Programs & Examples On #Row number

An index or rank which indicates a row's position in a data-set.

Oracle 'Partition By' and 'Row_Number' keyword

PARTITION BY segregate sets, this enables you to be able to work(ROW_NUMBER(),COUNT(),SUM(),etc) on related set independently.

In your query, the related set comprised of rows with similar cdt.country_code, cdt.account, cdt.currency. When you partition on those columns and you apply ROW_NUMBER on them. Those other columns on those combination/set will receive sequential number from ROW_NUMBER

But that query is funny, if your partition by some unique data and you put a row_number on it, it will just produce same number. It's like you do an ORDER BY on a partition that is guaranteed to be unique. Example, think of GUID as unique combination of cdt.country_code, cdt.account, cdt.currency

newid() produces GUID, so what shall you expect by this expression?

   row_number() over(partition by newid() order by hi,ho)
from tbl;

...Right, all the partitioned(none was partitioned, every row is partitioned in their own row) rows' row_numbers are all set to 1

Basically, you should partition on non-unique columns. ORDER BY on OVER needed the PARTITION BY to have a non-unique combination, otherwise all row_numbers will become 1

An example, this is your data:

create table tbl(hi varchar, ho varchar);

insert into tbl values

Then this is analogous to your query:

   row_number() over(partition by hi,ho order by hi,ho)
from tbl;

What will be the output of that?

A   X   1
A   Y   1
A   Z   1
B   W   1
B   W   2
C   L   1
C   L   2

You see thee combination of HI HO? The first three rows has unique combination, hence they are set to 1, the B rows has same W, hence different ROW_NUMBERS, likewise with HI C rows.

Now, why is the ORDER BY needed there? If the previous developer merely want to put a row_number on similar data (e.g. HI B, all data are B-W, B-W), he can just do this:

   row_number() over(partition by hi,ho)
from tbl;

But alas, Oracle(and Sql Server too) doesn't allow partition with no ORDER BY; whereas in Postgresql, ORDER BY on PARTITION is optional:!1/27821/1

   row_number() over(partition by hi,ho)
from tbl;

Your ORDER BY on your partition look a bit redundant, not because of the previous developer's fault, some database just don't allow PARTITION with no ORDER BY, he might not able find a good candidate column to sort on. If both PARTITION BY columns and ORDER BY columns are the same just remove the ORDER BY, but since some database don't allow it, you can just do this:

SELECT cdt.*,
        ROW_NUMBER ()
        OVER (PARTITION BY cdt.country_code, cdt.account, cdt.currency
              ORDER BY newid())

You cannot find a good column to use for sorting similar data? You might as well sort on random, the partitioned data have the same values anyway. You can use GUID for example(you use newid() for SQL Server). So that has the same output made by previous developer, it's unfortunate that some database doesn't allow PARTITION with no ORDER BY

Though really, it eludes me and I cannot find a good reason to put a number on the same combinations (B-W, B-W in example above). It's giving the impression of database having redundant data. Somehow reminded me of this: How to get one unique record from the same list of records from table? No Unique constraint in the table

It really looks arcane seeing a PARTITION BY with same combination of columns with ORDER BY, can not easily infer the code's intent.

Live test:!3/27821/6

But as dbaseman have noticed also, it's useless to partition and order on same columns.

You have a set of data like this:

create table tbl(hi varchar, ho varchar);

insert into tbl values

Then you PARTITION BY hi,ho; and then you ORDER BY hi,ho. There's no sense numbering similar data :-)!3/29ab8/3

   row_number() over(partition by hi,ho order by hi,ho) as nr
from tbl;


A   X   1
A   X   2
A   X   3
B   Y   1
B   Y   2
C   Z   1
C   Z   2

See? Why need to put row numbers on same combination? What you will analyze on triple A,X, on double B,Y, on double C,Z? :-)

You just need to use PARTITION on non-unique column, then you sort on non-unique column(s)'s unique-ing column. Example will make it more clear:

create table tbl(hi varchar, ho varchar);

insert into tbl values

   row_number() over(partition by hi order by ho) as nr
from tbl;

PARTITION BY hi operates on non unique column, then on each partitioned column, you order on its unique column(ho), ORDER BY ho


A   D   1
A   E   2
A   F   3
B   E   1
B   F   2
C   D   1
C   E   2

That data set makes more sense

Live test:!3/d0b44/1

And this is similar to your query with same columns on both PARTITION BY and ORDER BY:

   row_number() over(partition by hi,ho order by hi,ho) as nr
from tbl;

And this is the ouput:

A   D   1
A   E   1
A   F   1
B   E   1
B   F   1
C   D   1
C   E   1

See? no sense?

Live test:!3/d0b44/3

Finally this might be the right query:

SELECT cdt.*,
     ROW_NUMBER ()
     OVER (PARTITION BY cdt.country_code, cdt.account -- removed: cdt.currency
           ORDER BY 
               -- removed: cdt.country_code, cdt.account, 
               cdt.currency) -- keep

Trouble using ROW_NUMBER() OVER (PARTITION BY ...)

It looks like a common gaps-and-islands problem. The difference between two sequences of row numbers rn1 and rn2 give the "group" number.

Run this query CTE-by-CTE and examine intermediate results to see how it works.

Sample data

I expanded sample data from the question a little.

    EmployeeID int,
    DateStarted date,
    DepartmentID int



Query for SQL Server 2008

There is no LEAD function in SQL Server 2008, so I had to use self-join via OUTER APPLY to get the value of the "next" row for the DateEnd.

        ,ROW_NUMBER() OVER (PARTITION BY EmployeeID ORDER BY DateStarted) AS rn1
        ,ROW_NUMBER() OVER (PARTITION BY EmployeeID, DepartmentID ORDER BY DateStarted) AS rn2
    FROM @Source
        ,MIN(DateStarted) AS DateStart
        ,rn1 - rn2
        SELECT TOP(1) G2.DateStart AS DateEnd
        FROM CTE_Groups AS G2
            G2.EmployeeID = CTE_Groups.EmployeeID
            AND G2.DateStart > CTE_Groups.DateStart
        ORDER BY G2.DateStart
    ) AS A

Query for SQL Server 2012+

Starting with SQL Server 2012 there is a LEAD function that makes this task more efficient.

        ,ROW_NUMBER() OVER (PARTITION BY EmployeeID ORDER BY DateStarted) AS rn1
        ,ROW_NUMBER() OVER (PARTITION BY EmployeeID, DepartmentID ORDER BY DateStarted) AS rn2
    FROM @Source
        ,MIN(DateStarted) AS DateStart
        ,rn1 - rn2
    ,LEAD(CTE_Groups.DateStart) OVER (PARTITION BY CTE_Groups.EmployeeID ORDER BY CTE_Groups.DateStart) AS DateEnd


| EmployeeID | DepartmentID | DateStart  |  DateEnd   |
|      10001 |            1 | 2013-01-01 | 2013-12-01 |
|      10001 |            2 | 2013-12-01 | 2014-10-01 |
|      10001 |            1 | 2014-10-01 | NULL       |
|      10005 |            1 | 2013-05-01 | 2013-12-01 |
|      10005 |            2 | 2013-12-01 | 2014-10-01 |
|      10005 |            1 | 2014-10-01 | NULL       |


The rownumber functionality can't be mimicked. You might get the results you expect, but you'll most likely get disappointed at some stage. Here's what mysql documentation says:

For other statements, such as SELECT, you might get the results you expect, but this is not guaranteed. In the following statement, you might think that MySQL will evaluate @a first and then do an assignment second: SELECT @a, @a:=@a+1, ...; However, the order of evaluation for expressions involving user variables is undefined.

Regards, Georgi.

Select specific row from mysql table

You can use LIMIT 2,1 instead of WHERE row_number() = 3.

As the documentation explains, the first argument specifies the offset of the first row to return, and the second specifies the maximum number of rows to return.

Keep in mind that it's an 0-based index. So, if you want the line number n, the first argument should be n-1. The second argument will always be 1, because you just want one row. For example, if you want the line number 56 of a table customer:

SELECT * FROM customer LIMIT 55,1

How to show row number in Access query like ROW_NUMBER in SQL

You can try this query:

Select A.*, (select count(*) from Table1 where A.ID>=ID) as RowNo
from Table1 as A
order by A.ID

Why is there still a row limit in Microsoft Excel?

Probably because of optimizations. Excel 2007 can have a maximum of 16 384 columns and 1 048 576 rows. Strange numbers?

14 bits = 16 384, 20 bits = 1 048 576

14 + 20 = 34 bits = more than one 32 bit register can hold.

But they also need to store the format of the cell (text, number etc) and formatting (colors, borders etc). Assuming they use two 32-bit words (64 bit) they use 34 bits for the cell number and have 30 bits for other things.

Why is that important? In memory they don't need to allocate all the memory needed for the whole spreadsheet but only the memory necessary for your data, and every data is tagged with in what cell it is supposed to be in.

Update 2016:

Found a link to Microsoft's specification for Excel 2013 & 2016

  • Open workbooks: Limited by available memory and system resources
  • Worksheet size: 1,048,576 rows (20 bits) by 16,384 columns (14 bits)
  • Column width: 255 characters (8 bits)
  • Row height: 409 points
  • Page breaks: 1,026 horizontal and vertical (unexpected number, probably wrong, 10 bits is 1024)
  • Total number of characters that a cell can contain: 32,767 characters (signed 16 bits)
  • Characters in a header or footer: 255 (8 bits)
  • Sheets in a workbook: Limited by available memory (default is 1 sheet)
  • Colors in a workbook: 16 million colors (32 bit with full access to 24 bit color spectrum)
  • Named views in a workbook: Limited by available memory
  • Unique cell formats/cell styles: 64,000 (16 bits = 65536)
  • Fill styles: 256 (8 bits)
  • Line weight and styles: 256 (8 bits)
  • Unique font types: 1,024 (10 bits) global fonts available for use; 512 per workbook
  • Number formats in a workbook: Between 200 and 250, depending on the language version of Excel that you have installed
  • Names in a workbook: Limited by available memory
  • Windows in a workbook: Limited by available memory
  • Hyperlinks in a worksheet: 66,530 hyperlinks (unexpected number, probably wrong. 16 bits = 65536)
  • Panes in a window: 4
  • Linked sheets: Limited by available memory
  • Scenarios: Limited by available memory; a summary report shows only the first 251 scenarios
  • Changing cells in a scenario: 32
  • Adjustable cells in Solver: 200
  • Custom functions: Limited by available memory
  • Zoom range: 10 percent to 400 percent
  • Reports: Limited by available memory
  • Sort references: 64 in a single sort; unlimited when using sequential sorts
  • Undo levels: 100
  • Fields in a data form: 32
  • Workbook parameters: 255 parameters per workbook
  • Items displayed in filter drop-down lists: 10,000

How do I use ROW_NUMBER()?

SQL Row_Number() function is to sort and assign an order number to data rows in related record set. So it is used to number rows, for example to identify the top 10 rows which have the highest order amount or identify the order of each customer which is the highest amount, etc.

If you want to sort the dataset and number each row by seperating them into categories we use Row_Number() with Partition By clause. For example, sorting orders of each customer within itself where the dataset contains all orders, etc.

FROM Sales.SalesOrderHeader

But as I understand you want to calculate the number of rows of grouped by a column. To visualize the requirement, if you want to see the count of all orders of the related customer as a seperate column besides order info, you can use COUNT() aggregation function with Partition By clause

For example,

    COUNT(*) OVER (PARTITION BY CustomerId) CustomerOrderCount
FROM Sales.SalesOrderHeader

MSSQL Select statement with incremental integer column... not from a table

It is ugly and performs badly, but technically this works on any table with at least one unique field AND works in SQL 2000.

SELECT (SELECT COUNT(*) FROM myTable T1 WHERE T1.UniqueField<=T2.UniqueField) as RowNum, T2.OtherField
FROM myTable T2
ORDER By T2.UniqueField

Note: If you use this approach and add a WHERE clause to the outer SELECT, you have to added it to the inner SELECT also if you want the numbers to be continuous.

MySQL - Get row number on select

Swamibebop's solution works, but by taking advantage of table.* syntax, we can avoid repeating the column names of the inner select and get a simpler/shorter result:

SELECT @r := @r+1 , 
FROM(/* your original select statement goes in here */)z, 
(SELECT @r:=0)y;

So that will give you:

SELECT @r := @r+1 , 
     SELECT itemID, 
     count(*) AS ordercount
     FROM orders
     GROUP BY itemID
     ORDER BY ordercount DESC
    (SELECT @r:=0)y;

How do I update Ruby Gems from behind a Proxy (ISA-NTLM)

Rather than editing batch files (which you may have to do for other Ruby gems, e.g. Bundler), it's probably better to do this once, and do it properly.

On Windows, behind my corporate proxy, all I had to do was add the HTTP_PROXY environment variable to my system.

  1. Start -> right click Computer -> Properties
  2. Choose "Advanced System Settings"
  3. Click Advanced -> Environment Variables
  4. Create a new System variable named "HTTP_PROXY", and set the Value to your proxy server
  5. Reboot or log out and back in again

Depending on your authentication requirements, the HTTP_PROXY value can be as simple as:


Or more complex as others have pointed out


using mailto to send email with an attachment

this is not possible in "mailto" function.

please go with server side coding(C#).make sure open vs in administrative permission.

Microsoft.Office.Interop.Outlook.Application oApp = new Microsoft.Office.Interop.Outlook.Application();
Microsoft.Office.Interop.Outlook.MailItem oMsg = (Microsoft.Office.Interop.Outlook.MailItem)oApp.CreateItem(Microsoft.Office.Interop.Outlook.OlItemType.olMailItem);

oMsg.Subject = "emailSubject";
oMsg.BodyFormat = Microsoft.Office.Interop.Outlook.OlBodyFormat.olFormatHTML;
oMsg.BCC = "emailBcc";
oMsg.To = "emailRecipient";

string body = "emailMessage";

oMsg.HTMLBody = "body";              
oMsg.Attachments.Add(Convert.ToString(@"/my_location_virtual_path/myfile.txt"), Microsoft.Office.Interop.Outlook.OlAttachmentType.olByValue, Type.Missing, Type.Missing);

oMsg.Display(false); //In order to displ

HTML5 textarea placeholder not appearing

its because there is a space somewhere. I was using jsfiddle and there was a space after the tag. After I deleted the space it started working

Using psql to connect to PostgreSQL in SSL mode

Well, you cloud provide all the information with following command in CLI, if connection requires in SSL mode:

psql "sslmode=verify-ca sslrootcert=server-ca.pem sslcert=client-cert.pem sslkey=client-key.pem hostaddr=your_host port=5432 user=your_user dbname=your_db" 

How to search for rows containing a substring?

Well, you can always try WHERE textcolumn LIKE "%SUBSTRING%" - but this is guaranteed to be pretty slow, as your query can't do an index match because you are looking for characters on the left side.

It depends on the field type - a textarea usually won't be saved as VARCHAR, but rather as (a kind of) TEXT field, so you can use the MATCH AGAINST operator.

To get the columns that don't match, simply put a NOT in front of the like: WHERE textcolumn NOT LIKE "%SUBSTRING%".

Whether the search is case-sensitive or not depends on how you stock the data, especially what COLLATION you use. By default, the search will be case-insensitive.

Updated answer to reflect question update:

I say that doing a WHERE field LIKE "%value%" is slower than WHERE field LIKE "value%" if the column field has an index, but this is still considerably faster than getting all values and having your application filter. Both scenario's:

1/ If you do SELECT field FROM table WHERE field LIKE "%value%", MySQL will scan the entire table, and only send the fields containing "value".

2/ If you do SELECT field FROM table and then have your application (in your case PHP) filter only the rows with "value" in it, MySQL will also scan the entire table, but send all the fields to PHP, which then has to do additional work. This is much slower than case #1.

Solution: Please do use the WHERE clause, and use EXPLAIN to see the performance.

The definitive guide to form-based website authentication

I dont't know whether it was best to answer this as an answer or as a comment. I opted for the first option.

Regarding the poing PART IV: Forgotten Password Functionality in the first answer, I would make a point about Timing Attacks.

In the Remember your password forms, an attacker could potentially check a full list of emails and detect which are registered to the system (see link below).

Regarding the Forgotten Password Form, I would add that it is a good idea to equal times between successful and unsucessful queries with some delay function.

ZIP Code (US Postal Code) validation

As I work in the mailing industry for 17 years I've seen all kinds of data entry in this area I find it interesting how many people do not know their address as it is defined by the USPS. I still see addresses like this:

XYZ College
IT Department
City, St ZIP

The worst part is the mail 99% of the time is delivered, the other 1%, well that is returned for an incomplete address as it should.

In an earlier post someone mentioned USPS CASS, that software is not free.

To regex a zip code tester is nice, I'm using expressions to determine if US, CA, UK, or AU zip code. I've seen expressions for Japan and others which only add challenges in choosing the correct country that a zip belongs to.

By far the best answer is to use Drop Down Lists for State, and Country. Then use tables to further validate if needed. Just to give you an idea there are 84052 acceptable US City St Zip combinations on just the first 5 digits. There are 249 valid countries as per the ISO and there are 65 US State/Territories.

There are Military, PO Box only, and Unique zip code classes as well. KISS applies here.

jQuery .slideRight effect

If you're willing to include the jQuery UI library, in addition to jQuery itself, then you can simply use hide(), with additional arguments, as follows:



JS Fiddle demo.

Without using jQuery UI, you could achieve your aim just using animate():

                            // to move it towards the right and, probably, off-screen.
                            // once it's finished moving to the right, just 
                            // removes the the element from the display, you could use
                            // `remove()` instead, or whatever.


JS Fiddle demo

If you do choose to use jQuery UI, then I'd recommend linking to the Google-hosted code, at:

for loop in Python

Use this instead of a for loop:

k = 1
while k <= c:
   k += 1

What does the question mark operator mean in Ruby?

It's a convention in Ruby that methods that return boolean values end in a question mark. There's no more significance to it than that.

VBA code to show Message Box popup if the formula in the target cell exceeds a certain value

I don't think a message box is the best way to go with this as you would need the VB code running in a loop to check the cell contents, or unless you plan to run the macro manually. In this case I think it would be better to add conditional formatting to the cell to change the background to red (for example) if the value exceeds the upper limit.

java: ArrayList - how can I check if an index exists?

This is what you need ...

public boolean indexExists(final List list, final int index) {
    return index >= 0 && index < list.size();

Why not use an plain old array? Indexed access to a List is a code smell I think.

how to download file in react js

If you are using React Router, use this:

<Link to="/files/myfile.pdf" target="_blank" download>Download</Link>

Where /files/myfile.pdf is inside your public folder.

Retrieve last 100 lines logs

You can simply use the following command:-


e.g tail -100 test.log

  • will fetch the last 100 lines from test.log

In case, if you want the output of the above in a separate file then you can pipes as follows:-


e.g tail -100 test.log > output.log

  • will fetch the last 100 lines from test.log and store them into a new file output.log)

Deleting objects from an ArrayList in Java

Obviously, of the two methods you mention number 1 is more efficient, since it only needs to go through the list once, while with method number 2 the list has to be traversed two times (first to find the elements to remove, and them to remove them).

Actually, removing a list of elements from another list is likely an algorithm that's worse than O(n) so method 2 is even worse.

The iterator method:

List data = ...;

for (Iterator i = data.iterator(); i.hasNext(); ) {
    Object element =;

    if (!(...)) {

SQL Server Management Studio – tips for improving the TSQL coding process

If you work with developers, often get a sliver of code that is formatted as one long line of code, then sql pretty printer add-on for SQL Server management Studio may helps a lot with more than 60+ formatter options.

is there any PHP function for open page in new tab

You can write JavaScript code in your file .

Put following code in your client side file:


    window.onload = function(){, "_blank"); // will open new tab on window.onload

using jQuery.ready

  $(document).ready(function(){, "_blank"); // will open new tab on document ready

How do malloc() and free() work?

This has nothing specifically to do with malloc and free. Your program exhibits undefined behaviour after you copy the string - it could crash at that point or at any point afterwards. This would be true even if you never used malloc and free, and allocated the char array on the stack or statically.

MySQL: Insert record if not exists in table

This query can be used in PHP code.

I have an ID column in this table, so I need check for duplication for all columns except this ID column:

#need to change values
SET @goodsType = 1, @sybType=5, @deviceId = asdf12345SDFasdf2345;    

INSERT INTO `devices` (`goodsTypeId`, `goodsId`, `deviceId`) #need to change tablename and columnsnames
SELECT * FROM (SELECT @goodsType, @sybType, @deviceId) AS tmp
    SELECT 'goodsTypeId' FROM `devices` #need to change tablename and columns names
    WHERE `goodsTypeId` = @goodsType
        AND `goodsId` = @sybType
        AND `deviceId` = @deviceId
) LIMIT 1;

and now new item will be added only in case of there is not exist row with values configured in SET string

How to get the file name from a full path using JavaScript?

function getFileName(path, isExtension){

  var fullFileName, fileNameWithoutExtension;

  // replace \ to /
  while( path.indexOf("\\") !== -1 ){
    path = path.replace("\\", "/");

  fullFileName = path.split("/").pop();
  return (isExtension) ? fullFileName : fullFileName.slice( 0, fullFileName.lastIndexOf(".") );

C# Lambda expressions: Why should I use them?

Lambda expressions are a simpler syntax for anonymous delegates and can be used everywhere an anonymous delegate can be used. However, the opposite is not true; lambda expressions can be converted to expression trees which allows for a lot of the magic like LINQ to SQL.

The following is an example of a LINQ to Objects expression using anonymous delegates then lambda expressions to show how much easier on the eye they are:

// anonymous delegate
var evens = Enumerable
                .Range(1, 100)
                .Where(delegate(int x) { return (x % 2) == 0; })

// lambda expression
var evens = Enumerable
                .Range(1, 100)
                .Where(x => (x % 2) == 0)

Lambda expressions and anonymous delegates have an advantage over writing a separate function: they implement closures which can allow you to pass local state to the function without adding parameters to the function or creating one-time-use objects.

Expression trees are a very powerful new feature of C# 3.0 that allow an API to look at the structure of an expression instead of just getting a reference to a method that can be executed. An API just has to make a delegate parameter into an Expression<T> parameter and the compiler will generate an expression tree from a lambda instead of an anonymous delegate:

void Example(Predicate<int> aDelegate);

called like:

Example(x => x > 5);


void Example(Expression<Predicate<int>> expressionTree);

The latter will get passed a representation of the abstract syntax tree that describes the expression x > 5. LINQ to SQL relies on this behavior to be able to turn C# expressions in to the SQL expressions desired for filtering / ordering / etc. on the server side.

reading and parsing a TSV file, then manipulating it for saving as CSV (*efficiently*)

You should use the csv module to read the tab-separated value file. Do not read it into memory in one go. Each row you read has all the information you need to write rows to the output CSV file, after all. Keep the output file open throughout.

import csv

with open('sample.txt', newline='') as tsvin, open('new.csv', 'w', newline='') as csvout:
    tsvin = csv.reader(tsvin, delimiter='\t')
    csvout = csv.writer(csvout)

    for row in tsvin:
        count = int(row[4])
        if count > 0:
            csvout.writerows([row[2:4] for _ in range(count)])

or, using the itertools module to do the repeating with itertools.repeat():

from itertools import repeat
import csv

with open('sample.txt', newline='') as tsvin, open('new.csv', 'w', newline='') as csvout:
    tsvin = csv.reader(tsvin, delimiter='\t')
    csvout = csv.writer(csvout)

    for row in tsvin:
        count = int(row[4])
        if count > 0:
            csvout.writerows(repeat(row[2:4], count))

How to click a href link using Selenium

Thi is your code :

Driver.findElement(By.xpath(//a[@href ='/docs/configuration']")).click();

You missed the Quotation mark

it should be as below


Hope this helps!

Store a closure as a variable in Swift

In Swift 4 and 5. I created a closure variable containing two parameter dictionary and bool.

 var completionHandler:([String:Any], Bool)->Void = { dict, success  in
    if success {

Calling the closure variable

self.completionHandler(["name":"Gurjinder singh"],true)

how do I insert a column at a specific column index in pandas?

see docs:

using loc = 0 will insert at the beginning

df.insert(loc, column, value)

df = pd.DataFrame({'B': [1, 2, 3], 'C': [4, 5, 6]})

   B  C
0  1  4
1  2  5
2  3  6

idx = 0
new_col = [7, 8, 9]  # can be a list, a Series, an array or a scalar   
df.insert(loc=idx, column='A', value=new_col)

   A  B  C
0  7  1  4
1  8  2  5
2  9  3  6

error: expected primary-expression before ')' token (C)

A function call needs to be performed with objects. You are doing the equivalent of this:

// function declaration/definition
void foo(int) {}

// function call
foo(int); // wat!??

i.e. passing a type where an object is required. This makes no sense in C or C++. You need to be doing

int i = 42;



MVC Calling a view from a different controller

You can move you read.aspx view to Shared folder. It is standard way in such circumstances

Find unused code

The truth is that the tool can never give you a 100% certain answer, but coverage tool can give you a pretty good run for the money.

If you count with comprehensive unit test suite, than you can use test coverage tool to see exactly what lines of code were not executed during the test run. You will still need to analyze the code manually: either eliminate what you consider dead code or write test to improve test coverage.

One such tool is NCover, with open source precursor on Sourceforge. Another alternative is PartCover.

Check out this answer on stackoverflow.

Double % formatting question for printf in Java

Yes, %d is for decimal (integer), double expect %f. But simply using %f will default to up to precision 6. To print all of the precision digits for a double, you can pass it via string as:

System.out.printf("%s \r\n",String.valueOf(d));


System.out.printf("%s \r\n",Double.toString(d));

This is what println do by default:


(and terminates the line)

TypeScript error: Type 'void' is not assignable to type 'boolean'

It means that the callback function you passed to should return a boolean and have 3 parameters, two of which can be optional:

  • value: Conversations
  • index: number
  • obj: Conversation[]

However, your callback function does not return anything (returns void). You should pass a callback function with the correct return value:, index, obj) => {
    // ...

    return true; // or false

or: => {
    // ...

    return true; // or false

Reason why it's this way: the function you pass to the find method is called a predicate. The predicate here defines a boolean outcome based on conditions defined in the function itself, so that the find method can determine which value to find.

In practice, this means that the predicate is called for each item in data, and the first item in data for which your predicate returns true is the value returned by find.

How to switch between hide and view password

To show the dots instead of the password set the PasswordTransformationMethod:

yourEditText.setTransformationMethod(new PasswordTransformationMethod());

of course you can set this by default in your edittext element in the xml layout with


To re-show the readable password, just pass null as transformation method:


Remote desktop connection protocol error 0x112f

Might not be a solution for all but I found that if I reduced the screen resolution of the RDP session, I was able to get in. The server was at 95% capacity I went from 3 high res monitors to 1 800x600 window.

C++ style cast from unsigned char * to const char *

char * and const unsigned char * are considered unrelated types. So you want to use reinterpret_cast.

But if you were going from const unsigned char* to a non const type you'd need to use const_cast first. reinterpret_cast cannot cast away a const or volatile qualification.

How to change button background image on mouseOver?

I think something like this:

btn.BackgroundImage = Properties.Resources.*Image_Identifier*;

Where *Image_Identifier* is an identifier of the image in your resources.

How to replace (null) values with 0 output in PIVOT


Order a List (C#) by many fields?

Make your object something like

public class MyObject : IComparable
    public string a;
    public string b;

    virtual public int CompareTo(object obj)
        if (obj is MyObject)
            var compareObj = (MyObject)obj;
            if (this.a.CompareTo(compareObj.a) == 0)
                // compare second value
                return this.b.CompareTo(compareObj.b);
            return this.a.CompareTo(compareObj.b);
            throw new ArgumentException("Object is not a MyObject ");

also note that the returns for CompareTo :

Then, if you have a List of MyObject, call .Sort() ie

var objList = new List<MyObject>();

Align printf output in Java

You can try the below example. Do use '-' before the width to ensure left indentation. By default they will be right indented; which may not suit your purpose.

System.out.printf("%2d. %-20s $%.2f%n",  i + 1, BOOK_TYPE[i], COST[i]);

Format String Syntax:

Formatting Numeric Print Output:

PS: This could go as a comment to DwB's answer, but i still don't have permissions to comment and so answering it.

Run Command Line & Command From VBS

Set oShell = CreateObject ("WScript.Shell") "cmd.exe /C copy ""S:Claims\Sound.wav"" ""C:\WINDOWS\Media\Sound.wav"" "

Serializing a list to JSON

.NET already supports basic Json serialization through the System.Runtime.Serialization.Json namespace and the DataContractJsonSerializer class since version 3.5. As the name implies, DataContractJsonSerializer takes into account any data annotations you add to your objects to create the final Json output.

That can be handy if you already have annotated data classes that you want to serialize Json to a stream, as described in How To: Serialize and Deserialize JSON Data. There are limitations but it's good enough and fast enough if you have basic needs and don't want to add Yet Another Library to your project.

The following code serializea a list to the console output stream. As you see it is a bit more verbose than Json.NET and not type-safe (ie no generics)

        var list = new List<string> {"a", "b", "c", "d"};

        using(var output = Console.OpenStandardOutput())                
            var writer = new DataContractJsonSerializer(typeof (List<string>));

On the other hand, Json.NET provides much better control over how you generate Json. This will come in VERY handy when you have to map javascript-friendly names names to .NET classes, format dates to json etc.

Another option is ServiceStack.Text, part of the ServicStack ... stack, which provides a set of very fast serializers for Json, JSV and CSV.

Targeting both 32bit and 64bit with Visual Studio in same solution/project

If you use Custom Actions written in .NET as part of your MSI installer then you have another problem.

The 'shim' that runs these custom actions is always 32bit then your custom action will run 32bit as well, despite what target you specify.

More info & some ninja moves to get around (basically change the MSI to use the 64 bit version of this shim)

Building an MSI in Visual Studio 2005/2008 to work on a SharePoint 64

64-bit Managed Custom Actions with Visual Studio

How to customise file type to syntax associations in Sublime Text?

for ST3

$language = "language u wish"

if exists,

go to ~/.config/sublime-text-3/Packages/User/$language.sublime-settings


create ~/.config/sublime-text-3/Packages/User/$language.sublime-settings

and set

{ "extensions": [ "yourextension" ] }

This way allows you to enable syntax for composite extensions (e.g. sql.mustache, js.php, etc ... )

submitting a form when a checkbox is checked

                if( $(this).is(":checked") )

Though it would probably be better to add classes to each of the checkboxes and do


so that you can choose which checkboxes submit the form instead of all of them doing it.

Set min-width either by content or 200px (whichever is greater) together with max-width

The problem is that flex: 1 sets flex-basis: 0. Instead, you need

.container .box {
  min-width: 200px;
  max-width: 400px;
  flex-basis: auto; /* default value */
  flex-grow: 1;

.container {_x000D_
  display: -webkit-flex;_x000D_
  display: flex;_x000D_
  -webkit-flex-wrap: wrap;_x000D_
  flex-wrap: wrap;_x000D_
.container .box {_x000D_
  -webkit-flex-grow: 1;_x000D_
  flex-grow: 1;_x000D_
  min-width: 100px;_x000D_
  max-width: 400px;_x000D_
  height: 200px;_x000D_
  background-color: #fafa00;_x000D_
  overflow: hidden;_x000D_
<div class="container">_x000D_
  <div class="box">_x000D_
    </table>    _x000D_
  <div class="box">_x000D_
    </table>    _x000D_
  <div class="box">_x000D_
    </table>    _x000D_

select rows in sql with latest date for each ID repeated multiple times

One way is:

select table.* 
from table
    select ID, max(Date) as max_dt 
    from table
    group by ID
) t
on table.ID= t.ID and table.Date = t.max_dt 

Note that if you have multiple equally higher dates for same ID, then you will get all those rows in result

No plot window in matplotlib

Modern IPython uses the "--matplotlib" argument with an optional backend parameter. It defaults to "auto", which is usually good enough on Mac and Windows. I haven't tested it on Ubuntu or any other Linux distribution, but I would expect it to work.

ipython --matplotlib

bash script use cut command at variable and store result at another variable

You can avoid the loop and cut etc by using:

awk -F ':' '{system("ping " $1);}' config.txt

However it would be better if you post a snippet of your config.txt

How to hide Android soft keyboard on EditText

My test result:

with setInputType:


the soft keyboard disappears, but the cursor will also disappear.

with setShowSoftInputOnFocus:


It works as expected.

How to check whether an array is empty using PHP?

Some decent answers, but just thought I'd expand a bit to explain more clearly when PHP determines if an array is empty.

Main Notes:

An array with a key (or keys) will be determined as NOT empty by PHP.

As array values need keys to exist, having values or not in an array doesn't determine if it's empty, only if there are no keys (AND therefore no values).

So checking an array with empty() doesn't simply tell you if you have values or not, it tells you if the array is empty, and keys are part of an array.

So consider how you are producing your array before deciding which checking method to use.
EG An array will have keys when a user submits your HTML form when each form field has an array name (ie name="array[]").
A non empty array will be produced for each field as there will be auto incremented key values for each form field's array.

Take these arrays for example:

/* Assigning some arrays */

// Array with user defined key and value
$ArrayOne = array("UserKeyA" => "UserValueA", "UserKeyB" => "UserValueB");

// Array with auto increment key and user defined value
// as a form field would return with user input
$ArrayTwo[] = "UserValue01";
$ArrayTwo[] = "UserValue02";

// Array with auto incremented key and no value
// as a form field would return without user input
$ArrayThree[] = '';
$ArrayThree[] = '';

If you echo out the array keys and values for the above arrays, you get the following:

[UserKeyA] => [UserValueA]
[UserKeyB] => [UserValueB]

[0] => [UserValue01]
[1] => [UserValue02]

[0] => []
[1] => []

And testing the above arrays with empty() returns the following results:

$ArrayOne is not empty

$ArrayTwo is not empty

$ArrayThree is not empty

An array will always be empty when you assign an array but don't use it thereafter, such as:

$ArrayFour = array();

This will be empty, ie PHP will return TRUE when using if empty() on the above.

So if your array has keys - either by eg a form's input names or if you assign them manually (ie create an array with database column names as the keys but no values/data from the database), then the array will NOT be empty().

In this case, you can loop the array in a foreach, testing if each key has a value. This is a good method if you need to run through the array anyway, perhaps checking the keys or sanitising data.

However it is not the best method if you simply need to know "if values exist" returns TRUE or FALSE. There are various methods to determine if an array has any values when it's know it will have keys. A function or class might be the best approach, but as always it depends on your environment and exact requirements, as well as other things such as what you currently do with the array (if anything).

Here's an approach which uses very little code to check if an array has values:

Using array_filter():
Iterates over each value in the array passing them to the callback function. If the callback function returns true, the current value from array is returned into the result array. Array keys are preserved.

$EmptyTestArray = array_filter($ArrayOne);

if (!empty($EmptyTestArray))
    // do some tests on the values in $ArrayOne
    // Likely not to need an else, 
    // but could return message to user "you entered nothing" etc etc

Running array_filter() on all three example arrays (created in the first code block in this answer) results in the following:

$arrayone is not empty

$arraytwo is not empty

$arraythree is empty

So when there are no values, whether there are keys or not, using array_filter() to create a new array and then check if the new array is empty shows if there were any values in the original array.
It is not ideal and a bit messy, but if you have a huge array and don't need to loop through it for any other reason, then this is the simplest in terms of code needed.

I'm not experienced in checking overheads, but it would be good to know the differences between using array_filter() and foreach checking if a value is found.

Obviously benchmark would need to be on various parameters, on small and large arrays and when there are values and not etc.

Is it possible to set the stacking order of pseudo-elements below their parent element?

Try it out

el {
  transform-style: preserve-3d;
el:after {
  transform: translateZ(-1px);

How to get Domain name from URL using jquery..?

var hostname = window.location.origin

Will not work for IE. For IE support as well I would something like this:

var hostName = window.location.hostname;
var protocol = window.locatrion.protocol;
var finalUrl = protocol + '//' + hostname;

How to use vertical align in bootstrap

For the parent: display: table;

For the child: display: table-cell;

Then add vertical-align: middle;

I can make a fiddle but home time now, yay!

OK here is the lovely fiddle:

.parent {

.child {

How to create a data file for gnuplot?

Just go to the properties of your cmd.exe shortcut and change the 'start in' by adding the file name where you put all your '.txt' files.I had same problems and i put the whole file mane as 'D:\photon' in the 'start in' of the properties and it worked.Remember you have to put all your files in that folder otherwise you have to create many shortcuts for each data files.Sorry for late reply

How to change the map center in Leaflet.js

You can also use:

map.setView(new L.LatLng(40.737, -73.923), 8);

It just depends on what behavior you want. map.panTo() will pan to the location with zoom/pan animation, while map.setView() immediately set the new view to the desired location/zoom level.

Regex: match everything but specific pattern

Just match /^index\.php/ then reject whatever matches it.

What's with the dollar sign ($"string")

String Interpolation

is a concept that languages like Perl have had for quite a while, and now we’ll get this ability in C# as well. In String Interpolation, we simply prefix the string with a $ (much like we use the @ for verbatim strings). Then, we simply surround the expressions we want to interpolate with curly braces (i.e. { and }):

It looks a lot like the String.Format() placeholders, but instead of an index, it is the expression itself inside the curly braces. In fact, it shouldn’t be a surprise that it looks like String.Format() because that’s really all it is – syntactical sugar that the compiler treats like String.Format() behind the scenes.

A great part is, the compiler now maintains the placeholders for you so you don’t have to worry about indexing the right argument because you simply place it right there in the string.

C# string interpolation is a method of concatenating,formatting and manipulating strings. This feature was introduced in C# 6.0. Using string interpolation, we can use objects and expressions as a part of the string interpolation operation.

Syntax of string interpolation starts with a ‘$’ symbol and expressions are defined within a bracket {} using the following syntax.



  • interpolatedExpression - The expression that produces a result to be formatted
  • alignment - The constant expression whose value defines the minimum number of characters in the string representation of the result of the interpolated expression. If positive, the string representation is right-aligned; if negative, it's left-aligned.
  • formatString - A format string that is supported by the type of the expression result.

The following code example concatenates a string where an object, author as a part of the string interpolation.

string author = "Mohit";  
string hello = $"Hello {author} !";  
Console.WriteLine(hello);  // Hello Mohit !

Read more on C#/.NET Little Wonders: String Interpolation in C# 6

pandas: How do I split text in a column into multiple rows?

This seems a far easier method than those suggested elsewhere in this thread.

split rows in pandas dataframe

Easy interview question got harder: given numbers 1..100, find the missing number(s) given exactly k are missing

Wait a minute. As the question is stated, there are 100 numbers in the bag. No matter how big k is, the problem can be solved in constant time because you can use a set and remove numbers from the set in at most 100 - k iterations of a loop. 100 is constant. The set of remaining numbers is your answer.

If we generalise the solution to the numbers from 1 to N, nothing changes except N is not a constant, so we are in O(N - k) = O(N) time. For instance, if we use a bit set, we set the bits to 1 in O(N) time, iterate through the numbers, setting the bits to 0 as we go (O(N-k) = O(N)) and then we have the answer.

It seems to me that the interviewer was asking you how to print out the contents of the final set in O(k) time rather than O(N) time. Clearly, with a bit set, you have to iterate through all N bits to determine whether you should print the number or not. However, if you change the way the set is implemented you can print out the numbers in k iterations. This is done by putting the numbers into an object to be stored in both a hash set and a doubly linked list. When you remove an object from the hash set, you also remove it from the list. The answers will be left in the list which is now of length k.

How to calculate the inverse of the normal cumulative distribution function in python?

# given random variable X (house price) with population muy = 60, sigma = 40
import scipy as sc
import scipy.stats as sct
sc.version.full_version # 0.15.1

#a. Find P(X<50)
sct.norm.cdf(x=50,loc=60,scale=40) # 0.4012936743170763

#b. Find P(X>=50)
sct.norm.sf(x=50,loc=60,scale=40) # 0.5987063256829237

#c. Find P(60<=X<=80)
sct.norm.cdf(x=80,loc=60,scale=40) - sct.norm.cdf(x=60,loc=60,scale=40)

#d. how much top most 5% expensive house cost at least? or find x where P(X>=x) = 0.05

#e. how much top most 5% cheapest house cost at least? or find x where P(X<=x) = 0.05

PostgreSQL: Resetting password of PostgreSQL on Ubuntu

Assuming you're the administrator of the machine, Ubuntu has granted you the right to sudo to run any command as any user.
Also assuming you did not restrict the rights in the pg_hba.conf file (in the /etc/postgresql/9.1/main directory), it should contain this line as the first rule:

# Database administrative login by Unix domain socket  
local   all             postgres                                peer

(About the file location: 9.1 is the major postgres version and main the name of your "cluster". It will differ if using a newer version of postgres or non-default names. Use the pg_lsclusters command to obtain this information for your version/system).

Anyway, if the pg_hba.conf file does not have that line, edit the file, add it, and reload the service with sudo service postgresql reload.

Then you should be able to log in with psql as the postgres superuser with this shell command:

sudo -u postgres psql

Once inside psql, issue the SQL command:

ALTER USER postgres PASSWORD 'newpassword';

In this command, postgres is the name of a superuser. If the user whose password is forgotten was ritesh, the command would be:

ALTER USER ritesh PASSWORD 'newpassword';

References: PostgreSQL 9.1.13 Documentation, Chapter 19. Client Authentication

Keep in mind that you need to type postgres with a single S at the end

If leaving the password in clear text in the history of commands or the server log is a problem, psql provides an interactive meta-command to avoid that, as an alternative to ALTER USER ... PASSWORD:

\password username

It asks for the password with a double blind input, then hashes it according to the password_encryption setting and issue the ALTER USER command to the server with the hashed version of the password, instead of the clear text version.

A regex for version number parsing

I tend to agree with split suggestion.

Ive created a "tester" for your problem in perl

#!/usr/bin/perl -w

@strings = ( "1.2.3", "1.2.*", "1.*","*" );

%regexp = ( svrist => qr/(?:(\d+)\.(\d+)\.(\d+)|(\d+)\.(\d+)|(\d+))?(?:\.\*)?/,
            onebyone => qr/^(\d+\.)?(\d+\.)?(\*|\d+)$/,
            greg => qr/^(\*|\d+(\.\d+){0,2}(\.\*)?)$/,
            vonc => qr/^((?:\d+(?!\.\*)\.)+)(\d+)?(\.\*)?$|^(\d+)\.\*$|^(\*|\d+)$/,
            ajb => qr/^(?:(\d+)\.)?(?:(\d+)\.)?(\*|\d+)$/,
            jrudolph => qr/^(((\d+)\.)?(\d+)\.)?(\d+|\*)$/

  foreach my $r (keys %regexp){
    my $reg = $regexp{$r};
    print "Using $r regexp\n";
foreach my $s (@strings){
  print "$s : ";

    if ($s =~m/$reg/){
    my ($main, $maj, $min,$rev,$ex1,$ex2,$ex3) = ("any","any","any","any","any","any","any");
    $main = $1 if ($1 && $1 ne "*") ;
    $maj = $2 if ($2 && $2 ne "*") ;
    $min = $3 if ($3 && $3 ne "*") ;
    $rev = $4 if ($4 && $4 ne "*") ;
    $ex1 = $5 if ($5 && $5 ne "*") ;
    $ex2 = $6 if ($6 && $6 ne "*") ;
    $ex3 = $7 if ($7 && $7 ne "*") ;
    print "$main $maj $min $rev $ex1 $ex2 $ex3\n";

  print " nomatch\n";
print "------------------------\n";

Current output:

> perl
Using onebyone regexp
1.2.3 : 1. 2. 3 any any any any
1.2.* : 1. 2. any any any any any
1.* : 1. any any any any any any
* : any any any any any any any
Using svrist regexp
1.2.3 : 1 2 3 any any any any
1.2.* : any any any 1 2 any any
1.* : any any any any any 1 any
* : any any any any any any any
Using vonc regexp
1.2.3 : 1.2. 3 any any any any any
1.2.* : 1. 2 .* any any any any
1.* : any any any 1 any any any
* : any any any any any any any
Using ajb regexp
1.2.3 : 1 2 3 any any any any
1.2.* : 1 2 any any any any any
1.* : 1 any any any any any any
* : any any any any any any any
Using jrudolph regexp
1.2.3 : 1.2. 1. 1 2 3 any any
1.2.* : 1.2. 1. 1 2 any any any
1.* : 1. any any 1 any any any
* : any any any any any any any
Using greg regexp
1.2.3 : 1.2.3 .3 any any any any any
1.2.* : 1.2.* .2 .* any any any any
1.* : 1.* any .* any any any any
* : any any any any any any any

Rendering partial view on button click in ASP.NET MVC

So here is the controller code.

public IActionResult AddURLTest()
    return ViewComponent("AddURL");

You can load it using JQuery load method.

$(document).ready (function(){

source code link

How do I fire an event when a iframe has finished loading in jQuery?

This did it for me (not pdf, but another "onload resistant" content):

<iframe id="frameid" src="page.aspx"></iframe>
<script language="javascript">
    iframe = document.getElementById("frameid");


    function WaitForIFrame() {
        if (iframe.readyState != "complete") {
            setTimeout("WaitForIFrame();", 200);
        } else {

    function done() {
        //some code after iframe has been loaded

Hope this helps.

Mixing a PHP variable with a string literal

You can use {} arround your variable, to separate it from what's after:

echo "{$test}y"

As reference, you can take a look to the Variable parsing - Complex (curly) syntax section of the PHP manual.

how to get param in method post spring mvc?

When I want to get all the POST params I am using the code below,

@RequestMapping(value = "/", method = RequestMethod.POST)
public ViewForResponseClass update(@RequestBody AClass anObject) {
    // Source..

I am using the @RequestBody annotation for post/put/delete http requests instead of the @RequestParam which reads the GET parameters.

A column-vector y was passed when a 1d array was expected

use below code:

model =, train_y.ravel())

if you are still getting slap by error as identical as below ?

Unknown label type: %r" % y

use this code:

y = train_y.ravel()
train_y = np.array(y).astype(int)
model =, train_y)

How do I properly compare strings in C?

Whenever you are trying to compare the strings, compare them with respect to each character. For this you can use built in string function called strcmp(input1,input2); and you should use the header file called #include<string.h>

Try this code:


int main() 
    char s[]="STACKOVERFLOW";
    char s1[200];
    printf("Enter the string to be checked\n");//enter the input string
    if(strcmp(s,s1)==0)//compare both the strings  
        printf("Both the Strings match\n"); 
        printf("Entered String does not match\n");  

How to start rails server?

For the latest version of Rails (Rails 5.1.4 released September 7, 2017), you need to start Rails server like below:

hello_world_rails_project$ ./bin/rails server

=> Booting Puma
=> Rails 5.1.4 application starting in development 
=> Run `rails server -h` for more startup options
Puma starting in single mode...
* Version 3.10.0 (ruby 2.4.2-p198), codename: Russell's Teapot
* Min threads: 5, max threads: 5
* Environment: development
* Listening on tcp://

More help information:

hello_world_rails_project$ ./bin/rails --help

The most common rails commands are:
generate     Generate new code (short-cut alias: "g")
console      Start the Rails console (short-cut alias: "c")
server       Start the Rails server (short-cut alias: "s")
test         Run tests except system tests (short-cut alias: "t")
test:system  Run system tests
dbconsole    Start a console for the database specified in 
             (short-cut alias: "db")

new          Create a new Rails application. "rails new my_app" creates a
             new application called MyApp in "./my_app"

Get current URL path in PHP

function current_url()
    $url      = "http://" . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
    $validURL = str_replace("&", "&amp", $url);
    return $validURL;
//echo "page URL is : ".current_url();

$offer_url = current_url();



if ($offer_url == "checking url name") {
?> <p> hi this is manip5595 </p>


Resolving LNK4098: defaultlib 'MSVCRT' conflicts with

Right-click the project, select Properties then under 'Configuration properties | Linker | Input | Ignore specific Library and write msvcrtd.lib

Assign a class name to <img> tag instead of write it in css file?

Assigning a class name and applying a CSS style are two different things.

If you mean <img class="someclass">, and

.someclass {

, then there is no real performance difference between applying the css to the class, or to .column img

UnicodeDecodeError: 'ascii' codec can't decode byte 0xc2


# encoding=utf8

Try This to starting of python file

Access a URL and read Data with R

Beside of read.csv(url("...")) you also can use read.table("http://...").


> sample <- read.table("")
> sample
                V1   V2   V3   V4 V5
1        Rochester 19.0 20.6 15.0  E
2         Syracuse 17.0 15.6 20.2  E
43         Atlanta  4.2 70.6 32.6  S

How to replace a whole line with sed?

If you would like to use awk then this would work too

awk -F= '{$2="xxx";print}' OFS="\=" filename

I lose my data when the container exits

the similar problem (and no way Dockerfile alone could fix it) brought me to this page.

stage 0: for all, hoping Dockerfile could fix it: until --dns and --dns-search will appear in Dockerfile support - there is no way to integrate intranet based resources into.

stage 1: after building image using Dockerfile (by the way it's a serious glitch Dockerfile must be in the current folder), having an image to deploy what's intranet based, by running docker run script. example: docker run -d \ --dns=${DNSLOCAL} \ --dns=${DNSGLOBAL} \ --dns-search=intranet \ -t pack/bsp \ --name packbsp-cont \ bash -c " \ wget -r --no-parent http://intranet/intranet-content.tar.gz \ tar -xvf intranet-content.tar.gz \ sudo -u ${USERNAME} bash --norc"

stage 2: applying docker run script in daemon mode providing local dns records to have ability to download and deploy local stuff.

important point: run script should be ending with something like /usr/bin/sudo -u ${USERNAME} bash --norc to keep container running even after the installation scripts finishes.

no, it's not possible to run container in interactive mode for the full automation matter as it will remain inside internal shall command prompt until CTRL-p CTRL-q being pressed.

no, if interacting bash will not be executed at the end of the installation script, the container will terminate immediately after finishes script execution, loosing all installation results.

stage 3: container is still running in background but it's unclear whether container has ended installation procedure or not yet. using following block to determine execution procedure finishes: while ! docker container top ${CONTNAME} | grep "00[[:space:]]\{12\}bash \--norc" - do echo "." sleep 5 done the script will proceed further only after completed installation. and this is the right moment to call: commit, providing current container id as well as destination image name (it may be the same as on the build/run procedure but appended with the local installation purposes tag. example: docker commit containerID pack/bsp:toolchained. see this link on how to get proper containerID

stage 4: container has been updated with the local installs as well as it has been committed into newly assigned image (the one having purposes tag added). it's safe now to stop container running. example: docker stop packbsp-cont

stage5: any moment the container with local installs require to run, start it with the image previously saved. example: docker run -d -t pack/bsp:toolchained

onchange event for input type="number"

To detect when mouse or key are pressed, you can also write:

$(document).on('keyup mouseup', '#your-id', function() {                                                                                                                     

What is the best way to trigger onchange event in react js

I know this answer comes a little late but I recently faced a similar problem. I wanted to trigger an event on a nested component. I had a list with radio and check box type widgets (they were divs that behaved like checkboxes and/or radio buttons) and in some other place in the application, if someone closed a toolbox, I needed to uncheck one.

I found a pretty simple solution, not sure if this is best practice but it works.

var event = new MouseEvent('click', {
 'view': window, 
 'bubbles': true, 
 'cancelable': false
var node = document.getElementById('nodeMyComponentsEventIsConnectedTo');

This triggered the click event on the domNode and my handler attached via react was indeed called so it behaves like I would expect if someone clicked on the element. I have not tested onChange but it should work, and not sure how this will fair in really old versions of IE but I believe the MouseEvent is supported in at least IE9 and up.

I eventually moved away from this for my particular use case because my component was very small (only a part of my application used react since i'm still learning it) and I could achieve the same thing another way without getting references to dom nodes.


As others have stated in the comments, it is better to use this.refs.refname to get a reference to a dom node. In this case, refname is the ref you attached to your component via <MyComponent ref='refname' />.

Proper way to catch exception from JSON.parse

I am fairly new to Javascript. But this is what I understood: JSON.parse() returns SyntaxError exceptions when invalid JSON is provided as its first parameter. So. It would be better to catch that exception as such like as follows:

try {
    let sData = `
            "id": "1",
            "name": "UbuntuGod",
} catch (objError) {
    if (objError instanceof SyntaxError) {
    } else {

The reason why I made the words "first parameter" bold is that JSON.parse() takes a reviver function as its second parameter.

How to clear all data in a listBox?

Try this:

 private void cleanlistbox(object sender, EventArgs e)
     listBox1.DataSource = null;

Android Facebook 4.0 SDK How to get Email, Date of Birth and gender of User

This is worked for me, Hope to help someone (Using my own button not FB login button )

CallbackManager callbackManager;

protected void onCreate(Bundle savedInstanceState) {

     LoginManager.getInstance().registerCallback(callbackManager, new FacebookCallback<LoginResult>() {
        public void onSuccess(LoginResult loginResult) {

            GraphRequest request = GraphRequest.newMeRequest(loginResult.getAccessToken(), new GraphRequest.GraphJSONObjectCallback() {
                public void onCompleted(JSONObject object, GraphResponse response) {
                    try {
                        Log.i("RESAULTS : ", object.getString("email"));
                    }catch (Exception e){

            Bundle parameters = new Bundle();
            parameters.putString("fields", "email");


        public void onCancel() {


        public void onError(FacebookException error) {
            Log.i("RESAULTS : ", error.getMessage());


protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    callbackManager.onActivityResult(requestCode, resultCode, data);
    super.onActivityResult(requestCode, resultCode, data);

boolean isEmailValid(CharSequence email) {
    return android.util.Patterns.EMAIL_ADDRESS.matcher(email).matches();

public void signupwith_facebook(View view) {

    LoginManager.getInstance().logInWithReadPermissions(this, Arrays.asList("public_profile","email"));

Insert line after first match using sed

Try doing this using GNU sed:

sed '/CLIENTSCRIPT="foo"/a CLIENTSCRIPT2="hello"' file

if you want to substitute in-place, use

sed -i '/CLIENTSCRIPT="foo"/a CLIENTSCRIPT2="hello"' file




  • see sed doc and search \a (append)

How can I parse a String to BigDecimal?

Try the correct constructor

You can directly instanciate the BigDecimal with the String ;)


BigDecimal bigDecimalValue= new BigDecimal("0.5");

How to cast ArrayList<> from List<>

May be:

ArrayList<ServiceModel> services = new ArrayList<>(parking.getServices());

Using margin:auto to vertically-align a div

.black {
.message {
    position: absolute;
    left: 50%;
    transform: translate(-50%, -50%);



<div class="black">
<div class="message">
    This is a popup message.

How to replace list item in best way

You could make it more readable and more efficient:

string oldValue = valueFieldValue.ToString();
string newValue = value.ToString();
int index = listofelements.IndexOf(oldValue);
if(index != -1)
    listofelements[index] = newValue;

This asks only once for the index. Your approach uses Contains first which needs to loop all items(in the worst case), then you're using IndexOf which needs to enumerate the items again .

Redirect to new Page in AngularJS using $location

The line

$location.absUrl() == '';

is wrong. First == makes a comparison, and what you are probably trying to do is an assignment, which is with simple = and not double ==.

And because absUrl() getter only. You can use url(), which can be used as a setter or as a getter if you want.

reference :$location

How to deserialize JS date using Jackson?

@JsonFormat only work for standard format supported by the jackson version that you are using.

Ex :- compatible with any of standard forms ("yyyy-MM-dd'T'HH:mm:ss.SSSZ", "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'", "EEE, dd MMM yyyy HH:mm:ss zzz", "yyyy-MM-dd")) for jackson 2.8.6

Dynamic Height Issue for UITableView Cells (Swift)

In addition to what others have said,


So instead of placing your label's constraints relative to other things around it, constrain it to the table view cell's content view.

Then, make sure your label's height is set to more than or equal 0, and the number of lines is set to 0.

Then in ViewDidLoad add:

tableView.estimatedRowHeight = 695

tableView.rowHeight = UITableViewAutomaticDimension

node.js require() cache - possible to invalidate?

I made a small module to delete module from the cache after loading. This forces reevaluation of the module next time it is required. See

// random.js
module.exports = Math.random()
const forget = require('require-and-forget')
const r1 = forget('./random')
const r2 = forget('./random')
// r1 and r2 will be different
// "random.js" will not be stored in the require.cache

PS: you can also put "self-destruct" into the module itself. See

PSS: more tricks with Node require in my

how can the textbox width be reduced?

<input type='text' 
       placeholder='typing some text' >

This is the text box, it has a fixed length of 10 characters, and if you can try but this text box does not contain maximum length 10 character

Table with fixed header and fixed column on pure css

All of these suggestions are great and all, but they're either only fixing either the header or a column, not both, or they're using javascript. The reason - it don't believe it can be done in pure CSS. The reason:

If it were possible to do it, you would need to nest several scrollable divs one inside the other, each with a scroll in a different direction. Then you would need to split your table into three parts - the fixed header, the fixed column and the rest of the data.

Fine. But now the problem - you can make one of them stay put when you scroll, but the other one is nested inside the scrolling area of first and is therefore subject to being scrolled out of sight itself, so can't be fixed in place on the screen. 'Ah-ha' you say 'but I can somehow use absolute or fixed position to do that' - no you can't. As soon as you do that you lose the ability to scroll that container. It's a chicken and egg situation - you can't have both, they cancel each other out.

I believe the only solution is through javascript. You need to completely seperate out the three elements and keep their positions in sync through javascript. There are good examples in other posts on this page. This one is also worth a look:

Converting JSON data to Java object

Easy and working java code to convert JSONObject to Java Object

import java.util.HashMap;
import java.util.Map;

import javax.annotation.Generated;

import com.fasterxml.jackson.annotation.JsonAnyGetter;
import com.fasterxml.jackson.annotation.JsonAnySetter;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;

public class Employee {

private Integer id;
private String firstName;
private String lastName;
private Map<String, Object> additionalProperties = new HashMap<String, Object>();

* @return
* The id
public Integer getId() {
return id;

* @param id
* The id
public void setId(Integer id) { = id;

* @return
* The firstName
public String getFirstName() {
return firstName;

* @param firstName
* The firstName
public void setFirstName(String firstName) {
this.firstName = firstName;

* @return
* The lastName
public String getLastName() {
return lastName;

* @param lastName
* The lastName
public void setLastName(String lastName) {
this.lastName = lastName;

public Map<String, Object> getAdditionalProperties() {
return this.additionalProperties;

public void setAdditionalProperty(String name, Object value) {
this.additionalProperties.put(name, value);


import org.codehaus.jettison.json.JSONObject;

import com.fasterxml.jackson.databind.ObjectMapper;

public class LoadFromJSON {

    public static void main(String args[]) throws Exception {
        JSONObject json = new JSONObject();
        json.put("id", 2);
        json.put("firstName", "hello");
        json.put("lastName", "world");

        byte[] jsonData = json.toString().getBytes();

        ObjectMapper mapper = new ObjectMapper();
        Employee employee = mapper.readValue(jsonData, Employee.class);



Split string and get first value only

string valueStr = "title, genre, director, actor";
var vals = valueStr.Split(',')[0];

vals will give you the title

scale fit mobile web content using viewport meta tag

ok, here is my final solution with 100% native javascript:

<meta id="viewport" name="viewport">

<script type="text/javascript">
//mobile viewport hack

  function apply_viewport(){
    if( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent)   ) {

      var ww = window.screen.width;
      var mw = 800; // min width of site
      var ratio =  ww / mw; //calculate ratio
      var viewport_meta_tag = document.getElementById('viewport');
      if( ww < mw){ //smaller than minimum size
        viewport_meta_tag.setAttribute('content', 'initial-scale=' + ratio + ', maximum-scale=' + ratio + ', minimum-scale=' + ratio + ', user-scalable=no, width=' + mw);
      else { //regular size
        viewport_meta_tag.setAttribute('content', 'initial-scale=1.0, maximum-scale=1, minimum-scale=1.0, user-scalable=yes, width=' + ww);

  //ok, i need to update viewport scale if screen dimentions changed
  window.addEventListener('resize', function(){



How to check if command line tools is installed

Go to Applications > Xcode > preferences > downloads

You should see the command line tools there for you to install.

Closing Applications

What role do they play when exiting an application in C#?

The same as every other application. Basically they get returned to the caller. Irrelvant if ythe start was an iicon double click. Relevant is the call is a batch file that decides whether the app worked on the return code. SO, unless you write a program that needs this, the return dcode IS irrelevant.

But what is the difference?

One comes from environment one from the System.Windows.Forms?.Application. Functionall there should not bbe a lot of difference.

How to use multiprocessing queue in Python?

Just made a simple and general example for demonstrating passing a message over a Queue between 2 standalone programs. It doesn't directly answer the OP's question but should be clear enough indicating the concept.


import asyncio
import concurrent.futures
import multiprocessing
import multiprocessing.managers
import queue
import sys
import threading
from typing import Any, AnyStr, Dict, Union

class QueueManager(multiprocessing.managers.BaseManager):

    def get_queue(self, ident: Union[AnyStr, int, type(None)] = None) -> multiprocessing.Queue:

def get_queue(ident: Union[AnyStr, int, type(None)] = None) -> multiprocessing.Queue:
    global q

    if not ident in q:
        q[ident] = multiprocessing.Queue()

    return q[ident]

q: Dict[Union[AnyStr, int, type(None)], multiprocessing.Queue] = dict()
delattr(QueueManager, 'get_queue')

def init_queue_manager_server():
    if not hasattr(QueueManager, 'get_queue'):
        QueueManager.register('get_queue', get_queue)

def serve(no: int, term_ev: threading.Event):
    manager: QueueManager
    with QueueManager(authkey=QueueManager.__name__.encode()) as manager:
        print(f"Server address {no}: {manager.address}")

        while not term_ev.is_set():
                item: Any = manager.get_queue().get(timeout=0.1)
                print(f"Client {no}: {item} from {manager.address}")
            except queue.Empty:

async def main(n: int):
    term_ev: threading.Event = threading.Event()
    executor: concurrent.futures.ThreadPoolExecutor = concurrent.futures.ThreadPoolExecutor()

    i: int
    for i in range(n):
        asyncio.ensure_future(asyncio.get_running_loop().run_in_executor(executor, serve, i, term_ev))

    # Gracefully shut down
        await asyncio.get_running_loop().create_future()
    except asyncio.CancelledError:

if __name__ == '__main__':[1])))


import multiprocessing
import multiprocessing.managers
import os
import sys
from typing import AnyStr, Union

class QueueManager(multiprocessing.managers.BaseManager):

    def get_queue(self, ident: Union[AnyStr, int, type(None)] = None) -> multiprocessing.Queue:

delattr(QueueManager, 'get_queue')

def init_queue_manager_client():
    if not hasattr(QueueManager, 'get_queue'):

def main():

    manager: QueueManager = QueueManager(sys.argv[1], authkey=QueueManager.__name__.encode())

    message = f"A message from {os.getpid()}"
    print(f"Message to send: {message}")

if __name__ == '__main__':



$ python3 N

N is a integer indicating how many servers should be created. Copy one of the <server-address-N> output by the server and make it the first argument of each


python3 <server-address-1>



Client 1: <item> from <server-address-1>


UPD: Created a package here.


import ipcq

with ipcq.QueueManagerServer(address=ipcq.Address.AUTO, authkey=ipcq.AuthKey.AUTO) as server:


import ipcq

client = ipcq.QueueManagerClient(address=ipcq.Address.AUTO, authkey=ipcq.AuthKey.AUTO)
client.get_queue().put('a message')

enter image description here

How can I perform a reverse string search in Excel without using VBA?

To add to Jerry and Joe's answers, if you're wanting to find the text BEFORE the last word you can use:


With 'My little cat' in A1 would result in 'My little' (where Joe and Jerry's would give 'cat'

In the same way that Jerry and Joe isolate the last word, this then just gets everything to the left of that (then trims it back)

Get first key in a (possibly) associative array?

This is the easier way I had ever found. Fast and only two lines of code :-D

$keys = array_keys($array);
echo $array[$keys[0]];

Apache is not running from XAMPP Control Panel ( Error: Apache shutdown unexpectedly. This may be due to a blocked port)

Run these commands in terminal and everything will work fine:

sudo /etc/init.d/apache2 stop   
sudo /opt/lampp/lampp start

Enable the display of line numbers in Visual Studio

Tools -> Options -> Show All Settings -> Text Editor -> All Languages -> Line Numbers

How to make div background color transparent in CSS

The problem with opacity is that it will also affect the content, when often you do not want this to happen.

If you just want your element to be transparent, it's really as easy as :

background-color: transparent;

But if you want it to be in colors, you can use:

background-color: rgba(255, 0, 0, 0.4);

Or define a background image (1px by 1px) saved with the right alpha.
(To do so, use Gimp, Paint.Net or any other image software that allows you to do that.
Just create a new image, delete the background and put a semi-transparent color in it, then save it in png.)

As said by René, the best thing to do would be to mix both, with the rgba first and the 1px by 1px image as a fallback if the browser doesn't support alpha :

background: url('img/red_transparent_background.png');
background: rgba(255, 0, 0, 0.4);

See also :

Demo : My JSFiddle

How to insert Records in Database using C# language?

You should form the command with the contents of the textboxes:

sql = "insert into Main (Firt Name, Last Name) values(" + textbox2.Text + 
"," + textbox3.Text+ ")";

This, of course, provided that you manage to open the connection correctly.

It would be helpful to know what is happening with your current code. If you are getting some error displayed in that message box, it would be great to know what it's saying.

You should also validate the inputs before actually running the command (i.e. make sure they don't contain malicious code).

How do I use Node.js Crypto to create a HMAC-SHA1 hash?

Gwerder's solution wont work because hash =; happens before the stream is done being finalized. Thus AngraX's issues. Also the hmac.write statement is un-necessary in this example.

Instead do this:

var crypto    = require('crypto');
var hmac;
var algorithm = 'sha1';
var key       = 'abcdeg';
var text      = 'I love cupcakes';
var hash;

hmac = crypto.createHmac(algorithm, key);

// readout format:
//or also commonly: hmac.setEncoding('base64');

// callback is attached as listener to stream's finish event:
hmac.end(text, function () {
    hash =;
    // something with the hash...

More formally, if you wish, the line

hmac.end(text, function () {

could be written

hmac.end(text, 'utf8', function () {

because in this example text is a utf string

How to debug Google Apps Script (aka where does Logger.log log to?)

Currently you are confined to the container bound nature of using scripts within docs. If you create a new script inside outside of docs then you will be able to export information to a google spreadsheet and use it like a logging tool.

For example in your first code block

function setCheckboxes() {

    // Add your spreadsheet data
    var errorSheet = SpreadsheetApp.openById('EnterSpreadSheetIDHere').getSheetByName('EnterSheetNameHere');
    var cell = errorSheet.getRange('A1').offset(errorSheet.getLastRow(),0);

    // existing code
    var checklist = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("checklist");
    var checklist_data_range = checklist.getDataRange();
    var checklist_num_rows = checklist_data_range.getNumRows();

    // existing logger
    Logger.log("checklist num rows: " + checklist_num_rows);

   //We can pass the information to the sheet using cell.setValue()
    cell.setValue(new Date() + "Checklist num rows: " + checklist_num_rows);

When I'm working with GAS I have two monitors ( you can use two windows ) set up with one containing the GAS environment and the other containing the SS so I can write information to and log.

How to remove docker completely from ubuntu 14.04

@miyuru. As suggested by him run all the steps.

Ubuntu version 16.04

Still when I ran docker --version it was returning a version. So to uninstall it completely

Again run the dpkg -l | grep -i docker which will list package still there in system.

For example:

ii  docker-ce-cli      5:19.03.6~3-0~ubuntu-xenial               
amd64        Docker CLI: the open-source application container engine

Now remove them as show below :

sudo apt-get purge -y docker-ce-cli

sudo apt-get autoremove -y --purge docker-ce-cli

sudo apt-get autoclean

Hope this will resolve it, as it did in my case.

Using pointer to char array, values in that array can be accessed?

Your should create ptr as follows:

char *ptr;

You have created ptr as an array of pointers to chars. The above creates a single pointer to a char.

Edit: complete code should be:

char *ptr;
char arr[5] = {'a','b','c','d','e'};
ptr = arr;
printf("\nvalue:%c", *(ptr+0));

.htaccess rewrite to redirect root URL to subdirectory

A little googling, gives me these results:

RewriteEngine On
RewriteBase /
RewriteRule ^index.(.*)?$ [r=301]

This will redirect any attempt to access a file named index.something to your subfolder, whether the file exists or not.

Or try this:

RewriteCond %{HTTP_HOST} !^$ [NC]
RewriteRule ^(.*)$ %{HTTP_HOST}/samlse/$1 [R=301,L]

I haven't done much redirect in the .htaccess file, so I'm not sure if this will work.

Multiple file extensions in OpenFileDialog

This is from MSDN sample:

(*.bmp, *.jpg)|*.bmp;*.jpg

So for your case

openFileDialog1.Filter = "JPG (*.jpg,*.jpeg)|*.jpg;*.jpeg|TIFF (*.tif,*.tiff)|*.tif;*.tiff"

<DIV> inside link (<a href="">) tag

Nesting of 'a' will not be possible. However if you badly want to keep the structure and still make it work like the way you want, then override the anchor tag click in javascript /jquery .

so you can have 2 event listeners for the two and control them accordingly.

How do I access refs of a child component in the parent component

First access the children with: this.props.children, each child will then have its ref as a property on it.

Add colorbar to existing axis

This technique is usually used for multiple axis in a figure. In this context it is often required to have a colorbar that corresponds in size with the result from imshow. This can be achieved easily with the axes grid tool kit:

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.axes_grid1 import make_axes_locatable

data = np.arange(100, 0, -1).reshape(10, 10)

fig, ax = plt.subplots()
divider = make_axes_locatable(ax)
cax = divider.append_axes('right', size='5%', pad=0.05)

im = ax.imshow(data, cmap='bone')

fig.colorbar(im, cax=cax, orientation='vertical')

Image with proper colorbar in size

How to make a transparent border using CSS?

Well if you want fully transparent than you can use

border: 5px solid transparent;

If you mean opaque/transparent, than you can use

border: 5px solid rgba(255, 255, 255, .5);

Here, a means alpha, which you can scale, 0-1.

Also some might suggest you to use opacity which does the same job as well, the only difference is it will result in child elements getting opaque too, yes, there are some work arounds but rgba seems better than using opacity.

For older browsers, always declare the background color using #(hex) just as a fall back, so that if old browsers doesn't recognize the rgba, they will apply the hex color to your element.


Demo 2 (With a background image for nested div)

Demo 3 (With an img tag instead of a background-image)

body {
    background: url(;   

div.wrap {
    border: 5px solid #fff; /* Fall back, not used in fiddle */
    border: 5px solid rgba(255, 255, 255, .5);
    height: 400px;
    width: 400px;
    margin: 50px;
    border-radius: 50%;

div.inner {
    background: #fff; /* Fall back, not used in fiddle */
    background: rgba(255, 255, 255, .5);
    height: 380px;
    width: 380px;
    border-radius: 50%; 
    margin: auto; /* Horizontal Center */
    margin-top: 10px; /* Vertical Center ... Yea I know, that's 
                         manually calculated*/

Note (For Demo 3): Image will be scaled according to the height and width provided so make sure it doesn't break the scaling ratio.

Cannot read property 'map' of undefined

The error occur mainly becuase the array isnt found. Just check if you have mapped to the correct array. Check the array name or declaration.

How do I display local image in markdown?

In Jupyter Notebook Markdown, you can use

<img src="RelPathofFolder/File" style="width:800px;height:300px;">

How to display a JSON representation and not [Object Object] on the screen

if you have array of object and you would like to deserialize them in compoent

get example() { => JSON.stringify (i) ) };

then in template

   <li *ngFor="obj of example">{{obj}}</li>

Stop a gif animation onload, on mouseover start the activation

css filter can stop gif from playing in chrome

just add

filter: blur(0.001px);

to your img tag then gif freezed to load via chrome performance concern :)

Select query to remove non-numeric characters

In case if there are some characters possible between digits (e.g. thousands separators), you may try following:

declare @table table (DirtyCol varchar(100))
insert into @table values
    ('AB ABCDE # 123')
    ,('ABCDE# 123')
    ,('AB: ABC# 123')
    ,('AB # 1 000 000')
    ,('AB # 1`234`567')
    ,('AB # (9)(876)(543)')

;with tally as (select top (100) N=row_number() over (order by @@spid) from sys.all_columns),
data as (
    select DirtyCol, Col
    from @table
        cross apply (
            select (select C + ''
            from (select N, substring(DirtyCol, N, 1) C from tally where N<=datalength(DirtyCol)) [1]
            where C between '0' and '9'
            order by N
            for xml path(''))
        ) p (Col)
    where p.Col is not NULL
select DirtyCol, cast(Col as int) IntCol
from data

Output is:

DirtyCol              IntCol
--------------------- -------
AB ABCDE # 123        123
ABCDE# 123            123
AB: ABC# 123          123
AB # 1 000 000        1000000
AB # 1`234`567        1234567
AB # (9)(876)(543)    9876543

For update, add ColToUpdate to select list of the data cte:

;with num as (...),
data as (
    select ColToUpdate, /*DirtyCol, */Col
    from ...
update data
set ColToUpdate = cast(Col as int)

Difference between chr(13) and chr(10)

Chr(10) is the Line Feed character and Chr(13) is the Carriage Return character.

You probably won't notice a difference if you use only one or the other, but you might find yourself in a situation where the output doesn't show properly with only one or the other. So it's safer to include both.

Historically, Line Feed would move down a line but not return to column 1:


Similarly Carriage Return would return to column 1 but not move down a line:


Paste this into a text editor and then choose to "show all characters", and you'll see both characters present at the end of each line. Better safe than sorry.

How to save image in database using C#

//Arrange the Picture Of Path.***

    if (openFileDialog1.ShowDialog() == DialogResult.OK)
                    pictureBox1.Image = Image.FromFile(openFileDialog1.FileName);

                    string[] PicPathArray;
                    string ArrangePathOfPic;

                    PicPathArray = openFileDialog1.FileName.Split('\\');

                    ArrangePathOfPic = PicPathArray[0] + "\\\\" + PicPathArray[1];
                    for (int a = 2; a < PicPathArray.Length; a++)
                        ArrangePathOfPic = ArrangePathOfPic + "\\\\" + PicPathArray[a];

// Save the path Of Pic in database

                    SqlConnection con = new SqlConnection("Data Source=baqar-pc\\baqar;Initial Catalog=Prac;Integrated Security=True");

                    SqlCommand cmd = new SqlCommand("insert into PictureTable (Pic_Path) values (@Pic_Path)", con);
                    cmd.Parameters.Add("@Pic_Path", SqlDbType.VarChar).Value = ArrangePathOfPic;


***// Get the Picture Path in Database.***

SqlConnection con = new SqlConnection("Data Source=baqar-pc\\baqar;Initial Catalog=Prac;Integrated Security=True");

                SqlCommand cmd = new SqlCommand("Select * from Pic_Path where ID = @ID", con);

                SqlDataAdapter adp = new SqlDataAdapter();
                cmd.Parameters.Add("@ID",SqlDbType.VarChar).Value = "1";
                adp.SelectCommand = cmd;

                DataTable DT = new DataTable();


                DataRow DR = DT.Rows[0];
                pictureBox1.Image = Image.FromFile(DR["Pic_Path"].ToString());

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

My templatized inline in-place find-and-replace:

template<class T>
int inline findAndReplace(T& source, const T& find, const T& replace)
    int num=0;
    typename T::size_t fLen = find.size();
    typename T::size_t rLen = replace.size();
    for (T::size_t pos=0; (pos=source.find(find, pos))!=T::npos; pos+=rLen)
        source.replace(pos, fLen, replace);
    return num;

It returns a count of the number of items substituted (for use if you want to successively run this, etc). To use it:

std::string str = "one two three";
int n = findAndReplace(str, "one", "1");

Count the number occurrences of a character in a string

This easy and straight forward function might help:

def check_freq(x):
    freq = {}
    for c in set(x):
       freq[c] = x.count(c)
    return freq

{'a': 7, 'b': 14, 'c': 3, 'd': 3}

If a comprehension is desired:

def check_freq(x):
    return {c: x.count(c) for c in set(x)}

Using LINQ to find item in a List but get "Value cannot be null. Parameter name: source"

I think you can get this error if your database model is not correct and the underlying data contains a null which the model is attempting to map to a non-null object.

For example, some auto-generated models can attempt to map nvarchar(1) columns to char rather than string and hence if this column contains nulls it will throw an error when you attempt to access the data.

Note, LinqPad has a compatibility option if you want it to generate a model like that, but probably doesn't do this by default, which might explain it doesn't give you the error.

Verify if file exists or not in C#

You can determine whether a specified file exists using the Exists method of the File class in the System.IO namespace:

bool System.IO.File.Exists(string path)

You can find the documentation here on MSDN.


using System;
using System.IO;

class Test
    public static void Main()
        string resumeFile = @"c:\ResumesArchive\923823.txt";
        string newFile = @"c:\ResumesImport\newResume.txt";
        if (File.Exists(resumeFile))
            File.Copy(resumeFile, newFile);
            Console.WriteLine("Resume file does not exist.");

Best ways to teach a beginner to program?

I'd recommend Charles Petzold's book Code - The Hidden Langauge of Computer Hardware and Software as an excellent general introduction to how computers work.

There's a lot of information in the book (382 pages) and it may take an absolute beginner some time to read but it's well worth it. Petzold manages to explain many of the core concepts of computers and programming from simple codes, relays, memory, CPUs to operating systems & GUIs in a very clear and enjoyable way. It will provide any reader with a good sense of what's actually happening behind the scenes when they write code.

I certainly wish it was around when I was first learning to program!

Fast ceiling of an integer division in C / C++

I would have rather commented but I don't have a high enough rep.

As far as I am aware, for positive arguments and a divisor which is a power of 2, this is the fastest way (tested in CUDA):

//example y=8
q = (x >> 3) + !!(x & 7);

For generic positive arguments only, I tend to do it like so:

q = x/y + !!(x % y);

How do I convert from a money datatype in SQL server?

You can try like this:

SELECT PARSENAME('$'+ Convert(varchar,Convert(money,@MoneyValue),1),2)

Seaborn plots not showing up

This worked for me

import matplotlib.pyplot as plt
import seaborn as sns

How can I calculate the number of years between two dates?

Sleek foundation javascript function.

 function calculateAge(birthday) { // birthday is a date
   var ageDifMs = - birthday;
   var ageDate = new Date(ageDifMs); // miliseconds from epoch
   return Math.abs(ageDate.getUTCFullYear() - 1970);

c++ and opencv get and set pixel color to Mat

I would not use .at for performance reasons.

Define a struct:

//#pragma pack(push, 2) //not useful (see comments below)
struct RGB {
    uchar blue;
    uchar green;
    uchar red;  };

And then use it like this on your cv::Mat image:

RGB& rgb = image.ptr<RGB>(y)[x];

image.ptr(y) gives you a pointer to the scanline y. And iterate through the pixels with loops of x and y

How to tell which disk Windows Used to Boot

You can use WMI to figure this out. The Win32_BootConfiguration class will tell you both the logical drive and the physical device from which Windows boots. Specifically, the Caption property will tell you which device you're booting from.

For example, in powershell, just type gwmi Win32_BootConfiguration to get your answer.

How best to include other scripts?

Of course, to each their own, but I think the block below is pretty solid. I believe this involves the "best" way to find a directory, and the "best" way to call another bash script:

scriptdir=`dirname "$BASH_SOURCE"`
source $scriptdir/

echo "The main script"

So this may be the "best" way to include other scripts. This is based off another "best" answer that tells a bash script where it is stored

how I can show the sum of in a datagridview column?

Use LINQ if you can.

  label1.Text =  dataGridView1.Rows.Cast<DataGridViewRow>()
                                   .Sum(x => int.Parse(x.Cells[1].Value.ToString()))

How do you cast a List of supertypes to a List of subtypes?

You cannot cast List<TestB> to List<TestA> as Steve Kuo mentions BUT you can dump the contents of List<TestA> into List<TestB>. Try the following:

List<TestA> result = new List<TestA>();
List<TestB> data = new List<TestB>();

I've not tried this code so there are probably mistakes but the idea is that it should iterate through the data object adding the elements (TestB objects) into the List. I hope that works for you.

How to squash commits in git after they have been pushed?

Squash commits locally with

git rebase -i origin/master~4 master

and then force push with

git push origin +master

Difference between --force and +

From the documentation of git push:

Note that --force applies to all the refs that are pushed, hence using it with push.default set to matching or with multiple push destinations configured with remote.*.push may overwrite refs other than the current branch (including local refs that are strictly behind their remote counterpart). To force a push to only one branch, use a + in front of the refspec to push (e.g git push origin +master to force a push to the master branch).

How to initialise memory with new operator in C++?

you can always use memset:

int myArray[10];
memset( myArray, 0, 10 * sizeof( int ));

How To change the column order of An Existing Table in SQL Server 2008

I got the answer for the same , Go on SQL Server ? Tools ? Options ? Designers ? Table and Database Designers and unselect Prevent saving changes that require table re-creation

enter image description here

2- Open table design view and that scroll your column up and down and save your changes.

enter image description here

Subset data to contain only columns whose names match a condition

Using dplyr you can:

df <- df %>% dplyr:: select(grep("ABC", names(df)), grep("XYZ", names(df)))

What is the use of static variable in C#? When to use it? Why can't I declare the static variable inside method?

You don't need to instantiate an object, because yau are going to use a static variable: Console.WriteLine(Book.myInt);

can't start MySql in Mac OS 10.6 Snow Leopard

Maybe this answer helps:

mysql5.58 unstart server in mac os 10.6.5

I just installed MySQL 5.5.8 (mysql-5.5.8-osx10.6-x86_64.dmg) on Mac os X 10.6.5 and also had the problem that MySQL was not starting.

After reading this post:,399397,399606#msg-399606 and editing the file as suggested everything started working.

I also did

sudo chown -R root:wheel /Library/StartupItems/MySQLCOM

after reading since when restarting my Mac OSx 10.6.6 it kept on asking something about not enough privileges. The line above solved that issue.

Now everything is working.

SQL: sum 3 columns when one column has a null value?

If you want to avoid the null value use IsNull(Column, 1)

CSS selector for first element with class

To match your selector, the element must have a class name of red and must be the first child of its parent.

    <span class="red"></span> <!-- MATCH -->

    <p class="red"></p> <!-- NO MATCH -->

    <div><p class="red"></p></div> <!-- MATCH -->

SQL Server Profiler - How to filter trace to only display events from one database?

By experiment I was able to observe this:

When SQL Profiler 2005 or SQL Profiler 2000 is used with database residing in SQLServer 2000 - problem mentioned problem persists, but when SQL Profiler 2005 is used with SQLServer 2005 database, it works perfect!

In Summary, the issue seems to be prevalent in SQLServer 2000 & rectified in SQLServer 2005.

The solution for the issue when dealing with SQLServer 2000 is (as explained by wearejimbo)

  1. Identify the DatabaseID of the database you want to filter by querying the sysdatabases table as below

    SELECT * 
    FROM master..sysdatabases 
    WHERE name like '%your_db_name%'   -- Remove this line to see all databases
    ORDER BY dbid
  2. Use the DatabaseID Filter (instead of DatabaseName) in the New Trace window of SQL Profiler 2000

Is it ok to run docker from inside docker?

Yes, we can run docker in docker, we'll need to attach the unix sockeet "/var/run/docker.sock" on which the docker daemon listens by default as volume to the parent docker using "-v /var/run/docker.sock:/var/run/docker.sock". Sometimes, permissions issues may arise for docker daemon socket for which you can write "sudo chmod 757 /var/run/docker.sock".

And also it would require to run the docker in privileged mode, so the commands would be:

sudo chmod 757 /var/run/docker.sock

docker run --privileged=true -v /var/run/docker.sock:/var/run/docker.sock -it ...

rails 3.1.0 ActionView::Template::Error (application.css isn't precompiled)

Just another way to fix this up on Heroku: Make sure your Rakefile is committed and pushed.

What is an undefined reference/unresolved external symbol error and how do I fix it?

Different architectures

You may see a message like:

library machine type 'x64' conflicts with target machine type 'X86'

In that case, it means that the available symbols are for a different architecture than the one you are compiling for.

On Visual Studio, this is due to the wrong "Platform", and you need to either select the proper one or install the proper version of the library.

On Linux, it may be due to the wrong library folder (using lib instead of lib64 for instance).

On MacOS, there is the option of shipping both architectures in the same file. It may be that the link expects both versions to be there, but only one is. It can also be an issue with the wrong lib/lib64 folder where the library is picked up.

How to remove first and last character of a string?

It's easy, You need to find index of [ and ] then substring. (Here [ is always at start and ] is at end) ,

String loginToken = "[wdsd34svdf]";
System.out.println( loginToken.substring( 1, loginToken.length() - 1 ) );

Determine if Python is running inside virtualenv

(edited) I found that way, what do you think of it ? (it also returns the venv base path and works even for readthedocs where checking the env variable does not):

import os
import sys
from distutils.sysconfig import get_config_vars

def get_venv_basedir():
    """Returns the base directory of the virtualenv, useful to read configuration and plugins"""

    exec_prefix = get_config_vars()['exec_prefix']

    if hasattr(sys, 'real_prefix') is False or exec_prefix.startswith(sys.real_prefix):
        raise EnvironmentError('You must be in a virtual environment')

    return os.path.abspath(get_config_vars()['exec_prefix'] + '/../')

Angular ng-class if else

Both John Conde's and ryeballar's answers are correct and will work.

If you want to get too geeky:

  • John's has the downside that it has to make two decisions per $digest loop (it has to decide whether to add/remove center and it has to decide whether to add/remove left), when clearly only one is needed.

  • Ryeballar's relies on the ternary operator which is probably going to be removed at some point (because the view should not contain any logic). (We can't be sure it will indeed be removed and it probably won't be any time soon, but if there is a more "safe" solution, why not ?)

So, you can do the following as an alternative:


Effect of using sys.path.insert(0, path) and sys.path(append) when loading modules

I'm quite a beginner in Python and I found the answer of Anand was very good but quite complicated to me, so I try to reformulate :

1) insert and append methods are not specific to sys.path and as in other languages they add an item into a list or array and :
* append(item) add item to the end of the list,
* insert(n, item) inserts the item at the nth position in the list (0 at the beginning, 1 after the first element, etc ...).

2) As Anand said, python search the import files in each directory of the path in the order of the path, so :
* If you have no file name collisions, the order of the path has no impact,
* If you look after a function already defined in the path and you use append to add your path, you will not get your function but the predefined one.

But I think that it is better to use append and not insert to not overload the standard behaviour of Python, and use non-ambiguous names for your files and methods.

Foreign key constraints: When to use ON UPDATE and ON DELETE

Do not hesitate to put constraints on the database. You'll be sure to have a consistent database, and that's one of the good reasons to use a database. Especially if you have several applications requesting it (or just one application but with a direct mode and a batch mode using different sources).

With MySQL you do not have advanced constraints like you would have in postgreSQL but at least the foreign key constraints are quite advanced.

We'll take an example, a company table with a user table containing people from theses company

     company_id INT NOT NULL,
     company_name VARCHAR(50),
     PRIMARY KEY (company_id)

     user_id INT, 
     user_name VARCHAR(50), 
     company_id INT,
     INDEX company_id_idx (company_id),
     FOREIGN KEY (company_id) REFERENCES COMPANY (company_id) ON...

Let's look at the ON UPDATE clause:

  • ON UPDATE RESTRICT : the default : if you try to update a company_id in table COMPANY the engine will reject the operation if one USER at least links on this company.
  • ON UPDATE CASCADE : the best one usually : if you update a company_id in a row of table COMPANY the engine will update it accordingly on all USER rows referencing this COMPANY (but no triggers activated on USER table, warning). The engine will track the changes for you, it's good.
  • ON UPDATE SET NULL : if you update a company_id in a row of table COMPANY the engine will set related USERs company_id to NULL (should be available in USER company_id field). I cannot see any interesting thing to do with that on an update, but I may be wrong.

And now on the ON DELETE side:

  • ON DELETE RESTRICT : the default : if you try to delete a company_id Id in table COMPANY the engine will reject the operation if one USER at least links on this company, can save your life.
  • ON DELETE CASCADE : dangerous : if you delete a company row in table COMPANY the engine will delete as well the related USERs. This is dangerous but can be used to make automatic cleanups on secondary tables (so it can be something you want, but quite certainly not for a COMPANY<->USER example)
  • ON DELETE SET NULL : handful : if you delete a COMPANY row the related USERs will automatically have the relationship to NULL. If Null is your value for users with no company this can be a good behavior, for example maybe you need to keep the users in your application, as authors of some content, but removing the company is not a problem for you.

usually my default is: ON DELETE RESTRICT ON UPDATE CASCADE. with some ON DELETE CASCADE for track tables (logs--not all logs--, things like that) and ON DELETE SET NULL when the master table is a 'simple attribute' for the table containing the foreign key, like a JOB table for the USER table.


It's been a long time since I wrote that. Now I think I should add one important warning. MySQL has one big documented limitation with cascades. Cascades are not firing triggers. So if you were over confident enough in that engine to use triggers you should avoid cascades constraints.

MySQL triggers activate only for changes made to tables by SQL statements. They do not activate for changes in views, nor by changes to tables made by APIs that do not transmit SQL statements to the MySQL Server

==> See below the last edit, things are moving on this domain

Triggers are not activated by foreign key actions.

And I do not think this will get fixed one day. Foreign key constraints are managed by the InnoDb storage and Triggers are managed by the MySQL SQL engine. Both are separated. Innodb is the only storage with constraint management, maybe they'll add triggers directly in the storage engine one day, maybe not.

But I have my own opinion on which element you should choose between the poor trigger implementation and the very useful foreign keys constraints support. And once you'll get used to database consistency you'll love PostgreSQL.

12/2017-Updating this Edit about MySQL:

as stated by @IstiaqueAhmed in the comments, the situation has changed on this subject. So follow the link and check the real up-to-date situation (which may change again in the future).

How to manage a redirect request after a jQuery Ajax call

I like Timmerz's method with a slight twist of lemon. If you ever get returned contentType of text/html when you're expecting JSON, you are most likely being redirected. In my case, I just simply reload the page, and it gets redirected to the login page. Oh, and check that the jqXHR status is 200, which seems silly, because you are in the error function, right? Otherwise, legitimate error cases will force an iterative reload (oops)

   error:  function (jqXHR, timeout, message) {
    var contentType = jqXHR.getResponseHeader("Content-Type");
    if (jqXHR.status === 200 && contentType.toLowerCase().indexOf("text/html") >= 0) {
        // assume that our login has expired - reload our current page


int value under 10 convert to string two digit number

The accepted answer is good and fast:




If you need more complexity, String.Format is worth a try:

var str1 = "";
var str2 = "";
for (int i = 1; i < 100; i++)
    str1 = String.Format("{0:00}", i);
    str2 = String.Format("{0:000}", i);

For the i = 10 case:

str1: "10"
str2: "010"

I use this, for example, to clear the text on particular Label Controls on my form by name:

private void EmptyLabelArray()
    var fmt = "Label_Row{0:00}_Col{0:00}";
    for (var rowIndex = 0; rowIndex < 100; rowIndex++)
        for (var colIndex = 0; colIndex < 100; colIndex++)
            var lblName = String.Format(fmt, rowIndex, colIndex);
            foreach (var ctrl in this.Controls)
                var lbl = ctrl as Label;
                if ((lbl != null) && (lbl.Name == lblName))
                    lbl.Text = null;

java : non-static variable cannot be referenced from a static context Error

Java has two kind of Variables

Class Level (Static) :
They are one per Class.Say you have Student Class and defined name as static variable.Now no matter how many student object you create all will have same name.

Object Level :
They belong to per Object.If name is non-static ,then all student can have different name.

Class Level :
This variables are initialized on Class load.So even if no student object is created you can still access and use static name variable.

Object Level: They will get initialized when you create a new object ,say by new();

Your Problem : Your class is Just loaded in JVM and you have called its main (static) method : Legally allowed.

Now from that you want to call an Object varibale : Where is the object ??

You have to create a Object and then only you can access Object level varibales.

Convert digits into words with JavaScript

You might want to try it recursive. It works for numbers between 0 and 999999. Keep in mind that (~~) does the same as Math.floor

var num = "zero one two three four five six seven eight nine ten eleven twelve thirteen fourteen fifteen sixteen seventeen eighteen nineteen".split(" ");_x000D_
var tens = "twenty thirty forty fifty sixty seventy eighty ninety".split(" ");_x000D_
function number2words(n){_x000D_
    if (n < 20) return num[n];_x000D_
    var digit = n%10;_x000D_
    if (n < 100) return tens[~~(n/10)-2] + (digit? "-" + num[digit]: "");_x000D_
    if (n < 1000) return num[~~(n/100)] +" hundred" + (n%100 == 0? "": " " + number2words(n%100));_x000D_
    return number2words(~~(n/1000)) + " thousand" + (n%1000 != 0? " " + number2words(n%1000): "");_x000D_

How can I make my own event in C#?

You can declare an event with the following code:

public event EventHandler MyOwnEvent;

A custom delegate type instead of EventHandler can be used if needed.

You can find detailed information/tutorials on the use of events in .NET in the article Events Tutorial (MSDN).

How to display hidden characters by default (ZERO WIDTH SPACE ie. &#8203)

Not sure what you meant, but you can permanently turn showing whitespaces on and off in Settings -> Editor -> General -> Appearance -> Show whitespaces.

Also, you can set it for a current file only in View -> Active Editor -> Show WhiteSpaces.


Had some free time since it looks like a popular issue, I had written a plugin to inspect the code for such abnormalities. It is called Zero Width Characters locator and you're welcome to give it a try.

How can I keep a container running on Kubernetes?

I did a hack by putting it in background:

[root@localhost ~]# kubectl run hello -it --image ubuntu -- bash &
[2] 128461

Exec on pod hello

[root@localhost ~]# kubectl exec -it hello -- whoami
[root@localhost ~]# kubectl exec -it hello -- hostname

Getting a shell

[root@localhost ~]# kubectl exec -it hello -- bash
root@hello:/# ls
bin  boot  dev  etc  home  lib  lib32  lib64  libx32  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var

jquery background-color change on focus and blur

Tested Code:



$('input:text').focus(function () {
    $(this).css({ 'background': 'Black' });

$('input:text').blur(function () {
    $(this).css({ 'background': 'red' });

Tested in version:


Javascript document.getElementById("id").value returning null instead of empty string when the element is an empty text box

Please check this fiddle and let me know if you get an alert of null value. I have copied your code there and added a couple of alerts. Just like others, I also dont see a null being returned, I get an empty string. Which browser are you using?

How do I check in SQLite whether a table exists?

Use this code:

SELECT name FROM sqlite_master WHERE type='table' AND name='yourTableName';

If the returned array count is equal to 1 it means the table exists. Otherwise it does not exist.

PHP : send mail in localhost

It is configured to use localhost:25 for the mail server.

The error message says that it can't connect to localhost:25.

Therefore you have two options:

  1. Install / Properly configure an SMTP server on localhost port 25
  2. Change the configuration to point to some other SMTP server that you can connect to

How to deselect all selected rows in a DataGridView control?

Thanks Cody heres the c# for ref:

if (e.Button == System.Windows.Forms.MouseButtons.Left)
            DataGridView.HitTestInfo hit = dgv_track.HitTest(e.X, e.Y);
            if (hit.Type == DataGridViewHitTestType.None)
                dgv_track.CurrentCell = null;

How many socket connections can a web server handle?

Note that HTTP doesn't typically keep TCP connections open for any longer than it takes to transmit the page to the client; and it usually takes much more time for the user to read a web page than it takes to download the page... while the user is viewing the page, he adds no load to the server at all.

So the number of people that can be simultaneously viewing your web site is much larger than the number of TCP connections that it can simultaneously serve.

How to query nested objects?

The two query mechanism work in different ways, as suggested in the docs at the section Subdocuments:

When the field holds an embedded document (i.e, subdocument), you can either specify the entire subdocument as the value of a field, or “reach into” the subdocument using dot notation, to specify values for individual fields in the subdocument:

Equality matches within subdocuments select documents if the subdocument matches exactly the specified subdocument, including the field order.

In the following example, the query matches all documents where the value of the field producer is a subdocument that contains only the field company with the value 'ABC123' and the field address with the value '123 Street', in the exact order:

db.inventory.find( {
    producer: {
        company: 'ABC123',
        address: '123 Street'

How to stop C# console applications from closing automatically?

If you do not want the program to close even if a user presses anykey;

 while (true) {
 };//This wont stop app

php string to int

What do you even want the result to be? 888888? If so, just remove the spaces with str_replace, then convert.

Getting activity from context in android

how about some live data callback,

class ProfileView{
    private val _profileViewClicked = MutableLiveData<ProfileView>()
    val profileViewClicked: LiveData<ProfileView> = _profileViewClicked

class ProfileActivity{

  override fun onCreateView(...){

    profileViewClicked.observe(viewLifecycleOwner, Observer { 


Is a Java hashmap search really O(1)?

This basically goes for most hash table implementations in most programming languages, as the algorithm itself doesn't really change.

If there are no collisions present in the table, you only have to do a single look-up, therefore the running time is O(1). If there are collisions present, you have to do more than one look-up, which drives down the performance towards O(n).

How to convert the following json string to java object?

No need to go with GSON for this; Jackson can do either plain Maps/Lists:

ObjectMapper mapper = new ObjectMapper();
Map<String,Object> map = mapper.readValue(json, Map.class);

or more convenient JSON Tree:

JsonNode rootNode = mapper.readTree(json);

By the way, there is no reason why you could not actually create Java classes and do it (IMO) more conveniently:

public class Library {
  public String name;

  public List<Song> songs;
public class Song {
  @JsonProperty("Artist Name") public String artistName;
  @JsonProperty("Song Name") public String songName;

Library lib = mapper.readValue(jsonString, Library.class);

Using both Python 2.x and Python 3.x in IPython Notebook

I looked at this excellent info and then wondered, since

  1. i have python2, python3 and IPython all installed,
  2. i have PyCharm installed,
  3. PyCharm uses IPython for its Python Console,

if PyCharm would use

  1. IPython-py2 when Menu>File>Settings>Project>Project Interpreter == py2 AND
  2. IPython-py3 when Menu>File>Settings>Project>Project Interpreter == py3


P.S. i have Python Launcher for Windows installed as well.

Return JsonResult from web api without its properties

return JsonConvert.SerializeObject(images.ToList(), Formatting.None, new JsonSerializerSettings { PreserveReferencesHandling = PreserveReferencesHandling.None, ReferenceLoopHandling = ReferenceLoopHandling.Ignore });

using Newtonsoft.Json;

brew install mysql on macOS

Okay I had the same issue and solved it. For some reason the mysql_secure_installation script doesn't work out of the box when using Homebrew to install mysql, so I did it manually. On the CLI enter:

mysql -u root

That should get you into mysql. Now do the following (taken from mysql_secure_installation):

UPDATE mysql.user SET Password=PASSWORD('your_new_pass') WHERE User='root';
DELETE FROM mysql.user WHERE User='root' AND Host NOT IN ('localhost', '', '::1');
DELETE FROM mysql.user WHERE User='';
DELETE FROM mysql.db WHERE Db='test' OR Db='test\\_%'

Now exit and get back into mysql with: mysql -u root -p

Write to CSV file and export it?

Here is a CSV action result I wrote that takes a DataTable and converts it into CSV. You can return this from your view and it will prompt the user to download the file. You should be able to convert this easily into a List compatible form or even just put your list into a DataTable.

using System;
using System.Text;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Data;

namespace Detectent.Analyze.ActionResults
    public class CSVResult : ActionResult
        /// <summary>
        /// Converts the columns and rows from a data table into an Microsoft Excel compatible CSV file.
        /// </summary>
        /// <param name="dataTable"></param>
        /// <param name="fileName">The full file name including the extension.</param>
        public CSVResult(DataTable dataTable, string fileName)
            Table = dataTable;
            FileName = fileName;

        public string FileName { get; protected set; }
        public DataTable Table { get; protected set; }

        public override void ExecuteResult(ControllerContext context)
            StringBuilder csv = new StringBuilder(10 * Table.Rows.Count * Table.Columns.Count);

            for (int c = 0; c < Table.Columns.Count; c++)
                if (c > 0)
                DataColumn dc = Table.Columns[c];
                string columnTitleCleaned = CleanCSVString(dc.ColumnName);
            foreach (DataRow dr in Table.Rows)
                StringBuilder csvRow = new StringBuilder();
                for(int c = 0; c < Table.Columns.Count; c++)
                    if(c != 0)

                    object columnValue = dr[c];
                    if (columnValue == null)
                        string columnStringValue = columnValue.ToString();

                        string cleanedColumnValue = CleanCSVString(columnStringValue);

                        if (columnValue.GetType() == typeof(string) && !columnStringValue.Contains(","))
                            cleanedColumnValue = "=" + cleanedColumnValue; // Prevents a number stored in a string from being shown as 8888E+24 in Excel. Example use is the AccountNum field in CI that looks like a number but is really a string.

            HttpResponseBase response = context.HttpContext.Response;
            response.ContentType = "text/csv";
            response.AppendHeader("Content-Disposition", "attachment;filename=" + this.FileName);

        protected string CleanCSVString(string input)
            string output = "\"" + input.Replace("\"", "\"\"").Replace("\r\n", " ").Replace("\r", " ").Replace("\n", "") + "\"";
            return output;

How do you use subprocess.check_output() in Python?

The right answer (using Python 2.7 and later, since check_output() was introduced then) is:

py2output = subprocess.check_output(['python','','-i', 'test.txt'])

To demonstrate, here are my two programs:

import sys
print sys.argv

import subprocess
py2output = subprocess.check_output(['python', '', '-i', 'test.txt'])
print('py2 said:', py2output)

Running it:

$ python3
py2 said: b"['', '-i', 'test.txt']\n"

Here's what's wrong with each of your versions:

py2output = subprocess.check_output([str('python '),'-i', 'test.txt'])

First, str('python') is exactly the same thing as 'python'—you're taking a str, and calling str to convert it to an str. This makes the code harder to read, longer, and even slower, without adding any benefit.

More seriously, python can't be a single argument, unless you're actually trying to run a program named, say, /usr/bin/python\ Which you're not; you're trying to run, say, /usr/bin/python with first argument So, you need to make them separate elements in the list.

Your second version fixes that, but you're missing the ' before test.txt'. This should give you a SyntaxError, probably saying EOL while scanning string literal.

Meanwhile, I'm not sure how you found documentation but couldn't find any examples with arguments. The very first example is:

>>> subprocess.check_output(["echo", "Hello World!"])
b'Hello World!\n'

That calls the "echo" command with an additional argument, "Hello World!".


-i is a positional argument for argparse, test.txt is what the -i is

I'm pretty sure -i is not a positional argument, but an optional argument. Otherwise, the second half of the sentence makes no sense.

Choosing line type and color in Gnuplot 4.0

I've ran into this topic, because i was struggling with dashed lines too (gnuplot 4.6 patchlevel 0)

If you use:

set termoption dashed

Your posted code will work accordingly.

Related question:
However, if I want to export a png with: set terminal png, this isn't working anymore. Anyone got a clue why?

Turns out, out, gnuplots png export library doesnt support this.
Possbile solutions:

  • one can simply export to ps, then convert it with pstopng
  • according to @christoph, if you use pngcairo as your terminal (set terminal pngcairo) it will work

C++ [Error] no matching function for call to

You are trying to call DeckOfCards::shuffle with a deckOfCards parameter:

deckOfCards cardDeck; // create DeckOfCards object
cardDeck.shuffle(cardDeck); // shuffle the cards in the deck

But the method takes a vector<Card>&:

void deckOfCards::shuffle(vector<Card>& deck)

The compiler error messages are quite clear on this. I'll paraphrase the compiler as it talks to you.


[Error] no matching function for call to 'deckOfCards::shuffle(deckOfCards&)'


Hey, pal. You're trying to call a function called shuffle which apparently takes a single parameter of type reference-to-deckOfCards, but there is no such function.


[Note] candidate is:

In file included from main.cpp

[Note] void deckOfCards::shuffle(std::vector&)


I mean, maybe you meant this other function called shuffle, but that one takes a reference-tovector<something>.


[Note] no known conversion for argument 1 from 'deckOfCards' to 'std::vector&'

Which I'd be happy to call if I knew how to convert from a deckOfCards to a vector; but I don't. So I won't.

Check if a variable is a string in JavaScript

I recommend using the built-in functions from jQuery or lodash/Underscore. They're simpler to use and easier to read.

Either function will handle the case DRAX mentioned... that is, they both check if (A) the variable is a string literal or (B) it's an instance of the String object. In either case, these functions correctly identify the value as being a string.

lodash / Underscore.js

   //it's a string
   //it's something else


if($.type(myVar) === "string")
   //it's a string
   //it's something else

See lodash Documentation for _.isString() for more details.

See jQuery Documentation for $.type() for more details.

How to get the latest file in a folder?

Try to sort items by creation time. Example below sorts files in a folder and gets first element which is latest.

import glob
import os

files_path = os.path.join(folder, '*')
files = sorted(
    glob.iglob(files_path), key=os.path.getctime, reverse=True) 
print files[0]


Public Function getLoginresponce(ByVal email As String, ByVal password As String) As String
    Dim requestUrl As String = "your api"
    Dim request As HttpWebRequest = TryCast(WebRequest.Create(requestUrl), HttpWebRequest)
    Dim response As HttpWebResponse = TryCast(request.GetResponse(), HttpWebResponse)
    Dim dataStream As Stream = response.GetResponseStream()
    Dim reader As New StreamReader(dataStream)
    Dim responseFromServer As String = reader.ReadToEnd()
    Dim result = responseFromServer
    Return result
End Function

Div show/hide media query

It sounds like you may be wanting to access the viewport of the device. You can do this by inserting this meta tag in your header.

<meta name="viewport" content="width=device-width, initial-scale=1.0">

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

Assuming that you have and trust (to be authoritative) the list of escape characters Java regex uses (would be nice if these characters were exposed in some Pattern class member) you can use the following method to escape the character if it is indeed necessary:

private static final char[] escapeChars = { '<', '(', '[', '{', '\\', '^', '-', '=', '$', '!', '|', ']', '}', ')', '?', '*', '+', '.', '>' };

private static String regexEscape(char character) {
    for (char escapeChar : escapeChars) {
        if (character == escapeChar) {
            return "\\" + character;
    return String.valueOf(character);

Read the current full URL with React?

As somebody else mentioned, first you need react-router package. But location object that it provides you with contains parsed url.

But if you want full url badly without accessing global variables, I believe the fastest way to do that would be


const getA = memoize(() => document.createElement('a'));
const getCleanA = () => Object.assign(getA(), { href: '' });

const MyComponent = ({ location }) => {
  const { href } = Object.assign(getCleanA(), location);


href is the one containing a full url.

For memoize I usually use lodash, it's implemented that way mostly to avoid creating new element without necessity.

P.S.: Of course is you're not restricted by ancient browsers you might want to try new URL() thing, but basically entire situation is more or less pointless, because you access global variable in one or another way. So why not to use window.location.href instead?

ActionBar text color

It's an old topic but for future readers, using ToolBar makes everything very easy:

Toolbar toolbar = (Toolbar) findViewById(;

How to join (merge) data frames (inner, outer, left, right)

  1. Using merge function we can select the variable of left table or right table, same way like we all familiar with select statement in SQL (EX : Select a.* ...or Select b.* from .....)
  2. We have to add extra code which will subset from the newly joined table .

    • SQL :- select a.* from df1 a inner join df2 b on a.CustomerId=b.CustomerId

    • R :- merge(df1, df2, by.x = "CustomerId", by.y = "CustomerId")[,names(df1)]

Same way

  • SQL :- select b.* from df1 a inner join df2 b on a.CustomerId=b.CustomerId

  • R :- merge(df1, df2, by.x = "CustomerId", by.y = "CustomerId")[,names(df2)]

Selecting multiple columns with linq query and lambda expression

Not sure what you table structure is like but see below.

public NamePriceModel[] AllProducts()
        using (UserDataDataContext db = new UserDataDataContext())
            return db.mrobProducts
                .Where(x => x.Status == 1)
                .Select(x => new NamePriceModel { 
                    Name = x.Name, 
                    Id = x.Id, 
                    Price = x.Price
                .OrderBy(x => x.Id)
         return null;

This would return an array of type anonymous with the members you require.


Create a new class.

public class NamePriceModel 
    public string Name {get; set;}
    public decimal? Price {get; set;}
    public int Id {get; set;}

I've modified the query above to return this as well and you should change your method from returning string[] to returning NamePriceModel[].

How do you reset the stored credentials in 'git credential-osxkeychain'?

Try this in your command line.

git config --local credential.helper ""

It works for me every time when I have multiple GitHub accounts in OSX keychain

Using ExcelDataReader to read Excel data starting from a particular cell

For ExcelDataReader v3.6.0 and above. I struggled a bit to iterate over the Rows. So here's a little more to the above code. Hope it helps for few atleast.

using (var stream = System.IO.File.Open(copyPath, FileMode.Open, FileAccess.Read))

                        IExcelDataReader excelDataReader = ExcelDataReader.ExcelReaderFactory.CreateReader(stream);

                        var conf = new ExcelDataSetConfiguration()
                            ConfigureDataTable = a => new ExcelDataTableConfiguration
                                UseHeaderRow = true

                        DataSet dataSet = excelDataReader.AsDataSet(conf);
                        //DataTable dataTable = dataSet.Tables["Sheet1"];
                        DataRowCollection row = dataSet.Tables["Sheet1"].Rows;
                        //DataColumnCollection col = dataSet.Tables["Sheet1"].Columns;

                        List<object> rowDataList = null;
                        List<object> allRowsList = new List<object>();
                        foreach (DataRow item in row)
                            rowDataList = item.ItemArray.ToList(); //list of each rows
                            allRowsList.Add(rowDataList); //adding the above list of each row to another list


"unexpected token import" in Nodejs5 and babel?

if you use the preset for react-native it accepts the import

npm i babel-preset-react-native --save-dev

and put it inside your .babelrc file

  "presets": ["react-native"]

in your project root directory

Remove/ truncate leading zeros by javascript/jquery

I got this solution for truncating leading zeros(number or any string) in javascript:

<script language="JavaScript" type="text/javascript">
function trimNumber(s) {
  while (s.substr(0,1) == '0' && s.length>1) { s = s.substr(1,9999); }
  return s;

var s1 = '00123';
var s2 = '000assa';
var s3 = 'assa34300';
var s4 = 'ssa';
var s5 = '121212000';

alert(s1 + '=' + trimNumber(s1));
alert(s2 + '=' + trimNumber(s2));
alert(s3 + '=' + trimNumber(s3));
alert(s4 + '=' + trimNumber(s4));
alert(s5 + '=' + trimNumber(s5));
// end hiding contents -->

How to solve java.lang.OutOfMemoryError trouble in Android

You can't increase the heap size dynamically but you can request to use more by using.


in the manifest.xml,you can add in your manifest these lines it is working for some situations.


Whether your application's processes should be created with a large Dalvik heap. This applies to all processes created for the application. It only applies to the first application loaded into a process; if you're using a shared user ID to allow multiple applications to use a process, they all must use this option consistently or they will have unpredictable results. Most apps should not need this and should instead focus on reducing their overall memory usage for improved performance. Enabling this also does not guarantee a fixed increase in available memory, because some devices are constrained by their total available memory.

To query the available memory size at runtime, use the methods getMemoryClass() or getLargeMemoryClass().

If still facing problem then this should also work

 BitmapFactory.Options options = new BitmapFactory.Options();
 options.inSampleSize = 8;
 mBitmapInsurance = BitmapFactory.decodeFile(mCurrentPhotoPath,options);

If set to a value > 1, requests the decoder to subsample the original image, returning a smaller image to save memory.

This is the optimal use of BitmapFactory.Options.inSampleSize with regards to speed of displaying the image. The documentation mentions using values that are a power of 2, so I am working with 2, 4, 8, 16 etc.

Lets get more deeper to Image Sampling:

For example, it’s not worth loading a 1024x768 pixel image into memory if it will eventually be displayed in a 128x128 pixel thumbnail in an ImageView.

To tell the decoder to subsample the image, loading a smaller version into memory, set inSampleSize to true in your BitmapFactory.Options object. For example, an image with resolution 2100 x 1500 pixels that is decoded with an inSampleSize of 4 produces a bitmap of approximately 512x384. Loading this into memory uses 0.75MB rather than 12MB for the full image (assuming a bitmap configuration of ARGB_8888). Here’s a method to calculate a sample size value that is a power of two based on a target width and height:

public static int calculateInSampleSize(
        BitmapFactory.Options options, int reqWidth, int reqHeight) {
    // Raw height and width of image
    final int height = options.outHeight;
    final int width = options.outWidth;
    int inSampleSize = 1;

    if (height > reqHeight || width > reqWidth) {

        final int halfHeight = height / 2;
        final int halfWidth = width / 2;

        // Calculate the largest inSampleSize value that is a power of 2 and keeps both
        // height and width larger than the requested height and width.
        while ((halfHeight / inSampleSize) > reqHeight
                && (halfWidth / inSampleSize) > reqWidth) {
            inSampleSize *= 2;

    return inSampleSize;

Note: A power of two value is calculated because the decoder uses a final value by rounding down to the nearest power of two, as per the inSampleSize documentation.

To use this method, first decode with inJustDecodeBounds set to true, pass the options through and then decode again using the new inSampleSize value and inJustDecodeBounds set to false:

public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId,
    int reqWidth, int reqHeight) {

    // First decode with inJustDecodeBounds=true to check dimensions
    final BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeResource(res, resId, options);

    // Calculate inSampleSize
    options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

    // Decode bitmap with inSampleSize set
    options.inJustDecodeBounds = false;
    return BitmapFactory.decodeResource(res, resId, options);

This method makes it easy to load a bitmap of arbitrarily large size into an ImageView that displays a 100x100 pixel thumbnail, as shown in the following example code:

mImageView.setImageBitmap(decodeSampledBitmapFromResource(getResources(),, 100, 100));

You can follow a similar process to decode bitmaps from other sources, by substituting the appropriate BitmapFactory.decode* method as needed.

I found this code also interesting:

private Bitmap getBitmap(String path) {

Uri uri = getImageUri(path);
InputStream in = null;
try {
    final int IMAGE_MAX_SIZE = 1200000; // 1.2MP
    in = mContentResolver.openInputStream(uri);

    // Decode image size
    BitmapFactory.Options o = new BitmapFactory.Options();
    o.inJustDecodeBounds = true;
    BitmapFactory.decodeStream(in, null, o);

    int scale = 1;
    while ((o.outWidth * o.outHeight) * (1 / Math.pow(scale, 2)) > 
          IMAGE_MAX_SIZE) {
    Log.d(TAG, "scale = " + scale + ", orig-width: " + o.outWidth + ", 
       orig-height: " + o.outHeight);

    Bitmap bitmap = null;
    in = mContentResolver.openInputStream(uri);
    if (scale > 1) {
        // scale to max possible inSampleSize that still yields an image
        // larger than target
        o = new BitmapFactory.Options();
        o.inSampleSize = scale;
        bitmap = BitmapFactory.decodeStream(in, null, o);

        // resize to desired dimensions
        int height = bitmap.getHeight();
        int width = bitmap.getWidth();
        Log.d(TAG, "1th scale operation dimenions - width: " + width + ",
           height: " + height);

        double y = Math.sqrt(IMAGE_MAX_SIZE
                / (((double) width) / height));
        double x = (y / height) * width;

        Bitmap scaledBitmap = Bitmap.createScaledBitmap(bitmap, (int) x, 
           (int) y, true);
        bitmap = scaledBitmap;

    } else {
        bitmap = BitmapFactory.decodeStream(in);

    Log.d(TAG, "bitmap size - width: " +bitmap.getWidth() + ", height: " + 
    return bitmap;
} catch (IOException e) {
    Log.e(TAG, e.getMessage(),e);
    return null;

How to Manage Your App's Memory: link

It's not a good idea to use android:largeHeap="true" here's the extract from google that explains it,

However, the ability to request a large heap is intended only for a small set of apps that can justify the need to consume more RAM (such as a large photo editing app). Never request a large heap simply because you've run out of memory and you need a quick fix—you should use it only when you know exactly where all your memory is being allocated and why it must be retained. Yet, even when you're confident your app can justify the large heap, you should avoid requesting it to whatever extent possible. Using the extra memory will increasingly be to the detriment of the overall user experience because garbage collection will take longer and system performance may be slower when task switching or performing other common operations.

After working excrutiatingly with out of memory errors i would say adding this to the manifest to avoid the oom issue is not a sin

Verifying App Behavior on the Android Runtime (ART)

The Android runtime (ART) is the default runtime for devices running Android 5.0 (API level 21) and higher. This runtime offers a number of features that improve performance and smoothness of the Android platform and apps. You can find more information about ART's new features in Introducing ART.

However, some techniques that work on Dalvik do not work on ART. This document lets you know about things to watch for when migrating an existing app to be compatible with ART. Most apps should just work when running with ART.

Addressing Garbage Collection (GC) Issues

Under Dalvik, apps frequently find it useful to explicitly call System.gc() to prompt garbage collection (GC). This should be far less necessary with ART, particularly if you're invoking garbage collection to prevent GC_FOR_ALLOC-type occurrences or to reduce fragmentation. You can verify which runtime is in use by calling System.getProperty("java.vm.version"). If ART is in use, the property's value is "2.0.0" or higher.

Furthermore, a compacting garbage collector is under development in the Android Open-Source Project (AOSP) to improve memory management. Because of this, you should avoid using techniques that are incompatible with compacting GC (such as saving pointers to object instance data). This is particularly important for apps that make use of the Java Native Interface (JNI). For more information, see Preventing JNI Issues.

Preventing JNI Issues

ART's JNI is somewhat stricter than Dalvik's. It is an especially good idea to use CheckJNI mode to catch common problems. If your app makes use of C/C++ code, you should review the following article:

Also, you can use native memory (NDK & JNI), so you actually bypass the heap size limitation.

Here are some posts made about it:

and here's a library made for it:

Cannot push to Git repository on Bitbucket

I solved this by removing the remote using command:

git remote remove origin

and then tried to add remote using https url instead of ssh

git remote add origin httpsUrl

It asks for github credentials. Enter credentials and then try pushing to git using:

git push origin master

Visual Studio C# IntelliSense not automatically displaying

Sometimes i've found Intellisense to be slow. Hit the . and wait for a minute and see if it appears after a delay. If so, then I believe there may be a cache that can be deleted to get it to rescan.

Java and unlimited decimal places?

I believe that you are looking for the java.lang.BigDecimal class.

Combine hover and click functions (jQuery)?

i think best approach is to make a common method and call in hover and click events.

Application Installation Failed in Android Studio

In my case, it was very a silly and funny mistake. I, accidentally without actually knowing, checked "Android Debug Bridge, Use libUsb backend". Actually it should stay unchecked..

In Mac Pro, Go Preferences - > Build, Execution,Deployment -> Debugger.enter image description here

NumPy array is not JSON serializable

use NumpyEncoder it will process json dump successfully.without throwing - NumPy array is not JSON serializable

import numpy as np
import json
from numpyencoder import NumpyEncoder
arr = array([   0,  239,  479,  717,  952, 1192, 1432, 1667], dtype=int64) 

Convert INT to FLOAT in SQL

In oracle db there is a trick for casting int to float (I suppose, it should also work in mysql):

select myintfield + 0.0 as myfloatfield from mytable

While @Heximal's answer works, I don't personally recommend it.

This is because it uses implicit casting. Although you didn't type CAST, either the SUM() or the 0.0 need to be cast to be the same data-types, before the + can happen. In this case the order of precedence is in your favour, and you get a float on both sides, and a float as a result of the +. But SUM(aFloatField) + 0 does not yield an INT, because the 0 is being implicitly cast to a FLOAT.

I find that in most programming cases, it is much preferable to be explicit. Don't leave things to chance, confusion, or interpretation.

If you want to be explicit, I would use the following.

CAST(SUM( AS FLOAT) * cp.price
-- using MySQL CAST FLOAT  requires 8.0

I won't discuss whether NUMERIC or FLOAT *(fixed point, instead of floating point)* is more appropriate, when it comes to rounding errors, etc. I'll just let you google that if you need to, but FLOAT is so massively misused that there is a lot to read about the subject already out there.

You can try the following to see what happens...

CAST(SUM( AS NUMERIC(10,4)) * CAST(cp.price AS NUMERIC(10,4))