Programs & Examples On #Azure

Microsoft Azure (formerly Windows Azure) is a Platform as a Service (PaaS) and Infrastructure as a Service (IaaS) cloud computing platform by Microsoft. Users of the platform can deploy their applications onto cloud hosting benefiting from on-demand service, elastic scale, and a highly managed environment on a pay-as-you-go basis.

How to re-create database for Entity Framework?

This worked for me:

  1. Delete database from SQL Server Object Explorer in Visual Studio. Right-click and select delete.
  2. Delete mdf and ldf files from file system - if they are still there.
  3. Rebuild Solution.
  4. Start Application - database will be re-created.

Could not load file or assembly "System.Net.Http, Version=, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"

Changing the binding information in my web.config (or app.config) - while a "hack" in my view, allows you to move forward with your project after a NuGet package update whacks your application and gives you the System.Net.Http error.

Set oldVersion="" and newVersion="" as follows

    <assemblyIdentity name="System.Net.Http" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
    <bindingRedirect oldVersion="" newVersion="" />

Could not load file or assembly System.Web.Http.WebHost after published to Azure web site

I met the same problem and I resolved it by setting CopyLocal to true for the following libs:


I must add that I use MVC4 and NET 4

Azure SQL Database "DTU percentage" metric

DTU is nothing but a blend of CPU, memory and IO. Why do we need a blend when these 3 are pretty clear? Because we want a unit for power. But it is still confusing in many ways. eg: If I simply increase memory will it increase power(DTU)? If yes, how can DTU be a blend? It is a yes. In this memory-increase case, as per the query in the answer given by jyong, DTU will be equivalent to memory(since we increased it). MS has even a pricing model based on this DTU and it raised many questions.

Because of these confusions and questions, MS wanted to bring in another option. We already had some specs in on-premise, why can't we use them? As a result, 'vCore pricing model' was born. In this model we have visibility to RAM and CPU. But not in DTU model.

The counter argument from DTU would be that DTU measures are calibrated using a benchmark that simulates real-world database workload. And that we are not in on-premise anymore ;). Yes it is designed with cloud computing in mind(but is also used in OLTP workloads).

But that is not all. Now that we are entering the pricing model the equation changes. The question now is about money and the bundle(what all features are included). Here DTU has some advantages(the way I see it) but enterprises with many existing licenses would disagree.

  • DTU has one pricing(Compute + Storage + Backup). Simpler and can start with lower pricing.
  • vCore has different pricing (Compute, Storage). Software assurance is available here. Enterprises will have on-premise licenses, this can be easily ported here(so they get big machines for less price than DTU model). Plus they commit for multiple years and get additional discounts.

We can switch between both when needed so if not sure start with DTU(Basic/Standard/Premium).

How can we know which pricing tier to use? Go to configure menu as given below: (on the right/left you can switch between both) VCore


Even though Vcore is bigger 'machine' and for bigger things, the cost can sometimes be cheaper for enterprise organizations. Here is a proof. DTU costs $147 . But Vcore costs $111. That is because you can commit for 3 years(but still pay monthly) and also because of the license re-use option(enterprises will have on-premise licenses).

Cost DTU

enter image description here

It is a bit too much than answering direct question but I am gonna go ahead and make this complete by answering 'how to choose between different options in DTU let alone choosing between DTU and vCore'. This is answered in this beautiful blog and this flowchart explains it all

enter image description here

Use SQL Server Management Studio to connect remotely to an SQL Server Express instance hosted on an Azure Virtual Machine

I too struggled with something similar. My guess is your actual problem is connecting to a SQL Express instance running on a different machine. The steps to do this can be summarized as follows:

  1. Ensure SQL Express is configured for SQL Authentication as well as Windows Authentication (the default). You do this via SQL Server Management Studio (SSMS) Server Properties/Security
  2. In SSMS create a new login called "sqlUser", say, with a suitable password, "sql", say. Ensure this new login is set for SQL Authentication, not Windows Authentication. SSMS Server Security/Logins/Properties/General. Also ensure "Enforce password policy" is unchecked
  3. Under Properties/Server Roles ensure this new user has the "sysadmin" role
  4. In SQL Server Configuration Manager SSCM (search for SQLServerManagerxx.msc file in Windows\SysWOW64 if you can't find SSCM) under SQL Server Network Configuration/Protocols for SQLExpress make sure TCP/IP is enabled. You can disable Named Pipes if you want
  5. Right-click protocol TCP/IP and on the IPAddresses tab, ensure every one of the IP addresses is set to Enabled Yes, and TCP Port 1433 (this is the default port for SQL Server)
  6. In Windows Firewall (WF.msc) create two new Inbound Rules - one for SQL Server and another for SQL Browser Service. For SQL Server you need to open TCP Port 1433 (if you are using the default port for SQL Server) and very importantly for the SQL Browser Service you need to open UDP Port 1434. Name these two rules suitably in your firewall
  7. Stop and restart the SQL Server Service using either SSCM or the Services.msc snap-in
  8. In the Services.msc snap-in make sure SQL Browser Service Startup Type is Automatic and then start this service

At this point you should be able to connect remotely, using SQL Authentication, user "sqlUser" password "sql" to the SQL Express instance configured as above. A final tip and easy way to check this out is to create an empty text file with the .UDL extension, say "Test.UDL" on your desktop. Double-clicking to edit this file invokes the Microsoft Data Link Properties dialog with which you can quickly test your remote SQL connection

Optimal way to concatenate/aggregate strings

I found Serge's answer to be very promising, but I also encountered performance issues with it as-written. However, when I restructured it to use temporary tables and not include double CTE tables, the performance went from 1 minute 40 seconds to sub-second for 1000 combined records. Here it is for anyone who needs to do this without FOR XML on older versions of SQL Server:

     ID                 INT
    ,VALUE              VARCHAR(MAX) NULL
    ,VALUECOUNT         INT




            ,CTE.VALUE + ' ' + SV.VALUE AS VALUE
    JOIN    CTE 
        ON  SV.ID = CTE.ID


MSOnline can't be imported on PowerShell (Connect-MsolService error)

The solution with copying 32-bit libs over to 64-bit did not work for me. What worked was unchecking Target Platform Prefer 32-bit check mark in project properties.

How do I copy SQL Azure database to my local development server?

Use the Import/Export service in SQL Azure to create a .bacpac file.

Then take a look at this method in another Stack Overflow article.

Azure SQL Database Bacpac Local Restore

ERROR 1064 (42000) in MySQL

Finally got a solution.

First .sql file converts into the UTF8.

Then use this command

mysql -p -u root --default_character_set utf8 test </var/201535.sql

---root is the username

---test is the database name


mysql -p -u root test < /var/201535.sql 

---root is the username

---test is the database name

Microsoft Azure: How to create sub directory in a blob container

There is a comment by @afr0 asking how to filter on folders..

There is two ways using the GetDirectoryReference or looping through a containers blobs and checking the type. The code below is in C#

CloudBlobContainer container = blobClient.GetContainerReference("photos");

//Method 1. grab a folder reference directly from the container
CloudBlobDirectory folder = container.GetDirectoryReference("directoryName");

//Method 2. Loop over container and grab folders.
foreach (IListBlobItem item in container.ListBlobs(null, false))
    if (item.GetType() == typeof(CloudBlobDirectory))
        // we know this is a sub directory now
        CloudBlobDirectory subFolder = (CloudBlobDirectory)item;

        Console.WriteLine("Directory: {0}", subFolder.Uri);

read this for more in depth coverage:

'Connect-MsolService' is not recognized as the name of a cmdlet

All links to the Azure Active Directory Connection page now seem to be invalid.

I had an older version of Azure AD installed too, this is what worked for me. Install this.

Run these in an elevated PS session:

uninstall-module AzureAD  # this may or may not be needed
install-module AzureAD
install-module AzureADPreview
install-module MSOnline

I was then able to log in and run what I needed.

Sending email from Azure

A nice way to achieve this "if you have an office 365 account" is to use Office 365 outlook connector integrated with Azure Logic App,

Hope this helps someone!

Where is the Microsoft.IdentityModel dll

In Windows 8.1 64bit, look under C:\Windows\ADFS

How do I create a new user in a SQL Azure database?

create a user and then add user to a specific role:

CREATE USER [test] WITH PASSWORD=N'<strong password>'
ALTER ROLE [db_datareader] ADD MEMBER [test]

How is VIP swapping + CNAMEs better than IP swapping + A records?

A VIP swap is an internal change to Azure's routers/load balancers, not an external DNS change. They're just routing traffic to go from one internal [set of] server[s] to another instead. Therefore the DNS info for doesn't change at all. Therefore the change for people accessing via the IP bound to (and CNAME'd by you) will see the change as soon as the VIP swap is complete.

Install-Module : The term 'Install-Module' is not recognized as the name of a cmdlet

Actually my solution to this problem was much simpler, because I already had the latest version of PowerShell and is still didn't recognize Install-Module command. What fixed the "issue" for me was just typing the command manually, since originally I tried copying the snippet from a website and apparently there was some issue with the formatting when copy&pasting, so when I typed the command manually it installed the module without any problem.

How to view the roles and permissions granted to any database user in Azure SQL server instance?

To view database roles assigned to users, you can use sys.database_role_members

The following query returns the members of the database roles.

SELECT AS DatabaseRoleName,   
    isnull (, 'No members') AS DatabaseUserName   
FROM sys.database_role_members AS DRM  
RIGHT OUTER JOIN sys.database_principals AS DP1  
    ON DRM.role_principal_id = DP1.principal_id  
LEFT OUTER JOIN sys.database_principals AS DP2  
    ON DRM.member_principal_id = DP2.principal_id  
WHERE DP1.type = 'R'

python: how to identify if a variable is an array or a scalar

While, @jamylak's approach is the better one, here is an alternative approach

>>> N=[2,3,5]
>>> P = 5
>>> type(P) in (tuple, list)
>>> type(N) in (tuple, list)

How to get a date in YYYY-MM-DD format from a TSQL datetime field?

One other way...

CONVERT(varchar, DATEPART(yyyy, @datetime)) + '/' + CONVERT(varchar, DATEPART(mm, @datetime)) + '/' + CONVERT(varchar, DATEPART(dd, @datetime)) 

org.hibernate.StaleStateException: Batch update returned unexpected row count from update [0]; actual row count: 0; expected: 1

I had the same as well.Making the Id (0) doing "(your Model value).setId(0)" solved my problem.

Bootstrap4 adding scrollbar to div

.Scroll {
  overflow-y: scroll;
<!DOCTYPE html>
<script src=""></script>

<h1>Smooth Scroll</h1>

<div class="Scroll">
  <div class="main" id="section1">
    <h2>Section 1</h2>
    <p>Click on the link to see the "smooth" scrolling effect.</p>
    <p>Note: Remove the scroll-behavior property to remove smooth scrolling.</p>
  <div class="main" id="section2">
    <h2>Section 2</h2>
    <p>Knowing how to write a paragraph is incredibly important. It’s a basic aspect of writing, and it is something that everyone should know how to do. There is a specific structure that you have to follow when you’re writing a paragraph. This structure helps make it easier for the reader to understand what is going on. Through writing good paragraphs, a person can communicate a lot better through their writing.</p>
  <div class="main" id="section3">
    <h2>Section 3</h2>
    <p>Knowing how to write a paragraph is incredibly important. It’s a basic aspect of writing, and it is something that everyone should know how to do. There is a specific structure that you have to follow when you’re writing a paragraph. This structure helps make it easier for the reader to understand what is going on. Through writing good paragraphs, a person can communicate a lot better through their writing.</p>
  <div class="main" id="section4">
    <h2>Section 4</h2>
    <p>Knowing how to write a paragraph is incredibly important. It’s a basic aspect of writing, and it is something that everyone should know how to do. There is a specific structure that you have to follow when you’re writing a paragraph. This structure helps make it easier for the reader to understand what is going on. Through writing good paragraphs, a person can communicate a lot better through their writing.</p>

  <div class="main" id="section5">
    <h2>Section 5</h2>
    <a href="#section1">Click Me to Smooth Scroll to Section 1 Above</a>
  <div class="main" id="section6">
    <h2>Section 6</h2>
    <p>Knowing how to write a paragraph is incredibly important. It’s a basic aspect of writing, and it is something that everyone should know how to do. There is a specific structure that you have to follow when you’re writing a paragraph. This structure helps make it easier for the reader to understand what is going on. Through writing good paragraphs, a person can communicate a lot better through their writing.</p>
  <div class="main" id="section7">
    <h2>Section 7</h2>
    <a href="#section1">Click Me to Smooth Scroll to Section 1 Above</a>

A message body writer for Java type, class myPackage.B, and MIME media type, application/octet-stream, was not found

This solved my issue.

Including following dependencies in your POM.xml and run Maven -> Update also fixed my issue.


How to install JRE 1.7 on Mac OS X and use it with Eclipse?

Try editing your eclipse.ini file and add the following at the top


Of course the path may be slightly different, looks like I have an older version...

I'm not sure if it will add itself automatically. If not go into

Preferences --> Java --> Installed JREs

Click Add and follow the instructions there to add it

Can we call the function written in one JavaScript in another JS file?

As long as both are referenced by the web page, yes.

You simply call the functions as if they are in the same JS file.

Java : Comparable vs Comparator

When your class implements Comparable, the compareTo method of the class is defining the "natural" ordering of that object. That method is contractually obligated (though not demanded) to be in line with other methods on that object, such as a 0 should always be returned for objects when the .equals() comparisons return true.

A Comparator is its own definition of how to compare two objects, and can be used to compare objects in a way that might not align with the natural ordering.

For example, Strings are generally compared alphabetically. Thus the "a".compareTo("b") would use alphabetical comparisons. If you wanted to compare Strings on length, you would need to write a custom comparator.

In short, there isn't much difference. They are both ends to similar means. In general implement comparable for natural order, (natural order definition is obviously open to interpretation), and write a comparator for other sorting or comparison needs.

Add Legend to Seaborn point plot

I would suggest not to use seaborn pointplot for plotting. This makes things unnecessarily complicated.
Instead use matplotlib plot_date. This allows to set labels to the plots and have them automatically put into a legend with ax.legend().

import matplotlib.pyplot as plt
import pandas as pd
import seaborn as sns
import numpy as np

date = pd.date_range("2017-03", freq="M", periods=15)
count = np.random.rand(15,4)
df1 = pd.DataFrame({"date":date, "count" : count[:,0]})
df2 = pd.DataFrame({"date":date, "count" : count[:,1]+0.7})
df3 = pd.DataFrame({"date":date, "count" : count[:,2]+2})

f, ax = plt.subplots(1, 1)
y_col = 'count'

ax.plot_date(, df1["count"], color="blue", label="A", linestyle="-")
ax.plot_date(, df2["count"], color="red", label="B", linestyle="-")
ax.plot_date(, df3["count"], color="green", label="C", linestyle="-")



enter image description here

In case one is still interested in obtaining the legend for pointplots, here a way to go:


ax.legend(handles=ax.lines[::len(df1)+1], labels=["A","B","C"])

ax.set_xticklabels([t.get_text().split("T")[0] for t in ax.get_xticklabels()])

Adding calculated column(s) to a dataframe in pandas

For the second part of your question, you can also use shift, for example:

df['t-1'] = df['t'].shift(1)

t-1 would then contain the values from t one row above.

Can't load AMD 64-bit .dll on a IA 32-bit platform

If you are still getting that error after installing the 64 bit JRE, it means that the JVM running Gurobi package is still using the 32 bit JRE.

Check that you have updated the PATH and JAVA_HOME globally and in the command shell that you are using. (Maybe you just need to exit and restart it.)

Check that your command shell runs the right version of Java by running "java -version" and checking that it says it is a 64bit JRE.

If you are launching the example via a wrapper script / batch file, make sure that the script is using the right JRE. Modify as required ...

Ruby's gives "No such file or directory - text.txt (Errno::ENOENT)" error

Try using


To see what's in the directory (and therefore what directory it's looking at).

How to make an app's background image repeat

Ok, here's what I've got in my app. It includes a hack to prevent ListViews from going black while scrolling.


<?xml version="1.0" encoding="utf-8"?>
    <bitmap xmlns:android=""
        android:tileMode="repeat" />


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

  <style name="app_theme" parent="android:Theme">
    <item name="android:windowBackground">@drawable/app_background</item>
    <item name="android:listViewStyle">@style/TransparentListView</item>
    <item name="android:expandableListViewStyle">@style/TransparentExpandableListView</item>

  <style name="TransparentListView" parent="@android:style/Widget.ListView">
    <item name="android:cacheColorHint">@android:color/transparent</item>

  <style name="TransparentExpandableListView" parent="@android:style/Widget.ExpandableListView">
    <item name="android:cacheColorHint">@android:color/transparent</item>



<application android:theme="@style/app_theme">

How can I print a circular structure in a JSON-like format?

I know this is an old question, but I'd like to suggest an NPM package I've created called smart-circular, which works differently from the other ways proposed. It's specially useful if you're using big and deep objects.

Some features are:

  • Replacing circular references or simply repeated structures inside the object by the path leading to its first occurrence (not just the string [circular]);

  • By looking for circularities in a breadth-first search, the package ensures this path is as small as possible, which is important when dealing with very big and deep objects, where the paths can get annoyingly long and difficult to follow (the custom replacement in JSON.stringify does a DFS);

  • Allows personalised replacements, handy to simplify or ignore less important parts of the object;

  • Finally, the paths are written exactly in the way necessary to access the field referenced, which can help you debugging.

How to change an Android app's name?

There's the android:label for the application, and the android:label for the launch activity. The former is what you see under Settings -> Applications -> Manage Applications on your device. The latter is what you see under Applications, and by extension in any shortcut to your application, e.g.

    android:label="@string/turns_up_in_manage_apps" >
        android:label="@string/turns_up_in_shortcuts" >

How to read value of a registry key c#

You need to first add using Microsoft.Win32; to your code page.

Then you can begin to use the Registry classes:

    using (RegistryKey key = Registry.LocalMachine.OpenSubKey("Software\\Wow6432Node\\MySQL AB\\MySQL Connector\\Net"))
        if (key != null)
            Object o = key.GetValue("Version");
            if (o != null)
                Version version = new Version(o as String);  //"as" because it's REG_SZ...otherwise ToString() might be safe(r)
                //do what you like with version
catch (Exception ex)  //just for's always best to handle specific exceptions
    //react appropriately

BEWARE: unless you have administrator access, you are unlikely to be able to do much in LOCAL_MACHINE. Sometimes even reading values can be a suspect operation without admin rights.

How to add time to DateTime in SQL

You can do:

SELECT GETDATE()+'03:30:00'

Why can't I make a vector of references?

yes you can, look for std::reference_wrapper, that mimics a reference but is assignable and also can be "reseated"

How can I set a UITableView to grouped style

You can use:

(instancetype)init {
return [[YourSubclassOfTableView alloc] initWithStyle:UITableViewStyleGrouped];

openCV video saving in python

Please make sure to set correct width and height. You can set it like bellow

cv2.VideoWriter('output.avi', fourcc, 20.0, (int(cap.get(3)), int(cap.get(4))))

What does AND 0xFF do?

Anding an integer with 0xFF leaves only the least significant byte. For example, to get the first byte in a short s, you can write s & 0xFF. This is typically referred to as "masking". If byte1 is either a single byte type (like uint8_t) or is already less than 256 (and as a result is all zeroes except for the least significant byte) there is no need to mask out the higher bits, as they are already zero.

See tristopiaPatrick Schlüter's answer below when you may be working with signed types. When doing bitwise operations, I recommend working only with unsigned types.

Function that creates a timestamp in c#

You could use the DateTime.Ticks property, which is a long and universal storable, always increasing and usable on the compact framework as well. Just make sure your code isn't used after December 31st 9999 ;)

Unicode, UTF, ASCII, ANSI format differences

Going down your list:

  • "Unicode" isn't an encoding, although unfortunately, a lot of documentation imprecisely uses it to refer to whichever Unicode encoding that particular system uses by default. On Windows and Java, this often means UTF-16; in many other places, it means UTF-8. Properly, Unicode refers to the abstract character set itself, not to any particular encoding.
  • UTF-16: 2 bytes per "code unit". This is the native format of strings in .NET, and generally in Windows and Java. Values outside the Basic Multilingual Plane (BMP) are encoded as surrogate pairs. These used to be relatively rarely used, but now many consumer applications will need to be aware of non-BMP characters in order to support emojis.
  • UTF-8: Variable length encoding, 1-4 bytes per code point. ASCII values are encoded as ASCII using 1 byte.
  • UTF-7: Usually used for mail encoding. Chances are if you think you need it and you're not doing mail, you're wrong. (That's just my experience of people posting in newsgroups etc - outside mail, it's really not widely used at all.)
  • UTF-32: Fixed width encoding using 4 bytes per code point. This isn't very efficient, but makes life easier outside the BMP. I have a .NET Utf32String class as part of my MiscUtil library, should you ever want it. (It's not been very thoroughly tested, mind you.)
  • ASCII: Single byte encoding only using the bottom 7 bits. (Unicode code points 0-127.) No accents etc.
  • ANSI: There's no one fixed ANSI encoding - there are lots of them. Usually when people say "ANSI" they mean "the default locale/codepage for my system" which is obtained via Encoding.Default, and is often Windows-1252 but can be other locales.

There's more on my Unicode page and tips for debugging Unicode problems.

The other big resource of code is which contains more information than you'll ever be able to work your way through - possibly the most useful bit is the code charts.

Angular2 multiple router-outlet in the same template

yes you can, but you need to use aux routing. you will need to give a name to your router-outlet:

<router-outlet name="auxPathName"></router-outlet>

and setup your route config:

  {path:'/', name: 'RetularPath', component: OneComponent, useAsDefault: true},
  {aux:'/auxRoute', name: 'AuxPath', component: SecondComponent}

Check out this example, and also this video.

Update for RC.5 Aux routes has changed a bit: in your router outlet use a name:

<router-outlet name="aux">

In your router config:

{path: '/auxRouter', component: secondComponentComponent, outlet: 'aux'}

HttpServletRequest get JSON POST data

Are you posting from a different source (so different port, or hostname)? If so, this very very recent topic I just answered might be helpful.

The problem was the XHR Cross Domain Policy, and a useful tip on how to get around it by using a technique called JSONP. The big downside is that JSONP does not support POST requests.

I know in the original post there is no mention of JavaScript, however JSON is usually used for JavaScript so that's why I jumped to that conclusion

How to secure an ASP.NET Web API

I would suggest starting with the most straightforward solutions first - maybe simple HTTP Basic Authentication + HTTPS is enough in your scenario.

If not (for example you cannot use https, or need more complex key management), you may have a look at HMAC-based solutions as suggested by others. A good example of such API would be Amazon S3 (

I wrote a blog post about HMAC based authentication in ASP.NET Web API. It discusses both Web API service and Web API client and the code is available on bitbucket.

Here is a post about Basic Authentication in Web API:

Remember that if you are going to provide an API to 3rd parties, you will also most likely be responsible for delivering client libraries. Basic authentication has a significant advantage here as it is supported on most programming platforms out of the box. HMAC, on the other hand, is not that standardized and will require custom implementation. These should be relatively straightforward but still require work.

PS. There is also an option to use HTTPS + certificates.

Are HTTPS headers encrypted?

HTTP version 1.1 added a special HTTP method, CONNECT - intended to create the SSL tunnel, including the necessary protocol handshake and cryptographic setup.
The regular requests thereafter all get sent wrapped in the SSL tunnel, headers and body inclusive.

Checking for empty queryset in Django

If you have a huge number of objects, this can (at times) be much faster:

    # If you get here, it exists...
except IndexError:
    # Doesn't exist!

On a project I'm working on with a huge database, not orgs is 400+ ms and orgs.count() is 250ms. In my most common use cases (those where there are results), this technique often gets that down to under 20ms. (One case I found, it was 6.)

Could be much longer, of course, depending on how far the database has to look to find a result. Or even faster, if it finds one quickly; YMMV.

EDIT: This will often be slower than orgs.count() if the result isn't found, particularly if the condition you're filtering on is a rare one; as a result, it's particularly useful in view functions where you need to make sure the view exists or throw Http404. (Where, one would hope, people are asking for URLs that exist more often than not.)

Android - SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length

I had the same problem then i fixed it by following code!

  text = (EditText)findViewById(; 

Return a value if no rows are found in Microsoft tSQL

I liked James Jenkins reply with the ISNULL check, but I think he meant IFNULL. ISNULL does not have a second parameter like his syntax, but IFNULL has the second parameter after the expression being checked to substitute if a NULL is found.

how do I give a div a responsive height

I know this is a little late to the party but you could use viewport units


Viewport units: vw, vh, vmin, vmax - CR Length units representing 1% of the viewport size for viewport width (vw), height (vh), the smaller of the two (vmin), or the larger of the two (vmax).


div {_x000D_
/* 25% of viewport */_x000D_
  height: 25vh;_x000D_
  width: 15rem;_x000D_
  background-color: #222;_x000D_
  color: #eee;_x000D_
  font-family: monospace;_x000D_
  padding: 2rem;_x000D_
<div>responsive height</div>

Start HTML5 video at a particular position when loading?

Using a #t=10,20 fragment worked for me.

exception in thread 'main' java.lang.NoClassDefFoundError:

Try doing


and then, if it comes up with no compiler errors (which it should not do because I cannot see any bugs in your programme), then type

java Hello

On linux SUSE or RedHat, how do I load Python 2.7

If you want to install Python 2.7 on Oracle Linux, you can proceed as follows:

Enable the Software Collection in /etc/yum.repos.d/public-yum-ol6.repo.

vim /etc/yum.repos.d/public-yum-ol6.repo

name=Software Collection Library release 1.2 packages for Oracle Linux 6 
    enabled=1 <==============change from 0 to 1

After making this change to the yum repository you can simply run the yum command to install the Python:

yum install gcc libffi libffi-devel python27 python27-python-devel openssl-devel python27-MySQL-python

edit bash_profile with follow variables:

vim ~/.bash_profile
PATH=$PATH:$HOME/bin:/opt/rh/python27/root/usr/bin export PATH
LD_LIBRARY_PATH=/opt/rh/python27/root/usr/lib64 export LD_LIBRARY_PATH
PKG_CONFIG_PATH=/opt/rh/python27/root/usr/lib64/pkgconfig export PKG_CONFIG_PATH

Now you can use python2.7 and pip for install Python modules:

/opt/rh/python27/root/usr/bin/pip install pynacl
/opt/rh/python27/root/usr/bin/python2.7 --version

What exactly does a jar file contain?

A jar file is a zip file with some additional files containing metadata. (Despite the .jar extension, it is in zip format, and any utilities that deal with .zip files are also able to deal with .jar files.)

Jar files can contain any kind of files, but they usually contain class files and supporting configuration files (properties), graphics and other data files needed by the application.

Class files contain compiled Java code, which is executable by the Java Virtual Machine.

Change date format in a Java string

Using the java.time package in Java 8 and later:

String date = "2011-01-18 00:00:00.0";
TemporalAccessor temporal = DateTimeFormatter
    .ofPattern("yyyy-MM-dd HH:mm:ss.S")
    .parse(date); // use parse(date, LocalDateTime::from) to get LocalDateTime
String output = DateTimeFormatter.ofPattern("yyyy-MM-dd").format(temporal);

Generating combinations in c++

A simple way using std::next_permutation:

#include <iostream>
#include <algorithm>
#include <vector>

int main() {
    int n, r;
    std::cin >> n;
    std::cin >> r;

    std::vector<bool> v(n);
    std::fill(v.end() - r, v.end(), true);

    do {
        for (int i = 0; i < n; ++i) {
            if (v[i]) {
                std::cout << (i + 1) << " ";
        std::cout << "\n";
    } while (std::next_permutation(v.begin(), v.end()));
    return 0;

or a slight variation that outputs the results in an easier to follow order:

#include <iostream>
#include <algorithm>
#include <vector>

int main() {
   int n, r;
   std::cin >> n;
   std::cin >> r;

   std::vector<bool> v(n);
   std::fill(v.begin(), v.begin() + r, true);

   do {
       for (int i = 0; i < n; ++i) {
           if (v[i]) {
               std::cout << (i + 1) << " ";
       std::cout << "\n";
   } while (std::prev_permutation(v.begin(), v.end()));
   return 0;

A bit of explanation:

It works by creating a "selection array" (v), where we place r selectors, then we create all permutations of these selectors, and print the corresponding set member if it is selected in in the current permutation of v.

You can implement it if you note that for each level r you select a number from 1 to n.

In C++, we need to 'manually' keep the state between calls that produces results (a combination): so, we build a class that on construction initialize the state, and has a member that on each call returns the combination while there are solutions: for instance

#include <iostream>
#include <iterator>
#include <vector>
#include <cstdlib>

using namespace std;

struct combinations
    typedef vector<int> combination_t;

    // initialize status
   combinations(int N, int R) :
       completed(N < 1 || R > N),
       N(N), R(R)
       for (int c = 1; c <= R; ++c)

   // true while there are more solutions
   bool completed;

   // count how many generated
   int generated;

   // get current and compute next combination
   combination_t next()
       combination_t ret = curr;

       // find what to increment
       completed = true;
       for (int i = R - 1; i >= 0; --i)
           if (curr[i] < N - R + i + 1)
               int j = curr[i] + 1;
               while (i <= R-1)
                   curr[i++] = j++;
               completed = false;

       return ret;


   int N, R;
   combination_t curr;

int main(int argc, char **argv)
    int N = argc >= 2 ? atoi(argv[1]) : 5;
    int R = argc >= 3 ? atoi(argv[2]) : 2;
    combinations cs(N, R);
    while (!cs.completed)
        combinations::combination_t c =;
        copy(c.begin(), c.end(), ostream_iterator<int>(cout, ","));
        cout << endl;
    return cs.generated;

test output:


How does java do modulus calculations with negative numbers?

Both definitions of modulus of negative numbers are in use - some languages use one definition and some the other.

If you want to get a negative number for negative inputs then you can use this:

int r = x % n;
if (r > 0 && x < 0)
    r -= n;

Likewise if you were using a language that returns a negative number on a negative input and you would prefer positive:

int r = x % n;
if (r < 0)
    r += n;

Getting the PublicKeyToken of .Net assemblies

An alternate method would be if you have decompiler, just look it up in there, they usually provide the public key. I have looked at .Net Reflector, Telerik Just Decompile and ILSpy just decompile they seem to have the public key token displayed.

.trim() in JavaScript not working in IE

This issue can be caused by IE using compatibility mode on intranet sites. There are two ways to resolve this, you can either update IE to not use compatibility mode on your local machine (in IE11: Tools-> Compatibility View Settings -> Uncheck Display intranet sites in Compatibility View)

Better yet you can update the meta tags in your webpage. Add in:

   <meta http-equiv="X-UA-Compatible" content="IE=edge">

What does this mean? It is telling IE to use the latest compatibility mode. More information is available in MSDN: Specifying legacy document modes

Align button to the right

You can also use like below code.

<button style="position: absolute; right: 0;">Button</button>

Linux command for extracting war file?

Using unzip

unzip -c whatever.war META-INF/MANIFEST.MF  

It will print the output in terminal.

And for extracting all the files,

 unzip whatever.war

Using jar

jar xvf test.war

Note! The jar command will extract war contents to current directory. Not to a subdirectory (like Tomcat does).

Laravel Eloquent inner join with multiple conditions

You can see the following code to solved the problem

return $query->join('kg_shops', function($join)
    $join->on('', '=', 'kg_feeds.shop_id');
    $join->where('','=', 1);

Or another way to solved it

 return $query->join('kg_shops', function($join)
    $join->on('', '=', 'kg_feeds.shop_id');
    $join->on('','=', DB::raw('1'));

Using a dispatch_once singleton model in Swift

I required my singleton to allow inheritance, and none of these solutions actually allowed it. So I came up with this:

public class Singleton {
    private static var sharedInstanceVar = Singleton()

    public class func sharedInstance() -> Singleton {
        return sharedInstanceVar

public class SubSingleton: Singleton {

    private static var sharedInstanceToken: dispatch_once_t = 0

    public class override func sharedInstance() -> SubSingleton {
        dispatch_once(&sharedInstanceToken) {
            sharedInstanceVar = SubSingleton()
    return sharedInstanceVar as! SubSingleton
  • This way when doing Singleton.sharedInstance() first it will return the instance of Singleton
  • When doing SubSingleton.sharedInstance() first it will return the instance of SubSingleton created.
  • If the above is done, then SubSingleton.sharedInstance() is Singleton is true and the same instance is used.

The issue with this first dirty approach is that I cannot guarantee that subclasses would implement the dispatch_once_t and make sure that sharedInstanceVar is only modified once per class.

I will try to refine this further, but it would be interesting to see if anyone has strong feelings against this (besides the fact that it is verbose and requires to manually update it).

mysql extract year from date format

try this code:


Jenkins, specifying JAVA_HOME

On CentOS 6.x and Redhat 6.x systems, the openjdk-devel package contains the jdk. It's sensible enough if you are familiar with the -devel pattern used in RedHat, but confusing if you're looking for a jdk package that conforms to java naming standards.

I/O error(socket error): [Errno 111] Connection refused

Its seems that server is not running properly so ensure that with terminal by

telnet ip port


telnet localhost 8069

It will return connected to localhost so it indicates that there is no problem with the connection Else it will return Connection refused it indicates that there is problem with the connection

Updating records codeigniter

In your Controller

public function updtitle() 
    $data = array(
        'table_name' => 'your_table_name_to_update', // pass the real table name
        'id' => $this->input->post('id'),
        'title' => $this->input->post('title')

    $this->load->model('Updmodel'); // load the model first
    if($this->Updmodel->upddata($data)) // call the method from the model
        // update successful
        // update not successful


In Your Model

public function upddata($data) {
    $this->db->where('emp_no', $id);
    $this->db->update($table_name, array('title' => $title));
    return true;

The active record query is similar to

"update $table_name set title='$title' where emp_no=$id"

Returning first x items from array

A more object oriented way would be to provide a range to the #[] method. For instance:

Say you want the first 3 items from an array.

numbers = [1,2,3,4,5,6]

numbers[0..2] # => [1,2,3]

Say you want the first x items from an array.


The great thing about this method is if you ask for more items than the array has, it simply returns the entire array.

numbers[0..100] # => [1,2,3,4,5,6]

How to read pdf file and write it to outputStream

You can use PdfBox from Apache which is simple to use and has good performance.

Here is an example of extracting text from a PDF file (you can read more here) :

import org.apache.pdfbox.pdmodel.*;
import org.apache.pdfbox.util.*;

public class PDFTest {

 public static void main(String[] args){
 PDDocument pd;
 BufferedWriter wr;
 try {
         File input = new File("C:\\Invoice.pdf");  // The PDF file from where you would like to extract
         File output = new File("C:\\SampleText.txt"); // The text file where you are going to store the extracted data
         pd = PDDocument.load(input);
         System.out.println(pd.isEncrypted());"CopyOfInvoice.pdf"); // Creates a copy called "CopyOfInvoice.pdf"
         PDFTextStripper stripper = new PDFTextStripper();
         wr = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(output)));
         stripper.writeText(pd, wr);
         if (pd != null) {
        // I use close() to flush the stream.
 } catch (Exception e){


You can get the text using PDFTextStripper:

PDFTextStripper reader = new PDFTextStripper();
String pageText = reader.getText(pd); // PDDocument object created

Create a list with initial capacity in Python

The Pythonic way for this is:

x = [None] * numElements

Or whatever default value you wish to prepopulate with, e.g.

bottles = [Beer()] * 99
sea = [Fish()] * many
vegetarianPizzas = [None] * peopleOrderingPizzaNotQuiche

(Caveat Emptor: The [Beer()] * 99 syntax creates one Beer and then populates an array with 99 references to the same single instance)

Python's default approach can be pretty efficient, although that efficiency decays as you increase the number of elements.


import time

class Timer(object):
    def __enter__(self):
        self.start = time.time()
        return self

    def __exit__(self, *args):
        end = time.time()
        secs = end - self.start
        msecs = secs * 1000  # Millisecs
        print('%fms' % msecs)

Elements   = 100000
Iterations = 144

print('Elements: %d, Iterations: %d' % (Elements, Iterations))

def doAppend():
    result = []
    i = 0
    while i < Elements:
        i += 1

def doAllocate():
    result = [None] * Elements
    i = 0
    while i < Elements:
        result[i] = i
        i += 1

def doGenerator():
    return list(i for i in range(Elements))

def test(name, fn):
    print("%s: " % name, end="")
    with Timer() as t:
        x = 0
        while x < Iterations:
            x += 1

test('doAppend', doAppend)
test('doAllocate', doAllocate)
test('doGenerator', doGenerator)


#include <vector>
typedef std::vector<unsigned int> Vec;

static const unsigned int Elements = 100000;
static const unsigned int Iterations = 144;

void doAppend()
    Vec v;
    for (unsigned int i = 0; i < Elements; ++i) {

void doReserve()
    Vec v;
    for (unsigned int i = 0; i < Elements; ++i) {

void doAllocate()
    Vec v;
    for (unsigned int i = 0; i < Elements; ++i) {
        v[i] = i;

#include <iostream>
#include <chrono>
using namespace std;

void test(const char* name, void(*fn)(void))
    cout << name << ": ";

    auto start = chrono::high_resolution_clock::now();
    for (unsigned int i = 0; i < Iterations; ++i) {
    auto end = chrono::high_resolution_clock::now();

    auto elapsed = end - start;
    cout << chrono::duration<double, milli>(elapsed).count() << "ms\n";

int main()
    cout << "Elements: " << Elements << ", Iterations: " << Iterations << '\n';

    test("doAppend", doAppend);
    test("doReserve", doReserve);
    test("doAllocate", doAllocate);

On my Windows 7 Core i7, 64-bit Python gives

Elements: 100000, Iterations: 144
doAppend: 3587.204933ms
doAllocate: 2701.154947ms
doGenerator: 1721.098185ms

While C++ gives (built with Microsoft Visual C++, 64-bit, optimizations enabled)

Elements: 100000, Iterations: 144
doAppend: 74.0042ms
doReserve: 27.0015ms
doAllocate: 5.0003ms

C++ debug build produces:

Elements: 100000, Iterations: 144
doAppend: 2166.12ms
doReserve: 2082.12ms
doAllocate: 273.016ms

The point here is that with Python you can achieve a 7-8% performance improvement, and if you think you're writing a high-performance application (or if you're writing something that is used in a web service or something) then that isn't to be sniffed at, but you may need to rethink your choice of language.

Also, the Python code here isn't really Python code. Switching to truly Pythonesque code here gives better performance:

import time

class Timer(object):
    def __enter__(self):
        self.start = time.time()
        return self

    def __exit__(self, *args):
        end = time.time()
        secs = end - self.start
        msecs = secs * 1000  # millisecs
        print('%fms' % msecs)

Elements   = 100000
Iterations = 144

print('Elements: %d, Iterations: %d' % (Elements, Iterations))

def doAppend():
    for x in range(Iterations):
        result = []
        for i in range(Elements):

def doAllocate():
    for x in range(Iterations):
        result = [None] * Elements
        for i in range(Elements):
            result[i] = i

def doGenerator():
    for x in range(Iterations):
        result = list(i for i in range(Elements))

def test(name, fn):
    print("%s: " % name, end="")
    with Timer() as t:

test('doAppend', doAppend)
test('doAllocate', doAllocate)
test('doGenerator', doGenerator)

Which gives

Elements: 100000, Iterations: 144
doAppend: 2153.122902ms
doAllocate: 1346.076965ms
doGenerator: 1614.092112ms

(in 32-bit, doGenerator does better than doAllocate).

Here the gap between doAppend and doAllocate is significantly larger.

Obviously, the differences here really only apply if you are doing this more than a handful of times or if you are doing this on a heavily loaded system where those numbers are going to get scaled out by orders of magnitude, or if you are dealing with considerably larger lists.

The point here: Do it the Pythonic way for the best performance.

But if you are worrying about general, high-level performance, Python is the wrong language. The most fundamental problem being that Python function calls has traditionally been up to 300x slower than other languages due to Python features like decorators, etc. (PythonSpeed/PerformanceTips, Data Aggregation).

Access host database from a docker container

Use host.docker.internal from Docker 18.03 onwards.

Add new item in existing array in

Very old question, but still wanted to add this.

If you're looking for a one-liner, you can use the code below. It combines the list constructor that accepts an enumerable and the "new" (since question raised) initializer syntax.

myArray = new List<string>(myArray) { "add this" }.ToArray();

use std::fill to populate vector with increasing numbers

I created a simple templated function, Sequence(), for generating sequences of numbers. The functionality follows the seq() function in R (link). The nice thing about this function is that it works for generating a variety of number sequences and types.

#include <iostream>
#include <vector>

template <typename T>
std::vector<T> Sequence(T min, T max, T by) {
  size_t n_elements = ((max - min) / by) + 1;
  std::vector<T> vec(n_elements);
  min -= by;
  for (size_t i = 0; i < vec.size(); ++i) {
    min += by;
    vec[i] = min;
  return vec;

Example usage:

int main()
    auto vec = Sequence(0., 10., 0.5);
    for(auto &v : vec) {
        std::cout << v << std::endl;

The only caveat is that all of the numbers should be of the same inferred type. In other words, for doubles or floats, include decimals for all of the inputs, as shown.

Updated: June 14, 2018

How to convert ‘false’ to 0 and ‘true’ to 1 in Python

Here's a yet another solution to your problem:

def to_bool(s):
    return 1 - sum(map(ord, s)) % 2
    # return 1 - sum(s.encode('ascii')) % 2  # Alternative for Python 3

It works because the sum of the ASCII codes of 'true' is 448, which is even, while the sum of the ASCII codes of 'false' is 523 which is odd.

The funny thing about this solution is that its result is pretty random if the input is not one of 'true' or 'false'. Half of the time it will return 0, and the other half 1. The variant using encode will raise an encoding error if the input is not ASCII (thus increasing the undefined-ness of the behaviour).

Seriously, I believe the most readable, and faster, solution is to use an if:

def to_bool(s):
    return 1 if s == 'true' else 0

See some microbenchmarks:

In [14]: def most_readable(s):
    ...:     return 1 if s == 'true' else 0

In [15]: def int_cast(s):
    ...:     return int(s == 'true')

In [16]: def str2bool(s):
    ...:     try:
    ...:         return ['false', 'true'].index(s)
    ...:     except (ValueError, AttributeError):
    ...:         raise ValueError()

In [17]: def str2bool2(s):
    ...:     try:
    ...:         return ('false', 'true').index(s)
    ...:     except (ValueError, AttributeError):
    ...:         raise ValueError()

In [18]: def to_bool(s):
    ...:     return 1 - sum(s.encode('ascii')) % 2

In [19]: %timeit most_readable('true')
10000000 loops, best of 3: 112 ns per loop

In [20]: %timeit most_readable('false')
10000000 loops, best of 3: 109 ns per loop

In [21]: %timeit int_cast('true')
1000000 loops, best of 3: 259 ns per loop

In [22]: %timeit int_cast('false')
1000000 loops, best of 3: 262 ns per loop

In [23]: %timeit str2bool('true')
1000000 loops, best of 3: 343 ns per loop

In [24]: %timeit str2bool('false')
1000000 loops, best of 3: 325 ns per loop

In [25]: %timeit str2bool2('true')
1000000 loops, best of 3: 295 ns per loop

In [26]: %timeit str2bool2('false')
1000000 loops, best of 3: 277 ns per loop

In [27]: %timeit to_bool('true')
1000000 loops, best of 3: 607 ns per loop

In [28]: %timeit to_bool('false')
1000000 loops, best of 3: 612 ns per loop

Notice how the if solution is at least 2.5x times faster than all the other solutions. It does not make sense to put as a requirement to avoid using ifs except if this is some kind of homework (in which case you shouldn't have asked this in the first place).

When to use MyISAM and InnoDB?

Read about Storage Engines.


The MyISAM storage engine in MySQL.

  • Simpler to design and create, thus better for beginners. No worries about the foreign relationships between tables.
  • Faster than InnoDB on the whole as a result of the simpler structure thus much less costs of server resources. -- Mostly no longer true.
  • Full-text indexing. -- InnoDB has it now
  • Especially good for read-intensive (select) tables. -- Mostly no longer true.
  • Disk footprint is 2x-3x less than InnoDB's. -- As of Version 5.7, this is perhaps the only real advantage of MyISAM.


The InnoDB storage engine in MySQL.

  • Support for transactions (giving you support for the ACID property).
  • Row-level locking. Having a more fine grained locking-mechanism gives you higher concurrency compared to, for instance, MyISAM.
  • Foreign key constraints. Allowing you to let the database ensure the integrity of the state of the database, and the relationships between tables.
  • InnoDB is more resistant to table corruption than MyISAM.
  • Support for large buffer pool for both data and indexes. MyISAM key buffer is only for indexes.
  • MyISAM is stagnant; all future enhancements will be in InnoDB. This was made abundantly clear with the roll out of Version 8.0.

MyISAM Limitations:

  • No foreign keys and cascading deletes/updates
  • No transactional integrity (ACID compliance)
  • No rollback abilities
  • 4,284,867,296 row limit (2^32) -- This is old default. The configurable limit (for many versions) has been 2**56 bytes.
  • Maximum of 64 indexes per table

InnoDB Limitations:

  • No full text indexing (Below-5.6 mysql version)
  • Cannot be compressed for fast, read-only (5.5.14 introduced ROW_FORMAT=COMPRESSED)
  • You cannot repair an InnoDB table

For brief understanding read below links:

  1. MySQL Engines: InnoDB vs. MyISAM – A Comparison of Pros and Cons
  2. MySQL Engines: MyISAM vs. InnoDB
  3. What are the main differences between InnoDB and MyISAM?
  4. MyISAM versus InnoDB
  5. What's the difference between MyISAM and InnoDB?
  6. MySql: MyISAM vs. Inno DB!

How to turn on front flash light programmatically in Android?

You can also use the following code to turn off the flash.

Camera.Parameters params = mCamera.getParameters()

UnicodeEncodeError: 'ascii' codec can't encode character at special name

Try setting the system default encoding as utf-8 at the start of the script, so that all strings are encoded using that.

Example -

import sys

The above should set the default encoding as utf-8 .

How do I import a sql data file into SQL Server?

There is no such thing as importing in MS SQL. I understand what you mean. It is so simple. Whenever you get/have a something.SQL file, you should just double click and it will directly open in your MS SQL Studio.

How do I bottom-align grid elements in bootstrap fluid layout

This is based on cfx's solution, but rather than setting the font size to zero in the parent container to remove the inter-column spaces added because of the display: inline-block and having to reset them, I simply added

.row.row-align-bottom > div {_x000D_
    float: none;_x000D_
    display: inline-block;_x000D_
    vertical-align: bottom;_x000D_
    margin-right: -0.25em;_x000D_

to the column divs to compensate.

How to check if a process is in hang state (Linux)

What do you mean by ‘hang state’? Typically, a process that is unresponsive and using 100% of a CPU is stuck in an endless loop. But there's no way to determine whether that has happened or whether the process might not eventually reach a loop exit state and carry on.

Desktop hang detectors just work by sending a message to the application's event loop and seeing if there's any response. If there's not for a certain amount of time they decide the app has ‘hung’... but it's entirely possible it was just doing something complicated and will come back to life in a moment once it's done. Anyhow, that's not something you can use for any arbitrary process.

Returning JSON from PHP to JavaScript?

There's a JSON section in the PHP's documentation. You'll need PHP 5.2.0 though.

As of PHP 5.2.0, the JSON extension is bundled and compiled into PHP by default.

If you don't, here's the PECL library you can install.

    $arr = array ('a'=>1,'b'=>2,'c'=>3,'d'=>4,'e'=>5);

    echo json_encode($arr); // {"a":1,"b":2,"c":3,"d":4,"e":5}

How to test if JSON object is empty in Java

if you want to check for the json empty case, we can directly use below code

String jsonString = {};
JSONObject jsonObject = new JSONObject(jsonString);
 System.out.println("json is empty");
} else{
 System.out.println("json is not empty");

this may help you.

How to initialize a nested struct?

package main

type    Proxy struct {
        Address string
        Port    string

type Configuration struct {
    Val   string


func main() {

    c := &Configuration{
        Val: "test",
        Proxy: Proxy {
            Address: "addr",
            Port:    "80",


TypeError: only length-1 arrays can be converted to Python scalars while plot showing

The error "only length-1 arrays can be converted to Python scalars" is raised when the function expects a single value but you pass an array instead.

If you look at the call signature of, you'll see that it accepts a single value, not an array. In general, if you want to apply a function that accepts a single element to every element in an array, you can use np.vectorize:

import numpy as np
import matplotlib.pyplot as plt

def f(x):
f2 = np.vectorize(f)
x = np.arange(1, 15.1, 0.1)
plt.plot(x, f2(x))

You can skip the definition of f(x) and just pass to the vectorize function: f2 = np.vectorize(

Note that np.vectorize is just a convenience function and basically a for loop. That will be inefficient over large arrays. Whenever you have the possibility, use truly vectorized functions or methods (like astype(int) as @FFT suggests).

How do I remove background-image in css?

Since in css3 one might set multiple background images setting "none" will only create a new layer and hide nothing.

I have not found a solution yet...

Ajax success event not working

I was returning valid JSON, getting a response of 200 in my "complete" callback, and could see it in the chrome network console... BUT I hadn't specified

dataType: "json"

once I did, unlike the "accepted answer", that actually fixed the problem.

jQuery to retrieve and set selected option value of html select element

Try this


bash: npm: command not found?

I also come here for the same problem, The solution I found is to install npm and then restart the Visual Studio Code

How do I check whether an array contains a string in TypeScript?

The same as in JavaScript, using Array.prototype.indexOf():

console.log(channelArray.indexOf('three') > -1);

Or using ECMAScript 2016 Array.prototype.includes():


Note that you could also use methods like showed by @Nitzan to find a string. However you wouldn't usually do that for a string array, but rather for an array of objects. There those methods were more sensible. For example

const arr = [{foo: 'bar'}, {foo: 'bar'}, {foo: 'baz'}];
console.log(arr.find(e => === 'bar')); // {foo: 'bar'} (first match)
console.log(arr.some(e => === 'bar')); // true
console.log(arr.filter(e => === 'bar')); // [{foo: 'bar'}, {foo: 'bar'}]





Apache could not be started - ServerRoot must be a valid directory and Unable to find the specified module

I had this exact same problem with Xampp portable on Windows 10 Home. I went through all the suggestions and none worked. I did get it working with Windows Firewall Settings and an error on my part.

My pen drive was labelled Drive E on my laptop and Drive F on my Desktop. Once I corrected that using disk partition and changed the drive letter to E for my desktop to windows asked for access for the firewall and everything clicked.

The steps to correct the drive letter were: 1. Hit the windows key and type Partition, "create and format harddisks partitions" should be at the top, hit enter 2. Find the drive you are looking for at the top panel and click on it. 3. Right click on it and select change drive letter and path, click okay 4. Now try to start xampp control panel and start Apache and Mysql 5. if you get the windows firewall click allow.

I can't say this will work but it did for me and is what I added to this discussion. I also think it might have been just the firewall did not allow the oither drive letter.

How to connect to SQL Server database from JavaScript in the browser?

You shouldn´t use client javascript to access databases for several reasons (bad practice, security issues, etc) but if you really want to do this, here is an example:

var connection = new ActiveXObject("ADODB.Connection") ;

var connectionstring="Data Source=<server>;Initial Catalog=<catalog>;User ID=<user>;Password=<password>;Provider=SQLOLEDB";

var rs = new ActiveXObject("ADODB.Recordset");

rs.Open("SELECT * FROM table", connection);


A better way to connect to a sql server would be to use some server side language like PHP, Java, .NET, among others. Client javascript should be used only for the interfaces.

And there are rumors of an ancient legend about the existence of server javascript, but this is another story. ;)

How to compile C++ under Ubuntu Linux?

You should use g++, not gcc, to compile C++ programs.

For this particular program, I just typed

make avishay

and let make figure out the rest. Gives your executable a decent name, too, instead of a.out.

removing html element styles via javascript

The class attribute can contain multiple styles, so you could specify it as

<tr class="row-even highlight">

and do string manipulation to remove 'highlight' from element.className


Using jQuery would make this simpler as you have the methods


that would enable you to toggle highlighting easily

Search and replace in bash using regular expressions

If you are making repeated calls and are concerned with performance, This test reveals the BASH method is ~15x faster than forking to sed and likely any other external process.


P1=$(date +%s)

for i in {1..10000}
   echo $hello | sed s/X//g > /dev/null

P2=$(date +%s)
echo $[$P2-$P1]

for i in {1..10000}
   echo ${hello//X/} > /dev/null

P3=$(date +%s)
echo $[$P3-$P2]

Toolbar overlapping below status bar

According google docs ,we should not use fitsSystemWindows attribute in app theme, it is intended to use in layout files. Using in themes can causes problem in toast messages .

Check Issue here & example of problem caused here

<item name="android:fitsSystemWindows">true</item>

Example of using correct way and which works fine with windowTranslucentStatus as well.

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



<include layout="@layout/toolbar"

    app:menu="@menu/navigation_drawer_menu" />


iOS - Build fails with CocoaPods cannot find header files

If you had the building errors after a "pod install" or a "pod update", it may be that one of your pods have been built with XCode 6.3 while you are still using a previous version.

In my case I had to update my OSX from mavericks to Yosemite to have Xcode 6.3 and solve the problem

Encode/Decode URLs in C++

Another solution is available using Facebook's folly library : folly::uriEscape and folly::uriUnescape.

Uncaught SoapFault exception: [HTTP] Error Fetching http headers

Try to set :

default_socket_timeout = 120

in your php.ini file.

Python match a string with regex

Are you sure you need a regex? It seems that you only need to know if a word is present in a string, so you can do:

>>> line = 'This,is,a,sample,string'
>>> "sample" in line

XPath query to get nth instance of an element

This seems to work:


I go this from "XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition" by Michael Kay.

There is also a note in the "Abbreviated Syntax" section of the XML Path Language specification that provided a clue.

simple custom event

Like has been mentioned already the progress field needs the keyword event

public event EventHandler<Progress> progress;

But I don't think that's where you actually want your event. I think you actually want the event in TestClass. How does the following look? (I've never actually tried setting up static events so I'm not sure if the following will compile or not, but I think this gives you an idea of the pattern you should be aiming for.)

public partial class Form1 : Form
    public Form1()
        TestClass.progress += SetStatus;

    private void SetStatus(object sender, Progress e)
        label1.Text = e.Status;

    private void button1_Click_1(object sender, EventArgs e)


public class TestClass
    public static event EventHandler<Progress> progress; 

    public static void Func()
        //time consuming code
        OnProgress(new Progress("current status"));
        // time consuming code
        OnProgress(new Progress("some new status"));            

    private static void OnProgress(EventArgs e) 
       if (progress != null)
          progress(this, e);

public class Progress : EventArgs
    public string Status { get; private set; }

    private Progress() {}

    public Progress(string status)
        Status = status;

Convert normal Java Array or ArrayList to Json Array in android

For a simple java String Array you should try

String arr_str [] = { "value1`", "value2", "value3" };

JSONArray arr_strJson = new JSONArray(Arrays.asList(arr_str));

If you have an Generic ArrayList of type String like ArrayList<String>. then you should try

 ArrayList<String> obj_list = new ArrayList<>();
  JSONArray arr_strJson = new JSONArray(obj_list));

CSS :not(:last-child):after selector

Remove the : before last-child and the :after and used

 ul li:not(last-child){
 content:' |';

Hopefully,it should work

Getting "unixtime" in Java

Avoid the Date object creation w/ System.currentTimeMillis(). A divide by 1000 gets you to Unix epoch.

As mentioned in a comment, you typically want a primitive long (lower-case-l long) not a boxed object long (capital-L Long) for the unixTime variable's type.

long unixTime = System.currentTimeMillis() / 1000L;

How to write a comment in a Razor view?

Note that in general, IDE's like Visual Studio will markup a comment in the context of the current language, by selecting the text you wish to turn into a comment, and then using the Ctrl+K Ctrl+C shortcut, or if you are using Resharper / Intelli-J style shortcuts, then Ctrl+/.

Server side Comments:

Razor .cshtml

Like so:

@* Comment goes here *@

For those looking for the older .aspx view (and Asp.Net WebForms) server side comment syntax:

<%-- Comment goes here --%>

Client Side Comments

HTML Comment

<!-- Comment goes here -->

Javascript Comment

// One line Comment goes Here
/* Multiline comment
   goes here */

As OP mentions, although not displayed on the browser, client side comments will still be generated for the page / script file on the server and downloaded by the page over HTTP, which unless removed (e.g. minification), will waste I/O, and, since the comment can be viewed by the user by viewing the page source or intercepting the traffic with the browser's Dev Tools or a tool like Fiddler or Wireshark, can also pose a security risk, hence the preference to use server side comments on server generated code (like MVC views or .aspx pages).

.htaccess: Invalid command 'RewriteEngine', perhaps misspelled or defined by a module not included in the server configuration

Also make sure php is enabled by uncommenting the

LoadModule php5_module libexec/apache2/

line that comes right after

LoadModule rewrite_module libexec/apache2/

Make sure both those lines in


are uncommented.

Letsencrypt add domain to existing certificate

this worked for me

 sudo letsencrypt certonly -a webroot --webroot-path=/var/www/html -d -d

How is a tag different from a branch in Git? Which should I use, here?

the simple answer is:

branch: the current branch pointer moves with every commit to the repository


tag: the commit that a tag points doesn't change, in fact the tag is a snapshot of that commit.

Android TextView padding between lines

You can use TextView.setLineSpacing(n,m) function.

calling another method from the main method in java

This is a fundamental understanding in Java, but can be a little tricky to new programmers. Do a little research on the difference between a static and instance method. The basic difference is the instance method do() is only accessible to a instance of the class foo.

You must instantiate (create an instance of) the class, creating an object, that you use to call the instance method.

I have included your example with a couple comments and example.

public class SomeName {

//this is a static method and cannot call an instance method without a object
public static void main(String[] args){

    // can't do this from this static method, no object reference
    // someMethod();

    //create instance of object
    SomeName thisObj = new SomeName();
    //call instance method using object

//instance method
public void someMethod(){
    System.out.print("some message...");

}// end class SomeName

How can I submit a POST form using the <a href="..."> tag?

You have to use Javascript submit function on your form object. Take a look in other functions.

<form action="showMessage.jsp" method="post">
    <a href="javascript:;" onclick="parentNode.submit();"><%=n%></a>
    <input type="hidden" name="mess" value=<%=n%>/>

Cannot open Windows.h in Microsoft Visual Studio

1) Go to C:\Program Files (x86)\Microsoft SDKs\Windows\v7.1A for VS2013

2) Copy the folders Include and Lib (you should check where are your folders in folder windows such as v7.1, v8, v6, etc.)

3) Paste them into C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC

I solved my problems like:

error lnk1104: cannot open file 'kernel32.lib'.
error c1083: Cannot open Windows.h


How do I specify the exit code of a console application in .NET?

Use this code


use 0 as the int if you don't want to return anything.

How to repair COMException error 80040154?

To find the DLL, go to your 64-bit machine and open the registry. Find the key called HKEY_CLASSES_ROOT\CLSID\{681EF637-F129-4AE9-94BB-618937E3F6B6}\InprocServer32. This key will have the filename of the DLL as its default value.

If you solved the problem on your 64-bit machine by recompiling your project for x86, then you'll need to look in the 32-bit portion of the registry instead of in the normal place. This is HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Classes\CLSID\{681EF637-F129-4AE9-94BB-618937E3F6B6}\InprocServer32.

If the DLL is built for 32 bits then you can use it directly on your 32-bit machine. If it's built for 64 bits then you'll have to contact the vendor and get a 32-bit version from them.

When you have the DLL, register it by running c:\windows\system32\regsvr32.exe.

How to store directory files listing into an array?

Running any shell command inside $(...) will help to store the output in a variable. So using that we can convert the files to array with IFS.

IFS=' ' read -r -a array <<< $(ls /path/to/dir)

How to Import 1GB .sql file to WAMP/phpmyadmin

I also face the same problem and strangely changing the values in php.ini did not worked for me. So I found out one more solution which worked for me.

  • Click your Wamp server icon -> MySql -> MySql console
  • Once mysql console is open. Enter your mysql password. and give these commands.

    1. use user_database_name
    2. source c:/your/sql/path/filename.sql

If you still have problems watch this video.

Partial Dependency (Databases)

I hope this explaination gives a more intuitive appeal to dependency than the answers previously given.

Functional Dependency

An analysis of dependency operates on the attribute level, i.e. one or more attribute is determined by another attribute, it comes before the concept of keys. 'The role of a key is based on the concept of determination. 'Determination is the state in which knowing the value of one attribute makes it possible to determine the value of another.' Database Systems 12ed

Functional dependency is when one or more attributes determine one or more attributes. For instance:

Social Security Number -> First Name, Last Name.

However, by definition of functional dependency:

(SSN, First Name) -> Last Name

This is also a valid functional dependency. The determinants (The attribute that which determines another attribution) are called super key.

Full Functional Dependency

Thus, as a subset of functional dependency, there is the concept of full functional dependency, where the bare minimal determinant is considered. We refer those bare minimal determinants collectively as one candidate key (weird linguistic quirk in my opinion, like the concept of vector).

Partial Functional Dependency

However, sometimes one of the attributes in the candidate key is sufficient to determine another attribute(s), BUT not all, in a relation (a table with no rows). That, is when you have a partial functional dependency within a relation.

Easiest way to open a download window without navigating away from the page

Modifying the location of window might cause some issue especially when you have a persistent connection like websocket. So I always resort to good old iframe solution.


<input type="button" onclick="downloadButtonClicked()" value="Download"/>
<iframe style="display:none;" name="hiddenIframe" id="hiddenIframe"></iframe>


function downloadButtonClicked() {
    // Simulate a link click
    var url = 'your_download_url_here';
    var elem = document.createElement('a');
    elem.href = url; = 'hiddenIframe';;

How to debug JavaScript / jQuery event bindings with Firebug or similar tools?

Looks like FireBug crew is working on an EventBug extension. It will add another panel to FireBug - Events.

"The events panel will list all of the event handlers on the page grouped by event type. For each event type you can open up to see the elements the listeners are bound to and summary of the function source." EventBug Rising

Although they cannot say right now when it will be released.

How do I add button on each row in datatable?

Take a Look.

$(document).ready(function () {     
            columns: [
                { 'data': 'ID' },
                { 'data': 'AuthorName' },
                { 'data': 'TotalBook' },
                { 'data': 'DateofBirth' },
                { 'data': 'OccupationEN' },   
                { 'data': null, title: 'Action', wrap: true, "render": function (item) { return '<div class="btn-group"> <button type="button" onclick="set_value(' + item.ID + ')" value="0" class="btn btn-warning" data-toggle="modal" data-target="#myModal">View</button></div>' } },
            bServerSide: true,
            sAjaxSource: 'EmployeeDataHandler.ashx'           

Using command line arguments in VBscript

Set args = Wscript.Arguments

For Each arg In args
  Wscript.Echo arg

From a command prompt, run the script like this:

CSCRIPT MyScript.vbs 1 2 A B "Arg with spaces"

Will give results like this:

Arg with spaces

How to set a border for an HTML div tag

I guess this is where you are pointing at ..

<div id="divActivites" name="divActivites" style="border:thin">
    <textarea id="inActivities" name="inActivities" style="border:solid">

Well. it must be written as border-width:thin

Here you go with the link (click here) check out the different types of Border-styles

you can also set the border width by writing the width in terms of pixels.. (like border-width:1px), minimum width is 1px.

What is the difference between $routeProvider and $stateProvider?

$route: This is used for deep-linking URLs to controllers and views (HTML partials) and watches $location.url() in order to map the path from an existing definition of route.

When we use ngRoute, the route is configured with $routeProvider and when we use ui-router, the route is configured with $stateProvider and $urlRouterProvider.

<div ng-view></div>
        .when('/contact/', {
            templateUrl: 'app/views/core/contact/contact.html',
            controller: 'ContactCtrl'

<div ui-view>
    <div ui-view='abc'></div>
    <div ui-view='abc'></div>
        .state("contact", {
            url: "/contact/",
            templateUrl: '/app/Aisel/Contact/views/contact.html',
            controller: 'ContactCtrl'

File to byte[] in Java

Guava has Files.toByteArray() to offer you. It has several advantages:

  1. It covers the corner case where files report a length of 0 but still have content
  2. It's highly optimized, you get a OutOfMemoryException if trying to read in a big file before even trying to load the file. (Through clever use of file.length())
  3. You don't have to reinvent the wheel.

Optional args in MATLAB functions

There are a few different options on how to do this. The most basic is to use varargin, and then use nargin, size etc. to determine whether the optional arguments have been passed to the function.

% Function that takes two arguments, X & Y, followed by a variable 
% number of additional arguments
function varlist(X,Y,varargin)
   fprintf('Total number of inputs = %d\n',nargin);

   nVarargs = length(varargin);
   fprintf('Inputs in varargin(%d):\n',nVarargs)
   for k = 1:nVarargs
      fprintf('   %d\n', varargin{k})

A little more elegant looking solution is to use the inputParser class to define all the arguments expected by your function, both required and optional. inputParser also lets you perform type checking on all arguments.

How to quit android application programmatically

@Sivi 's answer closes the app. But on return, if you have some child activities, another unfinished activity might be opened. I added noHistory:true to my activities so the app on return starts from MainActivity.


Java Long primitive type maximum limit

It will overflow and wrap around to Long.MIN_VALUE.

Its not too likely though. Even if you increment 1,000,000 times per second it will take about 300,000 years to overflow.

Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. The statement has been terminated

You could set the CommandTimeout property of the SQL Command to allow for the long running SQL transaction.

You might also need to look at the SQL Query that is causing the timeout.

What does $(function() {} ); do?

It's just shorthand for $(document).ready(), as in: $(document).ready(function() { YOUR_CODE_HERE });. Sometimes you have to use it because your function is running before the DOM finishes loading.

Everything is explained here:$(document).ready()

How to call jQuery function onclick?

Please have a look at

$("#submit").click(function () {
var url = $(location).attr('href');
$('#spn_url').html('<strong>' + url + '</strong>');

how to do file upload using jquery serialization

A file cannot be uploaded using AJAX because you cannot access the contents of a file stored on the client computer and send it in the request using javascript. One of the techniques to achieve this is to use hidden iframes. There's a nice jquery form plugin which allows you to AJAXify your forms and it supports file uploads as well. So using this plugin your code will simply look like this:

$(function() {
    $('#ifoftheform').ajaxForm(function(result) {
        alert('the form was successfully processed');

The plugin automatically takes care of subscribing to the submit event of the form, canceling the default submission, serializing the values, using the proper method and handle file upload fields, ...

remove / reset inherited css from an element

you may use this below option.


now , if their any place where you do not want to apply default style you can use 'no_common_style' class as class. ex:

<div class="no_common_style">
  It will not display in red

Python [Errno 98] Address already in use

This happens because you trying to run service at the same port and there is an already running application.

This can happen because your service is not stopped in the process stack. Then you just have to kill this process.

There is no need to install anything here is the one line command to kill all running python processes.

for Linux based OS:


kill -9 $(ps -A | grep python | awk '{print $1}')


kill -9 (ps -A | grep python | awk '{print $1}')

difference between @size(max = value ) and @min(value) @max(value)

@Min and @Max are used for validating numeric fields which could be String(representing number), int, short, byte etc and their respective primitive wrappers.

@Size is used to check the length constraints on the fields.

As per documentation @Size supports String, Collection, Map and arrays while @Min and @Max supports primitives and their wrappers. See the documentation.

What is the best way to add options to a select from a JavaScript object with jQuery?

There's a sorting problem with this solution in Chrome (jQuery 1.7.1) (Chrome sorts object properties by name/number?) So to keep the order (yes, it's object abusing), I changed this:

optionValues0 = {"4321": "option 1", "1234": "option 2"};

to this

optionValues0 = {"1": {id: "4321", value: "option 1"}, "2": {id: "1234", value: "option 2"}};

and then the $.each will look like:

$.each(optionValues0, function(order, object) {
  key =;
  value = object.value;
  $('#mySelect').append($('<option>', { value : key }).text(value));

How to create a .jar file or export JAR in IntelliJ IDEA (like Eclipse Java archive export)?

For Intellij IDEA version 11.0.2

File | Project Structure | Artifacts then you should press alt+insert or click the plus icon and create new artifact choose --> jar --> From modules with dependencies.

Next goto Build | Build artifacts --> choose your artifact.


What is an alternative to execfile in Python 3?

I'm just a newbie here so maybe it's pure luck if I found this :

After trying to run a script from the interpreter prompt >>> with the command


for which I got a "NameError: name 'execfile' is not defined" I tried a very basic

    import filename

it worked well :-)

I hope this can be helpful and thank you all for the great hints, examples and all those masterly commented pieces of code that are a great inspiration for newcomers !

I use Ubuntu 16.014 LTS x64. Python 3.5.2 (default, Nov 17 2016, 17:05:23) [GCC 5.4.0 20160609] on linux

UTF-8 encoding problem in Spring MVC

If you are using Spring MVC version 5 you can set the encoding also using the @GetMapping annotation. Here is an example which sets the content type to JSON and also the encoding type to UTF-8:

@GetMapping(value="/rest/events", produces = "application/json; charset=UTF-8")

More information on the @GetMapping annotation here:

how to call a onclick function in <a> tag?

You should read up on the onclick html attribute and the documentation. Below is what you want.

<a href='#' onclick='"", "myWin", "scrollbars=yes,width=400,height=650"); return false;'>1</a>


How to obtain Signing certificate fingerprint (SHA1) for OAuth 2.0 on Android?

I was so confusing first time, but I propose you final working solution for Windows:

1) Open cmd and go to your Java/jdk/bin directory (just press cd .. to go one folder back and cd NAME_FOLDER to go one folder forward), in my case, final folder: C:\Program Files\Java\jdk1.8.0_73\bin> enter image description here

2) Now type this command keytool -list -v -keystore C:\Users\YOUR_WINDOWS_USER\.android\debug.keystore -alias androiddebugkey -storepass android -keypass android

As result you have to get something like this: enter image description here

Add Expires headers

The easiest way to add these headers is a .htaccess file that adds some configuration to your server. If the assets are hosted on a server that you don't control, there's nothing you can do about it.

Note that some hosting providers will not let you use .htaccess files, so check their terms if it doesn't seem to work.

The HTML5Boilerplate project has an excellent .htaccess file that covers the necessary settings. See the relevant part of the file at their Github repository

These are the important bits

# ----------------------------------------------------------------------
# Expires headers (for better cache control)
# ----------------------------------------------------------------------

# These are pretty far-future expires headers.
# They assume you control versioning with filename-based cache busting
# Additionally, consider that outdated proxies may miscache

# If you don't use filenames to version, lower the CSS and JS to something like
# "access plus 1 week".

<IfModule mod_expires.c>
  ExpiresActive on

# Your document html
  ExpiresByType text/html "access plus 0 seconds"

# Media: images, video, audio
  ExpiresByType audio/ogg "access plus 1 month"
  ExpiresByType image/gif "access plus 1 month"
  ExpiresByType image/jpeg "access plus 1 month"
  ExpiresByType image/png "access plus 1 month"
  ExpiresByType video/mp4 "access plus 1 month"
  ExpiresByType video/ogg "access plus 1 month"
  ExpiresByType video/webm "access plus 1 month"

# CSS and JavaScript
  ExpiresByType application/javascript "access plus 1 year"
  ExpiresByType text/css "access plus 1 year"

They have documented what that file does, the most important bit is that you need to rename your CSS and Javascript files whenever they change, because your visitor's browsers will not check them again for a year, once they are cached.

Left Join With Where Clause

The result is correct based on the SQL statement. Left join returns all values from the right table, and only matching values from the left table.

ID and NAME columns are from the right side table, so are returned.

Score is from the left table, and 30 is returned, as this value relates to Name "Flow". The other Names are NULL as they do not relate to Name "Flow".

The below would return the result you were expecting:

    SELECT  a.*, b.Score
FROM    @Table1 a
    LEFT JOIN @Table2 b
       ON a.ID = b.T1_ID 
AND a.Name = 'Flow'

The SQL applies a filter on the right hand table.

How does Java resolve a relative path in new File()?

When your path starts with a root dir i.e. C:\ in windows or / in Unix or in java resources path, it is considered to be an absolute path. Everything else is relative, so

new File("test.txt") is the same as new File("./test.txt")

new File("test/../test.txt") is the same as new File("./test/../test.txt")

The major difference between getAbsolutePath and getCanonicalPath is that the first one concatenates a parent and a child path, so it may contain dots: .. or .. getCanonicalPath will always return the same path for a particular file.

Note: File.equals uses an abstract form of a path (getAbsolutePath) to compare files, so this means that two File objects for the same might not be equal and Files are unsafe to use in collections like Map or Set.

Array length in angularjs returns undefined



Instead of:


And next time "spell-check" your code.

How can I get the username of the logged-in user in Django?

You can use the request object to find the logged in user

def my_view(request):
    username = None
    if request.user.is_authenticated():
        username = request.user.username

According to

In version Django 2.0 the syntax has changed to


Understanding Bootstrap's clearfix class

.clearfix is defined in less/mixins.less. Right above its definition is a comment with a link to this article:

A new micro clearfix hack

The article explains how it all works.

UPDATE: Yes, link-only answers are bad. I knew this even at the time that I posted this answer, but I didn't feel like copying and pasting was OK due to copyright, plagiarism, and what have you. However, I now feel like it's OK since I have linked to the original article. I should also mention the author's name, though, for credit: Nicolas Gallagher. Here is the meat of the article (note that "Thierry’s method" is referring to Thierry Koblentz’s “clearfix reloaded”):

This “micro clearfix” generates pseudo-elements and sets their display to table. This creates an anonymous table-cell and a new block formatting context that means the :before pseudo-element prevents top-margin collapse. The :after pseudo-element is used to clear the floats. As a result, there is no need to hide any generated content and the total amount of code needed is reduced.

Including the :before selector is not necessary to clear the floats, but it prevents top-margins from collapsing in modern browsers. This has two benefits:

  • It ensures visual consistency with other float containment techniques that create a new block formatting context, e.g., overflow:hidden

  • It ensures visual consistency with IE 6/7 when zoom:1 is applied.

N.B.: There are circumstances in which IE 6/7 will not contain the bottom margins of floats within a new block formatting context. Further details can be found here: Better float containment in IE using CSS expressions.

The use of content:" " (note the space in the content string) avoids an Opera bug that creates space around clearfixed elements if the contenteditable attribute is also present somewhere in the HTML. Thanks to Sergio Cerrutti for spotting this fix. An alternative fix is to use font:0/0 a.

Legacy Firefox

Firefox < 3.5 will benefit from using Thierry’s method with the addition of visibility:hidden to hide the inserted character. This is because legacy versions of Firefox need content:"." to avoid extra space appearing between the body and its first child element, in certain circumstances (e.g.,

Alternative float-containment methods that create a new block formatting context, such as applying overflow:hidden or display:inline-block to the container element, will also avoid this behaviour in legacy versions of Firefox.

Matching exact string with JavaScript

Either modify the pattern beforehand so that it only matches the entire string:

var r = /^a$/

or check afterward whether the pattern matched the whole string:

function matchExact(r, str) {
   var match = str.match(r);
   return match && str === match[0];

Regular expression for excluding special characters

Use This one

^(?=[a-zA-Z0-9~@#$^*()_+=[\]{}|\\,.?: -]*$)(?!.*[<>'"/;`%])

The type or namespace name does not exist in the namespace 'System.Web.Mvc'

Clean your solution and then set the property of those files to Copy Local = True.

To set the Copy Local property to True or False

In Solution Explorer, click the Show All Files button to display the References node.

  • Open the References node for the project.
  • Right-click a reference in the References list, and click Properties. The properties associated with that reference appear in a list in the Properties window.
  • In the Properties window, change the Copy Local property to True or False.

How to use target in location.href

You could try this:

        <script type="text/javascript">
         function newWindow(url){

And call the function

What does functools.wraps do?

When you use a decorator, you're replacing one function with another. In other words, if you have a decorator

def logged(func):
    def with_logging(*args, **kwargs):
        print(func.__name__ + " was called")
        return func(*args, **kwargs)
    return with_logging

then when you say

def f(x):
   """does some math"""
   return x + x * x

it's exactly the same as saying

def f(x):
    """does some math"""
    return x + x * x
f = logged(f)

and your function f is replaced with the function with_logging. Unfortunately, this means that if you then say


it will print with_logging because that's the name of your new function. In fact, if you look at the docstring for f, it will be blank because with_logging has no docstring, and so the docstring you wrote won't be there anymore. Also, if you look at the pydoc result for that function, it won't be listed as taking one argument x; instead it'll be listed as taking *args and **kwargs because that's what with_logging takes.

If using a decorator always meant losing this information about a function, it would be a serious problem. That's why we have functools.wraps. This takes a function used in a decorator and adds the functionality of copying over the function name, docstring, arguments list, etc. And since wraps is itself a decorator, the following code does the correct thing:

from functools import wraps
def logged(func):
    def with_logging(*args, **kwargs):
        print(func.__name__ + " was called")
        return func(*args, **kwargs)
    return with_logging

def f(x):
   """does some math"""
   return x + x * x

print(f.__name__)  # prints 'f'
print(f.__doc__)   # prints 'does some math'

How to ping multiple servers and return IP address and Hostnames using batch script?

@echo off

set workdir={your working dir. for example - C:\work } set iplist=%workdir%\IP-list.txt

setlocal enabledelayedexpansion
set OUTPUT_FILE=%workdir%\result.csv

>nul copy nul %OUTPUT_FILE%
for /f %%i in (%iplist%) do (
    for /f "tokens=1,2,3" %%x in ('ping -a -n 1 %%i ^&^& echo SERVER_IS_UP') do (
    if %%x==Pinging set SERVER_ADDRESS_L=%%y
    if %%x==Pinging set SERVER_ADDRESS_I=%%z
        if %%x==SERVER_IS_UP (set SERVER_STATE=UP) else (set SERVER_STATE=DOWN)

Evaluating string "3*(4+2)" yield int 18

This is a simple Expression Evaluator using Stacks

public class MathEvaluator
    public static void Run()

    public static void Eval(string input)
        var ans = Evaluate(input);
        Console.WriteLine(input + " = " + ans);

    public static double Evaluate(String input)
        String expr = "(" + input + ")";
        Stack<String> ops = new Stack<String>();
        Stack<Double> vals = new Stack<Double>();

        for (int i = 0; i < expr.Length; i++)
            String s = expr.Substring(i, 1);
            if (s.Equals("(")){}
            else if (s.Equals("+")) ops.Push(s);
            else if (s.Equals("-")) ops.Push(s);
            else if (s.Equals("*")) ops.Push(s);
            else if (s.Equals("/")) ops.Push(s);
            else if (s.Equals("sqrt")) ops.Push(s);
            else if (s.Equals(")"))
                int count = ops.Count;
                while (count > 0)
                    String op = ops.Pop();
                    double v = vals.Pop();
                    if (op.Equals("+")) v = vals.Pop() + v;
                    else if (op.Equals("-")) v = vals.Pop() - v;
                    else if (op.Equals("*")) v = vals.Pop()*v;
                    else if (op.Equals("/")) v = vals.Pop()/v;
                    else if (op.Equals("sqrt")) v = Math.Sqrt(v);

            else vals.Push(Double.Parse(s));
        return vals.Pop();

TypeScript sorting an array

I wrote this one today while trying to recreate _.sortBy in TypeScript, and thought I would leave it for anyone in need.

// ** Credits for getKeyValue at the bottom **
export const getKeyValue = <T extends {}, U extends keyof T>(key: U) => (obj: T) => obj[key] 

export const sortBy = <T extends {}>(index: string, list: T[]): T[] => {
    return list.sort((a, b): number => {
        const _a = getKeyValue<keyof T, T>(index)(a)
        const _b = getKeyValue<keyof T, T>(index)(b)
        if (_a < _b) return -1
        if (_a > _b) return 1
        return 0


It expects an array of generic type T, hence the cast for <T extends {}>, as well as typing the parameter and function return type with T[]

const x = [{ label: 'anything' }, { label: 'goes'}]
const sorted = sortBy('label', x)

** getByKey fn found here

Cannot use mkdir in home directory: permission denied (Linux Lubuntu)

As @kirbyfan64sos notes in a comment, /home is NOT your home directory (a.k.a. home folder):

The fact that /home is an absolute, literal path that has no user-specific component provides a clue.

While /home happens to be the parent directory of all user-specific home directories on Linux-based systems, you shouldn't even rely on that, given that this differs across platforms: for instance, the equivalent directory on macOS is /Users.

What all Unix platforms DO have in common are the following ways to navigate to / refer to your home directory:

  • Using cd with NO argument changes to your home dir., i.e., makes your home dir. the working directory.
    • e.g.: cd # changes to home dir; e.g., '/home/jdoe'
  • Unquoted ~ by itself / unquoted ~/ at the start of a path string represents your home dir. / a path starting at your home dir.; this is referred to as tilde expansion (see man bash)
    • e.g.: echo ~ # outputs, e.g., '/home/jdoe'
  • $HOME - as part of either unquoted or preferably a double-quoted string - refers to your home dir. HOME is a predefined, user-specific environment variable:
    • e.g.: cd "$HOME/tmp" # changes to your personal folder for temp. files

Thus, to create the desired folder, you could use:

mkdir "$HOME/bin"  # same as: mkdir ~/bin

Note that most locations outside your home dir. require superuser (root user) privileges in order to create files or directories - that's why you ran into the Permission denied error. Connection refused

This exception means that there is no service listening on the IP/port you are trying to connect to:

  • You are trying to connect to the wrong IP/Host or port.
  • You have not started your server.
  • Your server is not listening for connections.
  • On Windows servers, the listen backlog queue is full.

Change default date time format on a single database in SQL Server

You can only change the language on the whole server, not individual databases. However if you need to support the UK you can run the following command before all inputs and outputs:

set language 'british english'

Or if you are having issues entering datatimes from your application you might want to consider a universal input type such as


"Could not find a part of the path" error message

I resolved a similar issue by simply restarting Visual Studio with admin rights.

The problem was because it couldn't open one project related to Sharepoint without elevated access.

Error With Port 8080 already in use

In your apache conf folder, open the httpd file and look for 8080 port. Change 8080 to any port you like. I believe you will find 8080 on two places. Restart your server to see changes.

jQuery: How to get the HTTP status code from within the $.ajax.error method?

You should create a map of actions using the statusCode setting:

  statusCode: {
    400: function() {
      alert('400 status code! user error');
    500: function() {
      alert('500 status code! server error');

Reference (Scroll to: 'statusCode')

EDIT (In response to comments)

If you need to take action based on the data returned in the response body (which seems odd to me), you will need to use error: instead of statusCode:

error:function (xhr, ajaxOptions, thrownError){
    switch (xhr.status) {
        case 404:
             // Take action, referencing xhr.responseText as needed.

How Do I Take a Screen Shot of a UIView?

iOS 7 has a new method that allows you to draw a view hierarchy into the current graphics context. This can be used to get an UIImage very fast.

I implemented a category method on UIView to get the view as an UIImage:

- (UIImage *)pb_takeSnapshot {
    UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, [UIScreen mainScreen].scale);

    [self drawViewHierarchyInRect:self.bounds afterScreenUpdates:YES];

    // old style [self.layer renderInContext:UIGraphicsGetCurrentContext()];

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    return image;

It is considerably faster then the existing renderInContext: method.


UPDATE FOR SWIFT: An extension that does the same:

extension UIView {

    func pb_takeSnapshot() -> UIImage {
        UIGraphicsBeginImageContextWithOptions(bounds.size, false, UIScreen.mainScreen().scale)

        drawViewHierarchyInRect(self.bounds, afterScreenUpdates: true)

        // old style: layer.renderInContext(UIGraphicsGetCurrentContext())

        let image = UIGraphicsGetImageFromCurrentImageContext()
        return image


    UIGraphicsBeginImageContextWithOptions(bounds.size, false, UIScreen.main.scale)

    drawHierarchy(in: self.bounds, afterScreenUpdates: true)

    let image = UIGraphicsGetImageFromCurrentImageContext()!
    return image

Multiple lines of input in <input type="text" />

If you need textarea with auto height, Use follows with pure javascript,

function auto_height(elem) {  /* javascript */_x000D_ = "1px";_x000D_ = (elem.scrollHeight)+"px";_x000D_
.auto_height { /* CSS */_x000D_
  width: 100%;_x000D_
<textarea rows="1" class="auto_height" oninput="auto_height(this)"></textarea>

How do I find which application is using up my port?

To see which ports are available on your machine run:

C:>  netstat -an |find /i "listening"

What is a "method" in Python?

In Python, a method is a function that is available for a given object because of the object's type.

For example, if you create my_list = [1, 2, 3], the append method can be applied to my_list because it's a Python list: my_list.append(4). All lists have an append method simply because they are lists.

As another example, if you create my_string = 'some lowercase text', the upper method can be applied to my_string simply because it's a Python string: my_string.upper().

Lists don't have an upper method, and strings don't have an append method. Why? Because methods only exist for a particular object if they have been explicitly defined for that type of object, and Python's developers have (so far) decided that those particular methods are not needed for those particular objects.

To call a method, the format is object_name.method_name(), and any arguments to the method are listed within the parentheses. The method implicitly acts on the object being named, and thus some methods don't have any stated arguments since the object itself is the only necessary argument. For example, my_string.upper() doesn't have any listed arguments because the only required argument is the object itself, my_string.

One common point of confusion regards the following:

import math

Is sqrt a method of the math object? No. This is how you call the sqrt function from the math module. The format being used is module_name.function_name(), instead of object_name.method_name(). In general, the only way to distinguish between the two formats (visually) is to look in the rest of the code and see if the part before the period (math, my_list, my_string) is defined as an object or a module.

Change bootstrap navbar collapse breakpoint without using LESS

This worked for me Bootstrap3

@media (min-width: 768px) {
    .navbar-header {
          float: none;
      .navbar-toggle {
          display: block;
      .navbar-collapse {
          border-top: 1px solid transparent;
          box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.1);
      .navbar-collapse.collapse {
          display: none!important;
      } {
          display: block!important;
      .navbar-nav {
          float: none!important;
          margin: 7.5px -15px;
      .navbar-nav>li {
          float: none;
      .navbar-nav>li>a {
          padding-top: 10px;
          padding-bottom: 10px;

Took a while to figure these two out:

.navbar-collapse.collapse {
   display: none!important;
} {
   display: block!important;

WebDriverException: unknown error: DevToolsActivePort file doesn't exist while trying to initiate Chrome Browser

I ran into same issue, i am using UBUNTU, PYTHON and OPERA browser. in my case the problem was originated because i had an outdated version of operadriver.

Solution: 1. Make sure you install latest opera browser version ( do not use opera beta or opera developer), for that go to the official opera site and download from there the latest opera_stable version.

  1. Install latest opera driver (if you already have an opera driver install, you have to remove it first use sudo rm ...)


   sudo mv operadriver /usr/bin/operadriver
   sudo chown root:root /usr/bin/operadriver
   sudo chmod +x /usr/bin/operadriver

in my case latest was 80.0.3987 as you can see

  1. Additionally i also installed chromedriver (but since i did it before testing, i do not know of this is needed) in order to install chromedriver, follow the steps on previous step :v

  2. Enjoy and thank me!

Sample selenium code

from selenium import webdriver
from selenium.webdriver.common.keys import Keys
driver = webdriver.Opera()
assert "Python" in driver.title
elem = driver.find_element_by_name("q")
assert "No results found." not in driver.page_source

Is it bad practice to use break to exit a loop in Java?

break and continue breaks the readability for the reader, although it's often useful. Not as much as "goto" concept, but almost.

Besides, if you take some new languages like Scala (inspired by Java and functional programming languages like Ocaml), you will notice that break and continue simply disappeared.

Especially in functional programming, this style of code is avoided:

Why scala doesn't support break and continue?

To sum up: break and continueare widely used in Java for an imperative style, but for any coders that used to practice functional programming, it might be.. weird.

Safely casting long to int in Java

here is a solution, in case you don't care about value in case it is bigger then needed ;)

public static int safeLongToInt(long l) {
    return (int) Math.max(Math.min(Integer.MAX_VALUE, l), Integer.MIN_VALUE);

<select> HTML element with height

You can also "center" the text with:

vertical-align: middle;

How can I convert a string to boolean in JavaScript?

In HTML the values of attributes eventually become strings. To mitigate that in undesired situations you can have a function to conditionally parse them into values they represent in the JavaScript or any other programming langauge of interest.

Following is an explanation to do it for reviving boolean type from the string type, but it can be further expanded into other data types too, like numbers, arrays or objects.

In addition to that JSON.parse has a revive parameter which is a function. It also can be used to achieve the same.

Let's call a string looking like a boolean, "true", a boolean string likewise we can call a string like a number, "1", a number string. Then we can determine if a string is a boolean string:

const isBooleanString = (string) => ['true', 'false'].some(item => item === string);

After that we need to parse the boolean string as JSON by JSON.parse method:


However, any string that is not a boolean string, number string, or any stringified object or array (any invalid JSON) will cause the JSON.parse method to throw a SyntaxError.

So, you will need to know with what to call it, i.e. if it is a boolean string. You can achieve this by writing a function that makes the above defiend boolean string check and call JSON.parse:

function parse(string){
  return isBooleanString(string) ? JSON.parse(string)
    : string;

One can further generalize the isBooleanString utility to have a more broader perspective on what qualifies as a boolean string by further parametrizing it to accept an optional array of accepted boolean strings:

const isBooleanString = (string, spec = ['true', 'false', 'True', 'False']) => spec.some(item => item === string);

jQuery: How to get to a particular child of a parent?

You could use .each() with .children() and a selector within the parenthesis:

//Grab Each Instance of Box.

    //For Each Instance, grab a child called .something1. Fade It Out.

HTTP Request in Swift with POST method

For anyone looking for a clean way to encode a POST request in Swift 5.

You don’t need to deal with manually adding percent encoding. Use URLComponents to create a GET request URL. Then use query property of that URL to get properly percent escaped query string.

let url = URL(string: "")!
var components = URLComponents(url: url, resolvingAgainstBaseURL: false)!

components.queryItems = [
    URLQueryItem(name: "key1", value: "NeedToEscape=And&"),
    URLQueryItem(name: "key2", value: "vålüé")

let query = components.url!.query

The query will be a properly escaped string:


Now you can create a request and use the query as HTTPBody:

var request = URLRequest(url: url)
request.httpMethod = "POST"
request.httpBody = Data(query.utf8)

Now you can send the request.

Difference between float and decimal data type

declare @float as float(10)
declare @Decimal as decimal(10)
declare @Inetger as int

set @float =10.7
set @Decimal =10.7
set @Inetger=@Decimal

print @Inetger

in float when set value to integer print 10 but in decimal 11

gcc-arm-linux-gnueabi command not found

CodeSourcery convention is to use prefix arm-none-linux-gnueabi- for all executables, not gcc-arm-linux-gnueabi that you mention. So, standard name for CodeSourcery gcc would be arm-none-linux-gnueabi-gcc.

After you have installed CodeSourcery G++, you need to add CodeSourcery directory into your PATH.

Typically, I prefer to install CodeSourcery into directory like /opt/arm-2010q1 or something like that. If you don't know where you have installed it, you can find it using locate arm-none-linux-gnueabi-gcc, however you may need to force to update your locate db using sudo updatedb before locate will work properly.

After you have identified where your CodeSourcery is installed, add it your PATH by editing ~/.bashrc like this:


Also, it is customary and very convenient to define


in your .bashrc, because with CROSS_COMPILE defined, most tools will automatically use proper compiler for ARM compilation without you doing anything.

Header set Access-Control-Allow-Origin in .htaccess doesn't work

Just for the record, I was running into the exact same problem and none of the answers worked.

I used a headers checker tool:

I was testing with my IP ( and what came back was the following:

HTTP/1.1 301 Moved Permanently => 
Date => Sat, 10 Jan 2015 04:03:35 GMT
Server => Apache/2.2.21 (Win32) mod_ssl/2.2.21 OpenSSL/1.0.0e PHP/5.3.8 mod_perl/2.0.4 Perl/v5.10.1
Location =>
Content-Length => 380
Connection => close
Content-Type => text/html; charset=iso-8859-1

There was a redirection happening and the AJAX request does not honor/follow redirects.

It turned out to be the missing slash at the end of the domain (

I tested again with slash at the end and I got this below. Added a slash in the script too, and it was now working.

HTTP/1.1 200 OK => 
Date => Sat, 10 Jan 2015 04:03:53 GMT
Server => Apache/2.2.21 (Win32) mod_ssl/2.2.21 OpenSSL/1.0.0e PHP/5.3.8 mod_perl/2.0.4 Perl/v5.10.1
X-Powered-By => PHP/5.3.8
Access-Control-Allow-Origin => *
Access-Control-Allow-Methods => PUT, GET, POST, DELETE, OPTIONS
Access-Control-Allow-Headers => *
Content-Length => 1435
Connection => close
Content-Type => text/html

Use this tool to test if your headers are good and to troubleshoot what is happening.

Text Editor which shows \r\n?

If you have Mathematica, you can try with this command:

ReadList["filename.txt", Record, RecordSeparators -> {}] // InputForm

That will show all the /r and /n

How to pre-populate the sms body text via an html link

Just put all of the symbols in this order (I only tested it in this order since it makes the most sense code-wise to me).

Notice for the body link... I just put... ;?&body=. Also, notice that I have found I needed to use %20 for any spaces.

I have tested it on my iphone (v. 9.2) and another android and it works just fine.

This will solve the issue with having to hack it for different devices. I have no artifacts when I tested it in the SMS.

<a href="sms:19131234567;?&" title="Click here to TEXT US gallery token needs updating!">Send me SMS</a>

Does C# have a String Tokenizer like Java's?

The similar to Java's method is:

Regex.Split(string, pattern);


  • string - the text you need to split
  • pattern - string type pattern, what is splitting the text

Appending a line to a file only if it does not already exist

I needed to edit a file with restricted write permissions so needed sudo. working from ghostdog74's answer and using a temp file:

awk 'FNR==NR && /configs.*projectname\.conf/{f=1;next}f==0;END{ if(!f) { print "your line"}} ' file > /tmp/file
sudo mv /tmp/file file

How do you kill all current connections to a SQL Server 2005 database?

Script to accomplish this, replace 'DB_NAME' with the database to kill all connections to:

USE master

DECLARE @DBName varchar(50)
DECLARE @spidstr varchar(8000)
DECLARE @ConnKilled smallint
SET @ConnKilled=0
SET @spidstr = ''

Set @DBName = 'DB_NAME'
IF db_id(@DBName) < 4
PRINT 'Connections to system databases cannot be killed'
SELECT @spidstr=coalesce(@spidstr,',' )+'kill '+convert(varchar, spid)+ '; '
FROM master..sysprocesses WHERE dbid=db_id(@DBName)

IF LEN(@spidstr) > 0
SELECT @ConnKilled = COUNT(1)
FROM master..sysprocesses WHERE dbid=db_id(@DBName)

Force page scroll position to top at page refresh in HTML

For a simple plain JavaScript implementation:

window.onbeforeunload = function () {_x000D_
  window.scrollTo(0, 0);_x000D_

How to concatenate a std::string and an int?

#include <string>
#include <sstream>
using namespace std;
string concatenate(std::string const& name, int i)
    stringstream s;
    s << name << i;
    return s.str();

How to use Jquery how to change the aria-expanded="false" part of a dom element (Bootstrap)?

Since the question asked for either jQuery or vanilla JS, here's an answer with vanilla JS.

I've added some CSS to the demo below to change the button's font color to red when its aria-expanded is set to true

const button = document.querySelector('button');_x000D_
button.addEventListener('click', () => {_x000D_
  button.ariaExpanded = !JSON.parse(button.ariaExpanded);_x000D_
button[aria-expanded="true"] {_x000D_
  color: red;_x000D_
<button type="button" aria-expanded="false">Click me!</button>

Error in Python IOError: [Errno 2] No such file or directory: 'data.csv'

You need to either provide the absolute path to data.csv, or run your script in the same directory as data.csv.

URL.Action() including route values

You also can use in this form:

<a href="@Url.Action("Information", "Admin", null)"> Admin</a>

Check if element found in array c++

One wants this to be done tersely. Nothing makes code more unreadable then spending 10 lines to achieve something elementary. In C++ (and other languages) we have all and any which help us to achieve terseness in this case. I want to check whether a function parameter is valid, meaning equal to one of a number of values. Naively and wrongly, I would first write

if (!any_of({ DNS_TYPE_A, DNS_TYPE_MX }, wtype) return false;

a second attempt could be

if (!any_of({ DNS_TYPE_A, DNS_TYPE_MX }, [&wtype](const int elem) { return elem == wtype; })) return false;

Less incorrect, but looses some terseness. However, this is still not correct because C++ insists in this case (and many others) that I specify both start and end iterators and cannot use the whole container as a default for both. So, in the end:

const vector validvalues{ DNS_TYPE_A, DNS_TYPE_MX };
if (!any_of(validvalues.cbegin(),  validvalues.cend(), [&wtype](const int elem) { return elem == wtype; })) return false;

which sort of defeats the terseness, but I don't know a better alternative... Thank you for not pointing out that in the case of 2 values I could just have just if ( || ). The best approach here (if possible) is to use a case structure with a default where not only the values are checked, but also the appropriate actions are done. The default case can be used for signalling an invalid value.

Is there an easy way to strike through text in an app widget?

Make a drawable file, striking_text.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="">
    <item android:state_pressed="false">
        <shape android:shape="line">
            <stroke android:width="1dp" android:color="@android:color/holo_red_dark" />

layout xml


If your min SDK below API level 23 just use the background or just put the background and foreground in the Textview then the android studio will show an error that says create a layout file for API >23 after that remove the android:foreground="@drawable/stricking_text" from the main layout

Output look like this: enter image description here

How to execute IN() SQL queries with Spring's JDBCTemplate effectively?

Many things changed since 2009, but I can only find answers saying you need to use NamedParametersJDBCTemplate.

For me it works if I just do a

db.query(sql, new MyRowMapper(), StringUtils.join(listeParamsForInClause, ","));

using SimpleJDBCTemplate or JDBCTemplate

Copy-item Files in Folders and subfolders in the same directory structure of source server using PowerShell

I had trouble with the most popular answer (overthinking). It put AFolder in the \Server\MyFolder\AFolder and I wanted the contents of AFolder and below in MyFolder. This didn't work.

Copy-Item -Verbose -Path C:\MyFolder\AFolder -Destination \\Server\MyFolder -recurse -Force

Plus I needed to Filter and only copy *.config files.

This didn't work, with "\*" because it did not recurse

Copy-Item -Verbose -Path C:\MyFolder\AFolder\* -Filter *.config -Destination \\Server\MyFolder -recurse -Force

I ended up lopping off the beginning of the path string, to get the childPath relative to where I was recursing from. This works for the use-case in question and went down many subdirectories, which some other solutions do not.

Get-Childitem -Path "$($sourcePath)/**/*.config" -Recurse | 
ForEach-Object {
  $childPath = "$_".substring($sourcePath.length+1)
  $dest = "$($destPath)\$($childPath)" #this puts a \ between dest and child path
  Copy-Item -Verbose -Path $_ -Destination $dest -Force   

Sort a List of objects by multiple fields

Your Comparator would look like this:

public class GraduationCeremonyComparator implements Comparator<GraduationCeremony> {
    public int compare(GraduationCeremony o1, GraduationCeremony o2) {
        int value1 = o1.campus.compareTo(o2.campus);
        if (value1 == 0) {
            int value2 = o1.faculty.compareTo(o2.faculty);
            if (value2 == 0) {
                return o1.building.compareTo(o2.building);
            } else {
                return value2;
        return value1;

Basically it continues comparing each successive attribute of your class whenever the compared attributes so far are equal (== 0).

Why are primes important in cryptography?

Most basic and general explanation: cryptography is all about number theory, and all integer numbers (except 0 and 1) are made up of primes, so you deal with primes a lot in number theory.

More specifically, some important cryptographic algorithms such as RSA critically depend on the fact that prime factorization of large numbers takes a long time. Basically you have a "public key" consisting of a product of two large primes used to encrypt a message, and a "secret key" consisting of those two primes used to decrypt the message. You can make the public key public, and everyone can use it to encrypt messages to you, but only you know the prime factors and can decrypt the messages. Everyone else would have to factor the number, which takes too long to be practical, given the current state of the art of number theory.

Encode html entities in javascript

Here is how I implemented the encoding. I took inspiration from the answers given above.

function encodeHTML(str) {
  const code = {
      ' ' : '&nbsp;',
      '¢' : '&cent;',
      '£' : '&pound;',
      '¥' : '&yen;',
      '€' : '&euro;', 
      '©' : '&copy;',
      '®' : '&reg;',
      '<' : '&lt;', 
      '>' : '&gt;',  
      '"' : '&quot;', 
      '&' : '&amp;',
      '\'' : '&apos;'
  return str.replace(/[\u00A0-\u9999<>\&''""]/gm, (i)=>code[i]);

console.log(encodeHTML("Dolce & Gabbana"));
console.log(encodeHTML("Hamburgers < Pizza < Tacos"));
console.log(encodeHTML("Sixty > twelve"));
console.log(encodeHTML('Stuff in "quotation marks"'));
console.log(encodeHTML("Schindler's List"));

How to list processes attached to a shared memory segment in linux?

given your example above - to find processes attached to shmid 98306

lsof | egrep "98306|COMMAND"

jQuery: how to get which button was clicked upon form submission?

For me, the best solutions was this:


   // Get the button that was clicked       
   var submit = $(;

   // You can get its name like this

   // You can get its attributes like this too


What is the difference between dim and set in vba

Dim: you are defining a variable (here: r is a variable of type Range)

Set: you are setting the property (here: set the value of r to Range("A1") - this is not a type, but a value).

You have to use set with objects, if r were a simple type (e.g. int, string), then you would just write:

Dim r As Integer

Passing a dictionary to a function as keyword parameters

In python, this is called "unpacking", and you can find a bit about it in the tutorial. The documentation of it sucks, I agree, especially because of how fantasically useful it is.

How to have image and text side by side

It's always worth grouping elements into sections that are relevant. In your case, a parent element that contains two columns;

  1. icon
  2. text.


<div class='container2'>
    <img src='' class='iconDetails' />

    <div class="text">
            fine location, GPS, coarse location
            <span>0 mins ago</span>


* {
.iconDetails {
    margin:0 2%;
.container2 {
.text {
.text h4, .text p {
.text p span {

How to upload a file to directory in S3 bucket using boto

I used this and it is very simple to implement

import tinys3

conn = tinys3.Connection('S3_ACCESS_KEY','S3_SECRET_KEY',tls=True)

f = open('','rb')

How to use @Nullable and @Nonnull annotations more effectively?

If you use Kotlin, it supports these nullability annotations in its compiler and will prevent you from passing a null to a java method that requires a non-null argument. Event though this question was originally targeted at Java, I mention this Kotlin feature because it is specifically targeted at these Java annotation and the question was "Is there a way to make these annotations more strictly enforced and/or propagate further?" and this feature does make these annotation more strictly enforced.

Java class using @NotNull annotation

public class MyJavaClazz {
    public void foo(@NotNull String myString) {
        // will result in an NPE if myString is null

Kotlin class calling Java class and passing null for the argument annotated with @NotNull

class MyKotlinClazz {
    fun foo() {

Kotlin compiler error enforcing the @NotNull annotation.

Error:(5, 27) Kotlin: Null can not be a value of a non-null type String


jQuery and TinyMCE: textarea value doesn't submit

From TinyMCE, jQuery and Ajax forms:

TinyMCE Form Submission

  • When a textarea is replaced by TinyMCE, it's actually hidden and TinyMCE editor (an iframe) is displayed instead.

  • However, it's this textarea's contents which is sent when the form is submitted. Consequently its contents has to be updated before the form submission.

  • For a standard form submission , it's handled by TinyMCE . For an Ajax form submission, you have to do it manually, by calling (before the form is submitted):


$('form').bind('form-pre-serialize', function(e) {

Nested routes with react router v4 / v5

A complete answer for React Router v6 or version 6 just in case needed.

import Dashboard from "./dashboard/Dashboard";
import DashboardDefaultContent from "./dashboard/dashboard-default-content";
import { Route, Routes } from "react-router";
import { useRoutes } from "react-router-dom";

/*Routes is used to be Switch*/
const Router = () => {

  return (
      <Route path="/" element={<LandingPage />} />
      <Route path="games" element={<Games />} />
      <Route path="game-details/:id" element={<GameDetails />} />
      <Route path="dashboard" element={<Dashboard />}>
        <Route path="/" element={<DashboardDefaultContent />} />
        <Route path="inbox" element={<Inbox />} />
        <Route path="settings-and-privacy" element={<SettingsAndPrivacy />} />
        <Route path="*" element={<NotFound />} />
      <Route path="*" element={<NotFound />} />
export default Router;
import DashboardSidebarNavigation from "./dashboard-sidebar-navigation";
import { Grid } from "@material-ui/core";
import { Outlet } from "react-router";

const Dashboard = () => {
  return (
      <DashboardSidebarNavigation />
      <Outlet />

export default Dashboard;

Github repo is here.

How to click a link whose href has a certain substring in Selenium?

With the help of xpath locator also, you can achieve the same.

Your statement would be:


And for clicking all the links contains long in the URL, you can use:-

List<WebElement> linksList = driver.findElements(By.xpath(".//a[contains(@href,'long')]"));

for (WebElement webElement : linksList){;

How can I count the occurrences of a list item?

I would use filter(), take Lukasz's example:

>>> lst = [1, 2, 3, 4, 1, 4, 1]
>>> len(filter(lambda x: x==1, lst))

How can I perform static code analysis in PHP?

See Semantic Designs' CloneDR, a "clone detection" tool that finds copy/paste/edited code.

It will find exact and near miss code fragments, in spite of white space, comments and even variable renamings. A sample detection report for PHP can be found at the website. (I'm the author.)

How to download a file over HTTP?

If you have wget installed, you can use parallel_sync.

pip install parallel_sync

from parallel_sync import wget
urls = ['http://something.png', 'http://somthing.tar.gz', '']'/tmp', urls)
# or a single file:'/tmp', urls[0], filenames='', extract=True)


This is pretty powerful. It can download files in parallel, retry upon failure , and it can even download files on a remote machine.

"Sources directory is already netbeans project" error when opening a project from existing sources

Thank you!

I was having the same problem:
Sources directory is already NetBeans project (maybe only in memory).

Netbeans creates a folder in your project named "nbproject". Once you delete that, restart the IDE and you're good to go.

Windows XP or later Windows: How can I run a batch file in the background with no window displayed?

Do you need the second batch file to run asynchronously? Typically one batch file runs another synchronously with the call command, and the second one would share the first one's window.

You can use start /b second.bat to launch a second batch file asynchronously from your first that shares your first one's window. If both batch files write to the console simultaneously, the output will be overlapped and probably indecipherable. Also, you'll want to put an exit command at the end of your second batch file, or you'll be within a second cmd shell once everything is done.

'pip' is not recognized as an internal or external command

The only way that worked on my Windows 10 machine was as follows:

py -3 -m pip install xxxxx

SQL Call Stored Procedure for each Row without using a cursor

If you don't what to use a cursor I think you'll have to do it externally (get the table, and then run for each statement and each time call the sp) it Is the same as using a cursor, but only outside SQL. Why won't you use a cursor ?

How can I check whether a option already exist in select by JQuery

Another way using jQuery:

var exists = false; 
$('#yourSelect  option').each(function(){
  if (this.value == yourValue) {
    exists = true;

How to call Makefile from another Makefile?

I'm not really too clear what you are asking, but using the -f command line option just specifies a file - it doesn't tell make to change directories. If you want to do the work in another directory, you need to cd to the directory:

    cd gtest-1.4.0 && $(MAKE) clean

Note that each line in Makefile runs in a separate shell, so there is no need to change the directory back.

Most pythonic way to delete a file which may not exist

As of Python 3.8, use missing_ok=True and pathlib.Path.unlink (docs here)

from pathlib import Path

my_file = Path("./dir1/dir2/file.txt")

# Python 3.8+

# Python 3.7 and earlier
if my_file.exists():

how to hide a vertical scroll bar when not needed

overflow: auto (or overflow-y: auto) is the correct way to go.

The problem is that your text area is taller than your div. The div ends up cutting off the textbox, so even though it looks like it should start scrolling when the text is taller than 159px it won't start scrolling until the text is taller than 400px which is the height of the textbox.

Try this:

I set overflow:auto on the text box, and made the textbox the same size as the div.

Also I don't believe it's valid to have a div inside a label, the browser will render it, but it might cause some funky stuff to happen. Also your div isn't closed.

How to remove td border with html?


<table border="1">
        <td style='border:none;'>one</td>
        <td style='border:none;'>two</td>
        <td style='border:none;'>one</td>
        <td style='border:none;'>two</td>

Second example

<table border="1" cellspacing="0" cellpadding="0">
    <td style='border-left:none;border-top:none'>one</td>
    <td style='border:none;'>two</td>
    <td style='border-left:none;border-bottom:none;border-top:none'>one</td>
    <td style='border:none;'>two</td>