Programs & Examples On #Dllexport

__declspec(dllexport) is a C and C++ compiler directive, which automates exporting of functions or variables when creating a DLL (Dynamic-link library).

DLL Load Library - Error Code 126

This error can happen because some MFC library (eg. mfc120.dll) from which the DLL is dependent is missing in windows/system32 folder.

what does "error : a nonstatic member reference must be relative to a specific object" mean?

Only static functions are called with class name.


Non static functions have to be called using objects.

classname obj;

This is exactly what your error means. Since your function is non static you have to use a object reference to invoke it.

Compile a DLL in C/C++, then call it from another program

Regarding building a DLL using MinGW, here are some very brief instructions.

First, you need to mark your functions for export, so they can be used by callers of the DLL. To do this, modify them so they look like (for example)

__declspec( dllexport ) int add2(int num){
   return num + 2;

then, assuming your functions are in a file called funcs.c, you can compile them:

gcc -shared -o mylib.dll funcs.c

The -shared flag tells gcc to create a DLL.

To check if the DLL has actually exported the functions, get hold of the free Dependency Walker tool and use it to examine the DLL.

For a free IDE which will automate all the flags etc. needed to build DLLs, take a look at the excellent Code::Blocks, which works very well with MinGW.

Edit: For more details on this subject, see the article Creating a MinGW DLL for Use with Visual Basic on the MinGW Wiki.

Exporting functions from a DLL with dllexport

I had exactly the same problem, my solution was to use module definition file (.def) instead of __declspec(dllexport) to define exports( I have no idea why this works, but it does

How to execute only one test spec with angular-cli

This is working for me in Angular 7. It is based on the --main option of the ng command. I am not sure if this option is undocumented and possibly subject to change, but it works for me. I put a line in my package.json file in scripts section. There using the --main option of with the ng test command, I specify the path to the .spec.ts file I want to execute. For example

"test 1": "ng test --main E:/WebRxAngularClient/src/app/test/shared/my-date-utils.spec.ts",

You can run the script as you run any such script. I run it in Webstorm by clicking on "test 1" in the npm section.

How to convert JSON to CSV format and store in a variable

Here's my simple version of converting an array of objects ito CSV (assuming those objects all share the same attributes):

var csv = []
if (items.length) {
  var keys = Object.keys(items[0])
  items.forEach(item => {
    let vals = => item[key] || '')

csv = csv.join('\n') 

php_network_getaddresses: getaddrinfo failed: Name or service not known

in simple word your site has been blocked to access network. may be you have automated some script and it caused your whole website to be blocked. the better way to resolve this is contact that site and tell your issue. if issue is genuine they may consider unblocking

Import Libraries in Eclipse?

No, don't do it that way.

From your Eclipse workspace, right click your project on the left pane -> Properties -> Java Build Path -> Add Jars -> add your jars here.

Tadaa!! :)

count of entries in data frame in R

You could use table:

R> x <- read.table(textConnection('
   Believe Age Gender Presents Behaviour
1    FALSE   9   male       25   naughty
2     TRUE   5   male       20      nice
3     TRUE   4 female       30      nice
4     TRUE   4   male       34   naughty'
), header=TRUE)

R> table(x$Believe)

    1     3 

Handling Enter Key in Vue.js

This event works to me:


How can building a heap be O(n) time complexity?

In case of building the heap, we start from height, logn -1 (where logn is the height of tree of n elements). For each element present at height 'h', we go at max upto (logn -h) height down.

    So total number of traversal would be:-
    T(n) = sigma((2^(logn-h))*h) where h varies from 1 to logn
    T(n) = n((1/2)+(2/4)+(3/8)+.....+(logn/(2^logn)))
    T(n) = n*(sigma(x/(2^x))) where x varies from 1 to logn
     and according to the [sources][1]
    function in the bracket approaches to 2 at infinity.
    Hence T(n) ~ O(n)

error: (-215) !empty() in function detectMultiScale

I ran the same code. There are two things to note here. 1. Give the entire path of the .xml files. 2. Give a key press event instruction at the end.

Add this block of code at the end and run your file, worked for me:

k = cv2.waitKey(0)
if k == 27:         # wait for ESC key to exit
elif k == ord('s'): # wait for 's' key to save and exit

For example, my code looked like

import numpy as np
import cv2

face_cascade = cv2.CascadeClassifier('C:\\opencv\\build\\etc\\haarcascades\\haarcascade_frontalface_default.xml')
eye_cascade = cv2.CascadeClassifier('C:\\opencv\\build\\etc\\haarcascades\\haarcascade_eye.xml')

img = cv2.imread('lena.jpg')

gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

faces = face_cascade.detectMultiScale(gray, 1.3, 5)
#faces = face_cascade.detectMultiScale(gray)

for (x,y,w,h) in faces:
    roi_gray = gray[y:y+h, x:x+w]
    roi_color = img[y:y+h, x:x+w]
    eyes = eye_cascade.detectMultiScale(roi_gray)
    for (ex,ey,ew,eh) in eyes:


k = cv2.waitKey(0)
if k == 27:         # wait for ESC key to exit
elif k == ord('s'): # wait for 's' key to save and exit

My output looked like this:


How to increase the clickable area of a <a> tag button?

add padding to the CSS class of anchor tag. If required, add padding-top, padding-bottom,... individually according to the clickable area you want. It worked for me.

How do I set default values for functions parameters in Matlab?

I am confused nobody has pointed out this blog post by Loren, one of Matlab's developers. The approach is based on varargin and avoids all those endless and painfull if-then-else or switch cases with convoluted conditions. When there are a few default values, the effect is dramatic. Here's an example from the linked blog:

function y = somefun2Alt(a,b,varargin)
% Some function that requires 2 inputs and has some optional inputs.

% only want 3 optional inputs at most
numvarargs = length(varargin);
if numvarargs > 3
    error('myfuns:somefun2Alt:TooManyInputs', ...
        'requires at most 3 optional inputs');

% set defaults for optional inputs
optargs = {eps 17 @magic};

% now put these defaults into the valuesToUse cell array, 
% and overwrite the ones specified in varargin.
optargs(1:numvarargs) = varargin;
% or ...
% [optargs{1:numvarargs}] = varargin{:};

% Place optional args in memorable variable names
[tol, mynum, func] = optargs{:};

If you still don't get it, then try reading the entire blog post by Loren. I have written a follow up blog post which deals with missing positional default values. I mean that you could write something like:

somefun2Alt(a, b, '', 42)

and still have the default eps value for the tol parameter (and @magic callback for func of course). Loren's code allows this with a slight but tricky modification.

Finally, just a few advantages of this approach:

  1. Even with a lot of defaults the boilerplate code doesn't get huge (as opposed to the family of if-then-else approaches, which get longer with each new default value)
  2. All the defaults are in one place. If any of those need to change, you have just one place to look at.

Trooth be told, there is a disadvantage too. When you type the function in Matlab shell and forget its parameters, you will see an unhelpful varargin as a hint. To deal with that, you're advised to write a meaningful usage clause.

How can I execute a PHP function in a form action?

It's better something like the data to the self page and maybe do a check on user input.

    require_once ( 'username.php' );

    if(isset($_POST)) {
      echo "form post"; // ex $_POST['textfield']

    echo '
    <form name="form1" method="post" action="' . $_SERVER['PHP_SELF'] . '">
          <input type="text" name="textfield" id="textfield">
          <input type="submit" name="button" id="button" value="Submit">

A keyboard shortcut to comment/uncomment the select text in Android Studio

Windows 10 and Android Studio: Ctrl + / (on small num pad), don't use Ctrl + Shift-7!

Is there a way to make mv create the directory to be moved to if it doesn't exist?

It sounds like the answer is no :). I don't really want to create an alias or func just to do this, often because it's one-off and I'm already in the middle of typing the mv command, but I found something that works well for that:

mv *.sh  shell_files/also_with_subdir/ || mkdir -p $_

If mv fails (dir does not exist), it will make the directory (which is the last argument to the previous command, so $_ has it). So just run this command, then up to re-run it, and this time mv should succeed. using a form to insert data into an sql server table

Simple, make a simple asp page with the designer (just for the beginning) Lets say the body is something like this:

    <form id="form1" runat="server">
        <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
        <br />
        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <asp:Button ID="Button1" runat="server" Text="Button" />

Great, now every asp object IS an object. So you can access it in the asp's CS code. The asp's CS code is triggered by events (mostly). The class will probably inherit from System.Web.UI.Page

If you go to the cs file of the asp page, you'll see a protected void Page_Load(object sender, EventArgs e) ... That's the load event, you can use that to populate data into your objects when the page loads.

Now, go to the button in your designer (Button1) and look at its properties, you can design it, or add events from there. Just change to the events view, and create a method for the event.

The button is a web control Button Add a Click event to the button call it Button1Click:

void Button1Click(Object sender,EventArgs e) { }

Now when you click the button, this method will be called. Because ASP is object oriented, you can think of the page as the actual class, and the objects will hold the actual current data.

So if for example you want to access the text in TextBox1 you just need to call that object in the C# code:

String firstBox = TextBox1.Text;

In the same way you can populate the objects when event occur.

Now that you have the data the user posted in the textboxes , you can use regular C# SQL connections to add the data to your database.

python location on mac osx

This one will solve all your problems not only for Mac but works on every basic shell -> Linux also:

If you have a Mac and you've installed python3 like most of us do :) (with brew install - ofc)

your file is located in:


How do you know? -> you can run this on every basic shell Run:

which python3

You should get:


Now this is a symbolic link, how do you know? Run:

ls -al /usr/local/bin/python3 

and you'll get:

/usr/local/bin/python3 -> /usr/local/Cellar/python/3.6.4_4/bin/python3

which means that your


is actually pointing to:


If, for some reason, your


is not pointing to the place you want, which in our case:


just backup it:

cp /usr/local/bin/python3{,.orig} 

and run:

rm -rf /usr/local/bin/python3

now create a new symbolic link:

ln -s /usr/local/Cellar/python/3.6.4_4/bin/python3 /usr/local/bin/python3 

and now your


is pointing to


Check it out by running:

ls -al /usr/local/bin/python3

generate days from date range

Shorter than accepted answer, same idea:

(SELECT TRIM('2016-01-05' + INTERVAL a + b DAY) date
WHERE '2016-01-05' + INTERVAL a + b DAY  <=  '2016-01-21')

The mysql extension is deprecated and will be removed in the future: use mysqli or PDO instead

  1. Why is this happening?

    The entire ext/mysql PHP extension, which provides all functions named with the prefix mysql_, was officially deprecated in PHP v5.5.0 and removed in PHP v7.

    It was originally introduced in PHP v2.0 (November 1997) for MySQL v3.20, and no new features have been added since 2006. Coupled with the lack of new features are difficulties in maintaining such old code amidst complex security vulnerabilities.

    The manual has contained warnings against its use in new code since June 2011.

  2. How can I fix it?

    As the error message suggests, there are two other MySQL extensions that you can consider: MySQLi and PDO_MySQL, either of which can be used instead of ext/mysql. Both have been in PHP core since v5.0, so if you're using a version that is throwing these deprecation errors then you can almost certainly just start using them right away—i.e. without any installation effort.

    They differ slightly, but offer a number of advantages over the old extension including API support for transactions, stored procedures and prepared statements (thereby providing the best way to defeat SQL injection attacks). PHP developer Ulf Wendel has written a thorough comparison of the features. has an excellent tutorial on migrating from ext/mysql to PDO.

  3. I understand that it's possible to suppress deprecation errors by setting error_reporting in php.ini to exclude E_DEPRECATED:

    error_reporting = E_ALL ^ E_DEPRECATED

    What will happen if I do that?

    Yes, it is possible to suppress such error messages and continue using the old ext/mysql extension for the time being. But you really shouldn't do this—this is a final warning from the developers that the extension may not be bundled with future versions of PHP (indeed, as already mentioned, it has been removed from PHP v7). Instead, you should take this opportunity to migrate your application now, before it's too late.

    Note also that this technique will suppress all E_DEPRECATED messages, not just those to do with the ext/mysql extension: therefore you may be unaware of other upcoming changes to PHP that would affect your application code. It is, of course, possible to only suppress errors that arise on the expression at issue by using PHP's error control operator—i.e. prepending the relevant line with @—however this will suppress all errors raised by that expression, not just E_DEPRECATED ones.

What should you do?

  • You are starting a new project.

    There is absolutely no reason to use ext/mysql—choose one of the other, more modern, extensions instead and reap the rewards of the benefits they offer.

  • You have (your own) legacy codebase that currently depends upon ext/mysql.

    It would be wise to perform regression testing: you really shouldn't be changing anything (especially upgrading PHP) until you have identified all of the potential areas of impact, planned around each of them and then thoroughly tested your solution in a staging environment.

    • Following good coding practice, your application was developed in a loosely integrated/modular fashion and the database access methods are all self-contained in one place that can easily be swapped out for one of the new extensions.

      Spend half an hour rewriting this module to use one of the other, more modern, extensions; test thoroughly. You can later introduce further refinements to reap the rewards of the benefits they offer.

    • The database access methods are scattered all over the place and cannot easily be swapped out for one of the new extensions.

      Consider whether you really need to upgrade to PHP v5.5 at this time.

      You should begin planning to replace ext/mysql with one of the other, more modern, extensions in order that you can reap the rewards of the benefits they offer; you might also use it as an opportunity to refactor your database access methods into a more modular structure.

      However, if you have an urgent need to upgrade PHP right away, you might consider suppressing deprecation errors for the time being: but first be sure to identify any other deprecation errors that are also being thrown.

  • You are using a third party project that depends upon ext/mysql.

    Consider whether you really need to upgrade to PHP v5.5 at this time.

    Check whether the developer has released any fixes, workarounds or guidance in relation to this specific issue; or, if not, pressure them to do so by bringing this matter to their attention. If you have an urgent need to upgrade PHP right away, you might consider suppressing deprecation errors for the time being: but first be sure to identify any other deprecation errors that are also being thrown.

    It is absolutely essential to perform regression testing.

What's sizeof(size_t) on 32-bit vs the various 64-bit data models?

size_t is defined by the C standard to be the unsigned integer return type of the sizeof operator (C99, and the argument of malloc and friends (C99 etc). The actual range is set such that the maximum (SIZE_MAX) is at least 65535 (C99

However, this doesn't let us determine sizeof(size_t). The implementation is free to use any representation it likes for size_t - so there is no upper bound on size - and the implementation is also free to define a byte as 16-bits, in which case size_t can be equivalent to unsigned char.

Putting that aside, however, in general you'll have 32-bit size_t on 32-bit programs, and 64-bit on 64-bit programs, regardless of the data model. Generally the data model only affects static data; for example, in GCC:

     Generate code for the small code model: the program and its
     symbols must be linked in the lower 2 GB of the address space.
     Pointers are 64 bits.  Programs can be statically or dynamically
     linked.  This is the default code model.

     Generate code for the kernel code model.  The kernel runs in the
     negative 2 GB of the address space.  This model has to be used for
     Linux kernel code.

     Generate code for the medium model: The program is linked in the
     lower 2 GB of the address space but symbols can be located
     anywhere in the address space.  Programs can be statically or
     dynamically linked, but building of shared libraries are not
     supported with the medium model.

     Generate code for the large model: This model makes no assumptions
     about addresses and sizes of sections.

You'll note that pointers are 64-bit in all cases; and there's little point to having 64-bit pointers but not 64-bit sizes, after all.

iPhone UILabel text soft shadow

I tried almost all of these techniques (except FXLabel) and couldn't get any of them to work with iOS 7. I did eventually find THLabel which is working perfectly for me. I used THLabel in Interface Builder and setup User Defined Runtime Attributes so that it's easy for a non programmer to control the look and feel.

How to create the most compact mapping n ? isprime(n) up to a limit N?

myInp=int(input("Enter a number: "))
if myInp==1:
    print("The number {} is neither a prime not composite no".format(myInp))
elif myInp>1:
    for i in range(2,myInp//2+1):
        if myInp%i==0:
            print("The Number {} is not a prime no".format(myInp))
        print("The Number {} is a prime no".format(myInp))
    print("Alas the no {} is a not a prime no".format(myInp))

How can I solve a connection pool problem between ASP.NET and SQL Server?

You have leaked connections on your code. You may try to use using to certify that you're closing them.

using (SqlConnection sqlconnection1 = new SqlConnection(“Server=.\\SQLEXPRESS ;Integrated security=sspi;connection timeout=5”)) 
    SqlCommand sqlcommand1 = sqlconnection1.CreateCommand();
    sqlcommand1.CommandText = “raiserror (‘This is a fake exception’, 17,1)”;
    sqlcommand1.ExecuteNonQuery();  //this throws a SqlException every time it is called.
    sqlconnection1.Close(); //Still never gets called.
} // Here sqlconnection1.Dispose is _guaranteed_

Append to string variable

var str1 = "add";
str1 = str1 + " ";

Hope that helps,


Prevent flex items from stretching

You don't want to stretch the span in height?
You have the possiblity to affect one or more flex-items to don't stretch the full height of the container.

To affect all flex-items of the container, choose this:
You have to set align-items: flex-start; to div and all flex-items of this container get the height of their content.

div {_x000D_
  align-items: flex-start;_x000D_
  background: tan;_x000D_
  display: flex;_x000D_
  height: 200px;_x000D_
span {_x000D_
  background: red;_x000D_
  <span>This is some text.</span>_x000D_

To affect only a single flex-item, choose this:
If you want to unstretch a single flex-item on the container, you have to set align-self: flex-start; to this flex-item. All other flex-items of the container aren't affected.

div {_x000D_
  display: flex;_x000D_
  height: 200px;_x000D_
  background: tan;_x000D_
span.only {_x000D_
  background: red;_x000D_
span {_x000D_
  <span class="only">This is some text.</span>_x000D_
  <span>This is more text.</span>_x000D_

Why is this happening to the span?
The default value of the property align-items is stretch. This is the reason why the span fill the height of the div.

Difference between baseline and flex-start?
If you have some text on the flex-items, with different font-sizes, you can use the baseline of the first line to place the flex-item vertically. A flex-item with a smaller font-size have some space between the container and itself at top. With flex-start the flex-item will be set to the top of the container (without space).

div {_x000D_
  align-items: baseline;_x000D_
  background: tan;_x000D_
  display: flex;_x000D_
  height: 200px;_x000D_
span {_x000D_
  background: red;_x000D_
span.fontsize {_x000D_
  <span class="fontsize">This is some text.</span>_x000D_
  <span>This is more text.</span>_x000D_

You can find more information about the difference between baseline and flex-start here:
What's the difference between flex-start and baseline?

Google maps API V3 method fitBounds()

 var map = new google.maps.Map(document.getElementById("map"),{
                mapTypeId: google.maps.MapTypeId.ROADMAP

var bounds = new google.maps.LatLngBounds();

for (i = 0; i < locations.length; i++){
        marker = new google.maps.Marker({
            position: new google.maps.LatLng(locations[i][1], locations[i][2]),
            map: map

XAMPP - MySQL shutdown unexpectedly

Guys just make sure you dont have MySql Server installed. Because I have MySql server pre-installed and when I start mysql from xampp control panel some port conflicts are happening and its not working.. SO before starting the mysql from xampp control panel make sure mysql server is not installed. I use .net so I have installed mysql server in the Past. Uninstalling it solved my Problem....

Rails 3 execute custom sql query without a model

Maybe try this:


Can the Android drawable directory contain subdirectories?

I like to use a simple script to flatten an organized directory structure provided by designers to something that can be used to generate an R file.

Run with current path in drawable-hdpi:

#! /bin/bash
DIRS=`find * -type d`
for dir in ${DIRS} ; do 
  for file in `ls ${dir}` ; do
    mv ${dir}/${file}  ${dir}_${file};
  rmdir ${dir};

Copying text outside of Vim with set mouse=a enabled

In Ubuntu, it is possible to use the X-Term copy & paste bindings inside VIM (Ctrl-Shift-C & Ctrl-Shift-V) on text that has been hilighted using the Shift key.

Why compile Python code?

There's certainly a performance difference when running a compiled script. If you run normal .py scripts, the machine compiles it every time it is run and this takes time. On modern machines this is hardly noticeable but as the script grows it may become more of an issue.

How to change the plot line color from blue to black?

If you get the object after creation (for instance after "seasonal_decompose"), you can always access and edit the properties of the plot; for instance, changing the color of the first subplot from blue to black:


When is it appropriate to use UDP instead of TCP?

I'm a bit reluctant to suggest UDP when TCP could possibly work. The problem is that if TCP isn't working for some reason, because the connection is too laggy or congested, changing the application to use UDP is unlikely to help. A bad connection is bad for UDP too. TCP already does a very good job of minimizing congestion.

The only case I can think of where UDP is required is for broadcast protocols. In cases where an application involves two, known hosts, UDP will likely only offer marginal performance benefits for substantially increased costs of code complexity.

cmake - find_library - custom library location

Use CMAKE_PREFIX_PATH by adding multiple paths (separated by semicolons and no white spaces). You can set it as an environmental variable to avoid having absolute paths in your cmake configuration files

Notice that cmake will look for config file in any of the following folders where is any of the path in CMAKE_PREFIX_PATH and name is the name of the library you are looking for

<prefix>/                                               (W)
<prefix>/(cmake|CMake)/                                 (W)
<prefix>/<name>*/                                       (W)
<prefix>/<name>*/(cmake|CMake)/                         (W)
<prefix>/(lib/<arch>|lib|share)/cmake/<name>*/          (U)
<prefix>/(lib/<arch>|lib|share)/<name>*/                (U)
<prefix>/(lib/<arch>|lib|share)/<name>*/(cmake|CMake)/  (U)

In your case you need to add to CMAKE_PREFIX_PATH the following two paths:


C++ undefined reference to defined function

Though previous posters covered your particular error, you can get 'Undefined reference' linker errors when attempting to compile C code with g++, if you don't tell the compiler to use C linkage.

For example you should do this in your C header files:

extern "C" {


void myfunc(int param);



To make 'myfunc' available in C++ programs.

If you still also want to use this from C, wrap the extern "C" { and } in #ifdef __cplusplus preprocessor conditionals, like

#ifdef __cplusplus
extern "C" {

This way, the extern block will just be “skipped” when using a C compiler.

Getting file size in Python?



It should return the size of a file, reported by os.stat().

Select the top N values by group

There are at least 4 ways to do this thing, however,each has some difference. We using u_id to group and using lift value to order/sort

1 dplyr traditional way

top10_final_subset1 = final_subset %>% arrange(desc(lift)) %>% group_by(u_id) %>% slice(1:10)

and if you switch the order of arrange(desc(lift)) and group_by(u_id) the result is essential the same.And if there is tie for equal lift value,it will slice to make sure each group has no more than 10 values, if you only have 5 lift value in the group, it will only gives you 5 results for that group.

2 dplyr topN way

top10_final_subset2 = final_subset %>% group_by(u_id) %>% top_n(10,lift)

this one if you have tie in lift value, say 15 same lift for the same u_id, you will got all 15 observations

3 data.table tail way

final_subset = data.table(final_subset,key = "lift")
top10_final_subset3 = final_subset[,tail(.SD,10),,by = c("u_id")]

It has the same row numbers as the first way, however, there are some rows are different, I guess they are using diff random algorithm dealing with tie.

4 data.table .SD way

top10_final_subset4 = final_subset[,.SD[order(lift,decreasing = TRUE),][1:10],by = "u_id"]

This way is the most "uniform" way,if in a group there are only 5 observation it will repeat value to make it to 10 observations and if there are ties it will still slice and only hold for 10 observations.

Git keeps prompting me for a password

I feel like the answer provided by static_rtti is hacky in some sense. I don't know if this was available earlier, but Git tools now provide credential storage.

Cache Mode

$ git config --global credential.helper cache

Use the “cache” mode to keep credentials in memory for a certain period of time. None of the passwords are ever stored on disk, and they are purged from the cache after 15 minutes.

Store Mode

$ git config --global credential.helper 'store --file ~/.my-credentials'

Use the “store” mode to save the credentials to a plain-text file on disk, and they never expire.

I personally used the store mode. I deleted my repository, cloned it, and then had to enter my credentials once.

Reference: 7.14 Git Tools - Credential Storage

Format date to MM/dd/yyyy in JavaScript

Try this; bear in mind that JavaScript months are 0-indexed, whilst days are 1-indexed.

var date = new Date('2010-10-11T00:00:00+05:30');_x000D_
    alert(((date.getMonth() > 8) ? (date.getMonth() + 1) : ('0' + (date.getMonth() + 1))) + '/' + ((date.getDate() > 9) ? date.getDate() : ('0' + date.getDate())) + '/' + date.getFullYear());

Running Java Program from Command Line Linux

Guys let's understand the syntax of it.

  1. If class file is present in the Current Dir.

    java -cp . fileName

  2. If class file is present within the Dir. Go to the Parent Dir and enter below cmd.

    java -cp . dir1.dir2.dir3.fileName

  3. If there is a dependency on external jars then,

    java -cp .:./jarName1:./jarName2 fileName

    Hope this helps.

Updating a date in Oracle SQL table

This is based on the assumption that you're getting an error about the date format, such as an invalid month value or non-numeric character when numeric expected.

Dates stored in the database do not have formats. When you query the date your client is formatting the date for display, as 4/16/2011. Normally the same date format is used for selecting and updating dates, but in this case they appear to be different - so your client is apparently doing something more complicated that SQL*Plus, for example.

When you try to update it it's using a default date format model. Because of how it's displayed you're assuming that is MM/DD/YYYY, but it seems not to be. You could find out what it is, but it's better not to rely on the default or any implicit format models at all.

Whether that is the problem or not, you should always specify the date model:


Since you aren't specifying a time component - all Oracle DATE columns include a time, even if it's midnight - you could also use a date literal:


You should maybe check that the current value doesn't include a time, though the column name suggests it doesn't.

jquery .live('click') vs .click()

As 'live' will handle events for future elements that match the current selector, you may choose click as you don't want that to happen - you only want to handle the current selected elements.

Also, I suspect (though have no evidence) that there is a slight efficiency using 'click' over 'live'.


How to pull remote branch from somebody else's repo

GitHub has a new option relative to the preceding answers, just copy/paste the command lines from the PR:

  1. Scroll to the bottom of the PR to see the Merge or Squash and merge button
  2. Click the link on the right: view command line instructions
  3. Press the Copy icon to the right of Step 1
  4. Paste the commands in your terminal

Create database from command line

As some of the answers point out, createdb is a command line utility that could be used to create database.

Assuming you have a user named dbuser, the following command could be used to create a database and provide access to dbuser:

createdb -h localhost -p 5432 -U dbuser testdb

Replace localhost with your correct DB host name, 5432 with correct DB port, and testdb with the database name you want to create.

Now psql could be used to connect to this newly created database:

psql -h localhost -p 5432 -U dbuser -d testdb

Tested with createdb and psql versions 9.4.15.

Accessing MP3 metadata with Python

Just additional information to you guys:

take a look at the section "MP3 stuff and Metadata editors" in the page of PythonInMusic.

How to unpack and pack pkg file?

Here is a bash script inspired by abarnert's answer which will unpack a package named MyPackage.pkg into a subfolder named MyPackage_pkg and then open the folder in Finder.

    #!/usr/bin/env bash
    pkgutil --expand "$filename" "$dirname"
    cd "$dirname"
    tar xvf Payload
    open .

Usage: MyPackage.pkg

Warning: This will not work in all cases, and will fail with certain files, e.g. the PKGs inside the OSX system installer. If you want to peek inside the pkg file and see what's inside, you can try SuspiciousPackage (free app), and if you need more options such as selectively unpacking specific files, then have a look at Pacifist (nagware).

Configuring diff tool with .gitconfig

If you want to have an option to use multiple diff tools add an alias to .gitconfig

    kdiff = difftool --tool kdiff3

How are booleans formatted in Strings in Python?

>>> print "%r, %r" % (True, False)
True, False

This is not specific to boolean values - %r calls the __repr__ method on the argument. %s (for str) should also work.

Windows CMD command for accessing usb?

Try this batch :

@echo off
Title List of connected external devices by Hackoo
Mode con cols=100 lines=20 & Color 9E
wmic LOGICALDISK where driveType=2 get deviceID > wmic.txt
for /f "skip=1" %%b IN ('type wmic.txt') DO (echo %%b & pause & Dir %%b)
Del wmic.txt

sed: print only matching group

The cut command is designed for this exact situation. It will "cut" on any delimiter and then you can specify which chunks should be output.

For instance: echo "foo bar <foo> bla 1 2 3.4" | cut -d " " -f 6-7

Will result in output of: 2 3.4

-d sets the delimiter

-f selects the range of 'fields' to output, in this case, it's the 6th through 7th chunks of the original string. You can also specify the range as a list, such as 6,7.

Powershell Get-ChildItem most recent file in directory

You could try to sort descending "sort LastWriteTime -Descending" and then "select -first 1." Not sure which one is faster

jquery : focus to div is not working

you can use the below code to bring focus to a div, in this example the page scrolls to the <div id="navigation">

$('html, body').animate({ scrollTop: $('#navigation').offset().top }, 'slow');

How to import multiple csv files in a single load?

Reader's Digest: (Spark 2.x)

For Example, if you have 3 directories holding csv files:

dir1, dir2, dir3

You then define paths as a string of comma delimited list of paths as follows:

paths = "dir1/,dir2/,dir3/*"

Then use the following function and pass it this paths variable

def get_df_from_csv_paths(paths):

        df ="csv").option("header", "false").\
            option('delimiter', '\t').\
            option('mode', 'DROPMALFORMED').\
        return df

By then running:

df = get_df_from_csv_paths(paths)

You will obtain in df a single spark dataframe containing the data from all the csvs found in these 3 directories.


Full Version:

In case you want to ingest multiple CSVs from multiple directories you simply need to pass a list and use wildcards.

For Example:

if your data_path looks like this:

s3://bucket_name/subbucket_name/2016-12-*/184/*, ... '

you can use the above function to ingest all the csvs in all these directories and subdirectories at once:

This would ingest all directories in s3 bucket_name/subbucket_name/ according to the wildcard patterns specified. e.g. the first pattern would look in


for all directories with names starting with


and for each of those take only the directory named


and within that subdirectory look for all csv files.

And this would be executed for each of the patterns in the comma delimited list.

This works way better than union..

Convert List<String> to List<Integer> directly

If you use Google Guava library this is what you can do, see Lists#transform

    String s = "AttributeGet:1,16,10106,10111";

    List<Integer> attributeIDGet = new ArrayList<Integer>();

    if(s.contains("AttributeGet:")) {
        List<String> attributeIDGetS = Arrays.asList(s.split(":")[1].split(","));
        attributeIDGet =
        Lists.transform(attributeIDGetS, new Function<String, Integer>() {
            public Integer apply(String e) {
                return Integer.parseInt(e);

Yep, agree with above answer that's it's bloated, but stylish. But it's just another way.

difference between iframe, embed and object elements


The iframe element represents a nested browsing context. HTML 5 standard - "The <iframe> element"

Primarily used to include resources from other domains or subdomains but can be used to include content from the same domain as well. The <iframe>'s strength is that the embedded code is 'live' and can communicate with the parent document.


Standardised in HTML 5, before that it was a non standard tag, which admittedly was implemented by all major browsers. Behaviour prior to HTML 5 can vary ...

The embed element provides an integration point for an external (typically non-HTML) application or interactive content. (HTML 5 standard - "The <embed> element")

Used to embed content for browser plugins. Exceptions to this is SVG and HTML that are handled differently according to the standard.

The details of what can and can not be done with the embedded content is up to the browser plugin in question. But for SVG you can access the embedded SVG document from the parent with something like:

svg = document.getElementById("parent_id").getSVGDocument();

From inside an embedded SVG or HTML document you can reach the parent with:

parent = window.parent.document;

For embedded HTML there is no way to get at the embedded document from the parent (that I have found).


The <object> element can represent an external resource, which, depending on the type of the resource, will either be treated as an image, as a nested browsing context, or as an external resource to be processed by a plugin. (HTML 5 standard - "The <object> element")


Unless you are embedding SVG or something static you are probably best of using <iframe>. To include SVG use <embed> (if I remember correctly <object> won't let you script†). Honestly I don't know why you would use <object> unless for older browsers or flash (that I don't work with).

† As pointed out in the comments below; scripts in <object> will run but the parent and child contexts can't communicate directly. With <embed> you can get the context of the child from the parent and vice versa. This means they you can use scripts in the parent to manipulate the child etc. That part is not possible with <object> or <iframe> where you would have to set up some other mechanism instead, such as the JavaScript postMessage API.

How can I create 2 separate log files with one log4j config file?

Modify your file accordingly:


Change the log levels for each logger depending to your needs.

Angular 2: 404 error occur when I refresh through the browser

Perhaps you can do it while registering your root with RouterModule. You can pass a second object with property useHash:true like the below:

import { NgModule }       from '@angular/core';
import { BrowserModule  } from '@angular/platform-browser';
import { AppComponent }   from './app.component';
import { ROUTES }   from './app.routes';

    declarations: [AppComponent],
    imports: [BrowserModule],
    RouterModule.forRoot(ROUTES ,{ useHash: true }),],
    providers: [],
    bootstrap: [AppComponent],
export class AppModule {}

Why is it OK to return a 'vector' from a function?

Pre C++11:

The function will not return the local variable, but rather a copy of it. Your compiler might however perform an optimization where no actual copy action is made.

See this question & answer for further details.


The function will move the value. See this answer for further details.

How do you create a read-only user in PostgreSQL?

I’ve created a convenient script for that; This script grants read-only privileges to a specified role on all tables, views and sequences in a database schema and sets them as default.

Passing additional variables from command line to make

Say you have a makefile like this:

    echo argument is $(argument)

You would then call it make action argument=something

How to detect Safari, Chrome, IE, Firefox and Opera browser?

Here is my customized solution.

        const inBrowser = typeof window !== 'undefined'
        const UA = inBrowser && window.navigator.userAgent.toLowerCase()
        const isIE =
          UA && /; msie|trident/i.test(UA) && !/ucbrowser/i.test(UA).test(UA)
        const isEdge = UA && /edg/i.test(UA)
        const isAndroid = UA && UA.indexOf('android') > 0
        const isIOS = UA && /iphone|ipad|ipod|ios/i.test(UA)
        const isChrome =
          UA &&
          /chrome|crios/i.test(UA) &&
        const isGoogleBot = UA && /googlebot/i.test(UA)
        const isChromium = UA && /chromium/i.test(UA)
        const isUcBrowser = UA && /ucbrowser/i.test(UA)
        const isSafari =
          UA &&
          /safari/i.test(UA) &&
        const isFirefox = UA && /firefox|fxios/i.test(UA) && !/seamonkey/i.test(UA)
        const isOpera = UA && /opr|opera/i.test(UA)
        const isMobile =
          /\b(BlackBerry|webOS|iPhone|IEMobile)\b/i.test(UA) ||
          /\b(Android|Windows Phone|iPad|iPod)\b/i.test(UA)
        const isSamsung = UA && /samsungbrowser/i.test(UA)
        const isIPad = UA && /ipad/.test(UA)
        const isIPhone = UA && /iphone/.test(UA)
        const isIPod = UA && /ipod/.test(UA)

Assigning the output of a command to a variable

You can use a $ sign like:


android: changing option menu items programmatically

You can do something simple like I did. Just change the text to what is needed when the menu item is touched. I needed to turn the sound off and on, plus the ability to perform an action by touching it. Here is my code:

public boolean onOptionsItemSelected(MenuItem item) {

    switch (item.getItemId()) {
        audioOn = !audioOn;
        if (audioOn)
            item.setTitle("Audio Off");
            item.setTitle("Audio On");
        return true;

        touchOn = !touchOn;
        if (touchOn)
            item.setTitle("Touch Off");
            item.setTitle("Touch On");
        return true;
        return super.onOptionsItemSelected(item);

audioOn and touchOn are booleans checked in other parts of the code. Hope this helps.

How to copy text programmatically in my Android app?

For Kotlin use the below code inside the activity.

import android.content.ClipboardManager

 val clipBoard = getSystemService(Context.CLIPBOARD_SERVICE) as ClipboardManager
 val clipData = ClipData.newPlainText("label","Message to be Copied")

python paramiko ssh

There is something wrong with the accepted answer, it sometimes (randomly) brings a clipped response from server. I do not know why, I did not investigate the faulty cause of the accepted answer because this code worked perfectly for me:

import paramiko

ip='server ip'

cmd='some useful command' 



stdin,stdout,stderr=ssh.exec_command('some really useful command')

Fastest way to get the first object from a queryset in django?

This could work as well:

def get_first_element(MyModel):
    my_query = MyModel.objects.all()
    return my_query[:1]

if it's empty, then returns an empty list, otherwise it returns the first element inside a list.

Kill detached screen session

add this to your ~/.bashrc:

alias cleanscreen="screen -ls | tail -n +2 | head -n -2 | awk '{print $1}'| xargs -I{} screen -S {} -X quit"

Then use cleanscreen to clean all screen session.

Hiding the scroll bar on an HTML page

I think I found a workaround for you guys if you're still interested. This is my first week, but it worked for me...

<div class="contentScroller">
    <div class="content">

.contentScroller {overflow-y: auto; visibility: hidden;}
.content {visibility: visible;}

Maximum number of rows of CSV data in excel sheet

CSV files have no limit of rows you can add to them. Excel won't hold more that the 1 million lines of data if you import a CSV file having more lines.

Excel will actually ask you whether you want to proceed when importing more than 1 million data rows. It suggests to import the remaining data by using the text import wizard again - you will need to set the appropriate line offset.

nvm keeps "forgetting" node in new terminal session

nvm does its job by changing the PATH variable, so you need to make sure you aren't somehow changing your PATH to something else after sourcing the script.

In my case, was being called in .bashrc but then the PATH variable was getting updated in .bash_profile which caused my session to find the system node before the nvm node.

jQuery UI dialog positioning

I've tried all the proposed solutions but they won't work because the dialog is not part of the main document and will has its own layer (but thats my educated guess).

  1. Initialize the dialog with $("#dialog").dialog("option", "position", 'top')
  2. Open it with $(dialog).dialog("open");
  3. Then get the x and y of the displayed dialog (not any other node of the document!)

    var xcoord = $(dialog).position().left + ADD_MODIFIER_FOR_X_HERE;

    var ycoord= $(dialog).position().top + ADD_MODIFIER_FOR_Y_HERE;

    $(dialog).dialog('option', 'position', [xcoord , ycoord]);

This way the coordinates are from the dialog not from the document and the position is altered according to the layer of the dialog.

E11000 duplicate key error index in mongodb mongoose

This is because there is already a collection with the same name with configuration..Just remove the collection from your mongodb through mongo shell and try again.


now run your application it should work

C error: undefined reference to function, but it IS defined

I think the problem is that when you're trying to compile testpoint.c, it includes point.h but it doesn't know about point.c. Since point.c has the definition for create, not having point.c will cause the compilation to fail.

I'm not familiar with MinGW, but you need to tell the compiler to look for point.c. For example with gcc you might do this:

gcc point.c testpoint.c

As others have pointed out, you also need to remove one of your main functions, since you can only have one.

Two Page Login with Spring Security 3.2.x

There should be three pages here:

  1. Initial login page with a form that asks for your username, but not your password.
  2. You didn't mention this one, but I'd check whether the client computer is recognized, and if not, then challenge the user with either a CAPTCHA or else a security question. Otherwise the phishing site can simply use the tendered username to query the real site for the security image, which defeats the purpose of having a security image. (A security question is probably better here since with a CAPTCHA the attacker could have humans sitting there answering the CAPTCHAs to get at the security images. Depends how paranoid you want to be.)
  3. A page after that that displays the security image and asks for the password.

I don't see this short, linear flow being sufficiently complex to warrant using Spring Web Flow.

I would just use straight Spring Web MVC for steps 1 and 2. I wouldn't use Spring Security for the initial login form, because Spring Security's login form expects a password and a login processing URL. Similarly, Spring Security doesn't provide special support for CAPTCHAs or security questions, so you can just use Spring Web MVC once again.

You can handle step 3 using Spring Security, since now you have a username and a password. The form login page should display the security image, and it should include the user-provided username as a hidden form field to make Spring Security happy when the user submits the login form. The only way to get to step 3 is to have a successful POST submission on step 1 (and 2 if applicable).

Converting string to double in C#

In your string I see: 15.5859949000000662452.23862099999999 which is not a double (it has two decimal points). Perhaps it's just a legitimate input error?

You may also want to figure out if your last String will be empty, and account for that situation.

Java Runtime.getRuntime(): getting output from executing a command line program

Pretty much the same as other snippets on this page but just organizing things up over an function, here we go...

String str=shell_exec("ls -l");

The Class function:

public String shell_exec(String cmd)
       String o=null;
         Process p=Runtime.getRuntime().exec(cmd);
         BufferedReader b=new BufferedReader(new InputStreamReader(p.getInputStream()));
         String r;
         }catch(Exception e){o="error";}
       return o;

How to set an image's width and height without stretching it?

What I can think of is to stretch either width or height and let it resize in ratio-aspect. There will be some white space on the sides. Something like how a Wide screen displays a resolution of 1024x768.

How to show imageView full screen on imageView click?

That didn't work for me, I used some code parts from web, what I did:

new activity: FullScreenImage with:

package yourpackagename;
import yourpackagename.R;

import android.annotation.SuppressLint;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

public class FullScreenImage  extends Activity {


public void onCreate(Bundle savedInstanceState) {


    Bundle extras = getIntent().getExtras();
    Bitmap bmp = (Bitmap) extras.getParcelable("imagebitmap");

    ImageView imgDisplay;
    Button btnClose;

    imgDisplay = (ImageView) findViewById(;
    btnClose = (Button) findViewById(;

   btnClose.setOnClickListener(new View.OnClickListener() {            
    public void onClick(View v) {

 imgDisplay.setImageBitmap(bmp );



Then create a xml: layout_full

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android=""
android:layout_height="match_parent" >

    android:scaleType="fitCenter" />

    android:text="Close" />


And finally, send the image name from your mainactivity

   final ImageView im = (ImageView)findViewById( ; 

   im.setOnClickListener(new OnClickListener() {

       public void onClick(View view) {
       Intent intent = new Intent(NAMEOFYOURCURRENTACTIVITY.this, FullScreenImage.class);

       Bitmap image= im.getDrawingCache();

       Bundle extras = new Bundle();
       extras.putParcelable("imagebitmap", image);


Subtracting 2 lists in Python

This answer shows how to write "normal/easily understandable" pythonic code.

I suggest not using zip as not really everyone knows about it.

The solutions use list comprehensions and common built-in functions.

Alternative 1 (Recommended):

a = [2, 2, 2]
b = [1, 1, 1]
result = [a[i] - b[i] for i in range(len(a))]

Recommended as it only uses the most basic functions in Python

Alternative 2:

a = [2, 2, 2]
b = [1, 1, 1]
result = [x - b[i] for i, x in enumerate(a)]

Alternative 3 (as mentioned by BioCoder):

a = [2, 2, 2]
b = [1, 1, 1]
result = list(map(lambda x, y: x - y, a, b))

What is the difference between <p> and <div>?

A p tag is for a paragraph, generally used for text. A div tag is for division, and generally used for creating sections of text.

Can anyone explain IEnumerable and IEnumerator to me?

IEnumerable and IEnumerator both are interfaces in C#.

IEnumerable is an interface defining a single method GetEnumerator() that returns an IEnumerator interface.

This works for read-only access to a collection that implements that IEnumerable can be used with a foreach statement.

IEnumerator has two methods, MoveNext and Reset. It also has a property called Current.

The following shows the implementation of IEnumerable and IEnumerator.

How do I loop through children objects in javascript?

In the year 2020 / 2021 it is even easier with Array.from to 'convert' from a array-like nodes to an actual array, and then using .map to loop through the resulting array. The code is as simple as the follows:


Spring: Why do we autowire the interface and not the implemented class?

How does spring know which polymorphic type to use.

As long as there is only a single implementation of the interface and that implementation is annotated with @Component with Spring's component scan enabled, Spring framework can find out the (interface, implementation) pair. If component scan is not enabled, then you have to define the bean explicitly in your application-config.xml (or equivalent spring configuration file).

Do I need @Qualifier or @Resource?

Once you have more than one implementation, then you need to qualify each of them and during auto-wiring, you would need to use the @Qualifier annotation to inject the right implementation, along with @Autowired annotation. If you are using @Resource (J2EE semantics), then you should specify the bean name using the name attribute of this annotation.

Why do we autowire the interface and not the implemented class?

Firstly, it is always a good practice to code to interfaces in general. Secondly, in case of spring, you can inject any implementation at runtime. A typical use case is to inject mock implementation during testing stage.

interface IA
  public void someFunction();

class B implements IA
  public void someFunction()
    //busy code block
  public void someBfunc()
     //doing b things

class C implements IA
  public void someFunction()
    //busy code block
  public void someCfunc()
     //doing C things

class MyRunner
     IA worker;


Your bean configuration should look like this:

<bean id="b" class="B" />
<bean id="c" class="C" />
<bean id="runner" class="MyRunner" />

Alternatively, if you enabled component scan on the package where these are present, then you should qualify each class with @Component as follows:

interface IA
  public void someFunction();

class B implements IA
  public void someFunction()
    //busy code block
  public void someBfunc()
     //doing b things

class C implements IA
  public void someFunction()
    //busy code block
  public void someCfunc()
     //doing C things

class MyRunner
     IA worker;


Then worker in MyRunner will be injected with an instance of type B.

catch forEach last iteration

Updated answer for ES6+ is here.

arr = [1, 2, 3]; 

arr.forEach(function(i, idx, array){
   if (idx === array.length - 1){ 
       console.log("Last callback call at index " + idx + " with value " + i ); 

would output:

Last callback call at index 2 with value 3

The way this works is testing arr.length against the current index of the array, passed to the callback function.

How do I use setsockopt(SO_REUSEADDR)?

Depending on the libc release it could be needed to set both SO_REUSEADDR and SO_REUSEPORT socket options as explained in socket(7) documentation :

   SO_REUSEPORT (since Linux 3.9)
          Permits multiple AF_INET or AF_INET6 sockets to be bound to an
          identical socket address.  This option must be set on each
          socket (including the first socket) prior to calling bind(2)
          on the socket.  To prevent port hijacking, all of the
          processes binding to the same address must have the same
          effective UID.  This option can be employed with both TCP and
          UDP sockets.

As this socket option appears with kernel 3.9 and raspberry use 3.12.x, it will be needed to set SO_REUSEPORT.

You can set theses two options before calling bind like this :

    int reuse = 1;
    if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (const char*)&reuse, sizeof(reuse)) < 0)
        perror("setsockopt(SO_REUSEADDR) failed");

    if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEPORT, (const char*)&reuse, sizeof(reuse)) < 0) 
        perror("setsockopt(SO_REUSEPORT) failed");

How to use the COLLATE in a JOIN in SQL Server?

Correct syntax looks like this. See MSDN.

  FROM [FAEB].[dbo].[ExportaComisiones] AS f
  JOIN [zCredifiel].[dbo].[optPerson] AS p

  ON p.vTreasuryId COLLATE Latin1_General_CI_AS = f.RFC COLLATE Latin1_General_CI_AS 

Installing Bootstrap 3 on Rails App

As many know, there is no need for a gem.

Steps to take:

  1. Download Bootstrap
  2. Copy


    to: app/assets/stylesheets

  3. Copy


    to: app/assets/javascripts

  4. Append to: app/assets/stylesheets/application.css

    *= require bootstrap

  5. Append to: app/assets/javascripts/application.js

    //= require bootstrap

That is all. You are ready to add a new cool Bootstrap template.

Why app/ instead of vendor/?

It is important to add the files to app/assets, so in the future you'll be able to overwrite Bootstrap styles.

If later you want to add a custom.css.scss file with custom styles. You'll have something similar to this in application.css:

 *= require bootstrap                                                            
 *= require custom  

If you placed the bootstrap files in app/assets, everything works as expected. But, if you placed them in vendor/assets, the Bootstrap files will be loaded last. Like this:

<link href="/assets/custom.css?body=1" media="screen" rel="stylesheet">
<link href="/assets/bootstrap.css?body=1" media="screen" rel="stylesheet">

So, some of your customizations won't be used as the Bootstrap styles will override them.

Reason behind this

Rails will search for assets in many locations; to get a list of this locations you can do this:

$ rails console
> Rails.application.config.assets.paths

In the output you'll see that app/assets takes precedence, thus loading it first.

grid controls for ASP.NET MVC?

We have been using jqGrid on a project and have had some good luck with it. Lots of options for inline editing, etc. If that stuff isn't necessary, then we've just used a plain foreach loop like @Hrvoje.

How to determine if a point is in a 2D triangle?

One of the easiest ways to check if the area formed by the vertices of triangle (x1,y1),(x2,y2),(x3,y3) is positive or not.

Area can by calculated by the formula:

1/2 [x1(y2–y3) + x2(y3–y1) + x3(y1–y2)]

or python code can be written as:

def triangleornot(p1,p2,p3):
    return (1/ 2) [p1[0](p2[1]–p3[1]) + p2[0] (p3[1]–p1[1]) + p3[0] (p1[0]–p2[0])]

How can I mix LaTeX in with Markdown?

Sorry to rouse a really old thread, but I've been using jemdoc for a couple of years and it is really excellent.

Convert URL to File or Blob for FileReader.readAsDataURL

I know this is an expansion off of @tibor-udvari's answer, but for a nicer copy and paste.

async function createFile(url, type){
  if (typeof window === 'undefined') return // make sure we are in the browser
  const response = await fetch(url)
  const data = await response.blob()
  const metadata = {
    type: type || 'video/quicktime'
  return new File([data], url, metadata)

Java OCR implementation

There are a variety of OCR libraries out there. However, my experience is that the major commercial implementations, ABBYY, Omnipage, and ReadIris, far outdo the open-source or other minor implementations. These commercial libraries are not primarily designed to work with Java, though of course it is possible.

Of course, if your interest is to learn the code, the open-source implementations will do the trick.

Kotlin - Property initialization using "by lazy" vs. "lateinit"

In addition to all of the great answers, there is a concept called lazy loading:

Lazy loading is a design pattern commonly used in computer programming to defer initialization of an object until the point at which it is needed.

Using it properly, you can reduce the loading time of your application. And Kotlin way of it's implementation is by lazy() which loads the needed value to your variable whenever it's needed.

But lateinit is used when you are sure a variable won't be null or empty and will be initialized before you use it -e.g. in onResume() method for android- and so you don't want to declare it as a nullable type.

What are the differences between WCF and ASMX web services?

ASMX Web services can only be invoked by HTTP (traditional webservice with .asmx). While WCF Service or a WCF component can be invoked by any protocol (like http, tcp etc.) and any transport type.

Second, ASMX web services are not flexible. However, WCF Services are flexible. If you make a new version of the service then you need to just expose a new end. Therefore, services are agile and which is a very practical approach looking at the current business trends.

We develop WCF as contracts, interface, operations, and data contracts. As the developer we are more focused on the business logic services and need not worry about channel stack. WCF is a unified programming API for any kind of services so we create the service and use configuration information to set up the communication mechanism like HTTP/TCP/MSMQ etc

Subtract days from a DateTime

Using AddDays(-1) worked for me until I tried to cross months. When I tried to subtract 2 days from 2017-01-01 the result was 2016-00-30. It could not handle the month change correctly (though the year seemed to be fine).

I used date = Convert.ToDateTime(date).Subtract(TimeSpan.FromDays(2)).ToString("yyyy-mm-dd"); and have no issues.

Multiple "order by" in LINQ

Using non-lambda, query-syntax LINQ, you can do this:

var movies = from row in _db.Movies 
             orderby row.Category, row.Name
             select row;

[EDIT to address comment] To control the sort order, use the keywords ascending (which is the default and therefore not particularly useful) or descending, like so:

var movies = from row in _db.Movies 
             orderby row.Category descending, row.Name
             select row;

How to transform currentTimeMillis to a readable date format?

There is a simpler way in Android


Moreover, Date is deprecated, so use DateFormat class.

   DateFormat.getDateInstance().format(new Date(0));  
   DateFormat.getDateTimeInstance().format(new Date(0));  
   DateFormat.getTimeInstance().format(new Date(0));  

The above three lines will give:

Dec 31, 1969  
Dec 31, 1969 4:00:00 PM  
4:00:00 PM  12:00:00 AM

Wait until an HTML5 video loads

In response to the final part of your question, which is still unanswered... When you write $('#video').duration, you're asking for the duration property of the jQuery collection object, which doesn't exist. The native DOM video element does have the duration. You can get that in a few ways.

Here's one:

// get the native element directly

Here's another:

// get it out of the jQuery object

And another:

// use the event object
v.bind('loadeddata', function(e) {

Parse JSON String to JSON Object in C#.NET

Another choice besides JObject is System.Json.JsonValue for Weak-Typed JSON object.

It also has a JsonValue blob = JsonValue.Parse(json); you can use. The blob will most likely be of type JsonObject which is derived from JsonValue, but could be JsonArray. Check the blob.JsonType if you need to know.

And to answer you question, YES, you may replace json with the name of your actual variable that holds the JSON string. ;-D

There is a System.Json.dll you should add to your project References.


MongoDB distinct aggregation

SQL Query: (group by & count of distinct)

select city,count(distinct(emailId)) from TransactionDetails group by city;

Equivalent mongo query would look like this:

{$group:{_id:{"CITY" : "$cityName"},uniqueCount: {$addToSet: "$emailId"}}},
{$project:{"CITY":1,uniqueCustomerCount:{$size:"$uniqueCount"}} } 

How to install ADB driver for any android device?

If no other driver package worked for your obscure device go read how to make a truly universal abd and fastboot driver out of Google's USB driver. The trick is to use CompatibleID instead of HardwareID in the driver's INF Models section

How to change color in markdown cells ipython/jupyter notebook?

You can simply use raw html tags like

foo <font color='red'>bar</font> foo

Be aware that this will not survive a conversion of the notebook to latex.

As there are some complaints about the deprecation of the proposed solution. They are totally valid and Scott has already answered the question with a more recent, i.e. CSS based approach. Nevertheless, this answer shows some general approach to use html tags within IPython to style markdown cell content beyond the available pure markdown capabilities.

How to call Oracle MD5 hash function?

To calculate MD5 hash of CLOB content field with my desired encoding without implicitly recoding content to AL32UTF8, I've used this code:

create or replace function clob2blob(AClob CLOB) return BLOB is
  Result BLOB;
  o1 integer;
  o2 integer;
  c integer;
  w integer;
  o1 := 1;
  o2 := 1;
  c := 0;
  w := 0;
  DBMS_LOB.CreateTemporary(Result, true);
  DBMS_LOB.ConvertToBlob(Result, AClob, length(AClob), o1, o2, 0, c, w);
end clob2blob;

update my_table t set t.hash = (rawtohex(DBMS_CRYPTO.Hash(clob2blob(t.content),2)));

Getting a list of values from a list of dicts

A very simple way to do it is:

for i in com_list:
    if j==0:


['apple', 'banana', 'cars']

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

If you have a mixture of formats in your date, don't forget to set infer_datetime_format=True to make life easier.

df['date'] = pd.to_datetime(df['date'], infer_datetime_format=True)

Source: pd.to_datetime

or if you want a customized approach:

def autoconvert_datetime(value):
    formats = ['%m/%d/%Y', '%m-%d-%y']  # formats to try
    result_format = '%d-%m-%Y'  # output format
    for dt_format in formats:
            dt_obj = datetime.strptime(value, dt_format)
            return dt_obj.strftime(result_format)
        except Exception as e:  # throws exception when format doesn't match
    return value  # let it be if it doesn't match

df['date'] = df['date'].apply(autoconvert_datetime)

PHP append one array to another (not array_push or +)

For big array, is better to concatenate without array_merge, for avoid a memory copy.

$array1 = array_fill(0,50000,'aa');
$array2 = array_fill(0,100,'bb');

// Test 1 (array_merge)
$start = microtime(true);
$r1 = array_merge($array1, $array2);
echo sprintf("Test 1: %.06f\n", microtime(true) - $start);

// Test2 (avoid copy)
$start = microtime(true);
foreach ($array2 as $v) {
    $array1[] = $v;
echo sprintf("Test 2: %.06f\n", microtime(true) - $start);

// Test 1: 0.004963
// Test 2: 0.000038

JPA EntityManager: Why use persist() over merge()?

Going through the answers there are some details missing regarding `Cascade' and id generation. See question

Also, it is worth mentioning that you can have separate Cascade annotations for merging and persisting: Cascade.MERGE and Cascade.PERSIST which will be treated according to the used method.

The spec is your friend ;)

'pip install' fails for every package ("Could not find a version that satisfies the requirement")

Upgrade pip as follows:

curl | python

Note: You may need to use sudo python above if not in a virtual environment.

What's happening: sites are stopping support for TLS versions 1.0 and 1.1. This means that Mac OS X version 10.12 (Sierra) or older will not be able to use pip unless they upgrade pip as above.

(Note that upgrading pip via pip install --upgrade pip will also not upgrade it correctly. It is a chicken-and-egg issue)

This thread explains it (thanks to this Twitter post):

Mac users who use pip and PyPI:

If you are running macOS/OS X version 10.12 or older, then you ought to upgrade to the latest pip (9.0.3) to connect to the Python Package Index securely:

curl | python

and we recommend you do that by April 8th.

Pip 9.0.3 supports TLSv1.2 when running under system Python on macOS < 10.13. Official release notes:

Also, the Python status page:

Completed - The rolling brownouts are finished, and TLSv1.0 and TLSv1.1 have been disabled. Apr 11, 15:37 UTC

Update - The rolling brownouts have been upgraded to a blackout, TLSv1.0 and TLSv1.1 will be rejected with a HTTP 403 at all times. Apr 8, 15:49 UTC

Lastly, to avoid other install errors, make sure you also upgrade setuptools after doing the above:

pip install --upgrade setuptools

How to make Scrollable Table with fixed headers using CSS

I can think of a cheeky way to do it, I don't think this will be the best option but it will work.

Create the header as a separate table then place the other in a div and set a max size, then allow the scroll to come in by using overflow.

table {_x000D_
  width: 500px;_x000D_
.scroll {_x000D_
  max-height: 60px;_x000D_
  overflow: auto;_x000D_
<table border="1">_x000D_
<div class="scroll">_x000D_
    <tr><td>Text Text</td><td>Text Text</td><td>Text Text</td><td>Text Text</td></tr>_x000D_
    <tr><td>Text Text</td><td>Text Text</td><td>Text Text</td><td>Text Text</td></tr>_x000D_
    <tr><td>Text Text</td><td>Text Text</td><td>Text Text</td><td>Text Text</td></tr>_x000D_
    <tr><td>Text Text</td><td>Text Text</td><td>Text Text</td><td>Text Text</td></tr>_x000D_
    <tr><td>Text Text</td><td>Text Text</td><td>Text Text</td><td>Text Text</td></tr>_x000D_
    <tr><td>Text Text</td><td>Text Text</td><td>Text Text</td><td>Text Text</td></tr>_x000D_
    <tr><td>More Text</td><td>More Text</td><td>More Text</td><td>More Text</td></tr>_x000D_
    <tr><td>Text Text</td><td>Text Text</td><td>Text Text</td><td>Text Text</td></tr>_x000D_
    <tr><td>Even More Text Text</td><td>Even More Text Text</td><td>Even More Text Text</td><td>Even More Text Text</td></tr>_x000D_

Download file of any type in Asp.Net MVC using FileResult?

its simple just give your physical path in directoryPath with file name

public FilePathResult GetFileFromDisk(string fileName)
    return File(directoryPath, "multipart/form-data", fileName);

Read response headers from API response - Angular 5 + TypeScript

You can get data from post response Headers in this way (Angular 6):

import { HttpClient, HttpHeaders, HttpResponse } from '@angular/common/http';

const httpOptions = {
  headers: new HttpHeaders({ 'Content-Type': 'application/json' }),
  observe: 'response' as 'response'
};,body,httpOptions).subscribe((res: HttpResponse<any>) => {

How do I select and store columns greater than a number in pandas?

Sample DF:

In [79]: df = pd.DataFrame(np.random.randint(5, 15, (10, 3)), columns=list('abc'))

In [80]: df
    a   b   c
0   6  11  11
1  14   7   8
2  13   5  11
3  13   7  11
4  13   5   9
5   5  11   9
6   9   8   6
7   5  11  10
8   8  10  14
9   7  14  13

present only those rows where b > 10

In [81]: df[df.b > 10]
   a   b   c
0  6  11  11
5  5  11   9
7  5  11  10
9  7  14  13

Minimums (for all columns) for the rows satisfying b > 10 condition

In [82]: df[df.b > 10].min()
a     5
b    11
c     9
dtype: int32

Minimum (for the b column) for the rows satisfying b > 10 condition

In [84]: df.loc[df.b > 10, 'b'].min()
Out[84]: 11

UPDATE: starting from Pandas 0.20.1 the .ix indexer is deprecated, in favor of the more strict .iloc and .loc indexers.

How to remove numbers from string using Regex.Replace?

Try the following:

var output = Regex.Replace(input, @"[\d-]", string.Empty);

The \d identifier simply matches any digit character.

Characters allowed in a URL

I tested it by requesting my website (apache) with all available chars on my german keyboard as URL parameter:^1234567890ß´qwertzuiopü+asdfghjklöä#<yxcvbnm,.-°!"§$%&/()=? `QWERTZUIOPÜ*ASDFGHJKLÖÄ\'>YXCVBNM;:_²³{[]}\|µ@€~

These were not encoded:


Not encoded after urlencode():


Not encoded after rawurlencode():


Note: Before PHP 5.3.0 rawurlencode() encoded ~ because of RFC 1738. But this was replaced by RFC 3986 so its safe to use, now. But I do not understand why for example {} are encoded through rawurlencode() because they are not mentioned in RFC 3986.

An additional test I made was regarding auto-linking in mail texts. I tested Mozilla Thunderbird,,,, and and they fully linked URLs containing these chars:


Of course the ? was linked, too, but only if it was used once.

Some people would now suggest to use only the rawurlencode() chars, but did you ever hear that someone had problems to open these websites?




At sign, Colon, Comma and Exclamation mark,...

Because of that these chars should be usable unencoded without problems. Of course you should not use &; because of encoding sequences like &amp;. The same reason is valid for % as it used to encode chars in general. And = as it assigns a value to a parameter name.

Finally I would say its ok to use these unencoded:


But if you expect randomly generated URLs you should not use .!, because those mark the end of a sentence and some mail apps will not auto-link the last char of the url. Example:

Visit! !

PHP simple foreach loop with HTML

This will work although when embedding PHP in HTML it is better practice to use the following form:

    <?php foreach($array as $key=>$value): ?>
        <td><?= $key; ?></td>
    <?php endforeach; ?>

You can find the doc for the alternative syntax on

oracle - what statements need to be committed?

DML (Data Manipulation Language) commands need to be commited/rolled back. Here is a list of those commands.

Data Manipulation Language (DML) statements are used for managing data within schema objects. Some examples:

INSERT - insert data into a table
UPDATE - updates existing data within a table
DELETE - deletes records from a table, the space for the records remain
MERGE - UPSERT operation (insert or update)
CALL - call a PL/SQL or Java subprogram
EXPLAIN PLAN - explain access path to data
LOCK TABLE - control concurrency

What linux shell command returns a part of a string?

If you are looking for a shell utility to do something like that, you can use the cut command.

To take your example, try:

echo "abcdefg" | cut -c3-5

which yields


Where -cN-M tells the cut command to return columns N to M, inclusive.

Convert int to string?

string a = i.ToString();
string b = Convert.ToString(i);
string c = string.Format("{0}", i);
string d = $"{i}";
string e = "" + i;
string f = string.Empty + i;
string g = new StringBuilder().Append(i).ToString();

What is the (best) way to manage permissions for Docker shared volumes?

To share folder between docker host and docker container, try below command

$ docker run -v "$(pwd):$(pwd)" -i -t ubuntu

The -v flag mounts the current working directory into the container. When the host directory of a bind-mounted volume doesn’t exist, Docker will automatically create this directory on the host for you,

However, there are 2 problems we have here:

  1. You cannot write to the volume mounted if you were non-root user because the shared file will be owned by other user in host,
  2. You shouldn't run the process inside your containers as root but even if you run as some hard-coded user it still won't match the user on your laptop/Jenkins,


Container: create a user say 'testuser', by default user id will be starting from 1000,

Host: create a group say 'testgroup' with group id 1000, and chown the directory to the new group(testgroup

How to set time to a date object in java

If you don't have access to java 8 and the API java.time, here is my simple function to copy the time of one date to another date using the old java.util.Calendar (inspire by Jigar Joshi) :

 * Copy only the time of one date to the date of another date.
public static Date copyTimeToDate(Date date, Date time) {
    Calendar t = Calendar.getInstance();

    Calendar c = Calendar.getInstance();
    c.set(Calendar.HOUR_OF_DAY, t.get(Calendar.HOUR_OF_DAY));
    c.set(Calendar.MINUTE, t.get(Calendar.MINUTE));
    c.set(Calendar.SECOND, t.get(Calendar.SECOND));
    c.set(Calendar.MILLISECOND, t.get(Calendar.MILLISECOND));
    return c.getTime();

How to change value of object which is inside an array using JavaScript or jQuery?

You can use map function --

const answers = => {
  if( === id) return { id: id, value: }
  return answer

this.setState({ answers: answers })

Difference between Mutable objects and Immutable objects

Mutable objects have fields that can be changed, immutable objects have no fields that can be changed after the object is created.

A very simple immutable object is a object without any field. (For example a simple Comparator Implementation).

class Mutable{
  private int value;

  public Mutable(int value) {
     this.value = value;

  //getter and setter for value

class Immutable {
  private final int value;

  public Immutable(int value) {
     this.value = value;

  //only getter

How do I build JSON dynamically in javascript?

First, I think you're calling it the wrong thing. "JSON" stands for "JavaScript Object Notation" - it's just a specification for representing some data in a string that explicitly mimics JavaScript object (and array, string, number and boolean) literals. You're trying to build up a JavaScript object dynamically - so the word you're looking for is "object".

With that pedantry out of the way, I think that you're asking how to set object and array properties.

// make an empty object
var myObject = {};

// set the "list1" property to an array of strings
myObject.list1 = ['1', '2'];

// you can also access properties by string
myObject['list2'] = [];
// accessing arrays is the same, but the keys are numbers
myObject.list2[0] = 'a';
myObject['list2'][1] = 'b';

myObject.list3 = [];
// instead of placing properties at specific indices, you
// can push them on to the end
// or unshift them on to the beginning
myObject.list3[0]['key1'] = 'value1';
myObject.list3[1]['key2'] = 'value2';

myObject.not_a_list = '11';

That code will build up the object that you specified in your question (except that I call it myObject instead of myJSON). For more information on accessing properties, I recommend the Mozilla JavaScript Guide and the book JavaScript: The Good Parts.

How to write loop in a Makefile?

Maybe you can use:

    for i in `seq 1 4`; do ./a.out $$i; done;

What causes javac to issue the "uses unchecked or unsafe operations" warning

If you do what it suggests and recompile with the "-Xlint:unchecked" switch, it will give you more detailed information.

As well as the use of raw types (as described by the other answers), an unchecked cast can also cause the warning.

Once you've compiled with -Xlint, you should be able to rework your code to avoid the warning. This is not always possible, particularly if you are integrating with legacy code that cannot be changed. In this situation, you may decide to suppress the warning in places where you know that the code is correct:

public void myMethod()

How do I find out what License has been applied to my SQL Server installation?

This shows the licence type and number of licences:


How can I reorder a list?

newList = [oldList[3]]

Powershell script to check if service is started, if not then start it

Given $arrService = Get-Service -Name $ServiceName, $arrService.Status is a static property, corresponding to the value at the time of the call. Use $arrService.Refresh() when needed to renew the properties to current values.

MSDN ~ ServiceController.Refresh()

Refreshes property values by resetting the properties to their current values.

Oracle client and networking components were not found

In my case this was because a file named ociw32.dll had been placed in c:\windows\system32. This is however only allowed to exist in c:\oracle\\bin.

Deleting the file from system32, which had been placed there by an installation of Crystal Reports, fixed this issue

How to find which version of Oracle is installed on a Linux server (In terminal)

A bit manual searching but its an alternative way...
Find the Oracle home or where the installation files for Oracle is installed on your linux server.

cd / <-- Goto root directory
find . -print| grep -i dbm*.sql

Result varies on how you installed Oracle but mine displays this


Goto the folder

less /db/oracle/db1/sqlplus/doc/README.htm

scroll down and you should see something like this

SQL*Plus Release Notes - Release

How to import and use image in a Vue single file component?

These both work for me in JavaScript and TypeScript

<img src="@/assets/images/logo.png" alt=""> 


 <img src="./assets/images/logo.png" alt="">

Enable/disable buttons with Angular

export class ClassComponent implements OnInit {
  classes = [
  name: 'string',
  level: 'string',
  code: 'number',
  currentLesson: '1'


    if(obj.currentLession == current){
      return true;

  return false;

<ul class="table lessonOverview">
          <p>Lesson 1</p>
          <button [routerLink]="['/lesson1']" 
             [disabled]="checkCurrentLession(1)" class="primair">
               Start lesson</button>
          <p>Lesson 2</p>
          <button [routerLink]="['/lesson2']" 
             [disabled]="!checkCurrentLession(2)" class="primair">
               Start lesson</button>

Chrome Extension - Get DOM content

The terms "background page", "popup", "content script" are still confusing you; I strongly suggest a more in-depth look at the Google Chrome Extensions Documentation.

Regarding your question if content scripts or background pages are the way to go:

Content scripts: Definitely
Content scripts are the only component of an extension that has access to the web-page's DOM.

Background page / Popup: Maybe (probably max. 1 of the two)
You may need to have the content script pass the DOM content to either a background page or the popup for further processing.

Let me repeat that I strongly recommend a more careful study of the available documentation!
That said, here is a sample extension that retrieves the DOM content on StackOverflow pages and sends it to the background page, which in turn prints it in the console:


// Regex-pattern to check URLs against. 
// It matches URLs like: http[s]://[...][...]
var urlRegex = /^https?:\/\/(?:[^./?#]+\.)?stackoverflow\.com/;

// A function to use as callback
function doStuffWithDom(domContent) {
    console.log('I received the following DOM content:\n' + domContent);

// When the browser-action button is clicked...
chrome.browserAction.onClicked.addListener(function (tab) {
    // ...check the URL of the active tab against our pattern and...
    if (urlRegex.test(tab.url)) {
        // ...if it matches, send a message specifying a callback too
        chrome.tabs.sendMessage(, {text: 'report_back'}, doStuffWithDom);


// Listen for messages
chrome.runtime.onMessage.addListener(function (msg, sender, sendResponse) {
    // If the received message has the expected format...
    if (msg.text === 'report_back') {
        // Call the specified callback, passing
        // the web-page's DOM content as argument


  "manifest_version": 2,
  "name": "Test Extension",
  "version": "0.0",

  "background": {
    "persistent": false,
    "scripts": ["background.js"]
  "content_scripts": [{
    "matches": ["*://**"],
    "js": ["content.js"]
  "browser_action": {
    "default_title": "Test Extension"

  "permissions": ["activeTab"]

SVN: Folder already under version control but not comitting?

Have you tried performing an svn cleanup?

Convert Pandas DataFrame to JSON format

The output that you get after DF.to_json is a string. So, you can simply slice it according to your requirement and remove the commas from it too.

out = df.to_json(orient='records')[1:-1].replace('},{', '} {')

To write the output to a text file, you could do:

with open('file_name.txt', 'w') as f:

How do HashTables deal with collisions?

I strongly suggest you to read this blog post which appeared on HackerNews recently: How HashMap works in Java

In short, the answer is

What will happen if two different HashMap key objects have same hashcode?

They will be stored in same bucket but no next node of linked list. And keys equals () method will be used to identify correct key value pair in HashMap.

milliseconds to days

If you don't have another time interval bigger than days:

int days = (int) (milliseconds / (1000*60*60*24));

If you have weeks too:

int days = (int) ((milliseconds / (1000*60*60*24)) % 7);
int weeks = (int) (milliseconds / (1000*60*60*24*7));

It's probably best to avoid using months and years if possible, as they don't have a well-defined fixed length. Strictly speaking neither do days: daylight saving means that days can have a length that is not 24 hours.

TypeError: string indices must be integers, not str // working with dict

Actually I think that more general approach to loop through dictionary is to use iteritems():

# get tuples of term, courses
for term, term_courses in courses.iteritems():
    # get tuples of course number, info
    for course, info in term_courses.iteritems():
        # loop through info
        for k, v in info.iteritems():
            print k, v


assistant Peter C.
prereq cs101
name Programming a Robotic Car
teacher Sebastian

Or, as Matthias mentioned in comments, if you don't need keys, you can just use itervalues():

for term_courses in courses.itervalues():
    for info in term_courses.itervalues():
        for k, v in info.iteritems():
            print k, v

Module 'tensorflow' has no attribute 'contrib'

This issue might be helpful for you, it explains how to achieve TPUStrategy, a popular functionality of tf.contrib in TF<2.0.

So, in TF 1.X you could do the following:

resolver = tf.contrib.cluster_resolver.TPUClusterResolver('grpc://' + os.environ['COLAB_TPU_ADDR'])
strategy = tf.contrib.distribute.TPUStrategy(resolver)

And in TF>2.0, where tf.contrib is deprecated, you achieve the same by:

tf.config.experimental_connect_to_host('grpc://' + os.environ['COLAB_TPU_ADDR'])
resolver = tf.distribute.cluster_resolver.TPUClusterResolver('grpc://' + os.environ['COLAB_TPU_ADDR'])
strategy = tf.distribute.experimental.TPUStrategy(resolver) 

Does C# have an equivalent to JavaScript's encodeURIComponent()?

Try Server.UrlEncode(), or System.Web.HttpUtility.UrlEncode() for instances when you don't have access to the Server object. You can also use System.Uri.EscapeUriString() to avoid adding a reference to the System.Web assembly.

How to create named and latest tag in Docker?

Variation of Aaron's answer. Using sed without temporary files

ID=$(docker build  -t ${IMAGE}  .  | tail -1 | sed 's/.*Successfully built \(.*\)$/\1/')

docker tag ${ID} ${IMAGE}:${VERSION}
docker tag -f ${ID} ${IMAGE}:latest

How to set opacity in parent div and not affect in child div?

As mentioned by Tom, background-color: rgba(229,229,229, 0.85) can do the trick. Place that on the style of the parent element and child wont be affected.

SELECT using 'CASE' in SQL

which platform ?

   END AS FRUIT     

How can I analyze a heap dump in IntelliJ? (memory leak)

There also exists a 'JVM Debugger Memory View' found in the plugin repository, which could be useful.

How Does Modulus Divison Work

modulus division is simply this : divide two numbers and return the remainder only

27 / 16 = 1 with 11 left over, therefore 27 % 16 = 11

ditto 43 / 16 = 2 with 11 left over so 43 % 16 = 11 too

postgresql COUNT(DISTINCT ...) very slow

-- My default settings (this is basically a single-session machine, so work_mem is pretty high)
SET effective_cache_size='2048MB';
SET work_mem='16MB';

\echo original
        COUNT (distinct val) as aantal
FROM one

\echo group by+count(*)
        distinct val
       -- , COUNT(*)
FROM one

\echo with CTE
WITH agg AS (
    SELECT distinct val
    FROM one
    GROUP BY val
SELECT COUNT (*) as aantal
FROM agg


original                                                      QUERY PLAN                                                      
 Aggregate  (cost=36448.06..36448.07 rows=1 width=4) (actual time=1766.472..1766.472 rows=1 loops=1)
   ->  Seq Scan on one  (cost=0.00..32698.45 rows=1499845 width=4) (actual time=31.371..185.914 rows=1499845 loops=1)
 Total runtime: 1766.642 ms
(3 rows)

group by+count(*)
                                                         QUERY PLAN                                                         
 HashAggregate  (cost=36464.31..36477.31 rows=1300 width=4) (actual time=412.470..412.598 rows=1300 loops=1)
   ->  HashAggregate  (cost=36448.06..36461.06 rows=1300 width=4) (actual time=412.066..412.203 rows=1300 loops=1)
         ->  Seq Scan on one  (cost=0.00..32698.45 rows=1499845 width=4) (actual time=26.134..166.846 rows=1499845 loops=1)
 Total runtime: 412.686 ms
(4 rows)

with CTE
                                                             QUERY PLAN                                                             
 Aggregate  (cost=36506.56..36506.57 rows=1 width=0) (actual time=408.239..408.239 rows=1 loops=1)
   CTE agg
     ->  HashAggregate  (cost=36464.31..36477.31 rows=1300 width=4) (actual time=407.704..407.847 rows=1300 loops=1)
           ->  HashAggregate  (cost=36448.06..36461.06 rows=1300 width=4) (actual time=407.320..407.467 rows=1300 loops=1)
                 ->  Seq Scan on one  (cost=0.00..32698.45 rows=1499845 width=4) (actual time=24.321..165.256 rows=1499845 loops=1)
       ->  CTE Scan on agg  (cost=0.00..26.00 rows=1300 width=0) (actual time=407.707..408.154 rows=1300 loops=1)
     Total runtime: 408.300 ms
    (7 rows)

The same plan as for the CTE could probably also be produced by other methods (window functions)

ln (Natural Log) in Python

Here is the correct implementation using numpy (np.log() is the natural logarithm)

import numpy as np
p = 100
r = 0.06 / 12
FV = 4000

n = np.log(1 + FV * r/ p) / np.log(1 + r)

print ("Number of periods = " + str(n))


Number of periods = 36.55539635919235

How to embed new Youtube's live video permanent URL?

The issue is two-fold:

  1. WordPress reformats the YouTube link
  2. You need a custom embed link to support a live stream embed

As a prerequisite (as of August, 2016), you need to link an AdSense account and then turn on monetization in your YouTube channel. It's a painful change that broke a lot of live streams.

You will need to use the following URL format for the embed:

<iframe width="560" height="315" src="" frameborder="0" allowfullscreen></iframe>

The &autoplay=1 is not necessary, but I like to include it. Change CHANNEL to your channel's ID. One thing to note is that WordPress may reformat the URL once you commit your change. Therefore, you'll need a plugin that allows you to use raw code and not have it override. Using a custom PHP code plugin can help and you would just echo the code like so:

<?php echo '<iframe width="560" height="315" src="" frameborder="0" allowfullscreen></iframe>'; ?>

Let me know if that worked for you!

Subdomain on different host

UPDATE - I do not have Total DNS enabled at GoDaddy because the domain is hosted at DiscountASP. As such, I could not add an A Record and that is why GoDaddy was only offering to forward my subdomain to a different site. I finally realized that I had to go to DiscountASP to add the A Record to point to DreamHost. Now waiting to see if it all works!

Of course, use the stinkin' IP! I'm not sure why that wasn't registering for me. I guess their helper text example of pointing to another url was throwing me off.

Thanks for both of the replies. I 'got it' as soon as I read Bryant's response which was first but Saif kicked it up a notch and added a little more detail.


Convert float to double without losing precision

I found the following solution:

public static Double getFloatAsDouble(Float fValue) {
    return Double.valueOf(fValue.toString());

If you use float and double instead of Float and Double use the following:

public static double getFloatAsDouble(float value) {
    return Double.valueOf(Float.valueOf(value).toString()).doubleValue();

first-child and last-child with IE8

If you want to carry on using CSS3 selectors but need to support older browsers I would suggest using a polyfill such as Selectivizr.js

Embed website into my site

You might want to check HTML frames, which can do pretty much exactly what you are looking for. They are considered outdated however.

How to get past the login page with Wget?

You can log in via browser and copy the needed headers afterwards:


Use "Copy as cURL" in the Network tab of browser developer tools and replace curl's flag -H with wget's --header (and also --data with --post-data if needed).

Concatenate rows of two dataframes in pandas

Thanks to @EdChum I was struggling with same problem especially when indexes do not match. Unfortunatly in pandas guide this case is missed (when you for example delete some rows)

import pandas as pd
t=t.loc[t['a']>1] #now index starts from 1

u['b']=[1,2,3] #index starts from 0

#option 1
#keep index of t
u.index = t.index 

#option 2
#index of t starts from 0
t.reset_index(drop=True, inplace=True)

#now concat will keep number of rows 
r=pd.concat([t,u], axis=1)

VBScript to send email without running Outlook

You can send email without Outlook in VBScript using the CDO.Message object. You will need to know the address of your SMTP server to use this:

Set MyEmail=CreateObject("CDO.Message")

MyEmail.From="[email protected]"
MyEmail.To="[email protected]"
MyEmail.TextBody="Testing one two three."

MyEmail.Configuration.Fields.Item ("")=2

'SMTP Server
MyEmail.Configuration.Fields.Item ("")=""

'SMTP Port
MyEmail.Configuration.Fields.Item ("")=25 


set MyEmail=nothing

If your SMTP server requires a username and password then paste these lines in above the MyEmail.Configuration.Fields.Update line:

'SMTP Auth (For Windows Auth set this to 2)
MyEmail.Configuration.Fields.Item ("")=1
MyEmail.Configuration.Fields.Item ("")="username" 
MyEmail.Configuration.Fields.Item ("")="password"

More information on using CDO to send email with VBScript can be found on the link below:

Could not find or load main class org.gradle.wrapper.GradleWrapperMain

In my case (using windows 10) gradlew.bat has the following lines of code in:

set DIRNAME=%~dp0
if "%DIRNAME%" == "" set DIRNAME=.
set APP_BASE_NAME=%~n0

The APP_HOME variable is essentially gradles root folder for the project, so, if this gets messed up in some way you are going to get:

Error: Could not find or load main class org.gradle.wrapper.GradleWrapperMain

For me, this had been messed up because my project folder structure had an ampersand (&) in it. Eg C:\Test&Dev\MyProject

So, gradel was trying to find the gradle-wrapper.jar file in a root folder of C:\Test (stripping off everything after and including the '&')

I found this by adding the following line below the set APP_HOME=%DIRNAME% line above. Then ran the bat file to see the result.

echo "%APP_HOME%"

There will be a few other 'special characters' that could break a path/directory.

':app:lintVitalRelease' error when generating signed apk

How to find error details

Anylyze -> Inspect Code

enter image description here

Then in Inspection Results you will see an error

enter image description here

In my case build failed due to unresolved javadoc reference in Google IAP

Populating a ComboBox using C#

but do you not just get your combo box name and then items.add("")?

For instance


Hope this helped :D

How to read pickle file?

I developed a software tool that opens (most) Pickle files directly in your browser (nothing is transferred so it's 100% private):

Maven Out of Memory Build Failure

Need to install jar files as well so that build can save memory in getting local jars.

Below command work for me after trying all those "MAVEN_OPTS" environment variable.

run "mvn clean install -U" on terminal from the root folder of the project.

Postgresql Windows, is there a default password?

Try this:

Open PgAdmin -> Files -> Open pgpass.conf

You would get the path of pgpass.conf at the bottom of the window. Go to that location and open this file, you can find your password there.


If the above does not work, you may consider trying this:

 1. edit pg_hba.conf to allow trust authorization temporarily
 2. Reload the config file (pg_ctl reload)
 3. Connect and issue ALTER ROLE / PASSWORD to set the new password
 4. edit pg_hba.conf again and restore the previous settings
 5. Reload the config file again

How to get the second column from command output?

import sys 

col = int(sys.argv[1]) - 1

for line in sys.stdin:
    columns = line.split()

    except IndexError:
        # ignore

Then, supposing you name the script as co, say, do something like this to get the sizes of files (the example assumes you're using Linux, but the script itself is OS-independent) :-

ls -lh | co 5

Why are hexadecimal numbers prefixed with 0x?

It's a prefix to indicate the number is in hexadecimal rather than in some other base. The C programming language uses it to tell compiler.


0x6400 translates to 6*16^3 + 4*16^2 + 0*16^1 +0*16^0 = 25600. When compiler reads 0x6400, It understands the number is hexadecimal with the help of 0x term. Usually we can understand by (6400)16 or (6400)8 or whatever ..

For binary it would be:


Hope I have helped in some way.

Good day!

Unable to load Private Key. (PEM routines:PEM_read_bio:no start line:pem_lib.c:648:Expecting: ANY PRIVATE KEY)

May be the private key itself is not present in the file.I was also faced the same issue but the problem is that there is no private key present in the file.

Select from one table where not in another

To expand on Johan's answer, if the part_num column in the sub-select can contain null values then the query will break.

To correct this, add a null check...

SELECT FROM r2r.partmaster pm
      (SELECT pd.part_num FROM wpsapi4.product_details pd 
                  where pd.part_num is not null)
  • Sorry but I couldn't add a comment as I don't have the rep!

iPhone App Icons - Exact Radius?

There are two totally conflicting answers with large number of votes one is 160px@1024 the other is 180px@1024. So witch one?

I ran some experiments and I think that it is 180px@1024 so drbarnard is correct.

I downloaded iTunes U icon from the App Store it's 175x175px I upscaled it in photoshop to 1024px and put two shapes on it, one with 160px radius and one with 180px.

As you can see below the shape (thin gray line) with 160px (the 1st one) is a bit off whereas the one with 180px looks just fine.

shape with 160px radiusenter image description here

This is what I do now in PhotoShop:

  1. I create a canvas sized 1026x1026px with a 180px mask for main design Smart Object.
  2. I duplicate the main Smart Object 5 times and resize them to 1024px, 144px, 114px, 72px and 57px.
  3. I put a "New layered Based Slice" on each Smart Objects and I rename slices according to their size (e.g. icon-72px).
  4. When I save the artwork I select "All User Slices" and BANG! I have all icons necessary for my app.

Remove attribute "checked" of checkbox

using .removeAttr() on a boolean attribute such as checked, selected, or readonly would also set the corresponding named property to false.

Hence removed this checked attribute

$("#IdName option:checked").removeAttr("checked");

How do I list all cron jobs for all users?

For me look at /var/spool/cron/crontabs is the best way

How to replace all special character into a string using C#

Also, It can be done with LINQ

var str = "Hello@Hello&Hello(Hello)";
var characters = str.Select(c => char.IsLetter(c) ? c : ',')).ToArray();             
var output = new string(characters);

Replace HTML page with contents retrieved via AJAX

You could try doing

document.getElementById(id).innerHTML = ajax_response

How to push changes to github after jenkins build completes?

Found an answer myself, this blog helped:

Basically need to execute:

git checkout master

before modifying any files


git commit -am "Updated version number"

after modified files

and then use post build action of Git Publisher with an option of Merge Results which will push changes to github on successful build.

Installation of VB6 on Windows 7 / 8 / 10

I've installed and use VB6 for legacy projects many times on Windows 7.

What I have done and never came across any issues, is to install VB6, ignore the errors and then proceed to install the latest service pack, currently SP6.

Download here:

Bonus: Also once you install it and realize that scrolling doesn't work, use the below:

Request Permission for Camera and Library in iOS 10 - Info.plist


Limited Photos



<string>$(PRODUCT_NAME) camera description.</string>


<string>$(PRODUCT_NAME)photos description.</string>

Save Photos

<string>$(PRODUCT_NAME) photos add description.</string>


<key> NSLocationWhenInUseUsageDescription</key>
<string>$(PRODUCT_NAME) location description.</string>

Apple Music

<string>$(PRODUCT_NAME) My description about why I need this capability</string>


<string>$(PRODUCT_NAME) My description about why I need this capability</string>


<string>$(PRODUCT_NAME) My description about why I need this capability</string>

Saving and Reading Bitmaps/Images from Internal memory in Android

 * Created by Ilya Gazman on 3/6/2016.
public class ImageSaver {

    private String directoryName = "images";
    private String fileName = "image.png";
    private Context context;
    private boolean external;

    public ImageSaver(Context context) {
        this.context = context;

    public ImageSaver setFileName(String fileName) {
        this.fileName = fileName;
        return this;

    public ImageSaver setExternal(boolean external) {
        this.external = external;
        return this;

    public ImageSaver setDirectoryName(String directoryName) {
        this.directoryName = directoryName;
        return this;

    public void save(Bitmap bitmapImage) {
        FileOutputStream fileOutputStream = null;
        try {
            fileOutputStream = new FileOutputStream(createFile());
            bitmapImage.compress(Bitmap.CompressFormat.PNG, 100, fileOutputStream);
        } catch (Exception e) {
        } finally {
            try {
                if (fileOutputStream != null) {
            } catch (IOException e) {

    private File createFile() {
        File directory;
            directory = getAlbumStorageDir(directoryName);
        else {
            directory = context.getDir(directoryName, Context.MODE_PRIVATE);
        if(!directory.exists() && !directory.mkdirs()){
            Log.e("ImageSaver","Error creating directory " + directory);

        return new File(directory, fileName);

    private File getAlbumStorageDir(String albumName) {
        return new File(Environment.getExternalStoragePublicDirectory(
                Environment.DIRECTORY_PICTURES), albumName);

    public static boolean isExternalStorageWritable() {
        String state = Environment.getExternalStorageState();
        return Environment.MEDIA_MOUNTED.equals(state);

    public static boolean isExternalStorageReadable() {
        String state = Environment.getExternalStorageState();
        return Environment.MEDIA_MOUNTED.equals(state) ||

    public Bitmap load() {
        FileInputStream inputStream = null;
        try {
            inputStream = new FileInputStream(createFile());
            return BitmapFactory.decodeStream(inputStream);
        } catch (Exception e) {
        } finally {
            try {
                if (inputStream != null) {
            } catch (IOException e) {
        return null;


  • To save:

    new ImageSaver(context).
  • To load:

    Bitmap bitmap = new ImageSaver(context).


Added ImageSaver.setExternal(boolean) to support saving to external storage based on googles example.

Building executable jar with maven?

If you don't want execute assembly goal on package, you can use next command:

mvn package assembly:single

Here package is keyword.

How to include libraries in Visual Studio 2012?

In code level also, you could add your lib to the project using the compiler directives #pragma.


#pragma comment( lib, "yourLibrary.lib" )

JSON Invalid UTF-8 middle byte

JSON data must be encoded as UTF-8, UTF-16 or UTF-32. The JSON decoder can determine the encoding by examining the first four octets of the byte stream:

       00 00 00 xx  UTF-32BE
       00 xx 00 xx  UTF-16BE
       xx 00 00 00  UTF-32LE
       xx 00 xx 00  UTF-16LE
       xx xx xx xx  UTF-8

It sounds like the server is encoding data in some illegal encoding (ISO-8859-1, windows-1252, etc.)

How to Call VBA Function from Excel Cells?

The issue you have encountered is that UDFs cannot modify the Excel environment, they can only return a value to the calling cell.

There are several alternatives

  1. For the sample given you don't actually need VBA. This formula will work

  2. Use a rather messy work around: See this answer

  3. You can use ExecuteExcel4Macro or OLEDB

How to increase apache timeout directive in .htaccess?

if you have long processing server side code, I don't think it does fall into 404 as you said ("it goes to a webpage is not found error page")

Browser should report request timeout error.

You may do 2 things:

Based on CGI/Server side engine increase timeout there

PHP : - default is 30 seconds

In php.ini:

max_execution_time 60

Increase apache timeout - default is 300 (in version 2.4 it is 60).

In your httpd.conf (in server config or vhost config)

TimeOut 600

Note that first setting allows your PHP script to run longer, it will not interferre with network timeout.

Second setting modify maximum amount of time the server will wait for certain events before failing a request

Sorry, I'm not sure if you are using PHP as server side processing, but if you provide more info I will be more accurate.

grant remote access of MySQL database from any IP address

GRANT ALL PRIVILEGES ON *.* TO 'user'@'ipadress'

JavaScript get child element

Try this one:

function show_sub(cat) {
    var parent = cat,
    sub = parent.getElementsByClassName('sub');
    if (sub[0].style.display == 'inline'){
        sub[0].style.display = 'none';
    else {
        sub[0].style.display = 'inline';

document.getElementById('cat').onclick = function(){

and use this for IE6 & 7

if (typeof document.getElementsByClassName!='function') {
    document.getElementsByClassName = function() {
        var elms = document.getElementsByTagName('*');
        var ei = new Array();
        for (i=0;i<elms.length;i++) {
            if (elms[i].getAttribute('class')) {
               ecl = elms[i].getAttribute('class').split(' ');
                for (j=0;j<ecl.length;j++) {
                    if (ecl[j].toLowerCase() == arguments[0].toLowerCase()) {
            } else if (elms[i].className) {
                ecl = elms[i].className.split(' ');
                for (j=0;j<ecl.length;j++) {
                    if (ecl[j].toLowerCase() == arguments[0].toLowerCase()) {
        return ei;

WPF TemplateBinding vs RelativeSource TemplatedParent

One more thing - TemplateBindings don't allow value converting. They don't allow you to pass a Converter and don't automatically convert int to string for example (which is normal for a Binding).

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

Here's a bug report on the feature you're requesting.

It's status is "reviewed" but I don't believe it's been implemented yet.

what innerHTML is doing in javascript?

For understanding innerHTML property you first need to go through the basics of the javascript object and HTML DOM(Document object model). I will try to explain:

  1. JavaScript objects consist of properties and methods.
  2. for rendering HTML document web browser creates a DOM, in DOM every HTML element is treated as a JavaScript Object which has a set of properties and methods associated with it.

Now coming to your Question:

HTML code:

<p id= "myPara"> We love to Code.</p>

JavaScript code:


here, document.getElementById("myPara") will return our html element as a javascript object which has pre-defined property innerHTML. innerHTML property contains the content of HTML tag.

Hope this will help.

You can run following HTML code in your browser to understand it:

  <p id= "myPara"> We love to Code.</p>

Change Name of Import in Java, or import two classes with the same name

As the other answers already stated, Java does not provide this feature.

Implementation of this feature has been requested multiple times, e.g. as JDK-4194542: class name aliasing or JDK-4214789: Extend import to allow renaming of imported type.

From the comments:

This is not an unreasonable request, though hardly essential. The occasional use of fully qualified names is not an undue burden (unless the library really reuses the same simple names right and left, which is bad style).

In any event, it doesn't pass the bar of price/performance for a language change.

So I guess we will not see this feature in Java anytime soon :-P

MySQL case sensitive query

To improve James' excellent answer:

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

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

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

adb command for getting ip address assigned by operator

To get all IPs (WIFI and data SIM) even on a non-rooted phone in 2019 use:

adb shell ip -o a

The output looks like:

1: lo    inet scope host lo\       valid_lft forever preferred_lft forever
1: lo    inet6 ::1/128 scope host \       valid_lft forever preferred_lft forever
3: dummy0    inet6 fe80::489c:2ff:fe4a:00005/64 scope link \       valid_lft forever preferred_lft forever
11: rmnet_data1    inet6 fe80::735d:50fb:2e2:0000/64 scope link \       valid_lft forever preferred_lft forever
21: r_rmnet_data0    inet6 fe80::e38:ce2a:523a:0000/64 scope link \       valid_lft forever preferred_lft forever
30: wlan0    inet brd scope global wlan0\       valid_lft forever preferred_lft forever
30: wlan0    inet6 fe80::c2ee:fbff:fe4a:0000/64 scope link \       valid_lft forever preferred_lft forever

You can connect either through adb shell or run the comman ip -o a directly in a terminal emulator. Again, no root required.

How can I get the day of a specific date with PHP

$datetime = DateTime::createFromFormat('Ymd', '20151102');

echo $datetime->format('D');

Are "while(true)" loops so bad?

I would say that generally the reason it's not considered a good idea is that you are not using the construct to it's full potential. Also, I tend to think that a lot of programming instructors don't like it when their students come in with "baggage". By that I mean I think they like to be the primary influence on their students programming style. So perhaps that's just a pet peeve of the instructor's.

How to get < span > value?

Try this

var div = document.getElementById("test");
var spans = div.getElementsByTagName("span");


Warning: DOMDocument::loadHTML(): htmlParseEntityRef: expecting ';' in Entity,


This is incorrect, use this instead:


How to pass a type as a method parameter in Java

You could pass a Class<T> in.

private void foo(Class<?> cls) {
    if (cls == String.class) { ... }
    else if (cls == int.class) { ... }

private void bar() {

Update: the OOP way depends on the functional requirement. Best bet would be an interface defining foo() and two concrete implementations implementing foo() and then just call foo() on the implementation you've at hand. Another way may be a Map<Class<?>, Action> which you could call by actions.get(cls). This is easily to be combined with an interface and concrete implementations: actions.get(cls).foo().

php is null or empty?

Use empty -


$a = '';
if(empty($a)) {
    echo 'is empty';

How to write files to assets folder or raw folder in android?

Why not update the files on the local file system instead? You can read/write files into your applications sandboxed area.

Other alternatives you may want to look into are Shared Perferences and using Cache Files (all described at the link above)

MySQL match() against() - order by relevance and column?

I have never done so, but it seems like

MATCH (head, head, body) AGAINST ('some words' IN BOOLEAN MODE)

Should give a double weight to matches found in the head.

Just read this comment on the docs page, Thought it might be of value to you:

Posted by Patrick O'Lone on December 9 2002 6:51am

It should be noted in the documentation that IN BOOLEAN MODE will almost always return a relevance of 1.0. In order to get a relevance that is meaningful, you'll need to:

SELECT MATCH('Content') AGAINST ('keyword1 keyword2') as Relevance 
FROM table 
WHERE MATCH ('Content') AGAINST('+keyword1+keyword2' IN BOOLEAN MODE) 
HAVING Relevance > 0.2 
ORDER BY Relevance DESC 

Notice that you are doing a regular relevance query to obtain relevance factors combined with a WHERE clause that uses BOOLEAN MODE. The BOOLEAN MODE gives you the subset that fulfills the requirements of the BOOLEAN search, the relevance query fulfills the relevance factor, and the HAVING clause (in this case) ensures that the document is relevant to the search (i.e. documents that score less than 0.2 are considered irrelevant). This also allows you to order by relevance.

This may or may not be a bug in the way that IN BOOLEAN MODE operates, although the comments I've read on the mailing list suggest that IN BOOLEAN MODE's relevance ranking is not very complicated, thus lending itself poorly for actually providing relevant documents. BTW - I didn't notice a performance loss for doing this, since it appears MySQL only performs the FULLTEXT search once, even though the two MATCH clauses are different. Use EXPLAIN to prove this.

So it would seem you may not need to worry about calling the fulltext search twice, though you still should "use EXPLAIN to prove this"

Python: How exactly can you take a string, split it, reverse it and join it back together again?

Not fitting 100% to this particular question but if you want to split from the back you can do it like this:

theStringInQuestion[::-1].split('/', 1)[1][::-1]

This code splits once at symbol '/' from behind.

Call break in nested if statements

But there is switch-case :)

switch (true) {
    case true:
        console.log("Yes, its ture :) Break from the switch-case");
    case false:
        console.log("Nope, but if the condition was set to false this would be used and then break");

        console.log("If all else fails");

Altering column size in SQL Server

ALTER TABLE "Employee" MODIFY ("Salary" NUMERIC(22,5));

PHP - Extracting a property from an array of objects

Warning create_function() has been DEPRECATED as of PHP 7.2.0. Relying on this function is highly discouraged.

Builtin loops in PHP are faster then interpreted loops, so it actually makes sense to make this one a one-liner:

$result = array();
array_walk($cats, create_function('$value, $key, &$result', '$result[] = $value->id;'), $result)

How to delete a file via PHP?

The following should help

  • realpath — Returns canonicalized absolute pathname
  • is_writable — Tells whether the filename is writable
  • unlink — Deletes a file

Run your filepath through realpath, then check if the returned path is writable and if so, unlink it.