Programs & Examples On #Variable caching

How to read all of Inputstream in Server Socket JAVA

The problem you have is related to TCP streaming nature.

The fact that you sent 100 Bytes (for example) from the server doesn't mean you will read 100 Bytes in the client the first time you read. Maybe the bytes sent from the server arrive in several TCP segments to the client.

You need to implement a loop in which you read until the whole message was received. Let me provide an example with DataInputStream instead of BufferedinputStream. Something very simple to give you just an example.

Let's suppose you know beforehand the server is to send 100 Bytes of data.

In client you need to write:

byte[] messageByte = new byte[1000];
boolean end = false;
String dataString = "";

try 
{
    DataInputStream in = new DataInputStream(clientSocket.getInputStream());

    while(!end)
    {
        int bytesRead = in.read(messageByte);
        dataString += new String(messageByte, 0, bytesRead);
        if (dataString.length == 100)
        {
            end = true;
        }
    }
    System.out.println("MESSAGE: " + dataString);
}
catch (Exception e)
{
    e.printStackTrace();
}

Now, typically the data size sent by one node (the server here) is not known beforehand. Then you need to define your own small protocol for the communication between server and client (or any two nodes) communicating with TCP.

The most common and simple is to define TLV: Type, Length, Value. So you define that every message sent form server to client comes with:

  • 1 Byte indicating type (For example, it could also be 2 or whatever).
  • 1 Byte (or whatever) for length of message
  • N Bytes for the value (N is indicated in length).

So you know you have to receive a minimum of 2 Bytes and with the second Byte you know how many following Bytes you need to read.

This is just a suggestion of a possible protocol. You could also get rid of "Type".

So it would be something like:

byte[] messageByte = new byte[1000];
boolean end = false;
String dataString = "";

try 
{
    DataInputStream in = new DataInputStream(clientSocket.getInputStream());
    int bytesRead = 0;

    messageByte[0] = in.readByte();
    messageByte[1] = in.readByte();

    int bytesToRead = messageByte[1];

    while(!end)
    {
        bytesRead = in.read(messageByte);
        dataString += new String(messageByte, 0, bytesRead);
        if (dataString.length == bytesToRead )
        {
            end = true;
        }
    }
    System.out.println("MESSAGE: " + dataString);
}
catch (Exception e)
{
    e.printStackTrace();
}

The following code compiles and looks better. It assumes the first two bytes providing the length arrive in binary format, in network endianship (big endian). No focus on different encoding types for the rest of the message.

import java.nio.ByteBuffer;
import java.io.DataInputStream;
import java.net.ServerSocket;
import java.net.Socket;

class Test
{
    public static void main(String[] args)
    {
        byte[] messageByte = new byte[1000];
        boolean end = false;
        String dataString = "";

        try 
        {
            Socket clientSocket;
            ServerSocket server;

            server = new ServerSocket(30501, 100);
            clientSocket = server.accept();

            DataInputStream in = new DataInputStream(clientSocket.getInputStream());
            int bytesRead = 0;

            messageByte[0] = in.readByte();
            messageByte[1] = in.readByte();
            ByteBuffer byteBuffer = ByteBuffer.wrap(messageByte, 0, 2);

            int bytesToRead = byteBuffer.getShort();
            System.out.println("About to read " + bytesToRead + " octets");

            //The following code shows in detail how to read from a TCP socket

            while(!end)
            {
                bytesRead = in.read(messageByte);
                dataString += new String(messageByte, 0, bytesRead);
                if (dataString.length() == bytesToRead )
                {
                    end = true;
                }
            }

            //All the code in the loop can be replaced by these two lines
            //in.readFully(messageByte, 0, bytesToRead);
            //dataString = new String(messageByte, 0, bytesToRead);

            System.out.println("MESSAGE: " + dataString);
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }
}

What is the problem with shadowing names defined in outer scopes?

Do this:

data = [4, 5, 6]

def print_data():
    global data
    print(data)

print_data()

Changing default encoding of Python?

Here is a simpler method (hack) that gives you back the setdefaultencoding() function that was deleted from sys:

import sys
# sys.setdefaultencoding() does not exist, here!
reload(sys)  # Reload does the trick!
sys.setdefaultencoding('UTF8')

(Note for Python 3.4+: reload() is in the importlib library.)

This is not a safe thing to do, though: this is obviously a hack, since sys.setdefaultencoding() is purposely removed from sys when Python starts. Reenabling it and changing the default encoding can break code that relies on ASCII being the default (this code can be third-party, which would generally make fixing it impossible or dangerous).

Python "\n" tag extra line

Add , after the print "\n" line

so that it reads print "\n",

Is it possible to pass parameters programmatically in a Microsoft Access update query?

Try using the QueryDefs. Create the query with parameters. Then use something like this:

Dim dbs As DAO.Database
Dim qdf As DAO.QueryDef

Set dbs = CurrentDb
Set qdf = dbs.QueryDefs("Your Query Name")

qdf.Parameters("Parameter 1").Value = "Parameter Value"
qdf.Parameters("Parameter 2").Value = "Parameter Value"
qdf.Execute
qdf.Close

Set qdf = Nothing
Set dbs = Nothing

What is the first character in the sort order used by Windows Explorer?

TLDR; technically space sorts before exclamation mar, and can be used by preceding it with ' or - (which will be ignored in sorting), but exclamation mark follows right after space, and is easier to use.

On windows 7 at least, a minus sign (-) and (') seem to be ignored in a name except for one quirk: in a name that is otherwise identical, the ' will be sorted before -, for example: (a'a) will sort above (a-a)

Empty string will sort above everything else, which means for example aa will sort above aaa because the 'empty string' after two a letters will sort before the third 'a'.

This also means that aa will be sorted above a'a because the 'empty string' between two a letters will sort above the ' mark.

What follows then is, ' alone will sort first, because technically it's an empty string. However adding for example letters behind it will sort the name as if the ' didn't exist.

Since the first 'unignored' character (as far as I know) is space, in case you want to sort 'real names' above others, the best way to go would be ' followed by space, and then the name you want to actually use. For example: (' first)

You can of course top that by using more than one space in the strong, such as (' firster) and (' firstest) with two and three blanks before the f.

While minus sign sorts below ' in otherwise similar name, there's no other difference in sorting (that I know of), and I find minus sign visually clearer, so if I want to put something on top of list, I'd use minus followed by space, then the 'actual name', for example: (- first file -)

If you are worried about using space on the filename, then exclamation mark (!) is the next best thing - and since it can appear as first character on a string, it's easier to use.

Java JDBC connection status

Nothing. Just execute your query. If the connection has died, either your JDBC driver will reconnect (if it supports it, and you enabled it in your connection string--most don't support it) or else you'll get an exception.

If you check the connection is up, it might fall over before you actually execute your query, so you gain absolutely nothing by checking.

That said, a lot of connection pools validate a connection by doing something like SELECT 1 before handing connections out. But this is nothing more than just executing a query, so you might just as well execute your business query.

App store link for "rate/review this app"

For >= iOS8: (Simplified @EliBud's answer).

#define APP_STORE_ID 1108885113

- (void)rateApp{
    static NSString *const iOSAppStoreURLFormat = @"itms-apps://itunes.apple.com/WebObjects/MZStore.woa/wa/viewContentsUserReviews?type=Purple+Software&id=%d";

    NSURL *appStoreURL = [NSURL URLWithString:[NSString stringWithFormat:iOSAppStoreURLFormat, APP_STORE_ID]];

    if ([[UIApplication sharedApplication] canOpenURL:appStoreURL]) {
        [[UIApplication sharedApplication] openURL:appStoreURL];
    }
}

How to store Emoji Character in MySQL Database

Step 1, change your database's default charset:

ALTER DATABASE database_name CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci;

if the db is not created yet, create it with correct encodings:

CREATE DATABASE database_name DEFAULT CHARSET = utf8mb4 DEFAULT COLLATE = utf8mb4_unicode_ci;

Step 2, set charset when creating table:

CREATE TABLE IF NOT EXISTS table_name (
...
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE utf8mb4_unicode_ci;

or alter table

ALTER TABLE table_name CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
ALTER TABLE table_name MODIFY field_name TEXT CHARSET utf8mb4;

How to select all checkboxes with jQuery?

  $("#select_all").live("click", function(){
            $("input").prop("checked", $(this).prop("checked"));
    }
  });

Loop Through All Subfolders Using VBA

Just a simple folder drill down.

sub sample()
    Dim FileSystem As Object
    Dim HostFolder As String

    HostFolder = "C:\"

    Set FileSystem = CreateObject("Scripting.FileSystemObject")
    DoFolder FileSystem.GetFolder(HostFolder)
end  sub

Sub DoFolder(Folder)
    Dim SubFolder
    For Each SubFolder In Folder.SubFolders
        DoFolder SubFolder
    Next
    Dim File
    For Each File In Folder.Files
        ' Operate on each file
    Next
End Sub

Changing the text on a label

self.labelText = 'change the value'

The above sentence makes labelText change the value, but not change depositLabel's text.

To change depositLabel's text, use one of following setences:

self.depositLabel['text'] = 'change the value'

OR

self.depositLabel.config(text='change the value')

How to use comparison operators like >, =, < on BigDecimal

Using com.ibm.etools.marshall.util.BigDecimalRange util class of IBM one can compare if BigDecimal in range.

boolean isCalculatedSumInRange = BigDecimalRange.isInRange(low, high, calculatedSum);

jQuery returning "parsererror" for ajax request

You have specified the ajax call response dataType as:

'json'

where as the actual ajax response is not a valid JSON and as a result the JSON parser is throwing an error.

The best approach that I would recommend is to change the dataType to:

'text'

and within the success callback validate whether a valid JSON is being returned or not, and if JSON validation fails, alert it on the screen so that its obvious for what purpose the ajax call is actually failing. Have a look at this:

$.ajax({
    url: '/Admin/Ajax/GetViewContentNames',
    type: 'POST',
    dataType: 'text',
    data: {viewID: $("#view").val()},
    success: function (data) {
        try {
            var output = JSON.parse(data);
            alert(output);
        } catch (e) {
            alert("Output is not valid JSON: " + data);
        }
    }, error: function (request, error) {
        alert("AJAX Call Error: " + error);
    }
});

How do I add a placeholder on a CharField in Django?

class FormClass(forms.ModelForm):
    class Meta:
        model = Book
        fields = '__all__'
        widgets = {
            'field_name': forms.TextInput(attrs={'placeholder': 'Type placeholder text here..'}),
        }

Get button click inside UITableViewCell

1) In your cellForRowAtIndexPath: method, assign button tag as index:

cell.yourbutton.tag = indexPath.row;

2) Add target and action for your button as below:

[cell.yourbutton addTarget:self action:@selector(yourButtonClicked:) forControlEvents:UIControlEventTouchUpInside];

3) Code actions based on index as below in ViewControler:

-(void)yourButtonClicked:(UIButton*)sender
{
     if (sender.tag == 0) 
     {
         // Your code here
     }
}

Updates for multiple Section:

You can check this link to detect button click in table view for multiple row and section.

What is the difference between an abstract function and a virtual function?

Abstract methods are always virtual. They cannot have an implementation.

That's the main difference.

Basically, you would use a virtual method if you have the 'default' implementation of it and want to allow descendants to change its behaviour.

With an abstract method, you force descendants to provide an implementation.

Java "lambda expressions not supported at this language level"

The same project (Android Studio 3.3.2, gradle-4.10.1-all.zip, compileSdkVersion 28, buildToolsVersion '28.0.3') works fine on the new fast Windows machine and underline Java 8 stuff by red color on the old Ubuntu 18.04 laptop (however project is compiling without errors on Ubuntu).

The only two things I have changed to force it to stop underlining by red were excluding of incremental true and dexOptions

compileOptions {
//    incremental true
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
}

//dexOptions {
//    javaMaxHeapSize "4g"
//}

in the app- level build.gradle.

Html.HiddenFor value property not getting set

The following will work in MVC 4

@Html.HiddenFor(x => x.CRN, new { @Value = "1" });

@Value property is case sensitive. You need a capital 'V' on @Value.

Here is my model

public int CRN { get; set; }

Here is what is output in html when you look in the browser

<input value="1" data-val="true" data-val-number="The field CRN must be a number." data-val-required="The CRN field is required." id="CRN" name="CRN" type="hidden" value="1"/>

Here is my method

[HttpPost]
public ActionResult MyMethod(MyViewModel viewModel)
{
  int crn = viewModel.CRN;
}

How can I check if my Element ID has focus?

Compare document.activeElement with the element you want to check for focus. If they are the same, the element is focused; otherwise, it isn't.

// dummy element
var dummyEl = document.getElementById('myID');

// check for focus
var isFocused = (document.activeElement === dummyEl);

hasFocus is part of the document; there's no such method for DOM elements.

Also, document.getElementById doesn't use a # at the beginning of myID. Change this:

var dummyEl = document.getElementById('#myID');

to this:

var dummyEl = document.getElementById('myID');

If you'd like to use a CSS query instead you can use querySelector (and querySelectorAll).

MySQL ON DUPLICATE KEY UPDATE for multiple rows insert in single query

Beginning with MySQL 8.0.19 you can use an alias for that row (see reference).

INSERT INTO beautiful (name, age)
    VALUES
    ('Helen', 24),
    ('Katrina', 21),
    ('Samia', 22),
    ('Hui Ling', 25),
    ('Yumie', 29)
    AS new
ON DUPLICATE KEY UPDATE
    age = new.age
    ...

For earlier versions use the keyword VALUES (see reference, deprecated with MySQL 8.0.20).

INSERT INTO beautiful (name, age)
    VALUES
    ('Helen', 24),
    ('Katrina', 21),
    ('Samia', 22),
    ('Hui Ling', 25),
    ('Yumie', 29)
ON DUPLICATE KEY UPDATE
    age = VALUES(age),
     ...

Creating hard and soft links using PowerShell

Windows 10 (and Powershell 5.0 in general) allows you to create symbolic links via the New-Item cmdlet.

Usage:

New-Item -Path C:\LinkDir -ItemType SymbolicLink -Value F:\RealDir

Or in your profile:

function make-link ($target, $link) {
    New-Item -Path $link -ItemType SymbolicLink -Value $target
}

Turn on Developer Mode to not require admin privileges when making links with New-Item:

enter image description here

How to get the file ID so I can perform a download of a file from Google Drive API on Android?

Stan0 intial idea is not a good idea. There can be multiple files with the same name. Very error prone implementation. Stan0's second idea is the correct way.

When you first upload the file to google drive store its id (in SharedPreferences is probably easiest) for later use

ie.

file= mDrive.files().insert(body).execute();      //initial insert of file to google drive

whereverYouWantToStoreIt= file.getId(); //now you have the guaranteed unique id 
                                        //of the file just inserted. Store it and use it 
                                        //whenever you need to fetch this file

String.equals() with multiple conditions (and one action on result)

Pattern p = Pattern.compile("tom"); //the regular-expression pattern
Matcher m = p.matcher("(bob)(tom)(harry)"); //The data to find matches with

while (m.find()) {
    //do something???
}   

Use regex to find a match maybe?

Or create an array

 String[] a = new String[]{
        "tom",
        "bob",
        "harry"
 };

 if(a.contains(stringtomatch)){
     //do something
 }

MVC web api: No 'Access-Control-Allow-Origin' header is present on the requested resource

If you have security\requestFiltering nodes in your web.config as follows:

<security>
  <requestFiltering>
    <verbs allowUnlisted="false">
      <add verb="GET" allowed="true" />
      <add verb="POST" allowed="true" />
      <add verb="PUT" allowed="true" />
      <add verb="DELETE" allowed="true" />
      <add verb="DEBUG" allowed="true" />          
    </verbs>
  </requestFiltering>

make sure you add this as well

<add verb="OPTIONS" allowed="true" />

Proper use of const for defining functions in JavaScript

There are special cases where arrow functions just won't do the trick:

  1. If we're changing a method of an external API, and need the object's reference.

  2. If we need to use special keywords that are exclusive to the function expression: arguments, yield, bind etc. For more information: Arrow function expression limitations

Example:

I assigned this function as an event handler in the Highcharts API. It's fired by the library, so the this keyword should match a specific object.

export const handleCrosshairHover = function (proceed, e) {
  const axis = this; // axis object
  proceed.apply(axis, Array.prototype.slice.call(arguments, 1)); // method arguments
};

With an arrow function, this would match the declaration scope, and we won't have access to the API obj:

export const handleCrosshairHover = (proceed, e) => {
  const axis = this; // this = undefined
  proceed.apply(axis, Array.prototype.slice.call(arguments, 1)); // compilation error
};

In C/C++ what's the simplest way to reverse the order of bits in a byte?

#include <stdio.h>
#include <stdlib.h>

#define BIT0 (0x01)
#define BIT1 (0x02)
#define BIT2 (0x04)
#define BIT3 (0x08)
#define BIT4 (0x10)
#define BIT5 (0x20)
#define BIT6 (0x40)
#define BIT7 (0x80)

#define BYTE_TO_BINARY_PATTERN "%c%c%c%c%c%c%c%c\n"

#define BITETOBINARY(byte) \
(byte & BIT7 ? '1' : '0'), \
(byte & BIT6 ? '1' : '0'), \
(byte & BIT5 ? '1' : '0'), \
(byte & BIT4 ? '1' : '0'), \
(byte & BIT3 ? '1' : '0'), \
(byte & BIT2 ? '1' : '0'), \
(byte & BIT1 ? '1' : '0'), \
(byte & BIT0 ? '1' : '0') \

#define BITETOBINARYREVERSE(byte) \
(byte & BIT0 ? '1' : '0'), \
(byte & BIT1 ? '1' : '0'), \
(byte & BIT2 ? '1' : '0'), \
(byte & BIT3 ? '1' : '0'), \
(byte & BIT4 ? '1' : '0'), \
(byte & BIT5 ? '1' : '0'), \
(byte & BIT6 ? '1' : '0'), \
(byte & BIT7 ? '1' : '0') \



int main()
{

    int i,j,c;

    i |= BIT2|BIT7;

    printf("0x%02X\n",i);    

    printf(BYTE_TO_BINARY_PATTERN,BITETOBINARY(i));

    printf("Reverse");

    printf(BYTE_TO_BINARY_PATTERN,BITETOBINARYREVERSE(i));

   return 0;
}

Bootstrap dropdown not working

Both bootstrap and jquery must be included:

<link type="text/css" href="/{ProjectName}/css/ui-lightness/jquery-ui-1.8.18.custom.css" rel="stylesheet" />
<script type="text/javascript" src="/{ProjectName}/js/jquery-x.x.x.custom.min.js"></script>

<link type="text/css" href="/{ProjectName}/css/bootstrap.css" rel="stylesheet" />
<script type="text/javascript" src="/{ProjectName}/js/bootstrap.js"></script>

NOTE: jquery-x.x.x.min.js version must be version 2.x.x !!!

Simple argparse example wanted: 1 argument, 3 results

Matt is asking about positional parameters in argparse, and I agree that the Python documentation is lacking on this aspect. There's not a single, complete example in the ~20 odd pages that shows both parsing and using positional parameters.

None of the other answers here show a complete example of positional parameters, either, so here's a complete example:

# tested with python 2.7.1
import argparse

parser = argparse.ArgumentParser(description="An argparse example")

parser.add_argument('action', help='The action to take (e.g. install, remove, etc.)')
parser.add_argument('foo-bar', help='Hyphens are cumbersome in positional arguments')

args = parser.parse_args()

if args.action == "install":
    print("You asked for installation")
else:
    print("You asked for something other than installation")

# The following do not work:
# print(args.foo-bar)
# print(args.foo_bar)

# But this works:
print(getattr(args, 'foo-bar'))

The thing that threw me off is that argparse will convert the named argument "--foo-bar" into "foo_bar", but a positional parameter named "foo-bar" stays as "foo-bar", making it less obvious how to use it in your program.

Notice the two lines near the end of my example -- neither of those will work to get the value of the foo-bar positional param. The first one is obviously wrong (it's an arithmetic expression args.foo minus bar), but the second one doesn't work either:

AttributeError: 'Namespace' object has no attribute 'foo_bar'

If you want to use the foo-bar attribute, you must use getattr, as seen in the last line of my example. What's crazy is that if you tried to use dest=foo_bar to change the property name to something that's easier to access, you'd get a really bizarre error message:

ValueError: dest supplied twice for positional argument

Here's how the example above runs:

$ python test.py
usage: test.py [-h] action foo-bar
test.py: error: too few arguments

$ python test.py -h
usage: test.py [-h] action foo-bar

An argparse example

positional arguments:
  action      The action to take (e.g. install, remove, etc.)
  foo-bar     Hyphens are cumbersome in positional arguments

optional arguments:
  -h, --help  show this help message and exit

$ python test.py install foo
You asked for installation
foo

Regex to get the words after matching string

The following should work for you:

[\n\r].*Object Name:\s*([^\n\r]*)

Working example

Your desired match will be in capture group 1.


[\n\r][ \t]*Object Name:[ \t]*([^\n\r]*)

Would be similar but not allow for things such as " blah Object Name: blah" and also make sure that not to capture the next line if there is no actual content after "Object Name:"

React JS - Uncaught TypeError: this.props.data.map is not a function

I had the same problem. The solution was to change the useState initial state value from string to array. In App.js, previous useState was

const [favoriteFilms, setFavoriteFilms] = useState('');

I changed it to

const [favoriteFilms, setFavoriteFilms] = useState([]);

and the component that uses those values stopped throwing error with .map function.

SQLAlchemy ORDER BY DESCENDING?

from sqlalchemy import desc
someselect.order_by(desc(table1.mycol))

Usage from @jpmc26

How to obfuscate Python code effectively?

The best way to do this is to first generate a .c file, and then compile it with tcc to a .pyd file
Note: Windows-only

Requirements

  1. tcc
  2. pyobfuscate
  3. Cython

Install:

sudo pip install -U cython

To obfuscate your .py file:

pyobfuscate.py myfile.py >obfuscated.py

To generate a .c file,

  1. Add an init<filename>() function to your .py file Optional

  2. cython --embed file.py

  3. cp Python.h tcc\include

  4. tcc file.c -o file.pyd -shared -I\path\to\Python\include -L\path\to\Python\lib

  5. import .pyd file into app.exe

UL has margin on the left

The <ul> element has browser inherent padding & margin by default. In your case, Use

#footer ul {
    margin: 0; /* To remove default bottom margin */ 
    padding: 0; /* To remove default left padding */
}

or a CSS browser reset ( https://cssreset.com/ ) to deal with this.

How to "wait" a Thread in Android

Don't use wait(), use either android.os.SystemClock.sleep(1000); or Thread.sleep(1000);.

The main difference between them is that Thread.sleep() can be interrupted early -- you'll be told, but it's still not the full second. The android.os call will not wake early.

Deploying website: 500 - Internal server error

IIS also reports status code 500 without any event log hints if there are insufficient permissions on the physical home directory (i.e. IIS_IUSRS has no access).

How to resize datagridview control when form resizes

set the "Dock" property of datagridview in layoutto one of these properties : top, left, bottom, right. ok?

Can I apply the required attribute to <select> fields in HTML5?

Mandatory: Have the first value empty - required works on empty values

Prerequisites: correct html5 DOCTYPE and a named input field

<select name="somename" required>
<option value="">Please select</option>
<option value="one">One</option>
</select>

As per the documentation (the listing and bold is mine)

The required attribute is a boolean attribute.
When specified, the user will be required to select a value before submitting the form.

If a select element

  • has a required attribute specified,
  • does not have a multiple attribute specified,
  • and has a display size of 1 (do not have SIZE=2 or more - omit it if not needed);
  • and if the value of the first option element in the select element's list of options (if any) is the empty string (i.e. present as value=""),
  • and that option element's parent node is the select element (and not an optgroup element),

then that option is the select element's placeholder label option.

Omitting the second expression when using the if-else shorthand

Tiny addition to this very old thread..

If your'e evaluating an expression inside a for/while loop with a ternary operator, and want to continue or break as a result - you're gonna have a problem because both continue&break aren't expressions, they're statements without any value.

This will produce Uncaught SyntaxError: Unexpected token continue

 for (const item of myArray) {
      item.value ? break : continue;
 }

If you really want a one-liner that returns a statement, you can use this instead:

  for (const item of myArray) {
      if (item.value) break; else continue;
  }
  • P.S - This code might raise some eyebrows. Just saying.. :)

Use tab to indent in textarea

The above answers all wipe undo history. For anyone looking for a solution that doesn't do that, I spent the last hour coding up the following for Chrome:

jQuery.fn.enableTabs = function(TAB_TEXT){
    // options
    if(!TAB_TEXT)TAB_TEXT = '\t';
    // text input event for character insertion
    function insertText(el, text){
        var te = document.createEvent('TextEvent');
        te.initTextEvent('textInput', true, true, null, text, 9, "en-US");
        el.dispatchEvent(te);
    }
    // catch tab and filter selection
    jQuery(this).keydown(function(e){
        if((e.which || e.keyCode)!=9)return true;
        e.preventDefault();
        var contents = this.value,
            sel_start = this.selectionStart,
            sel_end = this.selectionEnd,
            sel_contents_before = contents.substring(0, sel_start),
            first_line_start_search = sel_contents_before.lastIndexOf('\n'),
            first_line_start = first_line_start_search==-1 ? 0 : first_line_start_search+1,
            tab_sel_contents = contents.substring(first_line_start, sel_end),
            tab_sel_contents_find = (e.shiftKey?new RegExp('\n'+TAB_TEXT, 'g'):new RegExp('\n', 'g')),
            tab_sel_contents_replace = (e.shiftKey?'\n':'\n'+TAB_TEXT);
            tab_sel_contents_replaced = (('\n'+tab_sel_contents)
                .replace(tab_sel_contents_find, tab_sel_contents_replace))
                .substring(1),
            sel_end_new = first_line_start+tab_sel_contents_replaced.length;
        this.setSelectionRange(first_line_start, sel_end);
        insertText(this, tab_sel_contents_replaced);
        this.setSelectionRange(first_line_start, sel_end_new);
    });
};

In short, tabs are inserted at the beginning of the selected lines.

JSFiddle: http://jsfiddle.net/iausallc/5Lnabspr/11/

Gist: https://gist.github.com/iautomation/e53647be326cb7d7112d

Example usage: $('textarea').enableTabs('\t')

Cons: Only works on Chrome as is.

Split string into array

ES6 is quite powerful in iterating through objects (strings, Array, Map, Set). Let's use a Spread Operator to solve this.

entry = prompt("Enter your name");
var count = [...entry];
console.log(count);

How to install mscomct2.ocx file from .cab file (Excel User Form and VBA)

You're correct that this is really painful to hand out to others, but if you have to, this is how you do it.

  1. Just extract the .ocx file from the .cab file (it is similar to a zip)
  2. Copy to the system folder (c:\windows\sysWOW64 for 64 bit systems and c:\windows\system32 for 32 bit)
  3. Use regsvr32 through the command prompt to register the file (e.g. "regsvr32 c:\windows\sysWOW64\mscomct2.ocx")

References

Direct download from Google Drive using Google Drive API

https://drive.google.com/uc?export=download&id=FILE_ID replace the FILE_ID with file id.

if you don't know were is file id then check this article Article LINK

Using Java 8 to convert a list of objects into a string obtained from the toString() method

List<String> list = Arrays.asList("One", "Two", "Three");
    list.stream()
            .reduce("", org.apache.commons.lang3.StringUtils::join);

Or

List<String> list = Arrays.asList("One", "Two", "Three");
        list.stream()
                .reduce("", (s1,s2)->s1+s2);

This approach allows you also build a string result from a list of objects Example

List<Wrapper> list = Arrays.asList(w1, w2, w2);
        list.stream()
                .map(w->w.getStringValue)
                .reduce("", org.apache.commons.lang3.StringUtils::join);

Here the reduce function allows you to have some initial value to which you want to append new string Example:

 List<String> errors = Arrays.asList("er1", "er2", "er3");
            list.stream()
                    .reduce("Found next errors:", (s1,s2)->s1+s2);

TypeScript add Object to array with push

If your example represents your real code, the problem is not in the push, it's that your constructor doesn't do anything.

You need to declare and initialize the x and y members.

Explicitly:

export class Pixel {
    public x: number;
    public y: number;   
    constructor(x: number, y: number) {
        this.x = x;
        this.y = y;
    }
}

Or implicitly:

export class Pixel {
    constructor(public x: number, public y: number) {}
}

Absolute positioning ignoring padding of parent

add padding:inherit in your absolute position

_x000D_
_x000D_
.box{_x000D_
  background: red;_x000D_
  position: relative;_x000D_
  padding: 30px;_x000D_
  width:500px;_x000D_
  height:200px;_x000D_
 box-sizing: border-box;_x000D_
 _x000D_
_x000D_
}
_x000D_
<div  class="box">_x000D_
_x000D_
  <div style="position: absolute;left:0;top:0;padding: inherit">top left</div>_x000D_
  <div style="position: absolute;right:0;top:0;padding: inherit">top right</div>_x000D_
  <div style="text-align: center;padding: inherit">center</div>_x000D_
  <div style="position: absolute;left:0;bottom:0;padding: inherit">bottom left</div>_x000D_
  <div style="position: absolute;right:0;bottom:0;padding: inherit">bottom right</div>_x000D_
_x000D_
_x000D_
</div>
_x000D_
_x000D_
_x000D_

Highlight a word with jQuery

Here's a variation that ignores and preserves case:

jQuery.fn.highlight = function (str, className) {
    var regex = new RegExp("\\b"+str+"\\b", "gi");

    return this.each(function () {
        this.innerHTML = this.innerHTML.replace(regex, function(matched) {return "<span class=\"" + className + "\">" + matched + "</span>";});
    });
};

jQuery UI Dialog Box - does not open after being closed

on the last line, don't use $(this).remove() use $(this).hide() instead.

EDIT: To clarify,on the close click event you're removing the #terms div from the DOM which is why its not coming back. You just need to hide it instead.

How to get the last characters in a String in Java, regardless of String size

Lots of things you could do.

s.substring(s.lastIndexOf(':') + 1);

will get everything after the last colon.

s.substring(s.lastIndexOf(' ') + 1);

everything after the last space.

String numbers[] = s.split("[^0-9]+");

splits off all sequences of digits; the last element of the numbers array is probably what you want.

Optimal number of threads per core

Benchmark.

I'd start ramping up the number of threads for an application, starting at 1, and then go to something like 100, run three-five trials for each number of threads, and build yourself a graph of operation speed vs. number of threads.

You should that the four thread case is optimal, with slight rises in runtime after that, but maybe not. It may be that your application is bandwidth limited, ie, the dataset you're loading into memory is huge, you're getting lots of cache misses, etc, such that 2 threads are optimal.

You can't know until you test.

jQuery addClass onClick

Try to make your css more specific so that the new (green) style is more specific than the previous one, so that it worked for me!

For example, you might use in css:

button:active {/*your style here*/}

Instead of (probably not working):

.active {/*style*/} (.active is not a pseudo-class)

Hope it helps!

How to Logout of an Application Where I Used OAuth2 To Login With Google?

You can log out and rediret to your site:

var logout = function() {
    document.location.href = "https://www.google.com/accounts/Logout?continue=https://appengine.google.com/_ah/logout?continue=http://www.example.com";
}

How to sort ArrayList<Long> in decreasing order?

Here's one way for your list:

list.sort(null);
Collections.reverse(list);

Or you could implement your own Comparator to sort on and eliminate the reverse step:

list.sort((o1, o2) -> o2.compareTo(o1));

Or even more simply use Collections.reverseOrder() since you're only reversing:

list.sort(Collections.reverseOrder());

Any way to declare an array in-line?

Other option is to use ArrayUtils.toArray in org.apache.commons.lang3

ArrayUtils.toArray("elem1","elem2")

Get most recent file in a directory on Linux

This is a recursive version (i.e. it finds the most recently updated file in a certain directory or any of its subdirectory)

find $DIR -type f -printf "%T@ %p\n" | sort -n | cut -d' ' -f 2- | tail -n 1

Edit: use -f 2- instead of -f 2 as suggested by Kevin

Generate MD5 hash string with T-SQL

try this:

select SUBSTRING(sys.fn_sqlvarbasetostr(HASHBYTES('MD5',  '[email protected]' )),3,32) 

Static image src in Vue.js template

You need use just simple code <img alt="img" src="../assets/index.png" />

Do not forgot atribut alt in balise img

Using OR operator in a jquery if statement

Update: using .indexOf() to detect if stat value is one of arr elements

Pure JavaScript

_x000D_
_x000D_
var arr = [20,30,40,50,60,70,80,90,100];_x000D_
//or detect equal to all_x000D_
//var arr = [10,10,10,10,10,10,10];_x000D_
    var stat = 10;_x000D_
_x000D_
if(arr.indexOf(stat)==-1)alert("stat is not equal to one more elements of array");
_x000D_
_x000D_
_x000D_

Configuring angularjs with eclipse IDE

  1. Make sure the project is extracted on your hard disk.
  2. In Eclipse go to the menu: File->New->Project.
  3. Select "General->Project" and click on the next button.
  4. Enter the project name in the "Project name:" field
  5. Disable "Use default location" Click on the "Browse ..." button and select the folder that contains the project (the one from step 1)
  6. Click on the "Finish" button
  7. Right-click with the mouse on you're new project and click "Configure->Convert to AngularJS Project.."
  8. Enable you're project goodies and click on the "OK" button.

MySQL: determine which database is selected?

You can always use STATUS command to get to know Current database & Current User

enter image description here

MVC 3: How to render a view without its layout page when loaded via ajax?

I prefer, and use, your #1 option. I don't like #2 because to me View() implies you are returning an entire page. It should be a fully fleshed out and valid HTML page once the view engine is done with it. PartialView() was created to return arbitrary chunks of HTML.

I don't think it's a big deal to have a view that just calls a partial. It's still DRY, and allows you to use the logic of the partial in two scenarios.

Many people dislike fragmenting their action's call paths with Request.IsAjaxRequest(), and I can appreciate that. But IMO, if all you are doing is deciding whether to call View() or PartialView() then the branch is not a big deal and is easy to maintain (and test). If you find yourself using IsAjaxRequest() to determine large portions of how your action plays out, then making a separate AJAX action is probably better.

Adding Jar files to IntellijIdea classpath

Go to File-> Project Structure-> Libraries and click green "+" to add the directory folder that has the JARs to CLASSPATH. Everything in that folder will be added to CLASSPATH.

Update:

It's 2018. It's a better idea to use a dependency manager like Maven and externalize your dependencies. Don't add JAR files to your project in a /lib folder anymore.

Screenshot

Error in Python script "Expected 2D array, got 1D array instead:"?

I use the below approach.

reg = linear_model.LinearRegression()
reg.fit(df[['year']],df.income)

reg.predict([[2136]])

SSIS Text was truncated with status value 4

I've had this problem before, you can go to "advanced" tab of "choose a data source" page and click on "suggested types" button, and set the "number of rows" as much as you want. after that, the type and text qualified are set to the true values.

i applied the above solution and can convert my data to SQL.

Catch KeyError in Python

If you don't want to handle error just NoneType and use get() e.g.:

manager.connect.get("")

[Vue warn]: Cannot find element

You can solve it in two ways.

  1. Make sure you put the CDN into the end of html page and place your own script after that. Example:
    <body>
      <div id="main">
        <div id="mainActivity" v-component="{{currentActivity}}" class="activity"></div>
      </div>
    </body>
    <script src="https://cdn.jsdelivr.net/npm/[email protected]"></script>
    <script src="js/app.js"></script>

where you need to put same javascript code you wrote in any other JavaScript file or in html file.

  1. Use window.onload function in your JavaScript file.

ERROR 1130 (HY000): Host '' is not allowed to connect to this MySQL server

$mysql -u root --host=127.0.0.1 -p

mysql>use mysql

mysql>GRANT ALL ON *.* to root@'%' IDENTIFIED BY 'redhat@123';

mysql>FLUSH PRIVILEGES;

mysql> SELECT host FROM mysql.user WHERE User = 'root';

(change) vs (ngModelChange) in angular

(change) event bound to classical input change event.

https://developer.mozilla.org/en-US/docs/Web/Events/change

You can use (change) event even if you don't have a model at your input as

<input (change)="somethingChanged()">

(ngModelChange) is the @Output of ngModel directive. It fires when the model changes. You cannot use this event without ngModel directive.

https://github.com/angular/angular/blob/master/packages/forms/src/directives/ng_model.ts#L124

As you discover more in the source code, (ngModelChange) emits the new value.

https://github.com/angular/angular/blob/master/packages/forms/src/directives/ng_model.ts#L169

So it means you have ability of such usage:

<input (ngModelChange)="modelChanged($event)">
modelChanged(newObj) {
    // do something with new value
}

Basically, it seems like there is no big difference between two, but ngModel events gains the power when you use [ngValue].

  <select [(ngModel)]="data" (ngModelChange)="dataChanged($event)" name="data">
      <option *ngFor="let currentData of allData" [ngValue]="currentData">
          {{data.name}}
      </option>
  </select>
dataChanged(newObj) {
    // here comes the object as parameter
}

assume you try the same thing without "ngModel things"

<select (change)="changed($event)">
    <option *ngFor="let currentData of allData" [value]="currentData.id">
        {{data.name}}
    </option>
</select>
changed(e){
    // event comes as parameter, you'll have to find selectedData manually
    // by using e.target.data
}

Display curl output in readable JSON format in Unix shell script

A few solutions to choose from:

json_pp: command utility available in Linux systems for JSON decoding/encoding

echo '{"type":"Bar","id":"1","title":"Foo"}' | json_pp -json_opt pretty,canonical
{
   "id" : "1",
   "title" : "Foo",
   "type" : "Bar"
}

You may want to keep the -json_opt pretty,canonical argument for predictable ordering.


: lightweight and flexible command-line JSON processor. It is written in portable C, and it has zero runtime dependencies.

echo '{"type":"Bar","id":"1","title":"Foo"}' | jq '.'
{
  "type": "Bar",
  "id": "1",
  "title": "Foo"
}

The simplest jq program is the expression ., which takes the input and produces it unchanged as output.

For additinal jq options check the manual


with :

echo '{"type":"Bar","id":"1","title":"Foo"}' | python -m json.tool
{
    "id": "1",
    "title": "Foo",
    "type": "Bar"
}

with and :

echo '{"type":"Bar","id":"1","title":"Foo"}' | node -e "console.log( JSON.stringify( JSON.parse(require('fs').readFileSync(0) ), 0, 1 ))"
{
 "type": "Bar",
 "id": "1",
 "title": "Foo"
}

How to set JAVA_HOME in Mac permanently?

Adding to Dilips's answer, if you are working with JDK 9, use the following (my JDK version is 9.0.4) in Step # 3:

export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk-9.0.4.jdk/Contents/Home

LINQ query on a DataTable

Try this...

SqlCommand cmd = new SqlCommand( "Select * from Employee",con);
SqlDataReader dr = cmd.ExecuteReader( );
DataTable dt = new DataTable( "Employee" );
dt.Load( dr );
var Data = dt.AsEnumerable( );
var names = from emp in Data select emp.Field<String>( dt.Columns[1] );
foreach( var name in names )
{
    Console.WriteLine( name );
}

Playing MP4 files in Firefox using HTML5 video

I can confirm that mp4 just will not work in the video tag. No matter how much you try to mess with the type tag and the codec and the mime types from the server.

Crazy, because for the same exact video, on the same test page, the old embed tag for an mp4 works just fine in firefox. I spent all yesterday messing with this. Firefox is like IE all of a sudden, hours and hours of time, not billable. Yay.

Speaking of IE, it fails FAR MORE gracefully on this. When it can't match up the format it falls to the content between the tags, so it is possible to just put video around object around embed and everything works great. Firefox, nope, despite failing, it puts up the poster image (greyed out so that isn't even useful as a fallback) with an error message smack in the middle. So now the options are put in browser recognition code (meaning we've gained nothing on embedding videos in the last ten years) or ditch html5.

CSS two div width 50% in one line with line break in file

<div id="wrapper" style="width: 400px">
    <div id="left" style="float: left; width: 200px;">Left</div>
    <div id="right" style="float: right; width: 200px;">Left</div>
    <div style="clear: both;"></div>
</div>

I know this question wanted inline block, but try to view http://jsfiddle.net/N9mzE/1/ in IE 7 (the oldest browser supported where I work). The divs are not side by side.

OP said he did not want to use floats because he did not like them. Well...in my opinion, making good webpages that does not look weird in any browsers should be the maingoal, and you do this by using floats.

Honestly, I can see the problem. Floats are fantastic.

Very Long If Statement in Python

According to PEP8, long lines should be placed in parentheses. When using parentheses, the lines can be broken up without using backslashes. You should also try to put the line break after boolean operators.

Further to this, if you're using a code style check such as pycodestyle, the next logical line needs to have different indentation to your code block.

For example:

if (abcdefghijklmnopqrstuvwxyz > some_other_long_identifier and
        here_is_another_long_identifier != and_finally_another_long_name):
    # ... your code here ...
    pass

How to show git log history (i.e., all the related commits) for a sub directory of a git repo?

Enter

git log .

from the specific directory, it also gives commits in that directory.

What is object slicing?

The slicing problem in C++ arises from the value semantics of its objects, which remained mostly due to compatibility with C structs. You need to use explicit reference or pointer syntax to achieve "normal" object behavior found in most other languages that do objects, i.e., objects are always passed around by reference.

The short answers is that you slice the object by assigning a derived object to a base object by value, i.e. the remaining object is only a part of the derived object. In order to preserve value semantics, slicing is a reasonable behavior and has its relatively rare uses, which doesn't exist in most other languages. Some people consider it a feature of C++, while many considered it one of the quirks/misfeatures of C++.

How to silence output in a Bash script?

All output:

scriptname &>/dev/null

Portable:

scriptname >/dev/null 2>&1

Portable:

scriptname >/dev/null 2>/dev/null

For newer bash (no portable):

scriptname &>-

RecyclerView: Inconsistency detected. Invalid item position

For me, it worked after adding this line of code:

mRecyclerView.setItemAnimator(null);

Fast way of finding lines in one file that are not in another?

Like konsolebox suggested, the posters grep solution

grep -v -f file2 file1

actually works great (fast) if you simply add the -F option, to treat the patterns as fixed strings instead of regular expressions. I verified this on a pair of ~1000 line file lists I had to compare. With -F it took 0.031 s (real), while without it took 2.278 s (real), when redirecting grep output to wc -l.

These tests also included the -x switch, which are necessary part of the solution in order to ensure totally accuracy in cases where file2 contains lines which match part of, but not all of, one or more lines in file1.

So a solution that does not require the inputs to be sorted, is fast, flexible (case sensitivity, etc) is:

grep -F -x -v -f file2 file1

This doesn't work with all versions of grep, for example it fails in macOS, where a line in file 1 will be shown as not present in file 2, even though it is, if it matches another line that is a substring of it. Alternatively you can install GNU grep on macOS in order to use this solution.

How to set custom location for local installation of npm package?

After searching for this myself wanting several projects with shared dependencies to be DRYer, I’ve found:

  • Installing locally is the Node way for anything you want to use via require()
  • Installing globally is for binaries you want in your path, but is not intended for anything via require()
  • Using a prefix means you need to add appropriate bin and man paths to $PATH
  • npm link (info) lets you use a local install as a source for globals

? stick to the Node way and install locally

ref:

HTML/CSS: Making two floating divs the same height

I had similar problem and in my opinion best option is to use just a little bit of javascript or jquery.

You can get wanted divs to be same height by getting highest div value and applying that value to all other divs. If you have many divs and many solutions i suggest to write little advance js code to find out which of all divs is the highest and then use it's value.

With jquery and 2 divs it's very simple, here is example code:

$('.smaller-div').css('height',$('.higher-div').css('height'));

And for the end, there is 1 last thing. Their padding (top and bottom) must be the same ! If one have larger padding you need to eliminate padding difference.

XSLT - How to select XML Attribute by Attribute?

Note: using // at the beginning of the xpath is a bit CPU intensitve -- it will search every node for a match. Using a more specific path, such as /root/DataSet will create a faster query.

Convert Map<String,Object> to Map<String,String>

Now that we have Java 8/streams, we can add one more possible answer to the list:

Assuming that each of the values actually are String objects, the cast to String should be safe. Otherwise some other mechanism for mapping the Objects to Strings may be used.

Map<String,Object> map = new HashMap<>();
Map<String,String> newMap = map.entrySet().stream()
     .collect(Collectors.toMap(Map.Entry::getKey, e -> (String)e.getValue()));

TypeError: int() argument must be a string, a bytes-like object or a number, not 'list'

What the error is telling, is that you can't convert an entire list into an integer. You could get an index from the list and convert that into an integer:

x = ["0", "1", "2"] 
y = int(x[0]) #accessing the zeroth element

If you're trying to convert a whole list into an integer, you are going to have to convert the list into a string first:

x = ["0", "1", "2"]
y = ''.join(x) # converting list into string
z = int(y)

If your list elements are not strings, you'll have to convert them to strings before using str.join:

x = [0, 1, 2]
y = ''.join(map(str, x))
z = int(y)

Also, as stated above, make sure that you're not returning a nested list.

See changes to a specific file using git

Totally agree with @Greg Hewgill

And if you path includes spaces, you might use, try adding with apostrophe ' or `

git diff 'MyProject/My Folder/My Sub Folder/file_2.rb'

Capturing image from webcam in java?

Recommand using FMJ for multimedia relatived java app.

How to use in jQuery :not and hasClass() to get a specific element without a class

jQuery's hasClass() method returns a boolean (true/false) and not an element. Also, the parameter to be given to it is a class name and not a selector as such.

For ex: x.hasClass('error');

Build error: You must add a reference to System.Runtime

I had this problem in a solution with a Web API project and several library projects. One of the library projects was borking on build, with errors that said the Unity attributes weren't "valid" attributes, and then one error said I needed to reference System.Runtime.

After much searching, reinstalling the 4.5.2 Developer Pack, and nothing working, I figured maybe it was just a version mismatch. So I looked at the properties of every project, and one of the very base libraries was targeting 4.5 while every other one was targeting 4.5.2. I changed that one to also target 4.5.2 and the errors went away.

What is the size limit of a post request?

As David pointed out, I would go with KB in most cases.

php_value post_max_size 2K

Note: my form is simple, just a few text boxes, not long text.

(PHP shorthand for KB is K, as outlined here.)

Configure cron job to run every 15 minutes on Jenkins

It should be,

*/15 * * * *  your_command_or_whatever

How do I prompt for Yes/No/Cancel input in a Linux shell script?

yn() {
  if [[ 'y' == `read -s -n 1 -p "[y/n]: " Y; echo $Y` ]];
  then eval $1;
  else eval $2;
  fi }
yn 'echo yes' 'echo no'
yn 'echo absent no function works too!'

How can I override Bootstrap CSS styles?

Use jquery css instead of css . . . jquery have priority than bootstrap css...

e.g

$(document).ready(function(){
        $(".mnu").css({"color" : "#CCFF00" , "font-size": "16px" , "text-decoration" : "overline"});    


);

 instead of

.mnu
{

font-family:myfnt;
font-size:20px;
color:#006699;

}

req.query and req.param in ExpressJS

req.query will return a JS object after the query string is parsed.

/user?name=tom&age=55 - req.query would yield {name:"tom", age: "55"}

req.params will return parameters in the matched route. If your route is /user/:id and you make a request to /user/5 - req.params would yield {id: "5"}

req.param is a function that peels parameters out of the request. All of this can be found here.

UPDATE

If the verb is a POST and you are using bodyParser, then you should be able to get the form body in you function with req.body. That will be the parsed JS version of the POSTed form.

Is there a function to copy an array in C/C++?

Just include the standard library in your code.

#include<algorithm>

Array size will be denoted as n

Your old Array

int oldArray[n]={10,20,30,40,50};

Declare New Array in which you have to copy your old array value

int newArray[n];

Use this

copy_n(oldArray,n,newArray);

using javascript to detect whether the url exists before display in iframe

You can try and do a simple GET on the page, if you get a 200 back it means the page exists. Try this (using jQuery), the function is the success callback function on a successful page load. Note this will only work on sites within your domain to prevent XSS. Other domains will have to be handled server side

$.get(
   yourURL,
   function(data, textStatus, jqXHR) {
      //load the iframe here...
   }
);

How do I alter the position of a column in a PostgreSQL database table?

This post is old and probably solved but I had the same issue. I resolved it by creating a view of the original table specifying the new column order.

From here I could either use the view or create a new table from the view.

    CREATE VIEW original_tab_vw AS
    SELECT a.col1, a.col3, a.col4, a.col2
    FROM original_tab a
    WHERE a.col1 IS NOT NULL --or whatever
    SELECT * INTO new_table FROM original_tab_vw

Rename or drop the original table and set the name of the new table to the old table.

Appending to an empty DataFrame in Pandas?

And if you want to add a row, you can use a dictionary:

df = pd.DataFrame()
df = df.append({'name': 'Zed', 'age': 9, 'height': 2}, ignore_index=True)

which gives you:

   age  height name
0    9       2  Zed

What is difference between sjlj vs dwarf vs seh?

SJLJ (setjmp/longjmp): – available for 32 bit and 64 bit – not “zero-cost”: even if an exception isn’t thrown, it incurs a minor performance penalty (~15% in exception heavy code) – allows exceptions to traverse through e.g. windows callbacks

DWARF (DW2, dwarf-2) – available for 32 bit only – no permanent runtime overhead – needs whole call stack to be dwarf-enabled, which means exceptions cannot be thrown over e.g. Windows system DLLs.

SEH (zero overhead exception) – will be available for 64-bit GCC 4.8.

source: https://wiki.qt.io/MinGW-64-bit

Install a .NET windows service without InstallUtil.exe

Here is a class I use when writing services. I usually have an interactive screen that comes up when the service is not called. From there I use the class as needed. It allows for multiple named instances on the same machine -hence the InstanceID field

Sample Call

  IntegratedServiceInstaller Inst = new IntegratedServiceInstaller();
  Inst.Install("MySvc", "My Sample Service", "Service that executes something",
                    _InstanceID,
// System.ServiceProcess.ServiceAccount.LocalService,      // this is more secure, but only available in XP and above and WS-2003 and above
  System.ServiceProcess.ServiceAccount.LocalSystem,       // this is required for WS-2000
  System.ServiceProcess.ServiceStartMode.Automatic);
  if (controller == null)
  {
    controller = new System.ServiceProcess.ServiceController(String.Format("MySvc_{0}", _InstanceID), ".");
                }
                if (controller.Status == System.ServiceProcess.ServiceControllerStatus.Running)
                {
                    Start_Stop.Text = "Stop Service";
                    Start_Stop_Debugging.Enabled = false;
                }
                else
                {
                    Start_Stop.Text = "Start Service";
                    Start_Stop_Debugging.Enabled = true;
                }

The class itself

using System;
using System.Collections.Generic;
using System.Text;
using System.Diagnostics;
using Microsoft.Win32;

namespace MySvc
{
    class IntegratedServiceInstaller
    {
        public void Install(String ServiceName, String DisplayName, String Description,
            String InstanceID,
            System.ServiceProcess.ServiceAccount Account, 
            System.ServiceProcess.ServiceStartMode StartMode)
        {
            //http://www.theblacksparrow.com/
            System.ServiceProcess.ServiceProcessInstaller ProcessInstaller = new System.ServiceProcess.ServiceProcessInstaller();
            ProcessInstaller.Account = Account;

            System.ServiceProcess.ServiceInstaller SINST = new System.ServiceProcess.ServiceInstaller();

            System.Configuration.Install.InstallContext Context = new System.Configuration.Install.InstallContext();
            string processPath = Process.GetCurrentProcess().MainModule.FileName;
            if (processPath != null && processPath.Length > 0)
            {
                System.IO.FileInfo fi = new System.IO.FileInfo(processPath);

                String path = String.Format("/assemblypath={0}", fi.FullName);
                String[] cmdline = { path };
                Context = new System.Configuration.Install.InstallContext("", cmdline);
            }

            SINST.Context = Context;
            SINST.DisplayName = String.Format("{0} - {1}", DisplayName, InstanceID);
            SINST.Description = String.Format("{0} - {1}", Description, InstanceID);
            SINST.ServiceName = String.Format("{0}_{1}", ServiceName, InstanceID);
            SINST.StartType = StartMode;
            SINST.Parent = ProcessInstaller;

            // http://bytes.com/forum/thread527221.html
            SINST.ServicesDependedOn = new String[] { "Spooler", "Netlogon", "Netman" };

            System.Collections.Specialized.ListDictionary state = new System.Collections.Specialized.ListDictionary();
            SINST.Install(state);

            // http://www.dotnet247.com/247reference/msgs/43/219565.aspx
            using (RegistryKey oKey = Registry.LocalMachine.OpenSubKey(String.Format(@"SYSTEM\CurrentControlSet\Services\{0}_{1}", ServiceName, InstanceID), true))
            {
                try
                {
                    Object sValue = oKey.GetValue("ImagePath");
                    oKey.SetValue("ImagePath", sValue);
                }
                catch (Exception Ex)
                {
                    System.Windows.Forms.MessageBox.Show(Ex.Message);
                }
            }

        }
        public void Uninstall(String ServiceName, String InstanceID)
        {
            //http://www.theblacksparrow.com/
            System.ServiceProcess.ServiceInstaller SINST = new System.ServiceProcess.ServiceInstaller();

            System.Configuration.Install.InstallContext Context = new System.Configuration.Install.InstallContext("c:\\install.log", null);
            SINST.Context = Context;
            SINST.ServiceName = String.Format("{0}_{1}", ServiceName, InstanceID);
            SINST.Uninstall(null);
        }
    }
}

Display date/time in user's locale format and time offset

You can use new Date().getTimezoneOffset()/60 for the timezone. There is also a toLocaleString() method for displaying a date using the user's locale.

Here's the whole list: Working with Dates

pass array to method Java

class test
{
    void passArr()
    {
        int arr1[]={1,2,3,4,5,6,7,8,9};
        printArr(arr1);
    }

    void printArr(int[] arr2)
    {
        for(int i=0;i<arr2.length;i++)
        {
            System.out.println(arr2[i]+"  ");
        }
    }

    public static void main(String[] args)
    {
        test ob=new test();
        ob.passArr();
    }
}

How to append one DataTable to another DataTable

Merge takes a DataTable, Load requires an IDataReader - so depending on what your data layer gives you access to, use the required method. My understanding is that Load will internally call Merge, but not 100% sure about that.

If you have two DataTables, use Merge.

What does ** (double star/asterisk) and * (star/asterisk) do for parameters?

*args and **kwargs: allow you to pass a variable number of arguments to a function.

*args: is used to send a non-keyworded variable length argument list to the function:

def args(normal_arg, *argv):
    print("normal argument:", normal_arg)

    for arg in argv:
        print("Argument in list of arguments from *argv:", arg)

args('animals', 'fish', 'duck', 'bird')

Will produce:

normal argument: animals
Argument in list of arguments from *argv: fish
Argument in list of arguments from *argv: duck
Argument in list of arguments from *argv: bird

**kwargs*

**kwargs allows you to pass keyworded variable length of arguments to a function. You should use **kwargs if you want to handle named arguments in a function.

def who(**kwargs):
    if kwargs is not None:
        for key, value in kwargs.items():
            print("Your %s is %s." % (key, value))

who(name="Nikola", last_name="Tesla", birthday="7.10.1856", birthplace="Croatia")  

Will produce:

Your name is Nikola.
Your last_name is Tesla.
Your birthday is 7.10.1856.
Your birthplace is Croatia.

Why are there two ways to unstage a file in Git?

Quite simply:

  • git rm --cached <file> makes git stop tracking the file completely (leaving it in the filesystem, unlike plain git rm*)
  • git reset HEAD <file> unstages any modifications made to the file since the last commit (but doesn't revert them in the filesystem, contrary to what the command name might suggest**). The file remains under revision control.

If the file wasn't in revision control before (i.e. you're unstaging a file that you had just git added for the first time), then the two commands have the same effect, hence the appearance of these being "two ways of doing something".

* Keep in mind the caveat @DrewT mentions in his answer, regarding git rm --cached of a file that was previously committed to the repository. In the context of this question, of a file just added and not committed yet, there's nothing to worry about.

** I was scared for an embarrassingly long time to use the git reset command because of its name -- and still today I often look up the syntax to make sure I don't screw up. (update: I finally took the time to summarize the usage of git reset in a tldr page, so now I have a better mental model of how it works, and a quick reference for when I forget some detail.)

"Port 4200 is already in use" when running the ng serve command

In Windows; In command prompt which is running your ng serve just click and press keys:

ctrl + c

It will ask you: Terminate batch job (Y/N)? and you type Y

Why should Java 8's Optional not be used in arguments

There are almost no good reasons for not using Optional as parameters. The arguments against this rely on arguments from authority (see Brian Goetz - his argument is we can't enforce non null optionals) or that the Optional arguments may be null (essentially the same argument). Of course, any reference in Java can be null, we need to encourage rules being enforced by the compiler, not programmers memory (which is problematic and does not scale).

Functional programming languages encourage Optional parameters. One of the best ways of using this is to have multiple optional parameters and using liftM2 to use a function assuming the parameters are not empty and returning an optional (see http://www.functionaljava.org/javadoc/4.4/functionaljava/fj/data/Option.html#liftM2-fj.F-). Java 8 has unfortunately implemented a very limited library supporting optional.

As Java programmers we should only be using null to interact with legacy libraries.

Get img src with PHP

You would be better off using a DOM parser for this kind of HTML parsing. Consider this code:

$html = '<img id="12" border="0" src="/images/image.jpg"
         alt="Image" width="100" height="100" />';
$doc = new DOMDocument();
libxml_use_internal_errors(true);
$doc->loadHTML($html); // loads your html
$xpath = new DOMXPath($doc);
$nodelist = $xpath->query("//img"); // find your image
$node = $nodelist->item(0); // gets the 1st image
$value = $node->attributes->getNamedItem('src')->nodeValue;
echo "src=$value\n"; // prints src of image

OUTPUT:

src=/images/image.jpg

PostgreSQL: How to change PostgreSQL user password?

For my case on Ubuntu 14.04 installed with postgres 10.3. I need to follow the following steps

  • su - postgres to switch user to postgres
  • psql to enter postgres shell
  • \password then enter your password
  • \q to quit the shell session
  • Then you switch back to root by executing exit and configure your pg_hba.conf (mine is at /etc/postgresql/10/main/pg_hba.conf) by making sure you have the following line

    local all postgres md5

  • Restart your postgres service by service postgresql restart
  • Now switch to postgres user and enter postgres shell again. It will prompt you with password.

Responsive width Facebook Page Plugin

After struggling for some time, I think I found out quite simple solution.

Inspired by Robin Wilson I made this simple JS function (the original resizes both width and height, mine is just for the width):

 function changeFBPagePlugin() {
    var container_width = Number($('.fb-container').width()).toFixed(0);
    if (!isNaN(container_width)) {
        $(".fb-page").attr("data-width", container_width);
    }
    if (typeof FB !== 'undefined') {
        FB.XFBML.parse();
    }
};

It checks for the current width of the wrapping div and then puts the value inside fb-page div. The magic is done with FB.XFBML object, that is a part of Facebook SDK, which becomes available when you initialize the fb-page itself via window.fbAsyncInit

I bind my function to html body's onLoad and onResize:

<body onload="changeFBPagePlugin()" onresize="changeFBPagePlugin()">

On the page I have my fb-page plugin wrapped in another div that is used as reference:

<div class="fb-container"> 
    <div class="fb-page" ...stuff you need for FB page plugin... </div>
</div>

Finally the simple CSS for the wrapper to assure it stretches over the available space:

.fb-container {
    width: 95%;
    margin: 0px auto;
}

Putting all this together the results seem quite satisfying. Hopefuly this will help someone, although the question was posted quite a long time ago.

jQuery Multiple ID selectors

Try this:

$("#upload_link,#upload_link2,#upload_link3").each(function(){
    $(this).upload({
        //whateveryouwant
    });
});

How to get the string size in bytes?

I like to use:

(strlen(string) + 1 ) * sizeof(char)

This will give you the buffer size in bytes. You can use this with snprintf() may help:

const char* message = "%s, World!";
char* string = (char*)malloc((strlen(message)+1))*sizeof(char));
snprintf(string, (strlen(message)+1))*sizeof(char), message, "Hello");

Cheers! Function: size_t strlen (const char *s)

How to change Vagrant 'default' machine name?

In case there are many people using your vagrant file - you might want to set name dynamically. Below is the example how to do it using username from your HOST machine as the name of the box and hostname:

require 'etc'
vagrant_name = "yourProjectName-" + Etc.getlogin
Vagrant.configure("2") do |config|
  config.vm.box = "ubuntu/xenial64"
  config.vm.hostname = vagrant_name
  config.vm.provider "virtualbox" do |v|
    v.name = vagrant_name
  end
end

Rails 3: I want to list all paths defined in my rails application

Update

I later found that, there is an official way to see all the routes, by going to http://localhost:3000/rails/info/routes. Official docs: https://guides.rubyonrails.org/routing.html#listing-existing-routes


Though, it may be late, But I love the error page which displays all the routes. I usually try to go at /routes (or some bogus) path directly from the browser. Rails server automatically gives me a routing error page as well as all the routes and paths defined. That was very helpful :)

So, Just go to http://localhost:3000/routes enter image description here

Resource interpreted as Document but transferred with MIME type application/json warning in Chrome Developer Tools

This type of warnings are usually flagged because of the request HTTP headers. Specifically the Accept request header. The MDN documentation for HTTP headers states

The Accept request HTTP header advertises which content types, expressed as MIME types, the client is able to understand. Using content negotiation, the server then selects one of the proposals, uses it and informs the client of its choice with the Content-Type response header. Browsers set adequate values for this header depending of the context where the request is done....

application/json is probably not on the list of MIME types in the Accept header sent by the browser hence the warning.

Solution

Custom HTTP headers can only be sent programmatically via XMLHttpRequest or any of the js library wrappers implementing it.

Compiling with g++ using multiple cores

People have mentioned make but bjam also supports a similar concept. Using bjam -jx instructs bjam to build up to x concurrent commands.

We use the same build scripts on Windows and Linux and using this option halves our build times on both platforms. Nice.

Handling of non breaking space: <p>&nbsp;</p> vs. <p> </p>

How about a workaround? In my case I took the value of the textarea in a jQuery variable, and changed all "<p>&nbsp" to <p class="clear"> and clear class to have certain height and margin, as the following example:

jQuery

tinyMCE.triggerSave();
var val = $('textarea').val();
val = val.replace(/<p>&nbsp/g, '<p class="clear">');

the val is then saved to the database with the new val.

CSS

p.clear{height: 2px; margin-bottom: 3px;}

You can adjust the height & margin as you wish. And since 'p' is a display: block element. it should give you the expected output.

Hope that helps!

How to remove all subviews of a view in Swift?

For removing just subviews of a specific class - this was the only Swift code that worked for me in Xcode6.1.1. Assuming the only subviews you want to remove are of type UIButton...

for subView in nameofmysuperview.subviews {
    if subView.isKindOfClass(UIButton) {
        subView.removeFromSuperview()
    }
}

Difference between exit() and sys.exit() in Python

If I use exit() in a code and run it in the shell, it shows a message asking whether I want to kill the program or not. It's really disturbing. See here

But sys.exit() is better in this case. It closes the program and doesn't create any dialogue box.

Python functions call by reference

class demoClass:
    x = 4
    y = 3
foo1 = demoClass()
foo1.x = 2
foo2 = demoClass()
foo2.y = 5
def mySquare(myObj):
    myObj.x = myObj.x**2
    myObj.y = myObj.y**2
print('foo1.x =', foo1.x)
print('foo1.y =', foo1.y)
print('foo2.x =', foo2.x)
print('foo2.y =', foo2.y)
mySquare(foo1)
mySquare(foo2)
print('After square:')
print('foo1.x =', foo1.x)
print('foo1.y =', foo1.y)
print('foo2.x =', foo2.x)
print('foo2.y =', foo2.y)

Python map object is not subscriptable

In Python 3, map returns an iterable object of type map, and not a subscriptible list, which would allow you to write map[i]. To force a list result, write

payIntList = list(map(int,payList))

However, in many cases, you can write out your code way nicer by not using indices. For example, with list comprehensions:

payIntList = [pi + 1000 for pi in payList]
for pi in payIntList:
    print(pi)

Cannot find R.layout.activity_main

There is probably an issue with the layout files, correct it and the auto generated class will appear.

Angular 2 - NgFor using numbers instead collections

Since the fill() method (mentioned in the accepted answer) without arguments throw an error, I would suggest something like this (works for me, Angular 7.0.4, Typescript 3.1.6)

<div class="month" *ngFor="let item of items">
...
</div>

In component code:

this.items = Array.from({length: 10}, (v, k) => k + 1);

How to hide code from cells in ipython notebook visualized with nbviewer?

The accepted solution also works in julia Jupyter/IJulia with the following modifications:

display("text/html", """<script>
code_show=true; 
function code_toggle() {
 if (code_show){
 \$("div.input").hide();
 } else {
 \$("div.input").show();
 }
 code_show = !code_show
} 
\$( document ).ready(code_toggle);
</script>
<form action="javascript:code_toggle()"><input type="submit" value="Click here to toggle on/off the raw code."></form>""")

note in particular:

  • use the display function
  • escape the $ sign (otherwise seen as a variable)

The name 'InitializeComponent' does not exist in the current context

None of the above answers worked for me. I tried them all except the duplicate ones. However for some weird reason this worked in my cross-platform project in Visual Studio 2015:

  1. Right-click the project that is causing the problem in the Solution Explorer. In the pop-up menu choose: Add --> Class
  2. Select cross-platform --> Forms Xaml Page. Keep the pretty Page1.cs standard name and click Add.
  3. Notice how the previous InitializeComponent()-problem just disappeared for some reason.
  4. Delete the newly created Page1.cs and continue programming as if Visual Studio was working just fine.

Fundamental difference between Hashing and Encryption algorithms

Cryptography deals with numbers and strings. Basically every digital thing in the entire universe are numbers. When I say numbers, its 0 & 1. You know what they are, binary. The images you see on screen, the music that you listen through your earphone, everything are binaries. But our ears and eyes will not understand binaries right? Only brain could understand that, and even if it could understand binaries, it can’t enjoy binaries. So we convert the binaries to human understandable formats such as mp3,jpg,etc. Let’s term the process as Encoding. It’s two way process and can be easily decoded back to its original form.

Hashing

Hashing is another cryptography technique in which a data once converted to some other form can never be recovered back. In Layman’s term, there is no process called de-hashing. There are many hash functions to do the job such as sha-512, md5 and so on.

If the original value cannot be recovered, then where do we use this? Passwords! When you set up a password for your mobile or PC, a hash of your password is created and stored in a secure place. When you make a login attempt next time, the entered string is again hashed with the same algorithm (hash function) and the output is matched with the stored value. If it’s the same, you get logged in. Otherwise you are thrown out.

Credits: wikimedia By applying hash to the password, we can ensure that an attacker will never get our password even if he steal the stored password file. The attacker will have the hash of the password. He can probably find a list of most commonly used passwords and apply sha-512 to each of it and compare it with the value in his hand. It is called the dictionary attack. But how long would he do this? If your password is random enough, do you think this method of cracking would work? All the passwords in the databases of Facebook, Google and Amazon are hashed, or at least they are supposed to be hashed.

Then there is Encryption

Encryption lies in between hashing and encoding. Encoding is a two way process and should not be used to provide security. Encryption is also a two way process, but original data can be retrieved if and only if the encryption key is known. If you don’t know how encryption works, don’t worry, we will discuss the basics here. That would be enough to understand the basics of SSL. So, there are two types of Encryption namely Symmetric and Asymmetric encryption.

Symmetric Key Encryption

I am trying to keep things as simple as I could. So, let’s understand the symmetric encryption by means of a shift algorithm. This algorithm is used to encrypt alphabets by shifting the letters to either left or right. Let’s take a string CRYPTO and consider a number +3. Then, the encrypted format of CRYPTO will be FUBSWR. That means each letter is shifted to right by 3 places. Here, the word CRYPTO is called Plaintext, the output FUBSWR is called the Ciphertext, the value +3 is called the Encryption key (symmetric key) and the whole process is a cipher. This is one of the oldest and basic symmetric key encryption algorithm and its first usage was reported during the time of Julius Caesar. So, it was named after him and it is the famous Caesar Cipher. Anyone who knows the encryption key and can apply the reverse of Caesar’s algorithm and retrieve the original Plaintext. Hence it is called a Symmetric Encryption.

Asymmetric Key Encryption

We know that, in Symmetric encryption same key is used for both encryption and decryption. Once that key is stolen, all the data is gone. That’s a huge risk and we need more complex technique. In 1976, Whitfield Diffie and Martin Hellman first published the concept of Asymmetric encryption and the algorithm was known as Diffie–Hellman key exchange. Then in 1978, Ron Rivest, Adi Shamir and Leonard Adleman of MIT published the RSA algorithm. These can be considered as the foundation of Asymmetric cryptography.

As compared to Symmetric encryption, in Asymmetric encryption, there will be two keys instead of one. One is called the Public key, and the other one is the Private key. Theoretically, during initiation we can generate the Public-Private key pair to our machine. Private key should be kept in a safe place and it should never be shared with anyone. Public key, as the name indicates, can be shared with anyone who wish to send encrypted text to you. Now, those who have your public key can encrypt the secret data with it. If the key pair were generated using RSA algorithm, then they should use the same algorithm while encrypting the data. Usually the algorithm will be specified in the public key. The encrypted data can only be decrypted with the private key which is owned by you.

Source: SSL/TLS for dummies part 1 : Ciphersuite, Hashing,Encryption | WST (https://www.wst.space/ssl-part1-ciphersuite-hashing-encryption/)

ssl.SSLError: tlsv1 alert protocol version

For Mac OS X

1) Update to Python 3.6.5 using the native app installer downloaded from the official Python language website https://www.python.org/downloads/

I've found that the installer is taking care of updating the links and symlinks for the new Python a lot better than homebrew.

2) Install a new certificate using "./Install Certificates.command" which is in the refreshed Python 3.6 directory

> cd "/Applications/Python 3.6/"
> sudo "./Install Certificates.command"

Where does gcc look for C and C++ header files?

`gcc -print-prog-name=cc1plus` -v

This command asks gcc which C++ preprocessor it is using, and then asks that preprocessor where it looks for includes.

You will get a reliable answer for your specific setup.

Likewise, for the C preprocessor:

`gcc -print-prog-name=cpp` -v

How to create .ipa file using Xcode?

Click Product > Archive from the menu, once this is complete open up the Organiser and click the latest version > Distribute > Save for Enterprise or Ad-Hoc Deployment > Choose correct signing > Save to destination

Disabling browser caching for all browsers from ASP.NET

I'm going to test adding the no-store tag to our site to see if this makes a difference to browser caching (Chrome has sometimes been caching the pages). I also found this article very useful on documentation on how and why caching works and will look at ETag's next if the no-store is not reliable:

http://www.mnot.net/cache_docs/

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

Why when I transfer a file through SFTP, it takes longer than FTP?

Yes, encryption add some load to your cpu, but if your cpu is not ancient that should not affect as much as you say.

If you enable compression for SSH, SCP is actually faster than FTP despite the SSH encryption (if I remember, twice as fast as FTP for the files I tried). I haven't actually used SFTP, but I believe it uses SCP for the actual file transfer. So please try this and let us know :-)

How does MySQL CASE work?

CASE is more like a switch statement. It has two syntaxes you can use. The first lets you use any compare statements you want:

CASE 
    WHEN user_role = 'Manager' then 4
    WHEN user_name = 'Tom' then 27
    WHEN columnA <> columnB then 99
    ELSE -1 --unknown
END

The second style is for when you are only examining one value, and is a little more succinct:

CASE user_role
    WHEN 'Manager' then 4
    WHEN 'Part Time' then 7
    ELSE -1 --unknown
END

Dynamically load JS inside JS

Necromancing.

I use this to load dependant scripts;
it works with IE8+ without adding any dependency on another library like jQuery !

var cScriptLoader = (function ()
{
    function cScriptLoader(files)
    {
        var _this = this;
        this.log = function (t)
        {
            console.log("ScriptLoader: " + t);
        };
        this.withNoCache = function (filename)
        {
            if (filename.indexOf("?") === -1)
                filename += "?no_cache=" + new Date().getTime();
            else
                filename += "&no_cache=" + new Date().getTime();
            return filename;
        };
        this.loadStyle = function (filename)
        {
            // HTMLLinkElement
            var link = document.createElement("link");
            link.rel = "stylesheet";
            link.type = "text/css";
            link.href = _this.withNoCache(filename);
            _this.log('Loading style ' + filename);
            link.onload = function ()
            {
                _this.log('Loaded style "' + filename + '".');
            };
            link.onerror = function ()
            {
                _this.log('Error loading style "' + filename + '".');
            };
            _this.m_head.appendChild(link);
        };
        this.loadScript = function (i)
        {
            var script = document.createElement('script');
            script.type = 'text/javascript';
            script.src = _this.withNoCache(_this.m_js_files[i]);
            var loadNextScript = function ()
            {
                if (i + 1 < _this.m_js_files.length)
                {
                    _this.loadScript(i + 1);
                }
            };
            script.onload = function ()
            {
                _this.log('Loaded script "' + _this.m_js_files[i] + '".');
                loadNextScript();
            };
            script.onerror = function ()
            {
                _this.log('Error loading script "' + _this.m_js_files[i] + '".');
                loadNextScript();
            };
            _this.log('Loading script "' + _this.m_js_files[i] + '".');
            _this.m_head.appendChild(script);
        };
        this.loadFiles = function ()
        {
            // this.log(this.m_css_files);
            // this.log(this.m_js_files);
            for (var i = 0; i < _this.m_css_files.length; ++i)
                _this.loadStyle(_this.m_css_files[i]);
            _this.loadScript(0);
        };
        this.m_js_files = [];
        this.m_css_files = [];
        this.m_head = document.getElementsByTagName("head")[0];
        // this.m_head = document.head; // IE9+ only
        function endsWith(str, suffix)
        {
            if (str === null || suffix === null)
                return false;
            return str.indexOf(suffix, str.length - suffix.length) !== -1;
        }
        for (var i = 0; i < files.length; ++i)
        {
            if (endsWith(files[i], ".css"))
            {
                this.m_css_files.push(files[i]);
            }
            else if (endsWith(files[i], ".js"))
            {
                this.m_js_files.push(files[i]);
            }
            else
                this.log('Error unknown filetype "' + files[i] + '".');
        }
    }
    return cScriptLoader;
})();
var ScriptLoader = new cScriptLoader(["foo.css", "Scripts/Script4.js", "foobar.css", "Scripts/Script1.js", "Scripts/Script2.js", "Scripts/Script3.js"]);
ScriptLoader.loadFiles();

If you are interested in the typescript-version used to create this:

class cScriptLoader {
    private m_js_files: string[];
    private m_css_files: string[];
    private m_head:HTMLHeadElement;
    
    private log = (t:any) =>
    {
        console.log("ScriptLoader: " + t);
    }
    
    
    constructor(files: string[]) {
        this.m_js_files = [];
        this.m_css_files = [];
        this.m_head = document.getElementsByTagName("head")[0];
        // this.m_head = document.head; // IE9+ only
        
        
        function endsWith(str:string, suffix:string):boolean 
        {
            if(str === null || suffix === null)
                return false;
                
            return str.indexOf(suffix, str.length - suffix.length) !== -1;
        }
        
        
        for(let i:number = 0; i < files.length; ++i) 
        {
            if(endsWith(files[i], ".css"))
            {
                this.m_css_files.push(files[i]);
            }
            else if(endsWith(files[i], ".js"))
            {
                this.m_js_files.push(files[i]);
            }
            else
                this.log('Error unknown filetype "' + files[i] +'".');
        }
        
    }
    
    
    public withNoCache = (filename:string):string =>
    {
        if(filename.indexOf("?") === -1)
            filename += "?no_cache=" + new Date().getTime();
        else
            filename += "&no_cache=" + new Date().getTime();
            
        return filename;    
    }
    

    public loadStyle = (filename:string) =>
    {
        // HTMLLinkElement
        let link = document.createElement("link");
        link.rel = "stylesheet";
        link.type = "text/css";
        link.href = this.withNoCache(filename);
        
        this.log('Loading style ' + filename);
        link.onload = () =>
        {
            this.log('Loaded style "' + filename + '".');
            
        };
        
        link.onerror = () =>
        {
            this.log('Error loading style "' + filename + '".');
        };
        
        this.m_head.appendChild(link);
    }
    
    
    public loadScript = (i:number) => 
    {
        let script = document.createElement('script');
        script.type = 'text/javascript';
        script.src = this.withNoCache(this.m_js_files[i]);
        
        var loadNextScript = () => 
        {
            if (i + 1 < this.m_js_files.length)
            {
                this.loadScript(i + 1);
            }
        }
        
        script.onload = () =>
        {
            this.log('Loaded script "' + this.m_js_files[i] + '".');
            loadNextScript();
        };
        
        
        script.onerror = () =>
        {
            this.log('Error loading script "' + this.m_js_files[i] + '".');
            loadNextScript();
        };
        
        
        this.log('Loading script "' + this.m_js_files[i] + '".');
        this.m_head.appendChild(script);
    }
    
    public loadFiles = () => 
    {
        // this.log(this.m_css_files);
        // this.log(this.m_js_files);
        
        for(let i:number = 0; i < this.m_css_files.length; ++i)
            this.loadStyle(this.m_css_files[i])
        
        this.loadScript(0);
    }
    
}


var ScriptLoader = new cScriptLoader(["foo.css", "Scripts/Script4.js", "foobar.css", "Scripts/Script1.js", "Scripts/Script2.js", "Scripts/Script3.js"]);
ScriptLoader.loadFiles();

If it's to load a dynamic list of scripts, write the scripts into an attribute, such as data-main, e.g. <script src="scriptloader.js" data-main="file1.js,file2.js,file3.js,etc." ></script>
and do a element.getAttribute("data-main").split(',')

such as

var target = document.currentScript || (function() {
  var scripts = document.getElementsByTagName('script');
  // Note: this is for IE as IE doesn't support currentScript
  // this does not work if you have deferred loading with async
  // e.g. <script src="..." async="async" ></script>
  // https://web.archive.org/web/20180618155601/https://www.w3schools.com/TAgs/att_script_async.asp
  return scripts[scripts.length - 1];
})();

target.getAttribute("data-main").split(',')

to obtain the list.

Creating a LINQ select from multiple tables

You can use anonymous types for this, i.e.:

var pageObject = (from op in db.ObjectPermissions
                  join pg in db.Pages on op.ObjectPermissionName equals page.PageName
                  where pg.PageID == page.PageID
                  select new { pg, op }).SingleOrDefault();

This will make pageObject into an IEnumerable of an anonymous type so AFAIK you won't be able to pass it around to other methods, however if you're simply obtaining data to play with in the method you're currently in it's perfectly fine. You can also name properties in your anonymous type, i.e.:-

var pageObject = (from op in db.ObjectPermissions
                  join pg in db.Pages on op.ObjectPermissionName equals page.PageName
                  where pg.PageID == page.PageID
                  select new
                  {
                      PermissionName = pg, 
                      ObjectPermission = op
                  }).SingleOrDefault();

This will enable you to say:-

if (pageObject.PermissionName.FooBar == "golden goose") Application.Exit();

For example :-)

How do I remove a submodule?

Since git1.8.3 (April 22d, 2013):

There was no Porcelain way to say "I no longer am interested in this submodule", once you express your interest in a submodule with "submodule init".
"submodule deinit" is the way to do so.

The deletion process also uses git rm (since git1.8.5 October 2013).

Summary

The 3-steps removal process would then be:

0. mv a/submodule a/submodule_tmp

1. git submodule deinit -f -- a/submodule    
2. rm -rf .git/modules/a/submodule
3. git rm -f a/submodule
# Note: a/submodule (no trailing slash)

# or, if you want to leave it in your working tree and have done step 0
3.   git rm --cached a/submodule
3bis mv a/submodule_tmp a/submodule

Explanation

rm -rf: This is mentioned in Daniel Schroeder's answer, and summarized by Eonil in the comments:

This leaves .git/modules/<path-to-submodule>/ unchanged.
So if you once delete a submodule with this method and re-add them again, it will not be possible because repository already been corrupted.


git rm: See commit 95c16418:

Currently using "git rm" on a submodule removes the submodule's work tree from that of the superproject and the gitlink from the index.
But the submodule's section in .gitmodules is left untouched, which is a leftover of the now removed submodule and might irritate users (as opposed to the setting in .git/config, this must stay as a reminder that the user showed interest in this submodule so it will be repopulated later when an older commit is checked out).

Let "git rm" help the user by not only removing the submodule from the work tree but by also removing the "submodule.<submodule name>" section from the .gitmodules file and stage both.


git submodule deinit: It stems from this patch:

With "git submodule init" the user is able to tell git they care about one or more submodules and wants to have it populated on the next call to "git submodule update".
But currently there is no easy way they can tell git they do not care about a submodule anymore and wants to get rid of the local work tree (unless the user knows a lot about submodule internals and removes the "submodule.$name.url" setting from .git/config together with the work tree himself).

Help those users by providing a 'deinit' command.
This removes the whole submodule.<name> section from .git/config either for the given submodule(s) (or for all those which have been initialized if '.' is given).
Fail if the current work tree contains modifications unless forced.
Complain when for a submodule given on the command line the url setting can't be found in .git/config, but nonetheless don't fail.

This takes care if the (de)initialization steps (.git/config and .git/modules/xxx)

Since git1.8.5, the git rm takes also care of the:

  • 'add' step which records the url of a submodule in the .gitmodules file: it is need to removed for you.
  • the submodule special entry (as illustrated by this question): the git rm removes it from the index:
    git rm --cached path_to_submodule (no trailing slash)
    That will remove that directory stored in the index with a special mode "160000", marking it as a submodule root directory.

If you forget that last step, and try to add what was a submodule as a regular directory, you would get error message like:

git add mysubmodule/file.txt 
Path 'mysubmodule/file.txt' is in submodule 'mysubmodule'

Note: since Git 2.17 (Q2 2018), git submodule deinit is no longer a shell script.
It is a call to a C function.

See commit 2e61273, commit 1342476 (14 Jan 2018) by Prathamesh Chavan (pratham-pc).
(Merged by Junio C Hamano -- gitster -- in commit ead8dbe, 13 Feb 2018)

git ${wt_prefix:+-C "$wt_prefix"} submodule--helper deinit \
  ${GIT_QUIET:+--quiet} \
  ${prefix:+--prefix "$prefix"} \
  ${force:+--force} \
  ${deinit_all:+--all} "$@"

There is already an object named in the database

"There is already an object named 'AboutUs' in the database."

This exception tells you that somebody has added an object named 'AboutUs' to the database already.

AutomaticMigrationsEnabled = true; can lead to it since data base versions are not controlled by you in this case. In order to avoid unpredictable migrations and make sure that every developer on the team works with the same data base structure I suggest you set AutomaticMigrationsEnabled = false;.

Automatic migrations and Coded migrations can live alongside if you are very careful and the only one developer on a project.

There is a quote from Automatic Code First Migrations post on Data Developer Center:

Automatic Migrations allows you to use Code First Migrations without having a code file in your project for each change you make. Not all changes can be applied automatically - for example column renames require the use of a code-based migration.

Recommendation for Team Environments

You can intersperse automatic and code-based migrations but this is not recommended in team development scenarios. If you are part of a team of developers that use source control you should either use purely automatic migrations or purely code-based migrations. Given the limitations of automatic migrations we recommend using code-based migrations in team environments.

Add and remove a class on click using jQuery?

Try this in your Head section of the site:

$(function() {
    $('.menu_box_list li').click(function() {
        $('.menu_box_list li.active').removeClass('active');
        $(this).addClass('active');
    });
});

Draw a connecting line between two elements

JointJS/Rappid supports this use case with its Kitchensink example which supports dragging and dropping of elements, and repositioning of connections. It has many examples.

This answer is based off of Vainbhav Jain's answer.

R not finding package even after package installation

So the package will be downloaded in a temp folder C:\Users\U122337.BOSTONADVISORS\AppData\Local\Temp\Rtmp404t8Y\downloaded_packages from where it will be installed into your library folder, e.g. C:\R\library\zoo

What you have to do once install command is done: Open Packages menu -> Load package...

You will see your package on the list. You can automate this: How to load packages in R automatically?

Detect whether Office is 32bit or 64bit via the registry

Search the registry for the install path of the office component you are interested in, e.g. for Excel 2010 look in SOFTWARE(Wow6432Node)\Microsoft\Office\14.0\Excel\InstallRoot. It will only be either in the 32-bit registry or the 64-bit registry not both.

How to get unique values in an array

Another thought of this question. Here is what I did to achieve this with fewer code.

_x000D_
_x000D_
var distinctMap = {};_x000D_
var testArray = ['John', 'John', 'Jason', 'Jason'];_x000D_
for (var i = 0; i < testArray.length; i++) {_x000D_
  var value = testArray[i];_x000D_
  distinctMap[value] = '';_x000D_
};_x000D_
var unique_values = Object.keys(distinctMap);_x000D_
_x000D_
console.log(unique_values);
_x000D_
_x000D_
_x000D_

what is the difference between uint16_t and unsigned short int incase of 64 bit processor?

uint16_t is guaranteed to be a unsigned integer that is 16 bits large

unsigned short int is guaranteed to be a unsigned short integer, where short integer is defined by the compiler (and potentially compiler flags) you are currently using. For most compilers for x86 hardware a short integer is 16 bits large.

Also note that per the ANSI C standard only the minimum size of 16 bits is defined, the maximum size is up to the developer of the compiler

Minimum Type Limits

Any compiler conforming to the Standard must also respect the following limits with respect to the range of values any particular type may accept. Note that these are lower limits: an implementation is free to exceed any or all of these. Note also that the minimum range for a char is dependent on whether or not a char is considered to be signed or unsigned.

Type Minimum Range

signed char     -127 to +127
unsigned char      0 to 255
short int     -32767 to +32767
unsigned short int 0 to 65535

How can I open a .tex file?

A .tex file should be a LaTeX source file.

If this is the case, that file contains the source code for a LaTeX document. You can open it with any text editor (notepad, notepad++ should work) and you can view the source code. But if you want to view the final formatted document, you need to install a LaTeX distribution and compile the .tex file.

Of course, any program can write any file with any extension, so if this is not a LaTeX document, then we can't know what software you need to install to open it. Maybe if you upload the file somewhere and link it in your question we can see the file and provide more help to you.


Yes, this is the source code of a LaTeX document. If you were able to paste it here, then you are already viewing it. If you want to view the compiled document, you need to install a LaTeX distribution. You can try to install MiKTeX then you can use that to compile the document to a .pdf file.

You can also check out this question and answer for how to do it: How to compile a LaTeX document?

Also, there's an online LaTeX editor and you can paste your code in there to preview the document: https://www.overleaf.com/.

Heroku "psql: FATAL: remaining connection slots are reserved for non-replication superuser connections"

I actually tried to implement connection pooling on the django end using:

https://github.com/gmcguire/django-db-pool

but I still received this error, despite lowering the number of connections available to below the standard development DB quota of 20 open connections.

There is an article here about how to move your postgresql database to the free/cheap tier of Amazon RDS. This would allow you to set max_connections higher. This will also allow you to pool connections at the database level using PGBouncer.

https://www.lewagon.com/blog/how-to-migrate-heroku-postgres-database-to-amazon-rds

UPDATE:

Heroku responded to my open ticket and stated that my database was improperly load balanced in their network. They said that improvements to their system should prevent similar problems in the future. Nonetheless, support manually relocated my database and performance is noticeably improved.

MVC If statement in View

You only need to prefix an if statement with @ if you're not already inside a razor code block.

Edit: You have a couple of things wrong with your code right now.

You're declaring nmb, but never actually doing anything with the value. So you need figure out what that's supposed to actually be doing. In order to fix your code, you need to make a couple of tiny changes:

@if (ViewBag.Articles != null)
{
    int nmb = 0;
    foreach (var item in ViewBag.Articles)
    {
        if (nmb % 3 == 0)
        {
            @:<div class="row"> 
        }

        <a href="@Url.Action("Article", "Programming", new { id = item.id })">
            <div class="tasks">
                <div class="col-md-4">
                    <div class="task important">
                        <h4>@item.Title</h4>
                        <div class="tmeta">
                            <i class="icon-calendar"></i>
                                @item.DateAdded - Pregleda:@item.Click
                            <i class="icon-pushpin"></i> Authorrr
                        </div>
                    </div>
                </div>
            </div>
        </a>
        if (nmb % 3 == 0)
        {
            @:</div>
        }
    }
}

The important part here is the @:. It's a short-hand of <text></text>, which is used to force the razor engine to render text.

One other thing, the HTML standard specifies that a tags can only contain inline elements, and right now, you're putting a div, which is a block-level element, inside an a.

How to specify font attributes for all elements on an html web page?

If you want to set styles of all elements in body you should use next code^

  body{
    color: green;
    }

Autoresize View When SubViews are Added

Yes, it is because you are using auto layout. Setting the view frame and resizing mask will not work.

You should read Working with Auto Layout Programmatically and Visual Format Language.

You will need to get the current constraints, add the text field, adjust the contraints for the text field, then add the correct constraints on the text field.

Pretty git branch graphs

Gitg is a clone of Gitk and GitX for GNOME (it also works on KDE etc.) which shows a pretty colored graph.

It is actively developed (as of 2012). It lets you sort the commits (graph nodes) either chronologically or topologically, and hide commits that don't lead to a selected branch.

It works fine with large repositories and complex dependency graphs.

Sample screenshots, showing the linux-git and linux-2.6 repositories:

linux-git

linux-2.6

Detecting EOF in C

EOF is just a macro with a value (usually -1). You have to test something against EOF, such as the result of a getchar() call.

One way to test for the end of a stream is with the feof function.

if (feof(stdin))

Note, that the 'end of stream' state will only be set after a failed read.

In your example you should probably check the return value of scanf and if this indicates that no fields were read, then check for end-of-file.

Reducing the gap between a bullet and text in a list item

To achieve the look I wanted, I made a div containing a basic UL and several LIs. I couldn't easily adjust the indent between the bullet and text with any of the suggested ideas above (technically possible, but not simple.) I just left the UL and LI without any listing feature (list-style-type: none) then adding a &bull; to the beginning of each line. It did give me a bit of trouble at first, it only displayed the first bullet, so I added a bullet character to the end of the first line, refreshed, then removed it and they all popped up. Just manually add a bullet HTML entity if you don't want a huge indent, add space HTML entities if you want more space :o I know it isn't the best method, but it worked for me.

Number of visitors on a specific page

Go to Behavior > Site Content > All Pages and put your URI into the search box.enter image description here

What is http multipart request?

A HTTP multipart request is a HTTP request that HTTP clients construct to send files and data over to a HTTP Server. It is commonly used by browsers and HTTP clients to upload files to the server.

can't access mysql from command line mac

I've tried all the solutions from the answers but couldn't get mysql command to work from the terminal, always getting the message

bash: command not found

The solution is to change the .bash_profile, and add the mysql path to .bash_profile

To do so follow these steps: 1. Open a new Terminal window or make sure you are in the home directory 2. Open .bash_profile using

nano .bash_profile

3. Add the following command to add the mysql path

PATH="/usr/local/mysql/bin:${PATH}"
export PATH

4. Press Ctrl+X, then press y and press enter.

The following is how my .bash_profile looks like enter image description here

Force div element to stay in same place, when page is scrolled

There is something wrong with your code.

position : absolute makes the element on top irrespective of other elements in the same page. But the position not relative to the scroll

This can be solved with position : fixed This property will make the element position fixed and still relative to the scroll.

Or

You can check it out Here

Elevating process privilege programmatically?

You should use Impersonation to elevate the state.

WindowsIdentity identity = new WindowsIdentity(accessToken);
WindowsImpersonationContext context = identity.Impersonate();

Don't forget to undo the impersonated context when you are done.

Handling JSON Post Request in Go

I like to define custom structs locally. So:

// my handler func
func addImage(w http.ResponseWriter, r *http.Request) {

    // define custom type
    type Input struct {
        Url        string  `json:"url"`
        Name       string  `json:"name"`
        Priority   int8    `json:"priority"`
    }

    // define a var 
    var input Input

    // decode input or return error
    err := json.NewDecoder(r.Body).Decode(&input)
    if err != nil {
        w.WriteHeader(400)
        fmt.Fprintf(w, "Decode error! please check your JSON formating.")
        return
    }

    // print user inputs
    fmt.Fprintf(w, "Inputed name: %s", input.Name)

}

MySQL match() against() - order by relevance and column?

Just adding for who might need.. Don't forget to alter the table!

ALTER TABLE table_name ADD FULLTEXT(column_name);

Download file of any type in Asp.Net MVC using FileResult?

its simple just give your physical path in directoryPath with file name

public FilePathResult GetFileFromDisk(string fileName)
{
    return File(directoryPath, "multipart/form-data", fileName);
}

Code not running in IE 11, works fine in Chrome

If this is happening in Angular 2+ application, you can just uncomment string polyfills in polyfills.ts:

import 'core-js/es6/string';

How to implement a queue using two stacks?

A - How To Reverse A Stack

To understand how to construct a queue using two stacks, you should understand how to reverse a stack crystal clear. Remember how stack works, it is very similar to the dish stack on your kitchen. The last washed dish will be on the top of the clean stack, which is called as Last In First Out (LIFO) in computer science.

Lets imagine our stack like a bottle as below;

enter image description here

If we push integers 1,2,3 respectively, then 3 will be on the top of the stack. Because 1 will be pushed first, then 2 will be put on the top of 1. Lastly, 3 will be put on the top of the stack and latest state of our stack represented as a bottle will be as below;

enter image description here

Now we have our stack represented as a bottle is populated with values 3,2,1. And we want to reverse the stack so that the top element of the stack will be 1 and bottom element of the stack will be 3. What we can do ? We can take the bottle and hold it upside down so that all the values should reverse in order ?

enter image description here

Yes we can do that, but that's a bottle. To do the same process, we need to have a second stack that which is going to store the first stack elements in reverse order. Let's put our populated stack to the left and our new empty stack to the right. To reverse the order of the elements, we are going to pop each element from left stack, and push them to the right stack. You can see what happens as we do so on the image below;

enter image description here

So we know how to reverse a stack.

B - Using Two Stacks As A Queue

On previous part, I've explained how can we reverse the order of stack elements. This was important, because if we push and pop elements to the stack, the output will be exactly in reverse order of a queue. Thinking on an example, let's push the array of integers {1, 2, 3, 4, 5} to a stack. If we pop the elements and print them until the stack is empty, we will get the array in the reverse order of pushing order, which will be {5, 4, 3, 2, 1} Remember that for the same input, if we dequeue the queue until the queue is empty, the output will be {1, 2, 3, 4, 5}. So it is obvious that for the same input order of elements, output of the queue is exactly reverse of the output of a stack. As we know how to reverse a stack using an extra stack, we can construct a queue using two stacks.

Our queue model will consist of two stacks. One stack will be used for enqueue operation (stack #1 on the left, will be called as Input Stack), another stack will be used for the dequeue operation (stack #2 on the right, will be called as Output Stack). Check out the image below;

enter image description here

Our pseudo-code is as below;


Enqueue Operation

Push every input element to the Input Stack

Dequeue Operation

If ( Output Stack is Empty)
    pop every element in the Input Stack
    and push them to the Output Stack until Input Stack is Empty

pop from Output Stack

Let's enqueue the integers {1, 2, 3} respectively. Integers will be pushed on the Input Stack (Stack #1) which is located on the left;

enter image description here

Then what will happen if we execute a dequeue operation? Whenever a dequeue operation is executed, queue is going to check if the Output Stack is empty or not(see the pseudo-code above) If the Output Stack is empty, then the Input Stack is going to be extracted on the output so the elements of Input Stack will be reversed. Before returning a value, the state of the queue will be as below;

enter image description here

Check out the order of elements in the Output Stack (Stack #2). It's obvious that we can pop the elements from the Output Stack so that the output will be same as if we dequeued from a queue. Thus, if we execute two dequeue operations, first we will get {1, 2} respectively. Then element 3 will be the only element of the Output Stack, and the Input Stack will be empty. If we enqueue the elements 4 and 5, then the state of the queue will be as follows;

enter image description here

Now the Output Stack is not empty, and if we execute a dequeue operation, only 3 will be popped out from the Output Stack. Then the state will be seen as below;

enter image description here

Again, if we execute two more dequeue operations, on the first dequeue operation, queue will check if the Output Stack is empty, which is true. Then pop out the elements of the Input Stack and push them to the Output Stack unti the Input Stack is empty, then the state of the Queue will be as below;

enter image description here

Easy to see, the output of the two dequeue operations will be {4, 5}

C - Implementation Of Queue Constructed with Two Stacks

Here is an implementation in Java. I'm not going to use the existing implementation of Stack so the example here is going to reinvent the wheel;

C - 1) MyStack class : A Simple Stack Implementation

public class MyStack<T> {

    // inner generic Node class
    private class Node<T> {
        T data;
        Node<T> next;

        public Node(T data) {
            this.data = data;
        }
    }

    private Node<T> head;
    private int size;

    public void push(T e) {
        Node<T> newElem = new Node(e);

        if(head == null) {
            head = newElem;
        } else {
            newElem.next = head;
            head = newElem;     // new elem on the top of the stack
        }

        size++;
    }

    public T pop() {
        if(head == null)
            return null;

        T elem = head.data;
        head = head.next;   // top of the stack is head.next

        size--;

        return elem;
    }

    public int size() {
        return size;
    }

    public boolean isEmpty() {
        return size == 0;
    }

    public void printStack() {
        System.out.print("Stack: ");

        if(size == 0)
            System.out.print("Empty !");
        else
            for(Node<T> temp = head; temp != null; temp = temp.next)
                System.out.printf("%s ", temp.data);

        System.out.printf("\n");
    }
}

C - 2) MyQueue class : Queue Implementation Using Two Stacks

public class MyQueue<T> {

    private MyStack<T> inputStack;      // for enqueue
    private MyStack<T> outputStack;     // for dequeue
    private int size;

    public MyQueue() {
        inputStack = new MyStack<>();
        outputStack = new MyStack<>();
    }

    public void enqueue(T e) {
        inputStack.push(e);
        size++;
    }

    public T dequeue() {
        // fill out all the Input if output stack is empty
        if(outputStack.isEmpty())
            while(!inputStack.isEmpty())
                outputStack.push(inputStack.pop());

        T temp = null;
        if(!outputStack.isEmpty()) {
            temp = outputStack.pop();
            size--;
        }

        return temp;
    }

    public int size() {
        return size;
    }

    public boolean isEmpty() {
        return size == 0;
    }

}

C - 3) Demo Code

public class TestMyQueue {

    public static void main(String[] args) {
        MyQueue<Integer> queue = new MyQueue<>();

        // enqueue integers 1..3
        for(int i = 1; i <= 3; i++)
            queue.enqueue(i);

        // execute 2 dequeue operations 
        for(int i = 0; i < 2; i++)
            System.out.println("Dequeued: " + queue.dequeue());

        // enqueue integers 4..5
        for(int i = 4; i <= 5; i++)
            queue.enqueue(i);

        // dequeue the rest
        while(!queue.isEmpty())
            System.out.println("Dequeued: " + queue.dequeue());
    }

}

C - 4) Sample Output

Dequeued: 1
Dequeued: 2
Dequeued: 3
Dequeued: 4
Dequeued: 5

Synchronization vs Lock

You can achieve everything the utilities in java.util.concurrent do with the low-level primitives like synchronized, volatile, or wait / notify

However, concurrency is tricky, and most people get at least some parts of it wrong, making their code either incorrect or inefficient (or both).

The concurrent API provides a higher-level approach, which is easier (and as such safer) to use. In a nutshell, you should not need to use synchronized, volatile, wait, notify directly anymore.

The Lock class itself is on the lower-level side of this toolbox, you may not even need to use that directly either (you can use Queues and Semaphore and stuff, etc, most of the time).

Hibernate: "Field 'id' doesn't have a default value"

you must be using update in your hbm2ddl property. make the changes and update it to Create so that it can create the table.

<property name="hbm2ddl.auto">create</property>

It worked for me.

Step-by-step debugging with IPython

You can use IPython's %pdb magic. Just call %pdb in IPython and when an error occurs, you're automatically dropped to ipdb. While you don't have the stepping immediately, you're in ipdb afterwards.

This makes debugging individual functions easy, as you can just load a file with %load and then run a function. You could force an error with an assert at the right position.

%pdb is a line magic. Call it as %pdb on, %pdb 1, %pdb off or %pdb 0. If called without argument it works as a toggle.

How to print the values of slices

For a []string, you can use strings.Join():

s := []string{"foo", "bar", "baz"}
fmt.Println(strings.Join(s, ", "))
// output: foo, bar, baz

php codeigniter count rows

replace the query inside your model function with this

$query = $this->db->query("SELECT id FROM home");

in view:

echo $query->num_rows();

How to disable a link using only CSS?

If you want to stick to just HTML/CSS on a form, another option is to use a button. Style it and set the disabled attribute.

E.g. http://jsfiddle.net/cFTxH/1/

How to change Apache Tomcat web server port number

1) Locate server.xml in {Tomcat installation folder}\ conf \ 2) Find following similar statement

       <!-- Define a non-SSL HTTP/1.1 Connector on port 8180 -->
      <Connector port="8080" maxHttpHeaderSize="8192"
           maxThreads="150" minSpareThreads="25" maxSpareThreads="75"
           enableLookups="false" redirectPort="8443" acceptCount="100"
           connectionTimeout="20000" disableUploadTimeout="true" />

For example

<Connector port="8181" protocol="HTTP/1.1" 
           connectionTimeout="20000" 
           redirectPort="8443" />

Edit and save the server.xml file. Restart Tomcat. Done

Further reference: http://www.mkyong.com/tomcat/how-to-change-tomcat-default-port/

How to retrieve the hash for the current commit in Git?

There's always git describe as well. By default it gives you --

john@eleanor:/dev/shm/mpd/ncmpc/pkg (master)$ git describe --always
release-0.19-11-g7a68a75

How to escape apostrophe (') in MySql?

Replace the string

value = value.replace(/'/g, "\\'");

where value is your string which is going to store in your Database.

Further,

NPM package for this, you can have look into it

https://www.npmjs.com/package/mysql-apostrophe

In MySQL, can I copy one row to insert into the same table?

This is an additional solution to the answer by "Grim..." There have been some comments on it having a primary key as null. Some comments about it not working. And some comments on solutions. None of the solutions worked for us. We have MariaDB with the InnoDB table.

We could not set the primary key to allow null. Using 0 instead of NULL led to duplicate value error for the primary key. SET SQL_SAFE_UPDATES = 0; Did not work either.

The solution from "Grim..." did work IF we changed our PRIMARY KEY to UNIQUE instead

Create hive table using "as select" or "like" and also specify delimiter

Create Table as select (CTAS) is possible in Hive.

You can try out below command:

CREATE TABLE new_test 
    row format delimited 
    fields terminated by '|' 
    STORED AS RCFile 
AS select * from source where col=1
  1. Target cannot be partitioned table.
  2. Target cannot be external table.
  3. It copies the structure as well as the data

Create table like is also possible in Hive.

  1. It just copies the source table definition.

Regular expression - starting and ending with a letter, accepting only letters, numbers and _

seeing how the rules are fairly complicated, I'd suggest the following:

/^[a-z](\w*)[a-z0-9]$/i

match the whole string and capture intermediate characters. Then either with the string functions or the following regex:

/__/

check if the captured part has two underscores in a row. For example in Python it would look like this:

>>> import re
>>> def valid(s):
    match = re.match(r'^[a-z](\w*)[a-z0-9]$', s, re.I)
    if match is not None:
        return match.group(1).count('__') == 0
    return False

Check with jquery if div has overflowing elements

I fixed this by adding another div in the one that overflows. Then you compare the heights of the 2 divs.

<div class="AAAA overflow-hidden" style="height: 20px;" >
    <div class="BBBB" >
        Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
    </div>
</div>

and the js

    if ($('.AAAA').height() < $('.BBBB').height()) {
        console.log('we have overflow')
    } else {
        console.log('NO overflow')
    }

This looks easier...

How to execute a .sql script from bash

You simply need to start mysql and feed it with the content of db.sql:

mysql -u user -p < db.sql

no operator "<<" matches these operands

You're not including the standard <string> header.

You got [un]lucky that some of its pertinent definitions were accidentally made available by the other standard headers that you did include ... but operator<< was not.

How do we determine the number of days for a given month in python

Alternative solution:

>>> from datetime import date
>>> (date(2012, 3, 1) - date(2012, 2, 1)).days
29

Oracle ORA-12154: TNS: Could not resolve service name Error?

Going on the assumption you're using TNSNAMES naming, here's a couple of things to do:

  • Create/modify the tnsnames.ora file in the network/admin subdirectory associated with OraHome90 to include an entry for your oracle database:
> SERVICENAME_alias =
>    (DESCRIPTION =
>     (ADDRESS = (PROTOCOL = TCP)(HOST = HOST.XYZi.com)(PORT = 1521))
>     (CONNECT_DATA = (SERVICE_NAME = SERVICENAME))

This is assuming you're using the standard Oracle port of 1521. Note that servicename_alias can be any name you want to use on the local system. You may also find that you need to specify (SID = SERVICENAME) instead of (SERVICENAME=SERVICENAME).

  • Execute tnsping servicename_alias to verify connectivity. Get this working before going any further. This will tell you if you're past the 12154 error.
  • Assuming a good connection, create an ODBC DSN using the control panel, specifying the ODBC driver for Oracle of your choice (generally there's a Microsoft ODBC driver at least, and it should work adequately as a proof of concept). I'll assume the name you gave of DATASOURCE. Use the servicename_alias as the Server name in the ODBC configuration.
  • At this point you should be able to connect to your database via Access. I am not a VB programmer, but I know you should be able to go to File->Get External Data->Link Tables and connect to your ODBC source. I would assume your code would work as well.

Export DataTable to Excel File

The most rank answer in this post work, however its is CSV file. It is not actual Excel file. Therefore, you will get a warning when you are opening a file.

The best solution I found on the web is using CloseXML https://github.com/closedxml/closedxml You need to Open XML as well.

 dt = city.GetAllCity();//your datatable
 using (XLWorkbook wb = new XLWorkbook())
    {
        wb.Worksheets.Add(dt);

        Response.Clear();
        Response.Buffer = true;
        Response.Charset = "";
        Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
        Response.AddHeader("content-disposition", "attachment;filename=GridView.xlsx");
        using (MemoryStream MyMemoryStream = new MemoryStream())
        {
            wb.SaveAs(MyMemoryStream);
            MyMemoryStream.WriteTo(Response.OutputStream);
            Response.Flush();
            Response.End();
        }
    }

Credit: http://www.aspsnippets.com/Articles/Solution-ASPNet-GridView-Export-to-Excel-The-file-you-are-trying-to-open-is-in-a-different-format-than-specified-by-the-file-extension.aspx

What does it mean when the size of a VARCHAR2 in Oracle is declared as 1 byte?

it means ONLY one byte will be allocated per character - so if you're using multi-byte charsets, your 1 character won't fit

if you know you have to have at least room enough for 1 character, don't use the BYTE syntax unless you know exactly how much room you'll need to store that byte

when in doubt, use VARCHAR2(1 CHAR)

same thing answered here Difference between BYTE and CHAR in column datatypes

Also, in 12c the max for varchar2 is now 32k, not 4000. If you need more than that, use CLOB

in Oracle, don't use VARCHAR

Is there a way to get a textarea to stretch to fit its content without using PHP or JavaScript?

Here is a function that works with jQuery (for height only, not width):

function setHeight(jq_in){
    jq_in.each(function(index, elem){
        // This line will work with pure Javascript (taken from NicB's answer):
        elem.style.height = elem.scrollHeight+'px'; 
    });
}
setHeight($('<put selector here>'));

Note: The op asked for a solution that does not use Javascript, however this should be helpful to many people who come across this question.

Convert NaN to 0 in javascript

using user 113716 solution, which by the way is great to avoid all those if-else I have implemented it this way to calculate my subtotal textbox from textbox unit and textbox quantity.

In the process writing of non numbers in unit and quantity textboxes, their values are bing replace by zero so final posting of user data has no non-numbers .

     <script src="/common/tools/jquery-1.10.2.js"></script>
     <script src="/common/tools/jquery-ui.js"></script>

     <!----------------- link above 2 lines to your jquery files ------>





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

    $('#quantity').val((+$('#quantity').val() || 0));
    $('#unit').val((+$('#unit').val() || 0));

    var  calculated = $('#quantity').val() * $('#unit').val() ;
    $('#subtotal').val(calculated);


    }
    </script>


      <input type = "text" onChange ="calculate_subtotal();" id = "quantity"/>
      <input type = "text" onChange ="calculate_subtotal();" id = "unit"/>
      <input type = "text" id = "subtotal"/>

Understanding __getitem__ method

The [] syntax for getting item by key or index is just syntax sugar.

When you evaluate a[i] Python calls a.__getitem__(i) (or type(a).__getitem__(a, i), but this distinction is about inheritance models and is not important here). Even if the class of a may not explicitly define this method, it is usually inherited from an ancestor class.

All the (Python 2.7) special method names and their semantics are listed here: https://docs.python.org/2.7/reference/datamodel.html#special-method-names

Scala Doubles, and Precision

How about :

 val value = 1.4142135623730951

//3 decimal places
println((value * 1000).round / 1000.toDouble)

//4 decimal places
println((value * 10000).round / 10000.toDouble)

Using multiple case statements in select query

There are two ways to write case statements, you seem to be using a combination of the two

case a.updatedDate
    when 1760 then 'Entered on' + a.updatedDate
    when 1710 then 'Viewed on' + a.updatedDate
    else 'Last Updated on' + a.updateDate
end

or

case 
    when a.updatedDate = 1760 then 'Entered on' + a.updatedDate
    when a.updatedDate = 1710 then 'Viewed on' + a.updatedDate
    else 'Last Updated on' + a.updateDate
end

are equivalent. They may not work because you may need to convert date types to varchars to append them to other varchars.

Unable to set data attribute using jQuery Data() API

To quote a quote:

The data- attributes are pulled in the first time the data property is accessed and then are no longer accessed or mutated (all data values are then stored internally in jQuery).

.data() - jQuery Documentiation

Note that this (Frankly odd) limitation is only withheld to the use of .data().

The solution? Use .attr instead.

Of course, several of you may feel uncomfortable with not using it's dedicated method. Consider the following scenario:

  • The 'standard' is updated so that the data- portion of custom attributes is no longer required/is replaced

Common sense - Why would they change an already established attribute like that? Just imagine class begin renamed to group and id to identifier. The Internet would break.

And even then, Javascript itself has the ability to fix this - And of course, despite it's infamous incompatibility with HTML, REGEX (And a variety of similar methods) could rapidly rename your attributes to this new-mythical 'standard'.

TL;DR

alert($(targetField).attr("data-helptext"));

Use of String.Format in JavaScript?

//Add "format" method to the string class
//supports:  "Welcome {0}. You are the first person named {0}".format("David");
//       and "First Name:{} Last name:{}".format("David","Wazy");
//       and "Value:{} size:{0} shape:{1} weight:{}".format(value, size, shape, weight)
String.prototype.format = function () {
    var content = this;
    for (var i = 0; i < arguments.length; i++) {
        var target = '{' + i + '}';
        content=content.split(target).join(String(arguments[i]))
        content = content.replace("{}", String(arguments[i]));
    }
    return content;
}
alert("I {} this is what {2} want and {} works for {2}!".format("hope","it","you"))

You can mix and match using positional and "named" replacement locations using this function.

Making a POST call instead of GET using urllib2

it should be sending a POST if you provide a data parameter (like you are doing):

from the docs: "the HTTP request will be a POST instead of a GET when the data parameter is provided"

so.. add some debug output to see what's up from the client side.

you can modify your code to this and try again:

import urllib
import urllib2

url = 'http://myserver/post_service'
opener = urllib2.build_opener(urllib2.HTTPHandler(debuglevel=1))
data = urllib.urlencode({'name' : 'joe',
                         'age'  : '10'})
content = opener.open(url, data=data).read()

Why do we have to override the equals() method in Java?

To answer your question, firstly I would strongly recommend looking at the Documentation.

Without overriding the equals() method, it will act like "==". When you use the "==" operator on objects, it simply checks to see if those pointers refer to the same object. Not if their members contain the same value.

We override to keep our code clean, and abstract the comparison logic from the If statement, into the object. This is considered good practice and takes advantage of Java's heavily Object Oriented Approach.

Python JSON serialize a Decimal object

How about subclassing json.JSONEncoder?

class DecimalEncoder(json.JSONEncoder):
    def default(self, o):
        if isinstance(o, decimal.Decimal):
            # wanted a simple yield str(o) in the next line,
            # but that would mean a yield on the line with super(...),
            # which wouldn't work (see my comment below), so...
            return (str(o) for o in [o])
        return super(DecimalEncoder, self).default(o)

Then use it like so:

json.dumps({'x': decimal.Decimal('5.5')}, cls=DecimalEncoder)

What's the difference between 'int?' and 'int' in C#?

you can use it when you expect a null value in your integer especially when you use CASTING ex:

x= (int)y;

if y = null then you will have an error. you have to use:

x = (int?)y;

Passing command line arguments from Maven as properties in pom.xml

Inside pom.xml

<project>

.....

<profiles>
    <profile>
        <id>linux64</id>
        <activation>
            <activeByDefault>true</activeByDefault>
        </activation>
        <properties>
            <build_os>linux</build_os>
            <build_ws>gtk</build_ws>
            <build_arch>x86_64</build_arch>
        </properties>
    </profile>

    <profile>
        <id>win64</id>
        <activation>
            <property>
                <name>env</name>
                <value>win64</value>
            </property>
        </activation>
        <properties>
            <build_os>win32</build_os>
            <build_ws>win32</build_ws>
            <build_arch>x86_64</build_arch>
        </properties>
    </profile>
</profiles>

.....

<plugin>
    <groupId>org.eclipse.tycho</groupId>
    <artifactId>target-platform-configuration</artifactId>
    <version>${tycho.version}</version>
    <configuration>
        <environments>
            <environment>
                <os>${build_os}</os>
                <ws>${build_ws}</ws>
                <arch>${build_arch}</arch>
            </environment>
        </environments>
    </configuration>
</plugin>

.....

In this example when you run the pom without any argument mvn clean install default profile will execute.

When executed with mvn -Denv=win64 clean install

win64 profile will executed.

Please refer http://maven.apache.org/guides/introduction/introduction-to-profiles.html

Set field value with reflection

It's worth reading Oracle Java Tutorial - Getting and Setting Field Values

Field#set(Object object, Object value) sets the field represented by this Field object on the specified object argument to the specified new value.

It should be like this

f.set(objectOfTheClass, new ConcurrentHashMap<>());

You can't set any value in null Object If tried then it will result in NullPointerException


Note: Setting a field's value via reflection has a certain amount of performance overhead because various operations must occur such as validating access permissions. From the runtime's point of view, the effects are the same, and the operation is as atomic as if the value was changed in the class code directly.

Select second last element with css

In CSS3 you have:

:nth-last-child(2)

See: https://developer.mozilla.org/en-US/docs/Web/CSS/:nth-last-child

nth-last-child Browser Support:

  • Chrome 2
  • Firefox 3.5
  • Opera 9.5, 10
  • Safari 3.1, 4
  • Internet Explorer 9

How to get local server host and port in Spring Boot?

You can get hostname from spring cloud property in spring-cloud-commons-2.1.0.RC2.jar

environment.getProperty("spring.cloud.client.ip-address");
environment.getProperty("spring.cloud.client.hostname");

spring.factories of spring-cloud-commons-2.1.0.RC2.jar

org.springframework.boot.env.EnvironmentPostProcessor=\
org.springframework.cloud.client.HostInfoEnvironmentPostProcessor

What does %s mean in a python format string?

%s indicates a conversion type of string when using python's string formatting capabilities. More specifically, %s converts a specified value to a string using the str() function. Compare this with the %r conversion type that uses the repr() function for value conversion.

Take a look at the docs for string formatting.

Bash mkdir and subfolders

To create multiple sub-folders

mkdir -p parentfolder/{subfolder1,subfolder2,subfolder3}

Best timestamp format for CSV/Excel?

I would guess that ISO-format is a good idea. (Wikipedia article, also with time info)

How to write log base(2) in c/c++

Simple math:

    log2 (x) = logy (x) / logy (2)

where y can be anything, which for standard log functions is either 10 or e.

Create folder in Android

Add this permission in Manifest,
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

File folder = new File(Environment.getExternalStorageDirectory() + 
                             File.separator + "TollCulator");
boolean success = true;
if (!folder.exists()) {
    success = folder.mkdirs();
}
if (success) {
    // Do something on success
} else {
    // Do something else on failure 
}

when u run the application go too DDMS->File Explorer->mnt folder->sdcard folder->toll-creation folder

What is private bytes, virtual bytes, working set?

The definition of the perfmon counters has been broken since the beginning and for some reason appears to be too hard to correct.

A good overview of Windows memory management is available in the video "Mysteries of Memory Management Revealed" on MSDN: It covers more topics than needed to track memory leaks (eg working set management) but gives enough detail in the relevant topics.


To give you a hint of the problem with the perfmon counter descriptions, here is the inside story about private bytes from "Private Bytes Performance Counter -- Beware!" on MSDN:

Q: When is a Private Byte not a Private Byte?

A: When it isn't resident.

The Private Bytes counter reports the commit charge of the process. That is to say, the amount of space that has been allocated in the swap file to hold the contents of the private memory in the event that it is swapped out. Note: I'm avoiding the word "reserved" because of possible confusion with virtual memory in the reserved state which is not committed.


From "Performance Planning" on MSDN:

3.3 Private Bytes

3.3.1 Description

Private memory, is defined as memory allocated for a process which cannot be shared by other processes. This memory is more expensive than shared memory when multiple such processes execute on a machine. Private memory in (traditional) unmanaged dlls usually constitutes of C++ statics and is of the order of 5% of the total working set of the dll.

StringStream in C#

You have a number of options:

One is to not use streams, but use the TextWriter

   void Print(TextWriter writer) 
   {
   }

   void Main() 
  {
    var textWriter = new StringWriter();
    Print(writer);
    string myString = textWriter.ToString();
   }

It's likely that TextWriter is the appropriate level of abstraction for your print function. Streams are aimed at writing binary data, while TextWriter works at a higher abstraction level, specifically geared towards outputting strings.

If your motivation is that you also want your Print function to write to files, you can get a text writer from a filestream as well.

void Print(TextWriter writer) 
{
}

void PrintToFile(string filePath) 
{
     using(var textWriter = new StreamWriter(filePath))
     {
         Print(writer);
     }
}

If you REALLY want a stream you can look at MemoryStream.