Programs & Examples On #Optgroup

The OPTGROUP element defines a group of choices within a SELECT menu.

Nesting optgroups in a dropdownlist/select

The HTML spec here is really broken. It should allow nested optgroups and recommend user agents render them as nested menus. Instead, only one optgroup level is allowed. However, they do have to say the following on the subject:

Note. Implementors are advised that future versions of HTML may extend the grouping mechanism to allow for nested groups (i.e., OPTGROUP elements may nest). This will allow authors to represent a richer hierarchy of choices.

And user agents could start using submenus to render optgoups instead of displaying titles before the first option element in an optgroup as they do now.

How to extract week number in sql

Select last_name, round (sysdate-hire_date)/7,0) as tuner 
  from employees
  Where department_id = 90 
  order by last_name;

Check if element is visible in DOM

So what I found is the most feasible method:

function visible(elm) {
  if(!elm.offsetHeight && !elm.offsetWidth) { return false; }
  if(getComputedStyle(elm).visibility === 'hidden') { return false; }
  return true;
}

This is build on these facts:

  • A display: none element (even a nested one) doesn't have a width nor height.
  • visiblity is hidden even for nested elements.

So no need for testing offsetParent or looping up in the DOM tree to test which parent has visibility: hidden. This should work even in IE 9.

You could argue if opacity: 0 and collapsed elements (has a width but no height - or visa versa) is not really visible either. But then again they are not per say hidden.

JSON to PHP Array using file_get_contents

The JSON sample you provided is not valid. Check it online with this JSON Validator http://jsonlint.com/. You need to remove the extra comma on line 59.

One you have valid json you can use this code to convert it to an array.

json_decode($json, true);

Array
(
    [bpath] => http://www.sampledomain.com/
    [clist] => Array
        (
            [0] => Array
                (
                    [cid] => 11
                    [display_type] => grid
                    [ctitle] => abc
                    [acount] => 71
                    [alist] => Array
                        (
                            [0] => Array
                                (
                                    [aid] => 6865
                                    [adate] => 2 Hours ago
                                    [atitle] => test
                                    [adesc] => test desc
                                    [aimg] => 
                                    [aurl] => ?nid=6865
                                    [weburl] => news.php?nid=6865
                                    [cmtcount] => 0
                                )

                            [1] => Array
                                (
                                    [aid] => 6857
                                    [adate] => 20 Hours ago
                                    [atitle] => test1
                                    [adesc] => test desc1
                                    [aimg] => 
                                    [aurl] => ?nid=6857
                                    [weburl] => news.php?nid=6857
                                    [cmtcount] => 0
                                )

                        )

                )

            [1] => Array
                (
                    [cid] => 1
                    [display_type] => grid
                    [ctitle] => test1
                    [acount] => 2354
                    [alist] => Array
                        (
                            [0] => Array
                                (
                                    [aid] => 6851
                                    [adate] => 1 Days ago
                                    [atitle] => test123
                                    [adesc] => test123 desc
                                    [aimg] => 
                                    [aurl] => ?nid=6851
                                    [weburl] => news.php?nid=6851
                                    [cmtcount] => 7
                                )

                            [1] => Array
                                (
                                    [aid] => 6847
                                    [adate] => 2 Days ago
                                    [atitle] => test12345
                                    [adesc] => test12345 desc
                                    [aimg] => 
                                    [aurl] => ?nid=6847
                                    [weburl] => news.php?nid=6847
                                    [cmtcount] => 7
                                )

                        )

                )

        )

)

android - listview get item view by position

workignHoursListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
    @Override
    public void onItemClick(AdapterView<?> parent,View view, int position, long id) {
        viewtype yourview=yourListViewId.getChildAt(position).findViewById(R.id.viewid);
    }
});

List files ONLY in the current directory

You can use the pathlib module.

from pathlib import Path
x = Path('./')
print(list(filter(lambda y:y.is_file(), x.iterdir())))

How to create a HTML Cancel button that redirects to a URL

Thats what i am using try it.

<a href="index.php"><button style ="position:absolute;top:450px;left:1100px;height:30px;width:200px;"> Cancel </button></a>

Copying formula to the next row when inserting a new row

One other key thing that I found regarding copying rows within a table, is that the worksheet you are working on needs to be activated. If you have a workbook with multiple sheets, you need to save the sheet you called the macro from, and then activate the sheet with the table. Once you are done, you can re-activate the original sheet.

You can use Application.ScreenUpdating = False to make sure the user doesn't see that you are switching worksheets within your macro.

If you don't have the worksheet activated, the copy doesn't seem to work properly, i.e. some stuff seem to work, and other stuff doesn't ??

Why did I get the compile error "Use of unassigned local variable"?

The default value table only applies to initializing a variable.

Per the linked page, the following two methods of initialization are equivalent...

int x = 0;
int x = new int();

In your code, you merely defined the variable, but never initialized the object.

How do function pointers in C work?

One of my favorite uses for function pointers is as cheap and easy iterators -

#include <stdio.h>
#define MAX_COLORS  256

typedef struct {
    char* name;
    int red;
    int green;
    int blue;
} Color;

Color Colors[MAX_COLORS];


void eachColor (void (*fp)(Color *c)) {
    int i;
    for (i=0; i<MAX_COLORS; i++)
        (*fp)(&Colors[i]);
}

void printColor(Color* c) {
    if (c->name)
        printf("%s = %i,%i,%i\n", c->name, c->red, c->green, c->blue);
}

int main() {
    Colors[0].name="red";
    Colors[0].red=255;
    Colors[1].name="blue";
    Colors[1].blue=255;
    Colors[2].name="black";

    eachColor(printColor);
}

What is a Memory Heap?

A memory heap is a common structure for holding dynamically allocated memory. See Dynamic_memory_allocation on wikipedia.

There are other structures, like pools, stacks and piles.

How should I escape strings in JSON?

If you need to escape JSON inside JSON string, use org.json.JSONObject.quote("your json string that needs to be escaped") seem to work well

Object cannot be cast from DBNull to other types

I suspect that the line

DataTO.Id = Convert.ToInt64(dataAccCom.GetParameterValue(IDbCmd, "op_Id"));

is causing the problem. Is it possible that the op_Id value is being set to null by the stored procedure?

To Guard against it use the Convert.IsDBNull method. For example:

if (!Convert.IsDBNull(dataAccCom.GetParameterValue(IDbCmd, "op_Id"))
{
 DataTO.Id = Convert.ToInt64(dataAccCom.GetParameterValue(IDbCmd, "op_Id"));
}
else 
{
 DataTO.Id = ...some default value or perform some error case management
}

Android webview slow

I was having this same issue and I had to work it out. I tried these solutions, but at the end the performance, at least for the scrolling didn't improve at all. So here the workaroud that I did perform and the explanation of why it did work for me.

If you had the chance to explore the drag events, just a little, by creating a "MiWebView" Class, overwriting the "onTouchEvent" method and at least printed the time in which every drag event occurs, you'll see that they are separated in time for (down to) 9ms away. That is a very short time in between events.

Take a look at the WebView Source Code, and just see the onTouchEvent function. It is just impossible for it to be handled by the processor in less than 9ms (Keep on dreaming!!!). That's why you constantly see the "Miss a drag as we are waiting for WebCore's response for touch down." message. The code just can't be handled on time.

How to fix it? First, you can not re-write the onTouchEvent code to improve it, it is just too much. But, you can "mock it" in order to limit the event rate for dragging movements let's say to 40ms or 50ms. (this depends on the processor).

All touch events go like this: ACTION_DOWN -> ACTION_MOVE......ACTION_MOVE -> ACTION_UP. So we need to keep the DOWN and UP movements and filter the MOVE rate (these are the bad guys).

And here is a way to do it (you can add more event types like 2 fingers touch, all I'm interested here is the single finger scrolling).

import android.content.Context;
import android.view.MotionEvent;
import android.webkit.WebView;


public class MyWebView extends WebView{

    public MyWebView(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }

    private long lastMoveEventTime = -1;
    private int eventTimeInterval = 40;

    @Override
    public boolean onTouchEvent(MotionEvent ev) {

        long eventTime = ev.getEventTime();
        int action = ev.getAction();

        switch (action){
            case MotionEvent.ACTION_MOVE: {
                if ((eventTime - lastMoveEventTime) > eventTimeInterval){
                    lastMoveEventTime = eventTime;
                    return super.onTouchEvent(ev);
                }
                break;
            }
            case MotionEvent.ACTION_DOWN:
            case MotionEvent.ACTION_UP: {
                return super.onTouchEvent(ev);
            }
        }
        return true;
    }
}

Of course Use this class instead of WebView and you'll see the difference when scrolling.

This is just an approach to a solution, yet still not fully implemented for all lag cases due to screen touching when using WebView. However it is the best solution I found, at least for my specific needs.

how do I print an unsigned char as hex in c++ using ostream?

Use:

cout << "a is " << hex << (int) a <<"; b is " << hex << (int) b << endl;

And if you want padding with leading zeros then:

#include <iomanip>
...
cout << "a is " << setw(2) << setfill('0') << hex << (int) a ; 

As we are using C-style casts, why not go the whole hog with terminal C++ badness and use a macro!

#define HEX( x )
   setw(2) << setfill('0') << hex << (int)( x )

you can then say

cout << "a is " << HEX( a );

Edit: Having said that, MartinStettner's solution is much nicer!

Safely remove migration In Laravel

I accidentally created a migration with a bad name (command: php artisan migrate:make). I did not run (php artisan migrate) the migration, so I decided to remove it. My steps:

  1. Manually delete the migration file under app/database/migrations/my_migration_file_name.php
  2. Reset the composer autoload files: composer dump-autoload
  3. Relax

If you did run the migration (php artisan migrate), you may do this:

a) Run migrate:rollback - it is the right way to undo the last migration (Thnx @Jakobud)

b) If migrate:rollback does not work, do it manually (I remember bugs with migrate:rollback in previous versions):

  1. Manually delete the migration file under app/database/migrations/my_migration_file_name.php
  2. Reset the composer autoload files: composer dump-autoload
  3. Modify your database: Remove the last entry from the migrations table

sqlite3.ProgrammingError: Incorrect number of bindings supplied. The current statement uses 1, and there are 74 supplied

You need to pass in a sequence, but you forgot the comma to make your parameters a tuple:

cursor.execute('INSERT INTO images VALUES(?)', (img,))

Without the comma, (img) is just a grouped expression, not a tuple, and thus the img string is treated as the input sequence. If that string is 74 characters long, then Python sees that as 74 separate bind values, each one character long.

>>> len(img)
74
>>> len((img,))
1

If you find it easier to read, you can also use a list literal:

cursor.execute('INSERT INTO images VALUES(?)', [img])

Binding an enum to a WinForms combo box, and then setting it

Generic method for setting a enum as datasource for drop downs

Display would be name. Selected value would be Enum itself

public IList<KeyValuePair<string, T>> GetDataSourceFromEnum<T>() where T : struct,IConvertible
    {
        IList<KeyValuePair<string, T>> list = new BindingList<KeyValuePair<string, T>>();
        foreach (string value in Enum.GetNames(typeof(T)))
        {
            list.Add(new KeyValuePair<string, T>(value, (T)Enum.Parse(typeof(T), value)));
        }
        return list;
    }

Logical operator in a handlebars.js {{#if}} conditional

Install Ember Truth Helpers addon by running the below command

ember install ember-truth-helpers

you can start use most of the logical operators(eq,not-eq,not,and,or,gt,gte,lt,lte,xor).

{{#if (or section1 section2)}}  
...content  
{{/if}}

You can even include subexpression to go further,

{{#if (or (eq section1 "section1") (eq section2 "section2") ) }}  
...content  
{{/if}}

SQL Server query - Selecting COUNT(*) with DISTINCT

I needed to get the number of occurrences of each distinct value. The column contained Region info. The simple SQL query I ended up with was:

SELECT Region, count(*)
FROM item
WHERE Region is not null
GROUP BY Region

Which would give me a list like, say:

Region, count
Denmark, 4
Sweden, 1
USA, 10

Attaching a Sass/SCSS to HTML docs

You can not "attach" a SASS/SCSS file to an HTML document.

SASS/SCSS is a CSS preprocessor that runs on the server and compiles to CSS code that your browser understands.

There are client-side alternatives to SASS that can be compiled in the browser using javascript such as LESS CSS, though I advise you compile to CSS for production use.

It's as simple as adding 2 lines of code to your HTML file.

<link rel="stylesheet/less" type="text/css" href="styles.less" />
<script src="less.js" type="text/javascript"></script>

SQL Server dynamic PIVOT query?

The below code provides the results which replaces NULL to zero in the output.

Table creation and data insertion:

create table test_table
 (
 date nvarchar(10),
 category char(3),
 amount money
 )

 insert into test_table values ('1/1/2012','ABC',1000.00)
 insert into test_table values ('2/1/2012','DEF',500.00)
 insert into test_table values ('2/1/2012','GHI',800.00)
 insert into test_table values ('2/10/2012','DEF',700.00)
 insert into test_table values ('3/1/2012','ABC',1100.00)

Query to generate the exact results which also replaces NULL with zeros:

DECLARE @DynamicPivotQuery AS NVARCHAR(MAX),
@PivotColumnNames AS NVARCHAR(MAX),
@PivotSelectColumnNames AS NVARCHAR(MAX)

--Get distinct values of the PIVOT Column
SELECT @PivotColumnNames= ISNULL(@PivotColumnNames + ',','')
+ QUOTENAME(category)
FROM (SELECT DISTINCT category FROM test_table) AS cat

--Get distinct values of the PIVOT Column with isnull
SELECT @PivotSelectColumnNames 
= ISNULL(@PivotSelectColumnNames + ',','')
+ 'ISNULL(' + QUOTENAME(category) + ', 0) AS '
+ QUOTENAME(category)
FROM (SELECT DISTINCT category FROM test_table) AS cat

--Prepare the PIVOT query using the dynamic 
SET @DynamicPivotQuery = 
N'SELECT date, ' + @PivotSelectColumnNames + '
FROM test_table
pivot(sum(amount) for category in (' + @PivotColumnNames + ')) as pvt';

--Execute the Dynamic Pivot Query
EXEC sp_executesql @DynamicPivotQuery

OUTPUT :

enter image description here

Owl Carousel Won't Autoplay

Owl Carousel version matters a lot, as of now (2nd Aug 2020) the version is 2.3.4 and the right options for autoplay are:

$(".owl-carousel").owlCarousel({
    autoplay : true,
    autoplayTimeout: 3000,//Autoplay interval timeout.
    loop:true,//Infinity loop. Duplicate last and first items to get loop illusion.
    items:1 //The number of items you want to see on the screen.
});

Read more Owl configurations

React Router Pass Param to Component

if you are using class component, you are most likely to use GSerjo suggestion. Pass in the params via <Route> props to your target component:

exact path="/problem/:problemId" render={props => <ProblemPage {...props.match.params} />}

how to include glyphicons in bootstrap 3

I think your particular problem isn't how to use Glyphicons but understanding how Bootstrap files work together.

Bootstrap requires a specific file structure to work. I see from your code you have this:

<link href="bootstrap.css" rel="stylesheet" media="screen">

Your Bootstrap.css is being loaded from the same location as your page, this would create a problem if you didn't adjust your file structure.

But first, let me recommend you setup your folder structure like so:

/css      <-- Bootstrap.css here
/fonts    <-- Bootstrap fonts here
/img
/js       <-- Bootstrap JavaScript here
index.html

If you notice, this is also how Bootstrap structures its files in its download ZIP.

You then include your Bootstrap file like so:

<link href="css/bootstrap.css" rel="stylesheet" media="screen">
or
<link href="./css/bootstrap.css" rel="stylesheet" media="screen">
or
<link href="/css/bootstrap.css" rel="stylesheet" media="screen">

Depending on your server structure or what you're going for.

The first and second are relative to your file's current directory. The second one is just more explicit by saying "here" (./) first then css folder (/css).

The third is good if you're running a web server, and you can just use relative to root notation as the leading "/" will be always start at the root folder.

So, why do this?

Bootstrap.css has this specific line for Glyphfonts:

@font-face {
    font-family: 'Glyphicons Halflings';
    src: url('../fonts/glyphicons-halflings-regular.eot');
    src: url('../fonts/glyphicons-halflings-regular.eot?#iefix') format('embedded-opentype'), url('../fonts/glyphicons-halflings-regular.woff') format('woff'), url('../fonts/glyphicons-halflings-regular.ttf') format('truetype'), url('../fonts/glyphicons-halflings-regular.svg#glyphicons-halflingsregular') format('svg');
}

What you can see is that that Glyphfonts are loaded by going up one directory ../ and then looking for a folder called /fonts and THEN loading the font file.

The URL address is relative to the location of the CSS file. So, if your CSS file is at the same location like this:

/fonts
Bootstrap.css
index.html

The CSS file is going one level deeper than looking for a /fonts folder.

So, let's say the actual location of these files are:

C:\www\fonts
C:\www\Boostrap.css
C:\www\index.html

The CSS file would technically be looking for a folder at:

C:\fonts

but your folder is actually in:

C:\www\fonts

So see if that helps. You don't have to do anything 'special' to load Bootstrap Glyphicons, except make sure your folder structure is set up appropriately.

When you get that fixed, your HTML should simply be:

<span class="glyphicon glyphicon-comment"></span>

Note, you need both classes. The first class glyphicon sets up the basic styles while glyphicon-comment sets the specific image.

How do you access the matched groups in a JavaScript regular expression?

Last but not least, I found one line of code that worked fine for me (JS ES6):

_x000D_
_x000D_
let reg = /#([\S]+)/igm; // Get hashtags._x000D_
let string = 'mi alegría es total! ?\n#fiestasdefindeaño #PadreHijo #buenosmomentos #france #paris';_x000D_
_x000D_
let matches = (string.match(reg) || []).map(e => e.replace(reg, '$1'));_x000D_
console.log(matches);
_x000D_
_x000D_
_x000D_

This will return:

['fiestasdefindeaño', 'PadreHijo', 'buenosmomentos', 'france', 'paris']

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

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

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

? stick to the Node way and install locally

ref:

Python : Trying to POST form using requests

You can use the Session object

import requests
headers = {'User-Agent': 'Mozilla/5.0'}
payload = {'username':'niceusername','password':'123456'}

session = requests.Session()
session.post('https://admin.example.com/login.php',headers=headers,data=payload)
# the session instance holds the cookie. So use it to get/post later.
# e.g. session.get('https://example.com/profile')

MySQL Insert into multiple tables? (Database normalization?)

This is the way that I did it for a uni project, works fine, prob not safe tho

$dbhost = 'localhost';
$dbuser = 'root';
$dbpass = '';
$conn = mysql_connect($dbhost, $dbuser, $dbpass);

$title =    $_POST['title'];            
$name =     $_POST['name'];         
$surname =  $_POST['surname'];                  
$email =    $_POST['email'];            
$pass =     $_POST['password'];     
$cpass =    $_POST['cpassword'];        

$check = 1;

if (){
}
else{
    $check = 1;
}   
if ($check == 1){

require_once('website_data_collecting/db.php');

$sel_user = "SELECT * FROM users WHERE user_email='$email'";
$run_user = mysqli_query($con, $sel_user);
$check_user = mysqli_num_rows($run_user);

if ($check_user > 0){
    echo    '<div style="margin: 0 0 10px 20px;">Email already exists!</br>
             <a href="recover.php">Recover Password</a></div>';
}
else{
    $users_tb = "INSERT INTO users ". 
           "(user_name, user_email, user_password) ". 
        "VALUES('$name','$email','$pass')";

    $users_info_tb = "INSERT INTO users_info".
           "(user_title, user_surname)".
        "VALUES('$title', '$surname')";

    mysql_select_db('dropbox');
    $run_users_tb = mysql_query( $users_tb, $conn );
    $run_users_info_tb = mysql_query( $users_info_tb, $conn );

    if(!$run_users_tb || !$run_users_info_tb){
        die('Could not enter data: ' . mysql_error());
    }
    else{
        echo "Entered data successfully\n";
    }

    mysql_close($conn);
}

}

What do I do when my program crashes with exception 0xc0000005 at address 0?

Exception code 0xc0000005 is an Access Violation. An AV at fault offset 0x00000000 means that something in your service's code is accessing a nil pointer. You will just have to debug the service while it is running to find out what it is accessing. If you cannot run it inside a debugger, then at least install a third-party exception logger framework, such as EurekaLog or MadExcept, to find out what your service was doing at the time of the AV.

Text in Border CSS HTML

You can do something like this, where you set a negative margin on the h1 (or whatever header you are using)

div{
    height:100px;
    width:100px;
    border:2px solid black;
}

h1{
    width:30px;
    margin-top:-10px;
    margin-left:5px;
    background:white;
}

Note: you need to set a background as well as a width on the h1

Example: http://jsfiddle.net/ZgEMM/


EDIT

To make it work with hiding the div, you could use some jQuery like this

$('a').click(function(){
    var a = $('h1').detach();
    $('div').hide();
    $(a).prependTo('body');    
});

(You will need to modify...)

Example #2: http://jsfiddle.net/ZgEMM/4/

How to send an email with Gmail as provider using Python?

Seems like problem of the old smtplib. In python2.7 everything works fine.

Update: Yep, server.ehlo() also could help.

How to open specific tab of bootstrap nav tabs on click of a particuler link using jQuery?

HTML:

<a href="PageName.php#tabID">link to other page tab</a>

Javascript:

window.onload = function(){  

    var url = document.location.toString();
    if (url.match('#')) {
        $('.nav-tabs a[href="#' + url.split('#')[1] + '"]').tab('show');
    }

    //Change hash for page-reload
    $('.nav-tabs a[href="#' + url.split('#')[1] + '"]').on('shown', function (e) {
        window.location.hash = e.target.hash;
    }); 
} 

Regular Expression For Duplicate Words

Use this in case you want case-insensitive checking for duplicate words.

(?i)\\b(\\w+)\\s+\\1\\b

Print the contents of a DIV

The best way to do it would be to submit the contents of the div to the server and open a new window where the server could put those contents into the new window.

If that's not an option you can try to use a client-side language like javascript to hide everything on the page except that div and then print the page...

How to fill Dataset with multiple tables?

         string connetionString = null;
        SqlConnection connection ;
        SqlCommand command ;
        SqlDataAdapter adapter = new SqlDataAdapter();
        DataSet ds = new DataSet();
        int i = 0;
        string firstSql = null;
        string secondSql = null;

        connetionString = "Data Source=ServerName;Initial Catalog=DatabaseName;User ID=UserName;Password=Password";
        firstSql = "Your First SQL Statement Here";
        secondSql = "Your Second SQL Statement Here";
        connection = new SqlConnection(connetionString);

        try
        {
            connection.Open();

            command = new SqlCommand(firstSql, connection);
            adapter.SelectCommand = command;
            adapter.Fill(ds, "First Table");

            adapter.SelectCommand.CommandText = secondSql;
            adapter.Fill(ds, "Second Table");

            adapter.Dispose();
            command.Dispose();
            connection.Close();

            //retrieve first table data 
            for (i = 0; i <= ds.Tables[0].Rows.Count - 1; i++)
            {
                MessageBox.Show(ds.Tables[0].Rows[i].ItemArray[0] + " -- " + ds.Tables[0].Rows[i].ItemArray[1]);
            }
            //retrieve second table data 
            for (i = 0; i <= ds.Tables[1].Rows.Count - 1; i++)
            {
                MessageBox.Show(ds.Tables[1].Rows[i].ItemArray[0] + " -- " + ds.Tables[1].Rows[i].ItemArray[1]);

            }
        }
        catch (Exception ex)
        {
            MessageBox.Show("Can not open connection ! ");
        }

Update .NET web service to use TLS 1.2

if you're using .Net earlier than 4.5 you wont have Tls12 in the enum so state is explicitly mentioned here

ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072;

How can I get terminal output in python?

The recommended way in Python 3.5 and above is to use subprocess.run():

from subprocess import run
output = run("pwd", capture_output=True).stdout

Box shadow in IE7 and IE8

Use CSS3 PIE, which emulates some CSS3 properties in older versions of IE.

It supports box-shadow (except for the inset keyword).

How to return multiple rows from the stored procedure? (Oracle PL/SQL)

You may use Oracle pipelined functions

Basically, when you would like a PLSQL (or java or c) routine to be the «source» of data -- instead of a table -- you would use a pipelined function.

Simple Example - Generating Some Random Data
How could you create N unique random numbers depending on the input argument?

create type array
as table of number;


create function  gen_numbers(n in number default null)
return array
PIPELINED
as
begin
  for i in 1 .. nvl(n,999999999)
  loop
     pipe row(i);
 end loop;
 return;
end;

Suppose we needed three rows for something. We can now do that in one of two ways:

select * from TABLE(gen_numbers(3));

COLUMN_VALUE


       1
       2
       3

or

select * from TABLE(gen_numbers)
 where rownum <= 3;

COLUMN_VALUE


       1
       2
       3

pipelied Functions1 pipelied Functions2

Spring: Returning empty HTTP Responses with ResponseEntity<Void> doesn't work

According Spring 4 MVC ResponseEntity.BodyBuilder and ResponseEntity Enhancements Example it could be written as:

....
   return ResponseEntity.ok().build();
....
   return ResponseEntity.noContent().build();

UPDATE:

If returned value is Optional there are convinient method, returned ok() or notFound():

return ResponseEntity.of(optional)

IIS Config Error - This configuration section cannot be used at this path

I think the better way is that you must remove you configuration from your web.config. Publish your code on the server and do what you want to remove directly from the IIS server interface.

Thanks to this method if you sucessfully do what you want, you just have to get the web.config and compare the differences. After that you just have to post the solution in this post :-P.

Rounded Corners Image in Flutter

Output:

enter image description here

Using BoxDecoration

Container(
              margin: EdgeInsets.all(8),
              width: 86,
              height: 86,
              decoration: BoxDecoration(
                shape: BoxShape.circle,
                image: DecorationImage(
                    image: NetworkImage('https://i.stack.imgur.com/0VpX0.png'),
                    fit: BoxFit.cover
                ),
              ), 
           ),

How do I ignore files in Subversion?

I found the article .svnignore Example for Java.

Example: .svnignore for Ruby on Rails,

/log

/public/*.JPEG
/public/*.jpeg
/public/*.png
/public/*.gif

*.*~

And after that:

svn propset svn:ignore -F .svnignore .

Examples for .gitignore. You can use for your .svnignore

https://github.com/github/gitignore

sql try/catch rollback/commit - preventing erroneous commit after rollback

I always thought this was one of the better articles on the subject. It includes the following example that I think makes it clear and includes the frequently overlooked @@trancount which is needed for reliable nested transactions

PRINT 'BEFORE TRY'
BEGIN TRY
    BEGIN TRAN
     PRINT 'First Statement in the TRY block'
     INSERT INTO dbo.Account(AccountId, Name , Balance) VALUES(1, 'Account1',  10000)
     UPDATE dbo.Account SET Balance = Balance + CAST('TEN THOUSAND' AS MONEY) WHERE AccountId = 1
     INSERT INTO dbo.Account(AccountId, Name , Balance) VALUES(2, 'Account2',  20000)
     PRINT 'Last Statement in the TRY block'
    COMMIT TRAN
END TRY
BEGIN CATCH
    PRINT 'In CATCH Block'
    IF(@@TRANCOUNT > 0)
        ROLLBACK TRAN;

    THROW; -- raise error to the client
END CATCH
PRINT 'After END CATCH'
SELECT * FROM dbo.Account WITH(NOLOCK)
GO

The following classes could not be instantiated: - android.support.v7.widget.Toolbar

I had the same error on my Android Studio screen when i wanted to prevew my project. I fix the problem by this ways:

1- I chang the version from 22 to 21. But if I change back to version 22, the rendering breaks, if I switch back to 21, it works again. Thank you @Overloaded_Operator

I updated my Android Studio but not working. Thank you @Salvuccio96

Multiple IF AND statements excel

Consider that you have multiple "tests", e.g.,

  1. If E2 = 'in play' and F2 = 'closed', output 3
  2. If E2 = 'in play' and F2 = 'suspended', output 2
  3. Etc.

What you really need to do is put successive tests in the False argument. You're presently trying to separate each test by a comma, and that won't work.

Your first three tests can all be joined in one expression like:

=IF(E2="In Play",IF(F2="Closed",3,IF(F2="suspended",2,IF(F2="Null",1))))

Remembering that each successive test needs to be the nested FALSE argument of the preceding test, you can do this:

=IF(E2="In Play",IF(F2="Closed",3,IF(F2="suspended",2,IF(F2="Null",1))),IF(AND(E2="Pre-Play",F2="Null"),-1,IF(AND(E2="completed",F2="closed"),2,IF(AND(E2="suspended",F2="Null"),3,-2))))

Convert row to column header for Pandas DataFrame,

You can specify the row index in the read_csv or read_html constructors via the header parameter which represents Row number(s) to use as the column names, and the start of the data. This has the advantage of automatically dropping all the preceding rows which supposedly are junk.

import pandas as pd
from io import StringIO

In[1]
    csv = '''junk1, junk2, junk3, junk4, junk5
    junk1, junk2, junk3, junk4, junk5
    pears, apples, lemons, plums, other
    40, 50, 61, 72, 85
    '''

    df = pd.read_csv(StringIO(csv), header=2)
    print(df)

Out[1]
       pears   apples   lemons   plums   other
    0     40       50       61      72      85

How to test if a double is zero?

Yes; all primitive numeric types default to 0.

However, calculations involving floating-point types (double and float) can be imprecise, so it's usually better to check whether it's close to 0:

if (Math.abs(foo.x) < 2 * Double.MIN_VALUE)

You need to pick a margin of error, which is not simple.

How to make CSS3 rounded corners hide overflow in Chrome/Opera

Here look at how I done it; Jsfiddle

With the Code I put in, I managed to get it working on Webkit (Chrome/Safari) and Firefox. I don't know if it works with the latest version of Opera. Yes it does work under the latest version of Opera.

#wrapper {
  width: 300px; height: 300px;
  border-radius: 100px;
  overflow: hidden;
  position: absolute; /* this breaks the overflow:hidden in Chrome/Opera */
}

#box {
  width: 300px; height: 300px;
  background-color: #cde;
  border-radius: 100px;
  -webkit-border-radius: 100px;
  -moz-border-radius: 100px;
  -o-border-radius: 100px;
}

Representing null in JSON

According to the JSON spec, the outermost container does not have to be a dictionary (or 'object') as implied in most of the comments above. It can also be a list or a bare value (i.e. string, number, boolean or null). If you want to represent a null value in JSON, the entire JSON string (excluding the quotes containing the JSON string) is simply null. No braces, no brackets, no quotes. You could specify a dictionary containing a key with a null value ({"key1":null}), or a list with a null value ([null]), but these are not null values themselves - they are proper dictionaries and lists. Similarly, an empty dictionary ({}) or an empty list ([]) are perfectly fine, but aren't null either.

In Python:

>>> print json.loads('{"key1":null}')
{u'key1': None}
>>> print json.loads('[null]')
[None]
>>> print json.loads('[]')
[]
>>> print json.loads('{}')
{}
>>> print json.loads('null')
None

how to convert java string to Date object

var startDate = "06/27/2007";
startDate = new Date(startDate);

console.log(startDate);

A valid provisioning profile for this executable was not found... (again)

I'm still not sure what the issue was but deleting all certificates and starting over (albeit twice) eventually solved it.

My best guess is that I've missed some small but important detail of the procedure. Unfortunately I can't be any more specific than that.

Connect to Amazon EC2 file directory using Filezilla and SFTP

If anyone is following all the steps and having no success, make sure that you are using the correct user. I was attempting to use "ec2-user" but I needed to use "ubuntu."

How to set placeholder value using CSS?

If the content is loaded via ajax anyway, use javascript to manipulate the placeholder. Every css approach is hack-isch anyway. E.g. with jQuery: $('#myFieldId').attr('placeholder', 'Search for Stuff');

Passing Multiple route params in Angular2

As detailed in this answer, mayur & user3869623's answer's are now relating to a deprecated router. You can now pass multiple parameters as follows:

To call router:

this.router.navigate(['/myUrlPath', "someId", "another ID"]);

In routes.ts:

{ path: 'myUrlpath/:id1/:id2', component: componentToGoTo},

Is it possible to specify the schema when connecting to postgres with JDBC?

As of version 9.4, you can use the currentSchema parameter in your connection string.

For example:

jdbc:postgresql://localhost:5432/mydatabase?currentSchema=myschema

need to test if sql query was successful

You can use this to check if there are any results ($result) from a query:

if (mysqli_num_rows($result) != 0)
 {
  //results found
 } else {
  // results not found
 }

Unable to load DLL 'SQLite.Interop.dll'

I had this problem because a dll I was using had Sqlite as a dependency (configured in NuGet with only the Sqlite core package.). The project compiles and copies all the Sqlite dll-s except the 'SQLite.Interop.dll' (both x86 and x64 folder).

The solution was very simple: just add the System.Data.SQLite.Core package as a dependency (with NuGet) to the project you are building/running and the dll-s will be copied.

How to exit a function in bash

If you want to return from an outer function with an error without exiting you can use this trick:

do-something-complex() {
  # Using `return` here would only return from `fail`, not from `do-something-complex`.
  # Using `exit` would close the entire shell.
  # So we (ab)use a different feature. :)
  fail() { : "${__fail_fast:?$1}"; }

  nested-func() {
      try-this || fail "This didn't work"
      try-that || fail "That didn't work"
  }
  nested-func
}

Trying it out:

$ do-something-complex
try-this: command not found
bash: __fail_fast: This didn't work

This has the added benefit/drawback that you can optionally turn off this feature: __fail_fast=x do-something-complex.

Note that this causes the outermost function to return 1.

How do I make a textbox that only accepts numbers?

Using the approach described in Fabio Iotti's answer I have created a more generic solution:

public abstract class ValidatedTextBox : TextBox {
    private string m_lastText = string.Empty;
    protected abstract bool IsValid(string text);
    protected sealed override void OnTextChanged(EventArgs e) {
        if (!IsValid(Text)) {
            var pos = SelectionStart - Text.Length + m_lastText.Length;
            Text = m_lastText;
            SelectionStart = Math.Max(0, pos);
        }
        m_lastText = Text;
        base.OnTextChanged(e);
    }
}

"ValidatedTextBox", which contains all nontrivial validation behavior. All that's left to do is inherit from this class and override "IsValid" method with whatever validation logic is required. For example, using this class, it is possible to create "RegexedTextBox" which will accept only strings which match specific regular expression:

public abstract class RegexedTextBox : ValidatedTextBox {
    private readonly Regex m_regex;
    protected RegexedTextBox(string regExpString) {
        m_regex = new Regex(regExpString);
    }
    protected override bool IsValid(string text) {
        return m_regex.IsMatch(Text);
    }
}

After that, inheriting from the "RegexedTextBox" class, we can easily create "PositiveNumberTextBox" and "PositiveFloatingPointNumberTextBox" controls:

public sealed class PositiveNumberTextBox : RegexedTextBox {
    public PositiveNumberTextBox() : base(@"^\d*$") { }
}

public sealed class PositiveFloatingPointNumberTextBox : RegexedTextBox {
    public PositiveFloatingPointNumberTextBox()
        : base(@"^(\d+\" + CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator + @")?\d*$") { }
}

How does Task<int> become an int?

Does an implicit conversion occur between Task<> and int?

Nope. This is just part of how async/await works.

Any method declared as async has to have a return type of:

  • void (avoid if possible)
  • Task (no result beyond notification of completion/failure)
  • Task<T> (for a logical result of type T in an async manner)

The compiler does all the appropriate wrapping. The point is that you're asynchronously returning urlContents.Length - you can't make the method just return int, as the actual method will return when it hits the first await expression which hasn't already completed. So instead, it returns a Task<int> which will complete when the async method itself completes.

Note that await does the opposite - it unwraps a Task<T> to a T value, which is how this line works:

string urlContents = await getStringTask;

... but of course it unwraps it asynchronously, whereas just using Result would block until the task had completed. (await can unwrap other types which implement the awaitable pattern, but Task<T> is the one you're likely to use most often.)

This dual wrapping/unwrapping is what allows async to be so composable. For example, I could write another async method which calls yours and doubles the result:

public async Task<int> AccessTheWebAndDoubleAsync()
{
    var task = AccessTheWebAsync();
    int result = await task;
    return result * 2;
}

(Or simply return await AccessTheWebAsync() * 2; of course.)

How to select current date in Hive SQL

To extract the year from current date

SELECT YEAR(CURRENT_DATE())

IBM Netezza

extract(year from now())

HIVE

SELECT YEAR(CURRENT_DATE())

How can I use xargs to copy files that have spaces and quotes in their names?

Be aware that most of the options discussed in other answers are not standard on platforms that do not use the GNU utilities (Solaris, AIX, HP-UX, for instance). See the POSIX specification for 'standard' xargs behaviour.

I also find the behaviour of xargs whereby it runs the command at least once, even with no input, to be a nuisance.

I wrote my own private version of xargs (xargl) to deal with the problems of spaces in names (only newlines separate - though the 'find ... -print0' and 'xargs -0' combination is pretty neat given that file names cannot contain ASCII NUL '\0' characters. My xargl isn't as complete as it would need to be to be worth publishing - especially since GNU has facilities that are at least as good.

jQuery ajax error function

Here is how you pull the asp error out.

              cache: false,
              url: "addInterview_Code.asp",
              type: "POST",
              datatype: "text",
              data: strData,
              success: function (html) {
                  alert('successful : ' + html);
                  $("#result").html("Successful");
              },
              error: function (jqXHR, textStatus, errorThrown) {
                  if (jqXHR.status == 500) {
                      alert('Internal error: ' + jqXHR.responseText);
                  } else {
                      alert('Unexpected error.');
                  }
              }

REST response code for invalid data

It is amusing to return 418 I'm a teapot to requests that are obviously crafted or malicious and "can't happen", such as failing CSRF check or missing request properties.

2.3.2 418 I'm a teapot

Any attempt to brew coffee with a teapot should result in the error code "418 I'm a teapot". The resulting entity body MAY be short and stout.

To keep it reasonably serious, I restrict usage of funny error codes to RESTful endpoints that are not directly exposed to the user.

Tensorflow: Using Adam optimizer

The AdamOptimizer class creates additional variables, called "slots", to hold values for the "m" and "v" accumulators.

See the source here if you're curious, it's actually quite readable: https://github.com/tensorflow/tensorflow/blob/master/tensorflow/python/training/adam.py#L39 . Other optimizers, such as Momentum and Adagrad use slots too.

These variables must be initialized before you can train a model.

The normal way to initialize variables is to call tf.initialize_all_variables() which adds ops to initialize the variables present in the graph when it is called.

(Aside: unlike its name suggests, initialize_all_variables() does not initialize anything, it only add ops that will initialize the variables when run.)

What you must do is call initialize_all_variables() after you have added the optimizer:

...build your model...
# Add the optimizer
train_op = tf.train.AdamOptimizer(1e-4).minimize(cross_entropy)
# Add the ops to initialize variables.  These will include 
# the optimizer slots added by AdamOptimizer().
init_op = tf.initialize_all_variables()

# launch the graph in a session
sess = tf.Session()
# Actually intialize the variables
sess.run(init_op)
# now train your model
for ...:
  sess.run(train_op)

How to compare arrays in JavaScript?

Here's a CoffeeScript version, for those who prefer that:

Array.prototype.equals = (array) ->
  return false if not array # if the other array is a falsy value, return
  return false if @length isnt array.length # compare lengths - can save a lot of time

  for item, index in @
    if item instanceof Array and array[index] instanceof Array # Check if we have nested arrays
      if not item.equals(array[index]) # recurse into the nested arrays
        return false
    else if this[index] != array[index]
      return false # Warning - two different object instances will never be equal: {x:20} != {x:20}
  true

All credits goes to @tomas-zato.

How to tell CRAN to install package dependencies automatically?

On your own system, try

install.packages("foo", dependencies=...)

with the dependencies= argument is documented as

dependencies: logical indicating to also install uninstalled packages
      which these packages depend on/link to/import/suggest (and so
      on recursively).  Not used if ‘repos = NULL’.  Can also be a
      character vector, a subset of ‘c("Depends", "Imports",
      "LinkingTo", "Suggests", "Enhances")’.

      Only supported if ‘lib’ is of length one (or missing), so it
      is unambiguous where to install the dependent packages.  If
      this is not the case it is ignored, with a warning.

      The default, ‘NA’, means ‘c("Depends", "Imports",
      "LinkingTo")’.

      ‘TRUE’ means (as from R 2.15.0) to use ‘c("Depends",
      "Imports", "LinkingTo", "Suggests")’ for ‘pkgs’ and
      ‘c("Depends", "Imports", "LinkingTo")’ for added
      dependencies: this installs all the packages needed to run
      ‘pkgs’, their examples, tests and vignettes (if the package
      author specified them correctly).

so you probably want a value TRUE.

In your package, list what is needed in Depends:, see the Writing R Extensions manual which is pretty clear on this.

Django values_list vs values

You can get the different values with:

set(Article.objects.values_list('comment_id', flat=True))

replace anchor text with jquery

function liReplace(replacement) {
    $(".dropit-submenu li").each(function() {
        var t = $(this);
        t.html(t.html().replace(replacement, "*" + replacement + "*"));
        t.children(":first").html(t.children(":first").html().replace(replacement, "*" +` `replacement + "*"));
        t.children(":first").html(t.children(":first").html().replace(replacement + " ", ""));
        alert(t.children(":first").text());
    });
}
  • First code find a title replace t.html(t.html()
  • Second code a text replace t.children(":first")

Sample <a title="alpc" href="#">alpc</a>

Convert a dataframe to a vector (by rows)

You can try this to get your combination:

as.numeric(rbind(test$x, test$y))

which will return:

26, 34, 21, 29, 20, 28

How to set cookie in node js using express framework?

Set Cookie?

res.cookie('cookieName', 'cookieValue')

Read Cookie?

req.cookies

Demo

const express('express')
    , cookieParser = require('cookie-parser'); // in order to read cookie sent from client

app.get('/', (req,res)=>{

    // read cookies
    console.log(req.cookies) 

    let options = {
        maxAge: 1000 * 60 * 15, // would expire after 15 minutes
        httpOnly: true, // The cookie only accessible by the web server
        signed: true // Indicates if the cookie should be signed
    }

    // Set cookie
    res.cookie('cookieName', 'cookieValue', options) // options is optional
    res.send('')

})

How to deploy a war file in JBoss AS 7?

Actually, for the latest JBOSS 7 AS, we need a .dodeploy marker even for archives. So add a marker to trigger the deployment.

In my case, I added a Hello.war.deployed file in the same directory and then everything worked fine.

Hope this helps someone!

Using GregorianCalendar with SimpleDateFormat

Why such complications?

public static GregorianCalendar convertFromDMY(String dd_mm_yy) throws ParseException 
{
    SimpleDateFormat fmt = new SimpleDateFormat("dd-MMM-yyyy");
    Date date = fmt.parse(dd_mm_yy);
    GregorianCalendar cal = GregorianCalendar.getInstance();
    cal.setTime(date);
    return cal;
}

Locking pattern for proper use of .NET MemoryCache

This is my 2nd iteration of the code. Because MemoryCache is thread safe you don't need to lock on the initial read, you can just read and if the cache returns null then do the lock check to see if you need to create the string. It greatly simplifies the code.

const string CacheKey = "CacheKey";
static readonly object cacheLock = new object();
private static string GetCachedData()
{

    //Returns null if the string does not exist, prevents a race condition where the cache invalidates between the contains check and the retreival.
    var cachedString = MemoryCache.Default.Get(CacheKey, null) as string;

    if (cachedString != null)
    {
        return cachedString;
    }

    lock (cacheLock)
    {
        //Check to see if anyone wrote to the cache while we where waiting our turn to write the new value.
        cachedString = MemoryCache.Default.Get(CacheKey, null) as string;

        if (cachedString != null)
        {
            return cachedString;
        }

        //The value still did not exist so we now write it in to the cache.
        var expensiveString = SomeHeavyAndExpensiveCalculation();
        CacheItemPolicy cip = new CacheItemPolicy()
                              {
                                  AbsoluteExpiration = new DateTimeOffset(DateTime.Now.AddMinutes(20))
                              };
        MemoryCache.Default.Set(CacheKey, expensiveString, cip);
        return expensiveString;
    }
}

EDIT: The below code is unnecessary but I wanted to leave it to show the original method. It may be useful to future visitors who are using a different collection that has thread safe reads but non-thread safe writes (almost all of classes under the System.Collections namespace is like that).

Here is how I would do it using ReaderWriterLockSlim to protect access. You need to do a kind of "Double Checked Locking" to see if anyone else created the cached item while we where waiting to to take the lock.

const string CacheKey = "CacheKey";
static readonly ReaderWriterLockSlim cacheLock = new ReaderWriterLockSlim();
static string GetCachedData()
{
    //First we do a read lock to see if it already exists, this allows multiple readers at the same time.
    cacheLock.EnterReadLock();
    try
    {
        //Returns null if the string does not exist, prevents a race condition where the cache invalidates between the contains check and the retreival.
        var cachedString = MemoryCache.Default.Get(CacheKey, null) as string;

        if (cachedString != null)
        {
            return cachedString;
        }
    }
    finally
    {
        cacheLock.ExitReadLock();
    }

    //Only one UpgradeableReadLock can exist at one time, but it can co-exist with many ReadLocks
    cacheLock.EnterUpgradeableReadLock();
    try
    {
        //We need to check again to see if the string was created while we where waiting to enter the EnterUpgradeableReadLock
        var cachedString = MemoryCache.Default.Get(CacheKey, null) as string;

        if (cachedString != null)
        {
            return cachedString;
        }

        //The entry still does not exist so we need to create it and enter the write lock
        var expensiveString = SomeHeavyAndExpensiveCalculation();
        cacheLock.EnterWriteLock(); //This will block till all the Readers flush.
        try
        {
            CacheItemPolicy cip = new CacheItemPolicy()
            {
                AbsoluteExpiration = new DateTimeOffset(DateTime.Now.AddMinutes(20))
            };
            MemoryCache.Default.Set(CacheKey, expensiveString, cip);
            return expensiveString;
        }
        finally 
        {
            cacheLock.ExitWriteLock();
        }
    }
    finally
    {
        cacheLock.ExitUpgradeableReadLock();
    }
}

Jinja2 shorthand conditional

Yes, it's possible to use inline if-expressions:

{{ 'Update' if files else 'Continue' }}

How to uninstall Python 2.7 on a Mac OS X 10.6.4?

Create the symlink to latest version

 ln -s -f /usr/local/bin/python3.8 /usr/local/bin/python

Close and open a new terminal

and try

 python --version

What's the Kotlin equivalent of Java's String[]?

There's no special case for String, because String is an ordinary referential type on JVM, in contrast with Java primitives (int, double, ...) -- storing them in a reference Array<T> requires boxing them into objects like Integer and Double. The purpose of specialized arrays like IntArray in Kotlin is to store non-boxed primitives, getting rid of boxing and unboxing overhead (the same as Java int[] instead of Integer[]).

You can use Array<String> (and Array<String?> for nullables), which is equivalent to String[] in Java:

val stringsOrNulls = arrayOfNulls<String>(10) // returns Array<String?>
val someStrings = Array<String>(5) { "it = $it" }
val otherStrings = arrayOf("a", "b", "c")

See also: Arrays in the language reference

Generating random numbers in Objective-C

I thought I could add a method I use in many projects.

- (NSInteger)randomValueBetween:(NSInteger)min and:(NSInteger)max {
    return (NSInteger)(min + arc4random_uniform(max - min + 1));
}

If I end up using it in many files I usually declare a macro as

#define RAND_FROM_TO(min, max) (min + arc4random_uniform(max - min + 1))

E.g.

NSInteger myInteger = RAND_FROM_TO(0, 74) // 0, 1, 2,..., 73, 74

Note: Only for iOS 4.3/OS X v10.7 (Lion) and later

Add Insecure Registry to Docker

I happened to encounter a similar kind of issue after setting up local internal JFrog Docker Private Registry on Amazon Linux.

THE followings I did to solve the issue:

Added "--insecure-registry xx.xx.xx.xx:8081" by modifying the OPTIONS variable in the /etc/sysconfig/docker file:

OPTIONS="--default-ulimit nofile=1024:40961 --insecure-registry hostname:8081"

Then restarted the docker.

I was then able to login to the local docker registry using:

docker login -u admin -p password hostname:8081

Android - Set text to TextView

In your layout. Your Texto should not contain (android:text=...). I would remove this line. Either keep the Java string OR the (android:text=...)

Can vue-router open a link in a new tab?

It seems like this is now possible in newer versions (Vue Router 3.0.1):

<router-link :to="{ name: 'fooRoute'}" target="_blank">
  Link Text
</router-link>

How do I import a namespace in Razor View Page?

Finally found the answer.

@using MyNamespace

For VB.Net:

@Imports Mynamespace

Take a look at @ravy amiry's answer if you want to include a namespace across the app.

Sorting a vector of custom objects

Yes, std::sort() with third parameter (function or object) would be easier. An example: http://www.cplusplus.com/reference/algorithm/sort/

Materialize CSS - Select Doesn't Seem to Render

I found myself in a situation where using the solution selected

$(document).ready(function() {
$('select').material_select();
}); 

for whatever reason was throwing errors because the material_select() function could not be found. It was not possible to just say <select class="browser-default... Because I was using a framework which auto-rendered the the forms. So my solution was to add the class using js(Jquery)

<script>
 $(document).ready(function() {
   $('select').attr("class", "browser-default")
});

process.env.NODE_ENV is undefined

In UBUNTU use:

$ export NODE_ENV=test

Controlling Maven final name of jar artifact

At the package stage, the plugin allows configuration of the imported file names via file mapping:

maven-ear-plugin

http://maven.apache.org/plugins/maven-ear-plugin/examples/customize-file-name-mapping.html

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-ear-plugin</artifactId>
    <version>2.7</version>
    <configuration>
       [...]
        <fileNameMapping>full</fileNameMapping>
    </configuration>
</plugin>

http://maven.apache.org/plugins/maven-war-plugin/war-mojo.html#outputFileNameMapping

If you have configured your version to be 'testing' via a profile or something, this would work for a war package:

maven-war-plugin

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-war-plugin</artifactId>
    <version>2.2</version>
    <configuration>
        <encoding>UTF-8</encoding>                        
        <outputFileNameMapping>@{groupId}@-@{artifactId}@-@{baseVersion}@@{dashClassifier?}@.@{extension}@</outputFileNameMapping>
    </configuration>
</plugin>

Remove all stylings (border, glow) from textarea

If you want to remove EVERYTHING :

textarea {
    border: none;
    background-color: transparent;
    resize: none;
    outline: none;
}

Apache and Node.js on the Same Server

Running Node and Apache on one server is trivial as they don't conflict. NodeJS is just a way to execute JavaScript server side. The real dilemma comes from accessing both Node and Apache from outside. As I see it you have two choices:

  1. Set up Apache to proxy all matching requests to NodeJS, which will do the file uploading and whatever else in node.

  2. Have Apache and Node on different IP:port combinations (if your server has two IPs, then one can be bound to your node listener, the other to Apache).

I'm also beginning to suspect that this might not be what you are actually looking for. If your end goal is for you to write your application logic in Nodejs and some "file handling" part that you off-load to a contractor, then its really a choice of language, not a web server.

How to check if a variable is equal to one string or another string?

if var == 'stringone' or var == 'stringtwo':
    dosomething()

'is' is used to check if the two references are referred to a same object. It compare the memory address. Apparently, 'stringone' and 'var' are different objects, they just contains the same string, but they are two different instances of the class 'str'. So they of course has two different memory addresses, and the 'is' will return False.

Getting the thread ID from a thread

You can use Thread.GetHashCode, which returns the managed thread ID. If you think about the purpose of GetHashCode, this makes good sense -- it needs to be a unique identifier (e.g. key in a dictionary) for the object (the thread).

The reference source for the Thread class is instructive here. (Granted, a particular .NET implementation may not be based on this source code, but for debugging purposes I'll take my chances.)

GetHashCode "provides this hash code for algorithms that need quick checks of object equality," so it is well-suited for checking Thread equality -- for example to assert that a particular method is executing on the thread you wanted it called from.

How to get "their" changes in the middle of conflicting Git rebase?

You want to use:

git checkout --ours foo/bar.java
git add foo/bar.java

If you rebase a branch feature_x against main (i.e. running git rebase main while on branch feature_x), during rebasing ours refers to main and theirs to feature_x.

As pointed out in the git-rebase docs:

Note that a rebase merge works by replaying each commit from the working branch on top of the branch. Because of this, when a merge conflict happens, the side reported as ours is the so-far rebased series, starting with <upstream>, and theirs is the working branch. In other words, the sides are swapped.

For further details read this thread.

Error: vector does not name a type

use:

std::vector <Acard> playerHand;

everywhere qualify it by std::

or do:

using std::vector;

in your cpp file.

You have to do this because vector is defined in the std namespace and you do not tell your program to find it in std namespace, you need to tell that.

How to save a data.frame in R?

Let us say you have a data frame you created and named "Data_output", you can simply export it to same directory by using the following syntax.

write.csv(Data_output, "output.csv", row.names = F, quote = F)

credit to Peter and Ilja, UMCG, the Netherlands

REST API error return good practices

I know this is extremely late to the party, but now, in year 2013, we have a few media types to cover error handling in a common distributed (RESTful) fashion. See "vnd.error", application/vnd.error+json (https://github.com/blongden/vnd.error) and "Problem Details for HTTP APIs", application/problem+json (https://tools.ietf.org/html/draft-nottingham-http-problem-05).

No mapping found for HTTP request with URI.... in DispatcherServlet with name

Removing the Tomcat Server and adding new tomcat configuration in Eclipse resolved issue for me.

S3 limit to objects in a bucket

According to Amazon:

Write, read, and delete objects containing from 0 bytes to 5 terabytes of data each. The number of objects you can store is unlimited.

Source: http://aws.amazon.com/s3/details/ as of Sep 3, 2015.

PHP cURL HTTP PUT

Using Postman for Chrome, selecting CODE you get this... And works

_x000D_
_x000D_
<?php_x000D_
_x000D_
$curl = curl_init();_x000D_
_x000D_
curl_setopt_array($curl, array(_x000D_
  CURLOPT_URL => "https://blablabla.com/comorl",_x000D_
  CURLOPT_RETURNTRANSFER => true,_x000D_
  CURLOPT_ENCODING => "",_x000D_
  CURLOPT_MAXREDIRS => 10,_x000D_
  CURLOPT_TIMEOUT => 30,_x000D_
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,_x000D_
  CURLOPT_CUSTOMREQUEST => "PUT",_x000D_
  CURLOPT_POSTFIELDS => "{\n  \"customer\" : \"con\",\n  \"customerID\" : \"5108\",\n  \"customerEmail\" : \"[email protected]\",\n  \"Phone\" : \"34600000000\",\n  \"Active\" : false,\n  \"AudioWelcome\" : \"https://audio.com/welcome-defecto-es.mp3\"\n\n}",_x000D_
  CURLOPT_HTTPHEADER => array(_x000D_
    "cache-control: no-cache",_x000D_
    "content-type: application/json",_x000D_
    "x-api-key: whateveriyouneedinyourheader"_x000D_
  ),_x000D_
));_x000D_
_x000D_
$response = curl_exec($curl);_x000D_
$err = curl_error($curl);_x000D_
_x000D_
curl_close($curl);_x000D_
_x000D_
if ($err) {_x000D_
  echo "cURL Error #:" . $err;_x000D_
} else {_x000D_
  echo $response;_x000D_
}_x000D_
_x000D_
?>
_x000D_
_x000D_
_x000D_

SQL - IF EXISTS UPDATE ELSE INSERT INTO

Try this:

INSERT INTO `center_course_fee` (`fk_course_id`,`fk_center_code`,`course_fee`) VALUES ('69', '4920153', '6000') ON DUPLICATE KEY UPDATE `course_fee` = '6000';

Difference between == and === in JavaScript

Take a look here: http://longgoldenears.blogspot.com/2007/09/triple-equals-in-javascript.html

The 3 equal signs mean "equality without type coercion". Using the triple equals, the values must be equal in type as well.

0 == false   // true
0 === false  // false, because they are of a different type
1 == "1"     // true, automatic type conversion for value only
1 === "1"    // false, because they are of a different type
null == undefined // true
null === undefined // false
'0' == false // true
'0' === false // false

True/False vs 0/1 in MySQL

Bit is also an option if tinyint isn't to your liking. A few links:

Not surprisingly, more info about numeric types is available in the manual.

One more link: http://blog.mclaughlinsoftware.com/2010/02/26/mysql-boolean-data-type/

And a quote from the comment section of the article above:

  • TINYINT(1) isn’t a synonym for bit(1).
  • TINYINT(1) can store -9 to 9.
  • TINYINT(1) UNSIGNED: 0-9
  • BIT(1): 0, 1. (Bit, literally).

Edit: This edit (and answer) is only remotely related to the original question...

Additional quotes by Justin Rovang and the author maclochlainn (comment section of the linked article).

Excuse me, seems I’ve fallen victim to substr-ism: TINYINT(1): -128-+127 TINYINT(1) UNSIGNED: 0-255 (Justin Rovang 25 Aug 11 at 4:32 pm)

True enough, but the post was about what PHPMyAdmin listed as a Boolean, and there it only uses 0 or 1 from the entire wide range of 256 possibilities. (maclochlainn 25 Aug 11 at 11:35 pm)

jQuery: How to get the event object in an event handler function without passing it as an argument?

in IE you can get the event object by window.event in other browsers with no 'use strict' directive, it is possible to get by arguments.callee.caller.arguments[0].

function myFunc(p1, p2, p3) {
    var evt = window.event || arguments.callee.caller.arguments[0];
}

Tool for comparing 2 binary files in Windows

I prefer to use objcopy to convert to hex, then use diff.

How to convert md5 string to normal text?

I you send passwords to users in an email, you might as well have no passwords at all.

You cannot reverse the MD5 function, so your only option is to generate a new password and send that to the user (preferably over some secure channel).

Can Android do peer-to-peer ad-hoc networking?

you can connect your android device to a known ad-hoc network.

edit /system/etc/wifi/tiwlan.ini

WiFiAdhoc = 1
dot11DesiredSSID = <your_network_ssid>
dot11DesiredBSSType = 0 

edit /data/misc/wifi/wpa_supplicant.conf

ctrl_interface=tiwlan0
update_config=1
eapol_version=1
ap_scan=2

if that is too simplistic, see these instructions.

How can I check if an InputStream is empty without reading from it?

Without reading you can't do this. But you can use a work around like below.

You can use mark() and reset() methods to do this.

mark(int readlimit) method marks the current position in this input stream.

reset() method repositions this stream to the position at the time the mark method was last called on this input stream.

Before you can use the mark and reset, you need to test out whether these operations are supported on the inputstream you’re reading off. You can do that with markSupported.

The mark method accepts an limit (integer), which denotes the maximum number of bytes that are to be read ahead. If you read more than this limit, you cannot return to this mark.

To apply this functionalities for this use case, we need to mark the position as 0 and then read the input stream. There after we need to reset the input stream and the input stream will be reverted to the original one.

    if (inputStream.markSupported()) {
          inputStream.mark(0);
          if (inputStream.read() != -1) {
               inputStream.reset();
          } else {
               //Inputstream is empty
          }
    }

Here if the input stream is empty then read() method will return -1.

Problems with Android Fragment back stack

executePendingTransactions() , commitNow() not worked (

Worked in androidx (jetpack).

private final FragmentManager fragmentManager = getSupportFragmentManager();

public void removeFragment(FragmentTag tag) {
    Fragment fragmentRemove = fragmentManager.findFragmentByTag(tag.toString());
    if (fragmentRemove != null) {
        fragmentManager.beginTransaction()
                .remove(fragmentRemove)
                .commit();

        // fix by @Ogbe
        fragmentManager.popBackStackImmediate(tag.toString(), 
            FragmentManager.POP_BACK_STACK_INCLUSIVE);
    }
}

How to programmatically move, copy and delete files and directories on SD?

Copy file using Square's Okio:

BufferedSink bufferedSink = Okio.buffer(Okio.sink(destinationFile));
bufferedSink.writeAll(Okio.source(sourceFile));
bufferedSink.close();

Re-doing a reverted merge in Git

To revert a revert in GIT:

git revert <commit-hash-of-previous-revert>

NSString property: copy or retain?

For strings in general, is it always a good idea to use the copy attribute instead of retain?

Yes - in general always use the copy attribute.

This is because your NSString property can be passed an NSString instance or an NSMutableString instance, and therefore we can not really determine if the value being passed is an immutable or mutable object.

Is a "copied" property in any way less efficient than such a "retain-ed" property?

  • If your property is being passed an NSString instance, the answer is "No" - copying is not less efficient than retain.
    (It's not less efficient because the NSString is smart enough to not actually perform a copy.)

  • If your property is passed an NSMutableString instance then the answer is "Yes" - copying is less efficient than retain.
    (It's less efficient because an actual memory allocation and copy must occur, but this is probably a desirable thing.)

  • Generally speaking a "copied" property has the potential to be less efficient - however through the use of the NSCopying protocol, it's possible to implement a class which is "just as efficient" to copy as it is to retain. NSString instances are an example of this.

Generally (not just for NSString), when should I use "copy" instead of "retain"?

You should always use copy when you don't want the internal state of the property changing without warning. Even for immutable objects - properly written immutable objects will handle copy efficiently (see next section regarding immutability and NSCopying).

There may be performance reasons to retain objects, but it comes with a maintenance overhead - you must manage the possibility of the internal state changing outside your code. As they say - optimize last.

But, I wrote my class to be immutable - can't I just "retain" it?

No - use copy. If your class is really immutable then it's best practice to implement the NSCopying protocol to make your class return itself when copy is used. If you do this:

  • Other users of your class will gain the performance benefits when they use copy.
  • The copy annotation makes your own code more maintainable - the copy annotation indicates that you really don't need to worry about this object changing state elsewhere.

Eclipse "this compilation unit is not on the build path of a java project"

This is what was missing in my .project file:

    <projectDescription>
        ...
        <buildSpec>
            <buildCommand>
                <name>org.eclipse.jdt.core.javabuilder</name>
                <arguments>
                </arguments>
            </buildCommand>
        </buildspec>
        ...
        ...
        ...
        <natures>
            <nature>org.eclipse.jdt.core.javanature</nature>
            <nature>org.eclipse.m2e.core.maven2Nature</nature>
        </natures>
        ...
    </projectDescription>

No plot window in matplotlib

pylab.show() works but blocks (you need to close the window).

A much more convenient solution is to do pylab.ion() (interactive mode on) when you start: all (the pylab equivalents of) pyplot.* commands display their plot immediately. More information on the interactive mode can be found on the official web site.

I also second using the even more convenient ipython -pylab (--pylab, in newer versions), which allows you to skip the from … import … part (%pylab works, too, in newer IPython versions).

What is ADT? (Abstract Data Type)

Abstract data type are like user defined data type on which we can perform functions without knowing what is there inside the datatype and how the operations are performed on them . As the information is not exposed its abstracted. eg. List,Array, Stack, Queue. On Stack we can perform functions like Push, Pop but we are not sure how its being implemented behind the curtains.

Form/JavaScript not working on IE 11 with error DOM7011

I run into this when click on a html , it is fixed by adding type = "button" attribute.

How to compile a static library in Linux?

Here a full makefile example:

makefile

TARGET = prog

$(TARGET): main.o lib.a
    gcc $^ -o $@

main.o: main.c
    gcc -c $< -o $@

lib.a: lib1.o lib2.o
    ar rcs $@ $^

lib1.o: lib1.c lib1.h
    gcc -c -o $@ $<

lib2.o: lib2.c lib2.h
    gcc -c -o $@ $<

clean:
    rm -f *.o *.a $(TARGET)

explaining the makefile:

  • target: prerequisites - the rule head
  • $@ - means the target
  • $^ - means all prerequisites
  • $< - means just the first prerequisite
  • ar - a Linux tool to create, modify, and extract from archives see the man pages for further information. The options in this case mean:
    • r - replace files existing inside the archive
    • c - create a archive if not already existent
    • s - create an object-file index into the archive

To conclude: The static library under Linux is nothing more than a archive of object files.

main.c using the lib

#include <stdio.h>

#include "lib.h"

int main ( void )
{
    fun1(10);
    fun2(10);
    return 0;
}

lib.h the libs main header

#ifndef LIB_H_INCLUDED
#define LIB_H_INCLUDED

#include "lib1.h"
#include "lib2.h"

#endif

lib1.c first lib source

#include "lib1.h"

#include <stdio.h>

void fun1 ( int x )
{
    printf("%i\n",x);
}

lib1.h the corresponding header

#ifndef LIB1_H_INCLUDED
#define LIB1_H_INCLUDED

#ifdef __cplusplus
   extern “C” {
#endif

void fun1 ( int x );

#ifdef __cplusplus
   }
#endif

#endif /* LIB1_H_INCLUDED */

lib2.c second lib source

#include "lib2.h"

#include <stdio.h>

void fun2 ( int x )
{
    printf("%i\n",2*x);
}

lib2.h the corresponding header

#ifndef LIB2_H_INCLUDED
#define LIB2_H_INCLUDED

#ifdef __cplusplus
   extern “C” {
#endif

void fun2 ( int x );

#ifdef __cplusplus
   }
#endif

#endif /* LIB2_H_INCLUDED */

When to use RDLC over RDL reports?

If you have a reporting services infrastructure available to you, use it. You will find RDL development to be a bit more pleasant. You can preview the report, easily setup parameters, etc.

Generate HTML table from 2D JavaScript array

Here is an example of how you can generate and read data from a matrix m x n... in JavaScript

let createMatrix = (m, n) => {
      let [row, column] = [[], []],
          rowColumn = m * n
      for (let i = 1; i <= rowColumn; i++) {
        column.push(i)
        if (i % n === 0) {
          row.push(column)
          column = []
        }
      }
      return row
    }

let setColorForEachElement = (matrix, colors) => {
  let row = matrix.map(row => {
    let column = row.map((column, key) => {
      return { number: column, color: colors[key] }
    })
    return column
  })
  return row
} 

const colors = ['red', 'green', 'blue', 'purple', 'brown', 'yellow', 'orange', 'grey']
const matrix = createMatrix(6, 8)
const colorApi = setColorForEachElement(matrix, colors)

let table ='<table>'
colorApi.forEach(row => {
  table+= '<tr>'
    row.forEach(column =>  table += `<td style='background: ${column.color};'>${column.number}<td>` )
  table+='</tr>'
})
table+= '</table>'
document.write(table);

How do I kill a process using Vb.NET or C#?

In my tray app, I needed to clean Excel and Word Interops. So This simple method kills processes generically.

This uses a general exception handler, but could be easily split for multiple exceptions like stated in other answers. I may do this if my logging produces alot of false positives (ie can't kill already killed). But so far so guid (work joke).

/// <summary>
/// Kills Processes By Name
/// </summary>
/// <param name="names">List of Process Names</param>
private void killProcesses(List<string> names)
{
    var processes = new List<Process>();
    foreach (var name in names)
        processes.AddRange(Process.GetProcessesByName(name).ToList());
    foreach (Process p in processes)
    {
        try
        {
            p.Kill();
            p.WaitForExit();
        }
        catch (Exception ex)
        {
            // Logging
            RunProcess.insertFeedback("Clean Processes Failed", ex);
        }
    }
}

This is how i called it then:

killProcesses((new List<string>() { "winword", "excel" }));

how to overcome ERROR 1045 (28000): Access denied for user 'ODBC'@'localhost' (using password: NO) permanently

I know it's been three years since this was asked, but I just figured out this problem for myself. I was using into outfile and getting the error. When I commented out this part of the query, it worked.

The FILE privilege is separate from all the others and must be granted to the user running the script.

GRANT FILE ON *.* TO 'asdfsdf'@'localhost';

There has been an error processing your request, Error log record number

A common solution is to upgrade magento setup by running this command

php bin/magento setup:upgrade && php bin/magento setup:di:compile

Otherwise just check var/report/{error number}

Can a html button perform a POST request?

You can do that with a little help of JS. In the example below, a POST request is being submitted on a button click using the fetch method:

_x000D_
_x000D_
const button = document.getElementById('post-btn');_x000D_
_x000D_
button.addEventListener('click', async _ => {_x000D_
  try {     _x000D_
    const response = await fetch('yourUrl', {_x000D_
      method: 'post',_x000D_
      body: {_x000D_
        // Your body_x000D_
      }_x000D_
    });_x000D_
    console.log('Completed!', response);_x000D_
  } catch(err) {_x000D_
    console.error(`Error: ${err}`);_x000D_
  }_x000D_
});
_x000D_
<button id="post-btn">I'm a button</button>
_x000D_
_x000D_
_x000D_

Why do you need ./ (dot-slash) before executable or script name to run it in bash?

When bash interprets the command line, it looks for commands in locations described in the environment variable $PATH. To see it type:

echo $PATH

You will have some paths separated by colons. As you will see the current path . is usually not in $PATH. So Bash cannot find your command if it is in the current directory. You can change it by having:

PATH=$PATH:.

This line adds the current directory in $PATH so you can do:

manage.py syncdb

It is not recommended as it has security issue, plus you can have weird behaviours, as . varies upon the directory you are in :)

Avoid:

PATH=.:$PATH

As you can “mask” some standard command and open the door to security breach :)

Just my two cents.

How can I compare strings in C using a `switch` statement?

There is no way to do this in C. There are a lot of different approaches. Typically the simplest is to define a set of constants that represent your strings and do a look up by string on to get the constant:

#define BADKEY -1
#define A1 1
#define A2 2
#define B1 3
#define B2 4

typedef struct { char *key; int val; } t_symstruct;

static t_symstruct lookuptable[] = {
    { "A1", A1 }, { "A2", A2 }, { "B1", B1 }, { "B2", B2 }
};

#define NKEYS (sizeof(lookuptable)/sizeof(t_symstruct))

int keyfromstring(char *key)
{
    int i;
    for (i=0; i < NKEYS; i++) {
        t_symstruct *sym = lookuptable[i];
        if (strcmp(sym->key, key) == 0)
            return sym->val;
    }
    return BADKEY;
}

/* ... */
switch (keyfromstring(somestring)) {
case A1: /* ... */ break;
case A2: /* ... */ break;
case B1: /* ... */ break;
case B2: /* ... */ break;
case BADKEY: /* handle failed lookup */
}

There are, of course, more efficient ways to do this. If you keep your keys sorted, you can use a binary search. You could use a hashtable too. These things change your performance at the expense of maintenance.

implementing merge sort in C++

This would be easy to understand:

#include <iostream>

using namespace std;

void Merge(int *a, int *L, int *R, int p, int q)
{
    int i, j=0, k=0;
    for(i=0; i<p+q; i++)
    {
        if(j==p)                       //When array L is empty
        {
            *(a+i) = *(R+k);
            k++;
        }
        else if(k==q)                  //When array R is empty
        {
            *(a+i) = *(L+j);
            j++;
        }
        else if(*(L+j) < *(R+k))  //When element in L is smaller than element in R
        {
            *(a+i) = *(L+j);
            j++;
        }
        else   //When element in R is smaller or equal to element in L
        {
            *(a+i) = *(R+k);
            k++;
        }
    }
}

void MergeSort(int *a, int len)
{
    int i, j;
    if(len > 1)
    {
        int p = len/2 + len%2;      //length of first array
        int q = len/2;              //length of second array
        int L[p];                   //first array
        int R[q];                   //second array
        for(i=0; i<p; i++)
        {
            L[i] = *(a+i);      //inserting elements in first array
        }
        for(i=0; i<q; i++)
        {
            R[i] = *(a+p+i);    //inserting elements in second array
        }
        MergeSort(&L[0], p);
        MergeSort(&R[0], q);
        Merge(a, &L[0], &R[0], p, q);   //Merge arrays L and R into A
    }
    else
    {
        return;        //if array only have one element just return
    }
}

int main()
{
    int i, n;
    int a[100000];
    cout<<"Enter numbers to sort. When you are done, enter -1\n";
    i=0;
    while(true)
    {
        cin>>n;
        if(n==-1)
        {
            break;
        }
        else
        {
            a[i] = n;
            i++;
        }
    }
    int len = i;
    MergeSort(&a[0], len);
    for(i=0; i<len; i++)
    {
        cout<<a[i]<<" ";
    }

    return 0;
}

Excel VBA function to print an array to the workbook

My tested version

Sub PrintArray(RowPrint, ColPrint, ArrayName, WorkSheetName)

Sheets(WorkSheetName).Range(Cells(RowPrint, ColPrint), _
Cells(RowPrint + UBound(ArrayName, 2) - 1, _
ColPrint + UBound(ArrayName, 1) - 1)) = _
WorksheetFunction.Transpose(ArrayName)

End Sub

Node JS Promise.all and forEach

Just to add to the solution presented, in my case I wanted to fetch multiple data from Firebase for a list of products. Here is how I did it:

useEffect(() => {
  const fn = p => firebase.firestore().doc(`products/${p.id}`).get();
  const actions = data.occasion.products.map(fn);
  const results = Promise.all(actions);
  results.then(data => {
    const newProducts = [];
    data.forEach(p => {
      newProducts.push({ id: p.id, ...p.data() });
    });
    setProducts(newProducts);
  });
}, [data]);

Twig: in_array or similar possible within if statement?

another example following @jake stayman:

{% for key, item in row.divs %}
    {% if (key not in [1,2,9]) %} // eliminate element 1,2,9
        <li>{{ item }}</li>
    {% endif %}
{% endfor %}

How can I change the default Django date template format?

In order to change date format in the views.py and then assign it to template.

# get the object details 
home = Home.objects.get(home_id=homeid)

# get the start date
_startDate = home.home_startdate.strftime('%m/%d/%Y')

# assign it to template 
return render_to_response('showme.html' 
                                        {'home_startdate':_startDate},   
                                         context_instance=RequestContext(request) )  

Is optimisation level -O3 dangerous in g++?

In my somewhat checkered experience, applying -O3 to an entire program almost always makes it slower (relative to -O2), because it turns on aggressive loop unrolling and inlining that make the program no longer fit in the instruction cache. For larger programs, this can also be true for -O2 relative to -Os!

The intended use pattern for -O3 is, after profiling your program, you manually apply it to a small handful of files containing critical inner loops that actually benefit from these aggressive space-for-speed tradeoffs. Newer versions of GCC have a profile-guided optimization mode that can (IIUC) selectively apply the -O3 optimizations to hot functions -- effectively automating this process.

Animate an element's width from 0 to 100%, with it and it's wrapper being only as wide as they need to be, without a pre-set width, in CSS3 or jQuery

I think I've got it.

_x000D_
_x000D_
.wrapper {_x000D_
    background:#DDD;_x000D_
    display:inline-block;_x000D_
    padding: 10px;_x000D_
    height: 20px;_x000D_
    width:auto;_x000D_
}_x000D_
_x000D_
.label {_x000D_
    display: inline-block;_x000D_
    width: 1em;_x000D_
}_x000D_
_x000D_
.contents, .contents .inner {_x000D_
    display:inline-block;_x000D_
}_x000D_
_x000D_
.contents {_x000D_
    white-space:nowrap;_x000D_
    margin-left: -1em;_x000D_
    padding-left: 1em;_x000D_
}_x000D_
_x000D_
.contents .inner {_x000D_
    background:#c3c;_x000D_
    width:0%;_x000D_
    overflow:hidden;_x000D_
    -webkit-transition: width 1s ease-in-out;_x000D_
    -moz-transition: width 1s ease-in-out;_x000D_
    -o-transition: width 1s ease-in-out;_x000D_
    transition: width 1s ease-in-out;_x000D_
}_x000D_
_x000D_
_x000D_
_x000D_
.wrapper:hover .contents .inner {_x000D_
   _x000D_
    width:100%;_x000D_
}
_x000D_
<div class="wrapper">_x000D_
    <span class="label">+</span><div class="contents">_x000D_
        <div class="inner">_x000D_
            These are the contents of this div_x000D_
        </div>_x000D_
    </div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

Animating to 100% causes it to wrap because the box is bigger than the available width (100% minus the + and the whitespace following it).

Instead, you can animate an inner element, whose 100% is the total width of .contents.

Remove multiple objects with rm()

An other solution rm(list=ls(pattern="temp")), remove all objects matching the pattern.

Clearing UIWebview cache

Don't disable caching completely, it'll hurt your app performance and it's unnecessary. The important thing is to explicitly configure the cache at app startup and purge it when necessary.

So in application:DidFinishLaunchingWithOptions: configure the cache limits as follows:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{   
    int cacheSizeMemory = 4*1024*1024; // 4MB
    int cacheSizeDisk = 32*1024*1024; // 32MB
    NSURLCache *sharedCache = [[NSURLCache alloc] initWithMemoryCapacity:cacheSizeMemory diskCapacity:cacheSizeDisk diskPath:@"nsurlcache"];
    [NSURLCache setSharedURLCache:sharedCache];

    // ... other launching code
}

Once you have it properly configured, then when you need to purge the cache (for example in applicationDidReceiveMemoryWarning or when you close a UIWebView) just do:

[[NSURLCache sharedURLCache] removeAllCachedResponses];

and you'll see the memory is recovered. I blogged about this issue here: http://twobitlabs.com/2012/01/ios-ipad-iphone-nsurlcache-uiwebview-memory-utilization/

How do I determine the current operating system with Node.js

Process

var opsys = process.platform;
if (opsys == "darwin") {
    opsys = "MacOS";
} else if (opsys == "win32" || opsys == "win64") {
    opsys = "Windows";
} else if (opsys == "linux") {
    opsys = "Linux";
}
console.log(opsys) // I don't know what linux is.

OS

const os = require("os"); // Comes with node.js
console.log(os.type());

Convert a CERT/PEM certificate to a PFX certificate

If you have a self-signed certificate generated by makecert.exe on a Windows machine, you will get two files: cert.pvk and cert.cer. These can be converted to a pfx using pvk2pfx

pvk2pfx is found in the same location as makecert (e.g. C:\Program Files (x86)\Windows Kits\10\bin\x86 or similar)

pvk2pfx -pvk cert.pvk -spc cert.cer -pfx cert.pfx

XMLHttpRequest blocked by CORS Policy

I believe sideshowbarker 's answer here has all the info you need to fix this. If your problem is just No 'Access-Control-Allow-Origin' header is present on the response you're getting, you can set up a CORS proxy to get around this. Way more info on it in the linked answer

Sorting object property by values

a = { b: 1, p: 8, c: 2, g: 1 }
Object.keys(a)
  .sort((c,b) => {
    return a[b]-a[c]
  })
  .reduce((acc, cur) => {
    let o = {}
    o[cur] = a[cur]
    acc.push(o)
    return acc
   } , [])

output = [ { p: 8 }, { c: 2 }, { b: 1 }, { g: 1 } ]

How do I call Objective-C code from Swift?

Just a note for whoever is trying to add an Objective-C library to Swift: You should add -ObjC in Build Settings -> Linking -> Other Linker Flags.

cmake and libpthread

target_compile_options solution above is wrong, it won't link the library.

Use:

SET(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -pthread")

OR

target_link_libraries(XXX PUBLIC pthread)

OR

set_target_properties(XXX PROPERTIES LINK_LIBRARIES -pthread)

PHP Try and Catch for SQL Insert

You can implement throwing exceptions on mysql query fail on your own. What you need is to write a wrapper for mysql_query function, e.g.:

// user defined. corresponding MySQL errno for duplicate key entry
const MYSQL_DUPLICATE_KEY_ENTRY = 1022;

// user defined MySQL exceptions
class MySQLException extends Exception {}
class MySQLDuplicateKeyException extends MySQLException {}

function my_mysql_query($query, $conn=false) {
    $res = mysql_query($query, $conn);
    if (!$res) {
        $errno = mysql_errno($conn);
        $error = mysql_error($conn);
        switch ($errno) {
        case MYSQL_DUPLICATE_KEY_ENTRY:
            throw new MySQLDuplicateKeyException($error, $errno);
            break;
        default:
            throw MySQLException($error, $errno);
            break;
        }
    }
    // ...
    // doing something
    // ...
    if ($something_is_wrong) {
        throw new Exception("Logic exception while performing query result processing");
    }

}

try {
    mysql_query("INSERT INTO redirects SET ua_string = '$ua_string'")
}
catch (MySQLDuplicateKeyException $e) {
    // duplicate entry exception
    $e->getMessage();
}
catch (MySQLException $e) {
    // other mysql exception (not duplicate key entry)
    $e->getMessage();
}
catch (Exception $e) {
    // not a MySQL exception
    $e->getMessage();
}

How to stop a PowerShell script on the first error?

I'm new to powershell but this seems to be most effective:

doSomething -arg myArg
if (-not $?) {throw "Failed to doSomething"}

How do I get the name of the current executable in C#?

  • System.Reflection.Assembly.GetEntryAssembly().Location returns location of exe name if assembly is not loaded from memory.
  • System.Reflection.Assembly.GetEntryAssembly().CodeBase returns location as URL.

python pip - install from local dir

All you need to do is run

pip install /opt/mypackage

and pip will search /opt/mypackage for a setup.py, build a wheel, then install it.

The problem with using the -e flag for pip install as suggested in the comments and this answer is that this requires that the original source directory stay in place for as long as you want to use the module. It's great if you're a developer working on the source, but if you're just trying to install a package, it's the wrong choice.

Alternatively, you don't even need to download the repo from Github at all. pip supports installing directly from git repos using a variety of protocols including HTTP, HTTPS, and SSH, among others. See the docs I linked to for examples.

ASP.Net MVC Redirect To A Different View

Here's what you can do:

return View("another view name", anotherviewmodel);

How do I convert a String to an int in Java?

Currently I'm doing an assignment for college, where I can't use certain expressions, such as the ones above, and by looking at the ASCII table, I managed to do it. It's a far more complex code, but it could help others that are restricted like I was.

The first thing to do is to receive the input, in this case, a string of digits; I'll call it String number, and in this case, I'll exemplify it using the number 12, therefore String number = "12";

Another limitation was the fact that I couldn't use repetitive cycles, therefore, a for cycle (which would have been perfect) can't be used either. This limits us a bit, but then again, that's the goal. Since I only needed two digits (taking the last two digits), a simple charAtsolved it:

 // Obtaining the integer values of the char 1 and 2 in ASCII
 int semilastdigitASCII = number.charAt(number.length() - 2);
 int lastdigitASCII = number.charAt(number.length() - 1);

Having the codes, we just need to look up at the table, and make the necessary adjustments:

 double semilastdigit = semilastdigitASCII - 48;  // A quick look, and -48 is the key
 double lastdigit = lastdigitASCII - 48;

Now, why double? Well, because of a really "weird" step. Currently we have two doubles, 1 and 2, but we need to turn it into 12, there isn't any mathematic operation that we can do.

We're dividing the latter (lastdigit) by 10 in the fashion 2/10 = 0.2 (hence why double) like this:

 lastdigit = lastdigit / 10;

This is merely playing with numbers. We were turning the last digit into a decimal. But now, look at what happens:

 double jointdigits = semilastdigit + lastdigit; // 1.0 + 0.2 = 1.2

Without getting too into the math, we're simply isolating units the digits of a number. You see, since we only consider 0-9, dividing by a multiple of 10 is like creating a "box" where you store it (think back at when your first grade teacher explained you what a unit and a hundred were). So:

 int finalnumber = (int) (jointdigits*10); // Be sure to use parentheses "()"

And there you go. You turned a String of digits (in this case, two digits), into an integer composed of those two digits, considering the following limitations:

  • No repetitive cycles
  • No "Magic" Expressions such as parseInt

Why do I get a C malloc assertion failure?

I got the following message, similar to your one:


    program: malloc.c:2372: sysmalloc: Assertion `(old_top == (((mbinptr) (((char *) &((av)->bins[((1) - 1) * 2])) - __builtin_offsetof (struct malloc_chunk, fd)))) && old_size == 0) || ((unsigned long) (old_size) >= (unsigned long)((((__builtin_offsetof (struct malloc_chunk, fd_nextsize))+((2 *(sizeof(size_t))) - 1)) & ~((2 *(sizeof(size_t))) - 1))) && ((old_top)->size & 0x1) && ((unsigned long) old_end & pagemask) == 0)' failed.

Made a mistake some method call before, when using malloc. Erroneously overwrote the multiplication sign '*' with a '+', when updating the factor after sizeof()-operator on adding a field to unsigned char array.

Here is the code responsible for the error in my case:


    UCHAR* b=(UCHAR*)malloc(sizeof(UCHAR)+5);
    b[INTBITS]=(some calculation);
    b[BUFSPC]=(some calculation);
    b[BUFOVR]=(some calculation);
    b[BUFMEM]=(some calculation);
    b[MATCHBITS]=(some calculation);

In another method later, I used malloc again and it produced the error message shown above. The call was (simple enough):


    UCHAR* b=(UCHAR*)malloc(sizeof(UCHAR)*50);

Think using the '+'-sign on the 1st call, which lead to mis-calculus in combination with immediate initialization of the array after (overwriting memory that was not allocated to the array), brought some confusion to malloc's memory map. Therefore the 2nd call went wrong.

Best way to check if a drop down list contains a value?

Sometimes the value needs to be trimmed of whitespace or it won't be matched, in such case this additional step can be used (source):

if(((DropDownList) myControl1).Items.Cast<ListItem>().Select(i => i.Value.Trim() == ctrl.value.Trim()).FirstOrDefault() != null){}

How to hide a column (GridView) but still access its value?

You can do it programmatically:

grid0.Columns[0].Visible = true;
grid0.DataSource = dt;
grid0.DataBind();
grid0.Columns[0].Visible = false;

In this way you set the column to visible before databinding, so the column is generated. The you set the column to not visible, so it is not displayed.

How to check whether a string is a valid HTTP URL?

Uri uri = null;
if (!Uri.TryCreate(url, UriKind.Absolute, out uri) || null == uri)
    return false;
else
    return true;

Here url is the string you have to test.

Iterating through a List Object in JSP

you can read empList directly in forEach tag.Try this

 <table>
       <c:forEach items="${sessionScope.empList}" var="employee">
            <tr>
                <td>Employee ID: <c:out value="${employee.eid}"/></td>
                <td>Employee Pass: <c:out value="${employee.ename}"/></td>  
            </tr>
        </c:forEach>
    </table>

Split long commands in multiple lines through Windows batch file

It seems however that splitting in the middle of the values of a for loop doesn't need a caret(and actually trying to use one will be considered a syntax error). For example,

for %n in (hello
bye) do echo %n

Note that no space is even needed after hello or before bye.

Why there is no ConcurrentHashSet against ConcurrentHashMap

As pointed by this the best way to obtain a concurrency-able HashSet is by means of Collections.synchronizedSet()

Set s = Collections.synchronizedSet(new HashSet(...));

This worked for me and I haven't seen anybody really pointing to it.

EDIT This is less efficient than the currently aproved solution, as Eugene points out, since it just wraps your set into a synchronized decorator, while a ConcurrentHashMap actually implements low-level concurrency and it can back your Set just as fine. So thanks to Mr. Stepanenkov for making that clear.

http://docs.oracle.com/javase/8/docs/api/java/util/Collections.html#synchronizedSet-java.util.Set-

Convert JS date time to MySQL datetime

Using toJSON() date function as below:

_x000D_
_x000D_
var sqlDatetime = new Date(new Date().getTime() - new Date().getTimezoneOffset() * 60 * 1000).toJSON().slice(0, 19).replace('T', ' ');
console.log(sqlDatetime);
_x000D_
_x000D_
_x000D_

How can git be installed on CENTOS 5.5?

Just installed git using the following instructions:

  1. Install EPEL V5
    #rpm -Uvh http://archives.fedoraproject.org/pub/archive/epel/5/x86_64/epel-release-5-4.noarch.rpm

  2. Install Git
    # yum install git git-daemon

  3. Check
    # git --version
    git version 1.8.2.3

  4. Optionally install Git GUI
    # yum install git-gui

For i386 substitute x86_64 by i386 in the URL at step #1.

#rpm -Uvh http://archives.fedoraproject.org/pub/archive/epel/5/i386/epel-release-5-4.noarch.rpm

What is the right way to check for a null string in Objective-C?

if(textfield.text.length == 0){
   //do your desired work
}

symfony 2 twig limit the length of the text and put three dots

It is better to use an HTML character

{{ entity.text[:50] }}&#8230;

How to connect to Oracle 11g database remotely

First, make sure the listener on database server (computer A) that receives client connection requests is running. To do so, run lsnrctl status command.

In case, if you get TNS:no listener message (see below image), it means listener service is not running. To start it, run lsnrctl start command.

enter image description here

Second, for database operations and connectivity from remote clients, the following executables must be added to the Windows Firewall exception list: (see image)

Oracle_home\bin\oracle.exe - Oracle Database executable

Oracle_home\bin\tnslsnr.exe - Oracle Listener

enter image description here

Finally, install oracle instant client on client machine (computer B) and run:

sqlplus user/password@computerA:port/XE

Purge Kafka Topic

Temporarily update the retention time on the topic to one second:

kafka-topics.sh --zookeeper <zkhost>:2181 --alter --topic <topic name> --config retention.ms=1000

And in newer Kafka releases, you can also do it with kafka-configs --entity-type topics

kafka-configs.sh --zookeeper <zkhost>:2181 --entity-type topics --alter --entity-name <topic name> --add-config retention.ms=1000

then wait for the purge to take effect (about one minute). Once purged, restore the previous retention.ms value.

What is the yield keyword used for in C#?

Recently Raymond Chen also ran an interesting series of articles on the yield keyword.

While it's nominally used for easily implementing an iterator pattern, but can be generalized into a state machine. No point in quoting Raymond, the last part also links to other uses (but the example in Entin's blog is esp good, showing how to write async safe code).

log4j:WARN No appenders could be found for logger (running jar file, not web app)

I had moved my log4j.properties into the resources folder and it worked fine for me !

On duplicate key ignore?

Mysql has this handy UPDATE INTO command ;)

edit Looks like they renamed it to REPLACE

REPLACE works exactly like INSERT, except that if an old row in the table has the same value as a new row for a PRIMARY KEY or a UNIQUE index, the old row is deleted before the new row is inserted

Compare one String with multiple values in one expression

Starting from Java 9, you can use either of following

List.of("val1", "val2", "val3").contains(str.toLowerCase())

Set.of("val1", "val2", "val3").contains(str.toLowerCase());

Java Hashmap: How to get key from value?

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

public class M{
public static void main(String[] args) {

        HashMap<String, List<String>> resultHashMap = new HashMap<String, List<String>>();

        Set<String> newKeyList = resultHashMap.keySet();


        for (Iterator<String> iterator = originalHashMap.keySet().iterator(); iterator.hasNext();) {
            String hashKey = (String) iterator.next();

            if (!newKeyList.contains(originalHashMap.get(hashKey))) {
                List<String> loArrayList = new ArrayList<String>();
                loArrayList.add(hashKey);
                resultHashMap.put(originalHashMap.get(hashKey), loArrayList);
            } else {
                List<String> loArrayList = resultHashMap.get(originalHashMap
                        .get(hashKey));
                loArrayList.add(hashKey);
                resultHashMap.put(originalHashMap.get(hashKey), loArrayList);
            }
        }

        System.out.println("Original HashMap : " + originalHashMap);
        System.out.println("Result HashMap : " + resultHashMap);
    }
}

Adding/removing items from a JavaScript object with jQuery

Adding an object in a json array

var arrList = [];
var arr = {};   
arr['worker_id'] = worker_id;
arr['worker_nm'] = worker_nm;
arrList.push(arr);

Removing an object from a json

It worker for me.

  arrList = $.grep(arrList, function (e) { 

        if(e.worker_id == worker_id) {
            return false;
        } else {
            return true;
        }
    });

It returns an array without that object.

Hope it helps.

How to run .sh on Windows Command Prompt?

The most common way to run a .sh file is using the sh command:

C:\>sh my-script-test.sh 

other good option is installing CygWin

in Windows the home is located in:

C:\cygwin64\home\[user]

for example i execute my my-script-test.sh file using the bash command as:

jorgesys@INT024P ~$ bash /home/[user]/my-script-test.sh 

Replacing NULL and empty string within Select statement

An alternative way can be this: - recommended as using just one expression -

case when address.country <> '' then address.country
else 'United States'
end as country

Note: Result of checking null by <> operator will return false.
And as documented: NULLIF is equivalent to a searched CASE expression
and COALESCE expression is a syntactic shortcut for the CASE expression.
So, combination of those are using two time of case expression.

LINQ Where with AND OR condition

Well, you're going to have to check for null somewhere. You could do something like this:

from item in db.vw_Dropship_OrderItems
         where (listStatus == null || listStatus.Contains(item.StatusCode)) 
            && (listMerchants == null || listMerchants.Contains(item.MerchantId))
         select item;

Android Studio : How to uninstall APK (or execute adb command) automatically before Run or Debug?

This command with --user 0 do the job:

adb uninstall --user 0 <package_name>

Custom li list-style with font-awesome icon

Now that the ::marker element is available in evergreen browsers, this is how you could use it, including using :hover to change the marker. As you can see, now you can use any Unicode character you want as a list item marker and even use custom counters.

_x000D_
_x000D_
@charset "UTF-8";
@counter-style fancy {
  system: fixed;
  symbols:   ;
  suffix: " ";
}

p {
  margin-left: 8em;
}

p.note {
  display: list-item;
  counter-increment: note-counter;
}

p.note::marker {
  content: "Note " counter(note-counter) ":";
}

ol {
  margin-left: 8em;
  padding-left: 0;
}

ol li {
  list-style-type: lower-roman;
}

ol li::marker {
  color: blue;
  font-weight: bold;
}

ul {
  margin-left: 8em;
  padding-left: 0;
}

ul.happy li::marker {
  content: "";
}

ul.happy li:hover {
  color: blue;
}

ul.happy li:hover::marker {
  content: "";
}

ul.fancy {
  list-style: fancy;
}
_x000D_
<p>This is the first paragraph in this document.</p>
<p class="note">This is a very short document.</p>
<ol>
  <li>This is the first item.
    <li>This is the second item.
      <li>This is the third item.
</ol>
<p>This is the end.</p>

<ul class="happy">
  <li>Item 1</li>
  <li>Item 2</li>
  <li>Item 3</li>
</ul>

<ul class="fancy">
  <li>Item 1</li>
  <li>Item 2</li>
  <li>Item 3</li>
</ul>
_x000D_
_x000D_
_x000D_

How to update each dependency in package.json to the latest version?

I solved this by seeing the instructions from https://github.com/tjunnone/npm-check-updates

$ npm install -g npm-check-updates
$ ncu
$ ncu -u # to update all the dependencies to latest
$ ncu -u "specific module name"  #in case you want to update specific dependencies to latest

how to set the query timeout from SQL connection string

Only from code:

_x000D_
_x000D_
namespace xxx.DsXxxTableAdapters {_x000D_
    partial class ZzzTableAdapter_x000D_
    {_x000D_
        public void SetTimeout(int timeout)_x000D_
        {_x000D_
            if (this.Adapter.DeleteCommand != null) { this.Adapter.DeleteCommand.CommandTimeout = timeout; }_x000D_
            if (this.Adapter.InsertCommand != null) { this.Adapter.InsertCommand.CommandTimeout = timeout; }_x000D_
            if (this.Adapter.UpdateCommand != null) { this.Adapter.UpdateCommand.CommandTimeout = timeout; }_x000D_
            if (this._commandCollection == null) { this.InitCommandCollection(); }_x000D_
            if (this._commandCollection != null)_x000D_
            {_x000D_
                foreach (System.Data.SqlClient.SqlCommand item in this._commandCollection)_x000D_
                {_x000D_
                    if (item != null)_x000D_
                    { item.CommandTimeout = timeout; }_x000D_
                }_x000D_
            }_x000D_
        }_x000D_
    }_x000D_
 _x000D_
    //...._x000D_
 _x000D_
 }
_x000D_
_x000D_
_x000D_

Run an Ansible task only when the variable contains a specific string

This example uses regex_search to perform a substring search.

- name: make conditional variable
  command: "file -s /dev/xvdf"
  register: fsm_out

- name: makefs
  command: touch "/tmp/condition_satisfied"
  when: fsm_out.stdout | regex_search(' data')

ansible version: 2.4.3.0

Read file content from S3 bucket with boto3

When you want to read a file with a different configuration than the default one, feel free to use either mpu.aws.s3_read(s3path) directly or the copy-pasted code:

def s3_read(source, profile_name=None):
    """
    Read a file from an S3 source.

    Parameters
    ----------
    source : str
        Path starting with s3://, e.g. 's3://bucket-name/key/foo.bar'
    profile_name : str, optional
        AWS profile

    Returns
    -------
    content : bytes

    botocore.exceptions.NoCredentialsError
        Botocore is not able to find your credentials. Either specify
        profile_name or add the environment variables AWS_ACCESS_KEY_ID,
        AWS_SECRET_ACCESS_KEY and AWS_SESSION_TOKEN.
        See https://boto3.readthedocs.io/en/latest/guide/configuration.html
    """
    session = boto3.Session(profile_name=profile_name)
    s3 = session.client('s3')
    bucket_name, key = mpu.aws._s3_path_split(source)
    s3_object = s3.get_object(Bucket=bucket_name, Key=key)
    body = s3_object['Body']
    return body.read()

How do I discover memory usage of my application in Android?

Hackbod's is one of the best answers on Stack Overflow. It throws light on a very obscure subject. It helped me a lot.

Another really helpful resource is this must-see video: Google I/O 2011: Memory management for Android Apps


UPDATE:

Process Stats, a service to discover how your app manages memory explained at the blog post Process Stats: Understanding How Your App Uses RAM by Dianne Hackborn:

Set background color in PHP?

I would recommend to use css, but php to use to set some class or id for the element, in order to make it generated dynamically.

Can Twitter Bootstrap alerts fade in as well as out?

I got this way to close fading my Alert after 3 seconds. Hope it will be useful.

    setTimeout(function(){
    $('.alert').fadeTo("slow", 0.1, function(){
        $('.alert').alert('close')
    });     
    }, 3000)

Can PHP cURL retrieve response headers AND body in a single request?

is this what are you looking to?

curl_setopt($ch, CURLOPT_HTTPHEADER, array('Expect:'));
$response = curl_exec($ch); 
list($header, $body) = explode("\r\n\r\n", $response, 2);

Angular - ui-router get previous state

I use resolve to save the current state data before moving to the new state:

angular.module('MyModule')
.config(['$stateProvider', function ($stateProvider) {
    $stateProvider
        .state('mystate', {
            templateUrl: 'mytemplate.html',
            controller: ["PreviousState", function (PreviousState) {
                if (PreviousState.Name == "mystate") {
                    // ...
                }
            }],
            resolve: {
                PreviousState: ["$state", function ($state) {
                    var currentStateData = {
                        Name: $state.current.name,
                        Params: $state.params,
                        URL: $state.href($state.current.name, $state.params)
                    };
                    return currentStateData;
                }]
            }
        });
}]);

How to implement a Navbar Dropdown Hover in Bootstrap v4?

Just Add this simple css code in your style-sheet and you are ready to go.

.dropdown:hover > .dropdown-menu {
    display: block;
}
.dropdown > .dropdown-toggle:active {
    /*Without this, clicking will make it sticky*/
    pointer-events: none;
}

Java IOException "Too many open files"

Recently, I had a program batch processing files, I have certainly closed each file in the loop, but the error still there.

And later, I resolved this problem by garbage collect eagerly every hundreds of files:

int index;
while () {
    try {
        // do with outputStream...
    } finally {
        out.close();
    }
    if (index++ % 100 = 0)
        System.gc();
}

How to specify non-default shared-library path in GCC Linux? Getting "error while loading shared libraries" when running

Should it be LIBRARY_PATH instead of LD_LIBRARY_PATH. gcc checks for LIBRARY_PATH which can be seen with -v option

ERROR 403 in loading resources like CSS and JS in my index.php

Find out the web server user

open up terminal and type lsof -i tcp:80

This will show you the user of the web server process Here is an example from a raspberry pi running debian:

COMMAND   PID     USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
apache2  7478 www-data    3u  IPv4 450666      0t0  TCP *:http (LISTEN)
apache2  7664 www-data    3u  IPv4 450666      0t0  TCP *:http (LISTEN)
apache2  7794 www-data    3u  IPv4 450666      0t0  TCP *:http (LISTEN)

The user is www-data

If you give ownership of the web files to the web server:

chown www-data:www-data -R /opt/lamp/htdocs

And chmod 755 for good measure:

chmod 755 -R /opt/lamp/htdocs

Let me know how you go, maybe you need to use 'sudo' before the command, i.e. sudo chown www-data:www-data -R /opt/lamp/htdocs

if it doesn't work, please give us the output of: ls -al /opt/lamp/htdocs

SQL set values of one column equal to values of another column in the same table

Here is sample code that might help you coping Column A to Column B:

UPDATE YourTable
SET ColumnB = ColumnA
WHERE
ColumnB IS NULL
AND ColumnA IS NOT NULL;

How to normalize a vector in MATLAB efficiently? Any related built-in function?

The only problem you would run into is if the norm of V is zero (or very close to it). This could give you Inf or NaN when you divide, along with a divide-by-zero warning. If you don't care about getting an Inf or NaN, you can just turn the warning on and off using WARNING:

oldState = warning('off','MATLAB:divideByZero');  % Return previous state then
                                                  %   turn off DBZ warning
uV = V/norm(V);
warning(oldState);  % Restore previous state

If you don't want any Inf or NaN values, you have to check the size of the norm first:

normV = norm(V);
if normV > 0,  % Or some other threshold, like EPS
  uV = V/normV;
else,
  uV = V;  % Do nothing since it's basically 0
end

If I need it in a program, I usually put the above code in my own function, usually called unit (since it basically turns a vector into a unit vector pointing in the same direction).

SQL Server: Importing database from .mdf?

Apart from steps mentioned in posted answers by @daniele3004 above, I had to open SSMS as Administrator otherwise it was showing Primary file is read only error.

Go to Start Menu , navigate to SSMS link , right click on the SSMS link , select Run As Administrator. Then perform the above steps.

Database Diagram Support Objects cannot be Installed ... no valid owner

1.Right click on your Database , 2.Then select properties . 3.Select the option in compatibility levels choose sql 2008[100] if you are working with Microsoft sql 2008.

4.Then select the file and write ( sa ) in owner`s textbox

100% works for me.

Linux: command to open URL in default browser

I think a combination of xdg-open as described by shellholic and - if it fails - the solution to finding a browser using the which command as described here is probably the best solution.

Copy struct to struct in C

For simple structures you can either use memcpy like you do, or just assign from one to the other:

RTCclk = RTCclkBuffert;

The compiler will create code to copy the structure for you.


An important note about the copying: It's a shallow copy, just like with memcpy. That means if you have e.g. a structure containing pointers, it's only the actual pointers that will be copied and not what they point to, so after the copy you will have two pointers pointing to the same memory.

How can I generate random alphanumeric strings?

If your values are not completely random, but in fact may depend on something - you may compute an md5 or sha1 hash of that 'somwthing' and then truncate it to whatever length you want.

Also you may generate and truncate a guid.

Converting a value to 2 decimal places within jQuery

You need to use the .toFixed() method

It takes as a parameter the number of digits to show after the decimal point.

$(document).ready(function() {
  $('.add').click(function() {
     var value = parseFloat($('#total').text()) + parseFloat($(this).data('amount'))/100
     $('#total').text( value.toFixed(2) );
  });
})

Subquery returned more than 1 value.This is not permitted when the subquery follows =,!=,<,<=,>,>= or when the subquery is used as an expression

Use In instead of =

 select * from dbo.books
 where isbn in (select isbn from dbo.lending 
                where act between @fdate and @tdate
                and stat ='close'
               )

or you can use Exists

SELECT t1.*,t2.*
FROM  books   t1 
WHERE  EXISTS ( SELECT * FROM dbo.lending t2 WHERE t1.isbn = t2.isbn and
                t2.act between @fdate and @tdate and t2.stat ='close' )

Convert Json String to C# Object List

Try to change type of ScoreIfNoMatch, like this:

   public class MatrixModel
        {
            public string S1 { get; set; }
            public string S2 { get; set; }
            public string S3 { get; set; }
            public string S4 { get; set; }
            public string S5 { get; set; }
            public string S6 { get; set; }
            public string S7 { get; set; }
            public string S8 { get; set; }
            public string S9 { get; set; }
            public string S10 { get; set; }
            // the type should be string
            public string ScoreIfNoMatch { get; set; }
        }

Calculating Waiting Time and Turnaround Time in (non-preemptive) FCFS queue

For non-preemptive system,

waitingTime = startTime - arrivalTime

turnaroundTime = burstTime + waitingTime = finishTime- arrivalTime

startTime = Time at which the process started executing

finishTime = Time at which the process finished executing

You can keep track of the current time elapsed in the system(timeElapsed). Assign all processors to a process in the beginning, and execute until the shortest process is done executing. Then assign this processor which is free to the next process in the queue. Do this until the queue is empty and all processes are done executing. Also, whenever a process starts executing, recored its startTime, when finishes, record its finishTime (both same as timeElapsed). That way you can calculate what you need.

What does <meta http-equiv="X-UA-Compatible" content="IE=edge"> do?

This is LITERALLY 1 google query away, but here goes:

http://msdn.microsoft.com/en-us/library/jj676915(v=vs.85).aspx

Understanding legacy document modes

Use the following value to display the webpage in edge mode, which is the highest standards mode supported by Internet Explorer, from Internet Explorer 6 through IE11.

<meta http-equiv="x-ua-compatible" content="IE=edge"

Note that this is functionally equivalent to using the HTML5 doctype. It places Internet Explorer into the highest supported document mode. Edge most is most useful for regularly maintained websites that are routinely tested for interoperability between multiple browsers, including Internet Explorer.

Note Starting with IE11, edge mode is considered the preferred document mode. (In earlier versions, it was considered experimental.) To learn more, see Document modes are deprecated. Starting with Windows Internet Explorer 8, some web developers used the edge mode meta element to hide the Compatibility View button on the address bar. As of IE11, this is no longer necessary as the button has been removed from the address bar. Because it forces all pages to be opened in standards mode, regardless of the version of Internet Explorer, you might be tempted to use edge mode for all pages viewed with Internet Explorer. Don't do this, as the X-UA-Compatible header is only supported starting with Internet Explorer 8.

Tip If you want all supported versions of Internet Explorer to open your pages in standards mode, use the HTML5 document type declaration, as shown in the earlier example.

Also among the search results is:

Remove border radius from Select tag in bootstrap 3

Using the SVG from @ArnoTenkink as an data url combined with the accepted answer, this gives us the perfect solution for retina displays.

select.form-control:not([multiple]) {
    border-radius: 0;
    appearance: none;
    background-position: right 50%;
    background-repeat: no-repeat;
    background-image: url(data:image/svg+xml,%3C%3Fxml%20version%3D%221.0%22%20encoding%3D%22utf-8%22%3F%3E%20%3C%21DOCTYPE%20svg%20PUBLIC%20%22-//W3C//DTD%20SVG%201.1//EN%22%20%22http%3A//www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd%22%3E%20%3Csvg%20version%3D%221.1%22%20id%3D%22Layer_1%22%20xmlns%3D%22http%3A//www.w3.org/2000/svg%22%20xmlns%3Axlink%3D%22http%3A//www.w3.org/1999/xlink%22%20x%3D%220px%22%20y%3D%220px%22%20width%3D%2214px%22%20height%3D%2212px%22%20viewBox%3D%220%200%2014%2012%22%20enable-background%3D%22new%200%200%2014%2012%22%20xml%3Aspace%3D%22preserve%22%3E%20%3Cpolygon%20points%3D%223.862%2C7.931%200%2C4.069%207.725%2C4.069%20%22/%3E%3C/svg%3E);
    padding: .5em;
    padding-right: 1.5em
}

how to get request path with express req object

req.route.path is working for me

var pool = require('../db');

module.exports.get_plants = function(req, res) {
    // to run a query we can acquire a client from the pool,
    // run a query on the client, and then return the client to the pool
    pool.connect(function(err, client, done) {
        if (err) {
            return console.error('error fetching client from pool', err);
        }
        client.query('SELECT * FROM plants', function(err, result) {
            //call `done()` to release the client back to the pool
            done();
            if (err) {
                return console.error('error running query', err);
            }
            console.log('A call to route: %s', req.route.path + '\nRequest type: ' + req.method.toLowerCase());
            res.json(result);
        });
    });
};

after executing I see the following in the console and I get perfect result in my browser.

Express server listening on port 3000 in development mode
A call to route: /plants
Request type: get

How to empty a redis database?

You have two options:

  • FLUSHDB - clears currently active database
  • FLUSHALL - clears all the existing databases

Error You must specify a region when running command aws ecs list-container-instances

#1- Run this to configure the region once and for all:

aws configure set region us-east-1 --profile admin
  • Change admin next to the profile if it's different.

  • Change us-east-1 if your region is different.

#2- Run your command again:

aws ecs list-container-instances --cluster default

Change span text?

document.getElementById("serverTime").innerHTML = ...;

How to create string with multiple spaces in JavaScript

Use &nbsp;

It is the entity used to represent a non-breaking space. It is essentially a standard space, the primary difference being that a browser should not break (or wrap) a line of text at the point that this   occupies.

var a = 'something' + '&nbsp &nbsp &nbsp &nbsp &nbsp' + 'something'

Non-breaking Space

A common character entity used in HTML is the non-breaking space (&nbsp;).

Remember that browsers will always truncate spaces in HTML pages. If you write 10 spaces in your text, the browser will remove 9 of them. To add real spaces to your text, you can use the &nbsp; character entity.

http://www.w3schools.com/html/html_entities.asp

Demo

_x000D_
_x000D_
var a = 'something' + '&nbsp &nbsp &nbsp &nbsp &nbsp' + 'something';_x000D_
_x000D_
document.body.innerHTML = a;
_x000D_
_x000D_
_x000D_