Programs & Examples On #Opennms

OpenNMS is an enterprise grade network monitoring and network management platform developed under the free software or open source model.

json parsing error syntax error unexpected end of input

May be it will be useful.

The method parameter name should be the same like it has JSON

It will work fine

C#

public ActionResult GetMTypes(int id)

JS

 var params = { id: modelId  };
                 var url = '@Url.Action("GetMTypes", "MaintenanceTypes")';
                 $.ajax({
                     type: "POST",
                     url: url,
                     contentType: "application/json; charset=utf-8",
                     dataType: "json",
                     data: JSON.stringify(params),

It will NOT work fine

C#

public ActionResult GetMTypes(int modelId)

JS

 var params = { id: modelId  };
                 var url = '@Url.Action("GetMTypes", "MaintenanceTypes")';
                 $.ajax({
                     type: "POST",
                     url: url,
                     contentType: "application/json; charset=utf-8",
                     dataType: "json",
                     data: JSON.stringify(params),

What are the -Xms and -Xmx parameters when starting JVM?

Run the command java -X and you will get a list of all -X options:

C:\Users\Admin>java -X
-Xmixed           mixed mode execution (default)
-Xint             interpreted mode execution only
-Xbootclasspath:<directories and zip/jar files separated by ;>
                      set search path for bootstrap classes and resources
-Xbootclasspath/a:<directories and zip/jar files separated by ;>
                      append to end of bootstrap class path
-Xbootclasspath/p:<directories and zip/jar files separated by ;>
                      prepend in front of bootstrap class path
-Xdiag            show additional diagnostic messages
-Xnoclassgc       disable class garbage collection
-Xincgc           enable incremental garbage collection
-Xloggc:<file>    log GC status to a file with time stamps
-Xbatch           disable background compilation
-Xms<size>        set initial Java heap size.........................
-Xmx<size>        set maximum Java heap size.........................
-Xss<size>        set java thread stack size
-Xprof            output cpu profiling data
-Xfuture          enable strictest checks, anticipating future default
-Xrs              reduce use of OS signals by Java/VM (see documentation)
-Xcheck:jni       perform additional checks for JNI functions
-Xshare:off       do not attempt to use shared class data
-Xshare:auto      use shared class data if possible (default)
-Xshare:on        require using shared class data, otherwise fail.
-XshowSettings    show all settings and continue
-XshowSettings:all         show all settings and continue
-XshowSettings:vm          show all vm related settings and continue
-XshowSettings:properties  show all property settings and continue
-XshowSettings:locale      show all locale related settings and continue

The -X options are non-standard and subject to change without notice.

I hope this will help you understand Xms, Xmx as well as many other things that matters the most. :)

Can I calculate z-score with R?

if x is a vector with raw scores then scale(x) is a vector with standardized scores.

Or manually: (x-mean(x))/sd(x)

System.Net.WebException: The remote name could not be resolved:

Open the hosts file located at : **C:\windows\system32\drivers\etc**.

Hosts file is for what?

Add the following at end of this file :

YourServerIP YourDNS

Example:

198.168.1.1 maps.google.com

Why should I use the keyword "final" on a method parameter in Java?

Since Java passes copies of arguments I feel the relevance of final is rather limited. I guess the habit comes from the C++ era where you could prohibit reference content from being changed by doing a const char const *. I feel this kind of stuff makes you believe the developer is inherently stupid as f*** and needs to be protected against truly every character he types. In all humbleness may I say, I write very few bugs even though I omit final (unless I don't want someone to override my methods and classes). Maybe I'm just an old-school dev.

How can I get the size of an std::vector as an int?

In the first two cases, you simply forgot to actually call the member function (!, it's not a value) std::vector<int>::size like this:

#include <vector>

int main () {
    std::vector<int> v;
    auto size = v.size();
}

Your third call

int size = v.size();

triggers a warning, as not every return value of that function (usually a 64 bit unsigned int) can be represented as a 32 bit signed int.

int size = static_cast<int>(v.size());

would always compile cleanly and also explicitly states that your conversion from std::vector::size_type to int was intended.

Note that if the size of the vector is greater than the biggest number an int can represent, size will contain an implementation defined (de facto garbage) value.

How to take backup of a single table in a MySQL database?

Dump and restore a single table from .sql

Dump

mysqldump db_name table_name > table_name.sql

Dumping from a remote database

mysqldump -u <db_username> -h <db_host> -p db_name table_name > table_name.sql

For further reference:

http://www.abbeyworkshop.com/howto/lamp/MySQL_Export_Backup/index.html

Restore

mysql -u <user_name> -p db_name
mysql> source <full_path>/table_name.sql

or in one line

mysql -u username -p db_name < /path/to/table_name.sql


Dump and restore a single table from a compressed (.sql.gz) format

Credit: John McGrath

Dump

mysqldump db_name table_name | gzip > table_name.sql.gz

Restore

gunzip < table_name.sql.gz | mysql -u username -p db_name

No module named setuptools

For ubuntu users, this error may arise because setuptool is not installed system-wide. Simply install setuptool using the command:

sudo apt-get install -y python-setuptools

For python3:

sudo apt-get install -y python3-setuptools

After that, install your package again normally, using

sudo python setup.py install

That's all.

Updates were rejected because the tip of your current branch is behind its remote counterpart

It must be because of commit is ahead of your current push.

  1. git pull origin "name of branch you want to push"
  2. git rebase

If git rebase is successful, then good. Otherwise, you have resolve all merge conflicts locally and keep it continuing until rebase with remote is successful.

  1. git rebase --continue

Amazon S3 upload file and get URL

Below method uploads file in a particular folder in a bucket and return the generated url of the file uploaded.

private String uploadFileToS3Bucket(final String bucketName, final File file) {
    final String uniqueFileName = uploadFolder + "/" + file.getName();
    LOGGER.info("Uploading file with name= " + uniqueFileName);
    final PutObjectRequest putObjectRequest = new PutObjectRequest(bucketName, uniqueFileName, file);
    amazonS3.putObject(putObjectRequest);
    return ((AmazonS3Client) amazonS3).getResourceUrl(bucketName, uniqueFileName);
}

TypeError: $ is not a function WordPress

Other than noConflict, this is helpful too:

(function( $ ) {
    // Variables and DOM Caching using $.
    var body = $('body');
    console.log(body);
})( jQuery );

Intellij JAVA_HOME variable

In my case I needed a lower JRE, so I had to tell IntelliJ to use a different one in "Platform Settings"

  • Platform Settings > SDKs ( +; )
  • Click the + button to add a new SDK (or rename and load an existing one)
  • Choose the /Contents/Home directory from the appropriate SDK
    (i.e. /Library/Java/JavaVirtualMachines/jdk1.8.0_45.jdk/Contents/Home)

jQuery select change event get selected option

You can use the jQuery find method

 $('select').change(function () {
     var optionSelected = $(this).find("option:selected");
     var valueSelected  = optionSelected.val();
     var textSelected   = optionSelected.text();
 });

The above solution works perfectly but I choose to add the following code for them willing to get the clicked option. It allows you get the selected option even when this select value has not changed. (Tested with Mozilla only)

    $('select').find('option').click(function () {
     var optionSelected = $(this);
     var valueSelected  = optionSelected.val();
     var textSelected   = optionSelected.text();
   });

Python 3 Float Decimal Points/Precision

Try to understand through this below function using python3

def floating_decimals(f_val, dec):
    prc = "{:."+str(dec)+"f}" #first cast decimal as str
    print(prc) #str format output is {:.3f}
    return prc.format(f_val)


print(floating_decimals(50.54187236456456564, 3))

Output is : 50.542

Hope this helps you!

Unloading classes in java?

You can unload a ClassLoader but you cannot unload specific classes. More specifically you cannot unload classes created in a ClassLoader that's not under your control.

If possible, I suggest using your own ClassLoader so you can unload.

curl usage to get header

curl --head https://www.example.net

I was pointed to this by curl itself; when I issued the command with -X HEAD, it printed:

Warning: Setting custom HTTP method to HEAD with -X/--request may not work the 
Warning: way you want. Consider using -I/--head instead.

Show space, tab, CRLF characters in editor of Visual Studio

To see the CRLF you can try this extension: End of the Line

It works for VS2012+

Highlighting Text Color using Html.fromHtml() in Android?

This can be achieved using a Spannable String. You will need to import the following

import android.text.SpannableString; 
import android.text.style.BackgroundColorSpan; 
import android.text.style.StyleSpan;

And then you can change the background of the text using something like the following:

TextView text = (TextView) findViewById(R.id.text_login);
text.setText("");
text.append("Add all your funky text in here");
Spannable sText = (Spannable) text.getText();
sText.setSpan(new BackgroundColorSpan(Color.RED), 1, 4, 0);

Where this will highlight the charecters at pos 1 - 4 with a red color. Hope this helps!

How to get the mouse position without events (without moving the mouse)?

@Tim Down's answer is not performant if you render 2,000 x 2,000 <a> elements:

OK, I have just thought of a way. Overlay your page with a div that covers the whole document. Inside that, create (say) 2,000 x 2,000 elements (so that the :hover pseudo-class will work in IE 6, see), each 1 pixel in size. Create a CSS :hover rule for those elements that changes a property (let's say font-family). In your load handler, cycle through each of the 4 million elements, checking currentStyle / getComputedStyle() until you find the one with the hover font. Extrapolate back from this element to get the co-ordinates within the document.

N.B. DON'T DO THIS.

But you don't have to render 4 million elements at once, instead use binary search. Just use 4 <a> elements instead:

  • Step 1: Consider the whole screen as the starting search area
  • Step 2: Split the search area into 2 x 2 = 4 rectangle <a> elements
  • Step 3: Using the getComputedStyle() function determine in which rectangle mouse hovers
  • Step 4: Reduce the search area to that rectangle and repeat from step 2.

This way you would need to repeat these steps max 11 times, considering your screen is not wider than 2048px.

So you will generate max 11 x 4 = 44 <a> elements.

If you don't need to determine the mouse position exactly to a pixel, but say 10px precision is OK. You would repeat the steps at most 8 times, so you would need to draw max 8 x 4 = 32 <a> elements.

Also generating and then destroying the <a> elements is not performat as DOM is generally slow. Instead, you can just reuse the initial 4 <a> elements and just adjust their top, left, width and height as you loop through steps.

Now, creating 4 <a> is an overkill as well. Instead, you can reuse the same one <a> element for when testing for getComputedStyle() in each rectangle. So, instead of splitting the search area into 2 x 2 <a> elements just reuse a single <a> element by moving it with top and left style properties.

So, all you need is a single <a> element change its width and height max 11 times, and change its top and left max 44 times and you will have the exact mouse position.

Javascript Iframe innerHTML

Conroy's answer was right. In the case you need only stuff from body tag, just use:

$('#my_iframe').contents().find('body').html();

bodyParser is deprecated express 4

What is your opinion to use express-generator it will generate skeleton project to start with, without deprecated messages appeared in your log

run this command

npm install express-generator -g

Now, create new Express.js starter application by type this command in your Node projects folder.

express node-express-app

That command tell express to generate new Node.js application with the name node-express-app.

then Go to the newly created project directory, install npm packages and start the app using the command

cd node-express-app && npm install && npm start

How to copy a file to another path?

string directoryPath = Path.GetDirectoryName(destinationFileName);

// If directory doesn't exist create one
if (!Directory.Exists(directoryPath))
{
DirectoryInfo di = Directory.CreateDirectory(directoryPath);
}

File.Copy(sourceFileName, destinationFileName);

Copy data into another table

Try this:

INSERT INTO MyTable1 (Col1, Col2, Col4)
   SELECT Col1, Col2, Col3 FROM MyTable2

What is the role of the package-lock.json?

package-lock.json is written to when a numerical value in a property such as the "version" property, or a dependency property is changed in package.json.

If these numerical values in package.json and package-lock.json match, package-lock.json is read from.

If these numerical values in package.json and package-lock.json do not match, package-lock.json is written to with those new values, and new modifiers such as the caret and tilde if they are present. But it is the numeral that is triggering the change to package-lock.json.

To see what I mean, do the following. Using package.json without package-lock.json, run npm install with:

{
  "name": "test",
  "version": "1.0.0",
  ...
  "devDependencies": {
    "sinon": "7.2.2"
  }
}

package-lock.json will now have:

"sinon": {
  "version": "7.2.2",

Now copy/paste both files to a new directory. Change package.json to (only adding caret):

{
  "name": "test",
  "version": "1.0.0",
  ...
  "devDependencies": {
    "sinon": "^7.2.2"
  }
}

run npm install. If there were no package-lock.json file, [email protected] would be installed. npm install is reading from package-lock.json and installing 7.2.2.

Now change package.json to:

{
  "name": "test",
  "version": "1.0.0",
  ...
  "devDependencies": {
    "sinon": "^7.3.0"
  }
}

run npm install. package-lock.json has been written to, and will now show:

"sinon": {
  "version": "^7.3.0",

How do you copy a record in a SQL table but swap out the unique id of the new row?

Ok, I know that it's an old issue but I post my answer anyway.

I like this solution. I only have to specify the identity column(s).

SELECT * INTO TempTable FROM MyTable_T WHERE id = 1;
ALTER TABLE TempTable DROP COLUMN id;
INSERT INTO MyTable_T SELECT * FROM TempTable;
DROP TABLE TempTable;

The "id"-column is the identity column and that's the only column I have to specify. It's better than the other way around anyway. :-)

I use SQL Server. You may want to use "CREATE TABLE" and "UPDATE TABLE" at row 1 and 2. Hmm, I saw that I did not really give the answer that he wanted. He wanted to copy the id to another column also. But this solution is nice for making a copy with a new auto-id.

I edit my solution with the idéas from Michael Dibbets.

use MyDatabase; 
SELECT * INTO #TempTable FROM [MyTable] WHERE [IndexField] = :id;
ALTER TABLE #TempTable DROP COLUMN [IndexField]; 
INSERT INTO [MyTable] SELECT * FROM #TempTable; 
DROP TABLE #TempTable;

You can drop more than one column by separating them with a ",". The :id should be replaced with the id of the row you want to copy. MyDatabase, MyTable and IndexField should be replaced with your names (of course).

How can I make robocopy silent in the command line except for progress?

If you want no output at all this is the most simple way:

robocopy src dest > nul

If you still need some information and only want to strip parts of the output, use the parameters from R.Koene's answer.

javax.xml.bind.UnmarshalException: unexpected element (uri:"", local:"Group")

After looking more, the root element has to be associated with a schema-namespace as Blaise is noting. Yet, I didnt have a package-info java. So without using the @XMLSchema annotation, I was able to correct this issue by using

@XmlRootElement (name="RetrieveMultipleSetsResponse", namespace = XMLCodeTable.NS1)
@XmlType(name = "ns0", namespace = XMLCodeTable.NS1)
@XmlAccessorType(XmlAccessType.NONE)
public class RetrieveMultipleSetsResponse {//...}

Hope this helps!

Ubuntu apt-get unable to fetch packages

I tried this really interesting solution today, which worked for me on an Ubuntu server. Some DNS or another issue in the apt was making it adamant to not installing some packages from a custom PPA. What I did was install the apt-fast package and use it to install my packages instead of apt.

apt-fast is an alternative to apt which works on top of apt but uses aria2c to download packages. It is used to increase the download speed. In my case, it also solved whatever network problem was making apt to fail.

Using it is exactly the same as apt:

sudo apt-fast install package-name

How to set limits for axes in ggplot2 R plots?

Quick note: if you're also using coord_flip() to flip the x and the y axis, you won't be able to set range limits using coord_cartesian() because those two functions are exclusive (see here).

Fortunately, this is an easy fix; set your limits within coord_flip() like so:

p + coord_flip(ylim = c(3,5), xlim = c(100, 400))

This just alters the visible range (i.e. doesn't remove data points).

Get all table names of a particular database by SQL query?

In order if someone would like to list all tables within specific database without using the "use" keyword:

SELECT TABLE_NAME FROM databasename.INFORMATION_SCHEMA.TABLES

How to run JUnit test cases from the command line

With JUnit 4.12 the following didn't work for me:

java -cp .:/usr/share/java/junit.jar org.junit.runner.JUnitCore [test class name]

Apparently, from JUnit 4.11 onwards you should also include hamcrest-core.jar in your classpath:

java -cp .:/usr/share/java/junit.jar:/usr/share/java/hamcrest-core.jar org.junit.runner.JUnitCore [test class name]

SOAP Action WSDL

We put together Web Services on Windows Server and were trying to connect with PHP on Apache. We got the same error. The issue ended up being different versions of the Soap client on the different servers. Matching the SOAP versions in the options on both servers solved the issue in our case.

Passing parameter to controller action from a Html.ActionLink

You are using incorrect overload. You should use this overload

public static MvcHtmlString ActionLink(
    this HtmlHelper htmlHelper,
    string linkText,
    string actionName,
    string controllerName,
    Object routeValues,
    Object htmlAttributes
) 

And the correct code would be

<%= Html.ActionLink("Create New Part", "CreateParts", "PartList", new { parentPartId = 0 }, null)%>

Note that extra parameter at the end. For the other overloads, visit LinkExtensions.ActionLink Method. As you can see there is no string, string, string, object overload that you are trying to use.

How to Force New Google Spreadsheets to refresh and recalculate?

Old question ... nonetheless, just add a checkbox somewhere in the sheet. Checking or unchecking it will refresh the cell formulae.

How to play an android notification sound

If anyone's still looking for a solution to this, I found an answer at How to play ringtone/alarm sound in Android

try {
    Uri notification = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
    Ringtone r = RingtoneManager.getRingtone(getApplicationContext(), notification);
    r.play();
} catch (Exception e) {
    e.printStackTrace();
}

You can change TYPE_NOTIFICATION to TYPE_ALARM, but you'll want to keep track of your Ringtone r in order to stop playing it... say, when the user clicks a button or something.

Error: Failed to execute 'appendChild' on 'Node': parameter 1 is not of type 'Node'

In my case, there was no string on which i was calling appendChild, the object i was passing on appendChild argument was wrong, it was an array and i had pass an element object, so i used divel.appendChild(childel[0]) instead of divel.appendChild(childel) and it worked. Hope it help someone.

Pass multiple values with onClick in HTML link

A few things here...

If you want to call a function when the onclick event happens, you'll just want the function name plus the parameters.

Then if your parameters are a variable (which they look like they are), then you won't want quotes around them. Not only that, but if these are global variables, you'll want to add in "window." before that, because that's the object that holds all global variables.

Lastly, if these parameters aren't variables, you'll want to exclude the slashes to escape those characters. Since the value of onclick is wrapped by double quotes, single quotes won't be an issue. So your answer will look like this...

<a href=# onclick="ReAssign('valuationId', window.user)">Re-Assign</a>

There are a few extra things to note here, if you want more than a quick solution.

You looked like you were trying to use the + operator to combine strings in HTML. HTML is a scripting language, so when you're writing it, the whole thing is just a string itself. You can just skip these from now on, because it's not code your browser will be running (just a whole bunch of stuff, and anything that already exists is what has special meaning by the browser).

Next, you're using an anchor tag/link that doesn't actually take the user to another website, just runs some code. I'd use something else other than an anchor tag, with the appropriate CSS to format it to look the way you want. It really depends on the setting, but in many cases, a span tag will do. Give it a class (like class="runjs") and have a rule of CSS for that. To get it to imitate a link's behavior, use this:

.runjs {
    cursor: pointer;
    text-decoration: underline;
    color: blue;
}

This lets you leave out the href attribute which you weren't using anyways.

Last, you probably want to use JavaScript to set the value of this link's onclick attribute instead of hand writing it. It keeps your page cleaner by keeping the code of your page separate from what the structure of your page. In your class, you could change all these links like this...

var links = document.getElementsByClassName('runjs');
for(var i = 0; i < links.length; i++)
    links[i].onclick = function() { ReAssign('valuationId', window.user); };

While this won't work in some older browsers (because of the getElementsByClassName method), it's just three lines and does exactly what you're looking for. Each of these links has an anonymous function tied to them meaning they don't have any variable tied to them except that tag's onclick value. Plus if you wanted to, you could include more lines of code this way, all grouped up in one tidy location.

std::thread calling method of class

Not so hard:

#include <thread>

void Test::runMultiThread()
{
    std::thread t1(&Test::calculate, this,  0, 10);
    std::thread t2(&Test::calculate, this, 11, 20);
    t1.join();
    t2.join();
}

If the result of the computation is still needed, use a future instead:

#include <future>

void Test::runMultiThread()
{
     auto f1 = std::async(&Test::calculate, this,  0, 10);
     auto f2 = std::async(&Test::calculate, this, 11, 20);

     auto res1 = f1.get();
     auto res2 = f2.get();
}

UL list style not applying

Make sure the 'li' doesn't have overflow: hidden applied.

Show and hide a View with a slide up/down animation

I was having troubles understanding an applying the accepted answer. I needed a little more context. Now that I have figured it out, here is a full example:

enter image description here

MainActivity.java

public class MainActivity extends AppCompatActivity {

    Button myButton;
    View myView;
    boolean isUp;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        myView = findViewById(R.id.my_view);
        myButton = findViewById(R.id.my_button);

        // initialize as invisible (could also do in xml)
        myView.setVisibility(View.INVISIBLE);
        myButton.setText("Slide up");
        isUp = false;
    }

    // slide the view from below itself to the current position
    public void slideUp(View view){
        view.setVisibility(View.VISIBLE);
        TranslateAnimation animate = new TranslateAnimation(
                0,                 // fromXDelta
                0,                 // toXDelta
                view.getHeight(),  // fromYDelta
                0);                // toYDelta
        animate.setDuration(500);
        animate.setFillAfter(true);
        view.startAnimation(animate);
    }

    // slide the view from its current position to below itself
    public void slideDown(View view){
        TranslateAnimation animate = new TranslateAnimation(
                0,                 // fromXDelta
                0,                 // toXDelta
                0,                 // fromYDelta
                view.getHeight()); // toYDelta
        animate.setDuration(500);
        animate.setFillAfter(true);
        view.startAnimation(animate);
    }

    public void onSlideViewButtonClick(View view) {
        if (isUp) {
            slideDown(myView);
            myButton.setText("Slide up");
        } else {
            slideUp(myView);
            myButton.setText("Slide down");
        }
        isUp = !isUp;
    }
}

activity_mail.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.slideview.MainActivity">

    <Button
        android:id="@+id/my_button"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="100dp"
        android:onClick="onSlideViewButtonClick"
        android:layout_width="150dp"
        android:layout_height="wrap_content"/>

    <LinearLayout
        android:id="@+id/my_view"
        android:background="#a6e1aa"
        android:orientation="vertical"
        android:layout_alignParentBottom="true"
        android:layout_width="match_parent"
        android:layout_height="200dp">

    </LinearLayout>

</RelativeLayout>

Notes

  • Thanks to this article for pointing me in the right direction. It was more helpful than the other answers on this page.
  • If you want to start with the view on screen, then don't initialize it as INVISIBLE.
  • Since we are animating it completely off screen, there is no need to set it back to INVISIBLE. If you are not animating completely off screen, though, then you can add an alpha animation and set the visibility with an AnimatorListenerAdapter.
  • Property Animation docs

How to determine the current language of a wordpress page when using polylang?

To show current language, you can use:

 <?php echo $lang=get_bloginfo("language"); ?>

Plain and simple

The CodeDom provider type "Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider" could not be located

ASP.NET does not search bin/debug or any subfolder under bin for assemblies like other types of applications do. You can instruct the runtime to look in a different place using the following configuration:

<configuration>
   <runtime>   
      <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
         <probing privatePath="bin;bin\Debug;bin\Release"/>
      </assemblyBinding>
   </runtime>   
</configuration>

Can I read the hash portion of the URL on my server-side application (PHP, Ruby, Python, etc.)?

Another solution is to add a hidden input field to the php page:

<input type="hidden" id="myHiddenLocationHash" name="myHiddenLocationHash" value="">

Using javascript/jQuery you can set the value of this field on the page load or responding to an event :

$('#myHiddenLocationHash').val(document.location.hash.replace('#',''));

In php on the server side you can read this value using the $_POST collection:

$server_location_hash = $_POST['myHiddenLocationHash'];

SQL Error: 0, SQLState: 08S01 Communications link failure

I'm answering on specific to this error code(08s01).

usually, MySql close socket connections are some interval of time that is wait_timeout defined on MySQL server-side which by default is 8hours. so if a connection will timeout after this time and the socket will throw an exception which SQLState is "08s01".

1.use connection pool to execute Query, make sure the pool class has a function to make an inspection of the connection members before it goes time_out.

2.give a value of <wait_timeout> greater than the default, but the largest value is 24 days

3.use another parameter in your connection URL, but this method is not recommended, and maybe deprecated.

Get first row of dataframe in Python Pandas based on criteria

For existing matches, use query:

df.query(' A > 3' ).head(1)
Out[33]: 
   A  B  C
2  4  6  3

df.query(' A > 4 and B > 3' ).head(1)
Out[34]: 
   A  B  C
4  5  4  5

df.query(' A > 3 and (B > 3 or C > 2)' ).head(1)
Out[35]: 
   A  B  C
2  4  6  3

Start script missing error when running npm start

I had this issue while installing react-js for the first time : These line helped me solve the issue:

npm rm -g create-react-app
npm install -g create-react-app
npx create-react-app my-app

source: https://stackoverflow.com/a/59260128/11652661

Open a facebook link by native Facebook app on iOS

2020 answer

Just open the url. Facebook automatically registers for deep links.

let url = URL(string:"https://www.facebook.com/TheGoodLordAbove")!
UIApplication.shared.open(url,completionHandler:nil)

this opens in the facebook app if installed, and in your default browser otherwise

Changing the size of a column referenced by a schema-bound view in SQL Server

here is what works with the version of the program that I'm using: may work for you too.

I will just place the instruction and command that does it. class is the name of the table. you change it in the table its self with this method. not just the return on the search process.


view the table class

select * from class

change the length of the columns FacID (seen as "faci") and classnumber (seen as "classnu") to fit the whole labels.

alter table class modify facid varchar (5);

alter table class modify classnumber varchar(11);

view table again to see the difference

select * from class;

(run the command again to see the difference)


This changes the the actual table for good, but for better.

P.S. I made these instructions up as a note for the commands. This is not a test, but can help on one :)

SMTP connect() failed PHPmailer - PHP

You are missing the directive that states the connection uses SSL

require ("class.phpmailer.php");
$mail = new PHPMailer();
$mail->IsSMTP(); 
$mail->SMTPAuth = true;     // turn of SMTP authentication
$mail->Username = "YAHOO ACCOUNT";  // SMTP username
$mail->Password = "YAHOO ACCOUNT PASSWORD"; // SMTP password
$mail->SMTPSecure = "ssl";
$mail->Host = "YAHOO HOST"; // SMTP host
$mail->Port = 465;

Then add in the other parts

$webmaster_email = "[email protected]";       //Reply to this email ID
$email="[email protected]";                // Recipients email ID
$name="My Name";                              // Recipient's name
$mail->From = $webmaster_email;
$mail->FromName = "My Name";
$mail->AddAddress($email,$name);
$mail->AddReplyTo($webmaster_email,"My Name");
$mail->WordWrap = 50;                         // set word wrap
$mail->IsHTML(true);                          // send as HTML
$mail->Subject = "subject";
$mail->Body = "Hi,
This is the HTML BODY ";                      //HTML Body 
$mail->AltBody = "This is the body when user views in plain text format"; //Text Body 

if(!$mail->Send())
{
echo "Mailer Error: " . $mail->ErrorInfo;
}
else
{
echo "Message has been sent";
}

As a side note, I have had trouble using Body + AltBody together although they are supposed to work. As a result, I wrote the following wrapper function which works perfectly.

<?php
require ("class.phpmailer.php");

// Setup Configuration for Mail Server Settings
$email['host']          = 'smtp.email.com';
$email['port']          = 366;
$email['user']          = '[email protected]';
$email['pass']          = 'from password';
$email['from']          = 'From Name';
$email['reply']         = '[email protected]';
$email['replyname']     = 'Reply To Name';

$addresses_to_mail_to = '[email protected];[email protected]';
$email_subject = 'My Subject';
$email_body = '<html>Code Here</html>';
$who_is_receiving_name = 'John Smith';

$result = sendmail(
    $email_body,
    $email_subject,
    $addresses_to_mail_to,
    $who_is_receiving_name
);

var_export($result);


function sendmail($body, $subject, $to, $name, $attach = "") {

  global $email;
  $return = false;

  $mail = new PHPMailer(true); // the true param means it will throw exceptions on errors, which we need to catch
  $mail->IsSMTP(); // telling the class to use SMTP
  try {
    $mail->Host       = $email['host']; // SMTP server
//    $mail->SMTPDebug  = 2;                     // enables SMTP debug information (for testing)
    $mail->SMTPAuth   = true;                  // enable SMTP authentication
    $mail->Host       = $email['host']; // sets the SMTP server
    $mail->Port       = $email['port'];                    // set the SMTP port for the GMAIL server
    $mail->SMTPSecure = "tls";
    $mail->Username   = $email['user']; // SMTP account username
    $mail->Password   = $email['pass'];        // SMTP account password
    $mail->AddReplyTo($email['reply'], $email['replyname']);
    if(stristr($to,';')) {
      $totmp = explode(';',$to);
      foreach($totmp as $destto) {
        if(trim($destto) != "") {
          $mail->AddAddress(trim($destto), $name);
        }
      }
    } else {
      $mail->AddAddress($to, $name);
    }
    $mail->SetFrom($email['user'], $email['from']);
    $mail->Subject = $subject;
    $mail->AltBody = 'To view the message, please use an HTML compatible email viewer!'; // optional - MsgHTML will create an alternate automatically
    $mail->MsgHTML($body);
    if(is_array($attach)) {
        foreach($attach as $attach_f) {
            if($attach_f != "") {
              $mail->AddAttachment($attach_f);      // attachment
            }
        }
    } else {
        if($attach != "") {
          $mail->AddAttachment($attach);      // attachment
        }
    }
    $mail->Send();
  } catch (phpmailerException $e) {
    $return = $e->errorMessage();
  } catch (Exception $e) {
    $return = $e->errorMessage();
  }

  return $return;
}

Specifying Font and Size in HTML table

Enclose your code with the html and body tags. Size attribute does not correspond to font-size and it looks like its domain does not go beyond value 7. Furthermore font tag is not supported in HTML5. Consider this code for your case

<!DOCTYPE html>
<html>
<body>

<font size="2" face="Courier New" >
<table width="100%">
    <tr>
        <td><b>Client</b></td>
        <td><b>InstanceName</b></td>
        <td><b>dbname</b></td>
        <td><b>Filename</b></td>
        <td><b>KeyName</b></td>
        <td><b>Rotation</b></td>
        <td><b>Path</b></td>
    </tr>
    <tr>
        <td>NEWDEV6</td>
        <td>EXPRESS2012</td>
        <td>master</td><td>master.mdf</td>
        <td>test_key_16</td><td>0</td>
        <td>d:\Program&nbsp;Files\Microsoft&nbsp;SQL&nbsp;Server\MSSQL11.EXPRESS2012\MSSQL\DATA\master.mdf</td>
    </tr>
</table>
</font>
<font size="5" face="Courier New" >
<table width="100%">
    <tr>
        <td><b>Client</b></td>
        <td><b>InstanceName</b></td>
        <td><b>dbname</b></td>
        <td><b>Filename</b></td>
        <td><b>KeyName</b></td>
        <td><b>Rotation</b></td>
        <td><b>Path</b></td></tr>
    <tr>
        <td>NEWDEV6</td>
        <td>EXPRESS2012</td>
        <td>master</td>
        <td>master.mdf</td>
        <td>test_key_16</td>
        <td>0</td>
        <td>d:\Program&nbsp;Files\Microsoft&nbsp;SQL&nbsp;Server\MSSQL11.EXPRESS2012\MSSQL\DATA\master.mdf</td></tr>
</table></font>
</body>
</html>

How to fix the session_register() deprecated issue?

if you need a fallback function you could use this

function session_register($name){
    global $$name;
    $_SESSION[$name] = $$name;
    $$name = &$_SESSION[$name]; 
}

pandas: to_numeric for multiple columns

If you are looking for a range of columns, you can try this:

df.iloc[7:] = df.iloc[7:].astype(float)

The examples above will convert type to be float, for all the columns begin with the 7th to the end. You of course can use different type or different range.

I think this is useful when you have a big range of columns to convert and a lot of rows. It doesn't make you go over each row by yourself - I believe numpy do it more efficiently.

This is useful only if you know that all the required columns contain numbers only - it will not change "bad values" (like string) to be NaN for you.

How to include a class in PHP

Your code should be something like

require_once('class.twitter.php');

$t = new twitter;
$t->username = 'user';
$t->password = 'password';

$data = $t->publicTimeline();

Is there a way to use max-width and height for a background image?

Unfortunately there's no min (or max)-background-size in CSS you can only use background-size. However if you are seeking a responsive background image you can use Vmin and Vmaxunits for the background-size property to achieve something similar.

example:

#one {
    background:url('../img/blahblah.jpg') no-repeat;
    background-size:10vmin 100%;
}

that will set the height to 10% of the whichever smaller viewport you have whether vertical or horizontal, and will set the width to 100%.

Read more about css units here: https://www.w3schools.com/cssref/css_units.asp

Array inside a JavaScript Object?

// define
var foo = {
  bar: ['foo', 'bar', 'baz']
};

// access
foo.bar[2]; // will give you 'baz'

How to read PDF files using Java?

with Apache PDFBox it goes like this:

PDDocument document = PDDocument.load(new File("test.pdf"));
if (!document.isEncrypted()) {
    PDFTextStripper stripper = new PDFTextStripper();
    String text = stripper.getText(document);
    System.out.println("Text:" + text);
}
document.close();

CMD: How do I recursively remove the "Hidden"-Attribute of files and directories

You can't remove hidden without also removing system.

You want:

cd mydir
attrib -H -S /D /S

That will remove the hidden and system attributes from all the files/folders inside of your current directory.

How to resize Twitter Bootstrap modal dynamically based on the content

Mine Solution was just to add below style. <div class="modal-body" style="clear: both;overflow: hidden;">

javax.persistence.NoResultException: No entity found for query

You mentioned getting the result list from the Query, since you don't know that there is a UniqueResult (hence the exception) you could use list and check the size?

if (query.list().size() == 1) 

Since you're not doing a get() to get your unique object a query will be executed whether you call uniqueResult or list.

Adjust UILabel height depending on the text

Thanks for this post. It helped me a great deal. In my case I am also editing the text in a separate view controller. I noticed that when I use:

[cell.contentView addSubview:cellLabel];

in the tableView:cellForRowAtIndexPath: method that the label view was continually rendered over the top of the previous view each time I edited the cell. The text became pixelated, and when something was deleted or changed, the previous version was visible under the new version. Here's how I solved the problem:

if ([[cell.contentView subviews] count] > 0) {
    UIView *test = [[cell.contentView subviews] objectAtIndex:0];
    [test removeFromSuperview];
}
[cell.contentView insertSubview:cellLabel atIndex:0];

No more weird layering. If there is a better way to handle this, Please let me know.

Android Starting Service at Boot Time , How to restart service class after device Reboot?

First register a receiver in your manifest.xml file:

    <receiver android:name="com.mileagelog.service.Broadcast_PowerUp" >
        <intent-filter>
            <action android:name="android.intent.action.ACTION_POWER_CONNECTED" />
            <action android:name="android.intent.action.ACTION_POWER_DISCONNECTED" />
        </intent-filter>
    </receiver>

and then write a broadcast for this receiver like:

public class Broadcast_PowerUp extends BroadcastReceiver {

  @Override
  public void onReceive(Context context, Intent intent) {
    String action = intent.getAction();

    if (action.equals(Intent.ACTION_POWER_CONNECTED)) {
        Toast.makeText(context, "Service_PowerUp Started",
                Toast.LENGTH_LONG).show();


    } else if (action.equals(Intent.ACTION_POWER_DISCONNECTED)) {



        Toast.makeText(context, "Service_PowerUp Stoped", Toast.LENGTH_LONG)
        .show();
    }
  }
}

Change the default base url for axios

From axios docs you have baseURL and url

baseURL will be prepended to url when making requests. So you can define baseURL as http://127.0.0.1:8000 and make your requests to /url

 // `url` is the server URL that will be used for the request
 url: '/user',

 // `baseURL` will be prepended to `url` unless `url` is absolute.
 // It can be convenient to set `baseURL` for an instance of axios to pass relative URLs
 // to methods of that instance.
 baseURL: 'https://some-domain.com/api/',

Gson: Directly convert String to JsonObject (no POJO)

The simplest way is to use the JsonPrimitive class, which derives from JsonElement, as shown below:

JsonElement element = new JsonPrimitive(yourString);
JsonObject result = element.getAsJsonObject();

How to extend available properties of User.Identity

I also had added on or extended additional columns into my AspNetUsers table. When I wanted to simply view this data I found many examples like the code above with "Extensions" etc... This really amazed me that you had to write all those lines of code just to get a couple values from the current users.

It turns out that you can query the AspNetUsers table like any other table:

 ApplicationDbContext db = new ApplicationDbContext();
 var user = db.Users.Where(x => x.UserName == User.Identity.Name).FirstOrDefault();

How to store arrays in MySQL?

The proper way to do this is to use multiple tables and JOIN them in your queries.

For example:

CREATE TABLE person (
`id` INT NOT NULL PRIMARY KEY,
`name` VARCHAR(50)
);

CREATE TABLE fruits (
`fruit_name` VARCHAR(20) NOT NULL PRIMARY KEY,
`color` VARCHAR(20),
`price` INT
);

CREATE TABLE person_fruit (
`person_id` INT NOT NULL,
`fruit_name` VARCHAR(20) NOT NULL,
PRIMARY KEY(`person_id`, `fruit_name`)
);

The person_fruit table contains one row for each fruit a person is associated with and effectively links the person and fruits tables together, I.E.

1 | "banana"
1 | "apple"
1 | "orange"
2 | "straberry"
2 | "banana"
2 | "apple"

When you want to retrieve a person and all of their fruit you can do something like this:

SELECT p.*, f.*
FROM person p
INNER JOIN person_fruit pf
ON pf.person_id = p.id
INNER JOIN fruits f
ON f.fruit_name = pf.fruit_name

Difference between 'struct' and 'typedef struct' in C++?

In C++, there is only a subtle difference. It's a holdover from C, in which it makes a difference.

The C language standard (C89 §3.1.2.3, C99 §6.2.3, and C11 §6.2.3) mandates separate namespaces for different categories of identifiers, including tag identifiers (for struct/union/enum) and ordinary identifiers (for typedef and other identifiers).

If you just said:

struct Foo { ... };
Foo x;

you would get a compiler error, because Foo is only defined in the tag namespace.

You'd have to declare it as:

struct Foo x;

Any time you want to refer to a Foo, you'd always have to call it a struct Foo. This gets annoying fast, so you can add a typedef:

struct Foo { ... };
typedef struct Foo Foo;

Now struct Foo (in the tag namespace) and just plain Foo (in the ordinary identifier namespace) both refer to the same thing, and you can freely declare objects of type Foo without the struct keyword.


The construct:

typedef struct Foo { ... } Foo;

is just an abbreviation for the declaration and typedef.


Finally,

typedef struct { ... } Foo;

declares an anonymous structure and creates a typedef for it. Thus, with this construct, it doesn't have a name in the tag namespace, only a name in the typedef namespace. This means it also cannot be forward-declared. If you want to make a forward declaration, you have to give it a name in the tag namespace.


In C++, all struct/union/enum/class declarations act like they are implicitly typedef'ed, as long as the name is not hidden by another declaration with the same name. See Michael Burr's answer for the full details.

why numpy.ndarray is object is not callable in my simple for python loop

The error TypeError: 'numpy.ndarray' object is not callable means that you tried to call a numpy array as a function.

Use

Z=XY[0]+XY[1]

Instead of

Z=XY(i,0)+XY(i,1)

<code> vs <pre> vs <samp> for inline and block code snippets

Use <code> for inline code that can wrap and <pre><code> for block code that must not wrap. <samp> is for sample output, so I would avoid using it to represent sample code (which the reader is to input). This is what Stack Overflow does.

(Better yet, if you want easy to maintain, let the users edit the articles as Markdown, then they don’t have to remember to use <pre><code>.)

HTML5 agrees with this in “the pre element”:

The pre element represents a block of preformatted text, in which structure is represented by typographic conventions rather than by elements.

Some examples of cases where the pre element could be used:

  • Including fragments of computer code, with structure indicated according to the conventions of that language.

[…]

To represent a block of computer code, the pre element can be used with a code element; to represent a block of computer output the pre element can be used with a samp element. Similarly, the kbd element can be used within a pre element to indicate text that the user is to enter.

In the following snippet, a sample of computer code is presented.

_x000D_
_x000D_
<p>This is the <code>Panel</code> constructor:</p>
<pre><code>function Panel(element, canClose, closeHandler) {
      this.element = element;
      this.canClose = canClose;
      this.closeHandler = function () { if (closeHandler) closeHandler() };
    }</code></pre>
_x000D_
_x000D_
_x000D_

What's onCreate(Bundle savedInstanceState)

onCreate(Bundle savedInstanceState) gets called and savedInstanceState will be non-null if your Activity and it was terminated in a scenario(visual view) described above. Your app can then grab (catch) the data from savedInstanceState and regenerate your Activity

how to check if string contains '+' character

[+]is simpler

    String s = "ddjdjdj+kfkfkf";

    if(s.contains ("+"))
    {
        String parts[] = s.split("[+]");
        s =  parts[0]; // i want to strip part after  +
    }
    System.out.println(s);

error: expected unqualified-id before ‘.’ token //(struct)

ReducedForm is a type, so you cannot say

ReducedForm.iSimplifiedNumerator = iNumerator/iGreatCommDivisor;

You can only use the . operator on an instance:

ReducedForm rf;
rf.iSimplifiedNumerator = iNumerator/iGreatCommDivisor;

LoDash: Get an array of values from an array of object properties

And if you need to extract several properties from each object, then

let newArr = _.map(arr, o => _.pick(o, ['name', 'surname', 'rate']));

jQuery click event not working after adding class

on document ready event there is no a tag with class tabclick. so you have to bind click event dynamically when you are adding tabclick class. please this code:

$("a.applicationdata").click(function() {
    var appid = $(this).attr("id");

   $('#gentab a').addClass("tabclick")
    .click(function() {
          var liId = $(this).parent("li").attr("id");
         alert(liId);        
      });


 $('#gentab a').attr('href', '#datacollector');

});

What is the difference between public, private, and protected?

Reviving an old question, but I think a really good way to think of this is in terms of the API that you are defining.

  • public - Everything marked public is part of the API that anyone using your class/interface/other will use and rely on.

  • protected - Don't be fooled, this is also part of the API! People can subclass, extend your code and use anything marked protected.

  • private - Private properties and methods can be changed as much as you like. No one else can use these. These are the only things you can change without making breaking changes.

Or in Semver terms:

  • Changes to anything public or protected should be considered MAJOR changes.

  • Anything new public or protected should be (at least) MINOR

  • Only new/changes to anything private can be PATCH

So in terms of maintaining code, its good to be careful about what things you make public or protected because these are the things you are promising to your users.

JSON: why are forward slashes escaped?

The JSON spec says you CAN escape forward slash, but you don't have to.

How do I implement a callback in PHP?

You will want to verify whatever your calling is valid. For example, in the case of a specific function, you will want to check and see if the function exists:

function doIt($callback) {
    if(function_exists($callback)) {
        $callback();
    } else {
        // some error handling
    }
}

Understanding Apache's access log

I also don't under stand what the "-" means after the 200 140 section of the log

That value corresponds to the referer as described by Joachim. If you see a dash though, that means that there was no referer value to begin with (eg. the user went straight to a specific destination, like if he/she typed a URL in their browser)

Best way to remove an event handler in jQuery?

To remove ALL event-handlers, this is what worked for me:

To remove all event handlers mean to have the plain HTML structure without all the event handlers attached to the element and its child nodes. To do this, jQuery's clone() helped.

var original, clone;
// element with id my-div and its child nodes have some event-handlers
original = $('#my-div');
clone = original.clone();
//
original.replaceWith(clone);

With this, we'll have the clone in place of the original with no event-handlers on it.

Good Luck...

Creating a .dll file in C#.Net

You need to change project settings. Right click your project, go to properites. In Application tab change output type to class library instead of Windows application.

How to check if a file exists in a folder?

Use FileInfo.Exists Property:

DirectoryInfo di = new DirectoryInfo(ProcessingDirectory);
FileInfo[] TXTFiles = di.GetFiles("*.xml");
if (TXTFiles.Length == 0)
{
    log.Info("no files present")
}
foreach (var fi in TXTFiles)
    log.Info(fi.Exists);

or File.Exists Method:

string curFile = @"c:\temp\test.txt";
Console.WriteLine(File.Exists(curFile) ? "File exists." : "File does not exist.");

Javascript: Setting location.href versus location

Even if both work, I would use the latter. location is an object, and assigning a string to an object doesn't bode well for readability or maintenance.

How to get a Docker container's IP address from the host

NOTE!!! for Docker Compose Usage:

Since Docker Compose creates an isolated network for each cluster, the methods below do not work with docker-compose.


The most elegant and easy way is defining a shell function, currently the most-voted answer @WouterD's:

dockip() {
  docker inspect --format '{{ .NetworkSettings.IPAddress }}' "$@"
}

Docker can write container IDs to a file like Linux programs:

Running with --cidfile=filename, Docker dumps the ID of the container to "filename".

See "Docker runs PID equivalent Section" for more information.

--cidfile="app.cid": Write the container ID to the file

Using a PID file:

  1. Running container with --cidfile parameter, the app.cid file content is like:

    a29ac3b9f8aebf66a1ba5989186bd620ea66f1740e9fe6524351e7ace139b909
    
  2. You can use file content to inspect Docker containers:

    blog-v4 git:(develop) ? docker inspect `cat app.cid`
    
  3. You can extract the container IP using an inline Python script:

    $ docker inspect `cat app.cid` | python -c "import json;import sys;\
    sys.stdout.write(json.load(sys.stdin)[0]['NetworkSettings']['IPAddress'])"
    172.17.0.2
    

Here's a more human friendly form:

#!/usr/bin/env python
# Coding: utf-8
# Save this file like get-docker-ip.py in a folder that in $PATH
# Run it with
# $ docker inspect <CONTAINER ID> | get-docker-ip.py

import json
import sys

sys.stdout.write(json.load(sys.stdin)[0]['NetworkSettings']['IPAddress'])

See "10 alternatives of getting the Docker container IP addresses" for more information.

Python object.__repr__(self) should be an expression?

It should be a Python expression that, when eval'd, creates an object with the exact same properties as this one. For example, if you have a Fraction class that contains two integers, a numerator and denominator, your __repr__() method would look like this:

# in the definition of Fraction class
def __repr__(self):
    return "Fraction(%d, %d)" % (self.numerator, self.denominator)

Assuming that the constructor takes those two values.

Scatter plot and Color mapping in Python

Here is an example

import numpy as np
import matplotlib.pyplot as plt

x = np.random.rand(100)
y = np.random.rand(100)
t = np.arange(100)

plt.scatter(x, y, c=t)
plt.show()

Here you are setting the color based on the index, t, which is just an array of [1, 2, ..., 100]. enter image description here

Perhaps an easier-to-understand example is the slightly simpler

import numpy as np
import matplotlib.pyplot as plt

x = np.arange(100)
y = x
t = x
plt.scatter(x, y, c=t)
plt.show()

enter image description here

Note that the array you pass as c doesn't need to have any particular order or type, i.e. it doesn't need to be sorted or integers as in these examples. The plotting routine will scale the colormap such that the minimum/maximum values in c correspond to the bottom/top of the colormap.

Colormaps

You can change the colormap by adding

import matplotlib.cm as cm
plt.scatter(x, y, c=t, cmap=cm.cmap_name)

Importing matplotlib.cm is optional as you can call colormaps as cmap="cmap_name" just as well. There is a reference page of colormaps showing what each looks like. Also know that you can reverse a colormap by simply calling it as cmap_name_r. So either

plt.scatter(x, y, c=t, cmap=cm.cmap_name_r)
# or
plt.scatter(x, y, c=t, cmap="cmap_name_r")

will work. Examples are "jet_r" or cm.plasma_r. Here's an example with the new 1.5 colormap viridis:

import numpy as np
import matplotlib.pyplot as plt

x = np.arange(100)
y = x
t = x
fig, (ax1, ax2) = plt.subplots(1, 2)
ax1.scatter(x, y, c=t, cmap='viridis')
ax2.scatter(x, y, c=t, cmap='viridis_r')
plt.show()

enter image description here

Colorbars

You can add a colorbar by using

plt.scatter(x, y, c=t, cmap='viridis')
plt.colorbar()
plt.show()

enter image description here

Note that if you are using figures and subplots explicitly (e.g. fig, ax = plt.subplots() or ax = fig.add_subplot(111)), adding a colorbar can be a bit more involved. Good examples can be found here for a single subplot colorbar and here for 2 subplots 1 colorbar.

Freeing up a TCP/IP port?

sudo killall -9 "process name"

Python causing: IOError: [Errno 28] No space left on device: '../results/32766.html' on disk with lots of space

The ENOSPC ("No space left on device") error will be triggered in any situation in which the data or the metadata associated with an I/O operation can't be written down anywhere because of lack of space. This doesn't always mean disk space – it could mean physical disk space, logical space (e.g. maximum file length), space in a certain data structure or address space. For example you can get it if there isn't space in the directory table (vfat) or there aren't any inodes left. It roughly means “I can't find where to write this down”.

Particularly in Python, this can happen on any write I/O operation. It can happen during f.write, but it can also happen on open, on f.flush and even on f.close. Where it happened provides a vital clue for the reason that it did – if it happened on open there wasn't enough space to write the metadata for the entry, if it happened during f.write, f.flush or f.close there wasn't enough disk space left or you've exceeded the maximum file size.

If the filesystem in the given directory is vfat you'd hit the maximum file limit at about the same time that you did. The limit is supposed to be 2^16 directory entries, but if I recall correctly some other factors can affect it (e.g. some files require more than one entry).

It would be best to avoid creating so many files in a directory. Few filesystems handle so many directory entries with ease. Unless you're certain that your filesystem deals well with many files in a directory, you can consider another strategy (e.g. create more directories).

P.S. Also do not trust the remaining disk space – some file systems reserve some space for root and others miscalculate the free space and give you a number that just isn't true.

jQuery 1.9 .live() is not a function

The jQuery API documentation lists live() as deprecated as of version 1.7 and removed as of version 1.9: link.

version deprecated: 1.7, removed: 1.9

Furthermore it states:

As of jQuery 1.7, the .live() method is deprecated. Use .on() to attach event handlers. Users of older versions of jQuery should use .delegate() in preference to .live()

How to suppress binary file matching results in grep

There are three options, that you can use. -I is to exclude binary files in grep. Other are for line numbers and file names.

grep -I -n -H 


-I -- process a binary file as if it did not contain matching data; 
-n -- prefix each line of output with the 1-based line number within its input file
-H -- print the file name for each match

So this might be a way to run grep:

grep -InH your-word *

PL/SQL print out ref cursor returned by a stored procedure

Note: This code is untested

Define a record for your refCursor return type, call it rec. For example:

TYPE MyRec IS RECORD (col1 VARCHAR2(10), col2 VARCHAR2(20), ...);  --define the record
rec MyRec;        -- instantiate the record

Once you have the refcursor returned from your procedure, you can add the following code where your comments are now:

LOOP
  FETCH refCursor INTO rec;
  EXIT WHEN refCursor%NOTFOUND;
  dbms_output.put_line(rec.col1||','||rec.col2||','||...);
END LOOP;

Why is synchronized block better than synchronized method?

Define 'better'. A synchronized block is only better because it allows you to:

  1. Synchronize on a different object
  2. Limit the scope of synchronization

Now your specific example is an example of the double-checked locking pattern which is suspect (in older Java versions it was broken, and it is easy to do it wrong).

If your initialization is cheap, it might be better to initialize immediately with a final field, and not on the first request, it would also remove the need for synchronization.

phpMyAdmin mbstring error

My case was like this

Strangely, I noticed that the php.ini file that WAMP was using wasn't the one in the php directory, but rather was referencing a php.ini file in the bin directory... I copied my php.ini file to wamp\bin\apache\apache2.4.17\bin directory, restarted the wamp services and PHPMyadmin was off and running...

Thanks I solved the problem

How to create relationships in MySQL

One of the rules you have to know is that the table column you want to reference to has to be with the same data type as The referencing table . 2 if you decide to use mysql you have to use InnoDB Engine because according to your question that’s the engine which supports what you want to achieve in mysql .

Bellow is the code try it though the first people to answer this question they 100% provided great answers and please consider them all .

CREATE TABLE accounts(
    account_id INT NOT NULL AUTO_INCREMENT,
    customer_id INT( 4 ) NOT NULL ,
    account_type ENUM( 'savings', 'credit' ) NOT NULL,
    balance FLOAT( 9 ) NOT NULL,
    PRIMARY KEY (account_id)
)ENGINE=InnoDB;

CREATE TABLE customers(
    customer_id INT NOT NULL AUTO_INCREMENT,
    name VARCHAR(20) NOT NULL,
    address VARCHAR(20) NOT NULL,
    city VARCHAR(20) NOT NULL,
    state VARCHAR(20) NOT NULL,
     PRIMARY KEY ( account_id ), 
FOREIGN KEY (customer_id) REFERENCES customers(customer_id) 
)ENGINE=InnoDB; 

Choosing the default value of an Enum type without having to change values

The default for an enum (in fact, any value type) is 0 -- even if that is not a valid value for that enum. It cannot be changed.

Secure hash and salt for PHP passwords

Google says SHA256 is available to PHP.

You should definitely use a salt. I'd recommend using random bytes (and not restrict yourself to characters and numbers). As usually, the longer you choose, the safer, slower it gets. 64 bytes ought to be fine, i guess.

Concatenating string and integer in python

Python is an interesting language in that while there is usually one (or two) "obvious" ways to accomplish any given task, flexibility still exists.

s = "string"
i = 0

print (s + repr(i))

The above code snippet is written in Python3 syntax but the parentheses after print were always allowed (optional) until version 3 made them mandatory.

Hope this helps.

Caitlin

How to decode encrypted wordpress admin password?

just edit wp_user table with your phpmyadmin, and choose MD5 on Function field then input your new password, save it (go button). enter image description here

MySQLDump one INSERT statement for each data row

Use:

mysqldump --extended-insert=FALSE 

Be aware that multiple inserts will be slower than one big insert.

Remove final character from string

What you are trying to do is an extension of string slicing in Python:

Say all strings are of length 10, last char to be removed:

>>> st[:9]
'abcdefghi'

To remove last N characters:

>>> N = 3
>>> st[:-N]
'abcdefg'

Changing button text onclick

If you prefer binding your events outside the html-markup (in the javascript) you could do it like this:

_x000D_
_x000D_
document.getElementById("curtainInput").addEventListener(_x000D_
  "click",_x000D_
  function(event) {_x000D_
    if (event.target.value === "Open Curtain") {_x000D_
      event.target.value = "Close Curtain";_x000D_
    } else {_x000D_
      event.target.value = "Open Curtain";_x000D_
    }_x000D_
  },_x000D_
  false_x000D_
);
_x000D_
<!doctype html>_x000D_
<html>_x000D_
<body>_x000D_
  <input _x000D_
         id="curtainInput" _x000D_
         type="button" _x000D_
         value="Open Curtain" />_x000D_
</body>_x000D_
_x000D_
</html>
_x000D_
_x000D_
_x000D_

How to input a string from user into environment variable from batch file

You can use set with the /p argument:

SET /P variable=[promptString]

The /P switch allows you to set the value of a variable to a line of input entered by the user. Displays the specified promptString before reading the line of input. The promptString can be empty.

So, simply use something like

set /p Input=Enter some text: 

Later you can use that variable as argument to a command:

myCommand %Input%

Be careful though, that if your input might contain spaces it's probably a good idea to quote it:

myCommand "%Input%"

How to secure RESTful web services?

If choosing between OAuth versions, go with OAuth 2.0.

OAuth bearer tokens should only be used with a secure transport.

OAuth bearer tokens are only as secure or insecure as the transport that encrypts the conversation. HTTPS takes care of protecting against replay attacks, so it isn't necessary for the bearer token to also guard against replay.

While it is true that if someone intercepts your bearer token they can impersonate you when calling the API, there are plenty of ways to mitigate that risk. If you give your tokens a long expiration period and expect your clients to store the tokens locally, you have a greater risk of tokens being intercepted and misused than if you give your tokens a short expiration, require clients to acquire new tokens for every session, and advise clients not to persist tokens.

If you need to secure payloads that pass through multiple participants, then you need something more than HTTPS/SSL, since HTTPS/SSL only encrypts one link of the graph. This is not a fault of OAuth.

Bearer tokens are easy to for clients to obtain, easy for clients to use for API calls and are widely used (with HTTPS) to secure public facing APIs from Google, Facebook, and many other services.

How to properly upgrade node using nvm

Here are the steps that worked for me for Ubuntu OS and using nvm

Go to nodejs website and get the last LTS version (for example in your current dater the version will be: x.y.z)

nvm install x.y.z
# In my case current version is: 14.15.4 (and had 14.15.3)

After that, execute nvm list and you will get list of node versions installed by nvm.

Now you need to switch to the default last installed one by executing:

nvm alias default x.y.z

List again or run nvm --version to check: enter image description here

Update: sometimes even if i go over the steps above it doesn't work, so what i did was removing the symbolic links in /usr/local/bin

cd /usr/local/bin
sudo rm node npm npx

And relink:

sudo ln -s $(which node) /usr/local/bin/node
sudo ln -s $(which npm) /usr/local/bin/npm
sudo ln -s $(which npx) /usr/local/bin/npx

How to convert CLOB to VARCHAR2 inside oracle pl/sql

This is my aproximation:

  Declare 
  Variableclob Clob;
  Temp_Save Varchar2(32767); //whether it is greater than 4000

  Begin
  Select reportClob Into Temp_Save From Reporte Where Id=...;
  Variableclob:=To_Clob(Temp_Save);
  Dbms_Output.Put_Line(Variableclob);


  End;

datetimepicker is not a function jquery

Place your scripts in this order:   

 <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">

    <!-- Optional theme -->
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap-theme.min.css">
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datetimepicker/4.17.37/css/bootstrap-datetimepicker.min.css" />

    <script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.10.6/moment.min.js"></script>   
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>

    <script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datetimepicker/4.17.37/js/bootstrap-datetimepicker.min.js"></script>

PHP CURL & HTTPS

Quick fix, add this in your options:

curl_setopt($ch,CURLOPT_SSL_VERIFYPEER, false)

Now you have no idea what host you're actually connecting to, because cURL will not verify the certificate in any way. Hope you enjoy man-in-the-middle attacks!

Or just add it to your current function:

/**
 * Get a web file (HTML, XHTML, XML, image, etc.) from a URL.  Return an
 * array containing the HTTP server response header fields and content.
 */
function get_web_page( $url )
{
    $options = array(
        CURLOPT_RETURNTRANSFER => true,     // return web page
        CURLOPT_HEADER         => false,    // don't return headers
        CURLOPT_FOLLOWLOCATION => true,     // follow redirects
        CURLOPT_ENCODING       => "",       // handle all encodings
        CURLOPT_USERAGENT      => "spider", // who am i
        CURLOPT_AUTOREFERER    => true,     // set referer on redirect
        CURLOPT_CONNECTTIMEOUT => 120,      // timeout on connect
        CURLOPT_TIMEOUT        => 120,      // timeout on response
        CURLOPT_MAXREDIRS      => 10,       // stop after 10 redirects
        CURLOPT_SSL_VERIFYPEER => false     // Disabled SSL Cert checks
    );

    $ch      = curl_init( $url );
    curl_setopt_array( $ch, $options );
    $content = curl_exec( $ch );
    $err     = curl_errno( $ch );
    $errmsg  = curl_error( $ch );
    $header  = curl_getinfo( $ch );
    curl_close( $ch );

    $header['errno']   = $err;
    $header['errmsg']  = $errmsg;
    $header['content'] = $content;
    return $header;
}

Dockerfile if else condition with external arguments

Using Bash script and Alpine/Centos

Dockerfile

FROM alpine  #just change this to centos 

ARG MYARG=""
ENV E_MYARG=$MYARG

ADD . /tmp
RUN chmod +x /tmp/script.sh && /tmp/script.sh

script.sh

#!/usr/bin/env sh

if [ -z "$E_MYARG" ]; then
    echo "NO PARAM PASSED"
else
    echo $E_MYARG
fi

Passing arg: docker build -t test --build-arg MYARG="this is a test" .

....
Step 5/5 : RUN chmod +x /tmp/script.sh && /tmp/script.sh
 ---> Running in 10b0e07e33fc
this is a test
Removing intermediate container 10b0e07e33fc
 ---> f6f085ffb284
Successfully built f6f085ffb284

Without arg: docker build -t test .

....
Step 5/5 : RUN chmod +x /tmp/script.sh && /tmp/script.sh
 ---> Running in b89210b0cac0
NO PARAM PASSED
Removing intermediate container b89210b0cac0
....

Merge Two Lists in R

Here are two options, the first:

both <- list(first, second)
n <- unique(unlist(lapply(both, names)))
names(n) <- n
lapply(n, function(ni) unlist(lapply(both, `[[`, ni)))

and the second, which works only if they have the same structure:

apply(cbind(first, second),1,function(x) unname(unlist(x)))

Both give the desired result.

How do I read a large csv file with pandas?

You can read in the data as chunks and save each chunk as pickle.

import pandas as pd 
import pickle

in_path = "" #Path where the large file is
out_path = "" #Path to save the pickle files to
chunk_size = 400000 #size of chunks relies on your available memory
separator = "~"

reader = pd.read_csv(in_path,sep=separator,chunksize=chunk_size, 
                    low_memory=False)    


for i, chunk in enumerate(reader):
    out_file = out_path + "/data_{}.pkl".format(i+1)
    with open(out_file, "wb") as f:
        pickle.dump(chunk,f,pickle.HIGHEST_PROTOCOL)

In the next step you read in the pickles and append each pickle to your desired dataframe.

import glob
pickle_path = "" #Same Path as out_path i.e. where the pickle files are

data_p_files=[]
for name in glob.glob(pickle_path + "/data_*.pkl"):
   data_p_files.append(name)


df = pd.DataFrame([])
for i in range(len(data_p_files)):
    df = df.append(pd.read_pickle(data_p_files[i]),ignore_index=True)

@AspectJ pointcut for all methods of a class with specific annotation

You could use Spring's PerformanceMonitoringInterceptor and programmatically register the advice using a beanpostprocessor.

@Target({ ElementType.TYPE, ElementType.METHOD })
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface Monitorable
{

}


public class PerformanceMonitorBeanPostProcessor extends ProxyConfig implements BeanPostProcessor, BeanClassLoaderAware, Ordered,
    InitializingBean
{

  private Class<? extends Annotation> annotationType = Monitorable.class;

  private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();

  private Advisor advisor;

  public void setBeanClassLoader(ClassLoader classLoader)
  {
    this.beanClassLoader = classLoader;
  }

  public int getOrder()
  {
    return LOWEST_PRECEDENCE;
  }

  public void afterPropertiesSet()
  {
    Pointcut pointcut = new AnnotationMatchingPointcut(this.annotationType, true);
    Advice advice = getInterceptor();
    this.advisor = new DefaultPointcutAdvisor(pointcut, advice);
  }

  private Advice getInterceptor()
  {
    return new PerformanceMonitoringInterceptor();
  }

  public Object postProcessBeforeInitialization(Object bean, String beanName)
  {
    return bean;
  }

  public Object postProcessAfterInitialization(Object bean, String beanName)
  {
    if(bean instanceof AopInfrastructureBean)
    {
      return bean;
    }
    Class<?> targetClass = AopUtils.getTargetClass(bean);
    if(AopUtils.canApply(this.advisor, targetClass))
    {
      if(bean instanceof Advised)
      {
        ((Advised)bean).addAdvisor(this.advisor);
        return bean;
      }
      else
      {
        ProxyFactory proxyFactory = new ProxyFactory(bean);
        proxyFactory.copyFrom(this);
        proxyFactory.addAdvisor(this.advisor);
        return proxyFactory.getProxy(this.beanClassLoader);
      }
    }
    else
    {
      return bean;
    }
  }
}

Change GitHub Account username

Yes, it's possible. But first read, "What happens when I change my username?"

To change your username, click your profile picture in the top right corner, then click Settings. On the left side, click Account. Then click Change username.

hidden field in php

Can I use a field of the type ... and retrieve it after the GET / POST method ...

Yes (haven't you tried?)

Are there any other ways of using hidden fields in PHP?

You mean other ways of retrieving the value? No.
Of course you can use hidden fields for what ever you want.


Btw. input fiels have no end tag. So write either just <input ...> or as self-closing tag <input .../>.

How do I convert a C# List<string[]> to a Javascript array?

You could directly inject the values into JavaScript:

//View.cshtml
<script type="text/javascript">
    var arrayOfArrays = JSON.parse('@Html.Raw(Model.Addresses)');
</script>

See JSON.parse, Html.Raw

Alternatively you can get the values via Ajax:

public ActionResult GetValues()
{
    // logic
    // Edit you don't need to serialize it just return the object

    return Json(new { Addresses: lAddressGeocodeModel });
}

<script type="text/javascript">
$(function() {
    $.ajax({
        type: 'POST',
        url: '@Url.Action("GetValues")',
        success: function(result) {
            // do something with result
        }
    });
});
</script>

See jQuery.ajax

Get selected value/text from Select on change

<script>
function test(a) {
    var x = a.selectedIndex;
    alert(x);
}
</script>
<select onchange="test(this)" id="select_id">
    <option value="0">-Select-</option>
    <option value="1">Communication</option>
    <option value="2">Communication</option>
    <option value="3">Communication</option>
</select>

in the alert you'll see the INT value of the selected index, treat the selection as an array and you'll get the value

Pushing an existing Git repository to SVN

Here's how we made it work:

Clone your Git repository somewhere on your machine.

Open .git/config and add the following (from Maintaining a read-only SVN mirror of a Git repository):

[svn-remote "svn"]
    url = https://your.svn.repo
    fetch = :refs/remotes/git-svn

Now, from a console window, type these:

git svn fetch svn
git checkout -b svn git-svn
git merge master

Now, if it breaks here for whatever reason, type these three lines:

git checkout --theirs .
git add .
git commit -m "some message"

And finally, you can commit to SVN:

git svn dcommit

Note: I always scrap that folder afterwards.

How to declare a Fixed length Array in TypeScript

The javascript array has a constructor that accepts the length of the array:

let arr = new Array<number>(3);
console.log(arr); // [undefined × 3]

However, this is just the initial size, there's no restriction on changing that:

arr.push(5);
console.log(arr); // [undefined × 3, 5]

Typescript has tuple types which let you define an array with a specific length and types:

let arr: [number, number, number];

arr = [1, 2, 3]; // ok
arr = [1, 2]; // Type '[number, number]' is not assignable to type '[number, number, number]'
arr = [1, 2, "3"]; // Type '[number, number, string]' is not assignable to type '[number, number, number]'

Find full path of the Python interpreter?

There are a few alternate ways to figure out the currently used python in Linux is:

  1. which python command.
  2. command -v python command
  3. type python command

Similarly On Windows with Cygwin will also result the same.

kuvivek@HOSTNAME ~
$ which python
/usr/bin/python

kuvivek@HOSTNAME ~
$ whereis python
python: /usr/bin/python /usr/bin/python3.4 /usr/lib/python2.7 /usr/lib/python3.4        /usr/include/python2.7 /usr/include/python3.4m /usr/share/man/man1/python.1.gz

kuvivek@HOSTNAME ~
$ which python3
/usr/bin/python3

kuvivek@HOSTNAME ~
$ command -v python
/usr/bin/python

kuvivek@HOSTNAME ~
$ type python
python is hashed (/usr/bin/python)

If you are already in the python shell. Try anyone of these. Note: This is an alternate way. Not the best pythonic way.

>>> import os
>>> os.popen('which python').read()
'/usr/bin/python\n'
>>>
>>> os.popen('type python').read()
'python is /usr/bin/python\n'
>>>
>>> os.popen('command -v python').read()
'/usr/bin/python\n'
>>>
>>>

If you are not sure of the actual path of the python command and is available in your system, Use the following command.

pi@osboxes:~ $ which python
/usr/bin/python
pi@osboxes:~ $ readlink -f $(which python)
/usr/bin/python2.7
pi@osboxes:~ $ 
pi@osboxes:~ $ which python3
/usr/bin/python3
pi@osboxes:~ $ 
pi@osboxes:~ $ readlink -f $(which python3)
/usr/bin/python3.7
pi@osboxes:~ $ 

open new tab(window) by clicking a link in jquery

Try this:

window.open(url, '_blank');

This will open in new tab (if your code is synchronous and in this case it is. in other case it would open a window)

How to find the default JMX port number?

Now I need to connect that application from my local computer, but I don't know the JMX port number of the remote computer. Where can I find it? Or, must I restart that application with some VM parameters to specify the port number?

By default JMX does not publish on a port unless you specify the arguments from this page: How to activate JMX...

-Dcom.sun.management.jmxremote # no longer required for JDK6
-Dcom.sun.management.jmxremote.port=9010
-Dcom.sun.management.jmxremote.local.only=false # careful with security implications
-Dcom.sun.management.jmxremote.authenticate=false # careful with security implications

If you are running you should be able to access any of those system properties to see if they have been set:

if (System.getProperty("com.sun.management.jmxremote") == null) {
    System.out.println("JMX remote is disabled");
} else [
    String portString = System.getProperty("com.sun.management.jmxremote.port");
    if (portString != null) {
        System.out.println("JMX running on port "
            + Integer.parseInt(portString));
    }
}

Depending on how the server is connected, you might also have to specify the following parameter. As part of the initial JMX connection, jconsole connects up to the RMI port to determine which port the JMX server is running on. When you initially start up a JMX enabled application, it looks its own hostname to determine what address to return in that initial RMI transaction. If your hostname is not in /etc/hosts or if it is set to an incorrect interface address then you can override it with the following:

-Djava.rmi.server.hostname=<IP address>

As an aside, my SimpleJMX package allows you to define both the JMX server and the RMI port or set them both to the same port. The above port defined with com.sun.management.jmxremote.port is actually the RMI port. This tells the client what port the JMX server is running on.

How to verify if $_GET exists?

   if (isset($_GET["id"])){
        //do stuff
    }

Using $setValidity inside a Controller

This line:

myForm.file.$setValidity("myForm.file.$error.size", false);

Should be

$scope.myForm.file.$setValidity("size", false);

Importing a GitHub project into Eclipse

When the local git projects are cloned in eclipse and are viewable in git perspective but not in package explorer (workspace), the following steps worked for me:

  • Select the repository in git perspective
  • Right click and select import projects

Twitter bootstrap collapse: change display of toggle button

Some may take issue with changing the Bootstrap js (and perhaps validly so) but here is a two line approach to achieving this.

In bootstrap.js, look for the Collapse.prototype.show function and modify the this.$trigger call to add the html change as follows:

this.$trigger
  .removeClass('collapsed')
  .attr('aria-expanded', true)
  .html('Collapse')

Likewise in the Collapse.prototype.hide function change it to

this.$trigger
  .addClass('collapsed')
  .attr('aria-expanded', false)
  .html('Expand')

This will toggle the text between "Collapse" when everything is expanded and "Expand" when everything is collapsed.

Two lines. Done.

EDIT: longterm this won't work. bootstrap.js is part of a Nuget package so I don't think it was propogating my change to the server. As mentioned previously, not best practice anyway to edit bootstrap.js, so I implemented PSL's solution which worked great. Nonetheless, my solution will work locally if you need something quick just to try it out.

Can you call ko.applyBindings to bind a partial view?

While Niemeyer's answer is a more correct answer to the question, you could also do the following:

<div>
  <input data-bind="value: VMA.name" />
</div>

<div>
  <input data-bind="value: VMB.name" />
</div>

<script type="text/javascript">
  var viewModels = {
     VMA: {name: ko.observable("Bob")},
     VMB: {name: ko.observable("Ted")}
  };

  ko.applyBindings(viewModels);
</script>

This means you don't have to specify the DOM element, and you can even bind multiple models to the same element, like this:

<div>
  <input data-bind="value: VMA.name() + ' and ' + VMB.name()" />
</div>

How to completely remove a dialog on close

$(dialogElement).empty();

$(dialogElement).remove();

this fixes it for real

PHP: How to check if image file exists?

try this :

if (file_exists(FCPATH . 'uploads/pages/' . $image)) {
    unlink(FCPATH . 'uploads/pages/' . $image);
}

Accessing clicked element in angularjs

While AngularJS allows you to get a hand on a click event (and thus a target of it) with the following syntax (note the $event argument to the setMaster function; documentation here: http://docs.angularjs.org/api/ng.directive:ngClick):

function AdminController($scope) {    
  $scope.setMaster = function(obj, $event){
    console.log($event.target);
  }
}

this is not very angular-way of solving this problem. With AngularJS the focus is on the model manipulation. One would mutate a model and let AngularJS figure out rendering.

The AngularJS-way of solving this problem (without using jQuery and without the need to pass the $event argument) would be:

<div ng-controller="AdminController">
    <ul class="list-holder">
        <li ng-repeat="section in sections" ng-class="{active : isSelected(section)}">
            <a ng-click="setMaster(section)">{{section.name}}</a>
        </li>
    </ul>
    <hr>
    {{selected | json}}
</div>

where methods in the controller would look like this:

$scope.setMaster = function(section) {
    $scope.selected = section;
}

$scope.isSelected = function(section) {
    return $scope.selected === section;
}

Here is the complete jsFiddle: http://jsfiddle.net/pkozlowski_opensource/WXJ3p/15/

How to append something to an array?

Append a value to an array

Since Array.prototype.push adds one or more elements to the end of an array and returns the new length of the array, sometimes we want just to get the new up-to-date array so we can do something like so:

const arr = [1, 2, 3];
const val = 4;

arr.concat([val]); // [1, 2, 3, 4]

Or just:

[...arr, val] // [1, 2, 3, 4]

Oracle date difference to get number of years

Need to find difference in year, if leap year the a year is of 366 days.

I dont work in oracle much, please make this better. Here is how I did:

SELECT CASE
          WHEN    ( (fromisleapyear = 'Y') AND (frommonth < 3))
               OR ( (toisleapyear = 'Y') AND (tomonth > 2)) THEN
             datedif / 366
          ELSE
             datedif / 365
       END
          yeardifference
  FROM (SELECT datedif,
               frommonth,
               tomonth,
               CASE
                  WHEN (       (MOD (fromyear, 4) = 0)
                           AND (MOD (fromyear, 100) <> 0)
                        OR (MOD (fromyear, 400) = 0)) THEN
                     'Y'
               END
                  fromisleapyear,
               CASE
                  WHEN (   (MOD (toyear, 4) = 0) AND (MOD (toyear, 100) <> 0)
                        OR (MOD (toyear, 400) = 0)) THEN
                     'Y'
               END
                  toisleapyear
          FROM (SELECT (:todate - :fromdate) AS datedif,
                       TO_CHAR (:fromdate, 'YYYY') AS fromyear,
                       TO_CHAR (:fromdate, 'MM') AS frommonth,
                       TO_CHAR (:todate, 'YYYY') AS toyear,
                       TO_CHAR (:todate, 'MM') AS tomonth
                  FROM DUAL))

Split a string by another string in C#

In order to split by a string you'll have to use the string array overload.

string data = "THExxQUICKxxBROWNxxFOX";

return data.Split(new string[] { "xx" }, StringSplitOptions.None);

Get Value From Select Option in Angular 4

    //in html file
    <div class="row">
                <div class="col-md-6">
                    <div class="form-group">
                        <label for="name">Country</label>
                        <select class="form-control" formControlName="country" (change)="onCountryChange($event.target.value)">
                            <option disabled selected value [ngValue]="null"> -- Select Country  -- </option>
                            <option *ngFor="let country of countries" [value]="country.id">{{country.name}}</option>
                            <div *ngIf="isEdit">
                                <option></option>
                            </div>
                        </select>
                      </div>   
                </div>
            </div>
            <div class="help-block" *ngIf="studentForm.get('country').invalid && studentForm.get('country').touched">
                <div *ngIf="studentForm.get('country').errors.required">*country is required</div>
            </div>
            <div class="row">
                <div class="col-md-6">
                    <div class="form-group">
                        <label for="name">State</label>
                        <select class="form-control" formControlName="state" (change)="onStateChange($event.target.value)">
                            <option disabled selected value [ngValue]="null"> -- Select State -- </option>
                            <option *ngFor="let state of states" [value]="state.id">{{state.state_name}}</option>
                        </select>
                      </div>   
                </div>
            </div>
            <div class="help-block" *ngIf="studentForm.get('state').invalid && studentForm.get('state').touched">
                <div *ngIf="studentForm.get('state').errors.required">*state is enter code hererequired</div>
            </div>
            <div class="row">
                <div class="col-md-6">
                    <div class="form-group">
                        <label for="name">City</label>
                        <select class="form-control" formControlName="city">
                            <option disabled selected value [ngValue]="null"> -- Select City -- </option>
                            <option *ngFor="let city of cities" [value]="city.id" >{{city.city_name}}</option>
                        </select>
                      </div>   
                </div>
            </div>
            <div class="help-block" *ngIf="studentForm.get('city').invalid && studentForm.get('city').touched">
                <div *ngIf="studentForm.get('city').errors.required">*city is required</div>
            </div>
    //then in component
    onCountryChange(countryId:number){
   this.studentServive.getSelectedState(countryId).subscribe(resData=>{
    this.states = resData;
   });
  }
  onStateChange(stateId:number){
    this.studentServive.getSelectedCity(stateId).subscribe(resData=>{
     this.cities = resData;
    });
   }`enter code here`

Skip to next iteration in loop vba

For i = 2 To 24
  Level = Cells(i, 4)
  Return = Cells(i, 5)

  If Return = 0 And Level = 0 Then GoTo NextIteration
  'Go to the next iteration
  Else
  End If
  ' This is how you make a line label in VBA - Do not use keyword or
  ' integer and end it in colon
  NextIteration:
Next

Intel HAXM installation error - This computer does not support Intel Virtualization Technology (VT-x)

If any of the answers doesn't work just remove Android Emulator and reinstall it again. and after that try installing Intel Haxm.

PHPDoc type hinting for array of objects?

I've found something which is working, it can save lives !

private $userList = array();
$userList = User::fetchAll(); // now $userList is an array of User objects
foreach ($userList as $user) {
   $user instanceof User;
   echo $user->getName();
}

How do you add PostgreSQL Driver as a dependency in Maven?

<dependency>
    <groupId>org.postgresql</groupId>
    <artifactId>postgresql</artifactId>
    <scope>runtime</scope>
</dependency>

Row count where data exists

lastrow = Sheet1.Range("A#").End(xlDown).Row

This is more easy to determine the row count.
Make sure you declare the right variable when it comes to larger rows.
By the way the '#' sign must be a number where you want to start the row count.

Smooth scroll to div id jQuery

This script is a improvement of the script from Vector. I have made a little change to it. So this script works for every link with the class page-scroll in it.

At first without easing:

$("a.page-scroll").click(function() {
    var targetDiv = $(this).attr('href');
    $('html, body').animate({
        scrollTop: $(targetDiv).offset().top
    }, 1000);
});

For easing you will need Jquery UI:

<script src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.11.4/jquery-ui.min.js"></script>

Add this to the script:

'easeOutExpo'

Final

$("a.page-scroll").click(function() {
    var targetDiv = $(this).attr('href');
    $('html, body').animate({
        scrollTop: $(targetDiv).offset().top
    }, 1000, 'easeOutExpo');
});

All the easings you can find here: Cheat Sheet.

MySQL : transaction within a stored procedure

This is just an explanation not addressed in other answers

At least in recent versions of Mysql, your first query is not committed.

If you query it under the same session you will see the changes, but if you query it from a different session, the changes are not there, they are not committed.

What's going on?

When you open a transaction, and a query inside it fails, the transaction keeps open, it does not commit nor rollback the changes.

So BE CAREFUL, any table/row that was locked with a previous query likeSELECT ... FOR SHARE/UPDATE, UPDATE, INSERT or any other locking-query, keeps locked until that session is killed (and executes a rollback), or until a subsequent query commits it explicitly (COMMIT) or implicitly, thus making the partial changes permanent (which might happen hours later, while the transaction was in a waiting state).

That's why the solution involves declaring handlers to immediately ROLLBACK when an error happens.

Extra

Inside the handler you can also re-raise the error using RESIGNAL, otherwise the stored procedure executes "Successfully"

BEGIN
    DECLARE EXIT HANDLER FOR SQLEXCEPTION 
        BEGIN
            ROLLBACK;
            RESIGNAL;
        END;

    START TRANSACTION;
        #.. Query 1 ..
        #.. Query 2 ..
        #.. Query 3 ..
    COMMIT;
END

Passing the argument to CMAKE via command prompt

CMake 3.13 on Ubuntu 16.04

This approach is more flexible because it doesn't constraint MY_VARIABLE to a type:

$ cat CMakeLists.txt 
message("MY_VARIABLE=${MY_VARIABLE}")
if( MY_VARIABLE ) 
    message("MY_VARIABLE evaluates to True")
endif()

$ mkdir build && cd build

$ cmake ..
MY_VARIABLE=
-- Configuring done
-- Generating done
-- Build files have been written to: /path/to/build

$ cmake .. -DMY_VARIABLE=True
MY_VARIABLE=True
MY_VARIABLE evaluates to True
-- Configuring done
-- Generating done
-- Build files have been written to: /path/to/build

$ cmake .. -DMY_VARIABLE=False
MY_VARIABLE=False
-- Configuring done
-- Generating done
-- Build files have been written to: /path/to/build

$ cmake .. -DMY_VARIABLE=1
MY_VARIABLE=1
MY_VARIABLE evaluates to True
-- Configuring done
-- Generating done
-- Build files have been written to: /path/to/build

$ cmake .. -DMY_VARIABLE=0
MY_VARIABLE=0
-- Configuring done
-- Generating done
-- Build files have been written to: /path/to/build

Date format Mapping to JSON Jackson

Working for me. SpringBoot.

 import com.alibaba.fastjson.annotation.JSONField;

 @JSONField(format = "yyyy-MM-dd HH:mm:ss")  
 private Date createTime;

output:

{ 
   "createTime": "2019-06-14 13:07:21"
}

How to create large PDF files (10MB, 50MB, 100MB, 200MB, 500MB, 1GB, etc.) for testing purposes?

For those using macOS mkfile might be a good alternative to fallocate or dd

mkfile 100m some100mfile.pdf

reference - https://stackoverflow.com/a/33478049/711401

How to bind Close command to a button

In the beginning I was also having a bit of trouble figuring out how this works so I wanted to post a better explanation of what is actually going on.

According to my research the best way to handle things like this is using the Command Bindings. What happens is a "Message" is broadcast to everything in the program. So what you have to do is use the CommandBinding. What this essentially does is say "When you hear this Message do this".

So in the Question the User is trying to Close the Window. The first thing we need to do is setup our Functions that will be called when the SystemCommand.CloseWindowCommand is broadcast. Optionally you can assign a Function that determines if the Command should be executed. An example would be closing a Form and checking if the User has saved.

MainWindow.xaml.cs (Or other Code-Behind)

void CloseApp( object target, ExecutedRoutedEventArgs e ) {
    /*** Code to check for State before Closing ***/
    this.Close();
}

void CloseAppCanExecute( object sender, CanExecuteRoutedEventArgs e ) {
    /*** Logic to Determine if it is safe to Close the Window ***/
    e.CanExecute = true;
}

Now we need to setup the "Connection" between the SystemCommands.CloseWindowCommand and the CloseApp and CloseAppCanExecute

MainWindow.xaml (Or anything that implements CommandBindings)

<Window.CommandBindings>
    <CommandBinding Command="SystemCommands.CloseWindowCommand"
                    Executed="CloseApp"
                    CanExecute="CloseAppCanExecute"/>
</Window.CommandBindings>

You can omit the CanExecute if you know that the Command should be able to always be executed Save might be a good example depending on the Application. Here is a Example:

<Window.CommandBindings>
    <CommandBinding Command="SystemCommands.CloseWindowCommand"
                    Executed="CloseApp"/>
</Window.CommandBindings>

Finally you need to tell the UIElement to send out the CloseWindowCommand.

<Button Command="SystemCommands.CloseWindowCommand">

Its actually a very simple thing to do, just setup the link between the Command and the actual Function to Execute then tell the Control to send out the Command to the rest of your program saying "Ok everyone run your Functions for the Command CloseWindowCommand".

This is actually a very nice way of handing this because, you can reuse the Executed Function all over without having a wrapper like you would with say WinForms (using a ClickEvent and calling a function within the Event Function) like:

protected override void OnClick(EventArgs e){
    /*** Function to Execute ***/
}

In WPF you attach the Function to a Command and tell the UIElement to execute the Function attached to the Command instead.

I hope this clears things up...

force css grid container to fill full screen of device

If you want the .wrapper to be fullscreen, just add the following in the wrapper class:

position: absolute; width: 100%; height: 100%;

You can also add top: 0 and left:0

python request with authentication (access_token)

The requests package has a very nice API for HTTP requests, adding a custom header works like this (source: official docs):

>>> import requests
>>> response = requests.get(
... 'https://website.com/id', headers={'Authorization': 'access_token myToken'})

If you don't want to use an external dependency, the same thing using urllib2 of the standard library looks like this (source: the missing manual):

>>> import urllib2
>>> response = urllib2.urlopen(
... urllib2.Request('https://website.com/id', headers={'Authorization': 'access_token myToken'})

How to diff a commit with its parent?

Use:

git diff 15dc8^!

as described in the following fragment of git-rev-parse(1) manpage (or in modern git gitrevisions(7) manpage):

Two other shorthands for naming a set that is formed by a commit and its parent commits exist. The r1^@ notation means all parents of r1. r1^! includes commit r1 but excludes all of its parents.

This means that you can use 15dc8^! as a shorthand for 15dc8^..15dc8 anywhere in git where revisions are needed. For diff command the git diff 15dc8^..15dc8 is understood as git diff 15dc8^ 15dc8, which means the difference between parent of commit (15dc8^) and commit (15dc8).

Note: the description in git-rev-parse(1) manpage talks about revision ranges, where it needs to work also for merge commits, with more than one parent. Then r1^! is "r1 --not r1^@" i.e. "r1 ^r1^1 ^r1^2 ..."


Also, you can use git show COMMIT to get commit description and diff for a commit. If you want only diff, you can use git diff-tree -p COMMIT

"column not allowed here" error in INSERT statement

This error creeps in if we make some spelling mistake in entering the variable name. Like in stored proc, I have the variable name x and in my insert statement I am using

insert into tablename values(y);

It will throw an error column not allowed here.

read word by word from file in C++

I have edited the function for you,

void readFile()
{
    ifstream file;
    file.open ("program.txt");
    if (!file.is_open()) return;

    string word;
    while (file >> word)
    {
        cout<< word << '\n';
    }
}

How to convert char to int?

An extension of some other answers that covers hexadecimal representation:

public int CharToInt(char c) 
{
    if (c >= '0' && c <= '9') 
    {
        return c - '0';
    }
    else if (c >= 'a' && c <= 'f') 
    {
        return 10 + c - 'a';
    }
    else if (c >= 'A' && c <= 'F') 
    {
        return 10 + c - 'A';
    }

    return -1;
}

javascript: Disable Text Select

Just use this css method:

body{
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}

You can find the same answer here: How to disable text selection highlighting using CSS?

How to connect to Oracle 11g database remotely

First, make sure the listener on database server (computer A) that receives client connection requests is running. To do so, run lsnrctl status command.

In case, if you get TNS:no listener message (see below image), it means listener service is not running. To start it, run lsnrctl start command.

enter image description here

Second, for database operations and connectivity from remote clients, the following executables must be added to the Windows Firewall exception list: (see image)

Oracle_home\bin\oracle.exe - Oracle Database executable

Oracle_home\bin\tnslsnr.exe - Oracle Listener

enter image description here

Finally, install oracle instant client on client machine (computer B) and run:

sqlplus user/password@computerA:port/XE

How to get index of an item in java.util.Set

After creating Set just convert it to List and get by index from List:

Set<String> stringsSet = new HashSet<>();
stringsSet.add("string1");
stringsSet.add("string2");

List<String> stringsList = new ArrayList<>(stringsSet);
stringsList.get(0); // "string1";
stringsList.get(1); // "string2";

Add a space (" ") after an element using :after

There can be a problem with "\00a0" in pseudo-elements because it takes the text-decoration of its defining element, so that, for example, if the defining element is underlined, then the white space of the pseudo-element is also underlined.

The easiest way to deal with this is to define the opacity of the pseudo-element to be zero, eg:

element:before{
  content: "_";
  opacity: 0;
}

How to install package from github repo in Yarn

You can add any Git repository (or tarball) as a dependency to yarn by specifying the remote URL (either HTTPS or SSH):

yarn add <git remote url> installs a package from a remote git repository.
yarn add <git remote url>#<branch/commit/tag> installs a package from a remote git repository at specific git branch, git commit or git tag.
yarn add https://my-project.org/package.tgz installs a package from a remote gzipped tarball.

Here are some examples:

yarn add https://github.com/fancyapps/fancybox [remote url]
yarn add ssh://github.com/fancyapps/fancybox#3.0  [branch]
yarn add https://github.com/fancyapps/fancybox#5cda5b529ce3fb6c167a55d42ee5a316e921d95f [commit]

(Note: Fancybox v2.6.1 isn't available in the Git version.)

To support both npm and yarn, you can use the git+url syntax:

git+https://github.com/owner/package.git#commithashortagorbranch
git+ssh://github.com/owner/package.git#commithashortagorbranch

Could pandas use column as index?

Yes, with set_index you can make Locality your row index.

data.set_index('Locality', inplace=True)

If inplace=True is not provided, set_index returns the modified dataframe as a result.

Example:

> import pandas as pd
> df = pd.DataFrame([['ABBOTSFORD', 427000, 448000],
                     ['ABERFELDIE', 534000, 600000]],
                    columns=['Locality', 2005, 2006])

> df
     Locality    2005    2006
0  ABBOTSFORD  427000  448000
1  ABERFELDIE  534000  600000

> df.set_index('Locality', inplace=True)
> df
              2005    2006
Locality                  
ABBOTSFORD  427000  448000
ABERFELDIE  534000  600000

> df.loc['ABBOTSFORD']
2005    427000
2006    448000
Name: ABBOTSFORD, dtype: int64

> df.loc['ABBOTSFORD'][2005]
427000

> df.loc['ABBOTSFORD'].values
array([427000, 448000])

> df.loc['ABBOTSFORD'].tolist()
[427000, 448000]

Eliminate extra separators below UITableView

Try this

self.tables.tableFooterView = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 320.0f, 10.0f)];

How do I check if a SQL Server text column is empty?

Instead of using isnull use a case, because of performance it is better the case.

case when campo is null then '' else campo end

In your issue you need to do this:

case when campo is null then '' else
  case when len(campo) = 0 then '' else campo en
end

Code like this:

create table #tabla(
id int,
campo varchar(10)
)

insert into #tabla
values(1,null)

insert into #tabla
values(2,'')

insert into #tabla
values(3,null)

insert into #tabla
values(4,'dato4')

insert into #tabla
values(5,'dato5')

select id, case when campo is null then 'DATA NULL' else
  case when len(campo) = 0 then 'DATA EMPTY' else campo end
end
from #tabla

drop table #tabla

How to rsync only a specific list of files?

None of these answers worked for me, when all I had was a list of directories. Then I stumbled upon the solution! You have to add -r to --files-from because -a will not be recursive in this scenario (who knew?!).

rsync -aruRP --files-from=directory.list . ../new/location

How can I send an xml body using requests library?

Pass in the straight XML instead of a dictionary.

Installing Node.js (and npm) on Windows 10

go to http://nodejs.org/

and hit the button that says "Download For ..."

This'll download the .msi (or .pkg for mac) which will do all the installation and paths for you, unlike the selected answer.

CSS to set A4 paper size

https://github.com/cognitom/paper-css seems to solve all my needs.

Paper CSS for happy printing

Front-end printing solution - previewable and live-reloadable!

Jquery submit form

Since a jQuery object inherits from an array, and this array contains the selected DOM elements. Saying you're using an id and so the element should be unique within the DOM, you could perform a direct call to submit by doing :

$(".nextbutton").click(function() { 
  $("#formID")[0].submit();
});

What's the equivalent of Java's Thread.sleep() in JavaScript?

This eventually helped me:

    var x = 0;
    var buttonText = 'LOADING';

    $('#startbutton').click(function(){
        $(this).text(buttonText);
        window.setTimeout(addDotToButton,2000);
    })

    function addDotToButton(){
        x++;
        buttonText += '.';
        $('#startbutton').text(buttonText);

        if (x < 4) window.setTimeout(addDotToButton, 2000);
        else location.reload(true);
    }

How to get duration, as int milli's and float seconds from <chrono>?

Taking a guess at what it is you're asking for. I'm assuming by millisecond frame timer you're looking for something that acts like the following,

double mticks()
{
    struct timeval tv;
    gettimeofday(&tv, 0);
    return (double) tv.tv_usec / 1000 + tv.tv_sec * 1000;
}

but uses std::chrono instead,

double mticks()
{
    typedef std::chrono::high_resolution_clock clock;
    typedef std::chrono::duration<float, std::milli> duration;

    static clock::time_point start = clock::now();
    duration elapsed = clock::now() - start;
    return elapsed.count();
}

Hope this helps.

How can I uninstall Ruby on ubuntu?

This command should do the trick (provided that you installed it using a dpkg-based packet manager):

aptitude purge ruby

How to pass a Javascript Array via JQuery Post so that all its contents are accessible via the PHP $_POST array?

If you want to pass a JavaScript object/hash (ie. an associative array in PHP) then you would do:

$.post('/url/to/page', {'key1': 'value', 'key2': 'value'});

If you wanna pass an actual array (ie. an indexed array in PHP) then you can do:

$.post('/url/to/page', {'someKeyName': ['value','value']});

If you want to pass a JavaScript array then you can do:

$.post('/url/to/page', {'someKeyName': variableName});

How can I check if an InputStream is empty without reading from it?

You can use the available() method to ask the stream whether there is any data available at the moment you call it. However, that function isn't guaranteed to work on all types of input streams. That means that you can't use available() to determine whether a call to read() will actually block or not.

Check whether a cell contains a substring

For those who would like to do this using a single function inside the IF statement, I use

=IF(COUNTIF(A1,"*TEXT*"),TrueValue,FalseValue)

to see if the substring TEXT is in cell A1

[NOTE: TEXT needs to have asterisks around it]

Python print statement “Syntax Error: invalid syntax”

Use print("use this bracket -sample text")

In Python 3 print "Hello world" gives invalid syntax error.

To display string content in Python3 have to use this ("Hello world") brackets.

Error checking for NULL in VBScript

I will just add a blank ("") to the end of the variable and do the comparison. Something like below should work even when that variable is null. You can also trim the variable just in case of spaces.

If provider & "" <> "" Then 
    url = url & "&provider=" & provider 
End if

Gradle proxy configuration

Based on SourceSimian's response; this worked on Windows domain user accounts. Note that the Username does not have domain included,

task setHttpProxyFromEnv {
    def map = ['HTTP_PROXY': 'http', 'HTTPS_PROXY': 'https']
    for (e in System.getenv()) {
        def key = e.key.toUpperCase()
        if (key in map) {
            def base = map[key]
            def url = e.value.toURL()
            println " - systemProp.${base}.proxy=${url.host}:${url.port}"
            System.setProperty("${base}.proxyHost", url.host.toString())
            System.setProperty("${base}.proxyPort", url.port.toString())
            System.setProperty("${base}.proxyUser", "Username")
            System.setProperty("${base}.proxyPassword", "Password")
        }
    }
}
build.dependsOn setHttpProxyFromEnv

Correctly ignore all files recursively under a specific folder except for a specific file type

The best answer is to add a Resources/.gitignore file under Resources containing:

# Ignore any file in this directory except for this file and *.foo files
*
!/.gitignore
!*.foo

If you are unwilling or unable to add that .gitignore file, there is an inelegant solution:

# Ignore any file but *.foo under Resources. Update this if we add deeper directories
Resources/*
!Resources/*/
!Resources/*.foo
Resources/*/*
!Resources/*/*/
!Resources/*/*.foo
Resources/*/*/*
!Resources/*/*/*/
!Resources/*/*/*.foo
Resources/*/*/*/*
!Resources/*/*/*/*/
!Resources/*/*/*/*.foo

You will need to edit that pattern if you add directories deeper than specified.

What is the easiest way to initialize a std::vector with hardcoded elements?

For vector initialisation -

vector<int> v = {10,20,30}

can be done if you have C++11 compiler.

Else, you can have an array of the data and then use a for loop.

int array[] = {10,20,30}
for(unsigned int i=0; i<sizeof(array)/sizeof(array[0]); i++)
{
     v.push_back(array[i]);
}

Apart from these, there are various other ways described above using some code. In my opinion, these ways are easy to remember and quick to write.

How do you fix the "element not interactable" exception?

A possibility is that the element is currently unclickable because it is not visible. Reasons for this may be that another element is covering it up or it is not in view, i.e. it is outside the currently view-able area.

Try this

from selenium.webdriver.common.action_chains import ActionChains

button = driver.find_element_by_class_name(u"infoDismiss")
driver.implicitly_wait(10)
ActionChains(driver).move_to_element(button).click(button).perform()

How to reload or re-render the entire page using AngularJS

For reloading the page for a given route path :-

$location.path('/path1/path2');
$route.reload();

How to properly seed random number generator

just to toss it out for posterity: it can sometimes be preferable to generate a random string using an initial character set string. This is useful if the string is supposed to be entered manually by a human; excluding 0, O, 1, and l can help reduce user error.

var alpha = "abcdefghijkmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ23456789"

// generates a random string of fixed size
func srand(size int) string {
    buf := make([]byte, size)
    for i := 0; i < size; i++ {
        buf[i] = alpha[rand.Intn(len(alpha))]
    }
    return string(buf)
}

and I typically set the seed inside of an init() block. They're documented here: http://golang.org/doc/effective_go.html#init

When to use setAttribute vs .attribute= in JavaScript?

This looks like one case where it is better to use setAttribute:

Dev.Opera — Efficient JavaScript

var posElem = document.getElementById('animation');
var newStyle = 'background: ' + newBack + ';' +
'color: ' + newColor + ';' +
    'border: ' + newBorder + ';';
if(typeof(posElem.style.cssText) != 'undefined') {
    posElem.style.cssText = newStyle;
} else {
    posElem.setAttribute('style', newStyle);
}

What can cause a “Resource temporarily unavailable” on sock send() command

Let'e me give an example:

  1. client connect to server, and send 1MB data to server every 1 second.

  2. server side accept a connection, and then sleep 20 second, without recv msg from client.So the tcp send buffer in the client side will be full.

Code in client side:

#include <arpa/inet.h>
#include <sys/socket.h>
#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#define exit_if(r, ...)                                                                          \
    if (r) {                                                                                     \
        printf(__VA_ARGS__);                                                                     \
        printf("%s:%d error no: %d error msg %s\n", __FILE__, __LINE__, errno, strerror(errno)); \
        exit(1);                                                                                 \
    }

void setNonBlock(int fd) {
    int flags = fcntl(fd, F_GETFL, 0);
    exit_if(flags < 0, "fcntl failed");
    int r = fcntl(fd, F_SETFL, flags | O_NONBLOCK);
    exit_if(r < 0, "fcntl failed");
}

void test_full_sock_buf_1(){
    short port = 8000;
    struct sockaddr_in addr;
    memset(&addr, 0, sizeof addr);
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = INADDR_ANY;


    int fd = socket(AF_INET, SOCK_STREAM, 0);
    exit_if(fd<0, "create socket error");

    int ret = connect(fd, (struct sockaddr *) &addr, sizeof(struct sockaddr));
    exit_if(ret<0, "connect to server error");
    setNonBlock(fd);

    printf("connect to server success");

    const int LEN = 1024 * 1000;
    char msg[LEN];  // 1MB data
    memset(msg, 'a', LEN);

    for (int i = 0; i < 1000; ++i) {
        int len = send(fd, msg, LEN, 0);
        printf("send: %d, erron: %d, %s \n", len, errno, strerror(errno));
        sleep(1);
    }

}

int main(){
    test_full_sock_buf_1();

    return 0;
}

Code in server side:

    #include <arpa/inet.h>
    #include <sys/socket.h>
    #include <stdio.h>
    #include <errno.h>
    #include <fcntl.h>
    #include <stdlib.h>
    #include <string.h>
    #define exit_if(r, ...)                                                                          \
        if (r) {                                                                                     \
            printf(__VA_ARGS__);                                                                     \
            printf("%s:%d error no: %d error msg %s\n", __FILE__, __LINE__, errno, strerror(errno)); \
            exit(1);                                                                                 \
        }
void test_full_sock_buf_1(){

    int listenfd = socket(AF_INET, SOCK_STREAM, 0);
    exit_if(listenfd<0, "create socket error");

    short port = 8000;
    struct sockaddr_in addr;
    memset(&addr, 0, sizeof addr);
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = INADDR_ANY;

    int r = ::bind(listenfd, (struct sockaddr *) &addr, sizeof(struct sockaddr));
    exit_if(r<0, "bind socket error");

    r = listen(listenfd, 100);
    exit_if(r<0, "listen socket error");

    struct sockaddr_in raddr;
    socklen_t rsz = sizeof(raddr);
    int cfd = accept(listenfd, (struct sockaddr *) &raddr, &rsz);
    exit_if(cfd<0, "accept socket error");

    sockaddr_in peer;
    socklen_t alen = sizeof(peer);
    getpeername(cfd, (sockaddr *) &peer, &alen);

    printf("accept a connection from %s:%d\n", inet_ntoa(peer.sin_addr), ntohs(peer.sin_port));

    printf("but now I will sleep 15 second, then exit");
    sleep(15);
}

Start server side, then start client side.

server side may output:

accept a connection from 127.0.0.1:35764
but now I will sleep 15 second, then exit
Process finished with exit code 0

enter image description here

client side may output:

connect to server successsend: 1024000, erron: 0, Success 
send: 1024000, erron: 0, Success 
send: 1024000, erron: 0, Success 
send: 552190, erron: 0, Success 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 104, Connection reset by peer 
send: -1, erron: 32, Broken pipe 
send: -1, erron: 32, Broken pipe 
send: -1, erron: 32, Broken pipe 
send: -1, erron: 32, Broken pipe 
send: -1, erron: 32, Broken pipe 

enter image description here

You can see, as the server side doesn't recv the data from client, so when the client side tcp buffer get full, but you still send data, so you may get Resource temporarily unavailable error.

C#: easiest way to populate a ListBox from a List

You can also use the AddRange method

listBox1.Items.AddRange(myList.ToArray());

Get: TypeError: 'dict_values' object does not support indexing when using python 3.2.3

In Python 3, dict.values() (along with dict.keys() and dict.items()) returns a view, rather than a list. See the documentation here. You therefore need to wrap your call to dict.values() in a call to list like so:

v = list(d.values())
{names[i]:v[i] for i in range(len(names))}

How to declare a static const char* in your header file?

You need to define static variables in a translation unit, unless they are of integral types.

In your header:

private:
    static const char *SOMETHING;
    static const int MyInt = 8; // would be ok

In the .cpp file:

const char *YourClass::SOMETHING = "something";

C++ standard, 9.4.2/4:

If a static data member is of const integral or const enumeration type, its declaration in the class definition can specify a constant-initializer which shall be an integral constant expression. In that case, the member can appear in integral constant expressions within its scope. The member shall still be defined in a namespace scope if it is used in the program and the namespace scope definition shall not contain an initializer.

Bootstrap 3 Navbar Collapse

The big difference between Bootstrap 2 and Bootstrap 3 is that Bootstrap 3 is "mobile first".

That means the default styles are designed for mobile devices and in the case of Navbars, that means it's "collapsed" by default and "expands" when it reaches a certain minimum size.

Bootstrap 3's site actually has a "hint" as to what to do: http://getbootstrap.com/components/#navbar

Customize the collapsing point

Depending on the content in your navbar, you might need to change the point at which your navbar switches between collapsed and horizontal mode. Customize the @grid-float-breakpoint variable or add your own media query.

If you're going to re-compile your LESS, you'll find the noted LESS variable in the variables.less file. It's currently set to "expand" @media (min-width: 768px) which is a "small screen" (ie. a tablet) by Bootstrap 3 terms.

@grid-float-breakpoint: @screen-tablet;

If you want to keep the collapsed a little longer you can adjust it like such:

@grid-float-breakpoint: @screen-desktop; (992px break-point)

or expand sooner

@grid-float-breakpoint: @screen-phone (480px break-point)

If you want to have it expand later, and not deal with re-compiling the LESS, you'll have to overwrite the styles that get applied at the 768px media query and have them return to the previous value. Then re-add them at the appropriate time.

I'm not sure if there's a better way to do it. Recompiling the Bootstrap LESS to your needs is the best (easiest) way. Otherwise, you'll have to find all the CSS media queries that affect your Navbar, overwrite them to default styles @ the 768px width and then revert them back at a higher min-width.

Recompiling the LESS will do all that magic for you just by changing the variable. Which is pretty much the point of LESS/SASS pre-compilers. =)

(note, I did look them all up, it's about 100 lines of code, which is annoy enough for me to drop the idea and just re-compile Bootstrap for a given project and avoid messing something up by accident)

I hope that helps!

Cheers!

convert strtotime to date time format in php

Here is exp.

$date_search_strtotime = strtotime(date("Y-m-d"));
echo 'Now strtotime date : '.$date_search_strtotime;
echo '<br>';
echo 'Now date from strtotime : '.date('Y-m-d',$date_search_strtotime);

json.dumps vs flask.jsonify

This is flask.jsonify()

def jsonify(*args, **kwargs):
    if __debug__:
        _assert_have_json()
    return current_app.response_class(json.dumps(dict(*args, **kwargs),
        indent=None if request.is_xhr else 2), mimetype='application/json')

The json module used is either simplejson or json in that order. current_app is a reference to the Flask() object i.e. your application. response_class() is a reference to the Response() class.

How to merge 2 List<T> and removing duplicate values from it in C#

Union has not good performance : this article describe about compare them with together

var dict = list2.ToDictionary(p => p.Number);
foreach (var person in list1)
{
        dict[person.Number] = person;
}
var merged = dict.Values.ToList();

Lists and LINQ merge: 4820ms
Dictionary merge: 16ms
HashSet and IEqualityComparer: 20ms
LINQ Union and IEqualityComparer: 24ms

Get URL query string parameters

If you want the whole query string:

$_SERVER["QUERY_STRING"]

check if a number already exist in a list in python

If you want your numbers in ascending order you can add them into a set and then sort the set into an ascending list.

s = set()
if number1 not in s:
  s.add(number1)
if number2 not in s:
  s.add(number2)
...
s = sorted(s)  #Now a list in ascending order

Parse query string in JavaScript

function parseQuery(queryString) {
    var query = {};
    var pairs = (queryString[0] === '?' ? queryString.substr(1) : queryString).split('&');
    for (var i = 0; i < pairs.length; i++) {
        var pair = pairs[i].split('=');
        query[decodeURIComponent(pair[0])] = decodeURIComponent(pair[1] || '');
    }
    return query;
}

Turns query string like hello=1&another=2 into object {hello: 1, another: 2}. From there, it's easy to extract the variable you need.

That said, it does not deal with array cases such as "hello=1&hello=2&hello=3". To work with this, you must check whether a property of the object you make exists before adding to it, and turn the value of it into an array, pushing any additional bits.

How to detect Adblock on my website?

It works fine for me...

<html>
        <head>
            <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
        </head>
        <body>
            <p>If you click on me, I will disappear.</p>
            <p>Click me away!</p>
            <p>Click me too!</p>
            <script>
                var adBlockEnabled = false;
                var adSense = document.createElement('div');
                adSense.innerHTML = '&nbsp;';
                adSense.className = 'adsbox';
                document.body.appendChild(adSense);
                window.setTimeout(function() {
                  if (adSense.offsetHeight === 0) {
                    adBlockEnabled = true;
                  }
                  adSense.remove();
                  if (adBlockEnabled) {
                        alert('Adblock enabled');
                  } else {
                        alert('Adblock disabled or Not installed');
                  }
                }, 100);
            </script>
        </body>
    </html>

Access index of the parent ng-repeat from child ng-repeat

My example code was correct and the issue was something else in my actual code. Still, I know it was difficult to find examples of this so I'm answering it in case someone else is looking.

<div ng-repeat="f in foos">
  <div>
    <div ng-repeat="b in foos.bars">
      <a ng-click="addSomething($parent.$index)">Add Something</a>
    </div>
  </div>
</div>

Filter array to have unique values

As of June 15, 2015 you may use Set() to create a unique array:

var uniqueArray = [...new Set(array)]

For your Example:

var data = ["X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11"]
var newArray = [...new Set(data)]
console.log(newArray)

>> ["X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11"]

Managing large binary files with Git

If the program won't work without the files it seems like splitting them into a separate repo is a bad idea. We have large test suites that we break into a separate repo but those are truly "auxiliary" files.

However, you may be able to manage the files in a separate repo and then use git-submodule to pull them into your project in a sane way. So, you'd still have the full history of all your source but, as I understand it, you'd only have the one relevant revision of your images submodule. The git-submodule facility should help you keep the correct version of the code in line with the correct version of the images.

Here's a good introduction to submodules from Git Book.

How to delete projects in Intellij IDEA 14?

1. Choose project, right click, in context menu, choose Show in Explorer (on Mac, select Reveal in Finder).

enter image description here

2. Choose menu File \ Close Project

enter image description here

3. In Windows Explorer, press Del or Shift+Del for permanent delete.

4. At IntelliJ IDEA startup windows, hover cursor on old project name (what has been deleted) press Del for delelte.

enter image description here

How to format a floating number to fixed width in Python

for x in numbers:
    print "{:10.4f}".format(x)

prints

   23.2300
    0.1233
    1.0000
    4.2230
 9887.2000

The format specifier inside the curly braces follows the Python format string syntax. Specifically, in this case, it consists of the following parts:

  • The empty string before the colon means "take the next provided argument to format()" – in this case the x as the only argument.
  • The 10.4f part after the colon is the format specification.
  • The f denotes fixed-point notation.
  • The 10 is the total width of the field being printed, lefted-padded by spaces.
  • The 4 is the number of digits after the decimal point.

Predict() - Maybe I'm not understanding it

To avoid error, an important point about the new dataset is the name of independent variable. It must be the same as reported in the model. Another way is to nest the two function without creating a new dataset

model <- lm(Coupon ~ Total, data=df)
predict(model, data.frame(Total=c(79037022, 83100656, 104299800)))

Pay attention on the model. The next two commands are similar, but for predict function, the first work the second don't work.

model <- lm(Coupon ~ Total, data=df) #Ok
model <- lm(df$Coupon ~ df$Total) #Ko

Bootstrap datepicker disabling past dates without current date

_x000D_
_x000D_
var nowDate = new Date();_x000D_
var today = new Date(nowDate.getFullYear(), nowDate.getMonth(), nowDate.getDate(), 0, 0, 0, 0);_x000D_
 $('#date').datetimepicker({_x000D_
  startDate: today_x000D_
 });
_x000D_
_x000D_
_x000D_

ImportError: No module named _ssl

On Solaris 11, I had to modify setup.py to include /opt/csw/include/openssl in the SSL include search path.

Uwe

What are the basic rules and idioms for operator overloading?

Common operators to overload

Most of the work in overloading operators is boiler-plate code. That is little wonder, since operators are merely syntactic sugar, their actual work could be done by (and often is forwarded to) plain functions. But it is important that you get this boiler-plate code right. If you fail, either your operator’s code won’t compile or your users’ code won’t compile or your users’ code will behave surprisingly.

Assignment Operator

There's a lot to be said about assignment. However, most of it has already been said in GMan's famous Copy-And-Swap FAQ, so I'll skip most of it here, only listing the perfect assignment operator for reference:

X& X::operator=(X rhs)
{
  swap(rhs);
  return *this;
}

Bitshift Operators (used for Stream I/O)

The bitshift operators << and >>, although still used in hardware interfacing for the bit-manipulation functions they inherit from C, have become more prevalent as overloaded stream input and output operators in most applications. For guidance overloading as bit-manipulation operators, see the section below on Binary Arithmetic Operators. For implementing your own custom format and parsing logic when your object is used with iostreams, continue.

The stream operators, among the most commonly overloaded operators, are binary infix operators for which the syntax specifies no restriction on whether they should be members or non-members. Since they change their left argument (they alter the stream’s state), they should, according to the rules of thumb, be implemented as members of their left operand’s type. However, their left operands are streams from the standard library, and while most of the stream output and input operators defined by the standard library are indeed defined as members of the stream classes, when you implement output and input operations for your own types, you cannot change the standard library’s stream types. That’s why you need to implement these operators for your own types as non-member functions. The canonical forms of the two are these:

std::ostream& operator<<(std::ostream& os, const T& obj)
{
  // write obj to stream

  return os;
}

std::istream& operator>>(std::istream& is, T& obj)
{
  // read obj from stream

  if( /* no valid object of T found in stream */ )
    is.setstate(std::ios::failbit);

  return is;
}

When implementing operator>>, manually setting the stream’s state is only necessary when the reading itself succeeded, but the result is not what would be expected.

Function call operator

The function call operator, used to create function objects, also known as functors, must be defined as a member function, so it always has the implicit this argument of member functions. Other than this, it can be overloaded to take any number of additional arguments, including zero.

Here's an example of the syntax:

class foo {
public:
    // Overloaded call operator
    int operator()(const std::string& y) {
        // ...
    }
};

Usage:

foo f;
int a = f("hello");

Throughout the C++ standard library, function objects are always copied. Your own function objects should therefore be cheap to copy. If a function object absolutely needs to use data which is expensive to copy, it is better to store that data elsewhere and have the function object refer to it.

Comparison operators

The binary infix comparison operators should, according to the rules of thumb, be implemented as non-member functions1. The unary prefix negation ! should (according to the same rules) be implemented as a member function. (but it is usually not a good idea to overload it.)

The standard library’s algorithms (e.g. std::sort()) and types (e.g. std::map) will always only expect operator< to be present. However, the users of your type will expect all the other operators to be present, too, so if you define operator<, be sure to follow the third fundamental rule of operator overloading and also define all the other boolean comparison operators. The canonical way to implement them is this:

inline bool operator==(const X& lhs, const X& rhs){ /* do actual comparison */ }
inline bool operator!=(const X& lhs, const X& rhs){return !operator==(lhs,rhs);}
inline bool operator< (const X& lhs, const X& rhs){ /* do actual comparison */ }
inline bool operator> (const X& lhs, const X& rhs){return  operator< (rhs,lhs);}
inline bool operator<=(const X& lhs, const X& rhs){return !operator> (lhs,rhs);}
inline bool operator>=(const X& lhs, const X& rhs){return !operator< (lhs,rhs);}

The important thing to note here is that only two of these operators actually do anything, the others are just forwarding their arguments to either of these two to do the actual work.

The syntax for overloading the remaining binary boolean operators (||, &&) follows the rules of the comparison operators. However, it is very unlikely that you would find a reasonable use case for these2.

1 As with all rules of thumb, sometimes there might be reasons to break this one, too. If so, do not forget that the left-hand operand of the binary comparison operators, which for member functions will be *this, needs to be const, too. So a comparison operator implemented as a member function would have to have this signature:

bool operator<(const X& rhs) const { /* do actual comparison with *this */ }

(Note the const at the end.)

2 It should be noted that the built-in version of || and && use shortcut semantics. While the user defined ones (because they are syntactic sugar for method calls) do not use shortcut semantics. User will expect these operators to have shortcut semantics, and their code may depend on it, Therefore it is highly advised NEVER to define them.

Arithmetic Operators

Unary arithmetic operators

The unary increment and decrement operators come in both prefix and postfix flavor. To tell one from the other, the postfix variants take an additional dummy int argument. If you overload increment or decrement, be sure to always implement both prefix and postfix versions. Here is the canonical implementation of increment, decrement follows the same rules:

class X {
  X& operator++()
  {
    // do actual increment
    return *this;
  }
  X operator++(int)
  {
    X tmp(*this);
    operator++();
    return tmp;
  }
};

Note that the postfix variant is implemented in terms of prefix. Also note that postfix does an extra copy.2

Overloading unary minus and plus is not very common and probably best avoided. If needed, they should probably be overloaded as member functions.

2 Also note that the postfix variant does more work and is therefore less efficient to use than the prefix variant. This is a good reason to generally prefer prefix increment over postfix increment. While compilers can usually optimize away the additional work of postfix increment for built-in types, they might not be able to do the same for user-defined types (which could be something as innocently looking as a list iterator). Once you got used to do i++, it becomes very hard to remember to do ++i instead when i is not of a built-in type (plus you'd have to change code when changing a type), so it is better to make a habit of always using prefix increment, unless postfix is explicitly needed.

Binary arithmetic operators

For the binary arithmetic operators, do not forget to obey the third basic rule operator overloading: If you provide +, also provide +=, if you provide -, do not omit -=, etc. Andrew Koenig is said to have been the first to observe that the compound assignment operators can be used as a base for their non-compound counterparts. That is, operator + is implemented in terms of +=, - is implemented in terms of -= etc.

According to our rules of thumb, + and its companions should be non-members, while their compound assignment counterparts (+= etc.), changing their left argument, should be a member. Here is the exemplary code for += and +; the other binary arithmetic operators should be implemented in the same way:

class X {
  X& operator+=(const X& rhs)
  {
    // actual addition of rhs to *this
    return *this;
  }
};
inline X operator+(X lhs, const X& rhs)
{
  lhs += rhs;
  return lhs;
}

operator+= returns its result per reference, while operator+ returns a copy of its result. Of course, returning a reference is usually more efficient than returning a copy, but in the case of operator+, there is no way around the copying. When you write a + b, you expect the result to be a new value, which is why operator+ has to return a new value.3 Also note that operator+ takes its left operand by copy rather than by const reference. The reason for this is the same as the reason giving for operator= taking its argument per copy.

The bit manipulation operators ~ & | ^ << >> should be implemented in the same way as the arithmetic operators. However, (except for overloading << and >> for output and input) there are very few reasonable use cases for overloading these.

3 Again, the lesson to be taken from this is that a += b is, in general, more efficient than a + b and should be preferred if possible.

Array Subscripting

The array subscript operator is a binary operator which must be implemented as a class member. It is used for container-like types that allow access to their data elements by a key. The canonical form of providing these is this:

class X {
        value_type& operator[](index_type idx);
  const value_type& operator[](index_type idx) const;
  // ...
};

Unless you do not want users of your class to be able to change data elements returned by operator[] (in which case you can omit the non-const variant), you should always provide both variants of the operator.

If value_type is known to refer to a built-in type, the const variant of the operator should better return a copy instead of a const reference:

class X {
  value_type& operator[](index_type idx);
  value_type  operator[](index_type idx) const;
  // ...
};

Operators for Pointer-like Types

For defining your own iterators or smart pointers, you have to overload the unary prefix dereference operator * and the binary infix pointer member access operator ->:

class my_ptr {
        value_type& operator*();
  const value_type& operator*() const;
        value_type* operator->();
  const value_type* operator->() const;
};

Note that these, too, will almost always need both a const and a non-const version. For the -> operator, if value_type is of class (or struct or union) type, another operator->() is called recursively, until an operator->() returns a value of non-class type.

The unary address-of operator should never be overloaded.

For operator->*() see this question. It's rarely used and thus rarely ever overloaded. In fact, even iterators do not overload it.


Continue to Conversion Operators