Programs & Examples On #Argumentexception

An ArgumentException is a specific exception in the .NET framework thrown when one of the arguments provided to a method is not valid.

How to check if a column exists in a datatable

DataColumnCollection col = datatable.Columns;        
if (!columns.Contains("ColumnName1"))
{
   //Column1 Not Exists
}

if (columns.Contains("ColumnName2"))
{
   //Column2 Exists
}

"Parameter not valid" exception loading System.Drawing.Image

My guess is that byteArrayIn doesn't contain valid image data.

Please give more information though:

  • Which line of code is throwing an exception?
  • What's the message?
  • Where did you get byteArrayIn from, and are you sure it should contain a valid image?

Invalid postback or callback argument. Event validation is enabled using '<pages enableEventValidation="true"/>'

In this case add id to the button in RowDataBound of the grid. It will solve your problem.

Eclipse - Installing a new JRE (Java SE 8 1.8.0)

You can have many java versions in your system.

I think you should add the java 8 in yours JREs installed or edit.

Take a look my screen:

enter image description here

If you click in edit (check your java 8 path):

enter image description here

File path to resource in our war/WEB-INF folder?

There's a couple ways of doing this. As long as the WAR file is expanded (a set of files instead of one .war file), you can use this API:

ServletContext context = getContext();
String fullPath = context.getRealPath("/WEB-INF/test/foo.txt");

http://tomcat.apache.org/tomcat-5.5-doc/servletapi/javax/servlet/ServletContext.html#getRealPath(java.lang.String)

That will get you the full system path to the resource you are looking for. However, that won't work if the Servlet Container never expands the WAR file (like Tomcat). What will work is using the ServletContext's getResource methods.

ServletContext context = getContext();
URL resourceUrl = context.getResource("/WEB-INF/test/foo.txt");

or alternatively if you just want the input stream:

InputStream resourceContent = context.getResourceAsStream("/WEB-INF/test/foo.txt");

http://tomcat.apache.org/tomcat-5.5-doc/servletapi/javax/servlet/ServletContext.html#getResource(java.lang.String)

The latter approach will work no matter what Servlet Container you use and where the application is installed. The former approach will only work if the WAR file is unzipped before deployment.

EDIT: The getContext() method is obviously something you would have to implement. JSP pages make it available as the context field. In a servlet you get it from your ServletConfig which is passed into the servlet's init() method. If you store it at that time, you can get your ServletContext any time you want after that.

Convert seconds to Hour:Minute:Second

If you need to do that in javascript, you can do it in just one line of code as answered here Convert seconds to HH-MM-SS with JavaScript. Replace SECONDS with what you want to convert.

var time = new Date(SECONDS * 1000).toISOString().substr(11, 8);

PHP Notice: Undefined offset: 1 with array when reading data

The output of the error, is because you call an index of the Array that does not exist, for example

$arr = Array(1,2,3);
echo $arr[3]; 
// Error PHP Notice:  Undefined offset: 1 pointer 3 does not exist, the array only has 3 elements but starts at 0 to 2, not 3!

Best timestamp format for CSV/Excel?

Go to the language settings in the Control Panel, then Format Options, select a locale and see the actual date format for the chosen locale used by Windows by default. Yes, that timestamp format is locale-sensitive. Excel uses those formats when parsing CSV.

Even further, if the locale uses characters beyond ASCII, you'll have to emit CSV in the corresponding pre-Unicode Windows "ANSI" codepage, e.g. CP1251. Excel won't accept UTF-8.

Node.js - EJS - including a partial

In oficial documentation https://github.com/mde/ejs#includes show that includes works like that:

<%- include('../partials/head') %>

Why AVD Manager options are not showing in Android Studio

Should be something to do with your Platform Settings. Try the below steps

  1. Go to Project Structure -> Platform Settings -> SDKs
  2. Select available SDK's as shown in screenshots
  3. Re-start the Android Studio
  4. Android will detect the framework in the right corner. Click on it
  5. Then click ok as shown in second screenshot

SDK's Setup Frameworks

jQuery if checkbox is checked

for jQuery 1.6 or higher:

if ($('input.checkbox_check').prop('checked')) {
    //blah blah
}

the cross-browser-compatible way to determine if a checkbox is checked is to use the property https://api.jquery.com/prop/

How to convert the time from AM/PM to 24 hour format in PHP?

$time = '09:15 AM';

$chunks = explode(':', $time);
if (strpos( $time, 'AM') === false && $chunks[0] !== '12') {
    $chunks[0] = $chunks[0] + 12;
} else if (strpos( $time, 'PM') === false && $chunks[0] == '12') {
    $chunks[0] = '00';
}

echo preg_replace('/\s[A-Z]+/s', '', implode(':', $chunks));

How should I multiple insert multiple records?

When it are a lot of entries consider to use SqlBulkCopy. The performance is much faster than a series of single inserts.

Including dependencies in a jar with Maven

Have a look at this answer:

I am creating an installer that runs as a Java JAR file and it needs to unpack WAR and JAR files into appropriate places in the installation directory. The dependency plugin can be used in the package phase with the copy goal and it will download any file in the Maven repository (including WAR files) and write them where ever you need them. I changed the output directory to ${project.build.directory}/classes and then end result is that the normal JAR task includes my files just fine. I can then extract them and write them into the installation directory.

<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
    <execution>
        <id>getWar</id>
        <phase>package</phase>
        <goals>
            <goal>copy</goal>
        </goals>
        <configuration>
            <artifactItems>
                <artifactItem>
                    <groupId>the.group.I.use</groupId>
                    <artifactId>MyServerServer</artifactId>
                    <version>${env.JAVA_SERVER_REL_VER}</version>
                    <type>war</type>
                    <destFileName>myWar.war</destFileName>
                </artifactItem>
            </artifactItems>
            <outputDirectory>${project.build.directory}/classes</outputDirectory>
        </configuration>
    </execution>
</executions>

Java Ordered Map

LinkedHashMap maintains the order of the keys.

java.util.LinkedHashMap appears to work just like a normal HashMap otherwise.

Why does an onclick property set with setAttribute fail to work in IE?

Or you could use jQuery and avoid all those issues:

var execBtn = $("<input>", {
       type: "button",
       id: "execBtn",
       value: "Execute"
    })
    .click(runCommand);        

jQuery will take care of all the cross-browser issues as well.

Reading Email using Pop3 in C#

You can also try Mail.dll mail component, it has SSL support, unicode, and multi-national email support:

using(Pop3 pop3 = new Pop3())
{
    pop3.Connect("mail.host.com");           // Connect to server and login
    pop3.Login("user", "password");

    foreach(string uid in pop3.GetAll())
    {
        IMail email = new MailBuilder()
            .CreateFromEml(pop3.GetMessageByUID(uid));
          Console.WriteLine( email.Subject );
    }
    pop3.Close(false);      
}

You can download it here at https://www.limilabs.com/mail

Please note that this is a commercial product I've created.

Simulating group_concat MySQL function in Microsoft SQL Server 2005?

No REAL easy way to do this. Lots of ideas out there, though.

Best one I've found:

SELECT table_name, LEFT(column_names , LEN(column_names )-1) AS column_names
FROM information_schema.columns AS extern
CROSS APPLY
(
    SELECT column_name + ','
    FROM information_schema.columns AS intern
    WHERE extern.table_name = intern.table_name
    FOR XML PATH('')
) pre_trimmed (column_names)
GROUP BY table_name, column_names;

Or a version that works correctly if the data might contain characters such as <

WITH extern
     AS (SELECT DISTINCT table_name
         FROM   INFORMATION_SCHEMA.COLUMNS)
SELECT table_name,
       LEFT(y.column_names, LEN(y.column_names) - 1) AS column_names
FROM   extern
       CROSS APPLY (SELECT column_name + ','
                    FROM   INFORMATION_SCHEMA.COLUMNS AS intern
                    WHERE  extern.table_name = intern.table_name
                    FOR XML PATH(''), TYPE) x (column_names)
       CROSS APPLY (SELECT x.column_names.value('.', 'NVARCHAR(MAX)')) y(column_names) 

Mysql - delete from multiple tables with one query

from two tables with foreign key you can try this Query:

DELETE T1, T2
FROM T1
INNER JOIN T2 ON T1.key = T2.key
WHERE condition

Can I load a .NET assembly at runtime and instantiate a type knowing only the name?

Consider the limitations of the different Load* methods. From the MSDN docs...

LoadFile does not load files into the LoadFrom context, and does not resolve dependencies using the load path, as the LoadFrom method does.

More information on Load Contexts can be found in the LoadFrom docs.

Gradle store on local file system

Gradle's local repository folder is:

  • $USER_HOME/.gradle/caches/modules-2/files-2.1

Defined dependencies will be loaded from remote repositories into gradle's local repository folder. For each loaded file, gradle will be create a new folder named with md5 value of the original file (pom,jar,..). Full path for the dependency file is made up from :

  • groupid + artifactid + version + FILE_MD5_VALUE + FILE_NAME

If our defined dependency is:

  • compile 'org.springframework:spring-jdbc:4.3.4.RELEASE'

Then the library will be loaded into :

  • /$USER_HOME/.gradle/caches/modules-2/files-2.1/org.springframework/spring-jdbc/4.3.4.RELEASE/42175d194cf6aa7c716c0887f30255e5c0a5262c/spring-jdbc-4.3.4.RELEASE.jar

What is the use of static synchronized method in java?

Java VM contains a single class object per class. Each class may have some shared variables called static variables. If the critical section of the code plays with these variables in a concurrent environment, then we need to make that particular section as synchronized. When there is more than one static synchronized method only one of them will be executed at a time without preemption. That's what lock on class object does.

How to find EOF through fscanf?

If you have integers in your file fscanf returns 1 until integer occurs. For example:

FILE *in = fopen("./task.in", "r");
int length = 0;
int counter;
int sequence;

for ( int i = 0; i < 10; i++ ) {
    counter = fscanf(in, "%d", &sequence);
    if ( counter == 1 ) {
        length += 1;
    }
}

To find out the end of the file with symbols you can use EOF. For example:

char symbol;
FILE *in = fopen("./task.in", "r");

for ( ; fscanf(in, "%c", &symbol) != EOF; ) {
    printf("%c", symbol); 
}

How to convert JSON to a Ruby hash

You could also use Rails' with_indifferent_access method so you could access the body with either symbols or strings.

value = '{"val":"test","val1":"test1","val2":"test2"}'
json = JSON.parse(value).with_indifferent_access

then

json[:val] #=> "test"

json["val"] #=> "test"

how to hide a vertical scroll bar when not needed

overflow: auto; or overflow: hidden; should do it I think.

How to implement a secure REST API with node.js

There are many questions about REST auth patterns here on SO. These are the most relevant for your question:

Basically you need to choose between using API keys (least secure as the key may be discovered by an unauthorized user), an app key and token combo (medium), or a full OAuth implementation (most secure).

Int or Number DataType for DataAnnotation validation attribute

Try this attribute :

public class NumericAttribute : ValidationAttribute, IClientValidatable {

    public override bool IsValid(object value) {
        return value.ToString().All(c => (c >= '0' && c <= '9') || c == '-' || c == ' ');
    }


    public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context) {
        var rule = new ModelClientValidationRule
        {
            ErrorMessage = FormatErrorMessage(metadata.DisplayName),
            ValidationType = "numeric"
        };
        yield return rule;
    }
}

And also you must register the attribute in the validator plugin:

if($.validator){
     $.validator.unobtrusive.adapters.add(
        'numeric', [], function (options) {
            options.rules['numeric'] = options.params;
            options.messages['numeric'] = options.message;
        }
    );
}

How to process SIGTERM signal gracefully?

Found easiest way for me. Here an example with fork for clarity that this way is useful for flow control.

import signal
import time
import sys
import os

def handle_exit(sig, frame):
    raise(SystemExit)

def main():
    time.sleep(120)

signal.signal(signal.SIGTERM, handle_exit)

p = os.fork()
if p == 0:
    main()
    os._exit()

try:
    os.waitpid(p, 0)
except (KeyboardInterrupt, SystemExit):
    print('exit handled')
    os.kill(p, 15)
    os.waitpid(p, 0)

adding noise to a signal in python

You can generate a noise array, and add it to your signal

import numpy as np

noise = np.random.normal(0,1,100)

# 0 is the mean of the normal distribution you are choosing from
# 1 is the standard deviation of the normal distribution
# 100 is the number of elements you get in array noise

CSS full screen div with text in the middle

The standard approach is to give the centered element fixed dimensions, and place it absolutely:

<div class='fullscreenDiv'>
    <div class="center">Hello World</div>
</div>?

.center {
    position: absolute;
    width: 100px;
    height: 50px;
    top: 50%;
    left: 50%;
    margin-left: -50px; /* margin is -0.5 * dimension */
    margin-top: -25px; 
}?

What JSON library to use in Scala?

@AlaxDean's #7 answer, Argonaut is the only one that I was able to get working quickly with sbt and intellij. Actually json4s also took little time but dealing with a raw AST is not what I wanted. I got argonaut to work by putting in a single line into my build.st:

libraryDependencies += "io.argonaut" %% "argonaut" % "6.0.1"

And then a simple test to see if it I could get JSON:

package mytest


import scalaz._, Scalaz._
import argonaut._, Argonaut._

object Mytest extends App {

  val requestJson  =
    """
    {
      "userid": "1"
    }
    """.stripMargin

  val updatedJson: Option[Json] = for {
    parsed <- requestJson.parseOption
  } yield ("name", jString("testuser")) ->: parsed

  val obj = updatedJson.get.obj
  printf("Updated user: %s\n", updatedJson.toString())
  printf("obj : %s\n", obj.toString())
  printf("userid: %s\n", obj.get.toMap("userid"))
}

And then

$ sbt
> run
Updated user: Some({"userid":"1","name":"testuser"})
obj : Some(object[("userid","1"),("name","testuser")])
userid: "1"

Make sure you are familiar with Option which is just a value that can also be null (null safe I guess). Argonaut makes use of Scalaz so if you see something you don't understand like the symbol \/ (an or operation) it's probably Scalaz.

how to set font size based on container size?

I had a similar issue but I had to consider other issues that @apaul34208 example did not tackle. In my case;

  • I have a container that changed size depending on the viewport using media queries
  • Text inside is dynamically generated
  • I want to scale up as well as down

Not the most elegant of examples but it does the trick for me. Consider using throttling the window resize (https://lodash.com/)

_x000D_
_x000D_
var TextFit = function(){_x000D_
 var container = $('.container');_x000D_
  container.each(function(){_x000D_
    var container_width = $(this).width(),_x000D_
      width_offset = parseInt($(this).data('width-offset')),_x000D_
        font_container = $(this).find('.font-container');_x000D_
 _x000D_
     if ( width_offset > 0 ) {_x000D_
         container_width -= width_offset;_x000D_
     }_x000D_
                _x000D_
    font_container.each(function(){_x000D_
      var font_container_width = $(this).width(),_x000D_
          font_size = parseFloat( $(this).css('font-size') );_x000D_
_x000D_
      var diff = Math.max(container_width, font_container_width) - Math.min(container_width, font_container_width);_x000D_
 _x000D_
      var diff_percentage = Math.round( ( diff / Math.max(container_width, font_container_width) ) * 100 );_x000D_
      _x000D_
      if (diff_percentage !== 0){_x000D_
          if ( container_width > font_container_width ) {_x000D_
            new_font_size = font_size + Math.round( ( font_size / 100 ) * diff_percentage );_x000D_
          } else if ( container_width < font_container_width ) {_x000D_
            new_font_size = font_size - Math.round( ( font_size / 100 ) * diff_percentage );_x000D_
          }_x000D_
      }_x000D_
      $(this).css('font-size', new_font_size + 'px');_x000D_
    });_x000D_
  });_x000D_
}_x000D_
_x000D_
$(function(){_x000D_
  TextFit();_x000D_
  $(window).resize(function(){_x000D_
   TextFit();_x000D_
  });_x000D_
});
_x000D_
.container {_x000D_
  width:341px;_x000D_
  height:341px;_x000D_
  background-color:#000;_x000D_
  padding:20px;_x000D_
 }_x000D_
 .font-container {_x000D_
  font-size:131px;_x000D_
  text-align:center;_x000D_
  color:#fff;_x000D_
 }
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>_x000D_
_x000D_
<div class="container" data-width-offset="10">_x000D_
 <span class="font-container">£5000</span>_x000D_
</div>
_x000D_
_x000D_
_x000D_

https://jsfiddle.net/Merch80/b8hoctfb/7/

AngularJS: ng-repeat list is not updated when a model element is spliced from the model array

Remove "track by index" from the ng-repeat and it would refresh the DOM

LabelEncoder: TypeError: '>' not supported between instances of 'float' and 'str'

As string data types have variable length, it is by default stored as object type. I faced this problem after treating missing values too. Converting all those columns to type 'category' before label encoding worked in my case.

df[cat]=df[cat].astype('category')

And then check df.dtypes and perform label encoding.

How to have comments in IntelliSense for function in Visual Studio?

What you need is xml comments - basically, they follow this syntax (as vaguely described by Solmead):

C#

///<summary>
///This is a description of my function.
///</summary>
string myFunction() {
     return "blah";
}

VB

'''<summary>
'''This is a description of my function.
'''</summary>
Function myFunction() As String
    Return "blah"
End Function

Emulator: ERROR: x86 emulation currently requires hardware acceleration

I had the same issue. In my case I found two issues causing the problem

  1. I had Hyper-V running, I think if any Virtualization programs running you need to uninstall
  2. I was running under Standard Account / Not Administrator

Sniff HTTP packets for GET and POST requests from an application

You will have to use some sort of network sniffer if you want to get at this sort of data and you're likely to run into the same problem (pulling out the relevant data from the overall network traffic) with those that you do now with Wireshark.

ASP.NET Setting width of DataBound column in GridView

Width can be set to specific column as below: By percentages:

<asp:BoundField HeaderText="UserInfo"  DataField="UserInfo"  
SortExpression="UserInfo" ItemStyle-Width="100%"></asp:BoundField>

OR

By pixel:

<asp:BoundField HeaderText="UserInfo"  DataField="UserInfo"  
SortExpression="UserInfo" ItemStyle-Width="500px"></asp:BoundField>

git recover deleted file where no commit was made after the delete

if you are looking for a deleted directory.

 git checkout ./pathToDir/*

Passing command line arguments in Visual Studio 2010?

Visual Studio 2015:

Project => Your Application Properties. Each argument can be separated using space. If you have a space in between for the same argument, put double quotes as shown in the example below.

enter image description here

        static void Main(string[] args)
        {
            if(args == null || args.Length == 0)
            {
                Console.WriteLine("Please specify arguments!");
            }
            else
            {
                Console.WriteLine(args[0]);     // First
                Console.WriteLine(args[1]);     // Second Argument
            }
        }

How to make full screen background in a web page

its very simple use this css (replace image.jpg with your background image)

body{height:100%;
   width:100%;
   background-image:url(image.jpg);/*your background image*/  
   background-repeat:no-repeat;/*we want to have one single image not a repeated one*/  
   background-size:cover;/*this sets the image to fullscreen covering the whole screen*/  
   /*css hack for ie*/     
   filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(src='.image.jpg',sizingMethod='scale');
   -ms-filter:"progid:DXImageTransform.Microsoft.AlphaImageLoader(src='image.jpg',sizingMethod='scale')";
}

How do I create a circle or square with just CSS - with a hollow center?

If you want your div to keep it's circular shape even if you change its width/height (using js for instance) set the radius to 50%. Example: css:

.circle {
    border-radius: 50%/50%; 
    width: 50px;
    height: 50px;
    background: black;
}

html:

<div class="circle"></div>

How to delete a line from a text file in C#?

Remove a block of code from multiple files

To expand on @Markus Olsson's answer, I needed to remove a block of code from multiple files. I had problems with Swedish characters in a core project, so I needed to install System.Text.CodePagesEncodingProvider nuget package and use System.Text.Encoding.GetEncoding(1252) instead of System.Text.Encoding.UTF8.

    public static void Main(string[] args)
    {
        try
        {
            var dir = @"C:\Test";
            //Get all html and htm files
            var files = DirSearch(dir);
            foreach (var file in files)
            {
                RmCode(file);
            }
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
            throw;
        }

    }

    private static void RmCode(string file)
    {
        string tempFile = Path.GetTempFileName();

        using (var sr = new StreamReader(file, Encoding.UTF8))
        using (var sw = new StreamWriter(new FileStream(tempFile, FileMode.Open, FileAccess.ReadWrite), Encoding.UTF8))
        {
            string line;

            var startOfBadCode = "<div>";
            var endOfBadCode = "</div>";
            var deleteLine = false;

            while ((line = sr.ReadLine()) != null)
            {
                if (line.Contains(startOfBadCode))
                {
                    deleteLine = true;
                }
                if (!deleteLine)
                {
                    sw.WriteLine(line);
                }

                if (line.Contains(endOfBadCode))
                {
                    deleteLine = false;
                }
            }
        }

        File.Delete(file);
        File.Move(tempFile, file);
    }

    private static List<String> DirSearch(string sDir)
    {
        List<String> files = new List<String>();
        try
        {
            foreach (string f in Directory.GetFiles(sDir))
            {
                files.Add(f);
            }
            foreach (string d in Directory.GetDirectories(sDir))
            {
                files.AddRange(DirSearch(d));
            }
        }
        catch (System.Exception excpt)
        {
            Console.WriteLine(excpt.Message);
        }

        return files.Where(s => s.EndsWith(".htm") || s.EndsWith(".html")).ToList();
    }

NPM global install "cannot find module"

$ vim /etc/profile.d/nodejs.sh

NODE_PATH=/usr/lib/nodejs:/usr/lib/node_modules:/usr/share/javascript
export NODE_PATH="$NODE_PATH"

Colon (:) in Python list index

: is the delimiter of the slice syntax to 'slice out' sub-parts in sequences , [start:end]

[1:5] is equivalent to "from 1 to 5" (5 not included)
[1:] is equivalent to "1 to end"
[len(a):] is equivalent to "from length of a to end"

Watch https://youtu.be/tKTZoB2Vjuk?t=41m40s at around 40:00 he starts explaining that.

Works with tuples and strings, too.

SSL Error When installing rubygems, Unable to pull data from 'https://rubygems.org/

I had same problem while trying to install cucumber gem. However I noticed that bundler gem already installed with ruby 2.0. I created a Gemfile.rb in the project folder with required gems and followed this steps

  1. Navigate to project folder
  2. Type bundle install

All the required gems installed.

How to secure database passwords in PHP?

Several people misread this as a question about how to store passwords in a database. That is wrong. It is about how to store the password that lets you get to the database.

The usual solution is to move the password out of source-code into a configuration file. Then leave administration and securing that configuration file up to your system administrators. That way developers do not need to know anything about the production passwords, and there is no record of the password in your source-control.

How to use a variable of one method in another method?

You can't. Variables defined inside a method are local to that method.

If you want to share variables between methods, then you'll need to specify them as member variables of the class. Alternatively, you can pass them from one method to another as arguments (this isn't always applicable).


Looks like you're using instance methods instead of static ones.

If you don't want to create an object, you should declare all your methods static, so something like

private static void methodName(Argument args...)

If you want a variable to be accessible by all these methods, you should initialise it outside the methods and to limit its scope, declare it private.

private static int[][] array = new int[3][5];

Global variables are usually looked down upon (especially for situations like your one) because in a large-scale program they can wreak havoc, so making it private will prevent some problems at the least.

Also, I'll say the usual: You should try to keep your code a bit tidy. Use descriptive class, method and variable names and keep your code neat (with proper indentation, linebreaks etc.) and consistent.

Here's a final (shortened) example of what your code should be like:

public class Test3 {
    //Use this array in your methods
    private static int[][] scores = new int[3][5];

    /* Rather than just "Scores" name it so people know what
     * to expect
     */
    private static void createScores() {
        //Code...
    }
    //Other methods...

    /* Since you're now using static methods, you don't 
     * have to initialise an object and call its methods.
     */
    public static void main(String[] args){
        createScores();
        MD();   //Don't know what these do
        sumD(); //so I'll leave them.
    }
}

Ideally, since you're using an array, you would create the array in the main method and pass it as an argument across each method, but explaining how that works is probably a whole new question on its own so I'll leave it at that.

Java switch statement multiple cases

JEP 354: Switch Expressions (Preview) in JDK-13 and JEP 361: Switch Expressions (Standard) in JDK-14 will extend the switch statement so it can be used as an expression.

Now you can:

  • directly assign variable from switch expression,
  • use new form of switch label (case L ->):

    The code to the right of a "case L ->" switch label is restricted to be an expression, a block, or (for convenience) a throw statement.

  • use multiple constants per case, separated by commas,
  • and also there are no more value breaks:

    To yield a value from a switch expression, the break with value statement is dropped in favor of a yield statement.

Switch expression example:

public class SwitchExpression {

  public static void main(String[] args) {
      int month = 9;
      int year = 2018;
      int numDays = switch (month) {
        case 1, 3, 5, 7, 8, 10, 12 -> 31;
        case 4, 6, 9, 11 -> 30;
        case 2 -> {
          if (java.time.Year.of(year).isLeap()) {
            System.out.println("Wow! It's leap year!");
            yield 29;
          } else {
            yield 28;
          }
        }
        default -> {
          System.out.println("Invalid month.");
          yield 0;
        }
      };
      System.out.println("Number of Days = " + numDays);
  }
}

How to place a div below another div?

what about changing the position: relative on your #content #text div to position: absolute

#content #text {
   position:absolute;
   width:950px;
   height:215px;
   color:red;
}

http://jsfiddle.net/CaZY7/12/

then you can use the css properties left and top to position within the #content div

Why does z-index not work?

If you set position to other value than static but your element's z-index still doesn't seem to work, it may be that some parent element has z-index set.

The stacking contexts have hierarchy, and each stacking context is considered in the stacking order of the parent's stacking context.

So with following html

_x000D_
_x000D_
div { border: 2px solid #000; width: 100px; height: 30px; margin: 10px; position: relative; background-color: #FFF; }_x000D_
#el3 { background-color: #F0F; width: 100px; height: 60px; top: -50px; }
_x000D_
<div id="el1" style="z-index: 5"></div>_x000D_
<div id="el2" style="z-index: 3">_x000D_
  <div id="el3" style="z-index: 8"></div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

no matter how big the z-index of el3 will be set, it will always be under el1 because it's parent has lower stacking context. You can imagine stacking order as levels where stacking order of el3 is actually 3.8 which is lower than 5.

If you want to check stacking contexts of parent elements, you can use this:

var el = document.getElementById("#yourElement"); // or use $0 in chrome;
do {
    var styles = window.getComputedStyle(el);
    console.log(styles.zIndex, el);
} while(el.parentElement && (el = el.parentElement));

There is a great article about stacking contexts on MDN

Remove an item from array using UnderscoreJS

Underscore has a _without() method perfect for removing an item from an array, especially if you have the object to remove.

Returns a copy of the array with all instances of the values removed.

_.without(["bob", "sam", "fred"], "sam");

=> ["bob", "fred"]

Works with more complex objects too.

var bob = { Name: "Bob", Age: 35 };
var sam = { Name: "Sam", Age: 19 };
var fred = { Name: "Fred", Age: 50 };

var people = [bob, sam, fred]

_.without(people, sam);

=> [{ Name: "Bob", Age: 35 }, { Name: "Fred", Age: 50 }];

If you don't have the item to remove, just a property of it, you can use _.findWhere and then _.without.

Split String into an array of String

You need a regular expression like "\\s+", which means: split whenever at least one whitespace is encountered. The full Java code is:

try {
    String[] splitArray = input.split("\\s+");
} catch (PatternSyntaxException ex) {
    // 
}

Getting URL parameter in java and extract a specific text from that URL

I believe we have a better approach to answer this question.

1: Define a function that returns Map values.

Here we go.

public Map<String, String> getUrlValues(String url) throws UnsupportedEncodingException {
    int i = url.indexOf("?");
    Map<String, String> paramsMap = new HashMap<>();
    if (i > -1) {
        String searchURL = url.substring(url.indexOf("?") + 1);
        String params[] = searchURL.split("&");

        for (String param : params) {
            String temp[] = param.split("=");
            paramsMap.put(temp[0], java.net.URLDecoder.decode(temp[1], "UTF-8"));
        }
    }

    return paramsMap;
}

2: Call your function surrounding with a try catch block

Here we go

try {
     Map<String, String> values = getUrlValues("https://example.com/index.php?form_id=9&page=1&view_id=78");
     String formId = values.get("form_id");
     String page = values.get("page");
     String viewId = values.get("view_id");
     Log.d("FormID", formId);
     Log.d("Page", page);
     Log.d("ViewID", viewId);
} catch (UnsupportedEncodingException e) {
     Log.e("Error", e.getMessage());
} 

Android: Access child views from a ListView

This code is easier to use:

 View rowView = listView.getChildAt(viewIndex);//The item number in the List View
    if(rowView != null)
        {
           // Your code here
        }

Merge two dataframes by index

A silly bug that got me: the joins failed because index dtypes differed. This was not obvious as both tables were pivot tables of the same original table. After reset_index, the indices looked identical in Jupyter. It only came to light when saving to Excel...

Fixed with: df1[['key']] = df1[['key']].apply(pd.to_numeric)

Hopefully this saves somebody an hour!

Rails: Why "sudo" command is not recognized?

sudo is a Unix/Linux command. It's not available in Windows.

How do you uninstall MySQL from Mac OS X?

sudo find / | grep -i mysql

This worked like a charm for me. Just went through the list and ensured that anything MySQL related was deleted.

Transaction isolation levels relation with locks on table

The locks are always taken at DB level:-

Oracle official Document:- To avoid conflicts during a transaction, a DBMS uses locks, mechanisms for blocking access by others to the data that is being accessed by the transaction. (Note that in auto-commit mode, where each statement is a transaction, locks are held for only one statement.) After a lock is set, it remains in force until the transaction is committed or rolled back. For example, a DBMS could lock a row of a table until updates to it have been committed. The effect of this lock would be to prevent a user from getting a dirty read, that is, reading a value before it is made permanent. (Accessing an updated value that has not been committed is considered a dirty read because it is possible for that value to be rolled back to its previous value. If you read a value that is later rolled back, you will have read an invalid value.)

How locks are set is determined by what is called a transaction isolation level, which can range from not supporting transactions at all to supporting transactions that enforce very strict access rules.

One example of a transaction isolation level is TRANSACTION_READ_COMMITTED, which will not allow a value to be accessed until after it has been committed. In other words, if the transaction isolation level is set to TRANSACTION_READ_COMMITTED, the DBMS does not allow dirty reads to occur. The interface Connection includes five values that represent the transaction isolation levels you can use in JDBC.

what is the difference between const_iterator and iterator?

if you have a list a and then following statements

list<int>::iterator it; // declare an iterator
    list<int>::const_iterator cit; // declare an const iterator 
    it=a.begin();
    cit=a.begin();

you can change the contents of the element in the list using “it” but not “cit”, that is you can use “cit” for reading the contents not for updating the elements.

*it=*it+1;//returns no error
    *cit=*cit+1;//this will return error

How do I convert hex to decimal in Python?

You could use a literal eval:

>>> ast.literal_eval('0xdeadbeef')
3735928559

Or just specify the base as argument to int:

>>> int('deadbeef', 16)
3735928559

A trick that is not well known, if you specify the base 0 to int, then Python will attempt to determine the base from the string prefix:

>>> int("0xff", 0)
255
>>> int("0o644", 0)
420
>>> int("0b100", 0)
4
>>> int("100", 0)
100

How do I get to IIS Manager?

First of all, you need to check that the IIS is installed in your machine, for that you can go to:

Control Panel --> Add or Remove Programs --> Windows Features --> And Check if Internet Information Services is installed with at least the 'Web Administration Tools' Enabled and The 'World Wide Web Service'

If not, check it, and Press Accept to install it.

Once that is done, you need to go to Administrative Tools in Control Panel and the IIS Will be there. Or simply run inetmgr (after Win+R).

Edit: You should have something like this: enter image description here

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

Sometimes, there will be firewalls and restrictions in the network preventing the plugin to get downloaded. We can try some other network. This actually resolved my issue.

Android studio: emulator is running but not showing up in Run App "choose a running device"

This thread helped me to solve my problem, in particular this answer:

  • In Android Studio go to Menu -> Tools
  • Android
  • Uncheck Enable ADB Integration

How do I use $rootScope in Angular to store variables?

If it is just "access in other controller" then you can use angular constants for that, the benefit is; you can add some global settings or other things that you want to access throughout application

app.constant(‘appGlobals’, {
    defaultTemplatePath: '/assets/html/template/',
    appName: 'My Awesome App'
});

and then access it like:

app.controller(‘SomeController’, [‘appGlobals’, function SomeController(config) {
    console.log(appGlobals);
    console.log(‘default path’, appGlobals.defaultTemplatePath);
}]);

(didn't test)

more info: http://ilikekillnerds.com/2014/11/constants-values-global-variables-in-angularjs-the-right-way/

changing the language of error message in required field in html5 contact form

This work for me.

<input oninvalid="this.setCustomValidity('custom text on invalid')" onchange="this.setCustomValidity('')" required>

onchange is a must!

SQL (MySQL) vs NoSQL (CouchDB)

One of the best options is to go for MongoDB(NOSql dB) that supports scalability.Stores large amounts of data nothing but bigdata in the form of documents unlike rows and tables in sql.This is fasters that follows sharding of the data.Uses replicasets to ensure data guarantee that maintains multiple servers having primary db server as the base. Language independent. Flexible to use

How to compare two java objects

You need to Override equals and hashCode.
equals will compare the objects for equality according to the properties you need and hashCode is mandatory in order for your objects to be used correctly in Collections and Maps

Java error - "invalid method declaration; return type required"

You forgot to declare double as a return type

public double diameter()
{
    double d = radius * 2;
    return d;
}

Interface or an Abstract Class: which one to use?

Just wanted to add an example of when you may need to use both. I am currently writing a file handler bound to a database model in a general purpose ERP solution.

  • I have multiple abstract classes which handle the standard crud and also some specialty functionality like conversion and streaming for different categories of files.
  • The file access interface defines a common set of methods which are needed to get, store and delete a file.

This way, I get to have multiple templates for different files and a common set of interface methods with clear distinction. The interface gives the correct analogy to the access methods rather than what would have been with a base abstract class.

Further down the line when I will make adapters for different file storage services, this implementation will allow the interface to be used elsewhere in totally different contexts.

How can I rollback a git repository to a specific commit?

Another way:

Checkout the branch you want to revert, then reset your local working copy back to the commit that you want to be the latest one on the remote server (everything after it will go bye-bye). To do this, in SourceTree, I right-clicked on the and selected "Reset BRANCHNAME to this commit".

Then navigate to your repository's local directory and run this command:

git -c diff.mnemonicprefix=false -c core.quotepath=false push -v -f -- tags REPOSITORY_NAME BRANCHNAME:BRANCHNAME 

This will erase all commits after the current one in your local repository but only for that one branch.

Deserialize JSON into C# dynamic object?

I want to do this programmatically in unit tests, I do have the luxury of typing it out.

My solution is:

var dict = JsonConvert.DeserializeObject<ExpandoObject>(json) as IDictionary<string, object>;

Now I can assert that

dict.ContainsKey("ExpectedProperty");

Use PHP composer to clone git repo

In my case, I use Symfony2.3.x and the minimum-stability parameter is by default "stable" (which is good). I wanted to import a repo not in packagist but had the same issue "Your requirements could not be resolved to an installable set of packages.". It appeared that the composer.json in the repo I tried to import use a minimum-stability "dev".

So to resolve this issue, don't forget to verify the minimum-stability. I solved it by requiring a dev-master version instead of master as stated in this post.

Executing multiple SQL queries in one statement with PHP

With mysqli you're able to use multiple statements for real using mysqli_multi_query().

Read more on multiple statements in the PHP Docs.

How to check whether a variable is a class or not?

simplest way is to use inspect.isclass as posted in the most-voted answer.
the implementation details could be found at python2 inspect and python3 inspect.
for new-style class: isinstance(object, type)
for old-style class: isinstance(object, types.ClassType)
em, for old-style class, it is using types.ClassType, here is the code from types.py:

class _C:
    def _m(self): pass
ClassType = type(_C)

Moment.js: Date between dates

I do believe that

if (startDate <= date && date <= endDate) {
  alert("Yay");
} else {
  alert("Nay! :("); 
}

works too...

org.xml.sax.SAXParseException: Content is not allowed in prolog

For all those that get this error: WARNING: Catalina.start using conf/server.xml: Content is not allowed in prolog.

Not very informative.. but what this actually means is that there is garbage in your conf/server.xml file.

I have seen this exact error in other XML files.. this error can be caused by making changes with a text editor which introduces the garbage.

The way you can verify whether or not you have garbage in the file is to open it with a "HEX Editor" If you see any character before this string

     "<?xml version="1.0" encoding="UTF-8"?>"

like this would be garbage

     "‰ŠŒ<?xml version="1.0" encoding="UTF-8"?>"

that is your problem.... The Solution is to use a good HEX Editor.. One that will allow you to save files with differing types of encoding..

Then just save it as UTF-8. Some systems that use XML files may need it saved as UTF NO BOM Which means with "NO Byte Order Mark"

Hope this helps someone out there!!

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

Put the table in a container element that has

overflow:scroll; max-width:95vw;

or make the table fit to the screen and overflow:scroll all table cells.

Codeigniter displays a blank page instead of error messages

If you have this in your php.ini:

display_error = On;

and you have this in your CI Application at the same time

error_reporting(0);

you'll get HTTP/1.1 200 OK and a completely bank page.

That's because when display_error is on, the php-fpm always return HTTP code 200. And all the errors to output are forbidden by error_reporting(0).

For CI application,the entry index.php sets up the running environment as bellows:

if(isset($_SERVER['SERVER_ENV'])) {
    define('ENVIRONMENT', $_SERVER['SERVER_ENV']);
} else {
    define('ENVIRONMENT', 'development');
}

if (defined('ENVIRONMENT'))
{
    switch (ENVIRONMENT)
    {
        case 'development':
            error_reporting(E_ALL);
            ini_set('display_errors', 1);
        break;

        case 'testing':
        case 'production':
            error_reporting(0);
        break;

        default:
            exit('The application environment is not set correctly.');
    }
}

In short, when you set ENV directive in your webserver's conf,say Nginx's fastcgi_params:

fastcgi_param  SERVER_ENV         production;

then CI will automatically set

error_reporting(0);

Command line input in Python

Start your script with the following line. The script will first run and then you will get the python command prompt. At this point all variables and functions will be available for interactive use and invocations.

#!/usr/bin/env python -i

Declare a constant array

An array isn't immutable by nature; you can't make it constant.

The nearest you can get is:

var letter_goodness = [...]float32 {.0817, .0149, .0278, .0425, .1270, .0223, .0202, .0609, .0697, .0015, .0077, .0402, .0241, .0675, .0751, .0193, .0009, .0599, .0633, .0906, .0276, .0098, .0236, .0015, .0197, .0007 }

Note the [...] instead of []: it ensures you get a (fixed size) array instead of a slice. So the values aren't fixed but the size is.

Spring data JPA query with parameter properties

You could also solve it with an interface default method:

 @Query(select p from Person p where p.forename = :forename and p.surname = :surname)
User findByForenameAndSurname(@Param("surname") String lastname,
                         @Param("forename") String firstname);

default User findByName(Name name) {
  return findByForenameAndSurname(name.getLastname(), name.getFirstname());
}

Of course you'd still have the actual repository function publicly visible...

How to convert nanoseconds to seconds using the TimeUnit enum?

In Java 8 or Kotlin, I use Duration.ofNanos(1_000_000_000) like

val duration = Duration.ofNanos(1_000_000_000)
logger.info(String.format("%d %02dm %02ds %03d",
                elapse, duration.toMinutes(), duration.toSeconds(), duration.toMillis()))

Read more https://docs.oracle.com/javase/8/docs/api/java/time/Duration.html

Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister

In my case the problem was because of conflicting Jars.

Here is the full list of jars which is working absolutely fine for me.

antlr-2.7.7.jar
byte-buddy-1.8.12.jar
c3p0-0.9.5.2.jar
classmate-1.3.4.jar
dom4j-1.6.1.jar
geolatte-geom-1.3.0.jar
hibernate-c3p0-5.3.1.Final.jar
hibernate-commons-annotations-5.0.3.Final.jar
hibernate-core-5.3.1.Final.jar
hibernate-envers-5.3.1.Final.jar
hibernate-jpamodelgen-5.3.1.Final.jar
hibernate-osgi-5.3.1.Final.jar
hibernate-proxool-5.3.1.Final.jar
hibernate-spatial-5.3.1.Final.jar
jandex-2.0.3.Final.jar
javassist-3.22.0-GA.jar
javax.interceptor-api-1.2.jar
javax.persistence-api-2.2.jar
jboss-logging-3.3.2.Final.jar
jboss-transaction-api_1.2_spec-1.1.1.Final.jar
jts-core-1.14.0.jar
mchange-commons-java-0.2.11.jar
mysql-connector-java-5.1.21.jar
org.osgi.compendium-4.3.1.jar
org.osgi.core-4.3.1.jar
postgresql-42.2.2.jar
proxool-0.8.3.jar
slf4j-api-1.6.1.jar

How to handle a single quote in Oracle SQL

I found the above answer giving an error with Oracle SQL, you also must use square brackets, below;

SQL> SELECT Q'[Paddy O'Reilly]' FROM DUAL;


Result: Paddy O'Reilly

Could not reserve enough space for object heap to start JVM

It looks like the machine you're trying to run this on has only 256 MB memory.

Maybe the JVM tries to allocate a large, contiguous block of 64 MB memory. The 192 MB that you have free might be fragmented into smaller pieces, so that there is no contiguous block of 64 MB free to allocate.

Try starting your Java program with a smaller heap size, for example:

java -Xms16m ...

Maven Unable to locate the Javac Compiler in:

Go to Window -> Preferences... -> Java -> Installed JREs

Edit JRE Home = JAVA_HOME or JAVA_HOME\jre

For example if you use jdk1.6.0_04 which is installed in C:\Program Files, do the following change:

C:\Program Files\Java\jdk1.6.0_04\jre or C:\Program Files\Java\jdk1.6.0_04 instead of the default one which is at C:\Program Files\Java\jre7

How to position a div in the middle of the screen when the page is bigger than the screen

_x000D_
_x000D_
<!DOCTYPE html>_x000D_
<html>_x000D_
<head>_x000D_
<style>_x000D_
.loader {_x000D_
  position: absolute;_x000D_
  top: 50%;_x000D_
  left: 50%;_x000D_
  margin-top: -50px;_x000D_
  margin-left: -50px;_x000D_
  border: 10px solid #dcdcdc;_x000D_
  border-radius: 50%;_x000D_
  border-top: 10px solid #3498db;_x000D_
  width: 30px;_x000D_
  height: 30px;_x000D_
  -webkit-animation: spin 2s linear infinite;_x000D_
  animation: spin 1s linear infinite;  _x000D_
}_x000D_
_x000D_
@-webkit-keyframes spin {_x000D_
  0% { -webkit-transform: rotate(0deg); }_x000D_
  100% { -webkit-transform: rotate(360deg); }_x000D_
}_x000D_
_x000D_
@keyframes spin {_x000D_
  0% { transform: rotate(0deg); }_x000D_
  100% { transform: rotate(360deg); }_x000D_
}_x000D_
</style>_x000D_
</head>_x000D_
<body>_x000D_
_x000D_
_x000D_
<div class="loader" style="display:block"></div>_x000D_
_x000D_
</body>_x000D_
</html>
_x000D_
_x000D_
_x000D_

Add querystring parameters to link_to

If you want the quick and dirty way and don't worry about XSS attack, use params.merge to keep previous parameters. e.g.

<%= link_to 'Link', params.merge({:per_page => 20}) %>

see: https://stackoverflow.com/a/4174493/445908

Otherwise , check this answer: params.merge and cross site scripting

Label points in geom_point

The ggrepel package works great for repelling overlapping text labels away from each other. You can use either geom_label_repel() (draws rectangles around the text) or geom_text_repel() functions.

library(ggplot2)
library(ggrepel)

nba <- read.csv("http://datasets.flowingdata.com/ppg2008.csv", sep = ",")

nbaplot <- ggplot(nba, aes(x= MIN, y = PTS)) + 
  geom_point(color = "blue", size = 3)

### geom_label_repel
nbaplot + 
  geom_label_repel(aes(label = Name),
                  box.padding   = 0.35, 
                  point.padding = 0.5,
                  segment.color = 'grey50') +
  theme_classic()

enter image description here

### geom_text_repel
# only label players with PTS > 25 or < 18
# align text vertically with nudge_y and allow the labels to 
# move horizontally with direction = "x"
ggplot(nba, aes(x= MIN, y = PTS, label = Name)) + 
  geom_point(color = dplyr::case_when(nba$PTS > 25 ~ "#1b9e77", 
                                      nba$PTS < 18 ~ "#d95f02",
                                      TRUE ~ "#7570b3"), 
             size = 3, alpha = 0.8) +
  geom_text_repel(data          = subset(nba, PTS > 25),
                  nudge_y       = 32 - subset(nba, PTS > 25)$PTS,
                  size          = 4,
                  box.padding   = 1.5,
                  point.padding = 0.5,
                  force         = 100,
                  segment.size  = 0.2,
                  segment.color = "grey50",
                  direction     = "x") +
  geom_label_repel(data         = subset(nba, PTS < 18),
                  nudge_y       = 16 - subset(nba, PTS < 18)$PTS,
                  size          = 4,
                  box.padding   = 0.5,
                  point.padding = 0.5,
                  force         = 100,
                  segment.size  = 0.2,
                  segment.color = "grey50",
                  direction     = "x") +
  scale_x_continuous(expand = expand_scale(mult = c(0.2, .2))) +
  scale_y_continuous(expand = expand_scale(mult = c(0.1, .1))) +
  theme_classic(base_size = 16)

Edit: To use ggrepel with lines, see this and this.

Created on 2019-05-01 by the reprex package (v0.2.0).

How to import a bak file into SQL Server Express

Restoring a Database from Backup

sql-server-->connect to instance-->Databases-->right-click on databases-->Restore
            DataBase..-->Device-->Add-->choose the path_filename(.bak)-->click OK

How to sanity check a date in Java

setLenient to false if you like a strict validation

public boolean isThisDateValid(String dateToValidate, String dateFromat){

    if(dateToValidate == null){
        return false;
    }

    SimpleDateFormat sdf = new SimpleDateFormat(dateFromat);
    sdf.setLenient(false);

    try {

        //if not valid, it will throw ParseException
        Date date = sdf.parse(dateToValidate);
        System.out.println(date);

    } catch (ParseException e) {

        e.printStackTrace();
        return false;
    }

    return true;
}

How to center images on a web page for all screen sizes

text-align:center

Applying the text-align:center style to an element containing elements will center those elements.

<div id="method-one" style="text-align:center">
  CSS `text-align:center`
</div>

Thomas Shields mentions this method



margin:0 auto

Applying the margin:0 auto style to a block element will center it within the element it is in.

<div id="method-two" style="background-color:green">
  <div style="margin:0 auto;width:50%;background-color:lightblue">
    CSS `margin:0 auto` to have left and right margin set to center a block element within another element.
  </div>
</div>

user1468562 mentions this method


Center tag

My original answer was that you can use the <center></center> tag. To do this, just place the content you want centered between the tags. As of HTML4, this tag has been deprecated, though. <center> is still technically supported today (9 years later at the time of updating this), but I'd recommend the CSS alternatives I've included above.

<h3>Method 3</h1>
<div id="method-three">
  <center>Center tag (not recommended and deprecated in HTML4)</center>
</div>

You can see these three code samples in action in this jsfiddle.

I decided I should revise this answer as the previous one I gave was outdated. It was already deprecated when I suggested it as a solution and that's all the more reason to avoid it now 9 years later.

Can I recover a branch after its deletion in Git?

Yes, you should be able to do git reflog --no-abbrev and find the SHA1 for the commit at the tip of your deleted branch, then just git checkout [sha]. And once you're at that commit, you can just git checkout -b [branchname] to recreate the branch from there.


Credit to @Cascabel for this condensed/one-liner version and @Snowcrash for how to obtain the sha.

If you've just deleted the branch you'll see something like this in your terminal Deleted branch <your-branch> (was <sha>). Then just use that <sha> in this one-liner:

git checkout -b <your-branch> <sha>

How to download the latest artifact from Artifactory repository?

For me the easiest way was to read the last versions of the project with a combination of curl, grep, sort and tail.

My format: service-(version: 1.9.23)-(buildnumber)156.tar.gz

versionToDownload=$(curl -u$user:$password 'https://$artifactory/artifactory/$project/' | grep -o 'service-[^"]*.tar.gz' | sort | tail -1)

Case insensitive string as HashMap key

I like using ICU4J’s CaseInsensitiveString wrap of the Map key because it takes care of the hash\equals and issue and it works for unicode\i18n.

HashMap<CaseInsensitiveString, String> caseInsensitiveMap = new HashMap<>();
caseInsensitiveMap.put("tschüß", "bye");
caseInsensitiveMap.containsKey("TSCHÜSS"); # true

Getting full URL of action in ASP.NET MVC

I was having an issue with this, my server was running behind a load balancer. The load balancer was terminating the SSL/TLS connection. It then passed the request to the web servers using http.

Using the Url.Action() method with Request.Url.Schema, it kept creating a http url, in my case to create a link in an automated email (which my PenTester didn't like).

I may have cheated a little, but it is exactly what I needed to force a https url:

<a href="@Url.Action("Action", "Controller", new { id = Model.Id }, "https")">Click Here</a>

I actually use a web.config AppSetting so I can use http when debugging locally, but all test and prod environments use transformation to set the https value.

Append data to a POST NSURLRequest

The example code above was really helpful to me, however (as has been hinted at above), I think you need to use NSMutableURLRequest rather than NSURLRequest. In its current form, I couldn't get it to respond to the setHTTPMethod call. Changing the type fixed things right up.

What does "request for member '*******' in something not a structure or union" mean?

You are trying to access a member of a structure, but in something that is not a structure. For example:

struct {
    int a;
    int b;
} foo;
int fum;
fum.d = 5;

Global npm install location on windows?

Just press windows button and type %APPDATA% and type enter.

Above is the location where you can find \npm\node_modules folder. This is where global modules sit in your system.

Variable's memory size in Python

Use sys.getsizeof to get the size of an object, in bytes.

>>> from sys import getsizeof
>>> a = 42
>>> getsizeof(a)
12
>>> a = 2**1000
>>> getsizeof(a)
146
>>>

Note that the size and layout of an object is purely implementation-specific. CPython, for example, may use totally different internal data structures than IronPython. So the size of an object may vary from implementation to implementation.

How to use log levels in java

the different log levels are helpful for tools, whose can anaylse you log files. Normally a logfile contains lots of information. To avoid an information overload (or here an stackoverflow^^) you can use the log levels for grouping the information.

'uint32_t' does not name a type

You need to include iostream

#include <iostream>
using namespace std;

Insert Update trigger how to determine if insert or update

This does the trick for me:

declare @action_type int;
select @action_type = case
                       when i.id is not null and d.id is     null then 1 -- insert
                       when i.id is not null and d.id is not null then 2 -- update
                       when i.id is     null and d.id is not null then 3 -- delete
                     end
  from      inserted i
  full join deleted  d on d.id = i.id

Since not all columns can be updated at a time you can check whether a particular column is being updated by something like this:

IF UPDATE([column_name])

Override valueof() and toString() in Java enum

You can try out this code. Since you cannot override valueOf method you have to define a custom method (getEnum in the sample code below) which returns the value that you need and change your client to use this method instead.

public enum RandomEnum {

    StartHere("Start Here"),
    StopHere("Stop Here");

    private String value;

    RandomEnum(String value) {
        this.value = value;
    }

    public String getValue() {
        return value;
    }

    @Override
    public String toString() {
        return this.getValue();
    }

    public static RandomEnum getEnum(String value) {
        for(RandomEnum v : values())
            if(v.getValue().equalsIgnoreCase(value)) return v;
        throw new IllegalArgumentException();
    }
}

How to convert integer into date object python?

This question is already answered, but for the benefit of others looking at this question I'd like to add the following suggestion: Instead of doing the slicing yourself as suggested above you might also use strptime() which is (IMHO) easier to read and perhaps the preferred way to do this conversion.

import datetime
s = "20120213"
s_datetime = datetime.datetime.strptime(s, '%Y%m%d')

How to call a REST web service API from JavaScript?

I think add if (this.readyState == 4 && this.status == 200) to wait is better:

var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
       // Typical action to be performed when the document is ready:
        var response = xhttp.responseText;
        console.log("ok"+response);
    }
};
xhttp.open("GET", "your url", true);

xhttp.send();

Introducing FOREIGN KEY constraint may cause cycles or multiple cascade paths - why?

None of the aforementioned solutions worked for me. What I had to do was use a nullable int (int?) on the foreign key that was not required (or not a not null column key) and then delete some of my migrations.

Start by deleting the migrations, then try the nullable int.

Problem was both a modification and model design. No code change was necessary.

How to control the width and height of the default Alert Dialog in Android?

This works as well by adding .getWindow().setLayout(width, height) after show()

alertDialogBuilder
            .setMessage("Click yes to exit!")
            .setCancelable(false)
            .setPositiveButton("Yes",new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog,int id) {
                    // if this button is clicked, close
                    // current activity
                    MainActivity.this.finish();
                }
              })
            .setNegativeButton("No",new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog,int id) {
                    // if this button is clicked, just close
                    // the dialog box and do nothing
                    dialog.cancel();
                }
            }).show().getWindow().setLayout(600,500);

How to convert a boolean array to an int array

Most of the time you don't need conversion:

>>>array([True,True,False,False]) + array([1,2,3,4])
array([2, 3, 3, 4])

The right way to do it is:

yourArray.astype(int)

or

yourArray.astype(float)

Access-Control-Allow-Origin wildcard subdomains, ports and protocols

The CORS spec is all-or-nothing. It only supports *, null or the exact protocol + domain + port: http://www.w3.org/TR/cors/#access-control-allow-origin-response-header

Your server will need to validate the origin header using the regex, and then you can echo the origin value in the Access-Control-Allow-Origin response header.

java.lang.ClassNotFoundException: javax.servlet.jsp.jstl.core.Config

Download the following jars and add it to your WEB-INF/lib directory:

What is the point of "final class" in Java?

One scenario where final is important, when you want to prevent inheritance of a class, for security reasons. This allows you to make sure that code you are running cannot be overridden by someone.

Another scenario is for optimization: I seem to remember that the Java compiler inlines some function calls from final classes. So, if you call a.x() and a is declared final, we know at compile-time what the code will be and can inline into the calling function. I have no idea whether this is actually done, but with final it is a possibility.

Unable to connect to any of the specified mysql hosts. C# MySQL

I am running mysql on a computer on a local network. MySQL Workbench could connect to that server, but not my c# code. I solved my issue by disconnecting from a vpn client that was running.

Jersey client: How to add a list as query parameter

GET Request with JSON Query Param

package com.rest.jersey.jerseyclient;
import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;

public class JerseyClientGET {

    public static void main(String[] args) {
        try {               

            String BASE_URI="http://vaquarkhan.net:8080/khanWeb";               
            Client client = Client.create();    
            WebResource webResource = client.resource(BASE_URI);

            ClientResponse response = webResource.accept("application/json").get(ClientResponse.class);

            /*if (response.getStatus() != 200) {
               throw new RuntimeException("Failed : HTTP error code : "
                + response.getStatus());
            }
*/
            String output = webResource.path("/msg/sms").queryParam("search","{\"name\":\"vaquar\",\"surname\":\"khan\",\"ext\":\"2020\",\"age\":\"34\""}").get(String.class);
            //String output = response.getEntity(String.class);

            System.out.println("Output from Server .... \n");
            System.out.println(output);                         

        } catch (Exception e) {

            e.printStackTrace();    
        }    
    }    
}

Post Request :

package com.rest.jersey.jerseyclient;

import com.rest.jersey.dto.KhanDTOInput;
import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;
import com.sun.jersey.api.client.config.ClientConfig;
import com.sun.jersey.api.client.config.DefaultClientConfig;
import com.sun.jersey.api.json.JSONConfiguration;

public class JerseyClientPOST {

    public static void main(String[] args) {
        try {

            KhanDTOInput khanDTOInput = new KhanDTOInput("vaquar", "khan", "20", "E", null, "2222", "8308511500");                      

            ClientConfig clientConfig = new DefaultClientConfig();

            clientConfig.getFeatures().put( JSONConfiguration.FEATURE_POJO_MAPPING, Boolean.TRUE);

            Client client = Client.create(clientConfig);

               // final HTTPBasicAuthFilter authFilter = new HTTPBasicAuthFilter(username, password);
               // client.addFilter(authFilter);
               // client.addFilter(new LoggingFilter());

            //
            WebResource webResource = client
                    .resource("http://vaquarkhan.net:12221/khanWeb/messages/sms/api/v1/userapi");

              ClientResponse response = webResource.accept("application/json")
                .type("application/json").put(ClientResponse.class, khanDTOInput);


            if (response.getStatus() != 200) {
                throw new RuntimeException("Failed : HTTP error code :" + response.getStatus());
            }

            String output = response.getEntity(String.class);

            System.out.println("Server response .... \n");
            System.out.println(output);

        } catch (Exception e) {

            e.printStackTrace();

        }    
    }    
}

What does '&' do in a C++ declaration?

#include<iostream>
using namespace std;
int add(int &number);

int main ()
{
            int number;
            int result;
            number=5;
            cout << "The value of the variable number before calling the function : " << number << endl;
            result=add(&number);
            cout << "The value of the variable number after the function is returned : " << number << endl;
            cout << "The value of result : " << result << endl;
            return(0);
}

int add(int &p)
{
            *p=*p+100;
            return(*p);
}

This is invalid code on several counts. Running it through g++ gives:

crap.cpp: In function ‘int main()’:
crap.cpp:11: error: invalid initialization of non-const reference of type ‘int&’ from a temporary of type ‘int*’
crap.cpp:3: error: in passing argument 1 of ‘int add(int&)’
crap.cpp: In function ‘int add(int&)’:
crap.cpp:19: error: invalid type argument of ‘unary *’
crap.cpp:19: error: invalid type argument of ‘unary *’
crap.cpp:20: error: invalid type argument of ‘unary *’

A valid version of the code reads:

#include<iostream>
using namespace std;
int add(int &number);

int main ()
{
            int number;
            int result;
            number=5;
            cout << "The value of the variable number before calling the function : " << number << endl;
            result=add(number);
            cout << "The value of the variable number after the function is returned : " << number << endl;
            cout << "The value of result : " << result << endl;
            return(0);
}

int add(int &p)
{
            p=p+100;
            return p;
}

What is happening here is that you are passing a variable "as is" to your function. This is roughly equivalent to:

int add(int *p)
{
      *p=*p+100;
      return *p;
}

However, passing a reference to a function ensures that you cannot do things like pointer arithmetic with the reference. For example:

int add(int &p)
{
            *p=*p+100;
            return p;
}

is invalid.

If you must use a pointer to a reference, that has to be done explicitly:

int add(int &p)
{
                    int* i = &p;
            i=i+100L;
            return *i;
}

Which on a test run gives (as expected) junk output:

The value of the variable number before calling the function : 5
The value of the variable number after the function is returned : 5
The value of result : 1399090792

What is the ultimate postal code and zip regex?

There is none.

Postal/zip codes around the world don't follow a common pattern. In some countries they are made up by numbers, in others they can be combinations of numbers an letters, some can contain spaces, others dots, the number of characters can vary from two to at least six...

What you could do (theoretically) is create a seperate regex for every country in the world, not recommendable IMO. But you would still be missing on the validation part: Zip code 12345 may exist, but 12346 not, maybe 12344 doesn't exist either. How do you check for that with a regex?

You can't.

libz.so.1: cannot open shared object file

I've downloaded these packages:

  • libc6-i386
  • lib32stdc++6
  • lib32gcc1
  • lib32ncurses5
  • zlib1g

I then unpacked them and added the directories to LD_LIBRARY_PATH in my ~/.bashrc. Just make sure to add proper dirs to the path.

How to create a popup windows in javafx

Have you looked into ControlsFx Popover control.


import org.controlsfx.control.PopOver;
import org.controlsfx.control.PopOver.ArrowLocation;

private PopOver item;

final Scene scene = addItemButton.getScene();

final Point2D windowCoord = new Point2D(scene.getWindow()
        .getX(), scene.getWindow().getY());

final Point2D sceneCoord = new Point2D(scene.getX(), scene.
                getY());

final Point2D nodeCoord = addItemButton.localToScene(0.0,
                        0.0);
final double clickX = Math.round(windowCoord.getX()
    + sceneCoord.getY() + nodeCoord.getX());

final double clickY = Math.round(windowCoord.getY()
        + sceneCoord.getY() + nodeCoord.getY());
item.setContentNode(addItemScreen);
item.setArrowLocation(ArrowLocation.BOTTOM_LEFT);
item.setCornerRadius(4);                            
item.setDetachedTitle("Add New Item");
item.show(addItemButton.getParent(), clickX, clickY);

This is only an example but a PopOver sounds like it could accomplish what you want. Check out the documentation for more info.

Important note: ControlsFX will only work on JavaFX 8.0 b118 or later.

How do I get the path of the assembly the code is in?

I believe this would work for any kind of application:

AppDomain.CurrentDomain.RelativeSearchPath ?? AppDomain.CurrentDomain.BaseDirectory

How to open the terminal in Atom?

There are a number of Atom packages which give you access to the terminal from within Atom. Try a few out to find the best option for you.

Some recommendations which work in Ubuntu (with their primary keyboard shortcuts):

Open a terminal in Atom:

Edit: recommended plugin changed as terminal-plus is no longer maintained. Thanks for the head's-up, @MorganRodgers.

If you want to open a terminal panel in Atom, try atom-ide-terminal. Use the keyboard shortcut ctrl-` to open a new terminal instance.

Open an external terminal from Atom:

If you just want a shortcut to open your external terminal from within Atom, try atom-terminal (this is what I use). You can use ctrl-shift-t to open your external terminal in the current file's directory, or alt-shift-t to open the terminal in the project's root directory.

How to call a parent class function from derived class function?

Given a parent class named Parent and a child class named Child, you can do something like this:

class Parent {
public:
    virtual void print(int x);
};

class Child : public Parent {
    void print(int x) override;
};

void Parent::print(int x) {
    // some default behavior
}

void Child::print(int x) {
    // use Parent's print method; implicitly passes 'this' to Parent::print
    Parent::print(x);
}

Note that Parent is the class's actual name and not a keyword.

Disable and later enable all table indexes in Oracle

If you're on Oracle 11g, you may also want to check out dbms_index_utl.

Set textarea width to 100% in bootstrap modal

After testing those suggestions here, I draw the conclusion that we have to apply two things.

  1. Apply form-control class to your textarea element. This is among Bootstrap's built-in classes.

  2. Extend this class by adding the following property:

.form-control {
   max-width: 100%;
}

Hope this helps others who are looking for a solution to this issue.

Pass array to MySQL stored routine

I'm not sure if this is fully answering the question (it isn't), but it's the solution I came up with for my similar problem. Here I try to just use LOCATE() just once per delimiter.

-- *****************************************************************************
-- test_PVreplace

DROP FUNCTION IF EXISTS test_PVreplace;

delimiter //
CREATE FUNCTION test_PVreplace (
   str TEXT,   -- String to do search'n'replace on
   pv TEXT     -- Parameter/value pairs 'p1=v1|p2=v2|p3=v3'
   )
   RETURNS TEXT

-- Replace specific tags with specific values.

sproc:BEGIN
   DECLARE idx INT;
   DECLARE idx0 INT DEFAULT 1;   -- 1-origined, not 0-origined
   DECLARE len INT;
   DECLARE sPV TEXT;
   DECLARE iPV INT;
   DECLARE sP TEXT;
   DECLARE sV TEXT;

   -- P/V string *must* end with a delimiter.

   IF (RIGHT (pv, 1) <> '|') THEN
      SET pv = CONCAT (pv, '|');
      END IF;

   -- Find all the P/V pairs.

   SELECT LOCATE ('|', pv, idx0) INTO idx;
   WHILE (idx > 0) DO
      SET len = idx - idx0;
      SELECT SUBSTRING(pv, idx0, len) INTO sPV;

      -- Found a P/V pair.  Break it up.

      SELECT LOCATE ('=', sPV) INTO iPV;
      IF (iPV = 0) THEN
         SET sP = sPV;
         SET sV = '';
      ELSE
         SELECT SUBSTRING(sPV, 1, iPV-1) INTO sP;
         SELECT SUBSTRING(sPV, iPV+1) INTO sV;
         END IF;

      -- Do the substitution(s).

      SELECT REPLACE (str, sP, sV) INTO str;

      -- Do next P/V pair.

      SET idx0 = idx + 1;
      SELECT LOCATE ('|', pv, idx0) INTO idx;
      END WHILE;
   RETURN (str);
END//
delimiter ;

SELECT test_PVreplace ('%one% %two% %three%', '%one%=1|%two%=2|%three%=3');
SELECT test_PVreplace ('%one% %two% %three%', '%one%=I|%two%=II|%three%=III');
SELECT test_PVreplace ('%one% %two% %three% - %one% %two% %three%', '%one%=I|%two%=II|%three%=III');
SELECT test_PVreplace ('%one% %two% %three% - %one% %two% %three%', '');
SELECT test_PVreplace ('%one% %two% %three% - %one% %two% %three%', NULL);
SELECT test_PVreplace ('%one% %two% %three%', '%one%=%two%|%two%=%three%|%three%=III');

uncaught syntaxerror unexpected token U JSON

In my case it was trying to call JSON.parse() on an AJAX variable before the XHRResponse came back. EG:

var response = $.get(URL that returns a valid JSON string);
var data = JSON.parse(response.responseText);

I replaced that with an example out of the jQuery site for $.get:

<script type="text/javascript"> 
    var jqxhr = $.get( "https://jira.atlassian.com/rest/api/2/project", function() {
          alert( "success" );
        })
          .done(function() {
//insert code to assign the projects from Jira to a div.
                jqxhr = jqxhr.responseJSON;
                console.log(jqxhr);
                var div = document.getElementById("products");
                for (i = 0; i < jqxhr.length; i++) {
                    console.log(jqxhr[i].name);
                    div.innerHTML += "<b>Product: " + jqxhr[i].name + "</b><BR/>Key: " + jqxhr[i].key + "<BR/>";
                }
                console.log(div);
            alert( "second success" );
          })
          .fail(function() {
            alert( "error" );
          })
          .always(function() {
            alert( "finished" );
          });

        // Perform other work here ...

        // Set another completion function for the request above
        jqxhr.always(function() {
          alert( "second finished" );
        });
</script>

Java Immutable Collections

I believe the point here is that even if a collection is Unmodifiable, that does not ensure that it cannot change. Take for example a collection that evicts elements if they are too old. Unmodifiable just means that the object holding the reference cannot change it, not that it cannot change. A true example of this is Collections.unmodifiableList method. It returns an unmodifiable view of a List. The the List reference that was passed into this method is still modifiable and so the list can be modified by any holder of the reference that was passed. This can result in ConcurrentModificationExceptions and other bad things.

Immutable, mean that in no way can the collection be changed.

Second question: An Immutable collection does not mean that the objects contained in the collection will not change, just that collection will not change in the number and composition of objects that it holds. In other words, the collection's list of references will not change. That does not mean that the internals of the object being referenced cannot change.

apache server reached MaxClients setting, consider raising the MaxClients setting

Did you consider using nginx (or other event based web server) instead of apache?

nginx shall allow higher number of connections and consume much less resources (as it is event based and does not create separate process per connection). Anyway, you will need some processes, doing real work (like WSGI servers or so) and if they stay on the same server as the front end web server, you only shift the performance problem to a bit different place.

Latest apache version shall allow similar solution (configure it in event based manner), but this is not my area of expertise.

Simple way to query connected USB devices info in Python?

I can think of a quick code like this.

Since all USB ports can be accessed via /dev/bus/usb/< bus >/< device >

For the ID generated, even if you unplug the device and reattach it [ could be some other port ]. It will be the same.

import re
import subprocess
device_re = re.compile("Bus\s+(?P<bus>\d+)\s+Device\s+(?P<device>\d+).+ID\s(?P<id>\w+:\w+)\s(?P<tag>.+)$", re.I)
df = subprocess.check_output("lsusb")
devices = []
for i in df.split('\n'):
    if i:
        info = device_re.match(i)
        if info:
            dinfo = info.groupdict()
            dinfo['device'] = '/dev/bus/usb/%s/%s' % (dinfo.pop('bus'), dinfo.pop('device'))
            devices.append(dinfo)
print devices

Sample output here will be:

[
{'device': '/dev/bus/usb/001/009', 'tag': 'Apple, Inc. Optical USB Mouse [Mitsumi]', 'id': '05ac:0304'},
{'device': '/dev/bus/usb/001/001', 'tag': 'Linux Foundation 2.0 root hub', 'id': '1d6b:0002'},
{'device': '/dev/bus/usb/001/002', 'tag': 'Intel Corp. Integrated Rate Matching Hub', 'id': '8087:0020'},
{'device': '/dev/bus/usb/001/004', 'tag': 'Microdia ', 'id': '0c45:641d'}
]

Code Updated for Python 3

import re
import subprocess
device_re = re.compile(b"Bus\s+(?P<bus>\d+)\s+Device\s+(?P<device>\d+).+ID\s(?P<id>\w+:\w+)\s(?P<tag>.+)$", re.I)
df = subprocess.check_output("lsusb")
devices = []
for i in df.split(b'\n'):
    if i:
        info = device_re.match(i)
        if info:
            dinfo = info.groupdict()
            dinfo['device'] = '/dev/bus/usb/%s/%s' % (dinfo.pop('bus'), dinfo.pop('device'))
            devices.append(dinfo)
            
print(devices)

In R, dealing with Error: ggplot2 doesn't know how to deal with data of class numeric

The error happens because of you are trying to map a numeric vector to data in geom_errorbar: GVW[1:64,3]. ggplot only works with data.frame.

In general, you shouldn't subset inside ggplot calls. You are doing so because your standard errors are stored in four separate objects. Add them to your original data.frame and you will be able to plot everything in one call.

Here with a dplyr solution to summarise the data and compute the standard error beforehand.

library(dplyr)
d <- GVW %>% group_by(Genotype,variable) %>%
    summarise(mean = mean(value),se = sd(value) / sqrt(n()))

ggplot(d, aes(x = variable, y = mean, fill = Genotype)) + 
  geom_bar(position = position_dodge(), stat = "identity", 
      colour="black", size=.3) +
  geom_errorbar(aes(ymin = mean - se, ymax = mean + se), 
      size=.3, width=.2, position=position_dodge(.9)) +
  xlab("Time") +
  ylab("Weight [g]") +
  scale_fill_hue(name = "Genotype", breaks = c("KO", "WT"), 
      labels = c("Knock-out", "Wild type")) +
  ggtitle("Effect of genotype on weight-gain") +
  scale_y_continuous(breaks = 0:20*4) +
  theme_bw()

How do you push a Git tag to a branch using a refspec?

I create the tag like this and then I push it to GitHub:

git tag -a v1.1 -m "Version 1.1 is waiting for review"
git push --tags

Counting objects: 1, done.
Writing objects: 100% (1/1), 180 bytes, done.
Total 1 (delta 0), reused 0 (delta 0)
To [email protected]:neoneye/triangle_draw.git
 * [new tag]         v1.1 -> v1.1

Creating a new user and password with Ansible

Generating random password for user

first need to define users variable then follow below

tasks:

- name: Generate Passwords
  become: no
  local_action: command pwgen -N 1 8
  with_items: '{{ users }}'
  register: user_passwords

- name: Update User Passwords
  user:
    name: '{{ item.item }}'
    password: "{{ item.stdout | password_hash('sha512')}}"
    update_password: on_create
  with_items: '{{ user_passwords.results }}'

- name: Save Passwords Locally
  become: no
  local_action: copy content={{ item.stdout }} dest=./{{ item.item }}.txt
  with_items: '{{ user_passwords.results }}'

Multiprocessing a for loop?

You can use multiprocessing.Pool:

from multiprocessing import Pool
class Engine(object):
    def __init__(self, parameters):
        self.parameters = parameters
    def __call__(self, filename):
        sci = fits.open(filename + '.fits')
        manipulated = manipulate_image(sci, self.parameters)
        return manipulated

try:
    pool = Pool(8) # on 8 processors
    engine = Engine(my_parameters)
    data_outputs = pool.map(engine, data_inputs)
finally: # To make sure processes are closed in the end, even if errors happen
    pool.close()
    pool.join()

How to format a java.sql.Timestamp(yyyy-MM-dd HH:mm:ss.S) to a date(yyyy-MM-dd HH:mm:ss)

You do not need to use substring at all since your format doesn't hold that info.

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String fechaStr = "2013-10-10 10:49:29.10000";  
Date fechaNueva = format.parse(fechaStr);

System.out.println(format.format(fechaNueva)); // Prints 2013-10-10 10:49:29

Facebook Oauth Logout

Update: This solution works and just a call to 'FB.logout()' doesn't work because browser wants a user interaction to actually call this function, so that it knows - it is a user not a script.

<a href="#" onclick="FB.logout();">Logout</a> 

@RequestParam in Spring MVC handling optional parameters

As part of Spring 4.1.1 onwards you now have full support of Java 8 Optional (original ticket) therefore in your example both requests will go via your single mapping endpoint as long as you replace required=false with Optional for your 3 params logout, name, password:

@RequestMapping (value = "/submit/id/{id}", method = RequestMethod.GET,   
 produces="text/xml")
public String showLoginWindow(@PathVariable("id") String id,
                              @RequestParam(value = "logout") Optional<String> logout,
                              @RequestParam("name") Optional<String> username,
                              @RequestParam("password") Optional<String> password,
                              @ModelAttribute("submitModel") SubmitModel model,
                              BindingResult errors) throws LoginException {...}

How do you render primitives as wireframes in OpenGL?

If it's OpenGL ES 2.0 you're dealing with, you can choose one of draw mode constants from

GL_LINE_STRIP, GL_LINE_LOOP, GL_LINES, to draw lines,

GL_POINTS (if you need to draw only vertices), or

GL_TRIANGLE_STRIP, GL_TRIANGLE_FAN, and GL_TRIANGLES to draw filled triangles

as first argument to your

glDrawElements(GLenum mode, GLsizei count, GLenum type, const GLvoid * indices)

or

glDrawArrays(GLenum mode, GLint first, GLsizei count) calls.

How to make audio autoplay on chrome

As of April 2018, Chrome's autoplay policies changed:

"Chrome's autoplay policies are simple:

  • Muted autoplay is always allowed.

Autoplay with sound is allowed if:

  • User has interacted with the domain (click, tap, etc.).
  • On desktop, the user's Media Engagement Index threshold has been crossed, meaning the user has previously play video with sound.
  • On mobile, the user has added the site to his or her home screen.

Also

  • Top frames can delegate autoplay permission to their iframes to allow autoplay with sound. "

Chrome's developer site has more information, including some programming examples, which can be found here: https://developers.google.com/web/updates/2017/09/autoplay-policy-changes

Programmatically stop execution of python script?

sys.exit() will do exactly what you want.

import sys
sys.exit("Error message")

What is the difference between bool and Boolean types in C#

Perhaps bool is a tad "lighter" than Boolean; Interestingly, changing this:

namespace DuckbillServerWebAPI.Models
{
    public class Expense
    {
        . . .
        public bool CanUseOnItems { get; set; }
    }
}

...to this:

namespace DuckbillServerWebAPI.Models
{
    public class Expense
    {
        . . .
        public Boolean CanUseOnItems { get; set; }
    }
}

...caused my cs file to sprout a "using System;" Changing the type back to "bool" caused the using clause's hair to turn grey.

(Visual Studio 2010, WebAPI project)

How do multiple clients connect simultaneously to one port, say 80, on a server?

First off, a "port" is just a number. All a "connection to a port" really represents is a packet which has that number specified in its "destination port" header field.

Now, there are two answers to your question, one for stateful protocols and one for stateless protocols.

For a stateless protocol (ie UDP), there is no problem because "connections" don't exist - multiple people can send packets to the same port, and their packets will arrive in whatever sequence. Nobody is ever in the "connected" state.

For a stateful protocol (like TCP), a connection is identified by a 4-tuple consisting of source and destination ports and source and destination IP addresses. So, if two different machines connect to the same port on a third machine, there are two distinct connections because the source IPs differ. If the same machine (or two behind NAT or otherwise sharing the same IP address) connects twice to a single remote end, the connections are differentiated by source port (which is generally a random high-numbered port).

Simply, if I connect to the same web server twice from my client, the two connections will have different source ports from my perspective and destination ports from the web server's. So there is no ambiguity, even though both connections have the same source and destination IP addresses.

Ports are a way to multiplex IP addresses so that different applications can listen on the same IP address/protocol pair. Unless an application defines its own higher-level protocol, there is no way to multiplex a port. If two connections using the same protocol simultaneously have identical source and destination IPs and identical source and destination ports, they must be the same connection.

Converting a String array into an int Array in java

To help debug, and make your code better, do this:

private void processLine(String[] strings) {
    Integer[] intarray=new Integer[strings.length];
    int i=0;
    for(String str:strings){
        try {
            intarray[i]=Integer.parseInt(str);
            i++;
        } catch (NumberFormatException e) {
            throw new IllegalArgumentException("Not a number: " + str + " at index " + i, e);
        }
    }
}

Also, from a code neatness point, you could reduce the lines by doing this:

for (String str : strings)
    intarray[i++] = Integer.parseInt(str);

What's sizeof(size_t) on 32-bit vs the various 64-bit data models?

size_t is defined by the C standard to be the unsigned integer return type of the sizeof operator (C99 6.3.5.4.4), and the argument of malloc and friends (C99 7.20.3.3 etc). The actual range is set such that the maximum (SIZE_MAX) is at least 65535 (C99 7.18.3.2).

However, this doesn't let us determine sizeof(size_t). The implementation is free to use any representation it likes for size_t - so there is no upper bound on size - and the implementation is also free to define a byte as 16-bits, in which case size_t can be equivalent to unsigned char.

Putting that aside, however, in general you'll have 32-bit size_t on 32-bit programs, and 64-bit on 64-bit programs, regardless of the data model. Generally the data model only affects static data; for example, in GCC:

`-mcmodel=small'
     Generate code for the small code model: the program and its
     symbols must be linked in the lower 2 GB of the address space.
     Pointers are 64 bits.  Programs can be statically or dynamically
     linked.  This is the default code model.

`-mcmodel=kernel'
     Generate code for the kernel code model.  The kernel runs in the
     negative 2 GB of the address space.  This model has to be used for
     Linux kernel code.

`-mcmodel=medium'
     Generate code for the medium model: The program is linked in the
     lower 2 GB of the address space but symbols can be located
     anywhere in the address space.  Programs can be statically or
     dynamically linked, but building of shared libraries are not
     supported with the medium model.

`-mcmodel=large'
     Generate code for the large model: This model makes no assumptions
     about addresses and sizes of sections.

You'll note that pointers are 64-bit in all cases; and there's little point to having 64-bit pointers but not 64-bit sizes, after all.

I want to show all tables that have specified column name

SELECT t.name AS table_name,
SCHEMA_NAME(schema_id) AS schema_name,
c.name AS column_name,*
FROM sys.tables AS t
INNER JOIN sys.columns c ON t.OBJECT_ID = c.OBJECT_ID 
WHERE c.name LIKE '%YOUR_COLUMN%' 
ORDER BY schema_name, table_name;

In depth article by SQL Authority

Convert an image (selected by path) to base64 string

You can easily pass the path of the image to retrieve the base64 string

public static string ImageToBase64(string _imagePath)
    {
        string _base64String = null;

        using (System.Drawing.Image _image = System.Drawing.Image.FromFile(_imagePath))
        {
            using (MemoryStream _mStream = new MemoryStream())
            {
                _image.Save(_mStream, _image.RawFormat);
                byte[] _imageBytes = _mStream.ToArray();
                _base64String = Convert.ToBase64String(_imageBytes);

                return "data:image/jpg;base64," + _base64String;
            }
        }
    }

Hope this will help.

Send email with PHP from html form on submit with the same script

You can also use mandrill app to send the mail in php. You will get the API from https://mandrillapp.com/api/docs/index.php.html where you can find the complete details about emails sended and other details.

How to add url parameter to the current url?

There is no way to write a relative URI that preserves the existing query string while adding additional parameters to it.

You have to:

topic.php?id=14&like=like

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

I'm pretty late to the party, but I hope to provide a better answer; shorter and (assuming my benchmark is correct) also much faster.

long goodMask; // 0xC840C04048404040 computed below
{
    for (int i=0; i<64; ++i) goodMask |= Long.MIN_VALUE >>> (i*i);
}

public boolean isSquare(long x) {
    // This tests if the 6 least significant bits are right.
    // Moving the to be tested bit to the highest position saves us masking.
    if (goodMask << x >= 0) return false;
    final int numberOfTrailingZeros = Long.numberOfTrailingZeros(x);
    // Each square ends with an even number of zeros.
    if ((numberOfTrailingZeros & 1) != 0) return false;
    x >>= numberOfTrailingZeros;
    // Now x is either 0 or odd.
    // In binary each odd square ends with 001.
    // Postpone the sign test until now; handle zero in the branch.
    if ((x&7) != 1 | x <= 0) return x == 0;
    // Do it in the classical way.
    // The correctness is not trivial as the conversion from long to double is lossy!
    final long tst = (long) Math.sqrt(x);
    return tst * tst == x;
}

The first test catches most non-squares quickly. It uses a 64-item table packed in a long, so there's no array access cost (indirection and bounds checks). For a uniformly random long, there's a 81.25% probability of ending here.

The second test catches all numbers having an odd number of twos in their factorization. The method Long.numberOfTrailingZeros is very fast as it gets JIT-ed into a single i86 instruction.

After dropping the trailing zeros, the third test handles numbers ending with 011, 101, or 111 in binary, which are no perfect squares. It also cares about negative numbers and also handles 0.

The final test falls back to double arithmetic. As double has only 53 bits mantissa, the conversion from long to double includes rounding for big values. Nonetheless, the test is correct (unless the proof is wrong).

Trying to incorporate the mod255 idea wasn't successful.

Disable scrolling in all mobile devices

use this in style

body
{
overflow:hidden;
width:100%;
}

Use this in head tag

<meta name="viewport" content="user-scalable=no, width=device-width, initial-scale=1.0" />
<meta name="apple-mobile-web-app-capable" content="yes" />

ReferenceError: event is not defined error in Firefox

You're declaring (some of) your event handlers incorrectly:

$('.menuOption').click(function( event ){ // <---- "event" parameter here

    event.preventDefault();
    var categories = $(this).attr('rel');
    $('.pages').hide();
    $(categories).fadeIn();


});

You need "event" to be a parameter to the handlers. WebKit follows IE's old behavior of using a global symbol for "event", but Firefox doesn't. When you're using jQuery, that library normalizes the behavior and ensures that your event handlers are passed the event parameter.

edit — to clarify: you have to provide some parameter name; using event makes it clear what you intend, but you can call it e or cupcake or anything else.

Note also that the reason you probably should use the parameter passed in from jQuery instead of the "native" one (in Chrome and IE and Safari) is that that one (the parameter) is a jQuery wrapper around the native event object. The wrapper is what normalizes the event behavior across browsers. If you use the global version, you don't get that.

Forcing a postback

No, not from code behind. A postback is a request initiated from a page on the client back to itself on the server using the Http POST method. On the server side you can request a redirect but the will be Http GET request.

How to continue the code on the next line in VBA

To have newline in code you use _

Example:

Dim a As Integer
a = 500 _
  + 80 _
  + 90

MsgBox a

How to post pictures to instagram using API

Instagram now allows businesses to schedule their posts, using the new Content Publishing Beta endpoints.

https://developers.facebook.com/blog/post/2018/01/30/instagram-graph-api-updates/

However, this blog post - https://business.instagram.com/blog/instagram-api-features-updates - makes it clear that they are only opening that API to their Facebook Marketing Partners or Instagram Partners.

To get started with scheduling posts, please work with one of our Facebook Marketing Partners or Instagram Partners.

This link from Facebook - https://developers.facebook.com/docs/instagram-api/content-publishing - lists it as a closed beta.

The Content Publishing API is in closed beta with Facebook Marketing Partners and Instagram Partners only. We are not accepting new applicants at this time.

But this is how you would do it:

You have a photo at...

https://www.example.com/images/bronz-fonz.jpg

You want to publish it with the hashtag "#BronzFonz".

You could use the /user/media edge to create the container like this:

POST graph.facebook.com 
  /17841400008460056/media?
    image_url=https%3A%2F%2Fwww.example.com%2Fimages%2Fbronz-fonz.jpg&
    caption=%23BronzFonz

This would return a container ID (let's say 17889455560051444), which you would then publish using the /user/media_publish edge, like this:

POST graph.facebook.com
  /17841405822304914/media_publish
    ?creation_id=17889455560051444

This example from the docs.

What is the best way to conditionally apply attributes in AngularJS?

Was able to get this working:

ng-attr-aria-current="{{::item.isSelected==true ? 'page' : undefined}}"

The nice thing here is that if item.isSelected is false then the attribute simply isn't rendered.

Is String.Contains() faster than String.IndexOf()?

From a little reading, it appears that under the hood the String.Contains method simply calls String.IndexOf. The difference is String.Contains returns a boolean while String.IndexOf returns an integer with (-1) representing that the substring was not found.

I would suggest writing a little test with 100,000 or so iterations and see for yourself. If I were to guess, I'd say that IndexOf may be slightly faster but like I said it just a guess.

Jeff Atwood has a good article on strings at his blog. It's more about concatenation but may be helpful nonetheless.

What does principal end of an association means in 1:1 relationship in Entity framework

In one-to-one relation one end must be principal and second end must be dependent. Principal end is the one which will be inserted first and which can exist without the dependent one. Dependent end is the one which must be inserted after the principal because it has foreign key to the principal.

In case of entity framework FK in dependent must also be its PK so in your case you should use:

public class Boo
{
    [Key, ForeignKey("Foo")]
    public string BooId{get;set;}
    public Foo Foo{get;set;}
}

Or fluent mapping

modelBuilder.Entity<Foo>()
            .HasOptional(f => f.Boo)
            .WithRequired(s => s.Foo);

Use jquery to set value of div tag

When using the .html() method, a htmlString must be the parameter. (source) Put your string inside a HTML tag and it should work or use .text() as suggested by farzad.

Example:

<div class="demo-container">
    <div class="demo-box">Demonstration Box</div>
</div>

<script type="text/javascript">
$("div.demo-container").html( "<p>All new content. <em>You bet!</em></p>" );
</script>

How to download Visual Studio 2017 Community Edition for offline installation?

No, there should be an .exe file (vs_Community_xxxxx.exe) directly in you f:\vs2017c directory !

Just start from the this directory, not from a longer path. the packages downloaded are partly having very long path names, it fails if you start from a longer path.

How do I set the maximum line length in PyCharm?

For PyCharm 2017

We can follow below: File >> Settings >> Editor >> Code Style.

Then provide values for Hard Wrap & Visual Guides for wrapping while typing, tick the checkbox.

NB: look at other tabs as well, viz. Python, HTML, JSON etc.

How to make execution pause, sleep, wait for X seconds in R?

Sys.sleep() will not work if the CPU usage is very high; as in other critical high priority processes are running (in parallel).

This code worked for me. Here I am printing 1 to 1000 at a 2.5 second interval.

for (i in 1:1000)
{
  print(i)
  date_time<-Sys.time()
  while((as.numeric(Sys.time()) - as.numeric(date_time))<2.5){} #dummy while loop
}

How to convert a normal Git repository to a bare one?

In short: replace the contents of repo with the contents of repo/.git, then tell the repository that it is now a bare repository.

To do this, execute the following commands:

cd repo
mv .git ../repo.git # renaming just for clarity
cd ..
rm -fr repo
cd repo.git
git config --bool core.bare true

Note that this is different from doing a git clone --bare to a new location (see below).

How can I sanitize user input with PHP?

No, there is not.

First of all, SQL injection is an input filtering problem, and XSS is an output escaping one - so you wouldn't even execute these two operations at the same time in the code lifecycle.

Basic rules of thumb

  • For SQL query, bind parameters (as with PDO) or use a driver-native escaping function for query variables (such as mysql_real_escape_string())
  • Use strip_tags() to filter out unwanted HTML
  • Escape all other output with htmlspecialchars() and be mindful of the 2nd and 3rd parameters here.

How to change font in ipython notebook

In your notebook (simple approach). Add new cell with following code

%%html
<style type='text/css'>
.CodeMirror{
    font-size: 12px;
}

div.output_area pre {
    font-size: 12px;
}
</style>

Dynamic instantiation from string name of a class in dynamically imported module?

You can use getattr

getattr(module, class_name)

to access the class. More complete code:

module = __import__(module_name)
class_ = getattr(module, class_name)
instance = class_()

As mentioned below, we may use importlib

import importlib
module = importlib.import_module(module_name)
class_ = getattr(module, class_name)
instance = class_()

Does HTML5 <video> playback support the .avi format?

Short answer: No. Use WebM or Ogg instead.

This article covers just about everything you need to know about the <video> element, including which browsers support which container formats and codecs.

Select n random rows from SQL Server table

This link have a interesting comparison between Orderby(NEWID()) and other methods for tables with 1, 7, and 13 millions of rows.

Often, when questions about how to select random rows are asked in discussion groups, the NEWID query is proposed; it is simple and works very well for small tables.

SELECT TOP 10 PERCENT *
  FROM Table1
  ORDER BY NEWID()

However, the NEWID query has a big drawback when you use it for large tables. The ORDER BY clause causes all of the rows in the table to be copied into the tempdb database, where they are sorted. This causes two problems:

  1. The sorting operation usually has a high cost associated with it. Sorting can use a lot of disk I/O and can run for a long time.
  2. In the worst-case scenario, tempdb can run out of space. In the best-case scenario, tempdb can take up a large amount of disk space that never will be reclaimed without a manual shrink command.

What you need is a way to select rows randomly that will not use tempdb and will not get much slower as the table gets larger. Here is a new idea on how to do that:

SELECT * FROM Table1
  WHERE (ABS(CAST(
  (BINARY_CHECKSUM(*) *
  RAND()) as int)) % 100) < 10

The basic idea behind this query is that we want to generate a random number between 0 and 99 for each row in the table, and then choose all of those rows whose random number is less than the value of the specified percent. In this example, we want approximately 10 percent of the rows selected randomly; therefore, we choose all of the rows whose random number is less than 10.

Please read the full article in MSDN.

How do I change an HTML selected option using JavaScript?

Tools as pure JavaScript code for handling Selectbox:

Graphical Understanding:

Image - A

enter image description here


Image - B

enter image description here


Image - C

enter image description here

Updated - 25-June-2019 | Fiddler DEMO

JavaScript Code:

/**
 * Empty Select Box
 * @param eid Element ID
 * @param value text
 * @param text text
 * @author Neeraj.Singh
 */
function emptySelectBoxById(eid, value, text) {
    document.getElementById(eid).innerHTML = "<option value='" + value + "'>" + text + "</option>";
}


/**
 * Reset Select Box
 * @param eid Element ID
 */

function resetSelectBoxById(eid) {
    document.getElementById(eid).options[0].selected = 'selected';
}


/**
 * Set Select Box Selection By Index
 * @param eid Element ID
 * @param eindx Element Index
 */

function setSelectBoxByIndex(eid, eindx) {
    document.getElementById(eid).getElementsByTagName('option')[eindx].selected = 'selected';
    //or
    document.getElementById(eid).options[eindx].selected = 'selected';
}


/**
 * Set Select Box Selection By Value
 * @param eid Element ID
 * @param eval Element Index
 */
function setSelectBoxByValue(eid, eval) {
    document.getElementById(eid).value = eval;
}


/**
 * Set Select Box Selection By Text
 * @param eid Element ID
 * @param eval Element Index
 */
function setSelectBoxByText(eid, etxt) {
    var eid = document.getElementById(eid);
    for (var i = 0; i < eid.options.length; ++i) {
        if (eid.options[i].text === etxt)
            eid.options[i].selected = true;
    }
}


/**
 * Get Select Box Text By ID
 * @param eid Element ID
 * @return string
 */

function getSelectBoxText(eid) {
    return document.getElementById(eid).options[document.getElementById(eid).selectedIndex].text;
}


/**
 * Get Select Box Value By ID
 * @param eid Element ID
 * @return string
 */

function getSelectBoxValue(id) {
    return document.getElementById(id).options[document.getElementById(id).selectedIndex].value;
}

Eclipse reported "Failed to load JNI shared library"

First, ensure that your version of Eclipse and JDK match, either both 64-bit or both 32-bit (you can't mix-and-match 32-bit with 64-bit).

Second, the -vm argument in eclipse.ini should point to the java executable. See http://wiki.eclipse.org/Eclipse.ini for examples.

If you're unsure of what version (64-bit or 32-bit) of Eclipse you have installed, you can determine that a few different ways. See How to find out if an installed Eclipse is 32 or 64 bit version?

Getting "TypeError: failed to fetch" when the request hasn't actually failed

I know it's a relative old post but, I would like to share what worked for me: I've simply input "http://" before "localhost" in the url. Hope it helps somebody.

nvm is not compatible with the npm config "prefix" option:

I ran into this while using node installed via nvm, with nvm installed via homebrew. I solved it by running brew uninstall nvm, rm -rf $NVM_DIR, then reinstalling nvm using the official install script and reinstalling the node version I needed.

Note: I also had $NVM_DIR mounted and symlinked. I moved it back into my homedir.

How to check not in array element

$array1 = "Orange";
$array2 = array("Apple","Grapes","Orange","Pineapple");
if(in_array($array1,$array2)){
    echo $array1.' exists in array2';
}else{
    echo $array1.'does not exists in array2';
}

Git fast forward VS no fast forward merge

The --no-ff option is useful when you want to have a clear notion of your feature branch. So even if in the meantime no commits were made, FF is possible - you still want sometimes to have each commit in the mainline correspond to one feature. So you treat a feature branch with a bunch of commits as a single unit, and merge them as a single unit. It is clear from your history when you do feature branch merging with --no-ff.

If you do not care about such thing - you could probably get away with FF whenever it is possible. Thus you will have more svn-like feeling of workflow.

For example, the author of this article thinks that --no-ff option should be default and his reasoning is close to that I outlined above:

Consider the situation where a series of minor commits on the "feature" branch collectively make up one new feature: If you just do "git merge feature_branch" without --no-ff, "it is impossible to see from the Git history which of the commit objects together have implemented a feature—you would have to manually read all the log messages. Reverting a whole feature (i.e. a group of commits), is a true headache [if --no-ff is not used], whereas it is easily done if the --no-ff flag was used [because it's just one commit]."

Graphic showing how --no-ff groups together all commits from feature branch into one commit on master branch

Is there a way to detect if an image is blurry?

I tried solution based on Laplacian filter from this post. It didn't help me. So, I tried the solution from this post and it was good for my case (but is slow):

import cv2

image = cv2.imread("test.jpeg")
height, width = image.shape[:2]
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)

def px(x, y):
    return int(gray[y, x])

sum = 0
for x in range(width-1):
    for y in range(height):
        sum += abs(px(x, y) - px(x+1, y))

Less blurred image has maximum sum value!

You can also tune speed and accuracy by changing step, e.g.

this part

for x in range(width - 1):

you can replace with this one

for x in range(0, width - 1, 10):

In JavaScript can I make a "click" event fire programmatically for a file input element?

$(document).one('mousemove', function() { $(element).trigger('click') } );

Worked for me when I ran into similar problem, it's a regular eRube Goldberg.

Combine two (or more) PDF's

Following method gets a List of byte array which is PDF byte array and then returns a byte array.

using ...;
using PdfSharp.Pdf;
using PdfSharp.Pdf.IO;

public static class PdfHelper
{
    public static byte[] PdfConcat(List<byte[]> lstPdfBytes)
    {
        byte[] res;

        using (var outPdf = new PdfDocument())
        {
            foreach (var pdf in lstPdfBytes)
            {
                using (var pdfStream = new MemoryStream(pdf))
                using (var pdfDoc = PdfReader.Open(pdfStream, PdfDocumentOpenMode.Import))
                    for (var i = 0; i < pdfDoc.PageCount; i++)
                        outPdf.AddPage(pdfDoc.Pages[i]);
            }

            using (var memoryStreamOut = new MemoryStream())
            {
                outPdf.Save(memoryStreamOut, false);

                res = Stream2Bytes(memoryStreamOut);
            }
        }

        return res;
    }

    public static void DownloadAsPdfFile(string fileName, byte[] content)
    {
        var ms = new MemoryStream(content);

        HttpContext.Current.Response.Clear();
        HttpContext.Current.Response.ContentType = "application/pdf";
        HttpContext.Current.Response.AddHeader("content-disposition", $"attachment;filename={fileName}.pdf");
        HttpContext.Current.Response.Buffer = true;
        ms.WriteTo(HttpContext.Current.Response.OutputStream);
        HttpContext.Current.Response.End();
    }

    private static byte[] Stream2Bytes(Stream input)
    {
        var buffer = new byte[input.Length];
        using (var ms = new MemoryStream())
        {
            int read;
            while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
                ms.Write(buffer, 0, read);

            return ms.ToArray();
        }
    }
}

So, the result of PdfHelper.PdfConcat method is passed to PdfHelper.DownloadAsPdfFile method.

PS: A NuGet package named [PdfSharp][1] need to be installed. So in the Package Manage Console window type:

Install-Package PdfSharp

Date Difference in php on days?

I would recommend to use date->diff function, as in example below:

   $dStart = new DateTime('2012-07-26');
   $dEnd  = new DateTime('2012-08-26');
   $dDiff = $dStart->diff($dEnd);
   echo $dDiff->format('%r%a'); // use for point out relation: smaller/greater

see http://www.php.net/manual/en/datetime.diff.php

Find Number of CPUs and Cores per CPU using Command Prompt

If you want to find how many processors (or CPUs) a machine has the same way %NUMBER_OF_PROCESSORS% shows you the number of cores, save the following script in a batch file, for example, GetNumberOfCores.cmd:

@echo off
for /f "tokens=*" %%f in ('wmic cpu get NumberOfCores /value ^| find "="') do set %%f

And then execute like this:

GetNumberOfCores.cmd

echo %NumberOfCores%

The script will set a environment variable named %NumberOfCores% and it will contain the number of processors.

How npm start runs a server on port 8000

You can change the port in the console by running the following on Windows:

SET PORT=8000

For Mac, Linux or Windows WSL use the following:

export PORT=8000

The export sets the environment variable for the current shell and all child processes like npm that might use it.

If you want the environment variable to be set just for the npm process, precede the command with the environment variable like this (on Mac and Linux and Windows WSL):

PORT=8000 npm run start

java.lang.ClassNotFoundException: Didn't find class on path: dexpathlist

The following solution worked for me...

I tried everything mentioned above but still didn't get my app running. I have react-native app running on latest version of gradle 4+ and android studio.

I had the issue where if i run react-native run-android it was failing with issue saying its not able to find MainApplication class...i.e ClassNotFoundException

I was able to resolve the issue when I updated my gradle.properties to use the compiler D8.

I added:

android.enableD8=true

to my gradle.properties

Doc Details here: https://android-developers.googleblog.com/2017/08/next-generation-dex-compiler-now-in.html

Number to String in a formula field

I believe this is what you're looking for:

Convert Decimal Numbers to Text showing only the non-zero decimals

Especially this line might be helpful:

StringVar text     :=  Totext ( {Your.NumberField} , 6 , ""  )  ;

The first parameter is the decimal to be converted, the second parameter is the number of decimal places and the third parameter is the separator for thousands/millions etc.

How to check a Long for null in java

You can check Long object for null value with longValue == null , you can use longValue == 0L for long (primitive), because default value of long is 0L, but it's result will be true if longValue is zero too

Convert all data frame character columns to factors

I used to do a simple for loop. As @A5C1D2H2I1M1N2O1R2T1 answer, lapply is a nice solution. But if you convert all the columns, you will need a data.frame before, otherwise you will end up with a list. Little execution time differences.

 mm2N=mm2New[,10:18]
 str(mm2N)
'data.frame':   35487 obs. of  9 variables:
 $ bb    : int  4 6 2 3 3 2 5 2 1 2 ...
 $ vabb  : int  -3 -3 -2 -2 -3 -1 0 0 3 3 ...
 $ bb55  : int  7 6 3 4 4 4 9 2 5 4 ...
 $ vabb55: int  -3 -1 0 -1 -2 -2 -3 0 -1 3 ...
 $ zr    : num  0 -2 -1 1 -1 -1 -1 1 1 0 ...
 $ z55r  : num  -2 -2 0 1 -2 -2 -2 1 -1 1 ...
 $ fechar: num  0 -1 1 0 1 1 0 0 1 0 ...
 $ varr  : num  3 3 1 1 1 1 4 1 1 3 ...
 $ minmax: int  3 0 4 6 6 6 0 6 6 1 ...

 # For solution
 t1=Sys.time()
 for(i in 1:ncol(mm2N)) mm2N[,i]=as.factor(mm2N[,i])
 Sys.time()-t1
Time difference of 0.2020121 secs
 str(mm2N)
'data.frame':   35487 obs. of  9 variables:
 $ bb    : Factor w/ 6 levels "1","2","3","4",..: 4 6 2 3 3 2 5 2 1 2 ...
 $ vabb  : Factor w/ 7 levels "-3","-2","-1",..: 1 1 2 2 1 3 4 4 7 7 ...
 $ bb55  : Factor w/ 8 levels "2","3","4","5",..: 6 5 2 3 3 3 8 1 4 3 ...
 $ vabb55: Factor w/ 7 levels "-3","-2","-1",..: 1 3 4 3 2 2 1 4 3 7 ...
 $ zr    : Factor w/ 5 levels "-2","-1","0",..: 3 1 2 4 2 2 2 4 4 3 ...
 $ z55r  : Factor w/ 5 levels "-2","-1","0",..: 1 1 3 4 1 1 1 4 2 4 ...
 $ fechar: Factor w/ 3 levels "-1","0","1": 2 1 3 2 3 3 2 2 3 2 ...
 $ varr  : Factor w/ 5 levels "1","2","3","4",..: 3 3 1 1 1 1 4 1 1 3 ...
 $ minmax: Factor w/ 7 levels "0","1","2","3",..: 4 1 5 7 7 7 1 7 7 2 ...

 #lapply solution
 mm2N=mm2New[,10:18]
 t1=Sys.time()
 mm2N <- lapply(mm2N, as.factor)
 Sys.time()-t1
Time difference of 0.209012 secs
 str(mm2N)
List of 9
 $ bb    : Factor w/ 6 levels "1","2","3","4",..: 4 6 2 3 3 2 5 2 1 2 ...
 $ vabb  : Factor w/ 7 levels "-3","-2","-1",..: 1 1 2 2 1 3 4 4 7 7 ...
 $ bb55  : Factor w/ 8 levels "2","3","4","5",..: 6 5 2 3 3 3 8 1 4 3 ...
 $ vabb55: Factor w/ 7 levels "-3","-2","-1",..: 1 3 4 3 2 2 1 4 3 7 ...
 $ zr    : Factor w/ 5 levels "-2","-1","0",..: 3 1 2 4 2 2 2 4 4 3 ...
 $ z55r  : Factor w/ 5 levels "-2","-1","0",..: 1 1 3 4 1 1 1 4 2 4 ...
 $ fechar: Factor w/ 3 levels "-1","0","1": 2 1 3 2 3 3 2 2 3 2 ...
 $ varr  : Factor w/ 5 levels "1","2","3","4",..: 3 3 1 1 1 1 4 1 1 3 ...
 $ minmax: Factor w/ 7 levels "0","1","2","3",..: 4 1 5 7 7 7 1 7 7 2 ...

 #data.frame lapply solution
 mm2N=mm2New[,10:18]
 t1=Sys.time()
 mm2N <- data.frame(lapply(mm2N, as.factor))
 Sys.time()-t1
Time difference of 0.2010119 secs
 str(mm2N)
'data.frame':   35487 obs. of  9 variables:
 $ bb    : Factor w/ 6 levels "1","2","3","4",..: 4 6 2 3 3 2 5 2 1 2 ...
 $ vabb  : Factor w/ 7 levels "-3","-2","-1",..: 1 1 2 2 1 3 4 4 7 7 ...
 $ bb55  : Factor w/ 8 levels "2","3","4","5",..: 6 5 2 3 3 3 8 1 4 3 ...
 $ vabb55: Factor w/ 7 levels "-3","-2","-1",..: 1 3 4 3 2 2 1 4 3 7 ...
 $ zr    : Factor w/ 5 levels "-2","-1","0",..: 3 1 2 4 2 2 2 4 4 3 ...
 $ z55r  : Factor w/ 5 levels "-2","-1","0",..: 1 1 3 4 1 1 1 4 2 4 ...
 $ fechar: Factor w/ 3 levels "-1","0","1": 2 1 3 2 3 3 2 2 3 2 ...
 $ varr  : Factor w/ 5 levels "1","2","3","4",..: 3 3 1 1 1 1 4 1 1 3 ...
 $ minmax: Factor w/ 7 levels "0","1","2","3",..: 4 1 5 7 7 7 1 7 7 2 ...

How to fix 'fs: re-evaluating native module sources is not supported' - graceful-fs

I was able to fix it by:

  1. updating by package.json
  2. deleting the node_modules folder
  3. executing npm install

Error: Unable to run mksdcard SDK tool

Here's what you need to do to fix the issue on Arch Linux :

  1. Enable the multilib repository on your system if you have not already done so by uncommenting the [multilib] section in /etc/pacman.conf :

    [multilib]
    Include = /etc/pacman.d/mirrorlist
    
  2. Update pacman :

    # pacman -Suy
    
  3. Install the 32 bit version of libstdc++5 :

    # pacman -S lib32-libstdc++5
    

Purpose of ESI & EDI registers?

Opcodes like MOVSB and MOVSW that efficiently copy data from the memory pointed to by ESI to the memory pointed to by EDI. Thus,

mov esi, source_address
mov edi, destination_address
mov ecx, byte_count
cld
rep movsb ; fast!

Why Is `Export Default Const` invalid?

Paul's answer is the one you're looking for. However, as a practical matter, I think you may be interested in the pattern I've been using in my own React+Redux apps.

Here's a stripped-down example from one of my routes, showing how you can define your component and export it as default with a single statement:

import React from 'react';
import { connect } from 'react-redux';

@connect((state, props) => ({
    appVersion: state.appVersion
    // other scene props, calculated from app state & route props
}))
export default class SceneName extends React.Component { /* ... */ }

(Note: I use the term "Scene" for the top-level component of any route).

I hope this is helpful. I think it's much cleaner-looking than the conventional connect( mapState, mapDispatch )( BareComponent )

How to make borders collapse (on a div)?

Instead using border use box-shadow:

  box-shadow: 
    2px 0 0 0 #888, 
    0 2px 0 0 #888, 
    2px 2px 0 0 #888,   /* Just to fix the corner */
    2px 0 0 0 #888 inset, 
    0 2px 0 0 #888 inset;

Demo: http://codepen.io/Hawkun/pen/rsIEp

How long is the SHA256 hash?

A sha256 is 256 bits long -- as its name indicates.

Since sha256 returns a hexadecimal representation, 4 bits are enough to encode each character (instead of 8, like for ASCII), so 256 bits would represent 64 hex characters, therefore you need a varchar(64), or even a char(64), as the length is always the same, not varying at all.

And the demo :

$hash = hash('sha256', 'hello, world!');
var_dump($hash);

Will give you :

$ php temp.php
string(64) "68e656b251e67e8358bef8483ab0d51c6619f3e7a1a9f0e75838d41ff368f728"

i.e. a string with 64 characters.

MySQL Error: #1142 - SELECT command denied to user

You should have to just clear sessions data thats it everything will work

What's the scope of a variable initialized in an if statement?

Yes. It is also true for for scope. But not functions of course.

In your example: if the condition in the if statement is false, x will not be defined though.

linux: kill background task

There's a special variable for this in bash:

kill $!

$! expands to the PID of the last process executed in the background.

Sublime Text 2 multiple line edit

ctrl + shift + right-click it works better that way

How to remove multiple indexes from a list at the same time?

There wasn't much hint on performance for the different ways so I performed a test on removing 5000 items from 50000 in all 3 generally different approaches, and for me numpy was the winner (if you have elements that fit in numpy):

  • 7.5 sec for the enumerated list comprehension [4.5 sec on another PC]
  • 0.08 sec for deleting items in reverse order [0.017 (!) sec]
  • 0.009 sec for numpy.delete [0.006 sec]

Here's the code I timed (in the third function conversion from/to list may be removed if working directly on numpy arrays is ok):

import time
import numpy as np
import random

def del_list_indexes(l, id_to_del):
    somelist = [i for j, i in enumerate(l) if j not in id_to_del]
    return somelist

def del_list_inplace(l, id_to_del):
    for i in sorted(id_to_del, reverse=True):
        del(l[i])

def del_list_numpy(l, id_to_del):
    arr = np.array(l, dtype='int32')
    return list(np.delete(arr, id_to_del))

l = range(50000)
random.shuffle(l)
remove_id = random.sample(range(len(l)), 5000) # 10% ==> 5000

# ...

Embedding a media player in a website using HTML

If you are using HTML 5, there is the <audio> element.

On MDN:

The audio element is used to embed sound content in an HTML or XHTML document. The audio element was added as part of HTML5.


Update:

In order to play audio in the browser in HTML versions before 5 (including XHTML), you need to use one of the many flash audio players.

mysql update multiple columns with same now()

MySQL evaluates now() once per statement when the statement commences execution. So it is safe to have multiple visible now() calls per statement.

select now(); select now(), sleep(10), now(); select now();
+---------------------+
| now()               |
+---------------------+
| 2018-11-05 16:54:00 |
+---------------------+
1 row in set (0.00 sec)

+---------------------+-----------+---------------------+
| now()               | sleep(10) | now()               |
+---------------------+-----------+---------------------+
| 2018-11-05 16:54:00 |         0 | 2018-11-05 16:54:00 |
+---------------------+-----------+---------------------+
1 row in set (10.00 sec)

+---------------------+
| now()               |
+---------------------+
| 2018-11-05 16:54:10 |
+---------------------+
1 row in set (0.00 sec)

How to sort a List of objects by their date (java collections, List<Object>)

I'd add Commons NullComparator instead to avoid some problems...

Convert UTC dates to local time in PHP

date() and localtime() both use the local timezone for the server unless overridden; you can override the timezone used with date_default_timezone_set().

http://www.php.net/manual/en/function.date-default-timezone-set.php

http://us3.php.net/manual/en/function.date.php

http://php.net/manual/en/function.localtime.php

How can prepared statements protect from SQL injection attacks?

Here is SQL for setting up an example:

CREATE TABLE employee(name varchar, paymentType varchar, amount bigint);

INSERT INTO employee VALUES('Aaron', 'salary', 100);
INSERT INTO employee VALUES('Aaron', 'bonus', 50);
INSERT INTO employee VALUES('Bob', 'salary', 50);
INSERT INTO employee VALUES('Bob', 'bonus', 0);

The Inject class is vulnerable to SQL injection. The query is dynamically pasted together with user input. The intent of the query was to show information about Bob. Either salary or bonus, based on user input. But the malicious user manipulates the input corrupting the query by tacking on the equivalent of an 'or true' to the where clause so that everything is returned, including the information about Aaron which was supposed to be hidden.

import java.sql.*;

public class Inject {

    public static void main(String[] args) throws SQLException {

        String url = "jdbc:postgresql://localhost/postgres?user=user&password=pwd";
        Connection conn = DriverManager.getConnection(url);

        Statement stmt = conn.createStatement();
        String sql = "SELECT paymentType, amount FROM employee WHERE name = 'bob' AND paymentType='" + args[0] + "'";
        System.out.println(sql);
        ResultSet rs = stmt.executeQuery(sql);

        while (rs.next()) {
            System.out.println(rs.getString("paymentType") + " " + rs.getLong("amount"));
        }
    }
}

Running this, the first case is with normal usage, and the second with the malicious injection:

c:\temp>java Inject salary
SELECT paymentType, amount FROM employee WHERE name = 'bob' AND paymentType='salary'
salary 50

c:\temp>java Inject "salary' OR 'a'!='b"
SELECT paymentType, amount FROM employee WHERE name = 'bob' AND paymentType='salary' OR 'a'!='b'
salary 100
bonus 50
salary 50
bonus 0

You should not build your SQL statements with string concatenation of user input. Not only is it vulnerable to injection, but it has caching implications on the server as well (the statement changes, so less likely to get a SQL statement cache hit whereas the bind example is always running the same statement).

Here is an example of Binding to avoid this kind of injection:

import java.sql.*;

public class Bind {

    public static void main(String[] args) throws SQLException {

        String url = "jdbc:postgresql://localhost/postgres?user=postgres&password=postgres";
        Connection conn = DriverManager.getConnection(url);

        String sql = "SELECT paymentType, amount FROM employee WHERE name = 'bob' AND paymentType=?";
        System.out.println(sql);

        PreparedStatement stmt = conn.prepareStatement(sql);
        stmt.setString(1, args[0]);

        ResultSet rs = stmt.executeQuery();

        while (rs.next()) {
            System.out.println(rs.getString("paymentType") + " " + rs.getLong("amount"));
        }
    }
}

Running this with the same input as the previous example shows the malicious code does not work because there is no paymentType matching that string:

c:\temp>java Bind salary
SELECT paymentType, amount FROM employee WHERE name = 'bob' AND paymentType=?
salary 50

c:\temp>java Bind "salary' OR 'a'!='b"
SELECT paymentType, amount FROM employee WHERE name = 'bob' AND paymentType=?

Illegal mix of collations MySQL Error

I found that using cast() was the best solution for me:

cast(Format(amount, "Standard") AS CHAR CHARACTER SET utf8) AS Amount

There is also a convert() function. More details on it here

Another resource here

How to generate a random number between 0 and 1?

In your version rand() % 10000 will yield an integer between 0 and 9999. Since RAND_MAX may be as little as 32767, and since this is not exactly divisible by 10000 and not large relative to 10000, there will be significant bias in the 'randomness' of the result, moreover, the maximum value will be 0.9999, not 1.0, and you have unnecessarily restricted your values to four decimal places.

It is simple arithmetic, a random number divided by the maximum possible random number will yield a number from 0 to 1 inclusive, while utilising the full resolution and distribution of the RNG

double r2()
{
    return (double)rand() / (double)RAND_MAX ;
}

Use (double)rand() / (double)((unsigned)RAND_MAX + 1) if exclusion of 1.0 was intentional.