data
df = pd.DataFrame(index=range(1_000_000))
df['1'] = 'CO'
df['2'] = 'BOB'
df['3'] = '01'
df['4'] = 'BILL'

def eval_join(df, columns):

    sum_elements = [f"df['{col}']" for col in list('1234')]
    to_eval = "+ '_' + ".join(sum_elements)

    return eval(to_eval)


#profile
%timeit df3 = eval_join(df, list('1234')) # 504 ms

Early exit from function?

If you are using jquery. This should stop the function from bubbling up to so the parent function calling this should stop as well.

  function myfunction(e)
  {
       e.stopImmediatePropagation();
       ................
  }

SQL Insert Query Using C#

class Program
{
    static void Main(string[] args)
    {
        string connetionString = null;
        SqlConnection connection;
        SqlCommand command;
        string sql = null;

        connetionString = "Data Source=Server Name;Initial Catalog=DataBaseName;User ID=UserID;Password=Password";
        sql = "INSERT INTO LoanRequest(idLoanRequest,RequestDate,Pickupdate,ReturnDate,EventDescription,LocationOfEvent,ApprovalComments,Quantity,Approved,EquipmentAvailable,ModifyRequest,Equipment,Requester)VALUES('5','2016-1-1','2016-2-2','2016-3-3','DescP','Loca1','Appcoment','2','true','true','true','4','5')";
        connection = new SqlConnection(connetionString);

        try
        {
            connection.Open();
            Console.WriteLine(" Connection Opened ");
            command = new SqlCommand(sql, connection);                
            SqlDataReader dr1 = command.ExecuteReader();         

            connection.Close();
        }
        catch (Exception ex)
        {
            Console.WriteLine("Can not open connection ! ");
        }
    }
}

XAMPP - Port 80 in use by "Unable to open process" with PID 4! 12

I had this problem too and stoping services using port 80 didn't helped. I resolved it by following this procedure (found on a french board):

  1. Launch RegEdit
  2. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\HTTP
  3. Change the value of "start" to 4 (disabled)
  4. Reboot your computer

Not sure how this affect other services, but it solved permanently the issue and so far I didn't see any issue.

Using Windows 10.

ojdbc14.jar vs. ojdbc6.jar

I have same problem!

Found following in oracle site link text

As mentioned above, the 11.1 drivers by default convert SQL DATE to Timestamp when reading from the database. This always was the right thing to do and the change in 9i was a mistake. The 11.1 drivers have reverted to the correct behavior. Even if you didn't set V8Compatible in your application you shouldn't see any difference in behavior in most cases. You may notice a difference if you use getObject to read a DATE column. The result will be a Timestamp rather than a Date. Since Timestamp is a subclass of Date this generally isn't a problem. Where you might notice a difference is if you relied on the conversion from DATE to Date to truncate the time component or if you do toString on the value. Otherwise the change should be transparent.

If for some reason your app is very sensitive to this change and you simply must have the 9i-10g behavior, there is a connection property you can set. Set mapDateToTimestamp to false and the driver will revert to the default 9i-10g behavior and map DATE to Date.

Test a string for a substring

if "ABCD" in "xxxxABCDyyyy":
    # whatever

How to write into a file in PHP?

You can use a higher-level function like:

file_put_contents($filename, $content);

which is identical to calling fopen(), fwrite(), and fclose() successively to write data to a file.

Docs: file_put_contents

How to escape % in String.Format?

To escape %, you will need to double it up: %%.

When should you use a class vs a struct in C++?

The differences between a class and a struct in C++ is:

  • struct members and base classes/structs are public by default.
  • class members and base classes/struts are private by default.

Both classes and structs can have a mixture of public, protected and private members, can use inheritance and can have member functions.

I would recommend you:

  • use struct for plain-old-data structures without any class-like features;
  • use class when you make use of features such as private or protected members, non-default constructors and operators, etc.

to call onChange event after pressing Enter key

Here is a common use case using class-based components: The parent component provides a callback function, the child component renders the input box, and when the user presses Enter, we pass the user's input to the parent.

class ParentComponent extends React.Component {
  processInput(value) {
    alert('Parent got the input: '+value);
  }

  render() {
    return (
      <div>
        <ChildComponent handleInput={(value) => this.processInput(value)} />
      </div>
    )
  }
}

class ChildComponent extends React.Component {
  constructor(props) {
    super(props);
    this.handleKeyDown = this.handleKeyDown.bind(this);
  }

  handleKeyDown(e) {
    if (e.key === 'Enter') {
      this.props.handleInput(e.target.value);
    }
  }

  render() {
    return (
      <div>
        <input onKeyDown={this.handleKeyDown} />
      </div>
    )
  }      
}

jQuery AJAX file upload PHP

and this is the php file to receive the uplaoded files

<?
$data = array();
    //check with your logic
    if (isset($_FILES)) {
        $error = false;
        $files = array();

        $uploaddir = $target_dir;
        foreach ($_FILES as $file) {
            if (move_uploaded_file($file['tmp_name'], $uploaddir . basename( $file['name']))) {
                $files[] = $uploaddir . $file['name'];
            } else {
                $error = true;
            }
        }
        $data = ($error) ? array('error' => 'There was an error uploading your files') : array('files' => $files);
    } else {
        $data = array('success' => 'NO FILES ARE SENT','formData' => $_REQUEST);
    }

    echo json_encode($data);
?>

Rename multiple files based on pattern in Unix

There are several ways, but using rename will probably be the easiest.

Using one version of rename:

rename 's/^fgh/jkl/' fgh*

Using another version of rename (same as Judy2K's answer):

rename fgh jkl fgh*

You should check your platform's man page to see which of the above applies.

Integer to hex string in C++

You can try the following. It's working...

#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
using namespace std;

template <class T>
string to_string(T t, ios_base & (*f)(ios_base&))
{
  ostringstream oss;
  oss << f << t;
  return oss.str();
}

int main ()
{
  cout<<to_string<long>(123456, hex)<<endl;
  system("PAUSE");
  return 0;
}

How to re-enable right click so that I can inspect HTML elements in Chrome?

The way I solved this was delete the event listeners on the page. After I did that, I was able to copy the text and paste it in to my processor of choice.

What is a faster alternative to Python's http.server (or SimpleHTTPServer)?

Try webfs, it's tiny and doesn't depend on having a platform like node.js or python installed.

AWS : The config profile (MyName) could not be found

I think there is something missing from the AWS documentation in http://docs.aws.amazon.com/lambda/latest/dg/setup-awscli.html, it did not mention that you should edit the file ~/.aws/config to add your username profile. There are two ways to do this:

  1. edit ~/.aws/config or

  2. aws configure --profile "your username"

Where is android_sdk_root? and how do I set it.?

in mac os you can try brew install gradle

Pointers in Python?

The following code emulates exactly the behavior of pointers in C:

from collections import deque # more efficient than list for appending things
pointer_storage = deque()
pointer_address = 0

class new:    
    def __init__(self):
        global pointer_storage    
        global pointer_address

        self.address = pointer_address
        self.val = None        
        pointer_storage.append(self)
        pointer_address += 1


def get_pointer(address):
    return pointer_storage[address]

def get_address(p):
    return p.address

null = new() # create a null pointer, whose address is 0    

Here are examples of use:

p = new()
p.val = 'hello'
q = new()
q.val = p
r = new()
r.val = 33

p = get_pointer(3)
print(p.val, flush = True)
p.val = 43
print(get_pointer(3).val, flush = True)

But it's now time to give a more professional code, including the option of deleting pointers, that I've just found in my personal library:

# C pointer emulation:

from collections import deque # more efficient than list for appending things
from sortedcontainers import SortedList #perform add and discard in log(n) times


class new:      
    # C pointer emulation:
    # use as : p = new()
    #          p.val             
    #          p.val = something
    #          p.address
    #          get_address(p) 
    #          del_pointer(p) 
    #          null (a null pointer)

    __pointer_storage__ = SortedList(key = lambda p: p.address)
    __to_delete_pointers__ = deque()
    __pointer_address__ = 0 

    def __init__(self):      

        self.val = None 

        if new.__to_delete_pointers__:
            p = new.__to_delete_pointers__.pop()
            self.address = p.address
            new.__pointer_storage__.discard(p) # performed in log(n) time thanks to sortedcontainers
            new.__pointer_storage__.add(self)  # idem

        else:
            self.address = new.__pointer_address__
            new.__pointer_storage__.add(self)
            new.__pointer_address__ += 1


def get_pointer(address):
    return new.__pointer_storage__[address]


def get_address(p):
    return p.address


def del_pointer(p):
    new.__to_delete_pointers__.append(p)

null = new() # create a null pointer, whose address is 0

PHP float with 2 decimal places: .00

try this

$result = number_format($FloatNumber, 2);

Bash script and /bin/bash^M: bad interpreter: No such file or directory

If you use Sublime Text on Windows or Mac to edit your scripts:

Click on View > Line Endings > Unix and save the file again.

enter image description here

Detecting a long press with Android

The solution by MSquare works only if you hold a specific pixel, but that's an unreasonable expectation for an end user unless they use a mouse (which they don't, they use fingers).

So I added a bit of a threshold for the distance between the DOWN and the UP action in case there was a MOVE action inbetween.

final Handler longPressHandler = new Handler();
Runnable longPressedRunnable = new Runnable() {
    public void run() {
        Log.e(TAG, "Long press detected in long press Handler!");
        isLongPressHandlerActivated = true;
    }
};

private boolean isLongPressHandlerActivated = false;

private boolean isActionMoveEventStored = false;
private float lastActionMoveEventBeforeUpX;
private float lastActionMoveEventBeforeUpY;

@Override
public boolean dispatchTouchEvent(MotionEvent event) {
    if(event.getAction() == MotionEvent.ACTION_DOWN) {
        longPressHandler.postDelayed(longPressedRunnable, 1000);
    }
    if(event.getAction() == MotionEvent.ACTION_MOVE || event.getAction() == MotionEvent.ACTION_HOVER_MOVE) {
        if(!isActionMoveEventStored) {
            isActionMoveEventStored = true;
            lastActionMoveEventBeforeUpX = event.getX();
            lastActionMoveEventBeforeUpY = event.getY();
        } else {
            float currentX = event.getX();
            float currentY = event.getY();
            float firstX = lastActionMoveEventBeforeUpX;
            float firstY = lastActionMoveEventBeforeUpY;
            double distance = Math.sqrt(
                    (currentY - firstY) * (currentY - firstY) + ((currentX - firstX) * (currentX - firstX)));
            if(distance > 20) {
                longPressHandler.removeCallbacks(longPressedRunnable);
            }
        }
    }
    if(event.getAction() == MotionEvent.ACTION_UP) {
        isActionMoveEventStored = false;
        longPressHandler.removeCallbacks(longPressedRunnable);
        if(isLongPressHandlerActivated) {
            Log.d(TAG, "Long Press detected; halting propagation of motion event");
            isLongPressHandlerActivated = false;
            return false;
        }
    }
    return super.dispatchTouchEvent(event);
}

How to add a search box with icon to the navbar in Bootstrap 3?

You could use the segmented buttons example from Bootstrap 3:

<form action="" class="navbar-form navbar-right">
   <div class="input-group">
       <input type="Search" placeholder="Search..." class="form-control" />
       <div class="input-group-btn">
           <button class="btn btn-info">
           <span class="glyphicon glyphicon-search"></span>
           </button>
       </div>
   </div>
</form>

How to check a string against null in java?

With Java 7 you can use

if (Objects.equals(foo, null)) {
    ...
}

which will return true if both parameters are null.

XPath to select Element by attribute value

You need to remove the / before the [. Predicates (the parts in [ ]) shouldn't have slashes immediately before them. Also, to select the Employee element itself, you should leave off the /text() at the end or otherwise you'd just be selecting the whitespace text values immediately under the Employee element.

//Employee[@id='4']

Edit: As Jens points out in the comments, // can be very slow because it searches the entire document for matching nodes. If the structure of the documents you're working with is going to be consistent, you are probably best off using a full path, for example:

/Employees/Employee[@id='4']

How to get the directory of the currently running file?

Use package osext

It's providing function ExecutableFolder() that returns an absolute path to folder where the currently running program executable reside (useful for cron jobs). It's cross platform.

Online documentation

package main

import (
    "github.com/kardianos/osext"
    "fmt"
    "log"
)

func main() {
    folderPath, err := osext.ExecutableFolder()
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println(folderPath)
}

RegExp matching string not starting with my

You could either use a lookahead assertion like others have suggested. Or, if you just want to use basic regular expression syntax:

^(.?$|[^m].+|m[^y].*)

This matches strings that are either zero or one characters long (^.?$) and thus can not be my. Or strings with two or more characters where when the first character is not an m any more characters may follow (^[^m].+); or if the first character is a m it must not be followed by a y (^m[^y]).

Rename a file in C#

Just add:

namespace System.IO
{
    public static class FileInfoExtensions
    {
        public static void Rename(this FileInfo fileInfo, string newName)
        {
            fileInfo.MoveTo(Path.Combine(fileInfo.Directory.FullName, newName));
        }
    }
}

And then...

FileInfo file = new FileInfo("c:\test.txt");
file.Rename("test2.txt");

Server.UrlEncode vs. HttpUtility.UrlEncode

HttpServerUtility.UrlEncode will use HttpUtility.UrlEncode internally. There is no specific difference. The reason for existence of Server.UrlEncode is compatibility with classic ASP.

'git status' shows changed files, but 'git diff' doesn't

For me, it had something to do with file permissions. Someone with Mac/Linux on my project seems to commit some files with non-default permissions which my Windows git client failed to reproduce. Solution for me was to tell git to ignore file permissions:

git config core.fileMode false

Other insight: How do I make Git ignore file mode (chmod) changes?

How do I change the default schema in sql developer?

After you granted the permissions to the specified user you have to do this at filtering:

First step:

First Step to change default Tables

Second step:

Second Step to change default Tables

Now you will be able to display the tables after you changed the default load Alter session to the desire schema (using a Trigger after LOG ON).

What is the difference between <%, <%=, <%# and -%> in ERB in Rails?

These are use in ruby on rails :-

<% %> :-

The <% %> tags are used to execute Ruby code that does not return anything, such as conditions, loops or blocks. Eg :-

<h1>Names of all the people</h1>
<% @people.each do |person| %>
  Name: <%= person.name %><br>
<% end %>

<%= %> :-

use to display the content .

Name: <%= person.name %><br>

<% -%>:-

Rails extends ERB, so that you can suppress the newline simply by adding a trailing hyphen to tags in Rails templates

<%# %>:-

comment out the code

<%# WRONG %>
Hi, Mr. <% puts "Frodo" %>

rails 3.1.0 ActionView::Template::Error (application.css isn't precompiled)

By default Rails assumes that you have your files precompiled in the production environment, if you want use live compiling (compile your assets during runtime) in production you must set the config.assets.compile to true.

# config/environments/production.rb
...
config.assets.compile = true
...

You can use this option to fallback to Sprockets when you are using precompiled assets but there are any missing precompiled files.

If config.assets.compile option is set to false and there are missing precompiled files you will get an "AssetNoPrecompiledError" indicating the name of the missing file.

Html ordered list 1.1, 1.2 (Nested counters and scope) not working

Check this out :

http://jsfiddle.net/PTbGc/

Your issue seems to have been fixed.


What shows up for me (under Chrome and Mac OS X)

1. one
2. two
  2.1. two.one
  2.2. two.two
  2.3. two.three
3. three
  3.1 three.one
  3.2 three.two
    3.2.1 three.two.one
    3.2.2 three.two.two
4. four

How I did it


Instead of :

<li>Item 1</li>
<li>Item 2</li>
   <ol>
        <li>Subitem 1</li>
        <li>Subitem 2</li>
   </ol>

Do :

<li>Item 1</li>
<li>Item 2
   <ol>
        <li>Subitem 1</li>
        <li>Subitem 2</li>
   </ol>
</li>

How to install the current version of Go in Ubuntu Precise

You can use a script from udhos/update-golang.

Here is a two-liner as example (run as root):

bash <(curl -s https://raw.githubusercontent.com/udhos/update-golang/master/update-golang.sh)
ln -vs /usr/local/go/bin/go* /usr/local/bin/

How do you close/hide the Android soft keyboard using Java?

An easy workaround ist to just editText.setEnabled(false);editText.setEnabled(true); in your Button onClick() method.

using setTimeout on promise chain

The shorter ES6 version of the answer:

const delay = t => new Promise(resolve => setTimeout(resolve, t));

And then you can do:

delay(3000).then(() => console.log('Hello'));

Redis: Show database size/size for keys

MEMORY USAGE key command gives you the number of bytes that a key and its value require to be stored in RAM.

The reported usage is the total of memory allocations for data and administrative overheads that a key its value require (source redis documentation)

GIT fatal: ambiguous argument 'HEAD': unknown revision or path not in the working tree

Jacob Helwig mentions in his answer that:

It looks like rev-parse is being used without sufficient error checking before-hand

Commit 62f162f from Jeff King (peff) should improve the robustness of git rev-parse in Git 1.9/2.0 (Q1 2014) (in addition of commit 1418567):

For cases where we do not match (e.g., "doesnotexist..HEAD"), we would then want to try to treat the argument as a filename.
try_difference() gets this right, and always unmunges in this case.
However, try_parent_shorthand() never unmunges, leading to incorrect error messages, or even incorrect results:

$ git rev-parse foobar^@
foobar
fatal: ambiguous argument 'foobar': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'

json.dump throwing "TypeError: {...} is not JSON serializable" on seemingly valid object?

In my case, boolean values in my Python dict were the problem. JSON boolean values are in lowercase ("true", "false") whereas in Python they are in Uppercase ("True", "False"). Couldn't find this solution anywhere online but hope it helps.

Read MS Exchange email in C#

Um,

I might be a bit too late here but isn't this kinda the point to EWS ?

https://msdn.microsoft.com/en-us/library/dd633710(EXCHG.80).aspx

Takes about 6 lines of code to get the mail from a mailbox:

ExchangeService service = new ExchangeService(ExchangeVersion.Exchange2007_SP1);

//service.Credentials = new NetworkCredential( "{Active Directory ID}", "{Password}", "{Domain Name}" );

service.AutodiscoverUrl( "[email protected]" );

FindItemsResults<Item> findResults = service.FindItems(
   WellKnownFolderName.Inbox,
   new ItemView( 10 ) 
);

foreach ( Item item in findResults.Items )
{
   Console.WriteLine( item.Subject );
}

List(of String) or Array or ArrayList

look to the List AddRange method here

json and empty array

null is a legal value (and reserved word) in JSON, but some environments do not have a "NULL" object (as opposed to a NULL value) and hence cannot accurately represent the JSON null. So they will sometimes represent it as an empty array.

Whether null is a legal value in that particular element of that particular API is entirely up to the API designer.

Half circle with CSS (border, outline only)

Below is a minimal code to achieve the effect.

This also works responsively since the border-radius is in percentage.

_x000D_
_x000D_
.semi-circle{_x000D_
width: 200px;_x000D_
height: 100px;_x000D_
border-radius: 50% 50% 0 0 / 100% 100% 0 0;_x000D_
border: 10px solid #000;_x000D_
border-bottom: 0;_x000D_
}
_x000D_
<div class="semi-circle"></div>
_x000D_
_x000D_
_x000D_

How do I sort arrays using vbscript?

Disconnected recordsets can be useful.

Const adVarChar = 200  'the SQL datatype is varchar

'Create a disconnected recordset
Set rs = CreateObject("ADODB.RECORDSET")
rs.Fields.append "SortField", adVarChar, 25

rs.CursorType = adOpenStatic
rs.Open
rs.AddNew "SortField", "Some data"
rs.Update
rs.AddNew "SortField", "All data"
rs.Update

rs.Sort = "SortField"

rs.MoveFirst

Do Until rs.EOF
    strList=strList & vbCrLf & rs.Fields("SortField")        
    rs.MoveNext
Loop 

MsgBox strList

What is a "cache-friendly" code?

Welcome to the world of Data Oriented Design. The basic mantra is to Sort, Eliminate Branches, Batch, Eliminate virtual calls - all steps towards better locality.

Since you tagged the question with C++, here's the obligatory typical C++ Bullshit. Tony Albrecht's Pitfalls of Object Oriented Programming is also a great introduction into the subject.

Newline character in StringBuilder

For multiple lines the best way I find is to do this:

        IEnumerable<string> lines = new List<string>
        {
            string.Format("{{ line with formatting... {0} }}", id),
            "line 2",
            "line 3"
        };
        StringBuilder sb = new StringBuilder();
        foreach(var line in lines)
            sb.AppendLine(line);

In this way you don't have to clutter the screen with the Environment.NewLine or AppendLine() repeated multiple times. It will also be less error prone than having to remember to type them.

How can I check if a Perl module is installed on my system from the command line?

Bravo for @user80168's solution (I'm still counting \'s !) but to avoid all the escaping involved with aliases and shells:

%~/ cat ~/bin/perlmod
perl -le'eval qq{require $ARGV[0]; } 
    ? print ( "Found $ARGV[0] Version: ", eval "$ARGV[0]->VERSION" ) 
    : print "Not installed" ' $1

works reasonably well.

Here might be the simplest and most "modern" approach, using Module::Runtime:

perl -MModule::Runtime=use_module -E '
     say "$ARGV[0] ", use_module($ARGV[0])->VERSION' DBI

This will give a useful error if the module is not installed.

Using -MModule::Runtime requires it to be installed (it is not a core module).

In what situations would AJAX long/short polling be preferred over HTML5 WebSockets?

XHR polling vs SSE vs WebSockets

  • XHR polling A Request is answered when the event occurs (could be straight away, or after a delay). Subsequent requests will need to made to receive further events.

    The browser makes an asynchronous request of the server, which may wait for data to be available before responding. The response can contain encoded data (typically XML or JSON) or Javascript to be executed by the client. At the end of the processing of the response, the browser creates and sends another XHR, to await the next event. Thus the browser always keeps a request outstanding with the server, to be answered as each event occurs. Wikipedia

  • Server Sent Events Client sends request to server. Server sends new data to webpage at any time.

    Traditionally, a web page has to send a request to the server to receive new data; that is, the page requests data from the server. With server-sent events, it's possible for a server to send new data to a web page at any time, by pushing messages to the web page. These incoming messages can be treated as Events + data inside the web page. Mozilla

  • WebSockets After the initial handshake (via HTTP protocol). Communication is done bidirectionally using the WebSocket protocol.

    The handshake starts with an HTTP request/response, allowing servers to handle HTTP connections as well as WebSocket connections on the same port. Once the connection is established, communication switches to a bidirectional binary protocol which does not conform to the HTTP protocol. Wikipedia

To add server using sp_addlinkedserver

Add the linked server first with

exec sp_addlinkedserver
@server = 'SNRJDI\SLAMANAGEMENT',
@srvproduct=N'',
@provider=N'SQLNCLI'

See http://msdn.microsoft.com/en-us/library/ms190479.aspx

Google Maps API 3 - Custom marker color for default (dot) marker

You can use this code it works fine.

 var pinImage = new google.maps.MarkerImage("http://www.googlemapsmarkers.com/v1/009900/");<br>

 var marker = new google.maps.Marker({
            position: yourlatlong,
            icon: pinImage,
            map: map
        });

How do you loop through each line in a text file using a windows batch file?

Here's a bat file I wrote to execute all SQL scripts in a folder:

REM ******************************************************************
REM Runs all *.sql scripts sorted by filename in the current folder.
REM To use integrated auth change -U <user> -P <password> to -E
REM ******************************************************************

dir /B /O:n *.sql > RunSqlScripts.tmp
for /F %%A in (RunSqlScripts.tmp) do osql -S (local) -d DEFAULT_DATABASE_NAME -U USERNAME_GOES_HERE -P PASSWORD_GOES_HERE -i %%A
del RunSqlScripts.tmp

Merge two HTML table cells

Set the colspan attribute to 2.

...but please don't use tables for layout.

How can I represent an infinite number in Python?

In Python, you can do:

test = float("inf")

In Python 3.5, you can do:

import math
test = math.inf

And then:

test > 1
test > 10000
test > x

Will always be true. Unless of course, as pointed out, x is also infinity or "nan" ("not a number").

Additionally (Python 2.x ONLY), in a comparison to Ellipsis, float(inf) is lesser, e.g:

float('inf') < Ellipsis

would return true.

How do I use ROW_NUMBER()?

select 
  Ml.Hid,
  ml.blockid,
  row_number() over (partition by ml.blockid order by Ml.Hid desc) as rownumber,
  H.HNAME 
from MIT_LeadBechmarkHamletwise ML
join [MT.HAMLE] h on ML.Hid=h.HID

How can I print out all possible letter combinations a given phone number can represent?

Here is one for pain C. This one is likley not efficet (in fact I don't think it is at all). But there are some intresting aspects to it.

  1. It take a number and converts it into a string
  2. It just raises the seed number once each time to create the next sequential string

Whats nice about this is that there is no real limit to the size of the string (no character limit) This allows you to generate longer and longer strings if need be just by waiting.

#include <stdlib.h>
#include <stdio.h>

#define CHARACTER_RANGE 95  //  The range of valid password characters
#define CHARACTER_OFFSET 32 //  The offset of the first valid character

void main(int argc, char *argv[], char *env[])
{
    int i;

    long int string;
    long int worker;
    char *guess;    //  Current Generation
    guess = (char*)malloc(1);   //  Allocate it so free doesn't fail

    int cur;

    for ( string = 0; ; string++ )
    {
        worker = string;

        free(guess);
        guess = (char*)malloc((string/CHARACTER_RANGE+1)*sizeof(char)); //  Alocate for the number of characters we will need

        for ( i = 0; worker > 0 && i < string/CHARACTER_RANGE + 1; i++ )    //  Work out the string
        {
            cur = worker % CHARACTER_RANGE; //  Take off the last digit
            worker = (worker - cur) / CHARACTER_RANGE;  //  Advance the digits
            cur += CHARACTER_OFFSET;

            guess[i] = cur;
        }
        guess[i+1] = '\0';  //  NULL terminate our string

        printf("%s\t%d\n", guess, string);
    }
}

How do I use HTML as the view engine in Express?

To make the render engine accept html instead of jade you can follow the following steps;

Install consolidate and swig to your directory.

 npm install consolidate
 npm install swig

add following lines to your app.js file

var cons = require('consolidate');

// view engine setup
app.engine('html', cons.swig)
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'html');

add your view templates as .html inside “views” folder. Restart you node server and start the app in the browser.

This should work

In PHP how can you clear a WSDL cache?

Edit your php.ini file, search for soap.wsdl_cache_enabled and set the value to 0

[soap]
; Enables or disables WSDL caching feature.
; http://php.net/soap.wsdl-cache-enabled
soap.wsdl_cache_enabled=0

How can I call a shell command in my Perl script?

From Perl HowTo, the most common ways to execute external commands from Perl are:

  • my $files = `ls -la` — captures the output of the command in $files
  • system "touch ~/foo" — if you don't want to capture the command's output
  • exec "vim ~/foo" — if you don't want to return to the script after executing the command
  • open(my $file, '|-', "grep foo"); print $file "foo\nbar" — if you want to pipe input into the command

Make column fixed position in bootstrap

iterating over Ihab's answer, just using position:fixed and bootstraps col-offset you don't need to be specific on the width.

<div class="row">
    <div class="col-lg-3" style="position:fixed">
        Fixed content
    </div>
    <div class="col-lg-9 col-lg-offset-3">
        Normal scrollable content
    </div>
</div>

HTML5 Video Autoplay not working correctly

_x000D_
_x000D_
html {_x000D_
  padding: 20px 0;_x000D_
  background-color: #efefef;_x000D_
}_x000D_
_x000D_
body {_x000D_
  width: 400px;_x000D_
  padding: 40px;_x000D_
  margin: 0 auto;_x000D_
  background: #fff;_x000D_
  box-shadow: 1px 1px 5px rgba(0, 0, 0, 0.5);_x000D_
}_x000D_
_x000D_
video {_x000D_
  width: 400px;_x000D_
  display: block;_x000D_
}
_x000D_
<video onloadeddata="this.play();this.muted=false;" poster="https://durian.blender.org/wp-content/themes/durian/images/void.png" playsinline loop muted controls>_x000D_
    <source src="http://grochtdreis.de/fuer-jsfiddle/video/sintel_trailer-480.mp4" type="video/mp4" />_x000D_
    Your browser does not support the video tag or the file format of this video._x000D_
</video>
_x000D_
_x000D_
_x000D_

MVC razor form with multiple different submit buttons?

This answer will show you that how to work in asp.net with razor, and to control multiple submit button event. Lets for example we have two button, one button will redirect us to "PageA.cshtml" and other will redirect us to "PageB.cshtml".

@{
  if (IsPost)
    {
       if(Request["btn"].Equals("button_A"))
        {
          Response.Redirect("PageA.cshtml");
        }
      if(Request[&quot;btn"].Equals("button_B"))
        {
          Response.Redirect(&quot;PageB.cshtml&quot;);
        }
  }
}
<form method="post">
   <input type="submit" value="button_A" name="btn"/>;
   <input type="submit" value="button_B" name="btn"/>;          
</form>

C# elegant way to check if a property's property is null

Just stumbled accross this post.

Some time ago I made a suggestion on Visual Studio Connect about adding a new ??? operator.

http://visualstudio.uservoice.com/forums/121579-visual-studio/suggestions/4104392-add-as-an-recursive-null-reference-check-opera

This would require some work from the framework team but don't need to alter the language but just do some compiler magic. The idea was that the compiler should change this code (syntax not allowed atm)

string product_name = Order.OrderDetails[0].Product.Name ??? "no product defined";

into this code

Func<string> _get_default = () => "no product defined"; 
string product_name = Order == null 
    ? _get_default.Invoke() 
    : Order.OrderDetails[0] == null 
        ? _get_default.Invoke() 
        : Order.OrderDetails[0].Product == null 
            ? _get_default.Invoke() 
            : Order.OrderDetails[0].Product.Name ?? _get_default.Invoke()

For null check this could look like

bool isNull = (Order.OrderDetails[0].Product ??? null) == null;

Laravel 5 Application Key

This line in your app.php, 'key' => env('APP_KEY', 'SomeRandomString'),, is saying that the key for your application can be found in your .env file on the line APP_KEY.

Basically it tells Laravel to look for the key in the .env file first and if there isn't one there then to use 'SomeRandomString'.

When you use the php artisan key:generate it will generate the new key to your .env file and not the app.php file.

As kotapeter said, your .env will be inside your root Laravel directory and may be hidden; xampp/htdocs/laravel/blog

How to insert data into elasticsearch

To test and try curl requests from Windows, you can make use of Postman client Chrome extension. It is very simple to use and quite powerful.

Or as suggested you can install the cURL util.

A sample curl request is as follows.

curl -X POST -H "Content-Type: application/json" -H "Cache-Control: no-cache" -d '{
"user" : "Arun Thundyill Saseendran",
"post_date" : "2009-03-23T12:30:00",
"message" : "trying out Elasticsearch"
}' "http://10.103.102.56:9200/sampleindex/sampletype/"

I am also getting started with and exploring ES in vast. So please let me know if you have any other doubts.

EDIT: Updated the index name and type name to be fully lowercase to avoid errors and follow convention.

How to dynamically remove items from ListView on a button click?

<ImageView
    android:id="@+id/btnDelete"
    android:layout_width="35dp"
    android:layout_height="match_parent"
    android:layout_alignBottom="@+id/editTipo"
    android:layout_alignParentRight="true"
    android:background="@drawable/abc_ic_clear"
    android:onClick="item_delete_handler"/>

And create Event item_delete_handler,

Working with UTF-8 encoding in Python source

Do not forget to verify if your text editor encodes properly your code in UTF-8.

Otherwise, you may have invisible characters that are not interpreted as UTF-8.

Please explain about insertable=false and updatable=false in reference to the JPA @Column annotation

I would like to add to the answers of BalusC and Pascal Thivent another common use of insertable=false, updatable=false:

Consider a column that is not an id but some kind of sequence number. The responsibility for calculating the sequence number may not necessarily belong to the application.

For example, sequence number starts with 1000 and should increment by one for each new entity. This is easily done, and very appropriately so, in the database, and in such cases these configurations makes sense.

How to send post request with x-www-form-urlencoded body

For HttpEntity, the below answer works

HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);

MultiValueMap<String, String> map= new LinkedMultiValueMap<String, String>();
map.add("email", "[email protected]");

HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<MultiValueMap<String, String>>(map, headers);

ResponseEntity<String> response = restTemplate.postForEntity( url, request , String.class );

For reference: How to POST form data with Spring RestTemplate?

How to customize the background color of a UITableViewCell?

Simply put this in you UITableView delegate class file (.m):

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell  forRowAtIndexPath:(NSIndexPath *)indexPath 
{
    UIColor *color = ((indexPath.row % 2) == 0) ? [UIColor colorWithRed:255.0/255 green:255.0/255 blue:145.0/255 alpha:1] : [UIColor clearColor];
    cell.backgroundColor = color;
}

Delete many rows from a table using id in Mysql

DELETE FROM table_name WHERE id BETWEEN 1 AND 256;

Try This.

Best way to get the max value in a Spark dataframe column

I used another solution (by @satprem rath) already present in this chain.

To find the min value of age in the dataframe:

df.agg(min("age")).show()

+--------+
|min(age)|
+--------+
|      29|
+--------+

edit: to add more context.

While the above method printed the result, I faced issues when assigning the result to a variable to reuse later.

Hence, to get only the int value assigned to a variable:

from pyspark.sql.functions import max, min  

maxValueA = df.agg(max("A")).collect()[0][0]
maxValueB = df.agg(max("B")).collect()[0][0]

MongoDB: How to find the exact version of installed MongoDB

Option1:

Start the console and execute this:

db.version()

Option2:

Open a shell console and do:

$ mongod --version

It will show you something like

$ mongod --version
db version v3.0.2

Calculate average in java

Just some minor modification to your code will do (with some var renaming for clarity) :

double sum = 0; //average will have decimal point

for(int i=0; i < args.length; i++){
   //parse string to double, note that this might fail if you encounter a non-numeric string
   //Note that we could also do Integer.valueOf( args[i] ) but this is more flexible
   sum += Double.valueOf( args[i] ); 
}

double average = sum/args.length;

System.out.println(average );

Note that the loop can also be simplified:

for(String arg : args){
   sum += Double.valueOf( arg );
}

Edit: the OP seems to want to use the args array. This seems to be a String array, thus updated the answer accordingly.

Update:

As zoxqoj correctly pointed out, integer/double overflow is not taken care of in the code above. Although I assume the input values will be small enough to not have that problem, here's a snippet to use for really large input values:

BigDecimal sum = BigDecimal.ZERO;
for(String arg : args){
  sum = sum.add( new BigDecimal( arg ) );
}

This approach has several advantages (despite being somewhat slower, so don't use it for time critical operations):

  • Precision is kept, with double you will gradually loose precision with the number of math operations (or not get exact precision at all, depending on the numbers)
  • The probability of overflow is practically eliminated. Note however, that a BigDecimal might be bigger than what fits into a double or long.

Eloquent ORM laravel 5 Get Array of ids

The correct answer to that is the method lists, it's very simple like this:

$test=test::select('id')->where('id' ,'>' ,0)->lists('id');

Regards!

Sync data between Android App and webserver

@Grantismo gives a great overview of Android sync components.

SyncManagerAndroid library provides a simple 2-way sync implementation to plug into the Android Sync framework (AbstractThreadedSyncAdapter.OnPerformSync).

https://github.com/sschendel/SyncManagerAndroid

How to update column with null value

Remember to look if your column can be null. You can do that using

mysql> desc my_table;

If your column cannot be null, when you set the value to null it will be the cast value to it.

Here a example

mysql> create table example ( age int not null, name varchar(100) not null );
mysql> insert into example values ( null, "without num" ), ( 2 , null );
mysql> select * from example;
+-----+-------------+
| age | name        |
+-----+-------------+
|   0 | without num |
|   2 |             |
+-----+-------------+
2 rows in set (0.00 sec)

mysql> select * from example where age is null or name is null;
Empty set (0.00 sec)

How to change TIMEZONE for a java.util.Calendar/Date

In Java, Dates are internally represented in UTC milliseconds since the epoch (so timezones are not taken into account, that's why you get the same results, as getTime() gives you the mentioned milliseconds).
In your solution:

Calendar cSchedStartCal = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
long gmtTime = cSchedStartCal.getTime().getTime();

long timezoneAlteredTime = gmtTime + TimeZone.getTimeZone("Asia/Calcutta").getRawOffset();
Calendar cSchedStartCal1 = Calendar.getInstance(TimeZone.getTimeZone("Asia/Calcutta"));
cSchedStartCal1.setTimeInMillis(timezoneAlteredTime);

you just add the offset from GMT to the specified timezone ("Asia/Calcutta" in your example) in milliseconds, so this should work fine.

Another possible solution would be to utilise the static fields of the Calendar class:

//instantiates a calendar using the current time in the specified timezone
Calendar cSchedStartCal = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
//change the timezone
cSchedStartCal.setTimeZone(TimeZone.getTimeZone("Asia/Calcutta"));
//get the current hour of the day in the new timezone
cSchedStartCal.get(Calendar.HOUR_OF_DAY);

Refer to stackoverflow.com/questions/7695859/ for a more in-depth explanation.

Nested jQuery.each() - continue/break

return true not work

return false working

found = false;
query = "foo";

$('.items').each(function()
{
  if($(this).text() == query)
  {
    found = true;
    return false;
  }
});

Can I use Class.newInstance() with constructor arguments?

You can use the getDeclaredConstructor method of Class. It expects an array of classes. Here is a tested and working example:

public static JFrame createJFrame(Class c, String name, Component parentComponent)
{
    try
    {
        JFrame frame = (JFrame)c.getDeclaredConstructor(new Class[] {String.class}).newInstance("name");
        if (parentComponent != null)
        {
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        }
        else
        {
            frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        }
        frame.setLocationRelativeTo(parentComponent);
        frame.pack();
        frame.setVisible(true);
    }
    catch (InstantiationException instantiationException)
    {
        ExceptionHandler.handleException(instantiationException, parentComponent, Language.messages.get(Language.InstantiationExceptionKey), c.getName());
    }
    catch(NoSuchMethodException noSuchMethodException)
    {
        //ExceptionHandler.handleException(noSuchMethodException, parentComponent, Language.NoSuchMethodExceptionKey, "NamedConstructor");
        ExceptionHandler.handleException(noSuchMethodException, parentComponent, Language.messages.get(Language.NoSuchMethodExceptionKey), "(Constructor or a JFrame method)");
    }
    catch (IllegalAccessException illegalAccessException)
    {
        ExceptionHandler.handleException(illegalAccessException, parentComponent, Language.messages.get(Language.IllegalAccessExceptionKey));
    }
    catch (InvocationTargetException invocationTargetException)
    {
        ExceptionHandler.handleException(invocationTargetException, parentComponent, Language.messages.get(Language.InvocationTargetExceptionKey));
    }
    finally
    {
        return null;
    }
}

Bootstrap tab activation with JQuery

Add an id attribute to a html tag

<ul class="nav nav-tabs">
    <li><a href="#aaa" data-toggle="tab" id="tab_aaa">AAA</a></li>
    <li><a href="#bbb" data-toggle="tab" id="tab_bbb">BBB</a></li>
    <li><a href="#ccc" data-toggle="tab" id="tab_ccc">CCC</a></li>
</ul>
<div class="tab-content" id="tabs">
    <div class="tab-pane" id="aaa">...Content...</div>
    <div class="tab-pane" id="bbb">...Content...</div>
    <div class="tab-pane" id="ccc">...Content...</div>
</div>

Then using JQuery

$("#tab_aaa").tab('show');

How can I change the Bootstrap default font family using font from Google?

The bootstrap-live-customizer is a good resource for customising your own bootstrap theme and seeing the results live as you customise. Using this website its very easy to just edit the font and then download the updated .css file.

What is the size of a boolean variable in Java?

Size of the boolean in java is virtual machine dependent. but Any Java object is aligned to an 8 bytes granularity. A Boolean has 8 bytes of header, plus 1 byte of payload, for a total of 9 bytes of information. The JVM then rounds it up to the next multiple of 8. so the one instance of java.lang.Boolean takes up 16 bytes of memory.

Python: CSV write by column rather than row

Read it in by row and then transpose it in the command line. If you're using Unix, install csvtool and follow the directions in: https://unix.stackexchange.com/a/314482/186237

Convert String to java.util.Date

It sounds like you may want to use something like SimpleDateFormat. http://java.sun.com/j2se/1.4.2/docs/api/java/text/SimpleDateFormat.html

You declare your date format and then call the parse method with your string.

private static final DateFormat DF = new SimpleDateFormat(...);
Date myDate = DF.parse("1234");

And as Guillaume says, set the timezone!

Is there a way to view past mysql queries with phpmyadmin?

To view the past queries simply run this query in phpMyAdmin.

SELECT * FROM `general_log`

if it is not enabled, run the following two queries before running it.

SET GLOBAL log_output = 'TABLE';
SET GLOBAL general_log = 'ON';

UnsupportedClassVersionError unsupported major.minor version 51.0 unable to load class

Well presumably it's not using the same version of Java when running it externally. Look through the startup scripts carefully to find where it picks up the version of Java to run. You should also check the startup logs to see whether they indicate which version is running.

Alternatively, unless you need the Java 7 features, you could always change your compiler preferences in Eclipse to target 1.6 instead.

Generating all permutations of a given string

public static void permutation(String str) { 
    permutation("", str); 
}

private static void permutation(String prefix, String str) {
    int n = str.length();
    if (n == 0) System.out.println(prefix);
    else {
        for (int i = 0; i < n; i++)
            permutation(prefix + str.charAt(i), str.substring(0, i) + str.substring(i+1, n));
    }
}

(via Introduction to Programming in Java)

Convert DateTime to long and also the other way around

From long to DateTime: new DateTime(long ticks)

From DateTime to long: DateTime.Ticks

java.lang.IllegalStateException: Fragment not attached to Activity

Fragment lifecycle is very complex and full of bugs, try to add:

Activity activity = getActivity(); 
if (isAdded() && activity != null) {
...
}

PHP header redirect 301 - what are the implications?

This is better:

<?php
//* Permanently redirect page
header("Location: new_page.php",TRUE,301);
?>

Just one call including code 301. Also notice the relative path to the file in the same directory (not "/dir/dir/new_page.php", etc.), which all modern browsers seem to support.

I think this is valid since PHP 5.1.2, possibly earlier.

AlertDialog.Builder with custom layout and EditText; cannot access view

View v=inflater.inflate(R.layout.alert_label_editor, null);
alertDialog.setContentView(v);
EditText editText = (EditText)v.findViewById(R.id.label_field);
editText.setText("test label");
alertDialog.show();

Loop through each cell in a range of cells when given a Range object

You could use Range.Rows, Range.Columns or Range.Cells. Each of these collections contain Range objects.

Here's how you could modify Dick's example so as to work with Rows:

Sub LoopRange()

    Dim rCell As Range
    Dim rRng As Range

    Set rRng = Sheet1.Range("A1:A6")

    For Each rCell In rRng.Rows
        Debug.Print rCell.Address, rCell.Value
    Next rCell

End Sub

And Columns:

Sub LoopRange()

    Dim rCell As Range
    Dim rRng As Range

    Set rRng = Sheet1.Range("A1:A6")

    For Each rCol In rRng.Columns
        For Each rCell In rCol.Rows
            Debug.Print rCell.Address, rCell.Value
        Next rCell
    Next rCol

End Sub

struct.error: unpack requires a string argument of length 4

By default, on many platforms the short will be aligned to an offset at a multiple of 2, so there will be a padding byte added after the char.

To disable this, use: struct.unpack("=BH", data). This will use standard alignment, which doesn't add padding:

>>> struct.calcsize('=BH')
3

The = character will use native byte ordering. You can also use < or > instead of = to force little-endian or big-endian byte ordering, respectively.

Number input type that takes only integers?

have you tried setting the step attribute to 1 like this

<input type="number" step="1" /> 

CSS ''background-color" attribute not working on checkbox inside <div>

Improving another answer here

input[type=checkbox] {
  cursor: pointer;
  margin-right: 10px;
}

input[type=checkbox]:after {
  content: " ";
  background-color: lightgray;
  display: inline-block;
  position: relative;
  top: -4px;
  width: 24px;
  height: 24px;
  margin-right: 10px;
}

input[type=checkbox]:checked:after {
  content: "\00a0\2714";
}

jQuery hyperlinks - href value?

I know this is old but wow, there's such an easy solution.

remove the "href" entirely and just add a class that does the following:

.no-href { cursor:pointer: }

And that's it!

jQuery find events handlers registered with an object

I created a custom jQuery selector that checks against both jQuery's cache of assigned event handlers as well as elements that use the native method for adding them:

(function($){

    $.find.selectors[":"].event = function(el, pos, match) {

        var search = (function(str){
            if (str.substring(0,2) === "on") {str = str.substring(2);}
            return str;
        })(String(match[3]).trim().toLowerCase());

        if (search) {
            var events = $._data(el, "events");
            return ((events && events.hasOwnProperty(search)) || el["on"+search]);
        }

        return false;

    };

})(jQuery);

Example:

$(":event(click)")

This will return elements that have a click handler attached to them.

MySQL Workbench Edit Table Data is read only

MySQL will run in Read-Only mode when you fetch by joining two tables and columns from two tables are included in the result. Then you can't update the values directly.

How to print Unicode character in Python?

If you're trying to print() Unicode, and getting ascii codec errors, check out this page, the TLDR of which is do export PYTHONIOENCODING=UTF-8 before firing up python (this variable controls what sequence of bytes the console tries to encode your string data as). Internally, Python3 uses UTF-8 by default (see the Unicode HOWTO) so that's not the problem; you can just put Unicode in strings, as seen in the other answers and comments. It's when you try and get this data out to your console that the problem happens. Python thinks your console can only handle ascii. Some of the other answers say, "Write it to a file, first" but note they specify the encoding (UTF-8) for doing so (so, Python doesn't change anything in writing), and then use a method for reading the file that just spits out the bytes without any regard for encoding, which is why that works.

Define a fixed-size list in Java

Yes,

Commons library provides a built-in FixedSizeList which does not support the add, remove and clear methods (but the set method is allowed because it does not modify the List's size). In other words, if you try to call one of these methods, your list still retain the same size.

To create your fixed size list, just call

List<YourType> fixed = FixedSizeList.decorate(Arrays.asList(new YourType[100]));

You can use unmodifiableList if you want an unmodifiable view of the specified list, or read-only access to internal lists.

List<YourType> unmodifiable = java.util.Collections.unmodifiableList(internalList);

Python Pandas Counting the Occurrences of a Specific value

Couple of ways using count or sum

In [338]: df
Out[338]:
  col1 education
0    a       9th
1    b       9th
2    c       8th

In [335]: df.loc[df.education == '9th', 'education'].count()
Out[335]: 2

In [336]: (df.education == '9th').sum()
Out[336]: 2

In [337]: df.query('education == "9th"').education.count()
Out[337]: 2

Best XML parser for Java

Here is a nice comparision on DOM, SAX, StAX & TrAX (Source: http://download.oracle.com/docs/cd/E17802_01/webservices/webservices/docs/1.6/tutorial/doc/SJSXP2.html )

Feature                  StAX                  SAX                      DOM                  TrAX

API Type                Pull,streaming     Push,streaming    In memory tree    XSLT Rule

Ease of Use          High                    Medium                 High                    Medium

XPath Capability   No                       No                        Yes                      Yes

CPU & Memory     Good                  Good                    Varies                  Varies

Forward Only        Yes                    Yes                        No                       No

Read XML              Yes                    Yes                        Yes                     Yes

Write XML              Yes                    No                          Yes                     Yes

CRUD                      No                      No                         Yes                     No

Jackson and generic type reference

'JavaType' works !! I was trying to unmarshall (deserialize) a List in json String to ArrayList java Objects and was struggling to find a solution since days.
Below is the code that finally gave me solution. Code:

JsonMarshallerUnmarshaller<T> {
    T targetClass;

    public ArrayList<T> unmarshal(String jsonString) {
        ObjectMapper mapper = new ObjectMapper();

        AnnotationIntrospector introspector = new JacksonAnnotationIntrospector();
        mapper.getDeserializationConfig()
            .withAnnotationIntrospector(introspector);

        mapper.getSerializationConfig()
            .withAnnotationIntrospector(introspector);
        JavaType type = mapper.getTypeFactory().
            constructCollectionType(
                ArrayList.class, 
                targetclass.getClass());

        try {
            Class c1 = this.targetclass.getClass();
            Class c2 = this.targetclass1.getClass();
            ArrayList<T> temp = (ArrayList<T>) 
                mapper.readValue(jsonString,  type);
            return temp ;
        } catch (JsonParseException e) {
            e.printStackTrace();
        } catch (JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null ;
    }  
}

How to create custom exceptions in Java?

public class MyException extends Exception {
        // special exception code goes here
}

Throw it as:

 throw new MyException ("Something happened")

Catch as:

catch (MyException e)
{
   // something
}

How to preSelect an html dropdown list with php?

I have 2 php files and i made this, and it works. (this is an example) the first code is from the one file and the second code from two file.

<form action="two.php" method="post">
<input type="submit" class="button" value="submit" name="one"/>
<select name="numbers">
<option value="1"> 1 </option>
<option value="2"> 2 </option>
<option value="3"> 3 </option>
</select>
</form>



if(isset ($_POST['one']))
{

if($_POST['numbers']=='1')
{
$a='1' ;
}
else if($_POST['numbers']=='2')
{
$a='2' ;
{
else if ($_POST['numbers']=='3')
{
$a='3' ;
}

}

Can't execute jar- file: "no main manifest attribute"

If using Maven, include following in the pom

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.4.2.RELEASE</version>
</parent>

<properties>
    <java.version>1.8</java.version>
</properties>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

Trusting all certificates using HttpClient over HTTPS

work with all https

httpClient = new DefaultHttpClient();

SSLContext ctx = SSLContext.getInstance("TLS");
X509TrustManager tm = new X509TrustManager() {
    public void checkClientTrusted(X509Certificate[] xcs, String string) throws CertificateException { }

    public void checkServerTrusted(X509Certificate[] xcs, String string) throws CertificateException { }

    public X509Certificate[] getAcceptedIssuers() {
        return null;
    }
};

ctx.init(null, new TrustManager[]{tm}, null);
SSLSocketFactory ssf = new SSLSocketFactory(ctx, SSLSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);

httpClient.getConnectionManager().getSchemeRegistry().register(new Scheme("https", 443, ssf));

Reading a plain text file in Java

My favorite way to read a small file is to use a BufferedReader and a StringBuilder. It is very simple and to the point (though not particularly effective, but good enough for most cases):

BufferedReader br = new BufferedReader(new FileReader("file.txt"));
try {
    StringBuilder sb = new StringBuilder();
    String line = br.readLine();

    while (line != null) {
        sb.append(line);
        sb.append(System.lineSeparator());
        line = br.readLine();
    }
    String everything = sb.toString();
} finally {
    br.close();
}

Some has pointed out that after Java 7 you should use try-with-resources (i.e. auto close) features:

try(BufferedReader br = new BufferedReader(new FileReader("file.txt"))) {
    StringBuilder sb = new StringBuilder();
    String line = br.readLine();

    while (line != null) {
        sb.append(line);
        sb.append(System.lineSeparator());
        line = br.readLine();
    }
    String everything = sb.toString();
}

When I read strings like this, I usually want to do some string handling per line anyways, so then I go for this implementation.

Though if I want to actually just read a file into a String, I always use Apache Commons IO with the class IOUtils.toString() method. You can have a look at the source here:

http://www.docjar.com/html/api/org/apache/commons/io/IOUtils.java.html

FileInputStream inputStream = new FileInputStream("foo.txt");
try {
    String everything = IOUtils.toString(inputStream);
} finally {
    inputStream.close();
}

And even simpler with Java 7:

try(FileInputStream inputStream = new FileInputStream("foo.txt")) {     
    String everything = IOUtils.toString(inputStream);
    // do something with everything string
}

Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column 2

Response you are getting is in object form i.e.

{ 
  "dstOffset" : 3600, 
  "rawOffset" : 36000, 
  "status" : "OK", 
  "timeZoneId" : "Australia/Hobart", 
  "timeZoneName" : "Australian Eastern Daylight Time" 
}

Replace below line of code :

List<Post> postsList = Arrays.asList(gson.fromJson(reader,Post.class))

with

Post post = gson.fromJson(reader, Post.class);

System.MissingMethodException: Method not found?

In my case it was a folder with olders DLLs of the same name that those wich were referenced in my .csproj file although the path was explicitly given they were somehow included therefore the several versions of the same DLLs were in conflict.

How to set div's height in css and html

<div style="height: 100px;"> </div>

OR

<div id="foo"/> and set the style as #foo { height: 100px; }
<div class="bar"/> and set the style as .bar{ height: 100px;  }

How to access SVG elements with Javascript

In case you use jQuery you need to wait for $(window).load, because the embedded SVG document might not be yet loaded at $(document).ready

$(window).load(function () {

    //alert("Document loaded, including graphics and embedded documents (like SVG)");
    var a = document.getElementById("alphasvg");

    //get the inner DOM of alpha.svg
    var svgDoc = a.contentDocument;

    //get the inner element by id
    var delta = svgDoc.getElementById("delta");
    delta.addEventListener("mousedown", function(){ alert('hello world!')}, false);
});

Simplest PHP example for retrieving user_timeline with Twitter API version 1.1

From their signature generator, you can generate curl commands of the form:

curl --get 'https://api.twitter.com/1.1/statuses/user_timeline.json' --data 'count=2&screen_name=twitterapi' --header 'Authorization: OAuth oauth_consumer_key="YOUR_KEY", oauth_nonce="YOUR_NONCE", oauth_signature="YOUR-SIG", oauth_signature_method="HMAC-SHA1", oauth_timestamp="TIMESTAMP", oauth_token="YOUR-TOKEN", oauth_version="1.0"' --verbose

SQL comment header examples

See if this suits your requirement:

/*  

* Notes on parameters: Give the details of all parameters supplied to the proc  

* This procedure will perform the following tasks: 
 Give details description of the intent of the proc  

* Additional notes: 
Give information of something that you think needs additional mention, though is not directly related to the proc  

* Modification History:
  07/11/2001    ACL    TICKET/BUGID        CHANGE DESCRIPTION


*/

Loading existing .html file with android WebView

You could read the html file manually and then use loadData or loadDataWithBaseUrl methods of WebView to show it.

javascript cell number validation

function IsMobileNumber(txtMobId) {
    var mob = /^[1-9]{1}[0-9]{9}$/;
    var txtMobile = document.getElementById(txtMobId);
    if (mob.test(txtMobile.value) == false) {
        alert("Please enter valid mobile number.");
        txtMobile.focus();
        return false;
    }
    return true;
}

Calling Validation Mobile Number Function HTML Code -

what is .subscribe in angular?

In Angular (currently on Angular-6) .subscribe() is a method on the Observable type. The Observable type is a utility that asynchronously or synchronously streams data to a variety of components or services that have subscribed to the observable.

The observable is an implementation/abstraction over the promise chain and will be a part of ES7 as a proposed and very supported feature. In Angular it is used internally due to rxjs being a development dependency.

An observable itself can be thought of as a stream of data coming from a source, in Angular this source is an API-endpoint, a service, a database or another observable. But the power it has is that it's not expecting a single response. It can have one or many values that are returned.

Link to rxjs for observable/subscribe docs here: https://rxjs-dev.firebaseapp.com/api/index/class/Observable#subscribe-

Subscribe takes 3 methods as parameters each are functions:

  • next: For each item being emitted by the observable perform this function
  • error: If somewhere in the stream an error is found, do this method
  • complete: Once all items are complete from the stream, do this method

Within each of these, there is the potentional to pipe (or chain) other utilities called operators onto the results to change the form or perform some layered logic.

In the simple example above:

.subscribe(hero => this.hero = hero); basically says on this observable take the hero being emitted and set it to this.hero.

Adding this answer to give more context to Observables based off the documentation and my understanding.

Server certificate verification failed: issuer is not trusted

The other answers don't work for me. I'm trying to get the command line working in Jenkins. All you need are the following command line arguments:

--non-interactive

--trust-server-cert

When to use virtual destructors?

I like to think about interfaces and implementations of interfaces. In C++ speak interface is pure virtual class. Destructor is part of the interface and expected to implemented. Therefore destructor should be pure virtual. How about constructor? Constructor is actually not part of the interface because object is always instantiated explicitly.

Caching a jquery ajax response in javascript/browser

I was looking for caching for my phonegap app storage and I found the answer of @TecHunter which is great but done using localCache.

I found and come to know that localStorage is another alternative to cache the data returned by ajax call. So, I created one demo using localStorage which will help others who may want to use localStorage instead of localCache for caching.

Ajax Call:

$.ajax({
    type: "POST",
    dataType: 'json',
    contentType: "application/json; charset=utf-8",
    url: url,
    data: '{"Id":"' + Id + '"}',
    cache: true, //It must "true" if you want to cache else "false"
    //async: false,
    success: function (data) {
        var resData = JSON.parse(data);
        var Info = resData.Info;
        if (Info) {
            customerName = Info.FirstName;
        }
    },
    error: function (xhr, textStatus, error) {
        alert("Error Happened!");
    }
});

To store data into localStorage:

$.ajaxPrefilter(function (options, originalOptions, jqXHR) {
if (options.cache) {
    var success = originalOptions.success || $.noop,
        url = originalOptions.url;

    options.cache = false; //remove jQuery cache as we have our own localStorage
    options.beforeSend = function () {
        if (localStorage.getItem(url)) {
            success(localStorage.getItem(url));
            return false;
        }
        return true;
    };
    options.success = function (data, textStatus) {
        var responseData = JSON.stringify(data.responseJSON);
        localStorage.setItem(url, responseData);
        if ($.isFunction(success)) success(responseJSON); //call back to original ajax call
    };
}
});

If you want to remove localStorage, use following statement wherever you want:

localStorage.removeItem("Info");

Hope it helps others!

"Could not find bundler" error

I had this problem, then I did:

gem install bundle

notice "bundle" not "bundler" solved my problem.

then in your project folder do:

bundle install

and then you can run your project using:

script/rails server

How to delete Tkinter widgets from a window?

One way you can do it, is to get the slaves list from the frame that needs to be cleared and destroy or "hide" them according to your needs. To get a clear frame you can do it like this:

from tkinter import *

root = Tk()

def clear():
    list = root.grid_slaves()
    for l in list:
        l.destroy()

Label(root,text='Hello World!').grid(row=0)
Button(root,text='Clear',command=clear).grid(row=1)

root.mainloop()

You should call grid_slaves(), pack_slaves() or slaves() depending on the method you used to add the widget to the frame.

How to slice an array in Bash

Array slicing like in Python (From the rebash library):

array_slice() {
    local __doc__='
    Returns a slice of an array (similar to Python).

    From the Python documentation:
    One way to remember how slices work is to think of the indices as pointing
    between elements, with the left edge of the first character numbered 0.
    Then the right edge of the last element of an array of length n has
    index n, for example:
    ```
    +---+---+---+---+---+---+
    | 0 | 1 | 2 | 3 | 4 | 5 |
    +---+---+---+---+---+---+
    0   1   2   3   4   5   6
    -6  -5  -4  -3  -2  -1
    ```

    >>> local a=(0 1 2 3 4 5)
    >>> echo $(array.slice 1:-2 "${a[@]}")
    1 2 3
    >>> local a=(0 1 2 3 4 5)
    >>> echo $(array.slice 0:1 "${a[@]}")
    0
    >>> local a=(0 1 2 3 4 5)
    >>> [ -z "$(array.slice 1:1 "${a[@]}")" ] && echo empty
    empty
    >>> local a=(0 1 2 3 4 5)
    >>> [ -z "$(array.slice 2:1 "${a[@]}")" ] && echo empty
    empty
    >>> local a=(0 1 2 3 4 5)
    >>> [ -z "$(array.slice -2:-3 "${a[@]}")" ] && echo empty
    empty
    >>> [ -z "$(array.slice -2:-2 "${a[@]}")" ] && echo empty
    empty

    Slice indices have useful defaults; an omitted first index defaults to
    zero, an omitted second index defaults to the size of the string being
    sliced.
    >>> local a=(0 1 2 3 4 5)
    >>> # from the beginning to position 2 (excluded)
    >>> echo $(array.slice 0:2 "${a[@]}")
    >>> echo $(array.slice :2 "${a[@]}")
    0 1
    0 1

    >>> local a=(0 1 2 3 4 5)
    >>> # from position 3 (included) to the end
    >>> echo $(array.slice 3:"${#a[@]}" "${a[@]}")
    >>> echo $(array.slice 3: "${a[@]}")
    3 4 5
    3 4 5

    >>> local a=(0 1 2 3 4 5)
    >>> # from the second-last (included) to the end
    >>> echo $(array.slice -2:"${#a[@]}" "${a[@]}")
    >>> echo $(array.slice -2: "${a[@]}")
    4 5
    4 5

    >>> local a=(0 1 2 3 4 5)
    >>> echo $(array.slice -4:-2 "${a[@]}")
    2 3

    If no range is given, it works like normal array indices.
    >>> local a=(0 1 2 3 4 5)
    >>> echo $(array.slice -1 "${a[@]}")
    5
    >>> local a=(0 1 2 3 4 5)
    >>> echo $(array.slice -2 "${a[@]}")
    4
    >>> local a=(0 1 2 3 4 5)
    >>> echo $(array.slice 0 "${a[@]}")
    0
    >>> local a=(0 1 2 3 4 5)
    >>> echo $(array.slice 1 "${a[@]}")
    1
    >>> local a=(0 1 2 3 4 5)
    >>> array.slice 6 "${a[@]}"; echo $?
    1
    >>> local a=(0 1 2 3 4 5)
    >>> array.slice -7 "${a[@]}"; echo $?
    1
    '
    local start end array_length length
    if [[ $1 == *:* ]]; then
        IFS=":"; read -r start end <<<"$1"
        shift
        array_length="$#"
        # defaults
        [ -z "$end" ] && end=$array_length
        [ -z "$start" ] && start=0
        (( start < 0 )) && let "start=(( array_length + start ))"
        (( end < 0 )) && let "end=(( array_length + end ))"
    else
        start="$1"
        shift
        array_length="$#"
        (( start < 0 )) && let "start=(( array_length + start ))"
        let "end=(( start + 1 ))"
    fi
    let "length=(( end - start ))"
    (( start < 0 )) && return 1
    # check bounds
    (( length < 0 )) && return 1
    (( start < 0 )) && return 1
    (( start >= array_length )) && return 1
    # parameters start with $1, so add 1 to $start
    let "start=(( start + 1 ))"
    echo "${@: $start:$length}"
}
alias array.slice="array_slice"

ValidateRequest="false" doesn't work in Asp.Net 4

Found solution on the error page itself. Just needed to add requestValidationMode="2.0" in web.config

<system.web>
    <compilation debug="true" targetFramework="4.0" />
    <httpRuntime requestValidationMode="2.0" />
</system.web>

MSDN information: HttpRuntimeSection.RequestValidationMode Property

Simulate a click on 'a' element using javascript/jquery

Using jQuery:

$('#gift-close').click();

How to replace a set of tokens in a Java String?

It depends of where the actual data that you want to replace is located. You might have a Map like this:

Map<String, String> values = new HashMap<String, String>();

containing all the data that can be replaced. Then you can iterate over the map and change everything in the String as follows:

String s = "Your String with [Fields]";
for (Map.Entry<String, String> e : values.entrySet()) {
  s = s.replaceAll("\\[" + e.getKey() + "\\]", e.getValue());
}

You could also iterate over the String and find the elements in the map. But that is a little bit more complicated because you need to parse the String searching for the []. You could do it with a regular expression using Pattern and Matcher.

HttpClient not supporting PostAsJsonAsync method C#

For me I found the solution after a lot of try which is replacing

HttpClient

with

System.Net.Http.HttpClient

simple HTTP server in Java using only Java SE API

Once upon a time I was looking for something similar - a lightweight yet fully functional HTTP server that I could easily embed and customize. I found two types of potential solutions:

  • Full servers that are not all that lightweight or simple (for an extreme definition of lightweight.)
  • Truly lightweight servers that aren't quite HTTP servers, but glorified ServerSocket examples that are not even remotely RFC-compliant and don't support commonly needed basic functionality.

So... I set out to write JLHTTP - The Java Lightweight HTTP Server.

You can embed it in any project as a single (if rather long) source file, or as a ~50K jar (~35K stripped) with no dependencies. It strives to be RFC-compliant and includes extensive documentation and many useful features while keeping bloat to a minimum.

Features include: virtual hosts, file serving from disk, mime type mappings via standard mime.types file, directory index generation, welcome files, support for all HTTP methods, conditional ETags and If-* header support, chunked transfer encoding, gzip/deflate compression, basic HTTPS (as provided by the JVM), partial content (download continuation), multipart/form-data handling for file uploads, multiple context handlers via API or annotations, parameter parsing (query string or x-www-form-urlencoded body), etc.

I hope others find it useful :-)

IllegalArgumentException or NullPointerException for a null parameter?

Actually, the question of throwing IllegalArgumentException or NullPointerException is in my humble view only a "holy war" for a minority with an incomlete understanding of exception handling in Java. In general, the rules are simple, and as follows:

  • argument constraint violations must be indicated as fast as possible (-> fast fail), in order to avoid illegal states which are much harder to debug
  • in case of an invalid null pointer for whatever reason, throw NullPointerException
  • in case of an illegal array/collection index, throw ArrayIndexOutOfBounds
  • in case of a negative array/collection size, throw NegativeArraySizeException
  • in case of an illegal argument that is not covered by the above, and for which you don't have another more specific exception type, throw IllegalArgumentException as a wastebasket
  • on the other hand, in case of a constraint violation WITHIN A FIELD that could not be avoided by fast fail for some valid reason, catch and rethrow as IllegalStateException or a more specific checked exception. Never let pass the original NullPointerException, ArrayIndexOutOfBounds, etc in this case!

There are at least three very good reasons against the case of mapping all kinds of argument constraint violations to IllegalArgumentException, with the third probably being so severe as to mark the practice bad style:

(1) A programmer cannot a safely assume that all cases of argument constraint violations result in IllegalArgumentException, because the large majority of standard classes use this exception rather as a wastebasket if there is no more specific kind of exception available. Trying to map all cases of argument constraint violations to IllegalArgumentException in your API only leads to programmer frustration using your classes, as the standard libraries mostly follow different rules that violate yours, and most of your API users will use them as well!

(2) Mapping the exceptions actually results in a different kind of anomaly, caused by single inheritance: All Java exceptions are classes, and therefore support single inheritance only. Therefore, there is no way to create an exception that is truly say both a NullPointerException and an IllegalArgumentException, as subclasses can only inherit from one or the other. Throwing an IllegalArgumentException in case of a null argument therefore makes it harder for API users to distinguish between problems whenever a program tries to programmatically correct the problem, for example by feeding default values into a call repeat!

(3) Mapping actually creates the danger of bug masking: In order to map argument constraint violations into IllegalArgumentException, you'll need to code an outer try-catch within every method that has any constrained arguments. However, simply catching RuntimeException in this catch block is out of the question, because that risks mapping documented RuntimeExceptions thrown by libery methods used within yours into IllegalArgumentException, even if they are no caused by argument constraint violations. So you need to be very specific, but even that effort doesn't protect you from the case that you accidentally map an undocumented runtime exception of another API (i.e. a bug) into an IllegalArgumentException of your API. Even the most careful mapping therefore risks masking programming errors of other library makers as argument constraint violations of your method's users, which is simply hillareous behavior!

With the standard practice on the other hand, the rules stay simple, and exception causes stay unmasked and specific. For the method caller, the rules are easy as well: - if you encounter a documented runtime exception of any kind because you passed an illegal value, either repeat the call with a default (for this specific exceptions are neccessary), or correct your code - if on the other hand you enccounter a runtime exception that is not documented to happen for a given set of arguments, file a bug report to the method's makers to ensure that either their code or their documentation is fixed.

A simple explanation of Naive Bayes Classification

Naive Bayes: Naive Bayes comes under supervising machine learning which used to make classifications of data sets. It is used to predict things based on its prior knowledge and independence assumptions.

They call it naive because it’s assumptions (it assumes that all of the features in the dataset are equally important and independent) are really optimistic and rarely true in most real-world applications.

It is classification algorithm which makes the decision for the unknown data set. It is based on Bayes Theorem which describe the probability of an event based on its prior knowledge.

Below diagram shows how naive Bayes works

enter image description here

Formula to predict NB:

enter image description here

How to use Naive Bayes Algorithm ?

Let's take an example of how N.B woks

Step 1: First we find out Likelihood of table which shows the probability of yes or no in below diagram. Step 2: Find the posterior probability of each class.

enter image description here

Problem: Find out the possibility of whether the player plays in Rainy condition?

P(Yes|Rainy) = P(Rainy|Yes) * P(Yes) / P(Rainy)

P(Rainy|Yes) = 2/9 = 0.222
P(Yes) = 9/14 = 0.64
P(Rainy) = 5/14 = 0.36

Now, P(Yes|Rainy) = 0.222*0.64/0.36 = 0.39 which is lower probability which means chances of the match played is low.

For more reference refer these blog.

Refer GitHub Repository Naive-Bayes-Examples

'Access denied for user 'root'@'localhost' (using password: NO)'

for this kind of error; you just have to set new password to the root user as an admin. follow the steps as follows:

[root ~]# mysql -u root
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password:NO)
  1. Stop the service/daemon of mysql running

    [root ~]# service mysql stop   
    mysql stop/waiting
    
  2. Start mysql without any privileges using the following option; This option is used to boot up and do not use the privilege system of MySQL.

    [root ~]# mysqld_safe --skip-grant-tables &
    

At this moment, the terminal will seem to halt. Let that be, and use new terminal for next steps.

  1. enter the mysql command prompt

    [root ~]# mysql -u root
    mysql> 
    
  2. Fix the permission setting of the root user ;

    mysql> use mysql;
    Database changed
    mysql> select * from  user;
    Empty set (0.00 sec)
    mysql> truncate table user;
    Query OK, 0 rows affected (0.00 sec)
    mysql> flush privileges;
    Query OK, 0 rows affected (0.01 sec)
    mysql> grant all privileges on *.* to root@localhost identified by 'YourNewPassword' with grant option;
    Query OK, 0 rows affected (0.01 sec)
    

*if you don`t want any password or rather an empty password

    mysql> grant all privileges on *.* to root@localhost identified by '' with grant option;
    Query OK, 0 rows affected (0.01 sec)*
    mysql> flush privileges;
    Query OK, 0 rows affected (0.00 sec)

Confirm the results:

    mysql> select host, user from user;
+-----------+------+
| host      | user |
+-----------+------+
| localhost | root |
+-----------+------+
1 row in set (0.00 sec)
  1. Exit the shell and restart mysql in normal mode.

    mysql> quit;
    [root ~]# kill -KILL [PID of mysqld_safe]
    [root ~]# kill -KILL [PID of mysqld]
    [root ~]# service mysql start
    
  2. Now you can successfully login as root user with the password you set

     [root ~]# mysql -u root -pYourNewPassword 
     mysql> 
    

How to add multiple values to a dictionary key in python?

Make the value a list, e.g.

a["abc"] = [1, 2, "bob"]

UPDATE:

There are a couple of ways to add values to key, and to create a list if one isn't already there. I'll show one such method in little steps.

key = "somekey"
a.setdefault(key, [])
a[key].append(1)

Results:

>>> a
{'somekey': [1]}

Next, try:

key = "somekey"
a.setdefault(key, [])
a[key].append(2)

Results:

>>> a
{'somekey': [1, 2]}

The magic of setdefault is that it initializes the value for that key if that key is not defined, otherwise it does nothing. Now, noting that setdefault returns the key you can combine these into a single line:

a.setdefault("somekey",[]).append("bob")

Results:

>>> a
{'somekey': [1, 2, 'bob']}

You should look at the dict methods, in particular the get() method, and do some experiments to get comfortable with this.

How to pick a new color for each plotted line within a figure in matplotlib?

I don't know if you can automatically change the color, but you could exploit your loop to generate different colors:

for i in range(20):
   ax1.plot(x, y, color = (0, i / 20.0, 0, 1)

In this case, colors will vary from black to 100% green, but you can tune it if you want.

See the matplotlib plot() docs and look for the color keyword argument.

If you want to feed a list of colors, just make sure that you have a list big enough and then use the index of the loop to select the color

colors = ['r', 'b', ...., 'w']

for i in range(20):
   ax1.plot(x, y, color = colors[i])

Sort an array of objects in React and render them

Chrome browser considers integer value as return type not boolean value so,

this.state.data.sort((a, b) => a.item.timeM > b.item.timeM ? 1:-1).map(
    (item, i) => <div key={i}> {item.matchID} {item.timeM} {item.description}</div>
)

Vue-router redirect on page not found (404)

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

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

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

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

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

How do I use sudo to redirect output to a location I don't have permission to write to?

The problem is that the command gets run under sudo, but the redirection gets run under your user. This is done by the shell and there is very little you can do about it.

sudo command > /some/file.log
`-----v-----'`-------v-------'
   command       redirection

The usual ways of bypassing this are:

  • Wrap the commands in a script which you call under sudo.

    If the commands and/or log file changes, you can make the script take these as arguments. For example:

    sudo log_script command /log/file.txt
    
  • Call a shell and pass the command line as a parameter with -c

    This is especially useful for one off compound commands. For example:

    sudo bash -c "{ command1 arg; command2 arg; } > /log/file.txt"
    

HTTP Status 405 - HTTP method POST is not supported by this URL java servlet

if you are using tomcat you may try this

<servlet-mapping>

    <http-method>POST</http-method>

</servlet-mapping>

in addition to <servlet-name> and <url-mapping>

The CSRF token is invalid. Please try to resubmit the form

This seems to be an issue when using bootstrap unless you are rendering the form by {{ form(form)}}. In addition, the issues seems to only occur on input type="hidden". If you inspect the page the with the form, you'll find that the hidden input is not part of the markup at all or it's being rendered but not submitted for some reason. As suggested above, adding {{form_rest(form)}} or wrapping the input like below should do the trick.

<div class="form-group">
    <input type="hidden" name="_csrf_token" value="{{ csrf_token('authenticate') }}">
</div>

codeigniter model error: Undefined property

It solved throung second parameter in Model load:

$this->load->model('user','User');

first parameter is the model's filename, and second it defining the name of model to be used in the controller:

function alluser() 
{
$this->load->model('User');
$result = $this->User->showusers();
}

compilation error: identifier expected

You also will have to catch or throw the IOException. See below. Not always the best way, but it will get you a result:

public class details {
    public static void main( String[] args) throws IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        System.out.println("What is your name?");
        String name = in.readLine(); ;
        System.out.println("Hello " + name);
    }
}

Altering a column to be nullable

For HSQLDB:

ALTER TABLE tableName ALTER COLUMN columnName SET NULL;

How to clear File Input

This is the method I like to use as well but I believe you need to add the bool true parameter to the clone method in order for any events to remain attached with the new object and you need to clear the contents.

    var input = $("#fileInput");

    function clearInput() {
        input = input.val('').clone(true);
    };

https://api.jquery.com/clone/

Could not load file or assembly or one of its dependencies. Access is denied. The issue is random, but after it happens once, it continues

In my case it was due to the Access Protection feature of my anti-virus (McAfee). It was obviously blocking access to this file, as of such the error.

I disabled it and the solution ran. You might want to check any utility application you might have running that could be affecting access to some files.

Get IFrame's document, from JavaScript in main document

The problem is that in IE (which is what I presume you're testing in), the <iframe> element has a document property that refers to the document containing the iframe, and this is getting used before the contentDocument or contentWindow.document properties. What you need is:

function GetDoc(x) {
    return x.contentDocument || x.contentWindow.document;
}

Also, document.all is not available in all browsers and is non-standard. Use document.getElementById() instead.