Programs & Examples On #Upcasting

Upcasting permits an object of a subclass type to be treated as an object of any superclass type.

Why do we assign a parent reference to the child object in Java?

You declare parent as Parent, so java will provide only methods and attributes of the Parent class.

Child child = new Child();

should work. Or

Parent child = new Child();
((Child)child).salary = 1;

What is the difference between up-casting and down-casting with respect to class variable

Better try this method for upcasting, it's easy to understand:

/* upcasting problem */
class Animal
{ 
    public void callme()
    {
        System.out.println("In callme of Animal");
    }
}

class Dog extends Animal 
{ 
    public void callme()
    {
        System.out.println("In callme of Dog");
    }

    public void callme2()
    {
        System.out.println("In callme2 of Dog");
    }
}

public class Useanimlas 
{
    public static void main (String [] args) 
    {
        Animal animal = new Animal ();
        Dog dog = new Dog();
        Animal ref;
        ref = animal;
        ref.callme();
        ref = dog;
        ref.callme();
    }
}

downcast and upcast

Upcasting (using (Employee)someInstance) is generally easy as the compiler can tell you at compile time if a type is derived from another.

Downcasting however has to be done at run time generally as the compiler may not always know whether the instance in question is of the type given. C# provides two operators for this - is which tells you if the downcast works, and return true/false. And as which attempts to do the cast and returns the correct type if possible, or null if not.

To test if an employee is a manager:

Employee m = new Manager();
Employee e = new Employee();

if(m is Manager) Console.WriteLine("m is a manager");
if(e is Manager) Console.WriteLine("e is a manager");

You can also use this

Employee someEmployee = e  as Manager;
    if(someEmployee  != null) Console.WriteLine("someEmployee (e) is a manager");

Employee someEmployee = m  as Manager;
    if(someEmployee  != null) Console.WriteLine("someEmployee (m) is a manager");

How can I append a string to an existing field in MySQL?

Update image field to add full URL, ignoring null fields:

UPDATE test SET image = CONCAT('https://my-site.com/images/',image) WHERE image IS NOT NULL;

Show hide div using codebehind

Hiding on the Client Side with javascript

Using plain old javascript, you can easily hide the same element in this manner:

var myDivElem = document.getElementById("myDiv");
myDivElem.style.display = "none";

Then to show again:

myDivElem.style.display = "";

jQuery makes hiding elements a little simpler if you prefer to use jQuery:

var myDiv = $("#<%=myDiv.ClientID%>");
myDiv.hide();

... and to show:

myDiv.show();

Display last git commit comment

This command will get you the last commit message:

git log -1 --oneline --format=%s | sed 's/^.*: //'

outputs something similar to:

Create FUNDING.yml

You can change the -1 to any negative number to increase the range of commit messages retrieved

jQuery find element by data attribute value

You can also use .filter()

$('.slide-link').filter('[data-slide="0"]').addClass('active');

How to do something to each file in a directory with a batch script

Alternatively, use:

forfiles /s /m *.png /c "cmd /c echo @path"

The forfiles command is available in Windows Vista and up.

Create a user with all privileges in Oracle

My issue was, i am unable to create a view with my "scott" user in oracle 11g edition. So here is my solution for this

Error in my case

SQL>create view v1 as select * from books where id=10;

insufficient privileges.

Solution

1)open your cmd and change your directory to where you install your oracle database. in my case i was downloaded in E drive so my location is E:\app\B_Amar\product\11.2.0\dbhome_1\BIN> after reaching in the position you have to type sqlplus sys as sysdba

E:\app\B_Amar\product\11.2.0\dbhome_1\BIN>sqlplus sys as sysdba

2) Enter password: here you have to type that password that you give at the time of installation of oracle software.

3) Here in this step if you want create a new user then you can create otherwise give all the privileges to existing user.

for creating new user

SQL> create user abc identified by xyz;

here abc is user and xyz is password.

giving all the privileges to abc user

SQL> grant all privileges to abc;

 grant succeeded. 

if you are seen this message then all the privileges are giving to the abc user.

4) Now exit from cmd, go to your SQL PLUS and connect to the user i.e enter your username & password.Now you can happily create view.

In My case

in cmd E:\app\B_Amar\product\11.2.0\dbhome_1\BIN>sqlplus sys as sysdba

SQL> grant all privileges to SCOTT;

grant succeeded.

Now I can create views.

Is there an addHeaderView equivalent for RecyclerView?

Based on this post, I created a subclass of RecyclerView.Adapter that supports an arbitrary number of headers and footers.

https://gist.github.com/mheras/0908873267def75dc746

Although it seems to be a solution, I also think this thing should be managed by the LayoutManager. Unfortunately, I need it now and I don't have time to implement a StaggeredGridLayoutManager from scratch (nor even extend from it).

I'm still testing it, but you can try it out if you want. Please let me know if you find any issues with it.

What is the difference between "px", "dip", "dp" and "sp"?

Please read the answer from community wiki. Below mentioned are some information to be considered in addition to the above answers. Most Android developers miss this while developing apps, so I am adding these points.

sp = scale independent pixel

dp = density independent pixels

dpi = density pixels

I have gone through the above answers...not finding them exactly correct. sp for text size, dp for layout bounds - standard. But sp for text size will break the layout if used carelessly in most of the devices.

sp take the textsize of the device, whereas dp take that of device density standard( never change in a device) Say 100sp text can occupies 80% of screen or 100% of screen depending on the font size set in device

enter image description here

You can use sp for layout bounds also, it will work :) No standard app use sp for whole text

Use sp and dp for text size considering UX.

  • Dont use sp for text in toolbar( can use android dimens available for different screen sizes with dp)
  • Dont use sp for text in small bounded buttons, very smaller text, etc

Some people use huge FONT size in their phone for more readability, giving them small hardcoded sized text will be an UX issue. Put sp for text where necessary, but make sure it won't break the layout when user changes his settings.

Similarly if you have a single app supporting all dimensions, adding xxxhdpi assets increases the app size a lot. But now xxxhdpi phones are common so we have to include xxxhdpi assets atleast for icons in side bar, toolbar and bottom bar. Its better to move to vector images to have a uniform and better quality images for all screen sizes.

Also note that people use custom font in their phone. So lack of a font can cause problems regarding spacing and all. Say text size 12sp for a custom font may take some pixels extra than default font.

Refer google developer site for screendensities and basedensity details for android. https://developer.android.com/training/multiscreen/screendensities

possible EventEmitter memory leak detected

Thanks to RLaaa for giving me an idea how to solve the real problem/root cause of the warning. Well in my case it was MySQL buggy code.

Providing you wrote a Promise with code inside like this:

pool.getConnection((err, conn) => {

  if(err) reject(err)

  const q = 'SELECT * from `a_table`'

  conn.query(q, [], (err, rows) => {

    conn.release()

    if(err) reject(err)

    // do something
  })

  conn.on('error', (err) => {

     reject(err)
  })
})

Notice there is a conn.on('error') listener in the code. That code literally adding listener over and over again depends on how many times you call the query. Meanwhile if(err) reject(err) does the same thing.

So I removed the conn.on('error') listener and voila... solved! Hope this helps you.

How do I detect the Python version at runtime?

Here's some code I use with sys.version_info to check the Python installation:

def check_installation(rv):
    current_version = sys.version_info
    if current_version[0] == rv[0] and current_version[1] >= rv[1]:
        pass
    else:
        sys.stderr.write( "[%s] - Error: Your Python interpreter must be %d.%d or greater (within major version %d)\n" % (sys.argv[0], rv[0], rv[1], rv[0]) )
        sys.exit(-1)
    return 0

...

# Calling the 'check_installation' function checks if Python is >= 2.7 and < 3
required_version = (2,7)
check_installation(required_version)

What is /var/www/html?

In the most shared hosts you can't set it.

On a VPS or dedicated server, you can set it, but everything has its price.

On shared hosts, in general you receive a Linux account, something such as /home/(your username)/, and the equivalent of /var/www/html turns to /home/(your username)/public_html/ (or something similar, such as /home/(your username)/www)

If you're accessing your account via FTP, you automatically has accessing the your */home/(your username)/ folder, just find the www or public_html and put your site in it.

If you're using absolute path in the code, bad news, you need to refactor it to use relative paths in the code, at least in a shared host.

MySQL Workbench not opening on Windows

it might be due to running of xampp or wampp server stop all services running and try to open mysql command line

Java heap terminology: young, old and permanent generations?

What is the young generation?

The Young Generation is where all new objects are allocated and aged. When the young generation fills up, this causes a minor garbage collection. A young generation full of dead objects is collected very quickly. Some survived objects are aged and eventually move to the old generation.

What is the old generation?

The Old Generation is used to store long surviving objects. Typically, a threshold is set for young generation object and when that age is met, the object gets moved to the old generation. Eventually the old generation needs to be collected. This event is called a major garbage collection

What is the permanent generation?

The Permanent generation contains metadata required by the JVM to describe the classes and methods used in the application. The permanent generation is populated by the JVM at runtime based on classes in use by the application.

PermGen has been replaced with Metaspace since Java 8 release.

PermSize & MaxPermSize parameters will be ignored now

How does the three generations interact/relate to each other?

enter image description here

Image source & oracle technetwork tutorial article: http://www.oracle.com/webfolder/technetwork/tutorials/obe/java/gc01/index.html

"The General Garbage Collection Process" in above article explains the interactions between them with many diagrams.

Have a look at summary diagram:

enter image description here

Cross domain POST request is not sending cookie Ajax Jquery

I had this same problem. The session ID is sent in a cookie, but since the request is cross-domain, the browser's security settings will block the cookie from being sent.

Solution: Generate the session ID on the client (in the browser), use Javascript sessionStorage to store the session ID then send the session ID with each request to the server.

I struggled a lot with this issue, and there weren't many good answers around. Here's an article detailing the solution: Javascript Cross-Domain Request With Session

Design Android EditText to show error message as described by google

Call myTextInputLayout.setError() instead of myEditText.setError().

These container and containment have double functionality on setting errors. Functionality you need is container's one. But you could require minimal version of 23 for that.

How to add line breaks to an HTML textarea?

I have a textarea with id is #infoartist follow:

<textarea id="infoartist" ng-show="dForm" style="width: 100%;" placeholder="Tell your contacts and collectors about yourself."></textarea>

In javascript code, i'll get value of textarea and replace escaping new line (\n\r) by <br /> tag, such as:

var text = document.getElementById("infoartist").value;
text = text.replace(/\r?\n/g, '<br />');

So if you are using jquery (like me):

var text = $("#infoartist").val();
text = text.replace(/\r?\n/g, '<br />');

Hope it helped you. :-)

Why do we use $rootScope.$broadcast in AngularJS?

  1. What does $rootScope.$broadcast do?

    $rootScope.$broadcast is sending an event through the application scope. Any children scope of that app can catch it using a simple: $scope.$on().

    It is especially useful to send events when you want to reach a scope that is not a direct parent (A branch of a parent for example)

    !!! One thing to not do however is to use $rootScope.$on from a controller. $rootScope is the application, when your controller is destroyed that event listener will still exist, and when your controller will be created again, it will just pile up more event listeners. (So one broadcast will be caught multiple times). Use $scope.$on() instead, and the listeners will also get destroyed.

  2. What is the difference between $rootScope.$broadcast & $rootScope.$broadcast.apply?

    Sometimes you have to use apply(), especially when working with directives and other JS libraries. However since I don't know that code base, I wouldn't be able to tell if that's the case here.

Adding click event listener to elements with the same class

The problem with using querySelectorAll and a for loop is that it creates a whole new event handler for each element in the array.

Sometimes that is exactly what you want. But if you have many elements, it may be more efficient to create a single event handler and attach it to a container element. You can then use event.target to refer to the specific element which triggered the event:

document.body.addEventListener("click", function (event) {
  if (event.target.classList.contains("delete")) {
    var title = event.target.getAttribute("title");

    if (!confirm("sure u want to delete " + title)) {
      event.preventDefault();
    }
  }
});

In this example we only create one event handler which is attached to the body element. Whenever an element inside the body is clicked, the click event bubbles up to our event handler.

How to use Monitor (DDMS) tool to debug application

Go to

Tools > Android > Android Device Monitor

in v0.8.6. That will pull up the DDMS eclipse perspective.

how to open

How to remove files and directories quickly via terminal (bash shell)

rm -rf *

Would remove everything (folders & files) in the current directory.

But be careful! Only execute this command if you are absolutely sure, that you are in the right directory.

Loop through JSON object List

This will work!

$(document).ready(function ()
    {
        $.ajax(
            {
            type: 'POST',
            url: "/Home/MethodName",
            success: function (data) {
                //data is the string that the method returns in a json format, but in string
                var jsonData = JSON.parse(data); //This converts the string to json

                for (var i = 0; i < jsonData.length; i++) //The json object has lenght
                {
                    var object = jsonData[i]; //You are in the current object
                    $('#olListId').append('<li class="someclass>' + object.Atributte  + '</li>'); //now you access the property.

                }

                /* JSON EXAMPLE
                [{ "Atributte": "value" }, 
                { "Atributte": "value" }, 
                { "Atributte": "value" }]
                */
            }
        });
    });

The main thing about this is using the property exactly the same as the attribute of the JSON key-value pair.

How to remove commits from a pull request

This is what helped me:

  1. Create a new branch with the existing one. Let's call the existing one branch_old and new as branch_new.

  2. Reset branch_new to a stable state, when you did not have any problem commit at all. For example, to put it at your local master's level do the following:

    git reset —hard master git push —force origin

  3. cherry-pick the commits from branch_old into branch_new

  4. git push

How to reset db in Django? I get a command 'reset' not found error

With django 1.11, simply delete all migration files from the migrations folder of each application (all files except __init__.py). Then

  1. Manually drop database.
  2. Manually create database.
  3. Run python3 manage.py makemigrations.
  4. Run python3 manage.py migrate.

And voilla, your database has been completely reset.

"Agreeing to the Xcode/iOS license requires admin privileges, please re-run as root via sudo." when using GCC

Follow these steps:

  1. Open Terminal.
  2. Enter this command: sudo xcodebuild --license.
  3. Enter system password.
  4. Agree to the license.

How to open an elevated cmd using command line for Windows?

Simple way I did after trying other answers here

Method 1: WITHOUT a 3rd party program (I used this)

  1. Create a file called sudo.bat (you can replace sudo with any name you want) with following content powershell.exe -Command "Start-Process cmd \"/k cd /d %cd%\" -Verb RunAs"
  2. Move sudo.bat to a folder in your PATH; if you don't know what that means, just move these files to c:\windows\
  3. Now sudo will work in Run dialog (win+r) or in explorer address bar (this is the best part :))

Method 2: WITH a 3rd party program

  1. Download NirCmd and unzip it.
  2. Create a file called sudo.bat (you can replace sudo with any name you want) with following content nircmdc elevate cmd /k "cd /d %cd%"
  3. Move nircmdc.exe and sudo.bat to a folder in your PATH; if you don't know what that means, just move these files to c:\windows\
  4. Now sudo will work in Run dialog (win+r) or in explorer address bar (this is the best part :))

"Templates can be used only with field access, property access, single-dimension array index, or single-parameter custom indexer expressions" error

I had the same problem with something like

@foreach (var item in Model)
{
    @Html.DisplayFor(m => !item.IsIdle, "BoolIcon")
}

I solved this just by doing

@foreach (var item in Model)
{
    var active = !item.IsIdle;
    @Html.DisplayFor(m => active , "BoolIcon")
}

When you know the trick, it's simple.

The difference is that, in the first case, I passed a method as a parameter whereas in the second case, it's an expression.

Comparing HTTP and FTP for transferring files

Here's a performance comparison of the two. HTTP is more responsive for request-response of small files, but FTP may be better for large files if tuned properly. FTP used to be generally considered faster. FTP requires a control channel and state be maintained besides the TCP state but HTTP does not. There are 6 packet transfers before data starts transferring in FTP but only 4 in HTTP.

I think a properly tuned TCP layer would have more effect on speed than the difference between application layer protocols. The Sun Blueprint Understanding Tuning TCP has details.

Heres another good comparison of individual characteristics of each protocol.

Updating a local repository with changes from a GitHub repository

With an already-set origin master, you just have to use the below command -

git pull "https://github.com/yourUserName/yourRepo.git"

sql select with column name like

SELECT * FROM SysColumns WHERE Name like 'a%'

Will get you a list of columns, you will want to filter more to restrict it to your target table

From there you can construct some ad-hoc sql

How do I delete an entity from symfony2

DELETE FROM ... WHERE id=...;

protected function templateRemove($id){
            $em = $this->getDoctrine()->getManager();
            $entity = $em->getRepository('XXXBundle:Templates')->findOneBy(array('id' => $id));

            if ($entity != null){
                $em->remove($entity);
                $em->flush();
            }
        }

How to run a C# console application with the console hidden

If you are using Process Class then you can write

yourprocess.StartInfo.UseShellExecute = false;
yourprocess.StartInfo.CreateNoWindow = true;

before yourprocess.start(); and process will be hidden

Resize UIImage and change the size of UIImageView

Use the category below and then apply border from Quartz into your image:

[yourimage.layer setBorderColor:[[UIColor whiteColor] CGColor]];
[yourimage.layer setBorderWidth:2];

The category: UIImage+AutoScaleResize.h

#import <Foundation/Foundation.h>

@interface UIImage (AutoScaleResize)

- (UIImage *)imageByScalingAndCroppingForSize:(CGSize)targetSize;

@end

UIImage+AutoScaleResize.m

#import "UIImage+AutoScaleResize.h"

@implementation UIImage (AutoScaleResize)

- (UIImage *)imageByScalingAndCroppingForSize:(CGSize)targetSize
{
    UIImage *sourceImage = self;
    UIImage *newImage = nil;
    CGSize imageSize = sourceImage.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;
    CGFloat targetWidth = targetSize.width;
    CGFloat targetHeight = targetSize.height;
    CGFloat scaleFactor = 0.0;
    CGFloat scaledWidth = targetWidth;
    CGFloat scaledHeight = targetHeight;
    CGPoint thumbnailPoint = CGPointMake(0.0,0.0);

    if (CGSizeEqualToSize(imageSize, targetSize) == NO)
    {
        CGFloat widthFactor = targetWidth / width;
        CGFloat heightFactor = targetHeight / height;

        if (widthFactor > heightFactor)
        {
            scaleFactor = widthFactor; // scale to fit height
        }
        else
        {
            scaleFactor = heightFactor; // scale to fit width
        }

        scaledWidth  = width * scaleFactor;
        scaledHeight = height * scaleFactor;

        // center the image
        if (widthFactor > heightFactor)
        {
            thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
        }
        else
        {
            if (widthFactor < heightFactor)
            {
                thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
            }
        }
    }

    UIGraphicsBeginImageContext(targetSize); // this will crop

    CGRect thumbnailRect = CGRectZero;
    thumbnailRect.origin = thumbnailPoint;
    thumbnailRect.size.width  = scaledWidth;
    thumbnailRect.size.height = scaledHeight;

    [sourceImage drawInRect:thumbnailRect];

    newImage = UIGraphicsGetImageFromCurrentImageContext();

    if(newImage == nil)
    {
        NSLog(@"could not scale image");
    }

    //pop the context to get back to the default
    UIGraphicsEndImageContext();

    return newImage;
}

@end

Remove leading and trailing spaces?

You can use the strip() to remove trailing and leading spaces.

>>> s = '   abd cde   '
>>> s.strip()
'abd cde'

Note: the internal spaces are preserved

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

try this (a2 is BLOB col)

PreparedStatement ps1 = conn.prepareStatement("update t1 set a2=? where id=1");
Blob blob = conn.createBlob();
blob.setBytes(1, str.getBytes());
ps1.setBlob(1, blob);
ps1.executeUpdate();

it may work even without BLOB, driver will transform types automatically:

   ps1.setBytes(1, str.getBytes);
   ps1.setString(1, str);

Besides if you work with text CLOB seems to be a more natural col type

How to get current time with jQuery

_x000D_
_x000D_
.clock {_x000D_
width: 260px;_x000D_
margin: 0 auto;_x000D_
padding: 30px;_x000D_
color: #FFF;background:#333;_x000D_
}_x000D_
.clock ul {_x000D_
width: 250px;_x000D_
margin: 0 auto;_x000D_
padding: 0;_x000D_
list-style: none;_x000D_
text-align: center_x000D_
}_x000D_
_x000D_
.clock ul li {_x000D_
display: inline;_x000D_
font-size: 3em;_x000D_
text-align: center;_x000D_
font-family: "Arial", Helvetica, sans-serif;_x000D_
text-shadow: 0 2px 5px #55c6ff, 0 3px 6px #55c6ff, 0 4px 7px #55c6ff_x000D_
}_x000D_
#Date { _x000D_
font-family: 'Arial', Helvetica, sans-serif;_x000D_
font-size: 26px;_x000D_
text-align: center;_x000D_
text-shadow: 0 2px 5px #55c6ff, 0 3px 6px #55c6ff;_x000D_
padding-bottom: 40px;_x000D_
}_x000D_
_x000D_
#point {_x000D_
position: relative;_x000D_
-moz-animation: mymove 1s ease infinite;_x000D_
-webkit-animation: mymove 1s ease infinite;_x000D_
padding-left: 10px;_x000D_
padding-right: 10px_x000D_
}_x000D_
_x000D_
/* Animasi Detik Kedap - Kedip */_x000D_
@-webkit-keyframes mymove _x000D_
{_x000D_
0% {opacity:1.0; text-shadow:0 0 20px #00c6ff;}_x000D_
50% {opacity:0; text-shadow:none; }_x000D_
100% {opacity:1.0; text-shadow:0 0 20px #00c6ff; } _x000D_
}_x000D_
_x000D_
@-moz-keyframes mymove _x000D_
{_x000D_
0% {opacity:1.0; text-shadow:0 0 20px #00c6ff;}_x000D_
50% {opacity:0; text-shadow:none; }_x000D_
100% {opacity:1.0; text-shadow:0 0 20px #00c6ff; } _x000D_
}
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js"></script>_x000D_
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js"></script>_x000D_
<script type="text/javascript">_x000D_
$(document).ready(function() {_x000D_
// Making 2 variable month and day_x000D_
var monthNames = [ "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" ]; _x000D_
var dayNames= ["Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"]_x000D_
_x000D_
// make single object_x000D_
var newDate = new Date();_x000D_
// make current time_x000D_
newDate.setDate(newDate.getDate());_x000D_
// setting date and time_x000D_
$('#Date').html(dayNames[newDate.getDay()] + " " + newDate.getDate() + ' ' + monthNames[newDate.getMonth()] + ' ' + newDate.getFullYear());_x000D_
_x000D_
setInterval( function() {_x000D_
// Create a newDate() object and extract the seconds of the current time on the visitor's_x000D_
var seconds = new Date().getSeconds();_x000D_
// Add a leading zero to seconds value_x000D_
$("#sec").html(( seconds < 10 ? "0" : "" ) + seconds);_x000D_
},1000);_x000D_
_x000D_
setInterval( function() {_x000D_
// Create a newDate() object and extract the minutes of the current time on the visitor's_x000D_
var minutes = new Date().getMinutes();_x000D_
// Add a leading zero to the minutes value_x000D_
$("#min").html(( minutes < 10 ? "0" : "" ) + minutes);_x000D_
},1000);_x000D_
_x000D_
setInterval( function() {_x000D_
// Create a newDate() object and extract the hours of the current time on the visitor's_x000D_
var hours = new Date().getHours();_x000D_
// Add a leading zero to the hours value_x000D_
$("#hours").html(( hours < 10 ? "0" : "" ) + hours);_x000D_
}, 1000); _x000D_
});_x000D_
</script>_x000D_
<div class="clock">_x000D_
<div id="Date"></div>_x000D_
<ul>_x000D_
<li id="hours"></li>_x000D_
<li id="point">:</li>_x000D_
<li id="min"></li>_x000D_
<li id="point">:</li>_x000D_
<li id="sec"></li>_x000D_
</ul>_x000D_
</div>
_x000D_
_x000D_
_x000D_

"Automatic" vs "Automatic (Delayed start)"

In short, services set to Automatic will start during the boot process, while services set to start as Delayed will start shortly after boot.

Starting your service Delayed improves the boot performance of your server and has security benefits which are outlined in the article Adriano linked to in the comments.

Update: "shortly after boot" is actually 2 minutes after the last "automatic" service has started, by default. This can be configured by a registry key, according to Windows Internals and other sources (3,4).

The registry keys of interest (At least in some versions of windows) are:

  • HKLM\SYSTEM\CurrentControlSet\services\<service name>\DelayedAutostart will have the value 1 if delayed, 0 if not.
  • HKLM\SYSTEM\CurrentControlSet\services\AutoStartDelay or HKLM\SYSTEM\CurrentControlSet\Control\AutoStartDelay (on Windows 10): decimal number of seconds to wait, may need to create this one. Applies globally to all Delayed services.

How to remove a package from Laravel using composer?

Simpliest and Easiest way

Syntax:

composer remove <package>

Example:

composer remove laravel/tinker

Store text file content line by line into array

Just use Apache Commons IO

List<String> lines = IOUtils.readLines(new FileInputStream("path/of/text"));

Failed to resolve: com.android.support:appcompat-v7:28.0

Ensure that your buildToolsVersion version tallies with your app compact version.

In order to find both installed compileSdkVersion and buildToolsVersion go to Tools > SDK Manager. This will pull up a window that will allow you to manage your compileSdkVersion and your buildToolsVersion.

To see the exact version breakdowns ensure you have the Show Package Details checkbox checked.

android {
    compileSdkVersion 28
    buildToolsVersion "28.0.3" (HERE)
    defaultConfig {
        applicationId "com.example.truecitizenquiz"
        minSdkVersion 14
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0' (HERE)
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

jQuery UI DatePicker to show year only

Try this piece of code, it worked for me:

$('#year').datepicker({
    format: "yyyy",
    viewMode: "years",
    minViewMode: "years"
});

I hope it will do magic also for you.

Query an object array using linq

Add:

using System.Linq;

to the top of your file.

And then:

Car[] carList = ...
var carMake = 
    from item in carList
    where item.Model == "bmw" 
    select item.Make;

or if you prefer the fluent syntax:

var carMake = carList
    .Where(item => item.Model == "bmw")
    .Select(item => item.Make);

Things to pay attention to:

  • The usage of item.Make in the select clause instead if s.Make as in your code.
  • You have a whitespace between item and .Model in your where clause

Convert integers to strings to create output filenames at run time

I already showed this elsewhere on SO (How to use a variable in the format specifier statement? , not an exact duplicate IMHO), but I think it is worthwhile to place it here. It is possible to use the techniques from other answers for this question to make a simple function

function itoa(i) result(res)
  character(:),allocatable :: res
  integer,intent(in) :: i
  character(range(i)+2) :: tmp
  write(tmp,'(i0)') i
  res = trim(tmp)
end function

which you can use after without worrying about trimming and left-adjusting and without writing to a temporary variable:

OPEN(1, FILE = 'Output'//itoa(i)//'.TXT')

It requires Fortran 2003 because of the allocatable string.

VERR_VMX_MSR_VMXON_DISABLED when starting an image from Oracle virtual box

I believe VirtualBox is throwing this error for a number of reasons. Very annoying that it's one error for so many things but, I guess it's the same requirement it's just that the root cause is different.

Potential gotchas:

  1. You haven't enabled VT-x in VirtualBox and it's required for the VM.
    • To enable: open vbox, click the VM, click Settings..., System->Acceleration->VT-x check box.
  2. You haven't enabled VT-x in BIOS and it's required.
    • Check your motherboard manual but you basically want to enter your BIOS just after the machine turns on (usually DEL key, F2, F12 etc) and find "Advanced" tag, enter "CPU configuration", then enable "Intel Virtualization Technology".
  3. Your processor doesn't support VT-x (eg a Core i3).
    • In this case your BIOS and VirtualBox shouldn't allow you to try and enable VT-x (but if they do, you'll likely get a crash in the VM).
  4. Your trying to install or boot a 64 bit guest OS.
    • I think 64 bit OS requires true CPU pass-through which requires VT-x. (A VM expert can comment on this point).
  5. You are trying to allocate >3GB of RAM to the VM.
    • Similar to the previous point, this requires: (a) a 64 bit host system; and (b) true hardware pass-through ie VT-x.

So for my little mess around machine that I'm resurrecting that has 8GB RAM but only a ye-olde Core i3, I'm having success if I install: 32 bit version of linux, allocating 2.5GB RAM.

Oh, and wherever I say "VT-x" above, that obviously applies equally to AMD's "AMD-V" virtualization tech.

I hope that helps.

Using LINQ to remove elements from a List<T>

I think you could do something like this

    authorsList = (from a in authorsList
                  where !authors.Contains(a)
                  select a).ToList();

Although I think the solutions already given solve the problem in a more readable way.

Trigger a button click with JavaScript on the Enter key in a text box

For those who may like brevity and modern js approach.

input.addEventListener('keydown', (e) => {if (e.keyCode == 13) doSomething()});

where input is a variable containing your input element.

Getter and Setter declaration in .NET

The 1st one is default, when there is nothing special to return or write. 2nd and 3rd are basically the same where 3rd is a bit more expanded version of 2nd

How to check for empty value in Javascript?

First, I would check what i gets initialized to, to see if the elements returned by getElementsByName are what you think they are. Maybe split the problem by trying it with a hard-coded name like timetemp0, without the concatenation. You can also run the code through a browser debugger (FireBug, Chrome Dev Tools, IE Dev Tools).

Also, for your if-condition, this should suffice:

if (!timetemp[0].value) {
    // The value is empty.
}
else {
    // The value is not empty.
}

The empty string in Javascript is a falsey value, so the logical negation of that will get you into the if-block.

Setting the Vim background colors

Try adding

set background=dark

to your .gvimrc too. This work well for me.

Converting BigDecimal to Integer

Following should do the trick:

BigDecimal d = new BigDecimal(10);
int i = d.intValue();

How to POST request using RestSharp

it is better to use json after post your resuest like below

  var clien = new RestClient("https://smple.com/");
  var request = new RestRequest("index", Method.POST);
  request.AddHeader("Sign", signinstance);    
  request.AddJsonBody(JsonConvert.SerializeObject(yourclass));
  var response = client.Execute<YourReturnclassSample>(request);
  if (response.StatusCode == System.Net.HttpStatusCode.Created)
   {
       return Ok(response.Content);
   }

How to apply filters to *ngFor?

A simple solution that works with Angular 6 for filtering a ngFor, it's the following:

_x000D_
_x000D_
<span *ngFor="item of itemsList"  >_x000D_
  <div *ngIf="yourCondition(item)">_x000D_
    _x000D_
    your code_x000D_
    _x000D_
  </div>_x000D_
</span
_x000D_
_x000D_
_x000D_

Spans are useful because does not inherently represent anything.

Logical operators for boolean indexing in Pandas

When you say

(a['x']==1) and (a['y']==10)

You are implicitly asking Python to convert (a['x']==1) and (a['y']==10) to boolean values.

NumPy arrays (of length greater than 1) and Pandas objects such as Series do not have a boolean value -- in other words, they raise

ValueError: The truth value of an array is ambiguous. Use a.empty, a.any() or a.all().

when used as a boolean value. That's because its unclear when it should be True or False. Some users might assume they are True if they have non-zero length, like a Python list. Others might desire for it to be True only if all its elements are True. Others might want it to be True if any of its elements are True.

Because there are so many conflicting expectations, the designers of NumPy and Pandas refuse to guess, and instead raise a ValueError.

Instead, you must be explicit, by calling the empty(), all() or any() method to indicate which behavior you desire.

In this case, however, it looks like you do not want boolean evaluation, you want element-wise logical-and. That is what the & binary operator performs:

(a['x']==1) & (a['y']==10)

returns a boolean array.


By the way, as alexpmil notes, the parentheses are mandatory since & has a higher operator precedence than ==. Without the parentheses, a['x']==1 & a['y']==10 would be evaluated as a['x'] == (1 & a['y']) == 10 which would in turn be equivalent to the chained comparison (a['x'] == (1 & a['y'])) and ((1 & a['y']) == 10). That is an expression of the form Series and Series. The use of and with two Series would again trigger the same ValueError as above. That's why the parentheses are mandatory.

Socket.IO - how do I get a list of connected sockets/clients?

As of version 1.5.1, I'm able to access all the sockets in a namespace with:

var socket_ids = Object.keys(io.of('/namespace').sockets);
socket_ids.forEach(function(socket_id) {
    var socket = io.of('/namespace').sockets[socket_id];
    if (socket.connected) {
        // Do something...
    }
});

For some reason, they're using a plain object instead of an array to store the socket IDs.

How can I call controller/view helper methods from the console in Ruby on Rails?

Inside any controller action or view, you can invoke the console by calling the console method.

For example, in a controller:

class PostsController < ApplicationController
  def new
    console
    @post = Post.new
  end
end

Or in a view:

<% console %>

<h2>New Post</h2>

This will render a console inside your view. You don't need to care about the location of the console call; it won't be rendered on the spot of its invocation but next to your HTML content.

See: http://guides.rubyonrails.org/debugging_rails_applications.html

why are there two different kinds of for loops in java?

The first is the original for loop. You initialize a variable, set a terminating condition, and provide a state incrementing/decrementing counter (There are exceptions, but this is the classic)

For that,

for (int i=0;i<myString.length;i++) { 
  System.out.println(myString[i]); 
}

is correct.

For Java 5 an alternative was proposed. Any thing that implements iterable can be supported. This is particularly nice in Collections. For example you can iterate the list like this

List<String> list = ....load up with stuff

for (String string : list) {
  System.out.println(string);
}

instead of

for (int i=0; i<list.size();i++) {
  System.out.println(list.get(i));
}

So it's just an alternative notation really. Any item that implements Iterable (i.e. can return an iterator) can be written that way.

What's happening behind the scenes is somethig like this: (more efficient, but I'm writing it explicitly)

Iterator<String> it = list.iterator();
while (it.hasNext()) {
  String string=it.next();
  System.out.println(string);
}

In the end it's just syntactic sugar, but rather convenient.

Multiple Order By with LINQ

You can use the ThenBy and ThenByDescending extension methods:

foobarList.OrderBy(x => x.Foo).ThenBy( x => x.Bar)

logout and redirecting session in php

The simplest way to log out and redirect back to the login or index:

<?php
    if (!isset($_SESSION)) { session_start(); }
    $_SESSION = array(); 
    session_destroy(); 
    header("Location: login.php"); // Or wherever you want to redirect
    exit();
?>

Static Final Variable in Java

For the primitive types, the 'final static' will be a proper declaration to declare a constant. A non-static final variable makes sense when it is a constant reference to an object. In this case each instance can contain its own reference, as shown in JLS 4.5.4.

See Pavel's response for the correct answer.

Can I change the Android startActivity() transition animation?

If you always want to the same transition animation for the activity

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    overridePendingTransition(android.R.anim.fade_in, android.R.anim.fade_out);

@Override
protected void onPause() {
    super.onPause();
    if (isFinishing()) {
        overridePendingTransition(android.R.anim.fade_in, android.R.anim.fade_out);
    }
}

how to dynamically add options to an existing select in vanilla javascript

I guess something like this would do the job.

var option = document.createElement("option");
option.text = "Text";
option.value = "myvalue";
var select = document.getElementById("daySelect");
select.appendChild(option);

How do I read an image file using Python?

The word "read" is vague, but here is an example which reads a jpeg file using the Image class, and prints information about it.

from PIL import Image
jpgfile = Image.open("picture.jpg")

print(jpgfile.bits, jpgfile.size, jpgfile.format)

How to get the current date without the time?

Current Time :

DateTime.Now.ToString("HH:mm:ss");

Current Date :

DateTime.Today.ToString("dd-MM-yyyy");

Why do I need to do `--set-upstream` all the time?

I personally use these following alias in bash

in ~/.gitconfig file

[alias]
    pushup = "!git push --set-upstream origin $(git symbolic-ref --short HEAD)"

and in ~/.bashrc or ~/.zshrc file

alias gpo="git pushup"
alias gpof="gpo -f"
alias gf="git fetch"
alias gp="git pull"

How to change the button text of <input type="file" />?

Only CSS & bootstrap class

        <div class="col-md-4 input-group">
            <input class="form-control" type="text"/>
            <div class="input-group-btn">
                <label for="files" class="btn btn-default">browse</label>
                <input id="files" type="file" class="btn btn-default"  style="visibility:hidden;"/>
            </div>
        </div>

How do I UPDATE from a SELECT in SQL Server?

I add this only so you can see a quick way to write it so that you can check what will be updated before doing the update.

UPDATE Table 
SET  Table.col1 = other_table.col1,
     Table.col2 = other_table.col2 
--select Table.col1, other_table.col,Table.col2,other_table.col2, *   
FROM     Table 
INNER JOIN     other_table 
    ON     Table.id = other_table.id 

How to skip the OPTIONS preflight request?

When performing certain types of cross-domain AJAX requests, modern browsers that support CORS will insert an extra "preflight" request to determine whether they have permission to perform the action. From example query:

$http.get( ‘https://example.com/api/v1/users/’ +userId,
  {params:{
           apiKey:’34d1e55e4b02e56a67b0b66’
          }
  } 
);

As a result of this fragment we can see that the address was sent two requests (OPTIONS and GET). The response from the server includes headers confirming the permissibility the query GET. If your server is not configured to process an OPTIONS request properly, client requests will fail. For example:

Access-Control-Allow-Credentials: true
Access-Control-Allow-Headers: accept, origin, x-requested-with, content-type
Access-Control-Allow-Methods: DELETE
Access-Control-Allow-Methods: OPTIONS
Access-Control-Allow-Methods: PUT
Access-Control-Allow-Methods: GET
Access-Control-Allow-Methods: POST
Access-Control-Allow-Orgin: *
Access-Control-Max-Age: 172800
Allow: PUT
Allow: OPTIONS
Allow: POST
Allow: DELETE
Allow: GET

Passing Arrays to Function in C++

The syntaxes

int[]

and

int[X] // Where X is a compile-time positive integer

are exactly the same as

int*

when in a function parameter list (I left out the optional names).

Additionally, an array name decays to a pointer to the first element when passed to a function (and not passed by reference) so both int firstarray[3] and int secondarray[5] decay to int*s.

It also happens that both an array dereference and a pointer dereference with subscript syntax (subscript syntax is x[y]) yield an lvalue to the same element when you use the same index.

These three rules combine to make the code legal and work how you expect; it just passes pointers to the function, along with the length of the arrays which you cannot know after the arrays decay to pointers.

Learning Regular Expressions

The most important part is the concepts. Once you understand how the building blocks work, differences in syntax amount to little more than mild dialects. A layer on top of your regular expression engine's syntax is the syntax of the programming language you're using. Languages such as Perl remove most of this complication, but you'll have to keep in mind other considerations if you're using regular expressions in a C program.

If you think of regular expressions as building blocks that you can mix and match as you please, it helps you learn how to write and debug your own patterns but also how to understand patterns written by others.

Start simple

Conceptually, the simplest regular expressions are literal characters. The pattern N matches the character 'N'.

Regular expressions next to each other match sequences. For example, the pattern Nick matches the sequence 'N' followed by 'i' followed by 'c' followed by 'k'.

If you've ever used grep on Unix—even if only to search for ordinary looking strings—you've already been using regular expressions! (The re in grep refers to regular expressions.)

Order from the menu

Adding just a little complexity, you can match either 'Nick' or 'nick' with the pattern [Nn]ick. The part in square brackets is a character class, which means it matches exactly one of the enclosed characters. You can also use ranges in character classes, so [a-c] matches either 'a' or 'b' or 'c'.

The pattern . is special: rather than matching a literal dot only, it matches any character. It's the same conceptually as the really big character class [-.?+%$A-Za-z0-9...].

Think of character classes as menus: pick just one.

Helpful shortcuts

Using . can save you lots of typing, and there are other shortcuts for common patterns. Say you want to match a digit: one way to write that is [0-9]. Digits are a frequent match target, so you could instead use the shortcut \d. Others are \s (whitespace) and \w (word characters: alphanumerics or underscore).

The uppercased variants are their complements, so \S matches any non-whitespace character, for example.

Once is not enough

From there, you can repeat parts of your pattern with quantifiers. For example, the pattern ab?c matches 'abc' or 'ac' because the ? quantifier makes the subpattern it modifies optional. Other quantifiers are

  • * (zero or more times)
  • + (one or more times)
  • {n} (exactly n times)
  • {n,} (at least n times)
  • {n,m} (at least n times but no more than m times)

Putting some of these blocks together, the pattern [Nn]*ick matches all of

  • ick
  • Nick
  • nick
  • Nnick
  • nNick
  • nnick
  • (and so on)

The first match demonstrates an important lesson: * always succeeds! Any pattern can match zero times.

A few other useful examples:

  • [0-9]+ (and its equivalent \d+) matches any non-negative integer
  • \d{4}-\d{2}-\d{2} matches dates formatted like 2019-01-01

Grouping

A quantifier modifies the pattern to its immediate left. You might expect 0abc+0 to match '0abc0', '0abcabc0', and so forth, but the pattern immediately to the left of the plus quantifier is c. This means 0abc+0 matches '0abc0', '0abcc0', '0abccc0', and so on.

To match one or more sequences of 'abc' with zeros on the ends, use 0(abc)+0. The parentheses denote a subpattern that can be quantified as a unit. It's also common for regular expression engines to save or "capture" the portion of the input text that matches a parenthesized group. Extracting bits this way is much more flexible and less error-prone than counting indices and substr.

Alternation

Earlier, we saw one way to match either 'Nick' or 'nick'. Another is with alternation as in Nick|nick. Remember that alternation includes everything to its left and everything to its right. Use grouping parentheses to limit the scope of |, e.g., (Nick|nick).

For another example, you could equivalently write [a-c] as a|b|c, but this is likely to be suboptimal because many implementations assume alternatives will have lengths greater than 1.

Escaping

Although some characters match themselves, others have special meanings. The pattern \d+ doesn't match backslash followed by lowercase D followed by a plus sign: to get that, we'd use \\d\+. A backslash removes the special meaning from the following character.

Greediness

Regular expression quantifiers are greedy. This means they match as much text as they possibly can while allowing the entire pattern to match successfully.

For example, say the input is

"Hello," she said, "How are you?"

You might expect ".+" to match only 'Hello,' and will then be surprised when you see that it matched from 'Hello' all the way through 'you?'.

To switch from greedy to what you might think of as cautious, add an extra ? to the quantifier. Now you understand how \((.+?)\), the example from your question works. It matches the sequence of a literal left-parenthesis, followed by one or more characters, and terminated by a right-parenthesis.

If your input is '(123) (456)', then the first capture will be '123'. Non-greedy quantifiers want to allow the rest of the pattern to start matching as soon as possible.

(As to your confusion, I don't know of any regular-expression dialect where ((.+?)) would do the same thing. I suspect something got lost in transmission somewhere along the way.)

Anchors

Use the special pattern ^ to match only at the beginning of your input and $ to match only at the end. Making "bookends" with your patterns where you say, "I know what's at the front and back, but give me everything between" is a useful technique.

Say you want to match comments of the form

-- This is a comment --

you'd write ^--\s+(.+)\s+--$.

Build your own

Regular expressions are recursive, so now that you understand these basic rules, you can combine them however you like.

Tools for writing and debugging regexes:

Books

Free resources

Footnote

†: The statement above that . matches any character is a simplification for pedagogical purposes that is not strictly true. Dot matches any character except newline, "\n", but in practice you rarely expect a pattern such as .+ to cross a newline boundary. Perl regexes have a /s switch and Java Pattern.DOTALL, for example, to make . match any character at all. For languages that don't have such a feature, you can use something like [\s\S] to match "any whitespace or any non-whitespace", in other words anything.

Where can I find php.ini?

There are several valid ways already mentioned for locating the php.ini file, but if you came across this page because you want to do something with it in a bash script:

path_php_ini="$(php -i | grep 'Configuration File (php.ini) Path' | grep -oP '(?<=\=\>\s).*')" echo ${path_php_ini}

Git: How to find a deleted file in the project commit history?

Below is a simple command, where a dev or a git user can pass a deleted file name from the repository root directory and get the history:

git log --diff-filter=D --summary | grep filename | awk '{print $4; exit}' | xargs git log --all -- 

If anybody, can improve the command, please do.

How do I find a stored procedure containing <text>?

Stored Procedure for find text in SP.. {Dinesh Baskaran} Trendy Global Systems pvt ltd

  create Procedure [dbo].[TextFinder]
 (@Text varchar(500),@Type varchar(2)=NULL)
AS
BEGIN





SELECT DISTINCT o.name AS ObjectName, 
CASE o.xtype 
WHEN 'C' THEN 'CHECK constraint ' 
WHEN 'D' THEN 'Default or DEFAULT constraint'
WHEN 'F' THEN 'FOREIGN KEY constraint'
WHEN 'FN' THEN 'Scalar function'
WHEN 'IF' THEN 'In-lined table-function'
WHEN 'K' THEN 'PRIMARY KEY or UNIQUE constraint'
WHEN 'L' THEN 'Log'
WHEN 'P' THEN 'Stored procedure'
WHEN 'R' THEN 'Rule'
WHEN 'RF' THEN 'Replication filter stored procedure' 
WHEN 'S' THEN 'System table'  
WHEN 'TF' THEN 'Table function' 
WHEN 'TR' THEN 'Trigger'  
WHEN 'U' THEN 'User table' 
WHEN 'V' THEN 'View' 
WHEN 'X' THEN 'Extended stored procedure' 
ELSE o.xtype 
END AS ObjectType,  

ISNULL( p.Name, '[db]') AS Location

FROM syscomments c

INNER JOIN sysobjects o ON c.id=o.id

LEFT JOIN sysobjects p ON o.Parent_obj=p.id

WHERE c.text LIKE '%' + @Text + '%' and

o.xtype = case when @Type IS NULL then o.xtype  else @Type end 


ORDER BY Location, ObjectName



END

jQuery DataTable overflow and text-wrapping issues

The following CSS declaration works for me:

.td-limit {
    max-width: 70px;
    text-overflow: ellipsis;
    white-space: nowrap;
    overflow: hidden;
}

Swift alert view with OK and Cancel: which button tapped?

Updated for swift 3:

// function defination:

@IBAction func showAlertDialog(_ sender: UIButton) {
        // Declare Alert
        let dialogMessage = UIAlertController(title: "Confirm", message: "Are you sure you want to Logout?", preferredStyle: .alert)

        // Create OK button with action handler
        let ok = UIAlertAction(title: "OK", style: .default, handler: { (action) -> Void in
             print("Ok button click...")
             self.logoutFun()
        })

        // Create Cancel button with action handlder
        let cancel = UIAlertAction(title: "Cancel", style: .cancel) { (action) -> Void in
            print("Cancel button click...")
        }

        //Add OK and Cancel button to dialog message
        dialogMessage.addAction(ok)
        dialogMessage.addAction(cancel)

        // Present dialog message to user
        self.present(dialogMessage, animated: true, completion: nil)
    }

// logoutFun() function definaiton :

func logoutFun()
{
    print("Logout Successfully...!")
}

Apache and Node.js on the Same Server

Running Node and Apache on one server is trivial as they don't conflict. NodeJS is just a way to execute JavaScript server side. The real dilemma comes from accessing both Node and Apache from outside. As I see it you have two choices:

  1. Set up Apache to proxy all matching requests to NodeJS, which will do the file uploading and whatever else in node.

  2. Have Apache and Node on different IP:port combinations (if your server has two IPs, then one can be bound to your node listener, the other to Apache).

I'm also beginning to suspect that this might not be what you are actually looking for. If your end goal is for you to write your application logic in Nodejs and some "file handling" part that you off-load to a contractor, then its really a choice of language, not a web server.

How to install Selenium WebDriver on Mac OS

First up you need to download Selenium jar files from http://www.seleniumhq.org/download/. Then you'd need an IDE, something like IntelliJ or Eclipse. Then you'll have to map your jar files to those IDEs. Then depending on which language/framework you choose, you'll have to download the relevant library files, for example, if you're using JUnit you'll have to download Junit 4.11 jar file. Finally don't forget to download the drivers for Chrome and Safari (firefox driver comes standard with selenium). Once done, you can start coding and testing your code with the browser of your choice.

Python: Find in list

Finding the first occurrence

There's a recipe for that in itertools:

def first_true(iterable, default=False, pred=None):
    """Returns the first true value in the iterable.

    If no true value is found, returns *default*

    If *pred* is not None, returns the first item
    for which pred(item) is true.

    """
    # first_true([a,b,c], x) --> a or b or c or x
    # first_true([a,b], x, f) --> a if f(a) else b if f(b) else x
    return next(filter(pred, iterable), default)

For example, the following code finds the first odd number in a list:

>>> first_true([2,3,4,5], None, lambda x: x%2==1)
3  

Create a one to many relationship using SQL Server

This is a simple example of a classic Order example. Each Customer can have multiple Orders, and each Order can consist of multiple OrderLines.

You create a relation by adding a foreign key column. Each Order record has a CustomerID in it, that points to the ID of the Customer. Similarly, each OrderLine has an OrderID value. This is how the database diagram looks:

enter image description here

In this diagram, there are actual foreign key constraints. They are optional, but they ensure integrity of your data. Also, they make the structure of your database clearer to anyone using it.

I assume you know how to create the tables themselves. Then you just need to define the relationships between them. You can of course define constraints in T-SQL (as posted by several people), but they're also easily added using the designer. Using SQL Management Studio, you can right-click the Order table, click Design (I think it may be called Edit under 2005). Then anywhere in the window that opens right-click and select Relationships.

You will get another dialog, on the right there should be a grid view. One of the first lines reads "Tables and Columns Specification". Click that line, then click again on the little [...] button that appears on the right. You will get this dialog:

Foreign key constraint

The Order table should already be selected on the right. Select the Customer table on the left dropdown. Then in the left grid, select the ID column. In the right grid, select the CustomerID column. Close the dialog, and the next. Press Ctrl+S to save.

Having this constraint will ensure that no Order records can exist without an accompanying Customer record.

To effectively query a database like this, you might want to read up on JOINs.

python: how to send mail with TO, CC and BCC?

Don't add the bcc header.

See this: http://mail.python.org/pipermail/email-sig/2004-September/000151.html

And this: """Notice that the second argument to sendmail(), the recipients, is passed as a list. You can include any number of addresses in the list to have the message delivered to each of them in turn. Since the envelope information is separate from the message headers, you can even BCC someone by including them in the method argument but not in the message header.""" from http://pymotw.com/2/smtplib

toaddr = '[email protected]'
cc = ['[email protected]','[email protected]']
bcc = ['[email protected]']
fromaddr = '[email protected]'
message_subject = "disturbance in sector 7"
message_text = "Three are dead in an attack in the sewers below sector 7."
message = "From: %s\r\n" % fromaddr
    + "To: %s\r\n" % toaddr
    + "CC: %s\r\n" % ",".join(cc)
    # don't add this, otherwise "to and cc" receivers will know who are the bcc receivers
    # + "BCC: %s\r\n" % ",".join(bcc)
    + "Subject: %s\r\n" % message_subject
    + "\r\n" 
    + message_text
toaddrs = [toaddr] + cc + bcc
server = smtplib.SMTP('smtp.sunnydale.k12.ca.us')
server.set_debuglevel(1)
server.sendmail(fromaddr, toaddrs, message)
server.quit()

Spring cron expression for every after 30 minutes

in web app java spring what worked for me

cron="0 0/30 * * * ?"

This will trigger on for example 10:00AM then 10:30AM etc...

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:beans="http://www.springframework.org/schema/beans"
       xmlns:task="http://www.springframework.org/schema/task"
       xsi:schemaLocation="
    http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/task 
    http://www.springframework.org/schema/task/spring-task.xsd">

    <beans profile="cron">
        <bean id="executorService" class="java.util.concurrent.Executors" factory-method="newFixedThreadPool">
            <beans:constructor-arg value="5" />
        </bean>

        <task:executor id="threadPoolTaskExecutor" pool-size="5" />
        <task:annotation-driven executor="executorService" />

        <beans:bean id="expireCronJob" class="com.cron.ExpireCron"/>

        <task:scheduler id="serverScheduler" pool-size="5"/>
        <task:scheduled-tasks scheduler="serverScheduler">
            <task:scheduled ref="expireCronJob" method="runTask" cron="0 0/30 * * * ?"/> <!-- every thirty minute -->
        </task:scheduled-tasks>

    </beans>

</beans>

I dont know why but this is working on my local develop and production, but other changes if i made i have to be careful because it may work local and on develop but not on production

How to go back last page

In the final version of Angular 2.x / 4.x - here's the docs https://angular.io/api/common/Location

/* typescript */

import { Location } from '@angular/common';
// import stuff here

@Component({
// declare component here
})
export class MyComponent {

  // inject location into component constructor
  constructor(private location: Location) { }

  cancel() {
    this.location.back(); // <-- go back to previous location on cancel
  }
}

Login to website, via C#

Matthew Brindley, your code worked very good for some website I needed (with login), but I needed to change to HttpWebRequest and HttpWebResponse otherwise I get a 404 Bad Request from the remote server. Also I would like to share my workaround using your code, and is that I tried it to login to a website based on moodle, but it didn't work at your step "GETting the page behind the login form" because when successfully POSTing the login, the Header 'Set-Cookie' didn't return anything despite other websites does.

So I think this where we need to store cookies for next Requests, so I added this.


To the "POSTing to the login form" code block :

var cookies = new CookieContainer();
HttpWebRequest req = (HttpWebRequest)WebRequest.Create(formUrl);
req.CookieContainer = cookies;


And To the "GETting the page behind the login form" :

HttpWebRequest getRequest = (HttpWebRequest)WebRequest.Create(getUrl);
getRequest.CookieContainer = new CookieContainer();
getRequest.CookieContainer.Add(resp.Cookies);
getRequest.Headers.Add("Cookie", cookieHeader);


Doing this, lets me Log me in and get the source code of the "page behind login" (website based moodle) I know this is a vague use of the CookieContainer and HTTPCookies because we may ask first is there a previously set of cookies saved before sending the request to the server. This works without problem anyway, but here's a good info to read about WebRequest and WebResponse with sample projects and tutorial:
Retrieving HTTP content in .NET
How to use HttpWebRequest and HttpWebResponse in .NET

CSS selector for "foo that contains bar"?

Only thing that comes even close is the :contains pseudo class in CSS3, but that only selects textual content, not tags or elements, so you're out of luck.

A simpler way to select a parent with specific children in jQuery can be written as (with :has()):

$('#parent:has(#child)');

Creating Roles in Asp.net Identity MVC 5

If you are using the default template that is created when you select a new ASP.net Web application and selected Individual User accounts as Authentication and trying to create users with Roles so here is the solution. In the Account Controller's Register method which is called using [HttpPost], add the following lines in if condition.

using Microsoft.AspNet.Identity.EntityFramework;

var user = new ApplicationUser { UserName = model.Email, Email = model.Email };

var result = await UserManager.CreateAsync(user, model.Password);

if (result.Succeeded)
{
  var roleStore = new RoleStore<IdentityRole>(new ApplicationDbContext());
  var roleManager = new RoleManager<IdentityRole>(roleStore);
  if(!await roleManager.RoleExistsAsync("YourRoleName"))
     await roleManager.CreateAsync(new IdentityRole("YourRoleName"));

  await UserManager.AddToRoleAsync(user.Id, "YourRoleName");
  await SignInManager.SignInAsync(user, isPersistent:false, rememberBrowser:false);
  return RedirectToAction("Index", "Home");
}

This will create first create a role in your database and then add the newly created user to this role.

Last executed queries for a specific database

This works for me to find queries on any database in the instance. I'm sysadmin on the instance (check your privileges):

SELECT deqs.last_execution_time AS [Time], dest.text AS [Query], dest.*
FROM sys.dm_exec_query_stats AS deqs
CROSS APPLY sys.dm_exec_sql_text(deqs.sql_handle) AS dest
WHERE dest.dbid = DB_ID('msdb')
ORDER BY deqs.last_execution_time DESC

This is the same answer that Aaron Bertrand provided but it wasn't placed in an answer.

How to load all the images from one of my folder into my web page, using Jquery/Javascript

If interested in doing this without jQuery - here's a pure JS variant (from here) of the answer currently most upvoted:

var xhr = new XMLHttpRequest();
xhr.open("GET", "/img", true);
xhr.responseType = 'document';
xhr.onload = () => {
  if (xhr.status === 200) {
    var elements = xhr.response.getElementsByTagName("a");
    for (x of elements) {
      if ( x.href.match(/\.(jpe?g|png|gif)$/) ) { 
          let img = document.createElement("img");
          img.src = x.href;
          document.body.appendChild(img);
      } 
    };
  } 
  else {
    alert('Request failed. Returned status of ' + xhr.status);
  }
}
xhr.send()

TypeError: unhashable type: 'dict', when dict used as a key for another dict

From the error, I infer that referenceElement is a dictionary (see repro below). A dictionary cannot be hashed and therefore cannot be used as a key to another dictionary (or itself for that matter!).

>>> d1, d2 = {}, {}
>>> d1[d2] = 1
Traceback (most recent call last):
  File "<input>", line 1, in <module>
TypeError: unhashable type: 'dict'

You probably meant either for element in referenceElement.keys() or for element in json['referenceElement'].keys(). With more context on what types json and referenceElement are and what they contain, we will be able to better help you if neither solution works.

Converting a UNIX Timestamp to Formatted Date String

Assuming you are using PHP5.3 then the modern way of handling dates is via the native DateTime class. To get the current time you can just call

$currentTime = new DateTime();

To create a DateTime object from a specific timestamp (i.e. not now)

$currentTime = DateTime::createFromFormat( 'U', $timestamp );

To get a formatted string you can then call

$formattedString = $currentTime->format( 'c' );

See the manual page here

Cannot drop database because it is currently in use

Just wanted to give a vb.net (as with c language if want to convert..) I was having similar problem for uninstal of one of my programs, dropping the DB was bit tricky, yes could get users to go into server drop it using Express, but thats not clean, after few looks around got a perfect little bit of code together...

    Sub DropMyDatabase()
    Dim Your_DB_To_Drop_Name As String = "YourDB"
    Dim Your_Connection_String_Here As String = "SERVER=MyServer;Integrated Security=True"
    Dim Conn As SqlConnection = New SqlConnection(Your_Connection_String_Here)

    Dim AlterStr As String = "ALTER DATABASE " & Your_DB_To_Drop_Name & " SET OFFLINE WITH ROLLBACK IMMEDIATE"
    Dim AlterCmd = New SqlCommand(AlterStr, Conn)

    Dim DropStr As String = "DROP DATABASE " & Your_DB_To_Drop_Name
    Dim DropCmd = New SqlCommand(DropStr, Conn)

    Try
        Conn.Open()
        AlterCmd.ExecuteNonQuery()
        DropCmd.ExecuteNonQuery()
        Conn.Close()

    Catch ex As Exception
        If (Conn.State = ConnectionState.Open) Then
            Conn.Close()
        End If
        MsgBox("Failed... Sorry!" & vbCrLf & vbCrLf & ex.Message)
    End Try
End Sub

Hope this helps anyone looking xChickenx

UPDATE Using this converter here is the C# version :

public void DropMyDatabase()
    {
        var Your_DB_To_Drop_Name = "YourDB";
        var Your_Connection_String_Here = "SERVER=MyServer;Integrated Security=True";
        var Conn = new SqlConnection(Your_Connection_String_Here);

        var AlterStr = "ALTER DATABASE " + Your_DB_To_Drop_Name + " SET OFFLINE WITH ROLLBACK IMMEDIATE";
        var AlterCmd = new SqlCommand(AlterStr, Conn);

        var DropStr = "DROP DATABASE " + Your_DB_To_Drop_Name;
        var DropCmd = new SqlCommand(DropStr, Conn);

        try
        {
            Conn.Open();
            AlterCmd.ExecuteNonQuery();
            DropCmd.ExecuteNonQuery();
            Conn.Close();

        }
        catch(Exception ex)
        {
            if((Conn.State == ConnectionState.Open))
            {
                Conn.Close();
            }
            Trace.WriteLine("Failed... Sorry!" + Environment.NewLine + ex.Message);
        }
    }

Getting the current date in SQL Server?

As you are using SQL Server 2008, go with Martin's answer.

If you find yourself needing to do it in SQL Server 2005 where you don't have access to the Date column type, I'd use:

SELECT DATEADD(DAY, DATEDIFF(DAY, 0, GETDATE()), 0)

SQLFiddle

How to use Macro argument as string literal?

#define NAME(x) printf("Hello " #x);
main(){
    NAME(Ian)
}
//will print: Hello Ian

What is "pass-through authentication" in IIS 7?

Normally, IIS would use the process identity (the user account it is running the worker process as) to access protected resources like file system or network.

With passthrough authentication, IIS will attempt to use the actual identity of the user when accessing protected resources.

If the user is not authenticated, IIS will use the application pool identity instead. If pool identity is set to NetworkService or LocalSystem, the actual Windows account used is the computer account.

The IIS warning you see is not an error, it's just a warning. The actual check will be performed at execution time, and if it fails, it'll show up in the log.

How to change the default GCC compiler in Ubuntu?

I found this problem while trying to install a new clang compiler. Turns out that both the Debian and the LLVM maintainers agree that the alternatives system should be used for alternatives, NOT for versioning.

The solution they propose is something like this:
PATH=/usr/lib/llvm-3.7/bin:$PATH
where /usr/lib/llvm-3.7/bin is a directory that got created by the llvm-3.7 package, and which contains all the tools with their non-suffixed names. With that, llvm-config (version 3.7) appears with its plain name in your PATH. No need to muck around with symlinks, nor to call the llvm-config-3.7 that got installed in /usr/bin.

Also, check for a package named llvm-defaults (or gcc-defaults), which might offer other way to do this (I didn't use it).

Questions every good Java/Java EE Developer should be able to answer?

Describe the differences between the "four" (not three ;)) types of inner class..

How to press/click the button using Selenium if the button does not have the Id?

You don't need to use only identifier as elements locators. You can use a few ways to find an element. Read this article and choose the best for you.

Sequence contains no elements?

Well, what is ID here? In particular, is it a local variable? There are some scope / capture issues, which mean that it may be desirable to use a second variable copy, just for the query:

var id = ID;
BlogPost post = (from p in dc.BlogPosts
                 where p.BlogPostID == id
                 select p).Single();

Also; if this is LINQ-to-SQL, then in the current version you get a slightly better behaviour if you use the form:

var id = ID;
BlogPost post = dc.BlogPosts.Single(p => p.BlogPostID == id);

Add a new line to a text file in MS-DOS

  • I always use copy con to write text, It so easy to write a long text
  • Example:

    C:\COPY CON [drive:][path][File name]

    .... Content

    F6

    1 file(s) is copied

MySQL: ERROR 1227 (42000): Access denied - Cannot CREATE USER

First thing to do is run this:

SHOW GRANTS;

You will quickly see you were assigned the anonymous user to authenticate into mysql.

Instead of logging into mysql with

mysql

login like this:

mysql -uroot

By default, root@localhost has all rights and no password.

If you cannot login as root without a password, do the following:

Step 01) Add the two options in the mysqld section of my.ini:

[mysqld]
skip-grant-tables
skip-networking

Step 02) Restart mysql

net stop mysql
<wait 10 seconds>
net start mysql

Step 03) Connect to mysql

mysql

Step 04) Create a password from root@localhost

UPDATE mysql.user SET password=password('whateverpasswordyoulike')
WHERE user='root' AND host='localhost';
exit

Step 05) Restart mysql

net stop mysql
<wait 10 seconds>
net start mysql

Step 06) Login as root with password

mysql -u root -p

You should be good from there.

CAVEAT: Please remove anonymous users !!!

How to create byte array from HttpPostedFile

in your question, both buffer and byteArray seem to be byte[]. So:

ImageElement image = ImageElement.FromBinary(buffer);

How to get thread id of a pthread in linux c program?

pid_t tid = syscall(SYS_gettid);

Linux provides such system call to allow you get id of a thread.

How to get the scroll bar with CSS overflow on iOS

Edit following the comment left, kindly, by kritzikratzi:

[Starting] with ios 5beta a new property -webkit-overflow-scrolling: touch can be added which should result in the expected behaviour.

Some, but very little, further reading:


Original answer, left for posterity.

Unfortunately neither overflow: auto, or scroll, produces scrollbars on the iOS devices, apparently due to the screen-width that would be taken up such useful mechanisms.

Instead, as you've found, users are required to perform the two-finger swipe in order to scroll the overflow-ed content. The only reference, since I'm unable to find the manual for the phone itself, I could find is here: tuaw.com: iPhone 101: Two-fingered scrolling.

The only work-around I can think of for this, is if you could possibly use some JavaScript, and maybe jQTouch, to create your own scroll-bars for overflow elements. Alternatively you could use @media queries to remove the overflow and show the content in full, as an iPhone user this gets my vote, if only for the sheer simplicity. For example:

<link rel="stylesheet" href="handheld.css" media="only screen and (max-device width:480px)" />

The preceding code comes from A List Apart, from the same article linked-to above (I'm not sure why they left of the type="text/css", but I assume there are reasons.

"git checkout <commit id>" is changing branch to "no branch"

This worked best for me when I wanted to check out the code, given the commit ID <commit_id_SHA1>

git fetch origin <commit_id_SHA1>
git checkout -b new_branch FETCH_HEAD

python capitalize first letter only

def solve(s):

names = list(s.split(" "))
return " ".join([i.capitalize() for i in names])

Takes a input like your name: john doe

Returns the first letter capitalized.(if first character is a number, then no capitalization occurs)

works for any name length

How to set Apache Spark Executor memory

Apparently, the question never says to run on local mode not on yarn. Somehow I couldnt get spark-default.conf change to work. Instead I tried this and it worked for me

bin/spark-shell --master yarn --num-executors 6  --driver-memory 5g --executor-memory 7g

( couldnt bump executor-memory to 8g there is some restriction from yarn configuration.)

How can I create an MSI setup?

You can use Visual Studio - that's paid.

You can use https://www.advancedinstaller.com/ - that has a free edition.

You can use http://nsis.sourceforge.net/Main_Page - for example Winamp uses this installer - and is very configurable and is Open Source.

How to open the terminal in Atom?

  1. Open your Atom IDE
  2. press ctrl+shift+P and search for "platformio-ide-terminal" package
  3. press install
  4. once installed press ctrl+~ (tilde above tab key in a standard keyboard)
  5. terminal opens enjoy!!!

How to fix "Only one expression can be specified in the select list when the subquery is not introduced with EXISTS" error?

Try this:

 Select 
    Id, 
    Salt, 
    Password, 
    BannedEndDate, 
    (Select Count(*) 
        From LoginFails 
        Where username = '" + LoginModel.Username + "' And IP = '" + Request.ServerVariables["REMOTE_ADDR"] + "')
 From Users 
 Where username = '" + LoginModel.Username + "'

And I recommend you strongly to use parameters in your query to avoid security risks with sql injection attacks!

Hope that helps!

ImportError: No module named xlsxwriter

I am not sure what caused this but it went all well once I changed the path name from Lib into lib and I was finally able to make it work.

What is the meaning of @_ in Perl?

All Perl's "special variables" are listed in the perlvar documentation page.

how to customise input field width in bootstrap 3

i solved with a max-width in my main css-file.

/* Set width on the form input elements since they're 100% wide by default */
input,
select,
textarea {
    max-width: 280px;
}

It's a simple solution with little "code"

How to launch another aspx web page upon button click?

This button post to the current page while at the same time opens OtherPage.aspx in a new browser window. I think this is what you mean with ...the original page and the newly launched page should both be launched.

<asp:Button ID="myBtn" runat="server" Text="Click me" 
     onclick="myBtn_Click" OnClientClick="window.open('OtherPage.aspx', 'OtherPage');" />

Anyway to prevent the Blue highlighting of elements in Chrome when clicking quickly?

To remove the blue overlay on mobiles, you can use one of the following:

-webkit-tap-highlight-color: transparent; /* transparent with keyword */
-webkit-tap-highlight-color: rgba(0,0,0,0); /* transparent with rgba */
-webkit-tap-highlight-color: hsla(0,0,0,0); /* transparent with hsla */
-webkit-tap-highlight-color: #00000000; /* transparent with hex with alpha */
-webkit-tap-highlight-color: #0000; /* transparent with short hex with alpha */

However, unlike other properties, you can't use

-webkit-tap-highlight-color: none; /* none keyword */

In DevTools, this will show up as an 'invalid property value' or something.


To remove the blue/black/orange outline when focused, use this:

:focus {
    outline: none; /* no outline - for most browsers */
    box-shadow: none; /* no box shadow - for some browsers or if you are using Bootstrap */
}

The reason why I removed the box-shadow is because Bootsrap (and some browsers) sometimes add it to focused elements, so you can remove it using this.

But if anyone is navigating with a keyboard, they will get very confused indeed, because they rely on this outline to navigate. So you can replace it instead

:focus {
    outline: 100px dotted #f0f; /* 100px dotted pink outline */
}

You can target taps on mobile using :hover or :active, so you could use those to help, possibly. Or it could get confusing.


Full code:

element {
    -webkit-tap-highlight-color: transparent; /* remove tap highlight */
}
element:focus {
    outline: none; /* remove outline */
    box-shadow: none; /* remove box shadow */
}

Other information:

  • If you would like to customise the -webkit-tap-highlight-color then you should set it to a semi-transparent color so the element underneath doesn't get hidden when tapped
  • Please don't remove the outline from focused elements, or add some more styles for them.
  • -webkit-tap-highlight-color has not got great browser support and is not standard. You can still use it, but watch out!

Static array vs. dynamic array in C++

static is a keyword in C and C++, so rather than a general descriptive term, static has very specific meaning when applied to a variable or array. To compound the confusion, it has three distinct meanings within separate contexts. Because of this, a static array may be either fixed or dynamic.

Let me explain:

The first is C++ specific:

  • A static class member is a value that is not instantiated with the constructor or deleted with the destructor. This means the member has to be initialized and maintained some other way. static member may be pointers initialized to null and then allocated the first time a constructor is called. (Yes, that would be static and dynamic)

Two are inherited from C:

  • within a function, a static variable is one whose memory location is preserved between function calls. It is static in that it is initialized only once and retains its value between function calls (use of statics makes a function non-reentrant, i.e. not threadsafe)

  • static variables declared outside of functions are global variables that can only be accessed from within the same module (source code file with any other #include's)

The question (I think) you meant to ask is what the difference between dynamic arrays and fixed or compile-time arrays. That is an easier question, compile-time arrays are determined in advance (when the program is compiled) and are part of a functions stack frame. They are allocated before the main function runs. dynamic arrays are allocated at runtime with the "new" keyword (or the malloc family from C) and their size is not known in advance. dynamic allocations are not automatically cleaned up until the program stops running.

Transaction marked as rollback only: How do I find the cause

disable the transactionmanager in your Bean.xml

<tx:annotation-driven proxy-target-class="true" transaction-manager="transactionManager"/>
    <bean id="transactionManager"
        class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"></property>
    </bean>

comment out these lines, and you'll see the exception causing the rollback ;)

How to split an integer into an array of digits?

[int(i) for i in str(number)]

or, if do not want to use a list comprehension or you want to use a base different from 10

from __future__ import division # for compatibility of // between Python 2 and 3
def digits(number, base=10):
    assert number >= 0
    if number == 0:
        return [0]
    l = []
    while number > 0:
        l.append(number % base)
        number = number // base
    return l

ReferenceError: fetch is not defined

You can use cross-fetch from @lquixada

Platform agnostic: browsers, node or react native

Install

npm install --save cross-fetch

Usage

With promises:

import fetch from 'cross-fetch';
// Or just: import 'cross-fetch/polyfill';

fetch('//api.github.com/users/lquixada')
  .then(res => {
    if (res.status >= 400) {
      throw new Error("Bad response from server");
    }
    return res.json();
  })
  .then(user => {
    console.log(user);
  })
  .catch(err => {
    console.error(err);
  });

With async/await:

import fetch from 'cross-fetch';
// Or just: import 'cross-fetch/polyfill';

(async () => {
  try {
    const res = await fetch('//api.github.com/users/lquixada');

    if (res.status >= 400) {
      throw new Error("Bad response from server");
    }

    const user = await res.json();

    console.log(user);
  } catch (err) {
    console.error(err);
  }
})();

DateTime.TryParse issue with dates of yyyy-dd-MM format

This should work based on your example "2011-29-01 12:00 am"

DateTime dt;
DateTime.TryParseExact(dateTime, 
                       "yyyy-dd-MM hh:mm tt", 
                       CultureInfo.InvariantCulture, 
                       DateTimeStyles.None, 
                       out dt);

what is the use of fflush(stdin) in c programming

it clears stdin buffer before reading. From the man page:

For output streams, fflush() forces a write of all user-space buffered data for the given output or update stream via the stream's underlying write function. For input streams, fflush() discards any buffered data that has been fetched from the underlying file, but has not been consumed by the application.

Note: This is Linux-specific, using fflush() on input streams is undefined by the standard, however, most implementations behave the same as in Linux.

SQLite Query in Android to count rows

If you are using ContentProvider then you can use:

Cursor cursor = getContentResolver().query(CONTENT_URI, new String[] {"count(*)"},
            uname=" + loginname + " and pwd=" + loginpass, null, null);
    cursor.moveToFirst();
    int count = cursor.getInt(0);

bootstrap 4 row height

Use the sizing utility classes...

  • h-50 = height 50%
  • h-100 = height 100%

http://www.codeply.com/go/Y3nG0io2uE

 <div class="container">
        <div class="row">
            <div class="col-md-8 col-lg-6 B">
                <div class="card card-inverse card-primary">
                    <img src="http://lorempicsum.com/rio/800/500/4" class="img-fluid" alt="Responsive image">
                </div>
            </div>
            <div class="col-md-4 col-lg-3 G">
                <div class="row h-100">
                    <div class="col-md-6 col-lg-6 B h-50 pb-3">
                        <div class="card card-inverse card-success h-100">

                        </div>
                    </div>
                    <div class="col-md-6 col-lg-6 B h-50 pb-3">
                        <div class="card card-inverse bg-success h-100">

                        </div>
                    </div>
                    <div class="col-md-12 h-50">
                        <div class="card card-inverse bg-danger h-100">

                        </div>
                    </div>
                </div>
            </div>
        </div>
    </div>

Or, for an unknown number of child columns, use flexbox and the cols will fill height. See the d-flex flex-column on the row, and h-100 on the child cols.

<div class="container">
    <div class="row">
        <div class="col-md-8 col-lg-6 B">
            <div class="card card-inverse card-primary">
                <img src="http://lorempicsum.com/rio/800/500/4" class="img-fluid" alt="Responsive image">
            </div>
        </div>
        <div class="col-md-4 col-lg-3 G ">
            <div class="row d-flex flex-column h-100">
                <div class="col-md-6 col-lg-6 B h-100">
                    <div class="card bg-success h-100">

                    </div>
                </div>
                <div class="col-md-6 col-lg-6 B h-100">
                    <div class="card bg-success h-100">

                    </div>
                </div>
                <div class="col-md-12 h-100">
                    <div class="card bg-danger h-100">

                    </div>
                </div>
            </div>
        </div>
    </div>
</div>

https://www.codeply.com/go/tgzFAH8vaW

Loading resources using getClass().getResource()

getClass().getResource(path) loads resources from the classpath, not from a filesystem path.

Java associative-array

There is no such thing as associative array in Java. Its closest relative is a Map, which is strongly typed, however has less elegant syntax/API.

This is the closest you can get based on your example:

Map<Integer, Map<String, String>> arr = 
    org.apache.commons.collections.map.LazyMap.decorate(
         new HashMap(), new InstantiateFactory(HashMap.class));

//$arr[0]['name'] = 'demo';
arr.get(0).put("name", "demo");

System.out.println(arr.get(0).get("name"));
System.out.println(arr.get(1).get("name"));    //yields null

How to get the position of a character in Python?

What happens when the string contains a duplicate character? from my experience with index() I saw that for duplicate you get back the same index.

For example:

s = 'abccde'
for c in s:
    print('%s, %d' % (c, s.index(c)))

would return:

a, 0
b, 1
c, 2
c, 2
d, 4

In that case you can do something like that:

for i, character in enumerate(my_string):
   # i is the position of the character in the string

Add legend to ggplot2 line plot

I really like the solution proposed by @Brian Diggs. However, in my case, I create the line plots in a loop rather than giving them explicitly because I do not know apriori how many plots I will have. When I tried to adapt the @Brian's code I faced some problems with handling the colors correctly. Turned out I needed to modify the aesthetic functions. In case someone has the same problem, here is the code that worked for me.

I used the same data frame as @Brian:

data <- structure(list(month = structure(c(1317452400, 1317538800, 1317625200, 1317711600, 
                                       1317798000, 1317884400, 1317970800, 1318057200, 
                                       1318143600, 1318230000, 1318316400, 1318402800, 
                                       1318489200, 1318575600, 1318662000, 1318748400, 
                                       1318834800, 1318921200, 1319007600, 1319094000), 
                                     class = c("POSIXct", "POSIXt"), tzone = ""),
                   TempMax = c(26.58, 27.78, 27.9, 27.44, 30.9, 30.44, 27.57, 25.71, 
                               25.98, 26.84, 33.58, 30.7, 31.3, 27.18, 26.58, 26.18, 
                               25.19, 24.19, 27.65, 23.92), 
                   TempMed = c(22.88, 22.87, 22.41, 21.63, 22.43, 22.29, 21.89, 20.52,
                                 19.71, 20.73, 23.51, 23.13, 22.95, 21.95, 21.91, 20.72, 
                                 20.45, 19.42, 19.97, 19.61), 
                   TempMin = c(19.34, 19.14, 18.34, 17.49, 16.75, 16.75, 16.88, 16.82, 
                               14.82, 16.01, 16.88, 17.55, 16.75, 17.22, 19.01, 16.95, 
                               17.55, 15.21, 14.22, 16.42)), 
              .Names = c("month", "TempMax", "TempMed", "TempMin"), 
              row.names = c(NA, 20L), class = "data.frame")  

In my case, I generate my.cols and my.names dynamically, but I don't want to make things unnecessarily complicated so I give them explicitly here. These three lines make the ordering of the legend and assigning colors easier.

my.cols <- heat.colors(3, alpha=1)
my.names <- c("TempMin", "TempMed", "TempMax")
names(my.cols) <- my.names

And here is the plot:

p <-  ggplot(data, aes(x = month))

for (i in 1:3){
  p <- p + geom_line(aes_(y = as.name(names(data[i+1])), colour = 
colnames(data[i+1])))#as.character(my.names[i])))
}
p + scale_colour_manual("", 
                        breaks = as.character(my.names),
                        values = my.cols)
p

enter image description here

How to negate a method reference predicate

Building on other's answers and personal experience:

Predicate<String> blank = String::isEmpty;
content.stream()
       .filter(blank.negate())

C/C++ switch case with string

If you are after performance and don't want to go through all the if clauses each time if there are many or the need to hash the values, you could send some extra information to the function with the help of enum or just add an enum type to your structure.

I can't access http://localhost/phpmyadmin/

Based on your output, one of your plugins is messing up with the phpmyadmin. Try disabling all plugins to see if that works.

If it does, enable them one by one and check again, to find the problematic one.

How can I get dictionary key as variable directly in Python (not by searching from value)?

easily change the position of your keys and values,then use values to get key, in dictionary keys can have same value but they(keys) should be different. for instance if you have a list and the first value of it is a key for your problem and other values are the specs of the first value:

list1=["Name",'ID=13736','Phone:1313','Dep:pyhton']

you can save and use the data easily in Dictionary by this loop:

data_dict={}
for i in range(1, len(list1)):
     data_dict[list1[i]]=list1[0]
print(data_dict)
{'ID=13736': 'Name', 'Phone:1313': 'Name', 'Dep:pyhton': 'Name'}

then you can find the key(name) base on any input value.

No == operator found while comparing structs in C++

Comparison doesn't work on structs in C or C++. Compare by fields instead.

Add centered text to the middle of a <hr/>-like line

Just Use

    hr
    {
        padding: 0;
        border: none;
        border-top: 1px solid #CCC;
        color: #333;
        text-align: center;
        font-size: 12px;
        vertical-align:middle;
    }
    hr:after
    {
        content: "Or";
        display: inline-block;
        position: relative;
        top: -0.7em;
        font-size: 1.2em;
        padding: 0 0.25em;
        background: white;
    }

What svn command would list all the files modified on a branch?

-u option will display including object files if they are added during compilation.

So, to overcome that additionally you may use like this.

svn status -u | grep -v '\?' 

How to "comment-out" (add comment) in a batch/cmd?

Putting comments on the same line with commands: use & :: comment

color C          & :: set red font color
echo IMPORTANT INFORMATION
color            & :: reset the color to default

Explanation:

& separates two commands, so in this case color C is the first command and :: set red font color is the second one.


Important:

This statement with comment looks intuitively correct:

goto error1         :: handling the error

but it is not a valid use of the comment. It works only because goto ignores all arguments past the first one. The proof is easy, this goto will not fail either:

goto error1 handling the error

But similar attempt

color 17            :: grey on blue

fails executing the command due to 4 arguments unknown to the color command: ::, grey, on, blue.

It will only work as:

color 17     &      :: grey on blue

So the ampersand is inevitable.

bootstrap datepicker change date event doesnt fire up when manually editing dates or clearing date

Try with below code sample.it is working for me

var date_input_field = $('input[name="date"]');
    date_input_field .datepicker({
        dateFormat: '/dd/mm/yyyy',
        container: container,
        todayHighlight: true,
        autoclose: true,
    }).on('change', function(selected){
        alert("startDate..."+selected.timeStamp);
    });

How to get the html of a div on another page with jQuery ajax?

Unfortunately an ajax request gets the entire file, but you can filter the content once it's retrieved:

$.ajax({
   url:href,
   type:'GET',
   success: function(data) {
       var content = $('<div>').append(data).find('#content');
       $('#content').html( content );
   }
});

Note the use of a dummy element as find() only works with descendants, and won't find root elements.

or let jQuery filter it for you:

$('#content').load(href + ' #IDofDivToFind');

I'm assuming this isn't a cross domain request, as that won't work, only pages on the same domain.

How to download a file via FTP with Python ftplib

This is a Python code that is working fine for me. Comments are in Spanish but the app is easy to understand

# coding=utf-8

from ftplib import FTP                                                                      # Importamos la libreria ftplib desde FTP

import sys

def imprimirMensaje():                                                                      # Definimos la funcion para Imprimir el mensaje de bienvenida
    print "------------------------------------------------------"
    print "--               COMMAND LINE EXAMPLE               --"
    print "------------------------------------------------------"
    print ""
    print ">>>             Cliente FTP  en Python                "
    print ""
    print ">>> python <appname>.py <host> <port> <user> <pass>   "
    print "------------------------------------------------------"

def f(s):                                                                                   # Funcion para imprimir por pantalla los datos 
    print s

def download(j):                                                                            # Funcion para descargarnos el fichero que indiquemos según numero    
    print "Descargando=>",files[j]      
    fhandle = open(files[j], 'wb')
    ftp.retrbinary('RETR ' + files[j], fhandle.write)                                       # Imprimimos por pantalla lo que estamos descargando        #fhandle.close()
    fhandle.close()                                                     

ip          = sys.argv[1]                                                                   # Recogemos la IP       desde la linea de comandos sys.argv[1] 
puerto      = sys.argv[2]                                                                   # Recogemos el PUERTO   desde la linea de comandos sys.argv[2]
usuario     = sys.argv[3]                                                                   # Recogemos el USUARIO  desde la linea de comandos sys.argv[3]
password    = sys.argv[4]                                                                   # Recogemos el PASSWORD desde la linea de comandos sys.argv[4]


ftp = FTP(ip)                                                                               # Creamos un objeto realizando una instancia de FTP pasandole la IP
ftp.login(usuario,password)                                                                 # Asignamos al objeto ftp el usuario y la contraseña

files = ftp.nlst()                                                                          # Ponemos en una lista los directorios obtenidos del FTP

for i,v in enumerate(files,1):                                                              # Imprimimos por pantalla el listado de directorios enumerados
    print i,"->",v

print ""
i = int(raw_input("Pon un Nº para descargar el archivo or pulsa 0 para descargarlos\n"))    # Introducimos algun numero para descargar el fichero que queramos. Lo convertimos en integer

if i==0:                                                                                    # Si elegimos el valor 0 nos decargamos todos los ficheros del directorio                                                                               
    for j in range(len(files)):                                                             # Hacemos un for para la lista files y
        download(j)                                                                         # llamamos a la funcion download para descargar los ficheros
if i>0 and i<=len(files):                                                                   # Si elegimos unicamente un numero para descargarnos el elemento nos lo descargamos. Comprobamos que sea mayor de 0 y menor que la longitud de files 
    download(i-1)                                                                           # Nos descargamos i-1 por el tema que que los arrays empiezan por 0 

iOS Safari – How to disable overscroll but allow scrollable divs to scroll normally?

This solution doesn't require you to put a scrollable class on all your scrollable divs so is more general. Scrolling is allowed on all elements which are, or are children of, INPUT elements contenteditables and overflow scroll or autos.

I use a custom selector and I also cache the result of the check in the element to improve performance. No need to check the same element every time. This may have a few issues as only just written but thought I'd share.

$.expr[':'].scrollable = function(obj) {
    var $el = $(obj);
    var tagName = $el.prop("tagName");
    return (tagName !== 'BODY' && tagName !== 'HTML') && (tagName === 'INPUT' || $el.is("[contentEditable='true']") || $el.css("overflow").match(/auto|scroll/));
};
function preventBodyScroll() {
    function isScrollAllowed($target) {
        if ($target.data("isScrollAllowed") !== undefined) {
            return $target.data("isScrollAllowed");
        }
        var scrollAllowed = $target.closest(":scrollable").length > 0;
        $target.data("isScrollAllowed",scrollAllowed);
        return scrollAllowed;
    }
    $('body').bind('touchmove', function (ev) {
        if (!isScrollAllowed($(ev.target))) {
            ev.preventDefault();
        }
    });
}

How to include a sub-view in Blade templates?

You can use the blade template engine:

@include('view.name') 

'view.name' would live in your main views folder:

// for laravel 4.X
app/views/view/name.blade.php  

// for laravel 5.X
resources/views/view/name.blade.php

Another example

@include('hello.world');

would display the following view

// for laravel 4.X
app/views/hello/world.blade.php

// for laravel 5.X
resources/views/hello/world.blade.php

Another example

@include('some.directory.structure.foo');

would display the following view

// for Laravel 4.X
app/views/some/directory/structure/foo.blade.php

// for Laravel 5.X
resources/views/some/directory/structure/foo.blade.php

So basically the dot notation defines the directory hierarchy that your view is in, followed by the view name, relative to app/views folder for laravel 4.x or your resources/views folder in laravel 5.x

ADDITIONAL

If you want to pass parameters: @include('view.name', array('paramName' => 'value'))

You can then use the value in your views like so <p>{{$paramName}}</p>

Call static method with reflection

As the documentation for MethodInfo.Invoke states, the first argument is ignored for static methods so you can just pass null.

foreach (var tempClass in macroClasses)
{
   // using reflection I will be able to run the method as:
   tempClass.GetMethod("Run").Invoke(null, null);
}

As the comment points out, you may want to ensure the method is static when calling GetMethod:

tempClass.GetMethod("Run", BindingFlags.Public | BindingFlags.Static).Invoke(null, null);

X close button only using css

-- Simple HTML Solution --

Final result of easy to resize icon:

two close X buttons with different thickness.

JSfiddle demo: https://jsfiddle.net/allenski/yr5gk3cm/

The simple HTML:

<a href="#" class="close" tabindex="0" role="button">close</a>

Note:

  • tabindex attribute is there to help accessibility focus of iOS touch devices.
  • role attribute is to let screen readers users know this is a button.
  • The word close is also intended for screen readers to mention.

The CSS code:

.close {
    position: absolute;
    top: 0;
    right: 0;
    display: block;
    width: 50px;
    height: 50px;
    font-size: 0;
}
.close:before, 
.close:after {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 5px;
    height: 20px;
    background-color: #F0F0F0;
    transform: rotate(45deg) translate(-50%, -50%);
    transform-origin: top left;
    content: '';
}
.close:after {
    transform: rotate(-45deg) translate(-50%, -50%);
}

To adjust thickness of close X icon, change the width property. Example for thinner icon:

.close:before, 
.close:after {
    width: 2px;
}

To adjust length of close X icon, change the height property. Example:

.close:before, 
.close:after {
    height: 33px;
}

How to copy sheets to another workbook using vba?

    Workbooks.Open Filename:="Path(Ex: C:\Reports\ClientWiseReport.xls)"ReadOnly:=True


    For Each Sheet In ActiveWorkbook.Sheets

        Sheet.Copy After:=ThisWorkbook.Sheets(1)

    Next Sheet

Get Android shared preferences value in activity/normal class

I tried this code, to retrieve shared preferences from an activity, and could not get it to work:

        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
    sharedPreferences.getAll();
    Log.d("AddNewRecord", "getAll: " + sharedPreferences.getAll());
    Log.d("AddNewRecord", "Size: " + sharedPreferences.getAll().size());

Every time I tried, my preferences returned 0, even though I have 14 preferences saved by the preference activity. I finally found the answer. I added this to the preferences in the onCreate section.

getPreferenceManager().setSharedPreferencesName("defaultPreferences");

After I added this statement, my saved preferences returned as expected. I hope that this helps someone else who may experience the same issue that I did.

How to enable NSZombie in Xcode?

In xcode 4.2

Goto, Product -> edit scheme -> click Run yourappname.app -> Diagonostics -> Enable Zombie object.

How do you wait for input on the same Console.WriteLine() line?

Use Console.Write instead, so there's no newline written:

Console.Write("What is your name? ");
var name = Console.ReadLine();

Aligning label and textbox on same line (left and right)

You should use CSS to align the textbox. The reason your code above does not work is because by default a div's width is the same as the container it's in, therefore in your example it is pushed below.

The following would work.

<td  colspan="2" class="cell">
                <asp:Label ID="Label6" runat="server" Text="Label"></asp:Label>        
                <asp:TextBox ID="TextBox3" runat="server" CssClass="righttextbox"></asp:TextBox>       
</td>

In your CSS file:

.cell
{
text-align:left;
}

.righttextbox
{
float:right;
}

What does "use strict" do in JavaScript, and what is the reasoning behind it?

My two cents:

One of the goals of strict mode is to allow for faster debugging of issues. It helps the developers by throwing exception when certain wrong things occur that can cause silent & strange behaviour of your webpage. The moment we use use strict, the code will throw out errors which helps developer to fix it in advance.

Few important things which I have learned after using use strict :

Prevents Global Variable Declaration:

var tree1Data = { name: 'Banana Tree',age: 100,leafCount: 100000};

function Tree(typeOfTree) {
    var age;
    var leafCount;

    age = typeOfTree.age;
    leafCount = typeOfTree.leafCount;
    nameoftree = typeOfTree.name;
};

var tree1 = new Tree(tree1Data);
console.log(window);

Now,this code creates nameoftree in global scope which could be accessed using window.nameoftree. When we implement use strict the code would throw error.

Uncaught ReferenceError: nameoftree is not defined

Sample

Eliminates with statement :

with statements can't be minified using tools like uglify-js. They're also deprecated and removed from future JavaScript versions.

Sample

Prevents Duplicates :

When we have duplicate property, it throws an exception

Uncaught SyntaxError: Duplicate data property in object literal not allowed in strict mode

"use strict";
var tree1Data = {
    name: 'Banana Tree',
    age: 100,
    leafCount: 100000,
    name:'Banana Tree'
};

There are few more but I need to gain more knowledge on that.

Bootstrap 3 Horizontal and Vertical Divider

I know this is an "older" post. This question and the provided answers helped me get ideas for my own problem. I think this solution addresses the OP question (intersecting borders with 4 and 2 columns depending on display)

Fiddle: https://jsfiddle.net/tqmfpwhv/1/


css based on OP information, media query at end is for med & lg view.

.vr-all {
    padding:0px;
    border-right:1px solid #CC0000;
}
.vr-xs {
    padding:0px;
}
.vr-md {
    padding:0px;
}
.hrspacing { padding:0px; }
.hrcolor {
    border-color: #CC0000;
    border-style: solid;
    border-bottom: 1px;
    margin:0px;
    padding:0px;
}
/* for medium and up */
@media(min-width:992px){
    .vr-xs {
        border-right:1px solid #CC0000;
    }
    }

html adjustments to OP provided code. Red border and Img links for example.

<div class="container">
  <div class="row">
        <div class="col-xs-6 col-sm-6 col-md-3 text-center vr-all" id="one">
            <h5>Rich Media Ad Production</h5>
            <img src="http://png-1.findicons.com/files/icons/2338/reflection/128/mobile_phone.png" />
        </div>
        <div class="col-xs-6 col-sm-6 col-md-3 text-center vr-xs" id="two">
            <h5>Web Design & Development</h5>
            <img src="http://png-1.findicons.com/files/icons/2338/reflection/128/mobile_phone.png" >
        </div>

        <!-- hr for only x-small/small viewports -->
        <div class="col-xs-12 col-sm-12 hidden-md hidden-lg hrspacing"><hr class="hrcolor"></div>

        <div class="col-xs-6 col-sm-6 col-md-3 text-center vr-all" id="three">
            <h5>Mobile Apps Development</h5>
            <img src="http://png-1.findicons.com/files/icons/2338/reflection/128/mobile_phone.png" >
        </div>
        <div class="col-xs-6 col-sm-6 col-md-3 text-center vr-md" id="four">
            <h5>Creative Design</h5>
            <img src="http://png-1.findicons.com/files/icons/2338/reflection/128/mobile_phone.png" >
        </div>

        <!-- hr for for all viewports -->
        <div class="col-xs-12 hrspacing"><hr class="hrcolor"></div>

        <div class="col-xs-6 col-sm-6 col-md-3 text-center vr-all" id="five">
            <h5>Web Analytics</h5>
            <img src="http://png-1.findicons.com/files/icons/2338/reflection/128/mobile_phone.png" >
        </div>
        <div class="col-xs-6 col-sm-6 col-md-3 text-center vr-xs" id="six">
            <h5>Search Engine Marketing</h5>
            <img src="http://png-1.findicons.com/files/icons/2338/reflection/128/mobile_phone.png" >
        </div>

        <!-- hr for only x-small/small viewports -->
        <div class="col-xs-12 col-sm-12 hidden-md hidden-lg hrspacing"><hr class="hrcolor"></div>

        <div class="col-xs-6 col-sm-6 col-md-3 text-center vr-all" id="seven">
            <h5>Mobile Apps Development</h5>
            <img src="http://png-1.findicons.com/files/icons/2338/reflection/128/mobile_phone.png" >
        </div>
        <div class="col-xs-6 col-sm-6 col-md-3 text-center vr-md" id="eight">
            <h5>Quality Assurance</h5>
            <img src="http://png-1.findicons.com/files/icons/2338/reflection/128/mobile_phone.png" >
        </div>


    </div>
</div>

Keeping it simple and how to do multiple CTE in a query

You can have multiple CTEs in one query, as well as reuse a CTE:

WITH    cte1 AS
        (
        SELECT  1 AS id
        ),
        cte2 AS
        (
        SELECT  2 AS id
        )
SELECT  *
FROM    cte1
UNION ALL
SELECT  *
FROM    cte2
UNION ALL
SELECT  *
FROM    cte1

Note, however, that SQL Server may reevaluate the CTE each time it is accessed, so if you are using values like RAND(), NEWID() etc., they may change between the CTE calls.

How to format a duration in java? (e.g format H:MM:SS)

I'm not sure that is you want, but check this Android helper class

import android.text.format.DateUtils

For example: DateUtils.formatElapsedTime()

Java method: Finding object in array list given a known attribute value

I solved this using java 8 lambdas

int dogId = 2;

return dogList.stream().filter(dog-> dogId == dog.getId()).collect(Collectors.toList()).get(0);

Python: Best way to add to sys.path relative to the current running script

Using python 3.4+
Barring the use of cx_freeze or using in IDLE.

import sys
from pathlib import Path

sys.path.append(Path(__file__).parent / "lib")

SQL keys, MUL vs PRI vs UNI

Let's understand in simple words

  • PRI - It's a primary key, and used to identify records uniquely.
  • UNI - It's a unique key, and also used to identify records uniquely. It looks similar like primary key but a table can have multiple unique keys and unique key can have one null value, on the other hand table can have only one primary key and can't store null as a primary key.
  • MUL - It's doesn't have unique constraint and table can have multiple MUL columns.

Note: These keys have more depth as a concept but this is good to start.

Where to put default parameter value in C++?

C++ places the default parameter logic in the calling side, this means that if the default value expression cannot be computed from the calling place, then the default value cannot be used.

Other compilation units normally just include the declaration so default value expressions placed in the definition can be used only in the defining compilation unit itself (and after the definition, i.e. after the compiler sees the default value expressions).

The most useful place is in the declaration (.h) so that all users will see it.

Some people like to add the default value expressions in the implementation too (as a comment):

void foo(int x = 42,
         int y = 21);

void foo(int x /* = 42 */,
         int y /* = 21 */)
{
   ...
}

However, this means duplication and will add the possibility of having the comment out of sync with the code (what's worse than uncommented code? code with misleading comments!).

Error on renaming database in SQL Server 2008 R2

This did it for me:

USE [master];
GO
ALTER DATABASE [OldDataBaseName] SET SINGLE_USER WITH ROLLBACK IMMEDIATE;
GO
EXEC sp_renamedb N'OldDataBaseName', N'NewDataBaseName';


-- Add users again
ALTER DATABASE [NewDataBaseName] SET MULTI_USER
GO

AngularJs ReferenceError: $http is not defined

I have gone through the same problem when I was using

    myApp.controller('mainController', ['$scope', function($scope,) {
        //$http was not working in this
    }]);

I have changed the above code to given below. Remember to include $http(2 times) as given below.

 myApp.controller('mainController', ['$scope','$http', function($scope,$http) {
      //$http is working in this
 }]);

and It has worked well.

C++ int float casting

Integer division occurs, then the result, which is an integer, is assigned as a float. If the result is less than 1 then it ends up as 0.

You'll want to cast the expressions to floats first before dividing, e.g.

float m = (float)(a.y - b.y) / (float)(a.x - b.x);

jQuery AJAX form using mail() PHP script sends email, but POST data from HTML form is undefined

Your PHP script (external file 'email.php') should look like this:

<?php
if($_POST){
    $name = $_POST['name'];
    $email = $_POST['email'];
    $message = $_POST['text'];

//send email
    mail("[email protected]", "51 Deep comment from" .$email, $message);
}
?>

Is bool a native C type?

bool exists in the current C - C99, but not in C89/90.

In C99 the native type is actually called _Bool, while bool is a standard library macro defined in stdbool.h (which expectedly resolves to _Bool). Objects of type _Bool hold either 0 or 1, while true and false are also macros from stdbool.h.

Note, BTW, that this implies that C preprocessor will interpret #if true as #if 0 unless stdbool.h is included. Meanwhile, C++ preprocessor is required to natively recognize true as a language literal.

How to echo xml file in php

You can use the asXML method

echo $xml->asXML();

You can also give it a filename

$xml->asXML('filename.xml');

How to run the Python program forever?

I know this is too old thread but why no one mentioned this

#!/usr/bin/python3
import asyncio 

loop = asyncio.get_event_loop()
try:
    loop.run_forever()
finally:
    loop.close()

Dynamic button click event handler

Some code for a variation on this problem. Using the above code got me my click events as needed, but I was then stuck trying to work out which button had been clicked. My scenario is I have a dynamic amount of tab pages. On each tab page are (all dynamically created) 2 charts, 2 DGVs and a pair of radio buttons. Each control has a unique name relative to the tab, but there could be 20 radio buttons with the same name if I had 20 tab pages. The radio buttons switch between which of the 2 graphs and DGVs you get to see. Here is the code for when one of the radio buttons gets checked (There's a nearly identical block that swaps the charts and DGVs back):

   Private Sub radioFit_Components_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)

    If sender.name = "radioFit_Components" And sender.visible Then
        If sender.checked Then
            For Each ctrl As Control In TabControl1.SelectedTab.Controls
                Select Case ctrl.Name
                    Case "embChartSSE_Components"
                        ctrl.BringToFront()
                    Case "embChartSSE_Fit_Curve"
                        ctrl.SendToBack()
                    Case "dgvFit_Components"
                        ctrl.BringToFront()
                End Select
            Next

        End If
    End If

End Sub

This code will fire for any of the tab pages and swap the charts and DGVs over on any of the tab pages. The sender.visible check is to stop the code firing when the form is being created.

HTML anchor link - href and onclick both?

<a href="#Foo" onclick="return runMyFunction();">Do it!</a>

and

function runMyFunction() {
  //code
  return true;
}

This way you will have youf function executed AND you will follow the link AND you will follow the link exactly after your function was successfully run.

How do I convert Int/Decimal to float in C#?

You can just do a cast

int val1 = 1;
float val2 = (float)val1;

or

decimal val3 = 3;
float val4 = (float)val3;

How to replace local branch with remote branch entirely in Git?

git checkout .

i always use this command to replace my local changes with repository changes. git checkout space dot.

Why a function checking if a string is empty always returns true?

You can simply cast to bool, dont forget to handle zero.

function isEmpty(string $string): bool {
    if($string === '0') {
        return false;
    }
    return !(bool)$string;
}

var_dump(isEmpty('')); // bool(true)
var_dump(isEmpty('foo')); // bool(false)
var_dump(isEmpty('0')); // bool(false)

Bold words in a string of strings.xml in Android

I was having a text something like:

Forgot Password? Reset here.

To implement this the easy way I used the existing android:textStyle="bold"

<LinearLayout
        android:id="@+id/forgotPassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:gravity="center"
        >


        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:autoLink="all"
            android:linksClickable="false"
            android:selectAllOnFocus="false"

            android:text="Forgot password? "
            android:textAlignment="center"
            android:textColor="@android:color/white"
            />

        <TextView

            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:autoLink="all"
            android:linksClickable="false"
            android:selectAllOnFocus="false"

            android:text="Reset here"
            android:textAlignment="center"
            android:textColor="@android:color/white"
            android:textStyle="bold" />
    </LinearLayout>

Maybe it helps someone

Spring Bean Scopes

Also websocket scope is added:

Scopes a single bean definition to the lifecycle of a WebSocket. Only valid in the context of a web-aware Spring ApplicationContext.

As the per the content of the documentation, there is also thread scope, that is not registered by default.

Output ("echo") a variable to a text file

Note: The answer below is written from the perspective of Windows PowerShell.
However, it applies to the cross-platform PowerShell Core edition (v6+) as well, except that the latter - commendably - consistently defaults to BOM-less UTF-8 character encoding, which is the most widely compatible one across platforms and cultures.
.


To complement bigtv's helpful answer helpful answer with a more concise alternative and background information:

# > $file is effectively the same as | Out-File $file
# Objects are written the same way they display in the console.
# Default character encoding is UTF-16LE (mostly 2 bytes per char.), with BOM.
# Use Out-File -Encoding <name> to change the encoding.
$env:computername > $file

# Set-Content calls .ToString() on each object to output.
# Default character encoding is "ANSI" (culture-specific, single-byte).
# Use Set-Content -Encoding <name> to change the encoding.
# Use Set-Content rather than Add-Content; the latter is for *appending* to a file.
$env:computername | Set-Content $file 

When outputting to a text file, you have 2 fundamental choices that use different object representations and, in Windows PowerShell (as opposed to PowerShell Core), also employ different default character encodings:

  • Out-File (or >) / Out-File -Append (or >>):

    • Suitable for output objects of any type, because PowerShell's default output formatting is applied to the output objects.

      • In other words: you get the same output as when printing to the console.
    • The default encoding, which can be changed with the -Encoding parameter, is Unicode, which is UTF-16LE in which most characters are encoded as 2 bytes. The advantage of a Unicode encoding such as UTF-16LE is that it is a global alphabet, capable of encoding all characters from all human languages.

      • In PSv5.1+, you can change the encoding used by > and >>, via the $PSDefaultParameterValues preference variable, taking advantage of the fact that > and >> are now effectively aliases of Out-File and Out-File -Append. To change to UTF-8, for instance, use:
        $PSDefaultParameterValues['Out-File:Encoding']='UTF8'
  • Set-Content / Add-Content:

    • For writing strings and instances of types known to have meaningful string representations, such as the .NET primitive data types (Booleans, integers, ...).

      • .psobject.ToString() method is called on each output object, which results in meaningless representations for types that don't explicitly implement a meaningful representation; [hashtable] instances are an example:
        @{ one = 1 } | Set-Content t.txt writes literal System.Collections.Hashtable to t.txt, which is the result of @{ one = 1 }.ToString().
    • The default encoding, which can be changed with the -Encoding parameter, is Default, which is the system's "ANSI" code page, a the single-byte culture-specific legacy encoding for non-Unicode applications, most commonly Windows-1252.
      Note that the documentation currently incorrectly claims that ASCII is the default encoding.

    • Note that Add-Content's purpose is to append content to an existing file, and it is only equivalent to Set-Content if the target file doesn't exist yet.
      Furthermore, the default or specified encoding is blindly applied, irrespective of the file's existing contents' encoding.

Out-File / > / Set-Content / Add-Content all act culture-sensitively, i.e., they produce representations suitable for the current culture (locale), if available (though custom formatting data is free to define its own, culture-invariant representation - see Get-Help about_format.ps1xml). This contrasts with PowerShell's string expansion (string interpolation in double-quoted strings), which is culture-invariant - see this answer of mine.

As for performance: Since Set-Content doesn't have to apply default formatting to its input, it performs better.


As for the OP's symptom with Add-Content:

Since $env:COMPUTERNAME cannot contain non-ASCII characters, Add-Content's output, using "ANSI" encoding, should not result in ? characters in the output, and the likeliest explanation is that the ? were part of the preexisting content in output file $file, which Add-Content appended to.

error LNK2001: unresolved external symbol (C++)

Sounds like you are using Microsoft Visual C++. If that is the case, then the most possibility is that you don't compile your two.cpp with one.cpp (one.cpp is the implementation for one.h).

If you are from command line (cmd.exe), then try this first: cl -o two.exe one.cpp two.cpp

If you are from IDE, right click on the project name from Solution Explore. Then choose Add, Existing Item.... Add one.cpp into your project.

Convert number to varchar in SQL with formatting

What is the value range? Is it 0 through 10? If so, then try:

SELECT REPLICATE('0',2-LEN(@t)) + CAST(@t AS VARCHAR)

That handles 0 through 9 as well as 10 through 99.

Now, tinyint can go up to the value of 255. If you want to handle > 99 through 255, then try this solution:

declare @t  TINYINT
set @t =233
SELECT ISNULL(REPLICATE('0',2-LEN(@t)),'') + CAST(@t AS VARCHAR)

To understand the solution, the expression to the left of the + calculates the number of zeros to prefix to the string.

In case of the value 3, the length is 1. 2 - 1 is 1. REPLICATE Adds one zero. In case of the value 10, the length is 2. 2 - 2 is 0. REPLICATE Adds nothing. In the case of the value 100, the length is -1 which produces a NULL. However, the null value is handled and set to an empty string.

Now if you decide that because tinyint can contain up to 255 and you want your formatting as three characters, just change the 2-LEN to 3-LEN in the left expression and you're set.

How to rename array keys in PHP?

This should work in most versions of PHP 4+. Array map using anonymous functions is not supported below 5.3.

Also the foreach examples will throw a warning when using strict PHP error handling.

Here is a small multi-dimensional key renaming function. It can also be used to process arrays to have the correct keys for integrity throughout your app. It will not throw any errors when a key does not exist.

function multi_rename_key(&$array, $old_keys, $new_keys)
{
    if(!is_array($array)){
        ($array=="") ? $array=array() : false;
        return $array;
    }
    foreach($array as &$arr){
        if (is_array($old_keys))
        {
            foreach($new_keys as $k => $new_key)
            {
                (isset($old_keys[$k])) ? true : $old_keys[$k]=NULL;
                $arr[$new_key] = (isset($arr[$old_keys[$k]]) ? $arr[$old_keys[$k]] : null);
                unset($arr[$old_keys[$k]]);
            }
        }else{
            $arr[$new_keys] = (isset($arr[$old_keys]) ? $arr[$old_keys] : null);
            unset($arr[$old_keys]);
        }
    }
    return $array;
}

Usage is simple. You can either change a single key like in your example:

multi_rename_key($tags, "url", "value");

or a more complex multikey

multi_rename_key($tags, array("url","name"), array("value","title"));

It uses similar syntax as preg_replace() where the amount of $old_keys and $new_keys should be the same. However when they are not a blank key is added. This means you can use it to add a sort if schema to your array.

Use this all the time, hope it helps!

How to remove the hash from window.location (URL) with JavaScript without page refresh?

Here is another solution to change the location using href and clear the hash without scrolling.

The magic solution is explained here. Specs here.

const hash = window.location.hash;
history.scrollRestoration = 'manual';
window.location.href = hash;    
history.pushState('', document.title, window.location.pathname);

NOTE: The proposed API is now part of WhatWG HTML Living Standard

Failed to decode downloaded font, OTS parsing error: invalid version tag + rails 4

I had same problem when I opened and saved .woff and .woff2 files through Sublime Text with EditorConfig option end_of_line = lf. I just copied files to font folder without opening them into Sublime and problem was solved.

Enum to String C++

Kind of an anonymous lookup table rather than a long switch statement:

return (const char *[]) {
    "bananas & monkeys",
    "Round and orange", 
    "APPLE",
}[enumVal];

What is Linux’s native GUI API?

GUI is a high level abstraction of capability, so almost everything from XOrg server to OpenGL is ported cross-platform, including for Windows platform. But if by GUI API you mean *nix graphics API then you might be wandering around "Direct Rendering Infrastructure".

Threads vs Processes in Linux

The decision between thread/process depends a little bit on what you will be using it to. One of the benefits with a process is that it has a PID and can be killed without also terminating the parent.

For a real world example of a web server, apache 1.3 used to only support multiple processes, but in in 2.0 they added an abstraction so that you can swtch between either. Comments seems to agree that processes are more robust but threads can give a little bit better performance (except for windows where performance for processes sucks and you only want to use threads).

Find CRLF in Notepad++

It appears that this is a FAQ, and the resolution offered is:

Simple search (Ctrl+H) without regexp

You can turn on View/Show End of Line or view/Show All, and select the now visible newline characters. Then when you start the command some characters matching the newline character will be pasted into the search field. Matches will be replaced by the replace string, unlike in regex mode.

Note 1: If you select them with the mouse, start just before them and drag to the start of the next line. Dragging to the end of the line won't work.

Note 2: You can't copy and paste them into the field yourself.

Advanced search (Ctrl+R) without regexp

Ctrl+M will insert something that matches newlines. They will be replaced by the replace string.

How to use shell commands in Makefile

Also, in addition to torek's answer: one thing that stands out is that you're using a lazily-evaluated macro assignment.

If you're on GNU Make, use the := assignment instead of =. This assignment causes the right hand side to be expanded immediately, and stored in the left hand variable.

FILES := $(shell ...)  # expand now; FILES is now the result of $(shell ...)

FILES = $(shell ...)   # expand later: FILES holds the syntax $(shell ...)

If you use the = assignment, it means that every single occurrence of $(FILES) will be expanding the $(shell ...) syntax and thus invoking the shell command. This will make your make job run slower, or even have some surprising consequences.

How to deal with bad_alloc in C++?

You can catch it like any other exception:

try {
  foo();
}
catch (const std::bad_alloc&) {
  return -1;
}

Quite what you can usefully do from this point is up to you, but it's definitely feasible technically.



In general you cannot, and should not try, to respond to this error. bad_alloc indicates that a resource cannot be allocated because not enough memory is available. In most scenarios your program cannot hope to cope with that, and terminating soon is the only meaningful behaviour.

Worse, modern operating systems often over-allocate: on such systems, malloc and new can return a valid pointer even if there is not enough free memory left – std::bad_alloc will never be thrown, or is at least not a reliable sign of memory exhaustion. Instead, attempts to access the allocated memory will then result in a segmentation fault, which is not catchable (you can handle the segmentation fault signal, but you cannot resume the program afterwards).

The only thing you could do when catching std::bad_alloc is to perhaps log the error, and try to ensure a safe program termination by freeing outstanding resources (but this is done automatically in the normal course of stack unwinding after the error gets thrown if the program uses RAII appropriately).

In certain cases, the program may attempt to free some memory and try again, or use secondary memory (= disk) instead of RAM but these opportunities only exist in very specific scenarios with strict conditions:

  1. The application must ensure that it runs on a system that does not overcommit memory, i.e. it signals failure upon allocation rather than later.
  2. The application must be able to free memory immediately, without any further accidental allocations in the meantime.

It’s exceedingly rare that applications have control over point 1 — userspace applications never do, it’s a system-wide setting that requires root permissions to change.1

OK, so let’s assume you’ve fixed point 1. What you can now do is for instance use a LRU cache for some of your data (probably some particularly large business objects that can be regenerated or reloaded on demand). Next, you need to put the actual logic that may fail into a function that supports retry — in other words, if it gets aborted, you can just relaunch it:

lru_cache<widget> widget_cache;

double perform_operation(int widget_id) {
    std::optional<widget> maybe_widget = widget_cache.find_by_id(widget_id);
    if (not maybe_widget) {
        maybe_widget = widget_cache.store(widget_id, load_widget_from_disk(widget_id));
    }
    return maybe_widget->frobnicate();
}

…

for (int num_attempts = 0; num_attempts < MAX_NUM_ATTEMPTS; ++num_attempts) {
    try {
        return perform_operation(widget_id);
    } catch (std::bad_alloc const&) {
        if (widget_cache.empty()) throw; // memory error elsewhere.
        widget_cache.remove_oldest();
    }
}

// Handle too many failed attempts here.

But even here, using std::set_new_handler instead of handling std::bad_alloc provides the same benefit and would be much simpler.


1 If you’re creating an application that does control point 1, and you’re reading this answer, please shoot me an email, I’m genuinely curious about your circumstances.


What is the C++ Standard specified behavior of new in c++?

The usual notion is that if new operator cannot allocate dynamic memory of the requested size, then it should throw an exception of type std::bad_alloc.
However, something more happens even before a bad_alloc exception is thrown:

C++03 Section 3.7.4.1.3: says

An allocation function that fails to allocate storage can invoke the currently installed new_handler(18.4.2.2), if any. [Note: A program-supplied allocation function can obtain the address of the currently installed new_handler using the set_new_handler function (18.4.2.3).] If an allocation function declared with an empty exception-specification (15.4), throw(), fails to allocate storage, it shall return a null pointer. Any other allocation function that fails to allocate storage shall only indicate failure by throw-ing an exception of class std::bad_alloc (18.4.2.1) or a class derived from std::bad_alloc.

Consider the following code sample:

#include <iostream>
#include <cstdlib>

// function to call if operator new can't allocate enough memory or error arises
void outOfMemHandler()
{
    std::cerr << "Unable to satisfy request for memory\n";

    std::abort();
}

int main()
{
    //set the new_handler
    std::set_new_handler(outOfMemHandler);

    //Request huge memory size, that will cause ::operator new to fail
    int *pBigDataArray = new int[100000000L];

    return 0;
}

In the above example, operator new (most likely) will be unable to allocate space for 100,000,000 integers, and the function outOfMemHandler() will be called, and the program will abort after issuing an error message.

As seen here the default behavior of new operator when unable to fulfill a memory request, is to call the new-handler function repeatedly until it can find enough memory or there is no more new handlers. In the above example, unless we call std::abort(), outOfMemHandler() would be called repeatedly. Therefore, the handler should either ensure that the next allocation succeeds, or register another handler, or register no handler, or not return (i.e. terminate the program). If there is no new handler and the allocation fails, the operator will throw an exception.

What is the new_handler and set_new_handler?

new_handler is a typedef for a pointer to a function that takes and returns nothing, and set_new_handler is a function that takes and returns a new_handler.

Something like:

typedef void (*new_handler)();
new_handler set_new_handler(new_handler p) throw();

set_new_handler's parameter is a pointer to the function operator new should call if it can't allocate the requested memory. Its return value is a pointer to the previously registered handler function, or null if there was no previous handler.

How to handle out of memory conditions in C++?

Given the behavior of newa well designed user program should handle out of memory conditions by providing a proper new_handlerwhich does one of the following:

Make more memory available: This may allow the next memory allocation attempt inside operator new's loop to succeed. One way to implement this is to allocate a large block of memory at program start-up, then release it for use in the program the first time the new-handler is invoked.

Install a different new-handler: If the current new-handler can't make any more memory available, and of there is another new-handler that can, then the current new-handler can install the other new-handler in its place (by calling set_new_handler). The next time operator new calls the new-handler function, it will get the one most recently installed.

(A variation on this theme is for a new-handler to modify its own behavior, so the next time it's invoked, it does something different. One way to achieve this is to have the new-handler modify static, namespace-specific, or global data that affects the new-handler's behavior.)

Uninstall the new-handler: This is done by passing a null pointer to set_new_handler. With no new-handler installed, operator new will throw an exception ((convertible to) std::bad_alloc) when memory allocation is unsuccessful.

Throw an exception convertible to std::bad_alloc. Such exceptions are not be caught by operator new, but will propagate to the site originating the request for memory.

Not return: By calling abort or exit.

File content into unix variable with newlines

Bash -ge 4 has the mapfile builtin to read lines from the standard input into an array variable.

help mapfile 

mapfile < file.txt lines
printf "%s" "${lines[@]}"

mapfile -t < file.txt lines    # strip trailing newlines
printf "%s\n" "${lines[@]}" 

See also:

http://bash-hackers.org/wiki/doku.php/commands/builtin/mapfile

How to modify a CSS display property from JavaScript?

CSS properties should be set by cssText property or setAttribute method.

// Set multiple styles in a single statement
elt.style.cssText = "color: blue; border: 1px solid black"; 
// Or
elt.setAttribute("style", "color:red; border: 1px solid blue;");

Styles should not be set by assigning a string directly to the style property (as in elt.style = "color: blue;"), since it is considered read-only, as the style attribute returns a CSSStyleDeclaration object which is also read-only.

How to plot vectors in python using matplotlib

This may also be achieved using matplotlib.pyplot.quiver, as noted in the linked answer;

plt.quiver([0, 0, 0], [0, 0, 0], [1, -2, 4], [1, 2, -7], angles='xy', scale_units='xy', scale=1)
plt.xlim(-10, 10)
plt.ylim(-10, 10)
plt.show()

mpl output

Creating a new ArrayList in Java

    ArrayList<Class> myArray = new ArrayList<Class>();

Here ArrayList of the particular Class will be made. In general one can have any datatype like int,char, string or even an array in place of Class.

These are added to the array list using

    myArray.add();

And the values are retrieved using

    myArray.get();

Which Architecture patterns are used on Android?

Update November 2018

After working and blogging about MVC and MVP in Android for several years (see the body of the answer below), I decided to capture my knowledge and understanding in a more comprehensive and easily digestible form.

So, I released a full blown video course about Android applications architecture. So, if you're interested in mastering the most advanced architectural patterns in Android development, check out this comprehensive course here.

This answer was updated in order to remain relevant as of November 2016


It looks like you are seeking for architectural patterns rather than design patterns.

Design patterns aim at describing a general "trick" that programmer might implement for handling a particular set of recurring software tasks. For example: In OOP, when there is a need for an object to notify a set of other objects about some events, the observer design pattern can be employed.

Since Android applications (and most of AOSP) are written in Java, which is object-oriented, I think you'll have a hard time looking for a single OOP design pattern which is NOT used on Android.

Architectural patterns, on the other hand, do not address particular software tasks - they aim to provide templates for software organization based on the use cases of the software component in question.

It sounds a bit complicated, but I hope an example will clarify: If some application will be used to fetch data from a remote server and present it to the user in a structured manner, then MVC might be a good candidate for consideration. Note that I said nothing about software tasks and program flow of the application - I just described it from user's point of view, and a candidate for an architectural pattern emerged.

Since you mentioned MVC in your question, I'd guess that architectural patterns is what you're looking for.

Enter image description here


Historically, there were no official guidelines by Google about applications' architectures, which (among other reasons) led to a total mess in the source code of Android apps. In fact, even today most applications that I see still do not follow OOP best practices and do not show a clear logical organization of code.

But today the situation is different - Google recently released the Data Binding library, which is fully integrated with Android Studio, and, even, rolled out a set of architecture blueprints for Android applications.

Two years ago it was very hard to find information about MVC or MVP on Android. Today, MVC, MVP and MVVM has become "buzz-words" in the Android community, and we are surrounded by countless experts which constantly try to convince us that MVx is better than MVy. In my opinion, discussing whether MVx is better than MVy is totally pointless because the terms themselves are very ambiguous - just look at the answers to this question, and you'll realize that different people can associate these abbreviations with completely different constructs.

Due to the fact that a search for a best architectural pattern for Android has officially been started, I think we are about to see several more ideas come to light. At this point, it is really impossible to predict which pattern (or patterns) will become industry standards in the future - we will need to wait and see (I guess it is matter of a year or two).

However, there is one prediction I can make with a high degree of confidence: Usage of the Data Binding library will not become an industry standard. I'm confident to say that because the Data Binding library (in its current implementation) provides short-term productivity gains and some kind of architectural guideline, but it will make the code non-maintainable in the long run. Once long-term effects of this library will surface - it will be abandoned.


Now, although we do have some sort of official guidelines and tools today, I, personally, don't think that these guidelines and tools are the best options available (and they are definitely not the only ones). In my applications I use my own implementation of an MVC architecture. It is simple, clean, readable and testable, and does not require any additional libraries.

This MVC is not just cosmetically different from others - it is based on a theory that Activities in Android are not UI Elements, which has tremendous implications on code organization.

So, if you're looking for a good architectural pattern for Android applications that follows SOLID principles, you can find a description of one in my post about MVC and MVP architectural patterns in Android.

Change Bootstrap tooltip color

For bootstrap4 I used code:

_x000D_
_x000D_
$('[data-toggle="tooltip"]').tooltip();
_x000D_
.tooltip-inner {
  background-color: #f00 !important;
  color: #f00 ;
}
.bs-tooltip-top .arrow::before, .bs-tooltip-auto[x-placement^="top"] .arrow::before {
  border-top-color: #f00 !important;
}

.bs-tooltip-right .arrow::before, .bs-tooltip-auto[x-placement^="right"] .arrow::before {
  border-right-color: #f00 !important;
}


.bs-tooltip-bottom .arrow::before, .bs-tooltip-auto[x-placement^="bottom"] .arrow::before {
  border-bottom-color: #f00 !important;
}


.bs-tooltip-left .arrow::before, .bs-tooltip-auto[x-placement^="left"] .arrow::before {
  border-left-color: #f00 !important;
}
_x000D_
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" rel="stylesheet"/>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"></script>



<a title="This is an example" data-toggle="tooltip">Hover me</a>
_x000D_
_x000D_
_x000D_

MySql Error: 1364 Field 'display_name' doesn't have default value

I also faced that problem and there are two ways to solve this in laravel.

  1. first one is you can set the default value as null. I will show you an example:

    public function up()
    {
        Schema::create('users', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name');
            $table->string('gender');
            $table->string('slug');
            $table->string('pic')->nullable();
            $table->string('email')->unique();
            $table->string('password');
            $table->rememberToken();
            $table->timestamps();
        });
    }
    

as the above example, you can set nullable() for that feature. then when you are inserting data MySQL set the default value as null.

  1. second one is in your model set your input field in protected $fillable field. as example:

    protected $fillable = [
        'name', 'email', 'password', 'slug', 'gender','pic'
    ];
    

I think the second one is fine than the first one and also you can set nullable feature as well as fillable in the same time without a problem.

Image vs zImage vs uImage

What is the difference between them?

Image: the generic Linux kernel binary image file.

zImage: a compressed version of the Linux kernel image that is self-extracting.

uImage: an image file that has a U-Boot wrapper (installed by the mkimage utility) that includes the OS type and loader information.
A very common practice (e.g. the typical Linux kernel Makefile) is to use a zImage file. Since a zImage file is self-extracting (i.e. needs no external decompressors), the wrapper would indicate that this kernel is "not compressed" even though it actually is.


Note that the author/maintainer of U-Boot considers the (widespread) use of using a zImage inside a uImage questionable:

Actually it's pretty stupid to use a zImage inside an uImage. It is much better to use normal (uncompressed) kernel image, compress it using just gzip, and use this as poayload for mkimage. This way U-Boot does the uncompresiong instead of including yet another uncompressor with each kernel image.

(quoted from https://lists.yoctoproject.org/pipermail/yocto/2013-October/016778.html)


Which type of kernel image do I have to use?

You could choose whatever you want to program for.
For economy of storage, you should probably chose a compressed image over the uncompressed one.
Beware that executing the kernel (presumably the Linux kernel) involves more than just loading the kernel image into memory. Depending on the architecture (e.g. ARM) and the Linux kernel version (e.g. with or without DTB), there are registers and memory buffers that may have to be prepared for the kernel. In one instance there was also hardware initialization that U-Boot performed that had to be replicated.

ADDENDUM

I know that u-boot needs a kernel in uImage format.

That is accurate for all versions of U-Boot which only have the bootm command.
But more recent versions of U-Boot could also have the bootz command that can boot a zImage.

C# Java HashMap equivalent

From C# equivalent to Java HashMap

I needed a Dictionary which accepted a "null" key, but there seems to be no native one, so I have written my own. It's very simple, actually. I inherited from Dictionary, added a private field to hold the value for the "null" key, then overwritten the indexer. It goes like this :

public class NullableDictionnary : Dictionary<string, string>
{
    string null_value;

    public StringDictionary this[string key]
    {
        get
        {
            if (key == null) 
            {
                return null_value;
            }
            return base[key];
        }
        set
        {
            if (key == null)
            {
                null_value = value;
            }
            else 
            {
                base[key] = value;
            }
        }
    }
}

Hope this helps someone in the future.

==========

I modified it to this format

public class NullableDictionnary : Dictionary<string, object>

Using setDate in PreparedStatement

tl;dr

With JDBC 4.2 or later and java 8 or later:

myPreparedStatement.setObject( … , myLocalDate  )

…and…

myResultSet.getObject( … , LocalDate.class )

Details

The Answer by Vargas is good about mentioning java.time types but refers only to converting to java.sql.Date. No need to convert if your driver is updated.

java.time

The java.time framework is built into Java 8 and later. These classes supplant the old troublesome date-time classes such as java.util.Date, .Calendar, & java.text.SimpleDateFormat. The Joda-Time team also advises migration to java.time.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations.

Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport and further adapted to Android in ThreeTenABP.

LocalDate

In java.time, the java.time.LocalDate class represents a date-only value without time-of-day and without time zone.

If using a JDBC driver compliant with JDBC 4.2 or later spec, no need to use the old java.sql.Date class. You can pass/fetch LocalDate objects directly to/from your database via PreparedStatement::setObject and ResultSet::getObject.

LocalDate localDate = LocalDate.now( ZoneId.of( "America/Montreal" ) );
myPreparedStatement.setObject( 1 , localDate  );

…and…

LocalDate localDate = myResultSet.getObject( 1 , LocalDate.class );

Before JDBC 4.2, convert

If your driver cannot handle the java.time types directly, fall back to converting to java.sql types. But minimize their use, with your business logic using only java.time types.

New methods have been added to the old classes for conversion to/from java.time types. For java.sql.Date see the valueOf and toLocalDate methods.

java.sql.Date sqlDate = java.sql.Date.valueOf( localDate );

…and…

LocalDate localDate = sqlDate.toLocalDate();

Placeholder value

Be wary of using 0000-00-00 as a placeholder value as shown in your Question’s code. Not all databases and other software can handle going back that far in time. I suggest using something like the commonly-used Unix/Posix epoch reference date of 1970, 1970-01-01.

LocalDate EPOCH_DATE = LocalDate.ofEpochDay( 0 ); // 1970-01-01 is day 0 in Epoch counting.

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.

Where to obtain the java.time classes?

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

how to make twitter bootstrap submenu to open on the left side?

If you have only one level and you use bootstrap 3 add pull-right to the ul element

<ul class="dropdown-menu pull-right" role="menu">

MVC: How to Return a String as JSON

The issue, I believe, is that the Json action result is intended to take an object (your model) and create an HTTP response with content as the JSON-formatted data from your model object.

What you are passing to the controller's Json method, though, is a JSON-formatted string object, so it is "serializing" the string object to JSON, which is why the content of the HTTP response is surrounded by double-quotes (I'm assuming that is the problem).

I think you can look into using the Content action result as an alternative to the Json action result, since you essentially already have the raw content for the HTTP response available.

return this.Content(returntext, "application/json");
// not sure off-hand if you should also specify "charset=utf-8" here, 
//  or if that is done automatically

Another alternative would be to deserialize the JSON result from the service into an object and then pass that object to the controller's Json method, but the disadvantage there is that you would be de-serializing and then re-serializing the data, which may be unnecessary for your purposes.

How do I disable a href link in JavaScript?

Install this plugin for jquery and use it

http://plugins.jquery.com/project/jqueryenabledisable

It allows you to disable/enable pretty much any field in the page.

If you want to open a page on some condition write a java script function and call it from href. If the condition satisfied you open page otherwise just do nothing.

code looks like this:

<a href="javascript: openPage()" >Click here</a>

and function:
function openPage()
{
if(some conditon)
opener.document.location = "http://www.google.com";
}
}

You can also put the link in a div and set the display property of the Style attribute to none. this will hide the div. For eg.,

<div id="divid" style="display:none">
<a href="Hiding Link" />
</div>

This will hide the link. Use a button or an image to make this div visible now by calling this function in onclick as:

<a href="Visible Link" onclick="showDiv()">

and write the js code as:

function showDiv(){
document.getElememtById("divid").style.display="block";
}

You can also put an id tag to the html tag, so it would be

<a id="myATag" href="whatever"></a>

And get this id on your javascript by using

document.getElementById("myATag").value="#"; 

One of this must work for sure haha

How to extract string following a pattern with grep, regex or perl

If the structure of your xml (or text in general) is fixed, the easiest way is using cut. For your specific case:

echo '<table name="content_analyzer" primary-key="id">
  <type="global" />
</table>
<table name="content_analyzer2" primary-key="id">
  <type="global" />
</table>
<table name="content_analyzer_items" primary-key="id">
  <type="global" />
</table>' | grep name= | cut -f2 -d '"'

What is the use of BindingResult interface in spring MVC?

Basically BindingResult is an interface which dictates how the object that stores the result of validation should store and retrieve the result of the validation(errors, attempt to bind to disallowed fields etc)

From Spring MVC Form Validation with Annotations Tutorial:

[BindingResult] is Spring’s object that holds the result of the validation and binding and contains errors that may have occurred. The BindingResult must come right after the model object that is validated or else Spring will fail to validate the object and throw an exception.

When Spring sees @Valid, it tries to find the validator for the object being validated. Spring automatically picks up validation annotations if you have “annotation-driven” enabled. Spring then invokes the validator and puts any errors in the BindingResult and adds the BindingResult to the view model.

XPath to fetch SQL XML value

I always go back to this article SQL Server 2005 XQuery and XML-DML - Part 1 to know how to use the XML features in SQL Server 2005.

For basic XPath know-how, I'd recommend the W3Schools tutorial.

How to convert upper case letters to lower case

You can find more methods and functions related to Python strings in section 5.6.1. String Methods of the documentation.

w.strip(',.').lower()

jQuery delete all table rows except first

$('#table tr').slice(1).remove();

I remember coming across that 'slice' is faster than all other approaches, so just putting it here.

Hidden Columns in jqGrid

I just want to expand on queen3's suggestion, applying the following does the trick:

editoptions: { 
              dataInit: function(element) { 
                          $(element).attr("readonly", "readonly"); 
                        } 
             }

Scenario #1:

  • Field must be visible in the grid
  • Field must be visible in the form
  • Field must be read-only

Solution:

colModel:[
        {  name:'providerUserId',
               index:'providerUserId', 
               width:100,editable:true, 
               editrules:{required:true}, 
               editoptions:{ 
                            dataInit: function(element) { 
                                  jq(element).attr("readonly", "readonly"); 
                             } 
                           }
            },
],

The providerUserId is visible in the grid and visible when editing the form. But you cannot edit the contents.


Scenario #2:

  • Field must not be visible in the grid
  • Field must be visible in the form
  • Field must be read-only

Solution:

colModel:[
           {name:'providerUserId',
            index:'providerUserId', 
            width:100,editable:true, 
            editrules:{
                         required:true, 
                         edithidden:true
                      },
            hidden:true, 
            editoptions:{ 
                  dataInit: function(element) {                     
                             jq(element).attr("readonly", "readonly"); 
                          } 
                     }
         },
        ]

Notice in both instances I'm using jq to reference jquery, instead of the usual $. In my HTML I have the following script to modify the variable used by jQuery:

<script type="text/javascript">
    var jq = jQuery.noConflict();
</script>