Programs & Examples On #Pycairo

A set of Python bindings for the cairo graphics library.

Convert SVG to PNG in Python

SVG scaling and PNG rendering

Using pycairo and librsvg I was able to achieve SVG scaling and rendering to a bitmap. Assuming your SVG is not exactly 256x256 pixels, the desired output, you can read in the SVG to a Cairo context using rsvg and then scale it and write to a PNG.

main.py

import cairo
import rsvg

width = 256
height = 256

svg = rsvg.Handle('cool.svg')
unscaled_width = svg.props.width
unscaled_height = svg.props.height

svg_surface = cairo.SVGSurface(None, width, height)
svg_context = cairo.Context(svg_surface)
svg_context.save()
svg_context.scale(width/unscaled_width, height/unscaled_height)
svg.render_cairo(svg_context)
svg_context.restore()

svg_surface.write_to_png('cool.png')

RSVG C binding

From the Cario website with some minor modification. Also a good example of how to call a C-library from Python

from ctypes import CDLL, POINTER, Structure, byref, util
from ctypes import c_bool, c_byte, c_void_p, c_int, c_double, c_uint32, c_char_p


class _PycairoContext(Structure):
    _fields_ = [("PyObject_HEAD", c_byte * object.__basicsize__),
                ("ctx", c_void_p),
                ("base", c_void_p)]


class _RsvgProps(Structure):
    _fields_ = [("width", c_int), ("height", c_int),
                ("em", c_double), ("ex", c_double)]


class _GError(Structure):
    _fields_ = [("domain", c_uint32), ("code", c_int), ("message", c_char_p)]


def _load_rsvg(rsvg_lib_path=None, gobject_lib_path=None):
    if rsvg_lib_path is None:
        rsvg_lib_path = util.find_library('rsvg-2')
    if gobject_lib_path is None:
        gobject_lib_path = util.find_library('gobject-2.0')
    l = CDLL(rsvg_lib_path)
    g = CDLL(gobject_lib_path)
    g.g_type_init()

    l.rsvg_handle_new_from_file.argtypes = [c_char_p, POINTER(POINTER(_GError))]
    l.rsvg_handle_new_from_file.restype = c_void_p
    l.rsvg_handle_render_cairo.argtypes = [c_void_p, c_void_p]
    l.rsvg_handle_render_cairo.restype = c_bool
    l.rsvg_handle_get_dimensions.argtypes = [c_void_p, POINTER(_RsvgProps)]

    return l


_librsvg = _load_rsvg()


class Handle(object):
    def __init__(self, path):
        lib = _librsvg
        err = POINTER(_GError)()
        self.handle = lib.rsvg_handle_new_from_file(path.encode(), byref(err))
        if self.handle is None:
            gerr = err.contents
            raise Exception(gerr.message)
        self.props = _RsvgProps()
        lib.rsvg_handle_get_dimensions(self.handle, byref(self.props))

    def get_dimension_data(self):
        svgDim = self.RsvgDimensionData()
        _librsvg.rsvg_handle_get_dimensions(self.handle, byref(svgDim))
        return (svgDim.width, svgDim.height)

    def render_cairo(self, ctx):
        """Returns True is drawing succeeded."""
        z = _PycairoContext.from_address(id(ctx))
        return _librsvg.rsvg_handle_render_cairo(self.handle, z.ctx)

how to get param in method post spring mvc?

When I want to get all the POST params I am using the code below,

@RequestMapping(value = "/", method = RequestMethod.POST)
public ViewForResponseClass update(@RequestBody AClass anObject) {
    // Source..
}

I am using the @RequestBody annotation for post/put/delete http requests instead of the @RequestParam which reads the GET parameters.

java.lang.ClassNotFoundException: com.sun.jersey.spi.container.servlet.ServletContainer

A simple workaround is , check whether you have dependencies or libs in deployment assembly of eclipse.probably if you are using tomcat , the server might not have identified the libs we are using . in that case specify it explicitly in deployment assembly.

Checking whether a variable is an integer or not

You can also use str.isdigit. Try looking up help(str.isdigit)

def is_digit(str):
      return str.isdigit()

Best way to convert string to bytes in Python 3?

If you look at the docs for bytes, it points you to bytearray:

bytearray([source[, encoding[, errors]]])

Return a new array of bytes. The bytearray type is a mutable sequence of integers in the range 0 <= x < 256. It has most of the usual methods of mutable sequences, described in Mutable Sequence Types, as well as most methods that the bytes type has, see Bytes and Byte Array Methods.

The optional source parameter can be used to initialize the array in a few different ways:

If it is a string, you must also give the encoding (and optionally, errors) parameters; bytearray() then converts the string to bytes using str.encode().

If it is an integer, the array will have that size and will be initialized with null bytes.

If it is an object conforming to the buffer interface, a read-only buffer of the object will be used to initialize the bytes array.

If it is an iterable, it must be an iterable of integers in the range 0 <= x < 256, which are used as the initial contents of the array.

Without an argument, an array of size 0 is created.

So bytes can do much more than just encode a string. It's Pythonic that it would allow you to call the constructor with any type of source parameter that makes sense.

For encoding a string, I think that some_string.encode(encoding) is more Pythonic than using the constructor, because it is the most self documenting -- "take this string and encode it with this encoding" is clearer than bytes(some_string, encoding) -- there is no explicit verb when you use the constructor.

Edit: I checked the Python source. If you pass a unicode string to bytes using CPython, it calls PyUnicode_AsEncodedString, which is the implementation of encode; so you're just skipping a level of indirection if you call encode yourself.

Also, see Serdalis' comment -- unicode_string.encode(encoding) is also more Pythonic because its inverse is byte_string.decode(encoding) and symmetry is nice.

Pass correct "this" context to setTimeout callback?

If you're using underscore, you can use bind.

E.g.

if (this.options.destroyOnHide) {
     setTimeout(_.bind(this.tip.destroy, this), 1000);
}

SVN icon overlays not showing properly

First clear the temporary files in Windows system, then restart your system.

Run > %temp% > delete all files

Import PEM into Java Key Store

I used Keystore Explorer

  1. Open JKS with a private key
  2. Examine signed PEM from CA
  3. Import key
  4. Save JKS

When and Why to use abstract classes/methods?

At a very high level:

Abstraction of any kind comes down to separating concerns. "Client" code of an abstraction doesn't care how the contract exposed by the abstraction is fulfilled. You usually don't care if a string class uses a null-terminated or buffer-length-tracked internal storage implementation, for example. Encapsulation hides the details, but by making classes/methods/etc. abstract, you allow the implementation to change or for new implementations to be added without affecting the client code.

Simulate string split function in Excel formula

A formula to return either the first word or all the other words.

=IF(ISERROR(FIND(" ",TRIM(A2),1)),TRIM(A2),MID(TRIM(A2),FIND(" ",TRIM(A2),1),LEN(A2)))

Examples and results

Text                  Description                      Results

                      Blank 
                      Space 
some                  Text no space                some
some text             Text with space                  text
 some                 Text with leading space          some
some                  Text with trailing space         some
some text some text   Text with multiple spaces        text some text

Comments on Formula:

  • The TRIM function is used to remove all leading and trailing spaces. Duplicate spacing within the text is also removed.
  • The FIND function then finds the first space
  • If there is no space then the trimmed text is returned
  • Otherwise the MID function is used to return any text after the first space

Avoid trailing zeroes in printf()

This can't be done with the normal printf format specifiers. The closest you could get would be:

printf("%.6g", 359.013); // 359.013
printf("%.6g", 359.01);  // 359.01

but the ".6" is the total numeric width so

printf("%.6g", 3.01357); // 3.01357

breaks it.

What you can do is to sprintf("%.20g") the number to a string buffer then manipulate the string to only have N characters past the decimal point.

Assuming your number is in the variable num, the following function will remove all but the first N decimals, then strip off the trailing zeros (and decimal point if they were all zeros).

char str[50];
sprintf (str,"%.20g",num);  // Make the number.
morphNumericString (str, 3);
:    :
void morphNumericString (char *s, int n) {
    char *p;
    int count;

    p = strchr (s,'.');         // Find decimal point, if any.
    if (p != NULL) {
        count = n;              // Adjust for more or less decimals.
        while (count >= 0) {    // Maximum decimals allowed.
             count--;
             if (*p == '\0')    // If there's less than desired.
                 break;
             p++;               // Next character.
        }

        *p-- = '\0';            // Truncate string.
        while (*p == '0')       // Remove trailing zeros.
            *p-- = '\0';

        if (*p == '.') {        // If all decimals were zeros, remove ".".
            *p = '\0';
        }
    }
}

If you're not happy with the truncation aspect (which would turn 0.12399 into 0.123 rather than rounding it to 0.124), you can actually use the rounding facilities already provided by printf. You just need to analyse the number before-hand to dynamically create the widths, then use those to turn the number into a string:

#include <stdio.h>

void nDecimals (char *s, double d, int n) {
    int sz; double d2;

    // Allow for negative.

    d2 = (d >= 0) ? d : -d;
    sz = (d >= 0) ? 0 : 1;

    // Add one for each whole digit (0.xx special case).

    if (d2 < 1) sz++;
    while (d2 >= 1) { d2 /= 10.0; sz++; }

    // Adjust for decimal point and fractionals.

    sz += 1 + n;

    // Create format string then use it.

    sprintf (s, "%*.*f", sz, n, d);
}

int main (void) {
    char str[50];
    double num[] = { 40, 359.01335, -359.00999,
        359.01, 3.01357, 0.111111111, 1.1223344 };
    for (int i = 0; i < sizeof(num)/sizeof(*num); i++) {
        nDecimals (str, num[i], 3);
        printf ("%30.20f -> %s\n", num[i], str);
    }
    return 0;
}

The whole point of nDecimals() in this case is to correctly work out the field widths, then format the number using a format string based on that. The test harness main() shows this in action:

  40.00000000000000000000 -> 40.000
 359.01335000000000263753 -> 359.013
-359.00999000000001615263 -> -359.010
 359.00999999999999090505 -> 359.010
   3.01357000000000008200 -> 3.014
   0.11111111099999999852 -> 0.111
   1.12233439999999995429 -> 1.122

Once you have the correctly rounded value, you can once again pass that to morphNumericString() to remove trailing zeros by simply changing:

nDecimals (str, num[i], 3);

into:

nDecimals (str, num[i], 3);
morphNumericString (str, 3);

(or calling morphNumericString at the end of nDecimals but, in that case, I'd probably just combine the two into one function), and you end up with:

  40.00000000000000000000 -> 40
 359.01335000000000263753 -> 359.013
-359.00999000000001615263 -> -359.01
 359.00999999999999090505 -> 359.01
   3.01357000000000008200 -> 3.014
   0.11111111099999999852 -> 0.111
   1.12233439999999995429 -> 1.122

Should I use != or <> for not equal in T-SQL?

I preferred using != instead of <> because sometimes I use the <s></s> syntax to write SQL commands. Using != is more handy to avoid syntax errors in this case.

Android WebView progress bar

This is how I did it with Kotlin to show progress with percentage.

My fragment layout.

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
         xmlns:tools="http://schemas.android.com/tools"
         android:layout_width="match_parent"
         android:layout_height="match_parent">

<WebView
    android:id="@+id/webView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

<ProgressBar
    android:layout_marginLeft="32dp"
    android:layout_marginRight="32dp"
    style="?android:attr/progressBarStyleHorizontal"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:id="@+id/progressBar"/>
</FrameLayout>

My kotlin fragment in onViewCreated

    progressBar.max = 100;
    webView.webChromeClient = object : WebChromeClient() {
        override fun onProgressChanged(view: WebView?, newProgress: Int) {
            super.onProgressChanged(view, newProgress)
            progressBar.progress = newProgress;
        }
    }

    webView!!.webViewClient = object : WebViewClient() {

        override fun onPageStarted(view: WebView?, url: String?, favicon: Bitmap?) {
            progressBar.visibility = View.VISIBLE
            progressBar.progress = 0;
            super.onPageStarted(view, url, favicon)
        }

        override fun shouldOverrideUrlLoading(view: WebView?, url: String?): Boolean {
            view?.loadUrl(url)
            return true
        }

        override fun shouldOverrideUrlLoading(
            view: WebView?,
            request: WebResourceRequest?): Boolean {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                view?.loadUrl(request?.url.toString())
            }
            return true
        }

        override fun onPageFinished(view: WebView?, url: String?) {
            super.onPageFinished(view, url)
            progressBar.visibility = View.GONE
        }
    }

    webView.loadUrl(url)

Does the join order matter in SQL?

For INNER joins, no, the order doesn't matter. The queries will return same results, as long as you change your selects from SELECT * to SELECT a.*, b.*, c.*.


For (LEFT, RIGHT or FULL) OUTER joins, yes, the order matters - and (updated) things are much more complicated.

First, outer joins are not commutative, so a LEFT JOIN b is not the same as b LEFT JOIN a

Outer joins are not associative either, so in your examples which involve both (commutativity and associativity) properties:

a LEFT JOIN b 
    ON b.ab_id = a.ab_id
  LEFT JOIN c
    ON c.ac_id = a.ac_id

is equivalent to:

a LEFT JOIN c 
    ON c.ac_id = a.ac_id
  LEFT JOIN b
    ON b.ab_id = a.ab_id

but:

a LEFT JOIN b 
    ON  b.ab_id = a.ab_id
  LEFT JOIN c
    ON  c.ac_id = a.ac_id
    AND c.bc_id = b.bc_id

is not equivalent to:

a LEFT JOIN c 
    ON  c.ac_id = a.ac_id
  LEFT JOIN b
    ON  b.ab_id = a.ab_id
    AND b.bc_id = c.bc_id

Another (hopefully simpler) associativity example. Think of this as (a LEFT JOIN b) LEFT JOIN c:

a LEFT JOIN b 
    ON b.ab_id = a.ab_id          -- AB condition
 LEFT JOIN c
    ON c.bc_id = b.bc_id          -- BC condition

This is equivalent to a LEFT JOIN (b LEFT JOIN c):

a LEFT JOIN  
    b LEFT JOIN c
        ON c.bc_id = b.bc_id          -- BC condition
    ON b.ab_id = a.ab_id          -- AB condition

only because we have "nice" ON conditions. Both ON b.ab_id = a.ab_id and c.bc_id = b.bc_id are equality checks and do not involve NULL comparisons.

You can even have conditions with other operators or more complex ones like: ON a.x <= b.x or ON a.x = 7 or ON a.x LIKE b.x or ON (a.x, a.y) = (b.x, b.y) and the two queries would still be equivalent.

If however, any of these involved IS NULL or a function that is related to nulls like COALESCE(), for example if the condition was b.ab_id IS NULL, then the two queries would not be equivalent.

Reshape an array in NumPy

a = np.arange(18).reshape(9,2)
b = a.reshape(3,3,2).swapaxes(0,2)

# a: 
array([[ 0,  1],
       [ 2,  3],
       [ 4,  5],
       [ 6,  7],
       [ 8,  9],
       [10, 11],
       [12, 13],
       [14, 15],
       [16, 17]])


# b:
array([[[ 0,  6, 12],
        [ 2,  8, 14],
        [ 4, 10, 16]],

       [[ 1,  7, 13],
        [ 3,  9, 15],
        [ 5, 11, 17]]])

cannot resolve symbol javafx.application in IntelliJ Idea IDE

Another way to resolve the problem : Click the left mouse's button on the project folder in the project structure at the left, and click on "open module settings" in the list of actions In the new windows, click on SDKs which is under the menu title "Platform settngs" Then check on the "Classpath" list if you can find the jfxrt plugin path, if not, click on the + symbol on the right and select the repertory of the jfxrt plugin (C:\Program Files\Java\jdk1.8.0\jre\lib\ext\jfxrt.jar on my desktop)

How to apply !important using .css()?

You can do this:

$("#elem").css("cssText", "width: 100px !important;");

Using "cssText" as the property name and whatever you want added to the CSS as its value.

Populating VBA dynamic arrays

Yes, you're looking for the ReDim statement, which dynamically allocates the required amount of space in the array.

The following statement

Dim MyArray()

declares an array without dimensions, so the compiler doesn't know how big it is and can't store anything inside of it.

But you can use the ReDim statement to resize the array:

ReDim MyArray(0 To 3)

And if you need to resize the array while preserving its contents, you can use the Preserve keyword along with the ReDim statement:

ReDim Preserve MyArray(0 To 3)

But do note that both ReDim and particularly ReDim Preserve have a heavy performance cost. Try to avoid doing this over and over in a loop if at all possible; your users will thank you.


However, in the simple example shown in your question (if it's not just a throwaway sample), you don't need ReDim at all. Just declare the array with explicit dimensions:

Dim MyArray(0 To 3)

Convert array to string in NodeJS

toString is a function, not a property. You'll want this:

console.log(aa.toString());

Alternatively, use join to specify the separator (toString() === join(','))

console.log(aa.join(' and '));

Why doesn't [01-12] range work as expected?

A character class in regular expressions, denoted by the [...] syntax, specifies the rules to match a single character in the input. As such, everything you write between the brackets specify how to match a single character.

Your pattern, [01-12] is thus broken down as follows:

  • 0 - match the single digit 0
  • or, 1-1, match a single digit in the range of 1 through 1
  • or, 2, match a single digit 2

So basically all you're matching is 0, 1 or 2.

In order to do the matching you want, matching two digits, ranging from 01-12 as numbers, you need to think about how they will look as text.

You have:

  • 01-09 (ie. first digit is 0, second digit is 1-9)
  • 10-12 (ie. first digit is 1, second digit is 0-2)

You will then have to write a regular expression for that, which can look like this:

  +-- a 0 followed by 1-9
  |
  |      +-- a 1 followed by 0-2
  |      |
<-+--> <-+-->
0[1-9]|1[0-2]
      ^
      |
      +-- vertical bar, this roughly means "OR" in this context

Note that trying to combine them in order to get a shorter expression will fail, by giving false positive matches for invalid input.

For instance, the pattern [0-1][0-9] would basically match the numbers 00-19, which is a bit more than what you want.

I tried finding a definite source for more information about character classes, but for now all I can give you is this Google Query for Regex Character Classes. Hopefully you'll be able to find some more information there to help you.

PHP str_replace replace spaces with underscores

I'll suggest that you use this as it will check for both single and multiple occurrence of white space (as suggested by Lucas Green).

$journalName = preg_replace('/\s+/', '_', $journalName);

instead of:

$journalName = str_replace(' ', '_', $journalName);

How to display pie chart data values of each slice in chart.js

@Hung Tran's answer works perfect. As an improvement, I would suggest not showing values that are 0. Say you have 5 elements and 2 of them are 0 and rest of them have values, the solution above will show 0 and 0%. It is better to filter that out with a not equal to 0 check!

          var val = dataset.data[i];
          var percent = String(Math.round(val/total*100)) + "%";

          if(val != 0) {
            ctx.fillText(dataset.data[i], model.x + x, model.y + y);
            // Display percent in another line, line break doesn't work for fillText
            ctx.fillText(percent, model.x + x, model.y + y + 15);
          }

Updated code below:

var data = {
    datasets: [{
        data: [
            11,
            16,
            7,
            3,
            14
        ],
        backgroundColor: [
            "#FF6384",
            "#4BC0C0",
            "#FFCE56",
            "#E7E9ED",
            "#36A2EB"
        ],
        label: 'My dataset' // for legend
    }],
    labels: [
        "Red",
        "Green",
        "Yellow",
        "Grey",
        "Blue"
    ]
};

var pieOptions = {
  events: false,
  animation: {
    duration: 500,
    easing: "easeOutQuart",
    onComplete: function () {
      var ctx = this.chart.ctx;
      ctx.font = Chart.helpers.fontString(Chart.defaults.global.defaultFontFamily, 'normal', Chart.defaults.global.defaultFontFamily);
      ctx.textAlign = 'center';
      ctx.textBaseline = 'bottom';

      this.data.datasets.forEach(function (dataset) {

        for (var i = 0; i < dataset.data.length; i++) {
          var model = dataset._meta[Object.keys(dataset._meta)[0]].data[i]._model,
              total = dataset._meta[Object.keys(dataset._meta)[0]].total,
              mid_radius = model.innerRadius + (model.outerRadius - model.innerRadius)/2,
              start_angle = model.startAngle,
              end_angle = model.endAngle,
              mid_angle = start_angle + (end_angle - start_angle)/2;

          var x = mid_radius * Math.cos(mid_angle);
          var y = mid_radius * Math.sin(mid_angle);

          ctx.fillStyle = '#fff';
          if (i == 3){ // Darker text color for lighter background
            ctx.fillStyle = '#444';
          }

          var val = dataset.data[i];
          var percent = String(Math.round(val/total*100)) + "%";

          if(val != 0) {
            ctx.fillText(dataset.data[i], model.x + x, model.y + y);
            // Display percent in another line, line break doesn't work for fillText
            ctx.fillText(percent, model.x + x, model.y + y + 15);
          }
        }
      });               
    }
  }
};

var pieChartCanvas = $("#pieChart");
var pieChart = new Chart(pieChartCanvas, {
  type: 'pie', // or doughnut
  data: data,
  options: pieOptions
});

Change the On/Off text of a toggle button Android

Set the XML as:

<ToggleButton
    android:id="@+id/flashlightButton"
    style="@style/Button"
    android:layout_above="@+id/buttonStrobeLight"
    android:layout_marginBottom="20dp"
    android:onClick="onToggleClicked"
    android:text="ToggleButton"
    android:textOn="Light ON"
    android:textOff="Light OFF" />

Can you test google analytics on a localhost address?

Answer for 2019

The best practice is to setup two separate properties for your development/staging, and your production servers. You do not want to pollute your Analytics data with test, and setting up filters is not pleasant if you are forced to do that.

That being said, Google Analytics now has real time tracking, and if you want to track Campaigns or Transactions, the lag is around 1 minute until the data is shown on the page, as long as you select the current day.

For example, you create Site and Site Test, and each one ha UA-XXXX-Y code.

In your application logic, where you serve the analytics JavaScript, check your environment and for production use your Site UA-XXXX-Y, and for staging/development use the Site Test one.

You can have this setup until you learn the ins and outs of GA, and then remove it, or keep it if you need to make constant changes (which you will test on development/staging first).

Source: personal experience, various articles.

How to remove text before | character in notepad++

Please use regex to remove anything before |

example

dsfdf | fdfsfsf
dsdss|gfghhghg
dsdsds |dfdsfsds

Use find and replace in notepad++

find: .+(\|) replace: \1

output

| fdfsfsf
|gfghhghg
|dfdsfsds

Can we have multiple "WITH AS" in single sql - Oracle SQL

Yes you can...

WITH SET1 AS (SELECT SYSDATE FROM DUAL), -- SET1 initialised
     SET2 AS (SELECT * FROM SET1)        -- SET1 accessed
SELECT * FROM SET2;                      -- SET2 projected

10/29/2013 10:43:26 AM

Follow the order in which it should be initialized in Common Table Expressions

Confirm deletion using Bootstrap 3 modal box

You need the modal in your HTML. When the delete button is clicked it popup the modal. It's also important to prevent the click of that button from submitting the form. When the confirmation is clicked the form will submit.

_x000D_
_x000D_
   _x000D_
_x000D_
 $('button[name="remove_levels"]').on('click', function(e) {_x000D_
      var $form = $(this).closest('form');_x000D_
      e.preventDefault();_x000D_
      $('#confirm').modal({_x000D_
          backdrop: 'static',_x000D_
          keyboard: false_x000D_
      })_x000D_
      .on('click', '#delete', function(e) {_x000D_
          $form.trigger('submit');_x000D_
        });_x000D_
      $("#cancel").on('click',function(e){_x000D_
       e.preventDefault();_x000D_
       $('#confirm').modal.model('hide');_x000D_
      });_x000D_
    });
_x000D_
<link href="http://getbootstrap.com/2.3.2/assets/css/bootstrap.css" rel="stylesheet" />_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<script src="http://getbootstrap.com/2.3.2/assets/js/bootstrap.js"></script>_x000D_
<form action="#" method="POST">_x000D_
  <button class='btn btn-danger btn-xs' type="submit" name="remove_levels" value="delete"><span class="fa fa-times"></span> delete</button>_x000D_
</form>_x000D_
_x000D_
<div id="confirm" class="modal">_x000D_
  <div class="modal-body">_x000D_
    Are you sure?_x000D_
  </div>_x000D_
  <div class="modal-footer">_x000D_
    <button type="button" data-dismiss="modal" class="btn btn-primary" id="delete">Delete</button>_x000D_
    <button type="button" data-dismiss="modal" class="btn">Cancel</button>_x000D_
  </div>_x000D_
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how to stop a loop arduino

The three options that come to mind:

1st) End void loop() with while(1)... or equally as good... while(true)

void loop(){
    //the code you want to run once here, 
    //e.g., If (blah == blah)...etc.

    while(1)        //last line of main loop
}

This option runs your code once and then kicks the Ard into an endless "invisible" loop. Perhaps not the nicest way to go, but as far as outside appearances, it gets the job done.
The Ard will continue to draw current while it spins itself in an endless circle... perhaps one could set up a sort of timer function that puts the Ard to sleep after so many seconds, minutes, etc., of looping... just a thought... there are certainly various sleep libraries out there... see e.g., Monk, Programming Arduino: Next Steps, pgs., 85-100 for further discussion of such.

2nd) Create a "stop main loop" function with a conditional control structure that makes its initial test fail on a second pass.
This often requires declaring a global variable and having the "stop main loop" function toggle the value of the variable upon termination. E.g.,

boolean stop_it = false;         //global variable

void setup(){
    Serial.begin(9600); 
    //blah...
}

boolean stop_main_loop(){        //fancy stop main loop function

    if(stop_it == false){   //which it will be the first time through

        Serial.println("This should print once.");

       //then do some more blah....you can locate all the
       // code you want to run once here....eventually end by 
       //toggling the "stop_it" variable ... 
    }
    stop_it = true; //...like this
    return stop_it;   //then send this newly updated "stop_it" value
                     // outside the function
}

void loop{ 

    stop_it = stop_main_loop();     //and finally catch that updated 
                                    //value and store it in the global stop_it 
                                    //variable, effectively 
                                    //halting the loop  ...
}

Granted, this might not be especially pretty, but it also works.
It kicks the Ard into another endless "invisible" loop, but this time it's a case of repeatedly checking the if(stop_it == false) condition in stop_main_loop() which of course fails to pass every time after the first time through.

3rd) One could once again use a global variable but use a simple if (test == blah){} structure instead of a fancy "stop main loop" function.

boolean start = true;                  //global variable

void setup(){

      Serial.begin(9600);
}

void loop(){

      if(start == true){           //which it will be the first time through



           Serial.println("This should print once.");       

           //the code you want to run once here, 
           //e.g., more If (blah == blah)...etc.

     }

start = false;                //toggle value of global "start" variable
                              //Next time around, the if test is sure to fail.
}

There are certainly other ways to "stop" that pesky endless main loop but these three as well as those already mentioned should get you started.

What is the syntax to insert one list into another list in python?

If we just do x.append(y), y gets referenced into x such that any changes made to y will affect appended x as well. So if we need to insert only elements, we should do following:

x = [1,2,3] y = [4,5,6] x.append(y[:])

"string could not resolved" error in Eclipse for C++ (Eclipse can't resolve standard library)

You need to ensure your environment is properly setup in Eclipse so it knows the paths to your includes. Otherwise, it underlines them as not found.

Getting error: ISO C++ forbids declaration of with no type

You forgot the return types in your member function definitions:

int ttTree::ttTreeInsert(int value) { ... }
^^^               

and so on.

What database does Google use?

Bigtable

A Distributed Storage System for Structured Data

Bigtable is a distributed storage system (built by Google) for managing structured data that is designed to scale to a very large size: petabytes of data across thousands of commodity servers.

Many projects at Google store data in Bigtable, including web indexing, Google Earth, and Google Finance. These applications place very different demands on Bigtable, both in terms of data size (from URLs to web pages to satellite imagery) and latency requirements (from backend bulk processing to real-time data serving).

Despite these varied demands, Bigtable has successfully provided a flexible, high-performance solution for all of these Google products.

Some features

  • fast and extremely large-scale DBMS
  • a sparse, distributed multi-dimensional sorted map, sharing characteristics of both row-oriented and column-oriented databases.
  • designed to scale into the petabyte range
  • it works across hundreds or thousands of machines
  • it is easy to add more machines to the system and automatically start taking advantage of those resources without any reconfiguration
  • each table has multiple dimensions (one of which is a field for time, allowing versioning)
  • tables are optimized for GFS (Google File System) by being split into multiple tablets - segments of the table as split along a row chosen such that the tablet will be ~200 megabytes in size.

Architecture

BigTable is not a relational database. It does not support joins nor does it support rich SQL-like queries. Each table is a multidimensional sparse map. Tables consist of rows and columns, and each cell has a time stamp. There can be multiple versions of a cell with different time stamps. The time stamp allows for operations such as "select 'n' versions of this Web page" or "delete cells that are older than a specific date/time."

In order to manage the huge tables, Bigtable splits tables at row boundaries and saves them as tablets. A tablet is around 200 MB, and each machine saves about 100 tablets. This setup allows tablets from a single table to be spread among many servers. It also allows for fine-grained load balancing. If one table is receiving many queries, it can shed other tablets or move the busy table to another machine that is not so busy. Also, if a machine goes down, a tablet may be spread across many other servers so that the performance impact on any given machine is minimal.

Tables are stored as immutable SSTables and a tail of logs (one log per machine). When a machine runs out of system memory, it compresses some tablets using Google proprietary compression techniques (BMDiff and Zippy). Minor compactions involve only a few tablets, while major compactions involve the whole table system and recover hard-disk space.

The locations of Bigtable tablets are stored in cells. The lookup of any particular tablet is handled by a three-tiered system. The clients get a point to a META0 table, of which there is only one. The META0 table keeps track of many META1 tablets that contain the locations of the tablets being looked up. Both META0 and META1 make heavy use of pre-fetching and caching to minimize bottlenecks in the system.

Implementation

BigTable is built on Google File System (GFS), which is used as a backing store for log and data files. GFS provides reliable storage for SSTables, a Google-proprietary file format used to persist table data.

Another service that BigTable makes heavy use of is Chubby, a highly-available, reliable distributed lock service. Chubby allows clients to take a lock, possibly associating it with some metadata, which it can renew by sending keep alive messages back to Chubby. The locks are stored in a filesystem-like hierarchical naming structure.

There are three primary server types of interest in the Bigtable system:

  1. Master servers: assign tablets to tablet servers, keeps track of where tablets are located and redistributes tasks as needed.
  2. Tablet servers: handle read/write requests for tablets and split tablets when they exceed size limits (usually 100MB - 200MB). If a tablet server fails, then a 100 tablet servers each pickup 1 new tablet and the system recovers.
  3. Lock servers: instances of the Chubby distributed lock service. Lots of actions within BigTable require acquisition of locks including opening tablets for writing, ensuring that there is no more than one active Master at a time, and access control checking.

Example from Google's research paper:

alt text

A slice of an example table that stores Web pages. The row name is a reversed URL. The contents column family contains the page contents, and the anchor column family contains the text of any anchors that reference the page. CNN's home page is referenced by both the Sports Illustrated and the MY-look home pages, so the row contains columns named anchor:cnnsi.com and anchor:my.look.ca. Each anchor cell has one version; the contents column has three versions, at timestamps t3, t5, and t6.

API

Typical operations to BigTable are creation and deletion of tables and column families, writing data and deleting columns from a row. BigTable provides this functions to application developers in an API. Transactions are supported at the row level, but not across several row keys.


Here is the link to the PDF of the research paper.

And here you can find a video showing Google's Jeff Dean in a lecture at the University of Washington, discussing the Bigtable content storage system used in Google's backend.

Fixing Xcode 9 issue: "iPhone is busy: Preparing debugger support for iPhone"

I've faced the same problem because of a cable. I changed my third party USB/lighting cable into original Apple cable, and it worked.

How can I listen to the form submit event in javascript?

Why do people always use jQuery when it isn't necessary?
Why can't people just use simple JavaScript?

var ele = /*Your Form Element*/;
if(ele.addEventListener){
    ele.addEventListener("submit", callback, false);  //Modern browsers
}else if(ele.attachEvent){
    ele.attachEvent('onsubmit', callback);            //Old IE
}

callback is a function that you want to call when the form is being submitted.

About EventTarget.addEventListener, check out this documentation on MDN.

To cancel the native submit event (prevent the form from being submitted), use .preventDefault() in your callback function,

document.querySelector("#myForm").addEventListener("submit", function(e){
    if(!isValid){
        e.preventDefault();    //stop form from submitting
    }
});

Listening to the submit event with libraries

If for some reason that you've decided a library is necessary (you're already using one or you don't want to deal with cross-browser issues), here's a list of ways to listen to the submit event in common libraries:

  1. jQuery

    $(ele).submit(callback);
    

    Where ele is the form element reference, and callback being the callback function reference. Reference

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  1. AngularJS (1.x)

    <form ng-submit="callback()">
    
    $scope.callback = function(){ /*...*/ };
    

    Very straightforward, where $scope is the scope provided by the framework inside your controller. Reference

  2. React

    <form onSubmit={this.handleSubmit}>
    
    class YourComponent extends Component {
        // stuff
    
        handleSubmit(event) {
            // do whatever you need here
    
            // if you need to stop the submit event and 
            // perform/dispatch your own actions
            event.preventDefault();
        }
    
        // more stuff
    }
    

    Simply pass in a handler to the onSubmit prop. Reference

  3. Other frameworks/libraries

    Refer to the documentation of your framework.


Validation

You can always do your validation in JavaScript, but with HTML5 we also have native validation.

<!-- Must be a 5 digit number -->
<input type="number" required pattern="\d{5}">

You don't even need any JavaScript! Whenever native validation is not supported, you can fallback to a JavaScript validator.

Demo: http://jsfiddle.net/DerekL/L23wmo1L/

Nested select statement in SQL Server

You need to alias the subquery.

SELECT name FROM (SELECT name FROM agentinformation) a  

or to be more explicit

SELECT a.name FROM (SELECT name FROM agentinformation) a  

"Parse Error : There is a problem parsing the package" while installing Android application

I had this problem, even when I specified the correct minSDK and targetSDK version. My problem was, I was using "android:theme="@android:style/Theme.NoTitleBar.Fullscreen" in launcher activity, on Jellybean device. When I removed this attribute, it worked.

Trying to get PyCharm to work, keep getting "No Python interpreter selected"

Your problem probably is that you haven't installed python. Meaning that, if you are using Windows, you have not downloaded the installer for Windows, that you can find on the official Python website.

In case you have, chances are that PyCharm cannot find your Python installation because its not in the default location, which is usually C:\Python27 or C:\Python33 (for me at least).

So, if you have installed Python and it still gives this error, then there can be two things that have happened:

  1. You use a virtualenv and that virtualenv has been deleted or the filepath changed. In this case, you will have to find proceed to the next part of this answer.
  2. Your python installation is not in its default place, in which case you will need to find its location, and locate the python.exe file.

Once you have located the necessary binaries, you will need to tell PyCharm were to look:

  1. Open your settings dialogue CTRL + ALT + S
  2. Then you will need to type in interpreter in the search box:

    enter image description here

  3. As you can see above, you will need to go to Project Interpreter and then go to Python Interpreter. The location has been selected for you in the above image.

  4. To the side you will see a couple of options as icons, click the big + icon, then click on local, because your interpreter is on this computer.

  5. This will open up a dialogue box. Make sure to select the python.exe file of that directory, do not give pycharm the whole directory. It just wants the interpreter.

Transform only one axis to log10 scale with ggplot2

I had a similar problem and this scale worked for me like a charm:

breaks = 10**(1:10)
scale_y_log10(breaks = breaks, labels = comma(breaks))

as you want the intermediate levels, too (10^3.5), you need to tweak the formatting:

breaks = 10**(1:10 * 0.5)
m <- ggplot(diamonds, aes(y = price, x = color)) + geom_boxplot()
m + scale_y_log10(breaks = breaks, labels = comma(breaks, digits = 1))

After executing::

enter image description here

How to fit Windows Form to any screen resolution?

int h = Screen.PrimaryScreen.WorkingArea.Height;
int w = Screen.PrimaryScreen.WorkingArea.Width;
this.ClientSize = new Size(w , h);

Animate text change in UILabel

Swift 4

The proper way to fade a UILabel (or any UIView for that matter) is to use a Core Animation Transition. This will not flicker, nor will it fade to black if the content is unchanged.

A portable and clean solution is to use a Extension in Swift (invoke prior changing visible elements)

// Usage: insert view.fadeTransition right before changing content


extension UIView {
    func fadeTransition(_ duration:CFTimeInterval) {
        let animation = CATransition()
        animation.timingFunction = CAMediaTimingFunction(name:
            CAMediaTimingFunctionName.easeInEaseOut)
        animation.type = CATransitionType.fade
        animation.duration = duration
        layer.add(animation, forKey: CATransitionType.fade.rawValue)
    }
}

Invocation looks like this:

// This will fade
aLabel.fadeTransition(0.4)
aLabel.text = "text"

Blank, then 1 to 5 fade transition


? Find this solution on GitHub and additional details on Swift Recipes.

Library not loaded: libmysqlclient.16.dylib error when trying to run 'rails server' on OS X 10.6 with mysql2 gem

I solved this problem by deleting my gemset for my current project and recreating it and rerunning bundle install. I think I caused it by installing a newer version of mysql.

How do I iterate over a range of numbers defined by variables in Bash?

The POSIX way

If you care about portability, use the example from the POSIX standard:

i=2
end=5
while [ $i -le $end ]; do
    echo $i
    i=$(($i+1))
done

Output:

2
3
4
5

Things which are not POSIX:

Excel to CSV with UTF8 encoding

Came across the same problem and googled out this post. None of the above worked for me. At last I converted my Unicode .xls to .xml (choose Save as ... XML Spreadsheet 2003) and it produced the correct character. Then I wrote code to parse the xml and extracted content for my use.

What is a NullReferenceException, and how do I fix it?

While what causes a NullReferenceExceptions and approaches to avoid/fix such an exception have been addressed in other answers, what many programmers haven't learned yet is how to independently debug such exceptions during development.

In Visual Studio this is usually easy thanks to the Visual Studio Debugger.


First, make sure that the correct error is going to be caught - see How do I allow breaking on 'System.NullReferenceException' in VS2010? Note1

Then either Start with Debugging (F5) or Attach [the VS Debugger] to Running Process. On occasion it may be useful to use Debugger.Break, which will prompt to launch the debugger.

Now, when the NullReferenceException is thrown (or unhandled) the debugger will stop (remember the rule set above?) on the line on which the exception occurred. Sometimes the error will be easy to spot.

For instance, in the following line the only code that can cause the exception is if myString evaluates to null. This can be verified by looking at the Watch Window or running expressions in the Immediate Window.

var x = myString.Trim();

In more advanced cases, such as the following, you'll need to use one of the techniques above (Watch or Immediate Windows) to inspect the expressions to determine if str1 was null or if str2 was null.

var x = str1.Trim() + str2.Trim();

Once where the exception is throw has been located, it's usually trivial to reason backwards to find out where the null value was [incorrectly] introduced --

Take the time required to understand the cause of the exception. Inspect for null expressions. Inspect the previous expressions which could have resulted in such null expressions. Add breakpoints and step through the program as appropriate. Use the debugger.


1 If Break on Throws is too aggressive and the debugger stops on an NPE in the .NET or 3rd-party library, Break on User-Unhandled can be used to limit the exceptions caught. Additionally, VS2012 introduces Just My Code which I recommend enabling as well.

If you are debugging with Just My Code enabled, the behavior is slightly different. With Just My Code enabled, the debugger ignores first-chance common language runtime (CLR) exceptions that are thrown outside of My Code and do not pass through My Code

Create numpy matrix filled with NaNs

You can always use multiplication if you don't immediately recall the .empty or .full methods:

>>> np.nan * np.ones(shape=(3,2))
array([[ nan,  nan],
       [ nan,  nan],
       [ nan,  nan]])

Of course it works with any other numerical value as well:

>>> 42 * np.ones(shape=(3,2))
array([[ 42,  42],
       [ 42,  42],
       [ 42, 42]])

But the @u0b34a0f6ae's accepted answer is 3x faster (CPU cycles, not brain cycles to remember numpy syntax ;):

$ python -mtimeit "import numpy as np; X = np.empty((100,100));" "X[:] = np.nan;"
100000 loops, best of 3: 8.9 usec per loop
(predict)laneh@predict:~/src/predict/predict/webapp$ master
$ python -mtimeit "import numpy as np; X = np.ones((100,100));" "X *= np.nan;"
10000 loops, best of 3: 24.9 usec per loop

JUnit tests pass in Eclipse but fail in Maven Surefire

I suddenly experienced this error, and the solution for me was to disable to run tests in parallel.

Your milage may vary, since I could lower number of failing tests by configuring surefire to run parallel tests by ´classes´.:

            <plugin>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.22.2</version>
                <configuration>
                    <parallel>classes</parallel>
                    <threadCount>10</threadCount>
                </configuration>
            </plugin>

As I wrote first, this was not enough for my test suite, so I completely disabled parallel by removing the <configuration> section.

Changing column names of a data frame

Just to correct and slightly extend Scott Wilson answer.
You can use data.table's setnames function on data.frames too.

Do not expect speed up of the operation but you can expect the setnames to be more efficient for memory consumption as it updates column names by reference. This can be tracked with address function, see below.

library(data.table)
set.seed(123)
n = 1e8

df = data.frame(bad=sample(1:3, n, TRUE), worse=rnorm(n))
address(df)
#[1] "0x208f9f00"
colnames(df) <- c("good", "better")
address(df)
#[1] "0x208fa1d8"
rm(df)

dt = data.table(bad=sample(1:3, n, TRUE), worse=rnorm(n))
address(dt)
#[1] "0x535c830"
setnames(dt, c("good", "better"))
address(dt)
#[1] "0x535c830"
rm(dt)

So if you are hitting your memory limits you may consider to use this one instead.

How to check model string property for null in a razor view

Try this first, you may be passing a Null Model:

@if (Model != null && !String.IsNullOrEmpty(Model.ImageName))
{
    <label for="Image">Change picture</label>
}
else
{ 
    <label for="Image">Add picture</label>
}

Otherise, you can make it even neater with some ternary fun! - but that will still error if your model is Null.

<label for="Image">@(String.IsNullOrEmpty(Model.ImageName) ? "Add" : "Change") picture</label>

How can I add an ampersand for a value in a ASP.net/C# app config file value

Have you tried this?

<appSettings>  
  <add key="myurl" value="http://www.myurl.com?&amp;cid=&amp;sid="/>
<appSettings>

JavaScript open in a new window, not tab

I just tried this with IE (11) and Chrome (54.0.2794.1 canary SyzyASan):

window.open(url, "_blank", "x=y")

... and it opened in a new window.

Which means that Clint pachl had it right when he said that providing any one parameter will cause the new window to open.

-- and apparently it doesn't have to be a legitimate parameter!

(YMMV - as I said, I only tested it in two places...and the next upgrade might invalidate the results, any way)

ETA: I just noticed, though - in IE, the window has no decorations.

How to check for null in a single statement in scala?

Option(getObject) foreach (QueueManager add)

How to print an exception in Python 3?

I'm guessing that you need to assign the Exception to a variable. As shown in the Python 3 tutorial:

def fails():
    x = 1 / 0

try:
    fails()
except Exception as ex:
    print(ex)

To give a brief explanation, as is a pseudo-assignment keyword used in certain compound statements to assign or alias the preceding statement to a variable.

In this case, as assigns the caught exception to a variable allowing for information about the exception to stored and used later, instead of needing to be dealt with immediately. (This is discussed in detail in the Python 3 Language Reference: The try Statement.)


The other compound statement using as is the with statement:

@contextmanager
def opening(filename):
    f = open(filename)
    try:
        yield f
    finally:
        f.close()

with opening(filename) as f:
    # ...read data from f...

Here, with statements are used to wrap the execution of a block with methods defined by context managers. This functions like an extended try...except...finally statement in a neat generator package, and the as statement assigns the generator-produced result from the context manager to a variable for extended use. (This is discussed in detail in the Python 3 Language Reference: The with Statement.)


Finally, as can be used when importing modules, to alias a module to a different (usually shorter) name:

import foo.bar.baz as fbb

This is discussed in detail in the Python 3 Language Reference: The import Statement.

How to insert values in two dimensional array programmatically?

Try to code below,

String[][] shades = new String[4][3];
for(int i = 0; i < 4; i++)
{
  for(int y = 0; y < 3; y++)
  {
    shades[i][y] = value;
  }
}

Convert timestamp in milliseconds to string formatted time in Java

It is possible to use apache commons (commons-lang3) and its DurationFormatUtils class.

<dependency>
  <groupId>org.apache.commons</groupId>
  <artifactId>commons-lang3</artifactId>
  <version>3.1</version>
</dependency>

For example:

String formattedDuration = DurationFormatUtils.formatDurationHMS(12313152);
// formattedDuration value is "3:25:13.152"
String otherFormattedDuration = DurationFormatUtils.formatDuration(12313152, DurationFormatUtils.ISO_EXTENDED_FORMAT_PATTERN);
// otherFormattedDuration value is "P0000Y0M0DT3H25M13.152S"

Hope it can help ...

Remove columns from dataframe where ALL values are NA

You can use Janitor package remove_empty

library(janitor)

df %>%
  remove_empty(c("rows", "cols")) #select either row or cols or both

Also, Another dplyr approach

 library(dplyr) 
 df %>% select_if(~all(!is.na(.)))

OR

df %>% select_if(colSums(!is.na(.)) == nrow(df))

this is also useful if you want to only exclude / keep column with certain number of missing values e.g.

 df %>% select_if(colSums(!is.na(.))>500)

Two Page Login with Spring Security 3.2.x

There should be three pages here:

  1. Initial login page with a form that asks for your username, but not your password.
  2. You didn't mention this one, but I'd check whether the client computer is recognized, and if not, then challenge the user with either a CAPTCHA or else a security question. Otherwise the phishing site can simply use the tendered username to query the real site for the security image, which defeats the purpose of having a security image. (A security question is probably better here since with a CAPTCHA the attacker could have humans sitting there answering the CAPTCHAs to get at the security images. Depends how paranoid you want to be.)
  3. A page after that that displays the security image and asks for the password.

I don't see this short, linear flow being sufficiently complex to warrant using Spring Web Flow.

I would just use straight Spring Web MVC for steps 1 and 2. I wouldn't use Spring Security for the initial login form, because Spring Security's login form expects a password and a login processing URL. Similarly, Spring Security doesn't provide special support for CAPTCHAs or security questions, so you can just use Spring Web MVC once again.

You can handle step 3 using Spring Security, since now you have a username and a password. The form login page should display the security image, and it should include the user-provided username as a hidden form field to make Spring Security happy when the user submits the login form. The only way to get to step 3 is to have a successful POST submission on step 1 (and 2 if applicable).

How to update /etc/hosts file in Docker image during "docker build"

Tis is me Dockefile
FROM XXXXX
ENV DNS_1="10.0.0.1 TEST1.COM"
ENV DNS_1="10.0.0.1 TEST2.COM" 
CMD ["bash","change_hosts.sh"]`

#cat change_hosts.sh
su - root -c "env | grep DNS | akw -F "=" '{print $2}' >> /etc/hosts"
  • info
  • user must su

accepting HTTPS connections with self-signed certificates

I was frustrated trying to connect my Android App to my RESTful service using https. Also I was a bit annoyed about all the answers that suggested to disable certificate checking altogether. If you do so, whats the point of https?

After googled about the topic for a while, I finally found this solution where external jars are not needed, just Android APIs. Thanks to Andrew Smith, who posted it on July, 2014

 /**
 * Set up a connection to myservice.domain using HTTPS. An entire function
 * is needed to do this because myservice.domain has a self-signed certificate.
 * 
 * The caller of the function would do something like:
 * HttpsURLConnection urlConnection = setUpHttpsConnection("https://littlesvr.ca");
 * InputStream in = urlConnection.getInputStream();
 * And read from that "in" as usual in Java
 * 
 * Based on code from:
 * https://developer.android.com/training/articles/security-ssl.html#SelfSigned
 */
public static HttpsURLConnection setUpHttpsConnection(String urlString)
{
    try
    {
        // Load CAs from an InputStream
        // (could be from a resource or ByteArrayInputStream or ...)
        CertificateFactory cf = CertificateFactory.getInstance("X.509");

        // My CRT file that I put in the assets folder
        // I got this file by following these steps:
        // * Go to https://littlesvr.ca using Firefox
        // * Click the padlock/More/Security/View Certificate/Details/Export
        // * Saved the file as littlesvr.crt (type X.509 Certificate (PEM))
        // The MainActivity.context is declared as:
        // public static Context context;
        // And initialized in MainActivity.onCreate() as:
        // MainActivity.context = getApplicationContext();
        InputStream caInput = new BufferedInputStream(MainActivity.context.getAssets().open("littlesvr.crt"));
        Certificate ca = cf.generateCertificate(caInput);
        System.out.println("ca=" + ((X509Certificate) ca).getSubjectDN());

        // Create a KeyStore containing our trusted CAs
        String keyStoreType = KeyStore.getDefaultType();
        KeyStore keyStore = KeyStore.getInstance(keyStoreType);
        keyStore.load(null, null);
        keyStore.setCertificateEntry("ca", ca);

        // Create a TrustManager that trusts the CAs in our KeyStore
        String tmfAlgorithm = TrustManagerFactory.getDefaultAlgorithm();
        TrustManagerFactory tmf = TrustManagerFactory.getInstance(tmfAlgorithm);
        tmf.init(keyStore);

        // Create an SSLContext that uses our TrustManager
        SSLContext context = SSLContext.getInstance("TLS");
        context.init(null, tmf.getTrustManagers(), null);

        // Tell the URLConnection to use a SocketFactory from our SSLContext
        URL url = new URL(urlString);
        HttpsURLConnection urlConnection = (HttpsURLConnection)url.openConnection();
        urlConnection.setSSLSocketFactory(context.getSocketFactory());

        return urlConnection;
    }
    catch (Exception ex)
    {
        Log.e(TAG, "Failed to establish SSL connection to server: " + ex.toString());
        return null;
    }
}

It worked nice for my mockup App.

Change value of input onchange?

for jQuery we can use below:

by input name:

$('input[name="textboxname"]').val('some value');

by input class:

$('input[type=text].textboxclass').val('some value');

by input id:

$('#textboxid').val('some value');

disable past dates on datepicker

you have just introduce parameter startDate as mentioned below.

var todaydate = new Date();
    $(".leave-day").datepicker({
        autoclose: true,
        todayBtn: "linked",
        todayHighlight: true,
        startDate: todaydate     
      }
    ).on('changeDate', function (e) {
        var dateCalendar = e.format();
        dateCalendar = moment(dateCalendar, 'MM/DD/YYYY').format('YYYY-MM-DD');
        $("#date-leave").val(dateCalendar);
    });

Insert a string at a specific index

Using slice

You can use slice(0,index) + str + slice(index). Or you can create a method for it.

_x000D_
_x000D_
String.prototype.insertAt = function(index,str){_x000D_
  return this.slice(0,index) + str + this.slice(index)_x000D_
}_x000D_
console.log("foo bar".insertAt(4,'baz ')) //foo baz bar
_x000D_
_x000D_
_x000D_

Splice method for Strings

You can split() the main string and add then use normal splice()

_x000D_
_x000D_
String.prototype.splice = function(index,del,...newStrs){_x000D_
  let str = this.split('');_x000D_
  str.splice(index,del,newStrs.join('') || '');_x000D_
  return str.join('');_x000D_
}_x000D_
_x000D_
_x000D_
 var txt1 = "foo baz"_x000D_
_x000D_
//inserting single string._x000D_
console.log(txt1.splice(4,0,"bar ")); //foo bar baz_x000D_
_x000D_
_x000D_
//inserting multiple strings_x000D_
console.log(txt1.splice(4,0,"bar ","bar2 ")); //foo bar bar2 baz_x000D_
_x000D_
_x000D_
//removing letters_x000D_
console.log(txt1.splice(1,2)) //f baz_x000D_
_x000D_
_x000D_
//remving and inseting atm_x000D_
console.log(txt1.splice(1,2," bar")) //f bar baz
_x000D_
_x000D_
_x000D_

Applying splice() at multiple indexes

The method takes an array of arrays each element of array representing a single splice().

_x000D_
_x000D_
String.prototype.splice = function(index,del,...newStrs){_x000D_
  let str = this.split('');_x000D_
  str.splice(index,del,newStrs.join('') || '');_x000D_
  return str.join('');_x000D_
}_x000D_
_x000D_
_x000D_
String.prototype.mulSplice = function(arr){_x000D_
  str = this_x000D_
  let dif = 0;_x000D_
  _x000D_
  arr.forEach(x => {_x000D_
    x[2] === x[2] || [];_x000D_
    x[1] === x[1] || 0;_x000D_
    str = str.splice(x[0] + dif,x[1],...x[2]);_x000D_
    dif += x[2].join('').length - x[1];_x000D_
  })_x000D_
  return str;_x000D_
}_x000D_
_x000D_
let txt = "foo bar baz"_x000D_
_x000D_
//Replacing the 'foo' and 'bar' with 'something1' ,'another'_x000D_
console.log(txt.splice(0,3,'something'))_x000D_
console.log(txt.mulSplice(_x000D_
[_x000D_
[0,3,["something1"]],_x000D_
[4,3,["another"]]_x000D_
]_x000D_
_x000D_
))
_x000D_
_x000D_
_x000D_

What online brokers offer APIs?

I vote for IB(Interactive Brokers). I've used them in the past as was quite happy. Pinnacle Capital Markets trading also has an API (pcmtrading.com) but I haven't used them.

Interactive Brokers:

https://www.interactivebrokers.com/en/?f=%2Fen%2Fsoftware%2Fibapi.php

Pinnacle Capital Markets:

http://www.pcmtrading.com/es/technology/api.html

Fragment MyFragment not attached to Activity

simple solution and work 100%

if (getActivity() == null || !isAdded()) return;

repository element was not specified in the POM inside distributionManagement element or in -DaltDep loymentRepository=id::layout::url parameter

In your pom.xml you should add distributionManagement configuration to where to deploy.

In the following example I have used file system as the locations.

<distributionManagement>
       <repository>
         <id>internal.repo</id>
         <name>Internal repo</name>
         <url>file:///home/thara/testesb/in</url>
       </repository>
   </distributionManagement>

you can add another location while deployment by using the following command (but to avoid above error you should have at least 1 repository configured) :

mvn deploy -DaltDeploymentRepository=internal.repo::default::file:///home/thara/testesb/in

ASP MVC in IIS 7 results in: HTTP Error 403.14 - Forbidden

I know this is an old topic, but you can also get this error (when you are debugging) if you have a folder named the same as a route in a controller.

For instance, if you have a UserController, with a route called /User and you ALSO have a folder in your solution called "User" then IISExpress will try to browse the folder instead of showing your view.

Running vbscript from batch file

Batch files are processed row by row and terminate whenever you call an executable directly.
- To make the batch file wait for the process to terminate and continue, put call in front of it.
- To make the batch file continue without waiting, put start "" in front of it.

I recommend using this single line script to accomplish your goal:

@call cscript "%~dp0necdaily.vbs"

(because this is a single line, you can use @ instead of @echo off)

If you believe your script can only be called from the SysWOW64 versions of cmd.exe, you might try:

@%WINDIR%\SysWOW64\cmd.exe /c call cscript "%~dp0necdaily.vbs"

If you need the window to remain, you can replace /c with /k

Animation fade in and out

we can simply use:

public void animStart(View view) {
    if(count==0){
        Log.d("count", String.valueOf(count));
        i1.animate().alpha(0f).setDuration(2000);
        i2.animate().alpha(1f).setDuration(2000);
        count =1;
    }
    else if(count==1){
        Log.d("count", String.valueOf(count));
        count =0;
        i2.animate().alpha(0f).setDuration(2000);
        i1.animate().alpha(1f).setDuration(2000);
    }
}

where i1 and i2 are defined in the onCreateView() as:

    i1 = (ImageView)findViewById(R.id.firstImage);
    i2 = (ImageView)findViewById(R.id.secondImage);

count is a class variable initilaized to 0.

The XML file is :

    <?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">
        <ImageView
            android:id="@+id/secondImage"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:onClick="animStart"
            android:src="@drawable/second" />
      <ImageView
          android:id="@+id/firstImage"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"

          android:onClick="animStart"
          android:src="@drawable/first" />
    </RelativeLayout>

@drawable/first and @drawable/second are the images in the drawable folder in res.

Ternary operator (?:) in Bash

Here's a general solution, that

  • works with string tests as well
  • feels rather like an expression
  • avoids any subtle side effects when the condition fails

Test with numerical comparison

a=$(if [ "$b" -eq 5 ]; then echo "$c"; else echo "$d"; fi)

Test with String comparison

a=$(if [ "$b" = "5" ]; then echo "$c"; else echo "$d"; fi)

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

You should first take a look at this. This explains what happens when you import a package. For convenience:

The import statement uses the following convention: if a package’s __init__.py code defines a list named __all__, it is taken to be the list of module names that should be imported when from package import * is encountered. It is up to the package author to keep this list up-to-date when a new version of the package is released. Package authors may also decide not to support it, if they don’t see a use for importing * from their package.

So PyCharm respects this by showing a warning message, so that the author can decide which of the modules get imported when * from the package is imported. Thus this seems to be useful feature of PyCharm (and in no way can it be called a bug, I presume). You can easily remove this warning by adding the names of the modules to be imported when your package is imported in the __all__ variable which is list, like this

__init__.py

from . import MyModule1, MyModule2, MyModule3
__all__ = [MyModule1, MyModule2, MyModule3]

After you add this, you can ctrl+click on these module names used in any other part of your project to directly jump to the declaration, which I often find very useful.

Side-by-side plots with ggplot2

Yes, methinks you need to arrange your data appropriately. One way would be this:

X <- data.frame(x=rep(x,2),
                y=c(3*x+eps, 2*x+eps),
                case=rep(c("first","second"), each=100))

qplot(x, y, data=X, facets = . ~ case) + geom_smooth()

I am sure there are better tricks in plyr or reshape -- I am still not really up to speed on all these powerful packages by Hadley.

Trim Whitespaces (New Line and Tab space) in a String in Oracle

TRANSLATE (column_name, 'd'||CHR(10)||CHR(13), 'd')

The 'd' is a dummy character, because translate does not work if the 3rd parameter is null.

Should I use window.navigate or document.location in JavaScript?

You can move your page using

window.location.href =Url;

How to read a file byte by byte in Python and how to print a bytelist as a binary?

There's a python module especially made for reading and writing to and from binary encoded data called 'struct'. Since versions of Python under 2.6 doesn't support str.format, a custom method needs to be used to create binary formatted strings.

import struct

# binary string
def bstr(n): # n in range 0-255
    return ''.join([str(n >> x & 1) for x in (7,6,5,4,3,2,1,0)])

# read file into an array of binary formatted strings.
def read_binary(path):
    f = open(path,'rb')
    binlist = []
    while True:
        bin = struct.unpack('B',f.read(1))[0] # B stands for unsigned char (8 bits)
        if not bin:
            break
        strBin = bstr(bin)
        binlist.append(strBin)
    return binlist

Check if list is empty in C#

If the list implementation you're using is IEnumerable<T> and Linq is an option, you can use Any:

if (!list.Any()) {

}

Otherwise you generally have a Length or Count property on arrays and collection types respectively.

Jquery assiging class to th in a table

You had thead in your selector, but there is no thead in your table. Also you had your selectors backwards. As you mentioned above, you wanted to be adding the tr class to the th, not vice-versa (although your comment seems to contradict what you wrote up above).

$('tr th').each(function(index){     if($('tr td').eq(index).attr('class') != ''){         // get the class of the td         var tdClass = $('tr td').eq(index).attr('class');         // add it to this th         $(this).addClass(tdClass );     } }); 

Fiddle

How do I clear all options in a dropdown box?

To remove the options of an HTML element of select, you can utilize the remove() method:

function removeOptions(selectElement) {
   var i, L = selectElement.options.length - 1;
   for(i = L; i >= 0; i--) {
      selectElement.remove(i);
   }
}

// using the function:
removeOptions(document.getElementById('DropList'));

It's important to remove the options backwards; as the remove() method rearranges the options collection. This way, it's guaranteed that the element to be removed still exists!

How to prevent a double-click using jQuery?

I found that most solutions didn't work with clicks on elements like Labels or DIV's (eg. when using Kendo controls). So I made this simple solution:

function isDoubleClicked(element) {
    //if already clicked return TRUE to indicate this click is not allowed
    if (element.data("isclicked")) return true;

    //mark as clicked for 1 second
    element.data("isclicked", true);
    setTimeout(function () {
        element.removeData("isclicked");
    }, 1000);

    //return FALSE to indicate this click was allowed
    return false;
}

Use it on the place where you have to decide to start an event or not:

$('#button').on("click", function () {
    if (isDoubleClicked($(this))) return;

    ..continue...
});

How do I get an apk file from an Android device?

Try this one liner bash command to backup all your apps:

for package in $(adb shell pm list packages -3 | tr -d '\r' | sed 's/package://g'); do apk=$(adb shell pm path $package | tr -d '\r' | sed 's/package://g'); echo "Pulling $apk"; adb pull -p $apk "$package".apk; done

This command is derived from Firelord's script. I just renamed all apks to their package names for solving the issue with elcuco's script, i.e the same base.apk file getting overwritten on Android 6.0 "Marshmallow" and above.

Note that this command backs up only 3rd party apps, coz I don't see the point of backing up built-in apps. But if you wanna backup system apps too, just omit the -3 option.

How can I embed a YouTube video on GitHub wiki pages?

Markdown does not officially support video embeddings but you can embed raw HTML in it. I tested out with GitHub Pages and it works flawlessly.

  1. Go to the Video page on YouTube and click on the Share Button
  2. Choose Embed
  3. Copy and Paste the HTML snippet in your markdown

The snippet looks like:

    <iframe width="560" height="315"
src="https://www.youtube.com/embed/MUQfKFzIOeU" 
frameborder="0" 
allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" 
allowfullscreen></iframe>

PS: You can check out the live preview here

How to put a jar in classpath in Eclipse?

Right click your project in eclipse, build path -> add external jars.

How can I remove the top and right axis in matplotlib?

If you need to remove it from all your plots, you can remove spines in style settings (style sheet or rcParams). E.g:

import matplotlib as mpl

mpl.rcParams['axes.spines.right'] = False
mpl.rcParams['axes.spines.top'] = False

If you want to remove all spines:

mpl.rcParams['axes.spines.left'] = False
mpl.rcParams['axes.spines.right'] = False
mpl.rcParams['axes.spines.top'] = False
mpl.rcParams['axes.spines.bottom'] = False

How to convert jsonString to JSONObject in Java

To anyone still looking for an answer:

JSONParser parser = new JSONParser();
JSONObject json = (JSONObject) parser.parse(stringToParse);

Sass Nesting for :hover does not work

For concatenating selectors together when nesting, you need to use the parent selector (&):

.class {
    margin:20px;
    &:hover {
        color:yellow;
    }
}

How to echo (or print) to the js console with php

For something simple that work for arrays , strings , and objects I builed this function:

function console_testing($var){

    $var = json_encode($var,JSON_UNESCAPED_UNICODE);

    $output = <<<EOT
    <script>
        console.log($var); 
    </script>
EOT;

    echo $output;

}

Why javascript getTime() is not a function?

For all those who came here and did indeed use Date typed Variables, here is the solution I found. It does also apply to TypeScript.

I was facing this error because I tried to compare two dates using the following Method

var res = dat1.getTime() > dat2.getTime(); // or any other comparison operator

However Im sure I used a Date object, because Im using angularjs with typescript, and I got the data from a typed API call.

Im not sure why the error is raised, but I assume that because my Object was created by JSON deserialisation, possibly the getTime() method was simply not added to the prototype.

Solution

In this case, recreating a date-Object based on your dates will fix the issue.

var res = new Date(dat1).getTime() > new Date(dat2).getTime()

Edit:

I was right about this. Types will be cast to the according type but they wont be instanciated. Hence there will be a string cast to a date, which will obviously result in a runtime exception.

The trick is, if you use interfaces with non primitive only data such as dates or functions, you will need to perform a mapping after your http request.

class Details {
    description: string;
    date: Date;
    score: number;
    approved: boolean;

    constructor(data: any) {
      Object.assign(this, data);
    }
}

and to perform the mapping:

public getDetails(id: number): Promise<Details> {
    return this.http
               .get<Details>(`${this.baseUrl}/api/details/${id}`)
               .map(response => new Details(response.json()))
               .toPromise();
}

for arrays use:

public getDetails(): Promise<Details[]> {
    return this.http
               .get<Details>(`${this.baseUrl}/api/details`)
               .map(response => {
                   const array = JSON.parse(response.json()) as any[];
                   const details = array.map(data => new Details(data));
                   return details;
               })
               .toPromise();
}

For credits and further information about this topic follow the link.

Adding items in a Listbox with multiple columns

select propety

Row Source Type => Value List

Code :

ListbName.ColumnCount=2

ListbName.AddItem "value column1;value column2"

What is the difference between a port and a socket?

A socket represents a single connection between two network applications. These two applications nominally run on different computers, but sockets can also be used for interprocess communication on a single computer. Applications can create multiple sockets for communicating with each other. Sockets are bidirectional, meaning that either side of the connection is capable of both sending and receiving data. Therefore a socket can be created theoretically at any level of the OSI model from 2 upwards. Programmers often use sockets in network programming, albeit indirectly. Programming libraries like Winsock hide many of the low-level details of socket programming. Sockets have been in widespread use since the early 1980s.

A port represents an endpoint or "channel" for network communications. Port numbers allow different applications on the same computer to utilize network resources without interfering with each other. Port numbers most commonly appear in network programming, particularly socket programming. Sometimes, though, port numbers are made visible to the casual user. For example, some Web sites a person visits on the Internet use a URL like the following:

http://www.mairie-metz.fr:8080/ In this example, the number 8080 refers to the port number used by the Web browser to connect to the Web server. Normally, a Web site uses port number 80 and this number need not be included with the URL (although it can be).

In IP networking, port numbers can theoretically range from 0 to 65535. Most popular network applications, though, use port numbers at the low end of the range (such as 80 for HTTP).

Note: The term port also refers to several other aspects of network technology. A port can refer to a physical connection point for peripheral devices such as serial, parallel, and USB ports. The term port also refers to certain Ethernet connection points, such as those on a hub, switch, or router.

ref http://compnetworking.about.com/od/basicnetworkingconcepts/l/bldef_port.htm

ref http://compnetworking.about.com/od/itinformationtechnology/l/bldef_socket.htm

Word wrapping in phpstorm

For Word Wrapping in Php Storm 2019.1.3 Just follow below steps:

from top nagivation menu

View -> Active Editor -> Soft-Wrap

that's it so simple.

ASP.NET MVC Conditional validation

There's a much better way to add conditional validation rules in MVC3; have your model inherit IValidatableObject and implement the Validate method:

public class Person : IValidatableObject
{
    public string Name { get; set; }
    public bool IsSenior { get; set; }
    public Senior Senior { get; set; }

    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext) 
    { 
        if (IsSenior && string.IsNullOrEmpty(Senior.Description)) 
            yield return new ValidationResult("Description must be supplied.");
    }
}

Read more at Introducing ASP.NET MVC 3 (Preview 1).

How do I launch a Git Bash window with particular working directory using a script?

In addition, Win10 gives you an option to open git bash from your working directory by right-clicking on your folder and selecting GitBash here.

enter image description here

How do I use namespaces with TypeScript external modules?

Candy Cup Analogy

Version 1: A cup for every candy

Let's say you wrote some code like this:

Mod1.ts

export namespace A {
    export class Twix { ... }
}

Mod2.ts

export namespace A {
    export class PeanutButterCup { ... }
}

Mod3.ts

export namespace A {
     export class KitKat { ... }
}

You've created this setup: enter image description here

Each module (sheet of paper) gets its own cup named A. This is useless - you're not actually organizing your candy here, you're just adding an additional step (taking it out of the cup) between you and the treats.


Version 2: One cup in the global scope

If you weren't using modules, you might write code like this (note the lack of export declarations):

global1.ts

namespace A {
    export class Twix { ... }
}

global2.ts

namespace A {
    export class PeanutButterCup { ... }
}

global3.ts

namespace A {
     export class KitKat { ... }
}

This code creates a merged namespace A in the global scope:

enter image description here

This setup is useful, but doesn't apply in the case of modules (because modules don't pollute the global scope).


Version 3: Going cupless

Going back to the original example, the cups A, A, and A aren't doing you any favors. Instead, you could write the code as:

Mod1.ts

export class Twix { ... }

Mod2.ts

export class PeanutButterCup { ... }

Mod3.ts

export class KitKat { ... }

to create a picture that looks like this:

enter image description here

Much better!

Now, if you're still thinking about how much you really want to use namespace with your modules, read on...


These Aren't the Concepts You're Looking For

We need to go back to the origins of why namespaces exist in the first place and examine whether those reasons make sense for external modules.

Organization: Namespaces are handy for grouping together logically-related objects and types. For example, in C#, you're going to find all the collection types in System.Collections. By organizing our types into hierarchical namespaces, we provide a good "discovery" experience for users of those types.

Name Conflicts: Namespaces are important to avoid naming collisions. For example, you might have My.Application.Customer.AddForm and My.Application.Order.AddForm -- two types with the same name, but a different namespace. In a language where all identifiers exist in the same root scope and all assemblies load all types, it's critical to have everything be in a namespace.

Do those reasons make sense in external modules?

Organization: External modules are already present in a file system, necessarily. We have to resolve them by path and filename, so there's a logical organization scheme for us to use. We can have a /collections/generic/ folder with a list module in it.

Name Conflicts: This doesn't apply at all in external modules. Within a module, there's no plausible reason to have two objects with the same name. From the consumption side, the consumer of any given module gets to pick the name that they will use to refer to the module, so accidental naming conflicts are impossible.


Even if you don't believe that those reasons are adequately addressed by how modules work, the "solution" of trying to use namespaces in external modules doesn't even work.

Boxes in Boxes in Boxes

A story:

Your friend Bob calls you up. "I have a great new organization scheme in my house", he says, "come check it out!". Neat, let's go see what Bob has come up with.

You start in the kitchen and open up the pantry. There are 60 different boxes, each labelled "Pantry". You pick a box at random and open it. Inside is a single box labelled "Grains". You open up the "Grains" box and find a single box labelled "Pasta". You open the "Pasta" box and find a single box labelled "Penne". You open this box and find, as you expect, a bag of penne pasta.

Slightly confused, you pick up an adjacent box, also labelled "Pantry". Inside is a single box, again labelled "Grains". You open up the "Grains" box and, again, find a single box labelled "Pasta". You open the "Pasta" box and find a single box, this one is labelled "Rigatoni". You open this box and find... a bag of rigatoni pasta.

"It's great!" says Bob. "Everything is in a namespace!".

"But Bob..." you reply. "Your organization scheme is useless. You have to open up a bunch of boxes to get to anything, and it's not actually any more convenient to find anything than if you had just put everything in one box instead of three. In fact, since your pantry is already sorted shelf-by-shelf, you don't need the boxes at all. Why not just set the pasta on the shelf and pick it up when you need it?"

"You don't understand -- I need to make sure that no one else puts something that doesn't belong in the 'Pantry' namespace. And I've safely organized all my pasta into the Pantry.Grains.Pasta namespace so I can easily find it"

Bob is a very confused man.

Modules are Their Own Box

You've probably had something similar happen in real life: You order a few things on Amazon, and each item shows up in its own box, with a smaller box inside, with your item wrapped in its own packaging. Even if the interior boxes are similar, the shipments are not usefully "combined".

Going with the box analogy, the key observation is that external modules are their own box. It might be a very complex item with lots of functionality, but any given external module is its own box.


Guidance for External Modules

Now that we've figured out that we don't need to use 'namespaces', how should we organize our modules? Some guiding principles and examples follow.

Export as close to top-level as possible

  • If you're only exporting a single class or function, use export default:

MyClass.ts

export default class SomeType {
  constructor() { ... }
}

MyFunc.ts

function getThing() { return 'thing'; }
export default getThing;

Consumption

import t from './MyClass';
import f from './MyFunc';
var x = new t();
console.log(f());

This is optimal for consumers. They can name your type whatever they want (t in this case) and don't have to do any extraneous dotting to find your objects.

  • If you're exporting multiple objects, put them all at top-level:

MyThings.ts

export class SomeType { ... }
export function someFunc() { ... }

Consumption

import * as m from './MyThings';
var x = new m.SomeType();
var y = m.someFunc();
  • If you're exporting a large number of things, only then should you use the module/namespace keyword:

MyLargeModule.ts

export namespace Animals {
  export class Dog { ... }
  export class Cat { ... }
}
export namespace Plants {
  export class Tree { ... }
}

Consumption

import { Animals, Plants} from './MyLargeModule';
var x = new Animals.Dog();

Red Flags

All of the following are red flags for module structuring. Double-check that you're not trying to namespace your external modules if any of these apply to your files:

  • A file whose only top-level declaration is export module Foo { ... } (remove Foo and move everything 'up' a level)
  • A file that has a single export class or export function that isn't export default
  • Multiple files that have the same export module Foo { at top-level (don't think that these are going to combine into one Foo!)

Convert bytes to int?

Assuming you're on at least 3.2, there's a built in for this:

int.from_bytes( bytes, byteorder, *, signed=False )

...

The argument bytes must either be a bytes-like object or an iterable producing bytes.

The byteorder argument determines the byte order used to represent the integer. If byteorder is "big", the most significant byte is at the beginning of the byte array. If byteorder is "little", the most significant byte is at the end of the byte array. To request the native byte order of the host system, use sys.byteorder as the byte order value.

The signed argument indicates whether two’s complement is used to represent the integer.


## Examples:
int.from_bytes(b'\x00\x01', "big")                         # 1
int.from_bytes(b'\x00\x01', "little")                      # 256

int.from_bytes(b'\x00\x10', byteorder='little')            # 4096
int.from_bytes(b'\xfc\x00', byteorder='big', signed=True)  #-1024

Loop in Jade (currently known as "Pug") template engine

for example:

- for (var i = 0; i < 10; ++i) {
  li= array[i]
- }

you may see https://github.com/visionmedia/jade for detailed document.

How to find index of all occurrences of element in array?

findIndex retrieves only the first index which matches callback output. You can implement your own findIndexes by extending Array , then casting your arrays to the new structure .

_x000D_
_x000D_
class EnhancedArray extends Array {_x000D_
  findIndexes(where) {_x000D_
    return this.reduce((a, e, i) => (where(e, i) ? a.concat(i) : a), []);_x000D_
  }_x000D_
}_x000D_
   /*----Working with simple data structure (array of numbers) ---*/_x000D_
_x000D_
//existing array_x000D_
let myArray = [1, 3, 5, 5, 4, 5];_x000D_
_x000D_
//cast it :_x000D_
myArray = new EnhancedArray(...myArray);_x000D_
_x000D_
//run_x000D_
console.log(_x000D_
   myArray.findIndexes((e) => e===5)_x000D_
)_x000D_
/*----Working with Array of complex items structure-*/_x000D_
_x000D_
let arr = [{name: 'Ahmed'}, {name: 'Rami'}, {name: 'Abdennour'}];_x000D_
_x000D_
arr= new EnhancedArray(...arr);_x000D_
_x000D_
_x000D_
console.log(_x000D_
  arr.findIndexes((o) => o.name.startsWith('A'))_x000D_
)
_x000D_
_x000D_
_x000D_

PHP returning JSON to JQUERY AJAX CALL

You can return json in PHP this way:

header('Content-Type: application/json');
echo json_encode(array('foo' => 'bar'));
exit;

Subscript out of range error in this Excel VBA script

This looks a little better than your previous version but get rid of that .Activate on that line and see if you still get that error.

Dim sh1 As Worksheet
set sh1 = Workbooks.Add(filenum(lngPosition) & ".csv")

Creates a worksheet object. Not until you create that object do you want to start working with it. Once you have that object you can do the following:

sh1.Range("A69").Paste
sh1.Range("A69").Select

The sh1. explicitely tells Excel which object you are saying to work with... otherwise if you start selecting other worksheets while this code is running you could wind up pasting data to the wrong place.

Get list of data-* attributes using javascript / jQuery

or convert gilly3's excellent answer to a jQuery method:

$.fn.info = function () {
    var data = {};
    [].forEach.call(this.get(0).attributes, function (attr) {
        if (/^data-/.test(attr.name)) {
            var camelCaseName = attr.name.substr(5).replace(/-(.)/g, function ($0, $1) {
                return $1.toUpperCase();
            });
            data[camelCaseName] = attr.value;
        }
    });
    return data;
}

Using: $('.foo').info();

Hide div by default and show it on click with bootstrap

Try this one:

<button class="button" onclick="$('#target').toggle();">
    Show/Hide
</button>
<div id="target" style="display: none">
    Hide show.....
</div>

How does GPS in a mobile phone work exactly?

GPS, the Global Positioning System run by the United States Military, is free for civilian use, though the reality is that we're paying for it with tax dollars.

However, GPS on cell phones is a bit more murky. In general, it won't cost you anything to turn on the GPS in your cell phone, but when you get a location it usually involves the cell phone company in order to get it quickly with little signal, as well as get a location when the satellites aren't visible (since the gov't requires a fix even if the satellites aren't visible for emergency 911 purposes). It uses up some cellular bandwidth. This also means that for phones without a regular GPS receiver, you cannot use the GPS at all if you don't have cell phone service.

For this reason most cell phone companies have the GPS in the phone turned off except for emergency calls and for services they sell you (such as directions).

This particular kind of GPS is called assisted GPS (AGPS), and there are several levels of assistance used.

GPS

A normal GPS receiver listens to a particular frequency for radio signals. Satellites send time coded messages at this frequency. Each satellite has an atomic clock, and sends the current exact time as well.

The GPS receiver figures out which satellites it can hear, and then starts gathering those messages. The messages include time, current satellite positions, and a few other bits of information. The message stream is slow - this is to save power, and also because all the satellites transmit on the same frequency and they're easier to pick out if they go slow. Because of this, and the amount of information needed to operate well, it can take 30-60 seconds to get a location on a regular GPS.

When it knows the position and time code of at least 3 satellites, a GPS receiver can assume it's on the earth's surface and get a good reading. 4 satellites are needed if you aren't on the ground and you want altitude as well.

AGPS

As you saw above, it can take a long time to get a position fix with a normal GPS. There are ways to speed this up, but unless you're carrying an atomic clock with you all the time, or leave the GPS on all the time, then there's always going to be a delay of between 5-60 seconds before you get a location.

In order to save cost, most cell phones share the GPS receiver components with the cellular components, and you can't get a fix and talk at the same time. People don't like that (especially when there's an emergency) so the lowest form of GPS does the following:

  1. Get some information from the cell phone company to feed to the GPS receiver - some of this is gross positioning information based on what cellular towers can 'hear' your phone, so by this time they already phone your location to within a city block or so.
  2. Switch from cellular to GPS receiver for 0.1 second (or some small, practically unoticable period of time) and collect the raw GPS data (no processing on the phone).
  3. Switch back to the phone mode, and send the raw data to the phone company
  4. The phone company processes that data (acts as an offline GPS receiver) and send the location back to your phone.

This saves a lot of money on the phone design, but it has a heavy load on cellular bandwidth, and with a lot of requests coming it requires a lot of fast servers. Still, overall it can be cheaper and faster to implement. They are reluctant, however, to release GPS based features on these phones due to this load - so you won't see turn by turn navigation here.

More recent designs include a full GPS chip. They still get data from the phone company - such as current location based on tower positioning, and current satellite locations - this provides sub 1 second fix times. This information is only needed once, and the GPS can keep track of everything after that with very little power. If the cellular network is unavailable, then they can still get a fix after awhile. If the GPS satellites aren't visible to the receiver, then they can still get a rough fix from the cellular towers.

But to completely answer your question - it's as free as the phone company lets it be, and so far they do not charge for it at all. I doubt that's going to change in the future. In the higher end phones with a full GPS receiver you may even be able to load your own software and access it, such as with mologogo on a motorola iDen phone - the J2ME development kit is free, and the phone is only $40 (prepaid phone with $5 credit). Unlimited internet is about $10 a month, so for $40 to start and $10 a month you can get an internet tracking system. (Prices circa August 2008)

It's only going to get cheaper and more full featured from here on out...

Re: Google maps and such

Yes, Google maps and all other cell phone mapping systems require a data connection of some sort at varying times during usage. When you move far enough in one direction, for instance, it'll request new tiles from its server. Your average phone doesn't have enough storage to hold a map of the US, nor the processor power to render it nicely. iPhone would be able to if you wanted to use the storage space up with maps, but given that most iPhones have a full time unlimited data plan most users would rather use that space for other things.

Adding integers to an int array

To add an element to an array you need to use the format:

array[index] = element;

Where array is the array you declared, index is the position where the element will be stored, and element is the item you want to store in the array.

In your code, you'd want to do something like this:

int[] num = new int[args.length];
for (int i = 0; i < args.length; i++) {
    int neki = Integer.parseInt(args[i]);
    num[i] = neki;
}

The add() method is available for Collections like List and Set. You could use it if you were using an ArrayList (see the documentation), for example:

List<Integer> num = new ArrayList<>();
for (String s : args) {
    int neki = Integer.parseInt(s);
    num.add(neki);
}

javascript - match string against the array of regular expressions

let expressions = [ '/something/', '/something_else/', '/and_something_else/'];

let str = 'else';

here will be the check for following expressions:

if( expressions.find(expression => expression.includes(str) ) ) {

}

using Array .find() method to traverse array and .include to check substring

Compare 2 JSON objects

Simply parsing the JSON and comparing the two objects is not enough because it wouldn't be the exact same object references (but might be the same values).

You need to do a deep equals.

From http://threebit.net/mail-archive/rails-spinoffs/msg06156.html - which seems the use jQuery.

Object.extend(Object, {
   deepEquals: function(o1, o2) {
     var k1 = Object.keys(o1).sort();
     var k2 = Object.keys(o2).sort();
     if (k1.length != k2.length) return false;
     return k1.zip(k2, function(keyPair) {
       if(typeof o1[keyPair[0]] == typeof o2[keyPair[1]] == "object"){
         return deepEquals(o1[keyPair[0]], o2[keyPair[1]])
       } else {
         return o1[keyPair[0]] == o2[keyPair[1]];
       }
     }).all();
   }
});

Usage:

var anObj = JSON.parse(jsonString1);
var anotherObj= JSON.parse(jsonString2);

if (Object.deepEquals(anObj, anotherObj))
   ...

Replacement for deprecated sizeWithFont: in iOS 7?

Multi-line labels using dynamic height may require additional information to set the size properly. You can use sizeWithAttributes with UIFont and NSParagraphStyle to specify both the font and the line-break mode.

You would define the Paragraph Style and use an NSDictionary like this:

// set paragraph style
NSMutableParagraphStyle *style = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
[style setLineBreakMode:NSLineBreakByWordWrapping];
// make dictionary of attributes with paragraph style
NSDictionary *sizeAttributes        = @{NSFontAttributeName:myLabel.font, NSParagraphStyleAttributeName: style};
// get the CGSize
CGSize adjustedSize = CGSizeMake(label.frame.size.width, CGFLOAT_MAX);

// alternatively you can also get a CGRect to determine height
CGRect rect = [myLabel.text boundingRectWithSize:adjustedSize
                                                         options:NSStringDrawingUsesLineFragmentOrigin
                                                      attributes:sizeAttributes
                                                         context:nil];

You can use the CGSize 'adjustedSize' or CGRect as rect.size.height property if you're looking for the height.

More info on NSParagraphStyle here: https://developer.apple.com/library/mac/documentation/cocoa/reference/applicationkit/classes/NSParagraphStyle_Class/Reference/Reference.html

Iterating through a variable length array

here is an example, where the length of the array is changed during execution of the loop

import java.util.ArrayList;
public class VariableArrayLengthLoop {

public static void main(String[] args) {

    //create new ArrayList
    ArrayList<String> aListFruits = new ArrayList<String>();

    //add objects to ArrayList
    aListFruits.add("Apple");
    aListFruits.add("Banana");
    aListFruits.add("Orange");
    aListFruits.add("Strawberry");

    //iterate ArrayList using for loop
    for(int i = 0; i < aListFruits.size(); i++){

        System.out.println( aListFruits.get(i) + " i = "+i );
         if ( i == 2 ) {
                aListFruits.add("Pineapple");  
                System.out.println( "added now a Fruit to the List "); 
                }
        }
    }
}

What does it mean if a Python object is "subscriptable" or not?

It basically means that the object implements the __getitem__() method. In other words, it describes objects that are "containers", meaning they contain other objects. This includes strings, lists, tuples, and dictionaries.

How to loop through a checkboxlist and to find what's checked and not checked?

This will give a list of selected

List<ListItem> items =  checkboxlist.Items.Cast<ListItem>().Where(n => n.Selected).ToList();

This will give a list of the selected boxes' values (change Value for Text if that is wanted):

var values =  checkboxlist.Items.Cast<ListItem>().Where(n => n.Selected).Select(n => n.Value ).ToList()

adb remount permission denied, but able to access super user in shell -- android

Try with an API lvl 28 emulator (Android 9). I was trying with api lvl 29 and kept getting errors.

java.sql.SQLException: No suitable driver found for jdbc:microsoft:sqlserver

Following is a simple code to read from SQL database. Database names is "database1". Table name is "table1". It contain two columns "uname" and "pass". Dont forget to add "sqljdbc4.jar" to your project. Download sqljdbc4.jar

public class NewClass {

    public static void main(String[] args) {

        Connection conn = null;
        String dbName = "database1";
        String serverip="192.168.100.100";
        String serverport="1433";
        String url = "jdbc:sqlserver://"+serverip+"\\SQLEXPRESS:"+serverport+";databaseName="+dbName+"";
        Statement stmt = null;
        ResultSet result = null;
        String driver = "com.microsoft.sqlserver.jdbc.SQLServerDriver";
        String databaseUserName = "admin";
        String databasePassword = "root";
        try {
            Class.forName(driver).newInstance();
            conn = DriverManager.getConnection(url, databaseUserName, databasePassword);
            stmt = conn.createStatement();
            result = null;
            String pa,us;
            result = stmt.executeQuery("select * from table1 ");

            while (result.next()) {
                us=result.getString("uname");
                pa = result.getString("pass");              
                System.out.println(us+"  "+pa);
            }

            conn.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

How do I create a random alpha-numeric string in C++?

Mehrdad Afshari's answer would do the trick, but I found it a bit too verbose for this simple task. Look-up tables can sometimes do wonders:

#include <iostream>
#include <ctime>
#include <unistd.h>

using namespace std;

string gen_random(const int len) {
    
    string tmp_s;
    static const char alphanum[] =
        "0123456789"
        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        "abcdefghijklmnopqrstuvwxyz";
    
    srand( (unsigned) time(NULL) * getpid());

    tmp_s.reserve(len);

    for (int i = 0; i < len; ++i) 
        tmp_s += alphanum[rand() % (sizeof(alphanum) - 1)];
    
    
    return tmp_s;
    
}

int main(int argc, char *argv[]) {
    
    cout << gen_random(12) << endl;
    
    return 0;
}

Javascript: Uncaught TypeError: Cannot call method 'addEventListener' of null

Your code is in the <head> => runs before the elements are rendered, so document.getElementById('compute'); returns null, as MDN promise...

element = document.getElementById(id);
element is a reference to an Element object, or null if an element with the specified ID is not in the document.

MDN

Solutions:

  1. Put the scripts in the bottom of the page.
  2. Call the attach code in the load event.
  3. Use jQuery library and it's DOM ready event.

What is the jQuery ready event and why is it needed?
(why no just JavaScript's load event):

While JavaScript provides the load event for executing code when a page is rendered, this event does not get triggered until all assets such as images have been completely received. In most cases, the script can be run as soon as the DOM hierarchy has been fully constructed. The handler passed to .ready() is guaranteed to be executed after the DOM is ready, so this is usually the best place to attach all other event handlers...
...

ready docs

How can I add an element after another element?

try

.insertAfter()

here

$(content).insertAfter('#bla');

UINavigationBar Hide back Button Text

The following method works on iOS 11 and is safe to not crash on other iOS versions. Doing this may get your app rejected in App Store review since both UIModernBarButton and UIBackButtonContainerView are private APIs. Place in AppDelegate.

    if
        let UIModernBarButton = NSClassFromString("_UIModernBarButton") as? UIButton.Type,
        let UIBackButtonContainerView = NSClassFromString("_UIBackButtonContainerView") as? UIView.Type {

        let backButton = UIModernBarButton.appearance(whenContainedInInstancesOf: [UIBackButtonContainerView.self])
        backButton.setTitleColor(.clear, for: .normal)
    }

Search text in fields in every table of a MySQL database

You could use

SHOW TABLES;

Then get the columns in those tables (in a loop) with

SHOW COLUMNS FROM table;

and then with that info create many many queries which you can also UNION if you need.

But this is extremely heavy on the database. Specially if you are doing a LIKE search.

What's the difference between Instant and LocalDateTime?

You are wrong about LocalDateTime: it does not store any time-zone information and it has nanosecond precision. Quoting the Javadoc (emphasis mine):

A date-time without a time-zone in the ISO-8601 calendar system, such as 2007-12-03T10:15:30.

LocalDateTime is an immutable date-time object that represents a date-time, often viewed as year-month-day-hour-minute-second. Other date and time fields, such as day-of-year, day-of-week and week-of-year, can also be accessed. Time is represented to nanosecond precision. For example, the value "2nd October 2007 at 13:45.30.123456789" can be stored in a LocalDateTime.

The difference between the two is that Instant represents an offset from the Epoch (01-01-1970) and, as such, represents a particular instant on the time-line. Two Instant objects created at the same moment in two different places of the Earth will have exactly the same value.

how to open .mat file without using MATLAB?

A .mat-file is a compressed binary file. It is not possible to open it with a text editor (except you have a special plugin as Dennis Jaheruddin says). Otherwise you will have to convert it into a text file (csv for example) with a script. This could be done by python for example: Read .mat files in Python.

jQuery get the rendered height of an element?

Try one of:

var h = document.getElementById('someDiv').clientHeight;
var h = document.getElementById('someDiv').offsetHeight;
var h = document.getElementById('someDiv').scrollHeight;

clientHeight includes the height and vertical padding.

offsetHeight includes the height, vertical padding, and vertical borders.

scrollHeight includes the height of the contained document (would be greater than just height in case of scrolling), vertical padding, and vertical borders.

How does spring.jpa.hibernate.ddl-auto property exactly work in Spring?

For the record, the spring.jpa.hibernate.ddl-auto property is Spring Data JPA specific and is their way to specify a value that will eventually be passed to Hibernate under the property it knows, hibernate.hbm2ddl.auto.

The values create, create-drop, validate, and update basically influence how the schema tool management will manipulate the database schema at startup.

For example, the update operation will query the JDBC driver's API to get the database metadata and then Hibernate compares the object model it creates based on reading your annotated classes or HBM XML mappings and will attempt to adjust the schema on-the-fly.

The update operation for example will attempt to add new columns, constraints, etc but will never remove a column or constraint that may have existed previously but no longer does as part of the object model from a prior run.

Typically in test case scenarios, you'll likely use create-drop so that you create your schema, your test case adds some mock data, you run your tests, and then during the test case cleanup, the schema objects are dropped, leaving an empty database.

In development, it's often common to see developers use update to automatically modify the schema to add new additions upon restart. But again understand, this does not remove a column or constraint that may exist from previous executions that is no longer necessary.

In production, it's often highly recommended you use none or simply don't specify this property. That is because it's common practice for DBAs to review migration scripts for database changes, particularly if your database is shared across multiple services and applications.

SQL select join: is it possible to prefix all columns as 'prefix.*'?

I totally understand your problem about duplicated field names.

I needed that too until I coded my own function to solve it. If you are using PHP you can use it, or code yours in the language you are using for if you have this following facilities.

The trick here is that mysql_field_table() returns the table name and mysql_field_name() the field for each row in the result if it's got with mysql_num_fields() so you can mix them in a new array.

This prefixes all columns ;)

Regards,

function mysql_rows_with_columns($query) {
    $result = mysql_query($query);
    if (!$result) return false; // mysql_error() could be used outside
    $fields = mysql_num_fields($result);
    $rows = array();
    while ($row = mysql_fetch_row($result)) { 
        $newRow = array();
        for ($i=0; $i<$fields; $i++) {
            $table = mysql_field_table($result, $i);
            $name = mysql_field_name($result, $i);
            $newRow[$table . "." . $name] = $row[$i];
        }
        $rows[] = $newRow;
    }
    mysql_free_result($result);
    return $rows;
}

How do you find the first key in a dictionary?

Well as simple, the answer according to me will be

first = list(prices)[0]

converting the dictionary to list will output the keys and we will select the first key from the list.

How do you perform wireless debugging in Xcode 9 with iOS 11, Apple TV 4K, etc?

Network debugging requires Xcode 9.0 or later running on macOS 10.12.4 or later, and on the device, requires iOS 11.0 or later, or tvOS 11.0 or later.

iPhone

iOS 11 won't be available for 32bit devices, i.e. iPhone 5 and iPhone 5c and below. The first 64bit iPhone is 5s.

iPad

iPad mini 2 will be the oldest iPad with iOS 11 support.

iPod

iPod needs to be an iPod 6 to be able to run iOS.

If you use your devices not only for developing but also for production, be warned that a beta OS is not for the faint hearted ;-)

IntelliJ: Working on multiple projects

Yes, your intuition was good. You shouldn't use three instances of intellij. You can open one Project and add other 'parts' of application as Modules. Add them via project browser, default hotkey is alt+1

How do I deserialize a complex JSON object in C# .NET?

Should just be this:

var jobject = JsonConvert.DeserializeObject<RootObject>(jsonstring);

You can paste the json string to here: http://json2csharp.com/ to check your classes are correct.

Transposing a 2D-array in JavaScript

array[0].map((_, colIndex) => array.map(row => row[colIndex]));

map calls a provided callback function once for each element in an array, in order, and constructs a new array from the results. callback is invoked only for indexes of the array which have assigned values; it is not invoked for indexes which have been deleted or which have never been assigned values.

callback is invoked with three arguments: the value of the element, the index of the element, and the Array object being traversed. [source]

MySQL fails on: mysql "ERROR 1524 (HY000): Plugin 'auth_socket' is not loaded"

You can try with the below commands:

hduser@master:~$ sudo /etc/init.d/mysql stop
[ ok ] Stopping mysql (via systemctl): mysql.service.
hduser@master:~$ sudo /etc/init.d/mysql start
[ ok ] Starting mysql (via systemctl): mysql.service.

pip: no module named _internal

my solution: first step like most other answer:

curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
python2.7 get-pip.py --force-reinstall

second, add soft link

sudo ln -s /usr/local/bin/pip /usr/bin/pip

(unicode error) 'unicodeescape' codec can't decode bytes in position 2-3: truncated \UXXXXXXXX escape

This error occurs because you are using a normal string as a path. You can use one of the three following solutions to fix your problem:

1: Just put r before your normal string it converts normal string to raw string:

pandas.read_csv(r"C:\Users\DeePak\Desktop\myac.csv")

2:

pandas.read_csv("C:/Users/DeePak/Desktop/myac.csv")

3:

pandas.read_csv("C:\\Users\\DeePak\\Desktop\\myac.csv")

Java Look and Feel (L&F)

You can also use JTattoo (http://www.jtattoo.net/), it has a couple of cool themes that can be used.

Just download the jar and import it into your classpath, or add it as a maven dependency:

<dependency>
        <groupId>com.jtattoo</groupId>
        <artifactId>JTattoo</artifactId>
        <version>1.6.11</version>
</dependency>

Here is a list of some of the cool themes they have available:

  • com.jtattoo.plaf.acryl.AcrylLookAndFeel
  • com.jtattoo.plaf.aero.AeroLookAndFeel
  • com.jtattoo.plaf.aluminium.AluminiumLookAndFeel
  • com.jtattoo.plaf.bernstein.BernsteinLookAndFeel
  • com.jtattoo.plaf.fast.FastLookAndFeel
  • com.jtattoo.plaf.graphite.GraphiteLookAndFeel
  • com.jtattoo.plaf.hifi.HiFiLookAndFeel
  • com.jtattoo.plaf.luna.LunaLookAndFeel
  • com.jtattoo.plaf.mcwin.McWinLookAndFeel
  • com.jtattoo.plaf.mint.MintLookAndFeel
  • com.jtattoo.plaf.noire.NoireLookAndFeel
  • com.jtattoo.plaf.smart.SmartLookAndFeel
  • com.jtattoo.plaf.texture.TextureLookAndFeel
  • com.jtattoo.plaf.custom.flx.FLXLookAndFeel

Regards

Android + Pair devices via bluetooth programmatically

if you have the BluetoothDevice object you can create bond(pair) from api 19 onwards with bluetoothDevice.createBond() method.

Edit

for callback, if the request was accepted or denied you will have to create a BroadcastReceiver with BluetoothDevice.ACTION_BOND_STATE_CHANGED action

ProcessStartInfo hanging on "WaitForExit"? Why?

I know that this is supper old but, after reading this whole page none of the solutions was working for me, although I didn't try Muhammad Rehan as the code was a little hard to follow, although I guess he was on the right track. When I say it didn't work that's not entirely true, sometimes it would work fine, I guess it is something to do with the length of the output before an EOF mark.

Anyway, the solution that worked for me was to use different threads to read the StandardOutput and StandardError and write the messages.

        StreamWriter sw = null;
        var queue = new ConcurrentQueue<string>();

        var flushTask = new System.Timers.Timer(50);
        flushTask.Elapsed += (s, e) =>
        {
            while (!queue.IsEmpty)
            {
                string line = null;
                if (queue.TryDequeue(out line))
                    sw.WriteLine(line);
            }
            sw.FlushAsync();
        };
        flushTask.Start();

        using (var process = new Process())
        {
            try
            {
                process.StartInfo.FileName = @"...";
                process.StartInfo.Arguments = $"...";
                process.StartInfo.UseShellExecute = false;
                process.StartInfo.RedirectStandardOutput = true;
                process.StartInfo.RedirectStandardError = true;

                process.Start();

                var outputRead = Task.Run(() =>
                {
                    while (!process.StandardOutput.EndOfStream)
                    {
                        queue.Enqueue(process.StandardOutput.ReadLine());
                    }
                });

                var errorRead = Task.Run(() =>
                {
                    while (!process.StandardError.EndOfStream)
                    {
                        queue.Enqueue(process.StandardError.ReadLine());
                    }
                });

                var timeout = new TimeSpan(hours: 0, minutes: 10, seconds: 0);

                if (Task.WaitAll(new[] { outputRead, errorRead }, timeout) &&
                    process.WaitForExit((int)timeout.TotalMilliseconds))
                {
                    if (process.ExitCode != 0)
                    {
                        throw new Exception($"Failed run... blah blah");
                    }
                }
                else
                {
                    throw new Exception($"process timed out after waiting {timeout}");
                }
            }
            catch (Exception e)
            {
                throw new Exception($"Failed to succesfully run the process.....", e);
            }
        }
    }

Hope this helps someone, who thought this could be so hard!

How to get a shell environment variable in a makefile?

for those who want some official document to confirm the behavior

Variables in make can come from the environment in which make is run. Every environment variable that make sees when it starts up is transformed into a make variable with the same name and value. However, an explicit assignment in the makefile, or with a command argument, overrides the environment. (If the ‘-e’ flag is specified, then values from the environment override assignments in the makefile.

https://www.gnu.org/software/make/manual/html_node/Environment.html

Can't open and lock privilege tables: Table 'mysql.user' doesn't exist

You have to initialize the data directory by running the following command

mysqld --initialize [with random root password]

mysqld --initialize-insecure [with blank root password]

Java: Find .txt files in specified folder

Here is my platform specific code(unix)

public static List<File> findFiles(String dir, String... names)
    {
        LinkedList<String> command = new LinkedList<String>();
        command.add("/usr/bin/find");
        command.add(dir);
        List<File> result = new LinkedList<File>();
        if (names.length > 1)
            {
                List<String> newNames = new LinkedList<String>(Arrays.asList(names));
                String first = newNames.remove(0);
                command.add("-name");
                command.add(first);
                for (String newName : newNames)
                    {
                        command.add("-or");
                        command.add("-name");
                        command.add(newName);
                    }
            }
        else if (names.length > 0)
            {
                command.add("-name");
                command.add(names[0]);
            }
        try
            {
                ProcessBuilder pb = new ProcessBuilder(command);
                Process p = pb.start();
                p.waitFor();
                InputStream is = p.getInputStream();
                InputStreamReader isr = new InputStreamReader(is);
                BufferedReader br = new BufferedReader(isr);
                String line;
                while ((line = br.readLine()) != null)
                    {
                        // System.err.println(line);
                        result.add(new File(line));
                    }
                p.destroy();
            }
        catch (Exception e)
            {
                e.printStackTrace();
            }
        return result;
    }

Clear text in EditText when entered

i don't know what mistakes i did while implementing the above solutions, bt they were unsuccessful for me

txtDeck.setOnFocusChangeListener(new OnFocusChangeListener() {
    @Override       
    public void onFocusChange(View v, boolean hasFocus) {
        txtDeck.setText("");
    }
});

This works for me,

How do I disable orientation change on Android?

In Visual Studio Xamarin:

  1. Add:

using Android.Content.PM; to you activity namespace list.

  1. Add:

[Activity(ScreenOrientation = Android.Content.PM.ScreenOrientation.Portrait)]

as an attribute to you class, like that:

[Activity(ScreenOrientation = ScreenOrientation.Portrait)]
public class MainActivity : Activity
{...}

How to check whether Kafka Server is running?

You can install Kafkacat tool on your machine

For example on Ubuntu You can install it using

apt-get install kafkacat

once kafkacat is installed then you can use following command to connect it

kafkacat -b <your-ip-address>:<kafka-port> -t test-topic
  • Replace <your-ip-address> with your machine ip
  • <kafka-port> can be replaced by the port on which kafka is running. Normally it is 9092

once you run the above command and if kafkacat is able to make the connection then it means that kafka is up and running

Zookeeper connection error

This is a common issue if the Zookeeper server is not running or no longer running (i.e. it crashed after you started it).

So first, check that you have the Zookeeper server running. A simple way to check is grep the running processes:

# ps -ef | grep zookeeper

(run this a couple of times to see if the same process ID is still there. its possible it keep restarting with a new process ID. Alternatively you can use 'systemctl status zookeeper' if your Linux distro support systemd)

You should see the process running as a java process:

# ps -ef | grep zookeeper
root       492     0  0 00:01 pts/1    00:00:00 java -Dzookeeper.log.dir=. -Dzookeeper.root.logger=INFO,CONSOLE -cp /root/zookeeper-3.5.0-alpha/bin/../build/classes:/root/zookeeper-3.5.0-alpha/bin/../build/lib/*.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/slf4j-log4j12-1.7.5.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/slf4j-api-1.7.5.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/servlet-api-2.5-20081211.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/netty-3.7.0.Final.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/log4j-1.2.16.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/jline-2.11.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/jetty-util-6.1.26.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/jetty-6.1.26.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/javacc.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/jackson-mapper-asl-1.9.11.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/jackson-core-asl-1.9.11.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/commons-cli-1.2.jar:/root/zookeeper-3.5.0-alpha/bin/../zookeeper-3.5.0-alpha.jar:/root/zookeeper-3.5.0-alpha/bin/../src/java/lib/*.jar:/root/zookeeper-3.5.0-alpha/bin/../conf: -Xmx1000m -Xmx1000m -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.local.only=false org.apache.zookeeper.server.quorum.QuorumPeerMain /root/zookeeper-3.5.0-alpha/bin/../conf/zoo.cfg

If its not there, then there's likely something in the zookeeper log file indicating the issue.

To find the zookeeper log file, you should first figure out where its configured for logging. In my case I have zookeeper installed under my root directory (not suggesting you install it there):

[root@centos6_zookeeper conf]# pwd
/root/zookeeper-3.5.0-alpha/conf

And you can find the log setting in this file:

[root@centos6_zookeeper conf]# grep "zookeeper.log" log4j.properties 
zookeeper.log.dir=/var/log
zookeeper.log.file=zookeeper.log
zookeeper.log.threshold=INFO
zookeeper.log.maxfilesize=256MB
zookeeper.log.maxbackupindex=20

So Zookeeper is configured to log under /var/log.

Then there's usually a zookeeper.log and/or zookeeper.out file which should indicate your startup error.

CSS Input field text color of inputted text

To add color to an input, Use the following css code:

input{
     color: black;
}

How to change default format at created_at and updated_at value laravel

You can also try like this.

Use Carbon\Carbon;


$created_at = "2014-06-26 04:07:31";

$date = Carbon::parse($created_at);

echo $date->format("Y-m-d");

How to use border with Bootstrap

Depending what size you want your div to be, you could utilize Bootstrap's built-in component thumbnail class, along with (or without) the grid system to create borders around each of your div items.

These examples on Bootstrap's website demonstrates the ease-of-use and lack of need for any special additional CSS:

<div class="row">
    <div class="col-xs-6 col-md-3">
        <a href="#" class="thumbnail">
            <img src="..." alt="...">
        </a>
    </div>
    ...
</div>

which produces the following div grid items:

Simple grid objects

or add some additional content:

<div class="row">
  <div class="col-sm-6 col-md-4">
    <div class="thumbnail">
      <img src="..." alt="...">
      <div class="caption">
        <h3>Thumbnail label</h3>
        <p>...</p>
        <p>
            <a href="#" class="btn btn-primary" role="button">Button</a>
            <a href="#" class="btn btn-default" role="button">Button</a>
       </p>
      </div>
    </div>
  </div>
</div>

which produces the following div grid items:

Custom grid objects

Gradle failed to resolve library in Android Studio

Some time you may just need to add maven { url "https://jitpack.io" } in your allprojects block in project level build.gradle file.

Example:

allprojects {
    repositories {
        jcenter()
        maven { url "https://jitpack.io" }
    }
}

How to check if the request is an AJAX request with PHP

From PHP 7 with null coalescing operator it will be shorter:

$is_ajax = 'xmlhttprequest' == strtolower( $_SERVER['HTTP_X_REQUESTED_WITH'] ?? '' );

Export from pandas to_excel without row names (index)?

Example: index = False

import pandas as pd

writer = pd.ExcelWriter("dataframe.xlsx", engine='xlsxwriter')
dataframe.to_excel(writer,sheet_name = dataframe, index=False)
writer.save() 

Check if starting characters of a string are alphabetical in T-SQL

select * from my_table where my_field Like '[a-z][a-z]%'

Adding text to a cell in Excel using VBA

Range("$A$1").Value = "'01/01/13 00:00" will do it.

Note the single quote; this will defeat automatic conversion to a number type. But is that what you really want? An alternative would be to format the cell to take a date-time value. Then drop the single quote from the string.

When I run `npm install`, it returns with `ERR! code EINTEGRITY` (npm 5.3.0)

I had the same issue. I used yarn instead of npm to install the dependencies and it worked.

yarn add *****

How to use python numpy.savetxt to write strings and float number to an ASCII file?

The currently accepted answer does not actually address the question, which asks how to save lists that contain both strings and float numbers. For completeness I provide a fully working example, which is based, with some modifications, on the link given in @joris comment.

import numpy as np

names  = np.array(['NAME_1', 'NAME_2', 'NAME_3'])
floats = np.array([ 0.1234 ,  0.5678 ,  0.9123 ])

ab = np.zeros(names.size, dtype=[('var1', 'U6'), ('var2', float)])
ab['var1'] = names
ab['var2'] = floats

np.savetxt('test.txt', ab, fmt="%10s %10.3f")

Update: This example also works properly in Python 3 by using the 'U6' Unicode string dtype, when creating the ab structured array, instead of the 'S6' byte string. The latter dtype would work in Python 2.7, but would write strings like b'NAME_1' in Python 3.

pg_config executable not found

sudo yum install postgresql-devel (centos6X)

pip install psycopg2==2.5.2

IOException: read failed, socket might closed - Bluetooth on Android 4.3

Even i had the same problem ,finally understand my issue , i was trying to connect from (out of range) Bluetooth coverage range.

How to replace a string in an existing file in Perl?

None of the existing answers here has provided a complete example of how to do this from within a script (not a one-liner). Here is what I did:

rename($file, $file.'.bak');
open(IN, '<'.$file.'.bak') or die $!;
open(OUT, '>'.$file) or die $!;
while(<IN>)
{
    $_ =~ s/blue/red/g;
    print OUT $_;
}
close(IN);
close(OUT);

What is a handle in C++?

A handle is whatever you want it to be.

A handle can be a unsigned integer used in some lookup table.

A handle can be a pointer to, or into, a larger set of data.

It depends on how the code that uses the handle behaves. That determines the handle type.

The reason the term 'handle' is used is what is important. That indicates them as an identification or access type of object. Meaning, to the programmer, they represent a 'key' or access to something.

get next sequence value from database using hibernate

Here is the way I do it:

@Entity
public class ServerInstanceSeq
{
    @Id //mysql bigint(20)
    @SequenceGenerator(name="ServerInstanceIdSeqName", sequenceName="ServerInstanceIdSeq", allocationSize=20)
    @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="ServerInstanceIdSeqName")
    public Long id;

}

ServerInstanceSeq sis = new ServerInstanceSeq();
session.beginTransaction();
session.save(sis);
session.getTransaction().commit();
System.out.println("sis.id after save: "+sis.id);

Why XML-Serializable class need a parameterless constructor

First of all, this what is written in documentation. I think it is one of your class fields, not the main one - and how you want deserialiser to construct it back w/o parameterless construction ?

I think there is a workaround to make constructor private.

Read the package name of an Android APK

aapt dump badging <path-to-apk> | grep package:\ name

How can I set the opacity or transparency of a Panel in WinForms?

Yes, opacity can only work on top-level windows. It uses a hardware feature of the video adapter, that doesn't support child windows, like Panel. The only top-level Control derived class in Winforms is Form.

Several of the 'pure' Winform controls, the ones that do their own painting instead of letting a native Windows control do the job, do however support a transparent BackColor. Panel is one of them. It uses a trick, it asks the Parent to draw itself to produce the background pixels. One side-effect of this trick is that overlapping controls doesn't work, you only see the parent pixels, not the overlapped controls.

This sample form shows it at work:

public partial class Form1 : Form {
    public Form1() {
        InitializeComponent();
        this.BackColor = Color.White;
        panel1.BackColor = Color.FromArgb(25, Color.Black);
    }
    protected override void OnPaint(PaintEventArgs e) {
        e.Graphics.DrawLine(Pens.Yellow, 0, 0, 100, 100);
    }
}

If that's not good enough then you need to consider stacking forms on top of each other. Like this.

Notable perhaps is that this restriction is lifted in Windows 8. It no longer uses the video adapter overlay feature and DWM (aka Aero) cannot be turned off anymore. Which makes opacity/transparency on child windows easy to implement. Relying on this is of course future-music for a while to come. Windows 7 will be the next XP :)

Laravel, sync() - how to sync an array and also pass additional pivot fields?

Putting this here in case I forget it later and Google it again.

In my case I wanted the extra column to have the same data for each row

Where $syncData is an array of IDs:

$syncData = array_map(fn($locationSysid) => ['other_column' => 'foo'], array_flip($syncData));

or without arrow

$syncData = array_map(function($locationSysid) {
      return ['ENTITY' => 'dbo.Cli_Core'];
   }, array_flip($syncData));

(array_flip means we're using the IDs as the index for the array)

SQL Server - How to lock a table until a stored procedure finishes

Needed this answer myself and from the link provided by David Moye, decided on this and thought it might be of use to others with the same question:

CREATE PROCEDURE ...
AS
BEGIN
  BEGIN TRANSACTION

  -- lock table "a" till end of transaction
  SELECT ...
  FROM a
  WITH (TABLOCK, HOLDLOCK)
  WHERE ...

  -- do some other stuff (including inserting/updating table "a")



  -- release lock
  COMMIT TRANSACTION
END

How to list the files in current directory?

Had a quick snoop around for this one, but this looks like it should work. I haven't tested it yet though.

    File f = new File("."); // current directory

    File[] files = f.listFiles();
    for (File file : files) {
        if (file.isDirectory()) {
            System.out.print("directory:");
        } else {
            System.out.print("     file:");
        }
        System.out.println(file.getCanonicalPath());
    }

Using malloc for allocation of multi-dimensional arrays with different row lengths

I think a 2 step approach is best, because c 2-d arrays are just and array of arrays. The first step is to allocate a single array, then loop through it allocating arrays for each column as you go. This article gives good detail.

How to launch Safari and open URL from iOS app

Here one check is required that the url going to be open is able to open by device or simulator or not. Because some times (majority in simulator) i found it causes crashes.

Objective-C

NSURL *url = [NSURL URLWithString:@"some url"];
if ([[UIApplication sharedApplication] canOpenURL:url]) {
   [[UIApplication sharedApplication] openURL:url];
}

Swift 2.0

let url : NSURL = NSURL(string: "some url")!
if UIApplication.sharedApplication().canOpenURL(url) {
     UIApplication.sharedApplication().openURL(url)
}

Swift 4.2

guard let url = URL(string: "some url") else {
    return
}
if UIApplication.shared.canOpenURL(url) {
    UIApplication.shared.open(url, options: [:], completionHandler: nil)
}

Using Node.js require vs. ES6 import/export

The main advantages are syntactic:

  • More declarative/compact syntax
  • ES6 modules will basically make UMD (Universal Module Definition) obsolete - essentially removes the schism between CommonJS and AMD (server vs browser).

You are unlikely to see any performance benefits with ES6 modules. You will still need an extra library to bundle the modules, even when there is full support for ES6 features in the browser.

Why are C# 4 optional parameters defined on interface not enforced on implementing class?

Because default parameters are resolved at compile time, not runtime. So the default values does not belong to the object being called, but to the reference type that it is being called through.

How to create Select List for Country and States/province in MVC

So many ways to do this... for #NetCore use Lib..

    using System;
    using System.Collections.Generic;
    using System.Linq; // only required when .AsEnumerable() is used
    using System.ComponentModel.DataAnnotations;
    using Microsoft.AspNetCore.Mvc.Rendering;

Model...

namespace MyProject.Models
{
  public class MyModel
  {
    [Required]
    [Display(Name = "State")]
    public string StatePick { get; set; }
    public string state { get; set; }
    [StringLength(35, ErrorMessage = "State cannot be longer than 35 characters.")]
    public SelectList StateList { get; set; }
  }
}

Controller...

namespace MyProject.Controllers
{
    /// <summary>
    /// create SelectListItem from strings
    /// </summary>
    /// <param name="isValue">defaultValue is SelectListItem.Value is true, SelectListItem.Text if false</param>
    /// <returns></returns>
    private SelectListItem newItem(string value, string text, string defaultValue = "", bool isValue = false)
    {
        SelectListItem ss = new SelectListItem();
        ss.Text = text;
        ss.Value = value;

        // select default by Value or Text
        if (isValue && ss.Value == defaultValue || !isValue && ss.Text == defaultValue)
        {
            ss.Selected = true;
        }

        return ss;
    }

    /// <summary>
    /// this pulls the state name from _context and sets it as the default for the selectList
    /// </summary>
    /// <param name="myState">sets default value for list of states</param>
    /// <returns></returns>
    private SelectList getStateList(string myState = "")
    {
        List<SelectListItem> states = new List<SelectListItem>();
        SelectListItem chosen = new SelectListItem();

        // set default selected state to OHIO
        string defaultValue = "OH";
        if (!string.IsNullOrEmpty(myState))
        {
            defaultValue = myState;
        }

        try
        {
            states.Add(newItem("AL", "Alabama", defaultValue, true));
            states.Add(newItem("AK", "Alaska", defaultValue, true));
            states.Add(newItem("AZ", "Arizona", defaultValue, true));
            states.Add(newItem("AR", "Arkansas", defaultValue, true));
            states.Add(newItem("CA", "California", defaultValue, true));
            states.Add(newItem("CO", "Colorado", defaultValue, true));
            states.Add(newItem("CT", "Connecticut", defaultValue, true));
            states.Add(newItem("DE", "Delaware", defaultValue, true));
            states.Add(newItem("DC", "District of Columbia", defaultValue, true));
            states.Add(newItem("FL", "Florida", defaultValue, true));
            states.Add(newItem("GA", "Georgia", defaultValue, true));
            states.Add(newItem("HI", "Hawaii", defaultValue, true));
            states.Add(newItem("ID", "Idaho", defaultValue, true));
            states.Add(newItem("IL", "Illinois", defaultValue, true));
            states.Add(newItem("IN", "Indiana", defaultValue, true));
            states.Add(newItem("IA", "Iowa", defaultValue, true));
            states.Add(newItem("KS", "Kansas", defaultValue, true));
            states.Add(newItem("KY", "Kentucky", defaultValue, true));
            states.Add(newItem("LA", "Louisiana", defaultValue, true));
            states.Add(newItem("ME", "Maine", defaultValue, true));
            states.Add(newItem("MD", "Maryland", defaultValue, true));
            states.Add(newItem("MA", "Massachusetts", defaultValue, true));
            states.Add(newItem("MI", "Michigan", defaultValue, true));
            states.Add(newItem("MN", "Minnesota", defaultValue, true));
            states.Add(newItem("MS", "Mississippi", defaultValue, true));
            states.Add(newItem("MO", "Missouri", defaultValue, true));
            states.Add(newItem("MT", "Montana", defaultValue, true));
            states.Add(newItem("NE", "Nebraska", defaultValue, true));
            states.Add(newItem("NV", "Nevada", defaultValue, true));
            states.Add(newItem("NH", "New Hampshire", defaultValue, true));
            states.Add(newItem("NJ", "New Jersey", defaultValue, true));
            states.Add(newItem("NM", "New Mexico", defaultValue, true));
            states.Add(newItem("NY", "New York", defaultValue, true));
            states.Add(newItem("NC", "North Carolina", defaultValue, true));
            states.Add(newItem("ND", "North Dakota", defaultValue, true));
            states.Add(newItem("OH", "Ohio", defaultValue, true));
            states.Add(newItem("OK", "Oklahoma", defaultValue, true));
            states.Add(newItem("OR", "Oregon", defaultValue, true));
            states.Add(newItem("PA", "Pennsylvania", defaultValue, true));
            states.Add(newItem("RI", "Rhode Island", defaultValue, true));
            states.Add(newItem("SC", "South Carolina", defaultValue, true));
            states.Add(newItem("SD", "South Dakota", defaultValue, true));
            states.Add(newItem("TN", "Tennessee", defaultValue, true));
            states.Add(newItem("TX", "Texas", defaultValue, true));
            states.Add(newItem("UT", "Utah", defaultValue, true));
            states.Add(newItem("VT", "Vermont", defaultValue, true));
            states.Add(newItem("VA", "Virginia", defaultValue, true));
            states.Add(newItem("WA", "Washington", defaultValue, true));
            states.Add(newItem("WV", "West Virginia", defaultValue, true));
            states.Add(newItem("WI", "Wisconsin", defaultValue, true));
            states.Add(newItem("WY", "Wyoming", defaultValue, true));

            foreach (SelectListItem state in states)
            {
                if (state.Selected)
                {
                    chosen = state;
                    break;
                }
            }
        }
        catch (Exception err)
        {
            string ss = "ERR!   " + err.Source + "   " + err.GetType().ToString() + "\r\n" + err.Message.Replace("\r\n", "   ");
            ss = this.sendError("Online getStateList Request", ss, _errPassword);
            // return error
        }

        // .AsEnumerable() is not required in the pass.. it is an extension of Linq
        SelectList myList = new SelectList(states.AsEnumerable(), "Value", "Text", chosen);

        object val = myList.SelectedValue;

        return myList;
    }

    public ActionResult pickState(MyModel pData)
    {
        if (pData.StateList == null)
        {
            if (String.IsNullOrEmpty(pData.StatePick)) // state abbrev, value collected onchange
            {
                pData.StateList = getStateList();
            }
            else
            {
                pData.StateList = getStateList(pData.StatePick);
            }

            // assign values to state list items
            try
            {
                SelectListItem si = (SelectListItem)pData.StateList.SelectedValue;
                pData.state = si.Value;
                pData.StatePick = si.Value;
            }
            catch { }
        } 
    return View(pData);
    }
}

pickState.cshtml...

@model MyProject.Models.MyModel

@{
ViewBag.Title = "United States of America";
Layout = "~/Views/Shared/_Layout.cshtml";
}
<h2>@ViewBag.Title - Where are you...</h2>

@using (Html.BeginForm()) {
@Html.AntiForgeryToken()
@Html.ValidationSummary(true)

<fieldset>

    <div class="editor-label">
        @Html.DisplayNameFor(model => model.state)
    </div>
    <div class="display-field">            
        @Html.DropDownListFor(m => m.StatePick, Model.StateList, new { OnChange = "state.value = this.value;" })
        @Html.EditorFor(model => model.state)
        @Html.ValidationMessageFor(model => model.StateList)
    </div>         
</fieldset>
}

<div>
@Html.ActionLink("Back to List", "Index")
</div>

What is the difference between typeof and instanceof and when should one be used vs. the other?

One more case is that You only can collate with instanceof - it returns true or false. With typeof you can get type of provided something

Return back to MainActivity from another activity

I highly recommend reading the docs on the Intent.FLAG_ACTIVITY_CLEAR_TOP flag. Using it will not necessarily go back all the way to the first (main) activity. The flag will only remove all existing activities up to the activity class given in the Intent. This is explained well in the docs:

For example, consider a task consisting of the activities: A, B, C, D.
If D calls startActivity() with an Intent that resolves to the component of
activity B, then C and D will be finished and B receive the given Intent, 
resulting in the stack now being: A, B.

Note that the activity can set to be moved to the foreground (i.e., clearing all other activities on top of it), and then also being relaunched, or only get onNewIntent() method called.

Source

What does the ??!??! operator do in C?

??! is a trigraph that translates to |. So it says:

!ErrorHasOccured() || HandleError();

which, due to short circuiting, is equivalent to:

if (ErrorHasOccured())
    HandleError();

Guru of the Week (deals with C++ but relevant here), where I picked this up.

Possible origin of trigraphs or as @DwB points out in the comments it's more likely due to EBCDIC being difficult (again). This discussion on the IBM developerworks board seems to support that theory.

From ISO/IEC 9899:1999 §5.2.1.1, footnote 12 (h/t @Random832):

The trigraph sequences enable the input of characters that are not defined in the Invariant Code Set as described in ISO/IEC 646, which is a subset of the seven-bit US ASCII code set.

How to run 'sudo' command in windows

The following vbs script allows to launch a given command with arguments with elevation and mimics the behavior of the original unix sudo command for a limited set of used cases (it will not cache credentials nor it allows to truly execute commands with different credentials). I put it on C:\Windows\System32.

Set objArgs = WScript.Arguments
exe = objArgs(0)
args = ""
IF objArgs.Count >= 2 Then
   args = args & objArgs(1)
End If
For it = 2 to objArgs.Count - 1
   args = args & " " & objArgs(it)
Next
Set objShell = CreateObject( "WScript.Shell")
windir=objShell.ExpandEnvironmentStrings("%WINDIR%")
Set objShellApp = CreateObject("Shell.Application")
objShellApp.ShellExecute exe, args, "", "runas", 1
set objShellApp = nothing

Example use on a command prompt sudo net start service

How should I read a file line-by-line in Python?

if you're turned off by the extra line, you can use a wrapper function like so:

def with_iter(iterable):
    with iterable as iter:
        for item in iter:
            yield item

for line in with_iter(open('...')):
    ...

in Python 3.3, the yield from statement would make this even shorter:

def with_iter(iterable):
    with iterable as iter:
        yield from iter

Bootstrap number validation

you can use PATTERN:

<input class="form-control" minlength="1" pattern="[0-9]*" [(ngModel)]="value" #name="ngModel">

<div *ngIf="name.invalid && (name.dirty || name.touched)" class="text-danger">
  <div *ngIf="name.errors?.pattern">Is not a number</div>
</div>

Show Hide div if, if statement is true

Use show/hide method as below

$("div").show();//To Show

$("div").hide();//To Hide

Maximum number of threads per process in Linux?

In practical terms, the limit is usually determined by stack space. If each thread gets a 1MB stack (I can't remember if that is the default on Linux), then you a 32-bit system will run out of address space after 3000 threads (assuming that the last gb is reserved to the kernel).

However, you'll most likely experience terrible performance if you use more than a few dozen threads. Sooner or later, you get too much context-switching overhead, too much overhead in the scheduler, and so on. (Creating a large number of threads does little more than eat a lot of memory. But a lot of threads with actual work to do is going to slow you down as they're fighting for the available CPU time)

What are you doing where this limit is even relevant?

jQuery changing font family and font size

In some browsers, fonts are set explicit for textareas and inputs, so they don’t inherit the fonts from higher elements. So, I think you need to apply the font styles for each textarea and input in the document as well (not just the body).

One idea might be to add clases to the body, then use CSS to style the document accordingly.

Using an integer as a key in an associative array in JavaScript

Use an object, as people are saying. However, note that you can not have integer keys. JavaScript will convert the integer to a string. The following outputs 20, not undefined:

var test = {}
test[2300] = 20;
console.log(test["2300"]);

SQL Query - SUM(CASE WHEN x THEN 1 ELSE 0) for multiple columns

I would change the query in the following ways:

  1. Do the aggregation in subqueries. This can take advantage of more information about the table for optimizing the group by.
  2. Combine the second and third subqueries. They are aggregating on the same column. This requires using a left outer join to ensure that all data is available.
  3. By using count(<fieldname>) you can eliminate the comparisons to is null. This is important for the second and third calculated values.
  4. To combine the second and third queries, it needs to count an id from the mde table. These use mde.mdeid.

The following version follows your example by using union all:

SELECT CAST(Detail.ReceiptDate AS DATE) AS "Date",
       SUM(TOTALMAILED) as TotalMailed,
       SUM(TOTALUNDELINOTICESRECEIVED) as TOTALUNDELINOTICESRECEIVED,
       SUM(TRACEUNDELNOTICESRECEIVED) as TRACEUNDELNOTICESRECEIVED
FROM ((select SentDate AS "ReceiptDate", COUNT(*) as TotalMailed,
              NULL as TOTALUNDELINOTICESRECEIVED, NULL as TRACEUNDELNOTICESRECEIVED
       from MailDataExtract
       where SentDate is not null
       group by SentDate
      ) union all
      (select MDE.ReturnMailDate AS ReceiptDate, 0,
              COUNT(distinct mde.mdeid) as TOTALUNDELINOTICESRECEIVED,
              SUM(case when sd.ReturnMailTypeId = 1 then 1 else 0 end) as TRACEUNDELNOTICESRECEIVED
       from MailDataExtract MDE left outer join
            DTSharedData.dbo.ScanData SD
            ON SD.ScanDataID = MDE.ReturnScanDataID
       group by MDE.ReturnMailDate;
      )
     ) detail
GROUP BY CAST(Detail.ReceiptDate AS DATE)
ORDER BY 1;

The following does something similar using full outer join:

SELECT coalesce(sd.ReceiptDate, mde.ReceiptDate) AS "Date",
       sd.TotalMailed, mde.TOTALUNDELINOTICESRECEIVED,
       mde.TRACEUNDELNOTICESRECEIVED
FROM (select cast(SentDate as date) AS "ReceiptDate", COUNT(*) as TotalMailed
      from MailDataExtract
      where SentDate is not null
      group by cast(SentDate as date)
     ) sd full outer join
    (select cast(MDE.ReturnMailDate as date) AS ReceiptDate,
            COUNT(distinct mde.mdeID) as TOTALUNDELINOTICESRECEIVED,
            SUM(case when sd.ReturnMailTypeId = 1 then 1 else 0 end) as TRACEUNDELNOTICESRECEIVED
     from MailDataExtract MDE left outer join
          DTSharedData.dbo.ScanData SD
          ON SD.ScanDataID = MDE.ReturnScanDataID
     group by cast(MDE.ReturnMailDate as date)
    ) mde
    on sd.ReceiptDate = mde.ReceiptDate
ORDER BY 1;

Adding elements to object

cart.push({"element":{ id: id, quantity: quantity }});

jQuery won't parse my JSON from AJAX query

If you are echoing out the json response and your headers don't match */json then you can use the built in jQuery.parseJSON api to parse the response.

response = '{"name":"John"}';
var obj = jQuery.parseJSON(response);
alert( obj.name === "John" );

Python script to copy text to clipboard

GTK3:

#!/usr/bin/python3

from gi.repository import Gtk, Gdk


class Hello(Gtk.Window):

    def __init__(self):
        super(Hello, self).__init__()
        clipboard = Gtk.Clipboard.get(Gdk.SELECTION_CLIPBOARD)
        clipboard.set_text("hello world", -1)
        Gtk.main_quit()


def main():
    Hello()
    Gtk.main()

if __name__ == "__main__":
    main()

How to call python script on excel vba?

There are a couple of ways to solve this problem

Pyinx - a pretty lightweight tool that allows you to call Python from withing the excel process space http://code.google.com/p/pyinex/

I've used this one a few years ago (back when it was being actively developed) and it worked quite well

If you don't mind paying, this looks pretty good

https://datanitro.com/product.html

I've never used it though


Though if you are already writting in Python, maybe you could drop excel entirely and do everything in pure python? It's a lot easier to maintain one code base (python) rather than 2 (python + whatever excel overlay you have).

If you really have to output your data into excel there are even some pretty good tools for that in Python. If that may work better let me know and I'll get the links.

How to return a html page from a restful controller in spring boot?

You get only the name because you return only the name return "login";. It's @RestController and this controller returns data rather than a view; because of this, you get only content that you return from method.

If you want to show view with this name you need to use Spring MVC, see this example.

how to modify an existing check constraint?

NO, you can't do it other way than so.

How to check date of last change in stored procedure or function in SQL server

In latest version(2012 or more) we can get modified stored procedure detail by using this query

SELECT create_date, modify_date, name FROM sys.procedures 
ORDER BY modify_date DESC

How to programmatically open the Permission Screen for a specific app on Android Marshmallow?

Instead, you can open particular app's general settings with one line

 startActivity(new Intent(android.provider.Settings.ACTION_APPLICATION_DETAILS_SETTINGS, Uri.parse("package:" + BuildConfig.APPLICATION_ID)));

ValueError : I/O operation on closed file

Indent correctly; your for statement should be inside the with block:

import csv    

with open('v.csv', 'w') as csvfile:
    cwriter = csv.writer(csvfile, delimiter=' ', quotechar='|', quoting=csv.QUOTE_MINIMAL)

    for w, c in p.items():
        cwriter.writerow(w + c)

Outside the with block, the file is closed.

>>> with open('/tmp/1', 'w') as f:
...     print(f.closed)
... 
False
>>> print(f.closed)
True

Convert an integer to a byte array

Sorry, this might be a bit late. But I think I found a better implementation on the go docs.

buf := new(bytes.Buffer)
var num uint16 = 1234
err := binary.Write(buf, binary.LittleEndian, num)
if err != nil {
    fmt.Println("binary.Write failed:", err)
}
fmt.Printf("% x", buf.Bytes())

How do I execute a program using Maven?

With the global configuration that you have defined for the exec-maven-plugin:

<plugin>
  <groupId>org.codehaus.mojo</groupId>
  <artifactId>exec-maven-plugin</artifactId>
  <version>1.4.0</version>
  <configuration>
    <mainClass>org.dhappy.test.NeoTraverse</mainClass>
  </configuration>
</plugin>

invoking mvn exec:java on the command line will invoke the plugin which is configured to execute the class org.dhappy.test.NeoTraverse.

So, to trigger the plugin from the command line, just run:

mvn exec:java

Now, if you want to execute the exec:java goal as part of your standard build, you'll need to bind the goal to a particular phase of the default lifecycle. To do this, declare the phase to which you want to bind the goal in the execution element:

<plugin>
  <groupId>org.codehaus.mojo</groupId>
  <artifactId>exec-maven-plugin</artifactId>
  <version>1.4</version>
  <executions>
    <execution>
      <id>my-execution</id>
      <phase>package</phase>
      <goals>
        <goal>java</goal>
      </goals>
    </execution>
  </executions>
  <configuration>
    <mainClass>org.dhappy.test.NeoTraverse</mainClass>
  </configuration>
</plugin>

With this example, your class would be executed during the package phase. This is just an example, adapt it to suit your needs. Works also with plugin version 1.1.

Visual Studio Code includePath

This answer maybe late but I just happened to fix the issue. Here is my c_cpp_properties.json file:

{
"configurations": [
    {
        "name": "Linux",
        "includePath": [
            "${workspaceFolder}/**",                
            "/usr/include/c++/5.4.0/",
            "usr/local/include/",
            "usr/include/"
        ],
        "defines": [],
        "compilerPath": "/usr/bin/gcc",
        "cStandard": "c11",
        "cppStandard": "c++14",
        "intelliSenseMode": "clang-x64"
    }
],
"version": 4

}

Import CSV into SQL Server (including automatic table creation)

SQL Server Management Studio provides an Import/Export wizard tool which have an option to automatically create tables.

You can access it by right clicking on the Database in Object Explorer and selecting Tasks->Import Data...

From there wizard should be self-explanatory and easy to navigate. You choose your CSV as source, desired destination, configure columns and run the package.

If you need detailed guidance, there are plenty of guides online, here is a nice one: http://www.mssqltips.com/sqlservertutorial/203/simple-way-to-import-data-into-sql-server/

When is it appropriate to use UDP instead of TCP?

Only use UDP if you really know what you are doing. UDP is in extremely rare cases today, but the number of (even very experienced) experts who would try to stick it everywhere seems to be out of proportion. Perhaps they enjoy implementing error-handling and connection maintenance code themselves.

TCP should be expected to be much faster with modern network interface cards due to what's known as checksum imprint. Surprisingly, at fast connection speeds (such as 1Gbps) computing a checksum would be a big load for a CPU so it is offloaded to NIC hardware that recognizes TCP packets for imprint, and it won't offer you the same service.

Set form backcolor to custom color

If you want to set the form's back color to some arbitrary RGB value, you can do this:

this.BackColor = Color.FromArgb(255, 232, 232); // this should be pink-ish

How to select all the columns of a table except one column?

Create a view. Yes, in the view creation statement, you will have to list each...and...every...field...by...name.

Once.

Then just select * from viewname after that.

Speed up rsync with Simultaneous/Concurrent File Transfers?

Have you tried using rclone.org?

With rclone you could do something like

rclone copy "${source}/${subfolder}/" "${target}/${subfolder}/" --progress --multi-thread-streams=N

where --multi-thread-streams=N represents the number of threads you wish to spawn.

Selecting only first-level elements in jquery

1

 $("ul.rootlist > target-element")
2   $("ul.rootlist").find(target-element).eq(0) (only one instance)
3   $("ul.rootlist").children(target-element)

there are probably many other ways

PHP remove special character from string

preg_replace('/[^a-zA-Z0-9_ \-()\/%-&]/s', '', $String);

What is Python buffer type for?

I think buffers are e.g. useful when interfacing python to native libraries. (Guido van Rossum explains buffer in this mailinglist post).

For example, numpy seems to use buffer for efficient data storage:

import numpy
a = numpy.ndarray(1000000)

the a.data is a:

<read-write buffer for 0x1d7b410, size 8000000, offset 0 at 0x1e353b0>

How do I go about adding an image into a java project with eclipse?

If you are doing it in eclipse, there are a few quick notes that if you are hovering your mouse over a class in your script, it will show a focus dialogue that says hit f2 for focus.

for computer apps, use ImageIcon. and for the path say,

ImageIcon thisImage = new ImageIcon("images/youpic.png");

specify the folder( images) then seperate with / and add the name of the pic file.

I hope this is helpful. If someone else posted it, I didn't read through. So...yea.. thought reinforcement.

Error while retrieving information from the server RPC:s-7:AEC-0 in Google play?

on the BlueStacks emulator worked for me the following solution

Go to ”Settings” -> “Applications” -> “Manage Applications” and select “All

Go to “Google Play Services Framework” and select “Clear Data” & “Clear Cache” to remove all the data.

Go to “Google Play Store” and Select “Clear Data” & “Clear Cache” to remove all the data regarding Google Play Store.

Go to “Settings” -> “Accounts” -> “Google” -> Select “Your Account

Go to “Menu” and Select “Remove Account”.

Now “Restart” your mobile device.

Go to “Menu” and “Add Your Account”.

and try to perform update or download.

How do I trim whitespace?

No one has posted these regex solutions yet.

Matching:

>>> import re
>>> p=re.compile('\\s*(.*\\S)?\\s*')

>>> m=p.match('  \t blah ')
>>> m.group(1)
'blah'

>>> m=p.match('  \tbl ah  \t ')
>>> m.group(1)
'bl ah'

>>> m=p.match('  \t  ')
>>> print m.group(1)
None

Searching (you have to handle the "only spaces" input case differently):

>>> p1=re.compile('\\S.*\\S')

>>> m=p1.search('  \tblah  \t ')
>>> m.group()
'blah'

>>> m=p1.search('  \tbl ah  \t ')
>>> m.group()
'bl ah'

>>> m=p1.search('  \t  ')
>>> m.group()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'NoneType' object has no attribute 'group'

If you use re.sub, you may remove inner whitespace, which could be undesirable.

Yarn install command error No such file or directory: 'install'

I had the same issue on Ubuntu 17.04.

This solution worked for me:

sudo apt remove cmdtest
sudo apt remove yarn
curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
sudo apt-get update
sudo apt-get install yarn -y

then

yarn install

result:

yarn install v1.3.2
warning You are using Node "6.0.0" which is not supported and may encounter bugs or unexpected behaviour. Yarn supports the following server range: "^4.8.0 || ^5.7.0 || ^6.2.2 || >=8.0.0"
info No lockfile found.
[1/4] Resolving packages...
[2/4] Fetching packages...
[3/4] Linking dependencies...
[4/4] Building fresh packages...

info Lockfile not saved, no dependencies.
Done in 0.20s.

Hope that it will help you.

How to get started with Windows 7 gadgets

Here's an MSDN article on Vista Gadgets. Some preliminary documentation on 7 gadgets, and changes. I think the only major changes are that Gadgets don't reside in the Sidebar anymore, and as such "dock/undock events" are now backwards-compatibility cludges that really shouldn't be used.

Best way to get started is probably to just tweak an existing gadget. There's an example gadget in the above link, or you could pick a different one out on your own.

Gadgets are written in HTML, CSS, and some IE scripting language (generally Javascript, but I believe VBScript also works). For really fancy things you might need to create an ActiveX object, so C#/C++ for COM could be useful to know.

Gadgets are packaged as ".gadget" files, which are just renamed Zip archives that contain a gadget manifest (gadget.xml) in their top level.