Programs & Examples On #Smart pointers

An abstract data type that simulates a pointer while providing additional features, such as automatic garbage collection or bounds checking

What is a smart pointer and when should I use one?

http://en.wikipedia.org/wiki/Smart_pointer

In computer science, a smart pointer is an abstract data type that simulates a pointer while providing additional features, such as automatic garbage collection or bounds checking. These additional features are intended to reduce bugs caused by the misuse of pointers while retaining efficiency. Smart pointers typically keep track of the objects that point to them for the purpose of memory management. The misuse of pointers is a major source of bugs: the constant allocation, deallocation and referencing that must be performed by a program written using pointers makes it very likely that some memory leaks will occur. Smart pointers try to prevent memory leaks by making the resource deallocation automatic: when the pointer to an object (or the last in a series of pointers) is destroyed, for example because it goes out of scope, the pointed object is destroyed too.

Why can I not push_back a unique_ptr into a vector?

std::unique_ptr has no copy constructor. You create an instance and then ask the std::vector to copy that instance during initialisation.

error: deleted function 'std::unique_ptr<_Tp, _Tp_Deleter>::uniqu
e_ptr(const std::unique_ptr<_Tp, _Tp_Deleter>&) [with _Tp = int, _Tp_D
eleter = std::default_delete<int>, std::unique_ptr<_Tp, _Tp_Deleter> =
 std::unique_ptr<int>]'

The class satisfies the requirements of MoveConstructible and MoveAssignable, but not the requirements of either CopyConstructible or CopyAssignable.

The following works with the new emplace calls.

std::vector< std::unique_ptr< int > > vec;
vec.emplace_back( new int( 1984 ) );

See using unique_ptr with standard library containers for further reading.

Example to use shared_ptr?

Through Boost you can do it >

std::vector<boost::any> vecobj;
    boost::shared_ptr<string> sharedString1(new string("abcdxyz!"));    
    boost::shared_ptr<int> sharedint1(new int(10));
    vecobj.push_back(sharedString1);
    vecobj.push_back(sharedint1);

> for inserting different object type in your vector container. while for accessing you have to use any_cast, which works like dynamic_cast, hopes it will work for your need.

Is there any use for unique_ptr with array?

There are tradeoffs, and you pick the solution which matches what you want. Off the top of my head:

Initial size

  • vector and unique_ptr<T[]> allow the size to be specified at run-time
  • array only allows the size to be specified at compile time

Resizing

  • array and unique_ptr<T[]> do not allow resizing
  • vector does

Storage

  • vector and unique_ptr<T[]> store the data outside the object (typically on the heap)
  • array stores the data directly in the object

Copying

  • array and vector allow copying
  • unique_ptr<T[]> does not allow copying

Swap/move

  • vector and unique_ptr<T[]> have O(1) time swap and move operations
  • array has O(n) time swap and move operations, where n is the number of elements in the array

Pointer/reference/iterator invalidation

  • array ensures pointers, references and iterators will never be invalidated while the object is live, even on swap()
  • unique_ptr<T[]> has no iterators; pointers and references are only invalidated by swap() while the object is live. (After swapping, pointers point into to the array that you swapped with, so they're still "valid" in that sense.)
  • vector may invalidate pointers, references and iterators on any reallocation (and provides some guarantees that reallocation can only happen on certain operations).

Compatibility with concepts and algorithms

  • array and vector are both Containers
  • unique_ptr<T[]> is not a Container

I do have to admit, this looks like an opportunity for some refactoring with policy-based design.

Where is shared_ptr?

If your'e looking bor boost's shared_ptr, you could have easily found the answer by googling shared_ptr, following the links to the docs, and pulling up a complete working example such as this.

In any case, here is a minimalistic complete working example for you which I just hacked up:

#include <boost/shared_ptr.hpp>

struct MyGizmo
{
    int n_;
};

int main()
{
    boost::shared_ptr<MyGizmo> p(new MyGizmo);
    return 0;
}

In order for the #include to find the header, the libraries obviously need to be in the search path. In MSVC, you set this in Project Settings>Configuration Properties>C/C++>Additional Include Directories. In my case, this is set to C:\Program Files (x86)\boost\boost_1_42

Download File Using Javascript/jQuery

To improve Imagine Breaker 's answer, this is supported on FF & IE :

var evt = document.createEvent("MouseEvents");
evt.initMouseEvent("click", true, true, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);

function downloadURI(uri, name) {
    var link = document.createElement("a");
    link.download = name;
    link.href = uri;
    link.dispatchEvent(evt);
}

In other words, just use a dispatchEvent function instead of click();

Spring get current ApplicationContext

If you're implementing a class that's not instantiated by Spring, like a JsonDeserializer you can use:

WebApplicationContext context = ContextLoader.getCurrentWebApplicationContext();
MyClass myBean = context.getBean(MyClass.class);

How to determine whether an object has a given property in JavaScript

You can trim that up a bit like this:

if ( x.y !== undefined ) ...

How to create a multi line body in C# System.Net.Mail.MailMessage

Try using a StringBuilder object and use the appendline method. That might work.

Parse a URI String into Name-Value Collection

If you're using Java 8 and you're willing to write a few reusable methods, you can do it in one line.

private Map<String, List<String>> parse(final String query) {
    return Arrays.asList(query.split("&")).stream().map(p -> p.split("=")).collect(Collectors.toMap(s -> decode(index(s, 0)), s -> Arrays.asList(decode(index(s, 1))), this::mergeLists));
}

private <T> List<T> mergeLists(final List<T> l1, final List<T> l2) {
    List<T> list = new ArrayList<>();
    list.addAll(l1);
    list.addAll(l2);
    return list;
}

private static <T> T index(final T[] array, final int index) {
    return index >= array.length ? null : array[index];
}

private static String decode(final String encoded) {
    try {
        return encoded == null ? null : URLDecoder.decode(encoded, "UTF-8");
    } catch(final UnsupportedEncodingException e) {
        throw new RuntimeException("Impossible: UTF-8 is a required encoding", e);
    }
}

But that's a pretty brutal line.

Change working directory in my current shell context when running Node script

There is no built-in method for Node to change the CWD of the underlying shell running the Node process.

You can change the current working directory of the Node process through the command process.chdir().

var process = require('process');
process.chdir('../');

When the Node process exists, you will find yourself back in the CWD you started the process in.

Wait until an HTML5 video loads

call function on load:

<video onload="doWhatYouNeedTo()" src="demo.mp4" id="video">

get video duration

var video = document.getElementById("video");
var duration = video.duration;

RegEx for matching "A-Z, a-z, 0-9, _" and "."

^[A-Za-z0-9_.]+$

From beginning until the end of the string, match one or more of these characters.

Edit:

Note that ^ and $ match the beginning and the end of a line. When multiline is enabled, this can mean that one line matches, but not the complete string.

Use \A for the beginning of the string, and \z for the end.

See for example: http://msdn.microsoft.com/en-us/library/h5181w5w(v=vs.110).aspx

How can I echo the whole content of a .html file in PHP?

Just use:

<?php
    include("/path/to/file.html");
?>

That will echo it as well. This also has the benefit of executing any PHP in the file.

If you need to do anything with the contents, use file_get_contents(),

For example,

<?php
    $pagecontents = file_get_contents("/path/to/file.html");

    echo str_replace("Banana", "Pineapple", $pagecontents);

?>

This doesn't execute code in that file, so be careful if you expect that to work.

I usually use:

include($_SERVER['DOCUMENT_ROOT']."/path/to/file/as/in/url.html");

as then I can move files without breaking the includes.

Image comparison - fast algorithm

I believe that dropping the size of the image down to an almost icon size, say 48x48, then converting to greyscale, then taking the difference between pixels, or Delta, should work well. Because we're comparing the change in pixel color, rather than the actual pixel color, it won't matter if the image is slightly lighter or darker. Large changes will matter since pixels getting too light/dark will be lost. You can apply this across one row, or as many as you like to increase the accuracy. At most you'd have 47x47=2,209 subtractions to make in order to form a comparable Key.

Getting the parent of a directory in Bash

use this : export MYVAR="$(dirname "$(dirname "$(dirname "$(dirname $PWD)")")")" if you want 4th parent directory

export MYVAR="$(dirname "$(dirname "$(dirname $PWD)")")" if you want 3rd parent directory

export MYVAR="$(dirname "$(dirname $PWD)")" if you want 2nd parent directory

Python Finding Prime Factors

The code is wrong with 100. It should check case i * i = n:

I think it should be:

while i * i <= n:
    if i * i = n:
        n = i
        break

    while n%i == 0:
        n = n / i
    i = i + 1

print (n)

How to set root password to null

The syntax is slightly different depending on version. From the docs here: https://dev.mysql.com/doc/refman/5.7/en/resetting-permissions.html

MySQL 5.7.6 and later:

ALTER USER 'root'@'localhost' IDENTIFIED BY '';

MySQL 5.7.5 and earlier:

SET PASSWORD FOR 'root'@'localhost' = PASSWORD('');

How do I connect to an MDF database file?

For Visual Studio 2015 the connection string is:

"Data Source=(localdb)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|Database1.mdf;Integrated Security=True"

Couldn't process file resx due to its being in the Internet or Restricted zone or having the mark of the web on the file

Complementing @lasse-v-karlsen answer. To unblock all files recursively, run from powershell as administrator inside the folder you want:

gci -recurse | Unblock-File

source link: How to Unblock Files Downloaded from Internet? - Winhelponline
https://www.winhelponline.com/blog/bulk-unblock-files-downloaded-internet/

Run a task every x-minutes with Windows Task Scheduler

On XP, I clicked the Advanced button on the Schedule tab. There is a checkbox for Repeat task. The default is every 10 minutes.

Additionally, you can create scheduled task via the command line. I haven't tried this myself, but it looks like you'd want something along the lines of (not tested):

schtasks /create /tn "Some task name" /tr "app.exe" /sc HOURLY 

How to use a ViewBag to create a dropdownlist?

hope it will work

 @Html.DropDownList("accountid", (IEnumerable<SelectListItem>)ViewBag.Accounts, String.Empty, new { @class ="extra-class" })

Here String.Empty will be the empty as a default selector.

A fast way to delete all rows of a datatable at once

If you are running your code against a sqlserver database then
use this command

string sqlTrunc = "TRUNCATE TABLE " + yourTableName
SqlCommand cmd = new SqlCommand(sqlTrunc, conn);
cmd.ExecuteNonQuery();

this will be the fastest method and will delete everything from your table and reset the identity counter to zero.

The TRUNCATE keyword is supported also by other RDBMS.

5 years later:
Looking back at this answer I need to add something. The answer above is good only if you are absolutely sure about the source of the value in the yourTableName variable. This means that you shouldn't get this value from your user because he can type anything and this leads to Sql Injection problems well described in this famous comic strip. Always present your user a choice between hard coded names (tables or other symbolic values) using a non editable UI.

adding line break

\n in c3 working correctly

using System; namespace testing2

public class Test { 
    public static void Main(string[] args) {
        Console.WriteLine("Enter your name");
        String s = Console.ReadLine();
        Console.WriteLine("Your name is " + s + "\n" + "Thank You");
    }
}

C# Return Different Types?

My post here is strictly related to Blazor v5 but should work in 3.x as well. Additionally, I'm using these methods with bootstrap 4.5 and 5.0 beta 1 but you could easily adapt it to use style's instead of classes or use your own classes.

To those recommending dynamic, I thank you. The dynamic type seems like it can be very valuable when used correctly. Most of the time you'll probably use an interface but this wasn't plausible for me. I went ahead and updated my project with a dynamic return type and it's working great while being the quickest, cleanest solution.

I previously added the following extension methods to boolean types to help me avoid long ternary operators in razor page code. Here are the 3 main extension methods I use to accomplish it:

public static T Then<T>(this bool value, T result) => value ? result : default;    
public static T Then<T>(this bool value, T thenResult, T elseResult) => value ? thenResult : elseResult;
public static T Else<T>(this bool value, T result) => !value ? result : default;

The following are examples of that implementation:

<div class="@Hidden.Then("d-none")">
    Hidden content...
</div>

Note: ErrorOrWarning would hide the content if there was no error/warning so I could default it to yellow/italic but this is an example so please use your imagination:

<div class="@ErrorOrWarning.Else("d-none")" style="@Error.Then("color:red;font-weight:bold;","color:yellow;font-style:italic;")">
    Error/Warning content...
</div>

This is the typical implementation without the extension methods. It's common to see this technique in Blazor guides/tutorials/videos online. There are cleaner ways to handle it but this is the basic idea:

<div class="@(ErrorOrWarning ? "" : "d-none")" style="@(Error ? "color:red;font-weight:bold;" : "color:yellow;font-style:italic;")">
    Error/Warning content...
</div>

While this might not seem like too big a difference, if you have a lot of dynamic content/styles driving your page, it can get really messy. With those 3 lines of code you can enhance the readability and cleanliness and it really does reduce risk of typos. Adding two more extension methods, you can reduce the risk even further Note: Again, this is using bootstrap class "d-none" for the style "display:none!important" but you could just as easily replace with your own usage:

public static string ThenShow(this bool value) => value ? "" : "d-none";
public static string ThenHide(this bool value) => value ? "d-none" : "";

The limitation I previously faced was when using the overloaded Then(thenResult, elseResult), each of the parameters must be of the same type. 99% of the time this is fine. Actually, another 0.5% of the time it's still okay because you can probably solve it quickly with a .ToString() or an explicit cast.

What I ran into, and what took me to this post was: I have a control you can imagine as a button. There is an Enum property allowing the user to select an icon to display. The selected Enum dynamically populates a readonly MarkupString property. As an alternative option, they can use the ChildContent (or IconContent in my example) of type RenderFragment. This will let them manually add anything they want (maybe an iFrame to stackoverflow haha) but my intention is for them to add style, most likely in the form of an icon.

I know I can cast/convert one to the other however my existing extension method is so clean and simple, it would be great to be able to use pass the MarkupString and RenderFragment together as parameters, conditionally output to the razor page. So, thanks to this post, I changed my Then(thenResult, elseResult) extension methods to use unique generic parameter types and return a dynamic type like so:

public static dynamic Then<T,E>(this bool value, T thenResult, E elseResult) => value ? thenResult : elseResult;

Now in my razor page I have a very simple line for the icon output. Note: IconContent is a RenderFragment and IconMarkup is a MarkupString.

@((@IconContent == null).Then(IconMarkup, IconContent))

And because I love extension methods and I'm typing this up, I took it a step further with another extension method:

public static bool IsNull(this RenderFragment value) => value == null;

Which enables the extremely clean and simple:

@IconContent.IsNull().Then(IconMarkup, IconContent)

Here's the extra extension method I mentioned above which converts a string to a MarkupString. It might be overkill but I like it.

public static MarkupString ToMarkup(this string value) => (MarkupString)value;

Let me know if you have a better recommendation or if you think I'm doing something wrong. I'm sure this post makes it seem like I overuse extension methods but I really don't. I keep their use limited to outcomes such as I've outlined in this post.

The client and server cannot communicate, because they do not possess a common algorithm - ASP.NET C# IIS TLS 1.0 / 1.1 / 1.2 - Win32Exception

Enabling TLS 1.0 solved our issues as well (after disabling SSL v3). (Server 2012 R2 with ASP.net 4.0 website processing against PPI pay services). This is the RegEdit script I used to set everything the way I wanted. We only disabled SSL v3 for the Client and not the server as doing that broke other things that we were not ready to deal with yet. After we upgrade the site to .Net 4.5.2 then we will disable TLS 1.0 again.

This script enables all protocols, Server and Client except for SSL v3 for the Client.

Be sure to backup your registry!

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 3.0\Client]
"Enabled"=dword:00000000

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 3.0\Server]
"Enabled"=dword:00000001

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.0\Client]
"Enabled"=dword:00000001

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.0\Client]
"DisabledByDefault"=dword:00000000

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.0\Server]
"Enabled"=dword:00000001

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.0\Server]
"DisabledByDefault"=dword:00000000

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Client]
"Enabled"=dword:00000001

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Client]
"DisabledByDefault"=dword:00000000

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Server]
"Enabled"=dword:00000001

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Server]
"DisabledByDefault"=dword:00000000

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Client]
"Enabled"=dword:00000001

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Client]
"DisabledByDefault"=dword:00000000

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Server]
"Enabled"=dword:00000001

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Server]
"DisabledByDefault"=dword:00000000

How can I hide select options with JavaScript? (Cross browser)

I thought I was bright ;-)

In CSS:

option:disabled {display:none;}

In Firefox and Chrome, a select with only the enabled options were created. Nice.

In IE, the enabled options were shown, the disabled where just blank lines, in their original location. Bad.

In Edge, the enabled options shown at top, followed by blank lines for disabled options. Acceptable.

How to disable HTML button using JavaScript?

Since this setting is not an attribute

It is an attribute.

Some attributes are defined as boolean, which means you can specify their value and leave everything else out. i.e. Instead of disabled="disabled", you include only the bold part. In HTML 4, you should include only the bold part as the full version is marked as a feature with limited support (although that is less true now then when the spec was written).

As of HTML 5, the rules have changed and now you include only the name and not the value. This makes no practical difference because the name and the value are the same.

The DOM property is also called disabled and is a boolean that takes true or false.

foo.disabled = true;

In theory you can also foo.setAttribute('disabled', 'disabled'); and foo.removeAttribute("disabled"), but I wouldn't trust this with older versions of Internet Explorer (which are notoriously buggy when it comes to setAttribute).

HTML5 input type range show range value

an even better way would be to catch the input event on the input itself rather than on the whole form (performance wise) :

<input type="range" id="rangeInput" name="rangeInput" min="0" max="20" value="0"
       oninput="amount.value=rangeInput.value">                                                       

<output id="amount" name="amount" for="rangeInput">0</output>

Here's a fiddle (with the id added as per Ryan's comment).

Variable not accessible when initialized outside function

Declare systemStatus in an outer scope and assign it in an onload handler.

systemStatus = null;

function onloadHandler(evt) {
    systemStatus = document.getElementById("....");
}

Or if you don't want the onload handler, put your script tag at the bottom of your HTML.

How to use Git Revert

Use git revert like so:

git revert <insert bad commit hash here>

git revert creates a new commit with the changes that are rolled back. git reset erases your git history instead of making a new commit.

The steps after are the same as any other commit.

Add some word to all or some rows in Excel?

Save a copy of your spreadsheet first (just in case).

  1. Insert two new columns to the left of the numbered column.

  2. Put a k in the first row of the first (new) column.

  3. Copy it (the k).

  4. Go to the original first column (now the third column) and leave your cursor on the first row that has data.

  5. Hit ctrl and down arrow (at the same time) to jump to the bottom of the populated data range for your original first column.

  6. Left arrow twice to get to the new first column, the one with a k at the very top.

  7. Hit Ctrl-shift-up arrow to go to the first cell with data populated (the original k you put in), highlighting all the cells in-between your starting and ending point.

  8. Use paste (ctrl-v, right-click or whatever your preferred method), and it'll fill all those cells with a k.

  9. Then use the "Concatenate" formula in the second column. Its two arguments will be the column of Ks (column A, first column) and the column with the numbers in it.

  10. This will get you a column with the results of the K column and your numbers.

Hope this helps! The ctrl-shift-arrow and ctrl-arrow shortcuts are amazing for working with large datasets in Excel.

String array initialization in Java

First up, this has got nothing to do with String, it is about arrays.. and that too specifically about declarative initialization of arrays.

As discussed by everyone in almost every answer here, you can, while declaring a variable, use:

String names[] = {"x","y","z"};

However, post declaration, if you want to assign an instance of an Array:

names = new String[] {"a","b","c"};

AFAIK, the declaration syntax is just a syntactic sugar and it is not applicable anymore when assigning values to variables because when values are assigned you need to create an instance properly.

However, if you ask us why it is so? Well... good luck getting an answer to that. Unless someone from the Java committee answers that or there is explicit documentation citing the said syntactic sugar.

Detect page change on DataTable

I've not found anything in the API, but one thing you could do is attach an event handler to the standard paginator and detect if it has changed:

$('.dataTables_length select').live('change', function(){
       alert(this.value);
    });

Shell script to get the process ID on Linux

Using grep on the results of ps is a bad idea in a script, since some proportion of the time it will also match the grep process you've just invoked. The command pgrep avoids this problem, so if you need to know the process ID, that's a better option. (Note that, of course, there may be many processes matched.)

However, in your example, you could just use the similar command pkill to kill all matching processes:

pkill ruby

Incidentally, you should be aware that using -9 is overkill (ho ho) in almost every case - there's some useful advice about that in the text of the "Useless Use of kill -9 form letter ":

No no no. Don't use kill -9.

It doesn't give the process a chance to cleanly:

  1. shut down socket connections
  2. clean up temp files
  3. inform its children that it is going away
  4. reset its terminal characteristics

and so on and so on and so on.

Generally, send 15, and wait a second or two, and if that doesn't work, send 2, and if that doesn't work, send 1. If that doesn't, REMOVE THE BINARY because the program is badly behaved!

Don't use kill -9. Don't bring out the combine harvester just to tidy up the flower pot.

Refused to load the font 'data:font/woff.....'it violates the following Content Security Policy directive: "default-src 'self'". Note that 'font-src'

In my laravel & VueJS project I solved this error with webpack.mix.js file. It contains

const mix = require('laravel-mix');

mix.webpackConfig({
   devServer: {
     proxy: {
       '*': 'http://localhost:8000'
     }
   },
   resolve: {
     alias: {
       "@": path.resolve(
         __dirname,
         "resources/assets/js"
       )
     }
   }
 });

mix.js('resources/js/app.js', 'public/js')
   .sass('resources/sass/app.scss', 'public/css');

Should ol/ul be inside <p> or outside?

GO here http://validator.w3.org/ upload your html file and it will tell you what is valid and what is not.

No Multiline Lambda in Python: Why not?

Here's a more interesting implementation of multi line lambdas. It's not possible to achieve because of how python use indents as a way to structure code.

But luckily for us, indent formatting can be disabled using arrays and parenthesis.

As some already pointed out, you can write your code as such:

lambda args: (expr1, expr2,... exprN)

In theory if you're guaranteed to have evaluation from left to right it would work but you still lose values being passed from one expression to an other.

One way to achieve that which is a bit more verbose is to have

lambda args: [lambda1, lambda2, ..., lambdaN]

Where each lambda receives arguments from the previous one.

def let(*funcs):
    def wrap(args):
        result = args                                                                                                                                                                                                                         
        for func in funcs:
            if not isinstance(result, tuple):
                result = (result,)
            result = func(*result)
        return result
    return wrap

This method let you write something that is a bit lisp/scheme like.

So you can write things like this:

let(lambda x, y: x+y)((1, 2))

A more complex method could be use to compute the hypotenuse

lst = [(1,2), (2,3)]
result = map(let(
  lambda x, y: (x**2, y**2),
  lambda x, y: (x + y) ** (1/2)
), lst)

This will return a list of scalar numbers so it can be used to reduce multiple values to one.

Having that many lambda is certainly not going to be very efficient but if you're constrained it can be a good way to get something done quickly then rewrite it as an actual function later.

PANIC: Cannot find AVD system path. Please define ANDROID_SDK_ROOT (in windows 10)

My problem was solved by creating a Windows user without an accent or special characters and reinstalling android studio on that user. Another change is to change the environment variables:

Left Click in My Computer > Advanced System Settings> Advanced > Environment Variables

ANDROID_HOME = c:\my_sdk_path

ANDROID_SDK_ROOT = c:\my_sdk_path

JAVA_HOME = c:\program files\Java\yourJavaPath

  • the default path of SDK is c:\users\youruser\AppData\LocalAndroid\sdk

Environment variables

Add in Path Variable the values:

  1. %ANDROID_HOME%\platform-tools

  2. %ANDROID_HOME%\tools

path variables

path values

After changes, restart windows and try again!

Git branching: master vs. origin/master vs. remotes/origin/master

I would try to make @ErichBSchulz's answer simpler for beginners:

  • origin/master is the state of master branch on remote repository
  • master is the state of master branch on local repository

Counting the number of non-NaN elements in a numpy ndarray in Python

Quick-to-write alterantive

Even though is not the fastest choice, if performance is not an issue you can use:

sum(~np.isnan(data)).

Performance:

In [7]: %timeit data.size - np.count_nonzero(np.isnan(data))
10 loops, best of 3: 67.5 ms per loop

In [8]: %timeit sum(~np.isnan(data))
10 loops, best of 3: 154 ms per loop

In [9]: %timeit np.sum(~np.isnan(data))
10 loops, best of 3: 140 ms per loop

How to Decrease Image Brightness in CSS

You can use css filters, below and example for web-kit. please look at this example: http://jsfiddle.net/m9sjdbx6/4/

    img { -webkit-filter: brightness(0.2);}

null check in jsf expression language

Use empty (it checks both nullness and emptiness) and group the nested ternary expression by parentheses (EL is in certain implementations/versions namely somewhat problematic with nested ternary expressions). Thus, so:

styleClass="#{empty obj.validationErrorMap ? ' ' :  
 (obj.validationErrorMap.contains('key') ? 'highlight_field' : 'highlight_row')}"

If still in vain (I would then check JBoss EL configs), use the "normal" EL approach:

styleClass="#{empty obj.validationErrorMap ? ' ' :  
 (obj.validationErrorMap['key'] ne null ? 'highlight_field' : 'highlight_row')}"

Update: as per the comments, the Map turns out to actually be a List (please work on your naming conventions). To check if a List contains an item the "normal" EL way, use JSTL fn:contains (although not explicitly documented, it works for List as well).

styleClass="#{empty obj.validationErrorMap ? ' ' :  
 (fn:contains(obj.validationErrorMap, 'key') ? 'highlight_field' : 'highlight_row')}"

Get a Div Value in JQuery

myDivObj = document.getElementById("myDiv");
if ( myDivObj ) {
   alert ( myDivObj.innerHTML ); 
}else{
   alert ( "Alien Found" );
}

Above code will show the innerHTML, i.e if you have used html tags inside div then it will show even those too. probably this is not what you expected. So another solution is to use: innerText / textContent property [ thanx to bobince, see his comment ]

function showDivText(){
            divObj = document.getElementById("myDiv");
            if ( divObj ){
                if ( divObj.textContent ){ // FF
                    alert ( divObj.textContent );
                }else{  // IE           
                    alert ( divObj.innerText );  //alert ( divObj.innerHTML );
                } 
            }  
        }

Sass nth-child nesting

You're trying to do &(2), &(4) which won't work

#romtest {
  .detailed {
    th {
      &:nth-child(2) {//your styles here}
      &:nth-child(4) {//your styles here}
      &:nth-child(6) {//your styles here}
      }
  }
}

104, 'Connection reset by peer' socket error, or When does closing a socket result in a RST rather than FIN?

I've had this problem. See The Python "Connection Reset By Peer" Problem.

You have (most likely) run afoul of small timing issues based on the Python Global Interpreter Lock.

You can (sometimes) correct this with a time.sleep(0.01) placed strategically.

"Where?" you ask. Beats me. The idea is to provide some better thread concurrency in and around the client requests. Try putting it just before you make the request so that the GIL is reset and the Python interpreter can clear out any pending threads.

Spring Hibernate - Could not obtain transaction-synchronized Session for current thread

I had this error too because in the file where I used @Transactional annotation, I was importing the wrong class

import javax.transaction.Transactional; 

Instead of javax, use

import org.springframework.transaction.annotation.Transactional; 

PHP convert date format dd/mm/yyyy => yyyy-mm-dd

I can see great answers, so there's no need to repeat here, so I'd like to offer some advice:

I would recommend using a Unix Timestamp integer instead of a human-readable date format to handle time internally, then use PHP's date() function to convert the timestamp value into a human-readable date format for user display. Here's a crude example of how it should be done:

// Get unix timestamp in seconds
$current_time = date();

// Or if you need millisecond precision

// Get unix timestamp in milliseconds
$current_time = microtime(true);

Then use $current_time as needed in your app (store, add or subtract, etc), then when you need to display the date value it to your users, you can use date() to specify your desired date format:

// Display a human-readable date format
echo date('d-m-Y', $current_time);

This way you'll avoid much headache dealing with date formats, conversions and timezones, as your dates will be in a standardized format (Unix Timestamp) that is compact, timezone-independent (always in UTC) and widely supported in programming languages and databases.

Sending string via socket (python)

This piece of code is incorrect.

while 1:
    (clientsocket, address) = serversocket.accept()
    print ("connection found!")
    data = clientsocket.recv(1024).decode()
    print (data)
    r='REceieve'
    clientsocket.send(r.encode())

The call on accept() on the serversocket blocks until there's a client connection. When you first connect to the server from the client, it accepts the connection and receives data. However, when it enters the loop again, it is waiting for another connection and thus blocks as there are no other clients that are trying to connect.

That's the reason the recv works correct only the first time. What you should do is find out how you can handle the communication with a client that has been accepted - maybe by creating a new Thread to handle communication with that client and continue accepting new clients in the loop, handling them in the same way.

Tip: If you want to work on creating your own chat application, you should look at a networking engine like Twisted. It will help you understand the whole concept better too.

Case insensitive 'in'

To have it in one line, this is what I did:

if any(([True if 'MICHAEL89' in username.upper() else False for username in USERNAMES])):
    print('username exists in list')

I didn't test it time-wise though. I am not sure how fast/efficient it is.

Filter dataframe rows if value in column is in a set list of values

You can use query, i.e.:

b = df.query('a > 1 & a < 5')

Setting Action Bar title and subtitle

This is trivial one-liner in Kotlin

supportActionBar?.title = getString(R.string.coolTitle)

Why does the JFrame setSize() method not set the size correctly?

JFrame SetSize() contains the the Area + Border.

I think you have to set the size of ContentPane of that

jFrame.getContentPane().setSize(800,400);

So I would advise you to use JPanel embedded in a JFrame and you draw on that JPanel. This would minimize your problem.

JFrame jf = new JFrame();
JPanel jp = new JPanel();
jp.setPreferredSize(new Dimension(400,800));// changed it to preferredSize, Thanks!
jf.getContentPane().add( jp );// adding to content pane will work here. Please read the comment bellow.
jf.pack();

I am reading this from Javadoc

The JFrame class is slightly incompatible with Frame. Like all other JFC/Swing top-level containers, a JFrame contains a JRootPane as its only child. The content pane provided by the root pane should, as a rule, contain all the non-menu components displayed by the JFrame. This is different from the AWT Frame case. For example, to add a child to an AWT frame you'd write:

frame.add(child);

However using JFrame you need to add the child to the JFrame's content pane instead:

frame.getContentPane().add(child);

How to redirect the output of a PowerShell to a file during its execution

If you want to do it from the command line and not built into the script itself, use:

.\myscript.ps1 | Out-File c:\output.csv

JavaScript Infinitely Looping slideshow with delays?

You can infinitely loop easily enough via recursion.

function it_keeps_going_and_going_and_going() {
  it_keeps_going_and_going_and_going();
}

it_keeps_going_and_going_and_going()

Turning multiple lines into one comma separated line

sed -n 's/.*/&,/;H;$x;$s/,\n/,/g;$s/\n\(.*\)/\1/;$s/\(.*\),/\1/;$p'

How to get the parents of a Python class?

If you want to ensure they all get called, use super at all levels.

How can I run a windows batch file but hide the command window?

Create a shortcut to your bat file by using the right-click and selecting Create shortcut. Right-click on the shortcut you created and click on properties. Click on the Run drop-down box and select Minimized.

Custom domain for GitHub project pages

Things are lot easier nowadays!

  1. Update your Apex domain (@) record to point

192.30.252.154

192.30.252.153

  1. Edit your Custome domain field in your github repo settings.

enter image description here

  1. www and other subdomains can be updated as CNAME to apex domain.

text box input height

Use CSS:

<input type="text" class="bigText"  name=" item" align="left" />

.bigText {
    height:30px;
}

Dreamweaver is a poor testing tool. It is not a browser.

Static methods in Python?

Python Static methods can be created in two ways.

  1. Using staticmethod()

    class Arithmetic:
        def add(x, y):
            return x + y
    # create add static method
    Arithmetic.add = staticmethod(Arithmetic.add)
    
    print('Result:', Arithmetic.add(15, 10))
    

Output:

Result: 25

  1. Using @staticmethod

    class Arithmetic:
    
    # create add static method
    @staticmethod
    def add(x, y):
        return x + y
    
    print('Result:', Arithmetic.add(15, 10))
    

Output:

Result: 25

Algorithm to return all combinations of k elements from n

In Python like Andrea Ambu, but not hardcoded for choosing three.

def combinations(list, k):
    """Choose combinations of list, choosing k elements(no repeats)"""
    if len(list) < k:
        return []
    else:
        seq = [i for i in range(k)]
        while seq:
            print [list[index] for index in seq]
            seq = get_next_combination(len(list), k, seq)

def get_next_combination(num_elements, k, seq):
        index_to_move = find_index_to_move(num_elements, seq)
        if index_to_move == None:
            return None
        else:
            seq[index_to_move] += 1

            #for every element past this sequence, move it down
            for i, elem in enumerate(seq[(index_to_move+1):]):
                seq[i + 1 + index_to_move] = seq[index_to_move] + i + 1

            return seq

def find_index_to_move(num_elements, seq):
        """Tells which index should be moved"""
        for rev_index, elem in enumerate(reversed(seq)):
            if elem < (num_elements - rev_index - 1):
                return len(seq) - rev_index - 1
        return None   

Show loading screen when navigating between routes in Angular 2

Why not just using simple css :

<router-outlet></router-outlet>
<div class="loading"></div>

And in your styles :

div.loading{
    height: 100px;
    background-color: red;
    display: none;
}
router-outlet + div.loading{
    display: block;
}

Or even we can do this for the first answer:

<router-outlet></router-outlet>
<spinner-component></spinner-component>

And then simply just

spinner-component{
   display:none;
}
router-outlet + spinner-component{
    display: block;
}

The trick here is, the new routes and components will always appear after router-outlet , so with a simple css selector we can show and hide the loading.

Nothing was returned from render. This usually means a return statement is missing. Or, to render nothing, return null

i solved the problem i exlained...for example in the file we render the other component,other component name is same with me method of current component such as:

const Login = () => {

}

render(
  <Login/>
)

..for solve this we must change the method name

How to set the max size of upload file

If you get a "connection resets" error, the problem could be in the Tomcat default connector maxSwallowSize attribute added from Tomcat 7.0.55 (ChangeLog)

From Apache Tomcat 8 Configuration Reference

maxSwallowSize: The maximum number of request body bytes (excluding transfer encoding overhead) that will be swallowed by Tomcat for an aborted upload. An aborted upload is when Tomcat knows that the request body is going to be ignored but the client still sends it. If Tomcat does not swallow the body the client is unlikely to see the response. If not specified the default of 2097152 (2 megabytes) will be used. A value of less than zero indicates that no limit should be enforced.

For Springboot embedded Tomcat declare a TomcatEmbeddedServletContainerFactory

Java 8:

@Bean
public TomcatEmbeddedServletContainerFactory tomcatEmbedded() {
    TomcatEmbeddedServletContainerFactory tomcat = new TomcatEmbeddedServletContainerFactory();
    tomcat.addConnectorCustomizers((TomcatConnectorCustomizer) connector -> {
        if ((connector.getProtocolHandler() instanceof AbstractHttp11Protocol<?>)) {
            //-1 for unlimited
            ((AbstractHttp11Protocol<?>) connector.getProtocolHandler()).setMaxSwallowSize(-1);
        }
    });
    return tomcat;
}

Java 7:

@Bean
public TomcatEmbeddedServletContainerFactory tomcatEmbedded() {
    TomcatEmbeddedServletContainerFactory tomcat = new TomcatEmbeddedServletContainerFactory();
    tomcat.addConnectorCustomizers(new TomcatConnectorCustomizer()  {
        @Override
        public void customize(Connector connector) {
            if ((connector.getProtocolHandler() instanceof AbstractHttp11Protocol<?>)) {
                //-1 for unlimited
                ((AbstractHttp11Protocol<?>) connector.getProtocolHandler()).setMaxSwallowSize(-1);
            }
        }
    });
    return tomcat;
}

Or in the Tomcat/conf/server.xml for 5MB

<Connector port="8080" protocol="HTTP/1.1"
       connectionTimeout="20000"
       redirectPort="8443"
       maxSwallowSize="5242880" />

remove all variables except functions

I wrote this to remove all objects apart from functions from the current environment (Programming language used is R with IDE R-Studio):

    remove_list=c()                             # create a vector

      for(i in 1:NROW(ls())){                   # repeat over all objects in environment
        if(class(get(ls()[i]))!="function"){    # if object is *not* a function
         remove_list=c(remove_list,ls()[i])     # ..add to vector remove_list
         }    
      }

    rm(list=remove_list)                        # remove all objects named in remove_list

Notes-

The argument "list" in rm(list=) must be a character vector.

The name of an object in position i of the current environment is returned from ls()[i] and the object itself from get(ls()[i]). Therefore the class of an object is returned from class(get(ls()[i]))

Re-assign host access permission to MySQL user

I haven't had to do this, so take this with a grain of salt and a big helping of "test, test, test".

What happens if (in a safe controlled test environment) you directly modify the Host column in the mysql.user and probably mysql.db tables? (E.g., with an update statement.) I don't think MySQL uses the user's host as part of the password encoding (the PASSWORD function doesn't suggest it does), but you'll have to try it to be sure. You may need to issue a FLUSH PRIVILEGES command (or stop and restart the server).

For some storage engines (MyISAM, for instance), you may also need to check/modify the .frm file any views that user has created. The .frm file stores the definer, including the definer's host. (I have had to do this, when moving databases between hosts where there had been a misconfiguration causing the wrong host to be recorded...)

Javascript: Easier way to format numbers?

Also try dojo.number which has built-in localization support. It is a much closer analog to Java's NumberFormat/DecimalFormat

How do I convert a dictionary to a JSON String in C#?

Json.NET probably serializes C# dictionaries adequately now, but when the OP originally posted this question, many MVC developers may have been using the JavaScriptSerializer class because that was the default option out of the box.

If you're working on a legacy project (MVC 1 or MVC 2), and you can't use Json.NET, I recommend that you use a List<KeyValuePair<K,V>> instead of a Dictionary<K,V>>. The legacy JavaScriptSerializer class will serialize this type just fine, but it will have problems with a dictionary.

Documentation: Serializing Collections with Json.NET

Concatenate in jQuery Selector

There is nothing wrong with syntax of

$('#part' + number).html(text);

jQuery accepts a String (usually a CSS Selector) or a DOM Node as parameter to create a jQuery Object.

In your case you should pass a String to $() that is

$(<a string>)

Make sure you have access to the variables number and text.

To test do:

function(){
    alert(number + ":" + text);//or use console.log(number + ":" + text)
    $('#part' + number).html(text);
}); 

If you see you dont have access, pass them as parameters to the function, you have to include the uual parameters for $.get and pass the custom parameters after them.

How can I avoid ResultSet is closed exception in Java?

Sounds like you executed another statement in the same connection before traversing the result set from the first statement. If you're nesting the processing of two result sets from the same database, you're doing something wrong. The combination of those sets should be done on the database side.

Select2 doesn't work when embedded in a bootstrap modal

If you use jquery mobile popup you must rewrite _handleDocumentFocusIn function:

_x000D_
_x000D_
$.mobile.popup.prototype._handleDocumentFocusIn = function(e) {_x000D_
  if ($(e.target).closest('.select2-dropdown').length) return true;_x000D_
}
_x000D_
_x000D_
_x000D_

Android runOnUiThread explanation

If you already have the data "for (Parcelable currentHeadline : allHeadlines)," then why are you doing that in a separate thread?

You should poll the data in a separate thread, and when it's finished gathering it, then call your populateTables method on the UI thread:

private void populateTable() {
    runOnUiThread(new Runnable(){
        public void run() {
            //If there are stories, add them to the table
            for (Parcelable currentHeadline : allHeadlines) {
                addHeadlineToTable(currentHeadline);
            }
            try {
                dialog.dismiss();
            } catch (final Exception ex) {
                Log.i("---","Exception in thread");
            }
        }
    });
}

Create table with jQuery - append

Or do it this way to use ALL jQuery. The each can loop through any data be it DOM elements or an array/object.

var data = ['one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight'];
var numCols = 1;           


$.each(data, function(i) {
  if(!(i%numCols)) tRow = $('<tr>');

  tCell = $('<td>').html(data[i]);

  $('table').append(tRow.append(tCell));
});
?

http://jsfiddle.net/n7cyE/93/

How to sign in kubernetes dashboard?

As of release 1.7 Dashboard supports user authentication based on:

— Dashboard on Github

Token

Here Token can be Static Token, Service Account Token, OpenID Connect Token from Kubernetes Authenticating, but not the kubeadm Bootstrap Token.

With kubectl, we can get an service account (eg. deployment controller) created in kubernetes by default.

$ kubectl -n kube-system get secret
# All secrets with type 'kubernetes.io/service-account-token' will allow to log in.
# Note that they have different privileges.
NAME                                     TYPE                                  DATA      AGE
deployment-controller-token-frsqj        kubernetes.io/service-account-token   3         22h

$ kubectl -n kube-system describe secret deployment-controller-token-frsqj
Name:         deployment-controller-token-frsqj
Namespace:    kube-system
Labels:       <none>
Annotations:  kubernetes.io/service-account.name=deployment-controller
              kubernetes.io/service-account.uid=64735958-ae9f-11e7-90d5-02420ac00002

Type:  kubernetes.io/service-account-token

Data
====
ca.crt:     1025 bytes
namespace:  11 bytes
token:      eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.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.OqFc4CE1Kh6T3BTCR4XxDZR8gaF1MvH4M3ZHZeCGfO-sw-D0gp826vGPHr_0M66SkGaOmlsVHmP7zmTi-SJ3NCdVO5viHaVUwPJ62hx88_JPmSfD0KJJh6G5QokKfiO0WlGN7L1GgiZj18zgXVYaJShlBSz5qGRuGf0s1jy9KOBt9slAN5xQ9_b88amym2GIXoFyBsqymt5H-iMQaGP35tbRpewKKtly9LzIdrO23bDiZ1voc5QZeAZIWrizzjPY5HPM1qOqacaY9DcGc7akh98eBJG_4vZqH2gKy76fMf0yInFTeNKr45_6fWt8gRM77DQmPwb3hbrjWXe1VvXX_g

Kubeconfig

The dashboard needs the user in the kubeconfig file to have either username & password or token, but admin.conf only has client-certificate. You can edit the config file to add the token that was extracted using the method above.

$ kubectl config set-credentials cluster-admin --token=bearer_token

Alternative (Not recommended for Production)

Here are two ways to bypass the authentication, but use for caution.

Deploy dashboard with HTTP

$ kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/master/src/deploy/alternative/kubernetes-dashboard.yaml

Dashboard can be loaded at http://localhost:8001/ui with kubectl proxy.

Granting admin privileges to Dashboard's Service Account

$ cat <<EOF | kubectl create -f -
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: kubernetes-dashboard
  labels:
    k8s-app: kubernetes-dashboard
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- kind: ServiceAccount
  name: kubernetes-dashboard
  namespace: kube-system
EOF

Afterwards you can use Skip option on login page to access Dashboard.

If you are using dashboard version v1.10.1 or later, you must also add --enable-skip-login to the deployment's command line arguments. You can do so by adding it to the args in kubectl edit deployment/kubernetes-dashboard --namespace=kube-system.

Example:

      containers:
      - args:
        - --auto-generate-certificates
        - --enable-skip-login            # <-- add this line
        image: k8s.gcr.io/kubernetes-dashboard-amd64:v1.10.1

how to open .mat file without using MATLAB?

I didn't use it myself but heard of a simple tool (not a text editor) for this so it is definitely possible without setting up a programming environment (by installing octave or python).

A quick search hints that it was possible with total commander. (A lightweight tool with an easy point and click interface)

I would not be surprised if this still works, but I can't guarantee it.

How to import/include a CSS file using PHP code and not HTML code?

Just put

echo "<link rel='stylesheet' type='text/css' href='CSS/main.css'>";

inside the php code, then your style is incuded. Worked for me, I tried.

Black transparent overlay on image hover with only CSS?

I would give a min-height and min-width to your overlay div of the size of the image, and change the background color on hover

.overlay { position: absolute; top: 0; left: 0;  z-index: 200; min-height:200px; min-width:200px; background-color: none;}
.overlay:hover { background-color: red;}

Determine the number of NA values in a column

In the summary() output, the function also counts the NAs so one can use this function if one wants the sum of NAs in several variables.

MySql: is it possible to 'SUM IF' or to 'COUNT IF'?

From MYSQL I solved the problem like this:

SUM(CASE WHEN used = 1 THEN 1 ELSE 0 END) as amount_one,

Hope this helps :D

Disable sorting for a particular column in jQuery DataTables

You can directry use .notsortable() method on column

 vm.dtOpt_product = DTOptionsBuilder.newOptions()
                .withOption('responsive', true)
        vm.dtOpt_product.withPaginationType('full_numbers');
        vm.dtOpt_product.withColumnFilter({
            aoColumns: [{
                    type: 'null'
                }, {
                    type: 'text',
                    bRegex: true,
                    bSmart: true
                }, {
                    type: 'text',
                    bRegex: true,
                    bSmart: true
                }, {
                    type: 'text',
                    bRegex: true,
                    bSmart: true
                }, {
                    type: 'select',
                    bRegex: false,
                    bSmart: true,
                    values: vm.dtProductTypes
                }]

        });

        vm.dtColDefs_product = [
            DTColumnDefBuilder.newColumnDef(0), DTColumnDefBuilder.newColumnDef(1),
            DTColumnDefBuilder.newColumnDef(2), DTColumnDefBuilder.newColumnDef(3).withClass('none'),
            DTColumnDefBuilder.newColumnDef(4), DTColumnDefBuilder.newColumnDef(5).notSortable()
        ];

Pass accepts header parameter to jquery ajax

There two alternate ways to set accept header, which are as below:

1) setRequestHeader('Accept','application/json; charset=utf-8');

2) $.ajax({
    dataType: ($.browser.msie) ? "text" : "json",
    accepts: {
        text: "application/json"
    }
});

How do I stretch a background image to cover the entire HTML element?

Simply make a div to be the direct child of body (with the class name bg for example), encompassing all other elements in the body, and add this to the CSS file:

.bg {
    background-image: url('_images/home.jpg');//Put your appropriate image URL here
    background-size: 100% 100%; //You need to put 100% twice here to stretch width and height
}

Refer to this link: https://www.w3schools.com/css/css_rwd_images.asp Scroll down to the part that says:

  1. If the background-size property is set to "100% 100%", the background image will stretch to cover the entire content area

There it shows the 'img_flowers.jpg' stretching to the size of the screen or browser regardless of how you resize it.

How can I find the version of php that is running on a distinct domain name?

By chance: Default error pages often contain detailed information, e.g.

Apache/{Version} ({OS}) {Modules} PHP/{Version} {Modules} Server at {Domain}

Not so easy: Find out which versions of PHP applications run on the server and which version of PHP they require.

Another approach, only mentioned for the sake of completeness; please forget after reading: You could (but you won't!) detect the PHP version by trying known exploits.

Ascending and Descending Number Order in java

package pack2;

import java.util.Scanner;

public class group {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    Scanner data= new Scanner(System.in);
    int value[]= new int[5];
    int temp=0,i=0,j=0;
    System.out.println("Enter 5 element of array");
    for(i=0;i<5;i++)
    value[i]=data.nextInt();
     for(i=0;i<5;i++)
     {
     for(j=i;j<5;j++)
     {
      if(value[i]>value[j])
      {
       temp=value[i];
       value[i]=value[j];
       value[j]=temp;
      }
     }

     }
      System.out.println("Increasing Order:");
      for(i=0;i<5;i++)
           System.out.println(""+value[i]); 
    }

How to compile python script to binary executable

Since other SO answers link to this question it's worth noting that there is another option now in PyOxidizer.

It's a rust utility which works in some of the same ways as pyinstaller, however has some additional features detailed here, to summarize the key ones:

  • Single binary of all packages by default with the ability to do a zero-copy load of modules into memory, vs pyinstaller extracting them to a temporary directory when using onefile mode
  • Ability to produce a static linked binary

(One other advantage of pyoxidizer is that it does not seem to suffer from the GLIBC_X.XX not found problem that can crop up with pyinstaller if you've created your binary on a system that has a glibc version newer than the target system).

Overall pyinstaller is much simpler to use than PyOxidizer, which often requires some complexity in the configuration file, and it's less Pythony since it's written in Rust and uses a configuration file format not very familiar in the Python world, but PyOxidizer does some more advanced stuff, especially if you are looking to produce single binaries (which is not pyinstaller's default).

Preferred Java way to ping an HTTP URL for availability

Instead of using URLConnection use HttpURLConnection by calling openConnection() on your URL object.

Then use getResponseCode() will give you the HTTP response once you've read from the connection.

here is code:

    HttpURLConnection connection = null;
    try {
        URL u = new URL("http://www.google.com/");
        connection = (HttpURLConnection) u.openConnection();
        connection.setRequestMethod("HEAD");
        int code = connection.getResponseCode();
        System.out.println("" + code);
        // You can determine on HTTP return code received. 200 is success.
    } catch (MalformedURLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } finally {
        if (connection != null) {
            connection.disconnect();
        }
    }

Also check similar question How to check if a URL exists or returns 404 with Java?

Hope this helps.

Converting a Pandas GroupBy output from Series to DataFrame

I found this worked for me.

import numpy as np
import pandas as pd

df1 = pd.DataFrame({ 
    "Name" : ["Alice", "Bob", "Mallory", "Mallory", "Bob" , "Mallory"] , 
    "City" : ["Seattle", "Seattle", "Portland", "Seattle", "Seattle", "Portland"]})

df1['City_count'] = 1
df1['Name_count'] = 1

df1.groupby(['Name', 'City'], as_index=False).count()

top align in html table?

Some CSS :

table td, table td * {
    vertical-align: top;
}

How to delete specific columns with VBA?

You say you want to delete any column with the title "Percent Margin of Error" so let's try to make this dynamic instead of naming columns directly.

Sub deleteCol()

On Error Resume Next

Dim wbCurrent As Workbook
Dim wsCurrent As Worksheet
Dim nLastCol, i As Integer

Set wbCurrent = ActiveWorkbook
Set wsCurrent = wbCurrent.ActiveSheet
'This next variable will get the column number of the very last column that has data in it, so we can use it in a loop later
nLastCol = wsCurrent.Cells.Find("*", LookIn:=xlValues, SearchOrder:=xlByColumns, SearchDirection:=xlPrevious).Column

'This loop will go through each column header and delete the column if the header contains "Percent Margin of Error"
For i = nLastCol To 1 Step -1
    If InStr(1, wsCurrent.Cells(1, i).Value, "Percent Margin of Error", vbTextCompare) > 0 Then
        wsCurrent.Columns(i).Delete Shift:=xlShiftToLeft
    End If
Next i

End Sub

With this you won't need to worry about where you data is pasted/imported to, as long as the column headers are in the first row.

EDIT: And if your headers aren't in the first row, it would be a really simple change. In this part of the code: If InStr(1, wsCurrent.Cells(1, i).Value, "Percent Margin of Error", vbTextCompare) change the "1" in Cells(1, i) to whatever row your headers are in.

EDIT 2: Changed the For section of the code to account for completely empty columns.

How to fetch JSON file in Angular 2

Here is a part of my code that parse JSON, it may be helpful for you:

import { Component, Input } from '@angular/core';
import { Injectable }     from '@angular/core';
import { Http, Response, Headers, RequestOptions } from '@angular/http';
import {Observable} from 'rxjs/Rx';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';

@Injectable()
export class AppServices{

    constructor(private http: Http) {
         var obj;
         this.getJSON().subscribe(data => obj=data, error => console.log(error));
    }

    public getJSON(): Observable<any> {
         return this.http.get("./file.json")
                         .map((res:any) => res.json())
                         .catch((error:any) => console.log(error));

     }
}

Can I edit an iPad's host file?

Yes, you can edit the iPad hosts file, but you need to be jailbroken. Once you've done that, download Cydia (app market), and get iFile. The hosts file is located within "/etc/hosts".

Convert Uri to String and String to Uri

Try this to convert string to uri

String mystring="Hello"
Uri myUri = Uri.parse(mystring);

Uri to String

Uri uri;
String uri_to_string;
uri_to_string= uri.toString();

best practice to generate random token for forgot password

This answers the 'best random' request:

Adi's answer1 from Security.StackExchange has a solution for this:

Make sure you have OpenSSL support, and you'll never go wrong with this one-liner

$token = bin2hex(openssl_random_pseudo_bytes(16));

1. Adi, Mon Nov 12 2018, Celeritas, "Generating an unguessable token for confirmation e-mails", Sep 20 '13 at 7:06, https://security.stackexchange.com/a/40314/

How does one create an InputStream from a String?

Java 7+

It's possible to take advantage of the StandardCharsets JDK class:

String str=...
InputStream is = new ByteArrayInputStream(StandardCharsets.UTF_16.encode(str).array());

Unexpected character encountered while parsing value

Suppose this is your json

{
  "date":"11/05/2016",
  "venue": "{\"ID\":12,\"CITY\":Delhi}"
}

if you again want deserialize venue, modify json as below

{
  "date":"11/05/2016",
  "venue": "{\"ID\":\"12\",\"CITY\":\"Delhi\"}"
}

then try to deserialize to respective class by taking the value of venue

How to solve a timeout error in Laravel 5

set time limit in __construct method or you can set in your index controller also where you want to have large time limit.

public function __construct()
{
    set_time_limit(8000000);
}

notifyDataSetChanged not working on RecyclerView

Clear your old viewmodel and set the new data to the adapter and call notifyDataSetChanged()

C++ - How to append a char to char*?

The function name does not reflect the semantic of the function. In fact you do not append a character. You create a new character array that contains the original array plus the given character. So if you indeed need a function that appends a character to a character array I would write it the following way

bool AppendCharToCharArray( char *array, size_t n, char c )
{
    size_t sz = std::strlen( array );

    if ( sz + 1 < n ) 
    {
        array[sz] = c;
        array[sz + 1] = '\0';
    }       

    return ( sz + 1 < n );
} 

If you need a function that will contain a copy of the original array plus the given character then it could look the following way

char * CharArrayPlusChar( const char *array, char c )
{
    size_t sz = std::strlen( array );
    char *s = new char[sz + 2];

    std::strcpy( s, array );
    s[sz] = c;
    s[sz + 1] = '\0';

    return ( s );
} 

How to get a right click mouse event? Changing EventArgs to MouseEventArgs causes an error in Form1Designer?

You need MouseClick instead of Click event handler, reference.

switch (e.Button) {

    case MouseButtons.Left:
    // Left click
    break;

    case MouseButtons.Right:
    // Right click
    break;
    ...
}

Getting a list of associative array keys

I am currently using Rob de la Cruz's reply:

Object.keys(obj)

And in a file loaded early on I have some lines of code borrowed from elsewhere on the Internet which cover the case of old versions of script interpreters that do not have Object.keys built in.

if (!Object.keys) {
    Object.keys = function(object) {
        var keys = [];
        for (var o in object) {
            if (object.hasOwnProperty(o)) {
                keys.push(o);
            }
        }
        return keys;
    };
}

I think this is the best of both worlds for large projects: simple modern code and backwards compatible support for old versions of browsers, etc.

Effectively it puts JW's solution into the function when Rob de la Cruz's Object.keys(obj) is not natively available.

In AVD emulator how to see sdcard folder? and Install apk to AVD?

  1. switch to DDMS perspective
  2. select the emulator in devices list, whose sdcard you want to explore.
  3. open File Explorer tab on right hand side.
  4. expand tree structure. mnt/sdcard/

refer to image belowenter image description here


To install apk manually: copy your apk to to sdk/platform-tools folder and run following command in the same folder

adb install apklocation.apk

Can I stop 100% Width Text Boxes from extending beyond their containers?

If you don't need to do it dynamically (for example, your form is of a fixed width) you can just set the width of child <input> elements to the width of their container minus any decorations like padding, margin, border, etc.:

 // the parent div here has a width of 200px:
.form-signin input[type="text"], .form-signin input[type="password"], .form-signin input[type="email"], .form-signin input[type="number"] {
  font-size: 16px;
  height: auto;
  display: block;
  width: 280px;
  margin-bottom: 15px;
  padding: 7px 9px;
}

$(form).ajaxSubmit is not a function

Drupal 8

Drupal 8 does not include JS-libraries to pages automaticly. So most probably if you meet this error you need to attach 'core/jquery.form' library to your page (or form). Add something like this to your render array:

$form['#attached']['library'][] = 'core/jquery.form';

Autoplay audio files on an iPad with HTML5

It seems to me that the answer to this question is (at least now) clearly documented on the Safari HTML5 docs:

User Control of Downloads Over Cellular Networks

In Safari on iOS (for all devices, including iPad), where the user may be on a cellular network and be charged per data unit, preload and autoplay are disabled. No data is loaded until the user initiates it. This means the JavaScript play() and load() methods are also inactive until the user initiates playback, unless the play() or load() method is triggered by user action. In other words, a user-initiated Play button works, but an onLoad="play()" event does not.

This plays the movie: <input type="button" value="Play" onClick="document.myMovie.play()">

This does nothing on iOS: <body onLoad="document.myMovie.play()">

Extract specific columns from delimited file using Awk

Other languages have short cuts for ranges of field numbers, but not awk, you'll have to write your code as your fear ;-)

awk -F, 'BEGIN {OFS=","} { print $1, $2, $3, $4 ..... $30, $33}' infile.csv > outfile.csv

There is no direct function in awk to use field names as column specifiers.

I hope this helps.

Getting Image from API in Angular 4/5+?

angular 5 :

 getImage(id: string): Observable<Blob> {
    return this.httpClient.get('http://myip/image/'+id, {responseType: "blob"});
}

Registering for Push Notifications in Xcode 8/Swift 3.0?

import UserNotifications  

Next, go to the project editor for your target, and in the General tab, look for the Linked Frameworks and Libraries section.

Click + and select UserNotifications.framework:

// iOS 12 support
if #available(iOS 12, *) {  
    UNUserNotificationCenter.current().requestAuthorization(options:[.badge, .alert, .sound, .provisional, .providesAppNotificationSettings, .criticalAlert]){ (granted, error) in }
    application.registerForRemoteNotifications()
}

// iOS 10 support
if #available(iOS 10, *) {  
    UNUserNotificationCenter.current().requestAuthorization(options:[.badge, .alert, .sound]){ (granted, error) in }
    application.registerForRemoteNotifications()
}
// iOS 9 support
else if #available(iOS 9, *) {  
    UIApplication.shared.registerUserNotificationSettings(UIUserNotificationSettings(types: [.badge, .sound, .alert], categories: nil))
    UIApplication.shared.registerForRemoteNotifications()
}
// iOS 8 support
else if #available(iOS 8, *) {  
    UIApplication.shared.registerUserNotificationSettings(UIUserNotificationSettings(types: [.badge, .sound, .alert], categories: nil))
    UIApplication.shared.registerForRemoteNotifications()
}
// iOS 7 support
else {  
    application.registerForRemoteNotifications(matching: [.badge, .sound, .alert])
}

Use Notification delegate methods

// Called when APNs has assigned the device a unique token
func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {  
    // Convert token to string
    let deviceTokenString = deviceToken.reduce("", {$0 + String(format: "%02X", $1)})
    print("APNs device token: \(deviceTokenString)")
}

// Called when APNs failed to register the device for push notifications
func application(_ application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: Error) {  
    // Print the error to console (you should alert the user that registration failed)
    print("APNs registration failed: \(error)")
}

For receiving push notification

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any], fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
    completionHandler(UIBackgroundFetchResult.noData)
}

Setting up push notifications is enabling the feature within Xcode 8 for your app. Simply go to the project editor for your target and then click on the Capabilities tab. Look for Push Notifications and toggle its value to ON.

Check below link for more Notification delegate methods

Handling Local and Remote Notifications UIApplicationDelegate - Handling Local and Remote Notifications

https://developer.apple.com/reference/uikit/uiapplicationdelegate

Have nginx access_log and error_log log to STDOUT and STDERR of master process

When running Nginx in a Docker container, be aware that a volume mounted over the log dir defeats the purpose of creating a softlink between the log files and stdout/stderr in your Dockerfile, as described in @Boeboe 's answer.

In that case you can either create the softlink in your entrypoint (executed after volumes are mounted) or not use a volume at all (e.g. when logs are already collected by a central logging system).

How to align this span to the right of the div?

You can do this without modifying the html. http://jsfiddle.net/8JwhZ/1085/

<div class="title">
<span>Cumulative performance</span>
<span>20/02/2011</span>
</div>

.title span:nth-of-type(1) { float:right }
.title span:nth-of-type(2) { float:left }

Difference between DOMContentLoaded and load events

The DOMContentLoaded event will fire as soon as the DOM hierarchy has been fully constructed, the load event will do it when all the images and sub-frames have finished loading.

DOMContentLoaded will work on most modern browsers, but not on IE including IE9 and above. There are some workarounds to mimic this event on older versions of IE, like the used on the jQuery library, they attach the IE specific onreadystatechange event.

java.security.cert.CertificateException: Certificates does not conform to algorithm constraints

this is more likely happening because somewhere along your certificate chain you have a certificate, more likely an old root, which is still signed with the MD2RSA algorythm.

You need to locate it into your certificate store and delete it.

Then get back to your certification authority and ask them for then new root.

It will more likely be the same root with the same validity period but it has been recertified with SHA1RSA.

Hope this help.

"Could not run curl-config: [Errno 2] No such file or directory" when installing pycurl

Similarly with yum package manager

yum install libcurl-devel

If you use dnf, use

dnf install libcurl-devel

Using Javascript in CSS

Not in any conventional sense of the phrase "inside CSS."

Rotate a div using javascript

I recently had to build something similar. You can check it out in the snippet below.

The version I had to build uses the same button to start and stop the spinner, but you can manipulate to code if you have a button to start the spin and a different button to stop the spin

Basically, my code looks like this...

Run Code Snippet

_x000D_
_x000D_
var rocket = document.querySelector('.rocket');_x000D_
var btn = document.querySelector('.toggle');_x000D_
var rotate = false;_x000D_
var runner;_x000D_
var degrees = 0;_x000D_
_x000D_
function start(){_x000D_
    runner = setInterval(function(){_x000D_
        degrees++;_x000D_
        rocket.style.webkitTransform = 'rotate(' + degrees + 'deg)';_x000D_
    },50)_x000D_
}_x000D_
_x000D_
function stop(){_x000D_
    clearInterval(runner);_x000D_
}_x000D_
_x000D_
btn.addEventListener('click', function(){_x000D_
    if (!rotate){_x000D_
        rotate = true;_x000D_
        start();_x000D_
    } else {_x000D_
        rotate = false;_x000D_
        stop();_x000D_
    }_x000D_
})
_x000D_
body {_x000D_
  background: #1e1e1e;_x000D_
}    _x000D_
_x000D_
.rocket {_x000D_
    width: 150px;_x000D_
    height: 150px;_x000D_
    margin: 1em;_x000D_
    border: 3px dashed teal;_x000D_
    border-radius: 50%;_x000D_
    background-color: rgba(128,128,128,0.5);_x000D_
    display: flex;_x000D_
    justify-content: center;_x000D_
    align-items: center;_x000D_
  }_x000D_
  _x000D_
  .rocket h1 {_x000D_
    margin: 0;_x000D_
    padding: 0;_x000D_
    font-size: .8em;_x000D_
    color: skyblue;_x000D_
    letter-spacing: 1em;_x000D_
    text-shadow: 0 0 10px black;_x000D_
  }_x000D_
  _x000D_
  .toggle {_x000D_
    margin: 10px;_x000D_
    background: #000;_x000D_
    color: white;_x000D_
    font-size: 1em;_x000D_
    padding: .3em;_x000D_
    border: 2px solid red;_x000D_
    outline: none;_x000D_
    letter-spacing: 3px;_x000D_
  }
_x000D_
<div class="rocket"><h1>SPIN ME</h1></div>_x000D_
<button class="toggle">I/0</button>
_x000D_
_x000D_
_x000D_

How to make a JTable non-editable

If you are creating the TableModel automatically from a set of values (with "new JTable(Vector, Vector)"), perhaps it is easier to remove editors from columns:

JTable table = new JTable(my_rows, my_header);

for (int c = 0; c < table.getColumnCount(); c++)
{
    Class<?> col_class = table.getColumnClass(c);
    table.setDefaultEditor(col_class, null);        // remove editor
}

Without editors, data will be not editable.

DataTable: How to get item value with row name and column name? (VB)

For i = 0 To dt.Rows.Count - 1

    ListV.Items.Add(dt.Rows(i).Item("STU_NUMBER").ToString)
    ListV.Items(i).SubItems.Add(dt.Rows(i).Item("FNAME").ToString & " " & dt.Rows(i).Item("MI").ToString & ". " & dt.Rows(i).Item("LNAME").ToString)
    ListV.Items(i).SubItems.Add(dt.Rows(i).Item("SEX").ToString)

Next

Hibernate table not mapped error in HQL query

In addition to the accepted answer, one other check is to make sure that you have the right reference to your entity package in sessionFactory.setPackagesToScan(...) while setting up your session factory.

C# Example of AES256 encryption using System.Security.Cryptography.Aes

Maybe this example listed here can help you out. Statement from the author

about 24 lines of code to encrypt, 23 to decrypt

Due to the fact that the link in the original posting is dead - here the needed code parts (c&p without any change to the original source)

  /*
  Copyright (c) 2010 <a href="http://www.gutgames.com">James Craig</a>
  
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
  
  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.
  
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  THE SOFTWARE.*/
   
  #region Usings
  using System;
  using System.IO;
  using System.Security.Cryptography;
  using System.Text;
  #endregion
   
  namespace Utilities.Encryption
  {
      /// <summary>
      /// Utility class that handles encryption
      /// </summary>
      public static class AESEncryption
      {
          #region Static Functions
   
          /// <summary>
          /// Encrypts a string
          /// </summary>
          /// <param name="PlainText">Text to be encrypted</param>
          /// <param name="Password">Password to encrypt with</param>
          /// <param name="Salt">Salt to encrypt with</param>
          /// <param name="HashAlgorithm">Can be either SHA1 or MD5</param>
          /// <param name="PasswordIterations">Number of iterations to do</param>
          /// <param name="InitialVector">Needs to be 16 ASCII characters long</param>
          /// <param name="KeySize">Can be 128, 192, or 256</param>
          /// <returns>An encrypted string</returns>
          public static string Encrypt(string PlainText, string Password,
              string Salt = "Kosher", string HashAlgorithm = "SHA1",
              int PasswordIterations = 2, string InitialVector = "OFRna73m*aze01xY",
              int KeySize = 256)
          {
              if (string.IsNullOrEmpty(PlainText))
                  return "";
              byte[] InitialVectorBytes = Encoding.ASCII.GetBytes(InitialVector);
              byte[] SaltValueBytes = Encoding.ASCII.GetBytes(Salt);
              byte[] PlainTextBytes = Encoding.UTF8.GetBytes(PlainText);
              PasswordDeriveBytes DerivedPassword = new PasswordDeriveBytes(Password, SaltValueBytes, HashAlgorithm, PasswordIterations);
              byte[] KeyBytes = DerivedPassword.GetBytes(KeySize / 8);
              RijndaelManaged SymmetricKey = new RijndaelManaged();
              SymmetricKey.Mode = CipherMode.CBC;
              byte[] CipherTextBytes = null;
              using (ICryptoTransform Encryptor = SymmetricKey.CreateEncryptor(KeyBytes, InitialVectorBytes))
              {
                  using (MemoryStream MemStream = new MemoryStream())
                  {
                      using (CryptoStream CryptoStream = new CryptoStream(MemStream, Encryptor, CryptoStreamMode.Write))
                      {
                          CryptoStream.Write(PlainTextBytes, 0, PlainTextBytes.Length);
                          CryptoStream.FlushFinalBlock();
                          CipherTextBytes = MemStream.ToArray();
                          MemStream.Close();
                          CryptoStream.Close();
                      }
                  }
              }
              SymmetricKey.Clear();
              return Convert.ToBase64String(CipherTextBytes);
          }
   
          /// <summary>
          /// Decrypts a string
          /// </summary>
          /// <param name="CipherText">Text to be decrypted</param>
          /// <param name="Password">Password to decrypt with</param>
          /// <param name="Salt">Salt to decrypt with</param>
          /// <param name="HashAlgorithm">Can be either SHA1 or MD5</param>
          /// <param name="PasswordIterations">Number of iterations to do</param>
          /// <param name="InitialVector">Needs to be 16 ASCII characters long</param>
          /// <param name="KeySize">Can be 128, 192, or 256</param>
          /// <returns>A decrypted string</returns>
          public static string Decrypt(string CipherText, string Password,
              string Salt = "Kosher", string HashAlgorithm = "SHA1",
              int PasswordIterations = 2, string InitialVector = "OFRna73m*aze01xY",
              int KeySize = 256)
          {
              if (string.IsNullOrEmpty(CipherText))
                  return "";
              byte[] InitialVectorBytes = Encoding.ASCII.GetBytes(InitialVector);
              byte[] SaltValueBytes = Encoding.ASCII.GetBytes(Salt);
              byte[] CipherTextBytes = Convert.FromBase64String(CipherText);
              PasswordDeriveBytes DerivedPassword = new PasswordDeriveBytes(Password, SaltValueBytes, HashAlgorithm, PasswordIterations);
              byte[] KeyBytes = DerivedPassword.GetBytes(KeySize / 8);
              RijndaelManaged SymmetricKey = new RijndaelManaged();
              SymmetricKey.Mode = CipherMode.CBC;
              byte[] PlainTextBytes = new byte[CipherTextBytes.Length];
              int ByteCount = 0;
              using (ICryptoTransform Decryptor = SymmetricKey.CreateDecryptor(KeyBytes, InitialVectorBytes))
              {
                  using (MemoryStream MemStream = new MemoryStream(CipherTextBytes))
                  {
                      using (CryptoStream CryptoStream = new CryptoStream(MemStream, Decryptor, CryptoStreamMode.Read))
                      {
   
                          ByteCount = CryptoStream.Read(PlainTextBytes, 0, PlainTextBytes.Length);
                          MemStream.Close();
                          CryptoStream.Close();
                      }
                  }
              }
              SymmetricKey.Clear();
              return Encoding.UTF8.GetString(PlainTextBytes, 0, ByteCount);
          }
   
          #endregion
      }
  }

awk - concatenate two string variable and assign to a third

Just use var = var1 var2 and it will automatically concatenate the vars var1 and var2:

awk '{new_var=$1$2; print new_var}' file

You can put an space in between with:

awk '{new_var=$1" "$2; print new_var}' file

Which in fact is the same as using FS, because it defaults to the space:

awk '{new_var=$1 FS $2; print new_var}' file

Test

$ cat file
hello how are you
i am fine
$ awk '{new_var=$1$2; print new_var}' file
hellohow
iam
$ awk '{new_var=$1 FS $2; print new_var}' file
hello how
i am

You can play around with it in ideone: http://ideone.com/4u2Aip

warning: incompatible implicit declaration of built-in function ‘xyz’

I met these warnings on mempcpy function. Man page says this function is a GNU extension and synopsis shows:

#define _GNU_SOURCE
#include <string.h>

When #define is added to my source before the #include, declarations for the GNU extensions are made visible and warnings disappear.

Named placeholders in string formatting

For very simple cases you can simply use a hardcoded String replace, no need for a library there:

    String url = "There's an incorrect value '%(value)' in column # %(column)";
    url = url.replace("%(value)", x); // 1
    url = url.replace("%(column)", y); // 2

WARNING: I just wanted to show the simplest code possible. Of course DO NOT use this for serious production code where security matters, as stated in the comments: escaping, error handling and security are an issue here. But in the worst case you now know why using a 'good' lib is required :-)

What is the difference between ApplicationContext and WebApplicationContext in Spring MVC?

Web Application context extended Application Context which is designed to work with the standard javax.servlet.ServletContext so it's able to communicate with the container.

public interface WebApplicationContext extends ApplicationContext {
    ServletContext getServletContext();
}

Beans, instantiated in WebApplicationContext will also be able to use ServletContext if they implement ServletContextAware interface

package org.springframework.web.context;
public interface ServletContextAware extends Aware { 
     void setServletContext(ServletContext servletContext);
}

There are many things possible to do with the ServletContext instance, for example accessing WEB-INF resources(xml configs and etc.) by calling the getResourceAsStream() method. Typically all application contexts defined in web.xml in a servlet Spring application are Web Application contexts, this goes both to the root webapp context and the servlet's app context.

Also, depending on web application context capabilities may make your application a little harder to test, and you may need to use MockServletContext class for testing.

Difference between servlet and root context Spring allows you to build multilevel application context hierarchies, so the required bean will be fetched from the parent context if it's not present in the current application context. In web apps as default there are two hierarchy levels, root and servlet contexts: Servlet and root context.

This allows you to run some services as the singletons for the entire application (Spring Security beans and basic database access services typically reside here) and another as separated services in the corresponding servlets to avoid name clashes between beans. For example one servlet context will be serving the web pages and another will be implementing a stateless web service.

This two level separation comes out of the box when you use the spring servlet classes: to configure the root application context you should use context-param tag in your web.xml

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>
        /WEB-INF/root-context.xml
            /WEB-INF/applicationContext-security.xml
    </param-value>
</context-param>

(the root application context is created by ContextLoaderListener which is declared in web.xml

<listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener> 

) and servlet tag for the servlet application contexts

<servlet>
   <servlet-name>myservlet</servlet-name>
   <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
   <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>app-servlet.xml</param-value>
   </init-param>
</servlet>

Please note that if init-param will be omitted, then spring will use myservlet-servlet.xml in this example.

See also: Difference between applicationContext.xml and spring-servlet.xml in Spring Framework

Perform Button click event when user press Enter key in Textbox

You can do it with javascript/jquery:

<script>
    function runScript(e) {
        if (e.keyCode == 13) {
            $("#myButton").click(); //jquery
            document.getElementById("myButton").click(); //javascript
        }
    }
</script>

<asp:textbox id="txtUsername" runat="server" onkeypress="return runScript(event)" />

<asp:LinkButton id="myButton" text="Login" runat="server" />

How to select current date in Hive SQL

select from_unixtime(unix_timestamp(current_date, 'yyyyMMdd'),'yyyy-MM-dd');

current_date - current date

yyyyMMdd - my systems current date format;

yyyy-MM-dd - if you wish to change the format to a diff one.

Convert negative data into positive data in SQL Server

The best solution is: from positive to negative or from negative to positive

For negative:

SELECT ABS(a) * -1 AS AbsoluteA, ABS(b) * -1 AS AbsoluteB
FROM YourTable

For positive:

SELECT ABS(a) AS AbsoluteA, ABS(b)  AS AbsoluteB
FROM YourTable

How to empty the content of a div

If you're using jQuery ...

$('div').html('');

or

$('div').empty();

Bootstrap 3 Glyphicons are not working

If you for example want the icon of glyphicon-chevron-left

Try adding class="glyphicon glyphicon-chevron-left"

What is the simplest C# function to parse a JSON string into an object?

You should create a structure that represents JSON keys (in case if you exactly know it) and then you can easily deserialize JSON string into your structure. In my examle I've deserialized a response from Google Cloud Message server:

class templateResponse
{
    public String multicast_id;
    public String success;
    public String failure;
    public String canonical_ids;
    public Result[] results;

    public class Result
    {
        public String message_id;
        public String registration_id;
        public String error;
    };
}

incoming JSON was:

"\"multicast_id\":7400896764380883211,\"success\":1,\"failure\":0,\"canonical_ids\":0,\"results\":[{\"message_id\":\"0:1351777805148960%39895cf0f9fd7ecd\"}]}"

So, use

templateResponse result = new JavaScriptSerializer().Deserialize<templateResponse>(json);

and you will get deserialized result object

How do I create a right click context menu in Java Swing?

This question is a bit old - as are the answers (and the tutorial as well)

The current api for setting a popupMenu in Swing is

myComponent.setComponentPopupMenu(myPopupMenu);

This way it will be shown automagically, both for mouse and keyboard triggers (the latter depends on LAF). Plus, it supports re-using the same popup across a container's children. To enable that feature:

myChild.setInheritsPopupMenu(true);

Starting the week on Monday with isoWeekday()

For those who want isoWeek to be the default you can modify moment's behaviour as such:

const moment = require('moment');
const proto = Object.getPrototypeOf(moment());

const {startOf, endOf} = proto;
proto.startOf = function(period) {
  if (period === 'week') {
    period = 'isoWeek';
  }
  return startOf.call(this, period);
};
proto.endOf = function(period) {
  if (period === 'week') {
    period = 'isoWeek';
  }
  return endOf.call(this, period);
};

Now you can simply use someDate.startOf('week') without worrying you'll get sunday or having to think about whether to use isoweek or isoWeek etc.

Plus you can store this in a variable like const period = 'week' and use it safely in subtract() or add() operations, e.g. moment().subtract(1, period).startOf(period);. This won't work with period being isoWeek.

How can I scroll a div to be visible in ReactJS?

In you keyup/down handler you just need to set the scrollTop property of the div you want to scroll to make it scroll down (or up).

For example:

JSX:

<div ref="foo">{content}</div>

keyup/down handler:

this.refs.foo.getDOMNode().scrollTop += 10

If you do something similar to above, your div will scroll down 10 pixels (assuming the div is set to overflow auto or scroll in css, and your content is overflowing of course).

You will need to expand on this to find the offset of the element inside your scrolling div that you want to scroll the div down to, and then modify the scrollTop to scroll far enough to show the element based on it's height.

Have a look at MDN's definitions of scrollTop, and offsetTop here:

https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollTop

https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/offsetTop

How to change button background image on mouseOver?

In the case of winforms:

If you include the images to your resources you can do it like this, very simple and straight forward:

public Form1()
          {
               InitializeComponent();
               button1.MouseEnter += new EventHandler(button1_MouseEnter);
               button1.MouseLeave += new EventHandler(button1_MouseLeave);
          }

          void button1_MouseLeave(object sender, EventArgs e)
          {
               this.button1.BackgroundImage = ((System.Drawing.Image)(Properties.Resources.img1));
          }


          void button1_MouseEnter(object sender, EventArgs e)
          {
               this.button1.BackgroundImage = ((System.Drawing.Image)(Properties.Resources.img2));
          }

I would not recommend hardcoding image paths.

As you have altered your question ...

There is no (on)MouseOver in winforms afaik, there are MouseHover and MouseMove events, but if you change image on those, it will not change back, so the MouseEnter + MouseLeave are what you are looking for I think. Anyway, changing the image on Hover or Move :

in the constructor:
button1.MouseHover += new EventHandler(button1_MouseHover); 
button1.MouseMove += new MouseEventHandler(button1_MouseMove);

void button1_MouseMove(object sender, MouseEventArgs e)
          {
               this.button1.BackgroundImage = ((System.Drawing.Image)(Properties.Resources.img2));
          }

          void button1_MouseHover(object sender, EventArgs e)
          {
               this.button1.BackgroundImage = ((System.Drawing.Image)(Properties.Resources.img2));
          }

To add images to your resources: Projectproperties/resources/add/existing file

How to save a Python interactive session?

I'd like to suggest another way to maintain python session through tmux on linux. you run tmux, attach your self to the session you opened (if not attached after opening it directly). execute python and do whatever you are doing on it. then detach from session. detaching from a tmux session does not close the session. the session remains open.

pros of this method: you can attach to this session from any other device (in case you can ssh your pc)

cons of this method: this method does not relinquish the resources used by the opened python session until you actually exist the python interpreter.

What does if [ $? -eq 0 ] mean for shell scripts?

It's checking the return value ($?) of grep. In this case it's comparing it to 0 (success).

Usually when you see something like this (checking the return value of grep) it's checking to see whether the particular string was detected. Although the redirect to /dev/null isn't necessary, the same thing can be accomplished using -q.

How to implement debounce in Vue2?

If you are using Vue you can also use v.model.lazy instead of debounce but remember v.model.lazy will not always work as Vue limits it for custom components.

For custom components you should use :value along with @change.native

<b-input :value="data" @change.native="data = $event.target.value" ></b-input>

Specifying row names when reading in a file

If you used read.table() (or one of it's ilk, e.g. read.csv()) then the easy fix is to change the call to:

read.table(file = "foo.txt", row.names = 1, ....)

where .... are the other arguments you needed/used. The row.names argument takes the column number of the data file from which to take the row names. It need not be the first column. See ?read.table for details/info.

If you already have the data in R and can't be bothered to re-read it, or it came from another route, just set the rownames attribute and remove the first variable from the object (assuming obj is your object)

rownames(obj) <- obj[, 1]  ## set rownames
obj <- obj[, -1]           ## remove the first variable

What's the best way to store Phone number in Django models

It all depends in what you understand as phone number. Phone numbers are country specific. The localflavors packages for several countries contains their own "phone number field". So if you are ok being country specific you should take a look at localflavor package (class us.models.PhoneNumberField for US case, etc.)

Otherwise you could inspect the localflavors to get the maximun lenght for all countries. Localflavor also has forms fields you could use in conjunction with the country code to validate the phone number.

How to draw a checkmark / tick using CSS?

i like this way because you don't need to create two components just one.

.checkmark:after {
    opacity: 1;
    height: 4em;
    width: 2em;
    -webkit-transform-origin: left top;
    transform-origin: left top;
    border-right: 2px solid #5cb85c;
    border-top: 2px solid #5cb85c;
    content: '';
    left: 2em;
    top: 4em;
    position: absolute;
}

Animation from Scott Galloway Pen

Remove scrollbars from textarea

Try the following, not sure which will work for all browsers or the browser you are working with, but it would be best to try all:

<textarea style="overflow:auto"></textarea>

Or

<textarea style="overflow:hidden"></textarea>

...As suggested above

You can also try adding this, I never used it before, just saw it posted on a site today:

<textarea style="resize:none"></textarea>

This last option would remove the ability to resize the textarea. You can find more information on the CSS resize property here

How to Add a Dotted Underline Beneath HTML Text

It's not impossible without CSS. For example as a list item:

<li style="border-bottom: 1px dashed"><!--content --></li>

Read only file system on Android

If there's a failure in copying the read-only file you can try locating the original file in the root directory and modify it with a root text editor (preferably) RB text editor, it comes with ROM Toolbox app.

Python Pandas: Get index of rows which column matches certain value

First you may check query when the target column is type bool (PS: about how to use it please check link )

df.query('BoolCol')
Out[123]: 
    BoolCol
10     True
40     True
50     True

After we filter the original df by the Boolean column we can pick the index .

df=df.query('BoolCol')
df.index
Out[125]: Int64Index([10, 40, 50], dtype='int64')

Also pandas have nonzero, we just select the position of True row and using it slice the DataFrame or index

df.index[df.BoolCol.nonzero()[0]]
Out[128]: Int64Index([10, 40, 50], dtype='int64')

MySQL - SELECT WHERE field IN (subquery) - Extremely slow why?

sometimes when data grow bigger mysql WHERE IN's could be pretty slow because of query optimization. Try using STRAIGHT_JOIN to tell mysql to execute query as is, e.g.

SELECT STRAIGHT_JOIN table.field FROM table WHERE table.id IN (...)

but beware: in most cases mysql optimizer works pretty well, so I would recommend to use it only when you have this kind of problem

add new element in laravel collection object

If you want to add a product into the array you can use:

$item['product'] = $product;

How to create table using select query in SQL Server?

An example statement that uses a sub-select :

select * into MyNewTable
from
(
select 
  * 
from 
[SomeOtherTablename]
where 
  EventStartDatetime >= '01/JAN/2018' 
)
) mysourcedata
;

note that the sub query must be given a name .. any name .. e.g. above example gives the subquery a name of mysourcedata. Without this a syntax error is issued in SQL*server 2012.

The database should reply with a message like: (9999 row(s) affected)

How do I set up IntelliJ IDEA for Android applications?

I've spent a day on trying to put all the pieces together, been in hundreds of sites and tutorials, but they all skip trivial steps.

So here's the full guide:

  1. Download and install Java JDK (Choose the Java platform)
  2. Download and install Android SDK (Installer is recommended)
  3. After android SD finishes installing, open SDK Manager under Android SDK Tools (sometimes needs to be opened under admin's privileges)
  4. Choose everything and mark Accept All and install.
  5. Download and install IntelliJ IDEA (The community edition is free)
  6. Wait for all downloads and installations and stuff to finish.

New Project:

  1. Run IntelliJ
  2. Create a new project (there's a tutorial here)
  3. Enter the name, choose Android type.
  4. There's a step missing in the tutorial, when you are asked to choose the JDK (before choosing the SDK) you need to choose the Java JDK you've installed earlier. Should be under C:\Program Files\Java\jdk{version}
  5. Choose a New platform ( if there's not one selected ) , the SDK platform is the android platform at C:\Program Files\Android\android-sdk-windows.
  6. Choose the android version.
  7. Now you can write your program.

Compiling:

  1. Near the Run button you need to select the drop-down-list, choose Edit Configurations
  2. In the Prefer Android Virtual device select the ... button
  3. Click on create, give it a name, press OK.
  4. Double click the new device to choose it.
  5. Press OK.
  6. You're ready to run the program.

Cannot find reference 'xxx' in __init__.py - Python / Pycharm

This is a bug in pycharm. PyCharm seems to be expecting the referenced module to be included in an __all__ = [] statement.

For proper coding etiquette, should you include the __all__ statement from your modules? ..this is actually the question we hear young Spock answering while he was being tested, to which he responded: "It is morally praiseworthy but not morally obligatory."

To get around it, you can simply disable that (extremely non-critical) (highly useful) inspection globally, or suppress it for the specific function or statement.

To do so:

  • put the caret over the erroring text ('choice', from your example above)
  • Bring up the intention menu (alt-enter by default, mine is set to alt-backspace)
  • hit the right arrow to open the submenu, and select the relevant action

PyCharm has its share of small bugs like this, but in my opinion its benefits far outweigh its drawbacks. If you'd like to try another good IDE, there's also Spyder/Spyderlib.

I know this is quite a bit after you asked your question, but I hope this helps (you, or someone else).

Edited: Originally, I thought that this was specific to checking __all__, but it looks like it's the more general 'Unresolved References' check, which can be very useful. It's probably best to use statement-level disabling of the feature, either by using the menu as mentioned above, or by specifying # noinspection PyUnresolvedReferences on the line preceding the statement.

iPhone 6 Plus resolution confusion: Xcode or Apple's website? for development

On the physical device, iPhone 6 Plus's main screen's bounds is 2208x1242 and nativeBounds is 1920x1080. There is hardware scaling involved to resize to the physical display.

On the simulator, the iPhone 6 Plus's main screen's bounds and nativeBounds are both 2208x1242.

In other words... Videos, OpenGL, and other things based on CALayers that deal with pixels will deal with the real 1920x1080 frame buffer on device (or 2208x1242 on sim). Things dealing with points in UIKit will be deal with the 2208x1242 (x3) bounds and get scaled as appropriate on device.

The simulator does not have access to the same hardware that is doing the scaling on device and there's not really much of a benefit to simulating it in software as they'd produce different results than the hardware. Thus it makes sense to set the nativeBounds of a simulated device's main screen to the bounds of the physical device's main screen.

iOS 8 added API to UIScreen (nativeScale and nativeBounds) to let a developer determine the resolution of the CADisplay corresponding to the UIScreen.

Generating Random Passwords

public static string GeneratePassword(int passLength) {
        var chars = "abcdefghijklmnopqrstuvwxyz@#$&ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        var random = new Random();
        var result = new string(
            Enumerable.Repeat(chars, passLength)
                      .Select(s => s[random.Next(s.Length)])
                      .ToArray());
        return result;
    }

javascript pushing element at the beginning of an array

Use unshift, which modifies the existing array by adding the arguments to the beginning:

TheArray.unshift(TheNewObject);

When to use CouchDB over MongoDB and vice versa

Ask this questions yourself? And you will decide your DB selection.

  1. Do you need master-master? Then CouchDB. Mainly CouchDB supports master-master replication which anticipates nodes being disconnected for long periods of time. MongoDB would not do well in that environment.
  2. Do you need MAXIMUM R/W throughput? Then MongoDB
  3. Do you need ultimate single-server durability because you are only going to have a single DB server? Then CouchDB.
  4. Are you storing a MASSIVE data set that needs sharding while maintaining insane throughput? Then MongoDB.
  5. Do you need strong consistency of data? Then MongoDB.
  6. Do you need high availability of database? Then CouchDB.
  7. Are you hoping multi databases and multi tables/ collections? Then MongoDB
  8. You have a mobile app offline users and want to sync their activity data to a server? Then you need CouchDB.
  9. Do you need large variety of querying engine? Then MongoDB
  10. Do you need large community to be using DB? Then MongoDB

Initialising mock objects - MockIto

A little example for JUnit 5 Jupiter, the "RunWith" was removed you now need to use the Extensions using the "@ExtendWith" Annotation.

@ExtendWith(MockitoExtension.class)
class FooTest {

  @InjectMocks
  ClassUnderTest test = new ClassUnderTest();

  @Spy
  SomeInject bla = new SomeInject();
}

Best way to check if MySQL results returned in PHP?

if (mysql_num_rows($result)==0) { PERFORM ACTION }

For PHP 5 and 7 and above use mysqli:

if (mysqli_num_rows($result)==0) { PERFORM ACTION }

This gets my vote.

OP assuming query is not returning any error, so this should be one of the way

How do I create a new branch?

Branches in SVN are essentially directories; you don't name the branch so much as choose the name of the directory to branch into.

The common way of 'naming' a branch is to place it under a directory called branches in your repository. In the "To URL:" portion of TortoiseSVN's Branch dialog, you would therefore enter something like:

(svn/http)://path-to-repo/branches/your-branch-name

The main branch of a project is referred to as the trunk, and is usually located in:

(svn/http)://path-to-repo/trunk

ASP.NET MVC Html.ValidationSummary(true) does not display model errors

You can try,

<div asp-validation-summary="All" class="text-danger"></div>

UIView frame, bounds and center

Since the question I asked has been seen many times I will provide a detailed answer of it. Feel free to modify it if you want to add more correct content.

First a recap on the question: frame, bounds and center and theirs relationships.

Frame A view's frame (CGRect) is the position of its rectangle in the superview's coordinate system. By default it starts at the top left.

Bounds A view's bounds (CGRect) expresses a view rectangle in its own coordinate system.

Center A center is a CGPoint expressed in terms of the superview's coordinate system and it determines the position of the exact center point of the view.

Taken from UIView + position these are the relationships (they don't work in code since they are informal equations) among the previous properties:

  • frame.origin = center - (bounds.size / 2.0)

  • center = frame.origin + (bounds.size / 2.0)

  • frame.size = bounds.size

NOTE: These relationships do not apply if views are rotated. For further info, I will suggest you take a look at the following image taken from The Kitchen Drawer based on Stanford CS193p course. Credits goes to @Rhubarb.

Frame, bounds and center

Using the frame allows you to reposition and/or resize a view within its superview. Usually can be used from a superview, for example, when you create a specific subview. For example:

// view1 will be positioned at x = 30, y = 20 starting the top left corner of [self view]
// [self view] could be the view managed by a UIViewController
UIView* view1 = [[UIView alloc] initWithFrame:CGRectMake(30.0f, 20.0f, 400.0f, 400.0f)];    
view1.backgroundColor = [UIColor redColor];

[[self view] addSubview:view1];

When you need the coordinates to drawing inside a view you usually refer to bounds. A typical example could be to draw within a view a subview as an inset of the first. Drawing the subview requires to know the bounds of the superview. For example:

UIView* view1 = [[UIView alloc] initWithFrame:CGRectMake(50.0f, 50.0f, 400.0f, 400.0f)];    
view1.backgroundColor = [UIColor redColor];

UIView* view2 = [[UIView alloc] initWithFrame:CGRectInset(view1.bounds, 20.0f, 20.0f)];    
view2.backgroundColor = [UIColor yellowColor];

[view1 addSubview:view2];

Different behaviours happen when you change the bounds of a view. For example, if you change the bounds size, the frame changes (and vice versa). The change happens around the center of the view. Use the code below and see what happens:

NSLog(@"Old Frame %@", NSStringFromCGRect(view2.frame));
NSLog(@"Old Center %@", NSStringFromCGPoint(view2.center));    

CGRect frame = view2.bounds;
frame.size.height += 20.0f;
frame.size.width += 20.0f;
view2.bounds = frame;

NSLog(@"New Frame %@", NSStringFromCGRect(view2.frame));
NSLog(@"New Center %@", NSStringFromCGPoint(view2.center));

Furthermore, if you change bounds origin you change the origin of its internal coordinate system. By default the origin is at (0.0, 0.0) (top left corner). For example, if you change the origin for view1 you can see (comment the previous code if you want) that now the top left corner for view2 touches the view1 one. The motivation is quite simple. You say to view1 that its top left corner now is at the position (20.0, 20.0) but since view2's frame origin starts from (20.0, 20.0), they will coincide.

CGRect frame = view1.bounds;
frame.origin.x += 20.0f;
frame.origin.y += 20.0f;
view1.bounds = frame; 

The origin represents the view's position within its superview but describes the position of the bounds center.

Finally, bounds and origin are not related concepts. Both allow to derive the frame of a view (See previous equations).

View1's case study

Here is what happens when using the following snippet.

UIView* view1 = [[UIView alloc] initWithFrame:CGRectMake(30.0f, 20.0f, 400.0f, 400.0f)];
view1.backgroundColor = [UIColor redColor];

[[self view] addSubview:view1];

NSLog(@"view1's frame is: %@", NSStringFromCGRect([view1 frame]));
NSLog(@"view1's bounds is: %@", NSStringFromCGRect([view1 bounds]));
NSLog(@"view1's center is: %@", NSStringFromCGPoint([view1 center]));

The relative image.

enter image description here

This instead what happens if I change [self view] bounds like the following.

// previous code here...
CGRect rect = [[self view] bounds];
rect.origin.x += 30.0f;
rect.origin.y += 20.0f;
[[self view] setBounds:rect];

The relative image.

enter image description here

Here you say to [self view] that its top left corner now is at the position (30.0, 20.0) but since view1's frame origin starts from (30.0, 20.0), they will coincide.

Additional references (to update with other references if you want)

About clipsToBounds (source Apple doc)

Setting this value to YES causes subviews to be clipped to the bounds of the receiver. If set to NO, subviews whose frames extend beyond the visible bounds of the receiver are not clipped. The default value is NO.

In other words, if a view's frame is (0, 0, 100, 100) and its subview is (90, 90, 30, 30), you will see only a part of that subview. The latter won't exceed the bounds of the parent view.

masksToBounds is equivalent to clipsToBounds. Instead to a UIView, this property is applied to a CALayer. Under the hood, clipsToBounds calls masksToBounds. For further references take a look to How is the relation between UIView's clipsToBounds and CALayer's masksToBounds?.

How to top, left justify text in a <td> cell that spans multiple rows

td[rowspan] {
  vertical-align: top;
  text-align: left;
}

See: CSS attribute selectors.

What is the correct SQL type to store a .Net Timespan with values > 24:00:00?

To be consistent with what is probably the most likely source of generating a time span (computing the difference of 2 times or date-times), you may want to store a .NET TimeSpan as a SQL Server DateTime Type.

This is because in SQL Server, the difference of 2 DateTime's (Cast to Float's and then Cast back to a DateTime) is simply a DateTime relative to Jan. 1, 1900. Ex. A difference of +0.1 second would be January 1, 1900 00:00:00.100 and -0.1 second would be Dec. 31, 1899 23:59:59.900.

To convert a .NET TimeSpan to a SQL Server DateTime Type, you would first convert it to a .NET DateTime Type by adding it to a DateTime of Jan. 1, 1900. Of course, when you read it into .NET from SQL Server, you would first read it into a .NET DateTime and then subtract Jan. 1, 1900 from it to convert it to a .NET TimeSpan.

For use cases where the time spans are being generated from SQL Server DateTime's and within SQL Server (i.e. via T-SQL) and SQL Server is prior to 2016, depending on your range and precision needs, it may not be practical to store them as milliseconds (not to mention Ticks) because the Int Type returned by DateDiff (vs. the BigInt from SS 2016+'s DateDiff_Big) overflows after ~24 days worth of milliseconds and ~67 yrs. of seconds. Whereas, this solution will handle time spans with precision down to 0.1 seconds and from -147 to +8,099 yrs..

WARNINGS:

  1. This would only work if the difference relative to Jan. 1, 1900 would result in a value within the range of a SQL Server DateTime Type (Jan. 1, 1753 to Dec. 31, 9999 aka -147 to +8,099 yrs.). We don't have to worry near as much on the .NET TimeSpan side, since it can hold ~29 k to +29 k yrs. I didn't mention the SQL Server DateTime2 Type (whose range, on the negative side, is much greater than SQL Server DateTime's), because: a) it cannot be converted to a numeric via a simple Cast and b) DateTime's range should suffice for the vast majority of use cases.

  2. SQL Server DateTime differences computed via the Cast - to - Float - and - back method does not appear to be accurate beyond 0.1 seconds.

Export HTML table to pdf using jspdf

Use get(0) instead of html(). In other words, replace

doc.fromHTML($('#htmlTableId').html(), 15, 15, {
    'width': 170,'elementHandlers': specialElementHandlers
});

with

doc.fromHTML($('#htmlTableId').get(0), 15, 15, {
    'width': 170,'elementHandlers': specialElementHandlers
});

Best way to add Activity to an Android project in Eclipse?

An easy method suggested by Google Android Developer Community.

enter image description here

How to concatenate two strings in SQL Server 2005

so if you have a table with a row like:

firstname lastname
Bill      smith

you can do something like

select firstname + ' ' + lastname from thetable

and you will get "Bill Smith"

Query-string encoding of a Javascript Object

Well, everyone seems to put his one-liner here so here goes mine:

const encoded = Object.entries(obj).map(([k, v]) => `${k}=${encodeURIComponent(v)}`).join("&");

Why maven? What are the benefits?

Maven is one of the tools where you need to actually decide up front that you like it and want to use it, since you will spend quite some time learning it, and having made said decision once and for all will allow you to skip all kinds of doubt while learning (because you like it and want to use it)!

The strong conventions help in many places - like Hudson that can do wonders with Maven projects - but it may be hard to see initially.

edit: As of 2016 Maven is the only Java build tool where all three major IDEs can use the sources out of the box. In other words, using maven makes your build IDE-agnostic. This allows for e.g. using Netbeans profiling even if you normally work In eclipse

Best way to define error codes/strings in Java?

Just to keep flogging this particular dead horse- we've had good use of numeric error codes when errors are shown to end-customers, since they frequently forget or misread the actual error message but may sometimes retain and report a numeric value that can give you a clue to what actually happened.

python : list index out of range error while iteratively popping elements

I think the best way to solve this problem is:

l = [1, 2, 3, 0, 0, 1]
while 0 in l:
    l.remove(0)

Instead of iterating over list I remove 0 until there aren't any 0 in list

How can I get an int from stdio in C?

The typical way is with scanf:

int input_value;

scanf("%d", &input_value);

In most cases, however, you want to check whether your attempt at reading input succeeded. scanf returns the number of items it successfully converted, so you typically want to compare the return value against the number of items you expected to read. In this case you're expecting to read one item, so:

if (scanf("%d", &input_value) == 1)
    // it succeeded
else
    // it failed

Of course, the same is true of all the scanf family (sscanf, fscanf and so on).

jQuery won't parse my JSON from AJAX query

According to the json.org specification, your return is invalid. The names are always quoted, so you should be returning

{ "title": "One", "key": "1" }

and

[ { "title": "One", "key": "1" }, { "title": "Two", "key": "2" } ]

This may not be the problem with your setup, since you say one of them works now, but it should be fixed for correctness in case you need to switch to another JSON parser in the future.

Android Gallery on Android 4.4 (KitKat) returns different URI for Intent.ACTION_GET_CONTENT

Building up on Paul Burke's answer I faced many problems resolving external SD card's URI path as most of the suggested "built-in" functions return paths which do not get resolved to files.

However, this is my approach of his // TODO handle non-primary volumes.

String resolvedPath = "";
File[] possibleExtSdComposites = context.getExternalFilesDirs(null);
for (File f : possibleExtSdComposites) {
    // Reset final path
    resolvedPath = "";

    // Construct list of folders
    ArrayList<String> extSdSplit = new ArrayList<>(Arrays.asList(f.getPath().split("/")));

    // Look for folder "<your_application_id>"
    int idx = extSdSplit.indexOf(BuildConfig.APPLICATION_ID);

    // ASSUMPTION: Expected to be found at depth 2 (in this case ExtSdCard's root is /storage/0000-0000/) - e.g. /storage/0000-0000/Android/data/<your_application_id>/files
    ArrayList<String> hierarchyList = new ArrayList<>(extSdSplit.subList(0, idx - 2));

    // Construct list containing full possible path to the file
    hierarchyList.add(tail);
    String possibleFilePath = TextUtils.join("/", hierarchyList);

    // If file is found --> success
    if (idx != -1 && new File(possibleFilePath).exists()) {
        resolvedPath = possibleFilePath;
        break;
    }
}

if (!resolvedPath.equals("")) {
    return resolvedPath;
} else {
    return null;
}

Note it depends on hierarchy which might be different on every phone manufacturer - I have not tested them all (it worked well so far on Xperia Z3 API 23 and Samsung Galaxy A3 API 23).

Please confirm if it does not perform well elsewhere.

How do I insert values into a Map<K, V>?

The syntax is

data.put("John","Taxi driver");

How to fix nginx throws 400 bad request headers on any header testing tools?

A cause can be invalid encoding in the URL request. Such as % being passed un-encoded.

git: Switch branch and ignore any changes without committing

Note that if you've merged remote branches or have local commits and want to go back to the remote HEAD you must do:

git reset --hard origin/HEAD

HEAD alone will only refer to the local commit/merge -- several times I have forgotten that when resetting and end up with "your repository is X commits ahead.." when I fully intended to nuke ALL changes/commits and return to the remote branch.

Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 32 bytes)

128M == 134217728, the number you are seeing.

The memory limit is working fine. When it says it tried to allocate 32 bytes, that the amount requested by the last operation before failing.

Are you building any huge arrays or reading large text files? If so, remember to free any memory you don't need anymore, or break the task down into smaller steps.

How to consume REST in Java

From your question its not clear whether you are using any frameworks.For REST you will be getting an WADL & Apache CXF recently added support for WADL-first development of REST services.Please go through http://cxf.apache.org/docs/index.html

How do I append to a table in Lua

I'd personally make use of the table.insert function:

table.insert(a,"b");

This saves you from having to iterate over the whole table therefore saving valuable resources such as memory and time.

Switch between python 2.7 and python 3.5 on Mac OS X

I already had python3 installed(via miniconda3) and needed to install python2 alongside in that case brew install python won't install python2, so you would need brew install python@2 .

Now alias python2 refers to python2.x from /usr/bin/python

and alias python3 refers to python3.x from /Users/ishandutta2007/miniconda3/bin/python

and alias python refers to python3 by default.

Now to use python as alias for python2, I added the following to .bashrc file

alias python='/usr/bin/python'.

To go back to python3 as default just remove this line when required.

JavaScript OR (||) variable assignment explanation

It will evaluate X and, if X is not null, the empty string, or 0 (logical false), then it will assign it to z. If X is null, the empty string, or 0 (logical false), then it will assign y to z.

var x = '';
var y = 'bob';
var z = x || y;
alert(z);

Will output 'bob';

Date ticks and rotation in matplotlib

If you prefer a non-object-oriented approach, move plt.xticks(rotation=70) to right before the two avail_plot calls, eg

plt.xticks(rotation=70)
avail_plot(axs[0], dates, s1, 'testing', 'green')
avail_plot(axs[1], dates, s1, 'testing2', 'red')

This sets the rotation property before setting up the labels. Since you have two axes here, plt.xticks gets confused after you've made the two plots. At the point when plt.xticks doesn't do anything, plt.gca() does not give you the axes you want to modify, and so plt.xticks, which acts on the current axes, is not going to work.

For an object-oriented approach not using plt.xticks, you can use

plt.setp( axs[1].xaxis.get_majorticklabels(), rotation=70 )

after the two avail_plot calls. This sets the rotation on the correct axes specifically.

What is the difference between Double.parseDouble(String) and Double.valueOf(String)?

Documentation for parseDouble() says "Returns a new double initialized to the value represented by the specified String, as performed by the valueOf method of class Double.", so they should be identical.

Return list using select new in LINQ

You cannot return anonymous types from a class... (Well, you can, but you have to cast them to object first and then use reflection at the other side to get the data out again) so you have to create a small class for the data to be contained within.

class ProjectNameAndId
{
    public string Name { get; set; }
    public string Id { get; set; }
}

Then in your LINQ statement:

select new ProjectNameAndId { Name = pro.ProjectName, Id = pro.ProjectId };

Install numpy on python3.3 - Install pip for python3

From the terminal run:

  sudo apt-get install python3-numpy

This package contains Numpy for Python 3.

For scipy:

 sudo apt-get install python3-scipy

For for plotting graphs use pylab:

 sudo apt-get install python3-matplotlib

Wait for async task to finish

This will never work, because the JS VM has moved on from that async_call and returned the value, which you haven't set yet.

Don't try to fight what is natural and built-in the language behaviour. You should use a callback technique or a promise.

function f(input, callback) {
    var value;

    // Assume the async call always succeed
    async_call(input, function(result) { callback(result) };

}

The other option is to use a promise, have a look at Q. This way you return a promise, and then you attach a then listener to it, which is basically the same as a callback. When the promise resolves, the then will trigger.

How to merge two files line by line in Bash

here's non-paste methods

awk

awk 'BEGIN {OFS=" "}{
  getline line < "file2"
  print $0,line
} ' file1

Bash

exec 6<"file2"
while read -r line
do
    read -r f2line <&6
    echo "${line}${f2line}"
done <"file1"
exec 6<&-

How to find a hash key containing a matching value

You could use hashname.key(valuename)

Or, an inversion may be in order. new_hash = hashname.invert will give you a new_hash that lets you do things more traditionally.

How to create an array for JSON using PHP?

also for array you can use short annotattion:

$arr = [
    [
        "region" => "valore",
        "price" => "valore2"
    ],
    [
        "region" => "valore",
        "price" => "valore2"
    ],
    [
        "region" => "valore",
        "price" => "valore2"
    ]
];

echo json_encode($arr);

Port 443 in use by "Unable to open process" with PID 4

I got this same error and managed to fix it by closing Skype and running XAMP as Administrator, works perfectly now. So right click THE XAMP icon and click run as admin.

String comparison: InvariantCultureIgnoreCase vs OrdinalIgnoreCase?

If you really want to match only the dot, then StringComparison.Ordinal would be fastest, as there is no case-difference.

"Ordinal" doesn't use culture and/or casing rules that are not applicable anyway on a symbol like a ..

Table overflowing outside of div

overflow-x: auto;
overflow-y : hidden;

Apply the styling above to the parent div.

Unable to use Intellij with a generated sources folder

i ran mvn generate-resources and then marked the /target/generated-resources folder as "sources" (Project Structure -> Project Settings -> Modules -> Select /target/generated-resources -> Click on blue "Sources" icon.

Merge DLL into EXE?

Download ilmerge and ilmergre gui . makes joining the files so easy ive used these and works great

How to maximize a plt.show() window using Python

For Tk-based backend (TkAgg), these two options maximize & fullscreen the window:

plt.get_current_fig_manager().window.state('zoomed')
plt.get_current_fig_manager().window.attributes('-fullscreen', True)

When plotting into multiple windows, you need to write this for each window:

data = rasterio.open(filepath)

blue, green, red, nir = data.read()
plt.figure(1)
plt.subplot(121); plt.imshow(blue);
plt.subplot(122); plt.imshow(red);
plt.get_current_fig_manager().window.state('zoomed')

rgb = np.dstack((red, green, blue))
nrg = np.dstack((nir, red, green))
plt.figure(2)
plt.subplot(121); plt.imshow(rgb);
plt.subplot(122); plt.imshow(nrg);
plt.get_current_fig_manager().window.state('zoomed')

plt.show()

Here, both 'figures' are plotted in separate windows. Using a variable such as

figure_manager = plt.get_current_fig_manager()

might not maximize the second window, since the variable still refers to the first window.

java.lang.UnsupportedClassVersionError Unsupported major.minor version 51.0

java.lang.UnsupportedClassVersionError happens because of a higher JDK during compile time and lower JDK during runtime.

Here's the list of versions:

Java SE 9 = 53,
Java SE 8 = 52,
Java SE 7 = 51,
Java SE 6.0 = 50,
Java SE 5.0 = 49,
JDK 1.4 = 48,
JDK 1.3 = 47,
JDK 1.2 = 46,
JDK 1.1 = 45

Absolute position of an element on the screen using jQuery

BTW, if anyone want to get coordinates of element on screen without jQuery, please try this:

function getOffsetTop (el) {
    if (el.offsetParent) return el.offsetTop + getOffsetTop(el.offsetParent)
    return el.offsetTop || 0
}
function getOffsetLeft (el) {
    if (el.offsetParent) return el.offsetLeft + getOffsetLeft(el.offsetParent)
    return el.offsetleft || 0
}
function coordinates(el) {
    var y1 = getOffsetTop(el) - window.scrollY;
    var x1 = getOffsetLeft(el) - window.scrollX; 
    var y2 = y1 + el.offsetHeight;
    var x2 = x1 + el.offsetWidth;
    return {
        x1: x1, x2: x2, y1: y1, y2: y2
    }
}

what is the difference between OLE DB and ODBC data sources?

To know why M$ invents OLEDB, you can't compare OLEDB with ODBC. Instead, you should compare OLEDB with DAO,RDO, or ADO. The latter largely relies on SQL. However, OLEDB relies on COM. But ODBC is already there many years, so there's a OLEDB-ODBC bridges to remedy this. I think there's a big picture when M$ invents OLEDB.

Where's the DateTime 'Z' format specifier?

When you use DateTime you are able to store a date and a time inside a variable.

The date can be a local time or a UTC time, it depend on you.

For example, I'm in Italy (+2 UTC)

var dt1 = new DateTime(2011, 6, 27, 12, 0, 0); // store 2011-06-27 12:00:00
var dt2 = dt1.ToUniversalTime()  // store 2011-06-27 10:00:00

So, what happen when I print dt1 and dt2 including the timezone?

dt1.ToString("MM/dd/yyyy hh:mm:ss z") 
// Compiler alert...
// Output: 06/27/2011 12:00:00 +2

dt2.ToString("MM/dd/yyyy hh:mm:ss z") 
// Compiler alert...
// Output: 06/27/2011 10:00:00 +2

dt1 and dt2 contain only a date and a time information. dt1 and dt2 don't contain the timezone offset.

So where the "+2" come from if it's not contained in the dt1 and dt2 variable?

It come from your machine clock setting.

The compiler is telling you that when you use the 'zzz' format you are writing a string that combine "DATE + TIME" (that are store in dt1 and dt2) + "TIMEZONE OFFSET" (that is not contained in dt1 and dt2 because they are DateTyme type) and it will use the offset of the server machine that it's executing the code.

The compiler tell you "Warning: the output of your code is dependent on the machine clock offset"

If i run this code on a server that is positioned in London (+1 UTC) the result will be completly different: instead of "+2" it will write "+1"

...
dt1.ToString("MM/dd/yyyy hh:mm:ss z") 
// Output: 06/27/2011 12:00:00 +1

dt2.ToString("MM/dd/yyyy hh:mm:ss z") 
// Output: 06/27/2011 10:00:00 +1

The right solution is to use DateTimeOffset data type in place of DateTime. It's available in sql Server starting from the 2008 version and in the .Net framework starting from the 3.5 version

jQuery .on('change', function() {} not triggering for dynamically created inputs

You should provide a selector to the on function:

$(document).on('change', 'input', function() {
  // Does some stuff and logs the event to the console
});

In that case, it will work as you expected. Also, it is better to specify some element instead of document.

Read this article for better understanding: http://elijahmanor.com/differences-between-jquery-bind-vs-live-vs-delegate-vs-on/

Add floating point value to android resources/values

As described in this link http://droidista.blogspot.in/2012/04/adding-float-value-to-your-resources.html

Declare in dimen.xml

<item name="my_float_value" type="dimen" format="float">9.52</item>

Referencing from xml

@dimen/my_float_value

Referencing from java

TypedValue typedValue = new TypedValue();
getResources().getValue(R.dimen.my_float_value, typedValue, true);
float myFloatValue = typedValue.getFloat();

Center an element in Bootstrap 4 Navbar

use mx-auto will do the job

<ul class="navbar-nav mx-auto">

PDO support for multiple queries (PDO_MYSQL, PDO_MYSQLND)

After half a day of fiddling with this, found out that PDO had a bug where...

--

//This would run as expected:
$pdo->exec("valid-stmt1; valid-stmt2;");

--

//This would error out, as expected:
$pdo->exec("non-sense; valid-stmt1;");

--

//Here is the bug:
$pdo->exec("valid-stmt1; non-sense; valid-stmt3;");

It would execute the "valid-stmt1;", stop on "non-sense;" and never throw an error. Will not run the "valid-stmt3;", return true and lie that everything ran good.

I would expect it to error out on the "non-sense;" but it doesn't.

Here is where I found this info: Invalid PDO query does not return an error

Here is the bug: https://bugs.php.net/bug.php?id=61613


So, I tried doing this with mysqli and haven't really found any solid answer on how it works so I thought I's just leave it here for those who want to use it..

try{
    // db connection
    $mysqli = new mysqli("host", "user" , "password", "database");
    if($mysqli->connect_errno){
        throw new Exception("Connection Failed: [".$mysqli->connect_errno. "] : ".$mysqli->connect_error );
        exit();
    }

    // read file.
    // This file has multiple sql statements.
    $file_sql = file_get_contents("filename.sql");

    if($file_sql == "null" || empty($file_sql) || strlen($file_sql) <= 0){
        throw new Exception("File is empty. I wont run it..");
    }

    //run the sql file contents through the mysqli's multi_query function.
    // here is where it gets complicated...
    // if the first query has errors, here is where you get it.
    $sqlFileResult = $mysqli->multi_query($file_sql);
    // this returns false only if there are errros on first sql statement, it doesn't care about the rest of the sql statements.

    $sqlCount = 1;
    if( $sqlFileResult == false ){
        throw new Exception("File: '".$fullpath."' , Query#[".$sqlCount."], [".$mysqli->errno."]: '".$mysqli->error."' }");
    }

    // so handle the errors on the subsequent statements like this.
    // while I have more results. This will start from the second sql statement. The first statement errors are thrown above on the $mysqli->multi_query("SQL"); line
    while($mysqli->more_results()){
        $sqlCount++;
        // load the next result set into mysqli's active buffer. if this fails the $mysqli->error, $mysqli->errno will have appropriate error info.
        if($mysqli->next_result() == false){
            throw new Exception("File: '".$fullpath."' , Query#[".$sqlCount."], Error No: [".$mysqli->errno."]: '".$mysqli->error."' }");
        }
    }
}
catch(Exception $e){
    echo $e->getMessage(). " <pre>".$e->getTraceAsString()."</pre>";
}

MaxJsonLength exception in ASP.NET MVC during JavaScriptSerializer

None of the above worked out for me until I changed the Action as [HttpPost]. and made the ajax type as POST.

    [HttpPost]
    public JsonResult GetSelectedSignalData(string signal1,...)
    {
         JsonResult result = new JsonResult();
         var signalData = GetTheData();
         try
         {
              var serializer = new System.Web.Script.Serialization.JavaScriptSerializer { MaxJsonLength = Int32.MaxValue, RecursionLimit = 100 };

            result.Data = serializer.Serialize(signalData);
            return Json(result, JsonRequestBehavior.AllowGet);
            ..
            ..
            ...

    }

And the ajax call as

$.ajax({
    type: "POST",
    url: some_url,
    data: JSON.stringify({  signal1: signal1,.. }),
    contentType: "application/json; charset=utf-8",
    success: function (data) {
        if (data !== null) {
            setValue();
        }

    },
    failure: function (data) {
        $('#errMessage').text("Error...");
    },
    error: function (data) {
        $('#errMessage').text("Error...");
    }
});

How to search for a string in cell array in MATLAB?

I see that everybody missed the most important flaw in your code:

strs = {'HA' 'KU' 'LA' 'MA' 'TATA'}

should be:

strs = {'HA' 'KU' 'NA' 'MA' 'TATA'} 

or

strs = {'HAKUNA' 'MATATA'}

Now if you stick to using

ind=find(ismember(strs,'KU'))

You'll have no worries :).

Bootstrap 4 align navbar items to the right

Using the bootstrap flex box helps us to control the placement and alignment of your navigation element. for the problem above adding mr-auto is a better solution to it .

<div id="app" class="container">
  <nav class="navbar navbar-toggleable-md navbar-light bg-faded">
    <button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarNavDropdown" aria-controls="navbarNavDropdown" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>
    <a class="navbar-brand" href="#">Navbar</a>
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Features</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Pricingg</a>
      </li>
    </ul>
    <ul class="navbar-nav  " >
      <li  class="nav-item">
        <a class="nav-link" href="{{ url('/login') }}">Login</a>
      </li>
      <li  class="nav-item">
        <a class="nav-link" href="{{ url('/register') }}">Register</a>
      </li>
    </ul>
  </nav>
  @yield('content')
</div>

other placement may include

fixed- top
    fixed bottom
    sticky-top