Programs & Examples On #Precision

For questions related to numerical precision in programming.

How to convert milliseconds to seconds with precision

Surely you just need:

double seconds = milliseconds / 1000.0;

There's no need to manually do the two parts separately - you just need floating point arithmetic, which the use of 1000.0 (as a double literal) forces. (I'm assuming your milliseconds value is an integer of some form.)

Note that as usual with double, you may not be able to represent the result exactly. Consider using BigDecimal if you want to represent 100ms as 0.1 seconds exactly. (Given that it's a physical quantity, and the 100ms wouldn't be exact in the first place, a double is probably appropriate, but...)

Show two digits after decimal point in c++

It is possible to print a 15 decimal number in C++ using the following:

#include <iomanip>
#include <iostream>

cout << fixed << setprecision(15) << " The Real_Pi is: " << real_pi << endl;
cout << fixed << setprecision(15) << " My Result_Pi is: " << my_pi << endl;
cout << fixed << setprecision(15) << " Processing error is: " << Error_of_Computing << endl;
cout << fixed << setprecision(15) << " Processing time is: " << End_Time-Start_Time << endl;

return 0;

decimal vs double! - Which one should I use and when?

I think that the main difference beside bit width is that decimal has exponent base 10 and double has 2

Double precision floating values in Python?

Decimal datatype

  • Unlike hardware based binary floating point, the decimal module has a user alterable precision (defaulting to 28 places) which can be as large as needed for a given problem.

If you are pressed by performance issuses, have a look at GMPY

Controlling number of decimal digits in print output in R

One more solution able to control the how many decimal digits to print out based on needs (if you don't want to print redundant zero(s))

For example, if you have a vector as elements and would like to get sum of it

elements <- c(-1e-05, -2e-04, -3e-03, -4e-02, -5e-01, -6e+00, -7e+01, -8e+02)
## -876.5432

Apparently, the last digital as 1 been truncated, the ideal result should be -876.54321, but if set as fixed printing decimal option, e.g sprintf("%.10f", sum(elements)), redundant zero(s) generate as -876.5432100000

Following the tutorial here: printing decimal numbers, if able to identify how many decimal digits in the certain numeric number, like here in -876.54321, there are 5 decimal digits need to print, then we can set up a parameter for format function as below:

decimal_length <- 5
formatC(sum(elements), format = "f", digits = decimal_length)
## -876.54321

We can change the decimal_length based on each time query, so it can satisfy different decimal printing requirement.

Dividing two integers to produce a float result

Cast the operands to floats:

float ans = (float)a / (float)b;

Double precision - decimal places

An IEEE double has 53 significant bits (that's the value of DBL_MANT_DIG in <cfloat>). That's approximately 15.95 decimal digits (log10(253)); the implementation sets DBL_DIG to 15, not 16, because it has to round down. So you have nearly an extra decimal digit of precision (beyond what's implied by DBL_DIG==15) because of that.

The nextafter() function computes the nearest representable number to a given number; it can be used to show just how precise a given number is.

This program:

#include <cstdio>
#include <cfloat>
#include <cmath>

int main() {
    double x = 1.0/7.0;
    printf("FLT_RADIX = %d\n", FLT_RADIX);
    printf("DBL_DIG = %d\n", DBL_DIG);
    printf("DBL_MANT_DIG = %d\n", DBL_MANT_DIG);
    printf("%.17g\n%.17g\n%.17g\n", nextafter(x, 0.0), x, nextafter(x, 1.0));

gives me this output on my system:

DBL_DIG = 15

(You can replace %.17g by, say, %.64g to see more digits, none of which are significant.)

As you can see, the last displayed decimal digit changes by 3 with each consecutive value. The fact that the last displayed digit of 1.0/7.0 (5) happens to match the mathematical value is largely coincidental; it was a lucky guess. And the correct rounded digit is 6, not 5. Replacing 1.0/7.0 by 1.0/3.0 gives this output:

DBL_DIG = 15

which shows about 16 decimal digits of precision, as you'd expect.

What is the difference between float and double?

Floats have less precision than doubles. Although you already know, read What WE Should Know About Floating-Point Arithmetic for better understanding.

How do I print a double value with full precision using cout?

Here is how to display a double with full precision:

double d = 100.0000000000005;
int precision = std::numeric_limits<double>::max_digits10;
std::cout << std::setprecision(precision) << d << std::endl;

This displays:


max_digits10 is the number of digits that are necessary to uniquely represent all distinct double values. max_digits10 represents the number of digits before and after the decimal point.

Don't use set_precision(max_digits10) with std::fixed.
On fixed notation, set_precision() sets the number of digits only after the decimal point. This is incorrect as max_digits10 represents the number of digits before and after the decimal point.

double d = 100.0000000000005;
int precision = std::numeric_limits<double>::max_digits10;
std::cout << std::fixed << std::setprecision(precision) << d << std::endl;

This displays incorrect result:


Note: Header files required

#include <iomanip>
#include <limits>

Changing precision of numeric column in Oracle

If the table is compressed this will work:

alter table EVAPP_FEES add AMOUNT_TEMP NUMBER(14,2);


update EVAPP_FEES set AMOUNT = null;

alter table EVAPP_FEES modify AMOUNT NUMBER(14,2);


alter table EVAPP_FEES move nocompress;

alter table EVAPP_FEES drop column AMOUNT_TEMP;

alter table EVAPP_FEES compress;

How do I interpret precision and scale of a number in a database?

Precision of a number is the number of digits.

Scale of a number is the number of digits after the decimal point.

What is generally implied when setting precision and scale on field definition is that they represent maximum values.

Example, a decimal field defined with precision=5 and scale=2 would allow the following values:

  • 123.45 (p=5,s=2)
  • 12.34 (p=4,s=2)
  • 12345 (p=5,s=0)
  • 123.4 (p=4,s=1)
  • 0 (p=0,s=0)

The following values are not allowed or would cause a data loss:

  • 12.345 (p=5,s=3) => could be truncated into 12.35 (p=4,s=2)
  • 1234.56 (p=6,s=2) => could be truncated into 1234.6 (p=5,s=1)
  • 123.456 (p=6,s=3) => could be truncated into 123.46 (p=5,s=2)
  • 123450 (p=6,s=0) => out of range

Note that the range is generally defined by the precision: |value| < 10^p ...

Get DateTime.Now with milliseconds precision

I was looking for a similar solution, base on what was suggested on this thread, I use the following DateTime.Now.ToString("MM/dd/yyyy hh:mm:ss.fff") , and it work like charm. Note: that .fff are the precision numbers that you wish to capture.

Limiting floats to two decimal points

In Python 2.7:

a = 13.949999999999999
output = float("%0.2f"%a)
print output

How do you round a double in Dart to a given degree of precision AFTER the decimal point?

Above solutions do not work for all cases. What worked for my problem was this solution that will round your number (0.5 to 1 or 0.49 to 0) and leave it without any decimals:

Input: 12.67

double myDouble = 12.67;
var myRoundedNumber; // Note the 'var' datatype

// Here I used 1 decimal. You can use another value in toStringAsFixed(x)
myRoundedNumber = double.parse((myDouble).toStringAsFixed(1));
myRoundedNumber = myRoundedNumber.round();


Output: 13

This link has other solutions too

What's the difference between a single precision and double precision floating point operation?

I read a lot of answers but none seems to correctly explain where the word double comes from. I remember a very good explanation given by a University professor I had some years ago.

Recalling the style of VonC's answer, a single precision floating point representation uses a word of 32 bit.

  • 1 bit for the sign, S
  • 8 bits for the exponent, 'E'
  • 24 bits for the fraction, also called mantissa, or coefficient (even though just 23 are represented). Let's call it 'M' (for mantissa, I prefer this name as "fraction" can be misunderstood).


bits:    31 30      23 22                     0

(Just to point out, the sign bit is the last, not the first.)

A double precision floating point representation uses a word of 64 bit.

  • 1 bit for the sign, S
  • 11 bits for the exponent, 'E'
  • 53 bits for the fraction / mantissa / coefficient (even though only 52 are represented), 'M'


bits:     63 62         52 51                                                  0

As you may notice, I wrote that the mantissa has, in both types, one bit more of information compared to its representation. In fact, the mantissa is a number represented without all its non-significative 0. For example,

  • 0.000124 becomes 0.124 × 10-3
  • 237.141 becomes 0.237141 × 103

This means that the mantissa will always be in the form × ßp

where ß is the base of representation. But since the fraction is a binary number, a1 will always be equal to 1, thus the fraction can be rewritten as × 2p and the initial 1 can be implicitly assumed, making room for an extra bit (at+1).

Now, it's obviously true that the double of 32 is 64, but that's not where the word comes from.

The precision indicates the number of decimal digits that are correct, i.e. without any kind of representation error or approximation. In other words, it indicates how many decimal digits one can safely use.

With that said, it's easy to estimate the number of decimal digits which can be safely used:

  • single precision: log10(224), which is about 7~8 decimal digits
  • double precision: log10(253), which is about 15~16 decimal digits

JavaScript displaying a float to 2 decimal places

number.parseFloat(2) works but it returns a string.

If you'd like to preserve it as a number type you can use:

Math.round(number * 100) / 100

Retain precision with double in Java

Do not waste your efford using BigDecimal. In 99.99999% cases you don't need it. java double type is of cource approximate but in almost all cases, it is sufficiently precise. Mind that your have an error at 14th significant digit. This is really negligible!

To get nice output use:

System.out.printf("%.2f\n", total);

Eloquent - where not equal to

Use where with a != operator in combination with whereNull

Code::where('to_be_used_by_user_id', '!=' , 2)->orWhereNull('to_be_used_by_user_id')->get()

How to stop line breaking in vim

I like that the long lines are displayed over more than one terminal line

This sort of visual/virtual line wrapping is enabled with the wrap window option:

set wrap

I don’t like that vim inserts newlines into my actual text.

To turn off physical line wrapping, clear both the textwidth and wrapmargin buffer options:

set textwidth=0 wrapmargin=0

Correct modification of state arrays in React.js

I am trying to push value in an array state and set value like this and define state array and push value by map function.

 this.state = {
        createJob: [],
    } => {
                this.setState({totalAmount:this.state.totalAmount += _.your_API_JSON.price})
                this.state.createJob.push({ id: _._id, price: _.your_API_JSON.price })
                return this.setState({createJob: this.state.createJob})

Catching multiple exception types in one catch block

Another option not listed here is to use the code attribute of an exception, so you can do something like this:

try {

    if (1 === $foo) {

         throw new Exception(sprintf('Invalid foo: %s', serialize($foo)), 1);

    if (2 === $bar) {
        throw new Exception(sprintf('Invalid bar: %s', serialize($foo)), 2);
} catch (Exception $e) {

    switch ($e->getCode()) {

        case 1:
            // Special handling for case 1

        case 2:
            // Special handling for case 2


            // Special handling for all other cases

Create an ArrayList of unique values

If you want to make a list with unique values from an existing list you can use

List myUniqueList =;

C#: Waiting for all threads to complete

This may not be an option for you, but if you can use the Parallel Extension for .NET then you could use Tasks instead of raw threads and then use Task.WaitAll() to wait for them to complete.

The FastCGI process exited unexpectedly

maybe you should try installing VC++ runtime as explained here.

There's a fairly good chance you're missing the correct VC++ runtime for the version of PHP you're running.

If you're running PHP 5.5.x you need to ensure the VC++11 runtime is installed:

Make sure you download and install the x86 version (vcredist_x86.exe), PHP on Windows isn't 64 bit yet.

If you're running PHP 5.4.x then you need to install the VC++9 runtime:

SqlServer: Login failed for user

I ran into the same issue, and I fixed it by adding my windows username to SQL and then to my server, here is how I did:

First, create a new login with your Windows username: enter image description here

Click Search, then type your name in the box and click check names. enter image description here

Then add your that user to the server:

Right click on the Server > Permissions > Search > Browse > Select your user (You will notice that now the user you created is available in the list)

enter image description here

I hope it helps ;-)

CSS On hover show another element

we just can show same label div on hovering like this

#b {
    display: none;

    display: block;


javax.mail.AuthenticationFailedException: failed to connect, no password specified?

I've solved this issue adding user and password in Transport.send call:

Transport.send(msg, "user", "password");

According to this signature of the send function in javax.mail (from version 1.5):

public static void send(Message msg, String user, String password)

Also, if you use this signature it's not necessary to set up any Authenticator, and to set user and password in the Properties (only the host is needed). So your code could be:

private void sendMail(){
      Properties prop = System.getProperties();
      prop.put("", "yourHost");
      Session session = Session.getInstance(prop);
      Message msg = #createYourMsg(session, from, to, subject, mailer, yatta yatta...)#;
      Transport.send(msg, "user", "password");
  }catch(Exception exc) {
      // Deal with it! :)

What is `related_name` used for in Django?

The related name parameter is actually an option. If we do not set it, Django automatically creates the other side of the relation for us. In the case of the Map model, Django would have created a map_set attribute, allowing access via m.map_set in your example(m being your class instance). The formula Django uses is the name of the model followed by the string _set. The related name parameter thus simply overrides Django’s default rather than providing new behavior.

Subset and ggplot2

There's another solution that I find useful, especially when I want to plot multiple subsets of the same object:

myplot<-ggplot(df)+geom_line(aes(Value1, Value2, group=ID, colour=ID))
myplot %+% subset(df, ID %in% c("P1","P3"))
myplot %+% subset(df, ID %in% c("P2"))

How to terminate the script in JavaScript?

If you don't care that it's an error just write:


That will stop your main (global) code from proceeding. Useful for some aspects of debugging/testing.

PHP date add 5 year to current date

Using Carbon:

$dt = Carbon::now();
echo $dt->addYears(5); 

Add common prefix to all cells in Excel

Select the cell you want to be like this, go to cell properties (or CTRL 1) under Number tab in custom enter "X"@

Put a space between " and @ if needed

Rotate label text in seaborn factorplot

You can also use plt.setp as follows:

import matplotlib.pyplot as plt
import seaborn as sns

plot=sns.barplot(data=df,  x=" ", y=" ")
plt.setp(plot.get_xticklabels(), rotation=90)

to rotate the labels 90 degrees.

In Javascript, how to conditionally add a member to an object?

var a = {
    ...(condition ? {b: 1} : '') // if condition is true 'b' will be added.

I hope this is the much efficient way to add an entry based on the condition. For more info on how to conditionally add entries inside an object literals.

MySQL Check if username and password matches in Database

Instead of selecting all the columns in count count(*) you can limit count for one column count(UserName).

You can limit the whole search to one row by using Limit 0,1

  FROM TableName
 WHERE UserName = 'User' AND
       Password = 'Pass'
 LIMIT 0, 1

Spring Boot - inject map from application.yml

I run into the same problem today, but unfortunately Andy's solution didn't work for me. In Spring Boot 1.2.1.RELEASE it's even easier, but you have to be aware of a few things.

Here is the interesting part from my application.yml:

     api: org.scribe.builder.api.Google2Api
     key: api_key
     secret: api_secret

providers map contains only one map entry, my goal is to provide dynamic configuration for other OAuth providers. I want to inject this map into a service that will initialize services based on the configuration provided in this yaml file. My initial implementation was:

@ConfigurationProperties(prefix = 'oauth')
class OAuth2ProvidersService implements InitializingBean {

    private Map<String, Map<String, String>> providers = [:]

    void afterPropertiesSet() throws Exception {

    private void initialize() {

After starting the application, providers map in OAuth2ProvidersService was not initialized. I tried the solution suggested by Andy, but it didn't work as well. I use Groovy in that application, so I decided to remove private and let Groovy generates getter and setter. So my code looked like this:

@ConfigurationProperties(prefix = 'oauth')
class OAuth2ProvidersService implements InitializingBean {

    Map<String, Map<String, String>> providers = [:]

    void afterPropertiesSet() throws Exception {

    private void initialize() {

After that small change everything worked.

Although there is one thing that might be worth mentioning. After I make it working I decided to make this field private and provide setter with straight argument type in the setter method. Unfortunately it wont work that. It causes org.springframework.beans.NotWritablePropertyException with message:

Invalid property 'providers[google]' of bean class [com.zinvoice.user.service.OAuth2ProvidersService]: Cannot access indexed value in property referenced in indexed property path 'providers[google]'; nested exception is org.springframework.beans.NotReadablePropertyException: Invalid property 'providers[google]' of bean class [com.zinvoice.user.service.OAuth2ProvidersService]: Bean property 'providers[google]' is not readable or has an invalid getter method: Does the return type of the getter match the parameter type of the setter?

Keep it in mind if you're using Groovy in your Spring Boot application.

Remove characters from C# string

Its a powerful method I usually use in the same case:

private string Normalize(string text)
        return string.Join("",
            from ch in text
            where char.IsLetterOrDigit(ch) || char.IsWhiteSpace(ch)
            select ch);


React-router: How to manually invoke Link?

again this is JS :) this still works ....

var linkToClick = document.getElementById('something');;

<Link id="something" to={/somewhaere}> the link </Link>

'module' object has no attribute 'DataFrame'

The most likely explanation is that either a file called '' is in the same directory as your script, or that another variable called 'pd' is used in your program.

Regex to accept alphanumeric and some special character in Javascript?

I forgot to mention. This should also accept whitespace.

You could use:


Note how this makes use of the character classes \w and \s.

EDIT:- Added \ to escape /

href overrides ng-click in Angular.js

This example from the angular documentation site just does href without even assigning it to an empty string:

[<a href ng-click="colors.splice($index, 1)">X</a>]

Windows Task Scheduler doesn't start batch file task

Make sure you set the 'Start in' and 'Program/script' options correctly. If your file address is: C:\Temp\foo.bat, set the 'start in' option to 'C:\Temp' and the 'Program/script' option to 'foo.bat'.

To set the 'Start in' option: Right click task in the task scheduler > Properties > Actions > Edit.

If this alone doesn't work then try moving the .bat file to a directory with basic permissions (maybe a shared directory for example).

I had a problem where my .bat file was located in a folder with some restrictive permissions on it, so that only my user account could access it. Even though I had set up the task scheduler to use my credentials it still failed. Moving the .bat file to another directory sorted the issue.

Adding and removing style attribute from div with jquery

Remove style attribute from div using J query:


Add style to div using J query:

$("#TableDiv").attr("style", "display: none;");

Add style using html:

<div class="row" id="TableDiv" style="display: none;">

Hope it will helpful :)

How to change the background color of the options menu?

protected void setMenuBackground() {
    getLayoutInflater().setFactory(new Factory() {
        public View onCreateView (String name, Context context, AttributeSet attrs) {
            if (name.equalsIgnoreCase("")) {
                try {
                    // Ask our inflater to create the view
                    LayoutInflater f = getLayoutInflater();
                    final View view = f.createView(name, null, attrs);
                    // Kind of apply our own background
                    new Handler().post( new Runnable() {
                        public void run () {
                    return view;
                catch (InflateException e) {
                catch (ClassNotFoundException e) {
            return null;

this is XML file


Generate an integer that is not among four billion given ones

Why make it so complicated? You ask for an integer not present in the file?

According to the rules specified, the only thing you need to store is the largest integer that you encountered so far in the file. Once the entire file has been read, return a number 1 greater than that.

There is no risk of hitting maxint or anything, because according to the rules, there is no restriction to the size of the integer or the number returned by the algorithm.

How to use split?

According to MDN, the split() method divides a String into an ordered set of substrings, puts these substrings into an array, and returns the array.


var str = 'Hello my friend'

var split1 = str.split(' ') // ["Hello", "my", "friend"]
var split2 = str.split('') // ["H", "e", "l", "l", "o", " ", "m", "y", " ", "f", "r", "i", "e", "n", "d"]

In your case

var str = 'something -- something_else'
var splitArr = str.split(' -- ') // ["something", "something_else"]

console.log(splitArr[0]) // something
console.log(splitArr[1]) // something_else

Tar archiving that takes input from a list of files

Assuming GNU tar (as this is Linux), the -T or --files-from option is what you want.

When and where to use GetType() or typeof()?

typeof is an operator to obtain a type known at compile-time (or at least a generic type parameter). The operand of typeof is always the name of a type or type parameter - never an expression with a value (e.g. a variable). See the C# language specification for more details.

GetType() is a method you call on individual objects, to get the execution-time type of the object.

Note that unless you only want exactly instances of TextBox (rather than instances of subclasses) you'd usually use:

if (myControl is TextBox)
    // Whatever


TextBox tb = myControl as TextBox;
if (tb != null)
    // Use tb

HTTP Error 500.19 and error code : 0x80070021

Check if IIS server installed the URL rewrite feature.
If it is not installed then make sure your web.config file don't have the URL rewrite related configuration

<!-- Make sure don't have below config, if server have not installed url rewrite feature. -->
    <rule name="Fail bad requests">
      <match url=".*"/> ...

Some time we copied the config from legacy server and straight away deploy to brand new server, then we may encounter such kind of 500 issue.

Datatables on-the-fly resizing

$(document).ready(function() {
    $('a[data-toggle="tab"]').on( '', function (e) {
        // var target = $("href"); // activated tab
        // alert (target);
        $($.fn.dataTable.tables( true ) ).css('width', '100%');
        $($.fn.dataTable.tables( true ) ).DataTable().columns.adjust().draw();
    } ); 

It works for me, with "autoWidth": false,

How to downgrade the installed version of 'pip' on windows?

pip itself is just a normal python package. Thus you can install pip with pip.

Of cource, you don't want to affect the system's pip, install it inside a virtualenv.

pip install pip==1.2.1

Change default text in input type="file"?

Here is how its done with bootstrap, only u should put the original input somewhere...idk in head and delete the < br > if you have it, because its only hidden and its taking space anyway :)

 <head> _x000D_
 <link rel="stylesheet" href="" integrity="sha384-Vkoo8x4CGsO3+Hhxv8T/Q5PaXtkKtu6ug5TOeNV6gBiFeWPGFN9MuhOf23Q9Ifjh" crossorigin="anonymous">_x000D_
 <label for="file" button type="file" name="image" class="btn btn-secondary">Secondary</button> </label>_x000D_
 <input type="file" id="file" name="image" value="Prebrskaj" style="visibility:hidden;">_x000D_
 <script src="" integrity="sha384-J6qa4849blE2+poT4WnyKhv5vZF5SrPo0iEjwBvKU7imGFAV0wwj1yYfoRSJoZ+n" crossorigin="anonymous"></script>_x000D_
<script src="[email protected]/dist/umd/popper.min.js" integrity="sha384-Q6E9RHvbIyZFJoft+2mJbHaEWldlvI9IOYy5n3zV9zzTtmI3UksdQRVvoxMfooAo" crossorigin="anonymous"></script>_x000D_
<script src="" integrity="sha384-wfSDF2E50Y2D1uUdj0O3uMBJnjuUD4Ih7YwaYd1iqfktj0Uod8GCExl3Og8ifwB6" crossorigin="anonymous"></script>_x000D_

How to make html <select> element look like "disabled", but pass values?

You can keep it disabled as desired, and then remove the disabled attribute before the form is submitted.

$('#myForm').submit(function() {

Note that if you rely on this method, you'll want to disable it programmatically as well, because if JS is disabled or not supported, you'll be stuck with the disabled select.

$(document).ready(function() {
    $('select').attr('disabled', 'disabled');

Algorithm: efficient way to remove duplicate integers from an array

Insert all the elements in a binary tree the disregards duplicates - O(nlog(n)). Then extract all of them back in the array by doing a traversal - O(n). I am assuming that you don't need order preservation.

Show Hide div if, if statement is true

Use show/hide method as below

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

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

How to find the port for MS SQL Server 2008?

Here are 5 methodes i found:

  • Method 1: SQL Server Configuration Manager
  • Method 2: Windows Event Viewer
  • Method 3: SQL Server Error Logs
  • Method 4: sys.dm_exec_connections DMV
  • Method 5: Reading registry using xp_instance_regread

Method 4: sys.dm_exec_connections DMV
I think this is almost the easiest way...
DMVs return server state that can be used to monitor SQL Server Instance. We can use sys.dm_exec_connections DMV to identify the port number SQL Server Instance is listening on using below T-SQL code:

SELECT local_tcp_port
FROM   sys.dm_exec_connections
WHERE  session_id = @@SPID

Result Set:

(1 row(s) affected)

Method 1: SQL Server Configuration Manager

Step 1. Click Start > All Programs > Microsoft SQL Server 2012 > Configuration Tools > SQL Server Configuration Manager

Step 2. Go to SQL Server Configuration Manager > SQL Server Network Configuration > Protocols for

Step 3. Right Click on TCP/IP and select Properties

enter image description here

Step 4. In TCP/IP Properties dialog box, go to IP Addresses tab and scroll down to IPAll group.

enter image description here

If SQL Server if configured to run on a static port it will be available in TCP Port textbox, and if it is configured on dynamic port then current port will be available in TCP Dynamic Ports textbox. Here my instance is listening on port number 61499.

The other methods you can find here:

Android getText from EditText field

You can simply get the text in editText by applying below code:

EditText editText=(EditText)findViewById(;
String text=editText.getText().toString();

then you can toast string text!

Happy coding!

Why does the Google Play store say my Android app is incompatible with my own device?

Permissions that Imply Feature Requirements

example, the android.hardware.bluetooth feature was added in Android 2.2 (API level 8), but the bluetooth API that it refers to was added in Android 2.0 (API level 5). Because of this, some apps were able to use the API before they had the ability to declare that they require the API via the system.

To prevent those apps from being made available unintentionally, Google Play assumes that certain hardware-related permissions indicate that the underlying hardware features are required by default. For instance, applications that use Bluetooth must request the BLUETOOTH permission in a element — for legacy apps, Google Play assumes that the permission declaration means that the underlying android.hardware.bluetooth feature is required by the application and sets up filtering based on that feature.

The table below lists permissions that imply feature requirements equivalent to those declared in elements. Note that declarations, including any declared android:required attribute, always take precedence over features implied by the permissions below.

For any of the permissions below, you can disable filtering based on the implied feature by explicitly declaring the implied feature explicitly, in a element, with an android:required="false" attribute. For example, to disable any filtering based on the CAMERA permission, you would add this declaration to the manifest file:

<uses-feature android:name="" android:required="false" />

<uses-feature android:name="android.hardware.bluetooth" android:required="false" />
<uses-feature android:name="android.hardware.location" android:required="false" />
<uses-feature android:name="android.hardware.location.gps" android:required="false" />
<uses-feature android:name="android.hardware.telephony" android:required="false" />
<uses-feature android:name="android.hardware.wifi" android:required="false" />

adb devices command not working

Please note that IDEs like IntelliJ IDEA tend to start their own adb-server.

Even manually killing the server and running an new instance with sudo won't help here until you make your IDE kill the server itself.

parse html string with jquery

I'm not a 100% sure, but won't


produce a jquery object with a DOM for that data, not connected anywhere? Or if it's already parsed as a DOM, you could just go $("#myImg", data), or whatever selector suits your needs.

Rereading your question it appears your 'data' is already a DOM, which means you could just go (assuming there's only an img in your DOM, otherwise you'll need a more precise selector)

$("img", data).attr ("src")

if you want to access the src-attribute. If your data is just text, it would probably work to do

$("img", $(data)).attr ("src")

Has anyone gotten HTML emails working with Twitter Bootstrap?

Emails require tables in order to work properly.

Inky (by foundation for emails) is a templating language that converts simple HTML tags into the complex table HTML required for emails.




  <table align="center" class="container">
          <table class="row">
                <th class="small-12 large-12 columns first last">
                        <th>Put content in me!</th>
                        <th class="expander"></th>


Will produce this:

enter image description here

How to save .xlsx data to file as a blob

Here's my implementation using the fetch api. The server endpoint sends a stream of bytes and the client receives a byte array and creates a blob out of it. A .xlsx file will then be generated.

return fetch(fullUrlEndpoint, options)
  .then((res) => {
    if (!res.ok) {
      const responseStatusText = res.statusText
      const errorMessage = `${responseStatusText}`
      throw new Error(errorMessage);
    return res.arrayBuffer();
    .then((ab) => {
      // BE endpoint sends a readable stream of bytes
      const byteArray = new Uint8Array(ab);
      const a = window.document.createElement('a');
      a.href = window.URL.createObjectURL(
        new Blob([byteArray], {
      ); = `${fileName}.XLSX`;
    .catch(error => {
      throw new Error('Error occurred:' + error);

What's a quick way to comment/uncomment lines in Vim?

Starting with the ideas in answers here, I started my own comment function. It toggles comments on and off. It can handle things like //print('blue'); //this thing is blue and just toggles the first comment. Furthermore it adds comments and a single space just where the first non whitespace is and not at the very start of the line. Aditionally it doesn't unnecessarily copy the whitespaces, but uses zooms (:h \zs for help) to avoid this extra work, when commenting and indented line. Hope it helps some minimalists out there. Suggestions are welcome.

" these lines are needed for ToggleComment()
autocmd FileType c,cpp,java      let b:comment_leader = '//'
autocmd FileType arduino         let b:comment_leader = '//'
autocmd FileType sh,ruby,python  let b:comment_leader = '#'
autocmd FileType zsh             let b:comment_leader = '#'
autocmd FileType conf,fstab      let b:comment_leader = '#'
autocmd FileType matlab,tex      let b:comment_leader = '%'
autocmd FileType vim             let b:comment_leader = '"'

" l:pos   --> cursor position
" l:space --> how many spaces we will use b:comment_leader + ' '

function! ToggleComment()
    if exists('b:comment_leader')
        let l:pos = col('.')
        let l:space = ( &ft =~ '\v(c|cpp|java|arduino)' ? '3' : '2' )
        if getline('.') =~ '\v(\s*|\t*)' .b:comment_leader
            let l:space -= ( getline('.') =~ '\v.*\zs' . b:comment_leader . '(\s+|\t+)@!' ?  1 : 0 )
            execute 'silent s,\v^(\s*|\t*)\zs' .b:comment_leader.'[ ]?,,g'
            let l:pos -= l:space
            exec 'normal! 0i' .b:comment_leader .' '
            let l:pos += l:space
        call cursor(line("."), l:pos)
        echo 'no comment leader found for filetype'

nnoremap <Leader>t :call ToggleComment()<CR>
inoremap <Leader>t <C-o>:call ToggleComment()<CR>
xnoremap <Leader>t :'<,'>call ToggleComment()<CR>

XAMPP Start automatically on Windows 7 startup

Try to run Your XAMPP Control Panel as Run as administrator, then install Apache and MySQL.

enter image description here

When XAMPP opens, ensure that Apache and MySQL services are stopped.

enter image description here

Now just check/tick on Apache and Mysql service module.

enter image description here

Now Apache and MySQL will be added to window services. You can set these services to start when Windows boots.

iptables block access to port 8000 except from IP address

You can always use iptables to delete the rules. If you have a lot of rules, just output them using the following command.

iptables-save > myfile

vi to edit them from the commend line. Just use the "dd" to delete the lines you no longer want.

iptables-restore < myfile and you're good to go.  


Android Completely transparent Status Bar?

I found the answer while I investigating this library:

so you need to add following codes to your activity

    window.statusBarColor = Color.TRANSPARENT
} else {

How to crop an image in OpenCV using Python

It's very simple. Use numpy slicing.

import cv2
img = cv2.imread("lenna.png")
crop_img = img[y:y+h, x:x+w]
cv2.imshow("cropped", crop_img)

Separation of business logic and data access in django

It seems like you are asking about the difference between the data model and the domain model – the latter is where you can find the business logic and entities as perceived by your end user, the former is where you actually store your data.

Furthermore, I've interpreted the 3rd part of your question as: how to notice failure to keep these models separate.

These are two very different concepts and it's always hard to keep them separate. However, there are some common patterns and tools that can be used for this purpose.

About the Domain Model

The first thing you need to recognize is that your domain model is not really about data; it is about actions and questions such as "activate this user", "deactivate this user", "which users are currently activated?", and "what is this user's name?". In classical terms: it's about queries and commands.

Thinking in Commands

Let's start by looking at the commands in your example: "activate this user" and "deactivate this user". The nice thing about commands is that they can easily be expressed by small given-when-then scenario's:

given an inactive user
when the admin activates this user
then the user becomes active
and a confirmation e-mail is sent to the user
and an entry is added to the system log
(etc. etc.)

Such scenario's are useful to see how different parts of your infrastructure can be affected by a single command – in this case your database (some kind of 'active' flag), your mail server, your system log, etc.

Such scenario's also really help you in setting up a Test Driven Development environment.

And finally, thinking in commands really helps you create a task-oriented application. Your users will appreciate this :-)

Expressing Commands

Django provides two easy ways of expressing commands; they are both valid options and it is not unusual to mix the two approaches.

The service layer

The service module has already been described by @Hedde. Here you define a separate module and each command is represented as a function.

def activate_user(user_id):
    user = User.objects.get(pk=user_id)

    # set active flag = True

    # mail user

    # etc etc

Using forms

The other way is to use a Django Form for each command. I prefer this approach, because it combines multiple closely related aspects:

  • execution of the command (what does it do?)
  • validation of the command parameters (can it do this?)
  • presentation of the command (how can I do this?)

class ActivateUserForm(forms.Form):

    user_id = IntegerField(widget = UsernameSelectWidget, verbose_name="Select a user to activate")
    # the username select widget is not a standard Django widget, I just made it up

    def clean_user_id(self):
        user_id = self.cleaned_data['user_id']
        if User.objects.get(pk=user_id).active:
            raise ValidationError("This user cannot be activated")
        # you can also check authorizations etc. 
        return user_id

    def execute(self):
        This is not a standard method in the forms API; it is intended to replace the 
        'extract-data-from-form-in-view-and-do-stuff' pattern by a more testable pattern. 
        user_id = self.cleaned_data['user_id']

        user = User.objects.get(pk=user_id)

        # set active flag = True

        # mail user

        # etc etc

Thinking in Queries

You example did not contain any queries, so I took the liberty of making up a few useful queries. I prefer to use the term "question", but queries is the classical terminology. Interesting queries are: "What is the name of this user?", "Can this user log in?", "Show me a list of deactivated users", and "What is the geographical distribution of deactivated users?"

Before embarking on answering these queries, you should always ask yourself this question, is this:

  • a presentational query just for my templates, and/or
  • a business logic query tied to executing my commands, and/or
  • a reporting query.

Presentational queries are merely made to improve the user interface. The answers to business logic queries directly affect the execution of your commands. Reporting queries are merely for analytical purposes and have looser time constraints. These categories are not mutually exclusive.

The other question is: "do I have complete control over the answers?" For example, when querying the user's name (in this context) we do not have any control over the outcome, because we rely on an external API.

Making Queries

The most basic query in Django is the use of the Manager object:


Of course, this only works if the data is actually represented in your data model. This is not always the case. In those cases, you can consider the options below.

Custom tags and filters

The first alternative is useful for queries that are merely presentational: custom tags and template filters.


<h1>Welcome, {{ user|friendly_name }}</h1>

def friendly_name(user):
    return remote_api.get_cached_name(

Query methods

If your query is not merely presentational, you could add queries to your (if you are using that), or introduce a module:

def inactive_users():
    return User.objects.filter(active=False)

def users_called_publysher():
    for user in User.objects.all():
        if remote_api.get_cached_name( == "publysher":
            yield user 

Proxy models

Proxy models are very useful in the context of business logic and reporting. You basically define an enhanced subset of your model. You can override a Manager’s base QuerySet by overriding the Manager.get_queryset() method.

class InactiveUserManager(models.Manager):
    def get_queryset(self):
        query_set = super(InactiveUserManager, self).get_queryset()
        return query_set.filter(active=False)

class InactiveUser(User):
    >>> for user in InactiveUser.objects.all():
    …        assert is False 

    objects = InactiveUserManager()
    class Meta:
        proxy = True

Query models

For queries that are inherently complex, but are executed quite often, there is the possibility of query models. A query model is a form of denormalization where relevant data for a single query is stored in a separate model. The trick of course is to keep the denormalized model in sync with the primary model. Query models can only be used if changes are entirely under your control.

class InactiveUserDistribution(models.Model):
    country = CharField(max_length=200)
    inactive_user_count = IntegerField(default=0)

The first option is to update these models in your commands. This is very useful if these models are only changed by one or two commands.

class ActivateUserForm(forms.Form):
    # see above
    def execute(self):
        # see above
        query_model = InactiveUserDistribution.objects.get_or_create(
        query_model.inactive_user_count -= 1

A better option would be to use custom signals. These signals are of course emitted by your commands. Signals have the advantage that you can keep multiple query models in sync with your original model. Furthermore, signal processing can be offloaded to background tasks, using Celery or similar frameworks.

user_activated = Signal(providing_args = ['user'])
user_deactivated = Signal(providing_args = ['user'])

class ActivateUserForm(forms.Form):
    # see above
    def execute(self):
        # see above
        user_activated.send_robust(sender=self, user=user)

class InactiveUserDistribution(models.Model):
    # see above

def on_user_activated(sender, **kwargs):
        user = kwargs['user']
        query_model = InactiveUserDistribution.objects.get_or_create(
        query_model.inactive_user_count -= 1

Keeping it clean

When using this approach, it becomes ridiculously easy to determine if your code stays clean. Just follow these guidelines:

  • Does my model contain methods that do more than managing database state? You should extract a command.
  • Does my model contain properties that do not map to database fields? You should extract a query.
  • Does my model reference infrastructure that is not my database (such as mail)? You should extract a command.

The same goes for views (because views often suffer from the same problem).

  • Does my view actively manage database models? You should extract a command.

Some References

Django documentation: proxy models

Django documentation: signals

Architecture: Domain Driven Design

Unable to launch the IIS Express Web server, Failed to register URL, Access is denied

Got the same issue where IIS express complained about http://localhost:50418/ and none of above solutions worked for me..

Went to projektFolder --> .vs --> config --> applicationhost.xml

In the tag <sites> I found that my web app had two bindnings registered.

<site name="myApp.Web" id="2">
    <application path="/" applicationPool="Clr4IntegratedAppPool">
        <virtualDirectory path="/" physicalPath="C:\git\myApp\myApp.Web" />
        <binding protocol="https" bindingInformation="*:44332:localhost" />
        <binding protocol="http" bindingInformation="*:50418:localhost" />

Removing the binding pointing to *:50418:localhost solved the issue.

Using VS2017 and IISExpress v10.

Angular 2 Hover event

For handling the event on overing, you can try something like this (it works for me):

In the Html template:

<div (mouseenter)="onHovering($event)" (mouseleave)="onUnovering($event)">
  <img src="../../../contents/ctm-icons/alarm.svg" class="centering-me" alt="Alerts" />

In the angular component:

    onHovering(eventObject) {
    var regExp = new RegExp(".svg" + "$");

    var srcObj =["0"];
    if (srcObj.tagName == "IMG") {
        srcObj.setAttribute("src", srcObj.getAttribute("src").replace(regExp, "_h.svg"));       

   onUnovering(eventObject) {
    var regExp = new RegExp("_h.svg" + "$");

    var srcObj =["0"];
    if (srcObj.tagName == "IMG") {
        srcObj.setAttribute("src", srcObj.getAttribute("src").replace(regExp, ".svg"));

How to select records without duplicate on just one field in SQL?

Ignore duplicate rows in SQL. I think this may help you.

    SELECT res2.*
    (select * from [dbo].[tbl_countries])as res1
    )as res2
    WHERE res2.num=1

Introducing FOREIGN KEY constraint may cause cycles or multiple cascade paths - why?

I was getting this error for lots of entities when I was migrating down from an EF7 model to an EF6 version. I didn't want to have to go through each entity one at a time, so I used:


Change user-agent for Selenium web-driver

There is no way in Selenium to read the request or response headers. You could do it by instructing your browser to connect through a proxy that records this kind of information.

Setting the User Agent in Firefox

The usual way to change the user agent for Firefox is to set the variable "general.useragent.override" in your Firefox profile. Note that this is independent from Selenium.

You can direct Selenium to use a profile different from the default one, like this:

from selenium import webdriver
profile = webdriver.FirefoxProfile()
profile.set_preference("general.useragent.override", "whatever you want")
driver = webdriver.Firefox(profile)

Setting the User Agent in Chrome

With Chrome, what you want to do is use the user-agent command line option. Again, this is not a Selenium thing. You can invoke Chrome at the command line with chrome --user-agent=foo to set the agent to the value foo.

With Selenium you set it like this:

from selenium import webdriver
from import Options
opts = Options()
opts.add_argument("user-agent=whatever you want")

driver = webdriver.Chrome(chrome_options=opts)

Both methods above were tested and found to work. I don't know about other browsers.

Getting the User Agent

Selenium does not have methods to query the user agent from an instance of WebDriver. Even in the case of Firefox, you cannot discover the default user agent by checking what general.useragent.override would be if not set to a custom value. (This setting does not exist before it is set to some value.)

Once the browser is started, however, you can get the user agent by executing:

agent = driver.execute_script("return navigator.userAgent")

The agent variable will contain the user agent.

Change action bar color in android

ActionBar bar = getActionBar();
bar.setBackgroundDrawable(new ColorDrawable("COLOR")); 

it worked for me here

What's the fastest way to read a text file line-by-line?

There's a good topic about this in Stack Overflow question Is 'yield return' slower than "old school" return?.

It says:

ReadAllLines loads all of the lines into memory and returns a string[]. All well and good if the file is small. If the file is larger than will fit in memory, you'll run out of memory.

ReadLines, on the other hand, uses yield return to return one line at a time. With it, you can read any size file. It doesn't load the whole file into memory.

Say you wanted to find the first line that contains the word "foo", and then exit. Using ReadAllLines, you'd have to read the entire file into memory, even if "foo" occurs on the first line. With ReadLines, you only read one line. Which one would be faster?

How to install APK from PC?

Just connect the device to the PC with a USB cable, then copy the .apk file to the device. On the device, touch the APK file in the file explorer to install it.

You could also offer the .apk on your website. People can download it, then touch it to install.

How do I get the first n characters of a string without checking the size or going out of bounds?

Don't reinvent the wheel...:

org.apache.commons.lang.StringUtils.substring(String s, int start, int len)

Javadoc says:

StringUtils.substring(null, *, *)    = null
StringUtils.substring("", * ,  *)    = "";
StringUtils.substring("abc", 0, 2)   = "ab"
StringUtils.substring("abc", 2, 0)   = ""
StringUtils.substring("abc", 2, 4)   = "c"
StringUtils.substring("abc", 4, 6)   = ""
StringUtils.substring("abc", 2, 2)   = ""
StringUtils.substring("abc", -2, -1) = "b"
StringUtils.substring("abc", -4, 2)  = "ab"


StringUtils.substring("abc", 0, 4) = "abc"

HTTP 404 when accessing .svc file in IIS

Verifies that you directory has been converted into an Application is your IIS.

How to make a select with array contains value clause in psql


SELECT * FROM table WHERE arr @> ARRAY['s']::varchar[]

How to make the 'cut' command treat same sequental delimiters as one?

shortest/friendliest solution

After becoming frustrated with the too many limitations of cut, I wrote my own replacement, which I called cuts for "cut on steroids".

cuts provides what is likely the most minimalist solution to this and many other related cut/paste problems.

One example, out of many, addressing this particular question:

$ cat text.txt
0   1        2 3
0 1          2   3 4

$ cuts 2 text.txt

cuts supports:

  • auto-detection of most common field-delimiters in files (+ ability to override defaults)
  • multi-char, mixed-char, and regex matched delimiters
  • extracting columns from multiple files with mixed delimiters
  • offsets from end of line (using negative numbers) in addition to start of line
  • automatic side-by-side pasting of columns (no need to invoke paste separately)
  • support for field reordering
  • a config file where users can change their personal preferences
  • great emphasis on user friendliness & minimalist required typing

and much more. None of which is provided by standard cut.

See also:

Source and documentation (free software):

RecyclerView: Inconsistency detected. Invalid item position

I had the same issue with recyclerView So i just notified the adapter about data set change right after the list cleared.



Android camera intent

I found a pretty simple way to do this. Use a button to open it using an on click listener to start the function openc(), like this:

String fileloc;
private void openc()
    Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    File f = null;
        f = File.createTempFile("temppic",".jpg",getApplicationContext().getCacheDir());
        if (takePictureIntent.resolveActivity(getPackageManager()) != null)
            takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT,FileProvider.getUriForFile(profile.this, BuildConfig.APPLICATION_ID+".provider",f));
            fileloc = Uri.fromFile(f)+"";
            Log.d("texts", "openc: "+fileloc);
            startActivityForResult(takePictureIntent, 3);
    catch (IOException e) 

protected void onActivityResult(int requestCode, int resultCode, Intent data) 
    super.onActivityResult(requestCode, resultCode, data);
    if(requestCode == 3 && resultCode == RESULT_OK) {
        Log.d("texts", "onActivityResult: "+fileloc);
        // fileloc is the uri of the file so do whatever with it

You can do whatever you want with the uri location string. For instance, I send it to an image cropper to crop the image.

What's the best way to parse command line arguments?

I extended Erco's approach to allow for required positional arguments and for optional arguments. These should precede the -d, -v etc. arguments.

Positional and optional arguments can be retrieved with PosArg(i) and OptArg(i, default) respectively. When an optional argument is found the start position of searching for options (e.g. -i) is moved 1 ahead to avoid causing an 'unexpected' fatal.

import os,sys

def HelpAndExit():
    print("<<your help output goes here>>")

def Fatal(msg):
    sys.stderr.write("%s: %s\n" % (os.path.basename(sys.argv[0]), msg))

def NextArg(i):
    '''Return the next command line argument (if there is one)'''
    if ((i+1) >= len(sys.argv)):
        Fatal("'%s' expected an argument" % sys.argv[i])
    return(1, sys.argv[i+1])

def PosArg(i):
    '''Return positional argument'''
    if i >= len(sys.argv):
        Fatal("'%s' expected an argument" % sys.argv[i])
    return sys.argv[i]

def OptArg(i, default):
    '''Return optional argument (if there is one)'''
    if i >= len(sys.argv):
        Fatal("'%s' expected an argument" % sys.argv[i])
    if sys.argv[i][:1] != '-':
        return True, sys.argv[i]
        return False, default

### MAIN
if __name__=='__main__':

    verbose = 0
    debug   = 0
    infile  = "infile"
    outfile = "outfile"
    options_start = 3

    # --- Parse two positional parameters ---
    n1 = int(PosArg(1))
    n2 = int(PosArg(2))

    # --- Parse an optional parameters ---
    present, a3 = OptArg(3,50)
    n3 = int(a3)
    options_start += int(present)

    # --- Parse rest of command line ---
    skip = 0
    for i in range(options_start, len(sys.argv)):
        if not skip:
            if   sys.argv[i][:2] == "-d": debug ^= 1
            elif sys.argv[i][:2] == "-v": verbose ^= 1
            elif sys.argv[i][:2] == "-i": (skip,infile)  = NextArg(i)
            elif sys.argv[i][:2] == "-o": (skip,outfile) = NextArg(i)
            elif sys.argv[i][:2] == "-h": HelpAndExit()
            elif sys.argv[i][:1] == "-":  Fatal("'%s' unknown argument" % sys.argv[i])
            else:                         Fatal("'%s' unexpected" % sys.argv[i])
        else: skip = 0

    print("Number 1 = %d" % n1)
    print("Number 2 = %d" % n2)
    print("Number 3 = %d" % n3)
    print("Debug    = %d" % debug)
    print("verbose  = %d" % verbose)
    print("infile   = %s" % infile)
    print("outfile  = %s" % outfile) 

How to Copy Contents of One Canvas to Another Canvas Locally

@robert-hurst has a cleaner approach.

However, this solution may also be used, in places when you actually want to have a copy of Data Url after copying. For example, when you are building a website that uses lots of image/canvas operations.

    // select canvas elements
    var sourceCanvas = document.getElementById("some-unique-id");
    var destCanvas = document.getElementsByClassName("some-class-selector")[0];

    //copy canvas by DataUrl
    var sourceImageData = sourceCanvas.toDataURL("image/png");
    var destCanvasContext = destCanvas.getContext('2d');

    var destinationImage = new Image;
    destinationImage.onload = function(){
    destinationImage.src = sourceImageData;

How to read a file into a variable in shell?

With bash you may use read like tis:

#!/usr/bin/env bash

{ IFS= read -rd '' value <config.txt;} 2>/dev/null

printf '%s' "$value"

Notice that:

  • The last newline is preserved.

  • The stderr is silenced to /dev/null by redirecting the whole commands block, but the return status of the read command is preserved, if one needed to handle read error conditions.

File name without extension name VBA

You could always use Replace() since you're performing this on the workbook's Name, which will almost certainly end with .xlsm by virtue of using VBA.

Using ActiveWorkbook per your example:

Replace(Application.ActiveWorkbook.Name, ".xlsm", "")

Using ThisWorkbook:

Replace(Application.ThisWorkbook.Name, ".xlsm", "")

How can I use JSON data to populate the options of a select box?

Why not just make the server return the names?

["Woodland Hills", "none", "Los Angeles", "Laguna Hills"]

Then create the <option> elements using JavaScript.

    data: 'q=' + str,
    dataType: 'json',
    success: function( json ) {
        $.each(json, function(i, value) {
            $('#myselect').append($('<option>').text(value).attr('value', value));

React Native Error: ENOSPC: System limit for number of file watchers reached

I encountered this issue on a linuxmint distro. It appeared to have happened when there was so many folders and subfolders/files I added to the /public folder in my app. I applied this fix and it worked well...

$ echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf

change directory into the /etc folder: cd /etc

then run this: sudo systcl -p

You may have to close your terminal and npm start again to get it to work.

If this fails i recommend installing react-scripts globally and running your application directly with that.

$ npm i -g --save react-scripts

then instead of npm start run react-scripts start to run your application.

Can I escape a double quote in a verbatim string literal?

Use a duplicated double quote.

@"this ""word"" is escaped";


this "word" is escaped

Maven command to determine which settings.xml file Maven is using

You can use the maven help plugin to tell you the contents of your user and global settings files.

mvn help:effective-settings

will ask maven to spit out the combined global and user settings.

MySQL case sensitive query

To improve James' excellent answer:

It's better to put BINARY in front of the constant instead:

SELECT * FROM `table` WHERE `column` = BINARY 'value'

Putting BINARY in front of column will prevent the use of any index on that column.

How to completely remove borders from HTML table

Using TinyMCE editor, the only way I was able to remove all borders was to use border:hidden in the style like this:

table, tr {border:hidden;}
td, th {border:hidden;}

And in the HTML like this:

<table style="border:hidden;"</table>


How to watch and compile all TypeScript sources?

The tsc compiler will only watch those files that you pass on the command line. It will not watch files that are included using a /// <sourcefile> reference. If your working with the bash, you could use find to recursively find all *.ts files and compile them:

find . -name "*.ts" | xargs tsc -w

How to support HTTP OPTIONS verb in ASP.NET MVC/WebAPI application

After encountering the same issue in a Web API 2 project (and being unable to use the standard CORS packages for reasons not worth going into here), I was able to resolve this by implementing a custom DelagatingHandler:

public class AllowOptionsHandler : DelegatingHandler
    protected override async Task<HttpResponseMessage> SendAsync(
        HttpRequestMessage request, CancellationToken cancellationToken)
        var response = await base.SendAsync(request, cancellationToken);

        if (request.Method == HttpMethod.Options &&
            response.StatusCode == HttpStatusCode.MethodNotAllowed)
            response = new HttpResponseMessage(HttpStatusCode.OK);

        return response;

For the Web API configuration:

config.MessageHandlers.Add(new AllowOptionsHandler());

Note that I also have the CORS headers enabled in Web.config, similar to some of the other answers posted here:

  <modules runAllManagedModulesForAllRequests="true">
    <remove name="WebDAVModule" />

      <add name="Access-Control-Allow-Origin" value="*" />
      <add name="Access-Control-Allow-Headers" value="accept, cache-control, content-type, authorization" />
      <add name="Access-Control-Allow-Methods" value="GET, POST, PUT, DELETE, OPTIONS" />

    <remove name="ExtensionlessUrlHandler-Integrated-4.0" />
    <remove name="TRACEVerbHandler" />
    <add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />

Note that my project does not include MVC, only Web API 2.

Differences between time complexity and space complexity?

There is a well know relation between time and space complexity.

First of all, time is an obvious bound to space consumption: in time t you cannot reach more than O(t) memory cells. This is usually expressed by the inclusion

                            DTime(f) ? DSpace(f)

where DTime(f) and DSpace(f) are the set of languages recognizable by a deterministic Turing machine in time (respectively, space) O(f). That is to say that if a problem can be solved in time O(f), then it can also be solved in space O(f).

Less evident is the fact that space provides a bound to time. Suppose that, on an input of size n, you have at your disposal f(n) memory cells, comprising registers, caches and everything. After having written these cells in all possible ways you may eventually stop your computation, since otherwise you would reenter a configuration you already went through, starting to loop. Now, on a binary alphabet, f(n) cells can be written in 2^f(n) different ways, that gives our time upper bound: either the computation will stop within this bound, or you may force termination, since the computation will never stop.

This is usually expressed in the inclusion

                          DSpace(f) ? Dtime(2^(cf))

for some constant c. the reason of the constant c is that if L is in DSpace(f) you only know that it will be recognized in Space O(f), while in the previous reasoning, f was an actual bound.

The above relations are subsumed by stronger versions, involving nondeterministic models of computation, that is the way they are frequently stated in textbooks (see e.g. Theorem 7.4 in Computational Complexity by Papadimitriou).

What is the difference between Amazon SNS and Amazon SQS?

You can see SNS as a traditional topic which you can have multiple Subscribers. You can have heterogeneous subscribers for one given SNS topic, including Lambda and SQS, for example. You can also send SMS messages or even e-mails out of the box using SNS. One thing to consider in SNS is only one message (notification) is received at once, so you cannot take advantage from batching.

SQS, on the other hand, is nothing but a queue, where you store messages and subscribe one consumer (yes, you can have N consumers to one SQS queue, but it would get messy very quickly and way harder to manage considering all consumers would need to read the message at least once, so one is better off with SNS combined with SQS for this use case, where SNS would push notifications to N SQS queues and every queue would have one subscriber, only) to process these messages. As of Jun 28, 2018, AWS Supports Lambda Triggers for SQS, meaning you don't have to poll for messages any more.

Furthermore, you can configure a DLQ on your source SQS queue to send messages to in case of failure. In case of success, messages are automatically deleted (this is another great improvement), so you don't have to worry about the already processed messages being read again in case you forgot to delete them manually. I suggest taking a look at Lambda Retry Behaviour to better understand how it works.

One great benefit of using SQS is that it enables batch processing. Each batch can contain up to 10 messages, so if 100 messages arrive at once in your SQS queue, then 10 Lambda functions will spin up (considering the default auto-scaling behaviour for Lambda) and they'll process these 100 messages (keep in mind this is the happy path as in practice, a few more Lambda functions could spin up reading less than the 10 messages in the batch, but you get the idea). If you posted these same 100 messages to SNS, however, 100 Lambda functions would spin up, unnecessarily increasing costs and using up your Lambda concurrency.

However, if you are still running traditional servers (like EC2 instances), you will still need to poll for messages and manage them manually.

You also have FIFO SQS queues, which guarantee the delivery order of the messages. SQS FIFO is also supported as an event source for Lambda as of November 2019

Even though there's some overlap in their use cases, both SQS and SNS have their own spotlight.

Use SNS if:

  • multiple subscribers is a requirement
  • sending SMS/E-mail out of the box is handy

Use SQS if:

  • only one subscriber is needed
  • batching is important

Versioning SQL Server database

We just started using Team Foundation Server. If your database is medium sized, then visual studio has some nice project integrations with built in compare, data compare, database refactoring tools, database testing framework, and even data generation tools.

But, that model doesn't fit very large or third party databases (that encrypt objects) very well. So, what we've done is to store only our customized objects. Visual Studio / Team foundation server works very well for that.

TFS Database chief arch. blog

MS TFS site

How to downgrade tensorflow, multiple versions possible?

Click to green checkbox on installed tensorflow and choose needed versionscreenshot Anaconda navigator

SSIS package creating Hresult: 0x80004005 Description: "Login timeout expired" error

I had a similar error..This might be due to two reasons. a) If you have used variables, re-evaluate the expressions in which variables are used and make sure the expression is evaluated without errors. b) If you are deleting the excel sheet and creating excel sheet on the fly in your package.

MVC4 Passing model from view to controller

I hope this complete example will help you.

This is the TaxiInfo class which holds information about a taxi ride:

namespace Taxi.Models
    public class TaxiInfo
        public String Driver { get; set; }
        public Double Fare { get; set; }
        public Double Distance { get; set; }
        public String StartLocation { get; set; }
        public String EndLocation { get; set; }

We also have a convenience model which holds a List of TaxiInfo(s):

namespace Taxi.Models
    public class TaxiInfoSet
        public List<TaxiInfo> TaxiInfoList { get; set; }

        public TaxiInfoSet(params TaxiInfo[] TaxiInfos)
            TaxiInfoList = new List<TaxiInfo>();

            foreach(var TaxiInfo in TaxiInfos)

Now in the home controller we have the default Index action which for this example makes two taxi drivers and adds them to the list contained in a TaxiInfo:

public ActionResult Index()
    var taxi1 = new TaxiInfo() { Fare = 20.2, Distance = 15, Driver = "Billy", StartLocation = "Perth", EndLocation = "Brisbane" };
    var taxi2 = new TaxiInfo() { Fare = 2339.2, Distance = 1500, Driver = "Smith", StartLocation = "Perth", EndLocation = "America" };

    return View(new TaxiInfoSet(taxi1,taxi2));

The code for the view is as follows:

@model Taxi.Models.TaxiInfoSet
    ViewBag.Title = "Index";


@foreach(var TaxiInfo in Model.TaxiInfoList){
        <h1>Cost: [email protected]</h1>
        <h2>Distance: @(TaxiInfo.Distance) km</h2>
            Our diver, @TaxiInfo.Driver will take you from @TaxiInfo.StartLocation to @TaxiInfo.EndLocation

The ActionLink is responsible for the re-directing to the booking action of the Home controller (and passing in the appropriate TaxiInfo object) which is defiend as follows:

    public ActionResult Booking(TaxiInfo Taxi)
        return View(Taxi);

This returns a the following view:

@model Taxi.Models.TaxiInfo

    ViewBag.Title = "Booking";

<h2>Booking For</h2>
<h1>@Model.Driver, going from @Model.StartLocation to @Model.EndLocation (a total of @Model.Distance km) for [email protected]</h1>

A visual tour:

The Index view

The Booking view

AngularJS Multiple ng-app within a page

I have modified your jsfiddle, can make top most module as rootModule for rest of the modules. Below Modifications updated on your jsfiddle.

  1. Second Module can injected in RootModule.
  2. In Html second defined ng-app placed inside the Root ng-app.

Updated JsFiddle:

Split a large pandas dataframe

Use np.array_split:

Split an array into multiple sub-arrays.

Please refer to the ``split`` documentation.  The only difference
between these functions is that ``array_split`` allows
`indices_or_sections` to be an integer that does *not* equally
divide the axis.

In [1]: import pandas as pd

In [2]: df = pd.DataFrame({'A' : ['foo', 'bar', 'foo', 'bar',
   ...:                           'foo', 'bar', 'foo', 'foo'],
   ...:                    'B' : ['one', 'one', 'two', 'three',
   ...:                           'two', 'two', 'one', 'three'],
   ...:                    'C' : randn(8), 'D' : randn(8)})

In [3]: print df
     A      B         C         D
0  foo    one -0.174067 -0.608579
1  bar    one -0.860386 -1.210518
2  foo    two  0.614102  1.689837
3  bar  three -0.284792 -1.071160
4  foo    two  0.843610  0.803712
5  bar    two -1.514722  0.870861
6  foo    one  0.131529 -0.968151
7  foo  three -1.002946 -0.257468

In [4]: import numpy as np
In [5]: np.array_split(df, 3)
[     A    B         C         D
0  foo  one -0.174067 -0.608579
1  bar  one -0.860386 -1.210518
2  foo  two  0.614102  1.689837,
      A      B         C         D
3  bar  three -0.284792 -1.071160
4  foo    two  0.843610  0.803712
5  bar    two -1.514722  0.870861,
      A      B         C         D
6  foo    one  0.131529 -0.968151
7  foo  three -1.002946 -0.257468]

Splitting a C++ std::string using tokens, e.g. ";"

You could use a string stream and read the elements into the vector.

Here are many different examples...

A copy of one of the examples:

std::vector<std::string> split(const std::string& s, char seperator)
   std::vector<std::string> output;

    std::string::size_type prev_pos = 0, pos = 0;

    while((pos = s.find(seperator, pos)) != std::string::npos)
        std::string substring( s.substr(prev_pos, pos-prev_pos) );


        prev_pos = ++pos;

    output.push_back(s.substr(prev_pos, pos-prev_pos)); // Last word

    return output;

Where is my m2 folder on Mac OS X Mavericks

By default it will be hidden in your home directory. Type ls -a ~ to view that.

NSDictionary - Need to check whether dictionary contains key-value pair or not

With literal syntax you can check as follows

static const NSString* kKeyToCheck = @"yourKey"
if (xyz[kKeyToCheck])
  NSLog(@"Key: %@, has Value: %@", kKeyToCheck, xyz[kKeyToCheck]);
 NSLog(@"Key pair do not exits for key: %@", kKeyToCheck); 

JOptionPane Input to int

String String_firstNumber = JOptionPane.showInputDialog("Input  Semisecond");
int Int_firstNumber = Integer.parseInt(firstNumber);

Now your Int_firstnumber contains integer value of String_fristNumber.

hope it helped

How can I convert a DateTime to an int?

Do you want an 'int' that looks like 20110425171213? In which case you'd be better off ToString with the appropriate format (something like 'yyyyMMddHHmmss') and then casting the string to an integer (or a long, unsigned int as it will be way more than 32 bits).

If you want an actual numeric value (the number of seconds since the year 0) then that's a very different calculation, e.g.

result = second
result += minute * 60
result += hour * 60 * 60
result += day * 60 * 60 * 24 


But you'd be better off using Ticks.

Convert an integer to an array of digits

Call this function:

  public int[] convertToArray(int number) {
    int i = 0;
    int length = (int) Math.log10(number);
    int divisor = (int) Math.pow(10, length);
    int temp[] = new int[length + 1];

    while (number != 0) {
        temp[i] = number / divisor;
        if (i < length) {
        number = number % divisor;
        if (i != 0) {
            divisor = divisor / 10;
    return temp;

Get Android shared preferences value in activity/normal class

I tried this code, to retrieve shared preferences from an activity, and could not get it to work:

        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
    Log.d("AddNewRecord", "getAll: " + sharedPreferences.getAll());
    Log.d("AddNewRecord", "Size: " + sharedPreferences.getAll().size());

Every time I tried, my preferences returned 0, even though I have 14 preferences saved by the preference activity. I finally found the answer. I added this to the preferences in the onCreate section.


After I added this statement, my saved preferences returned as expected. I hope that this helps someone else who may experience the same issue that I did.

Change Git repository directory location.

While the question involves Git for Windows, this seems to be the top result even when searching for Visual Studio Tools For Git (extension in VS 2012, native support in VS 2013).

Using the solutions above as a guide I determined that Visual Studio Git Tools makes moving repos (or even entire directory structure for all repos) locally very easy.

1) Close Visual Studio. 2) Move the Repo folder(s) to new location. 3) Open Visual Studio. Open Team Explorer. Switch to "Connect" view (plug icon at top). 3a) If Repos still show old path, click Refresh to force an update. 4) Repos that were moved locally should no longer be showing in "Local Git Repositories". 5) Click Add (not new or clone) and select the repo folder to add.

In step 5 you really are just providing a search path and the search automatically includes all subfolders. If you have multiple repos organized under a single root (independent repos just having the same parent folder) then selecting the parent will include all repos found below that.

Example: E:\Repos\RepoA E:\Repos\RepoB E:\Repos\RepoC

In Visual Studio Team Explorer [Add] > "E:\Repos\" > [Add] will return all three to the Local Repositories.

How to get year and month from a date - PHP

I will share my code:

In your given example date:

$dateValue = '2012-01-05';

It will go like this:


   function dateName($date) {

        $result = "";

        $convert_date = strtotime($date);
        $month = date('F',$convert_date);
        $year = date('Y',$convert_date);
        $name_day = date('l',$convert_date);
        $day = date('j',$convert_date);

        $result = $month . " " . $day . ", " . $year . " - " . $name_day;

        return $result;

and will return a value: January 5, 2012 - Thursday

How do you do the "therefore" (?) symbol on a Mac or in Textmate?

If you are trying to insert the therefore symbol into a WORD DOCUMENT

Hold down the ALT key and type 8756

Hope the answer ur question Regards Al~Hash.

Using Sockets to send and receive data

the easiest way to do this is to wrap your sockets in ObjectInput/OutputStreams and send serialized java objects. you can create classes which contain the relevant data, and then you don't need to worry about the nitty gritty details of handling binary protocols. just make sure that you flush your object streams after you write each object "message".

How to reset all checkboxes using jQuery or pure JS?

If you mean how to remove the 'checked' state from all checkboxes:


How to tell CRAN to install package dependencies automatically?

On your own system, try

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

with the dependencies= argument is documented as

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

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

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

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

so you probably want a value TRUE.

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

How to label each equation in align environment?

Usually my align environments are set up like

  \lambda_i + \mu_i = 0 \\
  \mu_i \xi_i = 0 \\
  \lambda_i [y_i( w^T x_i + b) - 1 + \xi_i] = 0

The \label command should be placed in the line you want to reference, the placement in the line does not matter. I prefer to place it at the beginning at the line (as a sort of description) while others place them at the end.

When is it practical to use Depth-First Search (DFS) vs Breadth-First Search (BFS)?

The following is a comprehensive answer to what you are asking.

In simple terms:

Breadth First Search (BFS) algorithm, from its name "Breadth", discovers all the neighbours of a node through the out edges of the node then it discovers the unvisited neighbours of the previously mentioned neighbours through their out edges and so forth, till all the nodes reachable from the origional source are visited (we can continue and take another origional source if there are remaining unvisited nodes and so forth). That's why it can be used to find the shortest path (if there is any) from a node (origional source) to another node if the weights of the edges are uniform.

Depth First Search (DFS) algorithm, from its name "Depth", discovers the unvisited neighbours of the most recently discovered node x through its out edges. If there is no unvisited neighbour from the node x, the algorithm backtracks to discover the unvisited neighbours of the node (through its out edges) from which node x was discovered, and so forth, till all the nodes reachable from the origional source are visited (we can continue and take another origional source if there are remaining unvisited nodes and so forth).

Both BFS and DFS can be incomplete. For example if the branching factor of a node is infinite, or very big for the resources (memory) to support (e.g. when storing the nodes to be discovered next), then BFS is not complete even though the searched key can be at a distance of few edges from the origional source. This infinite branching factor can be because of infinite choices (neighbouring nodes) from a given node to discover. If the depth is infinite, or very big for the resources (memory) to support (e.g. when storing the nodes to be discovered next), then DFS is not complete even though the searched key can be the third neighbor of the origional source. This infinite depth can be because of a situation where there is, for every node the algorithm discovers, at least a new choice (neighbouring node) that is unvisited before.

Therefore, we can conclude when to use the BFS and DFS. Suppose we are dealing with a manageable limited branching factor and a manageable limited depth. If the searched node is shallow i.e. reachable after some edges from the origional source, then it is better to use BFS. On the other hand, if the searched node is deep i.e. reachable after a lot of edges from the origional source, then it is better to use DFS.

For example, in a social network if we want to search for people who have similar interests of a specific person, we can apply BFS from this person as an origional source, because mostly these people will be his direct friends or friends of friends i.e. one or two edges far. On the other hand, if we want to search for people who have completely different interests of a specific person, we can apply DFS from this person as an origional source, because mostly these people will be very far from him i.e. friend of friend of friend.... i.e. too many edges far.

Applications of BFS and DFS can vary also because of the mechanism of searching in each one. For example, we can use either BFS (assuming the branching factor is manageable) or DFS (assuming the depth is manageable) when we just want to check the reachability from one node to another having no information where that node can be. Also both of them can solve same tasks like topological sorting of a graph (if it has). BFS can be used to find the shortest path, with unit weight edges, from a node (origional source) to another. Whereas, DFS can be used to exhaust all the choices because of its nature of going in depth, like discovering the longest path between two nodes in an acyclic graph. Also DFS, can be used for cycle detection in a graph.

In the end if we have infinite depth and infinite branching factor, we can use Iterative Deepening Search (IDS).

Find index of last occurrence of a sub-string using T-SQL

Old but still valid question, so heres what I created based on the info provided by others here.

create function fnLastIndexOf(@text varChar(max),@char varchar(1))
returns int
return len(@text) - charindex(@char, reverse(@text)) -1

"Missing return statement" within if / for / while

That is illegal syntax. It is not an optional thing for you to return a variable. You MUST return a variable of the type you specify in your method.

public String myMethod()
       return x;

You are effectively saying, I promise any class can use this method(public) and I promise it will always return a String(String).

Then you are saying IF my condition is true I will return x. Well that is too bad, there is no IF in your promise. You promised that myMethod will ALWAYS return a String. Even if your condition is ALWAYS true the compiler has to assume that there is a possibility of it being false. Therefore you always need to put a return at the end of your non-void method outside of any conditions JUST IN CASE all of your conditions fail.

public String myMethod()
       return x;
  return ""; //or whatever the default behavior will be if all of your conditions fail to return.

Dockerfile if else condition with external arguments

According to the doc for the docker build command, there is a parameter called --build-arg.

Example usage:

docker build --build-arg HTTP_PROXY= .

IMO it's what you need :)

How to import data from one sheet to another

Saw this thread while looking for something else and I know it is super old, but I wanted to add my 2 cents.

NEVER USE VLOOKUP. It's one of the worst performing formulas in excel. Use index match instead. It even works without sorting data, unless you have a -1 or 1 in the end of the match formula (explained more below)

Here is a link with the appropriate formulas.

The Sheet 2 formula would be this: =IF(A2="","",INDEX(Sheet1!B:B,MATCH($A2,Sheet1!$A:$A,0)))

  • IF(A2="","", means if A2 is blank, return a blank value
  • INDEX(Sheet1!B:B, is saying INDEX B:B where B:B is the data you want to return. IE the name column.
  • Match(A2, is saying to Match A2 which is the ID you want to return the Name for.
  • Sheet1!A:A, is saying you want to match A2 to the ID column in the previous sheet
  • ,0)) is specifying you want an exact value. 0 means return an exact match to A2, -1 means return smallest value greater than or equal to A2, 1 means return the largest value that is less than or equal to A2. Keep in mind -1 and 1 have to be sorted.

More information on the Index/Match formula

Other fun facts: $ means absolute in a formula. So if you specify $B$1 when filling a formula down or over keeps that same value. If you over $B1, the B remains the same across the formula, but if you fill down, the 1 increases with the row count. Likewise, if you used B$1, filling to the right will increment the B, but keep the reference of row 1.

I also included the use of indirect in the second section. What indirect does is allow you to use the text of another cell in a formula. Since I created a named range sheet1!A:A = ID, sheet1!B:B = Name, and sheet1!C:C=Price, I can use the column name to have the exact same formula, but it uses the column heading to change the search criteria.

Good luck! Hope this helps.

Saving a text file on server using JavaScript

You must have a server-side script to handle your request, it can't be done using javascript.

To send raw data without URIencoding or escaping special characters to the php and save it as new txt file you can send ajax request using post method and FormData like:


var data = new FormData();
data.append("data" , "the_text_you_want_to_save");
var xhr = (window.XMLHttpRequest) ? new XMLHttpRequest() : new activeXObject("Microsoft.XMLHTTP"); 'post', '/path/to/php', true );


$data = $_POST['data'];
$fname = mktime() . ".txt";//generates random name

$file = fopen("upload/" .$fname, 'w');//creates new file
fwrite($file, $data);


As Florian mentioned below, the XHR fallback is not required since FormData is not supported in older browsers (formdata browser compatibiltiy), so you can declare XHR variable as:

var xhr = new XMLHttpRequest();

Also please note that this works only for browsers that support FormData such as IE +10.

How to check radio button is checked using JQuery?

Given a group of radio buttons:

<input type="radio" id="radio1" name="radioGroup" value="1">
<input type="radio" id="radio2" name="radioGroup" value="2">

You can test whether a specific one is checked using jQuery as follows:

if ($("#radio1").prop("checked")) {
   // do something

// OR
if ($("#radio1").is(":checked")) {
   // do something

// OR if you don't have ids set you can go by group name and value
// (basically you need a selector that lets you specify the particular input)
if ($("input[name='radioGroup'][value='1']").prop("checked"))

You can get the value of the currently checked one in the group as follows:


Gridview with two columns and auto resized images

another simple approach with modern built-in stuff like PercentRelativeLayout is now available for new users who hit this problem. thanks to android team for release this item.

< xmlns:android=""

<FrameLayout xmlns:android=""

        android:scaleType="centerCrop" />

        android:textColor="@android:color/white" />


and for better performance you can use some stuff like picasso image loader which help you to fill whole width of every image parents. for example in your adapter you should use this:

int width= context.getResources().getDisplayMetrics().widthPixels;
            .load("some url")

now you dont need CustomImageView Class anymore.

P.S i recommend to use ImageView in place of Type Int in class Item.

hope this help..

Why is a primary-foreign key relation required when we can join without it?

The main reason for primary and foreign keys is to enforce data consistency.

A primary key enforces the consistency of uniqueness of values over one or more columns. If an ID column has a primary key then it is impossible to have two rows with the same ID value. Without that primary key, many rows could have the same ID value and you wouldn't be able to distinguish between them based on the ID value alone.

A foreign key enforces the consistency of data that points elsewhere. It ensures that the data which is pointed to actually exists. In a typical parent-child relationship, a foreign key ensures that every child always points at a parent and that the parent actually exists. Without the foreign key you could have "orphaned" children that point at a parent that doesn't exist.

How can I detect when the mouse leaves the window?

This will work in chrome,

$(document).bind('dragleave', function (e) {
    if (e.originalEvent.clientX == 0){
        alert("left window");

dynamic_cast and static_cast in C++

There are no classes in C, so it's impossible to to write dynamic_cast in that language. C structures don't have methods (as a result, they don't have virtual methods), so there is nothing "dynamic" in it.

Stack array using pop() and push()

Better solution for your Stack implementation

import java.util.List;
import java.util.ArrayList;
public class IntegerStack 


    private List<Integer> stack;

    public IntegerStack(int SIZE) 
        stack = new ArrayList<Integer>(SIZE);

    public void push(int i) 


     public int pop() 
           int i= stack.get(0);
           return i;
        } else{
           return -1;// Or any invalid value

     public int peek()
           return stack.get(0);
        } else{
           return -1;// Or any invalid value

     public boolean isEmpty() 


If you have to use Array... Here are problems in your code and possible solutions

import java.util.Arrays;
public class IntegerStack 

    private int stack [];
    private int top; 

    public IntegerStack(int SIZE) 
    stack = new int [SIZE];
    top = -1; // top should be 0. If you keep it as -1, problems will arise when SIZE is passed as 0. 
    // In your push method -1==0 will be false and your code will try to add the invalid element to Stack .. 
     /**Solution top=0; */

public void push(int i) 
    if (top == stack.length)

       stack[top]= i;


public int pop() 
    top --; // here you are reducing the top before giving the Object back 
      int value = stack[top];
       top --;
     return value; 
    } else{
      return -1;// OR invalid value
    return stack[top];

public int peek()
    return stack[top]; // Problem when stack is empty or size is 0
         return stack[top];
         return -1;// Or any invalid value


public boolean isEmpty() 
    if ( top == -1); // problem... we changed top to 0 above so here it need to check if its 0 and there should be no semicolon after the if statement
   /* Solution if(top==0) */
        return true;

private void extendStack()

    int [] copy = Arrays.copyOf(stack, stack.length); // The second parameter in Arrays.copyOf has no changes, so there will be no change in array length.
    stack=Arrays.copyOf(stack, stack.length+1); 


dyld: Library not loaded: /usr/local/lib/libpng16.16.dylib with anything php related

I suggest you run:

$ brew update && brew upgrade

Until couple of minutes ago I had this problem, too. Because I have an up to date PHP version, I solved it with:

$ brew reinstall php55

Hope that helps.

Getting key with maximum value in dictionary?

Much simpler to understand approach:

dict = { 'a':302, 'e':53, 'g':302, 'h':100 }
max_value_keys = [key for key in dict.keys() if dict[key] == max(dict.values())]
print(max_value_keys) # prints a list of keys with max value

Output: ['a', 'g']

Now you can choose only one key:

maximum = dict[max_value_keys[0]]

Strange Characters in database text: Ã, Ã, ¢, â‚ €,

If the charset of the tables is the same as it's content try to use mysql_set_charset('UTF8', $link_identifier). Note that MySQL uses UTF8 to specify the UTF-8 encoding instead of UTF-8 which is more common.

Check my other answer on a similar question too.

Parser Error: '_Default' is not allowed here because it does not extend class 'System.Web.UI.Page' & MasterType declaration

My issue was simple: the Master page and Master.Designer.cs class had the correct Namespace, but the Master.cs class had the wrong namespace.

How do you delete all text above a certain line


delete all lines above the current one.

Getting the name of the currently executing method

January 2009:
A full code would be (to use with @Bombe's caveat in mind):

 * Get the method name for a depth in call stack. <br />
 * Utility function
 * @param depth depth in the call stack (0 means current method, 1 means call method, ...)
 * @return method name
public static String getMethodName(final int depth)
  final StackTraceElement[] ste = Thread.currentThread().getStackTrace();

  //System. out.println(ste[ste.length-depth].getClassName()+"#"+ste[ste.length-depth].getMethodName());
  // return ste[ste.length - depth].getMethodName();  //Wrong, fails for depth = 0
  return ste[ste.length - 1 - depth].getMethodName(); //Thank you Tom Tresansky

More in this question.

Update December 2011:

bluish comments:

I use JRE 6 and gives me incorrect method name.
It works if I write ste[2 + depth].getMethodName().

  • 0 is getStackTrace(),
  • 1 is getMethodName(int depth) and
  • 2 is invoking method.

virgo47's answer (upvoted) actually computes the right index to apply in order to get back the method name.

Failed to execute 'btoa' on 'Window': The string to be encoded contains characters outside of the Latin1 range.

If you have UTF8, use this (actually works with SVG source), like:



 var imgsrc = 'data:image/svg+xml;base64,' + btoa(unescape(encodeURIComponent(markup)));
 var img = new Image(1, 1); // width, height values are optional params 
 img.src = imgsrc;

If you need to decode that base64, use this:

var str2 = decodeURIComponent(escape(window.atob(b64)));


var str = "äöüÄÖÜçéèñ";
var b64 = window.btoa(unescape(encodeURIComponent(str)))

var str2 = decodeURIComponent(escape(window.atob(b64)));

Note: if you need to get this to work in mobile-safari, you might need to strip all the white-space from the base64 data...

function b64_to_utf8( str ) {
    str = str.replace(/\s/g, '');    
    return decodeURIComponent(escape(window.atob( str )));

2017 Update

This problem has been bugging me again.
The simple truth is, atob doesn't really handle UTF8-strings - it's ASCII only.
Also, I wouldn't use bloatware like js-base64.
But webtoolkit does have a small, nice and very maintainable implementation:

*  Base64 encode / decode
var Base64 = {

    // private property
    _keyStr: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="

    // public method for encoding
    , encode: function (input)
        var output = "";
        var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
        var i = 0;

        input = Base64._utf8_encode(input);

        while (i < input.length)
            chr1 = input.charCodeAt(i++);
            chr2 = input.charCodeAt(i++);
            chr3 = input.charCodeAt(i++);

            enc1 = chr1 >> 2;
            enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
            enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
            enc4 = chr3 & 63;

            if (isNaN(chr2))
                enc3 = enc4 = 64;
            else if (isNaN(chr3))
                enc4 = 64;

            output = output +
                this._keyStr.charAt(enc1) + this._keyStr.charAt(enc2) +
                this._keyStr.charAt(enc3) + this._keyStr.charAt(enc4);
        } // Whend 

        return output;
    } // End Function encode 

    // public method for decoding
    ,decode: function (input)
        var output = "";
        var chr1, chr2, chr3;
        var enc1, enc2, enc3, enc4;
        var i = 0;

        input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
        while (i < input.length)
            enc1 = this._keyStr.indexOf(input.charAt(i++));
            enc2 = this._keyStr.indexOf(input.charAt(i++));
            enc3 = this._keyStr.indexOf(input.charAt(i++));
            enc4 = this._keyStr.indexOf(input.charAt(i++));

            chr1 = (enc1 << 2) | (enc2 >> 4);
            chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
            chr3 = ((enc3 & 3) << 6) | enc4;

            output = output + String.fromCharCode(chr1);

            if (enc3 != 64)
                output = output + String.fromCharCode(chr2);

            if (enc4 != 64)
                output = output + String.fromCharCode(chr3);

        } // Whend 

        output = Base64._utf8_decode(output);

        return output;
    } // End Function decode 

    // private method for UTF-8 encoding
    ,_utf8_encode: function (string)
        var utftext = "";
        string = string.replace(/\r\n/g, "\n");

        for (var n = 0; n < string.length; n++)
            var c = string.charCodeAt(n);

            if (c < 128)
                utftext += String.fromCharCode(c);
            else if ((c > 127) && (c < 2048))
                utftext += String.fromCharCode((c >> 6) | 192);
                utftext += String.fromCharCode((c & 63) | 128);
                utftext += String.fromCharCode((c >> 12) | 224);
                utftext += String.fromCharCode(((c >> 6) & 63) | 128);
                utftext += String.fromCharCode((c & 63) | 128);

        } // Next n 

        return utftext;
    } // End Function _utf8_encode 

    // private method for UTF-8 decoding
    ,_utf8_decode: function (utftext)
        var string = "";
        var i = 0;
        var c, c1, c2, c3;
        c = c1 = c2 = 0;

        while (i < utftext.length)
            c = utftext.charCodeAt(i);

            if (c < 128)
                string += String.fromCharCode(c);
            else if ((c > 191) && (c < 224))
                c2 = utftext.charCodeAt(i + 1);
                string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
                i += 2;
                c2 = utftext.charCodeAt(i + 1);
                c3 = utftext.charCodeAt(i + 2);
                string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
                i += 3;

        } // Whend 

        return string;
    } // End Function _utf8_decode 


  • For any character equal to or below 127 (hex 0x7F), the UTF-8 representation is one byte. It is just the lowest 7 bits of the full unicode value. This is also the same as the ASCII value.

  • For characters equal to or below 2047 (hex 0x07FF), the UTF-8 representation is spread across two bytes. The first byte will have the two high bits set and the third bit clear (i.e. 0xC2 to 0xDF). The second byte will have the top bit set and the second bit clear (i.e. 0x80 to 0xBF).

  • For all characters equal to or greater than 2048 but less that 65535 (0xFFFF), the UTF-8 representation is spread across three bytes.

How to call another components function in angular2

Component 1(child):

export class Component1{

Component 2(parent):

  template: `<com1 #component1></com1>`
export class Component2{
  @ViewChild("component1") component1: Component1;


Renaming Columns in an SQL SELECT Statement

you have to rename each column

SELECT col1 as MyCol1,
       col2 as MyCol2,
 FROM `foobar`

How to squash all git commits into one?

The easiest way is to use the 'plumbing' command update-ref to delete the current branch.

You can't use git branch -D as it has a safety valve to stop you deleting the current branch.

This puts you back into the 'initial commit' state where you can start with a fresh initial commit.

git update-ref -d refs/heads/master
git commit -m "New initial commit"

TypeError: $(...).modal is not a function with bootstrap Modal

In my case, I use rails framework and require jQuery twice. I think that is a possible reason.

You can first check app/assets/application.js file. If the jquery and bootstrap-sprockets appears, then there is not need for a second library require. The file should be similar to this:

//= require jquery
//= require jquery_ujs
//= require turbolinks
//= require bootstrap-sprockets
//= require_tree .

Then check app/views/layouts/application.html.erb, and remove the script for requiring jquery. For example:

    <script src=""></script>

I think sometimes when newbies use multiple tutorial code examples will cause this issue.

Completely uninstall PostgreSQL 9.0.4 from Mac OSX Lion?

I don't use the same version, but uninstall actions are the same: Looking for file uninstall-postgresql inside directory


enter image description here

then run it.

enter image description here

(Screenshot in macOS 10.13)


sudo rm -rf /Library/PostgreSQL/

to delete all unnecessary directory.

How do I Search/Find and Replace in a standard string?

Why not implement your own replace?

void myReplace(std::string& str,
               const std::string& oldStr,
               const std::string& newStr)
  std::string::size_type pos = 0u;
  while((pos = str.find(oldStr, pos)) != std::string::npos){
     str.replace(pos, oldStr.length(), newStr);
     pos += newStr.length();

Google MAP API Uncaught TypeError: Cannot read property 'offsetWidth' of null

My fail was to use


as an option, rather than the correct option


Graphical user interface Tutorial in C

You can also have a look at FLTK (C++ and not plain C though)

FLTK (pronounced "fulltick") is a cross-platform C++ GUI toolkit for UNIX®/Linux® (X11), Microsoft® Windows®, and MacOS® X. FLTK provides modern GUI functionality without the bloat and supports 3D graphics via OpenGL® and its built-in GLUT emulation.

FLTK is designed to be small and modular enough to be statically linked, but works fine as a shared library. FLTK also includes an excellent UI builder called FLUID that can be used to create applications in minutes.

Here are some quickstart screencasts

[Happy New Year!]

how to display none through code behind

Try if this works:

Panel2.Style.Add("display", "none");

How to force reloading php.ini file?

To force a reload of the php.ini you should restart apache.

Try sudo service apache2 restart from the command line. Or sudo /etc/init.d/apache2 restart

How to replace all dots in a string using JavaScript

replaceAll(search, replaceWith) [MDN]

 ".a.b.c.".replaceAll('.', ' ')
 // result: " a b c "

 // Using RegEx. You MUST use a global RegEx.
 ".a.b.c.".replaceAll(/\./g, ' ')
 // result: " a b c "

replaceAll() replaces ALL occurrences of search with replaceWith.

It's actually the same as using replace() [MDN] with a global regex(*), merely replaceAll() is a bit more readable in my view.

(*) Meaning it'll match all occurrences.

Important(!) if you choose regex:

when using a regexp you have to set the global ("g") flag; otherwise, it will throw a TypeError: "replaceAll must be called with a global RegExp".

Multiple inheritance for an anonymous class

An anonymous class is extending or implementing while creating its object For example :

Interface in = new InterFace()



Here anonymous class is implementing Interface.

Class cl = new Class(){



here anonymous Class is extending a abstract Class.

Simple way to get element by id within a div tag?

A simple way to do what OP desires in core JS.


Where to change default pdf page width and font size in jspdf.debug.js?

Besides using one of the default formats you can specify any size you want in the unit you specify.

For example:

// Document of 210mm wide and 297mm high
new jsPDF('p', 'mm', [297, 210]);
// Document of 297mm wide and 210mm high
new jsPDF('l', 'mm', [297, 210]);
// Document of 5 inch width and 3 inch high
new jsPDF('l', 'in', [3, 5]);

The 3rd parameter of the constructor can take an array of the dimensions. However they do not correspond to width and height, instead they are long side and short side (or flipped around).

Your 1st parameter (landscape or portrait) determines what becomes the width and the height.

In the sourcecode on GitHub you can see the supported units (relative proportions to pt), and you can also see the default page formats (with their sizes in pt).

Alternating Row Colors in Bootstrap 3 - No Table

I find that if I specify .row:nth-of-type(..), my other row's elements (for other formatting, etc) also get alternating colours. So rather, I'd define in my css an entirely new class:

  background-color: #efefef;

  background-color: #ffffff;

So now, the alternating row colours will only apply to the row container, when I specify its class as .row-striped, and not the elements inside the row.

<!-- this entire row container is #efefef -->
<div class="row row-striped">
    <div class="form-group">
        <div class="col-sm-8"><h5>Field Greens with strawberry vinegrette</h5></div>
        <div class="col-sm-4">
            <input type="number" type="number" step="1" min="0"></input><small>$30/salad</small>

<!-- this entire row container is #ffffff -->
<div class="row row-striped">
    <div class="form-group">
        <div class="col-sm-8"><h5>Greek Salad</h5></div>
        <div class="col-sm-4">
            <input type="number" type="number" step="1" min="0"></input><small>$25/salad</small>

HTML5 record audio to file

The code shown below is copyrighted to Matt Diamond and available for use under MIT license. The original files are here:

Save this files and use

      var WORKER_PATH = 'recorderWorker.js';_x000D_
      var Recorder = function(source, cfg){_x000D_
        var config = cfg || {};_x000D_
        var bufferLen = config.bufferLen || 4096;_x000D_
        this.context = source.context;_x000D_
        this.node = this.context.createScriptProcessor(bufferLen, 2, 2);_x000D_
        var worker = new Worker(config.workerPath || WORKER_PATH);_x000D_
          command: 'init',_x000D_
          config: {_x000D_
            sampleRate: this.context.sampleRate_x000D_
        var recording = false,_x000D_
        this.node.onaudioprocess = function(e){_x000D_
          if (!recording) return;_x000D_
            command: 'record',_x000D_
            buffer: [_x000D_
        this.configure = function(cfg){_x000D_
          for (var prop in cfg){_x000D_
            if (cfg.hasOwnProperty(prop)){_x000D_
              config[prop] = cfg[prop];_x000D_
        this.record = function(){_x000D_
          recording = true;_x000D_
        this.stop = function(){_x000D_
          recording = false;_x000D_
        this.clear = function(){_x000D_
          worker.postMessage({ command: 'clear' });_x000D_
        this.getBuffer = function(cb) {_x000D_
          currCallback = cb || config.callback;_x000D_
          worker.postMessage({ command: 'getBuffer' })_x000D_
        this.exportWAV = function(cb, type){_x000D_
          currCallback = cb || config.callback;_x000D_
          type = type || config.type || 'audio/wav';_x000D_
          if (!currCallback) throw new Error('Callback not set');_x000D_
            command: 'exportWAV',_x000D_
            type: type_x000D_
        worker.onmessage = function(e){_x000D_
          var blob =;_x000D_
        this.node.connect(this.context.destination);    //this should not be necessary_x000D_
      Recorder.forceDownload = function(blob, filename){_x000D_
        var url = (window.URL || window.webkitURL).createObjectURL(blob);_x000D_
        var link = window.document.createElement('a');_x000D_
        link.href = url;_x000D_ = filename || 'output.wav';_x000D_
        var click = document.createEvent("Event");_x000D_
        click.initEvent("click", true, true);_x000D_
      window.Recorder = Recorder;_x000D_
    //ADDITIONAL JS recorderWorker.js_x000D_
    var recLength = 0,_x000D_
      recBuffersL = [],_x000D_
      recBuffersR = [],_x000D_
    this.onmessage = function(e){_x000D_
        case 'init':_x000D_
        case 'record':_x000D_
        case 'exportWAV':_x000D_
        case 'getBuffer':_x000D_
        case 'clear':_x000D_
    function init(config){_x000D_
      sampleRate = config.sampleRate;_x000D_
    function record(inputBuffer){_x000D_
      recLength += inputBuffer[0].length;_x000D_
    function exportWAV(type){_x000D_
      var bufferL = mergeBuffers(recBuffersL, recLength);_x000D_
      var bufferR = mergeBuffers(recBuffersR, recLength);_x000D_
      var interleaved = interleave(bufferL, bufferR);_x000D_
      var dataview = encodeWAV(interleaved);_x000D_
      var audioBlob = new Blob([dataview], { type: type });_x000D_
    function getBuffer() {_x000D_
      var buffers = [];_x000D_
      buffers.push( mergeBuffers(recBuffersL, recLength) );_x000D_
      buffers.push( mergeBuffers(recBuffersR, recLength) );_x000D_
    function clear(){_x000D_
      recLength = 0;_x000D_
      recBuffersL = [];_x000D_
      recBuffersR = [];_x000D_
    function mergeBuffers(recBuffers, recLength){_x000D_
      var result = new Float32Array(recLength);_x000D_
      var offset = 0;_x000D_
      for (var i = 0; i < recBuffers.length; i++){_x000D_
        result.set(recBuffers[i], offset);_x000D_
        offset += recBuffers[i].length;_x000D_
      return result;_x000D_
    function interleave(inputL, inputR){_x000D_
      var length = inputL.length + inputR.length;_x000D_
      var result = new Float32Array(length);_x000D_
      var index = 0,_x000D_
        inputIndex = 0;_x000D_
      while (index < length){_x000D_
        result[index++] = inputL[inputIndex];_x000D_
        result[index++] = inputR[inputIndex];_x000D_
      return result;_x000D_
    function floatTo16BitPCM(output, offset, input){_x000D_
      for (var i = 0; i < input.length; i++, offset+=2){_x000D_
        var s = Math.max(-1, Math.min(1, input[i]));_x000D_
        output.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7FFF, true);_x000D_
    function writeString(view, offset, string){_x000D_
      for (var i = 0; i < string.length; i++){_x000D_
        view.setUint8(offset + i, string.charCodeAt(i));_x000D_
    function encodeWAV(samples){_x000D_
      var buffer = new ArrayBuffer(44 + samples.length * 2);_x000D_
      var view = new DataView(buffer);_x000D_
      /* RIFF identifier */_x000D_
      writeString(view, 0, 'RIFF');_x000D_
      /* file length */_x000D_
      view.setUint32(4, 32 + samples.length * 2, true);_x000D_
      /* RIFF type */_x000D_
      writeString(view, 8, 'WAVE');_x000D_
      /* format chunk identifier */_x000D_
      writeString(view, 12, 'fmt ');_x000D_
      /* format chunk length */_x000D_
      view.setUint32(16, 16, true);_x000D_
      /* sample format (raw) */_x000D_
      view.setUint16(20, 1, true);_x000D_
      /* channel count */_x000D_
      view.setUint16(22, 2, true);_x000D_
      /* sample rate */_x000D_
      view.setUint32(24, sampleRate, true);_x000D_
      /* byte rate (sample rate * block align) */_x000D_
      view.setUint32(28, sampleRate * 4, true);_x000D_
      /* block align (channel count * bytes per sample) */_x000D_
      view.setUint16(32, 4, true);_x000D_
      /* bits per sample */_x000D_
      view.setUint16(34, 16, true);_x000D_
      /* data chunk identifier */_x000D_
      writeString(view, 36, 'data');_x000D_
      /* data chunk length */_x000D_
      view.setUint32(40, samples.length * 2, true);_x000D_
      floatTo16BitPCM(view, 44, samples);_x000D_
      return view;_x000D_
      <audio controls autoplay></audio>_x000D_
      <script type="text/javascript" src="recorder.js"> </script>_x000D_
                    <fieldset><legend>RECORD AUDIO</legend>_x000D_
      <input onclick="startRecording()" type="button" value="start recording" />_x000D_
      <input onclick="stopRecording()" type="button" value="stop recording and play" />_x000D_
       var onFail = function(e) {_x000D_
        console.log('Rejected!', e);_x000D_
       var onSuccess = function(s) {_x000D_
        var context = new webkitAudioContext();_x000D_
        var mediaStreamSource = context.createMediaStreamSource(s);_x000D_
        recorder = new Recorder(mediaStreamSource);_x000D_
        // audio loopback_x000D_
        // mediaStreamSource.connect(context.destination);_x000D_
       window.URL = window.URL || window.webkitURL;_x000D_
       navigator.getUserMedia  = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia;_x000D_
       var recorder;_x000D_
       var audio = document.querySelector('audio');_x000D_
       function startRecording() {_x000D_
        if (navigator.getUserMedia) {_x000D_
         navigator.getUserMedia({audio: true}, onSuccess, onFail);_x000D_
        } else {_x000D_
         console.log('navigator.getUserMedia not present');_x000D_
       function stopRecording() {_x000D_
        recorder.exportWAV(function(s) {_x000D_
                                  audio.src = window.URL.createObjectURL(s);_x000D_

Ignore 'Security Warning' running script from command line

Assume that you need to launch ps script from shared folder

copy \\\server\script.ps1 c:\tmp.ps1 /y && PowerShell.exe -ExecutionPolicy Bypass -File c:\tmp.ps1 && del /f c:\tmp.ps1

P.S. Reduce googling)

In Python, how do I iterate over a dictionary in sorted key order?

A dict's keys are stored in a hashtable so that is their 'natural order', i.e. psuedo-random. Any other ordering is a concept of the consumer of the dict.

sorted() always returns a list, not a dict. If you pass it a dict.items() (which produces a list of tuples), it will return a list of tuples [(k1,v1), (k2,v2), ...] which can be used in a loop in a way very much like a dict, but it is not in anyway a dict!

foo = {
    'a':    1,
    'b':    2,
    'c':    3,

print foo
>>> {'a': 1, 'c': 3, 'b': 2}

print foo.items()
>>> [('a', 1), ('c', 3), ('b', 2)]

print sorted(foo.items())
>>> [('a', 1), ('b', 2), ('c', 3)]

The following feels like a dict in a loop, but it's not, it's a list of tuples being unpacked into k,v:

for k,v in sorted(foo.items()):
    print k, v

Roughly equivalent to:

for k in sorted(foo.keys()):
    print k, foo[k]

Format date in a specific timezone

Use moment-timezone


Before being able to access a particular timezone, you will need to load it like so (or using alternative methods described here)'Europe/Berlin|CET CEST CEMT|-10 -20 -30')

Disable/enable an input with jQuery?

In jQuery Mobile:

For disable

$('#someselectElement').selectmenu().selectmenu('disable').selectmenu('refresh', true);

For enable

$('#someselectElement').selectmenu().selectmenu('enable').selectmenu('refresh', true);

Populate one dropdown based on selection in another

Could you please have a look at:

Basically, the data is stored in an Array and the options are added accordingly. I think the code says more than a thousand words.

var data = [ // The data
    ['ten', [
    ['twenty', [
        'twentyone', 'twentytwo'

$a = $('#a'); // The dropdowns
$b = $('#b');

for(var i = 0; i < data.length; i++) {
    var first = data[i][0];
    $a.append($("<option>"). // Add options
       data("sel", i).

$a.change(function() {
    var index = $(this).children('option:selected').data('sel');
    var second = data[index][1]; // The second-choice data

    $b.html(''); // Clear existing options in second dropdown

    for(var j = 0; j < second.length; j++) {
        $b.append($("<option>"). // Add options
           data("sel", j).
}).change(); // Trigger once to add options at load of first choice

Does "\d" in regex mean a digit?

\\d{3} matches any sequence of three digits in Java.

Razor Views not seeing System.Web.Mvc.HtmlHelper

As a variation on a theme, I could have sworn up and down that my Views\Web.config was correct:

<host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />

But I in fact needed to reference Version=, not Version= because of that security update that got pushed out a while back.

maven-dependency-plugin (goals "copy-dependencies", "unpack") is not supported by m2e

Another option is to navigate to problems tab, right click on error, click apply quick fix. The should generate the ignore xml code and apply it .pom file for you.

Video auto play is not working in Safari and Chrome desktop browser

Adding the below code at the bottom of the page worked for me . I dont know why it works :(


Get item in the list in Scala?

Please use parenthesis () to access the list elements list_name(index)

How can I resize an image using Java?

you can use following popular product: thumbnailator

Applying .gitignore to committed files

Be sure that your actual repo is the lastest version

  1. Edit .gitignore as you wish
  2. git rm -r --cached . (remove all files)
  3. git add . (re-add all files)

then commit as usual

Node.js EACCES error when listening on most ports

restart was not enough! The only way to solve the problem is by the following:

You have to kill the service which run at that port.

at cmd, run as admin, then type : netstat -aon | find /i "listening"

Then, you will get a list with the active service, search for the port that is running at 4200n and use the process id which is the last column to kill it by

: taskkill /F /PID 2652

Can we open pdf file using UIWebView on iOS?

NSString *folderName=[NSString stringWithFormat:@"/documents/%@",[tempDictLitrature objectForKey:@"folder"]];
NSString *fileName=[tempDictLitrature objectForKey:@"name"];
[self.navigationItem setTitle:fileName];
NSString *type=[tempDictLitrature objectForKey:@"type"];

NSString *path=[[NSBundle mainBundle]pathForResource:fileName ofType:type inDirectory:folderName];

NSURL *targetURL = [NSURL fileURLWithPath:path];
NSURLRequest *request = [NSURLRequest requestWithURL:targetURL];
webView=[[UIWebView alloc] initWithFrame:CGRectMake(0, 0, 1024, 730)];
[webView setBackgroundColor:[UIColor lightGrayColor]];
webView.scalesPageToFit = YES;

[[webView scrollView] setContentOffset:CGPointZero animated:YES];
[webView stringByEvaluatingJavaScriptFromString:[NSString stringWithFormat:@"window.scrollTo(0.0, 50.0)"]];
[webView loadRequest:request];
[self.view addSubview:webView];

How do I bottom-align grid elements in bootstrap fluid layout

This is based on cfx's solution, but rather than setting the font size to zero in the parent container to remove the inter-column spaces added because of the display: inline-block and having to reset them, I simply added

.row.row-align-bottom > div {_x000D_
    float: none;_x000D_
    display: inline-block;_x000D_
    vertical-align: bottom;_x000D_
    margin-right: -0.25em;_x000D_

to the column divs to compensate.

Ruby: How to convert a string to boolean

I've frequently used this pattern to extend the core behavior of Ruby to make it easier to deal with converting arbitrary data types to boolean values, which makes it really easy to deal with varying URL parameters, etc.

class String
  def to_boolean

class NilClass
  def to_boolean

class TrueClass
  def to_boolean

  def to_i

class FalseClass
  def to_boolean

  def to_i

class Integer
  def to_boolean

So let's say you have a parameter foo which can be:

  • an integer (0 is false, all others are true)
  • a true boolean (true/false)
  • a string ("true", "false", "0", "1", "TRUE", "FALSE")
  • nil

Instead of using a bunch of conditionals, you can just call foo.to_boolean and it will do the rest of the magic for you.

In Rails, I add this to an initializer named core_ext.rb in nearly all of my projects since this pattern is so common.


nil.to_boolean     == false
true.to_boolean    == true
false.to_boolean   == false
0.to_boolean       == false
1.to_boolean       == true
99.to_boolean      == true
"true".to_boolean  == true
"foo".to_boolean   == true
"false".to_boolean == false
"TRUE".to_boolean  == true
"FALSE".to_boolean == false
"0".to_boolean     == false
"1".to_boolean     == true
true.to_i          == 1
false.to_i         == 0

How to set fake GPS location on IOS real device

you can do it on real device by run device in Debug mode

Click Debug->Simulate Location -> add .gpx file for your location during run time

Write to file, but overwrite it if it exists

In Bash, if you have set noclobber a la set -o noclobber, then you use the syntax >|

For example:

echo "some text" >| existing_file

This also works if the file doesn't exist yet

  • Check if noclobber is set with: set -o | grep noclobber

  • For a more detailed explanation on this special type of operator, see this post

  • For a more exhaustive list of redirection operators, refer to this post

HttpServletRequest get JSON POST data

Normaly you can GET and POST parameters in a servlet the same way:


But only if the POST data is encoded as key-value pairs of content type: "application/x-www-form-urlencoded" like when you use a standard HTML form.

If you use a different encoding schema for your post data, as in your case when you post a json data stream, you need to use a custom decoder that can process the raw datastream from:

BufferedReader reader = request.getReader();

Json post processing example (uses org.json package )

public void doPost(HttpServletRequest request, HttpServletResponse response)
  throws ServletException, IOException {

  StringBuffer jb = new StringBuffer();
  String line = null;
  try {
    BufferedReader reader = request.getReader();
    while ((line = reader.readLine()) != null)
  } catch (Exception e) { /*report an error*/ }

  try {
    JSONObject jsonObject =  HTTP.toJSONObject(jb.toString());
  } catch (JSONException e) {
    // crash and burn
    throw new IOException("Error parsing JSON request string");

  // Work with the data using methods like...
  // int someInt = jsonObject.getInt("intParamName");
  // String someString = jsonObject.getString("stringParamName");
  // JSONObject nestedObj = jsonObject.getJSONObject("nestedObjName");
  // JSONArray arr = jsonObject.getJSONArray("arrayParamName");
  // etc...

How do I determine the dependencies of a .NET application?

Enable assembly binding logging set the registry value EnableLog in HKLM\Software\Microsoft\Fusion to 1. Note that you have to restart your application (use iisreset) for the changes to have any effect.

Tip: Remember to turn off fusion logging when you are done since there is a performance penalty to have it turned on.

Jquery set radio button checked, using id and class selectors

" a class and a div."

I assume when you say "div" you mean "id"? Try this:

$('#test2.test1').prop('checked', true);

No need to muck about with your [attributename=value] style selectors because id has its own format as does class, and they're easily combined although given that id is supposed to be unique it should be enough on its own unless your meaning is "select that element only if it currently has the specified class".

Or more generally to select an input where you want to specify a multiple attribute selector:

$('input:radio[class=test1][id=test2]').prop('checked', true);

That is, list each attribute with its own square brackets.

Note that unless you have a pretty old version of jQuery you should use .prop() rather than .attr() for this purpose.

Javascript ajax call on page onload

It's even easier to do without a library

window.onload = function() {
    // code

Curl to return http status code along with the response

while : ; do curl -sL -w "%{http_code} %{url_effective}\\n" http://host -o /dev/null; done

Openstreetmap: embedding map in webpage (like Google Maps)

You can use OpenLayers (js API for maps).

There's an example on their page showing how to embed OSM tiles.

Edit: New Link to OpenLayers examples

How to loop through a HashMap in JSP?

Depending on what you want to accomplish within the loop, iterate over one of these instead:

  • countries.keySet()
  • countries.entrySet()
  • countries.values()

How to reliably open a file in the same directory as a Python script

On Python 3.4, the pathlib module was added, and the following code will reliably open a file in the same directory as the current script:

from pathlib import Path

p = Path(__file__).with_name('file.txt')
with'r') as f:

You can also use parent.absolute() to get directory value as a string if needed:

p = Path(__file__)
dir_abs = p.parent.absolute()  # Will return the executable directory absolute path

Why is the Visual Studio 2015/2017/2019 Test Runner not discovering my xUnit v2 tests

I tried most of the suggestions above and nothing worked. In my case, I'm on a team and tests were appearing for other devs for the same solution. So, I attempted just deleting my .vs folder, but no luck there either.

I ended up deleting my local folder entirely and re-cloning the repo. That solved it for me.

How to set xlim and ylim for a subplot in matplotlib

You should use the OO interface to matplotlib, rather than the state machine interface. Almost all of the plt.* function are thin wrappers that basically do gca().*.

plt.subplot returns an axes object. Once you have a reference to the axes object you can plot directly to it, change its limits, etc.

import matplotlib.pyplot as plt

ax1 = plt.subplot(131)
ax1.scatter([1, 2], [3, 4])
ax1.set_xlim([0, 5])
ax1.set_ylim([0, 5])

ax2 = plt.subplot(132)
ax2.scatter([1, 2],[3, 4])
ax2.set_xlim([0, 5])
ax2.set_ylim([0, 5])

and so on for as many axes as you want.

or better, wrap it all up in a loop:

import matplotlib.pyplot as plt

DATA_x = ([1, 2],
          [2, 3],
          [3, 4])

DATA_y = DATA_x[::-1]

XLIMS = [[0, 10]] * 3
YLIMS = [[0, 10]] * 3

for j, (x, y, xlim, ylim) in enumerate(zip(DATA_x, DATA_y, XLIMS, YLIMS)):
    ax = plt.subplot(1, 3, j + 1)
    ax.scatter(x, y)

Target class controller does not exist - Laravel 8

in laravel-8 default remove namespace prefix so you can set old way in laravel-7 like:

in RouteServiceProvider.php add this variable

protected $namespace = 'App\Http\Controllers';

and update boot method

public function boot()

       $this->routes(function () {


Selenium -- How to wait until page is completely loaded

There are two different ways to use delay in selenium one which is most commonly in use. Please try this:

driver.manage().timeouts().implicitlyWait(20, TimeUnit.SECONDS);

second one which you can use that is simply try catch method by using that method you can get your desire result.if you want example code feel free to contact me defiantly I will provide related code

How to see the CREATE VIEW code for a view in PostgreSQL?

These is a little thing to point out.
Using the function pg_get_viewdef or pg_views or information_schema.views you will always get a rewrited version of your original DDL.
The rewited version may or not be the same as your originl DDL script.

If the Rule Manager rewrite your view definition your original DLL will be lost and you will able to read the only the rewrited version of your view definition.
Not all views are rewrited but if you use sub-select or joins probably your views will be rewrited.

Insert new column into table in sqlite?

I was facing the same problem and the second method proposed in the accepted answer, as noted in the comments, can be problematic when dealing with foreign keys.

My workaround is to export the database to a sql file making sure that the INSERT statements include column names. I do it using DB Browser for SQLite which has an handy feature for that. After that you just have to edit the create table statement and insert the new column where you want it and recreate the db.

In *nix like systems is just something along the lines of

cat db.sql | sqlite3 database.db

I don't know how feasible this is with very big databases, but it worked in my case.

How to use OpenSSL to encrypt/decrypt files?

Note that the OpenSSL CLI uses a weak non-standard algorithm to convert the passphrase to a key, and installing GPG results in various files added to your home directory and a gpg-agent background process running. If you want maximum portability and control with existing tools, you can use PHP or Python to access the lower-level APIs and directly pass in a full AES Key and IV.

Example PHP invocation via Bash:


ENCRYPTED=$(php -r "print(openssl_encrypt('$INPUT','aes-256-ctr',base64_decode('$KEY'),OPENSSL_ZERO_PADDING,base64_decode('$IV')));")
DECRYPTED=$(php -r "print(openssl_decrypt('$ENCRYPTED','aes-256-ctr',base64_decode('$KEY'),OPENSSL_ZERO_PADDING,base64_decode('$IV')));")

This outputs:


You could also use PHP's openssl_pbkdf2 function to convert a passphrase to a key securely.

JQuery show and hide div on mouse click (animate)

That .toggle() method was removed from jQuery in version 1.9. You can do this instead:

$(document).ready(function() {
    $('#showmenu').click(function() {


...but as with the code in your question that would slide up or down. To slide left or right you can do the following:

$(document).ready(function() {
    $('#showmenu').click(function() {


Noting that this requires jQuery-UI's slide effect, but you added that tag to your question so I assume that is OK.

How do I change tab size in Vim?

:set tabstop=4
:set shiftwidth=4
:set expandtab

This will insert four spaces instead of a tab character. Spaces are a bit more “stable”, meaning that text indented with spaces will show up the same in the browser and any other application.

The APK file does not exist on disk

Using Android Studio 2.2.1, I clicked the Sync Project with Gradle Files option, from the dropdown at the top, Tools>Android

Similar, to an answer posted above, see below for a screenshot of how to get to this option.

enter image description here

EF LINQ include multiple and nested entities

You can also try

db.Courses.Include("Modules.Chapters").Single(c => c.Id == id);

Finding median of list in Python

def midme(list1):

    if len(list1)%2>0:
            x = list1[int((len(list1)/2))]
            x = ((list1[int((len(list1)/2))-1])+(list1[int(((len(list1)/2)))]))/2
    return x


top align in html table?

Some CSS :

table td, table td * {
    vertical-align: top;

TypeScript for ... of with index / key?

Or another old school solution:

var someArray = [9, 2, 5];
let i = 0;
for (var item of someArray) {
    console.log(item); // 9,2,5

How to print (using cout) a number in binary form?

Using the std::bitset answers and convenience templates:

#include <iostream>
#include <bitset>
#include <climits>

template<typename T>
struct BinaryForm {
    BinaryForm(const T& v) : _bs(v) {}
    const std::bitset<sizeof(T)*CHAR_BIT> _bs;

template<typename T>
inline std::ostream& operator<<(std::ostream& os, const BinaryForm<T> bf) {
    return os << bf._bs;

Using it like this:

auto c = 'A';
std::cout << "c: " << c << " binary: " << BinaryForm{c} << std::endl;
unsigned x = 1234;
std::cout << "x: " << x << " binary: " << BinaryForm{x} << std::endl;
int64_t z { -1024 };
std::cout << "z: " <<  << " binary: " << BinaryForm{z} << std::endl;

Generates output:

c: A binary: 01000001
x: 1234 binary: 00000000000000000000010011010010
z: -1024 binary: 1111111111111111111111111111111111111111111111111111110000000000

How to Flatten a Multidimensional Array?

Here's a simplistic approach:

$My_Array = array(1,2,array(3,4, array(5,6,7), 8), 9);

function checkArray($value) {
    foreach ($value as $var) {
        if ( is_array($var) ) {
        } else {
            echo $var;


Setting up connection string in ASP.NET to SQL SERVER

You can try this. It is very simple

    <add name="conString" connectionString="Data Source=SQLServerAddress;Initial Catalog=YourDatabaseName; User Id=SQLServerLoginId; Password=SQLServerPassword"/>

Decimal to Hexadecimal Converter in Java

A better solution to convert Decimal To HexaDecimal and this one is less complex

import java.util.Scanner;
public class DecimalToHexa
    public static void main(String ar[])
        Scanner sc=new Scanner(;
        System.out.println("Enter a Decimal number: ");
        int n=sc.nextInt();
            System.out.println("Enter a positive integer");
        int i=0,d=0;
        String hx="",h="";
            d=n%16;`enter code here`
            else if(d==11)h="B";
            else if(d==12)h="C";
            else if(d==13)h="D";
            else if(d==14)h="E";
            else if(d==15)h="F";
            else h=""+d;            
        System.out.println("Equivalent HEXA: "+hx);

Where does flask look for image files?

Is the image file ayrton_senna_movie_wallpaper_by_bashgfx-d4cm6x6.jpg in your static directory? If you move it to your static directory and update your HTML as such:

<img src="/static/ayrton_senna_movie_wallpaper_by_bashgfx-d4cm6x6.jpg">

It should work.

Also, it is worth noting, there is a better way to structure this.

File structure:

from flask import Flask, render_template, url_for
app = Flask(__name__)

@app.route('/index', methods=['GET', 'POST'])
def lionel(): 
    return render_template('index.html')

if __name__ == '__main__':



    <h1>Hi Lionel Messi</h1>

  <img src="{{url_for('static', filename='ayrton_senna_movie_wallpaper_by_bashgfx-d4cm6x6.jpg')}}" />



Doing it this way ensures that you are not hard-coding a URL path for your static assets.

mysqli_connect(): (HY000/2002): No connection could be made because the target machine actively refused it

If you are using a non default MySQL port number then do the following:

  1. Stop your xampp/wamp/etc session
  2. Set port number used by MySQL in under the phpMyAdmin folder.
  3. For example if your MySQL port number is 33747 then paste the following
    $cfg['Servers'][$i]['port'] = 33747;
    under the
    /* Authentication type and info */
  4. Restart Apache and MySQL servers.

Use a loop to plot n charts Python

We can create a for loop and pass all the numeric columns into it. The loop will plot the graphs one by one in separate pane as we are including plt.figure() into it.

import pandas as pd
import seaborn as sns
import numpy as np

numeric_features=[x for x in data.columns if data[x].dtype!="object"]
#taking only the numeric columns from the dataframe.

for i in data[numeric_features].columns:

Group dataframe and get sum AND count?

Just in case you were wondering how to rename columns during aggregation, here's how for

pandas >= 0.25: Named Aggregation

df.groupby('Company Name')['Amount'].agg(MySum='sum', MyCount='count')


df.groupby('Company Name').agg(MySum=('Amount', 'sum'), MyCount=('Amount', 'count'))

                       MySum  MyCount
Company Name                       
Vifor Pharma UK Ltd  4207.93        5

How to set $_GET variable

$_GET contains the keys / values that are passed to your script in the URL.

If you have the following URL :

Then $_GET will contain :

  'a' => string '10' (length=2)
  'b' => string 'plop' (length=4)

Of course, as $_GET is not read-only, you could also set some values from your PHP code, if needed :

$_GET['my_value'] = 'test';

But this doesn't seem like good practice, as $_GET is supposed to contain data from the URL requested by the client.

org.apache.poi.POIXMLException: org.apache.poi.openxml4j.exceptions.InvalidFormatException:

You are trying to read xls with explicit implementation poi classes for xlsx.

G:\Selenium Jar Files\TestData\Data.xls

Either use HSSFWorkbook and HSSFSheet classes or make your implementation more generic by using shared interfaces, like;


XSSFWorkbook workbook = new XSSFWorkbook(file);

To: workbook = WorkbookFactory.create(file);

And Change:

XSSFSheet sheet = workbook.getSheetAt(0);

To: sheet = workbook.getSheetAt(0);

Check if all values of array are equal

Another way with delimited size and organized list:

array1 = [1,2,3]; array2 = [1,2,3];

function isEqual(){

    return array1.toString()==array2.toString();

How can I select all children of an element except the last child?

.nav-menu li:not(:last-child){
    // write some style here

this code should apply the style to all

  • except the last child

  • How to exclude property from Json Serialization

    You can also use the [NonSerialized] attribute

    public struct MySerializableStruct
        public string hiddenField;
        public string normalField;

    From the MS docs:

    Indicates that a field of a serializable class should not be serialized. This class cannot be inherited.

    If you're using Unity for example (this isn't only for Unity) then this works with UnityEngine.JsonUtility

    using UnityEngine;
    MySerializableStruct mss = new MySerializableStruct 
        hiddenField = "foo", 
        normalField = "bar" 
    Debug.Log(JsonUtility.ToJson(mss)); // result: {"normalField":"bar"}

    DTO and DAO concepts and MVC

    DTO is an abbreviation for Data Transfer Object, so it is used to transfer the data between classes and modules of your application.

    • DTO should only contain private fields for your data, getters, setters, and constructors.
    • DTO is not recommended to add business logic methods to such classes, but it is OK to add some util methods.

    DAO is an abbreviation for Data Access Object, so it should encapsulate the logic for retrieving, saving and updating data in your data storage (a database, a file-system, whatever).

    Here is an example of how the DAO and DTO interfaces would look like:

    interface PersonDTO {
        String getName();
        void setName(String name);
    interface PersonDAO {
        PersonDTO findById(long id);
        void save(PersonDTO person);

    The MVC is a wider pattern. The DTO/DAO would be your model in the MVC pattern.
    It tells you how to organize the whole application, not just the part responsible for data retrieval.

    As for the second question, if you have a small application it is completely OK, however, if you want to follow the MVC pattern it would be better to have a separate controller, which would contain the business logic for your frame in a separate class and dispatch messages to this controller from the event handlers.
    This would separate your business logic from the view.

    SQL Server - An expression of non-boolean type specified in a context where a condition is expected, near 'RETURN'

    Your problem might be here:

                                SELECT m.ResourceNo FROM JobMember m
                                JOIN JobTask t ON t.JobTaskNo = m.JobTaskNo
                                WHERE t.TaskManagerNo = @UserResourceNo
                                t.AlternateTaskManagerNo = @UserResourceNo

    try changing to

    OR r.ResourceNo IN
                                SELECT m.ResourceNo FROM JobMember m
                                JOIN JobTask t ON t.JobTaskNo = m.JobTaskNo
                                WHERE t.TaskManagerNo = @UserResourceNo
                                t.AlternateTaskManagerNo = @UserResourceNo

    Call web service in excel

    Yes You Can!

    I worked on a project that did that (see comment). Unfortunately no code samples from that one, but googling revealed these:

    How you can integrate data from several Web services using Excel and VBA

    STEP BY STEP: Consuming Web Services through VBA (Excel or Word)

    VBA: Consume Soap Web Services

    /usr/bin/ld: cannot find

    @Alwin Doss You should provide the -L option before -l. You would have done the other way round probably. Try this :)

    URL for public Amazon S3 bucket

    The URL structure you're referring to is called the REST endpoint, as opposed to the Web Site Endpoint.

    Note: Since this answer was originally written, S3 has rolled out dualstack support on REST endpoints, using new hostnames, while leaving the existing hostnames in place. This is now integrated into the information provided, below.

    If your bucket is really in the us-east-1 region of AWS -- which the S3 documentation formerly referred to as the "US Standard" region, but was subsequently officially renamed to the "U.S. East (N. Virginia) Region" -- then is not the correct form for that endpoint, even though it looks like it should be. The correct format for that region is either or

    The format you're using is applicable to all the other S3 regions, but not US Standard US East (N. Virginia) [us-east-1].

    S3 now also has dual-stack endpoint hostnames for the REST endpoints, and unlike the original endpoint hostnames, the names of these have a consistent format across regions, for example These endpoints support both IPv4 and IPv6 connectivity and DNS resolution, but are otherwise functionally equivalent to the existing REST endpoints.

    If your permissions and configuration are set up such that the web site endpoint works, then the REST endpoint should work, too.

    However... the two endpoints do not offer the same functionality.

    Roughly speaking, the REST endpoint is better-suited for machine access and the web site endpoint is better suited for human access, since the web site endpoint offers friendly error messages, index documents, and redirects, while the REST endpoint doesn't. On the other hand, the REST endpoint offers HTTPS and support for signed URLs, while the web site endpoint doesn't.

    Choose the correct type of endpoint (REST or web site) for your application:

    ¹ has been referred to as the "Northern Virginia endpoint," in contrast to the "Global endpoint" It was unofficially possible to get read-after-write consistency on new objects in this region if the "s3-external-1" hostname was used, because this would send you to a subset of possible physical endpoints that could provide that functionality. This behavior is now officially supported on this endpoint, so this is probably the better choice in many applications. Previously, s3-external-2 had been referred to as the "Pacific Northwest endpoint" for US-Standard, though it is now a CNAME in DNS for s3-external-1 so s3-external-2 appears to have no purpose except backwards-compatibility.

    How to dynamically create generic C# object using reflection?

    Check out this article and this simple example. Quick translation of same to your classes ...

    var d1 = typeof(Task<>);
    Type[] typeArgs = { typeof(Item) };
    var makeme = d1.MakeGenericType(typeArgs);
    object o = Activator.CreateInstance(makeme);

    Per your edit: For that case, you can do this ...

    var d1 = Type.GetType("GenericTest.TaskA`1"); // GenericTest was my namespace, add yours
    Type[] typeArgs = { typeof(Item) };
    var makeme = d1.MakeGenericType(typeArgs);
    object o = Activator.CreateInstance(makeme);

    To see where I came up with backtick1 for the name of the generic class, see this article.

    Note: if your generic class accepts multiple types, you must include the commas when you omit the type names, for example:

    Type type = typeof(IReadOnlyDictionary<,>);

    How can I install packages using pip according to the requirements.txt file from a local directory?

    I had a similar problem. I tried this:

        pip install -U -r requirements.txt

    (-U = update if it had already installed)

    But the problem continued. I realized that some of generic libraries for development were missed.

        sudo apt-get install libtiff5-dev libjpeg8-dev zlib1g-dev liblcms2-dev libwebp-dev tcl8.6-dev tk8.6-dev python-tk

    I don't know if this would help you.

    Could not find module "@angular-devkit/build-angular"

    If the following command does not work,

    npm install --save-dev @angular-devkit/build-angular

    then move to the project folder and run this command:

    npm install --save @angular-devkit/build-angular

    angular 2 sort and filter

    A pipe takes in data as input and transforms it to a desired output. Add this pipe file:orderby.ts inside your /app folder .


    //The pipe class implements the PipeTransform interface's transform method that accepts an input value and an optional array of parameters and returns the transformed value.
    import { Pipe,PipeTransform } from "angular2/core";
    //We tell Angular that this is a pipe by applying the @Pipe decorator which we import from the core Angular library.
      //The @Pipe decorator takes an object with a name property whose value is the pipe name that we'll use within a template expression. It must be a valid JavaScript identifier. Our pipe's name is orderby.
      name: "orderby"
    export class OrderByPipe implements PipeTransform {
      transform(array:Array<any>, args?) {
        // Check if array exists, in this case array contains articles and args is an array that has 1 element : !id
        if(array) {
          // get the first element
          let orderByValue = args[0]
          let byVal = 1
          // check if exclamation point 
          if(orderByValue.charAt(0) == "!") {
            // reverse the array
            byVal = -1
            orderByValue = orderByValue.substring(1)
          array.sort((a: any, b: any) => {
            if(a[orderByValue] < b[orderByValue]) {
              return -1*byVal;
            } else if (a[orderByValue] > b[orderByValue]) {
              return 1*byVal;
            } else {
              return 0;
          return array;

    In your component file (app.component.ts) import the pipe that you just added using: import {OrderByPipe} from './orderby';

    Then, add *ngFor="#article of articles | orderby:'id'" inside your template if you want to sort your articles by id in ascending order or orderby:'!id'" in descending order.

    We add parameters to a pipe by following the pipe name with a colon ( : ) and then the parameter value

    We must list our pipe in the pipes array of the @Component decorator. pipes: [ OrderByPipe ] .


    import {Component, OnInit} from 'angular2/core';
    import {OrderByPipe} from './orderby';
        selector: 'my-app',
        template: `
          <h2>orderby-pipe by N2B</h2>
          <p *ngFor="#article of articles | orderby:'id'">
            Article title : {{article.title}}
        pipes: [ OrderByPipe ]
    export class AppComponent{
            this.articles = [
                id: 1,
                title: "title1"
                id: 2,
                title: "title2",

    More info here on my github and this post on my website