Programs & Examples On #Mod perl

mod-perl is an Apache web server module. The module improves the performance of Perl CGI scripts. Scripts are loaded into memory on the first invocation and added to the Apache process. On each subsequent invocation the script is run directly with no need for loading and parsing.

Specifying number of decimal places in Python

There's a few ways to do this depending on how you want to hold the value.

You can use basic string formatting, e.g

'Your Meal Price is %.2f' %  mealPrice

You can modify the 2 to whatever precision you need.

However, since you're dealing with money you should look into the decimal module which has a cool method named quantize which is exactly for working with monetary applications. You can use it like so:

from decimal import Decimal, ROUND_DOWN
mealPrice = Decimal(str(mealPrice)).quantize(Decimal('.01'), rounding=ROUND_DOWN)

Note that the rounding attribute is purely optional as well.

Iterate over object attributes in python

For all the pythonian zealots out there I'm sure Johan Cleeze would approve of your dogmatism ;). I'm leaving this answer keep demeriting it It actually makes me more confidant. Leave a comment you chickens!

For python 3.6

class SomeClass:

    def attr_list1(self, should_print=False):

        for k in self.__dict__.keys():
            v = self.__dict__.__getitem__(k)
            if should_print:
                print(f"attr: {k}    value: {v}")

    def attr_list(self, should_print=False):

        b = [(k, v) for k, v in self.__dict__.items()]
        if should_print:
            [print(f"attr: {a[0]}    value: {a[1]}") for a in b]
        return b

403 Forbidden You don't have permission to access /folder-name/ on this server

Solved issue using below steps :

1) edit file "/etc/apache2/sites-enabled/000-default.conf"

    DocumentRoot "dir_name"

    ServerName <server_IP>

    <Directory "dir_name">
       Options Indexes FollowSymLinks
       AllowOverride None
       Require all granted
    </Directory>

    <Directory "dir_name">
       AllowOverride None
       # Allow open access:
       Require all granted

2) change folder permission sudo chmod -R 777 "dir_name"

Removing MySQL 5.7 Completely

First of all, do a backup of your needed databases with mysqldump

Note: If you want to restore later, just backup your relevant databases, and not the WHOLE, because the whole database might actually be the reason you need to purge and reinstall).

In total, do this:

sudo service mysql stop  #or mysqld
sudo killall -9 mysql
sudo killall -9 mysqld
sudo apt-get remove --purge mysql-server mysql-client mysql-common
sudo apt-get autoremove
sudo apt-get autoclean
sudo deluser -f mysql
sudo rm -rf /var/lib/mysql
sudo apt-get purge mysql-server-core-5.7
sudo apt-get purge mysql-client-core-5.7
sudo rm -rf /var/log/mysql
sudo rm -rf /etc/mysql

All above commands in single line (just copy and paste):

sudo service mysql stop && sudo killall -9 mysql && sudo killall -9 mysqld && sudo apt-get remove --purge mysql-server mysql-client mysql-common && sudo apt-get autoremove && sudo apt-get autoclean && sudo deluser mysql && sudo rm -rf /var/lib/mysql && sudo apt-get purge mysql-server-core-5.7 && sudo apt-get purge mysql-client-core-5.7 && sudo rm -rf /var/log/mysql && sudo rm -rf /etc/mysql

How to enable Logger.debug() in Log4j

Here's a quick one-line hack that I occasionally use to temporarily turn on log4j debug logging in a JUnit test:

Logger.getRootLogger().setLevel(Level.DEBUG);

or if you want to avoid adding imports:

org.apache.log4j.Logger.getRootLogger().setLevel(
      org.apache.log4j.Level.DEBUG);

Note: this hack doesn't work in log4j2 because setLevel has been removed from the API, and there doesn't appear to be equivalent functionality.

Failed to connect to mailserver at "localhost" port 25

On windows, nearly all AMPP (Apache,MySQL,PHP,PHPmyAdmin) packages don't include a mail server (but nearly all naked linuxes do have!). So, when using PHP under windows, you need to setup a mail server!

Imo the best and most simple tool ist this: http://smtp4dev.codeplex.com/

SMTP4Dev is a simple one-file mail server tool that does collect the mails it send (so it does not really sends mail, it just keeps them for development). Perfect tool.

Using Jquery AJAX function with datatype HTML

Here is a version that uses dataType html, but this is far less explicit, because i am returning an empty string to indicate an error.

Ajax call:

$.ajax({
  type : 'POST',
  url : 'post.php',
  dataType : 'html',
  data: {
      email : $('#email').val()
  },
  success : function(data){
      $('#waiting').hide(500);
      $('#message').removeClass().addClass((data == '') ? 'error' : 'success')
     .html(data).show(500);
      if (data == '') {
          $('#message').html("Format your email correcly");
          $('#demoForm').show(500);
      }
  },
  error : function(XMLHttpRequest, textStatus, errorThrown) {
      $('#waiting').hide(500);
      $('#message').removeClass().addClass('error')
      .text('There was an error.').show(500);
      $('#demoForm').show(500);
  }

});

post.php

<?php
sleep(1);

function processEmail($email) {
    if (preg_match("#^[a-zA-Z0-9_.-]+@[a-zA-Z0-9-]+.[a-zA-Z0-9-.]+$#", $email)) {
        // your logic here (ex: add into database)
        return true;
    }
    return false;
}

if (processEmail($_POST['email'])) {
    echo "<span>Your email is <strong>{$_POST['email']}</strong></span>";
}

How do you make Vim unhighlight what you searched for?

Append the following line to the end of your .vimrc to prevent highlighting altogether:

set nohlsearch

How to parse dates in multiple formats using SimpleDateFormat

Using DateTimeFormatter it can be achieved as below:


import java.text.SimpleDateFormat;
import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.time.temporal.TemporalAccessor;
import java.util.Date;
import java.util.TimeZone;

public class DateTimeFormatTest {

    public static void main(String[] args) {

        String pattern = "[yyyy-MM-dd[['T'][ ]HH:mm:ss[.SSSSSSSz][.SSS[XXX][X]]]]";
        String timeSample = "2018-05-04T13:49:01.7047141Z";
        SimpleDateFormat simpleDateFormatter = new SimpleDateFormat("dd/MM/yy HH:mm:ss");
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern(pattern);
        TemporalAccessor accessor = formatter.parse(timeSample);
        ZonedDateTime zTime = LocalDateTime.from(accessor).atZone(ZoneOffset.UTC);

        Date date=new Date(zTime.toEpochSecond()*1000);
        simpleDateFormatter.setTimeZone(TimeZone.getTimeZone(ZoneOffset.UTC));
        System.out.println(simpleDateFormatter.format(date));       
    }
}

Pay attention at String pattern, this is the combination of multiple patterns. In open [ and close ] square brackets you can mention any kind of patterns.

CSS horizontal centering of a fixed div?

If using inline-blocks is an option I would recommend this approach:

.container { 
    /* fixed position a zero-height full width container */
    position: fixed;
    top: 0; /* or whatever position is desired */
    left: 0;
    right: 0;
    height: 0;
    /* center all inline content */
    text-align: center;
}

.container > div {
    /* make the block inline */
    display: inline-block;
    /* reset container's center alignment */
    text-align: left;
} 

I wrote a short post on this here: http://salomvary.github.com/position-fixed-horizontally-centered.html

Get immediate first child element

Both these will give you the first child node:

console.log(parentElement.firstChild); // or
console.log(parentElement.childNodes[0]);

If you need the first child that is an element node then use:

console.log(parentElement.children[0]);

Edit

Ah, I see your problem now; parentElement is an array.

If you know that getElementsByClassName will only return one result, which it seems you do, you should use [0] to dearray (yes, I made that word up) the element:

var parentElement = document.getElementsByClassName("uniqueClassName")[0];

AlertDialog.Builder with custom layout and EditText; cannot access view

View v=inflater.inflate(R.layout.alert_label_editor, null);
alertDialog.setContentView(v);
EditText editText = (EditText)v.findViewById(R.id.label_field);
editText.setText("test label");
alertDialog.show();

Splitting on first occurrence

For me the better approach is that:

s.split('mango', 1)[-1]

...because if happens that occurrence is not in the string you'll get "IndexError: list index out of range".

Therefore -1 will not get any harm cause number of occurrences is already set to one.

How to change a string into uppercase

to make the string upper case -- just simply type

s.upper()

simple and easy! you can do the same to make it lower too

s.lower()

etc.

What is "Linting"?

Interpreted languages like Python and JavaScript benefit greatly from linting, as these languages don’t have a compiling phase to display errors before execution.

Linters are also useful for code formatting and/or adhering to language specific best practices.

Lately I have been using ESLint for JS/React and will occasionally use it with an airbnb-config file.

What is the use of the @ symbol in PHP?

It suppresses error messages — see Error Control Operators in the PHP manual.

Rails update_attributes without save?

You can use the 'attributes' method:

@car.attributes = {:model => 'Sierra', :years => '1990', :looks => 'Sexy'}

Source: http://api.rubyonrails.org/classes/ActiveRecord/Base.html

attributes=(new_attributes, guard_protected_attributes = true) Allows you to set all the attributes at once by passing in a hash with keys matching the attribute names (which again matches the column names).

If guard_protected_attributes is true (the default), then sensitive attributes can be protected from this form of mass-assignment by using the attr_protected macro. Or you can alternatively specify which attributes can be accessed with the attr_accessible macro. Then all the attributes not included in that won’t be allowed to be mass-assigned.

class User < ActiveRecord::Base
  attr_protected :is_admin
end

user = User.new
user.attributes = { :username => 'Phusion', :is_admin => true }
user.username   # => "Phusion"
user.is_admin?  # => false

user.send(:attributes=, { :username => 'Phusion', :is_admin => true }, false)
user.is_admin?  # => true

Postgresql - select something where date = "01/01/11"

I think you want to cast your dt to a date and fix the format of your date literal:

SELECT *
FROM table
WHERE dt::date = '2011-01-01' -- This should be ISO-8601 format, YYYY-MM-DD

Or the standard version:

SELECT *
FROM table
WHERE CAST(dt AS DATE) = '2011-01-01' -- This should be ISO-8601 format, YYYY-MM-DD

The extract function doesn't understand "date" and it returns a number.

ReferenceError: event is not defined error in Firefox

You're declaring (some of) your event handlers incorrectly:

$('.menuOption').click(function( event ){ // <---- "event" parameter here

    event.preventDefault();
    var categories = $(this).attr('rel');
    $('.pages').hide();
    $(categories).fadeIn();


});

You need "event" to be a parameter to the handlers. WebKit follows IE's old behavior of using a global symbol for "event", but Firefox doesn't. When you're using jQuery, that library normalizes the behavior and ensures that your event handlers are passed the event parameter.

edit — to clarify: you have to provide some parameter name; using event makes it clear what you intend, but you can call it e or cupcake or anything else.

Note also that the reason you probably should use the parameter passed in from jQuery instead of the "native" one (in Chrome and IE and Safari) is that that one (the parameter) is a jQuery wrapper around the native event object. The wrapper is what normalizes the event behavior across browsers. If you use the global version, you don't get that.

How to submit form on change of dropdown list?

Simple JavaScript will do -

<form action="myservlet.do" method="POST">
    <select name="myselect" id="myselect" onchange="this.form.submit()">
        <option value="1">One</option>
        <option value="2">Two</option>
        <option value="3">Three</option>
        <option value="4">Four</option>
    </select>
</form>

Here is a link for a good javascript tutorial.

Tensorflow installation error: not a supported wheel on this platform

I was trying to do the windows-based install and kept getting this error.

Turns out you have to have python 3.5.2. Not 2.7, not 3.6.x-- nothing other than 3.5.2.

After installing python 3.5.2 the pip install worked.

Flask raises TemplateNotFound error even though template file exists

If you run your code from an installed package, make sure template files are present in directory <python root>/lib/site-packages/your-package/templates.


Some details:

In my case I was trying to run examples of project flask_simple_ui and jinja would always say

jinja2.exceptions.TemplateNotFound: form.html

The trick was that sample program would import installed package flask_simple_ui. And ninja being used from inside that package is using as root directory for lookup the package path, in my case ...python/lib/site-packages/flask_simple_ui, instead of os.getcwd() as one would expect.

To my bad luck, setup.py has a bug and doesn't copy any html files, including the missing form.html. Once I fixed setup.py, the problem with TemplateNotFound vanished.

I hope it helps someone.

Display an image with Python

Solution for Jupyter notebook PIL image visualization with arbitrary number of images:

def show(*imgs, **kwargs):
    '''Show in Jupyter notebook one or sequence of PIL images in a row. figsize - optional parameter, controlling size of the image.
    Examples:
    show(img)
    show(img1,img2,img3)
    show(img1,img2,figsize=[8,8])
    '''
    
    if 'figsize' not in kwargs:
        figsize = [9,9]
    else:
        figsize = kwargs['figsize']
    
    fig, ax = plt.subplots(1,len(imgs),figsize=figsize)
    if len(imgs)==1:
        ax=[ax]
    
    for num,img in enumerate(imgs):
        ax[num].imshow(img)
        ax[num].axis('off')
        
    tight_layout()

regex to match a single character that is anything but a space

The following should suffice:

[^ ]

If you want to expand that to anything but white-space (line breaks, tabs, spaces, hard spaces):

[^\s]

or

\S  # Note this is a CAPITAL 'S'!

Programmatically get the version number of a DLL

Kris, your version works great when needing to load the assembly from the actual DLL file (and if the DLL is there!), however, one will get a much unwanted error if the DLL is EMBEDDED (i.e., not a file but an embedded DLL).

The other thing is, if one uses a versioning scheme with something like "1.2012.0508.0101", when one gets the version string you'll actually get "1.2012.518.101"; note the missing zeros.

So, here's a few extra functions to get the version of a DLL (embedded or from the DLL file):

    public static System.Reflection.Assembly GetAssembly(string pAssemblyName)
    {
        System.Reflection.Assembly tMyAssembly = null;

        if (string.IsNullOrEmpty(pAssemblyName)) { return tMyAssembly; }
        tMyAssembly = GetAssemblyEmbedded(pAssemblyName);
        if (tMyAssembly == null) { GetAssemblyDLL(pAssemblyName); }

        return tMyAssembly;
    }//System.Reflection.Assembly GetAssemblyEmbedded(string pAssemblyDisplayName)


    public static System.Reflection.Assembly GetAssemblyEmbedded(string pAssemblyDisplayName)
    {
        System.Reflection.Assembly tMyAssembly = null;

        if(string.IsNullOrEmpty(pAssemblyDisplayName)) { return tMyAssembly; }
        try //try #a
        {
            tMyAssembly = System.Reflection.Assembly.Load(pAssemblyDisplayName);
        }// try #a
        catch (Exception ex)
        {
            string m = ex.Message;
        }// try #a
        return tMyAssembly;
    }//System.Reflection.Assembly GetAssemblyEmbedded(string pAssemblyDisplayName)


    public static System.Reflection.Assembly GetAssemblyDLL(string pAssemblyNameDLL)
    {
        System.Reflection.Assembly tMyAssembly = null;

        if (string.IsNullOrEmpty(pAssemblyNameDLL)) { return tMyAssembly; }
        try //try #a
        {
            if (!pAssemblyNameDLL.ToLower().EndsWith(".dll")) { pAssemblyNameDLL += ".dll"; }
            tMyAssembly = System.Reflection.Assembly.LoadFrom(pAssemblyNameDLL);
        }// try #a
        catch (Exception ex)
        {
            string m = ex.Message;
        }// try #a
        return tMyAssembly;
    }//System.Reflection.Assembly GetAssemblyFile(string pAssemblyNameDLL)


    public static string GetVersionStringFromAssembly(string pAssemblyDisplayName)
    {
        string tVersion = "Unknown";
        System.Reflection.Assembly tMyAssembly = null;

        tMyAssembly = GetAssembly(pAssemblyDisplayName);
        if (tMyAssembly == null) { return tVersion; }
        tVersion = GetVersionString(tMyAssembly.GetName().Version.ToString());
        return tVersion;
    }//string GetVersionStringFromAssemblyEmbedded(string pAssemblyDisplayName)


    public static string GetVersionString(Version pVersion)
    {
        string tVersion = "Unknown";
        if (pVersion == null) { return tVersion; }
        tVersion = GetVersionString(pVersion.ToString());
        return tVersion;
    }//string GetVersionString(Version pVersion)


    public static string GetVersionString(string pVersionString)
    {
        string tVersion = "Unknown";
        string[] aVersion;

        if (string.IsNullOrEmpty(pVersionString)) { return tVersion; }
        aVersion = pVersionString.Split('.');
        if (aVersion.Length > 0) { tVersion = aVersion[0]; }
        if (aVersion.Length > 1) { tVersion += "." + aVersion[1]; }
        if (aVersion.Length > 2) { tVersion += "." + aVersion[2].PadLeft(4, '0'); }
        if (aVersion.Length > 3) { tVersion += "." + aVersion[3].PadLeft(4, '0'); }

        return tVersion;
    }//string GetVersionString(Version pVersion)


    public static string GetVersionStringFromAssemblyEmbedded(string pAssemblyDisplayName)
    {
        string tVersion = "Unknown";
        System.Reflection.Assembly tMyAssembly = null;

        tMyAssembly = GetAssemblyEmbedded(pAssemblyDisplayName);
        if (tMyAssembly == null) { return tVersion; }
        tVersion = GetVersionString(tMyAssembly.GetName().Version.ToString());
        return tVersion;
    }//string GetVersionStringFromAssemblyEmbedded(string pAssemblyDisplayName)


    public static string GetVersionStringFromAssemblyDLL(string pAssemblyDisplayName)
    {
        string tVersion = "Unknown";
        System.Reflection.Assembly tMyAssembly = null;

        tMyAssembly = GetAssemblyDLL(pAssemblyDisplayName);
        if (tMyAssembly == null) { return tVersion; }
        tVersion = GetVersionString(tMyAssembly.GetName().Version.ToString());
        return tVersion;
    }//string GetVersionStringFromAssemblyEmbedded(string pAssemblyDisplayName)

How to call any method asynchronously in c#

Here's a way to do it:

// The method to call
void Foo()
{
}


Action action = Foo;
action.BeginInvoke(ar => action.EndInvoke(ar), null);

Of course you need to replace Action by another type of delegate if the method has a different signature

Iterating over arrays in Python 3

While iterating over a list or array with this method:

ar = [10, 11, 12]
for i in ar:
    theSum = theSum + ar[i]

You are actually getting the values of list or array sequentially in i variable. If you print the variable i inside the for loop. You will get following output:

10
11
12

However, in your code you are confusing i variable with index value of array. Therefore, while doing ar[i] will mean ar[10] for the first iteration. Which is of course index out of range throwing IndexError

Edit You can read this for better understanding of different methods of iterating over array or list in Python

Git diff against a stash

Depending on what you want to compare the stash with (local working tree / parent commit / head commit), there are actually several commands available, amongst which the good old git diff, and the more specific git stash show:

+--------------------------------------------------------------------------+
¦ Compare stash with ? ¦ git diff                      ¦ git stash show    ¦
¦----------------------+-------------------------------+-------------------¦
¦ Local working tree   ¦ git diff stash@{0}            ¦ git stash show -l ¦
¦----------------------¦-------------------------------¦-------------------¦
¦ Parent commit        ¦ git diff stash@{0}^ stash@{0} ¦ git stash show -p ¦
¦----------------------¦-------------------------------¦-------------------¦
¦ HEAD commit          ¦ git diff stash@{0} HEAD       ¦   /               ¦
+--------------------------------------------------------------------------+

While git stash show looks more user friendly on first sight, git diff is actually more powerful in that it allows specifying filenames for a more focused diff. I've personally set up aliases for all of these commands in my zsh git plugin.

How to initialize/instantiate a custom UIView class with a XIB file in Swift

override func draw(_ rect: CGRect) 
{
    AlertView.layer.cornerRadius = 4
    AlertView.clipsToBounds = true

    btnOk.layer.cornerRadius = 4
    btnOk.clipsToBounds = true   
}

class func instanceFromNib() -> LAAlertView {
    return UINib(nibName: "LAAlertView", bundle: nil).instantiate(withOwner: nil, options: nil)[0] as! LAAlertView
}

@IBAction func okBtnDidClicked(_ sender: Any) {

    removeAlertViewFromWindow()

    UIView.animate(withDuration: 0.4, delay: 0.0, options: .allowAnimatedContent, animations: {() -> Void in
        self.AlertView.transform = CGAffineTransform(scaleX: 0.1, y: 0.1)

    }, completion: {(finished: Bool) -> Void in
        self.AlertView.transform = CGAffineTransform.identity
        self.AlertView.transform = CGAffineTransform(scaleX: 0.0, y: 0.0)
        self.AlertView.isHidden = true
        self.AlertView.alpha = 0.0

        self.alpha = 0.5
    })
}


func removeAlertViewFromWindow()
{
    for subview  in (appDel.window?.subviews)! {
        if subview.tag == 500500{
            subview.removeFromSuperview()
        }
    }
}


public func openAlertView(title:String , string : String ){

    lblTital.text  = title
    txtView.text  = string

    self.frame = CGRect(x: 0, y: 0, width: screenWidth, height: screenHeight)
    appDel.window!.addSubview(self)


    AlertView.alpha = 1.0
    AlertView.isHidden = false

    UIView.animate(withDuration: 0.2, animations: {() -> Void in
        self.alpha = 1.0
    })
    AlertView.transform = CGAffineTransform(scaleX: 0.0, y: 0.0)

    UIView.animate(withDuration: 0.3, delay: 0.2, options: .allowAnimatedContent, animations: {() -> Void in
        self.AlertView.transform = CGAffineTransform(scaleX: 1.1, y: 1.1)

    }, completion: {(finished: Bool) -> Void in
        UIView.animate(withDuration: 0.2, animations: {() -> Void in
            self.AlertView.transform = CGAffineTransform(scaleX: 1.0, y: 1.0)

        })
    })


}

What is the equivalent of ngShow and ngHide in Angular 2+?

Sorry, I have to disagree with binding to hidden which is considered to be unsafe when using Angular 2. This is because the hidden style could be overwritten easily for example using

display: flex;

The recommended approach is to use *ngIf which is safer. For more details, please refer to the official Angular blog. 5 Rookie Mistakes to Avoid with Angular 2

<div *ngIf="showGreeting">
   Hello, there!
</div>

What key shortcuts are to comment and uncomment code?

You can also add the toolbar in Visual Studio to have the buttons available.

View > Toolbars > Text Editor

enter image description here

What is the difference between the kernel space and the user space?

CPU rings are the most clear distinction

In x86 protected mode, the CPU is always in one of 4 rings. The Linux kernel only uses 0 and 3:

  • 0 for kernel
  • 3 for users

This is the most hard and fast definition of kernel vs userland.

Why Linux does not use rings 1 and 2: CPU Privilege Rings: Why rings 1 and 2 aren't used?

How is the current ring determined?

The current ring is selected by a combination of:

  • global descriptor table: a in-memory table of GDT entries, and each entry has a field Privl which encodes the ring.

    The LGDT instruction sets the address to the current descriptor table.

    See also: http://wiki.osdev.org/Global_Descriptor_Table

  • the segment registers CS, DS, etc., which point to the index of an entry in the GDT.

    For example, CS = 0 means the first entry of the GDT is currently active for the executing code.

What can each ring do?

The CPU chip is physically built so that:

  • ring 0 can do anything

  • ring 3 cannot run several instructions and write to several registers, most notably:

    • cannot change its own ring! Otherwise, it could set itself to ring 0 and rings would be useless.

      In other words, cannot modify the current segment descriptor, which determines the current ring.

    • cannot modify the page tables: How does x86 paging work?

      In other words, cannot modify the CR3 register, and paging itself prevents modification of the page tables.

      This prevents one process from seeing the memory of other processes for security / ease of programming reasons.

    • cannot register interrupt handlers. Those are configured by writing to memory locations, which is also prevented by paging.

      Handlers run in ring 0, and would break the security model.

      In other words, cannot use the LGDT and LIDT instructions.

    • cannot do IO instructions like in and out, and thus have arbitrary hardware accesses.

      Otherwise, for example, file permissions would be useless if any program could directly read from disk.

      More precisely thanks to Michael Petch: it is actually possible for the OS to allow IO instructions on ring 3, this is actually controlled by the Task state segment.

      What is not possible is for ring 3 to give itself permission to do so if it didn't have it in the first place.

      Linux always disallows it. See also: Why doesn't Linux use the hardware context switch via the TSS?

How do programs and operating systems transition between rings?

  • when the CPU is turned on, it starts running the initial program in ring 0 (well kind of, but it is a good approximation). You can think this initial program as being the kernel (but it is normally a bootloader that then calls the kernel still in ring 0).

  • when a userland process wants the kernel to do something for it like write to a file, it uses an instruction that generates an interrupt such as int 0x80 or syscall to signal the kernel. x86-64 Linux syscall hello world example:

    .data
    hello_world:
        .ascii "hello world\n"
        hello_world_len = . - hello_world
    .text
    .global _start
    _start:
        /* write */
        mov $1, %rax
        mov $1, %rdi
        mov $hello_world, %rsi
        mov $hello_world_len, %rdx
        syscall
    
        /* exit */
        mov $60, %rax
        mov $0, %rdi
        syscall
    

    compile and run:

    as -o hello_world.o hello_world.S
    ld -o hello_world.out hello_world.o
    ./hello_world.out
    

    GitHub upstream.

    When this happens, the CPU calls an interrupt callback handler which the kernel registered at boot time. Here is a concrete baremetal example that registers a handler and uses it.

    This handler runs in ring 0, which decides if the kernel will allow this action, do the action, and restart the userland program in ring 3. x86_64

  • when the exec system call is used (or when the kernel will start /init), the kernel prepares the registers and memory of the new userland process, then it jumps to the entry point and switches the CPU to ring 3

  • If the program tries to do something naughty like write to a forbidden register or memory address (because of paging), the CPU also calls some kernel callback handler in ring 0.

    But since the userland was naughty, the kernel might kill the process this time, or give it a warning with a signal.

  • When the kernel boots, it setups a hardware clock with some fixed frequency, which generates interrupts periodically.

    This hardware clock generates interrupts that run ring 0, and allow it to schedule which userland processes to wake up.

    This way, scheduling can happen even if the processes are not making any system calls.

What is the point of having multiple rings?

There are two major advantages of separating kernel and userland:

  • it is easier to make programs as you are more certain one won't interfere with the other. E.g., one userland process does not have to worry about overwriting the memory of another program because of paging, nor about putting hardware in an invalid state for another process.
  • it is more secure. E.g. file permissions and memory separation could prevent a hacking app from reading your bank data. This supposes, of course, that you trust the kernel.

How to play around with it?

I've created a bare metal setup that should be a good way to manipulate rings directly: https://github.com/cirosantilli/x86-bare-metal-examples

I didn't have the patience to make a userland example unfortunately, but I did go as far as paging setup, so userland should be feasible. I'd love to see a pull request.

Alternatively, Linux kernel modules run in ring 0, so you can use them to try out privileged operations, e.g. read the control registers: How to access the control registers cr0,cr2,cr3 from a program? Getting segmentation fault

Here is a convenient QEMU + Buildroot setup to try it out without killing your host.

The downside of kernel modules is that other kthreads are running and could interfere with your experiments. But in theory you can take over all interrupt handlers with your kernel module and own the system, that would be an interesting project actually.

Negative rings

While negative rings are not actually referenced in the Intel manual, there are actually CPU modes which have further capabilities than ring 0 itself, and so are a good fit for the "negative ring" name.

One example is the hypervisor mode used in virtualization.

For further details see:

ARM

In ARM, the rings are called Exception Levels instead, but the main ideas remain the same.

There exist 4 exception levels in ARMv8, commonly used as:

  • EL0: userland

  • EL1: kernel ("supervisor" in ARM terminology).

    Entered with the svc instruction (SuperVisor Call), previously known as swi before unified assembly, which is the instruction used to make Linux system calls. Hello world ARMv8 example:

    hello.S

    .text
    .global _start
    _start:
        /* write */
        mov x0, 1
        ldr x1, =msg
        ldr x2, =len
        mov x8, 64
        svc 0
    
        /* exit */
        mov x0, 0
        mov x8, 93
        svc 0
    msg:
        .ascii "hello syscall v8\n"
    len = . - msg
    

    GitHub upstream.

    Test it out with QEMU on Ubuntu 16.04:

    sudo apt-get install qemu-user gcc-arm-linux-gnueabihf
    arm-linux-gnueabihf-as -o hello.o hello.S
    arm-linux-gnueabihf-ld -o hello hello.o
    qemu-arm hello
    

    Here is a concrete baremetal example that registers an SVC handler and does an SVC call.

  • EL2: hypervisors, for example Xen.

    Entered with the hvc instruction (HyperVisor Call).

    A hypervisor is to an OS, what an OS is to userland.

    For example, Xen allows you to run multiple OSes such as Linux or Windows on the same system at the same time, and it isolates the OSes from one another for security and ease of debug, just like Linux does for userland programs.

    Hypervisors are a key part of today's cloud infrastructure: they allow multiple servers to run on a single hardware, keeping hardware usage always close to 100% and saving a lot of money.

    AWS for example used Xen until 2017 when its move to KVM made the news.

  • EL3: yet another level. TODO example.

    Entered with the smc instruction (Secure Mode Call)

The ARMv8 Architecture Reference Model DDI 0487C.a - Chapter D1 - The AArch64 System Level Programmer's Model - Figure D1-1 illustrates this beautifully:

enter image description here

The ARM situation changed a bit with the advent of ARMv8.1 Virtualization Host Extensions (VHE). This extension allows the kernel to run in EL2 efficiently:

enter image description here

VHE was created because in-Linux-kernel virtualization solutions such as KVM have gained ground over Xen (see e.g. AWS' move to KVM mentioned above), because most clients only need Linux VMs, and as you can imagine, being all in a single project, KVM is simpler and potentially more efficient than Xen. So now the host Linux kernel acts as the hypervisor in those cases.

Note how ARM, maybe due to the benefit of hindsight, has a better naming convention for the privilege levels than x86, without the need for negative levels: 0 being the lower and 3 highest. Higher levels tend to be created more often than lower ones.

The current EL can be queried with the MRS instruction: what is the current execution mode/exception level, etc?

ARM does not require all exception levels to be present to allow for implementations that don't need the feature to save chip area. ARMv8 "Exception levels" says:

An implementation might not include all of the Exception levels. All implementations must include EL0 and EL1. EL2 and EL3 are optional.

QEMU for example defaults to EL1, but EL2 and EL3 can be enabled with command line options: qemu-system-aarch64 entering el1 when emulating a53 power up

Code snippets tested on Ubuntu 18.10.

c++ Read from .csv file

a csv-file is just like any other file a stream of characters. the getline reads from the file up to a delimiter however in your case the delimiter for the last item is not ' ' as you assume

getline(file, genero, ' ') ; 

it is newline \n

so change that line to

getline(file, genero); // \n is default delimiter

Rails: How do I create a default value for attributes in Rails activerecord's model?

When I need default values its usually for new records before the new action's view is rendered. The following method will set the default values for only new records so that they are available when rendering forms. before_save and before_create are too late and will not work if you want default values to show up in input fields.

after_initialize do
  if self.new_record?
    # values will be available for new record forms.
    self.status = 'P'
    self.featured = true
  end
end

How to print strings with line breaks in java

You can try using StringBuilder: -

    final StringBuilder sb = new StringBuilder();

    sb.append("SHOP MA\n");
    sb.append("----------------------------\n");
    sb.append("Pannampitiya\n");
    sb.append("09-10-2012 harsha  no: 001\n");
    sb.append("No  Item  Qty  Price  Amount\n");
    sb.append("1 Bread 1 50.00  50.00\n");
    sb.append("____________________________\n");

    // To use StringBuilder as String.. Use `toString()` method..
    System.out.println(sb.toString());   

Datatables - Search Box outside datatable

I want to add one more thing to the @netbrain's answer relevant in case you use server-side processing (see serverSide option).

Query throttling performed by default by datatables (see searchDelay option) does not apply to the .search() API call. You can get it back by using $.fn.dataTable.util.throttle() in the following way:

var table = $('#myTable').DataTable();
var search = $.fn.dataTable.util.throttle(
    function(val) {
        table.search(val).draw();
    },
    400  // Search delay in ms
);

$('#mySearchBox').keyup(function() {
    search(this.value);
});

List all files and directories in a directory + subdirectories

Use the GetDirectories and GetFiles methods to get the folders and files.

Use the SearchOption AllDirectories to get the folders and files in the subfolders also.

How to find where javaw.exe is installed?

Try this

for %i in (javaw.exe) do @echo. %~$PATH:i

How can I remove the string "\n" from within a Ruby string?

You need to use "\n" not '\n' in your gsub. The different quote marks behave differently.

Double quotes " allow character expansion and expression interpolation ie. they let you use escaped control chars like \n to represent their true value, in this case, newline, and allow the use of #{expression} so you can weave variables and, well, pretty much any ruby expression you like into the text.

While on the other hand, single quotes ' treat the string literally, so there's no expansion, replacement, interpolation or what have you.

In this particular case, it's better to use either the .delete or .tr String method to delete the newlines.

See here for more info

flutter corner radius with transparent background

/// Create the bottom sheet UI
  Widget bottomSheetBuilder(){
    return Container(
      color: Color(0xFF737373), // This line set the transparent background
      child: Container(
        decoration: BoxDecoration(
          color: Colors.white,
            borderRadius: BorderRadius.only(
                topLeft: Radius.circular(16.0),
                topRight: Radius.circular( 16.0)
            )
        ),
        child: Center( child: Text("Hi everyone!"),)
      ),
    );
  }

Call this to show the BotoomSheet with corners:

/// Show the bottomSheet when called
  Future _onMenuPressed() async {
    showModalBottomSheet(
        context: context,
        builder: (widgetBuilder) => bottomSheetBuilder()
    );
  }

How to linebreak an svg text within javascript?

I have adapted a bit the solution by @steco, switching the dependency from d3 to jquery and adding the height of the text element as parameter

function wrap(text, width, height) {
  text.each(function(idx,elem) {
    var text = $(elem);
    text.attr("dy",height);
        var words = text.text().split(/\s+/).reverse(),
        word,
        line = [],
        lineNumber = 0,
        lineHeight = 1.1, // ems
        y = text.attr("y"),
        dy = parseFloat( text.attr("dy") ),
        tspan = text.text(null).append("tspan").attr("x", 0).attr("y", y).attr("dy", dy + "em");
    while (word = words.pop()) {
      line.push(word);
      tspan.text(line.join(" "));
      if (elem.getComputedTextLength() > width) {
        line.pop();
        tspan.text(line.join(" "));
        line = [word];
        tspan = text.append("tspan").attr("x", 0).attr("y", y).attr("dy", ++lineNumber * lineHeight + dy + "em").text(word);
      }
    }
  });
}

Is there a way to get the source code from an APK file?

There is also a new application on the Play Store with which it is possible to decompile an apk (system applications too) and view the source code right on your smartphone. It saves the files to your SD card so you can view it on your computer too. It does not require root or something else.

Just install and have fun. I think this is the easiest way to decompile an app.

Get Android .apk file VersionName or VersionCode WITHOUT installing apk

If you are using version 2.2 and above of Android Studio then in Android Studio use Build ? Analyze APK then select AndroidManifest.xml file.

Difference between shared objects (.so), static libraries (.a), and DLL's (.so)?

A static library(.a) is a library that can be linked directly into the final executable produced by the linker,it is contained in it and there is no need to have the library into the system where the executable will be deployed.

A shared library(.so) is a library that is linked but not embedded in the final executable, so will be loaded when the executable is launched and need to be present in the system where the executable is deployed.

A dynamic link library on windows(.dll) is like a shared library(.so) on linux but there are some differences between the two implementations that are related to the OS (Windows vs Linux) :

A DLL can define two kinds of functions: exported and internal. The exported functions are intended to be called by other modules, as well as from within the DLL where they are defined. Internal functions are typically intended to be called only from within the DLL where they are defined.

An SO library on Linux doesn't need special export statement to indicate exportable symbols, since all symbols are available to an interrogating process.

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException

i don't see any for loop to initalize the variables.you can do something like this.

for(i=0;i<50;i++){
 /* Code which is necessary with a simple if statement*/

   }

Detecting a mobile browser

Depends on the use case. All mobile devices require a battery. If what you're after is compute power without draining the battery use the Battery Status API:

navigator.getBattery().then(battery => {
  battery.charging ? 'charging' : 'not charging';
});

If what you're looking for is presentational use matchMedia, which returns a Boolean value:

if (window.matchMedia("(min-width: 400px)").matches) {
  /* the viewport is at least 400 pixels wide */
} else {
  /* the viewport is less than 400 pixels wide */
}

Or combine them for an even better user experience on tablet devices.

Get most recent row for given ID

SELECT *
FROM   tbl
WHERE  id = 1
ORDER  BY signin DESC
LIMIT  1;

The obvious index would be on (id), or a multicolumn index on (id, signin DESC).

Conveniently for the case, MySQL sorts NULL values last in descending order. That's what you typically want if there can be NULL values: the row with the latest not-null signin.

To get NULL values first:

ORDER BY signin IS NOT NULL, signin DESC

You may want to append more expressions to ORDER BY to get a deterministic pick from (potentially) multiple rows with NULL.
The same applies without NULL if signin is not defined UNIQUE.

Related:

The SQL standard does not explicitly define a default sort order for NULL values. The behavior varies quite a bit across different RDBMS. See:

But there are the NULLS FIRST / NULLS LAST clauses defined in the SQL standard and supported by most major RDBMS, but not by MySQL. See:

HTTP 400 (bad request) for logical error, not malformed request syntax

Status 422 (RFC 4918, Section 11.2) comes to mind:

The 422 (Unprocessable Entity) status code means the server understands the content type of the request entity (hence a 415(Unsupported Media Type) status code is inappropriate), and the syntax of the request entity is correct (thus a 400 (Bad Request) status code is inappropriate) but was unable to process the contained instructions. For example, this error condition may occur if an XML request body contains well-formed (i.e., syntactically correct), but semantically erroneous, XML instructions.

Where does Visual Studio look for C++ header files?

If the project came with a Visual Studio project file, then that should already be configured to find the headers for you. If not, you'll have to add the include file directory to the project settings by right-clicking the project and selecting Properties, clicking on "C/C++", and adding the directory containing the include files to the "Additional Include Directories" edit box.

How to align iframe always in the center

I think if you add margin: auto; to the div below it should work.

div#iframe-wrapper iframe {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    margin: auto;
    right: 100px;
    height: 100%;
    width: 100%;
}

How do I remove files saying "old mode 100755 new mode 100644" from unstaged changes in Git?

It seems you have changed some permissions of the directory. I did the following steps to restore it.

$  git diff > backup-diff.txt                ### in case you have some other code changes 

$  git checkout .

Android: failed to convert @drawable/picture into a drawable

I have the same problem on Android Studio. No need to restart the IDE, just close and reopen the project and that will resolve the problem. (Make sure the src are correclty input).

String concatenation with Groovy

I always go for the second method (using the GString template), though when there are more than a couple of parameters like you have, I tend to wrap them in ${X} as I find it makes it more readable.

Running some benchmarks (using Nagai Masato's excellent GBench module) on these methods also shows templating is faster than the other methods:

@Grab( 'com.googlecode.gbench:gbench:0.3.0-groovy-2.0' )
import gbench.*

def (foo,bar,baz) = [ 'foo', 'bar', 'baz' ]
new BenchmarkBuilder().run( measureCpuTime:false ) {
  // Just add the strings
  'String adder' {
    foo + bar + baz
  }
  // Templating
  'GString template' {
    "$foo$bar$baz"
  }
  // I find this more readable
  'Readable GString template' {
    "${foo}${bar}${baz}"
  }
  // StringBuilder
  'StringBuilder' {
    new StringBuilder().append( foo )
                       .append( bar )
                       .append( baz )
                       .toString()
  }
  'StringBuffer' {
    new StringBuffer().append( foo )
                      .append( bar )
                      .append( baz )
                      .toString()
  }
}.prettyPrint()

That gives me the following output on my machine:

Environment
===========
* Groovy: 2.0.0
* JVM: Java HotSpot(TM) 64-Bit Server VM (20.6-b01-415, Apple Inc.)
    * JRE: 1.6.0_31
    * Total Memory: 81.0625 MB
    * Maximum Memory: 123.9375 MB
* OS: Mac OS X (10.6.8, x86_64) 

Options
=======
* Warm Up: Auto 
* CPU Time Measurement: Off

String adder               539
GString template           245
Readable GString template  244
StringBuilder              318
StringBuffer               370

So with readability and speed in it's favour, I'd recommend templating ;-)

NB: If you add toString() to the end of the GString methods to make the output type the same as the other metrics, and make it a fairer test, StringBuilder and StringBuffer beat the GString methods for speed. However as GString can be used in place of String for most things (you just need to exercise caution with Map keys and SQL statements), it can mostly be left without this final conversion

Adding these tests (as it has been asked in the comments)

  'GString template toString' {
    "$foo$bar$baz".toString()
  }
  'Readable GString template toString' {
    "${foo}${bar}${baz}".toString()
  }

Now we get the results:

String adder                        514
GString template                    267
Readable GString template           269
GString template toString           478
Readable GString template toString  480
StringBuilder                       321
StringBuffer                        369

So as you can see (as I said), it is slower than StringBuilder or StringBuffer, but still a bit faster than adding Strings...

But still lots more readable.

Edit after comment by ruralcoder below

Updated to latest gbench, larger strings for concatenation and a test with a StringBuilder initialised to a good size:

@Grab( 'org.gperfutils:gbench:0.4.2-groovy-2.1' )

def (foo,bar,baz) = [ 'foo' * 50, 'bar' * 50, 'baz' * 50 ]
benchmark {
  // Just add the strings
  'String adder' {
    foo + bar + baz
  }
  // Templating
  'GString template' {
    "$foo$bar$baz"
  }
  // I find this more readable
  'Readable GString template' {
    "${foo}${bar}${baz}"
  }
  'GString template toString' {
    "$foo$bar$baz".toString()
  }
  'Readable GString template toString' {
    "${foo}${bar}${baz}".toString()
  }
  // StringBuilder
  'StringBuilder' {
    new StringBuilder().append( foo )
                       .append( bar )
                       .append( baz )
                       .toString()
  }
  'StringBuffer' {
    new StringBuffer().append( foo )
                      .append( bar )
                      .append( baz )
                      .toString()
  }
  'StringBuffer with Allocation' {
    new StringBuffer( 512 ).append( foo )
                      .append( bar )
                      .append( baz )
                      .toString()
  }
}.prettyPrint()

gives

Environment
===========
* Groovy: 2.1.6
* JVM: Java HotSpot(TM) 64-Bit Server VM (23.21-b01, Oracle Corporation)
    * JRE: 1.7.0_21
    * Total Memory: 467.375 MB
    * Maximum Memory: 1077.375 MB
* OS: Mac OS X (10.8.4, x86_64)

Options
=======
* Warm Up: Auto (- 60 sec)
* CPU Time Measurement: On

                                    user  system  cpu  real

String adder                         630       0  630   647
GString template                      29       0   29    31
Readable GString template             32       0   32    33
GString template toString            429       0  429   443
Readable GString template toString   428       1  429   441
StringBuilder                        383       1  384   396
StringBuffer                         395       1  396   409
StringBuffer with Allocation         277       0  277   286

Breaking out of a for loop in Java

How about

for (int k = 0; k < 10; k = k + 2) {
    if (k == 2) {
        break;
    }

    System.out.println(k);
}

The other way is a labelled loop

myloop:  for (int i=0; i < 5; i++) {

              for (int j=0; j < 5; j++) {

                if (i * j > 6) {
                  System.out.println("Breaking");
                  break myloop;
                }

                System.out.println(i + " " + j);
              }
          }

For an even better explanation you can check here

How can I create an editable combo box in HTML/Javascript?

Forget datalist element that good solution for autocomplete function, but not for combobox feature.

css:

.combobox {
    display: inline-block;
    position: relative;
}

.combobox select {
    display: none;
    position: absolute;
    overflow-y: auto;
}

html:

<div class="combobox">
    <input type="number" name="" value="" min="" max="" step=""/><br/>
    <select size="3">
        <option value="0"> 0</option>
        <option value="25"> 25</option>
        <option value="40"> 40</option>
    </select>
</div>

js (jQuery):

$('.combobox').each(function() {
    var
        $input = $(this).find('input'),
        $select = $(this).find('select');
    function hideSelect() {
        setTimeout(function() {
            if (!$select.is(':focus') && !$input.is(':focus')) {
                $select
                    .hide()
                    .css('z-index', 1);
            }
        }, 20);
    }
    $input
        .focusin(function() {
            if (!$select.is(':visible')) {
                $select
                    .outerWidth($input.outerWidth())
                    .show()
                    .css('z-index', 100);
            }
        })
        .focusout(hideSelect)
        .on('input', function() {
            $select.val('');
        });
    $select
        .change(function() {
            $input.val($select.val());
        })
        .focusout(hideSelect);
});

This works properly even when you use text input instead of number.

Overlapping elements in CSS

Use CSS grid and set all the grid items to be in the same cell.

.layered {
  display: grid;
}

.layered > * {
  grid-column-start: 1;
  grid-row-start: 1;
}

Adding the layered class to an element causes all it's children to be layered on top of each other.

if the layers are not the same size you can set the justify-items and align-items properties to set the horizontal and vertical alignment respectively.


Demo:

JsFiddle

_x000D_
_x000D_
.layered {
  display: grid;

  /* Set horizontal alignment of items in, case they have a different width. */
  /* justify-items: start | end | center | stretch (default); */
  justify-items: start;

  /* Set vertical alignment of items, in case they have a different height. */
  /* align-items: start | end | center | stretch (default); */
  align-items: start;
}

.layered > * {
  grid-column-start: 1;
  grid-row-start: 1;
}


/* for demonstration purposes only */
.layered > * {
  outline: 1px solid red;
  background-color: rgba(255, 255, 255, 0.4)
}
_x000D_
<div class="layered">
  <img src="https://via.placeholder.com/250x100?text=first" />
  <p>
    2
  </p>
  <div>
    <p>
      Third layer
    </p>
    <p>
      Third layer continued
    </p>
    <p>
      Third layer continued
    </p>
    <p>
      Third layer continued
    </p>
  </div>
</div>
_x000D_
_x000D_
_x000D_

How to execute a java .class from the command line

You need to specify the classpath. This should do it:

java -cp . Echo "hello"

This tells java to use . (the current directory) as its classpath, i.e. the place where it looks for classes. Note than when you use packages, the classpath has to contain the root directory, not the package subdirectories. e.g. if your class is my.package.Echo and the .class file is bin/my/package/Echo.class, the correct classpath directory is bin.

What characters are allowed in an email address?

Name:

abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!#$%&'*+-/=?^_`{|}~.

Server:

abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-.

Undefined reference to 'vtable for xxx'

You may take a look at this answer to an identical question (as I understand): https://stackoverflow.com/a/1478553 The link posted there explains the problem.

For quick solving your problem you should try to code something like this:

ImplementingClass::virtualFunctionToImplement(){...} It helped me a lot.

os.walk without digging into directories below

You can use this snippet

for root, dirs, files in os.walk(directory):
    if level > 0:
        # do some stuff
    else:
        break
    level-=1

Import Excel spreadsheet columns into SQL Server database

You could use OPENROWSET, something like:

SELECT * FROM OPENROWSET('Microsoft.Jet.OLEDB.4.0', 
  'Excel 8.0;IMEX=1;HDR=NO;DATABASE=C:\FILE.xls', 'Select * from [Sheet1$]'

Just make sure the path is a path on the server, not your local machine.

Android camera intent

private static final int TAKE_PICTURE = 1;    
private Uri imageUri;

public void takePhoto(View view) {
    Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    File photo = new File(Environment.getExternalStorageDirectory(),  "Pic.jpg");
    intent.putExtra(MediaStore.EXTRA_OUTPUT,
            Uri.fromFile(photo));
    imageUri = Uri.fromFile(photo);
    startActivityForResult(intent, TAKE_PICTURE);
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    switch (requestCode) {
    case TAKE_PICTURE:
        if (resultCode == Activity.RESULT_OK) {
            Uri selectedImage = imageUri;
            getContentResolver().notifyChange(selectedImage, null);
            ImageView imageView = (ImageView) findViewById(R.id.ImageView);
            ContentResolver cr = getContentResolver();
            Bitmap bitmap;
            try {
                 bitmap = android.provider.MediaStore.Images.Media
                 .getBitmap(cr, selectedImage);

                imageView.setImageBitmap(bitmap);
                Toast.makeText(this, selectedImage.toString(),
                        Toast.LENGTH_LONG).show();
            } catch (Exception e) {
                Toast.makeText(this, "Failed to load", Toast.LENGTH_SHORT)
                        .show();
                Log.e("Camera", e.toString());
            }
        }
    }
}

How does "304 Not Modified" work exactly?

Last-Modified : The last modified date for the requested object

If-Modified-Since : Allows a 304 Not Modified to be returned if last modified date is unchanged.

ETag : An ETag is an opaque identifier assigned by a web server to a specific version of a resource found at a URL. If the resource representation at that URL ever changes, a new and different ETag is assigned.

If-None-Match : Allows a 304 Not Modified to be returned if ETag is unchanged.

the browser store cache with a date(Last-Modified) or id(ETag), when you need to request the URL again, the browser send request message with the header:

enter image description here

the server will return 304 when the if statement is False, and browser will use cache.

Why does the PHP json_encode function convert UTF-8 strings to hexadecimal entities?

Here is my combined solution for various PHP versions.

In my company we are working with different servers with various PHP versions, so I had to find solution working for all.

$phpVersion = substr(phpversion(), 0, 3)*1;

if($phpVersion >= 5.4) {
  $encodedValue = json_encode($value, JSON_UNESCAPED_UNICODE);
} else {
  $encodedValue = preg_replace('/\\\\u([a-f0-9]{4})/e', "iconv('UCS-4LE','UTF-8',pack('V', hexdec('U$1')))", json_encode($value));
}

Credits should go to Marco Gasi & abu. The solution for PHP >= 5.4 is provided in the json_encode docs.

Does MySQL ignore null values on unique constraints?

I am unsure if the author originally was just asking whether or not this allows duplicate values or if there was an implied question here asking, "How to allow duplicate NULL values while using UNIQUE?" Or "How to only allow one UNIQUE NULL value?"

The question has already been answered, yes you can have duplicate NULL values while using the UNIQUE index.

Since I stumbled upon this answer while searching for "how to allow one UNIQUE NULL value." For anyone else who may stumble upon this question while doing the same, the rest of my answer is for you...

In MySQL you can not have one UNIQUE NULL value, however you can have one UNIQUE empty value by inserting with the value of an empty string.

Warning: Numeric and types other than string may default to 0 or another default value.

Rails 4: List of available datatypes

It is important to know not only the types but the mapping of these types to the database types, too:

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Source added - Agile Web Development with Rails 4

Change directory command in Docker?

RUN git clone http://username:password@url/example.git
WORKDIR /folder
RUN make

How to do a Postgresql subquery in select clause with join in from clause like SQL Server?

I am just answering here with the formatted version of the final sql I needed based on Bob Jarvis answer as posted in my comment above:

select n1.name, n1.author_id, cast(count_1 as numeric)/total_count
  from (select id, name, author_id, count(1) as count_1
          from names
          group by id, name, author_id) n1
inner join (select author_id, count(1) as total_count
              from names
              group by author_id) n2
  on (n2.author_id = n1.author_id)

How to make <input type="date"> supported on all browsers? Any alternatives?

Just use <script src="modernizr.js"></script> in the <head> section, and the script will add classes which help you to separate the two cases: if it's supported by the current browser, or if it's not.

Plus follow the links posted in this thread. It will help you: HTML5 input type date, color, range support in Firefox and Internet Explorer

JavaScript - document.getElementByID with onClick

In JavaScript functions are objects.

document.getElementById('foo').onclick = function(){
    prompt('Hello world');
}

Tomcat 7: How to set initial heap size correctly?

If it's not work in your centos 7 machine "export CATALINA_OPTS="-Xms512M -Xmx1024M"" then you can change heap memory from vi /etc/systemd/system/tomcat.service file then this value shown in your tomcat by help of ps -ef|grep tomcat.

Check a radio button with javascript

Easiest way would probably be with jQuery, as follows:

$(document).ready(function(){
  $("#_1234").attr("checked","checked");
})

This adds a new attribute "checked" (which in HTML does not need a value). Just remember to include the jQuery library:

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

Picking a random element from a set

Javascript solution ;)

function choose (set) {
    return set[Math.floor(Math.random() * set.length)];
}

var set  = [1, 2, 3, 4], rand = choose (set);

Or alternatively:

Array.prototype.choose = function () {
    return this[Math.floor(Math.random() * this.length)];
};

[1, 2, 3, 4].choose();

Select random lines from a file

Sort the file randomly and pick first 100 lines:

$ sort -R input | head -n 100 >output

What are the various "Build action" settings in Visual Studio project properties and what do they do?

  • None: The file is not included in the project output group and is not compiled in the build process. An example is a text file that contains documentation, such as a Readme file.

  • Compile: The file is compiled into the build output. This setting is used for code files.

  • Content: Allows you to retrieve a file (in the same directory as the assembly) as a stream via Application.GetContentStream(URI). For this method to work, it needs a AssemblyAssociatedContentFile custom attribute which Visual Studio graciously adds when you mark a file as "Content"

  • Embedded resource: Embeds the file in an exclusive assembly manifest resource.

  • Resource (WPF only): Embeds the file in a shared (by all files in the assembly with similar setting) assembly manifest resource named AppName.g.resources.

  • Page (WPF only): Used to compile a xaml file into baml. The baml is then embedded with the same technique as Resource (i.e. available as `AppName.g.resources)

  • ApplicationDefinition (WPF only): Mark the XAML/class file that defines your application. You specify the code-behind with the x:Class="Namespace.ClassName" and set the startup form/page with StartupUri="Window1.xaml"

  • SplashScreen (WPF only): An image that is marked as SplashScreen is shown automatically when an WPF application loads, and then fades

  • DesignData: Compiles XAML viewmodels so that usercontrols can be previewed with sample data in Visual Studio (uses mock types)

  • DesignDataWithDesignTimeCreatableTypes: Compiles XAML viewmodels so that usercontrols can be previewed with sample data in Visual Studio (uses actual types)

  • EntityDeploy: (Entity Framework): used to deploy the Entity Framework artifacts

  • CodeAnalysisDictionary: An XML file containing custom word dictionary for spelling rules

Duplicate AssemblyVersion Attribute

If you're having this problem in a Build Pipeline on Azure DevOps, try putting the Build Action as "Content" and Copy to Output Directory equal to "Copy if newer" in the AssembyInfo.cs file properties.

How can I add private key to the distribution certificate?

This site explain step by step that what you need to do Certificates, Identifiers & Profiles and as your question

"Valid Signing identity not found"?

You need the private key that were used to sign the code base with provisioning profile. . If you don't have then you can generate a new signing request on the iOS developer portal.

For Export:

Xcode -> Organizer, select your team. Click Export. Specify a filename and a password, and click Save.`

For Import:

Xcode -> Organizer, select your team. Click Import. Select the file containing your code signing assets. Enter the password for the file, and click Open.

Set a button group's width to 100% and make buttons equal width?

Bootstrap 4

            <ul class="nav nav-pills nav-fill">
                <li class="nav-item">
                    <a class="nav-link active" href="#">Active</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#">Longer nav link</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#">Link</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link disabled" href="#">Disabled</a>
                </li>
            </ul>

Getting the index of the returned max or min item using max()/min() on a list

What about this:

a=[1,55,2,36,35,34,98,0]
max_index=dict(zip(a,range(len(a))))[max(a)]

It creates a dictionary from the items in a as keys and their indexes as values, thus dict(zip(a,range(len(a))))[max(a)] returns the value that corresponds to the key max(a) which is the index of the maximum in a. I'm a beginner in python so I don't know about the computational complexity of this solution.

How to manipulate arrays. Find the average. Beginner Java

-while(int i=0; i < data.length; i++) 
+for(int i=0; i < data.length; i++) 

Regex that matches integers in between whitespace or start/end of string only

I would add this as a comment to the other good answers, but I need more reputation to do so. Be sure to allow for scientific notation if necessary, i.e. 3e4 = 30000. This is default behavior in many languages. I found the following regex to work:

/^[-+]?\d+([Ee][+-]?\d+)?$/;
//          ^^              If 'e' is present to denote exp notation, get it
//             ^^^^^          along with optional sign of exponent
//                  ^^^       and the exponent itself
//        ^            ^^     The entire exponent expression is optional

Get index of selected option with jQuery

You can use the .prop(propertyName) function to get a property from the first element in the jQuery object.

var savedIndex = $(selectElement).prop('selectedIndex');

This keeps your code within the jQuery realm and also avoids the other option of using a selector to find the selected option. You can then restore it using the overload:

$(selectElement).prop('selectedIndex', savedIndex);

How to check if a file exists before creating a new file

Looked around a bit, and the only thing I find is using the open system call. It is the only function I found that allows you to create a file in a way that will fail if it already exists

#include <fcntl.h>
#include <errno.h>

int fd=open(filename, O_WRONLY | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
if (fd < 0) {
  /* file exists or otherwise uncreatable
     you might want to check errno*/
}else {
  /* File is open to writing */
}

Note that you have to give permissions since you are creating a file.

This also removes any race conditions there might be

How to specify the JDK version in android studio?

On a Mac, you can use terminal to go to /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home (or wherever your Android SDK is installed) and enter the following in the command prompt:

./java -version

Display text from .txt file in batch file

Ok I wonder when's the use but, here are two snipets you could use:

lastlog.cmd

@echo off
for /f "delims=" %%l in (log.txt) do set TimeStamp=%%l
echo %TimeStamp%

Change the "echo.." line, but the last log time is within %TimeStamp%. No temp files used, no clutter and reusable as it is in a variable.

On the other hand, if you need to know this WITHIN your code, and not from another batch, change your logging for:

set TimeStamp=%date%, %time%
echo %TimeStamp% >> log.txt

so that the variable %TimeStamp% is usable later when you need it.

How to convert list of key-value tuples into dictionary?

If Tuple has no key repetitions, it's Simple.

tup = [("A",0),("B",3),("C",5)]
dic = dict(tup)
print(dic)

If tuple has key repetitions.

tup = [("A",0),("B",3),("C",5),("A",9),("B",4)]
dic = {}
for i, j in tup:
    dic.setdefault(i,[]).append(j)
print(dic)

Link to "pin it" on pinterest without generating a button

I had the same question. This works great in Wordpress!

<a href="//pinterest.com/pin/create/link/?url=<?php the_permalink();?>&amp;description=<?php the_title();?>">Pin this</a>

Reading and writing environment variables in Python?

Use os.environ[str(DEBUSSY)] for both reading and writing (http://docs.python.org/library/os.html#os.environ).

As for reading, you have to parse the number from the string yourself of course.

How to var_dump variables in twig templates?

{{ dump() }} doesn't work for me. PHP chokes. Nesting level too deep I guess.

All you really need to debug Twig templates if you're using a debugger is an extension like this.

Then it's just a matter of setting a breakpoint and calling {{ inspect() }} wherever you need it. You get the same info as with {{ dump() }} but in your debugger.

Notice: Undefined offset: 0 in

As explained it happens because there is no data in the $cur_votes[0] and hence it throws an error.

To ensure your code works fine, before performing "$votes_up = $cur_votes[0]+1;" echo the $cur_votes[0] value to see if there is any value stored or not.

Surely, there is no value stored.

ASP.NET MVC 3 - redirect to another action

return RedirectToAction("ActionName", "ControllerName");

Bootstrap 3 Navbar Collapse

Thanks to Seb33300 I got this working. However, an important part seems to be missing. At least in Bootstrap version 3.1.1.

My problem was that the navbar collapsed accordingly at the correct width, but the menu button didn't work. I couldn't expand and collapse the menu.

This is because the collapse.in class is overrided by the !important in .navbar-collapse.collapse, and can be solved by also adding the "collapse.in". Seb33300's example completed below:

@media (max-width: 991px) {
    .navbar-header {
        float: none;
    }
    .navbar-toggle {
        display: block;
    }
    .navbar-collapse {
        border-top: 1px solid transparent;
        box-shadow: inset 0 1px 0 rgba(255,255,255,0.1);
    }
    .navbar-collapse.collapse {
        display: none!important;
    }
    .navbar-collapse.collapse.in {
        display: block!important;
    }
    .navbar-nav {
        float: none!important;
        margin: 7.5px -15px;
    }
    .navbar-nav>li {
        float: none;
    }
    .navbar-nav>li>a {
        padding-top: 10px;
        padding-bottom: 10px;
    }
}

In C#, how to check whether a string contains an integer?

Sorry, didn't quite get your question. So something like this?

str.ToCharArray().Any(char.IsDigit);

Or does the value have to be an integer completely, without any additional strings?

if(str.ToCharArray().All(char.IsDigit(c));

How to inject a Map using the @Value Spring Annotation?

To get this working with YAML, do this:

property-name: '{
  key1: "value1",
  key2: "value2"
}'

From a Sybase Database, how I can get table description ( field names and types)?

If you want to use a command line program, but are not restricted to using SQL, you can use SchemaCrawler. SchemaCrawler is open source, and can produce files in plain text, CSV, or (X)HTML formats.

How do I include negative decimal numbers in this regular expression?

^[+-]?\d{1,18}(\.\d{1,2})?$

accepts positive or negative decimal values.

How do I print out the contents of a vector?

I see two problems. As pointed out in

for (x = 17; isalpha(firstsquare); x++)

there's either an infinite loop or never executed at all, and also in if (entrance == 'S') if the entrance character is different than 'S' then nothing in pushed to the path vector, making it empty and thus printing nothing on screen. You can test the latter checking for path.empty() or printing path.size().

Either way, wouldn't it be better to use a string instead of a vector? You can access the string contents like an array as well, seek characters, extract substrings and print the string easily (without a loop).

Doing it all with strings might be the way to have it written in a less convoluted way and make it easier to spot the problem.

How to check db2 version

You can try the following query:

SELECT service_level, fixpack_num FROM TABLE
  (sysproc.env_get_inst_info())
  as INSTANCEINFO

It works on LUW, so I can't guarantee that it'll work on z/OS, but it's worth a shot.

Get current date in milliseconds

An extension on date is probably the best way to about it.

extension NSDate {
    func msFromEpoch() -> Double {
        return self.timeIntervalSince1970 * 1000
    }
}

Difference between MEAN.js and MEAN.io

The Starter Trade-offs sheet of my comparison spreadsheet has comprehensive one-on-one comparisons between each generator. So no more need to distortedly cherry-pick great things to say about your favorite.

Here is the one between generator-angular-fullstack and MEAN.js. The percentages are values for each benefit based on my personal weightings, where a perfect generator would be 100%

generator- angular- fullstack offers 8% that MEANJS.org doesn't

  • 1.9% Client-side end-to-end tests
  • 0.6% factory
  • 0.5% provider
  • 0.4% SASS
  • 0.4% LESS
  • 0.4% Compass
  • 0.4% decorator
  • 0.4% Endpoint subgenerator
  • 0.4% Comments
  • 0.3% FontAwesome
  • 0.3% Run server in debug mode
  • 0.3% Save generator answers to a file
  • 0.2% constant
  • 0.2% Development build script: ...... replace 3rd party deps with CDN versions
  • 0.2% Authentication - Cookie
  • 0.2% Authentication - JSON Web Token (JWT)
  • 0.2% Server-side logging
  • 0.1% Development build script: run tasks in parallel to speed it up
  • 0.1% Development build script: Renames asset files to prevent browser caching
  • 0.1% Development build script: run end to end tests
  • 0.1% Production build script: safe pre-minification
  • 0.1% Production build script: add CSS vendor prefixes
  • 0.1% Heroku deployment automation
  • 0.1% value
  • 0.1% Jade
  • 0.1% Coffeescript
  • 0.1% Serverside authenticated route restriction
  • 0.1% SASS version of Twitter Bootstrap
  • 0.1% Production build script: compress images
  • 0.1% OpenShift deployment automation

MeanJS.org. offers 9% that generator-angular-fullstack doesn't

  • 3.7% Dedicated/searchable user group: response time mostly under a day
  • 0.4% Generate routes
  • 0.4% Authentication - Oauth
  • 0.4% config
  • 0.4% i18n, localization
  • 0.4% Input application profile
  • 0.3% FEATURE (a.k.a. module, entity, crud-mock)
  • 0.3% Menus system
  • 0.3% Options for making subcomponents
  • 0.3% test - client side
  • 0.3% Javascript performance thing
  • 0.3% Production build script: make static pages for SEO
  • 0.2% Quick install?
  • 0.2% Dedicated/searchable user group
  • 0.1% Development build script: reload build file upon change
  • 0.1% Development build script: coffee files compiled to JS
  • 0.1% controller - server side
  • 0.1% model - server side
  • 0.1% route - server side
  • 0.1% test - server side
  • 0.1% Swig
  • 0.1% Safe from IP Spoofing
  • 0.1% Production build script: uglification
  • 0.0% Approach to views: URLs start with "#!"
  • 0.0% Approach to frontend services and ajax calls: uses $resource

Here is the one between MEAN.io and MEAN.js in a more readable format

_x000D_
_x000D_
<table border="1" cellpadding="10"><tbody><tr><td valign="top" width="33%"><br><br><h1>MeanJS.org. provides these benefits that MEAN.io. doesn't</h1><br><br><b>Help</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Dedicated/searchable user group for questions, using github issues<br>&nbsp;&nbsp;&nbsp;&nbsp;* There's a book about it<br><b>File Organization</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Basic sourcecode organization, module(-&gt;submodule)-&gt;side<br>&nbsp;&nbsp;&nbsp;&nbsp;* Module directories hold directives<br><b>Code Modularization</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to AngularJS modules, Only one module definition per file<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to AngularJS modules, Don’t alter a module other than where it is defined<br><b>Model</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Object-relational mapping<br>&nbsp;&nbsp;&nbsp;&nbsp;* Server-side validation, server-side example<br>&nbsp;&nbsp;&nbsp;&nbsp;* Client side validation, using Angular 1.3<br><b>View</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to AngularJS views, Directives start with "data-"<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to data readiness, Use ng-init<br><b>Control</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to frontend routing or state changing, URLs start with '#!'<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to frontend routing or state changing, Use query parameters to store route state<br><b>Support for things</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Languages, LESS<br>&nbsp;&nbsp;&nbsp;&nbsp;* Languages, SASS<br><b>Syntax, language and coding</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* JavaScript 5 best practices, Don't use "new"<br><b>Testing</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Testing, using Mocha<br>&nbsp;&nbsp;&nbsp;&nbsp;* End-to-end tests<br>&nbsp;&nbsp;&nbsp;&nbsp;* End-to-end tests, using Protractor<br>&nbsp;&nbsp;&nbsp;&nbsp;* Continuous integration (CI), using Travis<br><b>Development and debugging</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Command line interface (CLI), using Yeoman<br><b>Build</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Build configurations file(s)<br>&nbsp;&nbsp;&nbsp;&nbsp;* Deployment automation, using Azure<br>&nbsp;&nbsp;&nbsp;&nbsp;* Deployment automation, using Digital Ocean, screencast of it<br>&nbsp;&nbsp;&nbsp;&nbsp;* Deployment automation, using Heroku, screencast of it<br><b>Code Generation</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Input application profile<br>&nbsp;&nbsp;&nbsp;&nbsp;* Quick install?<br>&nbsp;&nbsp;&nbsp;&nbsp;* Options for making subcomponents<br>&nbsp;&nbsp;&nbsp;&nbsp;* config generator<br>&nbsp;&nbsp;&nbsp;&nbsp;* controller (client side) generator<br>&nbsp;&nbsp;&nbsp;&nbsp;* directive generator<br>&nbsp;&nbsp;&nbsp;&nbsp;* filter generator<br>&nbsp;&nbsp;&nbsp;&nbsp;* route (client side) generator<br>&nbsp;&nbsp;&nbsp;&nbsp;* service (client side) generator<br>&nbsp;&nbsp;&nbsp;&nbsp;* test - client side<br>&nbsp;&nbsp;&nbsp;&nbsp;* view or view partial generator<br>&nbsp;&nbsp;&nbsp;&nbsp;* controller (server side) generator<br>&nbsp;&nbsp;&nbsp;&nbsp;* model (server side) generator<br>&nbsp;&nbsp;&nbsp;&nbsp;* route (server side) generator<br>&nbsp;&nbsp;&nbsp;&nbsp;* test (server side) generator<br><b>Implemented Functionality</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Account Management, Forgotten Password with Resetting<br>&nbsp;&nbsp;&nbsp;&nbsp;* Chat<br>&nbsp;&nbsp;&nbsp;&nbsp;* CSV processing<br>&nbsp;&nbsp;&nbsp;&nbsp;* E-mail sending system<br>&nbsp;&nbsp;&nbsp;&nbsp;* E-mail sending system, using Nodemailer<br>&nbsp;&nbsp;&nbsp;&nbsp;* E-mail sending system, using its own e-mail implementation<br>&nbsp;&nbsp;&nbsp;&nbsp;* Menus system, state-based<br>&nbsp;&nbsp;&nbsp;&nbsp;* Paypal integration<br>&nbsp;&nbsp;&nbsp;&nbsp;* Responsive design<br>&nbsp;&nbsp;&nbsp;&nbsp;* Social connections management page<br><b>Performance</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Creates a favicon<br><b>Security</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Safe from IP Spoofing<br>&nbsp;&nbsp;&nbsp;&nbsp;* Authorization, Access Contol List (ACL)<br>&nbsp;&nbsp;&nbsp;&nbsp;* Authentication, Cookie<br>&nbsp;&nbsp;&nbsp;&nbsp;* Websocket and RESTful http share security policies<br><br><br></td><td valign="top" width="33%"><br><br><h1>MEAN.io. provides these benefits that MeanJS.org. doesn't</h1><br><br><b>Quality</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Sponsoring company<br><b>Help</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Docs with flatdoc<br><b>Code Modularization</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Share code between projects<br>&nbsp;&nbsp;&nbsp;&nbsp;* Module manager<br><b>View</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to data readiness, Use state.resolve()<br><b>Control</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to frontend code loading, Use AMD with Require.js<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to frontend code loading, using wiredep<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to error handling, Server-side logging<br><b>Client/Server Communication</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Centralized event handling<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to XHR calls, using $http and $q<br><b>Syntax, language and coding</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* JavaScript 5 best practices, Wrap code in an IIFE (SEAF, SIAF)<br><b>Development and debugging</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* API introspection report and testing interface, using Swagger<br>&nbsp;&nbsp;&nbsp;&nbsp;* Command line interface (CLI), using Independent command line interface<br><b>Build</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Development build, add IIFEs (SEAF, SIAF) to executable copies of code<br>&nbsp;&nbsp;&nbsp;&nbsp;* Deployment automation<br>&nbsp;&nbsp;&nbsp;&nbsp;* Deployment automation, using Heroku<br><b>Code Generation</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Scaffolding undo&nbsp;&nbsp;&nbsp;&nbsp;(mean package -d &lt;name&gt;)<br>&nbsp;&nbsp;&nbsp;&nbsp;* FEATURE (a.k.a. module, entity) generator, Menu items added for new features<br><b>Implemented Functionality</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Admin page for users and roles<br>&nbsp;&nbsp;&nbsp;&nbsp;* Content Management System&nbsp;&nbsp;&nbsp;&nbsp;(Use special data-bound directives in your templates.<br>Switch to edit mode and you can edit the values right where you see them)<br>&nbsp;&nbsp;&nbsp;&nbsp;* File Upload<br>&nbsp;&nbsp;&nbsp;&nbsp;* i18n, localization<br>&nbsp;&nbsp;&nbsp;&nbsp;* Menus system, submenus<br>&nbsp;&nbsp;&nbsp;&nbsp;* Search<br>&nbsp;&nbsp;&nbsp;&nbsp;* Search, actually works with backend API<br>&nbsp;&nbsp;&nbsp;&nbsp;* Search, using Elastic Search<br>&nbsp;&nbsp;&nbsp;&nbsp;* Styles, using Bootstrap, using UI Bootstrap AngularJS directives<br>&nbsp;&nbsp;&nbsp;&nbsp;* Text (WYSIWYG) Editor<br>&nbsp;&nbsp;&nbsp;&nbsp;* Text (WYSIWYG) Editor, using medium-editor<br><b>Performance</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Instrumentation, server-side<br><b>Security</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Serverside authenticated route restriction<br>&nbsp;&nbsp;&nbsp;&nbsp;* Authentication, using Oauth, Link multiple Oauth strategies to one account<br>&nbsp;&nbsp;&nbsp;&nbsp;* Authentication, JSON Web Token (JWT)<br><br><br></td><td valign="top" width="33%"><br><br><h1>MEAN.io. and MeanJS.org. both provide these benefits</h1><br><br><b>Quality</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Version Control, using git<br><b>Platforms</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Client-side JS Framework, using AngularJS<br>&nbsp;&nbsp;&nbsp;&nbsp;* Frontend Server/ Framework, using Node.JS<br>&nbsp;&nbsp;&nbsp;&nbsp;* Frontend Server/ Framework, using Node.JS, using Express<br>&nbsp;&nbsp;&nbsp;&nbsp;* API Server/ Framework, using NodeJS<br>&nbsp;&nbsp;&nbsp;&nbsp;* API Server/ Framework, using NodeJS, using Express<br><b>Help</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Dedicated/searchable user group for questions<br>&nbsp;&nbsp;&nbsp;&nbsp;* Dedicated/searchable user group for questions, using Google Groups<br>&nbsp;&nbsp;&nbsp;&nbsp;* Dedicated/searchable user group for questions, using Facebook<br>&nbsp;&nbsp;&nbsp;&nbsp;* Dedicated/searchable user group for questions, response time mostly under a day<br>&nbsp;&nbsp;&nbsp;&nbsp;* Example application<br>&nbsp;&nbsp;&nbsp;&nbsp;* Tutorial screencast in English<br>&nbsp;&nbsp;&nbsp;&nbsp;* Tutorial screencast in English, using Youtube<br>&nbsp;&nbsp;&nbsp;&nbsp;* Dedicated chatroom<br><b>File Organization</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Basic sourcecode organization, module(-&gt;submodule)-&gt;side, with type subfolders<br>&nbsp;&nbsp;&nbsp;&nbsp;* Module directories hold controllers<br>&nbsp;&nbsp;&nbsp;&nbsp;* Module directories hold services<br>&nbsp;&nbsp;&nbsp;&nbsp;* Module directories hold templates<br>&nbsp;&nbsp;&nbsp;&nbsp;* Module directories hold unit tests<br>&nbsp;&nbsp;&nbsp;&nbsp;* Separate route configuration files for each module<br><b>Code Modularization</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Modularized Functionality<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to AngularJS modules, No global 'app' module variable<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to AngularJS modules, No global 'app' module variable without an IIFE<br><b>Model</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Setup of persistent storage<br>&nbsp;&nbsp;&nbsp;&nbsp;* Setup of persistent storage, using NoSQL db<br>&nbsp;&nbsp;&nbsp;&nbsp;* Setup of persistent storage, using NoSQL db, using MongoDB<br><b>View</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* No XHR calls in controllers<br>&nbsp;&nbsp;&nbsp;&nbsp;* Templates, using Angular directives<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to data readiness, prevents Flash of Unstyled/compiled Content (FOUC)<br><b>Control</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to frontend routing or state changing, example of it<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to frontend routing or state changing, State-based routing<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to frontend routing or state changing, State-based routing, using ui-router<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to frontend routing or state changing, HTML5 Mode<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to frontend code loading, using angular.bootstrap()<br><b>Client/Server Communication</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Serve status codes only as responses<br>&nbsp;&nbsp;&nbsp;&nbsp;* Accept nested, JSON parameters<br>&nbsp;&nbsp;&nbsp;&nbsp;* Add timer header to requests<br>&nbsp;&nbsp;&nbsp;&nbsp;* Support for signed and encrypted cookies<br>&nbsp;&nbsp;&nbsp;&nbsp;* Serve URLs based on the route definitions<br>&nbsp;&nbsp;&nbsp;&nbsp;* Can serve headers only<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to XHR calls, using JSON<br>&nbsp;&nbsp;&nbsp;&nbsp;* Approach to XHR calls, using $resource (angular-resource)<br><b>Support for things</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Languages, JavaScript (server side)<br>&nbsp;&nbsp;&nbsp;&nbsp;* Languages, Swig<br><b>Syntax, language and coding</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* JavaScript 5 best practices, Use 'use strict'<br><b>Tool Configuration/customization</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Separate runtime configuration profiles<br><b>Testing</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Testing, using Jasmine<br>&nbsp;&nbsp;&nbsp;&nbsp;* Testing, using Karma<br>&nbsp;&nbsp;&nbsp;&nbsp;* Client-side unit tests<br>&nbsp;&nbsp;&nbsp;&nbsp;* Continuous integration (CI)<br>&nbsp;&nbsp;&nbsp;&nbsp;* Automated device testing, using Live Reload<br>&nbsp;&nbsp;&nbsp;&nbsp;* Server-side integration &amp; unit tests<br>&nbsp;&nbsp;&nbsp;&nbsp;* Server-side integration &amp; unit tests, using Mocha<br><b>Development and debugging</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Command line interface (CLI)<br><b>Build</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Build-time Dependency Management, using npm<br>&nbsp;&nbsp;&nbsp;&nbsp;* Build-time Dependency Management, using bower<br>&nbsp;&nbsp;&nbsp;&nbsp;* Build tool / Task runner, using Grunt<br>&nbsp;&nbsp;&nbsp;&nbsp;* Build tool / Task runner, using gulp<br>&nbsp;&nbsp;&nbsp;&nbsp;* Development build, script<br>&nbsp;&nbsp;&nbsp;&nbsp;* Development build, reload build script file upon change<br>&nbsp;&nbsp;&nbsp;&nbsp;* Development build, copy assets to build or dist or target folder<br>&nbsp;&nbsp;&nbsp;&nbsp;* Development build, html page processing<br>&nbsp;&nbsp;&nbsp;&nbsp;* Development build, html page processing, inject references by searching directories<br>&nbsp;&nbsp;&nbsp;&nbsp;* Development build, html page processing, inject references by searching directories, injects js references<br>&nbsp;&nbsp;&nbsp;&nbsp;* Development build, html page processing, inject references by searching directories, injects css references<br>&nbsp;&nbsp;&nbsp;&nbsp;* Development build, LESS/SASS/etc files are linted, compiled<br>&nbsp;&nbsp;&nbsp;&nbsp;* Development build, JavaScript style checking<br>&nbsp;&nbsp;&nbsp;&nbsp;* Development build, JavaScript style checking, using jshint or jslint<br>&nbsp;&nbsp;&nbsp;&nbsp;* Development build, run unit tests<br>&nbsp;&nbsp;&nbsp;&nbsp;* Production build, script<br>&nbsp;&nbsp;&nbsp;&nbsp;* Production build, concatenation (aggregation, globbing, bundling)&nbsp;&nbsp;&nbsp;&nbsp;(If you add debug:true to your config/env/development.js the will not be <br>uglified)<br>&nbsp;&nbsp;&nbsp;&nbsp;* Production build, minification<br>&nbsp;&nbsp;&nbsp;&nbsp;* Production build, safe pre-minification, using ng-annotate<br>&nbsp;&nbsp;&nbsp;&nbsp;* Production build, uglification<br>&nbsp;&nbsp;&nbsp;&nbsp;* Production build, make static pages for SEO<br><b>Code Generation</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* FEATURE (a.k.a. module, entity) generator&nbsp;&nbsp;&nbsp;&nbsp;(README.md<br>feature css<br>routes<br>controller<br>view<br>additional menu item)<br><b>Implemented Functionality</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* 404 Page<br>&nbsp;&nbsp;&nbsp;&nbsp;* 500 Page<br>&nbsp;&nbsp;&nbsp;&nbsp;* Account Management<br>&nbsp;&nbsp;&nbsp;&nbsp;* Account Management, register/login/logout<br>&nbsp;&nbsp;&nbsp;&nbsp;* Account Management, is password manager friendly<br>&nbsp;&nbsp;&nbsp;&nbsp;* Front-end CRUD<br>&nbsp;&nbsp;&nbsp;&nbsp;* Full-stack CRUD<br>&nbsp;&nbsp;&nbsp;&nbsp;* Full-stack CRUD, with Read<br>&nbsp;&nbsp;&nbsp;&nbsp;* Full-stack CRUD, with Create, Update and Delete<br>&nbsp;&nbsp;&nbsp;&nbsp;* Google Analytics<br>&nbsp;&nbsp;&nbsp;&nbsp;* Menus system<br>&nbsp;&nbsp;&nbsp;&nbsp;* Realtime data sync<br>&nbsp;&nbsp;&nbsp;&nbsp;* Realtime data sync, using socket.io<br>&nbsp;&nbsp;&nbsp;&nbsp;* Styles, using Bootstrap<br><b>Performance</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* Javascript performance thing<br>&nbsp;&nbsp;&nbsp;&nbsp;* Javascript performance thing, using lodash<br>&nbsp;&nbsp;&nbsp;&nbsp;* One event-loop thread handles all requests<br>&nbsp;&nbsp;&nbsp;&nbsp;* Configurable response caching&nbsp;&nbsp;&nbsp;&nbsp;(Express plugin<br><b>https</b>://www.npmjs.org/package/apicache)<br>&nbsp;&nbsp;&nbsp;&nbsp;* Clustered HTTP sessions<br><b>Security</b>:<br>&nbsp;&nbsp;&nbsp;&nbsp;* JavaScript obfuscation<br>&nbsp;&nbsp;&nbsp;&nbsp;* https<br>&nbsp;&nbsp;&nbsp;&nbsp;* Authentication, using Oauth<br>&nbsp;&nbsp;&nbsp;&nbsp;* Authentication, Basic&nbsp;&nbsp;&nbsp;&nbsp;(With Passport or others)<br>&nbsp;&nbsp;&nbsp;&nbsp;* Authentication, Digest&nbsp;&nbsp;&nbsp;&nbsp;(With Passport or others)<br>&nbsp;&nbsp;&nbsp;&nbsp;* Authentication, Token&nbsp;&nbsp;&nbsp;&nbsp;(With Passport or others)<br></td></tr></tbody></table>
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How to determine whether a given Linux is 32 bit or 64 bit?

I can't believe that in all this time, no one has mentioned:

sudo lshw -class cpu

to get details about the speed, quantity, size and capabilities of the CPU hardware.

Adding data attribute to DOM

Using .data() will only add data to the jQuery object for that element. In order to add the information to the element itself you need to access that element using jQuery's .attr or native .setAttribute

$('div').attr('data-info', 1);
$('div')[0].setAttribute('data-info',1);

In order to access an element with the attribute set, you can simply select based on that attribute as you note in your post ($('div[data-info="1"]')), but when you use .data() you cannot. In order to select based on the .data() setting, you would need to use jQuery's filter function.

jsFiddle Demo

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$('div').data('info', 1);_x000D_
//alert($('div').data('info'));//1_x000D_
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$('div').filter(function(){_x000D_
   return $(this).data('info') == 1; _x000D_
}).text('222');
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<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<div>1</div>
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Can't install any package with node npm

If anyone is specifically getting Unexpected token <, and your package.json is fine, check your npm-shrinkwrap.json file! I had unresolved merge issues in mine, and fixing that resolved everything.

Using Excel VBA to run SQL query

Below is code that I currently use to pull data from a MS SQL Server 2008 into VBA. You need to make sure you have the proper ADODB reference [VBA Editor->Tools->References] and make sure you have Microsoft ActiveX Data Objects 2.8 Library checked, which is the second from the bottom row that is checked (I'm using Excel 2010 on Windows 7; you might have a slightly different ActiveX version, but it will still begin with Microsoft ActiveX):

References required for SQL

Sub Module for Connecting to MS SQL with Remote Host & Username/Password

Sub Download_Standard_BOM()
'Initializes variables
Dim cnn As New ADODB.Connection
Dim rst As New ADODB.Recordset
Dim ConnectionString As String
Dim StrQuery As String

'Setup the connection string for accessing MS SQL database
   'Make sure to change:
       '1: PASSWORD
       '2: USERNAME
       '3: REMOTE_IP_ADDRESS
       '4: DATABASE
    ConnectionString = "Provider=SQLOLEDB.1;Password=PASSWORD;Persist Security Info=True;User ID=USERNAME;Data Source=REMOTE_IP_ADDRESS;Use Procedure for Prepare=1;Auto Translate=True;Packet Size=4096;Use Encryption for Data=False;Tag with column collation when possible=False;Initial Catalog=DATABASE"

    'Opens connection to the database
    cnn.Open ConnectionString
    'Timeout error in seconds for executing the entire query; this will run for 15 minutes before VBA timesout, but your database might timeout before this value
    cnn.CommandTimeout = 900

    'This is your actual MS SQL query that you need to run; you should check this query first using a more robust SQL editor (such as HeidiSQL) to ensure your query is valid
    StrQuery = "SELECT TOP 10 * FROM tbl_table"

    'Performs the actual query
    rst.Open StrQuery, cnn
    'Dumps all the results from the StrQuery into cell A2 of the first sheet in the active workbook
    Sheets(1).Range("A2").CopyFromRecordset rst
End Sub

Change the column label? e.g.: change column "A" to column "Name"

What version of Excel?

In general, you cannot change the column letters. They are part of the Excel system.

You can use a row in the sheet to enter headers for a table that you are using. The table headers can be descriptive column names.

In Excel 2007 and later, you can convert a range of data into an Excel Table (Insert Ribbon > Table). An Excel Table can use structured table references instead of cell addresses, so the labels in the first row of the table now serve as a name reference for the data in the column.

If you have an Excel Table in your sheet (Excel 2007 and later) and scroll down, the column letters will be replaced with the column headers for the table column.

enter image description here

If this does not answer your question, please consider editing your question to include the detail you want to learn about.

Can't resolve module (not found) in React.js

Deleted the package-lock.json file & then ran

npm install

Read further

UTF-8 byte[] to String

This also involves iterating, but this is much better than concatenating strings as they are very very costly.

public String openFileToString(String fileName)
{
    StringBuilder s = new StringBuilder(_bytes.length);

    for(int i = 0; i < _bytes.length; i++)
    {
        s.append((char)_bytes[i]);
    }

    return s.toString();    
}

How to Right-align flex item?

A more flex approach would be to use an auto left margin (flex items treat auto margins a bit differently than when used in a block formatting context).

.c {
    margin-left: auto;
}

Updated fiddle:

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.main { display: flex; }_x000D_
.a, .b, .c { background: #efefef; border: 1px solid #999; }_x000D_
.b { flex: 1; text-align: center; }_x000D_
.c {margin-left: auto;}
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<h2>With title</h2>_x000D_
<div class="main">_x000D_
    <div class="a"><a href="#">Home</a></div>_x000D_
    <div class="b"><a href="#">Some title centered</a></div>_x000D_
    <div class="c"><a href="#">Contact</a></div>_x000D_
</div>_x000D_
<h2>Without title</h2>_x000D_
<div class="main">_x000D_
    <div class="a"><a href="#">Home</a></div>_x000D_
    <!--<div class="b"><a href="#">Some title centered</a></div>-->_x000D_
    <div class="c"><a href="#">Contact</a></div>_x000D_
</div>_x000D_
<h1>Problem</h1>_x000D_
<p>Is there a more flexbox-ish way to right align "Contact" than to use position absolute?</p>
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How do I install g++ on MacOS X?

Type g++(or make) on terminal.

This will prompt for you to install the developer tools, if they are missing.

Also the size will be very less when compared to xcode

Writing Unicode text to a text file?

In case of writing in python3

>>> a = u'bats\u00E0'
>>> print a
batsà
>>> f = open("/tmp/test", "w")
>>> f.write(a)
>>> f.close()
>>> data = open("/tmp/test").read()
>>> data
'batsà'

In case of writing in python2:

>>> a = u'bats\u00E0'
>>> f = open("/tmp/test", "w")
>>> f.write(a)

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeEncodeError: 'ascii' codec can't encode character u'\xe0' in position 4: ordinal not in range(128)

To avoid this error you would have to encode it to bytes using codecs "utf-8" like this:

>>> f.write(a.encode("utf-8"))
>>> f.close()

and decode the data while reading using the codecs "utf-8":

>>> data = open("/tmp/test").read()
>>> data.decode("utf-8")
u'bats\xe0'

And also if you try to execute print on this string it will automatically decode using the "utf-8" codecs like this

>>> print a
batsà

Upload Image using POST form data in Python-requests

For Rest API to upload images from host to host:

import urllib2
import requests

api_host = 'https://host.url.com/upload/'
headers = {'Content-Type' : 'image/jpeg'}
image_url = 'http://image.url.com/sample.jpeg'

img_file = urllib2.urlopen(image_url)

response = requests.post(api_host, data=img_file.read(), headers=headers, verify=False)

You can use option verify set to False to omit SSL verification for HTTPS requests.

Set variable with multiple values and use IN

Use a Temp Table or a Table variable, e.g.

select 'A' as [value]
into #tmp
union
select 'B'
union 
select 'C'

and then

SELECT   
blah 
FROM    foo 
WHERE   myField IN (select [value] from #tmp) 

or

SELECT   
f.blah 
FROM foo f INNER JOIN #tmp t ON f.myField = t.[value]

Add a new column to existing table in a migration

Although a migration file is best practice as others have mentioned, in a pinch you can also add a column with tinker.

$ php artisan tinker

Here's an example one-liner for the terminal:

Schema::table('users', function(\Illuminate\Database\Schema\Blueprint $table){ $table->integer('paid'); })



(Here it is formatted for readability)

Schema::table('users', function(\Illuminate\Database\Schema\Blueprint $table){ 
    $table->integer('paid'); 
});

finding and replacing elements in a list

List comprehension works well, and looping through with enumerate can save you some memory (b/c the operation's essentially being done in place).

There's also functional programming. See usage of map:

>>> a = [1,2,3,2,3,4,3,5,6,6,5,4,5,4,3,4,3,2,1]
>>> map(lambda x: x if x != 4 else 'sss', a)
[1, 2, 3, 2, 3, 'sss', 3, 5, 6, 6, 5, 'sss', 5, 'sss', 3, 'sss', 3, 2, 1]

Mocking a method to throw an exception (moq), but otherwise act like the mocked object?

This is how I managed to do what I was trying to do:

[Test]
public void TransferHandlesDisconnect()
{
    // ... set up config here
    var methodTester = new Mock<Transfer>(configInfo);
    methodTester.CallBase = true;
    methodTester
        .Setup(m => 
            m.GetFile(
                It.IsAny<IFileConnection>(), 
                It.IsAny<string>(), 
                It.IsAny<string>()
            ))
        .Throws<System.IO.IOException>();

    methodTester.Object.TransferFiles("foo1", "foo2");
    Assert.IsTrue(methodTester.Object.Status == TransferStatus.TransferInterrupted);
}

If there is a problem with this method, I would like to know; the other answers suggest I am doing this wrong, but this was exactly what I was trying to do.

Multiple WHERE Clauses with LINQ extension methods

Surely:

if (useAdditionalClauses) 
{ 
  results = 
    results.Where(o => o.OrderStatus == OrderStatus.Open && 
    o.CustomerID == customerID)  
} 

Or just another .Where() call like this one (although I don't know why you would want to, unless it's split by another boolean control variable):

if (useAdditionalClauses) 
{ 
  results = results.Where(o => o.OrderStatus == OrderStatus.Open).
    Where(o => o.CustomerID == customerID);
} 

Or another reassignment to results: `results = results.Where(blah).

How to find the statistical mode?

A quick and dirty way of estimating the mode of a vector of numbers you believe come from a continous univariate distribution (e.g. a normal distribution) is defining and using the following function:

estimate_mode <- function(x) {
  d <- density(x)
  d$x[which.max(d$y)]
}

Then to get the mode estimate:

x <- c(5.8, 5.6, 6.2, 4.1, 4.9, 2.4, 3.9, 1.8, 5.7, 3.2)
estimate_mode(x)
## 5.439788

Is there Unicode glyph Symbol to represent "Search"

You can simply add this CSS to your header

<link href='http://netdna.bootstrapcdn.com/font-awesome/4.0.3/css/font-awesome.css' rel='stylesheet' type='text/css'>

next add this code in place where you want to display a glyph symbol.

<div class="fa fa-search"></div> <!-- smaller -->
<div class="fa fa-search fa-2x"></div> <!-- bigger -->

Have fun.

How to keep :active css style after click a button

I FIGURED IT OUT. SIMPLE, EFFECTIVE NO jQUERY

We're going to to be using a hidden checkbox.
This example includes one "on click - off click 'hover / active' state"

--

To make content itself clickable:

HTML

<input type="checkbox" id="activate-div">
  <label for="activate-div">
   <div class="my-div">
      //MY DIV CONTENT
   </div>
  </label>

CSS

#activate-div{display:none}    

.my-div{background-color:#FFF} 

#activate-div:checked ~ label 
.my-div{background-color:#000}



To make button change content:

HTML

<input type="checkbox" id="activate-div">
   <div class="my-div">
      //MY DIV CONTENT
   </div>

<label for="activate-div">
   //MY BUTTON STUFF
</label>

CSS

#activate-div{display:none}

.my-div{background-color:#FFF} 

#activate-div:checked + 
.my-div{background-color:#000}

Hope it helps!!

How to get current user, and how to use User class in MVC5?

Try something like:

var store = new UserStore<ApplicationUser>(new ApplicationDbContext());
var userManager = new UserManager<ApplicationUser>(store);
ApplicationUser user = userManager.FindByNameAsync(User.Identity.Name).Result;

Works with RTM.

Angular EXCEPTION: No provider for Http

I just add both these in my app.module.ts:

"import { HttpClientModule }    from '@angular/common/http'; 

&

import { HttpModule } from '@angular/http';"

Now its works fine.... And dont forget to add in the

@NgModule => Imports:[] array

"android.view.WindowManager$BadTokenException: Unable to add window" on buider.show()

I am creating Dialog in onCreate and using it with show and hide. For me the root cause was not dismissing onBackPressed, which was finishing the Home activity.

@Override
public void onBackPressed() {
new AlertDialog.Builder(this)
                .setTitle("Really Exit?")
                .setMessage("Are you sure you want to exit?")
                .setNegativeButton(android.R.string.no, null)
                .setPositiveButton(android.R.string.yes,
                        new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog,
                                    int which) {
                                Home.this.finish();
                                return;
                            }
                        }).create().show();

I was finishing the Home Activity onBackPressed without closing / dismissing my dialogs.

When I dismissed my dialogs the crash disappeared.

new AlertDialog.Builder(this)
                .setTitle("Really Exit?")
                .setMessage("Are you sure you want to exit?")
                .setNegativeButton(android.R.string.no, null)
                .setPositiveButton(android.R.string.yes,
                        new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog,
                                    int which) {
                                networkErrorDialog.dismiss() ;
                                homeLocationErrorDialog.dismiss() ;
                                currentLocationErrorDialog.dismiss() ;
                                Home.this.finish();
                                return;
                            }
                        }).create().show();

How to identify if a webpage is being loaded inside an iframe or directly into the browser window?

I actually used to check window.parent and it worked for me, but lately window is a cyclic object and always has a parent key, iframe or no iframe.

As the comments suggest hard comparing with window.parent works. Not sure if this will work if iframe is exactly the same webpage as parent.

window === window.parent;

SQL SERVER DATETIME FORMAT

In MS SQL Server you can do:

SET DATEFORMAT ymd

Java program to connect to Sql Server and running the sample query From Eclipse

Just Change the query like this:

SELECT TOP 1 * FROM [HumanResources].[Employee]

where Employee is your table name and HumanResources is your Schema name if I am not wrong.

Hope your problem will be resolved. :)

Error: Tablespace for table xxx exists. Please DISCARD the tablespace before IMPORT

For WAMP [Windows 7 Ultimate x64-bit] Users:

I agree with what DangerDave said and so I'm making an answer available for WAMP Users.

Note: First of all, you have to go to your ..\WAMP\Bin\MySQL\MySQL[Your MySQL Version]\Data folder.

Now, you'll see folders of all your databases

  • Double-click the folder of the database which has the offending table to open it
  • There shouldn't be a file [Your offending MySQL table name].frm, instead there should be a file [Your offending MySQL table name].ibd
  • Delete the [Your offending MySQL table name].ibd
  • Then, delete it from the Recycle Bin too
  • Then run your MySQL query on the database and you're done

Django 1.7 - "No migrations to apply" when run migrate after makemigrations

I had this same problem. Make sure the app's migrations folder is created (YOURAPPNAME/ migrations). Delete the folder and enter the commands:

python manage.py migrate --fake
python manage.py makemigrations <app_name>
python manage.py migrate --fake-initial

I inserted this lines in each class in models.py:

class Meta:
    app_label = '<app_name>'

This solved my problem.

Convert a string to datetime in PowerShell

ParseExact is told the format of the date it is expected to parse, not the format you wish to get out.

$invoice = '01-Jul-16'
[datetime]::parseexact($invoice, 'dd-MMM-yy', $null)

If you then wish to output a date string:

[datetime]::parseexact($invoice, 'dd-MMM-yy', $null).ToString('yyyy-MM-dd')

Chris

What is the minimum length of a valid international phone number?

The minimum length is 4 for Saint Helena (Format: +290 XXXX) and Niue (Format: +683 XXXX).

Storing and displaying unicode string (??????) using PHP and MySQL

Did you set proper charset in the HTML Head section?

<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">

or you can set content type in your php script using -

   header( 'Content-Type: text/html; charset=utf-8' ); 

There are already some discussions here on StackOverflow - please have a look

How to make MySQL handle UTF-8 properly setting utf8 with mysql through php

PHP/MySQL with encoding problems

So what i want to know is how can i directly store ???????? into my database and fetch it and display in my webpage using PHP.

I am not sure what you mean by "directly storing in the database" .. did you mean entering data using PhpMyAdmin or any other similar tool? If yes, I have tried using PhpMyAdmin to input unicode data, so it has worked fine for me - You could try inputting data using phpmyadmin and retrieve it using a php script to confirm. If you need to submit data via a Php script just set the NAMES and CHARACTER SET when you create mysql connection, before execute insert queries, and when you select data. Have a look at the above posts to find the syntax. Hope it helps.

** UPDATE ** Just fixed some typos etc

creating a table in ionic

This should probably be a comment, however, I don't have enough reputation to comment.

I suggest you really use the table (HTML) instead of ion-row and ion-col. Things will not look nice when one of the cell's content is too long.

One worse case looks like this:

| 10 | 20 | 30 | 40 |
| 1 | 2 | 3100 | 41 |

Higher fidelity example fork from @jpoveda

Add ArrayList to another ArrayList in java

Then you need a ArrayList of ArrayLists:

ArrayList<ArrayList<String>> nodes = new ArrayList<ArrayList<String>>();
ArrayList<String> nodeList = new ArrayList<String>();
nodes.add(nodeList);

Note that NodeList has been changed to nodeList. In Java Naming Conventions variables start with a lower case. Classes start with an upper case.

How to extract hours and minutes from a datetime.datetime object?

Don't know how you want to format it, but you can do:

print("Created at %s:%s" % (t1.hour, t1.minute))

for example.

AngularJS : When to use service instead of factory

Factory and Service are the most commonly used method. The only difference between them is that the Service method works better for objects that need inheritance hierarchy, while the Factory can produce JavaScript primitives and functions.

The Provider function is the core method and all the other ones are just syntactic sugar on it. You need it only if you are building a reusable piece of code that needs global configuration.

There are five methods to create services: Value, Factory, Service, Provider and Constant. You can learn more about this here angular service, this article explain all this methods with practical demo examples.

.

Can you run GUI applications in a Docker container?

The other solutions should work, but here is a solution for docker-compose.

To fix that error, you need to pass $DISPLAY and .X11-unix to docker, as well as grant the user who started docker access to xhost.

Within docker-compose.yml file:

version: '2'
services:
    node:
        build: .
        container_name: node
        environment:
            - DISPLAY
        volumes:
            - /tmp/.X11-unix:/tmp/.X11-unix

In terminal or script:

  • xhost +si:localuser:$USER
  • xhost +local:docker
  • export DISPLAY=$DISPLAY
  • docker-compose up

What are the proper permissions for an upload folder with PHP/Apache?

What is important is that the apache user and group should have minimum read access and in some cases execute access. For the rest you can give 0 access.

This is the most safe setting.

How to POST request using RestSharp

As of 2017 I post to a rest service and getting the results from it like that:

        var loginModel = new LoginModel();
        loginModel.DatabaseName = "TestDB";
        loginModel.UserGroupCode = "G1";
        loginModel.UserName = "test1";
        loginModel.Password = "123";

        var client = new RestClient(BaseUrl);

        var request = new RestRequest("/Connect?", Method.POST);
        request.RequestFormat = DataFormat.Json;
        request.AddBody(loginModel);

        var response = client.Execute(request);

        var obj = JObject.Parse(response.Content);

        LoginResult result = new LoginResult
        {
            Status = obj["Status"].ToString(),
            Authority = response.ResponseUri.Authority,
            SessionID = obj["SessionID"].ToString()
        };

Android How to adjust layout in Full Screen Mode when softkeyboard is visible

I just found a simple and reliable solution if you are using the system UI approach (https://developer.android.com/training/system-ui/immersive.html).

It works in the case when you are using View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN, e.g. if you are using CoordinatorLayout.

It won't work for WindowManager.LayoutParams.FLAG_FULLSCREEN (The one you can also set in theme with android:windowFullscreen), but you can achieve similar effect with SYSTEM_UI_FLAG_LAYOUT_STABLE (which "has the same visual effect" according to the docs) and this solution should work again.

getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_FULLSCREEN
                    | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION /* If you want to hide navigation */
                    | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | View.SYSTEM_UI_FLAG_LAYOUT_STABLE)

I've tested it on my device running Marshmallow.

The key is that soft keyboards are also one of the system windows (such as status bar and navigation bar), so the WindowInsets dispatched by system contains accurate and reliable information about it.

For the use case such as in DrawerLayout where we are trying to draw behind the status bar, We can create a layout that ignores only the top inset, and applies the bottom inset which accounts for the soft keyboard.

Here is my custom FrameLayout:

/**
 * Implements an effect similar to {@code android:fitsSystemWindows="true"} on Lollipop or higher,
 * except ignoring the top system window inset. {@code android:fitsSystemWindows="true"} does not
 * and should not be set on this layout.
 */
public class FitsSystemWindowsExceptTopFrameLayout extends FrameLayout {

    public FitsSystemWindowsExceptTopFrameLayout(Context context) {
        super(context);
    }

    public FitsSystemWindowsExceptTopFrameLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public FitsSystemWindowsExceptTopFrameLayout(Context context, AttributeSet attrs,
                                                 int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @RequiresApi(Build.VERSION_CODES.LOLLIPOP)
    public FitsSystemWindowsExceptTopFrameLayout(Context context, AttributeSet attrs,
                                                 int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    public WindowInsets onApplyWindowInsets(WindowInsets insets) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            setPadding(insets.getSystemWindowInsetLeft(), 0, insets.getSystemWindowInsetRight(),
                    insets.getSystemWindowInsetBottom());
            return insets.replaceSystemWindowInsets(0, insets.getSystemWindowInsetTop(), 0, 0);
        } else {
            return super.onApplyWindowInsets(insets);
        }
    }
}

And to use it:

<com.example.yourapplication.FitsSystemWindowsExceptTopFrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <!-- Your original layout here -->
</com.example.yourapplication.FitsSystemWindowsExceptTopFrameLayout>

This should theoretically work for any device without insane modification, much better than any hack that tries to take a random 1/3 or 1/4 of screen size as reference.

(It requires API 16+, but I'm using fullscreen only on Lollipop+ for drawing behind the status bar so it's the best solution in this case.)

jQuery-UI datepicker default date

If you want to update the highlighted day to a different day based on some server time, you can override the Date Picker code to allow for a new custom option named localToday or whatever you'd like to name it.

A small tweak to the selected answer in jQuery UI DatePicker change highlighted "today" date

// Get users 'today' date
var localToday = new Date();
localToday.setDate(tomorrow.getDate()+1); // tomorrow

// Pass the today date to datepicker
$( "#datepicker" ).datepicker({
    showButtonPanel: true,
    localToday: localToday    // This option determines the highlighted today date
});

I've overridden 2 datepicker methods to conditionally use a new setting for the "today" date instead of a new Date(). The new setting is called localToday.

Override $.datepicker._gotoToday and $.datepicker._generateHTML like this:

$.datepicker._gotoToday = function(id) {
    /* ... */
    var date = inst.settings.localToday || new Date()
    /* ... */
}

$.datepicker._generateHTML = function(inst) {
    /* ... */
    tempDate = inst.settings.localToday || new Date()
    /* ... */
}

Here's a demo which shows the full code and usage: http://jsfiddle.net/NAzz7/5/

How to go up a level in the src path of a URL in HTML?

Use ../:

background-image: url('../images/bg.png');

You can use that as often as you want, e.g. ../../images/ or even at different positions, e.g. ../images/../images/../images/ (same as ../images/ of course)

Usage of @see in JavaDoc?

A good example of a situation when @see can be useful would be implementing or overriding an interface/abstract class method. The declaration would have javadoc section detailing the method and the overridden/implemented method could use a @see tag, referring to the base one.

Related question: Writing proper javadoc with @see?

Java SE documentation: @see

UIView background color in Swift

Try This, It worked like a charm! for me,

The simplest way to add backgroundColor programmatically by using ColorLiteral.

You need to add the property ColorLiteral, Xcode will prompt you with a whole list of colors in which you can choose any color. The advantage of doing this is we use lesser code, add HEX values or RGB. You will also get the recently used colors from the storyboard.

Follow steps ,

1) Add below line of code in viewDidLoad() ,

self.view.backgroundColor = ColorLiteral

and clicked on enter button .

2) Display square box next to =

enter image description here

3) When Clicked on Square Box Xcode will prompt you with a whole list of colors which you can choose any colors also you can set HEX values or RGB

enter image description here

4) You can successfully set the colors .

enter image description here

Hope this will help some one to set backgroundColor in different ways.

Chosen Jquery Plugin - getting selected values

$("#select-id").chosen().val()

Get current domain

The only secure way of doing this

The only guaranteed secure method of retrieving the current domain is to store it in a secure location yourself.

Most frameworks take care of storing the domain for you, so you will want to consult the documentation for your particular framework. If you're not using a framework, consider storing the domain in one of the following places:

Secure methods of storing the domain Used By
A config file Joomla, Drupal/Symfony
The database WordPress
An environmental variable Laravel
A service registry Kubernetes DNS

The following work... but they're not secure

Hackers can make the following variables output whatever domain they want. This can lead to cache poisoning and barely noticeable phishing attacks.

$_SERVER['HTTP_HOST']

This gets the domain from the request headers which are open to manipulation by hackers. Same with:

$_SERVER['SERVER_NAME']

This one can be made better if the Apache setting usecanonicalname is turned off; in which case $_SERVER['SERVER_NAME'] will no longer be allowed to be populated with arbitrary values and will be secure. This is, however, non-default and not as common of a setup.

In popular systems

Below is how you can get the current domain in the following frameworks/systems:

WordPress

$urlparts = parse_url(home_url());
$domain = $urlparts['host'];

If you're constructing a URL in WordPress, just use home_url or site_url, or any of the other URL functions.

Laravel

request()->getHost()

The request()->getHost function is inherited from Symfony, and has been secure since the 2013 CVE-2013-4752 was patched.

Drupal

The installer does not yet take care of making this secure (issue #2404259). But in Drupal 8 there is documentation you can you can follow at Trusted Host Settings to secure your Drupal installation after which the following can be used:

\Drupal::request()->getHost();

Other frameworks

Feel free to edit this answer to include how to get the current domain in your favorite framework. When doing so, please include a link to the relevant source code or to anything else that would help me verify that the framework is doing things securely.


Addendum

Exploitation examples:

  1. Cache poisoning can happen if a botnet continuously requests a page using the wrong hosts header. The resulting HTML will then include links to the attackers website where they can phish your users. At first the malicious links will only be sent back to the hacker, but if the hacker does enough requests, the malicious version of the page will end up in your cache where it will be distributed to other users.

  2. A phishing attack can happen if you store links in the database based on the hosts header. For example, let say you store the absolute URL to a user's profiles on a forum. By using the wrong header, a hacker could get anyone who clicks on their profile link to be sent a phishing site.

  3. Password reset poisoning can happen if a hacker uses a malicious hosts header when filling out the password reset form for a different user. That user will then get an email containing a password reset link that leads to a phishing site. Another more complex form of this skips the user having to do anything by getting the email to bounce and resend to one of the hacker's SMTP servers (for example CVE-2017-8295.)

  4. Here are some more malicious examples

Additional Caveats and Notes:

  • When usecanonicalname is turned off the $_SERVER['SERVER_NAME'] is populated with the same header $_SERVER['HTTP_HOST'] would have used anyways (plus the port). This is Apache's default setup. If you or devops turns this on then you're okay -- ish -- but do you really want to rely on a separate team, or yourself three years in the future, to keep what would appear to be a minor configuration at a non-default value? Even though this makes things secure, I would caution against relying on this setup.
  • Redhat, however, does turn usecanonical on by default [source].
  • If serverAlias is used in the virtual hosts entry, and the aliased domain is requested, $_SERVER['SERVER_NAME'] will not return the current domain, but will return the value of the serverName directive.
  • If the serverName cannot be resolved, the operating system's hostname command is used in its place [source].
  • If the host header is left out, the server will behave as if usecanonical was on [source].
  • Lastly, I just tried exploiting this on my local server, and was unable to spoof the hosts header. I'm not sure if there was an update to Apache that addressed this, or if I was just doing something wrong. Regardless, this header would still be exploitable in environments where virtual hosts are not being used.

Little Rant:

     This question received hundreds of thousands of views without a single mention of the security problems at hand! It shouldn't be this way, but just because a Stack Overflow answer is popular, that doesn't mean it is secure.



Detect if page has finished loading

Is this what you had in mind?

$("document").ready( function() {
    // do your stuff
}

VBA to copy a file from one directory to another

This method is even easier if you're ok with fewer options:

FileCopy source, destination

Python3: ImportError: No module named '_ctypes' when using Value from module multiprocessing

If you are doing something nobody here will listen you about because "you're doing it the wrong way", but you have to do it "the wrong way" for reasons too asinine to explain and also beyond your ability to control, you can try this:

Get libffi and install it into your user install area the usual way.

git clone https://github.com/libffi/libffi.git
cd libffi
./configure --prefix=path/to/your/install/root
make
make install

Then go back to your Python 3 source and find this part of the code in setup.py at the top level of the python source directory

        ffi_inc = [sysconfig.get_config_var("LIBFFI_INCLUDEDIR")]
        if not ffi_inc or ffi_inc[0] == '':
            ffi_inc = find_file('ffi.h', [], inc_dirs)
        if ffi_inc is not None:
            ffi_h = ffi_inc[0] + '/ffi.h'
            if not os.path.exists(ffi_h):
                ffi_inc = None
                print('Header file {} does not exist'.format(ffi_h))
        ffi_lib = None
        if ffi_inc is not None:
            for lib_name in ('ffi', 'ffi_pic'):
                if (self.compiler.find_library_file(lib_dirs, lib_name)):
                    ffi_lib = lib_name
                    break

        ffi_lib="ffi"  # --- AND INSERT THIS LINE HERE THAT DOES NOT APPEAR ---
        if ffi_inc and ffi_lib:
            ext.include_dirs.extend(ffi_inc)
            ext.libraries.append(ffi_lib)
            self.use_system_libffi = True

and add the line I have marked above with the comment. Why it is necessary, and why there is no way to get configure to respect '--without-system-ffi` on Linux platforms, perhaps I will find out why that is "unsupported" in the next couple of hours, but everything has worked ever since. Otherwise, best of luck... YMMV.

WHAT IT DOES: just overrides the logic there and causes the compiler linking command to add "-lffi" which is all that it really needs. If you have the library user-installed, it is probably detecting the headers fine as long as your PKG_CONFIG_PATH includes path/to/your/install/root/lib/pkgconfig.

Read file content from S3 bucket with boto3

Using the client instead of resource:

s3 = boto3.client('s3')
bucket='bucket_name'
result = s3.list_objects(Bucket = bucket, Prefix='/something/')
for o in result.get('Contents'):
    data = s3.get_object(Bucket=bucket, Key=o.get('Key'))
    contents = data['Body'].read()
    print(contents)

Iterating through map in template

Check the Variables section in the Go template docs. A range may declare two variables, separated by a comma. The following should work:

{{ range $key, $value := . }}
   <li><strong>{{ $key }}</strong>: {{ $value }}</li>
{{ end }}

Send Email Intent

in Kotlin if anyone is looking

val emailArrray:Array<String> = arrayOf("[email protected]")
val intent = Intent(Intent.ACTION_SENDTO)
intent.data = Uri.parse("mailto:") // only email apps should handle this
intent.putExtra(Intent.EXTRA_EMAIL, emailArrray)
intent.putExtra(Intent.EXTRA_SUBJECT, "Inquire about travel agent")
if (intent.resolveActivity(getPackageManager()) != null) {
    startActivity(intent);
}

Make Bootstrap 3 Tabs Responsive

I have created a directive in agularJS supported with ng-bootStrap components

https://angular-ui.github.io/bootstrap/#!#tabs

here I share the code that I implemented

[https://jsfiddle.net/k1r02/u6gpv4dc/][1]

  [1]: https://jsfiddle.net/k1r02/u6gpv4dc/

How to include NA in ifelse?

You can't really compare NA with another value, so using == would not work. Consider the following:

NA == NA
# [1] NA

You can just change your comparison from == to %in%:

ifelse(is.na(test$time) | test$type %in% "A", NA, "1")
# [1] NA  "1" NA  "1"

Regarding your other question,

I could get this to work with my existing code if I could somehow change the result of is.na(test$type) to return FALSE instead of TRUE, but I'm not sure how to do that.

just use ! to negate the results:

!is.na(test$time)
# [1]  TRUE  TRUE FALSE  TRUE

What is Teredo Tunneling Pseudo-Interface?

Unless you have some kind of really weird problem, keep it. The number of IPv6 sites is very small, but there are some and it will let you get to them even if you're at an IPv4 only location.

If it is causing you a problem, it's best to fix it. I've seen a number of people recommending removing it to solve problems. However, they're not actually solving the root cause of the issue. In all the cases I've seen, removing Teredo just happens to cause a side-effect that fixes their problem... :)

StringLength vs MaxLength attributes ASP.NET MVC with Entity Framework EF Code First

Some quick but extremely useful additional information that I just learned from another post, but can't seem to find the documentation for (if anyone can share a link to it on MSDN that would be amazing):

The validation messages associated with these attributes will actually replace placeholders associated with the attributes. For example:

[MaxLength(100, "{0} can have a max of {1} characters")]
public string Address { get; set; }

Will output the following if it is over the character limit: "Address can have a max of 100 characters"

The placeholders I am aware of are:

  • {0} = Property Name
  • {1} = Max Length
  • {2} = Min Length

Much thanks to bloudraak for initially pointing this out.

Random float number generation

I wasn't satisfied by any of the answers so far so I wrote a new random float function. It makes bitwise assumptions about the float data type. It still needs a rand() function with at least 15 random bits.

//Returns a random number in the range [0.0f, 1.0f).  Every
//bit of the mantissa is randomized.
float rnd(void){
  //Generate a random number in the range [0.5f, 1.0f).
  unsigned int ret = 0x3F000000 | (0x7FFFFF & ((rand() << 8) ^ rand()));
  unsigned short coinFlips;

  //If the coin is tails, return the number, otherwise
  //divide the random number by two by decrementing the
  //exponent and keep going. The exponent starts at 63.
  //Each loop represents 15 random bits, a.k.a. 'coin flips'.
  #define RND_INNER_LOOP() \
    if( coinFlips & 1 ) break; \
    coinFlips >>= 1; \
    ret -= 0x800000
  for(;;){
    coinFlips = rand();
    RND_INNER_LOOP(); RND_INNER_LOOP(); RND_INNER_LOOP();
    //At this point, the exponent is 60, 45, 30, 15, or 0.
    //If the exponent is 0, then the number equals 0.0f.
    if( ! (ret & 0x3F800000) ) return 0.0f;
    RND_INNER_LOOP(); RND_INNER_LOOP(); RND_INNER_LOOP();
    RND_INNER_LOOP(); RND_INNER_LOOP(); RND_INNER_LOOP();
    RND_INNER_LOOP(); RND_INNER_LOOP(); RND_INNER_LOOP();
    RND_INNER_LOOP(); RND_INNER_LOOP(); RND_INNER_LOOP();
  }
  return *((float *)(&ret));
}

Get element from within an iFrame

Below code will help you to find out iframe data.

let iframe = document.getElementById('frameId');
let innerDoc = iframe.contentDocument || iframe.contentWindow.document;

What is the difference between up-casting and down-casting with respect to class variable

Better try this method for upcasting, it's easy to understand:

/* upcasting problem */
class Animal
{ 
    public void callme()
    {
        System.out.println("In callme of Animal");
    }
}

class Dog extends Animal 
{ 
    public void callme()
    {
        System.out.println("In callme of Dog");
    }

    public void callme2()
    {
        System.out.println("In callme2 of Dog");
    }
}

public class Useanimlas 
{
    public static void main (String [] args) 
    {
        Animal animal = new Animal ();
        Dog dog = new Dog();
        Animal ref;
        ref = animal;
        ref.callme();
        ref = dog;
        ref.callme();
    }
}

How can I get the number of days between 2 dates in Oracle 11g?

  • Full days between end of month and start of today, including the last day of the month:

    SELECT LAST_DAY (TRUNC(SysDate)) - TRUNC(SysDate) + 1 FROM dual
    
  • Days between using exact time:

    SELECT SysDate - TO_DATE('2018-01-01','YYYY-MM-DD') FROM dual
    

How to Replace dot (.) in a string in Java

You need two backslashes before the dot, one to escape the slash so it gets through, and the other to escape the dot so it becomes literal. Forward slashes and asterisk are treated literal.

str=xpath.replaceAll("\\.", "/*/");          //replaces a literal . with /*/

http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#replaceAll(java.lang.String,%20java.lang.String)

Correct path for img on React.js

You're using a relative url, which is relative to the current url, not the file system. You could resolve this by using absolute urls

<img src ="http://localhost:3000/details/img/myImage.png" />

But that's not great for when you deploy to www.my-domain.bike, or any other site. Better would be to use a url relative to the root directory of the site

<img src="/details/img/myImage.png" />

How to urlencode data for curl command?

Direct link to awk version : http://www.shelldorado.com/scripts/cmds/urlencode
I used it for years and it works like a charm

:
##########################################################################
# Title      :  urlencode - encode URL data
# Author     :  Heiner Steven ([email protected])
# Date       :  2000-03-15
# Requires   :  awk
# Categories :  File Conversion, WWW, CGI
# SCCS-Id.   :  @(#) urlencode  1.4 06/10/29
##########################################################################
# Description
#   Encode data according to
#       RFC 1738: "Uniform Resource Locators (URL)" and
#       RFC 1866: "Hypertext Markup Language - 2.0" (HTML)
#
#   This encoding is used i.e. for the MIME type
#   "application/x-www-form-urlencoded"
#
# Notes
#    o  The default behaviour is not to encode the line endings. This
#   may not be what was intended, because the result will be
#   multiple lines of output (which cannot be used in an URL or a
#   HTTP "POST" request). If the desired output should be one
#   line, use the "-l" option.
#
#    o  The "-l" option assumes, that the end-of-line is denoted by
#   the character LF (ASCII 10). This is not true for Windows or
#   Mac systems, where the end of a line is denoted by the two
#   characters CR LF (ASCII 13 10).
#   We use this for symmetry; data processed in the following way:
#       cat | urlencode -l | urldecode -l
#   should (and will) result in the original data
#
#    o  Large lines (or binary files) will break many AWK
#       implementations. If you get the message
#       awk: record `...' too long
#        record number xxx
#   consider using GNU AWK (gawk).
#
#    o  urlencode will always terminate it's output with an EOL
#       character
#
# Thanks to Stefan Brozinski for pointing out a bug related to non-standard
# locales.
#
# See also
#   urldecode
##########################################################################

PN=`basename "$0"`          # Program name
VER='1.4'

: ${AWK=awk}

Usage () {
    echo >&2 "$PN - encode URL data, $VER
usage: $PN [-l] [file ...]
    -l:  encode line endings (result will be one line of output)

The default is to encode each input line on its own."
    exit 1
}

Msg () {
    for MsgLine
    do echo "$PN: $MsgLine" >&2
    done
}

Fatal () { Msg "$@"; exit 1; }

set -- `getopt hl "$@" 2>/dev/null` || Usage
[ $# -lt 1 ] && Usage           # "getopt" detected an error

EncodeEOL=no
while [ $# -gt 0 ]
do
    case "$1" in
        -l) EncodeEOL=yes;;
    --) shift; break;;
    -h) Usage;;
    -*) Usage;;
    *)  break;;         # First file name
    esac
    shift
done

LANG=C  export LANG
$AWK '
    BEGIN {
    # We assume an awk implementation that is just plain dumb.
    # We will convert an character to its ASCII value with the
    # table ord[], and produce two-digit hexadecimal output
    # without the printf("%02X") feature.

    EOL = "%0A"     # "end of line" string (encoded)
    split ("1 2 3 4 5 6 7 8 9 A B C D E F", hextab, " ")
    hextab [0] = 0
    for ( i=1; i<=255; ++i ) ord [ sprintf ("%c", i) "" ] = i + 0
    if ("'"$EncodeEOL"'" == "yes") EncodeEOL = 1; else EncodeEOL = 0
    }
    {
    encoded = ""
    for ( i=1; i<=length ($0); ++i ) {
        c = substr ($0, i, 1)
        if ( c ~ /[a-zA-Z0-9.-]/ ) {
        encoded = encoded c     # safe character
        } else if ( c == " " ) {
        encoded = encoded "+"   # special handling
        } else {
        # unsafe character, encode it as a two-digit hex-number
        lo = ord [c] % 16
        hi = int (ord [c] / 16);
        encoded = encoded "%" hextab [hi] hextab [lo]
        }
    }
    if ( EncodeEOL ) {
        printf ("%s", encoded EOL)
    } else {
        print encoded
    }
    }
    END {
        #if ( EncodeEOL ) print ""
    }
' "$@"

Finding all possible combinations of numbers to reach a given sum

function solve(n){
    let DP = [];

     DP[0] = DP[1] = DP[2] = 1;
     DP[3] = 2;

    for (let i = 4; i <= n; i++) {
      DP[i] = DP[i-1] + DP[i-3] + DP[i-4];
    }
    return DP[n]
}

console.log(solve(5))

This is a Dynamic Solution for JS to tell how many ways anyone can get the certain sum. This can be the right solution if you think about time and space complexity.

How can I check the extension of a file?

#!/usr/bin/python

import shutil, os

source = ['test_sound.flac','ts.mp3']

for files in source:
  fileName,fileExtension = os.path.splitext(files)

  if fileExtension==".flac" :
    print 'This file is flac file %s' %files
  elif  fileExtension==".mp3":
    print 'This file is mp3 file %s' %files
  else:
    print 'Format is not valid'

source command not found in sh shell

$ls -l `which sh`
/bin/sh -> dash

$sudo dpkg-reconfigure dash #Select "no" when you're asked
[...]

$ls -l `which sh`
/bin/sh -> bash

Then it will be OK

Difference between subprocess.Popen and os.system

subprocess.Popen() is strict super-set of os.system().

Use and meaning of "in" in an if statement?

You are used to using the javascript if, and I assume you know how it works.

in is a Pythonic way of implementing iteration. It's supposed to be easier for non-programmatic thinkers to adopt, but that can sometimes make it harder for programmatic thinkers, ironically.

When you say if x in y, you are literally saying:

"if x is in y", which assumes that y has an index. In that if statement then, each object at each index in y is checked against the condition.

Similarly,

for x in y

iterates through x's in y, where y is that indexable set of items.

Think of the if situation this way (pseudo-code):

for i in next:
    if i == "0" || i == "1":
        how_much = int(next)

It takes care of the iteration over next for you.

Happy coding!

Run react-native application on iOS device directly from command line?

First install the required library globally on your computer:

npm install -g ios-deploy

Go to your settings on your iPhone to find the name of the device.

Then provide that below like:

react-native run-ios --device "______\'s iPhone"

Sometimes this will fail and output a message like this:

Found Xcode project ________.xcodeproj
Could not find device with the name: "_______'s iPhone".
Choose one of the following:
______’s iPhone Udid: _________

That udid is used like this:

react-native run-ios --udid 0412e2c230a14e23451699

Optionally you may use:

react-native run-ios --udid 0412e2c230a14e23451699 -- configuration Release

Setting a minimum/maximum character count for any character using a regular expression

It's usually the metacharacter . when not inside a character class.

So use ^.{1,35}$. However, dot does not include newlines unless the dot-all modifier is applied against it.

You can use ^[\S\s]{1,35}$ without any modifiers, and this includes newlines as well.

Converting char* to float or double

printf("price: %d, %f",temp,ftemp); 
              ^^^

This is your problem. Since the arguments are type double and float, you should be using %f for both (since printf is a variadic function, ftemp will be promoted to double).

%d expects the corresponding argument to be type int, not double.

Variadic functions like printf don't really know the types of the arguments in the variable argument list; you have to tell it with the conversion specifier. Since you told printf that the first argument is supposed to be an int, printf will take the next sizeof (int) bytes from the argument list and interpret it as an integer value; hence the first garbage number.

Now, it's almost guaranteed that sizeof (int) < sizeof (double), so when printf takes the next sizeof (double) bytes from the argument list, it's probably starting with the middle byte of temp, rather than the first byte of ftemp; hence the second garbage number.

Use %f for both.

Cannot execute RUN mkdir in a Dockerfile

The problem is that /var/www doesn't exist either, and mkdir isn't recursive by default -- it expects the immediate parent directory to exist.

Use:

mkdir -p /var/www/app

...or install a package that creates a /var/www prior to reaching this point in your Dockerfile.

How to get current time in python and break up into year, month, day, hour, minute?

Here's a one-liner that comes in just under the 80 char line max.

import time
year, month, day, hour, min = map(int, time.strftime("%Y %m %d %H %M").split())

Regular expression for only characters a-z, A-Z

Piggybacking on what the other answers say, since you don't know how to do them at all, here's an example of how you might do it in JavaScript:

var charactersOnly = "This contains only characters";
var nonCharacters = "This has _@#*($()*@#$(*@%^_(#@!$ non-characters";

if (charactersOnly.search(/[^a-zA-Z]+/) === -1) {
  alert("Only characters");
}

if (nonCharacters.search(/[^a-zA-Z]+/)) {
  alert("There are non characters.");
}

The / starting and ending the regular expression signify that it's a regular expression. The search function takes both strings and regexes, so the / are necessary to specify a regex.

From the MDN Docs, the function returns -1 if there is no match.

Also note: that this works for only a-z, A-Z. If there are spaces, it will fail.

Insert some string into given string at given index in Python

There are several ways to do this:

One way is to use slicing:

>>> a="line=Name Age Group Class Profession"
>>> b=a.split()
>>> b[2:2]=[b[2]]*3
>>> b
['line=Name', 'Age', 'Group', 'Group', 'Group', 'Group', 'Class', 'Profession']
>>> a=" ".join(b)
>>> a
'line=Name Age Group Group Group Group Class Profession'

Another would be to use regular expressions:

>>> import re
>>> a=re.sub(r"(\S+\s+\S+\s+)(\S+\s+)(.*)", r"\1\2\2\2\2\3", a)
>>> a
'line=Name Age Group Group Group Group Class Profession'

Min/Max-value validators in asp.net mvc

I don't think min/max validations attribute exist. I would use something like

[Range(1, Int32.MaxValue)]

for minimum value 1 and

[Range(Int32.MinValue, 10)]

for maximum value 10

Read data from SqlDataReader

In the simplest terms, if your query returns column_name and it holds a string:

while (rdr.Read())
{
    string yourString = rdr.getString("column_name")
}

Axios Delete request with body and headers?

To send an HTTP DELETE with some headers via axios I've done this:

  const deleteUrl = "http//foo.bar.baz";
  const httpReqHeaders = {
    'Authorization': token,
    'Content-Type': 'application/json'
  };
  // check the structure here: https://github.com/axios/axios#request-config
  const axiosConfigObject = {headers: httpReqHeaders}; 

  axios.delete(deleteUrl, axiosConfigObject);

The axios syntax for different HTTP verbs (GET, POST, PUT, DELETE) is tricky because sometimes the 2nd parameter is supposed to be the HTTP body, some other times (when it might not be needed) you just pass the headers as the 2nd parameter.

However let's say you need to send an HTTP POST request without an HTTP body, then you need to pass undefined as the 2nd parameter.

Bare in mind that according to the definition of the configuration object (https://github.com/axios/axios#request-config) you can still pass an HTTP body in the HTTP call via the data field when calling axios.delete, however for the HTTP DELETE verb it will be ignored.

This confusion between the 2nd parameter being sometimes the HTTP body and some other time the whole config object for axios is due to how the HTTP rules have been implemented. Sometimes an HTTP body is not needed for an HTTP call to be considered valid.

Remove last characters from a string in C#. An elegant way?

You can actually just use the Remove overload that takes one parameter:

str = str.Remove(str.Length - 3);

However, if you're trying to avoid hard coding the length, you can use:

str = str.Remove(str.IndexOf(','));

JAXB: How to ignore namespace during unmarshalling XML document?

Another way to add a default namespace to an XML Document before feeding it to JAXB is to use JDom:

  1. Parse XML to a Document
  2. Iterate through and set namespace on all Elements
  3. Unmarshall using a JDOMSource

Like this:

public class XMLObjectFactory {
    private static Namespace DEFAULT_NS = Namespace.getNamespace("http://tempuri.org/");

    public static Object createObject(InputStream in) {
        try {
            SAXBuilder sb = new SAXBuilder(false);
            Document doc = sb.build(in);
            setNamespace(doc.getRootElement(), DEFAULT_NS, true);
            Source src = new JDOMSource(doc);
            JAXBContext context = JAXBContext.newInstance("org.tempuri");
            Unmarshaller unmarshaller = context.createUnmarshaller();
            JAXBElement root = unmarshaller.unmarshal(src);
            return root.getValue();
        } catch (Exception e) {
            throw new RuntimeException("Failed to create Object", e);
        }
    }

    private static void setNamespace(Element elem, Namespace ns, boolean recurse) {
        elem.setNamespace(ns);
        if (recurse) {
            for (Object o : elem.getChildren()) {
                setNamespace((Element) o, ns, recurse);
            }
        }
    }

import sun.misc.BASE64Encoder results in error compiled in Eclipse

That error is caused by your Eclipse configuration. You can reduce it to a warning. Better still, use a Base64 encoder that isn't part of a non-public API. Apache Commons has one, or when you're already on Java 1.8, then use java.util.Base64.

How can I stop Chrome from going into debug mode?

If you were unfamiliar with the tools, it was likely that at some point while in the debugger you toggled a setting that was causing the debugger to stop the application.

I suggest you "Disable all break points":

Enter image description here

Source:

https://javascript.info/debugging-chrome

Trying to load local JSON file to show data in a html page using JQuery

As the jQuery API says: "Load JSON-encoded data from the server using a GET HTTP request."

http://api.jquery.com/jQuery.getJSON/

So you cannot load a local file with that function. But as you browse the web then you will see that loading a file from filesystem is really difficult in javascript as the following thread says:

Local file access with javascript

Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured

For me the resource folder was getting excluded on a maven update/build. I went to Build Path>Source and found that src/main/resources have "Excluded **". I removed that entry (Clicked on Excluded **>Remove>Apply and Close).

Then it worked fine.

enter image description here

Removing specific rows from a dataframe

This boils down to two distinct steps:

  1. Figure out when your condition is true, and hence compute a vector of booleans, or, as I prefer, their indices by wrapping it into which()
  2. Create an updated data.frame by excluding the indices from the previous step.

Here is an example:

R> set.seed(42)
R> DF <- data.frame(sub=rep(1:4, each=4), day=sample(1:4, 16, replace=TRUE))
R> DF
   sub day
1    1   4
2    1   4
3    1   2
4    1   4
5    2   3
6    2   3
7    2   3
8    2   1
9    3   3
10   3   3
11   3   2
12   3   3
13   4   4
14   4   2
15   4   2
16   4   4
R> ind <- which(with( DF, sub==2 & day==3 ))
R> ind
[1] 5 6 7
R> DF <- DF[ -ind, ]
R> table(DF)
   day
sub 1 2 3 4
  1 0 1 0 3
  2 1 0 0 0
  3 0 1 3 0
  4 0 2 0 2
R> 

And we see that sub==2 has only one entry remaining with day==1.

Edit The compound condition can be done with an 'or' as follows:

ind <- which(with( DF, (sub==1 & day==2) | (sub=3 & day=4) ))

and here is a new full example

R> set.seed(1)
R> DF <- data.frame(sub=rep(1:4, each=5), day=sample(1:4, 20, replace=TRUE))
R> table(DF)
   day
sub 1 2 3 4
  1 1 2 1 1
  2 1 0 2 2
  3 2 1 1 1
  4 0 2 1 2
R> ind <- which(with( DF, (sub==1 & day==2) | (sub==3 & day==4) ))
R> ind
[1]  1  2 15
R> DF <- DF[-ind, ]
R> table(DF)
   day
sub 1 2 3 4
  1 1 0 1 1
  2 1 0 2 2
  3 2 1 1 0
  4 0 2 1 2
R> 

Put a Delay in Javascript

Use a AJAX function which will call a php page synchronously and then in that page you can put the php usleep() function which will act as a delay.

function delay(t){

var xmlhttp;

if (window.XMLHttpRequest)

{// code for IE7+, Firefox, Chrome, Opera, Safari

xmlhttp=new XMLHttpRequest();

}

else

{// code for IE6, IE5

xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");

}

xmlhttp.open("POST","http://www.hklabs.org/files/delay.php?time="+t,false);

//This will call the page named delay.php and the response will be sent to a division with ID as "response"

xmlhttp.send();

document.getElementById("response").innerHTML=xmlhttp.responseText;

}

http://www.hklabs.org/articles/put-delay-in-javascript

How do you enable mod_rewrite on any OS?

network solutions offers the advice to put a php.ini in the cgi-bin to enable mod_rewrite

How do I convert a float to an int in Objective C?

I'm pretty sure C-style casting syntax works in Objective C, so try that, too:

int myInt = (int) myFloat;

It might silence a compiler warning, at least.

Remove specific characters from a string in Python

In Python 3.5

e.g.,

os.rename(file_name, file_name.translate({ord(c): None for c in '0123456789'}))

To remove all the number from the string

How do I improve ASP.NET MVC application performance?

Also if you use NHibernate you can turn on and setup second level cache for queries and add to queries scope and timeout. And there is kick ass profiler for EF, L2S and NHibernate - http://hibernatingrhinos.com/products/UberProf. It will help to tune your queries.

How to query SOLR for empty fields?

If you are using SolrSharp, it does not support negative queries.

You need to change QueryParameter.cs (Create a new parameter)

private bool _negativeQuery = false;

public QueryParameter(string field, string value, ParameterJoin parameterJoin = ParameterJoin.AND, bool negativeQuery = false)
{
    this._field = field;
    this._value = value.Trim();
    this._parameterJoin = parameterJoin;
    this._negativeQuery = negativeQuery;
}

public bool NegativeQuery
{
    get { return _negativeQuery; }
    set { _negativeQuery = value; }
}

And in QueryParameterCollection.cs class, the ToString() override, looks if the Negative parameter is true

arQ[x] = (qp.NegativeQuery ? "-(" : "(") + qp.ToString() + ")" + (qp.Boost != 1 ? "^" + qp.Boost.ToString() : "");

When you call the parameter creator, if it's a negative value. Simple change the propertie

List<QueryParameter> QueryParameters = new List<QueryParameter>();
QueryParameters.Add(new QueryParameter("PartnerList", "[* TO *]", ParameterJoin.AND, true));

How to change port for jenkins window service when 8080 is being used

Restart Jenkins service

Just restart the Jenkins service after you changed the port in jenkins.xml.

  1. Press Win + R
  2. Type "services.msc"
  3. Right click on the "Jenkins" line > Restart

    Restart Jenkins

  4. Type http://localhost:8081/ in your browser to test the change.

Ruby, Difference between exec, system and %x() or Backticks

system

The system method calls a system program. You have to provide the command as a string argument to this method. For example:

>> system("date")
Wed Sep 4 22:03:44 CEST 2013
=> true

The invoked program will use the current STDIN, STDOUT and STDERR objects of your Ruby program. In fact, the actual return value is either true, false or nil. In the example the date was printed through the IO object of STDIN. The method will return true if the process exited with a zero status, false if the process exited with a non-zero status and nil if the execution failed.

As of Ruby 2.6, passing exception: true will raise an exception instead of returning false or nil:

>> system('invalid')
=> nil

>> system('invalid', exception: true)
Traceback (most recent call last):
...
Errno::ENOENT (No such file or directory - invalid)

Another side effect is that the global variable $? is set to a Process::Status object. This object will contain information about the call itself, including the process identifier (PID) of the invoked process and the exit status.

>> system("date")
Wed Sep 4 22:11:02 CEST 2013
=> true
>> $?
=> #<Process::Status: pid 15470 exit 0>

Backticks

Backticks (``) call a system program and return its output. As opposed to the first approach, the command is not provided through a string, but by putting it inside a backticks pair.

>> `date`
=> Wed Sep 4 22:22:51 CEST 2013   

The global variable $? is set through the backticks, too. With backticks you can also make use string interpolation.

%x()

Using %x is an alternative to the backticks style. It will return the output, too. Like its relatives %w and %q (among others), any delimiter will suffice as long as bracket-style delimiters match. This means %x(date), %x{date} and %x-date- are all synonyms. Like backticks %x can make use of string interpolation.

exec

By using Kernel#exec the current process (your Ruby script) is replaced with the process invoked through exec. The method can take a string as argument. In this case the string will be subject to shell expansion. When using more than one argument, then the first one is used to execute a program and the following are provided as arguments to the program to be invoked.

Open3.popen3

Sometimes the required information is written to standard input or standard error and you need to get control over those as well. Here Open3.popen3 comes in handy:

require 'open3'

Open3.popen3("curl http://example.com") do |stdin, stdout, stderr, thread|
   pid = thread.pid
   puts stdout.read.chomp
end

How to rotate a 3D object on axis three.js?

In Three.js R66, this is what I use (CoffeeScript version):

THREE.Object3D.prototype.rotateAroundWorldAxis = (axis, radians) ->
  rotWorldMatrix = new THREE.Matrix4()
  rotWorldMatrix.makeRotationAxis axis.normalize(), radians
  rotWorldMatrix.multiply this.matrix
  this.matrix = rotWorldMatrix
  this.rotation.setFromRotationMatrix this.matrix

twitter bootstrap 3.0 typeahead ajax example

<input id="typeahead-input" type="text" data-provide="typeahead" />

<script type="text/javascript">
var data = ["Aamir", "Amol", "Ayesh", "Sameera", "Sumera", "Kajol", "Kamal",
  "Akash", "Robin", "Roshan", "Aryan"];
$(function() {
    $('#typeahead-input').typeahead({
        source: function (query, process) {
               process(data);
            });
        }
    });
});
</script>

XML Document to String

First you need to get rid of all newline characters in all your text nodes. Then you can use an identity transform to output your DOM tree. Look at the javadoc for TransformerFactory#newTransformer().