Programs & Examples On #Shell icons

SQLException: No suitable Driver Found for jdbc:oracle:thin:@//localhost:1521/orcl

i have changed my old path: jdbc:odbc:thin:@localhost:1521:orcl

to new : jdbc:oracle:thin:@//localhost:1521/orcl

and it worked for me.....hurrah!! image

Web colors in an Android color xml resource file

If you are just looking for the available colors that already exist with

@android:color/<color>

then you need to look in android.jar >> android >> R.class >> R >> color.

Here is the list that come with Android 4.4W I'm using:

background_dark
background_light
black
darker_gray
holo_blue_bright
holo_blue_dark
holo_blue_light
holo_green_dark
holo_green_light
holo_orange_dark
holo_orange_light
holo_purple
holo_red_dark
holo_red_light
primary_text_dark
primary_text_dark_nodisable
primary_text_light
primary_text_lignt_nodisable
secondary_text_dark
secondary_text_dark_nodisable
secondaryy_text_light
secondary_text_lignt_nodisable
tab_indicator_text
tertiary_text_dark
tertiary_text_light
transparent
white
widget_edittext_dark

Error while trying to run project: Unable to start program. Cannot find the file specified

I've tried deleting .suo; .ncb; .sdf; rebuild etc. Nothing helped. The message was:

Unable to start program
'C:\Users\some user\Downloads\project name\.\Debug\fil_name.exe'
The system cannot find the file specified.

The problem was mismatched file name and wrong path to that file.
1. So went to Project->Properties->Linker->General-> and on the right pane in 'Output file' changed the name from 'fil_name.exe' to 'file_name.exe'
The file_name.exe was in deeper folder like -> \Debug\crv.
2. Also did Project->Properties->Configuration Properties-> and on the right pane in 'Output Directory' edited '.\Debug\' to '.\Debug\crv'

MySQL: Check if the user exists and drop it

If you mean you want to delete a drop from a table if it exists, you can use the DELETE command, for example:

 DELETE FROM users WHERE user_login = 'foobar'

If no rows match, it's not an error.

How to logout and redirect to login page using Laravel 5.4?

In 5.5

adding

Route::get('logout', 'Auth\LoginController@logout');

to my routes file works fine.

What are abstract classes and abstract methods?

abstract method do not have body.A well defined method can't be declared abstract.

A class which has abstract method must be declared as abstract.

Abstract class can't be instantiated.

Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)

First Type this-:

brew services start mysql

Then this -:

mysql -uroot

Remove all of x axis labels in ggplot

You have to set to element_blank() in theme() elements you need to remove

ggplot(data = diamonds, mapping = aes(x = clarity)) + geom_bar(aes(fill = cut))+
  theme(axis.title.x=element_blank(),
        axis.text.x=element_blank(),
        axis.ticks.x=element_blank())

How to pass arguments to entrypoint in docker-compose.yml

You can use docker-compose run instead of docker-compose up and tack the arguments on the end. For example:

docker-compose run dperson/samba arg1 arg2 arg3

If you need to connect to other docker containers, use can use --service-ports option:

docker-compose run --service-ports dperson/samba arg1 arg2 arg3

How do change the color of the text of an <option> within a <select>?

Try just this without the span tag:

<option selected="selected" class="grey_color">select one option</option>

For bigger flexibility you can use any JS widget.

How do I resolve `The following packages have unmet dependencies`

I tried lots of method but below work like charm....

After this command run these :-

curl -sL https://deb.nodesource.com/setup_14.x 565 | sudo -E bash -
sudo apt-get install -y nodejs

Now check…

node -v
npm -v

sorting integers in order lowest to highest java

import java.util.Arrays;

public class sortNumber {

public static void main(String[] args) {
    // Our array contains 13 elements 
    int[] array = {9,  238,  248,  138,  118,  45,  180,  212,  103,  230,  104,  41,  49}; 

    Arrays.sort(array); 

    System.out.printf(" The result : %s", Arrays.toString(array)); 
  }
}

Replace non-numeric with empty string

try this

public static string cleanPhone(string inVal)
        {
            char[] newPhon = new char[inVal.Length];
            int i = 0;
            foreach (char c in inVal)
                if (c.CompareTo('0') > 0 && c.CompareTo('9') < 0)
                    newPhon[i++] = c;
            return newPhon.ToString();
        }

Copy filtered data to another sheet using VBA

I suggest you do it a different way.

In the following code I set as a Range the column with the sports name F and loop through each cell of it, check if it is "hockey" and if yes I insert the values in the other sheet one by one, by using Offset.

I do not think it is very complicated and even if you are just learning VBA, you should probably be able to understand every step. Please let me know if you need some clarification

Sub TestThat()

'Declare the variables
Dim DataSh As Worksheet
Dim HokySh As Worksheet
Dim SportsRange As Range
Dim rCell As Range
Dim i As Long

'Set the variables
Set DataSh = ThisWorkbook.Sheets("Data")
Set HokySh = ThisWorkbook.Sheets("Hoky")

Set SportsRange = DataSh.Range(DataSh.Cells(3, 6), DataSh.Cells(Rows.Count, 6).End(xlUp))
    'I went from the cell row3/column6 (or F3) and go down until the last non empty cell

    i = 2

    For Each rCell In SportsRange 'loop through each cell in the range

        If rCell = "hockey" Then 'check if the cell is equal to "hockey"

            i = i + 1                                'Row number (+1 everytime I found another "hockey")
            HokySh.Cells(i, 2) = i - 2               'S No.
            HokySh.Cells(i, 3) = rCell.Offset(0, -1) 'School
            HokySh.Cells(i, 4) = rCell.Offset(0, -2) 'Background
            HokySh.Cells(i, 5) = rCell.Offset(0, -3) 'Age

        End If

    Next rCell

End Sub

How to unlock a file from someone else in Team Foundation Server

You need to be project admin or to have tfs account (user name/password) of the user who had locked the file.

in Visual Studio 2019:

  • Menu > View > Terminal (ctrl+`)
  • Wait until developer powershell or command prompt loads to the cursor like this:
    Drive:\your solution path>
  • you must undo changes to unlock the file:
    tf vc undo /workspace:"workspacename;worksapceowner" "$/path/[file.extension][*]" [/recursive] [/login:"user name,password"]
    example:-
    tf vc undo /workspace:"DESKTOP-F6BN2GHTKQ8;Johne123" "$/mywebsite/mywebsite/appsettings.json"

How to properly add include directories with CMake

Two things must be done.

First add the directory to be included:

target_include_directories(test PRIVATE ${YOUR_DIRECTORY})

In case you are stuck with a very old CMake version (2.8.10 or older) without support for target_include_directories, you can also use the legacy include_directories instead:

include_directories(${YOUR_DIRECTORY})

Then you also must add the header files to the list of your source files for the current target, for instance:

set(SOURCES file.cpp file2.cpp ${YOUR_DIRECTORY}/file1.h ${YOUR_DIRECTORY}/file2.h)
add_executable(test ${SOURCES})

This way, the header files will appear as dependencies in the Makefile, and also for example in the generated Visual Studio project, if you generate one.

How to use those header files for several targets:

set(HEADER_FILES ${YOUR_DIRECTORY}/file1.h ${YOUR_DIRECTORY}/file2.h)

add_library(mylib libsrc.cpp ${HEADER_FILES})
target_include_directories(mylib PRIVATE ${YOUR_DIRECTORY})
add_executable(myexec execfile.cpp ${HEADER_FILES})
target_include_directories(myexec PRIVATE ${YOUR_DIRECTORY})

Eclipse 3.5 Unable to install plugins

Couple of weeks ago I stumbled upon a Problem with Java and a MySQL-Connection. The Problem being that no Connection could be established. Anyway, the fix was to add -Djava.net.preferIPv4Stack=true to the command line.

I just added the same line to eclipse.ini and as it turns out, it also fixes this issue for me. The option name is pretty self-explainitory: It prefers the IPv4 stack over the IPv6 stack. So this solution may not be viable for everyone.

Return a value if no rows are found in Microsoft tSQL

You should avoid using expensive methods. You don't need any column for TBL2.

SELECT COUNT(*) FROM(
         SELECT TOP 1     1 AS CNT  FROM  TBL1 
         WHERE ColumnValue ='FooDoo') AS TBL2

Or this code:

IF EXISTS (SELECT TOP 1 1 FROM TABLE1 AS T1 
                          WHERE T1.ColumnValue='VooDoo') 
   SELECT 1 
ELSE 
   SELECT 0
 

Infinite Recursion with Jackson JSON and Hibernate JPA issue

I have the same problem after doing more analysis i came to know that, we can get mapped entity also by just keeping @JsonBackReference at OneToMany annotation

@Entity
@Table(name = "ta_trainee", uniqueConstraints = {@UniqueConstraint(columnNames = {"id"})})
public class Trainee extends BusinessObject {

@Id
@GeneratedValue(strategy = GenerationType.TABLE)
@Column(name = "id", nullable = false)
private Integer id;

@Column(name = "name", nullable = true)
private String name;

@Column(name = "surname", nullable = true)
private String surname;

@OneToMany(mappedBy = "trainee", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
@Column(nullable = true)
@JsonBackReference
private Set<BodyStat> bodyStats;

CodeIgniter - accessing $config variable in view

$config['cricket'] = 'bat'; in config.php file

$this->config->item('cricket') use this in view

How to highlight cell if value duplicate in same column for google spreadsheet?

I tried all the options and none worked.

Only google app scripts helped me.

source : https://ctrlq.org/code/19649-find-duplicate-rows-in-google-sheets

At the top of your document

1.- go to tools > script editor

2.- set the name of your script

3.- paste this code :

function findDuplicates() {
  // List the columns you want to check by number (A = 1)
  var CHECK_COLUMNS = [1];

  // Get the active sheet and info about it
  var sourceSheet = SpreadsheetApp.getActiveSheet();
  var numRows = sourceSheet.getLastRow();
  var numCols = sourceSheet.getLastColumn();

  // Create the temporary working sheet
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var newSheet = ss.insertSheet("FindDupes");

  // Copy the desired rows to the FindDupes sheet
  for (var i = 0; i < CHECK_COLUMNS.length; i++) {
    var sourceRange = sourceSheet.getRange(1,CHECK_COLUMNS[i],numRows);
    var nextCol = newSheet.getLastColumn() + 1;
    sourceRange.copyTo(newSheet.getRange(1,nextCol,numRows));
  }

  // Find duplicates in the FindDupes sheet and color them in the main sheet
  var dupes = false;
  var data = newSheet.getDataRange().getValues();
  for (i = 1; i < data.length - 1; i++) {
    for (j = i+1; j < data.length; j++) {
      if  (data[i].join() == data[j].join()) {
        dupes = true;
        sourceSheet.getRange(i+1,1,1,numCols).setBackground("red");
        sourceSheet.getRange(j+1,1,1,numCols).setBackground("red");
      }
    }
  }

  // Remove the FindDupes temporary sheet
  ss.deleteSheet(newSheet);

  // Alert the user with the results
  if (dupes) {
    Browser.msgBox("Possible duplicate(s) found and colored red.");
  } else {
    Browser.msgBox("No duplicates found.");
  }
};

4.- save and run

In less than 3 seconds, my duplicate row was colored. Just copy-past the script.

If you don't know about google apps scripts , this links could be help you:

https://zapier.com/learn/google-sheets/google-apps-script-tutorial/

https://developers.google.com/apps-script/overview

I hope this helps.

How to add a button dynamically using jquery

Working plunk here.

To add the new input just once, use the following code:

$(document).ready(function()
{
  $("#insertAfterBtn").one("click", function(e)
  {
    var r = $('<input/>', { type: "button", id: "field", value: "I'm a button" });

    $("body").append(r);
  });
});

[... source stripped here ...]

<body>
    <button id="insertAfterBtn">Insert after</button>
</body>

[... source stripped here ...]

To make it work in w3 editor, copy/paste the code below into 'source code' section inside w3 editor and then hit 'Submit Code':

<!DOCTYPE html>
<html>

  <head>
    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
  </head>

  <body>
    <button id="insertAfterBtn">Insert only one button after</button>
    <div class="myClass"></div>
    <div id="myId"></div>
  </body>

<script type="text/javascript">
$(document).ready(function()
{
  // when dom is ready, call this method to add an input to 'body' tag.
  addInputTo($("body"));

  // when dom is ready, call this method to add an input to a div with class=myClass
  addInputTo($(".myClass"));

  // when dom is ready, call this method to add an input to a div with id=myId
  addInputTo($("#myId"));

  $("#insertAfterBtn").one("click", function(e)
  {
    var r = $('<input/>', { type: "button", id: "field", value: "I'm a button" });

    $("body").append(r);
  });
});

function addInputTo(container)
{
  var inputToAdd = $("<input/>", { type: "button", id: "field", value: "I was added on page load" });

  container.append(inputToAdd);
}
</script>

</html>

Better way to remove specific characters from a Perl string

With a character class this big it is easier to say what you want to keep. A caret in the first position of a character class inverts its sense, so you can write

$varTemp =~ s/[^"%'+\-0-9<=>a-z_{|}]+//gi

or, using the more efficient tr

$varTemp =~ tr/"%'+\-0-9<=>A-Z_a-z{|}//cd

tr docs

Tick symbol in HTML/XHTML

I normally use the fontawesome font(http://fontawesome.io/icon/check/), you can use it in html files:

 <i class="fa fa-check"></i>

or in css:

content: "\f00c";
font-family: FontAwesome;

Unresponsive KeyListener for JFrame

You must add your keyListener to every component that you need. Only the component with the focus will send these events. For instance, if you have only one TextBox in your JFrame, that TextBox has the focus. So you must add a KeyListener to this component as well.

The process is the same:

myComponent.addKeyListener(new KeyListener ...);

Note: Some components aren't focusable like JLabel.

For setting them to focusable you need to:

myComponent.setFocusable(true);

Initializing a two dimensional std::vector

The recommended approach is to use fill constructor to initialize a two-dimensional vector with a given default value :

std::vector<std::vector<int>> fog(M, std::vector<int>(N, default_value));

where, M and N are dimensions for your 2D vector.

How to insert a line break <br> in markdown

Try adding 2 spaces (or a backslash \) after the first line:

[Name of link](url)
My line of text\

Visually:

[Name of link](url)<space><space>
My line of text\

Output:

<p><a href="url">Name of link</a><br>
My line of text<br></p>

How to create threads in nodejs

There is also now https://github.com/xk/node-threads-a-gogo, though I'm not sure about project status.

How to calculate a mod b in Python?

There's the % sign. It's not just for the remainder, it is the modulo operation.

How to get the error message from the error code returned by GetLastError()?

If you're using c# you can use this code:

using System.Runtime.InteropServices;

public static class WinErrors
{
    #region definitions
    [DllImport("kernel32.dll", SetLastError = true)]
    static extern IntPtr LocalFree(IntPtr hMem);

    [DllImport("kernel32.dll", SetLastError = true)]
    static extern int FormatMessage(FormatMessageFlags dwFlags, IntPtr lpSource, uint dwMessageId, uint dwLanguageId, ref IntPtr lpBuffer, uint nSize, IntPtr Arguments);

    [Flags]
    private enum FormatMessageFlags : uint
    {
        FORMAT_MESSAGE_ALLOCATE_BUFFER = 0x00000100,
        FORMAT_MESSAGE_IGNORE_INSERTS = 0x00000200,
        FORMAT_MESSAGE_FROM_SYSTEM = 0x00001000,
        FORMAT_MESSAGE_ARGUMENT_ARRAY = 0x00002000,
        FORMAT_MESSAGE_FROM_HMODULE = 0x00000800,
        FORMAT_MESSAGE_FROM_STRING = 0x00000400,
    }
    #endregion

    /// <summary>
    /// Gets a user friendly string message for a system error code
    /// </summary>
    /// <param name="errorCode">System error code</param>
    /// <returns>Error string</returns>
    public static string GetSystemMessage(int errorCode)
    {
        try
        {
            IntPtr lpMsgBuf = IntPtr.Zero;

            int dwChars = FormatMessage(
                FormatMessageFlags.FORMAT_MESSAGE_ALLOCATE_BUFFER | FormatMessageFlags.FORMAT_MESSAGE_FROM_SYSTEM | FormatMessageFlags.FORMAT_MESSAGE_IGNORE_INSERTS,
                IntPtr.Zero,
                (uint) errorCode,
                0, // Default language
                ref lpMsgBuf,
                0,
                IntPtr.Zero);
            if (dwChars == 0)
            {
                // Handle the error.
                int le = Marshal.GetLastWin32Error();
                return "Unable to get error code string from System - Error " + le.ToString();
            }

            string sRet = Marshal.PtrToStringAnsi(lpMsgBuf);

            // Free the buffer.
            lpMsgBuf = LocalFree(lpMsgBuf);
            return sRet;
        }
        catch (Exception e)
        {
            return "Unable to get error code string from System -> " + e.ToString();
        }
    }
}

Filtering collections in C#

To do it in place, you can use the RemoveAll method of the "List<>" class along with a custom "Predicate" class...but all that does is clean up the code... under the hood it's doing the same thing you are...but yes, it does it in place, so you do same the temp list.

In C#, can a class inherit from another class and an interface?

I found the answer to the second part of my questions. Yes, a class can implement an interface that is in a different class as long that the interface is declared as public.

Rotate and translate

Something that may get missed: in my chaining project, it turns out a space separated list also needs a space separated semicolon at the end.

In other words, this doesn't work:

transform: translate(50%, 50%) rotate(90deg);

but this does:

transform: translate(50%, 50%) rotate(90deg) ; //has a space before ";"

Is there a typescript List<> and/or Map<> class/library?

It's very easy to write that yourself, and that way you have more control over things.. As the other answers say, TypeScript is not aimed at adding runtime types or functionality.

Map:

class Map<T> {
    private items: { [key: string]: T };

    constructor() {
        this.items = {};
    }

    add(key: string, value: T): void {
        this.items[key] = value;
    }

    has(key: string): boolean {
        return key in this.items;
    }

    get(key: string): T {
        return this.items[key];
    }
}

List:

class List<T> {
    private items: Array<T>;

    constructor() {
        this.items = [];
    }

    size(): number {
        return this.items.length;
    }

    add(value: T): void {
        this.items.push(value);
    }

    get(index: number): T {
        return this.items[index];
    }
}

I haven't tested (or even tried to compile) this code, but it should give you a starting point.. you can of course then change what ever you want and add the functionality that YOU need...

As for your "special needs" from the List, I see no reason why to implement a linked list, since the javascript array lets you add and remove items.
Here's a modified version of the List to handle the get prev/next from the element itself:

class ListItem<T> {
    private list: List<T>;
    private index: number;

    public value: T;

    constructor(list: List<T>, value: T, index: number) {
        this.list = list;
        this.index = index;
        this.value = value;
    }

    prev(): ListItem<T> {
        return this.list.get(this.index - 1);
    }

    next(): ListItem<T> {
        return this.list.get(this.index + 1);   
    }
}

class List<T> {
    private items: Array<ListItem<T>>;

    constructor() {
        this.items = [];
    }

    size(): number {
        return this.items.length;
    }

    add(value: T): void {
        this.items.push(new ListItem<T>(this, value, this.size()));
    }

    get(index: number): ListItem<T> {
        return this.items[index];
    }
}

Here too you're looking at untested code..

Hope this helps.


Edit - as this answer still gets some attention

Javascript has a native Map object so there's no need to create your own:

let map = new Map();
map.set("key1", "value1");
console.log(map.get("key1")); // value1

cpp / c++ get pointer value or depointerize pointer

To get the value of a pointer, just de-reference the pointer.

int *ptr;
int value;
*ptr = 9;

value = *ptr;

value is now 9.

I suggest you read more about pointers, this is their base functionality.

How to remove margin space around body or clear default css styles

I had the same problem and my first <p> element which was at the top of the page and also had a browser webkit default margin. This was pushing my entire div down which had the same effect you were talking about so watch out for any text-based elements that are at the very top of the page.

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>My Website</title>
  </head>
  <body style="margin:0;">
      <div id="image" style="background: url(pixabay-cleaning-kids-720.jpg) 
no-repeat; width: 100%; background-size: 100%;height:100vh">
<p>Text in Paragraph</p>
      </div>
    </div>
  </body>
</html>

So just remember to check all child elements not only the html and body tags.

What is the difference between a hash join and a merge join (Oracle RDBMS )?

I just want to edit this for posterity that the tags for oracle weren't added when I answered this question. My response was more applicable to MS SQL.

Merge join is the best possible as it exploits the ordering, resulting in a single pass down the tables to do the join. IF you have two tables (or covering indexes) that have their ordering the same such as a primary key and an index of a table on that key then a merge join would result if you performed that action.

Hash join is the next best, as it's usually done when one table has a small number (relatively) of items, its effectively creating a temp table with hashes for each row which is then searched continuously to create the join.

Worst case is nested loop which is order (n * m) which means there is no ordering or size to exploit and the join is simply, for each row in table x, search table y for joins to do.

Sorting Values of Set

You're using the default comparator to sort a Set<String>. In this case, that means lexicographic order. Lexicographically, "12" comes before "15", comes before "5".

Either use a Set<Integer>:

Set<Integer> set=new HashSet<Integer>();
set.add(12);
set.add(15);
set.add(5);

Or use a different comparator:

Collections.sort(list, new Comparator<String>() {
    public int compare(String a, String b) {
        return Integer.parseInt(a) - Integer.parseInt(b);
    }
});

Most efficient way to convert an HTMLCollection to an Array

This is my personal solution, based on the information here (this thread):

var Divs = new Array();    
var Elemns = document.getElementsByClassName("divisao");
    try {
        Divs = Elemns.prototype.slice.call(Elemns);
    } catch(e) {
        Divs = $A(Elemns);
    }

Where $A was described by Gareth Davis in his post:

function $A(iterable) {
  if (!iterable) return [];
  if ('toArray' in Object(iterable)) return iterable.toArray();
  var length = iterable.length || 0, results = new Array(length);
  while (length--) results[length] = iterable[length];
  return results;
}

If browser supports the best way, ok, otherwise will use the cross browser.

How do I mock a static method that returns void with PowerMock?

You can do it the same way you do it with Mockito on real instances. For example you can chain stubs, the following line will make the first call do nothing, then second and future call to getResources will throw the exception :

// the stub of the static method
doNothing().doThrow(Exception.class).when(StaticResource.class);
StaticResource.getResource("string");

// the use of the mocked static code
StaticResource.getResource("string"); // do nothing
StaticResource.getResource("string"); // throw Exception

Thanks to a remark of Matt Lachman, note that if the default answer is not changed at mock creation time, the mock will do nothing by default. Hence writing the following code is equivalent to not writing it.

doNothing().doThrow(Exception.class).when(StaticResource.class);
StaticResource.getResource("string");

Though that being said, it can be interesting for colleagues that will read the test that you expect nothing for this particular code. Of course this can be adapted depending on how is perceived understandability of the test.


By the way, in my humble opinion you should avoid mocking static code if your crafting new code. At Mockito we think it's usually a hint to bad design, it might lead to poorly maintainable code. Though existing legacy code is yet another story.

Generally speaking if you need to mock private or static method, then this method does too much and should be externalized in an object that will be injected in the tested object.

Hope that helps.

Regards

filedialog, tkinter and opening files

Did you try adding the self prefix to the fileName and replacing the method above the Button ? With the self, it becomes visible between methods.

...

def load_file(self):
    self.fileName = filedialog.askopenfilename(filetypes = (("Template files", "*.tplate")
                                                     ,("HTML files", "*.html;*.htm")
                                                     ,("All files", "*.*") ))
...

Twitter Bootstrap 3.0 how do I "badge badge-important" now

Well, this is a terribly late answer but I think I'll still put my two cents in... I could have posted this as a comment because this answer doesn't essentially add any new solution but it does add value to the post as yet another alternative. But in a comment I wouldn't be able to give all the details because of character limit.

NOTE: This needs an edit to bootstrap CSS file - move style definitions for .badge above .label-default. Couldn't find any practical side effects due to the change in my limited testing.

While broc.seib's solution is probably the best way to achieve the requirement of OP with minimal addition to CSS, it is possible to achieve the same effect without any extra CSS at all just like Jens A. Koch's solution or by using .label-xxx contextual classes because they are easy to remember compared to progress-bar-xxx classes. I don't think that .alert-xxx classes give the same effect.

All you have to do is just use .badge and .label-xxx classes together (but in this order). Don't forget to make the changes mentioned in NOTE above.

<a href="#">Inbox <span class="badge label-warning">42</span></a> looks like this:

Badge with warning bg

IMPORTANT: This solution may break your styles if you decide to upgrade and forget to make the changes in your new local CSS file. My solution for this challenge was to copy all .label-xxx styles in my custom CSS file and load it after all other CSS files. This approach also helps when I use a CDN for loading BS3.

**P.S: ** Both the top rated answers have their pros and cons. It's just the way you prefer to do your CSS because there is no "only correct way" to do it.

Select * from subquery

You can select every column from that sub-query by aliasing it and adding the alias before the *:

SELECT t.*, a+b AS total_sum
FROM
(
   SELECT SUM(column1) AS a, SUM(column2) AS b
   FROM table
) t

Dynamically allocating an array of objects

Using the placement feature of new operator, you can create the object in place and avoid copying:

placement (3) :void* operator new (std::size_t size, void* ptr) noexcept;

Simply returns ptr (no storage is allocated). Notice though that, if the function is called by a new-expression, the proper initialization will be performed (for class objects, this includes calling its default constructor).

I suggest the following:

A* arrayOfAs = new A[5]; //Allocate a block of memory for 5 objects
for (int i = 0; i < 5; ++i)
{
    //Do not allocate memory,
    //initialize an object in memory address provided by the pointer
    new (&arrayOfAs[i]) A(3);
}

What is an efficient way to implement a singleton pattern in Java?

Use an enum:

public enum Foo {
    INSTANCE;
}

Joshua Bloch explained this approach in his Effective Java Reloaded talk at Google I/O 2008: link to video. Also see slides 30-32 of his presentation (effective_java_reloaded.pdf):

The Right Way to Implement a Serializable Singleton

public enum Elvis {
    INSTANCE;
    private final String[] favoriteSongs =
        { "Hound Dog", "Heartbreak Hotel" };
    public void printFavorites() {
        System.out.println(Arrays.toString(favoriteSongs));
    }
}

Edit: An online portion of "Effective Java" says:

"This approach is functionally equivalent to the public field approach, except that it is more concise, provides the serialization machinery for free, and provides an ironclad guarantee against multiple instantiation, even in the face of sophisticated serialization or reflection attacks. While this approach has yet to be widely adopted, a single-element enum type is the best way to implement a singleton."

How to put scroll bar only for modal-body?

Adding on to Carlos Calla's great answer.

The height of .modal-body must be set, BUT you can use media queries to make sure it's appropriate for the screen size.

.modal-body{
    height: 250px;
    overflow-y: auto;
}

@media (min-height: 500px) {
    .modal-body { height: 400px; }
}

@media (min-height: 800px) {
    .modal-body { height: 600px; }
}

How do I collapse a table row in Bootstrap?

I just came up with the same problem since we still use bootstrap 2.3.2.

My solution for this: http://jsfiddle.net/KnuU6/281/

css:

.myCollapse {
    display: none;
}
.myCollapse.in {
    display: block;
}

javascript:

 $("[data-toggle=myCollapse]").click(function( ev ) {
   ev.preventDefault();
   var target;
   if (this.hasAttribute('data-target')) {
 target = $(this.getAttribute('data-target'));
   } else {
 target = $(this.getAttribute('href'));
   };
   target.toggleClass("in");
 });

html:

<table>
  <tr><td><a href="#demo" data-toggle="myCollapse">Click me to toggle next row</a></td></tr>
  <tr class="collapse" id="#demo"><td>You can collapse and expand me.</td></tr>
</table>

Change Select List Option background colour on hover

The problem is that even JavaScript does not see the option element being hovered. This is just to put emphasis on how it's not going to be solved (any time soon at least) by using just CSS:

window.onmouseover = function(e)
{
 console.log(e.target.nodeName);
}

The only way to resolve this issue (besides waiting a millennia for browser vendors to fix bugs, let alone one that afflicts what you're trying to do) is to replace the drop-down menu with your own HTML/XML using JavaScript. This would likely involve the use of replacing the select element with a ul element and the use of a radio input element per li element.

HTML/CSS font color vs span style

Use style. The font tag is deprecated (W3C Wiki).

Why is the parent div height zero when it has floated children

Content that is floating does not influence the height of its container. The element contains no content that isn't floating (so nothing stops the height of the container being 0, as if it were empty).

Setting overflow: hidden on the container will avoid that by establishing a new block formatting context. See methods for containing floats for other techniques and containing floats for an explanation about why CSS was designed this way.

How to add parameters to a HTTP GET request in Android?

As of HttpComponents 4.2+ there is a new class URIBuilder, which provides convenient way for generating URIs.

You can use either create URI directly from String URL:

List<NameValuePair> listOfParameters = ...;

URI uri = new URIBuilder("http://example.com:8080/path/to/resource?mandatoryParam=someValue")
    .addParameter("firstParam", firstVal)
    .addParameter("secondParam", secondVal)
    .addParameters(listOfParameters)
    .build();

Otherwise, you can specify all parameters explicitly:

URI uri = new URIBuilder()
    .setScheme("http")
    .setHost("example.com")
    .setPort(8080)
    .setPath("/path/to/resource")
    .addParameter("mandatoryParam", "someValue")
    .addParameter("firstParam", firstVal)
    .addParameter("secondParam", secondVal)
    .addParameters(listOfParameters)
    .build();

Once you have created URI object, then you just simply need to create HttpGet object and perform it:

//create GET request
HttpGet httpGet = new HttpGet(uri);
//perform request
httpClient.execute(httpGet ...//additional parameters, handle response etc.

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

python manage.py flush

deleted old db contents,

Don't forget to create new superuser:

python manage.py createsuperuser

How do I remove a single breakpoint with GDB?

Try these (reference):

clear linenum
clear filename:linenum

Creating your own header file in C

foo.h

#ifndef FOO_H_   /* Include guard */
#define FOO_H_

int foo(int x);  /* An example function declaration */

#endif // FOO_H_

foo.c

#include "foo.h"  /* Include the header (not strictly necessary here) */

int foo(int x)    /* Function definition */
{
    return x + 5;
}

main.c

#include <stdio.h>
#include "foo.h"  /* Include the header here, to obtain the function declaration */

int main(void)
{
    int y = foo(3);  /* Use the function here */
    printf("%d\n", y);
    return 0;
}

To compile using GCC

gcc -o my_app main.c foo.c

Run local python script on remote server

ssh user@machine python < script.py - arg1 arg2

Because cat | is usually not necessary

How many significant digits do floats and doubles have in java?

A 32-bit float has about 7 digits of precision and a 64-bit double has about 16 digits of precision

Long answer:

Floating-point numbers have three components:

  1. A sign bit, to determine if the number is positive or negative.
  2. An exponent, to determine the magnitude of the number.
  3. A fraction, which determines how far between two exponent values the number is. This is sometimes called “the significand, mantissa, or coefficient”

Essentially, this works out to sign * 2^exponent * (1 + fraction). The “size” of the number, it’s exponent, is irrelevant to us, because it only scales the value of the fraction portion. Knowing that log10(n) gives the number of digits of n,† we can determine the precision of a floating point number with log10(largest_possible_fraction). Because each bit in a float stores 2 possibilities, a binary number of n bits can store a number up to 2n - 1 (a total of 2n values where one of the values is zero). This gets a bit hairier, because it turns out that floating point numbers are stored with one less bit of fraction than they can use, because zeroes are represented specially and all non-zero numbers have at least one non-zero binary bit.‡

Combining this, the digits of precision for a floating point number is log10(2n), where n is the number of bits of the floating point number’s fraction. A 32-bit float has 24 bits of fraction for ˜7.22 decimal digits of precision, and a 64-bit double has 53 bits of fraction for ˜15.95 decimal digits of precision.

For more on floating point accuracy, you might want to read about the concept of a machine epsilon.


† For n = 1 at least — for other numbers your formula will look more like ?log10(|n|)? + 1.

‡ “This rule is variously called the leading bit convention, the implicit bit convention, or the hidden bit convention.” (Wikipedia)

Error checking for NULL in VBScript

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

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

Angular ForEach in Angular4/Typescript?

In Typescript use the For Each like below.

selectChildren(data, $event) {
let parentChecked = data.checked;
for(var obj in this.hierarchicalData)
    {
        for (var childObj in obj )
        {
            value.checked = parentChecked;
        }
    }
}

How to convert a pandas DataFrame subset of columns AND rows into a numpy array?

.loc accept row and column selectors simultaneously (as do .ix/.iloc FYI) This is done in a single pass as well.

In [1]: df = DataFrame(np.random.rand(4,5), columns = list('abcde'))

In [2]: df
Out[2]: 
          a         b         c         d         e
0  0.669701  0.780497  0.955690  0.451573  0.232194
1  0.952762  0.585579  0.890801  0.643251  0.556220
2  0.900713  0.790938  0.952628  0.505775  0.582365
3  0.994205  0.330560  0.286694  0.125061  0.575153

In [5]: df.loc[df['c']>0.5,['a','d']]
Out[5]: 
          a         d
0  0.669701  0.451573
1  0.952762  0.643251
2  0.900713  0.505775

And if you want the values (though this should pass directly to sklearn as is); frames support the array interface

In [6]: df.loc[df['c']>0.5,['a','d']].values
Out[6]: 
array([[ 0.66970138,  0.45157274],
       [ 0.95276167,  0.64325143],
       [ 0.90071271,  0.50577509]])

How to open a Bootstrap modal window using jQuery?

Most often, when $('#myModal').modal('show'); doesn't work, it's caused by having included jQuery twice. Including jQuery 2 times makes modals not to work.

Remove one of the links to make it work again.

Furthermore, some plugins cause errors too, in this case add

jQuery.noConflict(); 
$('#myModal').modal('show'); 

Twitter bootstrap scrollable table

This example shows how to have sticky headers when using Bootstrap 4 table styling.

_x000D_
_x000D_
.table-scrollable {
    /* set the height to enable overflow of the table */
    max-height: 200px;
    
    overflow-x: auto;
    overflow-y: auto;
    scrollbar-width: thin;
}

.table-scrollable thead th {
    border: none;
}

.table-scrollable thead th {
    /* Set header to stick to the top of the container. */
    position: sticky; 
    top: 0px;
    
    /* This is needed otherwise the sticky header will be transparent 
    */
    background-color: white;

    /* Because bootstrap adds `border-collapse: collapse` to the
     * table, the header boarders aren't sticky.
     * So, we need to make some adjustments to cover up the actual
     * header borders and created fake borders instead
     */
    margin-top: -1px;
    margin-bottom: -1px;

    /* This is our fake border (see above comment) */
    box-shadow: inset 0 1px 0 #dee2e6,
                inset 0 -1px 0 #dee2e6;
}
_x000D_
<!-- CSS -->
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" integrity="sha384-TX8t27EcRE3e/ihU7zmQxVncDAy5uIKz4rEkgIXeMed4M0jlfIDPvg6uqKI2xXr2" crossorigin="anonymous">

<!-- jQuery and JS bundle w/ Popper.js -->
<script src="https://code.jquery.com/jquery-3.5.1.slim.min.js" integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/js/bootstrap.bundle.min.js" integrity="sha384-ho+j7jyWK8fNQe+A12Hb8AhRq26LrZ/JpcUGGOn+Y7RsweNrtN/tE3MoK7ZeZDyx" crossorigin="anonymous"></script>


<div class="dashboard-container card">
  <div class="card-body">
    <div class="table-scrollable">
      <table class="table table-hover table-sortable">
          <thead>
              <tr>
                  <th data-sort-type="text">Course</th>
                  <th data-sort-type="numeric">In Progress</th>
                  <th data-sort-type="numeric">Not Started</th>
                  <th data-sort-type="numeric">Passed</th>
                  <th data-sort-type="numeric">Failed</th>
              </tr>
          </thead>
          <tbody>
            <tr>
              <td>How to be good at stuff</td>
              <td>0</td>
              <td>1000</td>
              <td>0</td>
              <td>0</td>
            </tr>
            <tr>
              <td>Quantum physics for artists</td>
              <td>200</td>
              <td>6</td>
              <td>66</td>
              <td>66</td>
            </tr>
            <tr>
              <td>The best way to skin a cat</td>
              <td>34</td>
              <td>16</td>
              <td>200</td>
              <td>7</td>
            </tr>
            <tr>
              <td>Human cookbook</td>
              <td>4</td>
              <td>7</td>
              <td>4</td>
              <td>50</td>
            </tr>
            <tr>
              <td>Aristocracy rules</td>
              <td>100</td>
              <td>3</td>
              <td>6</td>
              <td>18</td>
            </tr>
          </tbody>
      </table>
    </div>
  </div>
</div>
_x000D_
_x000D_
_x000D_

linux find regex

Note that -regex depends on whole path.

 -regex pattern
              File name matches regular expression pattern.  
              This is a match on the whole path, not a search.

You don't actually have to use -regex for what you are doing.

find . -iname "*[0-9]"

How can I count the number of matches for a regex?

Use the below code to find the count of number of matches that the regex finds in your input

        Pattern p = Pattern.compile(regex, Pattern.MULTILINE | Pattern.DOTALL);// "regex" here indicates your predefined regex.
        Matcher m = p.matcher(pattern); // "pattern" indicates your string to match the pattern against with
        boolean b = m.matches();
        if(b)
        count++;
        while (m.find())
        count++;

This is a generalized code not specific one though, tailor it to suit your need

Please feel free to correct me if there is any mistake.

Executing Shell Scripts from the OS X Dock?

As joe mentioned, creating the shell script and then creating an applescript script to call the shell script, will accomplish this, and is quite handy.

Shell Script

  1. Create your shell script in your favorite text editor, for example:

    mono "/Volumes/Media/~Users/me/Software/keepass/keepass.exe"

    (this runs the w32 executable, using the mono framework)

  2. Save shell script, for my example "StartKeepass.sh"

Apple Script

  1. Open AppleScript Editor, and call the shell script

    do shell script "sh /Volumes/Media/~Users/me/Software/StartKeepass.sh" user name "<enter username here>" password "<Enter password here>" with administrator privileges

    • do shell script - applescript command to call external shell commands
    • "sh ...." - this is your shell script (full path) created in step one (you can also run direct commands, I could omit the shell script and just run my mono command here)
    • user name - declares to applescript you want to run the command as a specific user
    • "<enter username here> - replace with your username (keeping quotes) ex "josh"
    • password - declares to applescript your password
    • "<enter password here>" - replace with your password (keeping quotes) ex "mypass"
    • with administrative privileges - declares you want to run as an admin

Create Your .APP

  1. save your applescript as filename.scpt, in my case RunKeepass.scpt

  2. save as... your applescript and change the file format to application, resulting in RunKeepass.app in my case

  3. Copy your app file to your apps folder

Whitespaces in java

If you can use apache.commons.lang in your project, the easiest way would be just to use the method provided there:

public static boolean containsWhitespace(CharSequence seq)

Check whether the given CharSequence contains any whitespace characters.

Parameters:

seq - the CharSequence to check (may be null) 

Returns:

true if the CharSequence is not empty and contains at least 1 whitespace character

It handles empty and null parameters and provides the functionality at a central place.

String formatting in Python 3

I like this approach

my_hash = {}
my_hash["goals"] = 3 #to show number
my_hash["penalties"] = "5" #to show string
print("I scored %(goals)d goals and took %(penalties)s penalties" % my_hash)

Note the appended d and s to the brackets respectively.

output will be:

I scored 3 goals and took 5 penalties

How to select and change value of table cell with jQuery?

i was looking for changing second row html and you can do cascading selector

$('#tbox1 tr:nth-child(2) td').html(11111)

What's a good, free serial port monitor for reverse-engineering?

Oops, can't comment yet (!) but re: Nick and logic analyser, beware: RS232 signal levels not typically Logic Analyser compatible unless you get/make a special serial probe. A 'proper' RS232/Serial port can use +/-12v swings (on all signals) and sometimes more. A laptop sometimes uses 0-5v swings (and often won't work with real serial interfaces) so could work with a vbasic 'ttl-level' LA interface.

Opening a .ipynb.txt File

Below is the easiest way in case if Anaconda is already installed.

1) Under "Files", there is an option called,"Upload".

2) Click on "Upload" button and it asks for the path of the file and select the file and click on upload button present beside the file.

Perform curl request in javascript?

curl is a command in linux (and a library in php). Curl typically makes an HTTP request.

What you really want to do is make an HTTP (or XHR) request from javascript.

Using this vocab you'll find a bunch of examples, for starters: Sending authorization headers with jquery and ajax

Essentially you will want to call $.ajax with a few options for the header, etc.

$.ajax({
        url: 'https://api.wit.ai/message?v=20140826&q=',
        beforeSend: function(xhr) {
             xhr.setRequestHeader("Authorization", "Bearer 6QXNMEMFHNY4FJ5ELNFMP5KRW52WFXN5")
        }, success: function(data){
            alert(data);
            //process the JSON data etc
        }
})

Bootstrap tab activation with JQuery

This one is quite straightforward from w3schools: https://www.w3schools.com/bootstrap/bootstrap_ref_js_tab.asp

// Select tab by name
$('.nav-tabs a[href="#home"]').tab('show')

// Select first tab
$('.nav-tabs a:first').tab('show') 

// Select last tab
$('.nav-tabs a:last').tab('show') 

// Select fourth tab (zero-based)
$('.nav-tabs li:eq(3) a').tab('show')

What does question mark and dot operator ?. mean in C# 6.0?

This is relatively new to C# which makes it easy for us to call the functions with respect to the null or non-null values in method chaining.

old way to achieve the same thing was:

var functionCaller = this.member;
if (functionCaller!= null)
    functionCaller.someFunction(var someParam);

and now it has been made much easier with just:

member?.someFunction(var someParam);

I strongly recommend this doc page.

Calculate relative time in C#

// Calculate total days in current year
int daysInYear;

for (var i = 1; i <= 12; i++)
    daysInYear += DateTime.DaysInMonth(DateTime.Now.Year, i);

// Past date
DateTime dateToCompare = DateTime.Now.Subtract(TimeSpan.FromMinutes(582));

// Calculate difference between current date and past date
double diff = (DateTime.Now - dateToCompare).TotalMilliseconds;

TimeSpan ts = TimeSpan.FromMilliseconds(diff);

var years = ts.TotalDays / daysInYear; // Years
var months = ts.TotalDays / (daysInYear / (double)12); // Months
var weeks = ts.TotalDays / 7; // Weeks
var days = ts.TotalDays; // Days
var hours = ts.TotalHours; // Hours
var minutes = ts.TotalMinutes; // Minutes
var seconds = ts.TotalSeconds; // Seconds

if (years >= 1)
    Console.WriteLine(Math.Round(years, 0) + " year(s) ago");
else if (months >= 1)
    Console.WriteLine(Math.Round(months, 0) + " month(s) ago");
else if (weeks >= 1)
    Console.WriteLine(Math.Round(weeks, 0) + " week(s) ago");
else if (days >= 1)
    Console.WriteLine(Math.Round(days, 0) + " days(s) ago");
else if (hours >= 1)
    Console.WriteLine(Math.Round(hours, 0) + " hour(s) ago");
else if (minutes >= 1)
    Console.WriteLine(Math.Round(minutes, 0) + " minute(s) ago");
else if (seconds >= 1)
    Console.WriteLine(Math.Round(seconds, 0) + " second(s) ago");

Console.ReadLine();

Tools to search for strings inside files without indexing

I'm a fan of the Find-In-Files dialog in Notepad++. Bonus: It's free.

enter image description here

How can I find WPF controls by name or type?

I was able to find objects by name using below code.

stkMultiChildControl = stkMulti.FindChild<StackPanel>("stkMultiControl_" + couter.ToString());

How do I center content in a div using CSS?

To align horizontally it's pretty straight forward:

    <style type="text/css"> 
body  {
    margin: 0; 
    padding: 0;
    text-align: center;
}
.bodyclass #container { 
    width: ???px; /*SET your width here*/
    margin: 0 auto;
    text-align: left;
} 
</style>
<body class="bodyclass ">
<div id="container">type your content here</div>
</body>

and for vertical align, it's a bit tricky: here's the source

    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html>
<head>
  <title>Universal vertical center with CSS</title>
  <style>
    .greenBorder {border: 1px solid green;} /* just borders to see it */
  </style>
</head>

<body>
  <div class="greenBorder" style="display: table; height: 400px; #position: relative; overflow: hidden;">
    <div style=" #position: absolute; #top: 50%;display: table-cell; vertical-align: middle;">
      <div class="greenBorder" style=" #position: relative; #top: -50%">
        any text<br>
        any height<br>
        any content, for example generated from DB<br>
        everything is vertically centered
      </div>
    </div>
  </div>
</body>
</html>

How does `scp` differ from `rsync`?

One major feature of rsync over scp (beside the delta algorithm and encryption if used w/ ssh) is that it automatically verifies if the transferred file has been transferred correctly. Scp will not do that, which occasionally might result in corruption when transferring larger files. So in general rsync is a copy with guarantee.

Centos manpages mention this the end of the --checksum option description:

Note that rsync always verifies that each transferred file was correctly reconstructed on the receiving side by checking a whole-file checksum that is generated as the file is transferred, but that automatic after-the-transfer verification has nothing to do with this option’s before-the-transfer “Does this file need to be updated?” check.

Code to loop through all records in MS Access

In "References", import DAO 3.6 object reference.

private sub showTableData

dim db as dao.database
dim rs as dao.recordset

set db = currentDb
set rs = db.OpenRecordSet("myTable") 'myTable is a MS-Access table created previously

'populate the table
rs.movelast
rs.movefirst

do while not rs.EOF
   debug.print(rs!myField) 'myField is a field name in table myTable
   rs.movenext             'press Ctrl+G to see debuG window beneath
loop

msgbox("End of Table")

end sub

You can interate data objects like queries and filtered tables in different ways:

Trhough query:

private sub showQueryData

dim db as dao.database
dim rs as dao.recordset
dim sqlStr as string

sqlStr = "SELECT * FROM customers as c WHERE c.country='Brazil'"

set db = currentDb
set rs = db.openRecordset(sqlStr)

rs.movefirst

do while not rs.EOF
  debug.print("cust ID: " & rs!id & " cust name: " & rs!name)
  rs.movenext
loop

msgbox("End of customers from Brazil")

end sub

You should also look for "Filter" property of the recordset object to filter only the desired records and then interact with them in the same way (see VB6 Help in MS-Access code window), or create a "QueryDef" object to run a query and use it as a recordset too (a little bit more tricky). Tell me if you want another aproach.

I hope I've helped.

What is a clearfix?

I tried out the accepted answer but I still had a problem with the content alignment. Adding a ":before" selector as shown below fixed the issue:

// LESS HELPER
.clearfix()
{
    &:after, &:before{
       content: " "; /* Older browser do not support empty content */
       visibility: hidden;
       display: block;
       height: 0;
       clear: both;
    }
}

LESS above will compile to CSS below:

clearfix:after,
clearfix:before {
  content: " ";
  /* Older browser do not support empty content */
  visibility: hidden;
  display: block;
  height: 0;
  clear: both;
}

shell script. how to extract string using regular expressions

Using bash regular expressions:

re="http://([^/]+)/"
if [[ $name =~ $re ]]; then echo ${BASH_REMATCH[1]}; fi

Edit - OP asked for explanation of syntax. Regular expression syntax is a large topic which I can't explain in full here, but I will attempt to explain enough to understand the example.

re="http://([^/]+)/"

This is the regular expression stored in a bash variable, re - i.e. what you want your input string to match, and hopefully extract a substring. Breaking it down:

  • http:// is just a string - the input string must contain this substring for the regular expression to match
  • [] Normally square brackets are used say "match any character within the brackets". So c[ao]t would match both "cat" and "cot". The ^ character within the [] modifies this to say "match any character except those within the square brackets. So in this case [^/] will match any character apart from "/".
  • The square bracket expression will only match one character. Adding a + to the end of it says "match 1 or more of the preceding sub-expression". So [^/]+ matches 1 or more of the set of all characters, excluding "/".
  • Putting () parentheses around a subexpression says that you want to save whatever matched that subexpression for later processing. If the language you are using supports this, it will provide some mechanism to retrieve these submatches. For bash, it is the BASH_REMATCH array.
  • Finally we do an exact match on "/" to make sure we match all the way to end of the fully qualified domain name and the following "/"

Next, we have to test the input string against the regular expression to see if it matches. We can use a bash conditional to do that:

if [[ $name =~ $re ]]; then
    echo ${BASH_REMATCH[1]}
fi

In bash, the [[ ]] specify an extended conditional test, and may contain the =~ bash regular expression operator. In this case we test whether the input string $name matches the regular expression $re. If it does match, then due to the construction of the regular expression, we are guaranteed that we will have a submatch (from the parentheses ()), and we can access it using the BASH_REMATCH array:

  • Element 0 of this array ${BASH_REMATCH[0]} will be the entire string matched by the regular expression, i.e. "http://www.google.com/".
  • Subsequent elements of this array will be subsequent results of submatches. Note you can have multiple submatch () within a regular expression - The BASH_REMATCH elements will correspond to these in order. So in this case ${BASH_REMATCH[1]} will contain "www.google.com", which I think is the string you want.

Note that the contents of the BASH_REMATCH array only apply to the last time the regular expression =~ operator was used. So if you go on to do more regular expression matches, you must save the contents you need from this array each time.

This may seem like a lengthy description, but I have really glossed over several of the intricacies of regular expressions. They can be quite powerful, and I believe with decent performance, but the regular expression syntax is complex. Also regular expression implementations vary, so different languages will support different features and may have subtle differences in syntax. In particular escaping of characters within a regular expression can be a thorny issue, especially when those characters would have an otherwise different meaning in the given language.


Note that instead of setting the $re variable on a separate line and referring to this variable in the condition, you can put the regular expression directly into the condition. However in bash 3.2, the rules were changed regarding whether quotes around such literal regular expressions are required or not. Putting the regular expression in a separate variable is a straightforward way around this, so that the condition works as expected in all bash versions that support the =~ match operator.

What are the different types of keys in RDBMS?

Partial Key:

It is a set of attributes that can uniquely identify weak entities and that are related to same owner entity. It is sometime called as Discriminator.

Alternate Key:

All Candidate Keys excluding the Primary Key are known as Alternate Keys.

Artificial Key:

If no obvious key, either stand alone or compound is available, then the last resort is to simply create a key, by assigning a unique number to each record or occurrence. Then this is known as developing an artificial key.

Compound Key:

If no single data element uniquely identifies occurrences within a construct, then combining multiple elements to create a unique identifier for the construct is known as creating a compound key.

Natural Key:

When one of the data elements stored within a construct is utilized as the primary key, then it is called the natural key.

Convert DataTable to IEnumerable<T>

Nothing wrong with that implementation. You might give the yield keyword a shot, see how you like it:

private IEnumerable<TankReading> ConvertToTankReadings(DataTable dataTable)
    {
        foreach (DataRow row in dataTable.Rows)
        {
            yield return new TankReading
                                  {
                                      TankReadingsID = Convert.ToInt32(row["TRReadingsID"]),
                                      TankID = Convert.ToInt32(row["TankID"]),
                                      ReadingDateTime = Convert.ToDateTime(row["ReadingDateTime"]),
                                      ReadingFeet = Convert.ToInt32(row["ReadingFeet"]),
                                      ReadingInches = Convert.ToInt32(row["ReadingInches"]),
                                      MaterialNumber = row["MaterialNumber"].ToString(),
                                      EnteredBy = row["EnteredBy"].ToString(),
                                      ReadingPounds = Convert.ToDecimal(row["ReadingPounds"]),
                                      MaterialID = Convert.ToInt32(row["MaterialID"]),
                                      Submitted = Convert.ToBoolean(row["Submitted"]),
                                  };
        }

    }

Also the AsEnumerable isn't necessary, as List<T> is already an IEnumerable<T>

Printing column separated by comma using Awk command line

Try this awk

awk -F, '{$0=$3}1' file
column3
  • , Divide fields by ,
  • $0=$3 Set the line to only field 3
  • 1 Print all out. (explained here)

This could also be used:

awk -F, '{print $3}' file

How to publish a website made by Node.js to Github Pages?

It's very simple steps to push your node js application from local to GitHub.

Steps:

  1. First create a new repository on GitHub
  2. Open Git CMD installed to your system (Install GitHub Desktop)
  3. Clone the repository to your system with the command: git clone repo-url
  4. Now copy all your application files to this cloned library if it's not there
  5. Get everything ready to commit: git add -A
  6. Commit the tracked changes and prepares them to be pushed to a remote repository: git commit -a -m "First Commit"
  7. Push the changes in your local repository to GitHub: git push origin master

Request string without GET arguments

Not everyone will find it simple, but I believe this to be the best way to go around it:

preg_match('/^[^\?]+/', $_SERVER['REQUEST_URI'], $return);
$url = 'http' . ('on' === $_SERVER['HTTPS'] ? 's' : '') . '://' . $_SERVER['HTTP_HOST'] . $return[0]


What is does is simply to go through the REQUEST_URI from the beginning of the string, then stop when it hits a "?" (which really, only should happen when you get to parameters).

Then you create the url and save it to $url:
When creating the $url... What we're doing is simply writing "http" then checking if https is being used, if it is, we also write "s", then we concatenate "://", concatenate the HTTP_HOST (the server, fx: "stackoverflow.com"), and concatenate the $return, which we found before, to that (it's an array, but we only want the first index in it... There can only ever be one index, since we're checking from the beginning of the string in the regex.).

I hope someone can use this...

PS. This has been confirmed to work while using SLIM to reroute the URL.

What is the right way to debug in iPython notebook?

I just discovered PixieDebugger. Even thought I have not yet had the time to test it, it really seems the most similar way to debug the way we're used in ipython with ipdb

enter image description here

It also has an "evaluate" tab

How to make button fill table cell

For starters:

<p align='center'>
<table width='100%'>
<tr>
<td align='center'><form><input type=submit value="click me" style="width:100%"></form></td>
</tr>
</table>
</p>

Note, if the width of the input button is 100%, you wont need the attribute "align='center'" anymore.

This would be the optimal solution:

<p align='center'>
<table width='100%'>
<tr>
<td><form><input type=submit value="click me" style="width:100%"></form></td>
</tr>
</table>
</p>

dd: How to calculate optimal blocksize?

I've found my optimal blocksize to be 8 MB (equal to disk cache?) I needed to wipe (some say: wash) the empty space on a disk before creating a compressed image of it. I used:

cd /media/DiskToWash/
dd if=/dev/zero of=zero bs=8M; rm zero

I experimented with values from 4K to 100M.

After letting dd to run for a while I killed it (Ctlr+C) and read the output:

36+0 records in
36+0 records out
301989888 bytes (302 MB) copied, 15.8341 s, 19.1 MB/s

As dd displays the input/output rate (19.1MB/s in this case) it's easy to see if the value you've picked is performing better than the previous one or worse.

My scores:

bs=   I/O rate
---------------
4K    13.5 MB/s
64K   18.3 MB/s
8M    19.1 MB/s <--- winner!
10M   19.0 MB/s
20M   18.6 MB/s
100M  18.6 MB/s   

Note: To check what your disk cache/buffer size is, you can use sudo hdparm -i /dev/sda

Start redis-server with config file

Okay, redis is pretty user friendly but there are some gotchas.

Here are just some easy commands for working with redis on Ubuntu:

install:

sudo apt-get install redis-server

start with conf:

sudo redis-server <path to conf>
sudo redis-server config/redis.conf

stop with conf:

redis-ctl shutdown

(not sure how this shuts down the pid specified in the conf. Redis must save the path to the pid somewhere on boot)

log:

tail -f /var/log/redis/redis-server.log

Also, various example confs floating around online and on this site were beyond useless. The best, sure fire way to get a compatible conf is to copy-paste the one your installation is already using. You should be able to find it here:

/etc/redis/redis.conf

Then paste it at <path to conf>, tweak as needed and you're good to go.

How to insert an object in an ArrayList at a specific position

You must handle ArrayIndexOutOfBounds by yourself when adding to a certain position.

For convenience, you may use this extension function in Kotlin

/**
 * Adds an [element] to index [index] or to the end of the List in case [index] is out of bounds
 */
fun <T> MutableList<T>.insert(index: Int, element: T) {
    if (index <= size) {
        add(index, element)
    } else {
        add(element)
    }
}

Check if property has attribute

If you are using .NET 3.5 you might try with Expression trees. It is safer than reflection:

class CustomAttribute : Attribute { }

class Program
{
    [Custom]
    public int Id { get; set; }

    static void Main()
    {
        Expression<Func<Program, int>> expression = p => p.Id;
        var memberExpression = (MemberExpression)expression.Body;
        bool hasCustomAttribute = memberExpression
            .Member
            .GetCustomAttributes(typeof(CustomAttribute), false).Length > 0;
    }
}

Error when using scp command "bash: scp: command not found"

Make sure the scp command is available on both sides - both on the client and on the server.

If this is Fedora or Red Hat Enterprise Linux and clones (CentOS), make sure this package is installed:

    yum -y install openssh-clients

If you work with Debian or Ubuntu and clones, install this package:

    apt-get install openssh-client

Again, you need to do this both on the server and the client, otherwise you can encounter "weird" error messages on your client: scp: command not found or similar although you have it locally. This already confused thousands of people, I guess :)

Access to Image from origin 'null' has been blocked by CORS policy

You're running into a CORS error.

Trying to access your file using the local file system doesn't work in your case.

Origin is null because it's your local file system. Could you possibly host this png file?

Suggestion:

Host these files to an AWS S3 bucket instead. Then you can use the http protocol rather than the file protocol. OR setup some http server on your local system and use http to your localhost to serve the files from if you want to keep everything local.

More Reading:

How CORS Works

postgres default timezone

Choose a timezone from:

SELECT * FROM pg_timezone_names;

And set as below given example:

ALTER DATABASE postgres SET timezone TO 'Europe/Berlin';

Use your DB name in place of postgres in above statement.

INSERT VALUES WHERE NOT EXISTS

Ingnoring the duplicated unique constraint isn't a solution?

INSERT IGNORE INTO tblSoftwareTitles...

How to write multiple conditions in Makefile.am with "else if"

ptomato's code can also be written in a cleaner manner like:

ifeq ($(TARGET_CPU),x86)
  TARGET_CPU_IS_X86 := 1
else ifeq ($(TARGET_CPU),x86_64)
  TARGET_CPU_IS_X86 := 1
else
  TARGET_CPU_IS_X86 := 0
endif

This doesn't answer OP's question but as it's the top result on google, I'm adding it here in case it's useful to anyone else.

What is the "right" way to iterate through an array in Ruby?

I think there is no one right way. There are a lot of different ways to iterate, and each has its own niche.

  • each is sufficient for many usages, since I don't often care about the indexes.
  • each_ with _index acts like Hash#each - you get the value and the index.
  • each_index - just the indexes. I don't use this one often. Equivalent to "length.times".
  • map is another way to iterate, useful when you want to transform one array into another.
  • select is the iterator to use when you want to choose a subset.
  • inject is useful for generating sums or products, or collecting a single result.

It may seem like a lot to remember, but don't worry, you can get by without knowing all of them. But as you start to learn and use the different methods, your code will become cleaner and clearer, and you'll be on your way to Ruby mastery.

nodejs mysql Error: Connection lost The server closed the connection

better solution is to use pool - ill handle this for you.

_x000D_
_x000D_
const pool = mysql.createPool({_x000D_
  host: 'localhost',_x000D_
  user: '--',_x000D_
  database: '---',_x000D_
  password: '----'_x000D_
});_x000D_
_x000D_
// ... later_x000D_
pool.query('select 1 + 1', (err, rows) => { /* */ });
_x000D_
_x000D_
_x000D_

https://github.com/sidorares/node-mysql2/issues/836

Is there a simple JavaScript slider?

script.aculo.us has a slider control that might be worth checking out.

Which characters are valid in CSS class names/selectors?

I’ve answered your question in-depth here: http://mathiasbynens.be/notes/css-escapes

The article also explains how to escape any character in CSS (and JavaScript), and I made a handy tool for this as well. From that page:

If you were to give an element an ID value of ~!@$%^&*()_+-=,./';:"?><[]{}|`#, the selector would look like this:

CSS:

<style>
  #\~\!\@\$\%\^\&\*\(\)\_\+-\=\,\.\/\'\;\:\"\?\>\<\[\]\\\{\}\|\`\#
  {
    background: hotpink;
  }
</style>

JavaScript:

<script>
  // document.getElementById or similar
  document.getElementById('~!@$%^&*()_+-=,./\';:"?><[]\\{}|`#');
  // document.querySelector or similar
  $('#\\~\\!\\@\\$\\%\\^\\&\\*\\(\\)\\_\\+-\\=\\,\\.\\/\\\'\\;\\:\\"\\?\\>\\<\\[\\]\\\\\\{\\}\\|\\`\\#');
</script>

How to pass variable number of arguments to printf/sprintf

You are looking for variadic functions. printf() and sprintf() are variadic functions - they can accept a variable number of arguments.

This entails basically these steps:

  1. The first parameter must give some indication of the number of parameters that follow. So in printf(), the "format" parameter gives this indication - if you have 5 format specifiers, then it will look for 5 more arguments (for a total of 6 arguments.) The first argument could be an integer (eg "myfunction(3, a, b, c)" where "3" signifies "3 arguments)

  2. Then loop through and retrieve each successive argument, using the va_start() etc. functions.

There are plenty of tutorials on how to do this - good luck!

How to sort a Pandas DataFrame by index?

Dataframes have a sort_index method which returns a copy by default. Pass inplace=True to operate in place.

import pandas as pd
df = pd.DataFrame([1, 2, 3, 4, 5], index=[100, 29, 234, 1, 150], columns=['A'])
df.sort_index(inplace=True)
print(df.to_string())

Gives me:

     A
1    4
29   2
100  1
150  5
234  3

Where to find the win32api module for Python?

I've found that UC Irvine has a great collection of python modules, pywin32 (win32api) being one of many listed there. I'm not sure how they do with keeping up with the latest versions of these modules but it hasn't let me down yet.

UC Irvine Python Extension Repository - http://www.lfd.uci.edu/~gohlke/pythonlibs

pywin32 module - http://www.lfd.uci.edu/~gohlke/pythonlibs/#pywin32

Working copy locked error in tortoise svn while committing

The accepted answer didn't work for me. To fix that issue, I had to right-click on the file that was locked, select repo-browser. This opened a popup with the files as they are on the SVN server. I then right-clicked on the locked file and selected break lock.

When I closed the repository browser, back on explorer I could finally commit!

How to force Docker for a clean build of an image

I would not recommend using --no-cache in your case.

You are running a couple of installations from step 3 to 9 (I would, by the way, prefer using a one liner) and if you don't want the overhead of re-running these steps each time you are building your image you can modify your Dockerfile with a temporary step prior to your wget instruction.

I use to do something like RUN ls . and change it to RUN ls ./ then RUN ls ./. and so on for each modification done on the tarball retrieved by wget

You can of course do something like RUN echo 'test1' > test && rm test increasing the number in 'test1 for each iteration.

It looks dirty, but as far as I know it's the most efficient way to continue benefiting from the cache system of Docker, which saves time when you have many layers...

Application_Start not firing?

Note : a nice easy alternative to using the inbuilt "Visual Studio Development Server" or IIS Express (e.g. because you are developing against IIS and have particular settings you need for proper functioning of your app) is to simply stay running run in IIS (I use the Custom Web Server + hosts file entry + IIS binding to same domain)

  1. wait for debugging session to fire up ok
  2. then just make a whitespace edit to the root web.config and save the file
  3. refresh your page (Ctrl + F5)

Your breakpoint should be hit nicely, and you can continue to debug in your natural IIS habitat. Great !

How to set up Android emulator proxy settings

Depending on which environment you are using to run the emulator, check the logs to see how the emulator is started. Mine is started as:

C:\Users\johan\AppData\Local\Android\Sdk\tools\emulator.exe -netdelay none -netspeed full -avd Nexus_5X_API_23

Then you add the -http-proxy option, in my case:

C:\Users\johan\AppData\Local\Android\Sdk\tools\emulator.exe -netdelay none -netspeed full -avd Nexus_5X_API_23 -http-proxy 192.168.0.22:8888

Managing large binary files with Git

Have a look at camlistore. It is not really Git-based, but I find it more appropriate for what you have to do.

How can I call a WordPress shortcode within a template?

Try this:

<?php 
/*
Template Name: [contact us]

*/
get_header();
echo do_shortcode('[CONTACT-US-FORM]'); 
?>

MySQL and GROUP_CONCAT() maximum length

The short answer: the setting needs to be setup when the connection to the MySQL server is established. For example, if using MYSQLi / PHP, it will look something like this:

$ myConn = mysqli_init(); 
$ myConn->options(MYSQLI_INIT_COMMAND, 'SET SESSION group_concat_max_len = 1000000');

Therefore, if you are using a home-brewed framework, well, you need to look for the place in the code when the connection is establish and provide a sensible value.

I am still using Codeigniter 3 on 2020, so in this framework, the code to add is in the application/system/database/drivers/mysqli/mysqli_driver.php, the function is named db_connect();

public function db_connect($persistent = FALSE)
    {
        // Do we have a socket path?
        if ($this->hostname[0] === '/')
        {
            $hostname = NULL;
            $port = NULL;
            $socket = $this->hostname;
        }
        else
        {
            $hostname = ($persistent === TRUE)
                ? 'p:'.$this->hostname : $this->hostname;
            $port = empty($this->port) ? NULL : $this->port;
            $socket = NULL;
        }

        $client_flags = ($this->compress === TRUE) ? MYSQLI_CLIENT_COMPRESS : 0;
        $this->_mysqli = mysqli_init();

        $this->_mysqli->options(MYSQLI_OPT_CONNECT_TIMEOUT, 10);
        $this->_mysqli->options(MYSQLI_INIT_COMMAND, 'SET SESSION group_concat_max_len = 1000000');

...
    }

A SELECT statement that assigns a value to a variable must not be combined with data-retrieval operations

Column values from the SELECT statement are assigned into @low and @day local variables; the @adjustedLow value is not assigned into any variable and it causes the problem:

The problem is here:

select 
    top 1 @low = low
    , @day = day
    , @adjustedLow  -- causes error!
--select high
from 
    securityquote sq
...

Detailed explanation and workaround: SQL Server Error Messages - Msg 141 - A SELECT statement that assigns a value to a variable must not be combined with data-retrieval operations.

C non-blocking keyboard input

On UNIX systems, you can use sigaction call to register a signal handler for SIGINT signal which represents the Control+C key sequence. The signal handler can set a flag which will be checked in the loop making it to break appropriately.

ASP.NET jQuery Ajax Calling Code-Behind Method

Firstly, you probably want to add a return false; to the bottom of your Submit() method in JavaScript (so it stops the submit, since you're handling it in AJAX).

You're connecting to the complete event, not the success event - there's a significant difference and that's why your debugging results aren't as expected. Also, I've never made the signature methods match yours, and I've always provided a contentType and dataType. For example:

$.ajax({
        type: "POST",
        url: "Default.aspx/OnSubmit",
        data: dataValue,                
        contentType: 'application/json; charset=utf-8',
        dataType: 'json',
        error: function (XMLHttpRequest, textStatus, errorThrown) {
            alert("Request: " + XMLHttpRequest.toString() + "\n\nStatus: " + textStatus + "\n\nError: " + errorThrown);
        },
        success: function (result) {
            alert("We returned: " + result);
        }
    });

Pointers in JavaScript?

I'm thinking that in contrary to C or any language with pointers :

/** Javascript **/
var o = {x:10,y:20};
var o2 = {z:50,w:200};
  • obviously in javascript you cannot access to objects o and o2 addresses in memory
  • but you can't compare their address neither : (no trivial possibility to sort them, and then access by dichotomy)

.

o == o2 // obviously false : not the same address in memory
o <= o2 // true !
o >= o2 // also true !!

that's a huge problem :

  • it means that you can list/manage every objects created (allocated) by your application,

  • from that huge list of objects, compute some information about these (how they are linked together for example)

  • but when you want to retrieve the information you created about a specific object, you cannot find it in your huge list by dichotomy : there is no unique identifier per object that could be used as a replacement of the real memory address

this finally means that this is a huge problem, if you want to write in javascript :

  • a javascript debugger / IDE
  • or a specially optimized garbage collector
  • a data structure drawer / analyzer

How to read a large file line by line?

The correct, fully Pythonic way to read a file is the following:

with open(...) as f:
    for line in f:
        # Do something with 'line'

The with statement handles opening and closing the file, including if an exception is raised in the inner block. The for line in f treats the file object f as an iterable, which automatically uses buffered I/O and memory management so you don't have to worry about large files.

There should be one -- and preferably only one -- obvious way to do it.

Add characters to a string in Javascript

var text ="";
for (var member in list) {
        text += list[member];
}

Remove accents/diacritics in a string in JavaScript

I used string.js's latinise() method, which lets you do it like this:

var output = S(input).latinise().toString();

ADB Install Fails With INSTALL_FAILED_TEST_ONLY

After searching and browsing all day, the only one works is adding

android.injected.testOnly=false

to the gradle.properties file

Jackson how to transform JsonNode to ArrayNode without casting?

Is there a method equivalent to getJSONArray in org.json so that I have proper error handling in case it isn't an array?

It depends on your input; i.e. the stuff you fetch from the URL. If the value of the "datasets" attribute is an associative array rather than a plain array, you will get a ClassCastException.

But then again, the correctness of your old version also depends on the input. In the situation where your new version throws a ClassCastException, the old version will throw JSONException. Reference: http://www.json.org/javadoc/org/json/JSONObject.html#getJSONArray(java.lang.String)

Android Studio doesn't start, fails saying components not installed

I'm in India, and my connection was not working properly. (I have internet, but sometime I have blank page on chrome, and I need to refresh)

I tried several time to restart android studio (almost 15 times). And now it's working.

Maybe you have same problem.

How can I selectively merge or pick changes from another branch in Git?

I like the previous 'git-interactive-merge' answer, but there's one easier. Let Git do this for you using a rebase combination of interactive and onto:

      A---C1---o---C2---o---o feature
     /
----o---o---o---o master

So the case is you want C1 and C2 from the 'feature' branch (branch point 'A'), but none of the rest for now.

# git branch temp feature
# git checkout master
# git rebase -i --onto HEAD A temp

Which, as in the previous answer, drops you in to the interactive editor where you select the 'pick' lines for C1 and C2 (as above). Save and quit, and then it will proceed with the rebase and give you branch 'temp' and also HEAD at master + C1 + C2:

      A---C1---o---C2---o---o feature
     /
----o---o---o---o-master--C1---C2 [HEAD, temp]

Then you can just update master to HEAD and delete the temp branch and you're good to go:

# git branch -f master HEAD
# git branch -d temp

How do I replace all line breaks in a string with <br /> elements?

Try

_x000D_
_x000D_
let s=`This is man._x000D_
_x000D_
     Man like dog._x000D_
     Man like to drink._x000D_
_x000D_
     Man is the king.`;_x000D_
     _x000D_
msg.innerHTML = s.replace(/\n/g,"<br />");
_x000D_
<div id="msg"></div>
_x000D_
_x000D_
_x000D_

Changing file permission in Python

FYI here is a function to convert a permission string with 9 characters (e.g. 'rwsr-x-wt') to a mask that can be used with os.chmod().

def perm2mask(p):
        
    assert len(p) == 9, 'Bad permission length'
    assert all(p[k] in 'rw-' for k in [0,1,3,4,6,7]), 'Bad permission format (read-write)'
    assert all(p[k] in 'xs-' for k in [2,5]), 'Bad permission format (execute)'
    assert p[8] in 'xt-', 'Bad permission format (execute other)'
    
    m = 0
    
    if p[0] == 'r': m |= stat.S_IRUSR 
    if p[1] == 'w': m |= stat.S_IWUSR 
    if p[2] == 'x': m |= stat.S_IXUSR 
    if p[2] == 's': m |= stat.S_IXUSR | stat.S_ISUID 
    
    if p[3] == 'r': m |= stat.S_IRGRP 
    if p[4] == 'w': m |= stat.S_IWGRP 
    if p[5] == 'x': m |= stat.S_IXGRP 
    if p[5] == 's': m |= stat.S_IXGRP | stat.S_ISGID 
    
    if p[6] == 'r': m |= stat.S_IROTH 
    if p[7] == 'w': m |= stat.S_IWOTH 
    if p[8] == 'x': m |= stat.S_IXOTH 
    if p[8] == 't': m |= stat.S_IXOTH | stat.S_ISVTX
    
    return m

Note that setting SUID/SGID/SVTX bits will automatically set the corresponding execute bit. Without this, the resulting permission would be invalid (ST characters).

How to stop C++ console application from exiting immediately?

Include conio.h and at the end of your code, before return 0, write _getch();

PHP Regex to check date is in YYYY-MM-DD format

To work with dates in php you should follow the php standard so the given regex will assure that you have valid date that can operate with PHP.

    preg_match("/^([0-9]{4})-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])$/",$date)

jQuery: Adding two attributes via the .attr(); method

Multiple Attribute

var tag = "tag name";
createNode(tag, target, attribute);

createNode: function(tag, target, attribute){
    var tag = jQuery("<" + tag + ">");
    jQuery.each(attribute, function(i,v){
        tag.attr(v);
    });
    target.append(tag);
    tag.appendTo(target);
}
var attribute = [
    {"data-level": "3"},
];

What is the correct way to read from NetworkStream in .NET

As per your requirement, Thread.Sleep is perfectly fine to use because you are not sure when the data will be available so you might need to wait for the data to become available. I have slightly changed the logic of your function this might help you little further.

string SendCmd(string cmd, string ip, int port)
{
    var client = new TcpClient(ip, port);
    var data = Encoding.GetEncoding(1252).GetBytes(cmd);
    var stm = client.GetStream();
    stm.Write(data, 0, data.Length);
    byte[] resp = new byte[2048];
    var memStream = new MemoryStream();

    int bytes = 0;

    do
    {
        bytes = 0;
        while (!stm.DataAvailable)
            Thread.Sleep(20); // some delay
        bytes = stm.Read(resp, 0, resp.Length);
        memStream.Write(resp, 0, bytes);
    } 
    while (bytes > 0);

    return Encoding.GetEncoding(1252).GetString(memStream.ToArray());
}

Hope this helps!

Run Android studio emulator on AMD processor

Open Android AVD Manager: Tools -> Android -> AVD Manager and create an emulator:

  • Create Virtual Device
  • Choose any hardware
  • Now in system image you need to click on the "Other Images" tab
  • Select an image to install. IMPORTANT: Notice that for AMD in the "ABI" column it has to say: ARM EABI v7a or ARM 64 v8a
  • Install it and restart Android Studio

This works for me.

Switch statement multiple cases in JavaScript

The problem with the above approaches, is that you have to repeat the several cases every time you call the function which has the switch. A more robust solution is to have a map or a dictionary.

Here is an example:

_x000D_
_x000D_
// The Map, divided by concepts
var dictionary = {
  timePeriod: {
    'month': [1, 'monthly', 'mensal', 'mês'],
    'twoMonths': [2, 'two months', '2 months', 'bimestral', 'bimestre'],
    'trimester': [3, 'trimesterly', 'quarterly', 'trimestral'],
    'semester': [4, 'semesterly', 'semestral', 'halfyearly'],
    'year': [5, 'yearly', 'annual', 'ano']
  },
  distance: {
    'km': [1, 'kms', 'kilometre', 'kilometers', 'kilometres'],
    'mile': [2, 'mi', 'miles'],
    'nordicMile': [3, 'Nordic mile', 'mil (10 km)', 'Scandinavian mile']
  },
  fuelAmount: {
    'ltr': [1, 'l', 'litre', 'Litre', 'liter', 'Liter'],
    'gal (imp)': [2, 'imp gallon', 'imperial gal', 'gal (UK)'],
    'gal (US)': [3, 'US gallon', 'US gal'],
    'kWh': [4, 'KWH']
  }
};

// This function maps every input to a certain defined value
function mapUnit (concept, value) {
  for (var key in dictionary[concept]) {
    if (key === value ||
      dictionary[concept][key].indexOf(value) !== -1) {
      return key
    }
  }
  throw Error('Uknown "'+value+'" for "'+concept+'"')
}

// You would use it simply like this
mapUnit("fuelAmount", "ltr") // => ltr
mapUnit("fuelAmount", "US gal") // => gal (US)
mapUnit("fuelAmount", 3) // => gal (US)
mapUnit("distance", "kilometre") // => km

// Now you can use the switch statement safely without the need
// to repeat the combinations every time you call the switch
var foo = 'monthly'
switch (mapUnit ('timePeriod', foo)) {
  case 'month':
    console.log('month')
    break
  case 'twoMonths':
    console.log('twoMonths')
    break
  case 'trimester':
    console.log('trimester')
    break
  case 'semester':
    console.log('semester')
    break
  case 'year':
    console.log('year')
    break
  default:
    throw Error('error')
}
_x000D_
_x000D_
_x000D_

Color theme for VS Code integrated terminal

VSCode comes with in-built color themes which can be used to change the colors of the editor and the terminal.

  • For changing the color theme press ctrl+k+t in windows/ubuntu or cmd+k+t on mac.
  • Alternatively you can open command palette by pressing ctrl+shift+p in windows/ubuntu or cmd+shift+p on mac and type color. Select preferences: color theme from the options, to select your favourite color.
  • You can also install more themes from the extensions menu on the left bar. just search category:themes to install your favourite themes. (If you need to sort the themes by installs search category:themes @sort:installs)

Edit - for manually editing colors in terminal

VSCode team have removed customizing colors from user settings page. Currently using the themes is the only way to customize terminal colors in VSCode. For more information check out issue #6766

TypeError: 'tuple' object does not support item assignment when swapping values

Evaluating "1,2,3" results in (1, 2, 3), a tuple. As you've discovered, tuples are immutable. Convert to a list before processing.

Passing parameters to a JQuery function

If you want to do an ajax call or a simple javascript function, don't forget to close your function with the return false

like this:

function DoAction(id, name) 
{ 
    // your code
    return false;
}

What is an Endpoint?

API stands for Application Programming Interface. It is a way for your application to interact with other applications via an endpoint. Conversely, you can build out an API for your application that is available for other developers to utilize/connect to via HTTP methods, which are RESTful. Representational State Transfer (REST):

  • GET: Retrieve data from an API endpoint.
  • PUT: Update data via an API - similar to POST but more about updating info.
  • POST: Send data to an API.
  • DELETE: Remove data from given API.

How do I unload (reload) a Python module?

This is the modern way of reloading a module:

from importlib import reload

If you want to support versions of Python older than 3.5, try this:

from sys import version_info
if version_info[0] < 3:
    pass # Python 2 has built in reload
elif version_info[0] == 3 and version_info[1] <= 4:
    from imp import reload # Python 3.0 - 3.4 
else:
    from importlib import reload # Python 3.5+

To use it, run reload(MODULE), replacing MODULE with the module you want to reload.

For example, reload(math) will reload the math module.

How to redirect stderr and stdout to different files in the same line in script?

Or if you like to mix outputs (stdout & stderr) in one single file you may want to use:

command > merged-output.txt 2>&1

How do I tokenize a string in C++?

I posted this answer for similar question.
Don't reinvent the wheel. I've used a number of libraries and the fastest and most flexible I have come across is: C++ String Toolkit Library.

Here is an example of how to use it that I've posted else where on the stackoverflow.

#include <iostream>
#include <vector>
#include <string>
#include <strtk.hpp>

const char *whitespace  = " \t\r\n\f";
const char *whitespace_and_punctuation  = " \t\r\n\f;,=";

int main()
{
    {   // normal parsing of a string into a vector of strings
       std::string s("Somewhere down the road");
       std::vector<std::string> result;
       if( strtk::parse( s, whitespace, result ) )
       {
           for(size_t i = 0; i < result.size(); ++i )
            std::cout << result[i] << std::endl;
       }
    }

    {  // parsing a string into a vector of floats with other separators
       // besides spaces

       std::string s("3.0, 3.14; 4.0");
       std::vector<float> values;
       if( strtk::parse( s, whitespace_and_punctuation, values ) )
       {
           for(size_t i = 0; i < values.size(); ++i )
            std::cout << values[i] << std::endl;
       }
    }

    {  // parsing a string into specific variables

       std::string s("angle = 45; radius = 9.9");
       std::string w1, w2;
       float v1, v2;
       if( strtk::parse( s, whitespace_and_punctuation, w1, v1, w2, v2) )
       {
           std::cout << "word " << w1 << ", value " << v1 << std::endl;
           std::cout << "word " << w2 << ", value " << v2 << std::endl;
       }
    }

    return 0;
}

Easy login script without database

if you dont have a database, you will have to hardcode the login details in your code, or read it from a flat file on disk.

Change image size with JavaScript

Once you have a reference to your image, you can set its height and width like so:

var yourImg = document.getElementById('yourImgId');
if(yourImg && yourImg.style) {
    yourImg.style.height = '100px';
    yourImg.style.width = '200px';
}

In the html, it would look like this:

<img src="src/to/your/img.jpg" id="yourImgId" alt="alt tags are key!"/>

How to get the background color code of an element in hex?

Check example link below and click on the div to get the color value in hex.

_x000D_
_x000D_
var color = '';_x000D_
$('div').click(function() {_x000D_
  var x = $(this).css('backgroundColor');_x000D_
  hexc(x);_x000D_
  console.log(color);_x000D_
})_x000D_
_x000D_
function hexc(colorval) {_x000D_
  var parts = colorval.match(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/);_x000D_
  delete(parts[0]);_x000D_
  for (var i = 1; i <= 3; ++i) {_x000D_
    parts[i] = parseInt(parts[i]).toString(16);_x000D_
    if (parts[i].length == 1) parts[i] = '0' + parts[i];_x000D_
  }_x000D_
  color = '#' + parts.join('');_x000D_
}
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>_x000D_
<div class='div' style='background-color: #f5b405'>Click me!</div>
_x000D_
_x000D_
_x000D_

Check working example at http://jsfiddle.net/DCaQb/

How to combine multiple inline style objects?

So basically I'm looking at this in the wrong way. From what I see, this is not a React specific question, more of a JavaScript question in how do I combine two JavaScript objects together (without clobbering similarly named properties).

In this StackOverflow answer it explains it. How can I merge properties of two JavaScript objects dynamically?

In jQuery I can use the extend method.

Java equivalent to C# extension methods

You can create a C# like extension/helper method by (RE) implementing the Collections interface and adding- example for Java Collection:

public class RockCollection<T extends Comparable<T>> implements Collection<T> {
private Collection<T> _list = new ArrayList<T>();

//###########Custom extension methods###########

public T doSomething() {
    //do some stuff
    return _list  
}

//proper examples
public T find(Predicate<T> predicate) {
    return _list.stream()
            .filter(predicate)
            .findFirst()
            .get();
}

public List<T> findAll(Predicate<T> predicate) {
    return _list.stream()
            .filter(predicate)
            .collect(Collectors.<T>toList());
}

public String join(String joiner) {
    StringBuilder aggregate = new StringBuilder("");
    _list.forEach( item ->
        aggregate.append(item.toString() + joiner)
    );
    return aggregate.toString().substring(0, aggregate.length() - 1);
}

public List<T> reverse() {
    List<T> listToReverse = (List<T>)_list;
    Collections.reverse(listToReverse);
    return listToReverse;
}

public List<T> sort(Comparator<T> sortComparer) {
    List<T> listToReverse = (List<T>)_list;
    Collections.sort(listToReverse, sortComparer);
    return listToReverse;
}

public int sum() {
    List<T> list = (List<T>)_list;
    int total = 0;
    for (T aList : list) {
        total += Integer.parseInt(aList.toString());
    }
    return total;
}

public List<T> minus(RockCollection<T> listToMinus) {
    List<T> list = (List<T>)_list;
    int total = 0;
    listToMinus.forEach(list::remove);
    return list;
}

public Double average() {
    List<T> list = (List<T>)_list;
    Double total = 0.0;
    for (T aList : list) {
        total += Double.parseDouble(aList.toString());
    }
    return total / list.size();
}

public T first() {
    return _list.stream().findFirst().get();
            //.collect(Collectors.<T>toList());
}
public T last() {
    List<T> list = (List<T>)_list;
    return list.get(_list.size() - 1);
}
//##############################################
//Re-implement existing methods
@Override
public int size() {
    return _list.size();
}

@Override
public boolean isEmpty() {
    return _list == null || _list.size() == 0;
}

Which is the correct C# infinite loop, for (;;) or while (true)?

Personally, I have always preferred for(;;) precisely because it has no condition (as opposed to while (true) which has an always-true one). However, this is really a very minor style point, which I don't feel is worth arguing about either way. I've yet to see a C# style guideline that mandated or forbade either approach.

Jquery Smooth Scroll To DIV - Using ID value from Link

You can do this:

$('.searchbychar').click(function () {
    var divID = '#' + this.id;
    $('html, body').animate({
        scrollTop: $(divID).offset().top
    }, 2000);
});

F.Y.I.

  • You need to prefix a class name with a . (dot) like in your first line of code.
  • $( 'searchbychar' ).click(function() {
  • Also, your code $('.searchbychar').attr('id') will return a string ID not a jQuery object. Hence, you can not apply .offset() method to it.

What causes HttpHostConnectException?

A "connection refused" error happens when you attempt to open a TCP connection to an IP address / port where there is nothing currently listening for connections. If nothing is listening, the OS on the server side "refuses" the connection.

If this is happening intermittently, then the most likely explanations are (IMO):

  • the server you are talking ("proxy.xyz.com" / port 60) to is going up and down, OR
  • there is something1 between your client and the proxy that is intermittently sending requests to a non-functioning host, or something.

Is this possible that this exception is caused when a search request is made from Android applications as our website don't support a request is being made from android applications.

It seems unlikely. You said that the "connection refused" exception message says that it is the proxy that is refusing the connection, not your server. Besides if a server was going to not handle certain kinds of request, it still has to accept the TCP connection to find out what the request is ... before it can reject it.


1 - For example, it could be a DNS that round-robin resolves the DNS name to different IP addresses. Or it could be an IP-based load balancer.

pip install failing with: OSError: [Errno 13] Permission denied on directory

So, I got this same exact error for a completely different reason. Due to a totally separate, but known Homebrew + pip bug, I had followed this workaround listed on Google Cloud's help docs, where you create a .pydistutils.cfg file in your home directory. This file has special config that you're only supposed to use for your install of certain libraries. I should have removed that disutils.cfg file after installing the packages, but I forgot to do so. So the fix for me was actually just...

rm ~/.pydistutils.cfg.

And then everything worked as normal. Of course, if you have some config in that file for a real reason, then you won't want to just straight rm that file. But in case anyone else did that workaround, and forgot to remove that file, this did the trick for me!

Tomcat 7 is not running on browser(http://localhost:8080/ )

There could be a number of reasons, have it as a checklist and go through it

Is your server running on 8080?I mean that is the default port but it could be configured to run on other.

Also there is a possibility that the default application is removed/uninstalled that is why it is giving "the requested resource is not available"

Also it could be a proxy issue. make sure you are not using any proxy in your browser.

Get the value in an input text box

You can only select a value with the following two ways:

// First way to get a value
value = $("#txt_name").val(); 

// Second way to get a value
value = $("#txt_name").attr('value');

If you want to use straight JavaScript to get the value, here is how:

document.getElementById('txt_name').value 

How can I get the assembly file version

Use this:

((AssemblyFileVersionAttribute)Attribute.GetCustomAttribute(
    Assembly.GetExecutingAssembly(), 
    typeof(AssemblyFileVersionAttribute), false)
).Version;

Or this:

new Version(System.Windows.Forms.Application.ProductVersion);

How do I add a newline to a windows-forms TextBox?

First you have to set the MultiLine property of the TextBox to true so that it supports multiple lines.

Then you just use Environment.NewLine to get the newline character combination.

git ignore exception

If you're working with Visual Studio and your .dll happens to be in a bin folder, then you'll need to add an exception for the particular bin folder itself, before you can add the exception for the .dll file. E.g.

!SourceCode/Solution/Project/bin
!SourceCode/Solution/Project/bin/My.dll

This is because the default Visual Studio .gitignore file includes an ignore pattern for [Bbin]/

This pattern is zapping all bin folders (and consequently their contents), which makes any attempt to include the contents redundant (since the folder itself is already ignored).

I was able to find why my file wasn't being excepted by running

git check-ignore -v -- SourceCode/Solution/Project/bin/My.dll

from a Git Bash window. This returned the [Bbin]/ pattern.

How to define Gradle's home in IDEA?

If you are using IntelliJ, just do the following.

  1. Close the project
  2. (re)Open the project
  3. you will see "Import gradle project" message on the right bottom. click.
  4. select "Use default gradle wrapper". not "Use local gradle distribution"

enter image description here

That's all.

Find CRLF in Notepad++

Maybe you can use TextFX plugins

In TextFX, go to textfx edit ? delete blank lines

How to use onResume()?

Any Activity that restarts has its onResume() method executed first.

To use this method, do this:

@Override
public void onResume(){
    super.onResume();
    // put your code here...

}

How do I create a new column from the output of pandas groupby().sum()?

How do I create a new column with Groupby().Sum()?

There are two ways - one straightforward and the other slightly more interesting.


Everybody's Favorite: GroupBy.transform() with 'sum'

@Ed Chum's answer can be simplified, a bit. Call DataFrame.groupby rather than Series.groupby. This results in simpler syntax.

# The setup.
df[['Date', 'Data3']]

         Date  Data3
0  2015-05-08      5
1  2015-05-07      8
2  2015-05-06      6
3  2015-05-05      1
4  2015-05-08     50
5  2015-05-07    100
6  2015-05-06     60
7  2015-05-05    120

df.groupby('Date')['Data3'].transform('sum')

0     55
1    108
2     66
3    121
4     55
5    108
6     66
7    121
Name: Data3, dtype: int64 

It's a tad faster,

df2 = pd.concat([df] * 12345)

%timeit df2['Data3'].groupby(df['Date']).transform('sum')
%timeit df2.groupby('Date')['Data3'].transform('sum')

10.4 ms ± 367 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)
8.58 ms ± 559 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)

Unconventional, but Worth your Consideration: GroupBy.sum() + Series.map()

I stumbled upon an interesting idiosyncrasy in the API. From what I tell, you can reproduce this on any major version over 0.20 (I tested this on 0.23 and 0.24). It seems like you consistently can shave off a few milliseconds of the time taken by transform if you instead use a direct function of GroupBy and broadcast it using map:

df.Date.map(df.groupby('Date')['Data3'].sum())

0     55
1    108
2     66
3    121
4     55
5    108
6     66
7    121
Name: Date, dtype: int64

Compare with

df.groupby('Date')['Data3'].transform('sum')

0     55
1    108
2     66
3    121
4     55
5    108
6     66
7    121
Name: Data3, dtype: int64

My tests show that map is a bit faster if you can afford to use the direct GroupBy function (such as mean, min, max, first, etc). It is more or less faster for most general situations upto around ~200 thousand records. After that, the performance really depends on the data.

(Left: v0.23, Right: v0.24)

Nice alternative to know, and better if you have smaller frames with smaller numbers of groups. . . but I would recommend transform as a first choice. Thought this was worth sharing anyway.

Benchmarking code, for reference:

import perfplot

perfplot.show(
    setup=lambda n: pd.DataFrame({'A': np.random.choice(n//10, n), 'B': np.ones(n)}),
    kernels=[
        lambda df: df.groupby('A')['B'].transform('sum'),
        lambda df:  df.A.map(df.groupby('A')['B'].sum()),
    ],
    labels=['GroupBy.transform', 'GroupBy.sum + map'],
    n_range=[2**k for k in range(5, 20)],
    xlabel='N',
    logy=True,
    logx=True
)

Why is NULL undeclared?

Are you including "stdlib.h" or "cstdlib" in this file? NULL is defined in stdlib.h/cstdlib

#include <stdlib.h>

or

#include <cstdlib>  // This is preferrable for c++

How to remove an iOS app from the App Store

What you need to do is this.

  1. Go to “Manage Your Applications” and select the app.
  2. Click “Rights and Pricing” (blue button at the top right.
  3. Below the availability date and price tier section, you should see a grid of checkboxes for the various countries your app is available in. Click the blue “Deselect All” button.
  4. Click “Save Changes” at the bottom.

Your app's state will then be “Developer Removed From Sale”, and it will no longer be available on the App Store in any country.

Java, "Variable name" cannot be resolved to a variable

If you look at the scope of the variable 'hoursWorked' you will see that it is a member of the class (declared as private int)

The two variables you are having trouble with are passed as parameters to the constructor.

The error message is because 'hours' is out of scope in the setter.

var.replace is not a function

My guess is that the code that's calling your trim function is not actually passing a string to it.

To fix this, you can make str a string, like this: str.toString().replace(...)
...as alper pointed out below.

Laravel 5 show ErrorException file_put_contents failed to open stream: No such file or directory

Apache + WSL on windows

This is a silly mistake, and a different answer compared to the others, but I'll add it because it happened to me.

If you use WSL (linux bash on windows) to manage your laravel application, while using your windows apache to run your server, then running any caching commands in the wsl will store the linux path rather than the windows path to the sessions and other folders.

Solution

Simply run the cache clearing commands in the powershell, rather than in WSL.

$ php artisan optimize

Was enough for me.

How to access POST form fields

from official doc version 4

const express = require('express')
const app = express()
app.use(express.json());
app.use(express.urlencoded({ extended: true })) 

app.post('/push/send', (request, response) => {
  console.log(request.body)
})

How to abort an interactive rebase if --abort doesn't work?

Try to follow the advice you see on the screen, and first reset your master's HEAD to the commit it expects.

git update-ref refs/heads/master b918ac16a33881ce00799bea63d9c23bf7022d67

Then, abort the rebase again.

Sending string via socket (python)

import socket
from threading import *

serversocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
host = "192.168.1.3"
port = 8000
print (host)
print (port)
serversocket.bind((host, port))

class client(Thread):
    def __init__(self, socket, address):
        Thread.__init__(self)
        self.sock = socket
        self.addr = address
        self.start()

    def run(self):
        while 1:
            print('Client sent:', self.sock.recv(1024).decode())
            self.sock.send(b'Oi you sent something to me')

serversocket.listen(5)
print ('server started and listening')
while 1:
    clientsocket, address = serversocket.accept()
    client(clientsocket, address)

This is a very VERY simple design for how you could solve it. First of all, you need to either accept the client (server side) before going into your while 1 loop because in every loop you accept a new client, or you do as i describe, you toss the client into a separate thread which you handle on his own from now on.

How do I determine the size of an object in Python?

How do I determine the size of an object in Python?

The answer, "Just use sys.getsizeof", is not a complete answer.

That answer does work for builtin objects directly, but it does not account for what those objects may contain, specifically, what types, such as custom objects, tuples, lists, dicts, and sets contain. They can contain instances each other, as well as numbers, strings and other objects.

A More Complete Answer

Using 64-bit Python 3.6 from the Anaconda distribution, with sys.getsizeof, I have determined the minimum size of the following objects, and note that sets and dicts preallocate space so empty ones don't grow again until after a set amount (which may vary by implementation of the language):

Python 3:

Empty
Bytes  type        scaling notes
28     int         +4 bytes about every 30 powers of 2
37     bytes       +1 byte per additional byte
49     str         +1-4 per additional character (depending on max width)
48     tuple       +8 per additional item
64     list        +8 for each additional
224    set         5th increases to 736; 21nd, 2272; 85th, 8416; 341, 32992
240    dict        6th increases to 368; 22nd, 1184; 43rd, 2280; 86th, 4704; 171st, 9320
136    func def    does not include default args and other attrs
1056   class def   no slots 
56     class inst  has a __dict__ attr, same scaling as dict above
888    class def   with slots
16     __slots__   seems to store in mutable tuple-like structure
                   first slot grows to 48, and so on.

How do you interpret this? Well say you have a set with 10 items in it. If each item is 100 bytes each, how big is the whole data structure? The set is 736 itself because it has sized up one time to 736 bytes. Then you add the size of the items, so that's 1736 bytes in total

Some caveats for function and class definitions:

Note each class definition has a proxy __dict__ (48 bytes) structure for class attrs. Each slot has a descriptor (like a property) in the class definition.

Slotted instances start out with 48 bytes on their first element, and increase by 8 each additional. Only empty slotted objects have 16 bytes, and an instance with no data makes very little sense.

Also, each function definition has code objects, maybe docstrings, and other possible attributes, even a __dict__.

Also note that we use sys.getsizeof() because we care about the marginal space usage, which includes the garbage collection overhead for the object, from the docs:

getsizeof() calls the object’s __sizeof__ method and adds an additional garbage collector overhead if the object is managed by the garbage collector.

Also note that resizing lists (e.g. repetitively appending to them) causes them to preallocate space, similarly to sets and dicts. From the listobj.c source code:

    /* This over-allocates proportional to the list size, making room
     * for additional growth.  The over-allocation is mild, but is
     * enough to give linear-time amortized behavior over a long
     * sequence of appends() in the presence of a poorly-performing
     * system realloc().
     * The growth pattern is:  0, 4, 8, 16, 25, 35, 46, 58, 72, 88, ...
     * Note: new_allocated won't overflow because the largest possible value
     *       is PY_SSIZE_T_MAX * (9 / 8) + 6 which always fits in a size_t.
     */
    new_allocated = (size_t)newsize + (newsize >> 3) + (newsize < 9 ? 3 : 6);

Historical data

Python 2.7 analysis, confirmed with guppy.hpy and sys.getsizeof:

Bytes  type        empty + scaling notes
24     int         NA
28     long        NA
37     str         + 1 byte per additional character
52     unicode     + 4 bytes per additional character
56     tuple       + 8 bytes per additional item
72     list        + 32 for first, 8 for each additional
232    set         sixth item increases to 744; 22nd, 2280; 86th, 8424
280    dict        sixth item increases to 1048; 22nd, 3352; 86th, 12568 *
120    func def    does not include default args and other attrs
64     class inst  has a __dict__ attr, same scaling as dict above
16     __slots__   class with slots has no dict, seems to store in 
                    mutable tuple-like structure.
904    class def   has a proxy __dict__ structure for class attrs
104    old class   makes sense, less stuff, has real dict though.

Note that dictionaries (but not sets) got a more compact representation in Python 3.6

I think 8 bytes per additional item to reference makes a lot of sense on a 64 bit machine. Those 8 bytes point to the place in memory the contained item is at. The 4 bytes are fixed width for unicode in Python 2, if I recall correctly, but in Python 3, str becomes a unicode of width equal to the max width of the characters.

And for more on slots, see this answer.

A More Complete Function

We want a function that searches the elements in lists, tuples, sets, dicts, obj.__dict__'s, and obj.__slots__, as well as other things we may not have yet thought of.

We want to rely on gc.get_referents to do this search because it works at the C level (making it very fast). The downside is that get_referents can return redundant members, so we need to ensure we don't double count.

Classes, modules, and functions are singletons - they exist one time in memory. We're not so interested in their size, as there's not much we can do about them - they're a part of the program. So we'll avoid counting them if they happen to be referenced.

We're going to use a blacklist of types so we don't include the entire program in our size count.

import sys
from types import ModuleType, FunctionType
from gc import get_referents

# Custom objects know their class.
# Function objects seem to know way too much, including modules.
# Exclude modules as well.
BLACKLIST = type, ModuleType, FunctionType


def getsize(obj):
    """sum size of object & members."""
    if isinstance(obj, BLACKLIST):
        raise TypeError('getsize() does not take argument of type: '+ str(type(obj)))
    seen_ids = set()
    size = 0
    objects = [obj]
    while objects:
        need_referents = []
        for obj in objects:
            if not isinstance(obj, BLACKLIST) and id(obj) not in seen_ids:
                seen_ids.add(id(obj))
                size += sys.getsizeof(obj)
                need_referents.append(obj)
        objects = get_referents(*need_referents)
    return size

To contrast this with the following whitelisted function, most objects know how to traverse themselves for the purposes of garbage collection (which is approximately what we're looking for when we want to know how expensive in memory certain objects are. This functionality is used by gc.get_referents.) However, this measure is going to be much more expansive in scope than we intended if we are not careful.

For example, functions know quite a lot about the modules they are created in.

Another point of contrast is that strings that are keys in dictionaries are usually interned so they are not duplicated. Checking for id(key) will also allow us to avoid counting duplicates, which we do in the next section. The blacklist solution skips counting keys that are strings altogether.

Whitelisted Types, Recursive visitor (old implementation)

To cover most of these types myself, instead of relying on the gc module, I wrote this recursive function to try to estimate the size of most Python objects, including most builtins, types in the collections module, and custom types (slotted and otherwise).

This sort of function gives much more fine-grained control over the types we're going to count for memory usage, but has the danger of leaving types out:

import sys
from numbers import Number
from collections import Set, Mapping, deque

try: # Python 2
    zero_depth_bases = (basestring, Number, xrange, bytearray)
    iteritems = 'iteritems'
except NameError: # Python 3
    zero_depth_bases = (str, bytes, Number, range, bytearray)
    iteritems = 'items'

def getsize(obj_0):
    """Recursively iterate to sum size of object & members."""
    _seen_ids = set()
    def inner(obj):
        obj_id = id(obj)
        if obj_id in _seen_ids:
            return 0
        _seen_ids.add(obj_id)
        size = sys.getsizeof(obj)
        if isinstance(obj, zero_depth_bases):
            pass # bypass remaining control flow and return
        elif isinstance(obj, (tuple, list, Set, deque)):
            size += sum(inner(i) for i in obj)
        elif isinstance(obj, Mapping) or hasattr(obj, iteritems):
            size += sum(inner(k) + inner(v) for k, v in getattr(obj, iteritems)())
        # Check for custom object instances - may subclass above too
        if hasattr(obj, '__dict__'):
            size += inner(vars(obj))
        if hasattr(obj, '__slots__'): # can have __slots__ with __dict__
            size += sum(inner(getattr(obj, s)) for s in obj.__slots__ if hasattr(obj, s))
        return size
    return inner(obj_0)

And I tested it rather casually (I should unittest it):

>>> getsize(['a', tuple('bcd'), Foo()])
344
>>> getsize(Foo())
16
>>> getsize(tuple('bcd'))
194
>>> getsize(['a', tuple('bcd'), Foo(), {'foo': 'bar', 'baz': 'bar'}])
752
>>> getsize({'foo': 'bar', 'baz': 'bar'})
400
>>> getsize({})
280
>>> getsize({'foo':'bar'})
360
>>> getsize('foo')
40
>>> class Bar():
...     def baz():
...         pass
>>> getsize(Bar())
352
>>> getsize(Bar().__dict__)
280
>>> sys.getsizeof(Bar())
72
>>> getsize(Bar.__dict__)
872
>>> sys.getsizeof(Bar.__dict__)
280

This implementation breaks down on class definitions and function definitions because we don't go after all of their attributes, but since they should only exist once in memory for the process, their size really doesn't matter too much.

Check if pull needed in Git

After reading many answers and multiple posts, and spending half a day trying various permutations, this is what I have come up with.

If you are on Windows, you may run this script in Windows using Git Bash provided by Git for Windows (installation or portable).

This script requires arguments

- local path e.g. /d/source/project1
- Git URL e.g. https://[email protected]/username/project1.git
- password

if a password should not be entered on the command line in plain text,
then modify the script to check if GITPASS is empty; do not
replace and let Git prompt for a password

The script will

- Find the current branch
- Get the SHA1 of the remote on that branch
- Get the SHA1 of the local on that branch
- Compare them.

If there is a change as printed by the script, then you may proceed to fetch or pull. The script may not be efficient, but it gets the job done for me.

Update - 2015-10-30: stderr to dev null to prevent printing the URL with the password to the console.

#!/bin/bash

# Shell script to check if a Git pull is required.

LOCALPATH=$1
GITURL=$2
GITPASS=$3

cd $LOCALPATH
BRANCH="$(git rev-parse --abbrev-ref HEAD)"

echo
echo git url = $GITURL
echo branch = $BRANCH

# Bash replace - replace @ with :password@ in the GIT URL
GITURL2="${GITURL/@/:$GITPASS@}"
FOO="$(git ls-remote $GITURL2 -h $BRANCH 2> /dev/null)"
if [ "$?" != "0" ]; then
  echo cannot get remote status
  exit 2
fi
FOO_ARRAY=($FOO)
BAR=${FOO_ARRAY[0]}
echo [$BAR]

LOCALBAR="$(git rev-parse HEAD)"
echo [$LOCALBAR]
echo

if [ "$BAR" == "$LOCALBAR" ]; then
  #read -t10 -n1 -r -p 'Press any key in the next ten seconds...' key
  echo No changes
  exit 0
else
  #read -t10 -n1 -r -p 'Press any key in the next ten seconds...' key
  #echo pressed $key
  echo There are changes between local and remote repositories.
  exit 1
fi

Eloquent Collection: Counting and Detect Empty

so Laravel actually returns a collection when just using Model::all(); you don't want a collection you want an array so you can type set it. (array)Model::all(); then you can use array_filter to return the results

$models = (array)Model::all()
$models = array_filter($models);
if(empty($models))
{
 do something
}

this will also allow you to do things like count().

Android Material: Status bar color won't change

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
    getWindow().addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
    getWindow().setStatusBarColor(getResources().getColor(R.color.actionbar));
}

Put this code in your Activity's onCreate method. This helped me.

Why does CSV file contain a blank line in between each data line when outputting with Dictwriter in Python

By default, the classes in the csv module use Windows-style line terminators (\r\n) rather than Unix-style (\n). Could this be what’s causing the apparent double line breaks?

If so, you can override it in the DictWriter constructor:

output = csv.DictWriter(open('file3.csv','w'), delimiter=',', lineterminator='\n', fieldnames=headers)

How to make inline plots in Jupyter Notebook larger?

The default figure size (in inches) is controlled by

matplotlib.rcParams['figure.figsize'] = [width, height]

For example:

import matplotlib.pyplot as plt
plt.rcParams['figure.figsize'] = [10, 5]

creates a figure with 10 (width) x 5 (height) inches

HTML Code for text checkbox '?'

Just make sure that your HTML file is encoded with UTF-8 and that your web server sends a HTTP header with that charset, then you just can write that character directly into your HTMl file.

http://www.w3.org/International/O-HTTP-charset

If you can't use UTF-8 for some reason, you can look up the codes in a unicode list such as http://en.wikipedia.org/wiki/List_of_Unicode_characters and use &#xABCD; where ABCD is the hexcode from that list (U+ABCD).

Get first word of string

Use regular expression

_x000D_
_x000D_
var totalWords = "foo love bar very much.";_x000D_
_x000D_
var firstWord = totalWords.replace(/ .*/,'');_x000D_
_x000D_
$('body').append(firstWord);
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
_x000D_
_x000D_
_x000D_

PHP - Get bool to echo false when false

Your'e casting a boolean to boolean and expecting an integer to be displayed. It works for true but not false. Since you expect an integer:

echo (int)$bool_val;

Byte Array to Hex String

Or, if you are a fan of functional programming:

>>> a = [133, 53, 234, 241]
>>> "".join(map(lambda b: format(b, "02x"), a))
8535eaf1
>>>

Concatenating bits in VHDL

The concatenation operator '&' is allowed on the right side of the signal assignment operator '<=', only

org.hibernate.NonUniqueResultException: query did not return a unique result: 2?

I don't think other answers explained the key part: why "COUNT(*)" returns more than one result?

I just encountered the same issue today, and what I found out is that if you have another class extending the target mapped class (here "CustomerData"), Hibernate will do this magic.

Hope this will save some time for other unfortunate guys.

How to hide the border for specified rows of a table?

I use this with good results:

border-style:hidden;

It also works for:

border-right-style:hidden; /*if you want to hide just a border on a cell*/

Example:

_x000D_
_x000D_
<style type="text/css">_x000D_
      table, th, td {_x000D_
       border: 2px solid green;_x000D_
      }_x000D_
      tr.hide_right > td, td.hide_right{_x000D_
        border-right-style:hidden;_x000D_
      }_x000D_
      tr.hide_all > td, td.hide_all{_x000D_
        border-style:hidden;_x000D_
      }_x000D_
  }_x000D_
</style>_x000D_
<table>_x000D_
  <tr>_x000D_
    <td class="hide_right">11</td>_x000D_
    <td>12</td>_x000D_
    <td class="hide_all">13</td>_x000D_
  </tr>_x000D_
  <tr class="hide_right">_x000D_
    <td>21</td>_x000D_
    <td>22</td>_x000D_
    <td>23</td>_x000D_
  </tr>_x000D_
  <tr class="hide_all">_x000D_
    <td>31</td>_x000D_
    <td>32</td>_x000D_
    <td>33</td>_x000D_
  </tr>_x000D_
</table>
_x000D_
_x000D_
_x000D_

Here is the result: enter image description here

can't access mysql from command line mac

I think this is the more simpler approach:

  1. Install mySQL-Shell package from mySQL site
  2. Run mysqlsh (should be added to your path by default after install)
  3. Connect to your database server like so: MySQL JS > \connect --mysql [username]@[endpoint/server]:3306
  4. Switch to SQL Mode by typing "\sql" in your prompt
  5. The console should print out the following to let you know you are good to go:

Switching to SQL mode... Commands end with ;

Go forth and do great things! :)

Spring 3.0: Unable to locate Spring NamespaceHandler for XML schema namespace

I have the same problem with spring 3.0.2 and spring-beans-3.0.xsd.

My solution:

Create a file META-INF/spring.schemas in the source folder and copy all necesary definitions. Create spring.handlers too.

I think that the class PluggableSchemaResolver is not working correctly.

http://static.springsource.org/spring/docs/3.0.x/javadoc-api/org/springframework/beans/factory/xml/PluggableSchemaResolver.html

from the javadoc:

"By default, this class will look for mapping files in the classpath using the pattern: META-INF/spring.schemas allowing for multiple files to exist on the classpath at any one time."

but in my case, this class only read the first spring.schemas finded.

Grettings. pacovr

What's the actual use of 'fail' in JUnit test case?

Let's say you are writing a test case for a negative flow where the code being tested should raise an exception.

try{
   bizMethod(badData);
   fail(); // FAIL when no exception is thrown
} catch (BizException e) {
   assert(e.errorCode == THE_ERROR_CODE_U_R_LOOKING_FOR)
}

Test process.env with Jest

In test file:

const APP_PORT = process.env.APP_PORT || 8080;

In the test script of ./package.json:

"scripts": {
   "test": "jest --setupFiles dotenv/config",
 }

In ./env:

APP_PORT=8080

Force "git push" to overwrite remote files

Simple steps by using tortoisegit

GIT giving local files commit and pushing into git repository.

Steps :

1) stash changes stash name

2) pull

3) stash pop

4) commit 1 or more files and give commit changes description set author and Date

5) push

How to print color in console using System.out.println?

If your terminal supports it, you can use ANSI escape codes to use color in your output. It generally works for Unix shell prompts; however, it doesn't work for Windows Command Prompt (Although, it does work for Cygwin). For example, you could define constants like these for the colors:

public static final String ANSI_RESET = "\u001B[0m";
public static final String ANSI_BLACK = "\u001B[30m";
public static final String ANSI_RED = "\u001B[31m";
public static final String ANSI_GREEN = "\u001B[32m";
public static final String ANSI_YELLOW = "\u001B[33m";
public static final String ANSI_BLUE = "\u001B[34m";
public static final String ANSI_PURPLE = "\u001B[35m";
public static final String ANSI_CYAN = "\u001B[36m";
public static final String ANSI_WHITE = "\u001B[37m";

Then, you could reference those as necessary.

For example, using the above constants, you could make the following red text output on supported terminals:

System.out.println(ANSI_RED + "This text is red!" + ANSI_RESET);

Update: You might want to check out the Jansi library. It provides an API and has support for Windows using JNI. I haven't tried it yet; however, it looks promising.

Update 2: Also, if you wish to change the background color of the text to a different color, you could try the following as well:

public static final String ANSI_BLACK_BACKGROUND = "\u001B[40m";
public static final String ANSI_RED_BACKGROUND = "\u001B[41m";
public static final String ANSI_GREEN_BACKGROUND = "\u001B[42m";
public static final String ANSI_YELLOW_BACKGROUND = "\u001B[43m";
public static final String ANSI_BLUE_BACKGROUND = "\u001B[44m";
public static final String ANSI_PURPLE_BACKGROUND = "\u001B[45m";
public static final String ANSI_CYAN_BACKGROUND = "\u001B[46m";
public static final String ANSI_WHITE_BACKGROUND = "\u001B[47m";

For instance:

System.out.println(ANSI_GREEN_BACKGROUND + "This text has a green background but default text!" + ANSI_RESET);
System.out.println(ANSI_RED + "This text has red text but a default background!" + ANSI_RESET);
System.out.println(ANSI_GREEN_BACKGROUND + ANSI_RED + "This text has a green background and red text!" + ANSI_RESET);

How to clear text area with a button in html using javascript?

You can simply use the ID attribute to the form and attach the <textarea> tag to the form like this:

<form name="commentform" action="#" method="post" target="_blank" id="1321">
    <textarea name="forcom" cols="40" rows="5" form="1321" maxlength="188">
        Enter your comment here...
    </textarea>
    <input type="submit" value="OK">
    <input type="reset" value="Clear">
</form>

Concatenate multiple result rows of one column into one, group by another column

Simpler with the aggregate function string_agg() (Postgres 9.0 or later):

SELECT movie, string_agg(actor, ', ') AS actor_list
FROM   tbl
GROUP  BY 1;

The 1 in GROUP BY 1 is a positional reference and a shortcut for GROUP BY movie in this case.

string_agg() expects data type text as input. Other types need to be cast explicitly (actor::text) - unless an implicit cast to text is defined - which is the case for all other character types (varchar, character, "char"), and some other types.

As isapir commented, you can add an ORDER BY clause in the aggregate call to get a sorted list - should you need that. Like:

SELECT movie, string_agg(actor, ', ' ORDER BY actor) AS actor_list
FROM   tbl
GROUP  BY 1;

But it's typically faster to sort rows in a subquery. See:

How to get the xml node value in string

You should use .Load and not .LoadXML

MSDN Link

"The LoadXml method is for loading an XML string directly. You want to use the Load method instead."

ref : Link

Secure random token in Node.js

Look at real_ates ES2016 way, it's more correct.

ECMAScript 2016 (ES7) way

import crypto from 'crypto';

function spawnTokenBuf() {
    return function(callback) {
        crypto.randomBytes(48, callback);
    };
}

async function() {
    console.log((await spawnTokenBuf()).toString('base64'));
};

Generator/Yield Way

var crypto = require('crypto');
var co = require('co');

function spawnTokenBuf() {
    return function(callback) {
        crypto.randomBytes(48, callback);
    };
}

co(function* () {
    console.log((yield spawnTokenBuf()).toString('base64'));
});

Determine command line working directory when running node bin script

  • process.cwd() returns directory where command has been executed (not directory of the node package) if it's has not been changed by 'process.chdir' inside of application.
  • __filename returns absolute path to file where it is placed.
  • __dirname returns absolute path to directory of __filename.

If you need to load files from your module directory you need to use relative paths.

require('../lib/test');

instead of

var lib  = path.join(path.dirname(fs.realpathSync(__filename)), '../lib');

require(lib + '/test');

It's always relative to file where it called from and don't depend on current work dir.

What event handler to use for ComboBox Item Selected (Selected Item not necessarily changed)

I hope that you will find helpfull the following trick.

You can bind both the events

combobox.SelectionChanged += OnSelectionChanged;
combobox.DropDownOpened += OnDropDownOpened;

And force selected item to null inside the OnDropDownOpened

private void OnDropDownOpened(object sender, EventArgs e)
{
    combobox.SelectedItem = null;
}

And do what you need with the item inside the OnSelectionChanged. The OnSelectionChanged will be raised every time you will open the combobox, but you can check if SelectedItem is null inside the method and skip the command

private void OnSelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        if (combobox.SelectedItem != null)
        {
           //Do something with the selected item
        }
    }

Spring's overriding bean

Any given Spring context can only have one bean for any given id or name. In the case of the XML id attribute, this is enforced by the schema validation. In the case of the name attribute, this is enforced by Spring's logic.

However, if a context is constructed from two different XML descriptor files, and an id is used by both files, then one will "override" the other. The exact behaviour depends on the ordering of the files when they get loaded by the context.

So while it's possible, it's not recommended. It's error-prone and fragile, and you'll get no help from Spring if you change the ID of one but not the other.

Install Qt on Ubuntu

Also take a look at awesome project aqtinstall https://github.com/miurahr/aqtinstall/ (it can install any Qt version on Linux, Mac and Windows machines without any interaction!) and GitHub Action that uses this tool: https://github.com/jurplel/install-qt-action

Convert String array to ArrayList

new ArrayList( Arrays.asList( new String[]{"abc", "def"} ) );

Is there a difference between `continue` and `pass` in a for loop in python?

Yes, there is a difference. Continue actually skips the rest of the current iteration of the loop (returning to the beginning). Pass is a blank statement that does nothing.

See the python docs

jQuery.inArray(), how to use it right?

The inArray function returns the index of the object supplied as the first argument to the function in the array supplied as the second argument to the function.

When inArray returns 0 it is indicating that the first argument was found at the first position of the supplied array.

To use inArray within an if statement use:

if(jQuery.inArray("test", myarray) != -1) {
    console.log("is in array");
} else {
    console.log("is NOT in array");
}

inArray returns -1 when the first argument passed to the function is not found in the array passed as the second argument.

My prerelease app has been "processing" for over a week in iTunes Connect, what gives?

Same issue for me... Upload app archives from Xcode (7.3.1). Connect to iTunesCo with both Chrome and Safari...

  • 20 august: v0.1.3 | b0.0.1 -> upload done -> never appeared on iTunesCo
  • 23 august: v0.1.4 | b0.0.1 -> upload done -> processing on iTunesCo
  • 23 august: v0.1.4 | b0.0.2 -> upload done -> processing on iTunesCo
  • 23 august: v0.1.4 | b0.0.3 -> upload done -> never appeared on iTunesCo
  • 24 august: v0.1.5 | b0.0.1 -> upload done -> available 5min later

The way it works has no logic... So I agree with @teapen:

...don't wait for Apple, just increase build and upload again...

Difference between adjustResize and adjustPan in android?

adjustResize = resize the page content

adjustPan = move page content without resizing page content