# Programs & Examples On #Heading

### Calculate compass bearing / heading to location in Android

If you are on the same timezone

Convert GPS to UTM

http://www.ibm.com/developerworks/java/library/j-coordconvert/ http://stackoverflow.com/questions/176137/java-convert-lat-lon-to-utm

UTM coordinates get you a simples X Y 2D

Calculate the angle between both UTM locations

http://forums.groundspeak.com/GC/index.php?showtopic=146917

This gives the direction as if you were looking north

So whatever you rotate related do North just subtract this angle

If both point have a UTM 45º degree angle and you are 5º east of north, your arrow will point to 40º of north

### How to export table as CSV with headings on Postgresql?

For version 9.5 I use, it would be like this:

``````COPY products_273 TO '/tmp/products_199.csv' WITH (FORMAT CSV, HEADER);
``````

### ImageView in android XML layout with layout_height="wrap_content" has padding top & bottom

I had a simular issue and resolved it using `android:adjustViewBounds="true"` on the ImageView.

``````<ImageView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:contentDescription="@string/banner_alt"
android:src="@drawable/banner_portrait" />
``````

### Keyboard shortcut for Jump to Previous View Location (Navigate back/forward) in IntelliJ IDEA

The underlying problem is Ctrl+Alt+Left and Right are used by window managers to switch workspace and/or OEM utilities to change the screen orientation.

You can change the assignments using `File / Settings / Keymap` then `Main Menu / Navigate` find `Back` and `Forward` and right click to `Add Keyboard Shortcut` to set an alternative key chord.

Alt Graph+Left and Alt Graph+Right works well for me (IDEA 13.1.4 on Ubuntu under IceWM).

### Change Date Format(DD/MM/YYYY) in SQL SELECT Statement

You will want to use a CONVERT() statement.

Try the following;

``````SELECT CONVERT(VARCHAR(10), SA.[RequestStartDate], 103) as 'Service Start Date', CONVERT(VARCHAR(10), SA.[RequestEndDate], 103) as 'Service End Date', FROM (......) SA WHERE.....
``````

### What is the difference between “int” and “uint” / “long” and “ulong”?

`u` means `unsigned`, so `ulong` is a large number without sign. You can store a bigger value in `ulong` than `long`, but no negative numbers allowed.

A `long` value is stored in 64-bit,with its first digit to show if it's a positive/negative number. while `ulong` is also 64-bit, with all 64 bit to store the number. so the maximum of ulong is 2(64)-1, while long is 2(63)-1.

### Eclipse error: "The import XXX cannot be resolved"

If you're developing plugins in eclipse and you're using a target platform (which was my case) you need to make sure you check the target's platform configuration from Window->Preferences->Plug-in Development->Target Platform and make sure your target platform is checked and configured. Hope this helps.

### How to install SQL Server Management Studio 2012 (SSMS) Express?

You need to install ENU\x64\SQLEXPRWT_x64_ENU.exe which is Express with Tools (RTM release. SP1 release can be found here).

As the page states

Express with Tools (with LocalDB) Includes the database engine and SQL Server Management Studio Express) This package contains everything needed to install and configure SQL Server as a database server. Choose either LocalDB or Express depending on your needs above.

So install this and use the management studio included with it.

### T-SQL - function with default parameters

With user defined functions, you have to declare every parameter, even if they have a default value.

The following would execute successfully:

``````IF dbo.CheckIfSFExists( 23, default ) = 0
SET @retValue = 'bla bla bla;
``````

### Cannot deserialize the current JSON object (e.g. {"name":"value"}) into type 'System.Collections.Generic.List`1

That happened to me too, because I was trying to get an `IEnumerable` but the response had a single value. Please try to make sure it's a list of data in your response. The lines I used (for api url get) to solve the problem are like these:

``````HttpResponseMessage response = await client.GetAsync("api/yourUrl");

if (response.IsSuccessStatusCode)
{
IEnumerable<RootObject> rootObjects =

foreach (var rootObject in rootObjects)
{
Console.WriteLine(
"{0}\t\${1}\t{2}",
rootObject.Data1, rootObject.Data2, rootObject.Data3);
}

}
``````

Hope It helps.

### iOS - Calling App Delegate method from ViewController

You can access the delegate like this:

``````MainClass *appDelegate = (MainClass *)[[UIApplication sharedApplication] delegate];
``````

Replace MainClass with the name of your application class.

Then, provided you have a property for the other view controller, you can call something like:

``````[appDelegate.viewController someMethod];
``````

### Redirect form to different URL based on select option element

This can be archived by adding code on the onchange event of the select control.

For Example:

``````<select onchange="this.options[this.selectedIndex].value && (window.location = this.options[this.selectedIndex].value);">
<option value="http://gmail.com">Gmail</option>
</select>
``````

### Get filename from input [type='file'] using jQuery

If selected more 1 file:

``````\$("input[type="file"]").change(function() {
var files = \$("input[type="file"]").prop("files");
var names = \$.map(files, function(val) { return val.name; });
\$(".some_div").text(names);
});
``````

`files` will be a `FileList` object. `names` is an array of strings (file names).

### How to float a div over Google Maps?

absolute positioning is evil... this solution doesn't take into account window size. If you resize the browser window, your div will be out of place!

### Emulate Samsung Galaxy Tab

If you are developing on Netbeans, you will not get the Third-Party add-ons. You can download the Skins directly from Samsung here: http://developer.samsung.com/android/tools-sdks

Restart the Android SDK Manager, and the new device should be there under Extras.

Scott

### How to check if directory exists in %PATH%?

I took your implementation using the for loop and extended it into something that iterates through all elements of the path. Each iteration of the for loop removes the first element of the path (%p) from the entire path (held in %q and %r).

``````@echo off
SET MYPATHCOPY=%PATH%

:search
for /f "delims=; tokens=1,2*" %%p in ("%MYPATHCOPY%") do (
@echo %%~p
SET MYPATHCOPY=%%~q;%%~r
)

if "%MYPATHCOPY%"==";" goto done;
goto search;

:done
``````

Sample output:

``````Z:\>path.bat
C:\Program Files\Microsoft DirectX SDK (November 2007)\Utilities\Bin\x86
c:\program files\imagemagick-6.3.4-q16
C:\WINDOWS\system32
C:\WINDOWS
C:\SFU\common\
c:\Program Files\Debugging Tools for Windows
C:\Program Files\Nmap
``````

### Two Divs on the same row and center align both of them

You could do this

``````<div style="text-align:center;">
<div style="border:1px solid #000; display:inline-block;">Div 1</div>
<div style="border:1px solid red; display:inline-block;">Div 2</div>
</div>
``````

http://jsfiddle.net/jasongennaro/MZrym/

1. wrap it in a `div` with `text-align:center;`
2. give the innder `div`s a `display:inline-block;` instead of a `float`

Best also to put that css in a stylesheet.

### How to get the hours difference between two date objects?

Use the timestamp you get by calling `valueOf` on the date object:

``````var diff = date2.valueOf() - date1.valueOf();
var diffInHours = diff/1000/60/60; // Convert milliseconds to hours
``````

### Installing and Running MongoDB on OSX

Make sure you are logged in as root user in your terminal.

Steps to start mongodb server in your mac

1. Open Terminal
2. Run the command `sudo su`
4. run the command `mongod`
5. MongoDb Server starts

Hope it helps you. Thanks

### Descending order by date filter in AngularJs

``````<!DOCTYPE html>
<html>
<body>

<p>Click the table headers to change the sorting order:</p>

<div ng-app="myApp" ng-controller="namesCtrl">

<table border="1" width="100%">
<tr>
<th ng-click="orderByMe('name')">Name</th>
<th ng-click="orderByMe('country')">Country</th>
</tr>
<tr ng-repeat="x in names | orderBy:myOrderBy:reverse">
<td>{{x.name}}</td>
<td>{{x.country}}</td>
</tr>
</table>

</div>

<script>
angular.module('myApp', []).controller('namesCtrl', function(\$scope) {
\$scope.names = [
{name:'Jani',country:'Norway'},
{name:'Carl',country:'Sweden'},
{name:'Margareth',country:'England'},
{name:'Hege',country:'Norway'},
{name:'Joe',country:'Denmark'},
{name:'Gustav',country:'Sweden'},
{name:'Birgit',country:'Denmark'},
{name:'Mary',country:'England'},
{name:'Kai',country:'Norway'}
];

\$scope.reverse=false;
\$scope.orderByMe = function(x) {

if(\$scope.myOrderBy == x) {
\$scope.reverse=!\$scope.reverse;
}
\$scope.myOrderBy = x;
}
});
</script>

</body>
</html>
``````

### Setting cursor at the end of any text of a textbox

For Windows Forms you can control cursor position (and selection) with `txtbox.SelectionStart` and `txtbox.SelectionLength` properties. If you want to set caret to end try this:

``````txtbox.SelectionStart = txtbox.Text.Length;
txtbox.SelectionLength = 0;
``````

For WPF see this question.

### 2 column div layout: right column with fixed width, left fluid

I'd like to suggest a yet-unmentioned solution: use CSS3's `calc()` to mix `%` and `px` units. `calc()` has excellent support nowadays, and it allows for fast construction of quite complex layouts.

Here's a JSFiddle link for the code below.

HTML:

``````<div class="sidebar">
sidebar fixed width
</div>
<div class="content">
content flexible width
</div>
``````

CSS:

``````.sidebar {
width: 180px;
float: right;
background: green;
}

.content {
width: calc(100% - 180px);
background: orange;
}
``````

And here's another JSFiddle demonstrating this concept applied to a more complex layout. I used SCSS here since its variables allow for flexible and self-descriptive code, but the layout can be easily re-created in pure CSS if having "hard-coded" values is not an issue.

### How can I debug my JavaScript code?

You might also check out YUI Logger. All you have to do to use it is include a couple of tags in your HTML. It is a helpful addition to Firebug, which is more or less a must.

### How to properly validate input values with React.JS?

Use `onChange={this.handleChange.bind(this, "name")` method and `value={this.state.fields["name"]}` on input text field and below that create span element to show error, see the below example.

``````export default class Form extends Component {

constructor(){
super()
this.state ={
fields: {
name:'',
email: '',
message: ''
},
errors: {},
disabled : false
}
}

handleValidation(){
let fields = this.state.fields;
let errors = {};
let formIsValid = true;

if(!fields["name"]){
formIsValid = false;
errors["name"] = "Name field cannot be empty";
}

if(typeof fields["name"] !== "undefined" && !fields["name"] === false){
if(!fields["name"].match(/^[a-zA-Z]+\$/)){
formIsValid = false;
errors["name"] = "Only letters";
}
}

if(!fields["email"]){
formIsValid = false;
errors["email"] = "Email field cannot be empty";
}

if(typeof fields["email"] !== "undefined" && !fields["email"] === false){
let lastAtPos = fields["email"].lastIndexOf('@');
let lastDotPos = fields["email"].lastIndexOf('.');

if (!(lastAtPos < lastDotPos && lastAtPos > 0 && fields["email"].indexOf('@@') === -1 && lastDotPos > 2 && (fields["email"].length - lastDotPos) > 2)) {
formIsValid = false;
errors["email"] = "Email is not valid";
}
}

if(!fields["message"]){
formIsValid = false;
errors["message"] = " Message field cannot be empty";
}

this.setState({errors: errors});
return formIsValid;
}

handleChange(field, e){
let fields = this.state.fields;
fields[field] = e.target.value;
this.setState({fields});
}

handleSubmit(e){
e.preventDefault();
if(this.handleValidation()){
console.log('validation successful')
}else{
console.log('validation failed')
}
}

render(){
return (
<form onSubmit={this.handleSubmit.bind(this)} method="POST">
<div className="row">
<div className="col-25">
<label htmlFor="name">Name</label>
</div>
<div className="col-75">
<input type="text" placeholder="Enter Name"  refs="name" onChange={this.handleChange.bind(this, "name")} value={this.state.fields["name"]}/>
<span style={{color: "red"}}>{this.state.errors["name"]}</span>
</div>
</div>
<div className="row">
<div className="col-25">
</div>
<div className="col-75">
<input type="email" placeholder="Enter Email" refs="email" aria-describedby="emailHelp" onChange={this.handleChange.bind(this, "email")} value={this.state.fields["email"]}/>
<span style={{color: "red"}}>{this.state.errors["email"]}</span>
</div>
</div>
<div className="row">
<div className="col-25">
<label htmlFor="message">Message</label>
</div>
<div className="col-75">
<textarea type="text" placeholder="Enter Message" rows="5" refs="message" onChange={this.handleChange.bind(this, "message")} value={this.state.fields["message"]}></textarea>
<span style={{color: "red"}}>{this.state.errors["message"]}</span>
</div>
</div>
<div className="row">
<button type="submit" disabled={this.state.disabled}>{this.state.disabled ? 'Sending...' : 'Send'}</button>
</div>
</form>
)
}
}
``````

### How to merge two arrays in JavaScript and de-duplicate items

Just wrote before for the same reason (works with any amount of arrays):

``````/**
* Returns with the union of the given arrays.
*
* @param Any amount of arrays to be united.
* @returns {array} The union array.
*/
function uniteArrays()
{
var union = [];
for (var argumentIndex = 0; argumentIndex < arguments.length; argumentIndex++)
{
eachArgument = arguments[argumentIndex];
if (typeof eachArgument !== 'array')
{
eachArray = eachArgument;
for (var index = 0; index < eachArray.length; index++)
{
eachValue = eachArray[index];
if (arrayHasValue(union, eachValue) == false)
union.push(eachValue);
}
}
}

return union;
}

function arrayHasValue(array, value)
{ return array.indexOf(value) != -1; }
``````

### Assign output of a program to a variable using a MS batch file

In addition to the answer, you can't directly use output redirection operators in the set part of `for` loop (e.g. if you wanna hide stderror output from a user and provide a nicer error message). Instead, you have to escape them with a caret character (`^`):

``````for /f %%O in ('some-erroring-command 2^> nul') do (echo %%O)
``````

### Set form backcolor to custom color

If you want to set the form's back color to some arbitrary RGB value, you can do this:

``````this.BackColor = Color.FromArgb(255, 232, 232); // this should be pink-ish
``````

### Using jQuery UI sortable with HTML tables

You can call `sortable` on a `<tbody>` instead of on the individual rows.

``````<table>
<tbody>
<tr>
<td>1</td>
<td>2</td>
</tr>
<tr>
<td>3</td>
<td>4</td>
</tr>
<tr>
<td>5</td>
<td>6</td>
</tr>
</tbody>
</table>?

<script>
\$('tbody').sortable();
</script>
``````

_x000D_
_x000D_
``````\$(function() {_x000D_
\$( "tbody" ).sortable();_x000D_
});``````
_x000D_
`````` _x000D_
table {_x000D_
border-spacing: collapse;_x000D_
border-spacing: 0;_x000D_
}_x000D_
td {_x000D_
width: 50px;_x000D_
height: 25px;_x000D_
border: 1px solid black;_x000D_
}``````
_x000D_
`````` _x000D_
_x000D_
<script src="//code.jquery.com/jquery-1.11.1.js"></script>_x000D_
<script src="//code.jquery.com/ui/1.11.1/jquery-ui.js"></script>_x000D_
_x000D_
<table>_x000D_
<tbody>_x000D_
<tr>_x000D_
<td>1</td>_x000D_
<td>2</td>_x000D_
</tr>_x000D_
<tr>_x000D_
<td>3</td>_x000D_
<td>4</td>_x000D_
</tr>_x000D_
<tr> _x000D_
<td>5</td>_x000D_
<td>6</td>_x000D_
</tr>_x000D_
<tr>_x000D_
<td>7</td>_x000D_
<td>8</td>_x000D_
</tr>_x000D_
<tr>_x000D_
<td>9</td> _x000D_
<td>10</td>_x000D_
</tr>  _x000D_
</tbody>    _x000D_
</table>``````
_x000D_
_x000D_
_x000D_

### How to change Android usb connect mode to charge only?

Nothing worked until I went this way: Settings>Developer options>Default USB configuration now you can choose your default USB connection purpose.

### SQL Query To Obtain Value that Occurs more than once

For postgresql:

``````SELECT * AS rec
FROM (
SELECT lastname, COUNT(*) AS counter
FROM students
GROUP BY lastname) AS tbl
WHERE counter > 1;
``````

I'm going to give you an example of how I read REST headers for my controllers. My controllers only accept application/json as a request type if I have data that needs to be read. I suspect that your problem is that you have an application/octet-stream that Spring doesn't know how to handle.

Normally my controllers look like this:

``````@Controller
public class FooController {
@Autowired
private DataService dataService;

@RequestMapping(value="/foo/", method = RequestMethod.GET)
@ResponseBody
return ResponseEntity.newInstance(dataService.getData(dataId);
}
``````

Now there is a lot of code doing stuff in the background here so I will break it down for you.

ResponseEntity is a custom object that every controller returns. It contains a static factory allowing the creation of new instances. My Data Service is a standard service class.

The magic happens behind the scenes, because you are working with JSON, you need to tell Spring to use Jackson to map HttpRequest objects so that it knows what you are dealing with.

You do this by specifying this inside your `<mvc:annotation-driven>` block of your config

``````<mvc:annotation-driven>
<mvc:message-converters>
<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
<property name="objectMapper" ref="objectMapper" />
</bean>
</mvc:message-converters>
</mvc:annotation-driven>
``````

ObjectMapper is simply an extension of `com.fasterxml.jackson.databind.ObjectMapper` and is what Jackson uses to actually map your request from JSON into an object.

I suspect you are getting your exception because you haven't specified a mapper that can read an Octet-Stream into an object, or something that Spring can handle. If you are trying to do a file upload, that is something else entirely.

So my request that gets sent to my controller looks something like this simply has an extra header called `dataId`.

If you wanted to change that to a request parameter and use `@RequestParam String dataId` to read the ID out of the request your request would look similar to this:

``````contactId : {"fooId"}
``````

This request parameter can be as complex as you like. You can serialize an entire object into JSON, send it as a request parameter and Spring will serialize it (using Jackson) back into a Java Object ready for you to use.

Example In Controller:

``````@RequestMapping(value = "/penguin Details/", method = RequestMethod.GET)
@ResponseBody
public DataProcessingResponseDTO<Pengin> getPenguinDetailsFromList(
@RequestParam DataProcessingRequestDTO jsonPenguinRequestDTO)
``````

Request Sent:

``````jsonPengiunRequestDTO: {
"draw": 1,
"columns": [
{
"data": {
},
"searchable": true,
"orderable": true,
"search": {
"value": "",
"regex": false
}
},
{
"data": {
},
"searchable": true,
"orderable": true,
"search": {
"value": "",
"regex": false
}
},
{
"data": {
"_": "customerCampaignId",
},
"name": "customerCampaignId",
"searchable": true,
"orderable": true,
"search": {
"value": "",
"regex": false
}
},
{
"data": {
"_": "penguinId",
},
"name": "penguinId",
"searchable": false,
"orderable": true,
"search": {
"value": "",
"regex": false
}
},
{
"data": {
"_": "validpenguin",
},
"name": "validpenguin",
"searchable": true,
"orderable": true,
"search": {
"value": "",
"regex": false
}
},
{
"data": {
"_": "",
},
"name": "",
"searchable": false,
"orderable": false,
"search": {
"value": "",
"regex": false
}
}
],
"order": [
{
"column": 0,
"dir": "asc"
}
],
"start": 0,
"length": 10,
"search": {
"value": "",
"regex": false
},
"objectId": "30"
}
``````

which gets automatically serialized back into an DataProcessingRequestDTO object before being given to the controller ready for me to use.

As you can see, this is quite powerful allowing you to serialize your data from JSON to an object without having to write a single line of code. You can do this for `@RequestParam` and `@RequestBody` which allows you to access JSON inside your parameters or request body respectively.

Now that you have a concrete example to go off, you shouldn't have any problems once you change your request type to `application/json`.

### Bootstrap modal appearing under background

In my case, the cause was boostrap.min.css. Once I excluded it from my HTML file as a reference, the dialog showed in front of the modal shade.

### enable/disable zoom in Android WebView

Improved Lukas Knuth's version:

``````public class TweakedWebView extends WebView {

private ZoomButtonsController zoomButtons;

public TweakedWebView(Context context) {
super(context);
init();
}

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

public TweakedWebView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}

private void init() {
getSettings().setBuiltInZoomControls(true);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
getSettings().setDisplayZoomControls(false);
} else {
try {
Method method = getClass()
.getMethod("getZoomButtonsController");
zoomButtons = (ZoomButtonsController) method.invoke(this);
} catch (Exception e) {
// pass
}
}
}

@Override
public boolean onTouchEvent(MotionEvent ev) {
boolean result = super.onTouchEvent(ev);
if (zoomButtons != null) {
zoomButtons.setVisible(false);
zoomButtons.getZoomControls().setVisibility(View.GONE);
}
return result;
}

}
``````

### Open another application from your own (intent)

Use following:

``````String packagename = "com.example.app";
startActivity(getPackageManager().getLaunchIntentForPackage(packagename));
``````

### How to pass a querystring or route parameter to AWS Lambda from Amazon API Gateway

My goal was to pass a query string similar to:

`````` protodb?sql=select * from protodb.prototab
``````

to a Node.js 12 Lambda function via a URL from the API gateway. I tried a number of the ideas from the other answers but really wanted to do something in the most API gateway UI native way possible, so I came up with this that worked for me (as of the UI for API Gateway as of December 2020):

On the API Gateway console for a given API, under resources, select the get method. Then select its Integration Request and fill out the data for the lambda function at the top of the page.

Scroll to the bottom and open up the mapping templates section. Choose Request Body Passthrough when there are no templates defined (recommended).

Click on Add mapping templates and create one with the content-type of application/json and hit the check mark button.

For that mapping template, choose the Method Request passthrough on the drop down list for generate template which will fill the textbox under it with AWS' general way to pass everything.

Hit the save button.

Now when I tested it, I could not get the parameter to come through as event.sql under node JS in the Lambda function. It turns out that when the API gateway sends the URL sql query parameter to the Lambda function, it comes through for Node.js as:

`````` var insql = event.params.querystring.sql;
``````

So the trick that took some time for me was to use JSON.stringify to show the full event stack and then work my way down through the sections to be able to pull out the sql parameter from the query string.

So basically you can use the default passthrough functionality in the API gateway with the trick being how the parameters are passed when you are in the Lambda function.

### How to format date and time in Android?

Use the standard Java DateFormat class.

For example to display the current date and time do the following:

``````Date date = new Date(location.getTime());
DateFormat dateFormat = android.text.format.DateFormat.getDateFormat(getApplicationContext());
mTimeText.setText("Time: " + dateFormat.format(date));
``````

You can initialise a Date object with your own values, however you should be aware that the constructors have been deprecated and you should really be using a Java Calendar object.

### Multiple select statements in Single query

If you use MyISAM tables, the fastest way is querying directly the stats:

``````select table_name, table_rows
from information_schema.tables
where
table_schema='databasename' and
table_name in ('user_table','cat_table','course_table')
``````

If you have InnoDB you have to query with count() as the reported value in information_schema.tables is wrong.

### Ruby: kind_of? vs. instance_of? vs. is_a?

It is more Ruby-like to ask objects whether they respond to a method you need or not, using `respond_to?`. This allows both minimal interface and implementation unaware programming.

It is not always applicable of course, thus there is still a possibility to ask about more conservative understanding of "type", which is class or a base class, using the methods you're asking about.

### Longer object length is not a multiple of shorter object length?

Yes, this is something that you should worry about. Check the length of your objects with nrow(). R can auto-replicate objects so that they're the same length if they differ, which means you might be performing operations on mismatched data.

In this case you have an obvious flaw in that your subtracting aggregated data from raw data. These will definitely be of different lengths. I suggest that you merge them as time series (using the dates), then locf(), then do your subtraction. Otherwise merge them by truncating the original dates to the same interval as the aggregated series. Just be very careful that you don't drop observations.

Lastly, as some general advice as you get started: look at the result of your computations to see if they make sense. You might even pull them into a spreadsheet and replicate the results.

### What is output buffering?

I know that this is an old question but I wanted to write my answer for visual learners. I couldn't find any diagrams explaining output buffering on the worldwide-web so I made a diagram myself in Windows `mspaint.exe`.

If output buffering is turned off, then `echo` will send data immediately to the Browser.

If output buffering is turned on, then an `echo` will send data to the output buffer before sending it to the Browser.

phpinfo

To see whether Output buffering is turned on / off please refer to phpinfo at the core section. The `output_buffering` directive will tell you if Output buffering is on/off.

In this case the `output_buffering` value is 4096 which means that the buffer size is 4 KB. It also means that Output buffering is turned on, on the Web server.

php.ini

It's possible to turn on/off and change buffer size by changing the value of the `output_buffering` directive. Just find it in `php.ini`, change it to the setting of your choice, and restart the Web server. You can find a sample of my `php.ini` below.

``````; Output buffering is a mechanism for controlling how much output data
; (excluding headers and cookies) PHP should keep internally before pushing that
; data to the client. If your application's output exceeds this setting, PHP
; will send that data in chunks of roughly the size you specify.
; Turning on this setting and managing its maximum buffer size can yield some
; interesting side-effects depending on your application and web server.
; through print or echo. You also may see performance benefits if your server is
; emitting less packets due to buffered output versus PHP streaming the output
; as it gets it. On production servers, 4096 bytes is a good setting for performance
; reasons.
; Note: Output buffering can also be controlled via Output Buffering Control
;   functions.
; Possible Values:
;   On = Enabled and buffer is unlimited. (Use with caution)
;   Off = Disabled
;   Integer = Enables the buffer and sets its maximum size in bytes.
; Note: This directive is hardcoded to Off for the CLI SAPI
; Default Value: Off
; Development Value: 4096
; Production Value: 4096
; http://php.net/output-buffering
output_buffering = 4096
``````

The directive `output_buffering` is not the only configurable directive regarding Output buffering. You can find other configurable Output buffering directives here: http://php.net/manual/en/outcontrol.configuration.php

Example: ob_get_clean()

Below you can see how to capture an `echo` and manipulate it before sending it to the browser.

``````// Turn on output buffering
ob_start();

echo 'Hello World';  // save to output buffer

\$output = ob_get_clean();  // Get content from the output buffer, and discard the output buffer ...
\$output = strtoupper(\$output); // manipulate the output

echo \$output;  // send to output stream / Browser

// OUTPUT:
HELLO WORLD
``````

Examples: Hackingwithphp.com

http://www.hackingwithphp.com/13/0/0/output-buffering

### Check if a div does NOT exist with javascript

There's an even better solution. You don't even need to check if the element returns `null`. You can simply do this:

``````if (document.getElementById('elementId')) {
console.log('exists')
}
``````

That code will only log `exists` to console if the element actually exists in the DOM.

### Git merge reports "Already up-to-date" though there is a difference

This often happens to me when I know there are changes on the remote master, so I try to merge them using `git merge master`. However, this doesn't merge with the remote master, but with your local master.

So before doing the merge, checkout master, and then `git pull` there. Then you will be able to merge the new changes into your branch.

### How to remove elements from a generic list while iterating over it?

I would do like this

``````using System.IO;
using System;
using System.Collections.Generic;

class Author
{
public string Firstname;
public string Lastname;
public int no;
}

class Program
{
private static bool isEven(int i)
{
return ((i % 2) == 0);
}

static void Main()
{
var authorsList = new List<Author>()
{
new Author{ Firstname = "Bob", Lastname = "Smith", no = 2 },
new Author{ Firstname = "Fred", Lastname = "Jones", no = 3 },
new Author{ Firstname = "Brian", Lastname = "Brains", no = 4 },
new Author{ Firstname = "Billy", Lastname = "TheKid", no = 1 }
};

authorsList.RemoveAll(item => isEven(item.no));

foreach(var auth in authorsList)
{
Console.WriteLine(auth.Firstname + " " + auth.Lastname);
}
}
}
``````

OUTPUT

``````Fred Jones
Billy TheKid
``````

### HTML list-style-type dash

Another way:

``````li:before {
content: '\2014\00a0\00a0'; /* em-dash followed by two non-breaking spaces*/
}
li {
list-style: none;
text-indent: -1.5em;
}
``````

### How to store a datetime in MySQL with timezone info

All the symptoms you describe suggest that you never tell MySQL what time zone to use so it defaults to system's zone. Think about it: if all it has is `'2011-03-13 02:49:10'`, how can it guess that it's a local Tanzanian date?

As far as I know, MySQL doesn't provide any syntax to specify time zone information in dates. You have to change it a per-connection basis; something like:

``````SET time_zone = 'EAT';
``````

If this doesn't work (to use named zones you need that the server has been configured to do so and it's often not the case) you can use UTC offsets because Tanzania does not observe daylight saving time at the time of writing but of course it isn't the best option:

``````SET time_zone = '+03:00';
``````

### \$http.get(...).success is not a function

This might be redundant but the above most voted answer says `.then(function (success)` and that didn't work for me as of Angular version `1.5.8`. Instead use `response` then inside the block `response.data` got me my json data I was looking for.

``````\$http({
method: 'get',
url: 'data/data.json'
}).then(function (response) {
console.log(response, 'res');
data = response.data;
},function (error){
console.log(error, 'can not get data.');
});
``````

### ListBox vs. ListView - how to choose for data binding

A ListView is a specialized ListBox (that is, it inherits from ListBox). It allows you to specify different views rather than a straight list. You can either roll your own view, or use GridView (think explorer-like "details view"). It's basically the multi-column listbox, the cousin of windows form's listview.

If you don't need the additional capabilities of ListView, you can certainly use ListBox if you're simply showing a list of items (Even if the template is complex).

### Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop

`Iterator.remove()` is safe, you can use it like this:

``````List<String> list = new ArrayList<>();

// This is a clever way to create the iterator and call iterator.hasNext() like
// you would do in a while-loop. It would be the same as doing:
//     Iterator<String> iterator = list.iterator();
//     while (iterator.hasNext()) {
for (Iterator<String> iterator = list.iterator(); iterator.hasNext();) {
String string = iterator.next();
if (string.isEmpty()) {
// Remove the current element from the iterator and the list.
iterator.remove();
}
}
``````

Note that `Iterator.remove()` is the only safe way to modify a collection during iteration; the behavior is unspecified if the underlying collection is modified in any other way while the iteration is in progress.

And similarly, if you have a `ListIterator` and want to add items, you can use `ListIterator#add`, for the same reason you can use `Iterator#remove` — it's designed to allow it.

In your case you tried to remove from a list, but the same restriction applies if trying to `put` into a `Map` while iterating its content.

### Get original URL referer with PHP?

try this

``````(isset (\$_SERVER['HTTP_CLIENT_IP']) ?
\$_SERVER['HTTP_CLIENT_IP'] :
(isset (\$_SERVER['HTTP_X_FORWARDED_FOR']) ?
\$_SERVER['HTTP_X_FORWARDED_FOR'] :
)
)
``````

### Convert Xml to DataTable

How To Read XML Data into a DataSet by Using Visual C# .NET contains some details. Basically, you can use the overloaded DataSet method ReadXml to get the data into a DataSet. Your XML data will be in the first DataTable there.

There is also a DataTable.ReadXml method.

### how to get bounding box for div element in jquery

using JQuery:

``````myelement=\$("#myelement")
[myelement.offset().left, myelement.offset().top,  myelement.width(), myelement.height()]
``````

### installing cPickle with python 3.5

`cPickle` comes with the standard library… in python 2.x. You are on python 3.x, so if you want `cPickle`, you can do this:

``````>>> import _pickle as cPickle
``````

However, in 3.x, it's easier just to use `pickle`.

No need to install anything. If something requires `cPickle` in python 3.x, then that's probably a bug.

### Custom circle button

Use xml drawable like this:

Save the following contents as `round_button.xml` in `drawable` folder

``````<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_pressed="false">
<shape android:shape="oval">
</shape>
</item>
<item android:state_pressed="true">
<shape android:shape="oval">
<solid android:color="#c20586"/>
</shape>
</item>
</selector>
``````

Android Material Effect: Although `FloatingActionButton` is a better option, If you want to do it using xml selector, create a folder `drawable-v21` in `res` and save another `round_button.xml` there with following xml

``````<?xml version="1.0" encoding="utf-8"?>
<ripple xmlns:android="http://schemas.android.com/apk/res/android"
android:color="#c20586">
<item>
<shape android:shape="oval">
</shape>
</item>
</ripple>
``````

And set it as background of `Button` in xml like this:

``````<Button
android:layout_width="50dp"
android:layout_height="50dp"
android:background="@drawable/round_button"
android:gravity="center_vertical|center_horizontal"
android:text="hello"
android:textColor="#fff" />
``````

Important:

1. If you want it to show all these states (enabled, disabled, highlighted etc), you will use selector as described here.
2. You've to keep both files in order to make the drawable backward-compatible. Otherwise, you'll face weird exceptions in previous android version.

### Equivalent of Clean & build in Android Studio?

in android studio version 2+, use this in gradle config

``````android{
..

compileOptions {
sourceCompatibility JavaVersion.VERSION_1_7
targetCompatibility JavaVersion.VERSION_1_7
incremental = false;
}
...

}
``````

after 3 days of search and test :(, this solve "rebuild for any run"

### Delete forked repo from GitHub

There will not be any harm deleting the forked repositories. You can again fork that. It won't change the original code. The flow is like this...

1) You fork a repository. Just think of this as another copy of code which you can access or make changes to. The url of this repository will be of the form `https://github.com/your-user-name/original-repo`.

2) You make some changes to that in your local machine and push them. Now the copy you created will be updated, but not the original one from which you have forked your repo.

3) If you want the changes you added to your forked repo to be applied to original repo(this may be helpful to the people who are organizing the repo) then you have to create a `pull request` which you can do through UI. Then if they like your contribution, they will `merge` that with their code.

Generally this is what open source organizations do.

### Angular pass callback function to child component as @Input similar to AngularJS way

UPDATE

This answer was submitted when Angular 2 was still in alpha and many of the features were unavailable / undocumented. While the below will still work, this method is now entirely outdated. I strongly recommend the accepted answer over the below.

Yes in fact it is, however you will want to make sure that it is scoped correctly. For this I've used a property to ensure that `this` means what I want it to.

``````@Component({
...
template: '<child [myCallback]="theBoundCallback"></child>',
directives: [ChildComponent]
})
export class ParentComponent{
public theBoundCallback: Function;

public ngOnInit(){
this.theBoundCallback = this.theCallback.bind(this);
}

public theCallback(){
...
}
}

@Component({...})
export class ChildComponent{
//This will be bound to the ParentComponent.theCallback
@Input()
public myCallback: Function;
...
}
``````

### Request redirect to /Account/Login?ReturnUrl=%2f since MVC 3 install on server

If nothing works then add authentication mode="Windows" in your system.web attribute in your Web.Config file. hope it will work for you.

### Warning - Build path specifies execution environment J2SE-1.4

Just change the version in Window-> Preferences-> Java -> Installed JREs. Check the installed JREs list. Then, Right-click on your project -> properties -> Java build path -> libraries. Change the "JRE System Library" to the version in "installed JREs".

The warning will be gone.

For debian after installing node enter

``````curl -k -O -L https://npmjs.org/install.sh
ln -s /usr/bin/nodejs /usr/bin/node
sh install.sh
``````

### Validation for 10 digit mobile number and focus input field on invalid

you can also use jquery for this

``````  var phoneNumber = 8882070980;
var filter = /^((\+[1-9]{1,4}[ \-]*)|(\([0-9]{2,3}\)[ \-]*)|([0-9]{2,4})[ \-]*)*?[0-9]{3,4}?[ \-]*[0-9]{3,4}?\$/;

if (filter.test(phoneNumber)) {
if(phoneNumber.length==10){
var validate = true;
} else {
var validate = false;
}
}
else {
var validate = false;
}

if(validate){
//number is equal to 10 digit or number is not string
enter code here...
}
``````

### How to unstash only certain files?

If you `git stash pop` (with no conflicts) it will remove the stash after it is applied. But if you `git stash apply` it will apply the patch without removing it from the stash list. Then you can revert the unwanted changes with `git checkout -- files...`

### How to add parameters to HttpURLConnection using POST using NameValuePair

`AsyncTask` to send data as `JSONObect` via `POST` Method

``````public class PostMethodDemo extends AsyncTask<String , Void ,String> {
String server_response;

@Override
protected String doInBackground(String... strings) {
URL url;
HttpURLConnection urlConnection = null;

try {
url = new URL(strings[0]);
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setDoOutput(true);
urlConnection.setDoInput(true);
urlConnection.setRequestMethod("POST");

DataOutputStream wr = new DataOutputStream(urlConnection.getOutputStream ());

try {
JSONObject obj = new JSONObject();
obj.put("key1" , "value1");
obj.put("key2" , "value2");

wr.writeBytes(obj.toString());
Log.e("JSON Input", obj.toString());
wr.flush();
wr.close();
} catch (JSONException ex) {
ex.printStackTrace();
}
urlConnection.connect();

int responseCode = urlConnection.getResponseCode();

if(responseCode == HttpURLConnection.HTTP_OK){
}

} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}

@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
Log.e("Response", "" + server_response);
}
}

public static String readStream(InputStream in) {
StringBuffer response = new StringBuffer();
try {
String line = "";
response.append(line);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
} catch (IOException e) {
e.printStackTrace();
}
}
}
return response.toString();
}
``````

### npm throws error without sudo

Actually, I was also having the same problem. I was running Ubuntu. Mine problem arises because I'd lost my public key of the Ubuntu. Even updating my system was not happening. It was giving GPG error. In that case, you can regain your key by using this command:

``````sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys <key in GPG error>
``````

After that npm works fine!

### Setting a max height on a table

I had a coworker ask how to do this today, and this is what I came up with. I don't love it but it is a way to do it without js and have headers respected. The main drawback however is you lose some semantics due to not having a true table header anymore.

Basically I wrap a table within a table, and use a div as the scroll container by giving it a `max-height`. Since I wrap the table in a parent table "colspanning" the fake header rows it appears as if the table respects them, but in reality the child table just has the same number of rows.

One small issue due to the scroll bar taking up space the child table column widths wont match up exactly.

Live Demo

Markup

``````<table class="table-container">
<tbody>
<tr>
</tr>
<tr>
<td colspan="2">
<div class="scroll-container">
<table>
<tr>
<td>entry1</td>
<td>entry1</td>
</tr>
</table>
</div>
</td>
</tr>
</tbody>
</table>
``````

CSS

``````.table-container {
border:1px solid #ccc;
width:50%;
}
.table-container table {
width: 100%;
}
.scroll-container{
max-height: 150px;
overflow-y: scroll;
}
``````

### python mpl_toolkits installation issue

It doesn't work on Ubuntu 16.04, it seems that some libraries have been forgotten in the python installation package on this one. You should use package manager instead.

#### Solution

Uninstall matplotlib from pip then install it again with apt-get

python 2:

``````sudo pip uninstall matplotlib
sudo apt-get install python-matplotlib
``````

python 3:

``````sudo pip3 uninstall matplotlib
sudo apt-get install python3-matplotlib
``````

### How to get start and end of day in Javascript?

Using the luxon.js library, same can be achieved using startOf and endOf methods by passing the 'day' as parameter

``````var DateTime = luxon.DateTime;
DateTime.local().startOf('day').toUTC().toISO(); //2017-11-16T18:30:00.000Z
DateTime.local().endOf('day').toUTC().toISO(); //2017-11-17T18:29:59.999Z
DateTime.fromISO(new Date().toISOString()).startOf('day').toUTC().toISO(); //2017-11-16T18:30:00.000Z
``````

remove .toUTC() if you need only the local time

and you may ask why not moment.js, answer is here for that.

### Static Initialization Blocks

It is a common misconception to think that a static block has only access to static fields. For this I would like to show below piece of code that I quite often use in real-life projects (copied partially from another answer in a slightly different context):

``````public enum Language {
ENGLISH("eng", "en", "en_GB", "en_US"),
GERMAN("de", "ge"),
CROATIAN("hr", "cro"),
RUSSIAN("ru"),
BELGIAN("be",";-)");

static final private Map<String,Language> ALIAS_MAP = new HashMap<String,Language>();
static {
for (Language l:Language.values()) {
// ignoring the case by normalizing to uppercase
ALIAS_MAP.put(l.name().toUpperCase(),l);
for (String alias:l.aliases) ALIAS_MAP.put(alias.toUpperCase(),l);
}
}

static public boolean has(String value) {
// ignoring the case by normalizing to uppercase
return ALIAS_MAP.containsKey(value.toUpper());
}

static public Language fromString(String value) {
if (value == null) throw new NullPointerException("alias null");
Language l = ALIAS_MAP.get(value);
if (l == null) throw new IllegalArgumentException("Not an alias: "+value);
return l;
}

private List<String> aliases;
private Language(String... aliases) {
this.aliases = Arrays.asList(aliases);
}
}
``````

Here the initializer is used to maintain an index (`ALIAS_MAP`), to map a set of aliases back to the original enum type. It is intended as an extension to the built-in valueOf method provided by the `Enum` itself.

As you can see, the static initializer accesses even the `private` field `aliases`. It is important to understand that the `static` block already has access to the `Enum` value instances (e.g. `ENGLISH`). This is because the order of initialization and execution in the case of `Enum` types, just as if the `static private` fields have been initialized with instances before the `static` blocks have been called:

1. The `Enum` constants which are implicit static fields. This requires the Enum constructor and instance blocks, and instance initialization to occur first as well.
2. `static` block and initialization of static fields in the order of occurrence.

This out-of-order initialization (constructor before `static` block) is important to note. It also happens when we initialize static fields with the instances similarly to a Singleton (simplifications made):

``````public class Foo {
static { System.out.println("Static Block 1"); }
public static final Foo FOO = new Foo();
static { System.out.println("Static Block 2"); }
public Foo() { System.out.println("Constructor"); }
static public void main(String p[]) {
System.out.println("In Main");
new Foo();
}
}
``````

What we see is the following output:

``````Static Block 1
Constructor
Static Block 2
In Main
Constructor
``````

Clear is that the static initialization actually can happen before the constructor, and even after:

Simply accessing Foo in the main method, causes the class to be loaded and the static initialization to start. But as part of the Static initialization we again call the constructors for the static fields, after which it resumes static initialization, and completes the constructor called from within the main method. Rather complex situation for which I hope that in normal coding we would not have to deal with.

### What is the difference between MySQL, MySQLi and PDO?

Those are different APIs to access a MySQL backend

• The mysql is the historical API
• The mysqli is a new version of the historical API. It should perform better and have a better set of function. Also, the API is object-oriented.
• PDO_MySQL, is the MySQL for PDO. PDO has been introduced in PHP, and the project aims to make a common API for all the databases access, so in theory you should be able to migrate between RDMS without changing any code (if you don't use specific RDBM function in your queries), also object-oriented.

So it depends on what kind of code you want to produce. If you prefer object-oriented layers or plain functions...

1. PDO
2. MySQLi
3. mysql

Also my feeling, the mysql API would probably being deleted in future releases of `PHP`.

### How can I remove specific rules from iptables?

You may also use the rule's number (--line-numbers):

``````iptables -L INPUT --line-numbers
``````

Example output :

``````Chain INPUT (policy ACCEPT)
num  target prot opt source destination
1    ACCEPT     udp  --  anywhere  anywhere             udp dpt:domain
2    ACCEPT     tcp  --  anywhere  anywhere             tcp dpt:domain
3    ACCEPT     udp  --  anywhere  anywhere             udp dpt:bootps
4    ACCEPT     tcp  --  anywhere  anywhere             tcp dpt:bootps
``````

So if you would like to delete second rule :

``````iptables -D INPUT 2
``````

#### Update

If you use(d) a specific table (eg nat), you have to add it to the delete command (thx to @ThorSummoner for the comment)

``````sudo iptables -t nat -D PREROUTING 1
``````

### getting the X/Y coordinates of a mouse click on an image with jQuery

The below code works always even if any image makes the window scroll.

``````\$(function() {
\$("#demo-box").click(function(e) {

var offset = \$(this).offset();
var relativeX = (e.pageX - offset.left);
var relativeY = (e.pageY - offset.top);

alert("X: " + relativeX + "  Y: " + relativeY);

});
});
``````

### using facebook sdk in Android studio

I fixed the

"Could not find property 'ANDROID_BUILD_SDK_VERSION' on project ':facebook'."

error on the `build.gradle` file, by adding in `gradle.properties` the values:

``````ANDROID_BUILD_TARGET_SDK_VERSION=21<br>
ANDROID_BUILD_MIN_SDK_VERSION=15<br>
ANDROID_BUILD_TOOLS_VERSION=21.1.2<br>
ANDROID_BUILD_SDK_VERSION=21<br>
``````

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

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

### Accessing constructor of an anonymous class

Here's another way around the problem:

``````public class Test{

public static final void main(String...args){

private String message = null;

this.message = message;
return this;
}

public void run(){
System.out.println(message);
}
}.initialise(args[0]).start();
}
}
``````

### Problems with a PHP shell script: "Could not open input file"

I know its stupid but in my case i was outside of my project folder i didn't have spark file.

### CSS media queries: max-width OR max-height

There are two ways for writing a proper media queries in css. If you are writing media queries for larger device first, then the correct way of writing will be:

``````@media only screen
and (min-width : 415px){
/* Styles */
}

@media only screen
and (min-width : 769px){
/* Styles */
}

@media only screen
and (min-width : 992px){
/* Styles */
}
``````

But if you are writing media queries for smaller device first, then it would be something like:

``````@media only screen
and (max-width : 991px){
/* Styles */
}

@media only screen
and (max-width : 768px){
/* Styles */
}

@media only screen
and (max-width : 414px){
/* Styles */
}
``````

### No tests found with test runner 'JUnit 4'

Yet another possible solution I'll throw into the ring: I wasn't able to run the test class either from the editor window, nor the Package Explorer, but right-clicking on the class name in the Outline view and selecting Run As JUnit Test did work... Go figure!

### The conversion of a datetime2 data type to a datetime data type resulted in an out-of-range value

``````    public DateTime? Time{ get; set; }
``````

Worked for me.

### How can I play sound in Java?

This thread is rather old but I have determined an option that could prove useful.

Instead of using the Java `AudioStream` library you could use an external program like Windows Media Player or VLC and run it with a console command through Java.

``````String command = "\"C:/Program Files (x86)/Windows Media Player/wmplayer.exe\" \"C:/song.mp3\"";
try {
Process p = Runtime.getRuntime().exec(command);
catch (IOException e) {
e.printStackTrace();
}
``````

This will also create a separate process that can be controlled it the program.

``````p.destroy();
``````

Of course this will take longer to execute than using an internal library but there may be programs that can start up faster and possibly without a GUI given certain console commands.

If time is not of the essence then this is useful.

### What's the difference between "git reset" and "git checkout"?

In their simplest form, `reset` resets the index without touching the working tree, while `checkout` changes the working tree without touching the index.

Resets the index to match `HEAD`, working tree left alone:

``````git reset
``````

Conceptually, this checks out the index into the working tree. To get it to actually do anything you would have to use `-f` to force it to overwrite any local changes. This is a safety feature to make sure that the "no argument" form isn't destructive:

``````git checkout
``````

Once you start adding parameters it is true that there is some overlap.

`checkout` is usually used with a branch, tag or commit. In this case it will reset `HEAD` and the index to the given commit as well as performing the checkout of the index into the working tree.

Also, if you supply `--hard` to `reset` you can ask `reset` to overwrite the working tree as well as resetting the index.

If you current have a branch checked out out there is a crucial different between `reset` and `checkout` when you supply an alternative branch or commit. `reset` will change the current branch to point at the selected commit whereas `checkout` will leave the current branch alone but will checkout the supplied branch or commit instead.

Other forms of `reset` and `commit` involve supplying paths.

If you supply paths to `reset` you cannot supply `--hard` and `reset` will only change the index version of the supplied paths to the version in the supplied commit (or `HEAD` if you don't specify a commit).

If you supply paths to `checkout`, like `reset` it will update the index version of the supplied paths to match the supplied commit (or `HEAD`) but it will always checkout the index version of the supplied paths into the working tree.

### SQLAlchemy: how to filter date field?

``````from app import SQLAlchemyDB as db

Chance.query.filter(Chance.repo_id==repo_id,
Chance.status=="1",
db.func.date(Chance.apply_time)<=end,
db.func.date(Chance.apply_time)>=start).count()
``````

it is equal to:

``````select
count(id)
from
Chance
where
repo_id=:repo_id
and status='1'
and date(apple_time) <= end
and date(apple_time) >= start
``````

### Which ChromeDriver version is compatible with which Chrome Browser version?

In case of mine, I solved it just by `npm install protractor@latest -g` and `npm install webdriver-manager@latest`. I am using chrome 80.x version. It worked for me in both Angular 4 & 6

### SQL update statement in C#

This is not a correct method of updating record in SQL:

``````command.CommandText = "UPDATE Student(LastName, FirstName, Address, City) VALUES (@ln, @fn, @add, @cit) WHERE LastName='" + lastName + "' AND FirstName='" + firstName+"'";
``````

You should write it like this:

``````command.CommandText = "UPDATE Student
``````

Then you add the parameters same as you added them for the insert operation.

### :first-child not working as expected

you can also use

``````.detail_container h1:nth-of-type(1)
``````

By changing the number 1 by any other number you can select any other h1 item.

### Removing underline with href attribute

Add a style with the attribute `text-decoration:none;`:

There are a number of different ways of doing this.

Inline style:

``````<a href="xxx.html" style="text-decoration:none;">goto this link</a>
``````

Inline stylesheet:

``````<html>
<style type="text/css">
a {
text-decoration:none;
}
</style>
<body>
</body>
</html>
``````

External stylesheet:

``````<html>
<body>
</body>
</html>
``````

stylesheet.css:

``````a {
text-decoration:none;
}
``````

### Keeping session alive with Curl and PHP

You also need to set the option `CURLOPT_COOKIEFILE`.

The manual describes this as

The name of the file containing the cookie data. The cookie file can be in Netscape format, or just plain HTTP-style headers dumped into a file. If the name is an empty string, no cookies are loaded, but cookie handling is still enabled.

Since you are using the cookie jar you end up saving the cookies when the requests finish, but since the `CURLOPT_COOKIEFILE` is not given, cURL isn't sending any of the saved cookies on subsequent requests.

### Field 'id' doesn't have a default value?

make sure that you do not have defined setter for the for your primary key in model class.

``````public class User{
@Id
@GeneratedValues
private int user_Id;

public int getUser_Id{
return user_Id;
}

}

}
}
``````

# If list

I was doing something for a list which is a set of strings and you want to remove all lines that have a certain substring you can do this

``````import re
def RemoveInList(sub,LinSplitUnOr):
indices = [i for i, x in enumerate(LinSplitUnOr) if re.search(sub, x)]
A = [i for j, i in enumerate(LinSplitUnOr) if j not in indices]
return A
``````

where `sub` is a patter that you do not wish to have in a list of lines `LinSplitUnOr`

for example

``````A=['Apple.good','Orange.good','Pear.bad','Pear.good','Banana.bad','Potato.bad']
sub = 'good'
A=RemoveInList(sub,A)
``````

Then `A` will be

### "Could not find a part of the path" error message

There can be one of the two cause for this error:

1. Path is not correct - but it is less likely as CreateDirectory should create any path unless path itself is not valid, read invalid characters
2. Account through which your application is running don't have rights to create directory at path location, like if you are trying to create directory on shared drive with not enough privileges etc

### Change IPython/Jupyter notebook working directory

If you are using ipython in linux, then follow the steps:
`!cd /directory_name/`
You can try all the commands which work in you linux terminal.
`!vi file_name.py`

Just specify the exclamation(!) symbol before your linux commands.

### Reset MySQL root password using ALTER USER statement after install on Mac

I also got the same problem in mac OS X 10.10.4(Yosemite).SET PASSWORD work for me.Alter password for mysql- mysql> SET PASSWORD = PASSWORD('your_password'); Query OK, 0 rows affected, 1 warning (0.01 sec)

set your Mysql environment path variable in .bash_profile and add the below line
export PATH=\$PATH:/usr/local/mysql/bin, after that, run the following command :source .bash_profile

### How to read a file into vector in C++?

1. In the loop you are assigning value rather than comparing value so

i=((Main.size())-1) -> i=(-1) since Main.size()

Main[i] will yield "Vector Subscript out of Range" coz i = -1.

2. You get Main.size() as 0 maybe becuase its not it can't find the file. Give the file path and check the output. Also it would be good to initialize the variables.

### Any way to write a Windows .bat file to kill processes?

``````taskkill /f /im "devenv.exe"
``````

this will forcibly kill the pid with the exe name "devenv.exe"

equivalent to -9 on the nix'y kill command

### size of uint8, uint16 and uint32?

It's quite unclear how you are computing the size ("the size in debug mode"?").

Use `printf()`:

``````printf("the size of c is %u\n", (unsigned int) sizeof c);
``````

Normally you'd print a `size_t` value (which is the type `sizeof` returns) with `%zu`, but if you're using a pre-C99 compiler like Visual Studio that won't work.

You need to find the `typedef` statements in your code that define the custom names like `uint8` and so on; those are not standard so nobody here can know how they're defined in your code.

New C code should use `<stdint.h>` which gives you `uint8_t` and so on.

### Angular 6 Material mat-select change method removed

For me `(selectionChange)` and the suggested `(onSelectionChange)` didn't work and I'm not using `ReactiveForms`. What I ended up doing was using the `(valueChange)` event like:

``````<mat-select (valueChange)="someFunction()">
``````

And this worked for me

### Regex matching beginning AND end strings

``````^dbo\..*_fn\$
``````

This should work you.

### How to use "svn export" command to get a single file from the repository?

You don't have to do this locally either. You can do it through a remote repository, for example:

``````svn export http://<repo>/process/test.txt /path/to/code/
``````

### u'\ufeff' in Python string

This problem arise basically when you save your python code in a UTF-8 or UTF-16 encoding because python add some special character at the beginning of the code automatically (which is not shown by the text editors) to identify the encoding format. But, when you try to execute the code it gives you the syntax error in line 1 i.e, start of code because python compiler understands ASCII encoding. when you view the code of file using read() function you can see at the begin of the returned code '\ufeff' is shown. The one simplest solution to this problem is just by changing the encoding back to ASCII encoding(for this you can copy your code to a notepad and save it Remember! choose the ASCII encoding... Hope this will help.

### Amazon S3 direct file upload from client browser - private key disclosure

You're saying you want a "serverless" solution. But that means you have no ability to put any of "your" code in the loop. (NOTE: Once you give your code to a client, it's "their" code now.) Locking down CORS is not going to help: People can easily write a non-web-based tool (or a web-based proxy) that adds the correct CORS header to abuse your system.

The big problem is that you can't differentiate between the different users. You can't allow one user to list/access his files, but prevent others from doing so. If you detect abuse, there is nothing you can do about it except change the key. (Which the attacker can presumably just get again.)

Your best bet is to create an "IAM user" with a key for your javascript client. Only give it write access to just one bucket. (but ideally, do not enable the ListBucket operation, that will make it more attractive to attackers.)

If you had a server (even a simple micro instance at \$20/month), you could sign the keys on your server while monitoring/preventing abuse in realtime. Without a server, the best you can do is periodically monitor for abuse after-the-fact. Here's what I would do:

1) periodically rotate the keys for that IAM user: Every night, generate a new key for that IAM user, and replace the oldest key. Since there are 2 keys, each key will be valid for 2 days.

2) enable S3 logging, and download the logs every hour. Set alerts on "too many uploads" and "too many downloads". You will want to check both total file size and number of files uploaded. And you will want to monitor both the global totals, and also the per-IP address totals (with a lower threshold).

These checks can be done "serverless" because you can run them on your desktop. (i.e. S3 does all the work, these processes just there to alert you to abuse of your S3 bucket so you don't get a giant AWS bill at the end of the month.)

### How to copy to clipboard in Vim?

Use the register `"+` to copy to the system clipboard (i.e. `"+y` instead of `y`).

Likewise you can paste from `"+` to get text from the system clipboard (i.e. `"+p` instead of `p`).

### use of entityManager.createNativeQuery(query,foo.class)

Here is a DB2 Stored Procidure that receive a parameter

#### SQL

``````CREATE PROCEDURE getStateByName (IN StateName VARCHAR(128))
DYNAMIC RESULT SETS 1
P1: BEGIN
-- Declare cursor
DECLARE State_Cursor CURSOR WITH RETURN for
-- #######################################################################
-- # Replace the SQL statement with your statement.
-- # Note: Be sure to end statements with the terminator character (usually ';')
-- #
-- # The example SQL statement SELECT NAME FROM SYSIBM.SYSTABLES
-- # returns all names from SYSIBM.SYSTABLES.
-- ######################################################################
SELECT * FROM COUNTRY.STATE
WHERE PROVINCE_NAME LIKE UPPER(stateName);
-- Cursor left open for client application
OPEN Province_Cursor;
END P1
``````

#### Java

``````//Country is a db2 scheme

//Now here is a java Entity bean Method

public List<Province> getStateByName(String stateName) throws Exception {

EntityManager em = this.em;
List<State> states= null;
try {
Query query = em.createNativeQuery("call NGB.getStateByName(?1)", Province.class);
query.setParameter(1, provinceName);
states= (List<Province>) query.getResultList();
} catch (Exception ex) {
throw ex;
}

return states;
}
``````

### Angular 2 Show and Hide an element

When you don't care about removing the Html Dom-Element, use *ngIf.

Otherwise, use this:

``````<div [style.visibility]="(numberOfUnreadAlerts == 0) ? 'hidden' : 'visible' ">
</div>
``````

### Python Traceback (most recent call last)

In Python2, `input` is evaluated, `input()` is equivalent to `eval(raw_input())`. When you enter klj, Python tries to evaluate that name and raises an error because that name is not defined.

Use `raw_input` to get a string from the user in Python2.

Demo 1: `klj` is not defined:

``````>>> input()
klj
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<string>", line 1, in <module>
NameError: name 'klj' is not defined
``````

Demo 2: `klj` is defined:

``````>>> klj = 'hi'
>>> input()
klj
'hi'
``````

Demo 3: getting a string with `raw_input`:

``````>>> raw_input()
klj
'klj'
``````

### Why doesn't the height of a container element increase if it contains floated elements?

You confuse how browsers renders the elements when there are floating elements. If one block element is floating (your inner div in your case), other block elements will ignore it because browser removes floating elements from the normal flow of the web page. Then, because the floated div has been removed from the normal flow, the outside div is filled in, like the inner div isn't there. However, inline elements (images, links, text, blackquotes) will respect the boundaries of the floating element. If you introduce text in the outside div, the text will place arround de inner div.

In other words, block elements (headers, paragraphs, divs, etc) ignore floating elements and fill in, and inline elements (images, links, text, etc) respect boundaries of floating elements.

An fiddle example here

``````<body>
<div style="float:right; background-color:blue;width:200px;min-height:400px;margin-right:20px">
floating element
</div>
<h1 style="background-color:red;"> this is a big header</h1>
<p style="background-color:green"> this is a parragraph with text and a big image. The text places arrounds the floating element. Because of the image is wider than space between paragrah and floating element places down the floating element. Try to make wider the viewport and see what happens :D
<img src="http://2.bp.blogspot.com/_nKxzQGcCLtQ/TBYPAJ6xM4I/AAAAAAAAAC8/lG6XemOXosU/s1600/css.png">
</p>
``````

### Setting default value in select drop-down using Angularjs

You can do it with following code(track by),

``````<select ng-model="modelName" ng-options="data.name for data in list track by data.id" ></select>
``````

### Access a function variable outside the function without using "global"

I've experienced the same problem. One of the responds to your question led me to the following idea (which worked eventually). I use Python 3.7.

``````    # just an example
def func(): # define a function
func.y = 4 # here y is a local variable, which I want to access; func.y defines
# a method for my example function which will allow me to access
# function's local variable y
x = func.y + 8 # this is the main task for the function: what it should do
return x

func() # now I'm calling the function
a = func.y # I put it's local variable into my new variable
print(a) # and print my new variable
``````

Then I launch this program in Windows PowerShell and get the answer 4. Conclusion: to be able to access a local function's variable one might add the name of the function and a dot before the name of the local variable (and then, of course, use this construction for calling the variable both in the function's body and outside of it). I hope this will help.

### Sleep function in C++

Recently I was learning about chrono library and thought of implementing a sleep function on my own. Here is the code,

``````#include <cmath>
#include <chrono>

template <typename rep = std::chrono::seconds::rep,
typename period = std::chrono::seconds::period>
void sleep(std::chrono::duration<rep, period> sec)
{
using sleep_duration = std::chrono::duration<long double, std::nano>;

long double elapsed_time =
std::chrono::duration_cast<sleep_duration>(end - start).count();

long double sleep_time =
std::chrono::duration_cast<sleep_duration>(sec).count();

while (std::isgreater(sleep_time, elapsed_time)) {
elapsed_time = std::chrono::duration_cast<sleep_duration>(end - start).count();
}
}
``````

We can use it with any `std::chrono::duration` type (By default it takes `std::chrono::seconds` as argument). For example,

``````#include <cmath>
#include <chrono>

template <typename rep = std::chrono::seconds::rep,
typename period = std::chrono::seconds::period>
void sleep(std::chrono::duration<rep, period> sec)
{
using sleep_duration = std::chrono::duration<long double, std::nano>;

long double elapsed_time =
std::chrono::duration_cast<sleep_duration>(end - start).count();

long double sleep_time =
std::chrono::duration_cast<sleep_duration>(sec).count();

while (std::isgreater(sleep_time, elapsed_time)) {
elapsed_time = std::chrono::duration_cast<sleep_duration>(end - start).count();
}
}

using namespace std::chrono_literals;
int main (void) {

sleep(5s);  // sleep for 5 seconds

std::cout << std::setprecision(9) << std::fixed;
std::cout << "Elapsed time was: " << std::chrono::duration_cast<std::chrono::seconds>(end1-start1).count() << "s\n";

sleep(500000ns);  // sleep for 500000 nano seconds/500 micro seconds
// same as writing: sleep(500us)

std::cout << "Elapsed time was: " << std::chrono::duration_cast<std::chrono::microseconds>(end2-start2).count() << "us\n";
return 0;
}
``````

For more information, visit https://en.cppreference.com/w/cpp/header/chrono and see this cppcon talk of Howard Hinnant, https://www.youtube.com/watch?v=P32hvk8b13M. He has two more talks on chrono library. And you can always use the library function, `std::this_thread::sleep_for`

Note: Outputs may not be accurate. So, don't expect it to give exact timings.

### How to get the concrete class name as a string?

``````<object>.__class__.__name__
``````

### How to use onClick with divs in React.js

Your box doesn't have a size. If you set the width and height, it works just fine:

_x000D_
_x000D_
``````var Box = React.createClass({_x000D_
getInitialState: function() {_x000D_
return {_x000D_
color: 'black'_x000D_
};_x000D_
},_x000D_
_x000D_
changeColor: function() {_x000D_
var newColor = this.state.color == 'white' ? 'black' : 'white';_x000D_
this.setState({_x000D_
color: newColor_x000D_
});_x000D_
},_x000D_
_x000D_
render: function() {_x000D_
return (_x000D_
<div>_x000D_
<div_x000D_
style = {{_x000D_
background: this.state.color,_x000D_
width: 100,_x000D_
height: 100_x000D_
}}_x000D_
onClick = {this.changeColor}_x000D_
>_x000D_
</div>_x000D_
</div>_x000D_
);_x000D_
}_x000D_
});_x000D_
_x000D_
ReactDOM.render(_x000D_
<Box />,_x000D_
document.getElementById('box')_x000D_
);``````
_x000D_
``````<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>_x000D_
_x000D_
<div id='box'></div>``````
_x000D_
_x000D_
_x000D_

### Jquery change background color

This is how it should be:

Code:

``````\$(function(){
\$("button").mouseover(function(){
var \$p = \$("#P44");
\$p.stop()
.css("background-color","yellow")
.hide(1500, function() {
\$p.css("background-color","red")
.show(1500);
});
});
});
``````

Explanation:

You have to wait for the callback on the animating functions before you switch background color. You should also not use only numeric ID:s, and if you have an ID of your `<p>` there you shouldn't include a class in your selector.

I also enhanced your code (caching of the jQuery object, chaining, etc.)

Update: As suggested by VKolev the color is now changing when the item is hidden.

### How to bind event listener for rendered elements in Angular 2?

If you want to bind an event like 'click' for all the elements having same class in the rendered DOM element then you can set up an event listener by using following parts of the code in components.ts file.

``````import { Component, OnInit, Renderer, ElementRef} from '@angular/core';

constructor( elementRef: ElementRef, renderer: Renderer) {
dragulaService.drop.subscribe((value) => {
this.onDrop(value.slice(1));
});
}

public onDrop(args) {

let [e, el] = args;

this.toggleClassComTitle(e,'checked');

}

public toggleClassComTitle(el: any, name: string) {

el.querySelectorAll('.com-item-title-anchor').forEach( function ( item ) {

console.log("item-clicked");

});
});

}
``````

### Is there an upper bound to BigInteger?

The first maximum you would hit is the length of a String which is 231-1 digits. It's much smaller than the maximum of a BigInteger but IMHO it loses much of its value if it can't be printed.

### Fastest way to determine if an integer's square root is an integer

You'll have to do some benchmarking. The best algorithm will depend on the distribution of your inputs.

Your algorithm may be nearly optimal, but you might want to do a quick check to rule out some possibilities before calling your square root routine. For example, look at the last digit of your number in hex by doing a bit-wise "and." Perfect squares can only end in 0, 1, 4, or 9 in base 16, So for 75% of your inputs (assuming they are uniformly distributed) you can avoid a call to the square root in exchange for some very fast bit twiddling.

Kip benchmarked the following code implementing the hex trick. When testing numbers 1 through 100,000,000, this code ran twice as fast as the original.

``````public final static boolean isPerfectSquare(long n)
{
if (n < 0)
return false;

switch((int)(n & 0xF))
{
case 0: case 1: case 4: case 9:
long tst = (long)Math.sqrt(n);
return tst*tst == n;

default:
return false;
}
}
``````

When I tested the analogous code in C++, it actually ran slower than the original. However, when I eliminated the switch statement, the hex trick once again make the code twice as fast.

``````int isPerfectSquare(int n)
{
int h = n & 0xF;  // h is the last hex "digit"
if (h > 9)
return 0;
// Use lazy evaluation to jump out of the if statement as soon as possible
if (h != 2 && h != 3 && h != 5 && h != 6 && h != 7 && h != 8)
{
int t = (int) floor( sqrt((double) n) + 0.5 );
return t*t == n;
}
return 0;
}
``````

Eliminating the switch statement had little effect on the C# code.

### Using set_facts and with_items together in Ansible

There is a workaround which may help. You may "register" results for each set_fact iteration and then map that results to list:

``````---
- hosts: localhost
- name: set fact
set_fact: foo_item="{{ item }}"
with_items:
- four
- five
- six
register: foo_result

- name: make a list
set_fact: foo="{{ foo_result.results | map(attribute='ansible_facts.foo_item') | list }}"

- debug: var=foo
``````

Output:

``````< TASK: debug var=foo >
---------------------
\   ^__^
\  (oo)\_______
(__)\       )\/\
||----w |
||     ||

ok: [localhost] => {
"var": {
"foo": [
"four",
"five",
"six"
]
}
}
``````

### Html: Difference between cell spacing and cell padding

CellSpacing as the name suggests it is the Space between the Adjacent cells and CellPadding on the other hand means the padding around the cell content.

### Password encryption/decryption code in .NET

One of the simplest methods of encryption (if you absolutely MUST make one up yourself since .NET has such awesome encryption libraries already [as provided by Cogwheel just before me]) is to XOR the ASCII value of each character of the input string against a known "key" value. XOR functionality in C# is accomplished using the ^ key I believe.

Then you can convert the values back from the result of the XOR to ASCII Chars, and store them in the database. This is not highly secure, but it is one of the easiest encryption methods.

Also, if using an access database, I've found that some characters when put in front of a string make the entire field unreadable when opening the database itself. But the field is still readable by your app even though it is blank to a malicious user. But who uses access anymore anyway right?

### bypass invalid SSL certificate in .net core

I solve with this:

Startup.cs

``````public void ConfigureServices(IServiceCollection services)
{
{
ClientCertificateOptions = ClientCertificateOption.Manual,
ServerCertificateCustomValidationCallback =
(httpRequestMessage, cert, cetChain, policyErrors) =>
{
return true;
}
});
``````

YourService.cs

``````public UserService(IHttpClientFactory clientFactory, IOptions<AppSettings> appSettings)
{
_appSettings = appSettings.Value;
_clientFactory = clientFactory;
}

var request = new HttpRequestMessage(...

var client = _clientFactory.CreateClient("HttpClientWithSSLUntrusted");

HttpResponseMessage response = await client.SendAsync(request);
``````

### How to refresh activity after changing language (Locale) inside application

I solved my problem with this code

``````public void setLocale(String lang) {

myLocale = new Locale(lang);
Resources res = getResources();
DisplayMetrics dm = res.getDisplayMetrics();
Configuration conf = res.getConfiguration();
conf.locale = myLocale;
res.updateConfiguration(conf, dm);

onConfigurationChanged(conf);
}

@Override
public void onConfigurationChanged(Configuration newConfig)
{
iv.setImageDrawable(getResources().getDrawable(R.drawable.keyboard));
greet.setText(R.string.greet);
textView1.setText(R.string.langselection);

super.onConfigurationChanged(newConfig);

}
``````

### Pause Console in C++ program

There might be a best way (like using the portable `cin.get()`), but a good way doesn't exist. A program that has done its job should quit and give its resources back to the computer.

And yes, any usage of `system()` leads to unportable code, as the parameter is passed to the shell that owns your process.

Having pausing-code in your source code sooner or later causes hassles:

• someone forgets to delete the pausing code before checking in
• now all working mates have to wonder why the app does not close anymore
• version history is tainted
• `#define` is hell
• it's annoying to anyone who runs your code from the console
• it's very, very, very annoying when trying to start and end your program from within a script; quadly annoying if your program is part of a pipeline in the shell, because if the program does not end, the shell script or pipeline won't, too

Instead, explore your IDE. It probably has an option not to close the console window after running. If not, it's a great justification to you as a developer worth her/his money to always have a console window open nearby.

Alternatively, you can make this a program option, but I personally have never seen a program with an option `--keep-alive-when-dead`.

Moral of the story: This is the user's problem, and not the program's problem. Don't taint your code.

The error means that R could not find the variable mentioned in the error message.

The easiest way to reproduce the error is to type the name of a variable that doesn't exist. (If you've defined `x` already, use a different variable name.)

``````x
``````

The more complex version of the error has the same cause: calling a function when `x` does not exist.

``````mean(x)
## Error in mean(x) :
##   error in evaluating the argument 'x' in selecting a method for function 'mean': Error: object 'x' not found
``````

Once the variable has been defined, the error will not occur.

``````x <- 1:5
x
## [1] 1 2 3 4 5
mean(x)
## [1] 3
``````

You can check to see if a variable exists using `ls` or `exists`.

``````ls()        # lists all the variables that have been defined
exists("x") # returns TRUE or FALSE, depending upon whether x has been defined.
``````

Errors like this can occur when you are using non-standard evaluation. For example, when using `subset`, the error will occur if a column name is not present in the data frame to subset.

``````d <- data.frame(a = rnorm(5))
subset(d, b > 0)
``````

The error can also occur if you use custom evaluation.

``````get("var", "package:stats") #returns the var function
get("var", "package:utils")
``````

In the second case, the `var` function cannot be found when R looks in the `utils` package's environment because `utils` is further down the `search` list than `stats`.

### Create request with POST, which response codes 200 or 201 and content

http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.19

It's just a colon delimited key-value.

ETag: "xyzzy"

It can be any type of text data - I generally include a JSON string with the identifier of the item created. The ease of testing alone makes including it worthwhile.

``````ETag: "{ id: 1234, uri: 'http://domain.com/comments/1234', type: 'comment' }"
``````

In this example, the identifier, the uri, and type of the created item are the "resource characteristics and location".

### Converting an array to a function arguments list

Yes. In current versions of JS you can use:

``````app[func]( ...args );
``````

Users of ES5 and older will need to use the `.apply()` method:

``````app[func].apply( this, args );
``````

Read up on these methods at MDN:

### Split a vector into chunks

``````simplified version...
n = 3
split(x, sort(x%%n))
``````

### How can I get javascript to read from a .json file?

Assuming you mean "file on a local filesystem" when you say .json file.

You'll need to save the json data formatted as jsonp, and use a `file:// url` to access it.

Your HTML will look like this:

``````<script src="file://c:\\data\\activity.jsonp"></script>
<script type="text/javascript">
function updateMe(){
var x = 0;
var activity=jsonstr;
foreach (i in activity) {
date = document.getElementById(i.date).innerHTML = activity.date;
event = document.getElementById(i.event).innerHTML = activity.event;
}
}
</script>
``````

And the file c:\data\activity.jsonp contains the following line:

``````jsonstr = [ {"date":"July 4th", "event":"Independence Day"} ];
``````

### In c, in bool, true == 1 and false == 0?

You neglected to say which version of C you are concerned about. Let's assume it's this one:

http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf

As you can see by reading the specification, the standard definitions of `true` and `false` are 1 and 0, yes.

If your question is about a different version of C, or about non-standard definitions for `true` and `false`, then ask a more specific question.

### How do I launch the Android emulator from the command line?

On Mac (and Linux I think), after you have created your AVD, you can make an alias: `alias run-android='~/Library/Android/sdk/tools/emulator -avd \${YOUR_AVD_NAME} &'`

Note: the execution of the alias will not lock your terminal, if you want that, just remove the last '&'.

Run `emulator` it self will give you an error because he expect that, in your current position, you have: `/emulator/qemu/\${YOUR_PATFORM}/qemu-system-x86_64'` to start the emulator.

### img tag displays wrong orientation

Your image is actually upside down. But it has a meta attribute "Orientation" which tells the viewer it should be the rotated 180 degrees. Some devices/viewers don't obey this rule.

Open it in Chrome: right way up Open it in FF: right way up Open it in IE: upside down

Open it in Paint: Upside down Open it in Photoshop: Right way up. etc.

### SQL SELECT multi-columns INTO multi-variable

``````SELECT @variable1 = col1, @variable2 = col2
FROM table1
``````

### How to count certain elements in array?

Here is a one liner in javascript.

1. Use map. Find the matching values `(v === 2)` in the array, returning an array of ones and zeros.
2. Use Reduce. Add all the values of the array for the total number found.
``````[1, 2, 3, 5, 2, 8, 9, 2]
.map(function(v) {
return v === 2 ? 1 : 0;
})
.reduce((a, b) => a + b, 0);
``````

The result is `3`.

### Conditional WHERE clause in SQL Server

Try this

``````SELECT
DateAppr,
TimeAppr,
TAT,
LaserLTR,
Permit,
LtrPrinter,
JobName,
JobNumber,
JobDesc,
ActQty,
(ActQty-LtrPrinted) AS L,
(ActQty-QtyInserted) AS M,
((ActQty-LtrPrinted)-(ActQty-QtyInserted)) AS N
FROM
[test].[dbo].[MM]
WHERE
DateDropped = 0
AND (
(ISNULL(@JobsOnHold, 0) = 1 AND DateAppr >= 0)
OR
(ISNULL(@JobsOnHold, 0) != 1 AND DateAppr != 0)
)
``````

### Axios handling errors

I tried using the `try{}catch{}` method but it did not work for me. However, when I switched to using `.then(...).catch(...)`, the AxiosError is caught correctly that I can play around with. When I try the former when putting a breakpoint, it does not allow me to see the AxiosError and instead, says to me that the caught error is undefined, which is also what eventually gets displayed in the UI.

Not sure why this happens I find it very trivial. Either way due to this, I suggest using the conventional `.then(...).catch(...)` method mentioned above to avoid throwing undefined errors to the user.

### How to populate HTML dropdown list with values from database

Below code is nice.. It was given by somebody else named aaronbd in this forum

``````<?php

or die ('Cannot connect to db');

\$result = \$conn->query("select id, name from table");

echo "<html>";
echo "<body>";
echo "<select name='id'>";

while (\$row = \$result->fetch_assoc()) {

unset(\$id, \$name);
\$id = \$row['id'];
\$name = \$row['name'];
echo '<option value="'.\$id.'">'.\$name.'</option>';

}

echo "</select>";
echo "</body>";
echo "</html>";
?>
``````

### Creating a blurring overlay view

You can directly make your Background Blur using "Visual Effect View with Blur" and "Visual Effect View with Blur and Vibrancy".

All you have to do for making Blur Background in iOS Application is...

1. Go and search for "Visual Effect View with Blur" in Object Library

Step 1 Image

1. Drag the "Visual Effect View with Blur" in your Storyboard and setup it...

Step 2 Image

1. Finally... You make your App Background Blur!

Application Layout before clicking on any Button!

Application View After Clicking on Button which makes the whole application background Blur!

### Get text from pressed button

Try this,

``````Button btn=(Button)findViewById(R.id.btn);
String btnText=btn.getText();
``````

### What is the difference between a strongly typed language and a statically typed language?

What is the difference between a strongly typed language and a statically typed language?

A statically typed language has a type system that is checked at compile time by the implementation (a compiler or interpreter). The type check rejects some programs, and programs that pass the check usually come with some guarantees; for example, the compiler guarantees not to use integer arithmetic instructions on floating-point numbers.

There is no real agreement on what "strongly typed" means, although the most widely used definition in the professional literature is that in a "strongly typed" language, it is not possible for the programmer to work around the restrictions imposed by the type system. This term is almost always used to describe statically typed languages.

#### Static vs dynamic

The opposite of statically typed is "dynamically typed", which means that

1. Values used at run time are classified into types.
2. There are restrictions on how such values can be used.
3. When those restrictions are violated, the violation is reported as a (dynamic) type error.

For example, Lua, a dynamically typed language, has a string type, a number type, and a Boolean type, among others. In Lua every value belongs to exactly one type, but this is not a requirement for all dynamically typed languages. In Lua, it is permissible to concatenate two strings, but it is not permissible to concatenate a string and a Boolean.

#### Strong vs weak

The opposite of "strongly typed" is "weakly typed", which means you can work around the type system. C is notoriously weakly typed because any pointer type is convertible to any other pointer type simply by casting. Pascal was intended to be strongly typed, but an oversight in the design (untagged variant records) introduced a loophole into the type system, so technically it is weakly typed. Examples of truly strongly typed languages include CLU, Standard ML, and Haskell. Standard ML has in fact undergone several revisions to remove loopholes in the type system that were discovered after the language was widely deployed.

# What's really going on here?

Overall, it turns out to be not that useful to talk about "strong" and "weak". Whether a type system has a loophole is less important than the exact number and nature of the loopholes, how likely they are to come up in practice, and what are the consequences of exploiting a loophole. In practice, it's best to avoid the terms "strong" and "weak" altogether, because

• Amateurs often conflate them with "static" and "dynamic".

• Apparently "weak typing" is used by some persons to talk about the relative prevalance or absence of implicit conversions.

• Professionals can't agree on exactly what the terms mean.

• Overall you are unlikely to inform or enlighten your audience.

The sad truth is that when it comes to type systems, "strong" and "weak" don't have a universally agreed on technical meaning. If you want to discuss the relative strength of type systems, it is better to discuss exactly what guarantees are and are not provided. For example, a good question to ask is this: "is every value of a given type (or class) guaranteed to have been created by calling one of that type's constructors?" In C the answer is no. In CLU, F#, and Haskell it is yes. For C++ I am not sure—I would like to know.

By contrast, static typing means that programs are checked before being executed, and a program might be rejected before it starts. Dynamic typing means that the types of values are checked during execution, and a poorly typed operation might cause the program to halt or otherwise signal an error at run time. A primary reason for static typing is to rule out programs that might have such "dynamic type errors".

Does one imply the other?

On a pedantic level, no, because the word "strong" doesn't really mean anything. But in practice, people almost always do one of two things:

• They (incorrectly) use "strong" and "weak" to mean "static" and "dynamic", in which case they (incorrectly) are using "strongly typed" and "statically typed" interchangeably.

• They use "strong" and "weak" to compare properties of static type systems. It is very rare to hear someone talk about a "strong" or "weak" dynamic type system. Except for FORTH, which doesn't really have any sort of a type system, I can't think of a dynamically typed language where the type system can be subverted. Sort of by definition, those checks are bulit into the execution engine, and every operation gets checked for sanity before being executed.

Either way, if a person calls a language "strongly typed", that person is very likely to be talking about a statically typed language.

### Control cannot fall through from one case label

You need to `break;`, `throw`, `goto`, or `return` from each of your case labels. In a loop you may also `continue`.

``````        switch (searchType)
{
case "SearchBooks":
Selenium.Type("//*[@id='SearchBooks_TextInput']", searchText);
Selenium.Click("//*[@id='SearchBooks_SearchBtn']");
break;

case "SearchAuthors":
Selenium.Type("//*[@id='SearchAuthors_TextInput']", searchText);
Selenium.Click("//*[@id='SearchAuthors_SearchBtn']");
break;
}
``````

The only time this isn't true is when the case labels are stacked like this:

`````` case "SearchBooks": // no code inbetween case labels.
case "SearchAuthors":
// handle both of these cases the same way.
break;
``````

### regex error - nothing to repeat

Beyond the bug that was discovered and fixed, I'll just note that the error message `sre_constants.error: nothing to repeat` is a bit confusing. I was trying to use `r'?.*'` as a pattern, and thought it was complaining for some strange reason about the `*`, but the problem is actually that `?` is a way of saying "repeat zero or one times". So I needed to say `r'\?.*'`to match a literal `?`

### Laravel where on relationship object

[OOT]

A bit OOT, but this question is the most closest topic with my question.

Here is an example if you want to show Event where ALL participant meet certain requirement. Let's say, event where ALL the participant has fully paid. So, it WILL NOT return events which having one or more participants that haven't fully paid .

Simply use the `whereDoesntHave` of the others 2 statuses.

Let's say the statuses are haven't paid at all [eq:1], paid some of it [eq:2], and fully paid [eq:3]

``````Event::whereDoesntHave('participants', function (\$query) {
return \$query->whereRaw('payment = 1 or payment = 2');
})->get();
``````

Tested on Laravel 5.8 - 7.x

### What's the difference between Sender, From and Return-Path?

A minor update to this: a sender should never set the `Return-Path:` header. There's no such thing as a `Return-Path:` header for a message in transit. That header is set by the MTA that makes final delivery, and is generally set to the value of the `5321.From` unless the local system needs some kind of quirky routing.

It's a common misunderstanding because users rarely see an email without a `Return-Path:` header in their mailboxes. This is because they always see delivered messages, but an MTA should never see a `Return-Path:` header on a message in transit. See http://tools.ietf.org/html/rfc5321#section-4.4

### How to save SELECT sql query results in an array in C# Asp.net

A great alternative that hasn't been mentioned is to use the entity framework, which uses an object that is the table - to get data into an array you can do things like:

``````var rows = db.someTable.SqlQuery("SELECT col1,col2 FROM  someTable").ToList().ToArray();
``````

for info on getting started with Entity Framework see https://msdn.microsoft.com/en-us/library/aa937723(v=vs.113).aspx

### How to start jenkins on different port rather than 8080 using command prompt in Windows?

If you have configured jenkins on ec2 instance with linux AMI and looking to change the port. Edit the file at

``````sudo vi /etc/sysconfig/jenkins
``````

Edit

``````JENKINS_PORT="your port number"
``````

Exit vim

``````:wq
``````

Restart jenkins

``````sudo service jenkins restart
``````

Or simply start it, if its not already running

``````sudo service jenkins start
``````

To verify if your jenkins is running on mentioned port

``````netstat -lntu | grep "your port number"
``````

### Could not establish secure channel for SSL/TLS with authority '*'

Yes an Untrusted certificate can cause this. Look at the certificate path for the webservice by opening the websservice in a browser and use the browser tools to look at the certificate path. You may need to install one or more intermediate certificates onto the computer calling the webservice. In the browser you may see "Certificate errors" with an option to "Install Certificate" when you investigate further - this could be the certificate you missing.

My particular problem was a Geotrust Geotrust DV SSL CA intermediate certificate missing following an upgrade to their root server in July 2010 https://knowledge.geotrust.com/support/knowledge-base/index?page=content&id=AR1422

### MySQL LEFT JOIN Multiple Conditions

Just move the extra condition into the JOIN ON criteria, this way the existence of b is not required to return a result

``````SELECT a.* FROM a
LEFT JOIN b ON a.group_id=b.group_id AND b.user_id!=\$_SESSION{['user_id']}
WHERE a.keyword LIKE '%".\$keyword."%'
GROUP BY group_id
``````

### PHP returning JSON to JQUERY AJAX CALL

You can return json in PHP this way:

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

### wait() or sleep() function in jquery?

You can use the `.delay()` function.
This is what you're after:

``````.addClass("load").delay(2000).addClass("done");
``````

### "psql: could not connect to server: Connection refused" Error when connecting to remote database

Following configuration, you need to set:

To open the port 5432 edit your `/etc/postgresql/9.1/main/postgresql.conf` and change

``````# Connection Settings -

``````

In /etc/postgresql/10/main/pg_hba.conf

``````# IPv4 local connections:
host    all             all             0.0.0.0/0           md5
``````

``````sudo service postgresql restart
``````

Now you can connect with

``````psql -h hostname(IP) -p port -U username -d database
``````

You Don't need to close the wrapped reader/writer.

If you've taken a look at the docs (`Reader.close()`,`Writer.close()`), You'll see that in `Reader.close()` it says:

Closes the stream and releases any system resources associated with it.

Which just says that it "releases any system resources associated with it". Even though it doesn't confirm.. it gives you a nudge to start looking deeper. and if you go to `Writer.close()` it only states that it closes itself.

In such cases, we refer to OpenJDK to take a look at the source code.

At BufferedWriter Line 265 you'll see `out.close()`. So it's not closing itself.. It's something else. If you search the class for occurences of "`out`" you'll notice that in the constructor at Line 87 that `out` is the writer the class wraps where it calls another constructor and then assigning `out` parameter to it's own `out` variable..

So.. What about others? You can see similar code at BufferedReader Line 514, BufferedInputStream Line 468 and InputStreamReader Line 199. Others i don't know but this should be enough to assume that they do.

### How to import a csv file using python with headers intact, where first column is a non-numerical

Python's csv module handles data row-wise, which is the usual way of looking at such data. You seem to want a column-wise approach. Here's one way of doing it.

Assuming your file is named `myclone.csv` and contains

``````workers,constant,age
w0,7.334,-1.406
w1,5.235,-4.936
w2,3.2225,-1.478
w3,0,0
``````

this code should give you an idea or two:

``````>>> import csv
>>> f = open('myclone.csv', 'rb')
['workers', 'constant', 'age']
>>> column = {}
...    column[h] = []
...
>>> column
{'workers': [], 'constant': [], 'age': []}
...   for h, v in zip(headers, row):
...     column[h].append(v)
...
>>> column
{'workers': ['w0', 'w1', 'w2', 'w3'], 'constant': ['7.334', '5.235', '3.2225', '0'], 'age': ['-1.406', '-4.936', '-1.478', '0']}
>>> column['workers']
['w0', 'w1', 'w2', 'w3']
>>> column['constant']
['7.334', '5.235', '3.2225', '0']
>>> column['age']
['-1.406', '-4.936', '-1.478', '0']
>>>
``````

``````converters = [str.strip] + [float] * (len(headers) - 1)
``````

up front, and do this

``````for h, v, conv in zip(headers, row, converters):
column[h].append(conv(v))
``````

for each row instead of the similar two lines above.

### Can Powershell Run Commands in Parallel?

You can execute parallel jobs in Powershell 2 using Background Jobs. Check out Start-Job and the other job cmdlets.

``````# Loop through the server list
Get-Content "ServerList.txt" | %{

# Define what each job does
\$ScriptBlock = {
param(\$pipelinePassIn)
Test-Path "\\\$pipelinePassIn\c`\$\Something"
Start-Sleep 60
}

# Execute the jobs in parallel
Start-Job \$ScriptBlock -ArgumentList \$_
}

Get-Job

# Wait for it all to complete
While (Get-Job -State "Running")
{
Start-Sleep 10
}

# Getting the information back from the jobs
``````

### OkHttp Post Body as JSON

Another approach is by using `FormBody.Builder()`.
Here's an example of callback:

``````Callback loginCallback = new Callback() {
@Override
public void onFailure(Call call, IOException e) {
try {
Log.i(TAG, "login failed: " + call.execute().code());
} catch (IOException e1) {
e1.printStackTrace();
}
}

@Override
public void onResponse(Call call, Response response) throws IOException {
try {
JSONObject responseObj = new JSONObject(response.body().string());
Log.i(TAG, "responseObj: " + responseObj);
} catch (JSONException e) {
e.printStackTrace();
}
}
};
``````

Then, we create our own body:

``````RequestBody formBody = new FormBody.Builder()
.build();

OkHttpClient client = new OkHttpClient.Builder()
.build();
Request request = new Request.Builder()
.post(formBody)
.build();
``````

Finally, we call the server:

``````client.newCall(request).enqueue(loginCallback);
``````

### How do I use cascade delete with SQL Server?

Use something like

``````ALTER TABLE T2
FOREIGN KEY (employeeID)
REFERENCES T1 (employeeID)
``````

Fill in the correct column names and you should be set. As mark_s correctly stated, if you have already a foreign key constraint in place, you maybe need to delete the old one first and then create the new one.

### Foreach loop in java for a custom object list

Using can also use Java 8 stream API and do the same thing in one line.

If you want to print any specific property then use this syntax:

``````ArrayList<Room> rooms = new ArrayList<>();
rooms.forEach(room -> System.out.println(room.getName()));
``````

OR

``````ArrayList<Room> rooms = new ArrayList<>();
rooms.forEach(room -> {
// here room is available
});
``````

if you want to print all the properties of Java object then use this:

``````ArrayList<Room> rooms = new ArrayList<>();
rooms.forEach(System.out::println);
``````

### How do I run a Python program?

Navigate your file location just press `Shift` button and click file name. Click tab `Open command window here` and write in your command prompt `python file_name.py`

### What does EntityManager.flush do and why do I need to use it?

The `EntityManager.flush()` operation can be used the write all changes to the database before the transaction is committed. By default JPA does not normally write changes to the database until the transaction is committed. This is normally desirable as it avoids database access, resources and locks until required. It also allows database writes to be ordered, and batched for optimal database access, and to maintain integrity constraints and avoid deadlocks. This means that when you call persist, merge, or remove the database DML `INSERT`, `UPDATE`, `DELETE` is not executed, until commit, or until a flush is triggered.

### How to get build time stamp from Jenkins build variables?

I know its late replying to this question, but I have recently found a better solution to this problem without installing any plugin. We can create a formatted version number and can then use the variable created to display the build date/time. Steps to create: Build Environment --> Create a formatted version number:

• Environment Variable Name: BUILD_DATE

• Version Number Format String: \${BUILD_DATE_FORMATTED}

thats it. Just use the variable created above in the email subject line as \${ENV, var="BUILD_DATE"} and you will get the date/time of the current build.

### How can I find script's directory?

This worked for me (and I found it via the this stackoverflow question)

``````os.path.realpath(__file__)
``````

### Why does JPA have a @Transient annotation?

Because they have different meanings. The `@Transient` annotation tells the JPA provider to not persist any (non-`transient`) attribute. The other tells the serialization framework to not serialize an attribute. You might want to have a `@Transient` property and still serialize it.

### How to connect Robomongo to MongoDB

1. First you have to run the `mongod` command in your terminal. Make sure the command executes properly.

2. Then in a new terminal tab run the `mongo` command.

3. Then open the Robomongo GUI and create a new connection with the default settings.

### Turn on torch/flash on iPhone

See a better answer below: https://stackoverflow.com/a/10054088/308315

First, in your AppDelegate .h file:

``````#import <AVFoundation/AVFoundation.h>

@interface AppDelegate : NSObject <UIApplicationDelegate> {

AVCaptureSession *torchSession;

}

@property (nonatomic, retain) AVCaptureSession * torchSession;

@end
``````

Then in your AppDelegate .m file:

``````@implementation AppDelegate

@synthesize torchSession;

- (void)dealloc {
[torchSession release];

[super dealloc];
}

- (id) init {
if ((self = [super init])) {

// initialize flashlight
// test if this class even exists to ensure flashlight is turned on ONLY for iOS 4 and above
Class captureDeviceClass = NSClassFromString(@"AVCaptureDevice");
if (captureDeviceClass != nil) {

AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

if ([device hasTorch] && [device hasFlash]){

if (device.torchMode == AVCaptureTorchModeOff) {

NSLog(@"Setting up flashlight for later use...");

AVCaptureDeviceInput *flashInput = [AVCaptureDeviceInput deviceInputWithDevice:device error: nil];
AVCaptureVideoDataOutput *output = [[AVCaptureVideoDataOutput alloc] init];

AVCaptureSession *session = [[AVCaptureSession alloc] init];

[session beginConfiguration];
[device lockForConfiguration:nil];

[device unlockForConfiguration];

[output release];

[session commitConfiguration];
[session startRunning];

[self setTorchSession:session];
[session release];
}

}

}
}
return self;
}
``````

Then anytime you want to turn it on, just do something like this:

``````// test if this class even exists to ensure flashlight is turned on ONLY for iOS 4 and above
Class captureDeviceClass = NSClassFromString(@"AVCaptureDevice");
if (captureDeviceClass != nil) {

AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

[device lockForConfiguration:nil];

[device setTorchMode:AVCaptureTorchModeOn];
[device setFlashMode:AVCaptureFlashModeOn];

[device unlockForConfiguration];

}
``````

And similar for turning it off:

``````// test if this class even exists to ensure flashlight is turned on ONLY for iOS 4 and above
Class captureDeviceClass = NSClassFromString(@"AVCaptureDevice");
if (captureDeviceClass != nil) {

AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

[device lockForConfiguration:nil];

[device setTorchMode:AVCaptureTorchModeOff];
[device setFlashMode:AVCaptureFlashModeOff];

[device unlockForConfiguration];
}
``````

### Live search through table rows

Using yckart's answer, I made it to search for the whole table - all td's.

``````\$("#search").keyup(function() {
var value = this.value;

\$("table").find("tr").each(function(index) {
if (index === 0) return;

var if_td_has = false; //boolean value to track if td had the entered key
\$(this).find('td').each(function () {
if_td_has = if_td_has || \$(this).text().indexOf(value) !== -1; //Check if td's text matches key and then use OR to check it for all td's
});

\$(this).toggle(if_td_has);

});
});
``````

### How do I find all files containing specific text on Linux?

Try:

``````find . -name "*.txt" | xargs grep -i "text_pattern"
``````

### php convert datetime to UTC

Do this way:

``````gmdate('Y-m-d H:i:s', \$timestamp)
``````

or simply

``````gmdate('Y-m-d H:i:s')
``````

to get "NOW" in UTC.

Check the reference:

http://www.php.net/manual/en/function.gmdate.php

### How to fill background image of an UIView

For Swift 3.0 use the following code:

``````    UIGraphicsBeginImageContext(self.view.frame.size)
UIImage(named: "bg.png")?.drawAsPattern(in: self.view.bounds)
let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
self.view.backgroundColor = UIColor(patternImage: image)
``````

### What size should apple-touch-icon.png be for iPad and iPhone?

I have been developing and designing iOS apps for a while and This is the best iOS design cheat sheet out there!

have fun :)!

Update: For iOS 8+, and the new devices (iPhone 6, 6 Plus, iPad Air) see this updated link.

Meta update: Iphone 6s/6s Plus have the same resolutions as iPhone 6/6 Plus respectively

This is an image from the new version of the article:

### PDF Parsing Using Python - extracting formatted and plain texts

You can also take a look at PDFMiner (or for older versions of Python see PDFMiner and PDFMiner).

A particular feature of interest in PDFMiner is that you can control how it regroups text parts when extracting them. You do this by specifying the space between lines, words, characters, etc. So, maybe by tweaking this you can achieve what you want (that depends of the variability of your documents). PDFMiner can also give you the location of the text in the page, it can extract data by Object ID and other stuff. So dig in PDFMiner and be creative!

But your problem is really not an easy one to solve because, in a PDF, the text is not continuous, but made from a lot of small groups of characters positioned absolutely in the page. The focus of PDF is to keep the layout intact. It's not content oriented but presentation oriented.

### How to modify WooCommerce cart, checkout pages (main theme portion)

You can use the is_cart() conditional tag:

``````if (! is_cart() ) {
// Do something.
}
``````

### How to set environment variables in Python?

You may need to consider some further aspects for code robustness;

when you're storing an integer-valued variable as an environment variable, try

``````os.environ['DEBUSSY'] = str(myintvariable)
``````

then for retrieval, consider that to avoid errors, you should try

``````os.environ.get('DEBUSSY', 'Not Set')
``````

possibly substitute '-1' for 'Not Set'

so, to put that all together

``````myintvariable = 1
os.environ['DEBUSSY'] = str(myintvariable)
strauss = int(os.environ.get('STRAUSS', '-1'))
# NB KeyError <=> strauss = os.environ['STRAUSS']
debussy = int(os.environ.get('DEBUSSY', '-1'))

print "%s %u, %s %u" % ('Strauss', strauss, 'Debussy', debussy)
``````

### Dump Mongo Collection into JSON format

Here's mine command for reference:

``````mongoexport --db AppDB --collection files --pretty --out output.json
``````

On Windows 7 (MongoDB 3.4), one has to move the cmd to the place where `mongod.exe` and `mongo.exe` file resides => `C:\MongoDB\Server\3.4\bin` else it won't work saying it does not recongnize `mongoexport` command.

### How to redirect a url in NGINX

Similar to another answer here, but change the http in the rewrite to to \$scheme like so:

``````server {
listen 80;
server_name test.com;
rewrite     ^ \$scheme://www.test.com\$request_uri? permanent;
}
``````

And edit your main server block server_name variable as following:

``````server_name  www.test.com;
``````

I had to do this to redirect www.test.com to test.com.

### Angular ReactiveForms: Producing an array of checkbox values?

My solution - solved it for Angular 5 with Material View
The connection is through the

This way it can work for multiple checkboxes arrays in one form. Just set the name of the controls array to connect each time.

_x000D_
_x000D_
``````constructor(_x000D_
private fb: FormBuilder,_x000D_
private http: Http,_x000D_
private codeTableService: CodeTablesService) {_x000D_
_x000D_
})_x000D_
..._x000D_
}_x000D_
_x000D_
_x000D_
createForm() {_x000D_
this.form = this.fb.group({_x000D_
});_x000D_
}_x000D_
_x000D_
ngOnInit() {_x000D_
this.createForm();_x000D_
}_x000D_
_x000D_
updateChkbxArray(id, isChecked, key) {_x000D_
const chkArray = < FormArray > this.form.get(key);_x000D_
if (isChecked) {_x000D_
chkArray.push(new FormControl(id));_x000D_
} else {_x000D_
let idx = chkArray.controls.findIndex(x => x.value == id);_x000D_
chkArray.removeAt(idx);_x000D_
}_x000D_
}``````
_x000D_
``````<div class="col-md-12">_x000D_
<mat-checkbox class="checkbox-margin" (change)="updateChkbxArray(n.id, \$event.checked, 'notification')" value="n.id">{{n.description}}</mat-checkbox>_x000D_
</p>_x000D_
</section>_x000D_
</div>``````
_x000D_
_x000D_
_x000D_

At the end you are getting to save the form with array of original records id's to save/update.

Will be happy to have any remarks for improvement.

### How to redirect single url in nginx?

``````location ~ /issue([0-9]+) {
return 301 http://example.com/shop/issues/custom_isse_name\$1;
}
``````

### JQuery \$.ajax() post - data in a java servlet

You don't want a string, you really want a JS map of key value pairs. E.g., change:

`````` data: myDataVar.toString(),
``````

with:

``````var myKeyVals = { A1984 : 1, A9873 : 5, A1674 : 2, A8724 : 1, A3574 : 3, A1165 : 5 }

var saveData = \$.ajax({
type: 'POST',
url: "someaction.do?action=saveData",
data: myKeyVals,
dataType: "text",
success: function(resultData) { alert("Save Complete") }
});
saveData.error(function() { alert("Something went wrong"); });
``````

jQuery understands key value pairs like that, it does NOT understand a big string. It passes it simply as a string.

UPDATE: Code fixed.

### Spring 3 RequestMapping: Get path value

Non-matched part of the URL is exposed as a request attribute named `HandlerMapping.PATH_WITHIN_HANDLER_MAPPING_ATTRIBUTE`:

``````@RequestMapping("/{id}/**")
public void foo(@PathVariable("id") int id, HttpServletRequest request) {
String restOfTheUrl = (String) request.getAttribute(
HandlerMapping.PATH_WITHIN_HANDLER_MAPPING_ATTRIBUTE);
...
}
``````

### .gitignore file for java eclipse project

You need to add your source files with `git add` or the GUI equivalent so that Git will begin tracking them.

Use `git status` to see what Git thinks about the files in any given directory.

### Specifying colClasses in the read.csv

For multiple datetime columns with no header, and a lot of columns, say my datetime fields are in columns 36 and 38, and I want them read in as character fields:

``````data<-read.csv("test.csv", head=FALSE,   colClasses=c("V36"="character","V38"="character"))
``````

### referenced before assignment error in python

My Scenario

``````def example():
cl = [0, 1]
def inner():
#cl = [1, 2] # access this way will throw `reference before assignment`
cl[0] = 1
cl[1] = 2   # these won't

inner()
``````

### Mysql password expired. Can't connect

You can only write SET PASSWORD = ''; which will set password as blank for root user.

### Adding the "Clear" Button to an iPhone UITextField

``````  func clear_btn(box_is : UITextField){
box_is.clearButtonMode = .always
if let clearButton = box_is.value(forKey: "_clearButton") as? UIButton {
let templateImage =  clearButton.imageView?.image?.withRenderingMode(.alwaysTemplate)

clearButton.setImage(templateImage, for: .normal)
clearButton.setImage(templateImage, for: .highlighted)

clearButton.tintColor = .white

}
}
``````

### How to merge two json string in Python?

You can load both json strings into Python Dictionaries and then combine. This will only work if there are unique keys in each json string.

``````import json

c = dict(a.items() + b.items())
# or c =  dict(a, **b)
``````

### Best way to deploy Visual Studio application that can run without installing

It is possible and is deceptively easy:

1. "Publish" the application (to, say, some folder on drive C), either from menu Build or from the project's properties ? Publish. This will create an installer for a ClickOnce application.
2. But instead of using the produced installer, find the produced files (the EXE file and the .config, .manifest, and .application files, along with any DLL files, etc.) - they are all in the same folder and typically in the `bin\Debug` folder below the project file (.csproj).
3. Zip that folder (leave out any *.vhost.* files and the `app.publish` folder (they are not needed), and the .pdb files unless you foresee debugging directly on your user's system (for example, by remote control)), and provide it to the users.

An added advantage is that, as a ClickOnce application, it does not require administrative privileges to run (if your application follows the normal guidelines for which folders to use for application data, etc.).

As for .NET, you can check for the minimum required version of .NET being installed (or at all) in the application (most users will already have it installed) and present a dialog with a link to the download page on the Microsoft website (or point to one of your pages that could redirect to the Microsoft page - this makes it more robust if the Microsoft URL change). As it is a small utility, you could target .NET 2.0 to reduce the probability of a user to have to install .NET.

It works. We use this method during development and test to avoid having to constantly uninstall and install the application and still being quite close to how the final application will run.

### Compute mean and standard deviation by group for multiple variables in a data.frame

Here's another take on the `data.table` answers, using @Carson's data, that's a bit more readable (and also a little faster, because of using `lapply` instead of `sapply`):

``````library(data.table)
set.seed(1)
dt = data.table(ID=c(1:3), Obs_1=rnorm(9), Obs_2=rnorm(9), Obs_3=rnorm(9))

dt[, c(mean = lapply(.SD, mean), sd = lapply(.SD, sd)), by = ID]
#   ID mean.Obs_1 mean.Obs_2 mean.Obs_3  sd.Obs_1  sd.Obs_2  sd.Obs_3
#1:  1  0.4854187 -0.3238542  0.7410611 1.1108687 0.2885969 0.1067961
#2:  2  0.4171586 -0.2397030  0.2041125 0.2875411 1.8732682 0.3438338
#3:  3 -0.3601052  0.8195368 -0.4087233 0.8105370 0.3829833 1.4705692
``````

### how to make negative numbers into positive

Use `float fabsf (float n)` for `float` values.

Use `double fabs (double n)` for `double` values.

Use `long double fabsl(long double)` for `long double` values.

Use `abs(int)` for `int` values.

### Return value from a VBScript function

To return a value from a VBScript function, assign the value to the name of the function, like this:

``````Function getNumber
getNumber = "423"
End Function
``````

### How do you embed binary data in XML?

Any binary-to-text encoding will do the trick. I use something like that

``````<data encoding="yEnc>
<![CDATA[ encoded binary data ]]>
</data>
``````

### difference between new String[]{} and new String[] in java

`String array=new String[];` and `String array=new String[]{};` both are invalid statement in java.

It will gives you an error that you are trying to assign `String array` to `String` datatype. More specifically error is like this `Type mismatch: cannot convert from String[] to String`

### Calculate time difference in minutes in SQL Server

The following works as expected:

``````SELECT  Diff = CASE DATEDIFF(HOUR, StartTime, EndTime)
WHEN 0 THEN CAST(DATEDIFF(MINUTE, StartTime, EndTime) AS VARCHAR(10))
ELSE CAST(60 - DATEPART(MINUTE, StartTime) AS VARCHAR(10)) +
REPLICATE(',60', DATEDIFF(HOUR, StartTime, EndTime) - 1) +
+ ',' + CAST(DATEPART(MINUTE, EndTime) AS VARCHAR(10))
END
FROM    (VALUES
(CAST('11:15' AS TIME), CAST('13:15' AS TIME)),
(CAST('10:45' AS TIME), CAST('18:59' AS TIME)),
(CAST('10:45' AS TIME), CAST('11:59' AS TIME))
) t (StartTime, EndTime);
``````

To get 24 columns, you could use 24 case expressions, something like:

``````SELECT  [0] = CASE WHEN DATEDIFF(HOUR, StartTime, EndTime) = 0
THEN DATEDIFF(MINUTE, StartTime, EndTime)
ELSE 60 - DATEPART(MINUTE, StartTime)
END,
[1] = CASE WHEN DATEDIFF(HOUR, StartTime, EndTime) = 1
THEN DATEPART(MINUTE, EndTime)
WHEN DATEDIFF(HOUR, StartTime, EndTime) > 1 THEN 60
END,
[2] = CASE WHEN DATEDIFF(HOUR, StartTime, EndTime) = 2
THEN DATEPART(MINUTE, EndTime)
WHEN DATEDIFF(HOUR, StartTime, EndTime) > 2 THEN 60
END -- ETC
FROM    (VALUES
(CAST('11:15' AS TIME), CAST('13:15' AS TIME)),
(CAST('10:45' AS TIME), CAST('18:59' AS TIME)),
(CAST('10:45' AS TIME), CAST('11:59' AS TIME))
) t (StartTime, EndTime);
``````

The following also works, and may end up shorter than repeating the same case expression over and over:

``````WITH Numbers (Number) AS
(   SELECT  ROW_NUMBER() OVER(ORDER BY t1.N) - 1
FROM    (VALUES (1), (1), (1), (1), (1), (1)) AS t1 (N)
CROSS JOIN (VALUES (1), (1), (1), (1)) AS t2 (N)
), YourData AS
(   SELECT  StartTime, EndTime
FROM    (VALUES
(CAST('11:15' AS TIME), CAST('13:15' AS TIME)),
(CAST('09:45' AS TIME), CAST('18:59' AS TIME)),
(CAST('10:45' AS TIME), CAST('11:59' AS TIME))
) AS t (StartTime, EndTime)
), PivotData AS
(   SELECT  t.StartTime,
t.EndTime,
n.Number,
MinuteDiff = CASE WHEN n.Number = 0 AND DATEDIFF(HOUR, StartTime, EndTime) = 0 THEN DATEDIFF(MINUTE, StartTime, EndTime)
WHEN n.Number = 0 THEN 60 - DATEPART(MINUTE, StartTime)
WHEN DATEDIFF(HOUR, t.StartTime, t.EndTime) <= n.Number THEN DATEPART(MINUTE, EndTime)
ELSE 60
END
FROM    YourData AS t
INNER JOIN Numbers AS n
ON n.Number <= DATEDIFF(HOUR, StartTime, EndTime)
)
SELECT  *
FROM    PivotData AS d
PIVOT
(   MAX(MinuteDiff)
FOR Number IN
(   [0], [1], [2], [3], [4], [5],
[6], [7], [8], [9], [10], [11],
[12], [13], [14], [15], [16], [17],
[18], [19], [20], [21], [22], [23]
)
) AS pvt;
``````

It works by joining to a table of 24 numbers, so the case expression doesn't need to be repeated, then rolling these 24 numbers back up into columns using `PIVOT`

### Easy way to turn JavaScript array into comma-separated list?

``````var array = ["Zero", "One", "Two"];
var s = array + [];
console.log(s); // => Zero,One,Two
``````

### How to linebreak an svg text within javascript?

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

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

### Visual studio code CSS indentation and formatting

Go to Files menu -> Preference -> Extentions Then type CSS Formatter wait for it to load and click install

### Bulk Insert Correctly Quoted CSV File in SQL Server

I've spent half a day on this problem. It's best to import using SQL Server Import & Export data wizard. There is a setting in that wizard which solves this problem. Detailed screenshots here: https://www.mssqltips.com/sqlservertip/1316/strip-double-quotes-from-an-import-file-in-integration-services-ssis/ Thanks

### yum error "Cannot retrieve metalink for repository: epel. Please verify its path and try again" updating ContextBroker

In my case when I comment out mirrorlist the error got away but the repo was also not working so I manually point the right baseurl in `/etc/yum.repos.d/epel.repo` as below

``````[epel]
name=Extra Packages for Enterprise Linux 7 - \$basearch
failovermethod=priority
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7

[epel-debuginfo]
name=Extra Packages for Enterprise Linux 7 - \$basearch - Debug
failovermethod=priority
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7
gpgcheck=1

[epel-source]
name=Extra Packages for Enterprise Linux 7 - \$basearch - Source
failovermethod=priority
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7
gpgcheck=1

``````

### Backbone.js fetch with parameters

``````try {
// THIS for POST+JSON
options.contentType = 'application/json';
options.type = 'POST';
options.data = JSON.stringify(options.data);

// OR THIS for GET+URL-encoded
//options.data = \$.param(_.clone(options.data));

console.log('.fetch options = ', options);
collection.fetch(options);
} catch (excp) {
}
``````

### Convert.ToDateTime: how to set format

``````    string test = "01-12-12";
try{
DateTime dateTime = DateTime.Parse(test);
test = dateTime.ToString("dd/yyyy");
}
catch (FormatException exc)
{
MessageBox.Show(exc.Message);
}
``````

Where test will be equal to "12/2012"

Hope it helps!

### req.query and req.param in ExpressJS

Passing params

``````GET request to "/cars/honda"
``````

returns a list of Honda car models

Passing query

``````GET request to "/car/honda?color=blue"
``````

returns a list of Honda car models, but filtered so only models with an stock color of blue are returned.

It doesn't make sense to add those filters into the URL parameters (/car/honda/color/blue) because according to REST, that would imply that we want to get a bunch of information about the color "blue". Since what we really want is a filtered list of Honda models, we use query strings to filter down the results that get returned.

Notice that the query strings are really just { key: value } pairs in a slightly different format: ?key1=value1&key2=value2&key3=value3.

### What's a good way to extend Error in JavaScript?

I would take a step back and consider why you want to do that? I think the point is to deal with different errors differently.

For example, in Python, you can restrict the catch statement to only catch `MyValidationError`, and perhaps you want to be able to do something similar in javascript.

``````catch (MyValidationError e) {
....
}
``````

You can't do this in javascript. There's only going to be one catch block. You're supposed to use an if statement on the error to determine its type.

``` catch(e) { if(isMyValidationError(e)) { ... } else { // maybe rethrow? throw e; } } ```

I think I would instead throw a raw object with a type, message, and any other properties you see fit.

``````throw { type: "validation", message: "Invalid timestamp" }
``````

And when you catch the error:

``````catch(e) {
if(e.type === "validation") {
// handle error
}
// re-throw, or whatever else
}
``````

### How to cancel a pull request on github?

Go to conversation tab then come down there is one "close pull request" button is there use that button to close pull request, Take ref of attached image

### How to change menu item text dynamically in Android

I needed to change the menu icon for the fragment. I altered Charles’s answer to this question a bit for the fragment:

``````    private Menu top_menu;

//...
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

//...
rootview = inflater.inflate(R.layout.first_content,null);
}

@Override
}

// my procedure
nav_undo.setIcon( R.drawable.back);
}
}
``````

### How to define custom exception class in Java, the easiest way?

Reason for this is explained in the Inheritance article of the Java Platform which says:

"A subclass inherits all the members (fields, methods, and nested classes) from its superclass. Constructors are not members, so they are not inherited by subclasses, but the constructor of the superclass can be invoked from the subclass."

### Directory.GetFiles of certain extension

If you would like to do your filtering in LINQ, you can do it like this:

``````var ext = new List<string> { "jpg", "gif", "png" };
var myFiles = Directory
.EnumerateFiles(dir, "*.*", SearchOption.AllDirectories)
.Where(s => ext.Contains(Path.GetExtension(s).TrimStart(".").ToLowerInvariant()));
``````

Now `ext` contains a list of allowed extensions; you can add or remove items from it as necessary for flexible filtering.