SyntaxFix

Programs & Examples On #Area

Area is a quantity that expresses the extent of a two-dimensional surface or shape, or planar lamina, in the plane.

Calculating the area under a curve given a set of coordinates, without knowing the function

The numpy and scipy libraries include the composite trapezoidal (numpy.trapz) and Simpson's (scipy.integrate.simps) rules.

Here's a simple example. In both trapz and simps, the argument dx=5 indicates that the spacing of the data along the x axis is 5 units.

from __future__ import print_function

import numpy as np
from scipy.integrate import simps
from numpy import trapz


# The y values.  A numpy array is used here,
# but a python list could also be used.
y = np.array([5, 20, 4, 18, 19, 18, 7, 4])

# Compute the area using the composite trapezoidal rule.
area = trapz(y, dx=5)
print("area =", area)

# Compute the area using the composite Simpson's rule.
area = simps(y, dx=5)
print("area =", area)

Output:

area = 452.5
area = 460.0

MATLAB, Filling in the area between two sets of data, lines in one figure

Building off of @gnovice's answer, you can actually create filled plots with shading only in the area between the two curves. Just use fill in conjunction with fliplr.

Example:

x=0:0.01:2*pi;                  %#initialize x array
y1=sin(x);                      %#create first curve
y2=sin(x)+.5;                   %#create second curve
X=[x,fliplr(x)];                %#create continuous x value array for plotting
Y=[y1,fliplr(y2)];              %#create y values for out and then back
fill(X,Y,'b');                  %#plot filled area

enter image description here

By flipping the x array and concatenating it with the original, you're going out, down, back, and then up to close both arrays in a complete, many-many-many-sided polygon.

ASP.NET strange compilation error

If you get the error "An error occurred during the compilation of a resource required to service this request. Compiler Error Message: The compiler failed with error code 255."

Try to terminate the processes "VBCSCompiler.exe". VBCSCompiler.exe can also be the problem if your application can not build due to the fact that some packages can not be transferred to the bin folder.

Bootstrap 3 - jumbotron background image effect

After inspecting the sample website you provided, I found that the author might achieve the effect by using a library called Stellar.js, take a look at the library site, cheers!

Proper way to initialize a C# dictionary with values?

I can't reproduce this issue in a simple .NET 4.0 console application:

static class Program
{
    static void Main(string[] args)
    {
        var myDict = new Dictionary<string, string>
        {
            { "key1", "value1" },
            { "key2", "value2" }
        };

        Console.ReadKey();
    }
}

Can you try to reproduce it in a simple Console application and go from there? It seems likely that you're targeting .NET 2.0 (which doesn't support it) or client profile framework, rather than a version of .NET that supports initialization syntax.

How to get row from R data.frame

10 years later ---> Using tidyverse we could achieve this simply and borrowing a leaf from Christopher Bottoms. For a better grasp, see slice().

library(tidyverse)
x <- structure(list(A = c(5,    3.5, 3.25, 4.25,  1.5 ), 
                    B = c(4.25, 4,   4,    4.5,   4.5 ),
                    C = c(4.5,  2.5, 4,    2.25,  3   )
),
.Names    = c("A", "B", "C"),
class     = "data.frame",
row.names = c(NA, -5L)
)

x
#>      A    B    C
#> 1 5.00 4.25 4.50
#> 2 3.50 4.00 2.50
#> 3 3.25 4.00 4.00
#> 4 4.25 4.50 2.25
#> 5 1.50 4.50 3.00

y<-c(A=5, B=4.25, C=4.5)
y
#>    A    B    C 
#> 5.00 4.25 4.50

#The slice() verb allows one to subset data row-wise. 
x <- x %>% slice(1) #(n) for the nth row, or (i:n) for range i to n, (i:n()) for i to last row...

x
#>   A    B   C
#> 1 5 4.25 4.5

#Test that the items in the row match the vector you wanted
x[1,]==y
#>      A    B    C
#> 1 TRUE TRUE TRUE

Created on 2020-08-06 by the reprex package (v0.3.0)

How is a JavaScript hash map implemented?

 
<html>
<head>
<script type="text/javascript">
function test(){
var map= {'m1': 12,'m2': 13,'m3': 14,'m4': 15}
     alert(map['m3']);
}
</script>
</head>
<body>
<input type="button" value="click" onclick="test()"/>
</body>
</html>

MySql Inner Join with WHERE clause

You are using two WHERE clauses but only one is allowed. Use it like this:

SELECT table1.f_id FROM table1
INNER JOIN table2 ON table2.f_id = table1.f_id
WHERE
  table1.f_com_id = '430'
  AND table1.f_status = 'Submitted'
  AND table2.f_type = 'InProcess'

Git - How to use .netrc file on Windows to save user and password

I am posting a way to use _netrc to download materials from the site www.course.com.

If someone is going to use the coursera-dl to download the open-class materials on www.coursera.com, and on the Windows OS someone wants to use a file like ".netrc" which is in like-Unix OS to add the option -n instead of -U <username> -P <password> for convenience. He/she can do it like this:

  1. Check the home path on Windows OS: setx HOME %USERPROFILE%(refer to VonC's answer). It will save the HOME environment variable as C:\Users\"username".

  2. Locate into the directory C:\Users\"username" and create a file name _netrc.NOTE: there is NOT any suffix. the content is like: machine coursera-dl login <user> password <pass>

  3. Use a command like coursera-dl -n --path PATH <course name> to download the class materials. More coursera-dl options details for this page.

CREATE FILE encountered operating system error 5(failed to retrieve text for this error. Reason: 15105)

I was able to solve the problem running MS SQL Management Studio as ADMINISTRATOR.

setup script exited with error: command 'x86_64-linux-gnu-gcc' failed with exit status 1

 
sudo apt-get install build-essential autoconf libtool pkg-config python-opengl python-imaging python-pyrex python-pyside.qtopengl idle-python2.7 qt4-dev-tools qt4-designer libqtgui4 libqtcore4 libqt4-xml libqt4-test libqt4-script libqt4-network libqt4-dbus python-qt4 python-qt4-gl libgle3 python-dev

sudo easy_install greenlet

sudo easy_install gevent

php implode (101) with quotes

Alternatively you can create such a function:

function implode_with_quotes(array $data)
{
    return sprintf("'%s'", implode("', '", $data));
}

com.google.android.gms:play-services-measurement-base is being requested by various other libraries

I had that same problem when I tried to add the firebase-database implementation, if I commented that line it works, so after a few tries I went to https://firebase.google.com/docs/android/setup

There I checked the versions of the available libraries and my firebase-core was at 16.0.1 (current version is 16.0.4) so I manually changed it and it worked just fine, build and sync were successful.

Convert array of strings into a string in Java

From Java 8, the simplest way I think is:

    String[] array = { "cat", "mouse" };
    String delimiter = "";
    String result = String.join(delimiter, array);

This way you can choose an arbitrary delimiter.

How do you return the column names of a table?

The following seems to be like the first suggested query above but sometime you have to specify the database to get it to work. Note that the query should also work without specifying the TABLE_SCHEMA:

SELECT COLUMN_NAME
FROM   YOUR_DB_NAME.INFORMATION_SCHEMA.COLUMNS
WHERE  TABLE_NAME = 'YOUR_TABLE_NAME' AND TABLE_SCHEMA = 'YOUR_DB_NAME'

If Browser is Internet Explorer: run an alternative script instead

For IE10+ standard conditions don't work cause of engine change or some another reasons, cause, you know, it's MSIE. But for IE10+ you need to run something like this in your scripts:

if (navigator.userAgent.match(/Trident\/7\./)) {
  // do stuff for IE.
}

Java, How to add library files in netbeans?

In Netbeans 8.2

1. Dowload the binaries from the web source. The Apache Commos are in: [http://commons.apache.org/components.html][1] In this case, you must select the "Logging" in the Components menu and follow the link to downloads in the Releases part. Direct URL: [http://commons.apache.org/proper/commons-logging/download_logging.cgi][2] For me, the correct download was the file: commons-logging-1.2-bin.zip from the Binaries.

2. Unzip downloaded content. Now, you can see several jar files inside the directory created from the zip file.

3. Add the library to the project. Right click in the project, select Properties and click in Libraries (in the left side). Click the button "Add Jar/Folder". Go to the previously unzipped contents and select the properly jar file. Clic in "Open" and click in"Ok". The library has been loaded!

How to convert data.frame column from Factor to numeric

As an alternative to $dollarsign notation, use a within block:

breast <- within(breast, {
  class <- as.numeric(as.character(class))
})

Note that you want to convert your vector to a character before converting it to a numeric. Simply calling as.numeric(class) will not the ids corresponding to each factor level (1, 2) rather than the levels themselves.

Histogram using gnuplot?

yes, and its quick and simple though very hidden:

binwidth=5
bin(x,width)=width*floor(x/width)

plot 'datafile' using (bin($1,binwidth)):(1.0) smooth freq with boxes

check out help smooth freq to see why the above makes a histogram

to deal with ranges just set the xrange variable.

How to list the size of each file and directory and sort by descending size in Bash?

[enhanced version]
This is going to be much faster and precise than the initial version below and will output the sum of all the file size of current directory:

echo `find . -type f -exec stat -c %s {} \; | tr '\n' '+' | sed 's/+$//g'` | bc

the stat -c %s command on a file will return its size in bytes. The tr command here is used to overcome xargs command limitations (apparently piping to xargs is splitting results on more lines, breaking the logic of my command). Hence tr is taking care of replacing line feed with + (plus) sign. sed has the only goal to remove the last + sign from the resulting string to avoid complains from the final bc (basic calculator) command that, as usual, does the math.

Performances: I tested it on several directories and over ~150.000 files top (the current number of files of my fedora 15 box) having what I believe it is an amazing result:

# time echo `find / -type f -exec stat -c %s {} \; | tr '\n' '+' | sed 's/+$//g'` | bc
12671767700

real    2m19.164s
user    0m2.039s
sys 0m14.850s

Just in case you want to make a comparison with the du -sb / command, it will output an estimated disk usage in bytes (-b option)

# du -sb /
12684646920 /

As I was expecting it is a little larger than my command calculation because the du utility returns allocated space of each file and not the actual consumed space.

[initial version]
You cannot use du command if you need to know the exact sum size of your folder because (as per man page citation) du estimates file space usage. Hence it will lead you to a wrong result, an approximation (maybe close to the sum size but most likely greater than the actual size you are looking for).

I think there might be different ways to answer your question but this is mine:

ls -l $(find . -type f | xargs) | cut -d" " -f5 | xargs | sed 's/\ /+/g'| bc

It finds all files under . directory (change . with whatever directory you like), also hidden files are included and (using xargs) outputs their names in a single line, then produces a detailed list using ls -l. This (sometimes) huge output is piped towards cut command and only the fifth field (-f5), which is the file size in bytes is taken and again piped against xargs which produces again a single line of sizes separated by blanks. Now take place a sed magic which replaces each blank space with a plus (+) sign and finally bc (basic calculator) does the math.

It might need additional tuning and you may have ls command complaining about arguments list too long.

Read Variable from Web.Config

If you want the basics, you can access the keys via:

string myKey = System.Configuration.ConfigurationManager.AppSettings["myKey"].ToString();
string imageFolder = System.Configuration.ConfigurationManager.AppSettings["imageFolder"].ToString();

To access my web config keys I always make a static class in my application. It means I can access them wherever I require and I'm not using the strings all over my application (if it changes in the web config I'd have to go through all the occurrences changing them). Here's a sample:

using System.Configuration;

public static class AppSettingsGet
{    
    public static string myKey
    {
        get { return ConfigurationManager.AppSettings["myKey"].ToString(); }
    }

    public static string imageFolder
    {
        get { return ConfigurationManager.AppSettings["imageFolder"].ToString(); }
    }

    // I also get my connection string from here
    public static string ConnectionString
    {
       get { return ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString; }
    }
}

How to delete projects in Intellij IDEA 14?

You will have to manually delete from the project explorer (your local machine hard drive), then delete the project in IntelliJ when it asks to re-open recent projects.

Get the first item from an iterable that matches a condition

Oneliner:

thefirst = [i for i in range(10) if i > 3][0]

If youre not sure that any element will be valid according to the criteria, you should enclose this with try/except since that [0] can raise an IndexError.

LINQ equivalent of foreach for IEnumerable<T>

MoreLinq has IEnumerable<T>.ForEach and a ton of other useful extensions. It's probably not worth taking the dependency just for ForEach, but there's a lot of useful stuff in there.

https://www.nuget.org/packages/morelinq/

https://github.com/morelinq/MoreLINQ

SSL Connection / Connection Reset with IISExpress

The issue that I had was related to @Jason Kleban's answer, but I had one small problem with my settings in the Visual Studio Properties for IIS Express.

Make sure that after you've changed the port to be in the range: 44300 to 44399, the address also starts with HTTPS

enter image description here

Android Studio Checkout Github Error "CreateProcess=2" (Windows)

If you have downloaded Github Desktop Client 1.0.9 then the path for git.exe will be

C:\Users\Username\AppData\Local\GitHubDesktop\app-1.0.9\resources\app\git\cmd\git.exe

Custom date format with jQuery validation plugin

nickf's answer is good, but note that the validation plug-in already includes validators for several other date formats, in the additional-methods.js file. Before you write your own, make sure that someone hasn't already done it.

Laravel orderBy on a relationship

Using sortBy... could help.

$users = User::all()->with('rated')->get()->sortByDesc('rated.rating');

How to create composite primary key in SQL Server 2008

Via Enterprise Manager (SSMS)...

  • Right Click on the Table you wish to create the composite key on and select Design.
  • Highlight the columns you wish to form as a composite key
  • Right Click over those columns and Set Primary Key

To see the SQL you can then right click on the Table > Script Table As > Create To

Mongoose query where value is not null

I ended up here and my issue was that I was querying for 

{$not: {email: /@domain.com/}}

instead of 

{email: {$not: /@domain.com/}}

$(this).val() not working to get text from span using jquery

I think you want .text():

var monthname = $(this).text();

Re-assign host access permission to MySQL user

I haven't had to do this, so take this with a grain of salt and a big helping of "test, test, test".

What happens if (in a safe controlled test environment) you directly modify the Host column in the mysql.user and probably mysql.db tables? (E.g., with an update statement.) I don't think MySQL uses the user's host as part of the password encoding (the PASSWORD function doesn't suggest it does), but you'll have to try it to be sure. You may need to issue a FLUSH PRIVILEGES command (or stop and restart the server).

For some storage engines (MyISAM, for instance), you may also need to check/modify the .frm file any views that user has created. The .frm file stores the definer, including the definer's host. (I have had to do this, when moving databases between hosts where there had been a misconfiguration causing the wrong host to be recorded...)

Javascript - How to extract filename from a file input control

 
// HTML
<input type="file" onchange="getFileName(this)">

// JS
function getFileName(input) {
    console.log(input.files[0].name) // With extension
    console.log(input.files[0].name.replace(/\.[^/.]+$/, '')) // Without extension
}

How to remove the extension

Copying text outside of Vim with set mouse=a enabled

Compilation settings that vim was compiled with, are part of the issue. vim --version shows these.

In OSX, the default vim has -clipboard But you need +clipboard

On osx you can and apparently generally should, use macvim. You can do brew cask install macvim That one has +clipboard.

Them you'll have two vims.

~$ ls -l /usr/bin/vim   <--- default vim
-rwxr-xr-x  1 root  wheel  1745984 15 Jul  2017 /usr/bin/vim

~$ ls -l /usr/local/bin/vim   <-- macvim, installed recently via that mentioned brew line. 
lrwxr-xr-x  1 apple  admin  42 16 May 23:32 /usr/local/bin/vim -> /Applications/MacVim.app/Contents/bin/mvim
~$

running vim will run macvim 'cos /usr/local/bin should be before /usr/bin in the path, though you can check with which vim.

running vim(to run macvim), is fine but you may want to map vi to macvim 'cos otherwise running vi stays at the default vim! You can rewrite or delete(with rm) and recreate the vi sym link, with ln. And to do that without an 'operation not permitted" error, you have to (temporarily) disable SIL. https://apple.stackexchange.com/questions/208478/how-do-i-disable-system-integrity-protection-sip-aka-rootless-on-macos-os-x .

macvim has +clipboard as shown by vim --version

Here is a working ~/.vim/vimrc with just the required lines.

:set mouse=a
:map <leader>c "+y
:map <leader>v "+p

The default leader key is backslash.

I read a suggestion that one should use the leader key.. (certainly control has many keys already in use, so the suggestion was to not use control. I don't know if that applies to command key too, but anyhow).

With that mentioned mapping, \c will do "+y which will copy from the register known as +, to the clipboard. And \v will paste from the register known as +.

So that's a copy/paste that works between windows.

Another OS may require "* rather than "+

Make install, but not to default directories?

It depends on the package. If the Makefile is generated by GNU autotools (./configure) you can usually set the target location like so:

./configure --prefix=/somewhere/else/than/usr/local

If the Makefile is not generated by autotools, but distributed along with the software, simply open it up in an editor and change it. The install target directory is probably defined in a variable somewhere.

AltGr key not working, instead I have to use Ctrl+AltGr

I found a solution for my problem while writing my question !

Going into my remote session i tried two key combinations, and it solved the problem on my Desktop : Alt+Enter and Ctrl+Enter (i don't know which one solved the problem though)

I tried to reproduce the problem, but i couldn't... but i'm almost sure it's one of the key combinations described in the question above (since i experienced this problem several times)

So it seems the problem comes from the use of RDP (windows7 and 8)

Update 2017: Problem occurs on Windows 10 aswell.

How to get year, month, day, hours, minutes, seconds and milliseconds of the current moment in Java?

Look at the API documentation for the java.util.Calendar class and its derivatives (you may be specifically interested in the GregorianCalendar class).

Display a angular variable in my html page

In your template, you have access to all the variables that are members of the current $scope. So, tobedone should be $scope.tobedone, and then you can display it with {{tobedone}}, or [[tobedone]] in your case.

Python mysqldb: Library not loaded: libmysqlclient.18.dylib

In my case, I was getting the error with Mac OS X 10.9 Mavericks. I installed MySQL Community Server directly from the Oracle/MySQL Website from DMG.

All I needed to do was symlink the lib files to the /usr/local/lib directory. 

mkdir -p /usr/local/lib   
ln -s /usr/local/mysql/lib/libmysql* /usr/local/lib

Bonus: If you're running Mac OS X as well, there is a great tool to finding files like the libmysqlclient.18.dylib file, http://apps.tempel.org/FindAnyFile. This is how I originally found the location of the dylib file.

RegEx for valid international mobile phone number

Even if you write a regular expression that matches exactly the subset "valid phone numbers" out of strings, there is no way to guarantee (by way of a regular expression) that they are valid mobile phone numbers. In several countries, mobile phone numbers are indistinguishable from landline phone numbers without at least a number plan lookup, and in some cases, even that won't help. For example, in Sweden, lots of people have "ported" their regular, landline-like phone number to their mobile phone. It's still the same number as they had before, but now it goes to a mobile phone instead of a landline.

Since valid phone numbers consist only of digits, I doubt that rolling your own would risk missing some obscure case of phone number at least. If you want to have better certainty, write a generator that takes a list of all valid country codes, and requires one of them at the beginning of the phone number to be matched by the generated regular expression.

The simplest possible JavaScript countdown timer?

If you want a real timer you need to use the date object.

Calculate the difference.

Format your string.

window.onload=function(){
      var start=Date.now(),r=document.getElementById('r');
      (function f(){
      var diff=Date.now()-start,ns=(((3e5-diff)/1e3)>>0),m=(ns/60)>>0,s=ns-m*60;
      r.textContent="Registration closes in "+m+':'+((''+s).length>1?'':'0')+s;
      if(diff>3e5){
         start=Date.now()
      }
      setTimeout(f,1e3);
      })();
}

Example

Jsfiddle

not so precise timer

var time=5*60,r=document.getElementById('r'),tmp=time;

setInterval(function(){
    var c=tmp--,m=(c/60)>>0,s=(c-m*60)+'';
    r.textContent='Registration closes in '+m+':'+(s.length>1?'':'0')+s
    tmp!=0||(tmp=time);
},1000);

JsFiddle

Get loop counter/index using for…of syntax in JavaScript

Answer Given by rushUp Is correct but this will be more convenient 

for (let [index, val] of array.entries() || []) {
   // your code goes here    
}

jQuery Form Validation before Ajax submit

I think submitHandler with jquery validation is good solution. Please get idea from this code. Inspired from @Darin Dimitrov

$('.calculate').validate({

                submitHandler: function(form) {
                    $.ajax({
                        url: 'response.php',
                        type: 'POST',
                        data: $(form).serialize(),
                        success: function(response) {
                            $('#'+form.id+' .ht-response-data').html(response);
                        }            
                    });
                }
            });

CSS for grabbing cursors (drag & drop)

The closed hand cursor is not 16x16. If you would need them in the same dimensions, here you have both of them in 16x16 px

opened hand closed hand

Or if you need original cursors:

https://www.google.com/intl/en_ALL/mapfiles/openhand.cur https://www.google.com/intl/en_ALL/mapfiles/closedhand.cur

Check if a given key already exists in a dictionary

Check if a given key already exists in a dictionary

To get the idea how to do that we first inspect what methods we can call on dictionary. Here are the methods: 

d={'clear':0, 'copy':1, 'fromkeys':2, 'get':3, 'items':4, 'keys':5, 'pop':6, 'popitem':7, 'setdefault':8, 'update':9, 'values':10}

Python Dictionary clear()       Removes all Items
Python Dictionary copy()        Returns Shallow Copy of a Dictionary
Python Dictionary fromkeys()    Creates dictionary from given sequence
Python Dictionary get()         Returns Value of The Key
Python Dictionary items()       Returns view of dictionary (key, value) pair
Python Dictionary keys()        Returns View Object of All Keys
Python Dictionary pop()         Removes and returns element having given key
Python Dictionary popitem()     Returns & Removes Element From Dictionary
Python Dictionary setdefault()  Inserts Key With a Value if Key is not Present
Python Dictionary update()      Updates the Dictionary 
Python Dictionary values()      Returns view of all values in dictionary

The brutal method to check if the key already exists may be the get() method:

d.get("key")

The other two interesting methods items() and keys() sounds like too much of work. So let's examine if get() is the right method for us. We have our dict d:

d= {'clear':0, 'copy':1, 'fromkeys':2, 'get':3, 'items':4, 'keys':5, 'pop':6, 'popitem':7, 'setdefault':8, 'update':9, 'values':10}

Printing shows the key we don't have will return None:

print(d.get('key')) #None
print(d.get('clear')) #0
print(d.get('copy')) #1

We may use that to get the info if the key is present or no. But consider this if we create a dict with a single key:None:

d= {'key':None}
print(d.get('key')) #None
print(d.get('key2')) #None

Leading that get() method is not reliable in case some values may be None. This story should have a happier ending. If we use the in comparator:

print('key' in d) #True
print('key2' in d) #False

We get the correct results. We may examine the Python byte code:

import dis
dis.dis("'key' in d")
#   1           0 LOAD_CONST               0 ('key')
#               2 LOAD_NAME                0 (d)
#               4 COMPARE_OP               6 (in)
#               6 RETURN_VALUE

dis.dis("d.get('key2')")
#   1           0 LOAD_NAME                0 (d)
#               2 LOAD_METHOD              1 (get)
#               4 LOAD_CONST               0 ('key2')
#               6 CALL_METHOD              1
#               8 RETURN_VALUE

This shows that in compare operator is not just more reliable but even faster than get().

Disable Pinch Zoom on Mobile Web

Try with min-width property. Let me explain you. Assume a device with screen width of 400px (for an instance). When you zoom in, the fonts gets larger and larger. But boxes and divs remains with same width. If you use min-width, you can avoid decreasing your div and box.

Templated check for the existence of a class member function?

MSVC has the __if_exists and __if_not_exists keywords (Doc). Together with the typeof-SFINAE approach of Nicola I could create a check for GCC and MSVC like the OP looked for.

Update: Source can be found Here

Anonymous method in Invoke call

I never understood why this makes a difference for the compiler, but this is sufficient.

public static class ControlExtensions
{
    public static void Invoke(this Control control, Action action)
    {
        control.Invoke(action);
    }
}

Bonus: add some error handling, because it is likely that, if you are using Control.Invoke from a background thread you are updating the text / progress / enabled state of a control and don't care if the control is already disposed.

public static class ControlExtensions
{
    public static void Invoke(this Control control, Action action)
    {
        try
        {
            if (!control.IsDisposed) control.Invoke(action);
        }
        catch (ObjectDisposedException) { }
    }
}

C++ - Assigning null to a std::string

compiler gives error because when assigning mValue=0 compiler find assignment operator=(int ) for compile time binding but it's not present in the string class. if we type cast following statement to char like mValue=(char)0 then its compile successfully because string class contain operator=(char) method.

Swift's guard keyword

When a condition is met using guard it exposes variables declared within the guard block to the rest of the code-block, bringing them into its scope. Which, as previously stated, will certainly come in handy with nested if let statements.

Note that guard requires a return or a throw in its else statement.

Parsing JSON with Guard

Below is an example of how one might parse a JSON object using guard rather than if-let. This is an excerpt from a blog entry that includes a playground file which you can find here:

How to use Guard in Swift 2 to parse JSON

func parseJSONWithGuard(data : [String : AnyObject]) throws -> Developer {

    guard let firstname = data["First"] as? String  else {
        return Developer() // we could return a nil Developer()
    }

    guard let lastname = data["Last"] as? String else {
        throw ParseError.BadName // or we could throw a custom exception and handle the error
    }

    guard let website = data["WebSite"] as? String else {
        throw ParseError.BadName
    }

    guard let iosDev = data["iosDeveloper"] as? Bool else {
        throw ParseError.BadName
    }



    return Developer(first: firstname, last: lastname, site: website, ios: iosDev)

}

download playground: guard playground

More info:

Here's an excerpt from the The Swift Programming Language Guide:

If the guard statement’s condition is met, code execution continues after the guard statement’s closing brace. Any variables or constants that were assigned values using an optional binding as part of the condition are available for the rest of the code block that the guard statement appears in.

If that condition is not met, the code inside the else branch is executed. That branch must transfer control to exit the code block that that guard statement appears in. It can do this with a control transfer statement such as return, break, or continue, or it can call a function or method that doesn’t return, such as fatalError().

Marquee text in Android

For setting Marquee programatically

TextView textView = (TextView) this.findViewById(R.id.textview_marquee);  
textView.setEllipsize(TruncateAt.MARQUEE);
textView.setMarqueeRepeatLimit(-1);
textView.setText("General Information... general information... General Information");
textView.setSelected(true);
textView.setSingleLine(true);

How To Get Selected Value From UIPickerView

You will need to ask the picker's delegate, in the same way your application does. Here is how I do it from within my UIPickerViewDelegate:

func selectedRowValue(picker : UIPickerView, ic : Int) -> String {

    //Row Index
    let ir  = picker.selectedRow(inComponent: ic);

    //Value
    let val = self.pickerView(picker,
                              titleForRow:  ir,
                              forComponent: ic);
    return val!;
}

What is C# equivalent of <map> in C++?

The equivalent would be class SortedDictionary<TKey, TValue> in the System.Collections.Generic namespace.

If you don't care about the order the class Dictionary<TKey, TValue> in the System.Collections.Generic namespace would probably be sufficient.

Running bash script from within python

If sleep.sh has the shebang #!/bin/sh and it has appropriate file permissions -- run chmod u+rx sleep.sh to make sure and it is in $PATH then your code should work as is:

import subprocess

rc = subprocess.call("sleep.sh")

If the script is not in the PATH then specify the full path to it e.g., if it is in the current working directory:

from subprocess import call

rc = call("./sleep.sh")

If the script has no shebang then you need to specify shell=True:

rc = call("./sleep.sh", shell=True)

If the script has no executable permissions and you can't change it e.g., by running os.chmod('sleep.sh', 0o755) then you could read the script as a text file and pass the string to subprocess module instead:

with open('sleep.sh', 'rb') as file:
    script = file.read()
rc = call(script, shell=True)

System.Data.OracleClient requires Oracle client software version 8.1.7

Update 1: It is possible for different users to have different path. But its not the likely problem here. There is more chance that the user that the iwam user doesn't have permission to the oracle client directory.

Update 0: Its suppose to work. Check for environment variable ( That are needed to find the oracle client and tnsnames.ora ). Also, Maybe you have a 32/64 bit issues. Also, consider using the Oracle Data Provider for .NET ( search for odp.net)

Function to return only alpha-numeric characters from string?

Warning: Note that English is not restricted to just A-Z.

Try this to remove everything except a-z, A-Z and 0-9:

$result = preg_replace("/[^a-zA-Z0-9]+/", "", $s);

If your definition of alphanumeric includes letters in foreign languages and obsolete scripts then you will need to use the Unicode character classes.

Try this to leave only A-Z:

$result = preg_replace("/[^A-Z]+/", "", $s);

The reason for the warning is that words like résumé contains the letter é that won't be matched by this. If you want to match a specific list of letters adjust the regular expression to include those letters. If you want to match all letters, use the appropriate character classes as mentioned in the comments.

How to install pip with Python 3?

Single Python in system

To install packages in Python always follow these steps:

  1. If the package is for python 2.x: sudo python -m pip install [package]
  2. If the package is for python 3.x: sudo python3 -m pip install [package]

Note: This is assuming no alias is set for python

Through this method, there will be no confusion regarding which python version is receiving the package.

Multiple Pythons

Say you have python3 ? python3.6 and python3.7 ? python3.7

  1. To install for python3.6: sudo python3 -m pip install [package]
  2. To instal for python3.7: sudo python3.7 -m pip install [package]

This is essentially the same method as shown previously.

Note 1

How to find which python, your python3 command spawns:

ganesh@Ganesh:~$ python3 # Type in terminal
Python 3.6.6 (default, Sep 12 2018, 18:26:19) # Your python3 version
[GCC 8.0.1 20180414 (experimental) [trunk revision 259383]] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

Notice python 3.6.6 in the second line.

Note 2

Change what python3 or python points to: https://askubuntu.com/questions/320996/how-to-make-python-program-command-execute-python-3

What are the differences between struct and class in C++?

The only other difference is the default inheritance of classes and structs, which, unsurprisingly, is private and public respectively.

Best design for a changelog / auditing database table?

In the project I'm working on, audit log also started from the very minimalistic design, like the one you described:

event ID
event date/time
event type
user ID
description

The idea was the same: to keep things simple.

However, it quickly became obvious that this minimalistic design was not sufficient. The typical audit was boiling down to questions like this: 

Who the heck created/updated/deleted a record 
with ID=X in the table Foo and when?

So, in order to be able to answer such questions quickly (using SQL), we ended up having two additional columns in the audit table

object type (or table name)
object ID

That's when design of our audit log really stabilized (for a few years now).

Of course, the last "improvement" would work only for tables that had surrogate keys. But guess what? All our tables that are worth auditing do have such a key!

How to get the full path of the file from a file input

You cannot do so - the browser will not allow this because of security concerns. Although there are workarounds, the fact is that you shouldn't count on this working. The following Stack Overflow questions are relevant here:

In addition to these, the new HTML5 specification states that browsers will need to feed a Windows compatible fakepath into the input type="file" field, ostensibly for backward compatibility reasons.

So trying to obtain the path is worse then useless in newer browsers - you'll actually get a fake one instead.

CSS3 selector to find the 2nd div of the same class

Is there a reason that you can't do this via Javascript? My advice would be to target the selectors with a universal rule (.foo) and then parse back over to get the last foo with Javascript and set any additional styling you'll need.

Or as suggested by Stein, just add two classes if you can:

<div class="foo"></div>
<div class="foo last"></div>

.foo {}
.foo.last {}

Adding new line of data to TextBox

Following are the ways

  1. From the code (the way you have mentioned) ->

    displayBox.Text += sent + "\r\n";

    or

    displayBox.Text += sent + Environment.NewLine;

  2. From the UI
    a) WPF

    Set TextWrapping="Wrap" and AcceptsReturn="True"

    Press Enter key to the textbox and new line will be created

    b) Winform text box 

    Set TextBox.MultiLine and TextBox.AcceptsReturn to true

Scroll to element on click in Angular 4

In Angular 7 works perfect

HTML

<button (click)="scroll(target)">Click to scroll</button>
<div #target>Your target</div>

In component

scroll(el: HTMLElement) {
    el.scrollIntoView({behavior: 'smooth'});
}

How to get user agent in PHP

You could also use the php native funcion get_browser()

IMPORTANT NOTE: You should have a browscap.ini file.

How do I get logs/details of ansible-playbook module executions?

Ansible command-line help, such as ansible-playbook --help shows how to increase output verbosity by setting the verbose mode (-v) to more verbosity (-vvv) or to connection debugging verbosity (-vvvv). This should give you some of the details you're after in stdout, which you can then be logged.

Truncate Decimal number not Round Off

You can use Math.Round:

decimal rounded = Math.Round(2.22939393, 3); //Returns 2.229

Or you can use ToString with the N3 numeric format.

string roundedNumber = number.ToString("N3");

EDIT: Since you don't want rounding, you can easily use Math.Truncate:

Math.Truncate(2.22977777 * 1000) / 1000; //Returns 2.229

Change keystore password from no password to a non blank password

Add -storepass to keytool arguments.

keytool -storepasswd -storepass '' -keystore mykeystore.jks

But also notice that -list command does not always require a password. I could execute follow command in both cases: without password or with valid password 

$JAVA_HOME/bin/keytool -list -keystore $JAVA_HOME/jre/lib/security/cacerts

How do I resolve a path relative to an ASP.NET MVC 4 application root?

Just use the following

Server.MapPath("~/Data/data.html")

How can I convert NSDictionary to NSData and vice versa?

Please try this one

NSError *error;
NSDictionary *responseJson = [NSJSONSerialization JSONObjectWithData:webData
                                options:NSJSONReadingMutableContainers
                                error:&error];

How to find the highest value of a column in a data frame in R?

Similar to colMeans, colSums, etc, you could write a column maximum function, colMax, and a column sort function, colSort. 

colMax <- function(data) sapply(data, max, na.rm = TRUE)
colSort <- function(data, ...) sapply(data, sort, ...)

I use ... in the second function in hopes of sparking your intrigue.

Get your data:

dat <- read.table(h=T, text = "Ozone Solar.R Wind Temp Month Day
1     41     190  7.4   67     5   1
2     36     118  8.0   72     5   2
3     12     149 12.6   74     5   3
4     18     313 11.5   62     5   4
5     NA      NA 14.3   56     5   5
6     28      NA 14.9   66     5   6
7     23     299  8.6   65     5   7
8     19      99 13.8   59     5   8
9      8      19 20.1   61     5   9")

Use colMax function on sample data:

colMax(dat)
#  Ozone Solar.R    Wind    Temp   Month     Day 
#   41.0   313.0    20.1    74.0     5.0     9.0

To do the sorting on a single column, 

sort(dat$Solar.R, decreasing = TRUE)
# [1] 313 299 190 149 118  99  19

and over all columns use our colSort function, 

colSort(dat, decreasing = TRUE) ## compare with '...' above

Selecting a row of pandas series/dataframe by integer index

I would normally go for .loc/.iloc as suggested by Ted, but one may also select a row by tranposing the DataFrame. To stay in the example above, df.T[2] gives you row 2 of df.

Open button in new window?

 
<input type="button" onclick="window.open(); return false;" value="click me" />

http://www.javascript-coder.com/window-popup/javascript-window-open.phtml

Changing button color programmatically

Here is an example using HTML:

<input type="button" value="click me" onclick="this.style.color='#000000';
this.style.backgroundColor = '#ffffff'" />

And here is an example using JavaScript:

document.getElementById("button").bgcolor="#Insert Color Here";

eclipse stuck when building workspace

Restart eclipse.
It worked for me several times.

Java Map equivalent in C#

Dictionary<,> is the equivalent. While it doesn't have a Get(...) method, it does have an indexed property called Item which you can access in C# directly using index notation:

class Test {
  Dictionary<int,String> entities;

  public String getEntity(int code) {
    return this.entities[code];
  }
}

If you want to use a custom key type then you should consider implementing IEquatable<> and overriding Equals(object) and GetHashCode() unless the default (reference or struct) equality is sufficient for determining equality of keys. You should also make your key type immutable to prevent weird things happening if a key is mutated after it has been inserted into a dictionary (e.g. because the mutation caused its hash code to change).

Where is Java Installed on Mac OS X?

If you type

java -verbose

This also gives the location from which the jars are loaded and hence also the java path.

How do I center list items inside a UL element?

Looks like all you need is text-align: center; in ul

Twitter Bootstrap dropdown menu

It actually requires inclusion of Twitter Bootstrap's dropdown.js

http://getbootstrap.com/2.3.2/components.html

How to get files in a relative path in C#

Write it like this:

string[] files = Directory.GetFiles(@".\Archive", "*.zip");

. is for relative to the folder where you started your exe, and @ to allow \ in the name.

When using filters, you pass it as a second parameter. You can also add a third parameter to specify if you want to search recursively for the pattern.

In order to get the folder where your .exe actually resides, use:

var executingPath = Path.GetDirectoryName(Assembly.GetEntryAssembly().Location);

What are the differences between git remote prune, git prune, git fetch --prune, etc

Note that one difference between git remote --prune and git fetch --prune is being fixed, with commit 10a6cc8, by Tom Miller (tmiller) (for git 1.9/2.0, Q1 2014):

When we have a remote-tracking branch named "frotz/nitfol" from a previous fetch, and the upstream now has a branch named "**frotz"**, fetch would fail to remove "frotz/nitfol" with a "git fetch --prune" from the upstream.
git would inform the user to use "git remote prune" to fix the problem.

So: when a upstream repo has a branch ("frotz") with the same name as a branch hierarchy ("frotz/xxx", a possible branch naming convention), git remote --prune was succeeding (in cleaning up the remote tracking branch from your repo), but git fetch --prune was failing.

Not anymore:

Change the way "fetch --prune" works by moving the pruning operation before the fetching operation.
This way, instead of warning the user of a conflict, it automatically fixes it.

Simple Deadlock Examples

Here is my detailed example for deadlock, after spending lots of time. Hope it helps :)

package deadlock;

public class DeadlockApp {

    String s1 = "hello";
    String s2 = "world";

    Thread th1 = new Thread() {
        public void run() {
            System.out.println("Thread th1 has started");
            synchronized (s1) { //A lock is created internally (holds access of s1), lock will be released or unlocked for s1, only when it exits the block Line #23
                System.out.println("Executing first synchronized block of th1!");
                try {
                    Thread.sleep(1000);
                } catch(InterruptedException ex) {
                    System.out.println("Exception is caught in th1");
                }
                System.out.println("Waiting for the lock to be released from parrallel thread th1");
                synchronized (s2) { //As another has runned parallely Line #32, lock has been created for s2
                    System.out.println(s1 + s2);
                }

            }
            System.out.println("Thread th1 has executed");
        }
    };


    Thread th2 = new Thread() {
        public void run() {
            System.out.println("Thread th2 has started");
            synchronized (s2) { //A lock is created internally (holds access of s2), lock will be released or unlocked for s2, only when it exits the block Line #44
                System.out.println("Executing first synchronized block of th2!");
                try {
                    Thread.sleep(1000);
                } catch(InterruptedException ex) {
                    System.out.println("Exception is caught in th2");
                }
                System.out.println("Waiting for the lock to be released from parrallel thread th2");
                synchronized (s1) { //As another has runned parallely Line #11, lock has been created for s1
                    System.out.println(s1 + s2);
                }

            }
            System.out.println("Thread th2 has executed");
        }
    };

    public static void main(String[] args) {
        DeadlockApp deadLock = new DeadlockApp();
        deadLock.th1.start();
        deadLock.th2.start();
        //Line #51 and #52 runs parallely on executing the program, a lock is created inside synchronized method
        //A lock is nothing but, something like a blocker or wall, which holds access of the variable from being used by others.
        //Locked object is accessible, only when it is unlocked (i.e exiting  the synchronized block)
        //Lock cannot be created for primitive types (ex: int, float, double)
        //Dont forget to add thread.sleep(time) because if not added, then object access will not be at same time for both threads to create Deadlock (not actual runtime with lots of threads) 
        //This is a simple program, so we added sleep90 to create Deadlock, it will execute successfully, if it is removed. 
    }

    //Happy coding -- Parthasarathy S
}

Mapping many-to-many association table with extra column(s)

I search a way to map a many-to-many association table with extra column(s) with hibernate in xml files configuration.

Assuming with have two table 'a' & 'c' with a many to many association with a column named 'extra'. Cause I didn't find any complete example, here is my code. Hope it will help :).

First here is the Java objects.

public class A implements Serializable{  

    protected int id;
    // put some others fields if needed ...   
    private Set<AC> ac = new HashSet<AC>();

    public A(int id) {
        this.id = id;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public Set<AC> getAC() {
        return ac;
    }

    public void setAC(Set<AC> ac) {
        this.ac = ac;
    }

    /** {@inheritDoc} */
    @Override
    public int hashCode() {
        final int prime = 97;
        int result = 1;
        result = prime * result + id;
        return result;
    }

    /** {@inheritDoc} */
    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (!(obj instanceof A))
            return false;
        final A other = (A) obj;
        if (id != other.getId())
            return false;
        return true;
    }

}

public class C implements Serializable{

    protected int id;
    // put some others fields if needed ...    

    public C(int id) {
        this.id = id;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    /** {@inheritDoc} */
    @Override
    public int hashCode() {
        final int prime = 98;
        int result = 1;
        result = prime * result + id;
        return result;
    }

    /** {@inheritDoc} */
    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (!(obj instanceof C))
            return false;
        final C other = (C) obj;
        if (id != other.getId())
            return false;
        return true;
    }

}

Now, we have to create the association table. The first step is to create an object representing a complex primary key (a.id, c.id).

public class ACId implements Serializable{

    private A a;
    private C c;

    public ACId() {
        super();
    }

    public A getA() {
        return a;
    }
    public void setA(A a) {
        this.a = a;
    }
    public C getC() {
        return c;
    }
    public void setC(C c) {
        this.c = c;
    }
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((a == null) ? 0 : a.hashCode());
        result = prime * result
                + ((c == null) ? 0 : c.hashCode());
        return result;
    }
    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        ACId other = (ACId) obj;
        if (a == null) {
            if (other.a != null)
                return false;
        } else if (!a.equals(other.a))
            return false;
        if (c == null) {
            if (other.c != null)
                return false;
        } else if (!c.equals(other.c))
            return false;
        return true;
    }
}

Now let's create the association object itself.

public class AC implements java.io.Serializable{

    private ACId id = new ACId();
    private String extra;

    public AC(){

    }

    public ACId getId() {
        return id;
    }

    public void setId(ACId id) {
        this.id = id;
    }

    public A getA(){
        return getId().getA();
    }

    public C getC(){
        return getId().getC();
    }

    public void setC(C C){
        getId().setC(C);
    }

    public void setA(A A){
        getId().setA(A);
    }

    public String getExtra() {
        return extra;
    }

    public void setExtra(String extra) {
        this.extra = extra;
    }

    public boolean equals(Object o) {
        if (this == o)
            return true;
        if (o == null || getClass() != o.getClass())
            return false;

        AC that = (AC) o;

        if (getId() != null ? !getId().equals(that.getId())
                : that.getId() != null)
            return false;

        return true;
    }

    public int hashCode() {
        return (getId() != null ? getId().hashCode() : 0);
    }
}

At this point, it's time to map all our classes with hibernate xml configuration.

A.hbm.xml and C.hxml.xml (quiete the same).

<class name="A" table="a">
        <id name="id" column="id_a" unsaved-value="0">
            <generator class="identity">
                <param name="sequence">a_id_seq</param>
            </generator>
        </id>
<!-- here you should map all others table columns -->
<!-- <property name="otherprop" column="otherprop" type="string" access="field" /> -->
    <set name="ac" table="a_c" lazy="true" access="field" fetch="select" cascade="all">
        <key>
            <column name="id_a" not-null="true" />
        </key>
        <one-to-many class="AC" />
    </set>
</class>

<class name="C" table="c">
        <id name="id" column="id_c" unsaved-value="0">
            <generator class="identity">
                <param name="sequence">c_id_seq</param>
            </generator>
        </id>
</class>

And then association mapping file, a_c.hbm.xml.

<class name="AC" table="a_c">
    <composite-id name="id" class="ACId">
        <key-many-to-one name="a" class="A" column="id_a" />
        <key-many-to-one name="c" class="C" column="id_c" />
    </composite-id>
    <property name="extra" type="string" column="extra" />
</class>

Here is the code sample to test.

A = ADao.get(1);
C = CDao.get(1);

if(A != null && C != null){
    boolean exists = false;
            // just check if it's updated or not
    for(AC a : a.getAC()){
        if(a.getC().equals(c)){
            // update field
            a.setExtra("extra updated");
            exists = true;
            break;
        }
    }

    // add 
    if(!exists){
        ACId idAC = new ACId();
        idAC.setA(a);
        idAC.setC(c);

        AC AC = new AC();
        AC.setId(idAC);
        AC.setExtra("extra added"); 
        a.getAC().add(AC);
    }

    ADao.save(A);
}

Is there any difference between DECIMAL and NUMERIC in SQL Server?

They are exactly the same. When you use it be consistent. Use one of them in your database

What does the Java assert keyword do, and when should it be used?

To recap (and this is true of many languages not just Java):

"assert" is primarily used as a debugging aid by software developers during the debugging process. Assert-messages should never appear. Many languages provide a compile-time option that will cause all "asserts" to be ignored, for use in generating "production" code.

"exceptions" are a handy way to handle all kinds of error conditions, whether or not they represent logic errors, because, if you run into an error-condition such that you cannot continue, you can simply "throw them up into the air," from wherever you are, expecting someone else out there to be ready to "catch" them. Control is transferred in one step, straight from the code that threw the exception, straight to the catcher's mitt. (And the catcher can see the complete backtrace of calls that had taken place.)

Furthermore, callers of that subroutine don't have to check to see if the subroutine succeeded: "if we're here now, it must have succeeded, because otherwise it would have thrown an exception and we wouldn't be here now!" This simple strategy makes code-design and debugging much, much easier.

Exceptions conveniently allow fatal-error conditions to be what they are: "exceptions to the rule." And, for them to be handled by a code-path that is also "an exception to the rule ... "fly ball!"

How to provide animation when calling another activity in Android?

Jelly Bean adds support for this with the ActivityOptions.makeCustomAnimation() method. Of course, since it's only on Jelly Bean, it's pretty much worthless for practical purposes.

printf %f with only 2 numbers after the decimal point?

You can use something like this:

printf("%.2f", number);

If you need to use the string for something other than printing out, use the NumberFormat class:

NumberFormat formatter = new DecimalFormatter("#.##");
String s = formatter.format(3.14159265); // Creates a string containing "3.14"

Replace words in the body text

I was trying to replace a really large string and for some reason regular expressions were throwing some errors/exceptions.

So I found this alternative to regular expressions which also runs pretty fast. At least it was fast enough for me: 

var search = "search string";
var replacement = "replacement string";

document.body.innerHTML = document.body.innerHTML.split(search).join(replacement)

src: How to replace all occurrences of a string in JavaScript?

Escape sequence \f - form feed - what exactly is it?

Although recently its use is undefined, a common and useful use for the form feed is to separate sections of code vertically, like so: enter image description here (from http://ergoemacs.org/emacs/emacs_form_feed_section_paging.html)

How to write to the Output window in Visual Studio?

 
#define WIN32_LEAN_AND_MEAN
#include <Windows.h>

wstring outputMe = L"can" + L" concatenate\n";
OutputDebugString(outputMe.c_str());

How can I list all the deleted files in a Git repository?

Citing this Stack Overflow answer.

It is a pretty neat way to get type-of-change (A:Added, M:Modified, D:Deleted) for each file that got changed.

git diff --name-status

Data binding for TextBox

I Recommend you implement INotifyPropertyChanged and change your databinding code to this:

this.textBox.DataBindings.Add("Text",
                                this.Food,
                                "Name",
                                false,
                                DataSourceUpdateMode.OnPropertyChanged);

That'll fix it.

Note that the default DataSourceUpdateMode is OnValidation, so if you don't specify OnPropertyChanged, the model object won't be updated until after your validations have occurred.

Struct like objects in Java

Use common sense really. If you have something like:

public class ScreenCoord2D{
    public int x;
    public int y;
}

Then there's little point in wrapping them up in getters and setters. You're never going to store an x, y coordinate in whole pixels any other way. Getters and setters will only slow you down.

On the other hand, with:

public class BankAccount{
    public int balance;
}

You might want to change the way a balance is calculated at some point in the future. This should really use getters and setters.

It's always preferable to know why you're applying good practice, so that you know when it's ok to bend the rules.

What's an Aggregate Root?

From Evans DDD:

An AGGREGATE is a cluster of associated objects that we treat as a unit for the purpose of data changes. Each AGGREGATE has a root and a boundary. The boundary defines what is inside the AGGREGATE. The root is a single, specific ENTITY contained in the AGGREGATE.

And:

The root is the only member of the AGGREGATE that outside objects are allowed to hold references to[.]

This means that aggregate roots are the only objects that can be loaded from a repository.

An example is a model containing a Customer entity and an Address entity. We would never access an Address entity directly from the model as it does not make sense without the context of an associated Customer. So we could say that Customer and Address together form an aggregate and that Customer is an aggregate root.

Default Activity not found in Android Studio

I figured it out. I mistakenly added final keyword in activity declaration. Once I removed it everything works!

public  class SplashActivity extends AppCompatActivity {
...
}

How do I find the time difference between two datetime objects in python?

I use somethign like this :

from datetime import datetime

def check_time_difference(t1: datetime, t2: datetime):
    t1_date = datetime(
        t1.year,
        t1.month,
        t1.day,
        t1.hour,
        t1.minute,
        t1.second)

    t2_date = datetime(
        t2.year,
        t2.month,
        t2.day,
        t2.hour,
        t2.minute,
        t2.second)

    t_elapsed = t1_date - t2_date

    return t_elapsed

# usage 
f = "%Y-%m-%d %H:%M:%S+01:00"
t1 = datetime.strptime("2018-03-07 22:56:57+01:00", f)
t2 = datetime.strptime("2018-03-07 22:48:05+01:00", f)
elapsed_time = check_time_difference(t1, t2)

print(elapsed_time)
#return : 0:08:52

C#: Waiting for all threads to complete

Possible solution:

var tasks = dataList
    .Select(data => Task.Factory.StartNew(arg => DoThreadStuff(data), TaskContinuationOptions.LongRunning | TaskContinuationOptions.PreferFairness))
    .ToArray();

var timeout = TimeSpan.FromMinutes(1);
Task.WaitAll(tasks, timeout);

Assuming dataList is the list of items and each item needs to be processed in a separate thread.

java.lang.ClassNotFoundException: org.eclipse.core.runtime.adaptor.EclipseStarter

You might be launching your application from a Product file which is not linked to the plugin file. Reset your workspace and launch using the MANIFEST.MF > Overview > Testing > Launch.

Get a Windows Forms control by name in C#

Have a look at the ToolStrip.Items collection. It even has a find method available.

convert datetime to date format dd/mm/yyyy

You have to pass the CultureInfo to get the result with slash(/)

DateTime.Now.ToString("dd/MM/yyyy", CultureInfo.InvariantCulture)

Explaining Python's '__enter__' and '__exit__'

try adding my answers (my thought of learning) :

__enter__ and [__exit__] both are methods that are invoked on entry to and exit from the body of "the with statement" (PEP 343) and implementation of both is called context manager.

the with statement is intend to hiding flow control of try finally clause and make the code inscrutable.

the syntax of the with statement is :

with EXPR as VAR:
    BLOCK

which translate to (as mention in PEP 343) :

mgr = (EXPR)
exit = type(mgr).__exit__  # Not calling it yet
value = type(mgr).__enter__(mgr)
exc = True
try:
    try:
        VAR = value  # Only if "as VAR" is present
        BLOCK
    except:
        # The exceptional case is handled here
        exc = False
        if not exit(mgr, *sys.exc_info()):
            raise
        # The exception is swallowed if exit() returns true
finally:
    # The normal and non-local-goto cases are handled here
    if exc:
        exit(mgr, None, None, None)

try some code:

>>> import logging
>>> import socket
>>> import sys

#server socket on another terminal / python interpreter
>>> s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
>>> s.listen(5)
>>> s.bind((socket.gethostname(), 999))
>>> while True:
>>>    (clientsocket, addr) = s.accept()
>>>    print('get connection from %r' % addr[0])
>>>    msg = clientsocket.recv(1024)
>>>    print('received %r' % msg)
>>>    clientsocket.send(b'connected')
>>>    continue

#the client side
>>> class MyConnectionManager:
>>>     def __init__(self, sock, addrs):
>>>         logging.basicConfig(level=logging.DEBUG, format='%(asctime)s \
>>>         : %(levelname)s --> %(message)s')
>>>         logging.info('Initiating My connection')
>>>         self.sock = sock
>>>         self.addrs = addrs
>>>     def __enter__(self):
>>>         try:
>>>             self.sock.connect(addrs)
>>>             logging.info('connection success')
>>>             return self.sock
>>>         except:
>>>             logging.warning('Connection refused')
>>>             raise
>>>     def __exit__(self, type, value, tb):
>>>             logging.info('CM suppress exception')
>>>             return False
>>> addrs = (socket.gethostname())
>>> s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
>>> with MyConnectionManager(s, addrs) as CM:
>>>     try:
>>>         CM.send(b'establishing connection')
>>>         msg = CM.recv(1024)
>>>         print(msg)
>>>     except:
>>>         raise
#will result (client side) :
2018-12-18 14:44:05,863         : INFO --> Initiating My connection
2018-12-18 14:44:05,863         : INFO --> connection success
b'connected'
2018-12-18 14:44:05,864         : INFO --> CM suppress exception

#result of server side
get connection from '127.0.0.1'
received b'establishing connection'

and now try manually (following translate syntax):

>>> s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) #make new socket object
>>> mgr = MyConnection(s, addrs)
2018-12-18 14:53:19,331         : INFO --> Initiating My connection
>>> ext = mgr.__exit__
>>> value = mgr.__enter__()
2018-12-18 14:55:55,491         : INFO --> connection success
>>> exc = True
>>> try:
>>>     try:
>>>         VAR = value
>>>         VAR.send(b'establishing connection')
>>>         msg = VAR.recv(1024)
>>>         print(msg)
>>>     except:
>>>         exc = False
>>>         if not ext(*sys.exc_info()):
>>>             raise
>>> finally:
>>>     if exc:
>>>         ext(None, None, None)
#the result:
b'connected'
2018-12-18 15:01:54,208         : INFO --> CM suppress exception

the result of the server side same as before

sorry for my bad english and my unclear explanations, thank you....

How to add onload event to a div element

You cannot add event onload on div, but you can add onkeydown and trigger onkeydown event on document load

_x000D_
_x000D_ 
$(function ()_x000D_
{_x000D_
  $(".ccsdvCotentPS").trigger("onkeydown");_x000D_
});
_x000D_ 
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.2.3/jquery.min.js"></script>_x000D_
_x000D_
<div  onkeydown="setCss( );"> </div>`
_x000D_
_x000D_
_x000D_

Java: how to add image to Jlabel?

(If you are using NetBeans IDE) Just create a folder in your project but out side of src folder. Named the folder Images. And then put the image into the Images folder and write code below.

// Import ImageIcon     
ImageIcon iconLogo = new ImageIcon("Images/YourCompanyLogo.png");
// In init() method write this code
jLabelYourCompanyLogo.setIcon(iconLogo);

Now run your program.

How to POST JSON request using Apache HttpClient?

As mentioned in the excellent answer by janoside, you need to construct the JSON string and set it as a StringEntity.

To construct the JSON string, you can use any library or method you are comfortable with. Jackson library is one easy example:

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ObjectNode;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;

ObjectMapper mapper = new ObjectMapper();
ObjectNode node = mapper.createObjectNode();
node.put("name", "value"); // repeat as needed
String JSON_STRING = node.toString();
postMethod.setEntity(new StringEntity(JSON_STRING, ContentType.APPLICATION_JSON));

How to do a num_rows() on COUNT query in codeigniter?

I'd suggest instead of doing another query with the same parameters just immediately running a SELECT FOUND_ROWS()

Share application "link" in Android

To automatically fill in the application name and application id you could use this:

int applicationNameId = context.getApplicationInfo().labelRes;
final String appPackageName = context.getPackageName();
Intent i = new Intent(Intent.ACTION_SEND);
i.setType("text/plain");
i.putExtra(Intent.EXTRA_SUBJECT, activity.getString(applicationNameId));
String text = "Install this cool application: ";
String link = "https://play.google.com/store/apps/details?id=" + appPackageName;
i.putExtra(Intent.EXTRA_TEXT, text + " " + link);
startActivity(Intent.createChooser(i, "Share link:"));

How to find the foreach index?

PHP arrays have internal pointers, so try this:

foreach($array as $key => $value){
   $index = current($array);
}

Works okay for me (only very preliminarily tested though).

How do I exclude Weekend days in a SQL Server query?

The answer depends on your server's week-start set up, so it's either

SELECT [date_created] FROM table WHERE DATEPART(w,[date_created]) NOT IN (7,1)

if Sunday is the first day of the week for your server

or

SELECT [date_created] FROM table WHERE DATEPART(w,[date_created]) NOT IN (6,7)

if Monday is the first day of the week for your server

Comment if you've got any questions :-)

ASP.NET document.getElementById('<%=Control.ClientID%>'); returns null

Is Button1 visible? I mean, from the server side. Make sure Button1.Visible is true.

Controls that aren't Visible won't be rendered in HTML, so although they are assigned a ClientID, they don't actually exist on the client side.

Failed to connect to mailserver at "localhost" port 25, verify your "SMTP" and "smtp_port" setting in php.ini or use ini_set()

If you are running your application just on localhost and it is not yet live, I believe it is very difficult to send mail using this.

Once you put your application online, I believe that this problem should be automatically solved. By the way,ini_set() helps you to change the values in php.ini during run time.

This is the same question as Failed to connect to mailserver at "localhost" port 25

also check this php mail function not working

How should I deal with "package 'xxx' is not available (for R version x.y.z)" warning?

I fixed this error on Ubuntu by carefully following the instructions for installing R. This included:

  1. adding deb http://cran.utstat.utoronto.ca/bin/linux/ubuntu trusty/ to my /etc/apt/sources.list file
  2. Running sudo apt-get update
  3. Running sudo apt-get install r-base-dev

For step 1 you can chose any CRAN download mirror in place of my University of Toronto one if you would like.

Bad operand type for unary +: 'str'

The code works for me. (after adding missing except clause / import statements)

Did you put \ in the original code?

urlToVisit = 'http://chartapi.finance.yahoo.com/instrument/1.0/' \
              + stock + '/chartdata;type=quote;range=5d/csv'

If you omit it, it could be a cause of the exception:

>>> stock = 'GOOG'
>>> urlToVisit = 'http://chartapi.finance.yahoo.com/instrument/1.0/'
>>> + stock + '/chartdata;type=quote;range=5d/csv'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: bad operand type for unary +: 'str'

BTW, string(e) should be str(e).

Appending to an object

Do you have the ability to change the outer-most structure to an array? So it would look like this

var alerts = [{"app":"helloworld","message":null},{"app":"helloagain","message":"another message"}];

So when you needed to add one, you can just push it onto the array

alerts.push( {"app":"goodbyeworld","message":"cya"} );

Then you have a built-in zero-based index for how the errors are enumerated.

Add a space (" ") after an element using :after

Turns out it needs to be specified via escaped unicode. This question is related and contains the answer.

The solution:

h2:after {
    content: "\00a0";
}

Spring MVC Controller redirect using URL parameters instead of in response

If you don't want the success message in the URL, then one option is to put it in the session (in the processForm method) and then check for it (and remove it) in the setupForm method.

Edited to add: if this is a pain to do manually, then you could write a subclass of RedirectView that adds a "message" attribute and wraps the process of inserting it into the session. Not sure, though, if there's an easy way to wrap getting the message back out of the session...

Honestly, I don't think there's an easy answer -- the nature of an HTTP redirect is that state isn't carried over; if you want to maintain state anyway, you're stuck with the various usual ways to maintain state in web applications: the session, a cookie, a querystring...

ORA-12516, TNS:listener could not find available handler

I fixed this problem with sql command line:

connect system/<password>
alter system set processes=300 scope=spfile;
alter system set sessions=300 scope=spfile;

Restart database.

diff current working copy of a file with another branch's committed copy

 
git diff mybranch master -- file

should also work

How to get values of selected items in CheckBoxList with foreach in ASP.NET C#?

I like to use this simple method to get the selected values and join them into a string

private string JoinCBLSelectedValues(CheckBoxList cbl, string separator = "")
{
    return string.Join(separator, cbl.Items.Cast<ListItem>().Where(li => li.Selected).ToList());
}

How to tar certain file types in all subdirectories?

find ./ -type f -name "*.php" -o -name "*.html" -printf '%P\n' |xargs tar -I 'pigz -9' -cf target.tgz

for multicore or just for one core:

find ./ -type f -name "*.php" -o -name "*.html" -printf '%P\n' |xargs tar -czf target.tgz

max value of integer

The C language definition specifies minimum ranges for various data types. For int, this minimum range is -32767 to 32767, meaning an int must be at least 16 bits wide. An implementation is free to provide a wider int type with a correspondingly wider range. For example, on the SLES 10 development server I work on, the range is -2147483647 to 2137483647.

There are still some systems out there that use 16-bit int types (All The World Is Not A VAX x86), but there are plenty that use 32-bit int types, and maybe a few that use 64-bit.

The C language was designed to run on different architectures. Java was designed to run in a virtual machine that hides those architectural differences.

How to create multiple page app using react

(Make sure to install react-router using npm!)

To use react-router, you do the following:

  1. Create a file with routes defined using Route, IndexRoute components

  2. Inject the Router (with 'r'!) component as the top-level component for your app, passing the routes defined in the routes file and a type of history (hashHistory, browserHistory)

  3. Add {this.props.children} to make sure new pages will be rendered there
  4. Use the Link component to change pages

Step 1 routes.js

import React from 'react';
import { Route, IndexRoute } from 'react-router';

/**
 * Import all page components here
 */
import App from './components/App';
import MainPage from './components/MainPage';
import SomePage from './components/SomePage';
import SomeOtherPage from './components/SomeOtherPage';

/**
 * All routes go here.
 * Don't forget to import the components above after adding new route.
 */
export default (
  <Route path="/" component={App}>
    <IndexRoute component={MainPage} />
    <Route path="/some/where" component={SomePage} />
    <Route path="/some/otherpage" component={SomeOtherPage} />
  </Route>
);

Step 2 entry point (where you do your DOM injection)

// You can choose your kind of history here (e.g. browserHistory)
import { Router, hashHistory as history } from 'react-router';
// Your routes.js file
import routes from './routes';

ReactDOM.render(
  <Router routes={routes} history={history} />,
  document.getElementById('your-app')
);

Step 3 The App component (props.children)

In the render for your App component, add {this.props.children}:

render() {
  return (
    <div>
      <header>
        This is my website!
      </header>

      <main>
        {this.props.children}
      </main>

      <footer>
        Your copyright message
      </footer>
    </div>
  );
}

Step 4 Use Link for navigation

Anywhere in your component render function's return JSX value, use the Link component:

import { Link } from 'react-router';
(...)
<Link to="/some/where">Click me</Link>

Change value of input and submit form in JavaScript

You're trying to access an element based on the name attribute which works for postbacks to the server, but JavaScript responds to the id attribute. Add an id with the same value as name and all should work fine.

<form name="myform" id="myform" action="action.php">
  <input type="hidden" name="myinput" id="myinput" value="0" />
  <input type="text" name="message" id="message" value="" />
  <input type="submit" name="submit" id="submit" onclick="DoSubmit()" />
</form>

function DoSubmit(){
  document.getElementById("myinput").value = '1';
  return true;
}

Find column whose name contains a specific string

 
# select columns containing 'spike'
df.filter(like='spike', axis=1)

You can also select by name, regular expression. Refer to: pandas.DataFrame.filter

Python MYSQL update statement

It should be:

cursor.execute ("""
   UPDATE tblTableName
   SET Year=%s, Month=%s, Day=%s, Hour=%s, Minute=%s
   WHERE Server=%s
""", (Year, Month, Day, Hour, Minute, ServerID))

You can also do it with basic string manipulation,

cursor.execute ("UPDATE tblTableName SET Year=%s, Month=%s, Day=%s, Hour=%s, Minute=%s WHERE Server='%s' " % (Year, Month, Day, Hour, Minute, ServerID))

but this way is discouraged because it leaves you open for SQL Injection. As it's so easy (and similar) to do it the right waytm. Do it correctly.

The only thing you should be careful, is that some database backends don't follow the same convention for string replacement (SQLite comes to mind).

How to make Visual Studio copy a DLL file to the output directory?

Use a post-build action in your project, and add the commands to copy the offending DLL. The post-build action are written as a batch script.

The output directory can be referenced as $(OutDir). The project directory is available as $(ProjDir). Try to use relative pathes where applicable, so that you can copy or move your project folder without breaking the post-build action.

Java, How do I get current index/key in "for each" loop

In Java, you can't, as foreach was meant to hide the iterator. You must do the normal For loop in order to get the current iteration.

PHP function ssh2_connect is not working

I have solved this on ubuntu 16.4 PHP 7.0.27-0+deb9u and nginx

sudo apt install php-ssh2

Accept server's self-signed ssl certificate in Java client

If 'they' are using a self-signed certificate it is up to them to take the steps required to make their server usable. Specifically that means providing their certificate to you offline in a trustworthy way. So get them to do that. You then import that into your truststore using the keytool as described in the JSSE Reference Guide. Don't even think about the insecure TrustManager posted here.

EDIT For the benefit of the seventeen (!) downvoters, and numerous commenters below, who clearly have not actually read what I have written here, this is not a jeremiad against self-signed certificates. There is nothing wrong with self-signed certificates when implemented correctly. But, the correct way to implement them is to have the certificate delivered securely via an offline process, rather than via the unauthenticated channel they are going to be used to authenticate. Surely this is obvious? It is certainly obvious to every security-aware organization I have ever worked for, from banks with thousands of branches to my own companies. The client-side code-base 'solution' of trusting all certificates, including self-signed certificates signed by absolutely anybody, or any arbitary body setting itself up as a CA, is ipso facto not secure. It is just playing at security. It is pointless. You are having a private, tamperproof, reply-proof, injection-proof conversation with ... somebody. Anybody. A man in the middle. An impersonator. Anybody. You may as well just use plaintext.

Hot to get all form elements values using jQuery?

I needed to get the form data as some sort of object. I used this:

$('#preview_form').serializeArray().reduce((function(acc, val) {
  acc[val.name.replace('[', '_').replace(']', '')] = val.value;
  return acc;
}), {});

How to getElementByClass instead of GetElementById with JavaScript?

 
document.getElementsByClassName('CLASSNAME')[0].style.display = 'none';

Acyually by using getElementsByClassName, it returns an array of multiple classes. Because same class name could be used in more than one instance inside same HTML page. We use array element id to target the class we need, in my case, it's first instance of the given class name.So I've used [0]

How to iterate (keys, values) in JavaScript?

You can do something like this :

dictionary = {'ab': {object}, 'cd':{object}, 'ef':{object}}
var keys = Object.keys(dictionary);

for(var i = 0; i < keys.length;i++){
   //keys[i] for key
   //dictionary[keys[i]] for the value
}

Check whether a path is valid in Python without creating a file at the path's target

 
open(filename,'r')   #2nd argument is r and not w

will open the file or give an error if it doesn't exist. If there's an error, then you can try to write to the path, if you can't then you get a second error

try:
    open(filename,'r')
    return True
except IOError:
    try:
        open(filename, 'w')
        return True
    except IOError:
        return False

Also have a look here about permissions on windows

How to delete a cookie?

Here a good link on Quirksmode.

function setCookie(name,value,days) {
    var expires = "";
    if (days) {
        var date = new Date();
        date.setTime(date.getTime() + (days*24*60*60*1000));
        expires = "; expires=" + date.toUTCString();
    }
    document.cookie = name + "=" + (value || "")  + expires + "; path=/";
}
function getCookie(name) {
    var nameEQ = name + "=";
    var ca = document.cookie.split(';');
    for(var i=0;i < ca.length;i++) {
        var c = ca[i];
        while (c.charAt(0)==' ') c = c.substring(1,c.length);
        if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
    }
    return null;
}
function eraseCookie(name) {   
    document.cookie = name+'=; Max-Age=-99999999;';  
}

navigator.geolocation.getCurrentPosition sometimes works sometimes doesn't

This works for me every time:

navigator.geolocation.getCurrentPosition(getCoor, errorCoor, {maximumAge:60000, timeout:5000, enableHighAccuracy:true});

Though it isn't very accurate. The funny thing is that on the same device if I run this it puts me off about 100 meters (every time), but if I go to google's maps it finds my location exactly. So although I think the enableHighAccuracy: true helps it to work consistently, it doesn't seem to make it any more accurate...

Deserializing JSON data to C# using JSON.NET

I found my I had built my object incorrectly. I used http://json2csharp.com/ to generate me my object class from the JSON. Once I had the correct Oject I was able to cast without issue. Norbit, Noob mistake. Thought I'd add it in case you have the same issue.

How to get to Model or Viewbag Variables in a Script Tag

Use single quotation marks ('): 

var val = '@ViewBag.ForSection';
alert(val);

What's the best way to store a group of constants that my program uses?

I would suggest static class with static readonly. Please find the code snippet below:

  public static class CachedKeysManager
    {
        public static readonly string DistributorList = "distributorList";
    }

How do I retrieve an HTML element's actual width and height?

Use width param as follows:

   style={{
      width: "80%",
      paddingLeft: 100,
      paddingRight: 200,
      paddingTop: 30,
      paddingBottom: 30,
      border: "3px solid lightGray",
    }}

Show SOME invisible/whitespace characters in Eclipse

I would prefer to keep the "Show Whitespace" button on the toolbar, so that in one click you can toggle it.

Go to Window -> Perspective -> Customize Perspective and enable to show the button on toolbar.

enter image description here

How to do SQL Like % in Linq?

For those how tumble here like me looking for a way to a "SQL Like" method in LINQ, I've something that is working very good.

I'm in a case where I cannot alter the Database in any way to change the column collation. So I've to find a way in my LINQ to do it.

I'm using the helper method SqlFunctions.PatIndex witch act similarly to the real SQL LIKE operator.

First I need enumerate all possible diacritics (a word that I just learned) in the search value to get something like:

déjà     => d[éèêëeÉÈÊËE]j[aàâäAÀÂÄ]
montreal => montr[éèêëeÉÈÊËE][aàâäAÀÂÄ]l
montréal => montr[éèêëeÉÈÊËE][aàâäAÀÂÄ]l

and then in LINQ for exemple:

var city = "montr[éèêëeÉÈÊËE][aàâäAÀÂÄ]l";
var data = (from loc in _context.Locations
                     where SqlFunctions.PatIndex(city, loc.City) > 0
                     select loc.City).ToList();

So for my needs I've written a Helper/Extension method 

   public static class SqlServerHelper
    {

        private static readonly List<KeyValuePair<string, string>> Diacritics = new List<KeyValuePair<string, string>>()
        {
            new KeyValuePair<string, string>("A", "aàâäAÀÂÄ"),
            new KeyValuePair<string, string>("E", "éèêëeÉÈÊËE"),
            new KeyValuePair<string, string>("U", "uûüùUÛÜÙ"),
            new KeyValuePair<string, string>("C", "cçCÇ"),
            new KeyValuePair<string, string>("I", "iîïIÎÏ"),
            new KeyValuePair<string, string>("O", "ôöÔÖ"),
            new KeyValuePair<string, string>("Y", "YŸÝýyÿ")
        };

        public static string EnumarateDiacritics(this string stringToDiatritics)
        {
            if (string.IsNullOrEmpty(stringToDiatritics.Trim()))
                return stringToDiatritics;

            var diacriticChecked = string.Empty;

            foreach (var c in stringToDiatritics.ToCharArray())
            {
                var diac = Diacritics.FirstOrDefault(o => o.Value.ToCharArray().Contains(c));
                if (string.IsNullOrEmpty(diac.Key))
                    continue;

                //Prevent from doing same letter/Diacritic more than one time
                if (diacriticChecked.Contains(diac.Key))
                    continue;

                diacriticChecked += diac.Key;

                stringToDiatritics = stringToDiatritics.Replace(c.ToString(), "[" + diac.Value + "]");
            }

            stringToDiatritics = "%" + stringToDiatritics + "%";
            return stringToDiatritics;
        }
    }

If any of you have suggestion to enhance this method, I'll be please to hear you.

What is the default stack size, can it grow, how does it work with garbage collection?

As you say, local variables and references are stored on the stack. When a method returns, the stack pointer is simply moved back to where it was before the method started, that is, all local data is "removed from the stack". Therefore, there is no garbage collection needed on the stack, that only happens in the heap.

To answer your specific questions:

  • See this question on how to increase the stack size.
  • You can limit the stack growth by:
    • grouping many local variables in an object: that object will be stored in the heap and only the reference is stored on the stack
    • limit the number of nested function calls (typically by not using recursion)
  • For windows, the default stack size is 320k for 32bit and 1024k for 64bit, see this link.

Update span tag value with JQuery

Tag ids must be unique. You are updating the span with ID 'ItemCostSpan' of which there are two. Give the span a class and get it using find.

    $("legend").each(function() {
        var SoftwareItem = $(this).text();
        itemCost = GetItemCost(SoftwareItem);
        $("input:checked").each(function() {               
            var Component = $(this).next("label").text();
            itemCost += GetItemCost(Component);
        });            
        $(this).find(".ItemCostSpan").text("Item Cost = $ " + itemCost);
    });

SQL Server: Importing database from .mdf?

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

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

Is there a decorator to simply cache function return values?

I coded this simple decorator class to cache function responses. I find it VERY useful for my projects:

from datetime import datetime, timedelta 

class cached(object):
    def __init__(self, *args, **kwargs):
        self.cached_function_responses = {}
        self.default_max_age = kwargs.get("default_cache_max_age", timedelta(seconds=0))

    def __call__(self, func):
        def inner(*args, **kwargs):
            max_age = kwargs.get('max_age', self.default_max_age)
            if not max_age or func not in self.cached_function_responses or (datetime.now() - self.cached_function_responses[func]['fetch_time'] > max_age):
                if 'max_age' in kwargs: del kwargs['max_age']
                res = func(*args, **kwargs)
                self.cached_function_responses[func] = {'data': res, 'fetch_time': datetime.now()}
            return self.cached_function_responses[func]['data']
        return inner

The usage is straightforward:

import time

@cached
def myfunc(a):
    print "in func"
    return (a, datetime.now())

@cached(default_max_age = timedelta(seconds=6))
def cacheable_test(a):
    print "in cacheable test: "
    return (a, datetime.now())


print cacheable_test(1,max_age=timedelta(seconds=5))
print cacheable_test(2,max_age=timedelta(seconds=5))
time.sleep(7)
print cacheable_test(3,max_age=timedelta(seconds=5))

How to create a template function within a class? (C++)

The easiest way is to put the declaration and definition in the same file, but it may cause over-sized excutable file. E.g.

class Foo
{
public:
template <typename T> void some_method(T t) {//...}
}

Also, it is possible to put template definition in the separate files, i.e. to put them in .cpp and .h files. All you need to do is to explicitly include the template instantiation to the .cpp files. E.g.

// .h file
class Foo
{
public:
template <typename T> void some_method(T t);
}

// .cpp file
//...
template <typename T> void Foo::some_method(T t) 
{//...}
//...

template void Foo::some_method<int>(int);
template void Foo::some_method<double>(double);

How to find whether or not a variable is empty in Bash?

 
if [ ${foo:+1} ]
then
    echo "yes"
fi

prints yes if the variable is set. ${foo:+1} will return 1 when the variable is set, otherwise it will return empty string.

How to include() all PHP files from a directory?

 
foreach (glob("classes/*.php") as $filename)
{
    include $filename;
}

Find files and tar them (with spaces)

Another solution as seen here:

find var/log/ -iname "anaconda.*" -exec tar -cvzf file.tar.gz {} +

Save and load MemoryStream to/from a file

The stream should really by disposed of even if there's an exception (quite likely on file I/O) - using clauses are my favourite approach for this, so for writing your MemoryStream, you can use:

using (FileStream file = new FileStream("file.bin", FileMode.Create, FileAccess.Write)) {
    memoryStream.WriteTo(file);
}

And for reading it back:

using (FileStream file = new FileStream("file.bin", FileMode.Open, FileAccess.Read)) {
    byte[] bytes = new byte[file.Length];
    file.Read(bytes, 0, (int)file.Length);
    ms.Write(bytes, 0, (int)file.Length);
}

If the files are large, then it's worth noting that the reading operation will use twice as much memory as the total file size. One solution to that is to create the MemoryStream from the byte array - the following code assumes you won't then write to that stream.

MemoryStream ms = new MemoryStream(bytes, writable: false);

My research (below) shows that the internal buffer is the same byte array as you pass it, so it should save memory.

byte[] testData = new byte[] { 104, 105, 121, 97 };
var ms = new MemoryStream(testData, 0, 4, false, true);
Assert.AreSame(testData, ms.GetBuffer());

How to Update a Component without refreshing full page - Angular

You can use a BehaviorSubject for communicating between different components throughout the app. You can define a data sharing service containing the BehaviorSubject to which you can subscribe and emit changes.

Define a data sharing service 

import { Injectable } from '@angular/core';
import { BehaviorSubject } from 'rxjs';

@Injectable()
export class DataSharingService {
    public isUserLoggedIn: BehaviorSubject<boolean> = new BehaviorSubject<boolean>(false);
}

Add the DataSharingService in your AppModule providers entry.

Next, import the DataSharingService in your <app-header> and in the component where you perform the sign-in operation. In <app-header> subscribe to the changes to isUserLoggedIn subject: 

import { DataSharingService } from './data-sharing.service';

export class AppHeaderComponent { 
    // Define a variable to use for showing/hiding the Login button
    isUserLoggedIn: boolean;

    constructor(private dataSharingService: DataSharingService) {

        // Subscribe here, this will automatically update 
        // "isUserLoggedIn" whenever a change to the subject is made.
        this.dataSharingService.isUserLoggedIn.subscribe( value => {
            this.isUserLoggedIn = value;
        });
    }
}

In your <app-header> html template, you need to add the *ngIf condition e.g.: 

<button *ngIf="!isUserLoggedIn">Login</button> 
<button *ngIf="isUserLoggedIn">Sign Out</button>

Finally, you just need to emit the event once the user has logged in e.g: 

someMethodThatPerformsUserLogin() {
    // Some code 
    // .....
    // After the user has logged in, emit the behavior subject changes.
    this.dataSharingService.isUserLoggedIn.next(true);
}

How do I convert a javascript object array to a string array of the object attribute I want?

You can use this function:

function createStringArray(arr, prop) {
   var result = [];
   for (var i = 0; i < arr.length; i += 1) {
      result.push(arr[i][prop]);
   }
   return result;
}

Just pass the array of objects and the property you need. The script above will work even in old EcmaScript implementations.

Using env variable in Spring Boot's application.properties

You don't need to use java variables. To include system env variables add the following to your application.properties file:

spring.datasource.url = ${OPENSHIFT_MYSQL_DB_HOST}:${OPENSHIFT_MYSQL_DB_PORT}/"nameofDB"
spring.datasource.username = ${OPENSHIFT_MYSQL_DB_USERNAME}
spring.datasource.password = ${OPENSHIFT_MYSQL_DB_PASSWORD}

But the way suggested by @Stefan Isele is more preferable, because in this case you have to declare just one env variable: spring.profiles.active. Spring will read the appropriate property file automatically by application-{profile-name}.properties template.

Can Mockito stub a method without regard to the argument?

http://site.mockito.org/mockito/docs/1.10.19/org/mockito/Matchers.html

anyObject() should fit your needs.

Also, you can always consider implementing hashCode() and equals() for the Bazoo class. This would make your code example work the way you want.

Can't bind to 'formControl' since it isn't a known property of 'input' - Angular2 Material Autocomplete issue

Start by adding a regular matInput to your template. Let's assume you're using the formControl directive from ReactiveFormsModule to track the value of the input.

Reactive forms provide a model-driven approach to handling form inputs whose values change over time. This guide shows you how to create and update a simple form control, progress to using multiple controls in a group, validate form values, and implement more advanced forms.

import { FormsModule, ReactiveFormsModule } from "@angular/forms"; //this to use ngModule

...

imports: [
    BrowserModule,
    AppRoutingModule,
    HttpModule,
    FormsModule,
    RouterModule,
    ReactiveFormsModule,
    BrowserAnimationsModule,
    MaterialModule],

How do I concatenate a string with a variable?

It's just like you did. And I'll give you a small tip for these kind of silly things: just use the browser url box to try js syntax. for example, write this: javascript:alert("test"+5) and you have your answer. The problem in your code is probably that this element does not exist in your document... maybe it's inside a form or something. You can test this too by writing in the url: javascript:alert(document.horseThumb_5) to check where your mistake is.

Update all objects in a collection using LINQ

 
collection.ToList().ForEach(c => c.PropertyToSet = value);

Is there a "standard" format for command line/shell help text?

The GNU Coding Standard is a good reference for things like this. This section deals with the output of --help. In this case it is not very specific. You probably can't go wrong with printing a table showing the short and long options and a succinct description. Try to get the spacing between all arguments right for readability. You probably want to provide a man page (and possibly an info manual) for your tool to provide a more elaborate explanation.

Capturing URL parameters in request.GET

You have two common ways to do that in case your URL looks like that:

https://domain/method/?a=x&b=y

Version 1:

If a specific key is mandatory you can use:

key_a = request.GET['a']

This will return a value of a if the key exists and an exception if not.

Version 2:

If your keys are optional:

request.GET.get('a')

You can try that without any argument and this will not crash. So you can wrap it with try: except: and return HttpResponseBadRequest() in example. This is a simple way to make your code less complex, without using special exceptions handling.

Setting Remote Webdriver to run tests in a remote computer using Java

This issue came for me due to the fact that .. i was running server with selenium-server-standalone-2.32.0 and client registered with selenium-server-standalone-2.37.0 .. When i made both selenium-server-standalone-2.32.0 and ran then things worked fine

How do you remove an array element in a foreach loop?

If you also get the key, you can delete that item like this:

foreach ($display_related_tags as $key => $tag_name) {
    if($tag_name == $found_tag['name']) {
        unset($display_related_tags[$key]);
    }
}

how to get html content from a webview?

I suggest to try out some Reflection approach, if you have time to spend on the debugger (sorry but I didn't have).

Starting from the loadUrl() method of the android.webkit.WebView class:

http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/2.2_r1.1/android/webkit/WebView.java#WebView.loadUrl%28java.lang.String%2Cjava.util.Map%29

You should arrive on the android.webkit.BrowserFrame that call the nativeLoadUrl() native method:

http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/2.2_r1.1/android/webkit/BrowserFrame.java#BrowserFrame.nativeLoadUrl%28java.lang.String%2Cjava.util.Map%29

The implementation of the native method should be here:

http://gitorious.org/0xdroid/external_webkit/blobs/a538f34148bb04aa6ccfbb89dfd5fd784a4208b1/WebKit/android/jni/WebCoreFrameBridge.cpp

Wish you good luck!

Using <style> tags in the <body> with other HTML

I guess this will vary from browser to browser: The global display rules will probably be updated as the browser goes along through the code.

You can see such changes in the global display rules sometimes when an external style sheet is loaded with a delay. Something similar might happen here but in such short succession that it doesn't actually get rendered.

It's not valid HTML anyway, so I'd say that it is a futile thing to think about. <style> tags belong in the head section of the page.

Convert UTC/GMT time to local time

 
TimeZone.CurrentTimeZone.ToLocalTime(date);

Redeploy alternatives to JRebel

You might want to take a look this:

HotSwap support: the object-oriented architecture of the Java HotSpot VM enables advanced features such as on-the-fly class redefinition, or "HotSwap". This feature provides the ability to substitute modified code in a running application through the debugger APIs. HotSwap adds functionality to the Java Platform Debugger Architecture, enabling a class to be updated during execution while under the control of a debugger. It also allows profiling operations to be performed by hotswapping in versions of methods in which profiling code has been inserted.

For the moment, this only allows for newly compiled method body to be redeployed without restarting the application. All you have to do is to run it with a debugger. I tried it in Eclipse and it works splendidly.

Also, as Emmanuel Bourg mentioned in his answer (JEP 159), there is hope to have support for the addition of supertypes and the addition and removal of methods and fields.

Reference: Java Whitepaper 135217: Reliability, Availability and Serviceability

Representing Directory & File Structure in Markdown Syntax

If you are concerned about Unicode characters you can use ASCII to build the structures, so your example structure becomes

.
+-- _config.yml
+-- _drafts
|   +-- begin-with-the-crazy-ideas.textile
|   +-- on-simplicity-in-technology.markdown
+-- _includes
|   +-- footer.html
|   +-- header.html
+-- _layouts
|   +-- default.html
|   +-- post.html
+-- _posts
|   +-- 2007-10-29-why-every-programmer-should-play-nethack.textile
|   +-- 2009-04-26-barcamp-boston-4-roundup.textile
+-- _data
|   +-- members.yml
+-- _site
+-- index.html

Which is similar to the format tree uses if you select ANSI output.

Loading a properties file from Java package

When loading the Properties from a Class in the package com.al.common.email.templates you can use

Properties prop = new Properties();
InputStream in = getClass().getResourceAsStream("foo.properties");
prop.load(in);
in.close();

(Add all the necessary exception handling).

If your class is not in that package, you need to aquire the InputStream slightly differently:

InputStream in = 
 getClass().getResourceAsStream("/com/al/common/email/templates/foo.properties");

Relative paths (those without a leading '/') in getResource()/getResourceAsStream() mean that the resource will be searched relative to the directory which represents the package the class is in.

Using java.lang.String.class.getResource("foo.txt") would search for the (inexistent) file /java/lang/String/foo.txt on the classpath.

Using an absolute path (one that starts with '/') means that the current package is ignored.

How can I login to a website with Python?

 
import cookielib
import urllib
import urllib2

url = 'http://www.someserver.com/auth/login'
values = {'email-email' : '[email protected]',
          'password-clear' : 'Combination',
          'password-password' : 'mypassword' }

data = urllib.urlencode(values)
cookies = cookielib.CookieJar()

opener = urllib2.build_opener(
    urllib2.HTTPRedirectHandler(),
    urllib2.HTTPHandler(debuglevel=0),
    urllib2.HTTPSHandler(debuglevel=0),
    urllib2.HTTPCookieProcessor(cookies))

response = opener.open(url, data)
the_page = response.read()
http_headers = response.info()
# The login cookies should be contained in the cookies variable

For more information visit: https://docs.python.org/2/library/urllib2.html

Splitting strings in PHP and get last part

You can do it like this:

$str = "abc-123-xyz-789";
$last = array_pop( explode('-', $str) );
echo $last; //echoes 789

Error in your SQL syntax; check the manual that corresponds to your MySQL server version

Some special characters give this type of error, so use

$query="INSERT INTO `tablename` (`name`, `email`)
VALUES
('$_POST[name]','$_POST[email]')";

Parse Error: Adjacent JSX elements must be wrapped in an enclosing tag

Import view and wrap in View. Wrapping in a div did not work for me.

import { View } from 'react-native';
...
    render() {
      return (
        <View>
          <h1>foo</h1>
          <h2>bar</h2>
        </View>
      );
    }

Understanding the order() function

Running this little piece of code allowed me to understand the order function

x <- c(3, 22, 5, 1, 77)

cbind(
  index=1:length(x),
  rank=rank(x),
  x, 
  order=order(x), 
  sort=sort(x)
)

     index rank  x order sort
[1,]     1    2  3     4    1
[2,]     2    4 22     1    3
[3,]     3    3  5     3    5
[4,]     4    1  1     2   22
[5,]     5    5 77     5   77

Reference: http://r.789695.n4.nabble.com/I-don-t-understand-the-order-function-td4664384.html

How to toggle boolean state of react component?

Set: const [state, setState] = useState(1);

Toggle: setState(state*-1);

Use: state > 0 ? 'on' : 'off';

Parsing JSON in Excel VBA

To parse JSON in VBA without adding a huge library to your workbook project, I created the following solution. It's extremely fast and stores all of the keys and values in a dictionary for easy access:

Function ParseJSON(json$, Optional key$ = "obj") As Object
    p = 1
    token = Tokenize(json)
    Set dic = CreateObject("Scripting.Dictionary")
    If token(p) = "{" Then ParseObj key Else ParseArr key
    Set ParseJSON = dic
End Function

Function ParseObj(key$)
    Do: p = p + 1
        Select Case token(p)
            Case "]"
            Case "[":  ParseArr key
            Case "{"
                       If token(p + 1) = "}" Then
                           p = p + 1
                           dic.Add key, "null"
                       Else
                           ParseObj key
                       End If
            
            Case "}":  key = ReducePath(key): Exit Do
            Case ":":  key = key & "." & token(p - 1)
            Case ",":  key = ReducePath(key)
            Case Else: If token(p + 1) <> ":" Then dic.Add key, token(p)
        End Select
    Loop
End Function

Function ParseArr(key$)
    Dim e&
    Do: p = p + 1
        Select Case token(p)
            Case "}"
            Case "{":  ParseObj key & ArrayID(e)
            Case "[":  ParseArr key
            Case "]":  Exit Do
            Case ":":  key = key & ArrayID(e)
            Case ",":  e = e + 1
            Case Else: dic.Add key & ArrayID(e), token(p)
        End Select
    Loop
End Function

The code above does use a few helper functions, but the above is the meat of it.

The strategy used here is to employ a recursive tokenizer. I found it interesting enough to write an article about this solution on Medium. It explains the details.

Here is the full (yet surprisingly short) code listing, including all of the helper functions:

'-------------------------------------------------------------------
' VBA JSON Parser
'-------------------------------------------------------------------
Option Explicit
Private p&, token, dic
Function ParseJSON(json$, Optional key$ = "obj") As Object
    p = 1
    token = Tokenize(json)
    Set dic = CreateObject("Scripting.Dictionary")
    If token(p) = "{" Then ParseObj key Else ParseArr key
    Set ParseJSON = dic
End Function
Function ParseObj(key$)
    Do: p = p + 1
        Select Case token(p)
            Case "]"
            Case "[":  ParseArr key
            Case "{"
                       If token(p + 1) = "}" Then
                           p = p + 1
                           dic.Add key, "null"
                       Else
                           ParseObj key
                       End If
            
            Case "}":  key = ReducePath(key): Exit Do
            Case ":":  key = key & "." & token(p - 1)
            Case ",":  key = ReducePath(key)
            Case Else: If token(p + 1) <> ":" Then dic.Add key, token(p)
        End Select
    Loop
End Function
Function ParseArr(key$)
    Dim e&
    Do: p = p + 1
        Select Case token(p)
            Case "}"
            Case "{":  ParseObj key & ArrayID(e)
            Case "[":  ParseArr key
            Case "]":  Exit Do
            Case ":":  key = key & ArrayID(e)
            Case ",":  e = e + 1
            Case Else: dic.Add key & ArrayID(e), token(p)
        End Select
    Loop
End Function
'-------------------------------------------------------------------
' Support Functions
'-------------------------------------------------------------------
Function Tokenize(s$)
    Const Pattern = """(([^""\\]|\\.)*)""|[+\-]?(?:0|[1-9]\d*)(?:\.\d*)?(?:[eE][+\-]?\d+)?|\w+|[^\s""']+?"
    Tokenize = RExtract(s, Pattern, True)
End Function
Function RExtract(s$, Pattern, Optional bGroup1Bias As Boolean, Optional bGlobal As Boolean = True)
  Dim c&, m, n, v
  With CreateObject("vbscript.regexp")
    .Global = bGlobal
    .MultiLine = False
    .IgnoreCase = True
    .Pattern = Pattern
    If .TEST(s) Then
      Set m = .Execute(s)
      ReDim v(1 To m.Count)
      For Each n In m
        c = c + 1
        v(c) = n.value
        If bGroup1Bias Then If Len(n.submatches(0)) Or n.value = """""" Then v(c) = n.submatches(0)
      Next
    End If
  End With
  RExtract = v
End Function
Function ArrayID$(e)
    ArrayID = "(" & e & ")"
End Function
Function ReducePath$(key$)
    If InStr(key, ".") Then ReducePath = Left(key, InStrRev(key, ".") - 1)
End Function
Function ListPaths(dic)
    Dim s$, v
    For Each v In dic
        s = s & v & " --> " & dic(v) & vbLf
    Next
    Debug.Print s
End Function
Function GetFilteredValues(dic, match)
    Dim c&, i&, v, w
    v = dic.keys
    ReDim w(1 To dic.Count)
    For i = 0 To UBound(v)
        If v(i) Like match Then
            c = c + 1
            w(c) = dic(v(i))
        End If
    Next
    ReDim Preserve w(1 To c)
    GetFilteredValues = w
End Function
Function GetFilteredTable(dic, cols)
    Dim c&, i&, j&, v, w, z
    v = dic.keys
    z = GetFilteredValues(dic, cols(0))
    ReDim w(1 To UBound(z), 1 To UBound(cols) + 1)
    For j = 1 To UBound(cols) + 1
         z = GetFilteredValues(dic, cols(j - 1))
         For i = 1 To UBound(z)
            w(i, j) = z(i)
         Next
    Next
    GetFilteredTable = w
End Function
Function OpenTextFile$(f)
    With CreateObject("ADODB.Stream")
        .Charset = "utf-8"
        .Open
        .LoadFromFile f
        OpenTextFile = .ReadText
    End With
End Function

How to center an element horizontally and vertically

_x000D_
_x000D_ 
    .align {_x000D_
        display: flex;_x000D_
        width: 400px;_x000D_
        height: 400px;_x000D_
        border: solid 1px black;_x000D_
        align-items: center;_x000D_
        justify-content: space-around;_x000D_
    }_x000D_
    .align div:first-child {_x000D_
        width: 20px;_x000D_
        height: 20px;_x000D_
        background-color: red;_x000D_
        position: absolute; _x000D_
    }_x000D_
    .align div {_x000D_
        width: 20px;_x000D_
        height: 20px;_x000D_
        background-color: blue;_x000D_
    }
_x000D_ 
    <div class='align'>_x000D_
        <div></div>_x000D_
        <div></div>_x000D_
        <div></div>_x000D_
        <div></div>_x000D_
        <div></div>_x000D_
        <div></div>_x000D_
    </div>
_x000D_
_x000D_
_x000D_

First child will be aligned vertically and horizontally at center

How can I enable MySQL's slow query log without restarting MySQL?

If you want to enable general error logs and slow query error log in the table instead of file

To start logging in table instead of file:

set global log_output = “TABLE”;

To enable general and slow query log:

set global general_log = 1;
set global slow_query_log = 1;

To view the logs:

select * from mysql.slow_log;
select * from mysql.general_log;

For more details visit this link

http://easysolutionweb.com/technology/mysql-server-logs/

How I can print to stderr in C?

To print your context ,you can write code like this :

FILE *fp;
char *of;
sprintf(of,"%s%s",text1,text2);
fp=fopen(of,'w');
fprintf(fp,"your print line");

Array or List in Java. Which is faster?

Depending on the implementation. it's possible that an array of primitive types will be smaller and more efficient than ArrayList. This is because the array will store the values directly in a contiguous block of memory, while the simplest ArrayList implementation will store pointers to each value. On a 64-bit platform especially, this can make a huge difference.

Of course, it's possible for the jvm implementation to have a special case for this situation, in which case the performance will be the same.

PHP DOMDocument loadHTML not encoding UTF-8 correctly

The only thing that worked for me was the accepted answer of

$profile = '<p>???????????????????????9</p>';
$dom = new DOMDocument();
$dom->loadHTML('<?xml encoding="utf-8" ?>' . $profile);
echo $dom->saveHTML();

HOWEVER

This brought about new issues, of having <?xml encoding="utf-8" ?> in the output of the document.

The solution for me was then to do

foreach ($doc->childNodes as $xx) {
    if ($xx instanceof \DOMProcessingInstruction) {
        $xx->parentNode->removeChild($xx);
    }
}

Some solutions told me that to remove the xml header, that I had to perform

$dom->saveXML($dom->documentElement);

This didn't work for me as for a partial document (e.g. a doc with two <p> tags), only one of the <p> tags where being returned.

Prevent jQuery UI dialog from setting focus to first textbox

This is really important for smartphones and tablets because the keyboard comes up when an input has the focus. This is what I've done, add this input at the beginning of the div:

<input type="image" width="1px" height="1px"/>

Doesn't work with size 0px. I guess it's even better with a real transparent image, either .png or .gif but I haven't tried.

Working fine so far in iPad.

How to read file with async/await properly?

There is a fs.readFileSync( path, options ) method, which is synchronous.

DateTime.TryParse issue with dates of yyyy-dd-MM format

Try using safe TryParseExact method

DateTime temp;
string   date = "2011-29-01 12:00 am";

DateTime.TryParseExact(date, "yyyy-dd-MM hh:mm tt", CultureInfo.InvariantCulture, DateTimeStyles.None, out temp);

Python extract pattern matches

You could use something like this:

import re
s = #that big string
# the parenthesis create a group with what was matched
# and '\w' matches only alphanumeric charactes
p = re.compile("name +(\w+) +is valid", re.flags)
# use search(), so the match doesn't have to happen 
# at the beginning of "big string"
m = p.search(s)
# search() returns a Match object with information about what was matched
if m:
    name = m.group(1)
else:
    raise Exception('name not found')

Android SDK location

If you only installed Xamarin with Visual Studio setup, the android SDK location is :

C:\Program Files (x86)\Android\android-sdk

You can find it in Android SDK Manager as said Raj Asapu

In visual Studio : Android SDK Manger from Visual Studio

Note : you should not use Program Files path to install Android Studio due to the space in path ! Android studio setup after Xamarin

Where does Internet Explorer store saved passwords?

No guarantee, but I suspect IE uses the older Protected Storage API.

twig: IF with multiple conditions

If I recall correctly Twig doesn't support || and && operators, but requires or and and to be used respectively. I'd also use parentheses to denote the two statements more clearly although this isn't technically a requirement.

{%if ( fields | length > 0 ) or ( trans_fields | length > 0 ) %}

Expressions

Expressions can be used in {% blocks %} and ${ expressions }.

Operator    Description
==          Does the left expression equal the right expression?
+           Convert both arguments into a number and add them.
-           Convert both arguments into a number and substract them.
*           Convert both arguments into a number and multiply them.
/           Convert both arguments into a number and divide them.
%           Convert both arguments into a number and calculate the rest of the integer division.
~           Convert both arguments into a string and concatenate them.
or          True if the left or the right expression is true.
and         True if the left and the right expression is true.
not         Negate the expression.

For more complex operations, it may be best to wrap individual expressions in parentheses to avoid confusion:

{% if (foo and bar) or (fizz and (foo + bar == 3)) %}

How to correctly close a feature branch in Mercurial?

It is strange, that no one yet has suggested the most robust way of closing a feature branches... You can just combine merge commit with --close-branch flag (i.e. commit modified files and close the branch simultaneously):

hg up feature-x
hg merge default
hg ci -m "Merge feature-x and close branch" --close-branch
hg branch default -f

So, that is all. No one extra head on revgraph. No extra commit.

Crop image in PHP

imagecopyresampled() will take a rectangular area from $src_image of width $src_w and height $src_h at position ($src_x, $src_y) and place it in a rectangular area of $dst_image of width $dst_w and height $dst_h at position ($dst_x, $dst_y).

If the source and destination coordinates and width and heights differ, appropriate stretching or shrinking of the image fragment will be performed. The coordinates refer to the upper left corner.

This function can be used to copy regions within the same image. But if the regions overlap, the results will be unpredictable.

- Edit -

If $src_w and $src_h are smaller than $dst_w and $dst_h respectively, thumb image will be zoomed in. Otherwise it will be zoomed out.

<?php
$dst_x = 0;   // X-coordinate of destination point
$dst_y = 0;   // Y-coordinate of destination point
$src_x = 100; // Crop Start X position in original image
$src_y = 100; // Crop Srart Y position in original image
$dst_w = 160; // Thumb width
$dst_h = 120; // Thumb height
$src_w = 260; // Crop end X position in original image
$src_h = 220; // Crop end Y position in original image

// Creating an image with true colors having thumb dimensions (to merge with the original image)
$dst_image = imagecreatetruecolor($dst_w, $dst_h);
// Get original image
$src_image = imagecreatefromjpeg('images/source.jpg');
// Cropping
imagecopyresampled($dst_image, $src_image, $dst_x, $dst_y, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h);
// Saving
imagejpeg($dst_image, 'images/crop.jpg');
?>

Why do I need to configure the SQL dialect of a data source?

Databases implement subtle differences in the SQL they use. Things such as data types for example vary across databases (e.g. in Oracle You might put an integer value in a number field and in SQL Server use an int field). Or database specific functionality - selecting the top n rows is different depending on the database. The dialect abstracts this so you don't have to worry about it.

What does "for" attribute do in HTML <label> tag?

The for attribute shows that this label stands for related input field, or check box or radio button or any other data entering field associated with it. for example

<li>
    <label>{translate:blindcopy}</label>
    <a class="" href="#" title="{translate:savetemplate}" onclick="" ><i class="fa fa-list" class="button" ></i></a> &nbsp 
            <input type="text" id="BlindCopy" name="BlindCopy" class="splitblindcopy" />

</li>

COUNT DISTINCT with CONDITIONS

Try the following statement:

select  distinct A.[Tag],
     count(A.[Tag]) as TAG_COUNT,
     (SELECT count(*) FROM [TagTbl] AS B WHERE A.[Tag]=B.[Tag] AND B.[ID]>0)
     from [TagTbl] AS A GROUP BY A.[Tag]

The first field will be the tag the second will be the whole count the third will be the positive ones count.

Unable to create migrations after upgrading to ASP.NET Core 2.0

In my case, the cause of the problem was multiple startup projects. I have three projects in my solution: Mvc, Api, and Dal. DbContext and Migrations in the Dal project.

I had configured multiple startup projects. Both Mvc and Api projects were running when I clicked Start. But in this case I was getting this error.

"Unable to create an object of type 'MyContext'. Add an implementation of 'IDesignTimeDbContextFactory' to the project, or see https://go.microsoft.com/fwlink/?linkid=851728 for additional patterns supported at design time."

I could successfully add migration after setting Mvc as the only startup project and selecting Dal in the Package Manager Console.

How do I link a JavaScript file to a HTML file?

First you need to download JQuery library from http://jquery.com/ then load the jquery library the following way within your html head tags

then you can test whether the jquery is working by coding your jquery code after the jquery loading script

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>

<!--LINK JQUERY-->
<script type="text/javascript" src="jquery-3.3.1.js"></script>
<!--PERSONAL SCRIPT JavaScript-->
<script type="text/javascript">
   $(function(){
      alert("My First Jquery Test");
   });
</script>

</head>
<body><!-- Your web--></body>
</html>

If you want to use your jquery scripts file seperately you must define the external .js file this way after the jquery library loading.

<script type="text/javascript" src="jquery-3.3.1.js"></script>
<script src="js/YourExternalJQueryScripts.js"></script>

Test in real time

_x000D_
_x000D_ 
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>_x000D_
<!DOCTYPE html>_x000D_
<html xmlns="http://www.w3.org/1999/xhtml">_x000D_
<head>_x000D_
_x000D_
<!--LINK JQUERY-->_x000D_
<script type="text/javascript" src="jquery-3.3.1.js"></script>_x000D_
<!--PERSONAL SCRIPT JavaScript-->_x000D_
<script type="text/javascript">_x000D_
   $(function(){_x000D_
      alert("My First Jquery Test");_x000D_
   });_x000D_
</script>_x000D_
_x000D_
</head>_x000D_
<body><!-- Your web--></body>_x000D_
</html>
_x000D_
_x000D_
_x000D_

Removing element from array in component state

I believe referencing this.state inside of setState() is discouraged (State Updates May Be Asynchronous).

The docs recommend using setState() with a callback function so that prevState is passed in at runtime when the update occurs. So this is how it would look:

Using Array.prototype.filter without ES6

removeItem : function(index) {
  this.setState(function(prevState){
    return { data : prevState.data.filter(function(val, i) {
      return i !== index;
    })};
  });
}

Using Array.prototype.filter with ES6 Arrow Functions

removeItem(index) {
  this.setState((prevState) => ({
    data: prevState.data.filter((_, i) => i !== index)
  }));
}

Using immutability-helper

import update from 'immutability-helper'
...
removeItem(index) {
  this.setState((prevState) => ({
    data: update(prevState.data, {$splice: [[index, 1]]})
  }))
}

Using Spread

function removeItem(index) {
  this.setState((prevState) => ({
    data: [...prevState.data.slice(0,index), ...prevState.data.slice(index+1)]
  }))
}

Note that in each instance, regardless of the technique used, this.setState() is passed a callback, not an object reference to the old this.state;

How to save user input into a variable in html and js

It doesn't work because name is a reserved word in JavaScript. Change the function name to something else.

See http://www.quackit.com/javascript/javascript_reserved_words.cfm

<form id="form" onsubmit="return false;">
    <input style="position:absolute; top:80%; left:5%; width:40%;" type="text" id="userInput" />
    <input style="position:absolute; top:50%; left:5%; width:40%;" type="submit" onclick="othername();" />
</form>

function othername() {
    var input = document.getElementById("userInput").value;
    alert(input);
}

CSS rounded corners in IE8

Internet Explorer (under version 9) does not natively support rounded corners.

There's an amazing script that will magically add it for you: CSS3 PIE.

I've used it a lot of times, with amazing results.

How to dump a dict to a json file?

If you're using Path:

example_path = Path('/tmp/test.json')
example_dict = {'x': 24, 'y': 25}
json_str = json.dumps(example_dict, indent=4) + '\n'
example_path.write_text(json_str, encoding='utf-8')

React navigation goBack() and update parent state

For those who don't want to manage via props, try this. It will call everytime when this page appear.

Note* (this is not only for goBack but it will call every-time you enter this page.)

import { NavigationEvents } from 'react-navigation';

render() {
    return (
        <View style={{ flex: 1 }}>
            <NavigationEvents
              onWillFocus={() => {
                // Do your things here
              }}
            />
        </View>
    );
}

IO Error: The Network Adapter could not establish the connection

Just try to re-create connection. In my situation one of jdbc connection stopped working for no reason. From console sqlplus was working ok. It took me 2 hours to realize that If i create the same connection - it works.

Relative imports for the billionth time

__name__ changes depending on whether the code in question is run in the global namespace or as part of an imported module.

If the code is not running in the global space, __name__ will be the name of the module. If it is running in global namespace -- for example, if you type it into a console, or run the module as a script using python.exe yourscriptnamehere.py then __name__ becomes "__main__".

You'll see a lot of python code with if __name__ == '__main__' is used to test whether the code is being run from the global namespace – that allows you to have a module that doubles as a script.

Did you try to do these imports from the console?