Programs & Examples On #Freebsd

FreeBSD is an advanced Unix-like operating system for modern server, desktop, and embedded computer platforms. It is open source and licensed under the 2-clause BSD license.

Determine the process pid listening on a certain port

Short version which you can pass to kill command:

lsof -i:80 -t

How to install packages offline?

I had a similar problem. And i had to make it install the same way, we do from pypi.

I did the following things:

  1. Make a directory to store all the packages in the machine that have internet access.

    mkdir -p /path/to/packages/
  2. Download all the packages to the path

Edit: You can also try:

python3 -m pip wheel --no-cache-dir -r requirements.txt -w /path/to/packages
pip download -r requirements.txt -d /path/to/packages

Eg:- ls /root/wheelhouse/  # **/root/wheelhouse** is my **/path/to/packages/**
total 4524
-rw-r--r--. 1 root root   16667 May 23  2017 incremental-17.5.0-py2.py3-none-any.whl
-rw-r--r--. 1 root root   34713 Sep  1 10:21 attrs-18.2.0-py2.py3-none-any.whl
-rw-r--r--. 1 root root 3088398 Oct 15 14:41 Twisted-18.9.0.tar.bz2
-rw-r--r--. 1 root root  133356 Jan 28 15:58 chardet-3.0.4-py2.py3-none-any.whl
-rw-r--r--. 1 root root  154154 Jan 28 15:58 certifi-2018.11.29-py2.py3-none-any.whl
-rw-r--r--. 1 root root   57987 Jan 28 15:58 requests-2.21.0-py2.py3-none-any.whl
-rw-r--r--. 1 root root   58594 Jan 28 15:58 idna-2.8-py2.py3-none-any.whl
-rw-r--r--. 1 root root  118086 Jan 28 15:59 urllib3-1.24.1-py2.py3-none-any.whl
-rw-r--r--. 1 root root   47229 Jan 28 15:59 tqdm-4.30.0-py2.py3-none-any.whl
-rw-r--r--. 1 root root    7922 Jan 28 16:13 constantly-15.1.0-py2.py3-none-any.whl
-rw-r--r--. 1 root root  164706 Jan 28 16:14 zope.interface-4.6.0-cp27-cp27mu-manylinux1_x86_64.whl
-rw-r--r--. 1 root root  573841 Jan 28 16:14 setuptools-40.7.0-py2.py3-none-any.whl
-rw-r--r--. 1 root root   37638 Jan 28 16:15 Automat-0.7.0-py2.py3-none-any.whl
-rw-r--r--. 1 root root   37905 Jan 28 16:15 hyperlink-18.0.0-py2.py3-none-any.whl
-rw-r--r--. 1 root root   52311 Jan 28 16:15 PyHamcrest-1.9.0-py2.py3-none-any.whl
 -rw-r--r--. 1 root root   10586 Jan 28 16:15 six-1.12.0-py2.py3-none-any.whl
  1. Tar the packages directory and copy it to the Machine that doesn't have internet access. Then do,

    cd /path/to/packages/
    tar -cvzf packages.tar.gz .  # not the . (dot) at the end

Copy the packages.tar.gz into the destination machine that doesn't have internet access.

  1. In the machine that doesn't have internet access, do the following (Assuming you copied the tarred packages to /path/to/package/ in the current machine)

    cd /path/to/packages/
    tar -xvzf packages.tar.gz
    mkdir -p $HOME/.config/pip/
    vi $HOME/.config/pip/pip.conf

and paste the following content inside and save it.

timeout = 10
find-links = file:///path/to/package/
no-cache-dir = true
no-index = true
  1. Finally, i suggest you use, some form of virtualenv for installing the packages.

    virtualenv -p python2 venv # use python3, if you are on python3
    source ./venv/bin/activate
    pip install <package>

You should be able to download all the modules that are in the directory /path/to/package/.

Note: I only did this, because i couldn't add options or change the way we install the modules. Otherwise i'd have done

pip install --no-index --find-links /path/to/download/dir/ -r requirements.txt

Check if string is neither empty nor space in shell script

Another quick test for a string to have something in it but space.

if [[ -n "${str// /}" ]]; then
    echo "It is not empty!"

"-n" means non-zero length string.

Then the first two slashes mean match all of the following, in our case space(s). Then the third slash is followed with the replacement (empty) string and closed with "}". Note the difference from the usual regular expression syntax.

You can read more about string manipulation in bash shell scripting here.

How can I get the behavior of GNU's readlink -f on a Mac?

Better late than never, I suppose. I was motivated to develop this specifically because my Fedora scripts weren't working on the Mac. The problem is dependencies and Bash. Macs don't have them, or if they do, they are often somewhere else (another path). Dependency path manipulation in a cross-platform Bash script is a headache at best and a security risk at worst - so it's best to avoid their use, if possible.

The function get_realpath() below is simple, Bash-centric, and no dependencies are required. I uses only the Bash builtins echo and cd. It is also fairly secure, as everything gets tested at each stage of the way and it returns error conditions.

If you don't want to follow symlinks, then put set -P at the front of the script, but otherwise cd should resolve the symlinks by default. It's been tested with file arguments that are {absolute | relative | symlink | local} and it returns the absolute path to the file. So far we've not had any problems with it.

function get_realpath() {

if [[ -f "$1" ]]
    # file *must* exist
    if cd "$(echo "${1%/*}")" &>/dev/null
        # file *may* not be local
        # exception is ./file.ext
        # try 'cd .; cd -;' *works!*
        local tmppwd="$PWD"
        cd - &>/dev/null
        # file *must* be local
        local tmppwd="$PWD"
    # file *cannot* exist
    return 1 # failure

# reassemble realpath
echo "$tmppwd"/"${1##*/}"
return 0 # success


You can combine this with other functions get_dirname, get_filename, get_stemname and validate_path. These can be found at our GitHub repository as realpath-lib (full disclosure - this is our product but we offer it free to the community without any restrictions). It also could serve as a instructional tool - it's well documented.

We've tried our best to apply so-called 'modern Bash' practices, but Bash is a big subject and I'm certain there will always be room for improvement. It requires Bash 4+ but could be made to work with older versions if they are still around.

ImportError: No module named psycopg2

For Python3

Step 1: Install Dependencies

sudo apt-get install python3 python-dev python3-dev

Step 2: Install

pip install psycopg2

How do I check if a type is a subtype OR the type of an object?

Apparently, no.

Here's the options:


As you've already found out, this will not work if the two types are the same, here's a sample LINQPad program that demonstrates:

void Main()

public class Base { }
public class Derived : Base { }



Which indicates that Derived is a subclass of Base, but that Baseis (obviously) not a subclass of itself.


Now, this will answer your particular question, but it will also give you false positives. As Eric Lippert has pointed out in the comments, while the method will indeed return True for the two above questions, it will also return True for these, which you probably don't want:

void Main()

public class Base { }
public class Derived : Base { }

Here you get the following output:


The last True there would indicate, if the method only answered the question asked, that uint[] inherits from int[] or that they're the same type, which clearly is not the case.

So IsAssignableFrom is not entirely correct either.

is and as

The "problem" with is and as in the context of your question is that they will require you to operate on the objects and write one of the types directly in code, and not work with Type objects.

In other words, this won't compile:

SubClass is BaseClass
   +-- need object reference here

nor will this:

typeof(SubClass) is typeof(BaseClass)
                            +-- need type name here, not Type object

nor will this:

typeof(SubClass) is BaseClass
       +-- this returns a Type object, And "System.Type" does not
           inherit from BaseClass


While the above methods might fit your needs, the only correct answer to your question (as I see it) is that you will need an extra check:

typeof(Derived).IsSubclassOf(typeof(Base)) || typeof(Derived) == typeof(Base);

which of course makes more sense in a method:

public bool IsSameOrSubclass(Type potentialBase, Type potentialDescendant)
    return potentialDescendant.IsSubclassOf(potentialBase)
           || potentialDescendant == potentialBase;

How to destroy JWT Tokens on logout?

You cannot manually expire a token after it has been created. Thus, you cannot log out with JWT on the server-side as you do with sessions.

JWT is stateless, meaning that you should store everything you need in the payload and skip performing a DB query on every request. But if you plan to have a strict log out functionality, that cannot wait for the token auto-expiration, even though you have cleaned the token from the client-side, then you might need to neglect the stateless logic and do some queries. so what's a solution?

  • Set a reasonable expiration time on tokens

  • Delete the stored token from client-side upon log out

  • Query provided token against The Blacklist on every authorized request


“Blacklist” of all the tokens that are valid no more and have not expired yet. You can use a DB that has a TTL option on documents which would be set to the amount of time left until the token is expired.


Redis is a good option for blacklist, which will allow fast in-memory access to the list. Then, in the middleware of some kind that runs on every authorized request, you should check if the provided token is in The Blacklist. If it is you should throw an unauthorized error. And if it is not, let it go and the JWT verification will handle it and identify if it is expired or still active.

For more information, see How to log out when using JWT. by Arpy Vanyan

Removing duplicate rows in Notepad++

Search for the regular expression: \b(\w+)\b([\w\W]*)\b\1\b

Replace it with: $1$2

Hit the Replace button until there are no more matches for the regular expression in your file.

How can I pad a value with leading zeros?

A simple function to do it:

function padStr(number, numDigits){
    (number < 0 ? '-':'') 
    + ((new Array(numDigits + 1).join("0"))
    + Math.abs(number)).slice(-numDigits);

Add a tooltip to a div

Tooltips Position pure css

      div {_x000D_
        position: absolute;_x000D_
        top: 50%;_x000D_
        left: 50%;_x000D_
        transform: translate(-50%, -50%);_x000D_
        -ms-transform: translate(-50%, -50%); /* IE 9 */_x000D_
        -webkit-transform: translate(-50%, -50%); /* Chrome, Safari, Opera */ _x000D_
        text-align: center;_x000D_
      }       _x000D_
      .tooltip {_x000D_
        position: relative;_x000D_
        display: inline-block;_x000D_
        border-bottom: 1px dotted black;_x000D_
      .tooltip .tooltiptext {_x000D_
        visibility: hidden;_x000D_
        width: 120px;_x000D_
        background-color: black;_x000D_
        color: #fff;_x000D_
        //text-align: center;_x000D_
        border-radius: 6px;_x000D_
        padding: 5px 0;_x000D_
        /* Position the tooltip */_x000D_
        position: absolute;_x000D_
        z-index: 1;_x000D_
      .tooltip:hover .tooltiptext {_x000D_
        visibility: visible;_x000D_
      }  _x000D_
      .toolLeft {_x000D_
        top: -5px;_x000D_
        right: 105%;_x000D_
      }     _x000D_
      .toolRight {_x000D_
        top: -5px;_x000D_
        left: 105%;_x000D_
      .toolTop {_x000D_
        bottom: 100%;_x000D_
        left: 50%;_x000D_
        margin-left: -60px;_x000D_
      .toolBottom {_x000D_
        top: 100%;_x000D_
        left: 50%;_x000D_
        margin-left: -60px;_x000D_
      <div class="tooltip">Top <span class="tooltiptext toolTop">Tooltip text</span></div><br />_x000D_
      <div class="tooltip">Left  <span class="tooltiptext toolLeft">Tooltip text</span></div><br />   _x000D_
      <div class="tooltip">Right <span class="tooltiptext toolRight">Tooltip text</span></div><br />_x000D_
      <div class="tooltip">Bottom  <span class="tooltiptext toolBottom">Tooltip text</span></div><br />   _x000D_

create table in postgreSQL

Please try this:

CREATE TABLE article (
  article_id bigint(20) NOT NULL serial,
  article_name varchar(20) NOT NULL,
  article_desc text NOT NULL,
  date_added datetime default NULL,
  PRIMARY KEY (article_id)

How to limit the maximum value of a numeric field in a Django model?

I had this very same problem; here was my solution:

SCORE_CHOICES = zip( range(1,n), range(1,n) )
score = models.IntegerField(choices=SCORE_CHOICES, blank=True)

How do I get just the date when using MSSQL GetDate()?

Slight bias to SQL Server


DATEADD(day, DATEDIFF(day, 0, GETDATE()), 0)

SQL Server 2008 has date type though. So just use


Edit: To add one day, compare to the day before "zero"

DATEADD(day, DATEDIFF(day, -1, GETDATE()), 0)

From cyberkiwi:

An alternative that does not involve 2 functions is (the +1 can be in or ourside the brackets).


DateDiff returns a number but for all purposes this will work as a date wherever you intend to use this expression, except converting it to VARCHAR directly - in which case you would have used the CONVERT approach directly on GETDATE(), e.g.

convert(varchar, GETDATE() +1, 102)

Converting a factor to numeric without losing information R (as.numeric() doesn't seem to work)

First, factor consists of indices and levels. This fact is very very important when you are struggling with factor.

For example,

> z <- factor(letters[c(3, 2, 3, 4)])

# human-friendly display, but internal structure is invisible
> z
[1] c b c d
Levels: b c d

# internal structure of factor
> unclass(z)
[1] 2 1 2 3
[1] "b" "c" "d"

here, z has 4 elements.
The index is 2, 1, 2, 3 in that order.
The level is associated with each index: 1 -> b, 2 -> c, 3 -> d.

Then, as.numeric converts simply the index part of factor into numeric.
as.character handles the index and levels, and generates character vector expressed by its level.

?as.numeric says that Factors are handled by the default method.

Handling of non breaking space: <p>&nbsp;</p> vs. <p> </p>

In HTML, elements containing nothing but normal whitespace characters are considered empty. A paragraph that contains just a normal space character will have zero height. A non-breaking space is a special kind of whitespace character that isn't considered to be insignificant, so it can be used as content for a non-empty paragraph.

Even if you consider CSS margins on paragraphs, since an "empty" paragraph has zero height, its vertical margins will collapse. This causes it to have no height and no margins, making it appear as if it were never there at all.

How to search file text for a pattern and replace it with a given value

Disclaimer: This approach is a naive illustration of Ruby's capabilities, and not a production-grade solution for replacing strings in files. It's prone to various failure scenarios, such as data loss in case of a crash, interrupt, or disk being full. This code is not fit for anything beyond a quick one-off script where all the data is backed up. For that reason, do NOT copy this code into your programs.

Here's a quick short way to do it.

file_names = ['foo.txt', 'bar.txt']

file_names.each do |file_name|
  text =
  new_contents = text.gsub(/search_regexp/, "replacement string")

  # To merely print the contents of the file, use:
  puts new_contents

  # To write changes to the file, use:, "w") {|file| file.puts new_contents }

Disable webkit's spin buttons on input type="number"?

I discovered that there is a second portion of the answer to this.

The first portion helped me, but I still had a space to the right of my type=number input. I had zeroed out the margin on the input, but apparently I had to zero out the margin on the spinner as well.

This fixed it:

input[type=number]::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;

ng if with angular for string contains

ng-if="'?') !== -1" 

Binary Data in JSON String. Something better than Base64

Just to add the resource and complexity standpoint to the discussion. Since doing PUT/POST and PATCH for storing new resources and altering them, one should remember that the content transfer is an exact representation of the content that is stored and that is received by issuing a GET operation.

A multi-part message is often used as a savior but for simplicity reason and for more complex tasks, I prefer the idea of giving the content as a whole. It is self-explaining and it is simple.

And yes JSON is something crippling but in the end JSON itself is verbose. And the overhead of mapping to BASE64 is a way to small.

Using Multi-Part messages correctly one has to either dismantle the object to send, use a property path as the parameter name for automatic combination or will need to create another protocol/format to just express the payload.

Also liking the BSON approach, this is not that widely and easily supported as one would like it to be.

Basically, we just miss something here but embedding binary data as base64 is well established and way to go unless you really have identified the need to do the real binary transfer (which is hardly often the case).

Convert MFC CString to integer

The simplest approach is to use the atoi() function found in stdlib.h:

CString s = "123";
int x = atoi( s );

However, this does not deal well with the case where the string does not contain a valid integer, in which case you should investigate the strtol() function:

CString s = "12zzz";    // bad integer
char * p;
int x = strtol ( s, & p, 10 );
if ( * p != 0 ) {
   // s does not contain an integer

String concatenation of two pandas columns

You could also use

df['bar'] = df['bar']['foo'].values.astype(str), sep=' is ')

How to set the From email address for mailx command?

You can use the "-r" option to set the sender address:

mailx -r [email protected] -s ...

Making a PowerShell POST request if a body param starts with '@'

Use Invoke-RestMethod to consume REST-APIs. Save the JSON to a string and use that as the body, ex:

$JSON = @'
 "username":"[email protected]",

$response = Invoke-RestMethod -Uri "" -Method Post -Body $JSON -ContentType "application/json"

If you use Powershell 3, I know there have been some issues with Invoke-RestMethod, but you should be able to use Invoke-WebRequest as a replacement:

$response = Invoke-WebRequest -Uri "" -Method Post -Body $JSON -ContentType "application/json"

If you don't want to write your own JSON every time, you can use a hashtable and use PowerShell to convert it to JSON before posting it. Ex.

$JSON = @{
    "@type" = "login"
    "username" = "[email protected]"
    "password" = "yyy"
} | ConvertTo-Json

The parameters dictionary contains a null entry for parameter 'id' of non-nullable type 'System.Int32'

Make the id parameter be a nullable int:

public ActionResult Edit(int? id, User collection)

And then add the validation:

if (Id == null) ...

How can I get the status code from an http error in Axios?

It's my code: Work for me

 var jsonData = request.body;
    var jsonParsed = JSON.parse(JSON.stringify(jsonData));

    // message_body = {
    //   "phone": "5511995001920",
    //   "body": "WhatsApp API on works good"
    // }, jsonParsed,validateStatus = true)
    .then((res) => {
      // console.log(`statusCode: ${res.statusCode}`)


        // var jsonData = res.body;
        // var jsonParsed = JSON.parse(JSON.stringify(jsonData));

    .catch((error) => {

What is a LAMP stack?

Linux, Apache, MySQL and PHP. free and open-source software. For example, an equivalent installation on the Microsoft Windows family of operating systems is known as WAMP. and for mac as MAMP. and XAMPP for both of them

copying all contents of folder to another folder using batch file?

@echo off
xcopy /s C:\yourfile C:\anotherfile\

This is how it is done! Simple, right?

How to create a box when mouse over text in pure CSS?

This is a small tweak on the other answers. If you have nested divs you can include more exciting content such as H1s in your popup.


div.appear {
    width: 250px; 
    border: #000 2px solid;
    position: relative;
    top: 5px;
    padding: 0 20px 20px 20px;
    z-index: 1000000;
div.hover  {
    width: 5px;
div.hover:hover div.appear {


<div class="hover">
<img src="questionmark.png"/>
    <div class="appear">
       <h1>My popup</h1>Hitherto and whenceforth.

The problem with these solutions is that everything after this in the page gets shifted when the popup is displayed, ie, the rest of the page jumps downwards to 'make space'. The only way I could fix this was by making position:absolute and removing the top and left CSS tags.

How do you change the width and height of Twitter Bootstrap's tooltips?

Just override bootstrap.css

The default value in BS2 is max-width:200px; So you can increase it with whatever fits your needs.

.tooltip-inner {
    max-width: 350px;
    /* If max-width does not work, try using width instead */
    width: 350px; 

MomentJS getting JavaScript Date in UTC

Or simply:

From MDN documentation:

The method returns the number of milliseconds elapsed since January 1, 1970

Available since ECMAScript 5.1

It's the same as was mentioned above (new Date().getTime()), but more shortcutted version.

Android Service needs to run always (Never pause or stop)

If you already have a service and want it to work all the time, you need to add 2 things:

  1. in the service itself:

    public int onStartCommand(Intent intent, int flags, int startId) {
        return START_STICKY;
  2. In the manifest:


No need to add bind unless you need it in the service.

Position: absolute and parent height?

This is a late answer, but by looking at the source code, I noticed that when the video is fullscreen, the "mejs-container-fullscreen" class is added to the "mejs-container" element. It is thus possible to change the styling based on this class.

.mejs-container.mejs-container-fullscreen {
    // This rule applies only to the container when in fullscreen
    padding-top: 57%;

Also, if you wish to make your MediaElement video fluid using CSS, below is a great trick by Chris Coyier:

Just add this to your CSS:

.mejs-container {
    width: 100% !important;
    height: auto !important;
    padding-top: 57%;
.mejs-overlay, .mejs-poster {
    width: 100% !important;
    height: 100% !important;
.mejs-mediaelement video {
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    width: 100% !important;
    height: 100% !important;

I hope it helps.

How can I delete multiple lines in vi?

You can delete multiple(range) lines if you know the line numbers:


Note: d stands for delete

start_line_no is the beginning line no you want to delete and end_line_no is the ending line no you want to delete. The lines between the start and end, including start and end will be deleted.



The lines between 45 and 101 including 45 and 101 will be deleted.

What are SP (stack) and LR in ARM?

SP is the stack register a shortcut for typing r13. LR is the link register a shortcut for r14. And PC is the program counter a shortcut for typing r15.

When you perform a call, called a branch link instruction, bl, the return address is placed in r14, the link register. the program counter pc is changed to the address you are branching to.

There are a few stack pointers in the traditional ARM cores (the cortex-m series being an exception) when you hit an interrupt for example you are using a different stack than when running in the foreground, you dont have to change your code just use sp or r13 as normal the hardware has done the switch for you and uses the correct one when it decodes the instructions.

The traditional ARM instruction set (not thumb) gives you the freedom to use the stack in a grows up from lower addresses to higher addresses or grows down from high address to low addresses. the compilers and most folks set the stack pointer high and have it grow down from high addresses to lower addresses. For example maybe you have ram from 0x20000000 to 0x20008000 you set your linker script to build your program to run/use 0x20000000 and set your stack pointer to 0x20008000 in your startup code, at least the system/user stack pointer, you have to divide up the memory for other stacks if you need/use them.

Stack is just memory. Processors normally have special memory read/write instructions that are PC based and some that are stack based. The stack ones at a minimum are usually named push and pop but dont have to be (as with the traditional arm instructions).

If you go to I created a teaching processor and have an assembly language tutorial. Somewhere in there I go through a discussion about stacks. It is NOT an arm processor but the story is the same it should translate directly to what you are trying to understand on the arm or most other processors.

Say for example you have 20 variables you need in your program but only 16 registers minus at least three of them (sp, lr, pc) that are special purpose. You are going to have to keep some of your variables in ram. Lets say that r5 holds a variable that you use often enough that you dont want to keep it in ram, but there is one section of code where you really need another register to do something and r5 is not being used, you can save r5 on the stack with minimal effort while you reuse r5 for something else, then later, easily, restore it.

Traditional (well not all the way back to the beginning) arm syntax:

stmdb r13!,{r5}
...temporarily use r5 for something else...
ldmia r13!,{r5}

stm is store multiple you can save more than one register at a time, up to all of them in one instruction.

db means decrement before, this is a downward moving stack from high addresses to lower addresses.

You can use r13 or sp here to indicate the stack pointer. This particular instruction is not limited to stack operations, can be used for other things.

The ! means update the r13 register with the new address after it completes, here again stm can be used for non-stack operations so you might not want to change the base address register, leave the ! off in that case.

Then in the brackets { } list the registers you want to save, comma separated.

ldmia is the reverse, ldm means load multiple. ia means increment after and the rest is the same as stm

So if your stack pointer were at 0x20008000 when you hit the stmdb instruction seeing as there is one 32 bit register in the list it will decrement before it uses it the value in r13 so 0x20007FFC then it writes r5 to 0x20007FFC in memory and saves the value 0x20007FFC in r13. Later, assuming you have no bugs when you get to the ldmia instruction r13 has 0x20007FFC in it there is a single register in the list r5. So it reads memory at 0x20007FFC puts that value in r5, ia means increment after so 0x20007FFC increments one register size to 0x20008000 and the ! means write that number to r13 to complete the instruction.

Why would you use the stack instead of just a fixed memory location? Well the beauty of the above is that r13 can be anywhere it could be 0x20007654 when you run that code or 0x20002000 or whatever and the code still functions, even better if you use that code in a loop or with recursion it works and for each level of recursion you go you save a new copy of r5, you might have 30 saved copies depending on where you are in that loop. and as it unrolls it puts all the copies back as desired. with a single fixed memory location that doesnt work. This translates directly to C code as an example:

void myfun ( void )
   int somedata;

In a C program like that the variable somedata lives on the stack, if you called myfun recursively you would have multiple copies of the value for somedata depending on how deep in the recursion. Also since that variable is only used within the function and is not needed elsewhere then you perhaps dont want to burn an amount of system memory for that variable for the life of the program you only want those bytes when in that function and free that memory when not in that function. that is what a stack is used for.

A global variable would not be found on the stack.

Going back...

Say you wanted to implement and call that function you would have some code/function you are in when you call the myfun function. The myfun function wants to use r5 and r6 when it is operating on something but it doesnt want to trash whatever someone called it was using r5 and r6 for so for the duration of myfun() you would want to save those registers on the stack. Likewise if you look into the branch link instruction (bl) and the link register lr (r14) there is only one link register, if you call a function from a function you will need to save the link register on each call otherwise you cant return.

bl myfun
    <--- the return from my fun returns here

stmdb sp!,{r5,r6,lr}
sub sp,#4 <--- make room for the somedata variable
some code here that uses r5 and r6
bl more_fun <-- this modifies lr, if we didnt save lr we wouldnt be able to return from myfun
   <---- more_fun() returns here
add sp,#4 <-- take back the stack memory we allocated for the somedata variable
ldmia sp!,{r5,r6,lr}
mov pc,lr <---- return to whomever called myfun.

So hopefully you can see both the stack usage and link register. Other processors do the same kinds of things in a different way. for example some will put the return value on the stack and when you execute the return function it knows where to return to by pulling a value off of the stack. Compilers C/C++, etc will normally have a "calling convention" or application interface (ABI and EABI are names for the ones ARM has defined). if every function follows the calling convention, puts parameters it is passing to functions being called in the right registers or on the stack per the convention. And each function follows the rules as to what registers it does not have to preserve the contents of and what registers it has to preserve the contents of then you can have functions call functions call functions and do recursion and all kinds of things, so long as the stack does not go so deep that it runs into the memory used for globals and the heap and such, you can call functions and return from them all day long. The above implementation of myfun is very similar to what you would see a compiler produce.

ARM has many cores now and a few instruction sets the cortex-m series works a little differently as far as not having a bunch of modes and different stack pointers. And when executing thumb instructions in thumb mode you use the push and pop instructions which do not give you the freedom to use any register like stm it only uses r13 (sp) and you cannot save all the registers only a specific subset of them. the popular arm assemblers allow you to use

push {r5,r6}
pop {r5,r6}

in arm code as well as thumb code. For the arm code it encodes the proper stmdb and ldmia. (in thumb mode you also dont have the choice as to when and where you use db, decrement before, and ia, increment after).

No you absolutly do not have to use the same registers and you dont have to pair up the same number of registers.

push {r5,r6,r7}
pop {r2,r3}
pop {r1}

assuming there is no other stack pointer modifications in between those instructions if you remember the sp is going to be decremented 12 bytes for the push lets say from 0x1000 to 0x0FF4, r5 will be written to 0xFF4, r6 to 0xFF8 and r7 to 0xFFC the stack pointer will change to 0x0FF4. the first pop will take the value at 0x0FF4 and put that in r2 then the value at 0x0FF8 and put that in r3 the stack pointer gets the value 0x0FFC. later the last pop, the sp is 0x0FFC that is read and the value placed in r1, the stack pointer then gets the value 0x1000, where it started.

The ARM ARM, ARM Architectural Reference Manual (, reference manuals, find the one for ARMv5 and download it, this is the traditional ARM ARM with ARM and thumb instructions) contains pseudo code for the ldm and stm ARM istructions for the complete picture as to how these are used. Likewise well the whole book is about the arm and how to program it. Up front the programmers model chapter walks you through all of the registers in all of the modes, etc.

If you are programming an ARM processor you should start by determining (the chip vendor should tell you, ARM does not make chips it makes cores that chip vendors put in their chips) exactly which core you have. Then go to the arm website and find the ARM ARM for that family and find the TRM (technical reference manual) for the specific core including revision if the vendor has supplied that (r2p0 means revision 2.0 (two point zero, 2p0)), even if there is a newer rev, use the manual that goes with the one the vendor used in their design. Not every core supports every instruction or mode the TRM tells you the modes and instructions supported the ARM ARM throws a blanket over the features for the whole family of processors that that core lives in. Note that the ARM7TDMI is an ARMv4 NOT an ARMv7 likewise the ARM9 is not an ARMv9. ARMvNUMBER is the family name ARM7, ARM11 without a v is the core name. The newer cores have names like Cortex and mpcore instead of the ARMNUMBER thing, which reduces confusion. Of course they had to add the confusion back by making an ARMv7-m (cortex-MNUMBER) and the ARMv7-a (Cortex-ANUMBER) which are very different families, one is for heavy loads, desktops, laptops, etc the other is for microcontrollers, clocks and blinking lights on a coffee maker and things like that. google beagleboard (Cortex-A) and the stm32 value line discovery board (Cortex-M) to get a feel for the differences. Or even the board which uses multiple cores at more than a gigahertz or the newer tegra 2 from nvidia, same deal super scaler, muti core, multi gigahertz. A cortex-m barely brakes the 100MHz barrier and has memory measured in kbytes although it probably runs of a battery for months if you wanted it to where a cortex-a not so much.

sorry for the very long post, hope it is useful.

Excel Date Conversion from yyyymmdd to mm/dd/yyyy

Do you have ROWS of data (horizontal) as you stated or COLUMNS (vertical)?

If it's the latter you can use "Text to columns" functionality to convert a whole column "in situ" - to do that:

Select column > Data > Text to columns > Next > Next > Choose "Date" under "column data format" and "YMD" from dropdown > Finish

....otherwise you can convert with a formula by using


and format in required date format

CSV in Python adding an extra carriage return, on Windows

Python 3:

The official csv documentation recommends opening the file with newline='' on all platforms to disable universal newlines translation:

with open('output.csv', 'w', newline='', encoding='utf-8') as f:
    writer = csv.writer(f)

The CSV writer terminates each line with the lineterminator of the dialect, which is \r\n for the default excel dialect on all platforms.

Python 2:

On Windows, always open your files in binary mode ("rb" or "wb"), before passing them to csv.reader or csv.writer.

Although the file is a text file, CSV is regarded a binary format by the libraries involved, with \r\n separating records. If that separator is written in text mode, the Python runtime replaces the \n with \r\n, hence the \r\r\n observed in the file.

See this previous answer.

round() for float in C++

Based on Kalaxy's response, the following is a templated solution that rounds any floating point number to the nearest integer type based on natural rounding. It also throws an error in debug mode if the value is out of range of the integer type, thereby serving roughly as a viable library function.

    // round a floating point number to the nearest integer
    template <typename Arg>
    int Round(Arg arg)
#ifndef NDEBUG
        // check that the argument can be rounded given the return type:
        if (
            (Arg)std::numeric_limits<int>::max() < arg + (Arg) 0.5) ||
            (Arg)std::numeric_limits<int>::lowest() > arg - (Arg) 0.5)
            throw std::overflow_error("out of bounds");

        return (arg > (Arg) 0.0) ? (int)(r + (Arg) 0.5) : (int)(r - (Arg) 0.5);

Android Facebook integration with invalid key hash

The following code will give you your hash for Facebook, but you have to follow these steps in order to get the release candidate hash.

  1. Copy and paste this code in your main activity

    try {
        PackageInfo info = getPackageManager().getPackageInfo(
        for (Signature signature : info.signatures) {
            MessageDigest md = MessageDigest.getInstance("SHA");
            Log.d("KeyHash:", Base64.encodeToString(md.digest(), Base64.DEFAULT));
    catch (NameNotFoundException e) {
    catch (NoSuchAlgorithmException e) {
  2. Generate a signed APK file.

  3. Connect your phone to a laptop and make sure it stays connected.
  4. Install and run the APK file in your phone by manually moving the release APK to your phone.
  5. Now look at Android LogCat (use filter KeyHash:). You should see your release hash key for Facebook. Simply copy and paste it in your It's under settings.
  6. Now you can test the app it should work perfectly well.

Best way to do a PHP switch with multiple values per case?

Put those many values into an array and query the array, as the switch-case seems to hide the underlying semantics of what you're trying to achieve when a string variable is used as the condition, making it harder to read and understand, e.g.:

$current_home = null;
$current_users = null;
$current_forum = null;

$lotsOfStrings = array('', 'users.location', 'users.featured', '');

if(empty($p)) {
    $current_home = 'current';

if(in_array($p,$lotsOfStrings)) {
    $current_users = 'current';

if(0 === strcmp('forum',$p)) {
    $current_forum = 'current';

C# if/then directives for debug vs release

If you are trying to use the variable defined for the build type you should remove the two lines ...

#define DEBUG  
#define RELEASE 

... these will cause the #if (DEBUG) to always be true.

Also there isn't a default Conditional compilation symbol for RELEASE. If you want to define one go to the project properties, click on the Build tab and then add RELEASE to the Conditional compilation symbols text box under the General heading.

The other option would be to do this...


How to execute a bash command stored as a string with quotes and asterisk

To eliminate the need for the cmd variable, you can do this:

eval 'mysql AMORE -u root --password="password" -h localhost -e "select host from amoreconfig"'

What does a lazy val do?

Also lazy is useful without cyclic dependencies, as in the following code:

abstract class X {
  val x: String
  println ("x is "+x.length)

object Y extends X { val x = "Hello" }

Accessing Y will now throw null pointer exception, because x is not yet initialized. The following, however, works fine:

abstract class X {
  val x: String
  println ("x is "+x.length)

object Y extends X { lazy val x = "Hello" }

EDIT: the following will also work:

object Y extends { val x = "Hello" } with X 

This is called an "early initializer". See this SO question for more details.

how to overcome ERROR 1045 (28000): Access denied for user 'ODBC'@'localhost' (using password: NO) permanently

for some reason, the ODBC user is the default username under windows even if you didn't create that user at setup time. simply typing


without specifying a username will attempt to connect with the non-existent ODBC username, and give:

Error 1045 (28000): Access denied for user 'ODBC'@'localhost' (using password: NO)

Instead, try specifying a username that you know, for example:

mysql -u root -p

where -u root specified the username root and -p will make the command prompt for a password.

MongoDB: How to find out if an array field contains an element?

It seems like the $in operator would serve your purposes just fine.

You could do something like this (pseudo-query):

if ({"students" : {"$in" : [studentId]}, "course" : courseId }).count() > 0) {
  // student is enrolled in class

Alternatively, you could remove the "course" : courseId clause and get back a set of all classes the student is enrolled in.

Simple Digit Recognition OCR in OpenCV-Python

OCR which stands for Optical Character Recognition is a computer vision technique used to identify the different types of handwritten digits that are used in common mathematics. To perform OCR in OpenCV we will use the KNN algorithm which detects the nearest k neighbors of a particular data point and then classifies that data point based on the class type detected for n neighbors.

Data Used

This data contains 5000 handwritten digits where there are 500 digits for every type of digit. Each digit is of 20×20 pixel dimensions. We will split the data such that 250 digits are for training and 250 digits are for testing for every class.

Below is the implementation.

import numpy as np
import cv2
# Read the image
image = cv2.imread('digits.png')
# gray scale conversion
gray_img = cv2.cvtColor(image,
# We will divide the image
# into 5000 small dimensions 
# of size 20x20
divisions = list(np.hsplit(i,100) for i in np.vsplit(gray_img,50))
# Convert into Numpy array
# of size (50,100,20,20)
NP_array = np.array(divisions)
# Preparing train_data
# and test_data.
# Size will be (2500,20x20)
train_data = NP_array[:,:50].reshape(-1,400).astype(np.float32)
# Size will be (2500,20x20)
test_data = NP_array[:,50:100].reshape(-1,400).astype(np.float32)
# Create 10 different labels 
# for each type of digit
k = np.arange(10)
train_labels = np.repeat(k,250)[:,np.newaxis]
test_labels = np.repeat(k,250)[:,np.newaxis]
# Initiate kNN classifier
knn =
# perform training of data
# obtain the output from the
# classifier by specifying the
# number of neighbors.
ret, output ,neighbours,
distance = knn.findNearest(test_data, k = 3)
# Check the performance and
# accuracy of the classifier.
# Compare the output with test_labels
# to find out how many are wrong.
matched = output==test_labels
correct_OP = np.count_nonzero(matched)
#Calculate the accuracy.
accuracy = (correct_OP*100.0)/(output.size)
# Display accuracy.



Well, I decided to workout myself on my question to solve the above problem. What I wanted is to implement a simple OCR using KNearest or SVM features in OpenCV. And below is what I did and how. (it is just for learning how to use KNearest for simple OCR purposes).

1) My first question was about file that comes with OpenCV samples. I wanted to know what is inside that file.

It contains a letter, along with 16 features of that letter.

And this SOF helped me to find it. These 16 features are explained in the paper Letter Recognition Using Holland-Style Adaptive Classifiers. (Although I didn't understand some of the features at the end)

2) Since I knew, without understanding all those features, it is difficult to do that method. I tried some other papers, but all were a little difficult for a beginner.

So I just decided to take all the pixel values as my features. (I was not worried about accuracy or performance, I just wanted it to work, at least with the least accuracy)

I took the below image for my training data:

enter image description here

(I know the amount of training data is less. But, since all letters are of the same font and size, I decided to try on this).

To prepare the data for training, I made a small code in OpenCV. It does the following things:

  1. It loads the image.
  2. Selects the digits (obviously by contour finding and applying constraints on area and height of letters to avoid false detections).
  3. Draws the bounding rectangle around one letter and wait for key press manually. This time we press the digit key ourselves corresponding to the letter in the box.
  4. Once the corresponding digit key is pressed, it resizes this box to 10x10 and saves all 100 pixel values in an array (here, samples) and corresponding manually entered digit in another array(here, responses).
  5. Then save both the arrays in separate .txt files.

At the end of the manual classification of digits, all the digits in the training data (train.png) are labeled manually by ourselves, image will look like below:

enter image description here

Below is the code I used for the above purpose (of course, not so clean):

import sys

import numpy as np
import cv2

im = cv2.imread('pitrain.png')
im3 = im.copy()

gray = cv2.cvtColor(im,cv2.COLOR_BGR2GRAY)
blur = cv2.GaussianBlur(gray,(5,5),0)
thresh = cv2.adaptiveThreshold(blur,255,1,1,11,2)

#################      Now finding Contours         ###################

contours,hierarchy = cv2.findContours(thresh,cv2.RETR_LIST,cv2.CHAIN_APPROX_SIMPLE)

samples =  np.empty((0,100))
responses = []
keys = [i for i in range(48,58)]

for cnt in contours:
    if cv2.contourArea(cnt)>50:
        [x,y,w,h] = cv2.boundingRect(cnt)
        if  h>28:
            roi = thresh[y:y+h,x:x+w]
            roismall = cv2.resize(roi,(10,10))
            key = cv2.waitKey(0)

            if key == 27:  # (escape to quit)
            elif key in keys:
                sample = roismall.reshape((1,100))
                samples = np.append(samples,sample,0)

responses = np.array(responses,np.float32)
responses = responses.reshape((responses.size,1))
print "training complete"


Now we enter in to training and testing part.

For the testing part, I used the below image, which has the same type of letters I used for the training phase.

enter image description here

For training we do as follows:

  1. Load the .txt files we already saved earlier
  2. create an instance of the classifier we are using (it is KNearest in this case)
  3. Then we use KNearest.train function to train the data

For testing purposes, we do as follows:

  1. We load the image used for testing
  2. process the image as earlier and extract each digit using contour methods
  3. Draw a bounding box for it, then resize it to 10x10, and store its pixel values in an array as done earlier.
  4. Then we use KNearest.find_nearest() function to find the nearest item to the one we gave. ( If lucky, it recognizes the correct digit.)

I included last two steps (training and testing) in single code below:

import cv2
import numpy as np

#######   training part    ############### 
samples = np.loadtxt('',np.float32)
responses = np.loadtxt('',np.float32)
responses = responses.reshape((responses.size,1))

model = cv2.KNearest()

############################# testing part  #########################

im = cv2.imread('pi.png')
out = np.zeros(im.shape,np.uint8)
gray = cv2.cvtColor(im,cv2.COLOR_BGR2GRAY)
thresh = cv2.adaptiveThreshold(gray,255,1,1,11,2)

contours,hierarchy = cv2.findContours(thresh,cv2.RETR_LIST,cv2.CHAIN_APPROX_SIMPLE)

for cnt in contours:
    if cv2.contourArea(cnt)>50:
        [x,y,w,h] = cv2.boundingRect(cnt)
        if  h>28:
            roi = thresh[y:y+h,x:x+w]
            roismall = cv2.resize(roi,(10,10))
            roismall = roismall.reshape((1,100))
            roismall = np.float32(roismall)
            retval, results, neigh_resp, dists = model.find_nearest(roismall, k = 1)
            string = str(int((results[0][0])))


And it worked, below is the result I got:

enter image description here

Here it worked with 100% accuracy. I assume this is because all the digits are of the same kind and the same size.

But anyway, this is a good start to go for beginners (I hope so).

IOError: [Errno 2] No such file or directory trying to open a file

I got this error and fixed by appending the directory path in the loop. script not in the same directory as the files. dr1 ="~/test" directory variable


Find a file in python

For fast, OS-independent search, use scandir

Read for details why.

How does Google reCAPTCHA v2 work behind the scenes?

This is speculation, but based on Google's reference to the "risk analysis engine" they use (

I would assume it looks at how you behaved prior to clicking, how your cursor moved on its way to the check (organic path/acceleration), which part of the checkbox was clicked (random places, or dead on center every time), browser fingerprint, Google cookies & contents, click location history tied to your fingerprint or account if it detects one etc.

It's fairly difficult to fake "organic" behavior in such a way that it would fool a continuously learning pattern detection engine. In the cases where it's not sure, it still prompts you to match an actual CAPTCHA string.

How to reload page the page with pagination in Angular 2?

This should technically be achievable using window.location.reload():


<button (click)="refresh()">Refresh</button>


refresh(): void {


Here is a basic StackBlitz example showing the refresh in action. Notice the URL on "/hello" path is retained when window.location.reload() is executed.

Return JSON with error status code MVC

The neatest solution I've found is to create your own JsonResult that extends the original implementation and allows you to specify a HttpStatusCode:

public class JsonHttpStatusResult : JsonResult
    private readonly HttpStatusCode _httpStatus;

    public JsonHttpStatusResult(object data, HttpStatusCode httpStatus)
        Data = data;
        _httpStatus = httpStatus;

    public override void ExecuteResult(ControllerContext context)
        context.RequestContext.HttpContext.Response.StatusCode = (int)_httpStatus;

You can then use this in your controller action like so:

    var errorModel = new { error = "There was an error" };
    return new JsonHttpStatusResult(errorModel, HttpStatusCode.InternalServerError);

Usage of \b and \r in C

The interpretation of the backspace and carriage return characters is left to the software you use for display. A terminal emulator, when displaying \b would move the cursor one step back, and when displaying \r to the beginning of the line. If you print these characters somewhere else, like a text file, the software may choose. to do something else.

How to Run the Procedure?

In SQL Plus:

EXEC gokul_proc(1,'GOKUL', :rc);
print rc

What does "make oldconfig" do exactly in the Linux kernel makefile?

From this page:

Make oldconfig takes the .config and runs it through the rules of the Kconfig files and produces a .config which is consistant with the Kconfig rules. If there are CONFIG values which are missing, the make oldconfig will ask for them.

If the .config is already consistant with the rules found in Kconfig, then make oldconfig is essentially a no-op.

If you were to run make oldconfig, and then run make oldconfig a second time, the second time won't cause any additional changes to be made.

Error: Cannot Start Container: stat /bin/sh: no such file or directory"

I had a similar problem:

docker: Error response from daemon: OCI runtime create failed: container_linux.go:346: starting container process caused "exec: \"sh\": executable file not found in $PATH": unknown.

In my case, I know the image works in other places, then was a corrupted local image. I solved the issue removing the image (docker rmi <imagename>) and pulling it again(docker pull <imagename>).

I did a docker system prune too, but I think it's not mandatory.

How to post pictures to instagram using API

If you read the link you shared, the accepted answer is:

You cannot post pictures to Instagram via the API.

Instagram have now said this:

Now you can post your content using Instagram APIs (New) effects from 26th Jan 2021 !

Hopefully you have some luck here.

Make flex items take content width, not width of parent container

In addtion to align-self you can also consider auto margin which will do almost the same thing

.container {_x000D_
  background: red;_x000D_
  height: 200px;_x000D_
  flex-direction: column;_x000D_
  padding: 10px;_x000D_
  display: flex;_x000D_
a {_x000D_
  padding: 10px 40px;_x000D_
  background: pink;_x000D_
<div class="container">_x000D_
  <a href="#">Test</a>_x000D_

How do I get the find command to print out the file size with the file name?

$ find . -name "test*" -exec du -sh {} \;
4.0K    ./test1
0       ./test2
0       ./test3
0       ./test4

Scripter World reference

How to instantiate, initialize and populate an array in TypeScript?

There isn't a field initialization syntax like that for objects in JavaScript or TypeScript.

Option 1:

class bar {
    // Makes a public field called 'length'
    constructor(public length: number) { }

bars = [ new bar(1) ];

Option 2:

interface bar {
    length: number;

bars = [ {length: 1} ];

Sending POST data without form

If you don't want your data to be seen by the user, use a PHP session.

Data in a post request is still accessible (and manipulable) by the user.

Checkout this tutorial on PHP Sessions.

Replace text in HTML page with jQuery

The html replace idea is good, but if done to the document.body, the page will blink and ads will disappear.

My solution:
$("*:contains('purrfect')").each(function() { var replaced = $(this).html().replace(/purrfect/g, "purrfect"); $(this).html(replaced); });

How to determine if a list of polygon points are in clockwise order?

Here is a simple C# implementation of the algorithm based on this answer.

Let's assume that we have a Vector type having X and Y properties of type double.

public bool IsClockwise(IList<Vector> vertices)
    double sum = 0.0;
    for (int i = 0; i < vertices.Count; i++) {
        Vector v1 = vertices[i];
        Vector v2 = vertices[(i + 1) % vertices.Count];
        sum += (v2.X - v1.X) * (v2.Y + v1.Y);
    return sum > 0.0;

% is the modulo or remainder operator performing the modulo operation which (according to Wikipedia) finds the remainder after division of one number by another.

Opening Android Settings programmatically

In case anyone finds this question and you want to open up settings for your specific application:

    val intent = Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS) = Uri.parse("package:" + context.packageName)

Run an exe from C# code


Process process = Process.Start(@"Data\myApp.exe");
int id = process.Id;
Process tempProc = Process.GetProcessById(id);
this.Visible = false;
this.Visible = true;

Download file from web in Python 3

from urllib import request

def get(url):
    with request.urlopen(url) as r:

def download(url, file=None):
    if not file:
        file = url.split('/')[-1]
    with open(file, 'wb') as f:

How to specify legend position in matplotlib in graph coordinates

The loc parameter specifies in which corner of the bounding box the legend is placed. The default for loc is loc="best" which gives unpredictable results when the bbox_to_anchor argument is used.
Therefore, when specifying bbox_to_anchor, always specify loc as well.

The default for bbox_to_anchor is (0,0,1,1), which is a bounding box over the complete axes. If a different bounding box is specified, is is usually sufficient to use the first two values, which give (x0, y0) of the bounding box.

Below is an example where the bounding box is set to position (0.6,0.5) (green dot) and different loc parameters are tested. Because the legend extents outside the bounding box, the loc parameter may be interpreted as "which corner of the legend shall be placed at position given by the 2-tuple bbox_to_anchor argument".

enter image description here

import matplotlib.pyplot as plt
plt.rcParams["figure.figsize"] = 6, 3
fig, axes = plt.subplots(ncols=3)
locs = ["upper left", "lower left", "center right"]
for l, ax in zip(locs, axes.flatten()):
    ax.plot([1,2,3],[2,3,1], "b-", label="blue")
    ax.plot([1,2,3],[1,2,1], "r-", label="red")
    ax.legend(loc=l, bbox_to_anchor=(0.6,0.5))
    ax.scatter((0.6),(0.5), s=81, c="limegreen", transform=ax.transAxes)


See especially this answer for a detailed explanation and the question What does a 4-element tuple argument for 'bbox_to_anchor' mean in matplotlib? .

If you want to specify the legend position in other coordinates than axes coordinates, you can do so by using the bbox_transform argument. If may make sense to use figure coordinates

ax.legend(bbox_to_anchor=(1,0), loc="lower right",  bbox_transform=fig.transFigure)

It may not make too much sense to use data coordinates, but since you asked for it this would be done via bbox_transform=ax.transData.

Detecting IE11 using CSS Capability/Feature Detection

You can use js and add a class in html to maintain the standard of conditional comments:

  var ua = navigator.userAgent,
      doc = document.documentElement;

  if ((ua.match(/MSIE 10.0/i))) {
    doc.className = doc.className + " ie10";

  } else if((ua.match(/rv:11.0/i))){
    doc.className = doc.className + " ie11";

Or use a lib like bowser:

Or modernizr for feature detection:

How do you get a list of the names of all files present in a directory in Node.js?

As of Node v10.10.0, it is possible to use the new withFileTypes option for fs.readdir and fs.readdirSync in combination with the dirent.isDirectory() function to filter for filenames in a directory. That looks like this:

fs.readdirSync('./dirpath', {withFileTypes: true})
.filter(item => !item.isDirectory())
.map(item =>

The returned array is in the form:

['file1.txt', 'file2.txt', 'file3.txt']

Docs for the fs.Dirent class

curl: (60) SSL certificate problem: unable to get local issuer certificate

Yes you need to add a CA certificate also. Adding a code snippet in Node.js for clear view.

var fs = require(fs)
var path = require('path')
var https = require('https')
var port = process.env.PORT || 8080;
var app = express();

key: fs.readFileSync(path.join(__dirname, './path to your private key/privkey.pem')),
cert: fs.readFileSync(path.join(__dirname, './path to your certificate/cert.pem')),
ca: fs.readFileSync(path.join(__dirname, './path to your CA file/chain.pem'))}, app).listen(port)

Programmatically Add CenterX/CenterY Constraints

If you don't care about this question being specifically about a tableview, and you'd just like to center one view on top of another view here's to do it:

    let horizontalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.CenterX, relatedBy: NSLayoutRelation.Equal, toItem: parentView, attribute: NSLayoutAttribute.CenterX, multiplier: 1, constant: 0)

    let verticalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.CenterY, relatedBy: NSLayoutRelation.Equal, toItem: parentView, attribute: NSLayoutAttribute.CenterY, multiplier: 1, constant: 0)

Multiple Inheritance in C#

Multiple inheritance is one of those things that generally causes more problems than it solves. In C++ it fits the pattern of giving you enough rope to hang yourself, but Java and C# have chosen to go the safer route of not giving you the option. The biggest problem is what to do if you inherit multiple classes that have a method with the same signature that the inheritee doesn't implement. Which class's method should it choose? Or should that not compile? There is generally another way to implement most things that doesn't rely on multiple inheritance.

Upper memory limit?

Not only are you reading the whole of each file into memory, but also you laboriously replicate the information in a table called list_of_lines.

You have a secondary problem: your choices of variable names severely obfuscate what you are doing.

Here is your script rewritten with the readlines() caper removed and with meaningful names:

file_A1_B1 = open("A1_B1_100000.txt", "r")
file_A2_B2 = open("A2_B2_100000.txt", "r")
file_A1_B2 = open("A1_B2_100000.txt", "r")
file_A2_B1 = open("A2_B1_100000.txt", "r")
file_write = open ("average_generations.txt", "w")
mutation_average = open("mutation_average", "w") # not used
files = [file_A2_B2,file_A2_B2,file_A1_B2,file_A2_B1]
for afile in files:
    table = []
    for aline in afile:
        values = aline.split('\t')
        values.remove('\n') # why?
    row_count = len(table)
    row0length = len(table[0])
    print_counter = 4
    for column_index in range(row0length):
        column_total = 0
        for row_index in range(row_count):
            number = float(table[row_index][column_index])
            column_total = column_total + number
        column_average = column_total/row_count
        print column_average
        if print_counter == 4:
            print_counter = 0
        print_counter +=1

It rapidly becomes apparent that (1) you are calculating column averages (2) the obfuscation led some others to think you were calculating row averages.

As you are calculating column averages, no output is required until the end of each file, and the amount of extra memory actually required is proportional to the number of columns.

Here is a revised version of the outer loop code:

for afile in files:
    for row_count, aline in enumerate(afile, start=1):
        values = aline.split('\t')
        values.remove('\n') # why?
        fvalues = map(float, values)
        if row_count == 1:
            row0length = len(fvalues)
            column_index_range = range(row0length)
            column_totals = fvalues
            assert len(fvalues) == row0length
            for column_index in column_index_range:
                column_totals[column_index] += fvalues[column_index]
    print_counter = 4
    for column_index in column_index_range:
        column_average = column_totals[column_index] / row_count
        print column_average
        if print_counter == 4:
            print_counter = 0
        print_counter +=1

Return a `struct` from a function in C

struct var e2 address pushed as arg to callee stack and values gets assigned there. In fact, get() returns e2's address in eax reg. This works like call by reference.

Visual Studio 2017 error: Unable to start program, An operation is not legal in the current state

Another solution you can try that worked for me when I received this error is to clean the solution, then do a rebuild. As the other solutions did not help me, I thought this might help someone else in the same boat.

Postgres: clear entire database before re-creating / re-populating from bash script

I'd just drop the database and then re-create it. On a UNIX or Linux system, that should do it:

$ dropdb development_db_name
$ createdb developmnent_db_name

That's how I do it, actually.

AngularJS custom filter function

Here's an example of how you'd use filter within your AngularJS JavaScript (rather than in an HTML element).

In this example, we have an array of Country records, each containing a name and a 3-character ISO code.

We want to write a function which will search through this list for a record which matches a specific 3-character code.

Here's how we'd do it without using filter:

$scope.FindCountryByCode = function (CountryCode) {
    //  Search through an array of Country records for one containing a particular 3-character country-code.
    //  Returns either a record, or NULL, if the country couldn't be found.
    for (var i = 0; i < $scope.CountryList.length; i++) {
        if ($scope.CountryList[i].IsoAlpha3 == CountryCode) {
            return $scope.CountryList[i];
    return null;

Yup, nothing wrong with that.

But here's how the same function would look, using filter:

$scope.FindCountryByCode = function (CountryCode) {
    //  Search through an array of Country records for one containing a particular 3-character country-code.
    //  Returns either a record, or NULL, if the country couldn't be found.

    var matches = $scope.CountryList.filter(function (el) { return el.IsoAlpha3 == CountryCode; })

    //  If 'filter' didn't find any matching records, its result will be an array of 0 records.
    if (matches.length == 0)
        return null;

    //  Otherwise, it should've found just one matching record
    return matches[0];

Much neater.

Remember that filter returns an array as a result (a list of matching records), so in this example, we'll either want to return 1 record, or NULL.

Hope this helps.

What is Bootstrap?

Bootstrap is an open-source Javascript framework developed by the team at Twitter. It is a combination of HTML, CSS, and Javascript code designed to help build user interface components. Bootstrap was also programmed to support both HTML5 and CSS3.

Also it is called Front-end-framework.

Bootstrap is a free collection of tools for creating a websites and web applications.

It contains HTML and CSS-based design templates for typography, forms, buttons, navigation and other interface components, as well as optional JavaScript extensions.

Some Reasons for programmers preferred Bootstrap Framework

  1. Easy to get started

  2. Great grid system

  3. Base styling for most HTML elements(Typography,Code,Tables,Forms,Buttons,Images,Icons)

  4. Extensive list of components

  5. Bundled Javascript plugins

Taken from About Bootstrap Framework

@Scope("prototype") bean scope not creating new bean

A protoype bean injected inside a singelton bean will behave like singelton untill expilictly called for creating a new instance by get bean.

context.getBean("Your Bean")

How can I search for a multiline pattern in a file?

You can use the grep alternative sift here (disclaimer: I am the author).

It support multiline matching and limiting the search to specific file types out of the box:

sift -m --files '*.py' 'YOUR_PATTERN'

(search all *.py files for the specified multiline regex pattern)

It is available for all major operating systems. Take a look at the samples page to see how it can be used to to extract multiline values from an XML file.

Iterating each character in a string using Python

You can also do the following:

txt = "Hello World!"
print (*txt, sep='\n')

This does not use loops but internally print statement takes care of it.

* unpacks the string into a list and sends it to the print statement

sep='\n' will ensure that the next char is printed on a new line

The output will be:


If you do need a loop statement, then as others have mentioned, you can use a for loop like this:

for x in txt: print (x)

Decompile .smali files on an APK

I second that.

Dex2jar will generate a WORKING jar, which you can add as your project source, with the xmls you got from apktool.

However, JDGUI generates .java files which have ,more often than not, errors.

It has got something to do with code obfuscation I guess.

react change class name on state change

Below is a fully functional example of what I believe you're trying to do (with a functional snippet).


Based on your question, you seem to be modifying 1 property in state for all of your elements. That's why when you click on one, all of them are being changed.

In particular, notice that the state tracks an index of which element is active. When MyClickable is clicked, it tells the Container its index, Container updates the state, and subsequently the isActive property of the appropriate MyClickables.


class Container extends React.Component {_x000D_
  state = {_x000D_
    activeIndex: null_x000D_
  handleClick = (index) => this.setState({ activeIndex: index })_x000D_
  render() {_x000D_
    return <div>_x000D_
      <MyClickable name="a" index={0} isActive={ this.state.activeIndex===0 } onClick={ this.handleClick } />_x000D_
      <MyClickable name="b" index={1} isActive={ this.state.activeIndex===1 } onClick={ this.handleClick }/>_x000D_
      <MyClickable name="c" index={2} isActive={ this.state.activeIndex===2 } onClick={ this.handleClick }/>_x000D_
class MyClickable extends React.Component {_x000D_
  handleClick = () => this.props.onClick(this.props.index)_x000D_
  render() {_x000D_
    return <button_x000D_
        this.props.isActive ? 'active' : 'album'_x000D_
      onClick={ this.handleClick }_x000D_
      <span>{ }</span>_x000D_
ReactDOM.render(<Container />, document.getElementById('app'))
button {_x000D_
  display: block;_x000D_
  margin-bottom: 1em;_x000D_
.album>span:after {_x000D_
  content: ' (an album)';_x000D_
.active {_x000D_
  font-weight: bold;_x000D_
.active>span:after {_x000D_
  content: ' ACTIVE';_x000D_
<script src=""></script>_x000D_
<script src=""></script>_x000D_
<div id="app"></div>

Update: "Loops"

In response to a comment about a "loop" version, I believe the question is about rendering an array of MyClickable elements. We won't use a loop, but map, which is typical in React + JSX. The following should give you the same result as above, but it works with an array of elements.

// New render method for `Container`
render() {
  const clickables = [
    { name: "a" },
    { name: "b" },
    { name: "c" },

  return <div>
      {, i) {
          return <MyClickable key={ }
            name={ }
            index={ i }
            isActive={ this.state.activeIndex === i }
            onClick={ this.handleClick }
        } )

How to find out the number of CPUs using python

multiprocessing.cpu_count() will return the number of logical CPUs, so if you have a quad-core CPU with hyperthreading, it will return 8. If you want the number of physical CPUs, use the python bindings to hwloc:

#!/usr/bin/env python
import hwloc
topology = hwloc.Topology()
print topology.get_nbobjs_by_type(hwloc.OBJ_CORE)

hwloc is designed to be portable across OSes and architectures.

java.lang.UnsatisfiedLinkError: dalvik.system.PathClassLoader

I use Android Studio 3.0 and encounter this problem. And I'm sure app's build.gradle is OK.

Go to Run -> Edit Configurations -> Profiling, and disable "Enable advanced profiling".

This works for me. Reference answer

C# string does not contain possible?

This should do the trick for you.

For one word:

if (!string.Contains("One"))

For two words:

if (!(string.Contains("One") && string.Contains("Two")))

Comparing strings in C# with OR in an if statement

use if (testString.Equals(testString2)).

Checking something isEmpty in Javascript?

Check for undefined:

if (typeof == "undefined")
    // do something

This would do the equivelant of vb's IsEmpty. If myvar contains any value, even null, empty string, or 0, it is not "empty".

To check if a variable or property exists, eg it's been declared, though it may be not have been defined, you can use the in operator.

if ("photo" in response)
    // do something

In what cases will HTTP_REFERER be empty

It will also be empty if the new Referrer Policy standard draft is used to prevent that the referer header is sent to the request origin. Example:

<meta name="referrer" content="none">

Although Chrome and Firefox have already implemented a draft version of the Referrer Policy, you should be careful with it because for example Chrome expects no-referrer instead of none (and I have seen also never somewhere).

Deep-Learning Nan loss reasons

The reason for nan, inf or -inf often comes from the fact that division by 0.0 in TensorFlow doesn't result in a division by zero exception. It could result in a nan, inf or -inf "value". In your training data you might have 0.0 and thus in your loss function it could happen that you perform a division by 0.0.

a = tf.constant([2., 0., -2.])
b = tf.constant([0., 0., 0.])
c = tf.constant([1., 1., 1.])
print((a / b) + c)

Output is the following tensor:

tf.Tensor([ inf  nan -inf], shape=(3,), dtype=float32)

Adding a small eplison (e.g., 1e-5) often does the trick. Additionally, since TensorFlow 2 the opteration tf.math.division_no_nan is defined.

How to convert a string to an integer in JavaScript?

Though an old question, but maybe this can be helpful to someone.

I use this way of converting string to int number

var str = "25";       // string
var number = str*1;   // number

So, when multiplying by 1, the value does not change, but js automatically returns a number.

But as it is shown below, this should be used if you are sure that the str is a number(or can be represented as a number), otherwise it will return NaN - not a number.

you can create simple function to use, e.g.

function toNumber(str) {
   return str*1;

enter image description here

Laravel 5 call a model function in a blade view

You can pass it to view but first query it in controller, and then after that add this :

return view('yourview', COMPACT('variabelnametobepassedtoview'));

JFrame background image

I used a very similar method to @bott, but I modified it a little bit to make there be no need to resize the image:

BufferedImage img = null;
try {
    img = File("image.jpg"));
} catch (IOException e) {
Image dimg = img.getScaledInstance(800, 508, Image.SCALE_SMOOTH);
ImageIcon imageIcon = new ImageIcon(dimg);
setContentPane(new JLabel(imageIcon));

Works every time. You can also get the width and height of the jFrame and use that in place of the 800 and 508 respectively.

Jquery, checking if a value exists in array or not

if ($.inArray('example', myArray) != -1)
  // found it

How to get evaluated attributes inside a custom directive

var myApp = angular.module('myApp',[]);

myApp .directive('myDirective', function ($timeout) {
    return function (scope, element, attr) {
            element.val("value = "+attr.value);


function MyCtrl($scope) {


Use $timeout because directive call after dom load so your changes doesn`'t apply

displaying a string on the textview when clicking a button in android

Just check your code in .java class

You had written below line


before initializing the mybtn object I mean

mybtn = (Button)findViewById(;

just switch this two line or put that line "mybtn.setOnClickListener(this)" after initializing your mybtn object and you will get the answer what you want..

What's the most efficient way to test two integer ranges for overlap?

Here's my version:

int xmin = min(x1,x2)
  , xmax = max(x1,x2)
  , ymin = min(y1,y2)
  , ymax = max(y1,y2);

for (int i = xmin; i < xmax; ++i)
    if (ymin <= i && i <= ymax)
        return true;

return false;

Unless you're running some high-performance range-checker on billions of widely-spaced integers, our versions should perform similarly. My point is, this is micro-optimization.

Split value from one field to two

In case someone needs to run over a table and split a field:

  1. First we use the function mention above:
CREATE DEFINER=`root`@`localhost` FUNCTION `fn_split_str`($str VARCHAR(800), $delimiter VARCHAR(12), $position INT) RETURNS varchar(800) CHARSET utf8
                SUBSTRING_INDEX($str, $delimiter, $position),
                    SUBSTRING_INDEX($str, $delimiter, $position -1)
                ) + 1
    $delimiter, '');
  1. Second, we run in a while loop on the string until there isn't any results (I've added $id for JOIN clause):
CREATE DEFINER=`root`@`localhost` FUNCTION `fn_split_str_to_rows`($id INT, $str VARCHAR(800), $delimiter VARCHAR(12), $empty_table BIT) RETURNS int(11)

    DECLARE position INT;
    DECLARE val VARCHAR(800);
    SET position = 1;
    IF $empty_table THEN
        DROP TEMPORARY TABLE IF EXISTS tmp_rows;    
    END IF;
    SET val = fn_split_str($str, ',', position);
    CREATE TEMPORARY TABLE IF NOT EXISTS tmp_rows AS (SELECT $id as id, val as val where 1 = 2);
    WHILE (val IS NOT NULL and val != '') DO               
        INSERT INTO tmp_rows
        SELECT $id, val;
        SET position = position + 1;
        SET val = fn_split_str($str, ',', position);
    RETURN position - 1;
  1. Finally we can use it like that:
SELECT  SUM(fn_split_str_to_rows(ID, FieldToSplit, ',', 0))
FROM    MyTable;

SELECT * FROM tmp_rows;

You can use the id to join to other table.

In case you are only splitting one value you can use it like that

SELECT  fn_split_str_to_rows(null, 'AAA,BBB,CCC,DDD,EEE,FFF,GGG', ',', 1);
SELECT * FROM tmp_rows;

We don't need to empty the temporary table, the function will take care of that.

Where can I find the TypeScript version installed in Visual Studio?

You can do npm list | grep typescript if it's installed through npm.

Tomcat is not deploying my web project from Eclipse

SOLVED: I faced this error and i cant understand, it took 5 hours.

Solution: project properties/Project faced/Dynamic web-module version set to 3.0

after one week ,I got same error

FIXED2 gwt-project-external-mode-main-main-nocache-js-not-found

Create a batch file to run an .exe with an additional parameter

You can use

start "" "%USERPROFILE%\Desktop\BGInfo\bginfo.exe" "%USERPROFILE%\Desktop\BGInfo\dc_bginfo.bgi"


start "" /D "%USERPROFILE%\Desktop\BGInfo" bginfo.exe dc_bginfo.bgi


"%USERPROFILE%\Desktop\BGInfo\bginfo.exe" "%USERPROFILE%\Desktop\BGInfo\dc_bginfo.bgi"


cd /D "%USERPROFILE%\Desktop\BGInfo"
bginfo.exe dc_bginfo.bgi

Help on commands start and cd is output by executing in a command prompt window help start or start /? and help cd or cd /?.

But I do not understand why you need a batch file at all for starting the application with the additional parameter. Create a shortcut (*.lnk) on your desktop for this application. Then right click on the shortcut, left click on Properties and append after a space character "%USERPROFILE%\Desktop\BGInfo\dc_bginfo.bgi" as parameter.

C-like structures in Python

dF: that's pretty cool... I didn't know that I could access the fields in a class using dict.

Mark: the situations that I wish I had this are precisely when I want a tuple but nothing as "heavy" as a dictionary.

You can access the fields of a class using a dictionary because the fields of a class, its methods and all its properties are stored internally using dicts (at least in CPython).

...Which leads us to your second comment. Believing that Python dicts are "heavy" is an extremely non-pythonistic concept. And reading such comments kills my Python Zen. That's not good.

You see, when you declare a class you are actually creating a pretty complex wrapper around a dictionary - so, if anything, you are adding more overhead than by using a simple dictionary. An overhead which, by the way, is meaningless in any case. If you are working on performance critical applications, use C or something.

jQuery - hashchange event

Here is updated version of @johnny.rodgers

Hope helps someone.

// ie9 ve ie7 return true but never fire, lets remove ie less then 10
if(("onhashchange" in window) && navigator.userAgent.toLowerCase().indexOf('msie') == -1){ // event supported?
    window.onhashchange = function(){
        var url = window.location.hash.substring(1);
else{ // event not supported:
    var storedhash = window.location.hash;
        if(window.location.hash != storedhash){
            storedhash = window.location.hash;
    }, 100);

Angular (4, 5, 6, 7) - Simple example of slide in out animation on ngIf

The most upvoted answer is not implementing a real slide in/out (or down/up), as:

  1. It's not doing a soft transition on the height attribute. At time zero the element already has the 100% of its height producing a sudden glitch on the elements below it.
  2. When sliding out/up, the element does a translateY(-100%) and then suddenly disappears, causing another glitch on the elements below it.

You can implement a slide in and slide out like so:


import { animate, style, transition, trigger } from '@angular/animations';

  animations: [
    trigger('slideDownUp', [
      transition(':enter', [style({ height: 0 }), animate(500)]),
      transition(':leave', [animate(500, style({ height: 0 }))]),


<div @slideDownUp *ngIf="isShowing" class="box">
  I am the content of the div!


.box {
  overflow: hidden;

Using Spring RestTemplate in generic method with generic parameter

My own implementation of generic restTemplate call:

private <REQ, RES> RES queryRemoteService(String url, HttpMethod method, REQ req, Class reqClass) {
    RES result = null;
    try {
        long startMillis = System.currentTimeMillis();

        // Set the Content-Type header
        HttpHeaders requestHeaders = new HttpHeaders();
        requestHeaders.setContentType(new MediaType("application","json"));            

        // Set the request entity
        HttpEntity<REQ> requestEntity = new HttpEntity<>(req, requestHeaders);

        // Create a new RestTemplate instance
        RestTemplate restTemplate = new RestTemplate();

        // Add the Jackson and String message converters
        restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
        restTemplate.getMessageConverters().add(new StringHttpMessageConverter());

        // Make the HTTP POST request, marshaling the request to JSON, and the response to a String
        ResponseEntity<RES> responseEntity =, method, requestEntity, reqClass);
        result = responseEntity.getBody();
        long stopMillis = System.currentTimeMillis() - startMillis;

        Log.d(TAG, method + ":" + url + " took " + stopMillis + " ms");
    } catch (Exception e) {
         Log.e(TAG, e.getMessage());
    return result;

To add some context, I'm consuming RESTful service with this, hence all requests and responses are wrapped into small POJO like this:

public class ValidateRequest {
  User user;
  User checkedUser;
  Vehicle vehicle;


public class UserResponse {
  User user;
  RequestResult requestResult;

Method which calls this is the following:

public User checkUser(User user, String checkedUserName) {
    String url = urlBuilder()

    ValidateRequest request = new ValidateRequest();
    request.setCheckedUser(new User(checkedUserName));

    UserResponse response = queryRemoteService(url, HttpMethod.POST, request, UserResponse.class);
    return response.getUser();

And yes, there's a List dto-s as well.

Does Java have something like C#'s ref and out keywords?

Direct answer: No

But you can simulate reference with wrappers.

And do the following:

void changeString( _<String> str ) {

void testRef() {
     _<String> abc = new _<String>("abc");
     changeString( abc );
     out.println( abc ); // prints def


void setString( _<String> ref ) {
    str.s( "def" );
void testOut(){
    _<String> abc = _<String>();
    setString( abc );
    out.println(abc); // prints def

And basically any other type such as:

_<Integer> one = new <Integer>(1);
addOneTo( one );

out.println( one ); // May print 2

CSS Display an Image Resized and Cropped

In the crop class, place the image size that you want to appear:

.crop {
    width: 282px;
    height: 282px;
    overflow: hidden;
.crop span.img {
    background-position: center;
    background-size: cover;
    height: 282px;
    display: block;

The html will look like:

<div class="crop">
    <span class="img" style="background-image:url('');"></span>

How can I iterate through a string and also know the index (current position)?

You can use standard STL function distance as mentioned before

index = std::distance(s.begin(), it);

Also, you can access string and some other containers with the c-like interface:

for (i=0;i<string1.length();i++) string1[i];

Split string into array

Use the .split() method. When specifying an empty string as the separator, the split() method will return an array with one element per character.

entry = prompt("Enter your name")
entryArray = entry.split("");

How to discard uncommitted changes in SourceTree?

From sourcetree gui click on working directoy, right-click the file(s) that you want to discard, then click on Discard

HTML5 pattern for formatting input box to take date mm/dd/yyyy?


This is pattern to enter the date for textbox in HTML5.
The first one[0-9]{1,2} will take only decimal number minimum 1 and maximum 2.
And other similarly.

How do I get a string format of the current date time, in python?

If you don't care about formatting and you just need some quick date, you can use this:

import time

Warning: Permanently added the RSA host key for IP address

The IP addresses have changed again.

github publishes the list of used IP addresses here so you can check the IP address in your message against github's list:

Or more precisely:

It looks like this (as I write this answer!):

verifiable_password_authentication  true
github_services_sha "4159703d573ee6f602e304ed25b5862463a2c73d"
0   ""
1   ""
0   ""
1   ""
2   ""
3   ""
4   ""
0   ""
1   ""
0   ""
1   ""
2   ""

If you are unsure whether your IP address is contained in the above list use an CIDR calculator like to show the valid IP range.

E. g. for the IP range is -

How do I write to the console from a Laravel Controller?

If you want to log to STDOUT you can use any of the ways Laravel provides; for example (from wired00's answer):

Log::info('This is some useful information.');

The STDOUT magic can be done with the following (you are setting the file where info messages go):

Log::useFiles('php://stdout', 'info');

Word of caution: this is strictly for debugging. Do no use anything in production you don't fully understand.

Oracle Installer:[INS-13001] Environment does not meet minimum requirements

To make @Raghavendra's answer more specific:

Once you've downloaded 2 zip files,

copy ALL the contents of " -> Database -> Stage -> Components" folder to " -> Database -> Stage -> Components" folder.

You'll still get the same warning, however, the installation will run completely without generating any errors.

Running multiple AsyncTasks at the same time -- not possible?

Making @sulai suggestion more generic :

public static <T> void executeAsyncTask(AsyncTask<T, ?, ?> asyncTask, T... params) {
        asyncTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, params);

Add querystring parameters to link_to

The API docs on link_to show some examples of adding querystrings to both named and oldstyle routes. Is this what you want?

link_to can also produce links with anchors or query strings:

link_to "Comment wall", profile_path(@profile, :anchor => "wall")
#=> <a href="/profiles/1#wall">Comment wall</a>

link_to "Ruby on Rails search", :controller => "searches", :query => "ruby on rails"
#=> <a href="/searches?query=ruby+on+rails">Ruby on Rails search</a>

link_to "Nonsense search", searches_path(:foo => "bar", :baz => "quux")
#=> <a href="/searches?foo=bar&amp;baz=quux">Nonsense search</a>

Javascript format date / time

I don't think that can be done RELIABLY with built in methods on the native Date object. The toLocaleString method gets close, but if I am remembering correctly, it won't work correctly in IE < 10. If you are able to use a library for this task, MomentJS is a really amazing library; and it makes working with dates and times easy. Otherwise, I think you will have to write a basic function to give you the format that you are after.

function formatDate(date) {
    var year = date.getFullYear(),
        month = date.getMonth() + 1, // months are zero indexed
        day = date.getDate(),
        hour = date.getHours(),
        minute = date.getMinutes(),
        second = date.getSeconds(),
        hourFormatted = hour % 12 || 12, // hour returned in 24 hour format
        minuteFormatted = minute < 10 ? "0" + minute : minute,
        morning = hour < 12 ? "am" : "pm";

    return month + "/" + day + "/" + year + " " + hourFormatted + ":" +
            minuteFormatted + morning;

How to add a browser tab icon (favicon) for a website?

I haven't used any others, but seems to be a top choice, and it hasn't been mentioned on here yet.

It supports SVGs as source images for generating favicons, and it provides helpful options to override images for different platforms. In addition, by default it doesn't generate a ton a images to be backwards-compatible with every outdated platform. Instead, it gives you options to check if you want them.

From an email the developer sent me, they also have plans to add support for generating SVG favicons, as well as SVG theme-sensitivity, I think, which is a totally awesome feature.

SOAP or REST for Web Services?

REST is a fundamentally different paradigm from SOAP. A good read on REST can be found here: How I explained REST to my wife.

If you don't have time to read it, here's the short version: REST is a bit of a paradigm shift by focusing on "nouns", and restraining the number of "verbs" you can apply to those nouns. The only allowed verbs are "get", "put", "post" and "delete". This differs from SOAP where many different verbs can be applied to many different nouns (i.e. many different functions).

For REST, the four verbs map to the corresponding HTTP requests, while the nouns are identified by URLs. This makes state management much more transparent than in SOAP, where its often unclear what state is on the server and what is on the client.

In practice though most of this falls away, and REST usually just refers to simple HTTP requests that return results in JSON, while SOAP is a more complex API that communicates by passing XML around. Both have their advantages and disadvantages, but I've found that in my experience REST is usually the better choice because you rarely if ever need the full functionality you get from SOAP.

What can <f:metadata>, <f:viewParam> and <f:viewAction> be used for?

Process GET parameters

The <f:viewParam> manages the setting, conversion and validation of GET parameters. It's like the <h:inputText>, but then for GET parameters.

The following example

    <f:viewParam name="id" value="#{}" />

does basically the following:

  • Get the request parameter value by name id.
  • Convert and validate it if necessary (you can use required, validator and converter attributes and nest a <f:converter> and <f:validator> in it like as with <h:inputText>)
  • If conversion and validation succeeds, then set it as a bean property represented by #{} value, or if the value attribute is absent, then set it as request attribtue on name id so that it's available by #{id} in the view.

So when you open the page as foo.xhtml?id=10 then the parameter value 10 get set in the bean this way, right before the view is rendered.

As to validation, the following example sets the param to required="true" and allows only values between 10 and 20. Any validation failure will result in a message being displayed.

    <f:viewParam id="id" name="id" value="#{}" required="true">
        <f:validateLongRange minimum="10" maximum="20" />
<h:message for="id" />

Performing business action on GET parameters

You can use the <f:viewAction> for this.

    <f:viewParam id="id" name="id" value="#{}" required="true">
        <f:validateLongRange minimum="10" maximum="20" />
    <f:viewAction action="#{bean.onload}" />
<h:message for="id" />


public void onload() {
    // ...

The <f:viewAction> is however new since JSF 2.2 (the <f:viewParam> already exists since JSF 2.0). If you can't upgrade, then your best bet is using <f:event> instead.

<f:event type="preRenderView" listener="#{bean.onload}" />

This is however invoked on every request. You need to explicitly check if the request isn't a postback:

public void onload() {
    if (!FacesContext.getCurrentInstance().isPostback()) {
        // ...

When you would like to skip "Conversion/Validation failed" cases as well, then do as follows:

public void onload() {
    FacesContext facesContext = FacesContext.getCurrentInstance();
    if (!facesContext.isPostback() && !facesContext.isValidationFailed()) {
        // ...

Using <f:event> this way is in essence a workaround/hack, that's exactly why the <f:viewAction> was introduced in JSF 2.2.

Pass view parameters to next view

You can "pass-through" the view parameters in navigation links by setting includeViewParams attribute to true or by adding includeViewParams=true request parameter.

<h:link outcome="next" includeViewParams="true">
<!-- Or -->
<h:link outcome="next?includeViewParams=true">

which generates with the above <f:metadata> example basically the following link

<a href="next.xhtml?id=10">

with the original parameter value.

This approach only requires that next.xhtml has also a <f:viewParam> on the very same parameter, otherwise it won't be passed through.

Use GET forms in JSF

The <f:viewParam> can also be used in combination with "plain HTML" GET forms.

    <f:viewParam id="query" name="query" value="#{bean.query}" />
    <f:viewAction action="#{}" />
    <label for="query">Query</label>
    <input type="text" name="query" value="#{empty bean.query ? param.query : bean.query}" />
    <input type="submit" value="Search" />
    <h:message for="query" />
<h:dataTable value="#{bean.results}" var="result" rendered="#{not empty bean.results}">

With basically this @RequestScoped bean:

private String query;
private List<Result> results;

public void search() {
    results =;

Note that the <h:message> is for the <f:viewParam>, not the plain HTML <input type="text">! Also note that the input value displays #{param.query} when #{bean.query} is empty, because the submitted value would otherwise not show up at all when there's a validation or conversion error. Please note that this construct is invalid for JSF input components (it is doing that "under the covers" already).

See also:

psql: FATAL: database "<user>" does not exist

Had the same problem, a simple psql -d postgres did it (Type the command in the terminal)

REST API Best practices: Where to put parameters?

"Pack" and POST your data against the "context" that universe-resource-locator provides, which means #1 for the sake of the locator.

Mind the limitations with #2. I prefer POSTs to #1.

note: limitations are discussed for

POST in Is there a max size for POST parameter content?

GET in Is there a limit to the length of a GET request? and Max size of URL parameters in _GET

p.s. these limits are based on the client capabilities (browser) and server(configuration).

Subtract a value from every number in a list in Python?

You can use map() function:

a = list(map(lambda x: x - 13, a))

Regular expression to match standard 10 digit phone number


why should I make a copy of a data frame in pandas

The primary purpose is to avoid chained indexing and eliminate the SettingWithCopyWarning.

Here chained indexing is something like dfc['A'][0] = 111

The document said chained indexing should be avoided in Returning a view versus a copy. Here is a slightly modified example from that document:

In [1]: import pandas as pd

In [2]: dfc = pd.DataFrame({'A':['aaa','bbb','ccc'],'B':[1,2,3]})

In [3]: dfc
    A   B
0   aaa 1
1   bbb 2
2   ccc 3

In [4]: aColumn = dfc['A']

In [5]: aColumn[0] = 111
A value is trying to be set on a copy of a slice from a DataFrame

In [6]: dfc
    A   B
0   111 1
1   bbb 2
2   ccc 3

Here the aColumn is a view and not a copy from the original DataFrame, so modifying aColumn will cause the original dfc be modified too. Next, if we index the row first:

In [7]: zero_row = dfc.loc[0]

In [8]: zero_row['A'] = 222
A value is trying to be set on a copy of a slice from a DataFrame

In [9]: dfc
    A   B
0   111 1
1   bbb 2
2   ccc 3

This time zero_row is a copy, so the original dfc is not modified.

From these two examples above, we see it's ambiguous whether or not you want to change the original DataFrame. This is especially dangerous if you write something like the following:

In [10]: dfc.loc[0]['A'] = 333
A value is trying to be set on a copy of a slice from a DataFrame

In [11]: dfc
    A   B
0   111 1
1   bbb 2
2   ccc 3

This time it didn't work at all. Here we wanted to change dfc, but we actually modified an intermediate value dfc.loc[0] that is a copy and is discarded immediately. It’s very hard to predict whether the intermediate value like dfc.loc[0] or dfc['A'] is a view or a copy, so it's not guaranteed whether or not original DataFrame will be updated. That's why chained indexing should be avoided, and pandas generates the SettingWithCopyWarning for this kind of chained indexing update.

Now is the use of .copy(). To eliminate the warning, make a copy to express your intention explicitly:

In [12]: zero_row_copy = dfc.loc[0].copy()

In [13]: zero_row_copy['A'] = 444 # This time no warning

Since you are modifying a copy, you know the original dfc will never change and you are not expecting it to change. Your expectation matches the behavior, then the SettingWithCopyWarning disappears.

Note, If you do want to modify the original DataFrame, the document suggests you use loc:

In [14]: dfc.loc[0,'A'] = 555

In [15]: dfc
    A   B
0   555 1
1   bbb 2
2   ccc 3

Is it possible to get the index you're sorting over in Underscore.js?

When available, I believe that most lodash array functions will show the iteration. But sorting isn't really an iteration in the same way: when you're on the number 66, you aren't processing the fourth item in the array until it's finished. A custom sort function will loop through an array a number of times, nudging adjacent numbers forward or backward, until the everything is in its proper place.

Reading settings from app.config or web.config in .NET

I always create an IConfig interface with typesafe properties declared for all configuration values. A Config implementation class then wraps the calls to System.Configuration. All your System.Configuration calls are now in one place, and it is so much easier and cleaner to maintain and track which fields are being used and declare their default values. I write a set of private helper methods to read and parse common data types.

Using an IoC framework you can access the IConfig fields anywhere your in application by simply passing the interface to a class constructor. You're also then able to create mock implementations of the IConfig interface in your unit tests so you can now test various configuration values and value combinations without needing to touch your App.config or Web.config file.

Click to call html

tl;dr What to do in modern (2018) times? Assume tel: is supported, use it and forget about anything else.

The tel: URI scheme RFC5431 (as well as sms: but also feed:, maps:, youtube: and others) is handled by protocol handlers (as mailto: and http: are).

They're unrelated to HTML5 specification (it has been out there from 90s and documented first time back in 2k with RFC2806) then you can't check for their support using tools as modernizr. A protocol handler may be installed by an application (for example Skype installs a callto: protocol handler with same meaning and behaviour of tel: but it's not a standard), natively supported by browser or installed (with some limitations) by website itself.

What HTML5 added is support for installing custom web based protocol handlers (with registerProtocolHandler() and related functions) simplifying also the check for their support through isProtocolHandlerRegistered() function.

There is some easy ways to determine if there is an handler or not:" How to detect browser's protocol handlers?).

In general what I suggest is:

  1. If you're running on a mobile device then you can safely assume tel: is supported (yes, it's not true for very old devices but IMO you can ignore them).
  2. If JS isn't active then do nothing.
  3. If you're running on desktop browsers then you can use one of the techniques in the linked post to determine if it's supported.
  4. If tel: isn't supported then change links to use callto: and repeat check desctibed in 3.
  5. If tel: and callto: aren't supported (or - in a desktop browser - you can't detect their support) then simply remove that link replacing URL in href with javascript:void(0) and (if number isn't repeated in text span) putting, telephone number in title. Here HTML5 microdata won't help users (just search engines). Note that newer versions of Skype handle both callto: and tel:.

Please note that (at least on latest Windows versions) there is always a - fake - registered protocol handler called App Picker (that annoying window that let you choose with which application you want to open an unknown file). This may vanish your tests so if you don't want to handle Windows environment as a special case you can simplify this process as:

  1. If you're running on a mobile device then assume tel: is supported.
  2. If you're running on desktop then replace tel: with callto:. then drop tel: or leave it as is (assuming there are good chances Skype is installed).

Getting value of select (dropdown) before change

Use following code,I have tested it and its working

var prev_val;
$('.dropdown').focus(function() {
    prev_val = $(this).val();
            var conf = confirm('Are you sure want to change status ?');

            if(conf == true){
                //your code
                return false;

How to set the Default Page in ASP.NET?

I prefer using the following method:

      <clear />
      <add value="CreateThing.aspx" />

Streaming a video file to an html5 video player with Node.js so that the video controls continue to work?

The accepted answer to this question is awesome and should remain the accepted answer. However I ran into an issue with the code where the read stream was not always being ended/closed. Part of the solution was to send autoClose: true along with start:start, end:end in the second createReadStream arg.

The other part of the solution was to limit the max chunksize being sent in the response. The other answer set end like so:

var end = positions[1] ? parseInt(positions[1], 10) : total - 1;

...which has the effect of sending the rest of the file from the requested start position through its last byte, no matter how many bytes that may be. However the client browser has the option to only read a portion of that stream, and will, if it doesn't need all of the bytes yet. This will cause the stream read to get blocked until the browser decides it's time to get more data (for example a user action like seek/scrub, or just by playing the stream).

I needed this stream to be closed because I was displaying the <video> element on a page that allowed the user to delete the video file. However the file was not being removed from the filesystem until the client (or server) closed the connection, because that is the only way the stream was getting ended/closed.

My solution was just to set a maxChunk configuration variable, set it to 1MB, and never pipe a read a stream of more than 1MB at a time to the response.

// same code as accepted answer
var end = positions[1] ? parseInt(positions[1], 10) : total - 1;
var chunksize = (end - start) + 1;

// poor hack to send smaller chunks to the browser
var maxChunk = 1024 * 1024; // 1MB at a time
if (chunksize > maxChunk) {
  end = start + maxChunk - 1;
  chunksize = (end - start) + 1;

This has the effect of making sure that the read stream is ended/closed after each request, and not kept alive by the browser.

I also wrote a separate StackOverflow question and answer covering this issue.

webpack command not working

The quickest way, just to get this working is to use the web pack from another location, this will stop you having to install it globally or if npm run webpack fails.

When you install webpack with npm it goes inside the "node_modules\.bin" folder of your project.

in command prompt (as administrator)

  1. go to the location of the project where your webpack.config.js is located.
  2. in command prompt write the following
"C:\Users\..\ProjectName\node_modules\.bin\webpack" --config webpack.config.vendor.js

Floating Div Over An Image

Never fails, once I post the question to SO, I get some enlightening "aha" moment and figure it out. The solution:

    .container {_x000D_
       border: 1px solid #DDDDDD;_x000D_
       width: 200px;_x000D_
       height: 200px;_x000D_
       position: relative;_x000D_
    .tag {_x000D_
       float: left;_x000D_
       position: absolute;_x000D_
       left: 0px;_x000D_
       top: 0px;_x000D_
       z-index: 1000;_x000D_
       background-color: #92AD40;_x000D_
       padding: 5px;_x000D_
       color: #FFFFFF;_x000D_
       font-weight: bold;_x000D_
<div class="container">_x000D_
       <div class="tag">Featured</div>_x000D_
       <img src="">_x000D_

The key is the container has to be positioned relative and the tag positioned absolute.

tar: file changed as we read it

Although its very late but I recently had the same issue.

Issue is because dir . is changing as xyz.tar.gz is created after running the command. There are two solutions:

Solution 1: tar will not mind if the archive is created in any directory inside .. There can be reasons why can't create the archive outside the work space. Worked around it by creating a temporary directory for putting the archive as:

mkdir artefacts
tar -zcvf artefacts/archive.tar.gz --exclude=./artefacts .
echo $?

Solution 2: This one I like. create the archive file before running tar:

touch archive.tar.gz
tar --exclude=archive.tar.gz -zcvf archive.tar.gz .
echo $?

Send JSON via POST in C# and Receive the JSON returned?

Using the JSON.NET NuGet package and anonymous types, you can simplify what the other posters are suggesting:

// ...

string payload = JsonConvert.SerializeObject(new
    agent = new
        name    = "Agent Name",
        version = 1,

    username = "username",
    password = "password",
    token    = "xxxxx",

var client = new HttpClient();
var content = new StringContent(payload, Encoding.UTF8, "application/json");

HttpResponseMessage response = await client.PostAsync(uri, content);

// ...

Batch files : How to leave the console window open

For leaving the console window open you only have to add to the last command line in the batch file:

' & pause'

Convert character to ASCII code in JavaScript

For supporting all UTF-16 (also non-BMP/supplementary characters) from ES6 the string.codePointAt() method is available;

This method is an improved version of charCodeAt which could support only unicode codepoints < 65536 ( 216 - a single 16bit ) .

Excel VBA Run-time error '424': Object Required when trying to copy TextBox

The issue is with this line

 xlo.Worksheets(1).Cells(2, 2) = TextBox1.Text

You have the textbox defined at some other location which you are not using here. Excel is unable to find the textbox object in the current sheet while this textbox was defined in xlw.

Hence replace this with

 xlo.Worksheets(1).Cells(2, 2) = worksheets("xlw").TextBox1.Text 

What is the SQL command to return the field names of a table?

This is also MySQL Specific:

show fields from [tablename];

this doesnt just show the table names but it also pulls out all the info about the fields.

How to increase the timeout period of web service in

1 - You can set a timeout in your application :

var client = new YourServiceReference.YourServiceClass();
client.Timeout = 60; // or -1 for infinite

It is in milliseconds.

2 - Also you can increase timeout value in httpruntime tag in web/app.config :

          <httpRuntime executionTimeout="<<**seconds**>>" />

For ASP.NET applications, the Timeout property value should always be less than the executionTimeout attribute of the httpRuntime element in Machine.config. The default value of executionTimeout is 90 seconds. This property determines the time ASP.NET continues to process the request before it returns a timed out error. The value of executionTimeout should be the proxy Timeout, plus processing time for the page, plus buffer time for queues. -- Source

error: pathspec 'test-branch' did not match any file(s) known to git

just follow three steps, git branch problem will be solved.

git remote update
git fetch
git checkout --track origin/test-branch

Clearfix with twitter bootstrap

clearfix should contain the floating elements but in your html you have added clearfix only after floating right that is your pull-right so you should do like this:

<div class="clearfix">
  <div id="sidebar">
  <div id="main">
      <div class="pull-right">
  <div>MOVED BELOW Z</div>

see this demo

Happy to know you solved the problem by setting overflow properties. However this is also good idea to clear the float. Where you have floated your elements you could add overflow: hidden; as you have done in your main.

How to send PUT, DELETE HTTP request in HttpURLConnection?

For doing a PUT in HTML correctly, you will have to surround it with try/catch:

try {
    url = new URL("");
    HttpURLConnection httpCon = (HttpURLConnection) url.openConnection();
    OutputStreamWriter out = new OutputStreamWriter(
    out.write("Resource content");
} catch (MalformedURLException e) {
} catch (ProtocolException e) {
} catch (IOException e) {

How do I copy a version of a single file from one git branch to another?

Run this from the branch where you want the file to end up:

git checkout otherbranch myfile.txt

General formulas:

git checkout <commit_hash> <relative_path_to_file_or_dir>
git checkout <remote_name>/<branch_name> <file_or_dir>

Some notes (from comments):

  • Using the commit hash you can pull files from any commit
  • This works for files and directories
  • overwrites the file myfile.txt and mydir
  • Wildcards don't work, but relative paths do
  • Multiple paths can be specified

an alternative:

git show commit_id:path/to/file > path/to/file

CSS: How to position two elements on top of each other, without specifying a height?

I had to set

Container_height = Element1_height = Element2_height

.Container {
    position: relative;

.ElementOne, .Container ,.ElementTwo{
    width: 283px;
    height: 71px;

.ElementOne {


Use can use z-index to set which one to be on top.

Display a RecyclerView in Fragment

Make sure that you have the correct layout, and that the RecyclerView id is inside the layout. Otherwise, you will be getting this error. I had the same problem, then I noticed the layout was wrong.

    public class ColorsFragment extends Fragment {

         public ColorsFragment() {}

         public View onCreateView(LayoutInflater inflater, ViewGroup container,
             Bundle savedInstanceState) {

==> make sure you are getting the correct layout here. R.layout...

             View rootView = inflater.inflate(R.layout.fragment_colors, container, false); 

'React' must be in scope when using JSX react/react-in-jsx-scope?

For those who still don't get the accepted solution :


import React from 'react'
import ReactDOM from 'react-dom'

at the top of the file.

Form inline inside a form horizontal in twitter bootstrap?

to make it simple, just add a class="form-inline" before the input.


<div class="col-md-4 form-inline"> //add the class here...
     <label>Lot Size:</label>
     <input type="text" value="" name="" class="form-control" >

C# code to validate email address

    /// <summary>
    /// Validates the email if it follows the valid email format
    /// </summary>
    /// <param name="emailAddress"></param>
    /// <returns></returns>
    public static bool EmailIsValid(string emailAddress)
        //if string is not null and empty then check for email follow the format
        return string.IsNullOrEmpty(emailAddress)?false : new Regex(@"^(?!\.)(""([^""\r\\]|\\[""\r\\])*""|([-a-z0-9!#$%&'*+/=?^_`{|}~]|(?<!\.)\.)*)(?<!\.)@[a-z0-9][\w\.-]*[a-z0-9]\.[a-z][a-z\.]*[a-z]$", RegexOptions.IgnoreCase).IsMatch(emailAddress);

Display Images Inline via CSS

The code you have posted here and code on your site both are different. There is a break <br> after second image, so the third image into new line, remove this <br> and it will display correctly.

Declaring an HTMLElement Typescript

Note that const declarations are block-scoped.

const el: HTMLElement | null = document.getElementById('content');

if (el) {
  const definitelyAnElement: HTMLElement = el;

So the value of definitelyAnElement is not accessible outside of the {}.

(I would have commented above, but I do not have enough Reputation apparently.)

keycode and charcode

keyCode and which represent the actual keyboard key pressed in the form of a numeric value. The reason both exist is that keyCode is available within Internet Explorer while which is available in W3C browsers like FireFox.

charCode is similar, but in this case you retrieve the Unicode value of the character pressed. For example, the letter "A."

The JavaScript expression:

var keyCode = e.keyCode ? e.keyCode : e.charCode;

Essentially says the following:

If the e.keyCode property exists, set variable keyCode to its value. Otherwise, set variable keyCode to the value of the e.charCode property.

Note that retrieving the keyCode or charCode properties typically involve figuring out differences between the event models in IE and in W3C. Some entails writing code like the following:

 get the event object: either window.event for IE 
 or the parameter e for other browsers
var evt = window.event ? window.event : e;
 get the numeric value of the key pressed: either 
 event.keyCode for IE for e.which for other browsers
var keyCode = evt.keyCode ? evt.keyCode : e.which;

EDIT: Corrections to my explanation of charCode as per Tor Haugen's comments.

How can I detect keydown or keypress event in angular.js?


ngKeypress, ngKeydown and ngKeyup are now part of AngularJS.

<!-- you can, for example, specify an expression to evaluate -->
<input ng-keypress="count = count + 1" ng-init="count=0">

<!-- or call a controller/directive method and pass $event as parameter.
     With access to $event you can now do stuff like 
     finding which key was pressed -->
<input ng-keypress="changed($event)">

Read more here:

Earlier solutions:

Solution 1: Use ng-change with ng-model

<input type="text" placeholder="+639178983214" ng-model="mobileNumber" 
ng-controller="RegisterDataController" ng-change="keydown()">


function RegisterDataController($scope) {       
   $scope.keydown = function() {
        /* validate $scope.mobileNumber here*/

Solution 2. Use $watch

<input type="text" placeholder="+639178983214" ng-model="mobileNumber" 


$scope.$watch("mobileNumber", function(newValue, oldValue) {
    /* change noticed */

What is a Y-combinator?

I wonder if there's any use in attempting to build this from the ground up. Let's see. Here's a basic, recursive factorial function:

function factorial(n) {
    return n == 0 ? 1 : n * factorial(n - 1);

Let's refactor and create a new function called fact that returns an anonymous factorial-computing function instead of performing the calculation itself:

function fact() {
    return function(n) {
        return n == 0 ? 1 : n * fact()(n - 1);

var factorial = fact();

That's a little weird, but there's nothing wrong with it. We're just generating a new factorial function at each step.

The recursion at this stage is still fairly explicit. The fact function needs to be aware of its own name. Let's parameterize the recursive call:

function fact(recurse) {
    return function(n) {
        return n == 0 ? 1 : n * recurse(n - 1);

function recurser(x) {
    return fact(recurser)(x);

var factorial = fact(recurser);

That's great, but recurser still needs to know its own name. Let's parameterize that, too:

function recurser(f) {
    return fact(function(x) {
        return f(f)(x);

var factorial = recurser(recurser);

Now, instead of calling recurser(recurser) directly, let's create a wrapper function that returns its result:

function Y() {
    return (function(f) {
        return f(f);

var factorial = Y();

We can now get rid of the recurser name altogether; it's just an argument to Y's inner function, which can be replaced with the function itself:

function Y() {
    return (function(f) {
        return f(f);
    })(function(f) {
        return fact(function(x) {
            return f(f)(x);

var factorial = Y();

The only external name still referenced is fact, but it should be clear by now that that's easily parameterized, too, creating the complete, generic, solution:

function Y(le) {
    return (function(f) {
        return f(f);
    })(function(f) {
        return le(function(x) {
            return f(f)(x);

var factorial = Y(function(recurse) {
    return function(n) {
        return n == 0 ? 1 : n * recurse(n - 1);

Read each line of txt file to new array element

This has been covered here quite well, but if you REALLY need even better performance than anything listed here, you can use this approach that uses strtok.

$Names_Keys = [];
$Name = strtok(file_get_contents($file), "\n");
while ($Name !== false) {
    $Names_Keys[$Name] = 0;
    $Name = strtok("\n");

Note, this assumes your file is saved with \n as the newline character (you can update that as need be), and it also stores the words/names/lines as the array keys instead of the values, so that you can use it as a lookup table, allowing the use of isset (much, much faster), instead of in_array.

Kubernetes Pod fails with CrashLoopBackOff

I ran into the same error.

NAME         READY   STATUS             RESTARTS   AGE
pod/webapp   0/1     CrashLoopBackOff   5          47h

My problem was that I was trying to run two different pods with the same metadata name.

kind: Pod metadata: name: webapp labels: ...

To find all the names of your pods run: kubectl get pods

webapp       1/1     Running   15         47h

then I changed the conflicting pod name and everything worked just fine.

NAME                 READY   STATUS    RESTARTS   AGE
webapp               1/1     Running   17         2d
webapp-release-0-5   1/1     Running   0          13m

What does an exclamation mark before a cell reference mean?

When entered as the reference of a Named range, it refers to range on the sheet the named range is used on.

For example, create a named range MyName refering to =SUM(!B1:!K1)

Place a formula on Sheet1 =MyName. This will sum Sheet1!B1:K1

Now place the same formula (=MyName) on Sheet2. That formula will sum Sheet2!B1:K1

Note: (as pnuts commented) this and the regular SheetName!B1:K1 format are relative, so reference different cells as the =MyName formula is entered into different cells.

SQL Server : SUM() of multiple rows including where clauses

Use a common table expression to add grand total row, top 100 is required for order by to work.

With Detail as 
    SELECT  top 100 propertyId, SUM(Amount) as TOTAL_COSTS
    FROM MyTable
    GROUP BY propertyId

Select * from Detail
Union all
Select ' Total ', sum(TOTAL_COSTS) from Detail

Android list view inside a scroll view

I was having the same problem for such a long time. Then I found a solution that worked for me. Add a ListViewHelper java class. Here below is code for

package com.molescope;

import android.view.View;
import android.view.ViewGroup;
import android.widget.ListAdapter;
import android.widget.ListView;

public class ListViewHelper {
    public static void getListViewSize(ListView listView){
        ListAdapter adapter = listView.getAdapter();
            int totalHeight = 0;

            //setting list adapter in loop tp get final size
            for (int i=0; i<adapter.getCount(); i++){
                View listItem = adapter.getView(i, null, listView);
                totalHeight += listItem.getMeasuredHeight();
            //setting listview items in adapter
            ViewGroup.LayoutParams params = listView.getLayoutParams();
            params.height = totalHeight + (listView.getDividerHeight() * 


And after adding this java file, in your code wherever you are setting adapter to listview, right after that line add the code below:

  ListView myList=(ListView) findViewById(;
  myList.setAdapter(new ArrayAdapter<String>. 
  (this,android.R.layout.simple_list_item_1, listview_array));

Pardon my english.

Converting PHP result array to JSON

json_encode is available in php > 5.2.0:


Convert a bitmap into a byte array

More simple:

return (byte[])System.ComponentModel.TypeDescriptor.GetConverter(pImagen).ConvertTo(pImagen, typeof(byte[]))

How do I get Maven to use the correct repositories?

Basically, all Maven is telling you is that certain dependencies in your project are not available in the central maven repository. The default is to look in your local .m2 folder (local repository), and then any configured repositories in your POM, and then the central maven repository. Look at the repositories section of the Maven reference.

The problem is that the project that was checked in didn't configure the POM in such a way that all the dependencies could be found and the project could be built from scratch.

How can I hide/show a div when a button is clicked?

The following solution is:

  • briefest. Somewhat similar to here. It's also minimal: The table in the DIV is orthogonal to your question.
  • fastest: getElementById is called once at the outset. This may or may not suit your purposes.
  • It uses pure JavaScript (i.e. without JQuery).
  • It uses a button. Your taste may vary.
  • extensible: it's ready to add more DIVs, sharing the code.

mydiv = document.getElementById("showmehideme");_x000D_
function showhide(d) {_x000D_ = ( !== "none") ? "none" : "block";_x000D_
#mydiv { background-color: #ddd; }
<button id="button" onclick="showhide(mydiv)">Show/Hide</button>_x000D_
<div id="showmehideme">_x000D_
    This div will show and hide on button click._x000D_

Check input value length

You can add a form onsubmit handler, something like:

<form onsubmit="return validate();">


<script>function validate() {
 // check if input is bigger than 3
 var value = document.getElementById('titleeee').value;
 if (value.length < 3) {
   return false; // keep form from submitting

 // else form is good let it submit, of course you will 
 // probably want to alert the user WHAT went wrong.

 return true;

Writing a dictionary to a text file?

If you want a dictionary you can import from a file by name, and also that adds entries that are nicely sorted, and contains strings you want to preserve, you can try this:

data = {'A': 'a', 'B': 'b', }

with open('','w') as file:
    file.write("dictionary_name = { \n")
    for k in sorted (data.keys()):
        file.write("'%s':'%s', \n" % (k, data[k]))

Then to import:

from file import dictionary_name

Check image width and height before upload with Javascript

    const ValidateImg = (file) =>{_x000D_
        let img = new Image()_x000D_
        img.src = window.URL.createObjectURL(file)_x000D_
        img.onload = () => {_x000D_
            if(img.width === 100 && img.height ===100){_x000D_
                alert("Correct size");_x000D_
                return true;_x000D_
            alert("Incorrect size");_x000D_
            return true;_x000D_

How to get a Fragment to remove itself, i.e. its equivalent of finish()?

You can use the approach below, it works fine:


Git fast forward VS no fast forward merge

The --no-ff option is useful when you want to have a clear notion of your feature branch. So even if in the meantime no commits were made, FF is possible - you still want sometimes to have each commit in the mainline correspond to one feature. So you treat a feature branch with a bunch of commits as a single unit, and merge them as a single unit. It is clear from your history when you do feature branch merging with --no-ff.

If you do not care about such thing - you could probably get away with FF whenever it is possible. Thus you will have more svn-like feeling of workflow.

For example, the author of this article thinks that --no-ff option should be default and his reasoning is close to that I outlined above:

Consider the situation where a series of minor commits on the "feature" branch collectively make up one new feature: If you just do "git merge feature_branch" without --no-ff, "it is impossible to see from the Git history which of the commit objects together have implemented a feature—you would have to manually read all the log messages. Reverting a whole feature (i.e. a group of commits), is a true headache [if --no-ff is not used], whereas it is easily done if the --no-ff flag was used [because it's just one commit]."

Graphic showing how --no-ff groups together all commits from feature branch into one commit on master branch

List of IP addresses/hostnames from local network in Python


import socket

print ([ip for ip in socket.gethostbyname_ex(socket.gethostname())[2] if not ip.startswith("127.")][:1])

How to redirect to another page in node.js

The If else statement needs to be wrapped in a .get or a .post to redirect. Such as'/login', function(req, res) {


app.get('/login', function(req, res) {

Rotating x axis labels in R for barplot


Here's a kind of hackish way. I'm guessing there's an easier way. But you could suppress the bar labels and the plot text of the labels by saving the bar positions from barplot and do a little tweaking up and down. Here's an example with the mtcars data set:

x <- barplot(table(mtcars$cyl), xaxt="n")
labs <- paste(names(table(mtcars$cyl)), "cylinders")
text(cex=1, x=x-.25, y=-1.25, labs, xpd=TRUE, srt=45)

Extract a substring using PowerShell

Not sure if this is efficient or not, but strings in PowerShell can be referred to using array index syntax, in a similar fashion to Python.

It's not completely intuitive because of the fact the first letter is referred to by index = 0, but it does:

  • Allow a second index number that is longer than the string, without generating an error
  • Extract substrings in reverse
  • Extract substrings from the end of the string

Here are some examples:

PS > 'Hello World'[0..2]

Yields the result (index values included for clarity - not generated in output):

H [0]
e [1]
l [2]

Which can be made more useful by passing -join '':

PS > 'Hello World'[0..2] -join ''

There are some interesting effects you can obtain by using different indices:


Use a first index value that is less than the second and the substring will be extracted in the forwards direction as you would expect. This time the second index value is far in excess of the string length but there is no error:

PS > 'Hello World'[3..300] -join ''
lo World


PS > 'Hello World'.Substring(3,300)
Exception calling "Substring" with "2" argument(s): "Index and length must refer to a location within
the string.


If you supply a second index value that is lower than the first, the string is returned in reverse:

PS > 'Hello World'[4..0] -join ''

From End

If you use negative numbers you can refer to a position from the end of the string. To extract 'World', the last 5 letters, we use:

PS > 'Hello World'[-5..-1] -join ''

How to set proper codeigniter base url?

Try to add the controller to your index page aswell. Just looked at as similar structure on one of my own site and I hade my base url set to = ""

C# convert int to string with padding zeros?

Easy peasy

int i = 1;

How to format a java.sql Timestamp for displaying?

java.sql.Timestamp extends java.util.Date. You can do:

String s = new SimpleDateFormat("MM/dd/yyyy").format(myTimestamp);

Or to also include time:

String s = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss").format(myTimestamp);

Converting ArrayList to Array in java

You don't need to reinvent the wheel, here's the toArray() method:

String []dsf = new String[al.size()];

Get Android Device Name

I solved this by getting the Bluetooth name, but not from the BluetoothAdapter (that needs Bluetooth permission).

Here's the code:

Settings.Secure.getString(getContentResolver(), "bluetooth_name");

No extra permissions needed.

Redirect stderr and stdout in Bash

The following functions can be used to automate the process of toggling outputs beetwen stdout/stderr and a logfile.


    #set -x

    # global vars

    # "private" function used by redirect_outputs_to_logfile()
    function save_standard_outputs {
        if [ "$OUTPUTS_REDIRECTED" == "true" ]; then
            echo "[ERROR]: ${FUNCNAME[0]}: Cannot save standard outputs because they have been redirected before"
            exit 1;
        exec 3>&1
        exec 4>&2

        trap restore_standard_outputs EXIT

    # Params: $1 => logfile to write to
    function redirect_outputs_to_logfile {
        if [ "$OUTPUTS_REDIRECTED" == "true" ]; then
            echo "[ERROR]: ${FUNCNAME[0]}: Cannot redirect standard outputs because they have been redirected before"
            exit 1;
        if [ -z "$LOGFILE" ]; then
            echo "[ERROR]: ${FUNCNAME[0]}: logfile empty [$LOGFILE]"

        if [ ! -f $LOGFILE ]; then
            touch $LOGFILE
        if [ ! -f $LOGFILE ]; then
            echo "[ERROR]: ${FUNCNAME[0]}: creating logfile [$LOGFILE]"
            exit 1


        exec 1>>${LOGFILE%.log}.log
        exec 2>&1

    # "private" function used by save_standard_outputs() 
    function restore_standard_outputs {
        if [ "$OUTPUTS_REDIRECTED" == "false" ]; then
            echo "[ERROR]: ${FUNCNAME[0]}: Cannot restore standard outputs because they have NOT been redirected"
            exit 1;
        exec 1>&-   #closes FD 1 (logfile)
        exec 2>&-   #closes FD 2 (logfile)
        exec 2>&4   #restore stderr
        exec 1>&3   #restore stdout


Example of usage inside script:

echo "this goes to stdout"
redirect_outputs_to_logfile /tmp/one.log
echo "this goes to logfile"
echo "this goes to stdout"

Node JS Promise.all and forEach

It's pretty straightforward with some simple rules:

  • Whenever you create a promise in a then, return it - any promise you don't return will not be waited for outside.
  • Whenever you create multiple promises, .all them - that way it waits for all the promises and no error from any of them are silenced.
  • Whenever you nest thens, you can typically return in the middle - then chains are usually at most 1 level deep.
  • Whenever you perform IO, it should be with a promise - either it should be in a promise or it should use a promise to signal its completion.

And some tips:

  • Mapping is better done with .map than with for/push - if you're mapping values with a function, map lets you concisely express the notion of applying actions one by one and aggregating the results.
  • Concurrency is better than sequential execution if it's free - it's better to execute things concurrently and wait for them Promise.all than to execute things one after the other - each waiting before the next.

Ok, so let's get started:

var items = [1, 2, 3, 4, 5];
var fn = function asyncMultiplyBy2(v){ // sample async action
    return new Promise(resolve => setTimeout(() => resolve(v * 2), 100));
// map over forEach since it returns

var actions =; // run the function over all items

// we now have a promises array and we want to wait for it

var results = Promise.all(actions); // pass array of promises

results.then(data => // or just .then(console.log)
    console.log(data) // [2, 4, 6, 8, 10]

// we can nest this of course, as I said, `then` chains:

var res2 = Promise.all([1, 2, 3, 4, 5].map(fn)).then(
    data => Promise.all(
    // the next `then` is executed after the promise has returned from the previous
    // `then` fulfilled, in this case it's an aggregate promise because of 
    // the `.all` 
    return Promise.all(;
    // just for good measure
    return Promise.all(;

// now to get the results:

    console.log(data); // [16, 32, 48, 64, 80]

Excel VBA: Copying multiple sheets into new workbook

Try do something like this (the problem was that you trying to use MyBook.Worksheets, but MyBook is not a Workbook object, but string, containing workbook name. I've added new varible Set WB = ActiveWorkbook, so you can use WB.Worksheets instead MyBook.Worksheets):

Sub NewWBandPasteSpecialALLSheets()
   MyBook = ActiveWorkbook.Name ' Get name of this book
   Workbooks.Add ' Open a new workbook
   NewBook = ActiveWorkbook.Name ' Save name of new book

   Workbooks(MyBook).Activate ' Back to original book

   Set WB = ActiveWorkbook

   Dim SH As Worksheet

   For Each SH In WB.Worksheets



       With SH.Range("A1")
        .PasteSpecial (xlPasteColumnWidths)
        .PasteSpecial (xlFormats)
        .PasteSpecial (xlValues)

       End With


End Sub

But your code doesn't do what you want: it doesen't copy something to a new WB. So, the code below do it for you:

Sub NewWBandPasteSpecialALLSheets()
   Dim wb As Workbook
   Dim wbNew As Workbook
   Dim sh As Worksheet
   Dim shNew As Worksheet

   Set wb = ThisWorkbook
   Workbooks.Add ' Open a new workbook
   Set wbNew = ActiveWorkbook

   On Error Resume Next

   For Each sh In wb.Worksheets

      'add new sheet into new workbook with the same name
      With wbNew.Worksheets

          Set shNew = Nothing
          Set shNew = .Item(sh.Name)

          If shNew Is Nothing Then
              .Add After:=.Item(.Count)
              .Item(.Count).Name = sh.Name
              Set shNew = .Item(.Count)
          End If
      End With

      With shNew.Range("A1")
          .PasteSpecial (xlPasteColumnWidths)
          .PasteSpecial (xlFormats)
          .PasteSpecial (xlValues)
      End With
End Sub

Create list or arrays in Windows Batch

Sometimes the array element may be very long, at that time you can create an array in this way:

set list=a
set list=%list%;b 
set list=%list%;c 
set list=%list%;d

Then show it:

@echo off
for %%a in (%list%) do ( 
 echo %%a

How do write IF ELSE statement in a MySQL query

You're looking for case:

case when action = 2 and state = 0 then 1 else 0 end as state

MySQL has an if syntax (if(action=2 and state=0, 1, 0)), but case is more universal.

Note that the as state there is just aliasing the column. I'm assuming this is in the column list of your SQL query.

Python, print all floats to 2 decimal places in output

If you just want to convert the values to nice looking strings do the following:

twodecimals = ["%.2f" % v for v in vars]

Alternatively, you could also print out the units like you have in your question:

vars = [0, 1, 2, 3] # just some example values
units = ['kg', 'lb', 'gal', 'l']
delimiter = ', ' # or however you want the values separated

print delimiter.join(["%.2f %s" % (v,u) for v,u in zip(vars, units)])
Out[189]: '0.00 kg, 1.00 lb, 2.00 gal, 3.00 l'

The second way allows you to easily change the delimiter (tab, spaces, newlines, whatever) to suit your needs easily; the delimiter could also be a function argument instead of being hard-coded.

Edit: To use your 'name = value' syntax simply change the element-wise operation within the list comprehension:

print delimiter.join(["%s = %.2f" % (u,v) for v,u in zip(vars, units)])
Out[190]: 'kg = 0.00, lb = 1.00, gal = 2.00, l = 3.00'

What is a .pid file and what does it contain?

To understand pid files, refer this DOC

Some times there are certain applications that require additional support of extra plugins and utilities. So it keeps track of these utilities and plugin process running ids using this pid file for reference.

That is why whenever you restart an application all necessary plugins and dependant apps must be restarted since the pid file will become stale.

Android : Fill Spinner From Java Code Programmatically

// you need to have a list of data that you want the spinner to display
List<String> spinnerArray =  new ArrayList<String>();

ArrayAdapter<String> adapter = new ArrayAdapter<String>(
    this, android.R.layout.simple_spinner_item, spinnerArray);

Spinner sItems = (Spinner) findViewById(;

also to find out what is selected you could do something like this

String selected = sItems.getSelectedItem().toString();
if (selected.equals("what ever the option was")) {

Changing selection in a select with the Chosen plugin

My answer is late, but i want to add some information that is missed in all above answers.

1) If you want to select single value in chosen select.


2) If you are using multiple chosen select, then may you need to set multiple values at single time.

$('#documents').val(["22", "25", "27"]).trigger('chosen:updated');

Information gathered from following links:
1) Chosen Docs
2) Chosen Github Discussion

Android custom dropdown/popup menu

Update: To create a popup menu in android with Kotlin refer my answer here.

To create a popup menu in android with Java:

Create a layout file activity_main.xml under res/layout directory which contains only one button.

Filename: activity_main.xml

<RelativeLayout xmlns:android=""  
    tools:context=".MainActivity" >  

        android:text="Show Popup" />  


Create a file popup_menu.xml under res/menu directory

It contains three items as shown below.

Filename: poupup_menu.xml

<menu xmlns:android="" >  





MainActivity class which displays the popup menu on button click.


public class MainActivity extends Activity {  
    private Button button1;  

    protected void onCreate(Bundle savedInstanceState) {

        button1 = (Button) findViewById(;
        button1.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                //Creating the instance of PopupMenu
                PopupMenu popup = new PopupMenu(MainActivity.this, button1);
                //Inflating the Popup using xml file
                    .inflate(, popup.getMenu());

                //registering popup with OnMenuItemClickListener
                popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
                    public boolean onMenuItemClick(MenuItem item) {
                            "You Clicked : " + item.getTitle(),
                        return true;

      ; //showing popup menu
        }); //closing the setOnClickListener method

To add programmatically:

PopupMenu menu = new PopupMenu(this, view);


Follow this link for creating menu programmatically.

How can I install Python's pip3 on my Mac?

After upgrading to macOS v10.15 (Catalina), and upgrading all my vEnv modules, pip3 stopped working (gave error: "TypeError: 'module' object is not callable").

I found question 58386953 which led to here and solution.

  1. Exit from the vEnv (I started a fresh shell)
  2. sudo python3 -m pip uninstall pip (this is necessary, but it did not fix problem, because it removed the base Python pip, but it didn't touch my vEnv pip)
  3. sudo easy_install pip (reinstalling pip in base Python, not in vEnv)
  4. cd to your vEnv/bin and type "source activate" to get into vEnv
  5. rm pip pip3 pip3.6 (it seems to be the only way to get rid of the bogus pip's in vEnv)
  6. Now pip is gone from vEnv, and we can use the one in the base Python (I wasn't able to successfully install pip into vEnv after deleting)

Runtime error: Could not load file or assembly 'System.Web.WebPages.Razor, Version=

I got this problem because I uninstalled VS 2012, I don't want to reinstall it back, so I downloaded the AspNetMVC4Setup.exe from and fixed my problem.

Encode/Decode URLs in C++

Adding a follow-up to Bill's recommendation for using libcurl: great suggestion, and to be updated:
after 3 years, the curl_escape function is deprecated, so for future use it's better to use curl_easy_escape.

Android toolbar center title and custom font

I was facing the same issue, fixed by doing this in MainActivity

Toolbar toolbar = (Toolbar) findViewById(;
TextView mTitle = (TextView) toolbar.findViewById(;

And In Fragment

public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    if (view == null) {
        // Inflate the layout for this fragment
        view = inflater.inflate(R.layout.fragment_example, container, false);
    getActivity().setTitle("Choose Fragment");
    return view;

public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
    inflater.inflate(, menu);

Correct set of dependencies for using Jackson mapper

I spent few hours on this.

Even if I had the right dependency the problem was fixed only after I deleted the com.fasterxml.jackson folder in the .m2 repository under C:\Users\username.m2 and updated the project

How to view the current heap size that an application is using?

Attach with jvisualvm from Sun Java 6 JDK. Startup flags are listed.

Read Excel File in Python

The approach I took reads the header information from the first row to determine the indexes of the columns of interest.

You mentioned in the question that you also want the values output to a string. I dynamically build a format string for the output from the FORMAT column list. Rows are appended to the values string separated by a new line char.

The output column order is determined by the order of the column names in the FORMAT list.

In my code below the case of the column name in the FORMAT list is important. In the question above you've got 'Pincode' in your FORMAT list, but 'PinCode' in your excel. This wouldn't work below, it would need to be 'PinCode'.

from xlrd import open_workbook
wb = open_workbook('sample.xls')

FORMAT = ['Arm_id', 'DSPName', 'PinCode']
values = ""

for s in wb.sheets():
    headerRow = s.row(0)
    columnIndex = [x for y in FORMAT for x in range(len(headerRow)) if y == firstRow[x].value]
    formatString = ("%s,"*len(columnIndex))[0:-1] + "\n"

    for row in range(1,s.nrows):
        currentRow = s.row(row)
        currentRowValues = [currentRow[x].value for x in columnIndex]
        values += formatString % tuple(currentRowValues)

print values

For the sample input you gave above this code outputs:

>>> 1.0,JaVAS,282001.0

And because I'm a python noob, props be to: this answer, this answer, this question, this question and this answer.

Git: cannot checkout branch - error: pathspec '...' did not match any file(s) known to git

Three steps

  1. Write a command 'git fetch'
  2. then you will see the desired branch then switch to the relevant branch 'git checkout 'your_branch_name'
  3. then write a command 'git pull origin your_desired_branch_name'

Set default format of datetimepicker as dd-MM-yyyy

You could easily use:

label1.Text = dateTimePicker1.Value.Date.ToString("dd/MM/yyyy")

and if you want to change '/' or '-', just add this:

label1.Text = label1.Text.Replace(".", "-")

More info about DateTimePicker.CustomFormat Property: Link

How to do constructor chaining in C#

Are you asking about this?

  public class VariantDate {
    public int day;
    public int month;
    public int year;

    public VariantDate(int day) : this(day, 1) {}

    public VariantDate(int day, int month) : this(day, month,1900){}

    public VariantDate(int day, int month, int year){;


Print time in a batch file (milliseconds)

%time% should work, provided enough time has elapsed between calls:

@echo OFF

@echo %time%
ping -n 1 -w 1 1>nul
@echo %time%

On my system I get the following output:


Javascript .querySelector find <div> by innerTEXT

Since there are no limits to the length of text in a data attribute, use data attributes! And then you can use regular css selectors to select your element(s) like the OP wants.

for (const element of document.querySelectorAll("*")) {_x000D_
  element.dataset.myInnerText = element.innerText;_x000D_
document.querySelector("*[data-my-inner-text='Different text.']").style.color="blue";
<div>SomeText, text continues.</div>_x000D_
<div>Different text.</div>

Ideally you do the data attribute setting part on document load and narrow down the querySelectorAll selector a bit for performance.

Insert current date/time using now() in a field using MySQL/PHP

You forgot to close the mysql_query command:

mysql_query("INSERT INTO users (first, last, whenadded) VALUES ('$first', '$last', now())");

Note that last parentheses.

Android: Quit application when press back button

try this

Intent a = new Intent(Intent.ACTION_MAIN);

How to use mongoimport to import csv

mongoimport -d test -c test --type csv --file SampleCSVFile_119kb.csv --headerline

check collection data:-

var collections = db.getCollectionNames();_x000D_
for(var i = 0; i< collections.length; i++)_x000D_
{    _x000D_
   print('Collection: ' + collections[i]);_x000D_
   // print the name of each collection_x000D_
   //and then print the json of each of its elements_x000D_

Naming Conventions: What to name a boolean variable?

Personally more than anything I would change the logic, or look at the business rules to see if they dictate any potential naming.

Since, the actual condition that toggles the boolean is actually the act of being "last". I would say that switching the logic, and naming it "IsLastItem" or similar would be a more preferred method.