Programs & Examples On #Chi squared

Anything related to chi-squared probability distribution or chi-squared statistical test (typically of distribution, independence, or goodness of fit).

jQuery get the name of a select option

The Code is very Simple, Lets Put This Code

var name = $("#band_type_choices  option:selected").text();

Here You don't want to use $(this).find().text(), directly you can put your id name and add option:selected along with text().

This will return the result option name. Better Try this...

Ascii/Hex convert in bash

Text2Conv="Aa"
for letter in $(echo "$Text2Conv" | sed "s/\(.\)/'\1 /g");do printf '%x' "$letter";done

4161

The trick is using sed to parse the Text2Conv to format we can then seperate anf loop using for.

How can I deserialize JSON to a simple Dictionary<string,string> in ASP.NET?

I added a check for null values in the JSON to the other answer

I had same problem so I wrote this my self. This solution is differentiated from other answers because it can deserialize in to multiple levels.

Just send json string in to deserializeToDictionary function it will return non strongly-typed Dictionary<string, object> object.

private Dictionary<string, object> deserializeToDictionary(string jo)
{
    var values = JsonConvert.DeserializeObject<Dictionary<string, object>>(jo);
    var values2 = new Dictionary<string, object>();
    foreach (KeyValuePair<string, object> d in values)
    {
        if (d.Value != null && d.Value.GetType().FullName.Contains("Newtonsoft.Json.Linq.JObject"))
        {
            values2.Add(d.Key, deserializeToDictionary(d.Value.ToString()));
        }
        else
        {
            values2.Add(d.Key, d.Value);
        }
    }
    return values2;
}

Ex: This will return Dictionary<string, object> object of a Facebook JSON response.

private void button1_Click(object sender, EventArgs e)
{
    string responsestring = "{\"id\":\"721055828\",\"name\":\"Dasun Sameera
        Weerasinghe\",\"first_name\":\"Dasun\",\"middle_name\":\"Sameera\",\"last_name\":\"Weerasinghe\",\"username\":\"dasun\",\"gender\":\"male\",\"locale\":\"en_US\",
        hometown: {id: \"108388329191258\", name: \"Moratuwa, Sri Lanka\",}}";
    Dictionary<string, object> values = deserializeToDictionary(responsestring);
}

Note: hometown further deserialize into a Dictionary<string, object> object.

NuGet Packages are missing

BEWARE - this updates packages for the entire solution not just the project.

If you have one more missing nuget package that giving your error while building your solution use following command using Nuget Command Console from Tools > Nuget Package Manager > Package Manager Console. It will reinstall your all current packages.

Update-Package –reinstall

Update:

You can pass specific project name as a parameter.

Update-Package –reinstall -ProjectName SampleApp

jQuery - Getting form values for ajax POST

var data={
 userName: $('#userName').val(),
 email: $('#email').val(),
 //add other properties similarly
}

and

$.ajax({
        type: "POST",
        url: "http://rt.ja.com/includes/register.php?submit=1",
        data: data

        success: function(html)
        {   
            //alert(html);
            $('#userError').html(html);
            $("#userError").html(userChar);
            $("#userError").html(userTaken);
        }
    });

You dont have to bother about anything else. jquery will handle the serialization etc. also you can append the submit query string parameter submit=1 into the data json object.

unable to remove file that really exists - fatal: pathspec ... did not match any files

I know this is not the OP's problem, but I ran into the same error with an entirely different basis, so I just wanted to drop it here in case anyone else has the same. This is Windows-specific, and I assume does not affect Linux users.

I had a LibreOffice doc file, call it final report.odt. I later changed its case to Final Report.odt. In Windows, this doesn't even count as a rename. final report.odt, Final Report.odt, FiNaL RePoRt.oDt are all the same. In Linux, these are all distinct.

When I eventually went to git rm "Final Report.odt" and got the "pathspec did not match any files" error. Only when I use the original casing at the time the file was added -- git rm "final report.odt" -- did it work.

Lesson learned: to change the case I should have instead done:

git mv "final report.odt" temp.odt
git mv temp.odt "Final Report.odt"

Again, that wasn't the problem for the OP here; and wouldn't affect a Linux user, as his posts shows he clearly is. I'm just including it for others who may have this problem in Windows git and stumble onto this question.

What is an MDF file?

Just to make this absolutely clear for all:

A .MDF file is “typically” a SQL Server data file however it is important to note that it does NOT have to be.

This is because .MDF is nothing more than a recommended/preferred notation but the extension itself does not actually dictate the file type.

To illustrate this, if someone wanted to create their primary data file with an extension of .gbn they could go ahead and do so without issue.

To qualify the preferred naming conventions:

  • .mdf - Primary database data file.
  • .ndf - Other database data files i.e. non Primary.
  • .ldf - Log data file.

How can I get Android Wifi Scan Results into a list?

Find a complete working example below:

The code by @Android is very good but has few issues, namely:

  1. Populating to ListView code needs to be moved to onReceive of BroadCastReceiver where only the result will be available. In the case result is obtained at 2nd attempt.
  2. BroadCastReceiver needs to be unregistered after the results are obtained.
  3. size = size -1 seems unnecessary.

Find below the modified code of @Android as a working example:

WifiScanner.java which is the Main Activity

package com.arjunandroid.wifiscanner;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.wifi.ScanResult;
import android.net.wifi.WifiManager;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class WifiScanner extends Activity implements View.OnClickListener{


    WifiManager wifi;
    ListView lv;
    Button buttonScan;
    int size = 0;
    List<ScanResult> results;

    String ITEM_KEY = "key";
    ArrayList<String> arraylist = new ArrayList<>();
    ArrayAdapter adapter;

    /* Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        getActionBar().setTitle("Widhwan Setup Wizard");

        setContentView(R.layout.activity_wifi_scanner);

        buttonScan = (Button) findViewById(R.id.scan);
        buttonScan.setOnClickListener(this);
        lv = (ListView)findViewById(R.id.wifilist);


        wifi = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);
        if (wifi.isWifiEnabled() == false)
        {
            Toast.makeText(getApplicationContext(), "wifi is disabled..making it enabled", Toast.LENGTH_LONG).show();
            wifi.setWifiEnabled(true);
        }
        this.adapter =  new ArrayAdapter<>(this,android.R.layout.simple_list_item_1,arraylist);
        lv.setAdapter(this.adapter);

        scanWifiNetworks();
    }

    public void onClick(View view)
    {
        scanWifiNetworks();
    }

    private void scanWifiNetworks(){

        arraylist.clear();
        registerReceiver(wifi_receiver, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));

        wifi.startScan();

        Log.d("WifScanner", "scanWifiNetworks");

        Toast.makeText(this, "Scanning....", Toast.LENGTH_SHORT).show();

    }

    BroadcastReceiver wifi_receiver= new BroadcastReceiver()
    {

        @Override
        public void onReceive(Context c, Intent intent)
        {
            Log.d("WifScanner", "onReceive");
            results = wifi.getScanResults();
            size = results.size();
            unregisterReceiver(this);

            try
            {
                while (size >= 0)
                {
                    size--;
                    arraylist.add(results.get(size).SSID);
                    adapter.notifyDataSetChanged();
                }
            }
            catch (Exception e)
            {
                Log.w("WifScanner", "Exception: "+e);

            }


        }
    };

}

activity_wifi_scanner.xml which is the layout file for the Activity

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:padding="10dp"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ListView
        android:id="@+id/wifilist"
        android:layout_width="match_parent"
        android:layout_height="312dp"
        android:layout_weight="0.97" />


    <Button
        android:id="@+id/scan"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_gravity="bottom"
        android:layout_margin="15dp"
        android:background="@android:color/holo_green_light"
        android:text="Scan Again" />
</LinearLayout>

Also as mentioned above, do not forget to add Wifi permissions in the AndroidManifest.xml

<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" /> 

UnmodifiableMap (Java Collections) vs ImmutableMap (Google)

Have a look at ImmutableMap JavaDoc: doc

There is information about that there:

Unlike Collections.unmodifiableMap(java.util.Map), which is a view of a separate map which can still change, an instance of ImmutableMap contains its own data and will never change. ImmutableMap is convenient for public static final maps ("constant maps") and also lets you easily make a "defensive copy" of a map provided to your class by a caller.

jQuery date/time picker

Not jQuery, but it works well for a calendar with time: JavaScript Date Time Picker.

I just bound the click event to pop it up:

$(".arrival-date").click(function() {
    NewCssCal($(this).attr('id'), 'mmddyyyy', 'dropdown', true, 12);
});

SVN 405 Method Not Allowed

If you use code.google.com to host your Subversion repository.

You know below things, right?

If you plan to make changes, use this command to check out the code as yourself using HTTPS:

# Project members authenticate over HTTPS to allow committing changes.
svn checkout https://.../svn/trunk/ user-...

When prompted, enter your generated googlecode.com password.
Use this command to anonymously check out the latest project source code:

# Non-members may check out a read-only working copy anonymously over HTTP.
svn checkout http://.../svn/trunk/ ...-read-only

The error you mentioned exactly you are using Non-members may check out a read-only working copy anonymously over HTTP status. Therefore, you can not commit or do anything so far.

You must use Project members authenticate over HTTPS to allow committing changes thing.

It will be fine now.

How do you get the string length in a batch file?

You can try this code. Fast, you can also include special characters

@echo off
set "str=[string]"
echo %str% > "%tmp%\STR"
for %%P in ("%TMP%\STR") do (set /a strlen=%%~zP-3)
echo String lenght: %strlen%

#1214 - The used table type doesn't support FULLTEXT indexes

Simply do the following:

  1. Open your .sql file with Notepad or Notepad ++

  2. Find InnoDB and Replace all (around 87) with MyISAM

  3. Save and now you can import your database with out error.

How do I install Python libraries in wheel format?

i have write the answer here How to add/use libraries in Python (3.5.1) but no problem will rewrite it again

if u have or you can create a file requirements.txt which contains the libraries that you want to install for ex:

numpy==1.14.2
Pillow==5.1.0

You gonna situate in your folder which contains that requirements.txt in my case the path to my project is

C:\Users\LE\Desktop\Projet2_Sig_Exo3\exo 3\k-means

now just type

python -m pip install -r ./requirements.txt

and all the libararies that you want gonna install

C:\Users\LE\Desktop\Projet2_Sig_Exo3\exo 3\k-means>python -m pip install -r ./requirements.txt

Connect to Amazon EC2 file directory using Filezilla and SFTP

I've created a video tutorial for this. Just check:

Connect to Amazon EC2 file directory using FileZilla and SFTP, Video Tutorial

Summary of above video tutorial:

  1. Edit (Preferences) > Settings > Connection > SFTP, Click "Add key file”
  2. Browse to the location of your .pem file and select it.
  3. A message box will appear asking your permission to convert the file into ppk format. Click Yes, then give the file a name and store it somewhere.
  4. If the new file is shown in the list of Keyfiles, then continue to the next step. If not, then click "Add keyfile..." and select the converted file.
  5. File > Site Manager Add a new site with the following parameters:

    Host: Your public DNS name of your EC2 instance, or the public IP address of the server.

    Protocol: SFTP

    Logon Type: Normal

    User: From the docs: "For Amazon Linux, the default user name is ec2-user. For RHEL5, the user name is often root but might be ec2-user. For Ubuntu, the user name is ubuntu. For SUSE Linux, the user name is root. For Debian, the user name is admin. Otherwise, check with your AMI provider."

    Press Connect Button - If saving of passwords has been disabled, you will be prompted that the logon type will be changed to 'Ask for password'. Say 'OK' and when connecting, at the password prompt push 'OK' without entering a password to proceed past the dialog.

    Note: FileZilla automatically figures out which key to use. You do not need to specify the key after importing it as described above.

If you use Cyberduck follow this.

Check this post if you have any permission issues.

An attempt was made to access a socket in a way forbidden by its access permissions

Not surprisingly, this error can arise when another process is listening on the desired port. This happened today when I started an instance of the Apache Web server, listening on its default port (80), having forgotten that I already had IIS 7 running, and listening on that port. This is well explained in Port 80 is being used by SYSTEM (PID 4), what is that? Better yet, that article points to Stop http.sys from listening on port 80 in Windows, which explains a very simple way to resolve it, with just a tad of help from an elevated command prompt and a one-line edit of my hosts file.

Add horizontal scrollbar to html table

I couldn't get any of the above solutions to work. However, I found a hack:

_x000D_
_x000D_
body {_x000D_
  background-color: #ccc;_x000D_
}_x000D_
_x000D_
.container {_x000D_
  width: 300px;_x000D_
  background-color: white;_x000D_
}_x000D_
_x000D_
table {_x000D_
  width: 100%;_x000D_
  border-collapse: collapse;_x000D_
}_x000D_
_x000D_
td {_x000D_
  border: 1px solid black;_x000D_
}_x000D_
_x000D_
/* try removing the "hack" below to see how the table overflows the .body */_x000D_
.hack1 {_x000D_
  display: table;_x000D_
  table-layout: fixed;_x000D_
  width: 100%;_x000D_
}_x000D_
_x000D_
.hack2 {_x000D_
  display: table-cell;_x000D_
  overflow-x: auto;_x000D_
  width: 100%;_x000D_
}
_x000D_
<div class="container">_x000D_
_x000D_
  <div class="hack1">_x000D_
    <div class="hack2">_x000D_
_x000D_
      <table>_x000D_
        <tr>_x000D_
          <td>table or other arbitrary content</td>_x000D_
          <td>that will cause your page to stretch</td>_x000D_
        </tr>_x000D_
        <tr>_x000D_
          <td>uncontrollably</td>_x000D_
          <td>xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx</td>_x000D_
        </tr>_x000D_
      </table>_x000D_
_x000D_
    </div>_x000D_
  </div>_x000D_
_x000D_
</div>
_x000D_
_x000D_
_x000D_

R: Print list to a text file

depending on your tastes, an alternative to nico's answer:

d<-lapply(mylist, write, file=" ... ", append=T);

HttpContext.Current.Request.Url.Host what it returns?

The Host property will return the domain name you used when accessing the site. So, in your development environment, since you're requesting

http://localhost:950/m/pages/Searchresults.aspx?search=knife&filter=kitchen

It's returning localhost. You can break apart your URL like so:

Protocol: http
Host: localhost
Port: 950
PathAndQuery: /m/pages/SearchResults.aspx?search=knight&filter=kitchen

Detect Route Change with react-router

Update for React Router 5.1+.

import React from 'react';
import { useLocation, Switch } from 'react-router-dom'; 

const App = () => {
  const location = useLocation();

  React.useEffect(() => {
    console.log('Location changed');
  }, [location]);

  return (
    <Switch>
      {/* Routes go here */}
    </Switch>
  );
};

Is try-catch like error handling possible in ASP Classic?

A rather nice way to handle this for missing COM classes:

Dim o:Set o = Nothing
On Error Resume Next
Set o = CreateObject("foo.bar")
On Error Goto 0
If o Is Nothing Then
  Response.Write "Oups, foo.bar isn't installed on this server!"
Else
  Response.Write "Foo bar found, yay."
End If

$ is not a function - jQuery error

There are quite lots of answer based on situation.

1) Try to replace '$' with "jQuery"

2) Check that code you are executed are always below the main jquery script.

<script src="http://code.jquery.com/jquery-1.11.3.min.js"></script>
<script type="text/javascript">
jQuery(document).ready(function(){

});
</script>

3) Pass $ into the function and add "jQuery" as a main function like below.

<script type="text/javascript">
jQuery(document).ready(function($){

});
</script>

img onclick call to JavaScript function

Well your onclick function works absolutely fine its your this line
window.external.values(a.value, b.value, c.value, d.value, e.value);

window.external is object and has no method name values

<html>
    <head>
     <script type="text/javascript">
          function exportToForm(a,b,c,d,e) {
             // window.external.values(a.value, b.value, c.value, d.value, e.value);
          //use alert to check its working 
         alert("HELLO");
}
      </script>
    </head>
    <body>
      <img onclick="exportToForm('1.6','55','10','50','1');" src="China-Flag-256.png"/>
      <button onclick="exportToForm('1.6','55','10','50','1');" style="background-color: #00FFFF">Export</button>
    </body>

    </html>

Get value from input (AngularJS)

If you want to get values in Javascript on frontend, you can use the native way to do it by using :

document.getElementsByName("movie")[0].value;

Where "movie" is the name of your input <input type="text" name="movie">

If you want to get it on angular.js controller, you can use;

$scope.movie

Java List.contains(Object with field value equal to x)

Predicate

If you dont use Java 8, or library which gives you more functionality for dealing with collections, you could implement something which can be more reusable than your solution.

interface Predicate<T>{
        boolean contains(T item);
    }

    static class CollectionUtil{

        public static <T> T find(final Collection<T> collection,final  Predicate<T> predicate){
            for (T item : collection){
                if (predicate.contains(item)){
                    return item;
                }
            }
            return null;
        }
    // and many more methods to deal with collection    
    }

i'm using something like that, i have predicate interface, and i'm passing it implementation to my util class.

What is advantage of doing this in my way? you have one method which deals with searching in any type collection. and you dont have to create separate methods if you want to search by different field. alll what you need to do is provide different predicate which can be destroyed as soon as it no longer usefull/

if you want to use it, all what you need to do is call method and define tyour predicate

CollectionUtil.find(list, new Predicate<MyObject>{
    public boolean contains(T item){
        return "John".equals(item.getName());
     }
});

parsing a tab-separated file in Python

I don't think any of the current answers really do what you said you want. (Correction: I now see that @Gareth Latty / @Lattyware has incorporated my answer into his own as an "Edit" near the end.)

Anyway, here's my take:

Say these are the tab-separated values in your input file:

1   2   3   4   5
6   7   8   9   10
11  12  13  14  15
16  17  18  19  20

then this:

with open("tab-separated-values.txt") as inp:
    print( list(zip(*(line.strip().split('\t') for line in inp))) )

would produce the following:

[('1', '6', '11', '16'), 
 ('2', '7', '12', '17'), 
 ('3', '8', '13', '18'), 
 ('4', '9', '14', '19'), 
 ('5', '10', '15', '20')]

As you can see, it put the k-th element of each row into the k-th array.

Date constructor returns NaN in IE, but works in Firefox and Chrome

Here's my approach:

var parseDate = function(dateArg) {
    var dateValues = dateArg.split('-');
    var date = new Date(dateValues[0],dateValues[1],dateValues[2]);
    return date.format("m/d/Y");
}

replace ('-') with the delimeter you're using.

Where does this come from: -*- coding: utf-8 -*-

# -*- coding: utf-8 -*- is a Python 2 thing. In Python 3+, the default encoding of source files is already UTF-8 and that line is useless.

See: Should I use encoding declaration in Python 3?

pyupgrade is a tool you can run on your code to remove those comments and other no-longer-useful leftovers from Python 2, like having all your classes inherit from object.

<SELECT multiple> - how to allow only one item selected?

Just don't make it a select multiple, but set a size to it, such as:

  <select name="user" id="userID" size="3">
    <option>John</option>
    <option>Paul</option>
    <option>Ringo</option>
    <option>George</option>
  </select>

Working example: https://jsfiddle.net/q2vo8nge/

How can I pass a list as a command-line argument with argparse?

TL;DR

Use the nargs option or the 'append' setting of the action option (depending on how you want the user interface to behave).

nargs

parser.add_argument('-l','--list', nargs='+', help='<Required> Set flag', required=True)
# Use like:
# python arg.py -l 1234 2345 3456 4567

nargs='+' takes 1 or more arguments, nargs='*' takes zero or more.

append

parser.add_argument('-l','--list', action='append', help='<Required> Set flag', required=True)
# Use like:
# python arg.py -l 1234 -l 2345 -l 3456 -l 4567

With append you provide the option multiple times to build up the list.

Don't use type=list!!! - There is probably no situation where you would want to use type=list with argparse. Ever.


Let's take a look in more detail at some of the different ways one might try to do this, and the end result.

import argparse

parser = argparse.ArgumentParser()

# By default it will fail with multiple arguments.
parser.add_argument('--default')

# Telling the type to be a list will also fail for multiple arguments,
# but give incorrect results for a single argument.
parser.add_argument('--list-type', type=list)

# This will allow you to provide multiple arguments, but you will get
# a list of lists which is not desired.
parser.add_argument('--list-type-nargs', type=list, nargs='+')

# This is the correct way to handle accepting multiple arguments.
# '+' == 1 or more.
# '*' == 0 or more.
# '?' == 0 or 1.
# An int is an explicit number of arguments to accept.
parser.add_argument('--nargs', nargs='+')

# To make the input integers
parser.add_argument('--nargs-int-type', nargs='+', type=int)

# An alternate way to accept multiple inputs, but you must
# provide the flag once per input. Of course, you can use
# type=int here if you want.
parser.add_argument('--append-action', action='append')

# To show the results of the given option to screen.
for _, value in parser.parse_args()._get_kwargs():
    if value is not None:
        print(value)

Here is the output you can expect:

$ python arg.py --default 1234 2345 3456 4567
...
arg.py: error: unrecognized arguments: 2345 3456 4567

$ python arg.py --list-type 1234 2345 3456 4567
...
arg.py: error: unrecognized arguments: 2345 3456 4567

$ # Quotes won't help here... 
$ python arg.py --list-type "1234 2345 3456 4567"
['1', '2', '3', '4', ' ', '2', '3', '4', '5', ' ', '3', '4', '5', '6', ' ', '4', '5', '6', '7']

$ python arg.py --list-type-nargs 1234 2345 3456 4567
[['1', '2', '3', '4'], ['2', '3', '4', '5'], ['3', '4', '5', '6'], ['4', '5', '6', '7']]

$ python arg.py --nargs 1234 2345 3456 4567
['1234', '2345', '3456', '4567']

$ python arg.py --nargs-int-type 1234 2345 3456 4567
[1234, 2345, 3456, 4567]

$ # Negative numbers are handled perfectly fine out of the box.
$ python arg.py --nargs-int-type -1234 2345 -3456 4567
[-1234, 2345, -3456, 4567]

$ python arg.py --append-action 1234 --append-action 2345 --append-action 3456 --append-action 4567
['1234', '2345', '3456', '4567']

Takeaways:

  • Use nargs or action='append'
    • nargs can be more straightforward from a user perspective, but it can be unintuitive if there are positional arguments because argparse can't tell what should be a positional argument and what belongs to the nargs; if you have positional arguments then action='append' may end up being a better choice.
    • The above is only true if nargs is given '*', '+', or '?'. If you provide an integer number (such as 4) then there will be no problem mixing options with nargs and positional arguments because argparse will know exactly how many values to expect for the option.
  • Don't use quotes on the command line1
  • Don't use type=list, as it will return a list of lists
    • This happens because under the hood argparse uses the value of type to coerce each individual given argument you your chosen type, not the aggregate of all arguments.
    • You can use type=int (or whatever) to get a list of ints (or whatever)

1: I don't mean in general.. I mean using quotes to pass a list to argparse is not what you want.

%i or %d to print integer in C using printf()?

d and i conversion specifiers behave the same with fprintf but behave differently for fscanf.

As some other wrote in their answer, the idiomatic way to print an int is using d conversion specifier.

Regarding i specifier and fprintf, C99 Rationale says that:

The %i conversion specifier was added in C89 for programmer convenience to provide symmetry with fscanf’s %i conversion specifier, even though it has exactly the same meaning as the %d conversion specifier when used with fprintf.

What is the shortcut in IntelliJ IDEA to find method / functions?

Ctrl + Shift + Alt+ 7 after selecting the method

Get div to take up 100% body height, minus fixed-height header and footer

As far as it is not cross browser solution, you might be take advantage of using calc(expression) to achive that.

html, body { 
 height: 100%;
}
header {        
 height: 50px;
 background-color: tomato
}

#content { 
 height: -moz-calc(100% - 100px); /* Firefox */
 height: -webkit-calc(100% - 100px); /* Chrome, Safari */
 height: calc(100% - 100px); /* IE9+ and future browsers */
 background-color: yellow 
}
footer { 
 height: 50px;
 background-color: grey;
}

Example at JsFiddle

If you want to know more about calc(expression) you'd better to visit this site.

c++ string array initialization

In C++11 you can. A note beforehand: Don't new the array, there's no need for that.

First, string[] strArray is a syntax error, that should either be string* strArray or string strArray[]. And I assume that it's just for the sake of the example that you don't pass any size parameter.

#include <string>

void foo(std::string* strArray, unsigned size){
  // do stuff...
}

template<class T>
using alias = T;

int main(){
  foo(alias<std::string[]>{"hi", "there"}, 2);
}

Note that it would be better if you didn't need to pass the array size as an extra parameter, and thankfully there is a way: Templates!

template<unsigned N>
void foo(int const (&arr)[N]){
  // ...
}

Note that this will only match stack arrays, like int x[5] = .... Or temporary ones, created by the use of alias above.

int main(){
  foo(alias<int[]>{1, 2, 3});
}

Excel VBA select range at last row and column

Is this what you are trying? I have commented the code so that you will not have any problem understanding it.

Sub Sample()
    Dim ws As Worksheet
    Dim lRow As Long, lCol As Long
    Dim rng As Range

    '~~> Set this to the relevant worksheet
    Set ws = [Sheet1]

    With ws
        '~~> Get the last row and last column
        lRow = .Range("A" & .Rows.Count).End(xlUp).Row
        lCol = .Cells(1, .Columns.Count).End(xlToLeft).Column

        '~~> Set the range
        Set rng = .Range(.Cells(lRow, 1), .Cells(lRow, lCol))

        With rng
            Debug.Print .Address
            '
            '~~> What ever you want to do with the address
            '
        End With
    End With
End Sub

BTW I am assuming that LastRow is the same for all rows and same goes for the columns. If that is not the case then you will have use .Find to find the Last Row and the Last Column. You might want to see THIS

Javascript Print iframe contents only

You can use this command:

document.getElementById('iframeid').contentWindow.print();

This command basically is the same as window.print(), but as the window we would like to print is in the iframe, we first need to obtain an instance of that window as a javascript object.

So, in reference to that iframe, we first obtain the iframe by using it's id, and then it's contentWindow returns a window(DOM) object. So, we are able to directly use the window.print() function on this object.

iOS8 Beta Ad-Hoc App Download (itms-services)

If you have already installed app on your device, try to change bundle identifer on the web .plist (not app plist) with something else like "com.vistair.docunet-test2", after that refresh webpage and try to reinstall... It works for me

OS X cp command in Terminal - No such file or directory

I know this question has already been answered, but another option is simply to open the destination and source folders in Finder and then drag and drop them into the terminal. The paths will automatically be copied and properly formatted (thus negating the need to actually figure out proper file names/extensions).

I have to do over-network copies between Mac and Windows machines, sometimes fairly deep down in filetrees, and have found this the most effective way to do so.

So, as an example:

cp -r [drag and drop source folder from finder] [drag and drop destination folder from finder]

python pandas extract year from datetime: df['year'] = df['date'].year is not working

When to use dt accessor

A common source of confusion revolves around when to use .year and when to use .dt.year.

The former is an attribute for pd.DatetimeIndex objects; the latter for pd.Series objects. Consider this dataframe:

df = pd.DataFrame({'Dates': pd.to_datetime(['2018-01-01', '2018-10-20', '2018-12-25'])},
                  index=pd.to_datetime(['2000-01-01', '2000-01-02', '2000-01-03']))

The definition of the series and index look similar, but the pd.DataFrame constructor converts them to different types:

type(df.index)     # pandas.tseries.index.DatetimeIndex
type(df['Dates'])  # pandas.core.series.Series

The DatetimeIndex object has a direct year attribute, while the Series object must use the dt accessor. Similarly for month:

df.index.month               # array([1, 1, 1])
df['Dates'].dt.month.values  # array([ 1, 10, 12], dtype=int64)

A subtle but important difference worth noting is that df.index.month gives a NumPy array, while df['Dates'].dt.month gives a Pandas series. Above, we use pd.Series.values to extract the NumPy array representation.

What does InitializeComponent() do, and how does it work in WPF?

The call to InitializeComponent() (which is usually called in the default constructor of at least Window and UserControl) is actually a method call to the partial class of the control (rather than a call up the object hierarchy as I first expected).

This method locates a URI to the XAML for the Window/UserControl that is loading, and passes it to the System.Windows.Application.LoadComponent() static method. LoadComponent() loads the XAML file that is located at the passed in URI, and converts it to an instance of the object that is specified by the root element of the XAML file.

In more detail, LoadComponent creates an instance of the XamlParser, and builds a tree of the XAML. Each node is parsed by the XamlParser.ProcessXamlNode(). This gets passed to the BamlRecordWriter class. Some time after this I get a bit lost in how the BAML is converted to objects, but this may be enough to help you on the path to enlightenment.

Note: Interestingly, the InitializeComponent is a method on the System.Windows.Markup.IComponentConnector interface, of which Window/UserControl implement in the partial generated class.

Hope this helps!

Ruby Hash to array of values

It is as simple as

hash.values
#=> [["a", "b", "c"], ["b", "c"]]

this will return a new array populated with the values from hash

if you want to store that new array do

array_of_values = hash.values
#=> [["a", "b", "c"], ["b", "c"]]

array_of_values
 #=> [["a", "b", "c"], ["b", "c"]]

With jQuery, how do I capitalize the first letter of a text field while the user is still editing that field?

this will help you in - convert first letter of each word to uppercase

<script>
  /* convert First Letter UpperCase */
  $('#txtField').on('keyup', function (e) {
    var txt = $(this).val();
    $(this).val(txt.replace(/^(.)|\s(.)/g, function ($1) {
      return $1.toUpperCase( );
    }));
  });
</script>

Example : this is a title case sentence -> This Is A Title Case Sentence

How do you express binary literals in Python?

I've tried this in Python 3.6.9

Convert Binary to Decimal

>>> 0b101111
47

>>> int('101111',2)
47

Convert Decimal to binary

>>> bin(47)
'0b101111'

Place a 0 as the second parameter python assumes it as decimal.

>>> int('101111',0)
101111

merge two object arrays with Angular 2 and TypeScript?

try this

 data => {
                this.results = [...this.results, ...data.results];
                this._next = data.next;
            }

How do I install the Nuget provider for PowerShell on a unconnected machine so I can install a nuget package from the PS command line?

The provider is bundled with PowerShell>=6.0.

If all you need is a way to install a package from a file, just grab the .msi installer for the latest version from the github releases page, copy it over to the machine, install it and use it.

Session 'app': Error Installing APK

If you are using android emulator, try changing a device.

Python to print out status bar and percentage

I came upon this thread today and after having tried out this solution from Mark Rushakoff

from time import sleep
import sys

for i in range(21):
sys.stdout.write('\r')
# the exact output you're looking for:
sys.stdout.write("[%-20s] %d%%" % ('='*i, 5*i))
sys.stdout.flush()
sleep(0.25)

I can say that this works fine on W7-64 with python 3.4.3 64-bit but only in the native console. However when using the built-in console of spyder 3.0.0dev, the line breaks are still/again present. As this took me some time to figure out, I'd like to report this observation here.

How to get HTTP response code for a URL in Java?

Try this piece of code which is checking the 400 error messages

huc = (HttpURLConnection)(new URL(url).openConnection());

huc.setRequestMethod("HEAD");

huc.connect();

respCode = huc.getResponseCode();

if(respCode >= 400) {
    System.out.println(url+" is a broken link");
} else {
    System.out.println(url+" is a valid link");
}

orderBy multiple fields in Angular

Created Pipe for sorting. Accepts both string and array of strings, sorting by multiple values. Works for Angular (not AngularJS). Supports both sort for string and numbers.

@Pipe({name: 'orderBy'})
export class OrderBy implements PipeTransform {
    transform(array: any[], filter: any): any[] {
        if(typeof filter === 'string') {
            return this.sortAray(array, filter)
        } else {
            for (var i = filter.length -1; i >= 0; i--) {
                array = this.sortAray(array, filter[i]);
            }

            return array;
        }
    }

    private sortAray(array, field) {
        return array.sort((a, b) => {
            if(typeof a[field] !== 'string') {
                a[field] !== b[field] ? a[field] < b[field] ? -1 : 1 : 0
            } else {
                a[field].toLowerCase() !== b[field].toLowerCase() ? a[field].toLowerCase() < b[field].toLowerCase() ? -1 : 1 : 0
            }
        });
    }
}

Gradle failed to resolve library in Android Studio

Solved by using "http://jcenter.bintray.com/" instead of "https://jcenter.bintray.com/".

repositories {
    jcenter( { url "http://jcenter.bintray.com/" } )
}

How to use curl to get a GET request exactly same as using Chrome?

If you need to set the user header string in the curl request, you can use the -H option to set user agent like:

curl -H "user-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.182 Safari/537.36" http://stackoverflow.com/questions/28760694/how-to-use-curl-to-get-a-get-request-exactly-same-as-using-chrome

Updated user-agent form newest Chrome at 02-22-2021


Using a proxy tool like Charles Proxy really helps make short work of something like what you are asking. Here is what I do, using this SO page as an example (as of July 2015 using Charles version 3.10):

  1. Get Charles Proxy running
  2. Make web request using browser
  3. Find desired request in Charles Proxy
  4. Right click on request in Charles Proxy
  5. Select 'Copy cURL Request'

Copy cURL Request example in Charles 3.10.2

You now have a cURL request you can run in a terminal that will mirror the request your browser made. Here is what my request to this page looked like (with the cookie header removed):

curl -H "Host: stackoverflow.com" -H "Cache-Control: max-age=0" -H "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8" -H "User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.89 Safari/537.36" -H "HTTPS: 1" -H "DNT: 1" -H "Referer: https://www.google.com/" -H "Accept-Language: en-US,en;q=0.8,en-GB;q=0.6,es;q=0.4" -H "If-Modified-Since: Thu, 23 Jul 2015 20:31:28 GMT" --compressed http://stackoverflow.com/questions/28760694/how-to-use-curl-to-get-a-get-request-exactly-same-as-using-chrome

How to use LINQ Distinct() with multiple fields

Employee emp1 = new Employee() { ID = 1, Name = "Narendra1", Salary = 11111, Experience = 3, Age = 30 };Employee emp2 = new Employee() { ID = 2, Name = "Narendra2", Salary = 21111, Experience = 10, Age = 38 };
Employee emp3 = new Employee() { ID = 3, Name = "Narendra3", Salary = 31111, Experience = 4, Age = 33 };
Employee emp4 = new Employee() { ID = 3, Name = "Narendra4", Salary = 41111, Experience = 7, Age = 33 };

List<Employee> lstEmployee = new List<Employee>();

lstEmployee.Add(emp1);
lstEmployee.Add(emp2);
lstEmployee.Add(emp3);
lstEmployee.Add(emp4);

var eemmppss=lstEmployee.Select(cc=>new {cc.ID,cc.Age}).Distinct();

How to pass "Null" (a real surname!) to a SOAP web service in ActionScript 3

@doc_180 had the right concept, except he is focused on numbers, whereas the original poster had issues with strings.

The solution is to change the mx.rpc.xml.XMLEncoder file. This is line 121:

    if (content != null)
        result += content;

(I looked at Flex 4.5.1 SDK; line numbers may differ in other versions.)

Basically, the validation fails because 'content is null' and therefore your argument is not added to the outgoing SOAP Packet; thus causing the missing parameter error.

You have to extend this class to remove the validation. Then there is a big snowball up the chain, modifying SOAPEncoder to use your modified XMLEncoder, and then modifying Operation to use your modified SOAPEncoder, and then moidfying WebService to use your alternate Operation class.

I spent a few hours on it, but I need to move on. It'll probably take a day or two.

You may be able to just fix the XMLEncoder line and do some monkey patching to use your own class.

I'll also add that if you switch to using RemoteObject/AMF with ColdFusion, the null is passed without problems.


11/16/2013 update:

I have one more recent addition to my last comment about RemoteObject/AMF. If you are using ColdFusion 10; then properties with a null value on an object are removed from the server-side object. So, you have to check for the properties existence before accessing it or you will get a runtime error.

Check like this:

<cfif (structKeyExists(arguments.myObject,'propertyName')>
 <!--- no property code --->
<cfelse>
 <!--- handle property  normally --->
</cfif>

This is a change in behavior from ColdFusion 9; where the null properties would turn into empty strings.


Edit 12/6/2013

Since there was a question about how nulls are treated, here is a quick sample application to demonstrate how a string "null" will relate to the reserved word null.

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
               xmlns:s="library://ns.adobe.com/flex/spark"
               xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600" initialize="application1_initializeHandler(event)">
    <fx:Script>
        <![CDATA[
            import mx.events.FlexEvent;

            protected function application1_initializeHandler(event:FlexEvent):void
            {
                var s :String = "null";
                if(s != null){
                    trace('null string is not equal to null reserved word using the != condition');
                } else {
                    trace('null string is equal to null reserved word using the != condition');
                }

                if(s == null){
                    trace('null string is equal to null reserved word using the == condition');
                } else {
                    trace('null string is not equal to null reserved word using the == condition');
                }

                if(s === null){
                    trace('null string is equal to null reserved word using the === condition');
                } else {
                    trace('null string is not equal to null reserved word using the === condition');
                }
            }
        ]]>
    </fx:Script>
    <fx:Declarations>
        <!-- Place non-visual elements (e.g., services, value objects) here -->
    </fx:Declarations>
</s:Application>

The trace output is:

null string is not equal to null reserved word using the != condition

null string is not equal to null reserved word using the == condition

null string is not equal to null reserved word using the === condition

OAuth2 and Google API: access token expiration time?

You shouldn't design your application based on specific lifetimes of access tokens. Just assume they are (very) short lived.

However, after a successful completion of the OAuth2 installed application flow, you will get back a refresh token. This refresh token never expires, and you can use it to exchange it for an access token as needed. Save the refresh tokens, and use them to get access tokens on-demand (which should then immediately be used to get access to user data).

EDIT: My comments above notwithstanding, there are two easy ways to get the access token expiration time:

  1. It is a parameter in the response (expires_in)when you exchange your refresh token (using /o/oauth2/token endpoint). More details.
  2. There is also an API that returns the remaining lifetime of the access_token:

    https://www.googleapis.com/oauth2/v1/tokeninfo?access_token={accessToken}

    This will return a json array that will contain an expires_in parameter, which is the number of seconds left in the lifetime of the token.

angularjs - using {{}} binding inside ng-src but ng-src doesn't load

Changing the ng-src value is actually very simple. Like this:

<html ng-app>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.0.6/angular.min.js"></script>
</head>
<body>
<img ng-src="{{img_url}}">
<button ng-click="img_url = 'https://farm4.staticflickr.com/3261/2801924702_ffbdeda927_d.jpg'">Click</button>
</body>
</html>

Here is a jsFiddle of a working example: http://jsfiddle.net/Hx7B9/2/

How to bind RadioButtons to an enum?

You could use a more generic converter

public class EnumBooleanConverter : IValueConverter
{
  #region IValueConverter Members
  public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
  {
    string parameterString = parameter as string;
    if (parameterString == null)
      return DependencyProperty.UnsetValue;

    if (Enum.IsDefined(value.GetType(), value) == false)
      return DependencyProperty.UnsetValue;

    object parameterValue = Enum.Parse(value.GetType(), parameterString);

    return parameterValue.Equals(value);
  }

  public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
  {
    string parameterString = parameter as string;
    if (parameterString == null)
        return DependencyProperty.UnsetValue;

    return Enum.Parse(targetType, parameterString);
  }
  #endregion
}

And in the XAML-Part you use:

<Grid>
    <Grid.Resources>
      <l:EnumBooleanConverter x:Key="enumBooleanConverter" />
    </Grid.Resources>
    <StackPanel >
      <RadioButton IsChecked="{Binding Path=VeryLovelyEnum, Converter={StaticResource enumBooleanConverter}, ConverterParameter=FirstSelection}">first selection</RadioButton>
      <RadioButton IsChecked="{Binding Path=VeryLovelyEnum, Converter={StaticResource enumBooleanConverter}, ConverterParameter=TheOtherSelection}">the other selection</RadioButton>
      <RadioButton IsChecked="{Binding Path=VeryLovelyEnum, Converter={StaticResource enumBooleanConverter}, ConverterParameter=YetAnotherOne}">yet another one</RadioButton>
    </StackPanel>
</Grid>

What command means "do nothing" in a conditional in Bash?

Although I'm not answering the original question concering the no-op command, many (if not most) problems when one may think "in this branch I have to do nothing" can be bypassed by simply restructuring the logic so that this branch won't occur.

I try to give a general rule by using the OPs example

do nothing when $a is greater than "10", print "1" if $a is less than "5", otherwise, print "2"

we have to avoid a branch where $a gets more than 10, so $a < 10 as a general condition can be applied to every other, following condition.

In general terms, when you say do nothing when X, then rephrase it as avoid a branch where X. Usually you can make the avoidance happen by simply negating X and applying it to all other conditions.

So the OPs example with the rule applied may be restructured as:

if [ "$a" -lt 10 ] && [ "$a" -le 5 ]
then
    echo "1"
elif [ "$a" -lt 10 ]
then
    echo "2"
fi

Just a variation of the above, enclosing everything in the $a < 10 condition:

if [ "$a" -lt 10 ]
then
    if [ "$a" -le 5 ]
    then
        echo "1"
    else
        echo "2"
    fi
fi

(For this specific example @Flimzys restructuring is certainly better, but I wanted to give a general rule for all the people searching how to do nothing.)

Identifier not found error on function call

You have to define void swapCase before the main definition.

Deserialize json object into dynamic object using Json.net

If you use JSON.NET with old version which didn't JObject.

This is another simple way to make a dynamic object from JSON: https://github.com/chsword/jdynamic

NuGet Install

PM> Install-Package JDynamic

Support using string index to access member like:

dynamic json = new JDynamic("{a:{a:1}}");
Assert.AreEqual(1, json["a"]["a"]);

Test Case

And you can use this util as following :

Get the value directly

dynamic json = new JDynamic("1");

//json.Value

2.Get the member in the json object

dynamic json = new JDynamic("{a:'abc'}");
//json.a is a string "abc"

dynamic json = new JDynamic("{a:3.1416}");
//json.a is 3.1416m

dynamic json = new JDynamic("{a:1}");
//json.a is integer: 1

3.IEnumerable

dynamic json = new JDynamic("[1,2,3]");
/json.Length/json.Count is 3
//And you can use json[0]/ json[2] to get the elements

dynamic json = new JDynamic("{a:[1,2,3]}");
//json.a.Length /json.a.Count is 3.
//And you can use  json.a[0]/ json.a[2] to get the elements

dynamic json = new JDynamic("[{b:1},{c:1}]");
//json.Length/json.Count is 2.
//And you can use the  json[0].b/json[1].c to get the num.

Other

dynamic json = new JDynamic("{a:{a:1} }");

//json.a.a is 1.

PyTorch: How to get the shape of a Tensor as a list of int

For PyTorch v1.0 and possibly above:

>>> import torch
>>> var = torch.tensor([[1,0], [0,1]])

# Using .size function, returns a torch.Size object.
>>> var.size()
torch.Size([2, 2])
>>> type(var.size())
<class 'torch.Size'>

# Similarly, using .shape
>>> var.shape
torch.Size([2, 2])
>>> type(var.shape)
<class 'torch.Size'>

You can cast any torch.Size object to a native Python list:

>>> list(var.size())
[2, 2]
>>> type(list(var.size()))
<class 'list'>

In PyTorch v0.3 and 0.4:

Simply list(var.size()), e.g.:

>>> import torch
>>> from torch.autograd import Variable
>>> from torch import IntTensor
>>> var = Variable(IntTensor([[1,0],[0,1]]))

>>> var
Variable containing:
 1  0
 0  1
[torch.IntTensor of size 2x2]

>>> var.size()
torch.Size([2, 2])

>>> list(var.size())
[2, 2]

How to import jquery using ES6 syntax?

If it helps anyone, javascript import statements are hoisted. Thus, if a library has a dependency (eg bootstrap) on jquery in the global namespace (window), this will NOT work:

import {$,jQuery} from 'jquery';
window.$ = $;
window.jQuery = jQuery;
import 'bootstrap/dist/js/bootstrap.min';

This is because the import of bootstrap is hoisted and evaluated before jQuery is attached to window.

One way to get around this is to not import jQuery directly, but instead import a module which itself imports jQuery AND attaches it to the window.

import jQuery from './util/leaked-jquery';
import 'bootstrap/dist/js/bootstrap.min';

where leaked-jquery looks like

import {$,jQuery} from 'jquery';
window.$ = $;
window.jQuery = jQuery;
export default $;
export jQuery;

EG, https://github.com/craigmichaelmartin/weather-app--birch/blob/4d9f3b03719e0a2ea3fb5ddbbfc453a10e9843c6/javascript/util/leak_jquery.js

When using Trusted_Connection=true and SQL Server authentication, will this affect performance?

This will probably have some performance costs when creating the connection but as connections are pooled, they are created only once and then reused, so it won't make any difference to your application. But as always: measure it.


UPDATE:

There are two authentication modes:

  1. Windows Authentication mode (corresponding to a trusted connection). Clients need to be members of a domain.
  2. SQL Server Authentication mode. Clients are sending username/password at each connection

How do you find the row count for all your tables in Postgres

Not sure if an answer in bash is acceptable to you, but FWIW...

PGCOMMAND=" psql -h localhost -U fred -d mydb -At -c \"
            SELECT   table_name
            FROM     information_schema.tables
            WHERE    table_type='BASE TABLE'
            AND      table_schema='public'
            \""
TABLENAMES=$(export PGPASSWORD=test; eval "$PGCOMMAND")

for TABLENAME in $TABLENAMES; do
    PGCOMMAND=" psql -h localhost -U fred -d mydb -At -c \"
                SELECT   '$TABLENAME',
                         count(*) 
                FROM     $TABLENAME
                \""
    eval "$PGCOMMAND"
done

How to define Singleton in TypeScript

After scouring this thread and playing around with all the options above - I settled with a Singleton that can be created with proper constructors:

export default class Singleton {
  private static _instance: Singleton

  public static get instance(): Singleton {
    return Singleton._instance
  }

  constructor(...args: string[]) {
    // Initial setup

    Singleton._instance = this
  }

  work() { /* example */ }

}

It would require an initial setup (in main.ts, or index.ts), which can easily be implemented by
new Singleton(/* PARAMS */)

Then, anywhere in your code, just call Singleton.instnace; in this case, to get work done, I would call Singleton.instance.work()

Getting the inputstream from a classpath resource (XML file)

That depends on where exactly the XML file is. Is it in the sources folder (in the "default package" or the "root") or in the same folder as the class?

In for former case, you must use "/file.xml" (note the leading slash) to find the file and it doesn't matter which class you use to try to locate it.

If the XML file is next to some class, SomeClass.class.getResourceAsStream() with just the filename is the way to go.

bash export command

If you are using C shell -

setenv PATH $PATH":/home/tmp"

Error in contrasts when defining a linear model in R

Metrics and Svens answer deals with the usual situation but for us who work in non-english enviroments if you have exotic characters (å,ä,ö) in your character variable you will get the same result, even if you have multiple factor levels.

Levels <- c("Pri", "För") gives the contrast error, while Levels <- c("Pri", "For") doesn't

This is probably a bug.

Submit form using <a> tag

Using Jquery you can do something like this:

_x000D_
_x000D_
$(document).ready(function() {_x000D_
  $('#btnSubmit').click(function() {_x000D_
    $('#deleteFrm').submit();_x000D_
  });_x000D_
_x000D_
});
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>_x000D_
<form action="" id="deleteFrm" method="POST">_x000D_
  <a id="btnSubmit">Submit</a>_x000D_
</form>
_x000D_
_x000D_
_x000D_

SQL: How to to SUM two values from different tables

select region,sum(number) total
from
(
    select region,number
    from cash_table
    union all
    select region,number
    from cheque_table
) t
group by region

Where to download visual studio express 2005?

You can still get it, from microsoft servers, see my answer on this question: Where is Visual Studio 2005 Express?

<ng-container> vs <template>

In my case it acts like a <div> or <span> however even <span> messes up with my AngularFlex styling but ng-container doesn't.

jQuery UI DatePicker - Change Date Format

The getDate method of datepicker returns a date type, not a string.

You need to format the returned value to a string using your date format. Use datepicker's formatDate function:

var dateTypeVar = $('#datepicker').datepicker('getDate');
$.datepicker.formatDate('dd-mm-yy', dateTypeVar);

The full list of format specifiers is available here.

What is the best open-source java charting library? (other than jfreechart)

I've used EasyCharts in the past and it lived up to it's name. It's not as powerful as JFreeChart, but the JAR for EasyCharts is much smaller than for JFreeChart.

If statements for Checkboxes

I suggest

if (checkbox.IsChecked == true)
{
    //do something
}

Hope it's helpful ^^

Insert content into iFrame

This should do what you want:

$("#iframe").ready(function() {
    var body = $("#iframe").contents().find("body");
    body.append('Test');
});

Check this JSFiddle for working demo.

Edit: You can of course do it one line style:

$("#iframe").contents().find("body").append('Test');

Select the first row by group

What about

DT <- data.table(test)
setkey(DT, id)

DT[J(unique(id)), mult = "first"]

Edit

There is also a unique method for data.tables which will return the the first row by key

jdtu <- function() unique(DT)

I think, if you are ordering test outside the benchmark, then you can removing the setkey and data.table conversion from the benchmark as well (as the setkey basically sorts by id, the same as order).

set.seed(21)
test <- data.frame(id=sample(1e3, 1e5, TRUE), string=sample(LETTERS, 1e5, TRUE))
test <- test[order(test$id), ]
DT <- data.table(DT, key = 'id')
ju <- function() test[!duplicated(test$id),]

jdt <- function() DT[J(unique(id)),mult = 'first']


 library(rbenchmark)
benchmark(ju(), jdt(), replications = 5)
##    test replications elapsed relative user.self sys.self 
## 2 jdt()            5    0.01        1      0.02        0        
## 1  ju()            5    0.05        5      0.05        0         

and with more data

** Edit with unique method**

set.seed(21)
test <- data.frame(id=sample(1e4, 1e6, TRUE), string=sample(LETTERS, 1e6, TRUE))
test <- test[order(test$id), ]
DT <- data.table(test, key = 'id')
       test replications elapsed relative user.self sys.self 
2  jdt()            5    0.09     2.25      0.09     0.00    
3 jdtu()            5    0.04     1.00      0.05     0.00      
1   ju()            5    0.22     5.50      0.19     0.03        

The unique method is fastest here.

How to check if a specific key is present in a hash or not?

It is very late but preferably symbols should be used as key:

my_hash = {}
my_hash[:my_key] = 'value'

my_hash.has_key?("my_key")
 => false 
my_hash.has_key?("my_key".to_sym)
 => true 

my_hash2 = {}
my_hash2['my_key'] = 'value'

my_hash2.has_key?("my_key")
 => true 
my_hash2.has_key?("my_key".to_sym)
 => false 

But when creating hash if you pass string as key then it will search for the string in keys.

But when creating hash you pass symbol as key then has_key? will search the keys by using symbol.


If you are using Rails, you can use Hash#with_indifferent_access to avoid this; both hash[:my_key] and hash["my_key"] will point to the same record

select2 onchange event only works once

This is what I am using:

$("#search_code").live('change', function(){
  alert(this.value)
});

For latest jQuery users, this one should work:

$(document.body).on("change","#search_code",function(){
 alert(this.value);
});

How to send email from MySQL 5.1

I would be very concerned about putting the load of sending e-mails on my database server (small though it may be). I might suggest one of these alternatives:

  1. Have application logic detect the need to send an e-mail and send it.
  2. Have a MySQL trigger populate a table that queues up the e-mails to be sent and have a process monitor that table and send the e-mails.

How to submit a form using Enter key in react.js?

this is how you do it if you want to listen for the "Enter" key. There is an onKeydown prop that you can use and you can read about it in react doc

and here is a codeSandbox

const App = () => {
    const something=(event)=> {
        if (event.keyCode === 13) {
            console.log('enter')
        }
    }
return (
    <div className="App">
        <h1>Hello CodeSandbox</h1>
        <h2>Start editing to see some magic happen!</h2>
        <input  type='text' onKeyDown={(e) => something(e) }/>
    </div>
);
}

How to display scroll bar onto a html table

Something like this?

http://jsfiddle.net/TweNm/

The idea is to wrap the <table> in a non-statically positioned <div> which has an overflow:auto CSS property. Then position the elements in the <thead> absolutely.

_x000D_
_x000D_
#table-wrapper {_x000D_
  position:relative;_x000D_
}_x000D_
#table-scroll {_x000D_
  height:150px;_x000D_
  overflow:auto;  _x000D_
  margin-top:20px;_x000D_
}_x000D_
#table-wrapper table {_x000D_
  width:100%;_x000D_
_x000D_
}_x000D_
#table-wrapper table * {_x000D_
  background:yellow;_x000D_
  color:black;_x000D_
}_x000D_
#table-wrapper table thead th .text {_x000D_
  position:absolute;   _x000D_
  top:-20px;_x000D_
  z-index:2;_x000D_
  height:20px;_x000D_
  width:35%;_x000D_
  border:1px solid red;_x000D_
}
_x000D_
<div id="table-wrapper">_x000D_
  <div id="table-scroll">_x000D_
    <table>_x000D_
        <thead>_x000D_
            <tr>_x000D_
                <th><span class="text">A</span></th>_x000D_
                <th><span class="text">B</span></th>_x000D_
                <th><span class="text">C</span></th>_x000D_
            </tr>_x000D_
        </thead>_x000D_
        <tbody>_x000D_
          <tr> <td>1, 0</td> <td>2, 0</td> <td>3, 0</td> </tr>_x000D_
          <tr> <td>1, 1</td> <td>2, 1</td> <td>3, 1</td> </tr>_x000D_
          <tr> <td>1, 2</td> <td>2, 2</td> <td>3, 2</td> </tr>_x000D_
          <tr> <td>1, 3</td> <td>2, 3</td> <td>3, 3</td> </tr>_x000D_
          <tr> <td>1, 4</td> <td>2, 4</td> <td>3, 4</td> </tr>_x000D_
          <tr> <td>1, 5</td> <td>2, 5</td> <td>3, 5</td> </tr>_x000D_
          <tr> <td>1, 6</td> <td>2, 6</td> <td>3, 6</td> </tr>_x000D_
          <tr> <td>1, 7</td> <td>2, 7</td> <td>3, 7</td> </tr>_x000D_
          <tr> <td>1, 8</td> <td>2, 8</td> <td>3, 8</td> </tr>_x000D_
          <tr> <td>1, 9</td> <td>2, 9</td> <td>3, 9</td> </tr>_x000D_
          <tr> <td>1, 10</td> <td>2, 10</td> <td>3, 10</td> </tr>_x000D_
          <!-- etc... -->_x000D_
          <tr> <td>1, 99</td> <td>2, 99</td> <td>3, 99</td> </tr>_x000D_
        </tbody>_x000D_
    </table>_x000D_
  </div>_x000D_
</div>
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Adding a month to a date in T SQL

DateAdd(m,1,reference_dt)

will add a month to the column value

babel-loader jsx SyntaxError: Unexpected token

For those who still might be facing issue adding jsx to test fixed it for me

test: /\.jsx?$/,

How to get height of entire document with JavaScript?

Document sizes are a browser compatibility nightmare because, although all browsers expose clientHeight and scrollHeight properties, they don't all agree how the values are calculated.

There used to be a complex best-practice formula around for how you tested for correct height/width. This involved using document.documentElement properties if available or falling back on document properties and so on.

The simplest way to get correct height is to get all height values found on document, or documentElement, and use the highest one. This is basically what jQuery does:

var body = document.body,
    html = document.documentElement;

var height = Math.max( body.scrollHeight, body.offsetHeight, 
                       html.clientHeight, html.scrollHeight, html.offsetHeight );

A quick test with Firebug + jQuery bookmarklet returns the correct height for both cited pages, and so does the code example.

Note that testing the height of the document before the document is ready will always result in a 0. Also, if you load more stuff in, or the user resizes the window, you may need to re-test. Use onload or a document ready event if you need this at load time, otherwise just test whenever you need the number.

How to determine whether a given Linux is 32 bit or 64 bit?

Simple script to get 64 bit or 32 bit

        if $(getconf LONG_BIT | grep '64'); then
           echo "64 bit system"
        else
            echo "32 bit system"
        fi

How to increase Java heap space for a tomcat app

There is a mechanism to do it without modifying any files that are in the distribution. You can create a separate file %CATALINA_HOME%\bin\setenv.bat or $CATALINA_HOME/bin/setenv.sh and put your environment variables there. Further, the memory settings apply to the JVM, not Tomcat, so I'd set the JAVA_OPTS variable instead:

set JAVA_OPTS=-Xmx512m

Appending a list or series to a pandas DataFrame as a row?

Following onto Mike Chirico's answer... if you want to append a list after the dataframe is already populated...

>>> list = [['f','g']]
>>> df = df.append(pd.DataFrame(list, columns=['col1','col2']),ignore_index=True)
>>> df
  col1 col2
0    a    b
1    d    e
2    f    g

ToggleButton in C# WinForms

Check FlatStyle property. Setting it to "System" makes the checkbox sunken in my environment.

How to get the primary IP address of the local machine on Linux and OS X?

ifconfig | grep 'inet ' | grep -v '127.0.0.1' | awk '{print $2}'

Convert DataFrame column type from string to datetime, dd/mm/yyyy format

The easiest way is to use to_datetime:

df['col'] = pd.to_datetime(df['col'])

It also offers a dayfirst argument for European times (but beware this isn't strict).

Here it is in action:

In [11]: pd.to_datetime(pd.Series(['05/23/2005']))
Out[11]:
0   2005-05-23 00:00:00
dtype: datetime64[ns]

You can pass a specific format:

In [12]: pd.to_datetime(pd.Series(['05/23/2005']), format="%m/%d/%Y")
Out[12]:
0   2005-05-23
dtype: datetime64[ns]

Core dump file analysis

Steps to debug coredump using GDB:

Some generic help:

gdb start GDB, with no debugging les

gdb program begin debugging program

gdb program core debug coredump core produced by program

gdb --help describe command line options

  1. First of all, find the directory where the corefile is generated.

  2. Then use ls -ltr command in the directory to find the latest generated corefile.

  3. To load the corefile use

    gdb binary path of corefile
    

    This will load the corefile.

  4. Then you can get the information using the bt command.

    For a detailed backtrace use bt full.

  5. To print the variables, use print variable-name or p variable-name

  6. To get any help on GDB, use the help option or use apropos search-topic

  7. Use frame frame-number to go to the desired frame number.

  8. Use up n and down n commands to select frame n frames up and select frame n frames down respectively.

  9. To stop GDB, use quit or q.

Execute combine multiple Linux commands in one line

I've found that using ; to separate commands only works in the foreground. eg :

cmd1; cmd2; cmd3 & - will only execute cmd3 in the background, whereas cmd1 && cmd2 && cmd3 & - will execute the entire chain in the background IF there are no errors.

To cater for unconditional execution, using parenthesis solves this :

(cmd1; cmd2; cmd3) & - will execute the chain of commands in the background, even if any step fails.

Ajax - 500 Internal Server Error

This may be an incorrect parameter to your SOAP call; look at the format of the parameter(s) in the 'data:' json section - this is the payload you are passing over - parameter and data wrapped in JSON format.

Google Chrome's debugging toolbar has some good tools to verify parameters and look at error messages - for example, start with the Console tab and click on the URL which errors or click on the network tab. You will want to view the message's headers, response etc...

File Upload with Angular Material

from jameswyse at https://github.com/angular/material/issues/3310

HTML

<input id="fileInput" name="file" type="file" class="ng-hide" multiple>
<md-button id="uploadButton" class="md-raised md-primary"> Choose Files </md-button>

CONTROLLER

    var link = function (scope, element, attrs) {
    const input = element.find('#fileInput');
    const button = element.find('#uploadButton');

    if (input.length && button.length) {
        button.click((e) => input.click());
    }
}

Worked for me.

How do change the color of the text of an <option> within a <select>?

Try just this without the span tag:

<option selected="selected" class="grey_color">select one option</option>

For bigger flexibility you can use any JS widget.

How to exclude 0 from MIN formula Excel

Not entirely sure what you want here, but if you want to discount blank cells in the range and pass over zeros then this would do it; if a little contrived:

=MIN(IF(A1:E1=0,MAX(A1:E1),A1:E1))

With Ctrl+Shift+Enter as an array.

What I'm doing here is replacing zeros with the maximum value in the list.

C++ Erase vector element by value rather than by position?

You can not do that directly. You need to use std::remove algorithm to move the element to be erased to the end of the vector and then use erase function. Something like: myVector.erase(std::remove(myVector.begin(), myVector.end(), 8), myVec.end());. See this erasing elements from vector for more details.

I need to know how to get my program to output the word i typed in and also the new rearranged word using a 2D array

  1. What exactly doesn't work?
  2. Why are you using a 2d array?
  3. If you must use a 2d array:

    int numOfPairs = 10;  String[][] array = new String[numOfPairs][2]; for(int i = 0; i < array.length; i++){     for(int j = 0; j < array[i].length; j++){         array[i] = new String[2];         array[i][0] = "original word";         array[i][1] = "rearranged word";     }    } 

Does this give you a hint?

MVC 4 Razor File Upload

I think, better way is use HttpPostedFileBase in your controller or API. After this you can simple detect size, type etc.

File properties you can find here:

MVC3 How to check if HttpPostedFileBase is an image

For example ImageApi:

[HttpPost]
[Route("api/image")]  
public ActionResult Index(HttpPostedFileBase file)  
{  
    if (file != null && file.ContentLength > 0)  
        try 
        {  
            string path = Path.Combine(Server.MapPath("~/Images"),  
               Path.GetFileName(file.FileName));

            file.SaveAs(path);  
            ViewBag.Message = "Your message for success";  
        }  
        catch (Exception ex)  
        {  
            ViewBag.Message = "ERROR:" + ex.Message.ToString();  
        }  
    else 
    {  
        ViewBag.Message = "Please select file";  
    }  
    return View();  
}

Hope it help.

HRESULT: 0x80131040: The located assembly's manifest definition does not match the assembly reference

I ran into this issue in a web api project.

Api project was using a nuget package of a library with version 3. And one of the referenced assemblies say X was using older version of the same nuget package with version 2.

Whenever referenced assembly is built or any other project referencing X is rebuilt, api project's assemblies gets updated with lower version. And got this assembly reference error.

Rebuild works but in my case I wanted a long term solution.

I made the assemblies reference same version of nuget package.

Hashing a string with Sha256

public string EncryptPassword(string password, string saltorusername)
        {
            using (var sha256 = SHA256.Create())
            {
                var saltedPassword = string.Format("{0}{1}", salt, password);
                byte[] saltedPasswordAsBytes = Encoding.UTF8.GetBytes(saltedPassword);
                return Convert.ToBase64String(sha256.ComputeHash(saltedPasswordAsBytes));
            }
        }

YouTube Autoplay not working

mute=1 or muted=1 as suggested by @Fab will work. However, if you wish to enable autoplay with sound you should add allow="autoplay" to your embedded <iframe>.

<iframe type="text/html" src="https://www.youtube.com/embed/-ePDPGXkvlw?autoplay=1" frameborder="0" allow="autoplay"></iframe>

This is officially supported and documented in Google's Autoplay Policy Changes 2017 post

Iframe delegation A feature policy allows developers to selectively enable and disable use of various browser features and APIs. Once an origin has received autoplay permission, it can delegate that permission to cross-origin iframes with a new feature policy for autoplay. Note that autoplay is allowed by default on same-origin iframes.

<!-- Autoplay is allowed. -->
<iframe src="https://cross-origin.com/myvideo.html" allow="autoplay">

<!-- Autoplay and Fullscreen are allowed. -->
<iframe src="https://cross-origin.com/myvideo.html" allow="autoplay; fullscreen">

When the feature policy for autoplay is disabled, calls to play() without a user gesture will reject the promise with a NotAllowedError DOMException. And the autoplay attribute will also be ignored.

How to convert a string from uppercase to lowercase in Bash?

If you define your variable using declare (old: typeset) then you can state the case of the value throughout the variable's use.

$ declare -u FOO=AbCxxx
$ echo $FOO
ABCXXX

"-l" does lc.

How do I execute multiple SQL Statements in Access' Query Editor?

You might find it better to use a 3rd party program to enter the queries into Access such as WinSQL I think from memory WinSQL supports multiple queries via it's batch feature.

I ultimately found it easier to just write a program in perl to do bulk INSERTS into an Access via ODBC. You could use vbscript or any language that supports ODBC though.

You can then do anything you like and have your own complicated logic to handle the importing.

What is the difference between g++ and gcc?

What is the difference between g++ and gcc?

gcc has evolved from a single language "GNU C Compiler" to be a multi-language "GNU Compiler Collection". The term "GNU C Compiler" is still used sometimes in the context of C programming.

The g++ is the C++ compiler for the GNU Compiler Collection. Like gnat is the Ada compiler for gcc. see Using the GNU Compiler Collection (GCC)

For example, the Ubuntu 16.04 and 18.04 man g++ command returns the GCC(1) manual page.

The Ubuntu 16.04 and 18.04 man gcc states that ...

g++ accepts mostly the same options as gcc

and that the default ...

... use of gcc does not add the C++ library. g++ is a program that calls GCC and automatically specifies linking against the C++ library. It treats .c, .h and .i files as C++ source files instead of C source files unless -x is used. This program is also useful when precompiling a C header file with a .h extension for use in C++ compilations.

Search the gcc man pages for more details on the option variances between gcc and g++.

Which one should be used for general c++ development?

Technically, either gcc or g++ can be used for general C++ development with applicable option settings. However, the g++ default behavior is naturally aligned to a C++ development.

The Ubuntu 18.04 'gcc' man page added, and Ubuntu 20.04 continues to have, the following paragraph:

The usual way to run GCC is to run the executable called gcc, or machine-gcc when cross-compiling, or machine-gcc-version to run a specific version of GCC. When you compile C++ programs, you should invoke GCC as g++ instead.

How to call a parent method from child class in javascript?

While you can call the parent method by the prototype of the parent, you will need to pass the current child instance for using call, apply, or bind method. The bind method will create a new function so I doesn't recommend that if you care for performance except it only called once.

As an alternative you can replace the child method and put the parent method on the instance while calling the original child method.

_x000D_
_x000D_
function proxy(context, parent){
  var proto = parent.prototype;
  var list = Object.getOwnPropertyNames(proto);
  
  for(var i=0; i < list.length; i++){
    var key = list[i];

    // Create only when child have similar method name
    if(context[key] !== proto[key]){
      let currentMethod = context[key];
      let parentMethod = proto[key];
      
      context[key] = function(){
        context.super = parentMethod;
        return currentMethod.apply(context, arguments);
      }
    }
  }
}

// ========= The usage would be like this ==========

class Parent {
  first = "Home";

  constructor(){
    console.log('Parent created');
  }

  add(arg){
    return this.first + ", Parent "+arg;
  }
}

class Child extends Parent{
  constructor(b){
    super();
    proxy(this, Parent);
    console.log('Child created');
  }

  // Comment this to call method from parent only
  add(arg){
    return super.add(arg) + ", Child "+arg;
  }
}

var family = new Child();
console.log(family.add('B'));
_x000D_
_x000D_
_x000D_

"Automatic" vs "Automatic (Delayed start)"

In short, services set to Automatic will start during the boot process, while services set to start as Delayed will start shortly after boot.

Starting your service Delayed improves the boot performance of your server and has security benefits which are outlined in the article Adriano linked to in the comments.

Update: "shortly after boot" is actually 2 minutes after the last "automatic" service has started, by default. This can be configured by a registry key, according to Windows Internals and other sources (3,4).

The registry keys of interest (At least in some versions of windows) are:

  • HKLM\SYSTEM\CurrentControlSet\services\<service name>\DelayedAutostart will have the value 1 if delayed, 0 if not.
  • HKLM\SYSTEM\CurrentControlSet\services\AutoStartDelay or HKLM\SYSTEM\CurrentControlSet\Control\AutoStartDelay (on Windows 10): decimal number of seconds to wait, may need to create this one. Applies globally to all Delayed services.

How can apply multiple background color to one div

With :after and :before you can do that.

HTML:

<div class="a"> </div>
<div class="b"> </div>
<div class="c"> </div>

CSS:

div {
    height: 100px;
    position: relative;
}
.a {
    background: #9C9E9F;
}
.b {
    background: linear-gradient(to right, #9c9e9f, #f6f6f6);
}
.a:after, .c:before, .c:after {
    content: '';
    width: 50%;
    height: 100%;
    top: 0;
    right: 0;
    display: block;
    position: absolute;
}
.a:after {
    background: #f6f6f6;    
}
.c:before {
    background: #9c9e9f;
    left: 0;
}
.c:after {
    background: #33CCFF;
    right: 0;
    height: 80%;
}

And a demo.

How to set 24-hours format for date on java?

This will give you the date in 24 hour format.

    Date date = new Date();
    date.setHours(date.getHours() + 8);
    System.out.println(date);
    SimpleDateFormat simpDate;
    simpDate = new SimpleDateFormat("kk:mm:ss");
    System.out.println(simpDate.format(date));

Process list on Linux via Python

The sanctioned way of creating and using child processes is through the subprocess module.

import subprocess
pl = subprocess.Popen(['ps', '-U', '0'], stdout=subprocess.PIPE).communicate()[0]
print pl

The command is broken down into a python list of arguments so that it does not need to be run in a shell (By default the subprocess.Popen does not use any kind of a shell environment it just execs it). Because of this we cant simply supply 'ps -U 0' to Popen.

Array of an unknown length in C#

You can create an array with the size set to a variable, i.e.

int size = 50;
string[] words = new string[size]; // contains 50 strings

However, that size can't change later on, if you decide you need 100 words. If you need the size to be really dynamic, you'll need to use a different sort of data structure. Try List.

How to implement "Access-Control-Allow-Origin" header in asp.net

From enable-cors.org:

CORS on ASP.NET

If you don't have access to configure IIS, you can still add the header through ASP.NET by adding the following line to your source pages:

Response.AppendHeader("Access-Control-Allow-Origin", "*");

See also: Configuring IIS6 / IIS7

How to convert a String into an array of Strings containing one character each

You mean you want to do "aabbab".toCharArray(); ? Which will return an array of chars. Or do you actually want the resulting array to contain single character string objects?

Why is sed not recognizing \t as a tab?

Use $(echo '\t'). You'll need quotes around the pattern.

Eg. To remove a tab:

sed "s/$(echo '\t')//"

How can I get all element values from Request.Form without specifying exactly which one with .GetValues("ElementIdName")

Here is a way to do it without adding an ID to the form elements.

<form method="post">
    ...
    <select name="List">
        <option value="1">Test1</option>
        <option value="2">Test2</option>
    </select>
    <select name="List">
        <option value="3">Test3</option>
        <option value="4">Test4</option>
    </select>
    ...
</form>

public ActionResult OrderProcessor()
{
    string[] ids = Request.Form.GetValues("List");
}

Then ids will contain all the selected option values from the select lists. Also, you could go down the Model Binder route like so:

public class OrderModel
{
    public string[] List { get; set; }
}

public ActionResult OrderProcessor(OrderModel model)
{
    string[] ids = model.List;
}

Hope this helps.

Get time of specific timezone

The best way to do this is to use getLocaleString, like this:

Create a date object:

date = new Date(0)

If you are in Berlin, this should convert to this string:

Thu Jan 01 1970 01:00:00 GMT+0100 (CET)

Get the hours in Athens:

date.toLocaleString('de-DE', {hour: '2-digit',   hour12: false, timeZone: 'Europe/Athens' })

'02'

Get the hours in Shanghai:

date.toLocaleString('de-DE', {hour: '2-digit',   hour12: false, timeZone: 'Asia/Shanghai' })

'08'

toBe(true) vs toBeTruthy() vs toBeTrue()

As you read through the examples below, just keep in mind this difference

true === true // true
"string" === true // false
1 === true // false
{} === true // false

But

Boolean("string") === true // true
Boolean(1) === true // true
Boolean({}) === true // true

1. expect(statement).toBe(true)

Assertion passes when the statement passed to expect() evaluates to true

expect(true).toBe(true) // pass
expect("123" === "123").toBe(true) // pass

In all other cases cases it would fail

expect("string").toBe(true) // fail
expect(1).toBe(true); // fail
expect({}).toBe(true) // fail

Even though all of these statements would evaluate to true when doing Boolean():

So you can think of it as 'strict' comparison

2. expect(statement).toBeTrue()

This one does exactly the same type of comparison as .toBe(true), but was introduced in Jasmine recently in version 3.5.0 on Sep 20, 2019

3. expect(statement).toBeTruthy()

toBeTruthy on the other hand, evaluates the output of the statement into boolean first and then does comparison

expect(false).toBeTruthy() // fail
expect(null).toBeTruthy() // fail
expect(undefined).toBeTruthy() // fail
expect(NaN).toBeTruthy() // fail
expect("").toBeTruthy() // fail
expect(0).toBeTruthy() // fail

And IN ALL OTHER CASES it would pass, for example

expect("string").toBeTruthy() // pass
expect(1).toBeTruthy() // pass
expect({}).toBeTruthy() // pass

Clear History and Reload Page on Login/Logout Using Ionic Framework

I was trying to do refresh page using angularjs when i saw websites i got confused but no code was working for the code then i got solution for reloading page using

$state.go('path',null,{reload:true});

use this in a function this will work.

Nested classes' scope?

class Outer(object):
    outer_var = 1

    class Inner(object):
        @property
        def inner_var(self):
            return Outer.outer_var

This isn't quite the same as similar things work in other languages, and uses global lookup instead of scoping the access to outer_var. (If you change what object the name Outer is bound to, then this code will use that object the next time it is executed.)

If you instead want all Inner objects to have a reference to an Outer because outer_var is really an instance attribute:

class Outer(object):
    def __init__(self):
        self.outer_var = 1

    def get_inner(self):
        return self.Inner(self)
        # "self.Inner" is because Inner is a class attribute of this class
        # "Outer.Inner" would also work, or move Inner to global scope
        # and then just use "Inner"

    class Inner(object):
        def __init__(self, outer):
            self.outer = outer

        @property
        def inner_var(self):
            return self.outer.outer_var

Note that nesting classes is somewhat uncommon in Python, and doesn't automatically imply any sort of special relationship between the classes. You're better off not nesting. (You can still set a class attribute on Outer to Inner, if you want.)

Append text using StreamWriter

Also look at log4net, which makes logging to 1 or more event stores — whether it's the console, the Windows event log, a text file, a network pipe, a SQL database, etc. — pretty trivial. You can even filter stuff in its configuration, for instance, so that only log records of a particular severity (say ERROR or FATAL) from a single component or assembly are directed to a particular event store.

http://logging.apache.org/log4net/

Importing CSV with line breaks in Excel 2007

This is for Excel 2016:

Just had the same problem with line breaks inside a csv file with the Excel Wizard.

Afterwards I was trying it with the "New Query" Feature: Data -> New Query -> From File -> From CSV -> Choose the File -> Import -> Load

It was working perfectly and a very quick workaround for all of you that have the same problem.

Onclick CSS button effect

You should apply the following styles:

#button:active {
    vertical-align: top;
    padding: 8px 13px 6px;
}

This will give you the necessary effect, demo here.

Extending the User model with custom fields in Django

Currently as of Django 2.2, the recommended way when starting a new project is to create a custom user model that inherits from AbstractUser, then point AUTH_USER_MODEL to the model.

Source: https://docs.djangoproject.com/en/2.2/topics/auth/customizing/#using-a-custom-user-model-when-starting-a-project

How to make a custom LinkedIn share button

Its best to use customize url approach. And its the easiest. Found this one. It will open a popup window and you dont need any bs authentication issues because of w_share and all.

_x000D_
_x000D_
<a href="https://www.linkedin.com/shareArticle?mini=true&url=http://chillyfacts.com/create-linkedin-share-button-on-website-webpages&title=Create LinkedIn Share button on Website Webpages&summary=chillyfacts.com&source=Chillyfacts" onclick="window.open(this.href, 'mywin', 'left=20,top=20,width=500,height=500,toolbar=1,resizable=0'); return false;">_x000D_
  <img src="http://chillyfacts.com/wp-content/uploads/2017/06/LinkedIN.gif" alt="" width="54" height="20" />_x000D_
</a>
_x000D_
_x000D_
_x000D_

Just change the url with your own url. Here is the link http://chillyfacts.com/create-linkedin-share-button-on-website-webpages/

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

I don't understand -Wl,-rpath -Wl,

The man page makes it pretty clear. If you want to pass two arguments (-rpath and .) to the linker you can write

-Wl,-rpath,.

or alternatively

-Wl,-rpath -Wl,.

The arguments -Wl,-rpath . you suggested do NOT make sense to my mind. How is gcc supposed to know that your second argument (.) is supposed to be passed to the linker instead of being interpreted normally? The only way it would be able to know that is if it had insider knowledge of all possible linker arguments so it knew that -rpath required an argument after it.

Passing an array using an HTML form hidden element

If you want to post an array you must use another notation:

foreach ($postvalue as $value){
<input type="hidden" name="result[]" value="$value.">
}

in this way you have three input fields with the name result[] and when posted $_POST['result'] will be an array

Python: Pandas Dataframe how to multiply entire column with a scalar

More recent pandas versions have the pd.DataFrame.multiply function.

df['quantity'] = df['quantity'].multiply(-1)

Replace Line Breaks in a String C#

Use replace with Environment.NewLine

myString = myString.Replace(System.Environment.NewLine, "replacement text"); //add a line terminating ;

As mentioned in other posts, if the string comes from another environment (OS) then you'd need to replace that particular environments implementation of new line control characters.

Invoke a second script with arguments from a script

Aha. This turned out to be a simple problem of there being spaces in the path to the script.

Changing the Invoke-Expression line to:

Invoke-Expression "& `"$scriptPath`" $argumentList"

...was enough to get it to kick off. Thanks to Neolisk for your help and feedback!

Cannot install signed apk to device manually, got error "App not installed"

I am using Android 10 in MiA2. The mistake I was making is that I tried to install the app via ES Explorer. I tried Settings -> Apps & Notifications -> Advanced -> Special App Access -> Install Unknown Apps -> ES File Manage -> Allow from this source. Even then the app won't install.

Then I tired to install the app using the default File Manager and it installed easily.

JNI and Gradle in Android Studio

Gradle Build Tools 2.2.0+ - The closest the NDK has ever come to being called 'magic'

In trying to avoid experimental and frankly fed up with the NDK and all its hackery I am happy that 2.2.x of the Gradle Build Tools came out and now it just works. The key is the externalNativeBuild and pointing ndkBuild path argument at an Android.mk or change ndkBuild to cmake and point the path argument at a CMakeLists.txt build script.

android {
    compileSdkVersion 19
    buildToolsVersion "25.0.2"

    defaultConfig {
        minSdkVersion 19
        targetSdkVersion 19

        ndk {
            abiFilters 'armeabi', 'armeabi-v7a', 'x86'
        }

        externalNativeBuild {
            cmake {
                cppFlags '-std=c++11'
                arguments '-DANDROID_TOOLCHAIN=clang',
                        '-DANDROID_PLATFORM=android-19',
                        '-DANDROID_STL=gnustl_static',
                        '-DANDROID_ARM_NEON=TRUE',
                        '-DANDROID_CPP_FEATURES=exceptions rtti'
            }
        }
    }

    externalNativeBuild {
        cmake {
             path 'src/main/jni/CMakeLists.txt'
        }
        //ndkBuild {
        //   path 'src/main/jni/Android.mk'
        //}
    }
}

For much more detail check Google's page on adding native code.

After this is setup correctly you can ./gradlew installDebug and off you go. You will also need to be aware that the NDK is moving to clang since gcc is now deprecated in the Android NDK.

Android Studio Clean and Build Integration - DEPRECATED

The other answers do point out the correct way to prevent the automatic creation of Android.mk files, but they fail to go the extra step of integrating better with Android Studio. I have added the ability to actually clean and build from source without needing to go to the command-line. Your local.properties file will need to have ndk.dir=/path/to/ndk

apply plugin: 'com.android.application'

android {
    compileSdkVersion 14
    buildToolsVersion "20.0.0"

    defaultConfig {
        applicationId "com.example.application"
        minSdkVersion 14
        targetSdkVersion 14

        ndk {
            moduleName "YourModuleName"
        }
    }

    sourceSets.main {
        jni.srcDirs = [] // This prevents the auto generation of Android.mk
        jniLibs.srcDir 'src/main/libs' // This is not necessary unless you have precompiled libraries in your project.
    }

    task buildNative(type: Exec, description: 'Compile JNI source via NDK') {
        def ndkDir = android.ndkDirectory
        commandLine "$ndkDir/ndk-build",
                '-C', file('src/main/jni').absolutePath, // Change src/main/jni the relative path to your jni source
                '-j', Runtime.runtime.availableProcessors(),
                'all',
                'NDK_DEBUG=1'
    }

    task cleanNative(type: Exec, description: 'Clean JNI object files') {
        def ndkDir = android.ndkDirectory
        commandLine "$ndkDir/ndk-build",
                '-C', file('src/main/jni').absolutePath, // Change src/main/jni the relative path to your jni source
                'clean'
    }

    clean.dependsOn 'cleanNative'

    tasks.withType(JavaCompile) {
        compileTask -> compileTask.dependsOn buildNative
    }
}

dependencies {
    compile 'com.android.support:support-v4:20.0.0'
}

The src/main/jni directory assumes a standard layout of the project. It should be the relative from this build.gradle file location to the jni directory.

Gradle - for those having issues

Also check this Stack Overflow answer.

It is really important that your gradle version and general setup are correct. If you have an older project I highly recommend creating a new one with the latest Android Studio and see what Google considers the standard project. Also, use gradlew. This protects the developer from a gradle version mismatch. Finally, the gradle plugin must be configured correctly.

And you ask what is the latest version of the gradle plugin? Check the tools page and edit the version accordingly.

Final product - /build.gradle

// Top-level build file where you can add configuration options common to all sub-projects/modules.

// Running 'gradle wrapper' will generate gradlew - Getting gradle wrapper working and using it will save you a lot of pain.
task wrapper(type: Wrapper) {
    gradleVersion = '2.2'
}

// Look Google doesn't use Maven Central, they use jcenter now.
buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:1.2.0'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
    }
}

Make sure gradle wrapper generates the gradlew file and gradle/wrapper subdirectory. This is a big gotcha.

ndkDirectory

This has come up a number of times, but android.ndkDirectory is the correct way to get the folder after 1.1. Migrating Gradle Projects to version 1.0.0. If you're using an experimental or ancient version of the plugin your mileage may vary.

What should a JSON service return on failure / error

I've spend some hours solving this problem. My solution is based on the following wishes/requirements:

  • Don't have repetitive boilerplate error handling code in all JSON controller actions.
  • Preserve HTTP (error) status codes. Why? Because higher level concerns should not affect lower level implementation.
  • Be able to get JSON data when an error/exception occur on the server. Why? Because I might want rich error information. E.g. error message, domain specific error status code, stack trace (in debug/development environment).
  • Ease of use client side - preferable using jQuery.

I create a HandleErrorAttribute (see code comments for explanation of the details). A few details including "usings" has been left out, so the code might not compile. I add the filter to the global filters during application initialization in Global.asax.cs like this:

GlobalFilters.Filters.Add(new UnikHandleErrorAttribute());

Attribute:

namespace Foo
{
  using System;
  using System.Diagnostics;
  using System.Linq;
  using System.Net;
  using System.Reflection;
  using System.Web;
  using System.Web.Mvc;

  /// <summary>
  /// Generel error handler attribute for Foo MVC solutions.
  /// It handles uncaught exceptions from controller actions.
  /// It outputs trace information.
  /// If custom errors are enabled then the following is performed:
  /// <ul>
  ///   <li>If the controller action return type is <see cref="JsonResult"/> then a <see cref="JsonResult"/> object with a <c>message</c> property is returned.
  ///       If the exception is of type <see cref="MySpecialExceptionWithUserMessage"/> it's message will be used as the <see cref="JsonResult"/> <c>message</c> property value.
  ///       Otherwise a localized resource text will be used.</li>
  /// </ul>
  /// Otherwise the exception will pass through unhandled.
  /// </summary>
  [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
  public sealed class FooHandleErrorAttribute : HandleErrorAttribute
  {
    private readonly TraceSource _TraceSource;

    /// <summary>
    /// <paramref name="traceSource"/> must not be null.
    /// </summary>
    /// <param name="traceSource"></param>
    public FooHandleErrorAttribute(TraceSource traceSource)
    {
      if (traceSource == null)
        throw new ArgumentNullException(@"traceSource");
      _TraceSource = traceSource;
    }

    public TraceSource TraceSource
    {
      get
      {
        return _TraceSource;
      }
    }

    /// <summary>
    /// Ctor.
    /// </summary>
    public FooHandleErrorAttribute()
    {
      var className = typeof(FooHandleErrorAttribute).FullName ?? typeof(FooHandleErrorAttribute).Name;
      _TraceSource = new TraceSource(className);
    }

    public override void OnException(ExceptionContext filterContext)
    {
      var actionMethodInfo = GetControllerAction(filterContext.Exception);
      // It's probably an error if we cannot find a controller action. But, hey, what should we do about it here?
      if(actionMethodInfo == null) return;

      var controllerName = filterContext.Controller.GetType().FullName; // filterContext.RouteData.Values[@"controller"];
      var actionName = actionMethodInfo.Name; // filterContext.RouteData.Values[@"action"];

      // Log the exception to the trace source
      var traceMessage = string.Format(@"Unhandled exception from {0}.{1} handled in {2}. Exception: {3}", controllerName, actionName, typeof(FooHandleErrorAttribute).FullName, filterContext.Exception);
      _TraceSource.TraceEvent(TraceEventType.Error, TraceEventId.UnhandledException, traceMessage);

      // Don't modify result if custom errors not enabled
      //if (!filterContext.HttpContext.IsCustomErrorEnabled)
      //  return;

      // We only handle actions with return type of JsonResult - I don't use AjaxRequestExtensions.IsAjaxRequest() because ajax requests does NOT imply JSON result.
      // (The downside is that you cannot just specify the return type as ActionResult - however I don't consider this a bad thing)
      if (actionMethodInfo.ReturnType != typeof(JsonResult)) return;

      // Handle JsonResult action exception by creating a useful JSON object which can be used client side
      // Only provide error message if we have an MySpecialExceptionWithUserMessage.
      var jsonMessage = FooHandleErrorAttributeResources.Error_Occured;
      if (filterContext.Exception is MySpecialExceptionWithUserMessage) jsonMessage = filterContext.Exception.Message;
      filterContext.Result = new JsonResult
        {
          Data = new
            {
              message = jsonMessage,
              // Only include stacktrace information in development environment
              stacktrace = MyEnvironmentHelper.IsDebugging ? filterContext.Exception.StackTrace : null
            },
          // Allow JSON get requests because we are already using this approach. However, we should consider avoiding this habit.
          JsonRequestBehavior = JsonRequestBehavior.AllowGet
        };

      // Exception is now (being) handled - set the HTTP error status code and prevent caching! Otherwise you'll get an HTTP 200 status code and running the risc of the browser caching the result.
      filterContext.ExceptionHandled = true;
      filterContext.HttpContext.Response.StatusCode = (int)HttpStatusCode.InternalServerError; // Consider using more error status codes depending on the type of exception
      filterContext.HttpContext.Response.Cache.SetCacheability(HttpCacheability.NoCache);

      // Call the overrided method
      base.OnException(filterContext);
    }

    /// <summary>
    /// Does anybody know a better way to obtain the controller action method info?
    /// See http://stackoverflow.com/questions/2770303/how-to-find-in-which-controller-action-an-error-occurred.
    /// </summary>
    /// <param name="exception"></param>
    /// <returns></returns>
    private static MethodInfo GetControllerAction(Exception exception)
    {
      var stackTrace = new StackTrace(exception);
      var frames = stackTrace.GetFrames();
      if(frames == null) return null;
      var frame = frames.FirstOrDefault(f => typeof(IController).IsAssignableFrom(f.GetMethod().DeclaringType));
      if (frame == null) return null;
      var actionMethod = frame.GetMethod();
      return actionMethod as MethodInfo;
    }
  }
}

I've developed the following jQuery plugin for client side ease of use:

(function ($, undefined) {
  "using strict";

  $.FooGetJSON = function (url, data, success, error) {
    /// <summary>
    /// **********************************************************
    /// * UNIK GET JSON JQUERY PLUGIN.                           *
    /// **********************************************************
    /// This plugin is a wrapper for jQuery.getJSON.
    /// The reason is that jQuery.getJSON success handler doesn't provides access to the JSON object returned from the url
    /// when a HTTP status code different from 200 is encountered. However, please note that whether there is JSON
    /// data or not depends on the requested service. if there is no JSON data (i.e. response.responseText cannot be
    /// parsed as JSON) then the data parameter will be undefined.
    ///
    /// This plugin solves this problem by providing a new error handler signature which includes a data parameter.
    /// Usage of the plugin is much equal to using the jQuery.getJSON method. Handlers can be added etc. However,
    /// the only way to obtain an error handler with the signature specified below with a JSON data parameter is
    /// to call the plugin with the error handler parameter directly specified in the call to the plugin.
    ///
    /// success: function(data, textStatus, jqXHR)
    /// error: function(data, jqXHR, textStatus, errorThrown)
    ///
    /// Example usage:
    ///
    ///   $.FooGetJSON('/foo', { id: 42 }, function(data) { alert('Name :' + data.name); }, function(data) { alert('Error: ' + data.message); });
    /// </summary>

    // Call the ordinary jQuery method
    var jqxhr = $.getJSON(url, data, success);

    // Do the error handler wrapping stuff to provide an error handler with a JSON object - if the response contains JSON object data
    if (typeof error !== "undefined") {
      jqxhr.error(function(response, textStatus, errorThrown) {
        try {
          var json = $.parseJSON(response.responseText);
          error(json, response, textStatus, errorThrown);
        } catch(e) {
          error(undefined, response, textStatus, errorThrown);
        }
      });
    }

    // Return the jQueryXmlHttpResponse object
    return jqxhr;
  };
})(jQuery);

What do I get from all this? The final result is that

  • None of my controller actions has requirements on HandleErrorAttributes.
  • None of my controller actions contains any repetitive boiler plate error handling code.
  • I have a single point of error handling code allowing me to easily change logging and other error handling related stuff.
  • A simple requirement: Controller actions returning JsonResult's must have return type JsonResult and not some base type like ActionResult. Reason: See code comment in FooHandleErrorAttribute.

Client side example:

var success = function(data) {
  alert(data.myjsonobject.foo);
};
var onError = function(data) {
  var message = "Error";
  if(typeof data !== "undefined")
    message += ": " + data.message;
  alert(message);
};
$.FooGetJSON(url, params, onSuccess, onError);

Comments are most welcome! I'll probably blog about this solution some day...

git pull remote branch cannot find remote ref

check your branch on your repo. maybe someone delete it.

How to create custom config section in app.config?

Import namespace :

using System.Configuration;

Create ConfigurationElement Company :

public class Company : ConfigurationElement
{

        [ConfigurationProperty("name", IsRequired = true)]
        public string Name
        {
            get
            {
                return this["name"] as string;
            }
        }
            [ConfigurationProperty("code", IsRequired = true)]
        public string Code
        {
            get
            {
                return this["code"] as string;
            }
        }
}

ConfigurationElementCollection:

public class Companies
        : ConfigurationElementCollection
    {
        public Company this[int index]
        {
            get
            {
                return base.BaseGet(index) as Company ;
            }
            set
            {
                if (base.BaseGet(index) != null)
                {
                    base.BaseRemoveAt(index);
                }
                this.BaseAdd(index, value);
            }
        }

       public new Company this[string responseString]
       {
            get { return (Company) BaseGet(responseString); }
            set
            {
                if(BaseGet(responseString) != null)
                {
                    BaseRemoveAt(BaseIndexOf(BaseGet(responseString)));
                }
                BaseAdd(value);
            }
        }

        protected override System.Configuration.ConfigurationElement CreateNewElement()
        {
            return new Company();
        }

        protected override object GetElementKey(System.Configuration.ConfigurationElement element)
        {
            return ((Company)element).Name;
        }
    }

and ConfigurationSection:

public class RegisterCompaniesConfig
        : ConfigurationSection
    {

        public static RegisterCompaniesConfig GetConfig()
        {
            return (RegisterCompaniesConfig)System.Configuration.ConfigurationManager.GetSection("RegisterCompanies") ?? new RegisterCompaniesConfig();
        }

        [System.Configuration.ConfigurationProperty("Companies")]
            [ConfigurationCollection(typeof(Companies), AddItemName = "Company")]
        public Companies Companies
        {
            get
            {
                object o = this["Companies"];
                return o as Companies ;
            }
        }

    }

and you must also register your new configuration section in web.config (app.config):

<configuration>       
    <configSections>
          <section name="Companies" type="blablabla.RegisterCompaniesConfig" ..>

then you load your config with

var config = RegisterCompaniesConfig.GetConfig();
foreach(var item in config.Companies)
{
   do something ..
}

How to reference image resources in XAML?

  1. Add folders to your project and add images to these through "Existing Item".
  2. XAML similar to this: <Image Source="MyRessourceDir\images\addButton.png"/>
  3. F6 (Build)

Auto increment primary key in SQL Server Management Studio 2012

You can use the keyword IDENTITY as the data type to the column along with PRIMARY KEY constraint when creating the table.
ex:

StudentNumber IDENTITY(1,1) PRIMARY KEY

In here the first '1' means the starting value and the second '1' is the incrementing value.

Markdown to create pages and table of contents?

Here is a short PHP code I use to generate the TOC, and enrich any headings with anchor:

$toc = []; //initialize the toc to an empty array
$markdown = "... your mardown content here...";

$markdown = preg_replace_callback("/(#+)\s*([^\n]+)/",function($matches) use (&$toc){
    static $section = [];
    $h = strlen($matches[1]);

    @$section[$h-1]++;
    $i = $h;
    while(isset($section[$i])) unset($section[$i++]);

    $anchor = preg_replace('/\s+/','-', strtolower(trim($matches[2])));

    $toc[] = str_repeat('  ',$h-1)."* [".implode('.',$section).". {$matches[2]}](#$anchor)";
    return str_repeat('#',$h)." <strong>".implode('.',$section).".</strong> ".$matches[2]."\n<a name=\"$anchor\"></a>\n";
}, $markdown);

You can then print the processed markdown and toc:

   print(implode("\n",$toc));
   print("\n\n");
   print($markdown);

List of all special characters that need to be escaped in a regex

The Pattern.quote(String s) sort of does what you want. However it leaves a little left to be desired; it doesn't actually escape the individual characters, just wraps the string with \Q...\E.

There is not a method that does exactly what you are looking for, but the good news is that it is actually fairly simple to escape all of the special characters in a Java regular expression:

regex.replaceAll("[\\W]", "\\\\$0")

Why does this work? Well, the documentation for Pattern specifically says that its permissible to escape non-alphabetic characters that don't necessarily have to be escaped:

It is an error to use a backslash prior to any alphabetic character that does not denote an escaped construct; these are reserved for future extensions to the regular-expression language. A backslash may be used prior to a non-alphabetic character regardless of whether that character is part of an unescaped construct.

For example, ; is not a special character in a regular expression. However, if you escape it, Pattern will still interpret \; as ;. Here are a few more examples:

  • > becomes \> which is equivalent to >
  • [ becomes \[ which is the escaped form of [
  • 8 is still 8.
  • \) becomes \\\) which is the escaped forms of \ and ( concatenated.

Note: The key is is the definition of "non-alphabetic", which in the documentation really means "non-word" characters, or characters outside the character set [a-zA-Z_0-9].

How to compare variables to undefined, if I don’t know whether they exist?

The best way is to check the type, because undefined/null/false are a tricky thing in JS. So:

if(typeof obj !== "undefined") {
    // obj is a valid variable, do something here.
}

Note that typeof always returns a string, and doesn't generate an error if the variable doesn't exist at all.

Check if enum exists in Java

You can also use Guava and do something like this:

// This method returns enum for a given string if it exists, otherwise it returns default enum.
private MyEnum getMyEnum(String enumName) {
  // It is better to return default instance of enum instead of null
  return hasMyEnum(enumName) ? MyEnum.valueOf(enumName) : MyEnum.DEFAULT;
}

// This method checks that enum for a given string exists.
private boolean hasMyEnum(String enumName) {
  return Iterables.any(Arrays.asList(MyEnum.values()), new Predicate<MyEnum>() {
    public boolean apply(MyEnum myEnum) {
      return myEnum.name().equals(enumName);
    }
  }); 
}

In second method I use guava (Google Guava) library which provides very useful Iterables class. Using the Iterables.any() method we can check if a given value exists in a list object. This method needs two parameters: a list and Predicate object. First I used Arrays.asList() method to create a list with all enums. After that I created new Predicate object which is used to check if a given element (enum in our case) satisfies the condition in apply method. If that happens, method Iterables.any() returns true value.

Migration: Cannot add foreign key constraint

Using Laravel 5.3 had the same problem.

The solution was to use unsignedInteger instead of integer('name')->unsigned().

So this is what worked

$table->unsignedInt('column_name');
$table->foreign('column_name')->references('id')->on('table_name');

The reason this worked is the fact that when using integer('name')->unsigned the column created in the table had length 11, but when using unsigedInteger('name') the column had length 10.

Length 10 is the length for primary keys when using Laravel so the columns length matched.

How to enable DataGridView sorting when user clicks on the column header?

You don't need to create a binding datasource. If you want to apply sorting for all of your columns, here is a more generic solution of mine;

private int _previousIndex;
private bool _sortDirection;

private void gridView_ColumnHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e)
{
    if (e.ColumnIndex == _previousIndex)
        _sortDirection ^= true; // toggle direction

    gridView.DataSource = SortData(
        (List<MainGridViewModel>)gridReview.DataSource, gridReview.Columns[e.ColumnIndex].Name, _sortDirection);

    _previousIndex = e.ColumnIndex;
}

public List<MainGridViewModel> SortData(List<MainGridViewModel> list, string column, bool ascending)
{
    return ascending ? 
        list.OrderBy(_ => _.GetType().GetProperty(column).GetValue(_)).ToList() :
        list.OrderByDescending(_ => _.GetType().GetProperty(column).GetValue(_)).ToList();
}

Make sure you subscribe your data grid to the event ColumnHeaderMouseClick. When the user clicks on the column it will sort by descending. If the same column header is clicked again, sorting will be applied by ascending.

What are the Differences Between "php artisan dump-autoload" and "composer dump-autoload"?

Laravel's Autoload is a bit different:

1) It will in fact use Composer for some stuff

2) It will call Composer with the optimize flag

3) It will 'recompile' loads of files creating the huge bootstrap/compiled.php

4) And also will find all of your Workbench packages and composer dump-autoload them, one by one.

Loading DLLs at runtime in C#

Members must be resolvable at compile time to be called directly from C#. Otherwise you must use reflection or dynamic objects.

Reflection

namespace ConsoleApplication1
{
    using System;
    using System.Reflection;

    class Program
    {
        static void Main(string[] args)
        {
            var DLL = Assembly.LoadFile(@"C:\visual studio 2012\Projects\ConsoleApplication1\ConsoleApplication1\DLL.dll");

            foreach(Type type in DLL.GetExportedTypes())
            {
                var c = Activator.CreateInstance(type);
                type.InvokeMember("Output", BindingFlags.InvokeMethod, null, c, new object[] {@"Hello"});
            }

            Console.ReadLine();
        }
    }
}

Dynamic (.NET 4.0)

namespace ConsoleApplication1
{
    using System;
    using System.Reflection;

    class Program
    {
        static void Main(string[] args)
        {
            var DLL = Assembly.LoadFile(@"C:\visual studio 2012\Projects\ConsoleApplication1\ConsoleApplication1\DLL.dll");

            foreach(Type type in DLL.GetExportedTypes())
            {
                dynamic c = Activator.CreateInstance(type);
                c.Output(@"Hello");
            }

            Console.ReadLine();
        }
    }
}

Can I export a variable to the environment from a bash script without sourcing it?

The answer is no, but for me I did the following

the script: myExport

#! \bin\bash
export $1

an alias in my .bashrc

alias myExport='source myExport' 

Still you source it, but maybe in this way it is more useable and it is interesting for someone else.

Difference between signed / unsigned char

I slightly disagree with the above. The unsigned char simply means: Use the most significant bit instead of treating it as a bit flag for +/- sign when performing arithmetic operations.

It makes significance if you use char as a number for instance:

typedef char BYTE1;
typedef unsigned char BYTE2;

BYTE1 a;
BYTE2 b;

For variable a, only 7 bits are available and its range is (-127 to 127) = (+/-)2^7 -1. For variable b all 8 bits are available and the range is 0 to 255 (2^8 -1).

If you use char as character, "unsigned" is completely ignored by the compiler just as comments are removed from your program.

Show hide div using codebehind

There are a few ways to handle rendering/showing controls on the page and you should take note to what happens with each method.

Rendering and Visibility

There are some instances where elements on your page don't need to be rendered for the user because of some type of logic or database value. In this case, you can prevent rendering (creating the control on the returned web page) altogether. You would want to do this if the control doesn't need to be shown later on the client side because no matter what, the user viewing the page never needs to see it.

Any controls or elements can have their visibility set from the server side. If it is a plain old html element, you just need to set the runat attribute value to server on the markup page.

<div id="myDiv" runat="server"></div>

The decision to render the div or not can now be done in the code behind class like so:

myDiv.Visible = someConditionalBool;

If set to true, it will be rendered on the page and if it's false it won't be rendered at all, not even hidden.

Client Side Hiding

Hiding an element is done on the client side only. Meaning, it's rendered but it has a display CSS style set on it which instructs your browser to not show it to the user. This is beneficial when you want to hide/show things based on user input. It's important to know that the element CAN be hidden on the server side too as long as the element/control has runat=server set just as I explained in the previous example.

Hiding in the Code Behind Class

To hide an element that you want rendered to the page but hidden is another simple single line of code:

myDiv.Style["display"] = "none";

If you have a need to remove the display style server side, it can be done by removing the display style, or setting it to a different value like inline or block (values described here).

myDiv.Style.Remove("display");
// -- or --
myDiv.Style["display"] = "inline";

Hiding on the Client Side with javascript

Using plain old javascript, you can easily hide the same element in this manner

var myDivElem = document.getElementById("myDiv");
myDivElem.style.display = "none";

// then to show again
myDivElem.style.display = "";

jQuery makes hiding elements a little simpler if you prefer to use jQuery:

var myDiv = $("#<%=myDiv.ClientID%>");
myDiv.hide();

// ... and to show 
myDiv.show();

Http Post request with content type application/x-www-form-urlencoded not working in Spring

The solution can be found here https://github.com/spring-projects/spring-framework/issues/22734

you can create two separate post request mappings. For example.

@PostMapping(path = "/test", consumes = "application/json")
public String test(@RequestBody User user) {
  return user.toString();
}

@PostMapping(path = "/test", consumes = "application/x-www-form-urlencoded")
public String test(User user) {
  return user.toString();
}

What does asterisk * mean in Python?

All of the above answers were perfectly clear and complete, but just for the record I'd like to confirm that the meaning of * and ** in python has absolutely no similarity with the meaning of similar-looking operators in C.

They are called the argument-unpacking and keyword-argument-unpacking operators.

Apache 2.4 - Request exceeded the limit of 10 internal redirects due to probable configuration error

This problem can be caused by requests for certain files that don't exist. For example, requests for files in wp-content/uploads/ where the file does not exist.

If this is the situation you're seeing, you can solve the problem by going to .htaccess and changing this line:

RewriteRule ^(wp-(content|admin|includes).*) $1 [L]

to:

RewriteRule ^(wp-(content|admin|includes).*) - [L]

The underlying issue is that the rule above triggers a rewrite to the exact same url with a slash in front and because there was a rewrite, the newly rewritten request goes back through the rules again and the same rule is triggered. By changing that line's "$1" to "-", no rewrite happens and so the rewriting process does not start over again with the same URL.

It's possible that there's a difference in how apache 2.2 and 2.4 handle this situation of only-difference-is-a-slash-in-front and that's why the default rules provided by WordPress aren't working perfectly.

Passing a 2D array to a C++ function

You are allowed to omit the leftmost dimension and so you end up with two options:

void f1(double a[][2][3]) { ... }

void f2(double (*a)[2][3]) { ... }

double a[1][2][3];

f1(a); // ok
f2(a); // ok 

This is the same with pointers:

// compilation error: cannot convert ‘double (*)[2][3]’ to ‘double***’ 
// double ***p1 = a;

// compilation error: cannot convert ‘double (*)[2][3]’ to ‘double (**)[3]’
// double (**p2)[3] = a;

double (*p3)[2][3] = a; // ok

// compilation error: array of pointers != pointer to array
// double *p4[2][3] = a;

double (*p5)[3] = a[0]; // ok

double *p6 = a[0][1]; // ok

The decay of an N dimensional array to a pointer to N-1 dimensional array is allowed by C++ standard, since you can lose the leftmost dimension and still being able to correctly access array elements with N-1 dimension information.

Details in here

Though, arrays and pointers are not the same: an array can decay into a pointer, but a pointer doesn't carry state about the size/configuration of the data to which it points.

A char ** is a pointer to a memory block containing character pointers, which themselves point to memory blocks of characters. A char [][] is a single memory block which contains characters. This has an impact on how the compiler translate the code and how the final performance will be.

Source

Length of array in function argument

First, a better usage to compute number of elements when the actual array declaration is in scope is:

sizeof array / sizeof array[0]

This way you don't repeat the type name, which of course could change in the declaration and make you end up with an incorrect length computation. This is a typical case of don't repeat yourself.

Second, as a minor point, please note that sizeof is not a function, so the expression above doesn't need any parenthesis around the argument to sizeof.

Third, C doesn't have references so your usage of & in a declaration won't work.

I agree that the proper C solution is to pass the length (using the size_t type) as a separate argument, and use sizeof at the place the call is being made if the argument is a "real" array.

Note that often you work with memory returned by e.g. malloc(), and in those cases you never have a "true" array to compute the size off of, so designing the function to use an element count is more flexible.

Can I rollback a transaction I've already committed? (data loss)

No, you can't undo, rollback or reverse a commit.

STOP THE DATABASE!

(Note: if you deleted the data directory off the filesystem, do NOT stop the database. The following advice applies to an accidental commit of a DELETE or similar, not an rm -rf /data/directory scenario).

If this data was important, STOP YOUR DATABASE NOW and do not restart it. Use pg_ctl stop -m immediate so that no checkpoint is run on shutdown.

You cannot roll back a transaction once it has commited. You will need to restore the data from backups, or use point-in-time recovery, which must have been set up before the accident happened.

If you didn't have any PITR / WAL archiving set up and don't have backups, you're in real trouble.

Urgent mitigation

Once your database is stopped, you should make a file system level copy of the whole data directory - the folder that contains base, pg_clog, etc. Copy all of it to a new location. Do not do anything to the copy in the new location, it is your only hope of recovering your data if you do not have backups. Make another copy on some removable storage if you can, and then unplug that storage from the computer. Remember, you need absolutely every part of the data directory, including pg_xlog etc. No part is unimportant.

Exactly how to make the copy depends on which operating system you're running. Where the data dir is depends on which OS you're running and how you installed PostgreSQL.

Ways some data could've survived

If you stop your DB quickly enough you might have a hope of recovering some data from the tables. That's because PostgreSQL uses multi-version concurrency control (MVCC) to manage concurrent access to its storage. Sometimes it will write new versions of the rows you update to the table, leaving the old ones in place but marked as "deleted". After a while autovaccum comes along and marks the rows as free space, so they can be overwritten by a later INSERT or UPDATE. Thus, the old versions of the UPDATEd rows might still be lying around, present but inaccessible.

Additionally, Pg writes in two phases. First data is written to the write-ahead log (WAL). Only once it's been written to the WAL and hit disk, it's then copied to the "heap" (the main tables), possibly overwriting old data that was there. The WAL content is copied to the main heap by the bgwriter and by periodic checkpoints. By default checkpoints happen every 5 minutes. If you manage to stop the database before a checkpoint has happened and stopped it by hard-killing it, pulling the plug on the machine, or using pg_ctl in immediate mode you might've captured the data from before the checkpoint happened, so your old data is more likely to still be in the heap.

Now that you have made a complete file-system-level copy of the data dir you can start your database back up if you really need to; the data will still be gone, but you've done what you can to give yourself some hope of maybe recovering it. Given the choice I'd probably keep the DB shut down just to be safe.

Recovery

You may now need to hire an expert in PostgreSQL's innards to assist you in a data recovery attempt. Be prepared to pay a professional for their time, possibly quite a bit of time.

I posted about this on the Pg mailing list, and ?????? ?????? linked to depesz's post on pg_dirtyread, which looks like just what you want, though it doesn't recover TOASTed data so it's of limited utility. Give it a try, if you're lucky it might work.

See: pg_dirtyread on GitHub.

I've removed what I'd written in this section as it's obsoleted by that tool.

See also PostgreSQL row storage fundamentals

Prevention

See my blog entry Preventing PostgreSQL database corruption.


On a semi-related side-note, if you were using two phase commit you could ROLLBACK PREPARED for a transction that was prepared for commit but not fully commited. That's about the closest you get to rolling back an already-committed transaction, and does not apply to your situation.

How to upgrade Angular CLI to the latest version

In addition to @ShinDarth answer.

I did what he said but my package did not updated the angular version, and I know that this post is about angular-cli, but i think that this can help too.

  • so after doing what @ShinDarth said above, to fix my angular version I had to create a new project with -ng new projectname that generated a package.
  • copy the new package, then paste the new package on all projects packages needing update (remember to add the dependencies you had and change the name on first line) or you can just change the versions manualy without copy and paste.
  • then run -npm install.

Now my ng serve is working again, maybe there is a better way to do all that, if someone know, please share, because this is a pain to do with all projects that need update.

Regex matching beginning AND end strings

Well, the simple regex is this:

/^dbo\..*_fn$/

It would be better, however, to use the string manipulation functionality of whatever programming language you're using to slice off the first four and the last three characters of the string and check whether they're what you want.

implement addClass and removeClass functionality in angular2

You can basically switch the class using [ngClass]

for example

<button [ngClass]="{'active': selectedItem === 'item1'}" (click)="selectedItem = 'item1'">Button One</button>
<button [ngClass]="{'active': selectedItem === 'item2'}" (click)="selectedItem = 'item2'">Button Two</button>

No resource found that matches the given name '@style/ Theme.Holo.Light.DarkActionBar'

Make sure you've set your target API (different from the target SDK) in the Project Properties (not the manifest) to be at least 4.0/API 14.

How Best to Compare Two Collections in Java and Act on Them?

For comaparing a list or set we can use Arrays.equals(object[], object[]). It will check for the values only. To get the Object[] we can use Collection.toArray() method.

Multiple HttpPost method in Web API controller

I think the question has already been answered. I was also looking for something a webApi controller that has same signatured mehtods but different names. I was trying to implement the Calculator as WebApi. Calculator has 4 methods with the same signature but different names.

public class CalculatorController : ApiController
{
    [HttpGet]
    [ActionName("Add")]
    public string Add(int num1 = 1, int num2 = 1, int timeDelay = 1)
    {
        Thread.Sleep(1000 * timeDelay);
        return string.Format("Add = {0}", num1 + num2);
    }

    [HttpGet]
    [ActionName("Sub")]
    public string Sub(int num1 = 1, int num2 = 1, int timeDelay = 1)
    {
        Thread.Sleep(1000 * timeDelay);
        return string.Format("Subtract result = {0}", num1 - num2);
    }

    [HttpGet]
    [ActionName("Mul")]
    public string Mul(int num1 = 1, int num2 = 1, int timeDelay = 1)
    {
        Thread.Sleep(1000 * timeDelay);
        return string.Format("Multiplication result = {0}", num1 * num2);
    }

    [HttpGet]
    [ActionName("Div")]
    public string Div(int num1 = 1, int num2 = 1, int timeDelay = 1)
    {
        Thread.Sleep(1000 * timeDelay);
        return string.Format("Division result = {0}", num1 / num2);
    }
}

and in the WebApiConfig file you already have

 config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{action}/{id}",
            defaults: new { id = RouteParameter.Optional });

Just set the authentication / authorisation on IIS and you are done!

Hope this helps!

Invalid URI: The format of the URI could not be determined

Sounds like it might be a realative uri. I ran into this problem when doing cross-browser Silverlight; on my blog I mentioned a workaround: pass a "context" uri as the first parameter.

If the uri is realtive, the context uri is used to create a full uri. If the uri is absolute, then the context uri is ignored.

EDIT: You need a "scheme" in the uri, e.g., "ftp://" or "http://"

Difference between using bean id and name in Spring configuration file

let me answer below question

Is there any difference between using an id attribute and using a name attribute on a <bean> tag,

There is no difference. you will experience same effect when id or name is used on a <bean> tag .

How?

Both id and name attributes are giving us a means to provide identifier value to a bean (For this moment, think id means id but not identifier). In both the cases, you will see same result if you call applicationContext.getBean("bean-identifier"); .

Take @Bean, the java equivalent of <bean> tag, you wont find an id attribute. you can give your identifier value to @Bean only through name attribute.

Let me explain it through an example :
Take this configuration file, let's call it as spring1.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans ...>
  <bean id="foo" class="com.intertech.Foo"></bean>
  <bean id="bar" class="com.intertech.Bar"></bean>
</beans>

Spring returns Foo object for, Foo f = (Foo) context.getBean("foo"); . Replace id="foo" with name="foo" in the above spring1.xml, You will still see the same result.

Define your xml configuration like,

<?xml version="1.0" encoding="UTF-8"?>
<beans ...>
  <bean id="fooIdentifier" class="com.intertech.Foo"></bean>
  <bean name="fooIdentifier" class="com.intertech.Foo"></bean>
</beans>

You will get BeanDefinitionParsingException. It will say, Bean name 'fooIdentifier' is already used in this element. By the way, This is the same exception you will see if you have below config
<bean name="fooIdentifier" class="com.intertech.Foo"></bean>
<bean name="fooIdentifier" class="com.intertech.Foo"></bean>


If you keep both id and name to the bean tag, the bean is said to have 2 identifiers. you can get the same bean with any identifier. take config as

<?xml version="1.0" encoding="UTF-8"?><br>
<beans ...>
  <bean id="fooById" name="fooByName" class="com.intertech.Foo"></bean>
  <bean id="bar" class="com.intertech.Bar"></bean>
</beans>

the following code prints true

FileSystemXmlApplicationContext context = new FileSystemXmlApplicationContext(...);
Foo fooById = (Foo) context.getBean("fooById")// returns Foo object;
Foo fooByName = (Foo) context.getBean("fooByName")// returns Foo object;
System.out.println(fooById == fooByName) //true

Limit Decimal Places in Android EditText

This implementation of InputFilter solves the problem.

import android.text.SpannableStringBuilder;
import android.text.Spanned;
import android.text.method.DigitsKeyListener;

public class MoneyValueFilter extends DigitsKeyListener {
    public MoneyValueFilter() {
        super(false, true);
    }

    private int digits = 2;

    public void setDigits(int d) {
        digits = d;
    }

    @Override
    public CharSequence filter(CharSequence source, int start, int end,
            Spanned dest, int dstart, int dend) {
        CharSequence out = super.filter(source, start, end, dest, dstart, dend);

        // if changed, replace the source
        if (out != null) {
            source = out;
            start = 0;
            end = out.length();
        }

        int len = end - start;

        // if deleting, source is empty
        // and deleting can't break anything
        if (len == 0) {
            return source;
        }

        int dlen = dest.length();

        // Find the position of the decimal .
        for (int i = 0; i < dstart; i++) {
            if (dest.charAt(i) == '.') {
                // being here means, that a number has
                // been inserted after the dot
                // check if the amount of digits is right
                return (dlen-(i+1) + len > digits) ? 
                    "" :
                    new SpannableStringBuilder(source, start, end);
            }
        }

        for (int i = start; i < end; ++i) {
            if (source.charAt(i) == '.') {
                // being here means, dot has been inserted
                // check if the amount of digits is right
                if ((dlen-dend) + (end-(i + 1)) > digits)
                    return "";
                else
                    break;  // return new SpannableStringBuilder(source, start, end);
            }
        }

        // if the dot is after the inserted part,
        // nothing can break
        return new SpannableStringBuilder(source, start, end);
    }
}

To use:

editCoin.setFilters(new InputFilter[] {new MoneyValueFilter(2)});

PHP FPM - check if running

Here is how you can do it with a socket on php-fpm 7

install socat
apt-get install socat

#!/bin/sh

  if echo /dev/null | socat UNIX:/var/run/php/php7.0-fpm.sock - ; then
    echo "$home/run/php-fpm.sock connect OK"
  else
    echo "$home/run/php-fpm.sock connect ERROR"
  fi

You can also check if the service is running like this.

service php7.0-fpm status | grep running

It will return

Active: active (running) since Sun 2017-04-09 12:48:09 PDT; 48s ago

Regex to validate JSON

I realize that this is from over 6 years ago. However, I think there is a solution that nobody here has mentioned that is way easier than regexing

function isAJSON(string) {
    try {
        JSON.parse(string)  
    } catch(e) {
        if(e instanceof SyntaxError) return false;
    };  
    return true;
}

How to access a RowDataPacket object

I had this problem when trying to consume a value returned from a stored procedure.

console.log(result[0]);

would output "[ RowDataPacket { datetime: '2019-11-15 16:37:05' } ]".

I found that

console.log(results[0][0].datetime);

Gave me the value I wanted.

jQuery $(".class").click(); - multiple elements, click event once

Just do below code it's working absolute fine

$(".addproduct").on('click', function(event){
    event.stopPropagation();
    event.stopImmediatePropagation();
    getRecord();
});


function getRecord(){
   $(".addproduct").each(function () {
       console.log("test");
       });

}

Regex Letters, Numbers, Dashes, and Underscores

Your expression should already match dashes, because the final - will not be interpreted as a range operator (since the range has no end). To add underscores as well, try:

([A-Za-z0-9_-]+)

onKeyPress Vs. onKeyUp and onKeyDown

First, they have different meaning: they fire:

  • KeyDown – when a key was pushed down
  • KeyUp – when a pushed button was released, and after the value of input/textarea is updated (the only one among these)
  • KeyPress – between those and doesn't actually mean a key was pushed and released (see below).

Second, some keys fire some of these events and don't fire others. For instance,

  • KeyPress ignores delete, arrows, PgUp/PgDn, home/end, ctrl, alt, shift etc while KeyDown and KeyUp don't (see details about esc below);
  • when you switch window via alt+tab in Windows, only KeyDown for alt fires because window switching happens before any other event (and KeyDown for tab is prevented by system, I suppose, at least in Chrome 71).

Also, you should keep in mind that event.keyCode (and event.which) usually have same value for KeyDown and KeyUp but different one for KeyPress. Try the playground I've created. By the way, I've noticed quite a quirk: in Chrome, when I press ctrl+a and the input/textarea is empty, for KeyPress fires with event.keyCode (and event.which) equal to 1! (when the input is not empty, it doesn't fire at all).

Finally, there's some pragmatics:

  • For handling arrows, you'll probably need to use onKeyDown: if user holds ?, KeyDown fires several times (while KeyUp fires only once when they release the button). Also, in some cases you can easily prevent propagation of KeyDown but can't (or can't that easily) prevent propagation of KeyUp (for instance, if you want to submit on enter without adding newline to the text field).
  • Suprisingly, when you hold a key, say in textarea, both KeyPress and KeyDown fire multiple times (Chrome 71), I'd use KeyDown if I need the event that fires multiple times and KeyUp for single key release.
  • KeyDown is usually better for games when you have to provide better responsiveness to their actions.
  • esc is usually processed via KeyDown: KeyPress doesn't fire and KeyUp behaves differently for inputs and textareas in different browsers (mostly due to loss of focus)
  • If you'd like to adjust height of a text area to the content, you probably won't use onKeyDown but rather onKeyPress (PS ok, it's actually better to use onChange for this case).

I've used all 3 in my project but unfortunately may have forgotten some of pragmatics. (to be noted: there's also input and change events)

Could not resolve placeholder in string value

You can also try default values. spring-value-annotation

Default values can be provided for properties that might not be defined. In this example the value “some default” will be injected:

@Value("${unknown.param:some default}")
private String someDefault;

If the same property is defined as a system property and in the properties file, then the system property would be applied.

Detecting when user scrolls to bottom of div with jQuery

I have crafted this piece of code that worked for me to detect when I scroll to the end of an element!

let element = $('.element');

if ($(document).scrollTop() > element.offset().top + element.height()) {

     /// do something ///
}

Manually install Gradle and use it in Android Studio

I used like this,

distributionUrl=file\:///E\:/Android/Gradle/gradle-5.4.1-all.zip

And its worked for me.

Which is faster: Stack allocation or Heap allocation

Stack is much faster. It literally only uses a single instruction on most architectures, in most cases, e.g. on x86:

sub esp, 0x10

(That moves the stack pointer down by 0x10 bytes and thereby "allocates" those bytes for use by a variable.)

Of course, the stack's size is very, very finite, as you will quickly find out if you overuse stack allocation or try to do recursion :-)

Also, there's little reason to optimize the performance of code that doesn't verifiably need it, such as demonstrated by profiling. "Premature optimization" often causes more problems than it's worth.

My rule of thumb: if I know I'm going to need some data at compile-time, and it's under a few hundred bytes in size, I stack-allocate it. Otherwise I heap-allocate it.

Setting public class variables

You're "setting" the value of that variable/attribute. Not overriding or overloading it. Your code is very, very common and normal.

All of these terms ("set", "override", "overload") have specific meanings. Override and Overload are about polymorphism (subclassing).

From http://en.wikipedia.org/wiki/Object-oriented_programming :

Polymorphism allows the programmer to treat derived class members just like their parent class' members. More precisely, Polymorphism in object-oriented programming is the ability of objects belonging to different data types to respond to method calls of methods of the same name, each one according to an appropriate type-specific behavior. One method, or an operator such as +, -, or *, can be abstractly applied in many different situations. If a Dog is commanded to speak(), this may elicit a bark(). However, if a Pig is commanded to speak(), this may elicit an oink(). They both inherit speak() from Animal, but their derived class methods override the methods of the parent class; this is Overriding Polymorphism. Overloading Polymorphism is the use of one method signature, or one operator such as "+", to perform several different functions depending on the implementation. The "+" operator, for example, may be used to perform integer addition, float addition, list concatenation, or string concatenation. Any two subclasses of Number, such as Integer and Double, are expected to add together properly in an OOP language. The language must therefore overload the addition operator, "+", to work this way. This helps improve code readability. How this is implemented varies from language to language, but most OOP languages support at least some level of overloading polymorphism.

How to show only next line after the matched one?

you can use grep, then take lines in jumps:
grep -A1 'blah' logfile | awk 'NR%3==2'

you can also take n lines after match, for example:
seq 100 | grep -A3 .2 | awk 'NR%5==4'
15
25
35
45
55
65
75
85
95
explanation -
here we want to grep all lines that are *2 and take 3 lines after it, which is *5.
seq 100 | grep -A3 .2 will give you:
12
13
14
15
--
22
23
24
25
--
...
the number in the modulo (NR%5) is the added rows by grep (here it's 3 by the flag -A3), +2 extra lines because you have current matching line and also the -- line that the grep is adding.

Log to the base 2 in python

Try this ,

import math
print(math.log(8,2))  # math.log(number,base) 

How do I fix a Git detached head?

The detached HEAD means that you are currently not on any branch. If you want to KEEP your current changes and simply create a new branch, this is what you do:

git commit -m "your commit message"
git checkout -b new_branch

Afterwards, you potentially want to merge this new branch with other branches. Always helpful is the git "a dog" command:

git log --all --decorate --oneline --graph

Reading a binary input stream into a single byte array in Java

The simplest approach IMO is to use Guava and its ByteStreams class:

byte[] bytes = ByteStreams.toByteArray(in);

Or for a file:

byte[] bytes = Files.toByteArray(file);

Alternatively (if you didn't want to use Guava), you could create a ByteArrayOutputStream, and repeatedly read into a byte array and write into the ByteArrayOutputStream (letting that handle resizing), then call ByteArrayOutputStream.toByteArray().

Note that this approach works whether you can tell the length of your input or not - assuming you have enough memory, of course.

Credentials for the SQL Server Agent service are invalid

I had a domain account with a strong password, but it didn´t work, then I used Network Service account. I tried to change it on SQL Server Configuration Manager after installation and it worked.

Git push error pre-receive hook declined

Might not be the case, but this was the solution to my "pre-receive hook declined" error:

There are some repositories that only allow modifications through Pull Request. This means that you have to

  1. Create a new branch taking as base the branch that you want to push your changes to.
  2. Commit and push your changes to the new branch.
  3. Open a Pull Request to merge your branch with the original one.

What is the naming convention in Python for variable and function names?

Typically, one follow the conventions used in the language's standard library.

Convert int to char in java

In java a char is an int. Your first snippet prints out the character corresponding to the value of 1 in the default character encoding scheme (which is probably Unicode). The Unicode character U+0001 is a non-printing character, which is why you don't see any output.

If you want to print out the character '1', you can look up the value of '1' in the encoding scheme you are using. In Unicode this is 49 (the same as ASCII). But this will only work for digits 0-9.

You might be better off using a String rather than a char, and using Java's built-in toString() method:

int a = 1;
String b = toString(a);
System.out.println(b);

This will work whatever your system encoding is, and will work for multi-digit numbers.

jQuery AJAX submit form

This code works even with file input

$(document).on("submit", "form", function(event)
{
    event.preventDefault();        
    $.ajax({
        url: $(this).attr("action"),
        type: $(this).attr("method"),
        dataType: "JSON",
        data: new FormData(this),
        processData: false,
        contentType: false,
        success: function (data, status)
        {

        },
        error: function (xhr, desc, err)
        {


        }
    });        
});

Can constructors throw exceptions in Java?

Yes, constructors are allowed to throw exceptions.

However, be very wise in choosing what exceptions they should be - checked exceptions or unchecked. Unchecked exceptions are basically subclasses of RuntimeException.

In almost all cases (I could not come up with an exception to this case), you'll need to throw a checked exception. The reason being that unchecked exceptions (like NullPointerException) are normally due to programming errors (like not validating inputs sufficiently).

The advantage that a checked exception offers is that the programmer is forced to catch the exception in his instantiation code, and thereby realizes that there can be a failure to create the object instance. Of course, only a code review will catch the poor programming practice of swallowing an exception.

Benefits of EBS vs. instance-store (and vice-versa)

For someone new to all this and if accidentally landed here

As of now all AMI's in quickstart section are EBS backed

enter image description here

Also there's a good explanation at official doc for difference between EBS and Instance store

& this image pretty much sums it up enter image description here

HTML Table cellspacing or padding just top / bottom

CSS?

td {
  padding-top: 2px;
  padding-bottom: 2px;
}

Google Spreadsheet, Count IF contains a string

In case someone is still looking for the answer, this worked for me:

=COUNTIF(A2:A51, "*" & B1 & "*")

B1 containing the iPad string.

Equivalent of Clean & build in Android Studio?

In latest releases of Android Studio one more option has been added dedicatedly for Clean.

Build > Clean Project 

Is there a good Valgrind substitute for Windows?

I've been loving Memory Validator, from a company called Software Verification.

How to install an APK file on an Android phone?

I was using the command prompt to manually install the .apk file on my device (Nexus 7) but the following should work in theory on any android device (after enabling the device for developer mode). This method was becoming cumbersome so I created a simple batch file so now all I have to do is double-click it and it installs for me (device must be plugged in to my development machine). Just create a text file and save it as .BAT with the following text (customize to accommodate your file paths):

cd C:\{**path to your install location**}\sdk\platform-tools

adb install C:\{**path to your .apk file**}\{**project/apk file name**}.apk

Change visibility of ASP.NET label with JavaScript

Continuing with what Dave Ward said:

  • You can't set the Visible property to false because the control will not be rendered.
  • You should use the Style property to set it's display to none.

Page/Control design

<asp:Label runat="server" ID="Label1" Style="display: none;" />

<asp:Button runat="server" ID="Button1" />

Code behind

Somewhere in the load section:

Label label1 = (Label)FindControl("Label1");
((Label)FindControl("Button1")).OnClientClick = "ToggleVisibility('" + label1.ClientID + "')";

Javascript file

function ToggleVisibility(elementID)
{
    var element = document.getElementByID(elementID);

    if (element.style.display = 'none')
    {
        element.style.display = 'inherit';
    }
    else
    {
        element.style.display = 'none';
    }
}

Of course, if you don't want to toggle but just to show the button/label then adjust the javascript method accordingly.

The important point here is that you need to send the information about the ClientID of the control that you want to manipulate on the client side to the javascript file either setting global variables or through a function parameter as in my example.

How can I make Flexbox children 100% height of their parent?

Use align-items: stretch

Similar to David Storey's answer, my workaround is:

.flex-2 {
    display: flex;
    align-items: stretch;
}

Note that height: 100% should be removed from the child component even (see comments).

Alternatively to align-items, you can use align-self just on the .flex-2-child item you want stretched.

SQL Query NOT Between Two Dates

What you are currently doing is checking whether neither the start_date nor the end_date fall within the range of the dates given.

I guess what you are really looking for is a record which does not fit in the date range given. If so, use the query below.

SELECT * 
    FROM `test_table` 
    WHERE  CAST('2009-12-15' AS DATE) > start_date  AND  CAST('2010-01-02' AS DATE) < end_date

How to concat a string to xsl:value-of select="...?

The easiest way to concat a static text string to a selected value is to use element.

<a>
  <xsl:attribute name="href"> 
    <xsl:value-of select="/*/properties/property[@name='report']/@value" />
    <xsl:text>staticIconExample.png</xsl:text>
  </xsl:attribute>
</a>

You should not use <Link> outside a <Router>

For JEST users

if you use Jest for testing and this error happen just wrap your component with <BrowserRouter>

describe('Test suits for MyComponentWithLink', () => {
it('should match with snapshot', () => {
const tree = renderer
  .create(
    <BrowserRouter>
      <MyComponentWithLink/>
    </BrowserRouter>
  )
  .toJSON();
 expect(tree).toMatchSnapshot();
 });
});

Difference between onCreate() and onStart()?

onCreate() method gets called when activity gets created, and its called only once in whole Activity life cycle. where as onStart() is called when activity is stopped... I mean it has gone to background and its onStop() method is called by the os. onStart() may be called multiple times in Activity life cycle.More details here

Javascript Equivalent to C# LINQ Select

You can try manipula package, which implement all of C# LINQ methods and save its syntax: https://github.com/litichevskiydv/manipula

https://www.npmjs.com/package/manipula

Your example selectedFruits.select(fruit=>fruit.id); will be implemented with manipula as

Manipula.from(selectedFruits).select(fruit=>fruit.id);

Securely storing passwords for use in python script

Know the master key yourself. Don't hard code it.

Use py-bcrypt (bcrypt), powerful hashing technique to generate a password yourself.

Basically you can do this (an idea...)

import bcrypt
from getpass import getpass
master_secret_key = getpass('tell me the master secret key you are going to use')
salt = bcrypt.gensalt()
combo_password = raw_password + salt + master_secret_key
hashed_password = bcrypt.hashpw(combo_password, salt)

save salt and hashed password somewhere so whenever you need to use the password, you are reading the encrypted password, and test against the raw password you are entering again.

This is basically how login should work these days.

pip installs packages successfully, but executables not found from command line

In addition to adding python's bin directory to $PATH variable, I also had to change the owner of that directory, to make it work. No idea why I wasn't the owner already.

chown -R ~/Library/Python/