Programs & Examples On #Ienumerable

IEnumerable, and its generic counterpart IEnumerable are .NET interfaces for iterating (or enumerating) through a collection of items.

Recreating a Dictionary from an IEnumerable<KeyValuePair<>>

If you're using .NET 3.5 or .NET 4, it's easy to create the dictionary using LINQ:

Dictionary<string, ArrayList> result = target.GetComponents()
                                      .ToDictionary(x => x.Key, x => x.Value);

There's no such thing as an IEnumerable<T1, T2> but a KeyValuePair<TKey, TValue> is fine.

How to concatenate two IEnumerable<T> into a new IEnumerable<T>?

You can use below code for your solution:-

public void Linq94() 
{ 
    int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 }; 
    int[] numbersB = { 1, 3, 5, 7, 8 }; 

    var allNumbers = numbersA.Concat(numbersB); 

    Console.WriteLine("All numbers from both arrays:"); 
    foreach (var n in allNumbers) 
    { 
        Console.WriteLine(n); 
    } 
}

How can I return an empty IEnumerable?

That's of course only a matter of personal preference, but I'd write this function using yield return:

public IEnumerable<Friend> FindFriends()
{
    //Many thanks to Rex-M for his help with this one.
    //http://stackoverflow.com/users/67/rex-m
    if (userExists)
    {
        foreach(var user in doc.Descendants("user"))
        {
            yield return new Friend
                {
                    ID = user.Element("id").Value,
                    Name = user.Element("name").Value,
                    URL = user.Element("url").Value,
                    Photo = user.Element("photo").Value
                }
        }
    }
}

filtering a list using LINQ

var filtered = projects;
foreach (var tag in filteredTags) {
  filtered = filtered.Where(p => p.Tags.Contains(tag))
}

The nice thing with this approach is that you can refine search results incrementally.

How to get the index of an element in an IEnumerable?

The whole point of getting things out as IEnumerable is so you can lazily iterate over the contents. As such, there isn't really a concept of an index. What you are doing really doesn't make a lot of sense for an IEnumerable. If you need something that supports access by index, put it in an actual list or collection.

Convert from List into IEnumerable format

You need to

using System.Linq;

to use IEnumerable options at your List.

LINQ equivalent of foreach for IEnumerable<T>

This "functional approach" abstraction leaks big time. Nothing on the language level prevents side effects. As long as you can make it call your lambda/delegate for every element in the container - you will get the "ForEach" behavior.

Here for example one way of merging srcDictionary into destDictionary (if key already exists - overwrites)

this is a hack, and should not be used in any production code.

var b = srcDictionary.Select(
                             x=>
                                {
                                  destDictionary[x.Key] = x.Value;
                                  return true;
                                }
                             ).Count();

What is the difference between IQueryable<T> and IEnumerable<T>?

The primary difference is that the LINQ operators for IQueryable<T> take Expression objects instead of delegates, meaning the custom query logic it receives, e.g., a predicate or value selector, is in the form of an expression tree instead of a delegate to a method.

  • IEnumerable<T> is great for working with sequences that are iterated in-memory, but
  • IQueryable<T> allows for out-of memory things like a remote data source, such as a database or web service.

Query execution:

  • Where the execution of a query is going to be performed "in process", typically all that's required is the code (as code) to execute each part of the query.

  • Where the execution will be performed out-of-process, the logic of the query has to be represented in data such that the LINQ provider can convert it into the appropriate form for the out-of-memory execution - whether that's an LDAP query, SQL or whatever.

More in:

http://www.codeproject.com/KB/cs/646361/WhatHowWhere.jpg

Can anyone explain IEnumerable and IEnumerator to me?

I have noticed these differences:

A. We iterate the list in different way, foreach can be used for IEnumerable and while loop for IEnumerator.

B. IEnumerator can remember the current index when we pass from one method to another (it start working with current index) but IEnumerable can't remember the index and it reset the index to beginning. More in this video https://www.youtube.com/watch?v=jd3yUjGc9M0

How to check if IEnumerable is null or empty?

I built this off of the answer by @Matt Greer

He answered the OP's question perfectly.

I wanted something like this while maintaining the original capabilities of Any while also checking for null. I'm posting this in case anyone else needs something similar.

Specifically I wanted to still be able to pass in a predicate.

public static class Utilities
{
    /// <summary>
    /// Determines whether a sequence has a value and contains any elements.
    /// </summary>
    /// <typeparam name="TSource">The type of the elements of source.</typeparam>
    /// <param name="source">The <see cref="System.Collections.Generic.IEnumerable"/> to check for emptiness.</param>
    /// <returns>true if the source sequence is not null and contains any elements; otherwise, false.</returns>
    public static bool AnyNotNull<TSource>(this IEnumerable<TSource> source)
    {
        return source?.Any() == true;
    }

    /// <summary>
    /// Determines whether a sequence has a value and any element of a sequence satisfies a condition.
    /// </summary>
    /// <typeparam name="TSource">The type of the elements of source.</typeparam>
    /// <param name="source">An <see cref="System.Collections.Generic.IEnumerable"/> whose elements to apply the predicate to.</param>
    /// <param name="predicate">A function to test each element for a condition.</param>
    /// <returns>true if the source sequence is not null and any elements in the source sequence pass the test in the specified predicate; otherwise, false.</returns>
    public static bool AnyNotNull<TSource>(this IEnumerable<TSource> source, Func<TSource, bool> predicate)
    {
        return source?.Any(predicate) == true;
    }
}

The naming of the extension method could probably be better.

Freely convert between List<T> and IEnumerable<T>

A List<T> is an IEnumerable<T>, so actually, there's no need to 'convert' a List<T> to an IEnumerable<T>. Since a List<T> is an IEnumerable<T>, you can simply assign a List<T> to a variable of type IEnumerable<T>.

The other way around, not every IEnumerable<T> is a List<T> offcourse, so then you'll have to call the ToList() member method of the IEnumerable<T>.

Remove an item from an IEnumerable<T> collection

Not removing but creating a new List without that element with LINQ:

// remove
users = users.Where(u => u.userId != 123).ToList();

// new list
var modified = users.Where(u => u.userId == 123).ToList();

How can I add an item to a IEnumerable<T> collection?

To add second message you need to -

IEnumerable<T> items = new T[]{new T("msg")};
items = items.Concat(new[] {new T("msg2")})

Convert DataTable to IEnumerable<T>

        PagedDataSource objPage = new PagedDataSource();

        DataView dataView = listData.DefaultView;
        objPage.AllowPaging = true;
        objPage.DataSource = dataView;
        objPage.PageSize = PageSize;

        TotalPages = objPage.PageCount;

        objPage.CurrentPageIndex = CurrentPage - 1;

        //Convert PagedDataSource to DataTable
        System.Collections.IEnumerator pagedData = objPage.GetEnumerator();

        DataTable filteredData = new DataTable();
        bool flagToCopyDTStruct = false;
        while (pagedData.MoveNext())
        {
            DataRowView rowView = (DataRowView)pagedData.Current;
            if (!flagToCopyDTStruct)
            {
                filteredData = rowView.Row.Table.Clone();
                flagToCopyDTStruct = true;
            }
            filteredData.LoadDataRow(rowView.Row.ItemArray, true);
        }

        //Here is your filtered DataTable
        return filterData; 

There is no ViewData item of type 'IEnumerable<SelectListItem>' that has the key 'xxx'

This is OK too; For example:
==> In "NumberController" file:

public ActionResult Create([Bind(Include = "NumberId,Number1,Number2,OperatorId")] Number number)
{
    if (ModelState.IsValid)
    {
        ...
        ...
        return RedirectToAction("Index");
    }
    ViewBag.OperatorId = new SelectList(db.Operators, "OperatorId", 
                                "OperatorSign", number.OperatorId);                
    return View();
}

==> In View file (Create.cshtml):

<div class="form-group">
    @Html.LabelFor(model => model.Number1, htmlAttributes: new { @class = 
                   "control-label col-md-2" })
    <div class="col-md-10">
        @Html.EditorFor(model => model.Number1, new { htmlAttributes = new { 
                        @class = "form-control" } })
        @Html.ValidationMessageFor(model => model.Number1, "", new { @class = 
                                   "text-danger" })
    </div>
</div>

Now if we remove this statement:

ViewBag.OperatorId = new SelectList(db.Operators, "OperatorId", "OperatorSign", number.OperatorId);

from back of the following statement (in our controller) :

return View();

we will see this error:

There is no ViewData item of type 'IEnumerable' that has the key 'OperatorId'.

* So be sure of the existing of these statements. *

What is the difference between IEnumerator and IEnumerable?

An Enumerator shows you the items in a list or collection. Each instance of an Enumerator is at a certain position (the 1st element, the 7th element, etc) and can give you that element (IEnumerator.Current) or move to the next one (IEnumerator.MoveNext). When you write a foreach loop in C#, the compiler generates code that uses an Enumerator.

An Enumerable is a class that can give you Enumerators. It has a method called GetEnumerator which gives you an Enumerator that looks at its items. When you write a foreach loop in C#, the code that it generates calls GetEnumerator to create the Enumerator used by the loop.

IEnumerable vs List - What to Use? How do they work?

Nobody mentioned one crucial difference, ironically answered on a question closed as a duplicated of this.

IEnumerable is read-only and List is not.

See Practical difference between List and IEnumerable

Converting from IEnumerable to List

If you're using an implementation of System.Collections.IEnumerable you can do like following to convert it to a List. The following uses Enumerable.Cast method to convert IEnumberable to a Generic List.

//ArrayList Implements IEnumerable interface
ArrayList _provinces = new System.Collections.ArrayList();
_provinces.Add("Western");
_provinces.Add("Eastern");

List<string> provinces = _provinces.Cast<string>().ToList();

If you're using Generic version IEnumerable<T>, The conversion is straight forward. Since both are generics, you can do like below,

IEnumerable<int> values = Enumerable.Range(1, 10);
List<int> valueList = values.ToList();

But if the IEnumerable is null, when you try to convert it to a List, you'll get ArgumentNullException saying Value cannot be null.

IEnumerable<int> values2 = null;
List<int> valueList2 = values2.ToList();

enter image description here

Therefore as mentioned in the other answer, remember to do a null check before converting it to a List.

Cannot apply indexing with [] to an expression of type 'System.Collections.Generic.IEnumerable<>

The IEnumerable<T> interface does not include an indexer, you're probably confusing it with IList<T>

If the object really is an IList<T> (e.g. List<T> or an array T[]), try making the reference to it of type IList<T> too.

Otherwise, you can use myEnumerable.ElementAt(index) which uses the Enumerable.ElementAt extension method. This should work for all IEnumerable<T>s . Note that unless the (run-time) object implements IList<T>, this will cause all of the first index + 1 items to be enumerated, with all but the last being discarded.

EDIT: As an explanation, IEnumerable<T> is simply an interface that represents "that which exposes an enumerator." A concrete implementation may well be some sort of in-memory list that does allow fast-access by index, or it may not. For instance, it could be a collection that cannot efficiently satisfy such a query, such as a linked-list (as mentioned by James Curran). It may even be no sort of in-memory data-structure at all, such as an iterator, where items are generated ('yielded') on demand, or by an enumerator that fetches the items from some remote data-source. Because IEnumerable<T> must support all these cases, indexers are excluded from its definition.

How to loop through a collection that supports IEnumerable?

Along with the already suggested methods of using a foreach loop, I thought I'd also mention that any object that implements IEnumerable also provides an IEnumerator interface via the GetEnumerator method. Although this method is usually not necessary, this can be used for manually iterating over collections, and is particularly useful when writing your own extension methods for collections.

IEnumerable<T> mySequence;
using (var sequenceEnum = mySequence.GetEnumerator())
{
    while (sequenceEnum.MoveNext())
    {
        // Do something with sequenceEnum.Current.
    }
}

A prime example is when you want to iterate over two sequences concurrently, which is not possible with a foreach loop.

Returning IEnumerable<T> vs. IQueryable<T>

There is a blog post with brief source code sample about how misuse of IEnumerable<T> can dramatically impact LINQ query performance: Entity Framework: IQueryable vs. IEnumerable.

If we dig deeper and look into the sources, we can see that there are obviously different extension methods are perfomed for IEnumerable<T>:

// Type: System.Linq.Enumerable
// Assembly: System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
// Assembly location: C:\Windows\Microsoft.NET\Framework\v4.0.30319\System.Core.dll
public static class Enumerable
{
    public static IEnumerable<TSource> Where<TSource>(
        this IEnumerable<TSource> source, 
        Func<TSource, bool> predicate)
    {
        return (IEnumerable<TSource>) 
            new Enumerable.WhereEnumerableIterator<TSource>(source, predicate);
    }
}

and IQueryable<T>:

// Type: System.Linq.Queryable
// Assembly: System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
// Assembly location: C:\Windows\Microsoft.NET\Framework\v4.0.30319\System.Core.dll
public static class Queryable
{
    public static IQueryable<TSource> Where<TSource>(
        this IQueryable<TSource> source, 
        Expression<Func<TSource, bool>> predicate)
    {
        return source.Provider.CreateQuery<TSource>(
            Expression.Call(
                null, 
                ((MethodInfo) MethodBase.GetCurrentMethod()).MakeGenericMethod(
                    new Type[] { typeof(TSource) }), 
                    new Expression[] 
                        { source.Expression, Expression.Quote(predicate) }));
    }
}

The first one returns enumerable iterator, and the second one creates query through the query provider, specified in IQueryable source.

Count the items from a IEnumerable<T> without iterating?

You can use System.Linq.

using System;
using System.Collections.Generic;
using System.Linq;

public class Test
{
    private IEnumerable<string> Tables
    {
        get {
             yield return "Foo";
             yield return "Bar";
         }
    }

    static void Main()
    {
        var x = new Test();
        Console.WriteLine(x.Tables.Count());
    }
}

You'll get the result '2'.

Shorter syntax for casting from a List<X> to a List<Y>?

In case when X derives from Y you can also use ToList<T> method instead of Cast<T>

listOfX.ToList<Y>()

Convert IEnumerable to DataTable

A 2019 answer if you're using .NET Core - use the Nuget ToDataTable library. Advantages:

Disclaimer - I'm the author of ToDataTable

Performance - I span up some Benchmark .Net tests and included them in the ToDataTable repo. The results were as follows:

Creating a 100,000 Row Datatable:

Reflection                 818.5 ms
DataTableProxy           1,068.8 ms
ToDataTable                449.0 ms

Insert line break inside placeholder attribute of a textarea?

Use &#10; in place of \n this will change the line.

Editing hosts file to redirect url?

You could use the RedirectMatch directive in Apache to do something similar you want.

It's pretty simple.

RedirectMatch / http://222.222.222.222/

Anyway, I can't see any reason to do that thing. Aren't you trying to intercept traffic? There are better ways. For Linux boxes as a router: iptables -j REDIRECT + Squid or Apache. For Cisco routers, you can use WCCP to a Cache or Web Server...

Adding external resources (CSS/JavaScript/images etc) in JSP

The reason that you get the 404 File Not Found error, is that your path to CSS given as a value to the href attribute is missing context path.

An HTTP request URL contains the following parts:

http://[host]:[port][request-path]?[query-string]

The request path is further composed of the following elements:

  • Context path: A concatenation of a forward slash (/) with the context root of the servlet's web application. Example: http://host[:port]/context-root[/url-pattern]

  • Servlet path: The path section that corresponds to the component alias that activated this request. This path starts with a forward slash (/).

  • Path info: The part of the request path that is not part of the context path or the servlet path.

Read more here.


Solutions

There are several solutions to your problem, here are some of them:

1) Using <c:url> tag from JSTL

In my Java web applications I usually used <c:url> tag from JSTL when defining the path to CSS/JavaScript/image and other static resources. By doing so you can be sure that those resources are referenced always relative to the application context (context path).

If you say, that your CSS is located inside WebContent folder, then this should work:

<link type="text/css" rel="stylesheet" href="<c:url value="/globalCSS.css" />" />

The reason why it works is explained in the "JavaServer Pages™ Standard Tag Library" version 1.2 specification chapter 7.5 (emphasis mine):

7.5 <c:url>
Builds a URL with the proper rewriting rules applied.
...
The URL must be either an absolute URL starting with a scheme (e.g. "http:// server/context/page.jsp") or a relative URL as defined by JSP 1.2 in JSP.2.2.1 "Relative URL Specification". As a consequence, an implementation must prepend the context path to a URL that starts with a slash (e.g. "/page2.jsp") so that such URLs can be properly interpreted by a client browser.

NOTE
Don't forget to use Taglib directive in your JSP to be able to reference JSTL tags. Also see an example JSP page here.


2) Using JSP Expression Language and implicit objects

An alternative solution is using Expression Language (EL) to add application context:

<link type="text/css" rel="stylesheet" href="${pageContext.request.contextPath}/globalCSS.css" />

Here we have retrieved the context path from the request object. And to access the request object we have used the pageContext implicit object.


3) Using <c:set> tag from JSTL

DISCLAIMER
The idea of this solution was taken from here.

To make accessing the context path more compact than in the solution ?2, you can first use the JSTL <c:set> tag, that sets the value of an EL variable or the property of an EL variable in any of the JSP scopes (page, request, session, or application) for later access.

<c:set var="root" value="${pageContext.request.contextPath}"/>
...
<link type="text/css" rel="stylesheet" href="${root}/globalCSS.css" />

IMPORTANT NOTE
By default, in order to set the variable in such manner, the JSP that contains this set tag must be accessed at least once (including in case of setting the value in the application scope using scope attribute, like <c:set var="foo" value="bar" scope="application" />), before using this new variable. For instance, you can have several JSP files where you need this variable. So you must ether a) both set the new variable holding context path in the application scope AND access this JSP first, before using this variable in other JSP files, or b) set this context path holding variable in EVERY JSP file, where you need to access to it.


4) Using ServletContextListener

The more effective way to make accessing the context path more compact is to set a variable that will hold the context path and store it in the application scope using a Listener. This solution is similar to solution ?3, but the benefit is that now the variable holding context path is set right at the start of the web application and is available application wide, no need for additional steps.

We need a class that implements ServletContextListener interface. Here is an example of such class:

package com.example.listener;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

@WebListener
public class AppContextListener implements ServletContextListener {

    @Override
    public void contextInitialized(ServletContextEvent event) {
        ServletContext sc = event.getServletContext();
        sc.setAttribute("ctx", sc.getContextPath());
    }

    @Override
    public void contextDestroyed(ServletContextEvent event) {}

}

Now in a JSP we can access this global variable using EL:

<link type="text/css" rel="stylesheet" href="${ctx}/globalCSS.css" />

NOTE
@WebListener annotation is available since Servlet version 3.0. If you use a servlet container or application server that supports older Servlet specifications, remove the @WebServlet annotation and instead configure the listener in the deployment descriptor (web.xml). Here is an example of web.xml file for the container that supports maximum Servlet version 2.5 (other configurations are omitted for the sake of brevity):

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
                        http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    version="2.5">
    ...  
    <listener>
        <listener-class>com.example.listener.AppContextListener</listener-class>
    </listener>
    ...
</webapp>


5) Using scriptlets

As suggested by user @gavenkoa you can also use scriptlets like this:

<%= request.getContextPath() %>

For such a small thing it is probably OK, just note that generally the use of scriptlets in JSP is discouraged.


Conclusion

I personally prefer either the first solution (used it in my previous projects most of the time) or the second, as they are most clear, intuitive and unambiguous (IMHO). But you choose whatever suits you most.


Other thoughts

You can deploy your web app as the default application (i.e. in the default root context), so it can be accessed without specifying context path. For more info read the "Update" section here.

How to open a new form from another form

Use this.Hide() instead of this.Close()

Insert array into MySQL database with PHP

most easiest way

for ($i=0; $i < count($tableData); $i++) { 

        $cost     =$tableData[$i]['cost'];
        $quantity =$tableData[$i]['quantity'];
        $price    =$tableData[$i]['price'];
        $p_id     =$tableData[$i]['p_id'];

        mysqli_query($conn,"INSERT INTO bill_details (bill_id, price, bill_date, p_id, quantity, cost) VALUES ($bill_id[bill_id],$price,$date,$p_id,$quantity,$cost)");
    }

SQLSTATE[HY000] [1698] Access denied for user 'root'@'localhost'

Users for mysql and for server are 2 different things, look how to add user to database and login with these credentials

Adding options to a <select> using jQuery?

I like to use non jquery approach:

mySelect.add(new Option('My option', 1));

Cannot attach the file *.mdf as database

As per @davide-icardi, remove the "Initial Catalog=xxx;" from web.config, but also check for your azure publish profile file to remove it from here too:
[YourAspNetProject path]\Properties\PublishProfiles[YourAspNetProjectName].pubxml

<PublishDatabaseSettings>
  <Objects xmlns="">
    <ObjectGroup Name="YourAspNetProjectName" Order="1" Enabled="True">
      <Destination Path="Data Source=AzureDataBaseServer;Initial Catalog=azureDatabase_db;User ID=AzureUser_db_sa@AzureDataBaseServer;Password=test" />
      <Object Type="DbCodeFirst">
        <Source Path="DBMigration" DbContext="YourAspNetProjectName.Models.ApplicationDbContext, YourAspNetProjectName" MigrationConfiguration="YourAspNetProjectName.Migrations.Configuration, YourAspNetProjectName" Origin="Configuration" />
      </Object>
    </ObjectGroup>
  </Objects>
</PublishDatabaseSettings>

Removing certain characters from a string in R

try: gsub('\\$', '', '$5.00$')

Installing Node.js (and npm) on Windows 10

Edit: It seems like new installers do not have this problem anymore, see this answer by Parag Meshram as my answer is likely obsolete now.

Original answer:

Follow these steps, closely:

  • http://nodejs.org/download/ download the 64 bits version, 32 is for hipsters
  • Install it anywhere you want, by default: C:\Program Files\nodejs
  • Control Panel -> System -> Advanced system settings -> Environment Variables
  • Select PATH and choose to edit it.

If the PATH variable is empty, change it to this: C:\Users\{YOUR USERNAME HERE}\AppData\Roaming\npm;C:\Program Files\nodejs

If the PATH variable already contains C:\Users\{YOUR USERNAME HERE}\AppData\Roaming\npm, append the following right after: ;C:\Program Files\nodejs

If the PATH variable contains information, but nothing regarding npm, append this to the end of the PATH: ;C:\Users\{YOUR USERNAME HERE}\AppData\Roaming\npm;C:\Program Files\nodejs

Now that the PATH variable is set correctly, you will still encounter errors. Manually go into the AppData directory and you will find that there is no npm directory inside Roaming. Manually create this directory.

Re-start the command prompt and npm will now work.

php convert datetime to UTC

With PHP 5 or superior, you may use datetime::format function (see documentation http://us.php.net/manual/en/datetime.format.php)

 echo strftime( '%e %B %Y' , 
    date_create_from_format('Y-d-m G:i:s', '2012-04-05 11:55:21')->format('U')
    );  // 4 May 2012

Largest and smallest number in an array

You (normally) cannot modify the collection you are iterating over when using foreach.

Although for and foreach seem to be similar from a developer perspective they are quite different from an implementation perspective.

Foreach uses an Iterator to access the individual objects while for doesn't know (or care) about the underlying object sequence.

How do I get the file name from a String containing the Absolute file path?

This answer works for me in c#:

using System.IO;
string fileName = Path.GetFileName("C:\Hello\AnotherFolder\The File Name.PDF");

How to find the difference in days between two dates?

Another Python version:

python -c "from datetime import date; print date(2003, 11, 22).toordinal() - date(2002, 10, 20).toordinal()"

Sort list in C# with LINQ

Well, the simplest way using LINQ would be something like this:

list = list.OrderBy(x => x.AVC ? 0 : 1)
           .ToList();

or

list = list.OrderByDescending(x => x.AVC)
           .ToList();

I believe that the natural ordering of bool values is false < true, but the first form makes it clearer IMO, because everyone knows that 0 < 1.

Note that this won't sort the original list itself - it will create a new list, and assign the reference back to the list variable. If you want to sort in place, you should use the List<T>.Sort method.

JavaScript string encryption and decryption?

I created an insecure but simple text cipher/decipher util. No dependencies with any external library.

These are the functions

const cipher = salt => {
    const textToChars = text => text.split('').map(c => c.charCodeAt(0));
    const byteHex = n => ("0" + Number(n).toString(16)).substr(-2);
    const applySaltToChar = code => textToChars(salt).reduce((a,b) => a ^ b, code);

    return text => text.split('')
        .map(textToChars)
        .map(applySaltToChar)
        .map(byteHex)
        .join('');
}

const decipher = salt => {
    const textToChars = text => text.split('').map(c => c.charCodeAt(0));
    const applySaltToChar = code => textToChars(salt).reduce((a,b) => a ^ b, code);
    return encoded => encoded.match(/.{1,2}/g)
        .map(hex => parseInt(hex, 16))
        .map(applySaltToChar)
        .map(charCode => String.fromCharCode(charCode))
        .join('');
}

And you can use them as follows:

// To create a cipher
const myCipher = cipher('mySecretSalt')

//Then cipher any text:
myCipher('the secret string')   // --> "7c606d287b6d6b7a6d7c287b7c7a61666f"

//To decipher, you need to create a decipher and use it:
const myDecipher = decipher('mySecretSalt')
myDecipher("7c606d287b6d6b7a6d7c287b7c7a61666f")    // --> 'the secret string'

How to filter keys of an object with lodash?

Just change filter to omitBy

_x000D_
_x000D_
const data = { aaa: 111, abb: 222, bbb: 333 };_x000D_
const result = _.omitBy(data, (value, key) => !key.startsWith("a"));_x000D_
console.log(result);
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js"></script>
_x000D_
_x000D_
_x000D_

Android Call an method from another class

Add this in MainActivity.

Intent intent = new Intent(getApplicationContext(), Heightimage.class);
startActivity(intent);

Display the binary representation of a number in C?

You have to write your own transformation. Only decimal, hex and octal numbers are supported with format specifiers.

Argparse optional positional arguments?

parser.add_argument also has a switch required. You can use required=False. Here is a sample snippet with Python 2.7:

parser = argparse.ArgumentParser(description='get dir')
parser.add_argument('--dir', type=str, help='dir', default=os.getcwd(), required=False)
args = parser.parse_args()

How to workaround 'FB is not defined'?

FB recommends to add the async all.js include right after body, so that FB object get prepared when you use it in page.

You can also have artificial delay using setTimeout to make sure FB object is loaded. e.g.

<script>setTimeout(function(){
FB.Event.subscribe('edge.create',
function (response) {
    alert('msg via fb');
});},2000);
</script>

How to delete an item in a list if it exists?

1) Almost-English style:

Test for presence using the in operator, then apply the remove method.

if thing in some_list: some_list.remove(thing)

The removemethod will remove only the first occurrence of thing, in order to remove all occurrences you can use while instead of if.

while thing in some_list: some_list.remove(thing)    
  • Simple enough, probably my choice.for small lists (can't resist one-liners)

2) Duck-typed, EAFP style:

This shoot-first-ask-questions-last attitude is common in Python. Instead of testing in advance if the object is suitable, just carry out the operation and catch relevant Exceptions:

try:
    some_list.remove(thing)
except ValueError:
    pass # or scream: thing not in some_list!
except AttributeError:
    call_security("some_list not quacking like a list!")

Off course the second except clause in the example above is not only of questionable humor but totally unnecessary (the point was to illustrate duck-typing for people not familiar with the concept).

If you expect multiple occurrences of thing:

while True:
    try:
        some_list.remove(thing)
    except ValueError:
        break
  • a little verbose for this specific use case, but very idiomatic in Python.
  • this performs better than #1
  • PEP 463 proposed a shorter syntax for try/except simple usage that would be handy here, but it was not approved.

However, with contextlib's suppress() contextmanager (introduced in python 3.4) the above code can be simplified to this:

with suppress(ValueError, AttributeError):
    some_list.remove(thing)

Again, if you expect multiple occurrences of thing:

with suppress(ValueError):
    while True:
        some_list.remove(thing)

3) Functional style:

Around 1993, Python got lambda, reduce(), filter() and map(), courtesy of a Lisp hacker who missed them and submitted working patches*. You can use filter to remove elements from the list:

is_not_thing = lambda x: x is not thing
cleaned_list = filter(is_not_thing, some_list)

There is a shortcut that may be useful for your case: if you want to filter out empty items (in fact items where bool(item) == False, like None, zero, empty strings or other empty collections), you can pass None as the first argument:

cleaned_list = filter(None, some_list)
  • [update]: in Python 2.x, filter(function, iterable) used to be equivalent to [item for item in iterable if function(item)] (or [item for item in iterable if item] if the first argument is None); in Python 3.x, it is now equivalent to (item for item in iterable if function(item)). The subtle difference is that filter used to return a list, now it works like a generator expression - this is OK if you are only iterating over the cleaned list and discarding it, but if you really need a list, you have to enclose the filter() call with the list() constructor.
  • *These Lispy flavored constructs are considered a little alien in Python. Around 2005, Guido was even talking about dropping filter - along with companions map and reduce (they are not gone yet but reduce was moved into the functools module, which is worth a look if you like high order functions).

4) Mathematical style:

List comprehensions became the preferred style for list manipulation in Python since introduced in version 2.0 by PEP 202. The rationale behind it is that List comprehensions provide a more concise way to create lists in situations where map() and filter() and/or nested loops would currently be used.

cleaned_list = [ x for x in some_list if x is not thing ]

Generator expressions were introduced in version 2.4 by PEP 289. A generator expression is better for situations where you don't really need (or want) to have a full list created in memory - like when you just want to iterate over the elements one at a time. If you are only iterating over the list, you can think of a generator expression as a lazy evaluated list comprehension:

for item in (x for x in some_list if x is not thing):
    do_your_thing_with(item)

Notes

  1. you may want to use the inequality operator != instead of is not (the difference is important)
  2. for critics of methods implying a list copy: contrary to popular belief, generator expressions are not always more efficient than list comprehensions - please profile before complaining

simple custom event

You haven't created an event. To do that write:

public event EventHandler<Progress> Progress;

Then, you can call Progress from within the class where it was declared like normal function or delegate:

Progress(this, new Progress("some status"));

So, if you want to report progress in TestClass, the event should be in there too and it should be also static. You can the subscribe to it from your form like this:

TestClass.Progress += SetStatus;

Also, you should probably rename Progress to ProgressEventArgs, so that it's clear what it is.

How to navigate to a section of a page

Main page

<a href="/sample.htm#page1">page1</a>
<a href="/sample.htm#page2">page2</a>

sample pages

<div id='page1'><a name="page1"></a></div>
<div id='page2'><a name="page2"></a></div>

Return index of highest value in an array

My solution to get the higher key is as follows:

max(array_keys($values['Users']));

jQuery append text inside of an existing paragraph tag

I have just discovered a way to append text and its working fine at least.

 var text = 'Put any text here';
 $('#text').append(text);

You can change text according to your need.

Hope this helps.

URL string format for connecting to Oracle database with JDBC

There are two ways to set this up. If you have an SID, use this (older) format:

jdbc:oracle:thin:@[HOST][:PORT]:SID

If you have an Oracle service name, use this (newer) format:

jdbc:oracle:thin:@//[HOST][:PORT]/SERVICE

Source: this OraFAQ page

The call to getConnection() is correct.

Also, as duffymo said, make sure the actual driver code is present by including ojdbc6.jar in the classpath, where the number corresponds to the Java version you're using.

Copying formula to the next row when inserting a new row

You need to insert the new row and then copy from the source row to the newly inserted row. Excel allows you to paste special just formulas. So in Excel:

  • Insert the new row
  • Copy the source row
  • Select the newly created target row, right click and paste special
  • Paste as formulas

VBA if required with Rows("1:1") being source and Rows("2:2") being target:

Rows("2:2").Insert Shift:=xlDown, CopyOrigin:=xlFormatFromLeftOrAbove
Rows("2:2").Clear

Rows("1:1").Copy
Rows("2:2").PasteSpecial Paste:=xlPasteFormulas, Operation:=xlNone

DataGrid get selected rows' column values

DataGrid get selected rows' column values it can be access by below code. Here grid1 is name of Gride.

private void Edit_Click(object sender, RoutedEventArgs e)
{
    DataRowView rowview = grid1.SelectedItem as DataRowView;
    string id = rowview.Row[0].ToString();
}

filtering a list using LINQ

var result = projects.Where(p => filtedTags.All(t => p.Tags.Contains(t)));

Java multiline string

It's not entirely clear from the question if author is interested in working with some sort of formatted large strings that need to have some dynamic values, but if that's the case a templating engine like StringTemplate (http://www.stringtemplate.org/) might be very useful.

A simple sample of the code that uses StringTemplate is below. The actual template ("Hello, < name >") could be loaded from an external plain text file. All indentation in the template will be preserved, and no escaping is necessary.

import org.stringtemplate.v4.*;
 
public class Hello {
    public static void main(String[] args) {
        ST hello = new ST("Hello, <name>");
        hello.add("name", "World");
        System.out.println(hello.render());
    }
}

P.S. It's always a good idea to remove large chunks of text from source code for readability and localization purposes.

Insert string in beginning of another string

It is better if you find quotation marks by using the indexof() method and then add a string behind that index.

string s="hai";
int s=s.indexof(""");

How to perform update operations on columns of type JSONB in Postgres 9.4

Maybe: UPDATE test SET data = '"my-other-name"'::json WHERE id = 1;

It worked with my case, where data is a json type

How to use Session attributes in Spring-mvc

Use @SessionAttributes

See the docs: Using @SessionAttributes to store model attributes in the HTTP session between requests

"Understanding Spring MVC Model And Session Attributes" also gives a very good overview of Spring MVC sessions and explains how/when @ModelAttributes are transferred into the session (if the controller is @SessionAttributes annotated).

That article also explains that it is better to use @SessionAttributes on the model instead of setting attributes directly on the HttpSession because that helps Spring MVC to be view-agnostic.

How to get multiline input from user

raw_input can correctly handle the EOF, so we can write a loop, read till we have received an EOF (Ctrl-D) from user:

Python 3

print("Enter/Paste your content. Ctrl-D or Ctrl-Z ( windows ) to save it.")
contents = []
while True:
    try:
        line = input()
    except EOFError:
        break
    contents.append(line)

Python 2

print "Enter/Paste your content. Ctrl-D or Ctrl-Z ( windows ) to save it."
contents = []
while True:
    try:
        line = raw_input("")
    except EOFError:
        break
    contents.append(line)

Let JSON object accept bytes or let urlopen output strings

This one works for me, I used 'request' library with json() check out the doc in requests for humans

import requests

url = 'here goes your url'

obj = requests.get(url).json() 

WCF - How to Increase Message Size Quota

For me, all I had to do is add maxReceivedMessageSize="2147483647" to the client app.config. The server left untouched.

Create an array of strings

Another option:

names = repmat({'Sample Text'}, 10, 1)

How to deal with floating point number precision in JavaScript?

You could use a regex to check if the number ends with a long string of 0s followed by a small remainder:

// using max number of 0s = 8, maximum remainder = 4 digits
x = 0.1048000000000051
parseFloat(x.toString().replace(/(\.[\d]+[1-9])0{8,}[1-9]{0,4}/, '$1'), 10)
// = 0.1048

How do I trigger a macro to run after a new mail is received in Outlook?

Try something like this inside ThisOutlookSession:

Private Sub Application_NewMail()
    Call Your_main_macro
End Sub

My outlook vba just fired when I received an email and had that application event open.

Edit: I just tested a hello world msg box and it ran after being called in the application_newmail event when an email was received.

Is HTML considered a programming language?

I think not exactly a programming language, but exactly what its name says: a markup language. We cannot program using just pure, HTML. But just annotate how to present content.

But if you consider programming the act of tell the computer how to present contents, it is a programming language.

Invoking Java main method with parameters from Eclipse

AFAIK there isn't a built-in mechanism in Eclipse for this.

The closest you can get is to create a wrapper that prompts you for these values and invokes the (hardcoded) main. You then get you execution history as long as you don't clear terminated processes. Two variations on this are either to use JUNit, or to use injection or parameter so that your wrapper always connects to the correct class for its main.

Call An Asynchronous Javascript Function Synchronously

What you want is actually possible now. If you can run the asynchronous code in a service worker, and the synchronous code in a web worker, then you can have the web worker send a synchronous XHR to the service worker, and while the service worker does the async things, the web worker's thread will wait. This is not a great approach, but it could work.

CASE statement in SQLite query

The syntax is wrong in this clause (and similar ones)

    CASE lkey WHEN lkey > 5 THEN
        lkey + 2
    ELSE
        lkey
    END

It's either

    CASE WHEN [condition] THEN [expression] ELSE [expression] END

or

    CASE [expression] WHEN [value] THEN [expression] ELSE [expression] END

So in your case it would read:

    CASE WHEN lkey > 5 THEN
        lkey + 2
    ELSE
        lkey
    END

Check out the documentation (The CASE expression):

http://www.sqlite.org/lang_expr.html

How to compare two date values with jQuery

just use the jQuery datepicker UI library and convert both your strings into date format, then you can easily compare. following link might be useful

https://stackoverflow.com/questions/2974496/jquery-javascript-convert-date-string-to-date

cheers..!!

Laravel 5.2 not reading env file

For me it has worked this in this order:

php artisan config:cache
php artisan config:clear
php artisan cache:clear

And I've tried all the rests without luck.

Unable to connect to mongodb Error: couldn't connect to server 127.0.0.1:27017 at src/mongo/shell/mongo.js:L112

Start mongod server first

mongod

Open another terminal window

Start mongo shell

mongo

SQL Server AS statement aliased column within WHERE statement

This would work on your edited question !

SELECT * FROM (SELECT <Column_List>,  
( 6371*1000 * acos( cos( radians(42.3936868308) ) * cos( radians( lat ) ) * cos( radians( lon ) - radians(-72.5277256966) ) + sin( radians(42.3936868308) ) * sin( radians( lat ) ) ) )  
AS distance 
FROM poi_table) TMP
WHERE distance < 500; 

How can I create an utility class?

I would make the class final and every method would be static.

So the class cannot be extended and the methods can be called by Classname.methodName. If you add members, be sure that they work thread safe ;)

How to change font size on part of the page in LaTeX?

\begingroup
    \fontsize{10pt}{12pt}\selectfont
    \begin{verbatim}  
        % how to set font size here to 10 px ?  
    \end{verbatim}  
\endgroup

How do I view the SQL generated by the Entity Framework?

I've just done this:

IQueryable<Product> query = EntitySet.Where(p => p.Id == id);
Debug.WriteLine(query);

And the result shown in the Output:

SELECT 
    [Extent1].[Id] AS [Id], 
    [Extent1].[Code] AS [Code], 
    [Extent1].[Name] AS [Name], 
    [Extent2].[Id] AS [Id1], 
    [Extent2].[FileName] AS [FileName], 
    FROM  [dbo].[Products] AS [Extent1]
    INNER JOIN [dbo].[PersistedFiles] AS [Extent2] ON [Extent1].[PersistedFileId] = [Extent2].[Id]
    WHERE [Extent1].[Id] = @p__linq__0

How do I create a new branch?

Right click and open SVN Repo-browser:

Enter image description here

Right click on Trunk (working copy) and choose Copy to...:

Enter image description here

Input the respective branch's name/path:

Enter image description here

Click OK, type the respective log message, and click OK.

How to join two JavaScript Objects, without using JQUERY

WORKING FIDDLE

Simplest Way with Jquery -

var finalObj = $.extend(obj1, obj2);

Without Jquery -

var finalobj={};
for(var _obj in obj1) finalobj[_obj ]=obj1[_obj];
for(var _obj in obj2) finalobj[_obj ]=obj2[_obj];

How to download a file via FTP with Python ftplib

handle = open(path.rstrip("/") + "/" + filename.lstrip("/"), 'wb')
ftp.retrbinary('RETR %s' % filename, handle.write)

How to change lowercase chars to uppercase using the 'keyup' event?

This worked for me

jQuery(document).ready(function(){ 
        jQuery('input').keyup(function() {
            this.value = this.value.toLocaleUpperCase();
        });
        jQuery('textarea').keyup(function() {
            this.value = this.value.toLocaleUpperCase();
        });
 });

<div> cannot appear as a descendant of <p>

I got this error when using Chakra UI in React when doing inline styling for some text. The correct way to do the inline styling was using the span element, as others also said for other styling frameworks. The correct code:

<Text as="span" fontWeight="bold">
    Bold text
    <Text display="inline" fontWeight="normal">normal inline text</Text>
</Text>

How to scale a UIImageView proportionally?

Fixed easily, once I found the documentation!

 imageView.contentMode = .scaleAspectFit

Loop through properties in JavaScript object with Lodash

For your stated desire to "check if a property exists" you can directly use Lo-Dash's has.

var exists = _.has(myObject, propertyNameToCheck);

how to call javascript function in html.actionlink in asp.net mvc?

This is the only one that worked for me in .cshtml file:

@Html.ActionLink(
   "Name", 
   "Action", 
   "Controller", 
   routeValues: null, 
   htmlAttributes:new Dictionary<string, object> {{ "onclick", "alert('Test');" }})

I hope this helps.

Lotus Notes email as an attachment to another email

The only way I know is this:

Reassure that preferences | Basic Notes Client configuration | Drag and drop saves as eml file is checked

1) Drag your email to e.g. your desktop or to an explorer instance (will be saved as an eml file).
2) Attach this file to your opened email by either selecting it with the paperclip menu item or drag 'n drop the file into the opened email.

How to insert a file in MySQL database?

You need to use BLOB, there's TINY, MEDIUM, LONG, and just BLOB, as with other types, choose one according to your size needs.

TINYBLOB 255
BLOB 65535
MEDIUMBLOB 16777215
LONGBLOB 4294967295
(in bytes)

The insert statement would be fairly normal. You need to read the file using fread and then addslashes to it.

Verify ImageMagick installation

In Bash you can check if Imagick is an installed module:

$ php -m | grep imagick

If the response is blank it is not installed.

How to embed a Google Drive folder in a website

For business/Gsuite apps or whatever they call them, you can specify the domain (had problem with 500 errors with the original answer when logged into multiple Google accounts).

<iframe 
  src="https://drive.google.com/a/YOUR_COMPANY_DOMAIN/embeddedfolderview?id=FOLDER-ID" 
  style="width:100%; height:600px; border:0;"
>
</iframe>

Jquery: how to trigger click event on pressing enter key

This appear to be default behaviour now, so it's enough to do:

$("#press-enter").on("click", function(){alert("You `clicked' or 'Entered' me!")})

You can try it in this JSFiddle

Tested on: Chrome 56.0 and Firefox (Dev Edition) 54.0a2, both with jQuery 2.2.x and 3.x

How to add headers to OkHttp request interceptor?

here is a useful gist from lfmingo

OkHttpClient.Builder httpClient = new OkHttpClient.Builder();

httpClient.addInterceptor(new Interceptor() {

    @Override
    public Response intercept(Interceptor.Chain chain) throws IOException {
        Request original = chain.request();

        Request request = original.newBuilder()
            .header("User-Agent", "Your-App-Name")
            .header("Accept", "application/vnd.yourapi.v1.full+json")
            .method(original.method(), original.body())
            .build();

        return chain.proceed(request);
    }
}

OkHttpClient client = httpClient.build();

Retrofit retrofit = new Retrofit.Builder()  
    .baseUrl(API_BASE_URL)
    .addConverterFactory(GsonConverterFactory.create())
    .client(client)
    .build();

Launching a website via windows commandline

To open a URL with the default browser, you can execute:

rundll32 url.dll,FileProtocolHandler https://www.google.com

I had issues with URL parameters with the other solutions. However, this one seemed to work correctly.

Quick Sort Vs Merge Sort

Quick sort is typically faster than merge sort when the data is stored in memory. However, when the data set is huge and is stored on external devices such as a hard drive, merge sort is the clear winner in terms of speed. It minimizes the expensive reads of the external drive and also lends itself well to parallel computing.

Accessing items in an collections.OrderedDict by index

If you have pandas installed, you can convert the ordered dict to a pandas Series. This will allow random access to the dictionary elements.

>>> import collections
>>> import pandas as pd
>>> d = collections.OrderedDict()
>>> d['foo'] = 'python'
>>> d['bar'] = 'spam'

>>> s = pd.Series(d)

>>> s['bar']
spam
>>> s.iloc[1]
spam
>>> s.index[1]
bar

Combine two columns of text in pandas dataframe

more efficient is

def concat_df_str1(df):
    """ run time: 1.3416s """
    return pd.Series([''.join(row.astype(str)) for row in df.values], index=df.index)

and here is a time test:

import numpy as np
import pandas as pd

from time import time


def concat_df_str1(df):
    """ run time: 1.3416s """
    return pd.Series([''.join(row.astype(str)) for row in df.values], index=df.index)


def concat_df_str2(df):
    """ run time: 5.2758s """
    return df.astype(str).sum(axis=1)


def concat_df_str3(df):
    """ run time: 5.0076s """
    df = df.astype(str)
    return df[0] + df[1] + df[2] + df[3] + df[4] + \
           df[5] + df[6] + df[7] + df[8] + df[9]


def concat_df_str4(df):
    """ run time: 7.8624s """
    return df.astype(str).apply(lambda x: ''.join(x), axis=1)


def main():
    df = pd.DataFrame(np.zeros(1000000).reshape(100000, 10))
    df = df.astype(int)

    time1 = time()
    df_en = concat_df_str4(df)
    print('run time: %.4fs' % (time() - time1))
    print(df_en.head(10))


if __name__ == '__main__':
    main()

final, when sum(concat_df_str2) is used, the result is not simply concat, it will trans to integer.

How to examine processes in OS X's Terminal?

To sort by cpu usage: top -o cpu

Unable to negotiate with XX.XXX.XX.XX: no matching host key type found. Their offer: ssh-dss

If you're like me, and would rather not make this security hole system or user-wide, then you can add a config option to any git repos that need this by running this command in those repos. (note only works with git version >= 2.10, released 2016-09-04)

git config core.sshCommand 'ssh -oHostKeyAlgorithms=+ssh-dss'

This only works after the repo is setup however. If you're not comfortable adding a remote manually (and just want to clone) then you can run the clone like this:

GIT_SSH_COMMAND='ssh -oHostKeyAlgorithms=+ssh-dss' git clone ssh://user@host/path-to-repository

then run the first command to make it permanent.

If you don't have the latest, and still would like to keep the hole as local as possible I recommend putting

export GIT_SSH_COMMAND='ssh -oHostKeyAlgorithms=+ssh-dss'

in a file somewhere, say git_ssh_allow_dsa_keys.sh, and sourceing it when needed.

Create a rounded button / button with border-radius in Flutter

     Container(
        width: yourWidth,
        height: yourHeight ,
        decoration: BoxDecoration(
            borderRadius: radius,
            gradient: yourGradient,
            border: yourBorder),
        child: FlatButton(
          onPressed: {} (),
          shape: RoundedRectangleBorder(borderRadius: radius),
    .......

and use the same radius.

What is the best Java email address validation method?

I'm just wondering why nobody came up with @Email from Hibernate Validator's additional constraints. The validator itself is EmailValidator.

How can I right-align text in a DataGridView column?

I know this is old, but for those surfing this question, the answer by MUG4N will align all columns that use the same defaultcellstyle. I'm not using autogeneratecolumns so that is not acceptable. Instead I used:

e.Column.DefaultCellStyle = new DataGridViewCellStyle(e.Column.DefaultCellStyle);
e.Column.DefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleRight;

In this case e is from:

Grd_ColumnAdded(object sender, DataGridViewColumnEventArgs e)  

How to compare two NSDates: Which is more recent?

Why don't you guys use these NSDate compare methods:

- (NSDate *)earlierDate:(NSDate *)anotherDate;
- (NSDate *)laterDate:(NSDate *)anotherDate;

Why does modulus division (%) only work with integers?

The modulo operator % in C and C++ is defined for two integers, however, there is an fmod() function available for usage with doubles.

How can I open a .db file generated by eclipse(android) form DDMS-->File explorer-->data--->data-->packagename-->database?

One of the way to browse your database is to use questoid sqlite manager.

# 1. Download questoid manager from this link .

# 2. Drop this file into your eclipse --> dropins.

# 3. Restart your eclipse.

# 4. Now go to your file explorer and click your database. you can find a blue database icon enabled in the top right corner.

# 5. Double click the icon and you can see ur inserted fields/tables/ in the database

Gradle Build Android Project "Could not resolve all dependencies" error

I had this message in Android Studio 2.1.1 in the Gradle Build tab. I installed a lot of files from the SDK Manager but it did not help.

I needed to click the next tab "Gradle Sync". There was a link "Install Repository and sync project" which installed the "Android Support Repository".

find the array index of an object with a specific key value in underscore

I got similar case but in contrary is to find the used key based on index of a given object's. I could find solution in underscore using Object.values to returns object in to an array to get the occurred index.

_x000D_
_x000D_
var tv = {id1:1,id2:2};_x000D_
var voteIndex = 1;_x000D_
console.log(_.findKey(tv, function(item) {_x000D_
  return _.indexOf(Object.values(tv), item) == voteIndex;_x000D_
}));
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js"></script>
_x000D_
_x000D_
_x000D_

Pythonic way of checking if a condition holds for any element of a list

any():

if any(t < 0 for t in x):
    # do something

Also, if you're going to use "True in ...", make it a generator expression so it doesn't take O(n) memory:

if True in (t < 0 for t in x):

Difference between java.lang.RuntimeException and java.lang.Exception

Exceptions are a good way to handle unexpected events in your application flow. RuntimeException are unchecked by the Compiler but you may prefer to use Exceptions that extend Exception Class to control the behaviour of your api clients as they are required to catch errors for them to compile. Also forms good documentation.

If want to achieve clean interface use inheritance to subclass the different types of exception your application has and then expose the parent exception.

How to get object length

You might have an undefined property in the object. If using the method of Object.keys(data).length is used those properties will also be counted.

You might want to filter them out out.

Object.keys(data).filter((v) => {return data[v] !== undefined}).length

How to echo shell commands as they are executed

Another option is to put "-x" at the top of your script instead of on the command line:

$ cat ./server
#!/bin/bash -x
ssh user@server

$ ./server
+ ssh user@server
user@server's password: ^C
$

Convert ArrayList<String> to String[] array

An alternative in Java 8:

String[] strings = list.stream().toArray(String[]::new);

JFrame: How to disable window resizing?

Use setResizable on your JFrame

yourFrame.setResizable(false);

But extending JFrame is generally a bad idea.

Oracle SQL query for Date format

you can use this command by getting your data. this will extract your data...

select * from employees where to_char(es_date,'dd/mon/yyyy')='17/jun/2003';

how to set "camera position" for 3d plots using python/matplotlib?

Try the following code to find the optimal camera position

Move the viewing angle of the plot using the keyboard keys as mentioned in the if clause

Use print to get the camera positions

def move_view(event):
    ax.autoscale(enable=False, axis='both') 
    koef = 8
    zkoef = (ax.get_zbound()[0] - ax.get_zbound()[1]) / koef
    xkoef = (ax.get_xbound()[0] - ax.get_xbound()[1]) / koef
    ykoef = (ax.get_ybound()[0] - ax.get_ybound()[1]) / koef
    ## Map an motion to keyboard shortcuts
    if event.key == "ctrl+down":
        ax.set_ybound(ax.get_ybound()[0] + xkoef, ax.get_ybound()[1] + xkoef)
    if event.key == "ctrl+up":
        ax.set_ybound(ax.get_ybound()[0] - xkoef, ax.get_ybound()[1] - xkoef)
    if event.key == "ctrl+right":
        ax.set_xbound(ax.get_xbound()[0] + ykoef, ax.get_xbound()[1] + ykoef)
    if event.key == "ctrl+left":
        ax.set_xbound(ax.get_xbound()[0] - ykoef, ax.get_xbound()[1] - ykoef)
    if event.key == "down":
        ax.set_zbound(ax.get_zbound()[0] - zkoef, ax.get_zbound()[1] - zkoef)
    if event.key == "up":
        ax.set_zbound(ax.get_zbound()[0] + zkoef, ax.get_zbound()[1] + zkoef)
    # zoom option
    if event.key == "alt+up":
        ax.set_xbound(ax.get_xbound()[0]*0.90, ax.get_xbound()[1]*0.90)
        ax.set_ybound(ax.get_ybound()[0]*0.90, ax.get_ybound()[1]*0.90)
        ax.set_zbound(ax.get_zbound()[0]*0.90, ax.get_zbound()[1]*0.90)
    if event.key == "alt+down":
        ax.set_xbound(ax.get_xbound()[0]*1.10, ax.get_xbound()[1]*1.10)
        ax.set_ybound(ax.get_ybound()[0]*1.10, ax.get_ybound()[1]*1.10)
        ax.set_zbound(ax.get_zbound()[0]*1.10, ax.get_zbound()[1]*1.10)
    
    # Rotational movement
    elev=ax.elev
    azim=ax.azim
    if event.key == "shift+up":
        elev+=10
    if event.key == "shift+down":
        elev-=10
    if event.key == "shift+right":
        azim+=10
    if event.key == "shift+left":
        azim-=10

    ax.view_init(elev= elev, azim = azim)

    # print which ever variable you want 

    ax.figure.canvas.draw()

fig.canvas.mpl_connect("key_press_event", move_view)

plt.show()

java.util.zip.ZipException: duplicate entry during packageAllDebugClassesForMultiDex

Simple Remove Your Jar file from dependencies gardle.project as v7 and run your project

OSError: [Errno 8] Exec format error

Have you tried this?

Out = subprocess.Popen('/usr/local/bin/script hostname = actual_server_name -p LONGLIST'.split(), shell=False,stdout=subprocess.PIPE,stderr=subprocess.PIPE) 

Edited per the apt comment from @J.F.Sebastian

How to copy selected files from Android with adb pull

Pull multiple files using regex:

Create pullFiles.sh:

#!/bin/bash
HOST_DIR=<pull-to>
DEVICE_DIR=/sdcard/<pull-from>
EXTENSION=".jpg"

for file in $(adb shell ls $DEVICE_DIR | grep $EXTENSION'$')
do
    file=$(echo -e $file | tr -d "\r\n"); # EOL fix
    adb pull $DEVICE_DIR/$file $HOST_DIR/$file;
done

Run it:

Make it executable: chmod +x pullFiles.sh

Run it: ./pullFiles.sh

Notes:

  • as is, won't work when filenames have spaces
  • includes a fix for end-of-line (EOL) on Android, which is a "\r\n"

SQL Server - transactions roll back on error?

From MDSN article, Controlling Transactions (Database Engine).

If a run-time statement error (such as a constraint violation) occurs in a batch, the default behavior in the Database Engine is to roll back only the statement that generated the error. You can change this behavior using the SET XACT_ABORT statement. After SET XACT_ABORT ON is executed, any run-time statement error causes an automatic rollback of the current transaction. Compile errors, such as syntax errors, are not affected by SET XACT_ABORT. For more information, see SET XACT_ABORT (Transact-SQL).

In your case it will rollback the complete transaction when any of inserts fail.

How to resize an image to a specific size in OpenCV?

For your information, the python equivalent is:

imageBuffer = cv.LoadImage( strSrc )
nW = new X size
nH = new Y size
smallerImage = cv.CreateImage( (nH, nW), imageBuffer.depth, imageBuffer.nChannels )
cv.Resize( imageBuffer, smallerImage , interpolation=cv.CV_INTER_CUBIC )
cv.SaveImage( strDst, smallerImage )

CryptographicException 'Keyset does not exist', but only through WCF

To solve the “Keyset does not exist” when browsing from IIS: It may be for the private permission

To view and give the permission:

  1. Run>mmc>yes
  2. click on file
  3. Click on Add/remove snap-in…
  4. Double click on certificate
  5. Computer Account
  6. Next
  7. Finish
  8. Ok
  9. Click on Certificates(Local Computer)
  10. Click on Personal
  11. Click Certificates

To give the permission:

  1. Right Click on the name of certificate
  2. All Tasks>Manage Private Keys…
  3. Add and give the privilege( adding IIS_IUSRS and giving it the privilege works for me )

What are the minimum margins most printers can handle?

As a general rule of thumb, I use 1 cm margins when producing pdfs. I work in the geospatial industry and produce pdf maps that reference a specific geographic scale. Therefore, I do not have the option to 'fit document to printable area,' because this would make the reference scale inaccurate. You must also realize that when you fit to printable area, you are fitting your already existing margins inside the printer margins, so you end up with double margins. Make your margins the right size and your documents will print perfectly. Many modern printers can print with margins less than 3 mm, so 1 cm as a general rule should be sufficient. However, if it is a high profile job, get the specs of the printer you will be printing with and ensure that your margins are adequate. All you need is the brand and model number and you can find spec sheets through a google search.

write a shell script to ssh to a remote machine and execute commands

This work for me.

Syntax : ssh -i pemfile.pem user_name@ip_address 'command_1 ; command 2; command 3'

#! /bin/bash

echo "########### connecting to server and run commands in sequence ###########"
ssh -i ~/.ssh/ec2_instance.pem ubuntu@ip_address 'touch a.txt; touch b.txt; sudo systemctl status tomcat.service'

java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to com.testing.models.Account

The way I could mitigate the JSON Array to collection of LinkedHashMap objects problem was by using CollectionType rather than a TypeReference . This is what I did and worked:

public <T> List<T> jsonArrayToObjectList(String json, Class<T> tClass) throws IOException {
    ObjectMapper mapper = new ObjectMapper();
    CollectionType listType = mapper.getTypeFactory().constructCollectionType(ArrayList.class, tClass);
    List<T> ts = mapper.readValue(json, listType);
    LOGGER.debug("class name: {}", ts.get(0).getClass().getName());
    return ts;
}

Using the TypeReference, I was still getting an ArrayList of LinkedHashMaps, i.e. does not work:

public <T> List<T> jsonArrayToObjectList(String json, Class<T> tClass) throws IOException {
    ObjectMapper mapper = new ObjectMapper();
    List<T> ts = mapper.readValue(json, new TypeReference<List<T>>(){});
    LOGGER.debug("class name: {}", ts.get(0).getClass().getName());
    return ts;
}

If isset $_POST

You can simply use:

if($_POST['username'] and $_POST['password']){
  $username = $_POST['username'];
  $password = $_POST['password'];
}

Alternatively, use empty()

if(!empty($_POST['username']) and !empty($_POST['password'])){
  $username = $_POST['username'];
  $password = $_POST['password'];
}

Left Outer Join using + sign in Oracle 11g

There is some incorrect information in this thread. I copied and pasted the incorrect information:

LEFT OUTER JOIN

SELECT *
FROM A, B
WHERE A.column = B.column(+)

RIGHT OUTER JOIN

SELECT *
FROM A, B
WHERE B.column(+) = A.column

The above is WRONG!!!!! It's reversed. How I determined it's incorrect is from the following book:

Oracle OCP Introduction to Oracle 9i: SQL Exam Guide. Page 115 Table 3-1 has a good summary on this. I could not figure why my converted SQL was not working properly until I went old school and looked in a printed book!

Here is the summary from this book, copied line by line:

Oracle outer Join Syntax:

from tab_a a, tab_b b,                                       
where a.col_1 + = b.col_1                                     

ANSI/ISO Equivalent:

from tab_a a left outer join  
tab_b b on a.col_1 = b.col_1

Notice here that it's the reverse of what is posted above. I suppose it's possible for this book to have errata, however I trust this book more so than what is in this thread. It's an exam guide for crying out loud...

How to find files recursively by file type and copy them to a directory while in ssh?

Something like this should work.

ssh [email protected] 'find -type f -name "*.pdf" -exec cp {} ./pdfsfolder \;'

MySQL: #126 - Incorrect key file for table

I got this error when I set ft_min_word_len = 2 in my.cnf, which lowers the minimum word length in a full text index to 2, from the default of 4.

Repairing the table fixed the problem.

How to use external ".js" files

You can simply add your JavaScript in body segment like this:

<body>

<script src="myScript.js"> </script>
</body>

myScript will be the file name for your JavaScript. Just write the code and enjoy!

No value accessor for form control with name: 'recipient'

Make sure you import MaterialModule as well since you are using md-input which does not belong to FormsModule

Printing result of mysql query from variable

This will print out the query:

$query = "SELECT order_date, no_of_items, shipping_charge, SUM(total_order_amount) as test FROM `orders` WHERE DATE(`order_date`) = DATE(NOW()) GROUP BY DATE(`order_date`)";

$dave= mysql_query($query) or die(mysql_error());
print $query;

This will print out the results:

$query = "SELECT order_date, no_of_items, shipping_charge, SUM(total_order_amount) as test FROM `orders` WHERE DATE(`order_date`) = DATE(NOW()) GROUP BY DATE(`order_date`)";

$dave= mysql_query($query) or die(mysql_error());

while($row = mysql_fetch_assoc($dave)){
    foreach($row as $cname => $cvalue){
        print "$cname: $cvalue\t";
    }
    print "\r\n";
}

Update using LINQ to SQL

AdventureWorksDataContext db = new AdventureWorksDataContext();
db.Log = Console.Out;

// Get hte first customer record
Customer c = from cust in db.Customers select cust where id = 5;
Console.WriteLine(c.CustomerType);
c.CustomerType = 'I';
db.SubmitChanges(); // Save the changes away

cursor.fetchall() vs list(cursor) in Python

A (MySQLdb/PyMySQL-specific) difference worth noting when using a DictCursor is that list(cursor) will always give you a list, while cursor.fetchall() gives you a list unless the result set is empty, in which case it gives you an empty tuple. This was the case in MySQLdb and remains the case in the newer PyMySQL, where it will not be fixed for backwards-compatibility reasons. While this isn't a violation of Python Database API Specification, it's still surprising and can easily lead to a type error caused by wrongly assuming that the result is a list, rather than just a sequence.

Given the above, I suggest always favouring list(cursor) over cursor.fetchall(), to avoid ever getting caught out by a mysterious type error in the edge case where your result set is empty.

Extract XML Value in bash script

As Charles Duffey has stated, XML parsers are best parsed with a proper XML parsing tools. For one time job the following should work.

grep -oPm1 "(?<=<title>)[^<]+"

Test:

$ echo "$data"
<item> 
  <title>15:54:57 - George:</title>
  <description>Diane DeConn? You saw Diane DeConn!</description> 
</item> 
<item> 
  <title>15:55:17 - Jerry:</title> 
  <description>Something huh?</description>
$ title=$(grep -oPm1 "(?<=<title>)[^<]+" <<< "$data")
$ echo "$title"
15:54:57 - George:

How to get a Color from hexadecimal Color String

If you define a color in your XML and want to use it to change background color or something this API is the one your are looking for:

 ((TextView) view).setBackgroundResource(R.drawable.your_color_here);

In my sample I used it for TestView

Replace duplicate spaces with a single space in T-SQL

Just Adding Another Method-

Replacing Multiple Spaces with Single Space WITHOUT Using REPLACE in SQL Server-

DECLARE @TestTable AS TABLE(input VARCHAR(MAX));

INSERT INTO @TestTable VALUES
('HAPPY         NEWYEAR     2020'),
('WELCOME       ALL     !');

SELECT
    CAST('<r><![CDATA[' + input + ']]></r>' AS XML).value('(/r/text())[1] cast as xs:token?','VARCHAR(MAX)')
    AS Expected_Result
FROM @TestTable;

--OUTPUT
/*
Expected_Result
HAPPY NEWYEAR 2020
WELCOME ALL !
*/

Is there a "do ... while" loop in Ruby?

How about this?

people = []

until (info = gets.chomp).empty?
  people += [Person.new(info)]
end

How do you write to a folder on an SD card in Android?

Add Permission to Android Manifest

Add this WRITE_EXTERNAL_STORAGE permission to your applications manifest.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="your.company.package"
    android:versionCode="1"
    android:versionName="0.1">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <!-- ... -->
    </application>
    <uses-sdk android:minSdkVersion="7" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
</manifest> 

Check availability of external storage

You should always check for availability first. A snippet from the official android documentation on external storage.

boolean mExternalStorageAvailable = false;
boolean mExternalStorageWriteable = false;
String state = Environment.getExternalStorageState();

if (Environment.MEDIA_MOUNTED.equals(state)) {
    // We can read and write the media
    mExternalStorageAvailable = mExternalStorageWriteable = true;
} else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
    // We can only read the media
    mExternalStorageAvailable = true;
    mExternalStorageWriteable = false;
} else {
    // Something else is wrong. It may be one of many other states, but all we need
    //  to know is we can neither read nor write
    mExternalStorageAvailable = mExternalStorageWriteable = false;
}

Use a Filewriter

At last but not least forget about the FileOutputStream and use a FileWriter instead. More information on that class form the FileWriter javadoc. You'll might want to add some more error handling here to inform the user.

// get external storage file reference
FileWriter writer = new FileWriter(getExternalStorageDirectory()); 
// Writes the content to the file
writer.write("This\n is\n an\n example\n"); 
writer.flush();
writer.close();

Visual Studio - How to change a project's folder name and solution name without breaking the solution

go to my start-documents-iisExpress-config and then right click on applicationhost and select open with visual studio 2013 for web you will get into applicationhost.config window in the visual studio and now in the region chsnge the physical path to the path where your project is placed

Calling a stored procedure in Oracle with IN and OUT parameters

Go to Menu Tool -> SQL Output, Run the PL/SQL statement, the output will show on SQL Output panel.

How do you build a Singleton in Dart?

Here's a concise example that combines the other solutions. Accessing the singleton can be done by:

  • Using a singleton global variable that points to the instance.
  • The common Singleton.instance pattern.
  • Using the default constructor, which is a factory that returns the instance.

Note: You should implement only one of the three options so that code using the singleton is consistent.

Singleton get singleton => Singleton.instance;
ComplexSingleton get complexSingleton => ComplexSingleton._instance;

class Singleton {
  static final Singleton instance = Singleton._private();
  Singleton._private();
  factory Singleton() => instance;
}

class ComplexSingleton {
  static ComplexSingleton _instance;
  static ComplexSingleton get instance => _instance;
  static void init(arg) => _instance ??= ComplexSingleton._init(arg);

  final property;
  ComplexSingleton._init(this.property);
  factory ComplexSingleton() => _instance;
}

If you need to do complex initialization, you'll just have to do so before using the instance later in the program.

Example

void main() {
  print(identical(singleton, Singleton.instance));        // true
  print(identical(singleton, Singleton()));               // true
  print(complexSingleton == null);                        // true
  ComplexSingleton.init(0); 
  print(complexSingleton == null);                        // false
  print(identical(complexSingleton, ComplexSingleton())); // true
}

Laravel Eloquent "WHERE NOT IN"

You can use WhereNotIn in the following way:

$category=DB::table('category')
          ->whereNotIn('category_id',[14 ,15])
          ->get();`enter code here`

What does operator "dot" (.) mean?

There is a whole page in the MATLAB documentation dedicated to this topic: Array vs. Matrix Operations. The gist of it is below:

MATLAB® has two different types of arithmetic operations: array operations and matrix operations. You can use these arithmetic operations to perform numeric computations, for example, adding two numbers, raising the elements of an array to a given power, or multiplying two matrices.

Matrix operations follow the rules of linear algebra. By contrast, array operations execute element by element operations and support multidimensional arrays. The period character (.) distinguishes the array operations from the matrix operations. However, since the matrix and array operations are the same for addition and subtraction, the character pairs .+ and .- are unnecessary.

How to turn off INFO logging in Spark?

Spark 1.6.2:

log4j = sc._jvm.org.apache.log4j
log4j.LogManager.getRootLogger().setLevel(log4j.Level.ERROR)

Spark 2.x:

spark.sparkContext.setLogLevel('WARN')

(spark being the SparkSession)

Alternatively the old methods,

Rename conf/log4j.properties.template to conf/log4j.properties in Spark Dir.

In the log4j.properties, change log4j.rootCategory=INFO, console to log4j.rootCategory=WARN, console

Different log levels available:

  • OFF (most specific, no logging)
  • FATAL (most specific, little data)
  • ERROR - Log only in case of Errors
  • WARN - Log only in case of Warnings or Errors
  • INFO (Default)
  • DEBUG - Log details steps (and all logs stated above)
  • TRACE (least specific, a lot of data)
  • ALL (least specific, all data)

How to check if cursor exists (open status)

This happened to me when a stored procedure running in SSMS encountered an error during the loop, while the cursor was in use to iterate over records and before the it was closed. To fix it I added extra code in the CATCH block to close the cursor if it is still open (using CURSOR_STATUS as other answers here suggest).

How do I compare two string variables in an 'if' statement in Bash?

For a version with pure Bash and without test, but really ugly, try:

if ( exit "${s1/*$s2*/0}" )2>/dev/null
then
   echo match
fi

Explanation: In ( )an extra subshell is opened. It exits with 0 if there was a match, and it tries to exit with $s1 if there was no match which raises an error (ugly). This error is directed to /dev/null.

How to check if a json key exists?

you could JSONObject#has, providing the key as input and check if the method returns true or false. You could also

use optString instead of getString:

Returns the value mapped by name if it exists, coercing it if necessary. Returns the empty string if no such mapping exists

getting the index of a row in a pandas apply function

To answer the original question: yes, you can access the index value of a row in apply(). It is available under the key name and requires that you specify axis=1 (because the lambda processes the columns of a row and not the rows of a column).

Working example (pandas 0.23.4):

>>> import pandas as pd
>>> df = pd.DataFrame([[1,2,3],[4,5,6]], columns=['a','b','c'])
>>> df.set_index('a', inplace=True)
>>> df
   b  c
a      
1  2  3
4  5  6
>>> df['index_x10'] = df.apply(lambda row: 10*row.name, axis=1)
>>> df
   b  c  index_x10
a                 
1  2  3         10
4  5  6         40

Using group by on two fields and count in SQL

You must group both columns, group and sub-group, then use the aggregate function COUNT().

SELECT
  group, subgroup, COUNT(*)
FROM
  groups
GROUP BY
  group, subgroup

how to change background image of button when clicked/focused?

You just need to set background and give previous.xml file in background of button in your layout file.

<Button
 android:id="@+id/button1"
 android:background="@drawable/previous"
 android:layout_width="200dp"
 android:layout_height="126dp"
 android:text="Hello" />

and done.Edit Following is previous.xml file in drawable directory

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

<item android:drawable="@drawable/onclick" android:state_selected="true"></item>
<item android:drawable="@drawable/onclick" android:state_pressed="true"></item>
<item android:drawable="@drawable/normal"></item>

Delete last char of string

In C# 8 ranges and indices were introduced, giving us a new more succinct solution:

strgroupids = strgroupids[..^1];

How can I detect window size with jQuery?

You could also use plain Javascript window.innerWidth to compare width.

But use jQuery's .resize() fired automatically for you:

$( window ).resize(function() {
  // your code...
}); 

http://api.jquery.com/resize/

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

It's been pointed out that the last d digits of a perfect square can only take on certain values. The last d digits (in base b) of a number n is the same as the remainder when n is divided by bd, ie. in C notation n % pow(b, d).

This can be generalized to any modulus m, ie. n % m can be used to rule out some percentage of numbers from being perfect squares. The modulus you are currently using is 64, which allows 12, ie. 19% of remainders, as possible squares. With a little coding I found the modulus 110880, which allows only 2016, ie. 1.8% of remainders as possible squares. So depending on the cost of a modulus operation (ie. division) and a table lookup versus a square root on your machine, using this modulus might be faster.

By the way if Java has a way to store a packed array of bits for the lookup table, don't use it. 110880 32-bit words is not much RAM these days and fetching a machine word is going to be faster than fetching a single bit.

How to create war files

I've always just selected Export from Eclipse. It builds the war file and includes all necessary files. Providing you created the project as a web project that's all you'll need to do. Eclipse makes it very simple to do.

Does a foreign key automatically create an index?

Strictly speaking, foreign keys have absolutely nothing to do with indexes, yes. But, as the speakers above me pointed out, it makes sense to create one to speed up the FK-lookups. In fact, in MySQL, if you don't specify an index in your FK declaration, the engine (InnoDB) creates it for you automatically.

Is there a Boolean data type in Microsoft SQL Server like there is in MySQL?

Use the Bit datatype. It has values 1 and 0 when dealing with it in native T-SQL

Can't update data-attribute value

Had similar problem and in the end I had to set both

obj.attr('data-myvar','myval')

and

obj.data('myvar','myval')

And after this

obj.data('myvar') == obj.attr('data-myvar')

Hope this helps.

OPENSSL file_get_contents(): Failed to enable crypto

Had same problem - it was somewhere in the ca certificate, so I used the ca bundle used for curl, and it worked. You can download the curl ca bundle here: https://curl.haxx.se/docs/caextract.html

For encryption and security issues see this helpful article:
https://www.venditan.com/labs/2014/06/26/ssl-and-php-streams-part-1-you-are-doing-it-wrongtm/432

Here is the example:

    $url = 'https://www.example.com/api/list';
    $cn_match = 'www.example.com';

    $data = array (     
        'apikey' => '[example api key here]',               
        'limit' => intval($limit),
        'offset' => intval($offset)
        );

    // use key 'http' even if you send the request to https://...
    $options = array(
        'http' => array(
            'header'  => "Content-type: application/x-www-form-urlencoded\r\n",
            'method'  => 'POST',                
            'content' => http_build_query($data)                
            )
        , 'ssl' => array(
            'verify_peer' => true,
            'cafile' => [path to file] . "cacert.pem",
            'ciphers' => 'HIGH:TLSv1.2:TLSv1.1:TLSv1.0:!SSLv3:!SSLv2',
            'CN_match' => $cn_match,
            'disable_compression' => true,
            )
        );

    $context  = stream_context_create($options);
    $response = file_get_contents($url, false, $context);

Hope that helps

C# using streams

To expand a little on other answers here, and help explain a lot of the example code you'll see dotted about, most of the time you don't read and write to a stream directly. Streams are a low-level means to transfer data.

You'll notice that the functions for reading and writing are all byte orientated, e.g. WriteByte(). There are no functions for dealing with integers, strings etc. This makes the stream very general-purpose, but less simple to work with if, say, you just want to transfer text.

However, .NET provides classes that convert between native types and the low-level stream interface, and transfers the data to or from the stream for you. Some notable such classes are:

StreamWriter // Badly named. Should be TextWriter.
StreamReader // Badly named. Should be TextReader.
BinaryWriter
BinaryReader

To use these, first you acquire your stream, then you create one of the above classes and associate it with the stream. E.g.

MemoryStream memoryStream = new MemoryStream();
StreamWriter myStreamWriter = new StreamWriter(memoryStream);

StreamReader and StreamWriter convert between native types and their string representations then transfer the strings to and from the stream as bytes. So

myStreamWriter.Write(123);

will write "123" (three characters '1', '2' then '3') to the stream. If you're dealing with text files (e.g. html), StreamReader and StreamWriter are the classes you would use.

Whereas

myBinaryWriter.Write(123);

will write four bytes representing the 32-bit integer value 123 (0x7B, 0x00, 0x00, 0x00). If you're dealing with binary files or network protocols BinaryReader and BinaryWriter are what you might use. (If you're exchanging data with networks or other systems, you need to be mindful of endianness, but that's another post.)

Firebug-like debugger for Google Chrome

Firebug Lite supports to inspect HTML elements, computed CSS style, and a lot more. Since it's pure JavaScript, it works in many different browsers. Just include the script in your source, or add the bookmarklet to your bookmark bar to include it on any page with a single click.

http://getfirebug.com/lite.html

How to "add existing frameworks" in Xcode 4?

Another easy way to do it so that it is referenced in the project folder you want, like "Frameworks", is to:

  1. Select "Show the Project navigator"
  2. Right-click on the project folder you wish to add the framework to.
  3. Select 'Add Files to "YourProjectName"'
  4. Browse to the framework - generally under /Developer/SDKs/MacOSXversion.sdk/System/Library/Frameworks
  5. Select the one you want.
  6. Select "Add"

It will appear in both the project navigator where you want it, as well as in the "Link Binary With Libraries" area of the "Build Phases" pane of your target.

Save ArrayList to SharedPreferences

Using this object --> TinyDB--Android-Shared-Preferences-Turbo its very simple.

TinyDB tinydb = new TinyDB(context);

to put

tinydb.putList("MyUsers", mUsersArray);

to get

tinydb.getList("MyUsers");

UPDATE

Some useful examples and troubleshooting might be found here: Android Shared Preference TinyDB putListObject frunction

How to get current instance name from T-SQL

Just to add some clarification to the registry queries. They only list the instances of the matching bitness (32 or 64) for the current instance.

The actual registry key for 32-bit SQL instances on a 64-bit OS is:

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Microsoft SQL Server

You can query this on a 64-bit instance to get all 32-bit instances as well. The 32-bit instance seems restricted to the Wow6432Node so cannot read the 64-bit registry tree.

Spring Boot REST service exception handling

For REST controllers, I would recommend to use Zalando Problem Spring Web.

https://github.com/zalando/problem-spring-web

If Spring Boot aims to embed some auto-configuration, this library does more for exception handling. You just need to add the dependency:

<dependency>
    <groupId>org.zalando</groupId>
    <artifactId>problem-spring-web</artifactId>
    <version>LATEST</version>
</dependency>

And then define one or more advice traits for your exceptions (or use those provided by default)

public interface NotAcceptableAdviceTrait extends AdviceTrait {

    @ExceptionHandler
    default ResponseEntity<Problem> handleMediaTypeNotAcceptable(
            final HttpMediaTypeNotAcceptableException exception,
            final NativeWebRequest request) {
        return Responses.create(Status.NOT_ACCEPTABLE, exception, request);
    }

}

Then you can defined the controller advice for exception handling as:

@ControllerAdvice
class ExceptionHandling implements MethodNotAllowedAdviceTrait, NotAcceptableAdviceTrait {

}

Comparing mongoose _id and strings

The three possible solutions suggested here have different use cases.

  1. Use .equals when comparing ObjectID on two mongoDocuments like this

    results.userId.equals(AnotherMongoDocument._id)

  2. Use .toString() when comparing a string representation of ObjectID to an ObjectID of a mongoDocument. like this

    results.userId === AnotherMongoDocument._id.toString()

MySQL Join Where Not Exists

There are three possible ways to do that.

  1. Option

    SELECT  lt.* FROM    table_left lt
    LEFT JOIN
        table_right rt
    ON      rt.value = lt.value
    WHERE   rt.value IS NULL
    
  2. Option

    SELECT  lt.* FROM    table_left lt
    WHERE   lt.value NOT IN
    (
    SELECT  value
    FROM    table_right rt
    )
    
  3. Option

    SELECT  lt.* FROM    table_left lt
    WHERE   NOT EXISTS
    (
    SELECT  NULL
    FROM    table_right rt
    WHERE   rt.value = lt.value
    )
    

Split string with JavaScript

Like this:

var myString = "19 51 2.108997";
var stringParts = myString.split(" ");
var html = "<span>" + stringParts[0] + " " + stringParts[1] + "</span> <span>" + stringParts[2] + "</span";

Spring Boot not serving static content

I think the previous answers address the topic very well. However, I'd add that in one case when you have Spring Security enabled in your application, you might have to specifically tell Spring to permit requests to other static resource directories like for example "/static/fonts".

In my case I had "/static/css", "/static/js", "/static/images" permited by default , but /static/fonts/** was blocked by my Spring Security implementation.

Below is an example of how I fixed this.

@Configuration
@EnableWebSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
.....
    @Override
    protected void configure(final HttpSecurity http) throws Exception {
        http.authorizeRequests().antMatchers("/", "/fonts/**").permitAll().
        //other security configuration rules
    }
.....
}

Create a File object in memory from a string in Java

Usually when a method accepts a file, there's another method nearby that accepts a stream. If this isn't the case, the API is badly coded. Otherwise, you can use temporary files, where permission is usually granted in many cases. If it's applet, you can request write permission.

An example:

try {
    // Create temp file.
    File temp = File.createTempFile("pattern", ".suffix");

    // Delete temp file when program exits.
    temp.deleteOnExit();

    // Write to temp file
    BufferedWriter out = new BufferedWriter(new FileWriter(temp));
    out.write("aString");
    out.close();
} catch (IOException e) {
}

Intermediate language used in scalac?

The nearest equivalents would be icode and bcode as used by scalac, view Miguel Garcia's site on the Scalac optimiser for more information, here: http://magarciaepfl.github.io/scala/

You might also consider Java bytecode itself to be your intermediate representation, given that bytecode is the ultimate output of scalac.

Or perhaps the true intermediate is something that the JIT produces before it finally outputs native instructions?

Ultimately though... There's no single place that you can point at an claim "there's the intermediate!". Scalac works in phases that successively change the abstract syntax tree, every single phase produces a new intermediate. The whole thing is like an onion, and it's very hard to try and pick out one layer as somehow being more significant than any other.

Adding gif image in an ImageView in android

Gif's can also be displayed in web view with couple of lines of code and without any 3rd party libraries. This way you can even load the gif from your SD card. No need to copy images to your Asset folder.

Take a web view.

<WebView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/imageWebView" />

Use can open a gif file from SD card not just from asset folder as shown in many examples.

    WebView webView = (WebView) findViewById(R.id.imageWebView);
    String  data    = "<body> <img src = \""+ filePath+"\"/></body>";
    // 'filePath' is the path of your .GIF file on SD card.
   webView.loadDataWithBaseURL("file:///android_asset/",data,"text/html","UTF-8",null);

Create file path from variables

You can also use an object-oriented path with pathlib (available as a standard library as of Python 3.4):

from pathlib import Path

start_path = Path('/my/root/directory')
final_path = start_path / 'in' / 'here'

Python - A keyboard command to stop infinite loop?

Ctrl+C is what you need. If it didn't work, hit it harder. :-) Of course, you can also just close the shell window.

Edit: You didn't mention the circumstances. As a last resort, you could write a batch file that contains taskkill /im python.exe, and put it on your desktop, Start menu, etc. and run it when you need to kill a runaway script. Of course, it will kill all Python processes, so be careful.

How can I parse a YAML file in Python

First install pyyaml using pip3.

Then import yaml module and load the file into a dictionary called 'my_dict':

import yaml
with open('filename.yaml') as f:
    my_dict = yaml.safe_load(f)

That's all you need. Now the entire yaml file is in 'my_dict' dictionary.

Find a class somewhere inside dozens of JAR files?

Grepj is a command line utility to search for classes within jar files. I am the author of the utility.

You can run the utility like grepj package.Class my1.jar my2.war my3.ear

Multiple jar, ear, war files can be provided. For advanced usage use find to provide a list of jars to be searched.

how to redirect to external url from c# controller

Use the Controller's Redirect() method.

public ActionResult YourAction()
{
    // ...
    return Redirect("http://www.example.com");
}

Update

You can't directly perform a server side redirect from an ajax response. You could, however, return a JsonResult with the new url and perform the redirect with javascript.

public ActionResult YourAction()
{
    // ...
    return Json(new {url = "http://www.example.com"});
}

$.post("@Url.Action("YourAction")", function(data) {
    window.location = data.url;
});

Disable/turn off inherited CSS3 transitions

Additionally there is a possibility to set a list of properties that will get transitioned by setting the property transition-property: width, height;, more details here

How to copy selected lines to clipboard in vim

I have added the following line to my .vimrc

vnoremap <F5> "+y<CR>

This allows you to copy the selected text to the clipboard by pressing F5. You must be in visual mode for this to work.

Connecting to TCP Socket from browser using javascript

See jsocket. Haven't used it myself. Been more than 3 years since last update (as of 26/6/2014).

* Uses flash :(

From the documentation:

<script type='text/javascript'>
    // Host we are connecting to
    var host = 'localhost'; 
    // Port we are connecting on
    var port = 3000;

    var socket = new jSocket();

    // When the socket is added the to document 
    socket.onReady = function(){
            socket.connect(host, port);             
    }

    // Connection attempt finished
    socket.onConnect = function(success, msg){
            if(success){
                    // Send something to the socket
                    socket.write('Hello world');            
            }else{
                    alert('Connection to the server could not be estabilished: ' + msg);            
            }       
    }
    socket.onData = function(data){
            alert('Received from socket: '+data);   
    }

    // Setup our socket in the div with the id="socket"
    socket.setup('mySocket');       
</script>

Accessing all items in the JToken

In addition to the accepted answer I would like to give an answer that shows how to iterate directly over the Newtonsoft collections. It uses less code and I'm guessing its more efficient as it doesn't involve converting the collections.

using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
//Parse the data
JObject my_obj = JsonConvert.DeserializeObject<JObject>(your_json);

foreach (KeyValuePair<string, JToken> sub_obj in (JObject)my_obj["ADDRESS_MAP"])
{
    Console.WriteLine(sub_obj.Key);
}

I started doing this myself because JsonConvert automatically deserializes nested objects as JToken (which are JObject, JValue, or JArray underneath I think).

I think the parsing works according to the following principles:

  • Every object is abstracted as a JToken

  • Cast to JObject where you expect a Dictionary

  • Cast to JValue if the JToken represents a terminal node and is a value

  • Cast to JArray if its an array

  • JValue.Value gives you the .NET type you need

How do I pass multiple ints into a vector at once?

You can do it with initializer list:

std::vector<unsigned int> array;

// First argument is an iterator to the element BEFORE which you will insert:
// In this case, you will insert before the end() iterator, which means appending value
// at the end of the vector.
array.insert(array.end(), { 1, 2, 3, 4, 5, 6 });

JQuery window scrolling event?

Try this: http://jsbin.com/axaler/3/edit

$(function(){
  $(window).scroll(function(){
    var aTop = $('.ad').height();
    if($(this).scrollTop()>=aTop){
        alert('header just passed.');
        // instead of alert you can use to show your ad
        // something like $('#footAd').slideup();
    }
  });
});

Where to put a textfile I want to use in eclipse?

Just create a folder Files under src and put your file there. This will look like src/Files/myFile.txt

Note: In your code you need to specify like this Files/myFile.txt e.g.

getResource("Files/myFile.txt");

So when you build your project and run the .jar file this should be able to work.

Uncaught TypeError: Cannot use 'in' operator to search for 'length' in

The only solution that worked for me and $.each was definitely causing the error. so i used for loop and it's not throwing error anymore.

Example code

     $.ajax({
            type: 'GET',
            url: 'https://example.com/api',
            data: { get_param: 'value' },
            success: function (data) {
                for (var i = 0; i < data.length; ++i) {
                    console.log(data[i].NameGerman);
                }
            }
        });

UIImageView - How to get the file name of the image assigned?

The code is work in swift3 - write code inside didFinishPickingMediaWithInfo delegate method:

if let referenceUrl = info[UIImagePickerControllerReferenceURL] as? NSURL {
  ALAssetsLibrary().asset(for: referenceUrl as URL!, resultBlock: { asset in

  let fileName = asset?.defaultRepresentation().filename()
  print(fileName!)

  //do whatever with your file name            
  }, failureBlock: nil)
}

How to add chmod permissions to file in Git?

According to official documentation, you can set or remove the "executable" flag on any tracked file using update-index sub-command.

To set the flag, use following command:

git update-index --chmod=+x path/to/file

To remove it, use:

git update-index --chmod=-x path/to/file

Under the hood

While this looks like the regular unix files permission system, actually it is not. Git maintains a special "mode" for each file in its internal storage:

  • 100644 for regular files
  • 100755 for executable ones

You can visualize it using ls-file subcommand, with --stage option:

$ git ls-files --stage
100644 aee89ef43dc3b0ec6a7c6228f742377692b50484 0       .gitignore
100755 0ac339497485f7cc80d988561807906b2fd56172 0       my_executable_script.sh

By default, when you add a file to a repository, Git will try to honor its filesystem attributes and set the correct filemode accordingly. You can disable this by setting core.fileMode option to false:

git config core.fileMode false

Troubleshooting

If at some point the Git filemode is not set but the file has correct filesystem flag, try to remove mode and set it again:

git update-index --chmod=-x path/to/file
git update-index --chmod=+x path/to/file

Bonus

Starting with Git 2.9, you can stage a file AND set the flag in one command:

git add --chmod=+x path/to/file

How do I disable a Pylint warning?

Starting from Pylint v. 0.25.3, you can use the symbolic names for disabling warnings instead of having to remember all those code numbers. E.g.:

# pylint: disable=locally-disabled, multiple-statements, fixme, line-too-long

This style is more instructive than cryptic error codes, and also more practical since newer versions of Pylint only output the symbolic name, not the error code.

The correspondence between symbolic names and codes can be found here.

A disable comment can be inserted on its own line, applying the disable to everything that comes after in the same block. Alternatively, it can be inserted at the end of the line for which it is meant to apply.

If Pylint outputs "Locally disabling" messages, you can get rid of them by including the disable locally-disabled first as in the example above.

installing vmware tools: location of GCC binary?

Install prerequisites VMware Tools for LinuxOS:

If you have RHEL/CentOS:

yum install perl gcc make kernel-headers kernel-devel -y

If you have Ubuntu/Debian:

sudo apt-get -y install linux-headers-server build-essential
  • build-essential, also install: dpkg-dev, g++, gcc, lib6-dev, libc-dev, make

Extracted from: http://www.sysadmit.com/2016/01/vmware-tools-linux-instalar-requisitos.html

How can I reverse a list in Python?

You can make use of the reversed function for this as:

>>> array=[0,10,20,40]
>>> for i in reversed(array):
...     print(i)

Note that reversed(...) does not return a list. You can get a reversed list using list(reversed(array)).

iloc giving 'IndexError: single positional indexer is out-of-bounds'

This happens when you index a row/column with a number that is larger than the dimensions of your dataframe. For instance, getting the eleventh column when you have only three.

import pandas as pd

df = pd.DataFrame({'Name': ['Mark', 'Laura', 'Adam', 'Roger', 'Anna'],
                   'City': ['Lisbon', 'Montreal', 'Lisbon', 'Berlin', 'Glasgow'],
                   'Car': ['Tesla', 'Audi', 'Porsche', 'Ford', 'Honda']})

You have 5 rows and three columns:

    Name      City      Car
0   Mark    Lisbon    Tesla
1  Laura  Montreal     Audi
2   Adam    Lisbon  Porsche
3  Roger    Berlin     Ford
4   Anna   Glasgow    Honda

Let's try to index the eleventh column (it doesn't exist):

df.iloc[:, 10] # there is obviously no 11th column

IndexError: single positional indexer is out-of-bounds

If you are a beginner with Python, remember that df.iloc[:, 10] would refer to the eleventh column.

Launch a shell command with in a python script, wait for the termination and return to the script

You can use subprocess.Popen. There's a few ways to do it:

import subprocess
cmd = ['/run/myscript', '--arg', 'value']
p = subprocess.Popen(cmd, stdout=subprocess.PIPE)
for line in p.stdout:
    print line
p.wait()
print p.returncode

Or, if you don't care what the external program actually does:

cmd = ['/run/myscript', '--arg', 'value']
subprocess.Popen(cmd).wait()

react-router getting this.props.location in child components

(Update) V5.1 & Hooks (Requires React >= 16.8)

You can use useHistory, useLocation and useRouteMatch in your component to get match, history and location .

const Child = () => {
  const location = useLocation();
  const history = useHistory();
  const match = useRouteMatch("write-the-url-you-want-to-match-here");

  return (
    <div>{location.pathname}</div>
  )
}

export default Child

(Update) V4 & V5

You can use withRouter HOC in order to inject match, history and location in your component props.

class Child extends React.Component {
  static propTypes = {
    match: PropTypes.object.isRequired,
    location: PropTypes.object.isRequired,
    history: PropTypes.object.isRequired
  }

  render() {
    const { match, location, history } = this.props

    return (
      <div>{location.pathname}</div>
    )
  }
}

export default withRouter(Child)

(Update) V3

You can use withRouter HOC in order to inject router, params, location, routes in your component props.

class Child extends React.Component {

  render() {
    const { router, params, location, routes } = this.props

    return (
      <div>{location.pathname}</div>
    )
  }
}

export default withRouter(Child)

Original answer

If you don't want to use the props, you can use the context as described in React Router documentation

First, you have to set up your childContextTypes and getChildContext

class App extends React.Component{

  getChildContext() {
    return {
      location: this.props.location
    }
  }

  render() {
    return <Child/>;
  }
}

App.childContextTypes = {
    location: React.PropTypes.object
}

Then, you will be able to access to the location object in your child components using the context like this

class Child extends React.Component{

   render() {
     return (
       <div>{this.context.location.pathname}</div>
     )
   }

}

Child.contextTypes = {
    location: React.PropTypes.object
 }

What is the difference between <html lang="en"> and <html lang="en-US">?

Well, the first question is easy. There are many ens (Englishes) but (mostly) only one US English. One would guess there are en-CN, en-GB, en-AU. Guess there might even be Austrian English but that's more yes you can than yes there is.

POSTing JsonObject With HttpClient From Web API

The easiest way is to use a StringContent, with the JSON representation of your JSON object.

httpClient.Post(
    "",
    new StringContent(
        myObject.ToString(),
        Encoding.UTF8,
        "application/json"));

std::queue iteration

while Alexey Kukanov's answer may be more efficient, you can also iterate through a queue in a very natural manner, by popping each element from the front of the queue, then pushing it to the back:

#include <iostream>
#include <queue>

using namespace std;

int main() {
    //populate queue
    queue<int> q;
    for (int i = 0; i < 10; ++i) q.push(i);

    // iterate through queue
    for (size_t i = 0; i < q.size(); ++i) {
        int elem = std::move(q.front());
        q.pop();
        elem *= elem;
        q.push(std::move(elem));
    }

    //print queue
    while (!q.empty()) {
        cout << q.front() << ' ';
        q.pop();
    }
}

output:

0 1 4 9 16 25 36 49 64 81 

Placing Unicode character in CSS content value

Why don't you just save/serve the CSS file as UTF-8?

nav a:hover:after {
    content: "?";
}

If that's not good enough, and you want to keep it all-ASCII:

nav a:hover:after {
    content: "\2193";
}

The general format for a Unicode character inside a string is \000000 to \FFFFFF – a backslash followed by six hexadecimal digits. You can leave out leading 0 digits when the Unicode character is the last character in the string or when you add a space after the Unicode character. See the spec below for full details.


Relevant part of the CSS2 spec:

Third, backslash escapes allow authors to refer to characters they cannot easily put in a document. In this case, the backslash is followed by at most six hexadecimal digits (0..9A..F), which stand for the ISO 10646 ([ISO10646]) character with that number, which must not be zero. (It is undefined in CSS 2.1 what happens if a style sheet does contain a character with Unicode codepoint zero.) If a character in the range [0-9a-fA-F] follows the hexadecimal number, the end of the number needs to be made clear. There are two ways to do that:

  1. with a space (or other white space character): "\26 B" ("&B"). In this case, user agents should treat a "CR/LF" pair (U+000D/U+000A) as a single white space character.
  2. by providing exactly 6 hexadecimal digits: "\000026B" ("&B")

In fact, these two methods may be combined. Only one white space character is ignored after a hexadecimal escape. Note that this means that a "real" space after the escape sequence must be doubled.

If the number is outside the range allowed by Unicode (e.g., "\110000" is above the maximum 10FFFF allowed in current Unicode), the UA may replace the escape with the "replacement character" (U+FFFD). If the character is to be displayed, the UA should show a visible symbol, such as a "missing character" glyph (cf. 15.2, point 5).

  • Note: Backslash escapes are always considered to be part of an identifier or a string (i.e., "\7B" is not punctuation, even though "{" is, and "\32" is allowed at the start of a class name, even though "2" is not).
    The identifier "te\st" is exactly the same identifier as "test".

Comprehensive list: Unicode Character 'DOWNWARDS ARROW' (U+2193).

How do you receive a url parameter with a spring controller mapping

You should be using @RequestParam instead of @ModelAttribute, e.g.

@RequestMapping("/{someID}")
public @ResponseBody int getAttr(@PathVariable(value="someID") String id, 
                                 @RequestParam String someAttr) {
}

You can even omit @RequestParam altogether if you choose, and Spring will assume that's what it is:

@RequestMapping("/{someID}")
public @ResponseBody int getAttr(@PathVariable(value="someID") String id, 
                                 String someAttr) {
}

How do I mock an open used in a with statement (using the Mock framework in Python)?

To use mock_open for a simple file read() (the original mock_open snippet already given on this page is geared more for write):

my_text = "some text to return when read() is called on the file object"
mocked_open_function = mock.mock_open(read_data=my_text)

with mock.patch("__builtin__.open", mocked_open_function):
    with open("any_string") as f:
        print f.read()

Note as per docs for mock_open, this is specifically for read(), so won't work with common patterns like for line in f, for example.

Uses python 2.6.6 / mock 1.0.1

Best way to select random rows PostgreSQL

postgresql order by random(), select rows in random order:

select your_columns from your_table ORDER BY random()

postgresql order by random() with a distinct:

select * from 
  (select distinct your_columns from your_table) table_alias
ORDER BY random()

postgresql order by random limit one row:

select your_columns from your_table ORDER BY random() limit 1

remove script tag from HTML content

This is a simplified variant of Dejan Marjanovic's answer:

function removeTags($html, $tag) {
    $dom = new DOMDocument();
    $dom->loadHTML($html);
    foreach (iterator_to_array($dom->getElementsByTagName($tag)) as $item) {
        $item->parentNode->removeChild($item);
    }
    return $dom->saveHTML();
}

Can be used to remove any kind of tag, including <script>:

$scriptlessHtml = removeTags($html, 'script');

JQuery post JSON object to a server

To send json to the server, you first have to create json

function sendData() {
    $.ajax({
        url: '/helloworld',
        type: 'POST',
        contentType: 'application/json',
        data: JSON.stringify({
            name:"Bob",
            ...
        }),
        dataType: 'json'
    });
}

This is how you would structure the ajax request to send the json as a post var.

function sendData() {
    $.ajax({
        url: '/helloworld',
        type: 'POST',
        data: { json: JSON.stringify({
            name:"Bob",
            ...
        })},
        dataType: 'json'
    });
}

The json will now be in the json post var.

Emulate Samsung Galaxy Tab

If you are developing on Netbeans, you will not get the Third-Party add-ons. You can download the Skins directly from Samsung here: http://developer.samsung.com/android/tools-sdks

After download, unzip to ...\Android\android-sdk\add-ons[name of device]

Restart the Android SDK Manager, and the new device should be there under Extras.

It would be better to add the download site directly to the SDK...if anyone knows it, please post it.

Scott

SQL SERVER: Check if variable is null and then assign statement for Where Clause

is null is the syntax I use for such things, when COALESCE is of no help.

Try:

if (@zipCode is null)
  begin
    ([Portal].[dbo].[Address].Position.Filter(@radiusBuff) = 1)   
  end
else 
  begin
    ([Portal].[dbo].[Address].PostalCode=@zipCode )
  end  

EXCEL VBA Check if entry is empty or not 'space'

You can use the following code to check if a textbox object is null/empty

'Checks if the box is null

If Me.TextBox & "" <> "" Then

        'Enter Code here...

End if

jQuery Ajax calls and the Html.AntiForgeryToken()

Here is the easiest way I've seen. Note: Make sure you have "@Html.AntiForgeryToken()" in your View

  $("a.markAsDone").click(function (event) {
        event.preventDefault();
        var sToken = document.getElementsByName("__RequestVerificationToken")[0].value;
        $.ajax({
            url: $(this).attr("rel"),
            type: "POST",
            contentType: "application/x-www-form-urlencoded",
            data: { '__RequestVerificationToken': sToken, 'id': parseInt($(this).attr("title")) }
        })
        .done(function (data) {
            //Process MVC Data here
        })
        .fail(function (jqXHR, textStatus, errorThrown) {
            //Process Failure here
        });
    });

How to list all files in a directory and its subdirectories in hadoop hdfs

Thanks Radu Adrian Moldovan for the suggestion.

Here is an implementation using queue:

private static List<String> listAllFilePath(Path hdfsFilePath, FileSystem fs)
throws FileNotFoundException, IOException {
  List<String> filePathList = new ArrayList<String>();
  Queue<Path> fileQueue = new LinkedList<Path>();
  fileQueue.add(hdfsFilePath);
  while (!fileQueue.isEmpty()) {
    Path filePath = fileQueue.remove();
    if (fs.isFile(filePath)) {
      filePathList.add(filePath.toString());
    } else {
      FileStatus[] fileStatus = fs.listStatus(filePath);
      for (FileStatus fileStat : fileStatus) {
        fileQueue.add(fileStat.getPath());
      }
    }
  }
  return filePathList;
}

How to make a DIV not wrap?

If I don't want to define a minimal width because I don't know the amount of elements the only thing that worked to me was:

display: inline-block;
white-space: nowrap;

But only in Chrome and Safari :/

javascript: detect scroll end

OK Here is a Good And Proper Solution

You have a Div call with an id="myDiv"

so the function goes.

function GetScrollerEndPoint()
{
   var scrollHeight = $("#myDiv").prop('scrollHeight');
   var divHeight = $("#myDiv").height();
   var scrollerEndPoint = scrollHeight - divHeight;

   var divScrollerTop =  $("#myDiv").scrollTop();
   if(divScrollerTop === scrollerEndPoint)
   {
       //Your Code 
       //The Div scroller has reached the bottom
   }
}

How to fix "unable to write 'random state' " in openssl

The quickest solution is: set environment variable RANDFILE to path where the 'random state' file can be written (of course check the file access permissions), eg. in your command prompt:

set RANDFILE=C:\MyDir\.rnd
openssl genrsa -out my-prvkey.pem 1024

More explanations: OpenSSL on Windows tries to save the 'random state' file in the following order:

  1. Path taken from RANDFILE environment variable
  2. If HOME environment variable is set then : ${HOME}\.rnd
  3. C:\.rnd

I'm pretty sure that in your case it ends up trying to save it in C:\.rnd (and it fails because lack of sufficient access rights). Unfortunately OpenSSL does not print the path that is actually tries to use in any error messages.

Printing reverse of any String without using any predefined function?

How about a simple traverse from the end of the string to the beg:

void printRev(String str) {
 for(int i=str.length()-1;i>=0;i--)
  System.out.print(str.charAt(i));
}

Measuring execution time of a function in C++

If you want to safe time and lines of code you can make measuring the function execution time a one line macro:

a) Implement a time measuring class as already suggested above ( here is my implementation for android):

class MeasureExecutionTime{
private:
    const std::chrono::steady_clock::time_point begin;
    const std::string caller;
public:
    MeasureExecutionTime(const std::string& caller):caller(caller),begin(std::chrono::steady_clock::now()){}
    ~MeasureExecutionTime(){
        const auto duration=std::chrono::steady_clock::now()-begin;
        LOGD("ExecutionTime")<<"For "<<caller<<" is "<<std::chrono::duration_cast<std::chrono::milliseconds>(duration).count()<<"ms";
    }
};

b) Add a convenient macro that uses the current function name as TAG (using a macro here is important, else __FUNCTION__ will evaluate to MeasureExecutionTime instead of the function you wanto to measure

#ifndef MEASURE_FUNCTION_EXECUTION_TIME
#define MEASURE_FUNCTION_EXECUTION_TIME const MeasureExecutionTime measureExecutionTime(__FUNCTION__);
#endif

c) Write your macro at the begin of the function you want to measure. Example:

 void DecodeMJPEGtoANativeWindowBuffer(uvc_frame_t* frame_mjpeg,const ANativeWindow_Buffer& nativeWindowBuffer){
        MEASURE_FUNCTION_EXECUTION_TIME
        // Do some time-critical stuff 
}

Which will result int the following output:

ExecutionTime: For DecodeMJPEGtoANativeWindowBuffer is 54ms

Note that this (as all other suggested solutions) will measure the time between when your function was called and when it returned, not neccesarily the time your CPU was executing the function. However, if you don't give the scheduler any change to suspend your running code by calling sleep() or similar there is no difference between.

How to close a window using jQuery

For IE: window.close(); and self.close(); should work fine.

If you want just open the IE browser and type

javascript:self.close() and hit enter, it should ask you for a prompt.

Note: this method doesn't work for Chrome or Firefox.

How to remove last n characters from a string in Bash?

You could use sed,

sed 's/.\{4\}$//' <<< "$var"

EXample:

$ var="some string.rtf"
$ var1=$(sed 's/.\{4\}$//' <<< "$var")
$ echo $var1
some string

Can comments be used in JSON?

*.json files are generally used as configuration files or static data, thus the need of comments ? some editors like NetBeans accept comments in *.json.

The problem is parsing content to an object. The solution is to always apply a cleaning function (server or client).

###PHP

 $rgx_arr = ["/\/\/[^\n]*/sim", "/\/\*.*?\*\//sim", "/[\n\r\t]/sim"];
 $valid_json_str = \preg_replace($rgx_arr, '', file_get_contents(path . 'a_file.json'));

###JavaScript

valid_json_str = json_str.replace(/\/\/[^\n]*/gim,'').replace(/\/\*.*?\*\//gim,'')

CSS Box Shadow Bottom Only

Do this:

box-shadow: 0 4px 2px -2px gray;

It's actually much simpler, whatever you set the blur to (3rd value), set the spread (4th value) to the negative of it.

Sort a list of numerical strings in ascending order

in python sorted works like you want with integers:

>>> sorted([10,3,2])
[2, 3, 10]

it looks like you have a problem because you are using strings:

>>> sorted(['10','3','2'])
['10', '2', '3']

(because string ordering starts with the first character, and "1" comes before "2", no matter what characters follow) which can be fixed with key=int

>>> sorted(['10','3','2'], key=int)
['2', '3', '10']

which converts the values to integers during the sort (it is called as a function - int('10') returns the integer 10)

and as suggested in the comments, you can also sort the list itself, rather than generating a new one:

>>> l = ['10','3','2']
>>> l.sort(key=int)
>>> l
['2', '3', '10']

but i would look into why you have strings at all. you should be able to save and retrieve integers. it looks like you are saving a string when you should be saving an int? (sqlite is unusual amongst databases, in that it kind-of stores data in the same type as it is given, even if the table column type is different).

and once you start saving integers, you can also get the list back sorted from sqlite by adding order by ... to the sql command:

select temperature from temperatures order by temperature;

How to use JNDI DataSource provided by Tomcat in Spring?

According to Apache Tomcat 7 JNDI Datasource HOW-TO page there must be a resource configuration in web.xml:

<resource-ref>
  <description>DB Connection</description>
  <res-ref-name>jdbc/TestDB</res-ref-name>
  <res-type>javax.sql.DataSource</res-type>
  <res-auth>Container</res-auth>

That works for me

Ship an application with a database

Currently there is no way to precreate an SQLite database to ship with your apk. The best you can do is save the appropriate SQL as a resource and run them from your application. Yes, this leads to duplication of data (same information exists as a resrouce and as a database) but there is no other way right now. The only mitigating factor is the apk file is compressed. My experience is 908KB compresses to less than 268KB.

The thread below has the best discussion/solution I have found with good sample code.

http://groups.google.com/group/android-developers/msg/9f455ae93a1cf152

I stored my CREATE statement as a string resource to be read with Context.getString() and ran it with SQLiteDatabse.execSQL().

I stored the data for my inserts in res/raw/inserts.sql (I created the sql file, 7000+ lines). Using the technique from the link above I entered a loop, read the file line by line and concactenated the data onto "INSERT INTO tbl VALUE " and did another SQLiteDatabase.execSQL(). No sense in saving 7000 "INSERT INTO tbl VALUE "s when they can just be concactenated on.

It takes about twenty seconds on the emulator, I do not know how long this would take on a real phone, but it only happens once, when the user first starts the application.

How to upload multiple files using PHP, jQuery and AJAX

Finally I have found the solution by using the following code:

$('body').on('click', '#upload', function(e){
        e.preventDefault();
        var formData = new FormData($(this).parents('form')[0]);

        $.ajax({
            url: 'upload.php',
            type: 'POST',
            xhr: function() {
                var myXhr = $.ajaxSettings.xhr();
                return myXhr;
            },
            success: function (data) {
                alert("Data Uploaded: "+data);
            },
            data: formData,
            cache: false,
            contentType: false,
            processData: false
        });
        return false;
});

How do you add a scroll bar to a div?

Css class to have a nice Div with scroll

.DivToScroll{   
    background-color: #F5F5F5;
    border: 1px solid #DDDDDD;
    border-radius: 4px 0 4px 0;
    color: #3B3C3E;
    font-size: 12px;
    font-weight: bold;
    left: -1px;
    padding: 10px 7px 5px;
}

.DivWithScroll{
    height:120px;
    overflow:scroll;
    overflow-x:hidden;
}

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

I ran into the same situation where commands such as git diff origin or git diff origin master produced the error reported in the question, namely Fatal: ambiguous argument...

To resolve the situation, I ran the command

git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/master

to set refs/remotes/origin/HEAD to point to the origin/master branch.

Before running this command, the output of git branch -a was:

* master
  remotes/origin/master

After running the command, the error no longer happened and the output of git branch -a was:

* master
  remotes/origin/HEAD -> origin/master
  remotes/origin/master

(Other answers have already identified that the source of the error is HEAD not being set for origin. But I thought it helpful to provide a command which may be used to fix the error in question, although it may be obvious to some users.)


Additional information:

For anybody inclined to experiment and go back and forth between setting and unsetting refs/remotes/origin/HEAD, here are some examples.

To unset:
git remote set-head origin --delete

To set:
(additional ways, besides the way shown at the start of this answer)
git remote set-head origin master to set origin/head explicitly
OR
git remote set-head origin --auto to query the remote and automatically set origin/HEAD to the remote's current branch.

References:

  • This SO Answer
  • This SO Comment and its associated answer
  • git remote --help see set-head description
  • git symbolic-ref --help

PHP - SSL certificate error: unable to get local issuer certificate

Thanks @Mladen Janjetovic,

Your suggestion worked for me in mac with ampps installed.

Copied: http://curl.haxx.se/ca/cacert.pem

To: /Applications/AMPPS/extra/etc/openssl/certs/cacert.pem

And updated php.ini with that path and restarted Apache:

[curl]
; A default value for the CURLOPT_CAINFO option. This is required to be an
; absolute path.
curl.cainfo="/Applications/AMPPS/extra/etc/openssl/certs/cacert.pem"
openssl.cafile="/Applications/AMPPS/extra/etc/openssl/certs/cacert.pem"

And applied same setting in windows AMPPS installation and it worked perfectly in it too.

[curl]
; A default value for the CURLOPT_CAINFO option. This is required to be an
; absolute path.
curl.cainfo="C:/Ampps/php/extras/ssl/cacert.pem"
openssl.cafile="C:/Ampps/php/extras/ssl/cacert.pem"

: Same for wamp.

[curl]
; A default value for the CURLOPT_CAINFO option. This is required to be an
; absolute path.
curl.cainfo="C:/wamp/bin/php/php5.6.16/extras/ssl/cacert.pem"
openssl.cafile="C:/wamp/bin/php/php5.6.16/extras/ssl/cacert.pem"

If you are looking for generating new SSL certificate using SAN for localhost, steps on this post worked for me on Centos 7 / Vagrant / Chrome Browser.

Enabling refreshing for specific html elements only

try to empty your innerHtml everytime. just like this:

_x000D_
_x000D_
Element.innerHtml="";
_x000D_
_x000D_
_x000D_

How to run Rake tasks from within Rake tasks?

If you need the task to behave as a method, how about using an actual method?

task :build => [:some_other_tasks] do
  build
end

task :build_all do
  [:debug, :release].each { |t| build t }
end

def build(type = :debug)
  # ...
end

If you'd rather stick to rake's idioms, here are your possibilities, compiled from past answers:

  • This always executes the task, but it doesn't execute its dependencies:

    Rake::Task["build"].execute
    
  • This one executes the dependencies, but it only executes the task if it has not already been invoked:

    Rake::Task["build"].invoke
    
  • This first resets the task's already_invoked state, allowing the task to then be executed again, dependencies and all:

    Rake::Task["build"].reenable
    Rake::Task["build"].invoke
    
  • Note that dependencies already invoked are not automatically re-executed unless they are re-enabled. In Rake >= 10.3.2, you can use the following to re-enable those as well:

    Rake::Task["build"].all_prerequisite_tasks.each(&:reenable)
    

How to set DOM element as the first child?

You can implement it directly i all your window html elements.
Like this :

HTMLElement.prototype.appendFirst = function(childNode) {
    if (this.firstChild) {
        this.insertBefore(childNode, this.firstChild);
    }
    else {
        this.appendChild(childNode);
    }
};