Programs & Examples On #String algorithm

How to add an auto-incrementing primary key to an existing table, in PostgreSQL?

I landed here because I was looking for something like that too. In my case, I was copying the data from a set of staging tables with many columns into one table while also assigning row ids to the target table. Here is a variant of the above approaches that I used. I added the serial column at the end of my target table. That way I don't have to have a placeholder for it in the Insert statement. Then a simple select * into the target table auto populated this column. Here are the two SQL statements that I used on PostgreSQL 9.6.4.

INSERT INTO target SELECT * from source;

Negative matching using grep (match lines that do not contain foo)

In your case, you presumably don't want to use grep, but add instead a negative clause to the find command, e.g.

find /home/baumerf/public_html/ -mmin -60 -not -name error_log

If you want to include wildcards in the name, you'll have to escape them, e.g. to exclude files with suffix .log:

find /home/baumerf/public_html/ -mmin -60 -not -name \*.log

Generating combinations in c++

A simple way using std::next_permutation:

#include <iostream>
#include <algorithm>
#include <vector>

int main() {
    int n, r;
    std::cin >> n;
    std::cin >> r;

    std::vector<bool> v(n);
    std::fill(v.end() - r, v.end(), true);

    do {
        for (int i = 0; i < n; ++i) {
            if (v[i]) {
                std::cout << (i + 1) << " ";
        std::cout << "\n";
    } while (std::next_permutation(v.begin(), v.end()));
    return 0;

or a slight variation that outputs the results in an easier to follow order:

#include <iostream>
#include <algorithm>
#include <vector>

int main() {
   int n, r;
   std::cin >> n;
   std::cin >> r;

   std::vector<bool> v(n);
   std::fill(v.begin(), v.begin() + r, true);

   do {
       for (int i = 0; i < n; ++i) {
           if (v[i]) {
               std::cout << (i + 1) << " ";
       std::cout << "\n";
   } while (std::prev_permutation(v.begin(), v.end()));
   return 0;

A bit of explanation:

It works by creating a "selection array" (v), where we place r selectors, then we create all permutations of these selectors, and print the corresponding set member if it is selected in in the current permutation of v.

You can implement it if you note that for each level r you select a number from 1 to n.

In C++, we need to 'manually' keep the state between calls that produces results (a combination): so, we build a class that on construction initialize the state, and has a member that on each call returns the combination while there are solutions: for instance

#include <iostream>
#include <iterator>
#include <vector>
#include <cstdlib>

using namespace std;

struct combinations
    typedef vector<int> combination_t;

    // initialize status
   combinations(int N, int R) :
       completed(N < 1 || R > N),
       N(N), R(R)
       for (int c = 1; c <= R; ++c)

   // true while there are more solutions
   bool completed;

   // count how many generated
   int generated;

   // get current and compute next combination
   combination_t next()
       combination_t ret = curr;

       // find what to increment
       completed = true;
       for (int i = R - 1; i >= 0; --i)
           if (curr[i] < N - R + i + 1)
               int j = curr[i] + 1;
               while (i <= R-1)
                   curr[i++] = j++;
               completed = false;

       return ret;


   int N, R;
   combination_t curr;

int main(int argc, char **argv)
    int N = argc >= 2 ? atoi(argv[1]) : 5;
    int R = argc >= 3 ? atoi(argv[2]) : 2;
    combinations cs(N, R);
    while (!cs.completed)
        combinations::combination_t c =;
        copy(c.begin(), c.end(), ostream_iterator<int>(cout, ","));
        cout << endl;
    return cs.generated;

test output:


Using COALESCE to handle NULL values in PostgreSQL

If you're using 0 and an empty string '' and null to designate undefined you've got a data problem. Just update the columns and fix your schema.

UPDATE pt.incentive_channel
SET   pt.incentive_marketing = NULL
WHERE pt.incentive_marketing = '';

UPDATE pt.incentive_channel
SET   pt.incentive_advertising = NULL
WHERE pt.incentive_marketing = '';

UPDATE pt.incentive_channel
SET   pt.incentive_channel = NULL
WHERE pt.incentive_marketing = '';

This will make joining and selecting substantially easier moving forward.

How can I escape a double quote inside double quotes?

Add "\" before double quote to escape it, instead of \

#! /bin/csh -f

set dbtable = balabala

set dbload = "load data local infile "\""'gfpoint.csv'"\"" into table $dbtable FIELDS TERMINATED BY ',' ENCLOSED BY '"\""' LINES TERMINATED BY "\""'\n'"\"" IGNORE 1 LINES"

echo $dbload
# load data local infile "'gfpoint.csv'" into table balabala FIELDS TERMINATED BY ',' ENCLOSED BY '"' LINES TERMINATED BY "''" IGNORE 1 LINES

XAMPP Apache won't start

I gave all users full access on the xampp folder, inclusive subdirectories. Afterwards it worked.

In Objective-C, how do I test the object type?

Running a simple test, I thought I'd document what works and what doesn't. Often I see people checking to see if the object's class is a member of the other class or is equal to the other class.

For the line below, we have some poorly formed data that can be an NSArray, an NSDictionary or (null).

NSArray *hits = [[[myXML objectForKey: @"Answer"] objectForKey: @"hits"] objectForKey: @"Hit"];

These are the tests that were performed:

NSLog(@"%@", [hits class]);

if ([hits isMemberOfClass:[NSMutableArray class]]) {
    NSLog(@"%@", [hits class]);

if ([hits isMemberOfClass:[NSMutableDictionary class]]) {
    NSLog(@"%@", [hits class]);

if ([hits isMemberOfClass:[NSArray class]]) {
    NSLog(@"%@", [hits class]);

if ([hits isMemberOfClass:[NSDictionary class]]) {
    NSLog(@"%@", [hits class]);

if ([hits isKindOfClass:[NSMutableDictionary class]]) {
    NSLog(@"%@", [hits class]);

if ([hits isKindOfClass:[NSDictionary class]]) {
    NSLog(@"%@", [hits class]);

if ([hits isKindOfClass:[NSArray class]]) {
    NSLog(@"%@", [hits class]);

if ([hits isKindOfClass:[NSMutableArray class]]) {
    NSLog(@"%@", [hits class]);

isKindOfClass worked rather well while isMemberOfClass didn't.

How do I enumerate the properties of a JavaScript object?

Simple enough:

for(var propertyName in myObject) {
   // propertyName is what you want
   // you can get the value like this: myObject[propertyName]

Now, you will not get private variables this way because they are not available.

EDIT: @bitwiseplatypus is correct that unless you use the hasOwnProperty() method, you will get properties that are inherited - however, I don't know why anyone familiar with object-oriented programming would expect anything less! Typically, someone that brings this up has been subjected to Douglas Crockford's warnings about this, which still confuse me a bit. Again, inheritance is a normal part of OO languages and is therefore part of JavaScript, notwithstanding it being prototypical.

Now, that said, hasOwnProperty() is useful for filtering, but we don't need to sound a warning as if there is something dangerous in getting inherited properties.

EDIT 2: @bitwiseplatypus brings up the situation that would occur should someone add properties/methods to your objects at a point in time later than when you originally wrote your objects (via its prototype) - while it is true that this might cause unexpected behavior, I personally don't see that as my problem entirely. Just a matter of opinion. Besides, what if I design things in such a way that I use prototypes during the construction of my objects and yet have code that iterates over the properties of the object and I want all inherited properties? I wouldn't use hasOwnProperty(). Then, let's say, someone adds new properties later. Is that my fault if things behave badly at that point? I don't think so. I think this is why jQuery, as an example, has specified ways of extending how it works (via jQuery.extend and jQuery.fn.extend).

nuget 'packages' element is not declared warning

You will see it only when the file is open. When you'll close the file in Visual Studio the warnings goes away

Search for a string in all tables, rows and columns of a DB

This procedure is for finding any string or date in all tables
if search string is date, its format should be yyyy-MM-dd
eg. 2011-07-05

-- ================================================
-- Exec SearchInTables 'f6f56934-a5d4-4967-80a1-1a2223b9c7b1'

-- ================================================
-- =============================================
-- Author:      <Joshy,,Name>
-- Create date: <Create Date,,>
-- Description: <Description,,>
-- =============================================
@myValue nvarchar(1000)
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.

    -- Insert statements for procedure here
        DECLARE @searchsql nvarchar(max)
        DECLARE @table_name nvarchar(1000)
        DECLARE @Schema_name nvarchar(1000)
        DECLARE @ParmDefinition nvarchar(500)
        DECLARE @XMLIn nvarchar(max)
        SET @ParmDefinition = N'@XMLOut varchar(max) OUTPUT'

        FROM sys.tables A 
            INNER JOIN sys.schemas B ON A.schema_id=B.schema_id
        WHERE like 'tbl_Tax_Sections' 

        DECLARE tables_cur CURSOR FOR 
                            SELECT, FOM sys.tables A 
                            INNER JOIN sys.schemas B ON A.schema_id=B.schema_id
                            WHERE A.type = 'U'  
        OPEN tables_cur  
        FETCH NEXT FROM tables_cur INTO @table_name , @Schema_name 
            WHILE (@@FETCH_STATUS = 0) 
                SET @searchsql ='SELECT @XMLOut=(SELECT PATINDEX(''%'+ @myValue+ '%'''
                SET @searchsql =@searchsql  + ', (SELECT * FROM '+@Schema_name+'.'+@table_name+' FOR XML AUTO) ))'
                --print @searchsql 
                EXEC sp_executesql @searchsql, @ParmDefinition, @XMLOut=@XMLIn OUTPUT
                --print @XMLIn 

                IF @XMLIn <> 0 PRINT @Schema_name+'.'+@table_name

                FETCH NEXT FROM tables_cur INTO @table_name , @Schema_name 

        CLOSE tables_cur 
        DEALLOCATE tables_cur 

Class Not Found Exception when running JUnit test

In my case I had a wrong maven directory structure.

Which should be like:

/src/test/java/ com.myproject.server.MyTest

After I fixed that - everything worked like a charm.

What is the difference between Set and List?

Few note worthy differences between List and Set in Java are given as following :

1) Fundamental difference between List and Set in Java is allowing duplicate elements. List in Java allows duplicates while Set doesn't allow any duplicate. If you insert duplicate in Set it will replace the older value. Any implementation of Set in Java will only contains unique elements.

2) Another significant difference between List and Set in Java is order. List is an Ordered Collection while Set is an unordered Collection. List maintains insertion order of elements, means any element which is inserted before will go on lower index than any element which is inserted after. Set in Java doesn't maintain any order. Though Set provide another alternative called SortedSet which can store Set elements in specific Sorting order defined by Comparable and Comparator methods of Objects stored in Set.

3) Popular implementation of List interface in Java includes ArrayList, Vector and LinkedList. While popular implementation of Set interface includes HashSet, TreeSet and LinkedHashSet.

Its pretty clear that if you need to maintain insertion order or object and you collection can contain duplicates than List is a way to go. On the other hand if your requirement is to maintain unique collection without any duplicates than Set is the way to go.

Setting java locale settings

With the user.language, and user.variant properties.


java -Duser.language=th -Duser.variant=TH SomeClass

How do I use the CONCAT function in SQL Server 2008 R2?

CONCAT is new to SQL Server 2012. The link you gave makes this clear, it is not a function on Previous Versions, including 2008 R2.

That it is part of SQL Server 2012 can be seen in the document tree:

SQL Server 2012  
Product Documentation  
Books Online for SQL Server 2012  
Database Engine  
  Transact-SQL Reference (Database Engine)  
    Built-in Functions (Transact-SQL)  
      String Functions (Transact-SQL)  

EDIT Martin Smith helpfully points out that SQL Server provides an implementation of ODBC's CONCAT function.

How to Delete Session Cookie?

Deleting a jQuery cookie:

$(function() {
    var COOKIE_NAME = 'test_cookie';
    var options = { path: '/', expires: 10 };
    $.cookie(COOKIE_NAME, 'test', options); // sets the cookie
    console.log( $.cookie( COOKIE_NAME)); // check the value // returns test
    $.cookie(COOKIE_NAME, null, options);   // deletes the cookie
    console.log( $.cookie( COOKIE_NAME)); // check the value // returns null

How do I run a program with a different working directory from current, from Linux shell?

Call the program like this:

(cd /c; /a/helloworld)

The parentheses cause a sub-shell to be spawned. This sub-shell then changes its working directory to /c, then executes helloworld from /a. After the program exits, the sub-shell terminates, returning you to your prompt of the parent shell, in the directory you started from.

Error handling: To avoid running the program without having changed the directory, e.g. when having misspelled /c, make the execution of helloworld conditional:

(cd /c && /a/helloworld)

Reducing memory usage: To avoid having the subshell waste memory while hello world executes, call helloworld via exec:

(cd /c && exec /a/helloworld)

[Thanks to Josh and Juliano for giving tips on improving this answer!]

C# Return Different Types?

Rick's solution is the 'best' way to go in most cases. Sometimes when that's not available you want to use object as base type. And you could use the method like this:

public object GetAnything()
     Hello hello = new Hello();
     Computer computer = new Computer();
     Radio radio = new Radio();

     return hello; // or computer or radio   

To use it, you will want to use the as operator, like this:

public void TestMethod()
    object anything = GetAnything();
    var hello = anything as Hello;
    var computer = anything as Computer;
    var radio = anything as Radio;

    if (hello != null)
        // GetAnything() returned a hello
    else if (computer != null)
        // GetAnything() returned a computer
    else if (radio != null)
        // GetAnything() returned a radio
        // GetAnything() returned... well anything :D

In your case you want to call a method play. So this'd seem more appropriate:

interface IPlayable
    void Play();

class Radio : IPlayable
    public void Play() { /* Play radio */ }

class Hello : IPlayable
    public void Play() { /* Say hello */ }

class Computer : IPlayable
    public void Play() { /* beep beep */ }

public IPlayable GetAnything()
     Hello hello = new Hello();
     Computer computer = new Computer();
     Radio radio = new Radio();

     return hello; // or computer or radio   

MongoNetworkError: failed to connect to server [localhost:27017] on first connect [MongoNetworkError: connect ECONNREFUSED]

just run mongod in terminal on the base folder if everything has been set up like installing mongo db and the client for it like mongoose. After running the command run the project file that you are working on and then the error shouldn't appear.

JPA : How to convert a native query result set to POJO class collection

if you are using Spring, you can use org.springframework.jdbc.core.RowMapper

Here is an example:

public List query(String objectType, String namedQuery)
  String rowMapper = objectType + "RowMapper";
  // then by reflection you can instantiate and use. The RowMapper classes need to follow the naming specific convention to follow such implementation.


More of a comment link for suggested further reading...A really good blog article which benchmarks various ways of accomplishing this task can be found here.

They use a few techniques: "Insert Where Not Exists", "Merge" statement, "Insert Except", and your typical "left join" to see which way is the fastest to accomplish this task.

The example code used for each technique is as follows (straight copy/paste from their page) :

INSERT INTO #table1 (Id, guidd, TimeAdded, ExtraData)
SELECT Id, guidd, TimeAdded, ExtraData
FROM #table2
WHERE NOT EXISTS (Select Id, guidd From #table1 WHERE =
MERGE #table1 as [Target]
USING  (select Id, guidd, TimeAdded, ExtraData from #table2) as [Source]
(id, guidd, TimeAdded, ExtraData)
    on [Target].id =[Source].id
    INSERT (id, guidd, TimeAdded, ExtraData)
    VALUES ([Source].id, [Source].guidd, [Source].TimeAdded, [Source].ExtraData);
INSERT INTO #table1 (id, guidd, TimeAdded, ExtraData)
SELECT id, guidd, TimeAdded, ExtraData from #table2
SELECT id, guidd, TimeAdded, ExtraData from #table1
INSERT INTO #table1 (id, guidd, TimeAdded, ExtraData)
SELECT, #table2.guidd, #table2.TimeAdded, #table2.ExtraData
FROM #table2
LEFT JOIN #table1 on =
WHERE is null

It's a good read for those who are looking for speed! On SQL 2014, the Insert-Except method turned out to be the fastest for 50 million or more records.

Prevent Bootstrap Modal from disappearing when clicking outside or pressing escape?

<button class='btn btn-danger fa fa-trash' data-toggle='modal' data-target='#deleteModal' data-backdrop='static' data-keyboard='false'></button>

simply add data-backdrop and data-keyboard attribute to your button on which model is open.

Count number of records returned by group by

you can also get by the below query

select column_group_by,count(*) as Coulm_name_to_be_displayed from Table group by Column;

-- For example:
select city,count(*) AS Count from people group by city

Split string on the first white space occurrence

Late to the game, I know but there seems to be a very simple way to do this:

const str = "72 tocirah sneab";_x000D_
const arr = str.split(/ (.*)/);_x000D_

This will leave arr[0] with "72" and arr[1] with "tocirah sneab". Note that arr[2] will be empty, but you can just ignore it.

For reference:

How do I sort arrays using vbscript?

VBScript does not have a method for sorting arrays so you've got two options:

  • Writing a sorting function like mergesort, from ground up.
  • Use the JScript tip from this article

The remote end hung up unexpectedly while git cloning

###Quick solution:

With this kind of error, I usually start by raising the postBuffer size by:

git config --global http.postBuffer 524288000

(some comments below report having to double the value):

git config --global http.postBuffer 1048576000

(For npm publish, Martin Braun reports in the comments setting it to no more than 50 000 000 instead of the default 1 000 000)

###More information:

From the git config man page, http.postBuffer is about:

Maximum size in bytes of the buffer used by smart HTTP transports when POSTing data to the remote system.
For requests larger than this buffer size, HTTP/1.1 and Transfer-Encoding: chunked is used to avoid creating a massive pack file locally. Default is 1 MiB, which is sufficient for most requests.

Even for the clone, that can have an effect, and in this instance, the OP Joe reports:

[clone] works fine now

Note: if something went wrong on the server side, and if the server uses Git 2.5+ (Q2 2015), the error message might be more explicit.
See "Git cloning: remote end hung up unexpectedly, tried changing postBuffer but still failing".

Kulai (in the comments) points out to this Atlassian Troubleshooting Git page, which adds:

Error code 56 indicates a curl receive the error of CURLE_RECV_ERROR which means there was some issue that prevented the data from being received during the cloning process.
Typically this is caused by a network setting, firewall, VPN client, or anti-virus that is terminating the connection before all data has been transferred.

It also mentions the following environment variable, order to help with the debugging process.

# Linux
export GIT_TRACE=1


With Git 2.25.1 (Feb. 2020), you know more about this http.postBuffer "solution".

See commit 7a2dc95, commit 1b13e90 (22 Jan 2020) by brian m. carlson (bk2204).
(Merged by Junio C Hamano -- gitster -- in commit 53a8329, 30 Jan 2020)
(Git Mailing list discussion)

docs: mention when increasing http.postBuffer is valuable

Signed-off-by: brian m. carlson

Users in a wide variety of situations find themselves with HTTP push problems.

Oftentimes these issues are due to antivirus software, filtering proxies, or other man-in-the-middle situations; other times, they are due to simple unreliability of the network.

However, a common solution to HTTP push problems found online is to increase http.postBuffer.

This works for none of the aforementioned situations and is only useful in a small, highly restricted number of cases: essentially, when the connection does not properly support HTTP/1.1.

Document when raising this value is appropriate and what it actually does, and discourage people from using it as a general solution for push problems, since it is not effective there.

So the documentation for git config http.postBuffer now includes:


Maximum size in bytes of the buffer used by smart HTTP transports when POSTing data to the remote system.
For requests larger than this buffer size, HTTP/1.1 and Transfer-Encoding: chunked is used to avoid creating a massive pack file locally.
Default is 1 MiB, which issufficient for most requests.

Note that raising this limit is only effective for disabling chunked transfer encoding and therefore should be used only where the remote server or a proxy only supports HTTP/1.0 or is noncompliant with the HTTP standard.
Raising this is not, in general, an effective solution for most push problems, but can increase memory consumption significantly since the entire buffer is allocated even for small pushes.

fatal: early EOF fatal: index-pack failed

I was getting the same error, on my side i resolved by running this command, In windows it has some memory issue.

git config --global pack.windowsMemory 256m

Display Adobe pdf inside a div

Yes you can.

See the code from the following thread from 2007: PDF within a DIV

    <object data="test.pdf" type="application/pdf" width="300" height="200">
        alt : <a href="test.pdf">test.pdf</a>

It uses <object>, which can be styled with CSS, and so you can float them, give them borders, etc.

(In the end, I edited my pdf files to remove large borders and converted them to jpg images.)

How to identify if a webpage is being loaded inside an iframe or directly into the browser window?

I actually used to check window.parent and it worked for me, but lately window is a cyclic object and always has a parent key, iframe or no iframe.

As the comments suggest hard comparing with window.parent works. Not sure if this will work if iframe is exactly the same webpage as parent.

window === window.parent;

Install Chrome extension form outside the Chrome Web Store

For regular Windows users who are not skilled with computers, it is practically not possible to install and use extensions from outside the Chrome Web Store.

Users of other operating systems (Linux, Mac, Chrome OS) can easily install unpacked extensions (in developer mode).
Windows users can also load an unpacked extension, but they will always see an information bubble with "Disable developer mode extensions" when they start Chrome or open a new incognito window, which is really annoying. The only way for Windows users to use unpacked extensions without such dialogs is to switch to Chrome on the developer channel, by installing

Extensions can be loaded in unpacked mode by following the following steps:

  1. Visit chrome://extensions (via omnibox or menu -> Tools -> Extensions).
  2. Enable Developer mode by ticking the checkbox in the upper-right corner.
  3. Click on the "Load unpacked extension..." button.
  4. Select the directory containing your unpacked extension.

If you have a crx file, then it needs to be extracted first. CRX files are zip files with a different header. Any capable zip program should be able to open it. If you don't have such a program, I recommend 7-zip.

These steps will work for almost every extension, except extensions that rely on their extension ID. If you use the previous method, you will get an extension with a random extension ID. If it is important to preserve the extension ID, then you need to know the public key of your CRX file and insert this in your manifest.json. I have previously given a detailed explanation on how to get and use this key at

PostgreSQL unnest() with element number

unnest2() as exercise

Older versions before pg v8.4 need a user-defined unnest(). We can adapt this old function to return elements with an index:

CREATE FUNCTION unnest2(anyarray)
  RETURNS setof record  AS
  SELECT $1[i], i
  FROM   generate_series(array_lower($1,1),
                         array_upper($1,1)) i;

How do I set the driver's python version in spark?

If you're running Spark in a larger organization and are unable to update the / file, exporting the environment variables may not work.

You can add the specific Spark settings through the --conf option when submitting the job at run time.

pyspark --master yarn --[other settings]\ 
  --conf "spark.pyspark.python=/your/python/loc/bin/python"\ 
  --conf "spark.pyspark.driver.python=/your/python/loc/bin/python"

How to test if a list contains another list?

I tried to make this as efficient as possible.

It uses a generator; those unfamiliar with these beasts are advised to check out their documentation and that of yield expressions.

Basically it creates a generator of values from the subsequence that can be reset by sending it a true value. If the generator is reset, it starts yielding again from the beginning of sub.

Then it just compares successive values of sequence with the generator yields, resetting the generator if they don't match.

When the generator runs out of values, i.e. reaches the end of sub without being reset, that means that we've found our match.

Since it works for any sequence, you can even use it on strings, in which case it behaves similarly to str.find, except that it returns False instead of -1.

As a further note: I think that the second value of the returned tuple should, in keeping with Python standards, normally be one higher. i.e. "string"[0:2] == "st". But the spec says otherwise, so that's how this works.

It depends on if this is meant to be a general-purpose routine or if it's implementing some specific goal; in the latter case it might be better to implement a general-purpose routine and then wrap it in a function which twiddles the return value to suit the spec.

def reiterator(sub):
    """Yield elements of a sequence, resetting if sent ``True``."""
    it = iter(sub)
    while True:
        if (yield
            it = iter(sub)

def find_in_sequence(sub, sequence):
    """Find a subsequence in a sequence.

    >>> find_in_sequence([2, 1], [-1, 0, 1, 2])
    >>> find_in_sequence([-1, 1, 2], [-1, 0, 1, 2])
    >>> find_in_sequence([0, 1, 2], [-1, 0, 1, 2])
    (1, 3)
    >>> find_in_sequence("subsequence",
    ...                  "This sequence contains a subsequence.")
    (25, 35)
    >>> find_in_sequence("subsequence", "This one doesn't.")

    start = None
    sub_items = reiterator(sub)
    sub_item =
    for index, item in enumerate(sequence):
        if item == sub_item:
            if start is None: start = index
            start = None
            sub_item = sub_items.send(start is None)
        except StopIteration:
            # If the subsequence is depleted, we win!
            return (start, index)
    return False

How to retrieve a user environment variable in CMake (Windows)

You need to have your variables exported. So for example in Linux:

export EnvironmentVariableName=foo

Unexported variables are empty in CMAKE.

Compare two Lists for differences

This approach from Microsoft works very well and provides the option to compare one list to another and switch them to get the difference in each. If you are comparing classes simply add your objects to two separate lists and then run the comparison.

Confusion: @NotNull vs. @Column(nullable = false) with JPA and Hibernate

The JPA @Column Annotation

The nullable attribute of the @Column annotation has two purposes:

  • it's used by the schema generation tool
  • it's used by Hibernate during flushing the Persistence Context

Schema Generation Tool

The HBM2DDL schema generation tool translates the @Column(nullable = false) entity attribute to a NOT NULL constraint for the associated table column when generating the CREATE TABLE statement.

As I explained in the Hibernate User Guide, it's better to use a tool like Flyway instead of relying on the HBM2DDL mechanism for generating the database schema.

Persistence Context Flush

When flushing the Persistence Context, Hibernate ORM also uses the @Column(nullable = false) entity attribute:

new Nullability( session ).checkNullability( values, persister, true );

If the validation fails, Hibernate will throw a PropertyValueException, and prevents the INSERT or UPDATE statement to be executed needesly:

if ( !nullability[i] && value == null ) {
    //check basic level one nullablilty
    throw new PropertyValueException(
            "not-null property references a null or transient value",

The Bean Validation @NotNull Annotation

The @NotNull annotation is defined by Bean Validation and, just like Hibernate ORM is the most popular JPA implementation, the most popular Bean Validation implementation is the Hibernate Validator framework.

When using Hibernate Validator along with Hibernate ORM, Hibernate Validator will throw a ConstraintViolation when validating the entity.

How to set textColor of UILabel in Swift

This code example that follows shows a basic UILabel configuration.

let lbl = UILabel(frame: CGRectMake(0, 0, 300, 200))
lbl.text = "yourString"

// Enum type, two variations:
lbl.textAlignment = NSTextAlignment.Right
lbl.textAlignment = .Right

lbl.textColor =
lbl.shadowColor =
lbl.font = UIFont(name: "HelveticaNeue", size: CGFloat(22))

Get last 3 characters of string

The easiest way would be using Substring

string str = "AM0122200204";
string substr = str.Substring(str.Length - 3);

Using the overload with one int as I put would get the substring of a string, starting from the index int. In your case being str.Length - 3, since you want to get the last three chars.

How to fix "namespace x already contains a definition for x" error? Happened after converting to VS2010

I had a similar issue however found a different solution than what I have read. I came to my fix after reading P Walker's answer.

My issue happened when I named my resource file for Japanese language incorrectly. Long story short I was trying to create a Resource for Japanese but I accidentally named it I then realized that the iso language code is ja not jp for Japanese. Once I changed the file name to localized.ja.resx and deleted everything that was in the designer file it fixed my problem.

This is what fixed my problem hopefully it helps someone else.

How to get the system uptime in Windows?

Two ways to do that..

Option 1:

1.  Go to "Start" -> "Run".

2.  Write "CMD" and press on "Enter" key.

3.  Write the command "net statistics server" and press on "Enter" key.

4.  The line that start with "Statistics since …" provides the time that the server was up from.

  The command "net stats srv" can be use instead.

Option 2:

Uptime.exe Tool Allows You to Estimate Server Availability with Windows NT 4.0 SP4 or Higher

Hope it helped you!!

Only allow specific characters in textbox

As mentioned in a comment (and another answer as I typed) you need to register an event handler to catch the keydown or keypress event on a text box. This is because TextChanged is only fired when the TextBox loses focus

The below regex lets you match those characters you want to allow

Regex regex = new Regex(@"[0-9+\-\/\*\(\)]");
MatchCollection matches = regex.Matches(textValue);

and this does the opposite and catches characters that aren't allowed

Regex regex = new Regex(@"[^0-9^+^\-^\/^\*^\(^\)]");
MatchCollection matches = regex.Matches(textValue);

I'm not assuming there'll be a single match as someone could paste text into the textbox. in which case catch textchanged

textBox1.TextChanged += new TextChangedEventHandler(textBox1_TextChanged);
private void textBox1_TextChanged(object sender, EventArgs e)
    Regex regex = new Regex(@"[^0-9^+^\-^\/^\*^\(^\)]");
    MatchCollection matches = regex.Matches(textBox1.Text);
    if (matches.Count > 0) {
       //tell the user

and to validate single key presses

textBox1.KeyPress += new KeyPressEventHandler(textBox1_KeyPress);
private void textBox1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
    // Check for a naughty character in the KeyDown event.
    if (System.Text.RegularExpressions.Regex.IsMatch(e.KeyChar.ToString(), @"[^0-9^+^\-^\/^\*^\(^\)]"))
        // Stop the character from being entered into the control since it is illegal.
        e.Handled = true;

How do I create a unique constraint that also allows nulls?

Create a view that selects only non-NULL columns and create the UNIQUE INDEX on the view:

FROM    mytable
WHERE   mycolumn IS NOT NULL

CREATE UNIQUE INDEX ux_myview_mycolumn ON myview (mycolumn)

Note that you'll need to perform INSERT's and UPDATE's on the view instead of table.

You may do it with an INSTEAD OF trigger:

CREATE TRIGGER trg_mytable_insert ON mytable
        INTO    myview
        SELECT  *
        FROM    inserted

Error in setting JAVA_HOME

The JAVA_HOME should point to the JDK home rather than the JRE home if you are going to be compiling stuff, likewise - I would try and install the JDK in a directory that doesn't include a space. Even if this is not your problem now, it can cause problems in the future!

Mockito: Mock private field initialization

In case you use Spring Test try org.springframework.test.util.ReflectionTestUtils

 ReflectionTestUtils.setField(testObject, "person", mockedPerson);

Rails: Missing host to link to! Please provide :host parameter or set default_url_options[:host]

just in case someone finds this searching for errors concerning ActiveStorage:

if you have a controller-action where you want to generate upload-urls etc with the local disc-service (most likely in test environment), you need to include ActiveStorage::SetCurrent in the controller in order to allow blob.service_url_for_direct_upload to work correctly.

Using lodash to compare jagged arrays (items existence without order)

You can use lodashs xor for this

doArraysContainSameElements = _.xor(arr1, arr2).length === 0

If you consider array [1, 1] to be different than array [1] then you may improve performance a bit like so:

doArraysContainSameElements = arr1.length === arr2.length === 0 && _.xor(arr1, arr2).length === 0

Can't choose class as main class in IntelliJ

Here is the complete procedure for IDEA IntelliJ 2019.3:

  1. File > Project Structure

  2. Under Project Settings > Modules

  3. Under 'Sources' tab, right-click on 'src' folder and select 'Sources'.

  4. Apply changes.

Java - Including variables within strings?

you can use String format to include variables within strings

i use this code to include 2 variable in string:

String myString = String.format("this is my string %s %2d", variable1Name, variable2Name);

TypeError: can't pickle _thread.lock objects

You need to change from queue import Queue to from multiprocessing import Queue.

The root reason is the former Queue is designed for threading module Queue while the latter is for multiprocessing.Process module.

For details, you can read some source code or contact me!

Loop over array dimension in plpgsql

Since PostgreSQL 9.1 there is the convenient FOREACH:

   m   varchar[];
   arr varchar[] := array[['key1','val1'],['key2','val2']];
      RAISE NOTICE 'another_func(%,%)',m[1], m[2];

Solution for older versions:

   arr varchar[] := '{{key1,val1},{key2,val2}}';
   FOR i IN array_lower(arr, 1) .. array_upper(arr, 1)
      RAISE NOTICE 'another_func(%,%)',arr[i][1], arr[i][2];

Also, there is no difference between varchar[] and varchar[][] for the PostgreSQL type system. I explain in more detail here.

The DO statement requires at least PostgreSQL 9.0, and LANGUAGE plpgsql is the default (so you can omit the declaration).

Property getters and setters

You can customize the set value using property observer. To do this use 'didSet' instead of 'set'.

class Point {

var x: Int {
    didSet {
        x = x * 2

As for getter ...

class Point {

var doubleX: Int {
    get {
        return x / 2

Using CSS in Laravel views?

Put your assets in the public folder


And them called it using Laravel

{{ HTML::script('js/scrollTo.js'); }}

{{ HTML::style('css/css.css'); }}

Programmatically scroll a UIScrollView

You can scroll to some point in a scroll view with one of the following statements in Objective-C

[scrollView setContentOffset:CGPointMake(x, y) animated:YES];

or Swift

scrollView.setContentOffset(CGPoint(x: x, y: y), animated: true)

See the guide "Scrolling the Scroll View Content" from Apple as well.

To do slideshows with UIScrollView, you arrange all images in the scroll view, set up a repeated timer, then -setContentOffset:animated: when the timer fires.

But a more efficient approach is to use 2 image views and swap them using transitions or simply switching places when the timer fires. See iPhone Image slideshow for details.

How to update std::map after using the find method?

You can use std::map::at member function, it returns a reference to the mapped value of the element identified with key k.

std::map<char,int> mymap = {
                               { 'a', 0 },
                               { 'b', 0 },
                           };'a') = 10;'b') = 20;

Create an Oracle function that returns a table

To return the whole table at once you could change the SELECT to:

FROM    ...

This is only advisable for results that aren't excessively large, since they all have to be accumulated in memory before being returned; otherwise consider the pipelined function as suggested by Charles, or returning a REF CURSOR.

Compare data of two Excel Columns A & B, and show data of Column A that do not exist in B

All values of column A that are not present in column B will have a red background. Hope that it helps as starting point.

Sub highlight_missings()
Dim i As Long, lastA As Long, lastB As Long
Dim compare As Variant
lastA = Range("A65536").End(xlUp).Row
lastB = Range("B65536").End(xlUp).Row

For i = 2 To lastA
    compare = Application.Match(Range("a" & i), Range("B2:B" & lastB), 0)
        If IsError(compare) Then
            Range("A" & i).Interior.ColorIndex = 3
        End If
Next i
End Sub

How to identify all stored procedures referring a particular table

FROM sys.procedures

BTW -- here is a handy resource for this type of question: Querying the SQL Server System Catalog FAQ

How to send list of file in a folder to a txt file in Linux

If only names of regular files immediately contained within a directory (assume it's ~/dirs) are needed, you can do

find ~/docs -type f -maxdepth 1 > filenames.txt

How can I set a dynamic model name in AngularJS?

You can use something like this scopeValue[field], but if your field is in another object you will need another solution.

To solve all kind of situations, you can use this directive:'dynamicModel', ['$compile', '$parse', function ($compile, $parse) {
    return {
        restrict: 'A',
        terminal: true,
        priority: 100000,
        link: function (scope, elem) {
            var name = $parse(elem.attr('dynamic-model'))(scope);
            elem.attr('ng-model', name);

Html example:

<input dynamic-model="'scopeValue.' + field" type="text">

How to correctly use Html.ActionLink with ASP.NET MVC 4 Areas

Below are some of the way by which you can create a link button in MVC.

@Html.ActionLink("Admin", "Index", "Home", new { area = "Admin" }, null)  
@Html.RouteLink("Admin", new { action = "Index", controller = "Home", area = "Admin" })  
@Html.Action("Action", "Controller", new { area = "AreaName" })  
@Url.Action("Action", "Controller", new { area = "AreaName" })  
<a class="ui-btn" data-val="abc" href="/Home/Edit/ANTON">Edit</a>  
<a data-ajax="true" data-ajax-method="GET" data-ajax-mode="replace" data-ajax-update="#CustomerList" href="/Home/Germany">Customer from Germany</a>  
<a data-ajax="true" data-ajax-method="GET" data-ajax-mode="replace" data-ajax-update="#CustomerList" href="/Home/Mexico">Customer from Mexico</a> 

Hope this will help you.

Is there any way to kill a Thread?

If you really need the ability to kill a sub-task, use an alternate implementation. multiprocessing and gevent both support indiscriminately killing a "thread".

Python's threading does not support cancellation. Do not even try. Your code is very likely to deadlock, corrupt or leak memory, or have other unintended "interesting" hard-to-debug effects which happen rarely and nondeterministically.

Can I convert a boolean to Yes/No in a ASP.NET GridView

I use this code for VB:

<asp:TemplateField HeaderText="Active" SortExpression="Active">
    <ItemTemplate><%#IIf(Boolean.Parse(Eval("Active").ToString()), "Yes", "No")%></ItemTemplate>

And this should work for C# (untested):

<asp:TemplateField HeaderText="Active" SortExpression="Active">
    <ItemTemplate><%# (Boolean.Parse(Eval("Active").ToString())) ? "Yes" : "No" %></ItemTemplate>

How to custom switch button?

I use this approach to create a custom switch using a RadioGroup and RadioButton;


enter image description here

Color Resource

<color name="blue">#FF005a9c</color>
<color name="lightBlue">#ff6691c4</color>
<color name="lighterBlue">#ffcdd8ec</color>
<color name="controlBackground">#ffffffff</color>

control_switch_color_selector (in res/color folder)

<selector xmlns:android="">



<shape xmlns:android=""
    <corners android:radius="5dp" />
    <solid android:color="@android:color/transparent" />
        android:color="@color/blue" />


<selector xmlns:android="">
    <item android:state_checked="true">
            <solid android:color="@color/blue"></solid>
    <item android:state_pressed="true">
            <solid android:color="@color/lighterBlue"></solid>
            <solid android:color="@android:color/transparent"></solid>


<selector xmlns:android="">
    <item android:state_checked="true">
            <solid android:color="@color/blue"></solid>
    <item android:state_pressed="true">
            <solid android:color="@color/lighterBlue"></solid>
            <item android:top="-1dp" android:bottom="-1dp" android:left="-1dp">
                    <solid android:color="@android:color/transparent"></solid>
                    <stroke android:width="1dp" android:color="@color/blue"></stroke>


            android:textColor="@color/control_switch_color_selector" />

PySpark: multiple conditions in when clause

it should works at least in pyspark 2.4

tdata = tdata.withColumn("Age",  when((tdata.Age == "") & (tdata.Survived == "0") , "NewValue").otherwise(tdata.Age))

Get properties of a class

Another solution, You can just iterate over the object keys like so, Note: you must use an instantiated object with existing properties:

printTypeNames<T>(obj: T) {
    const objectKeys = Object.keys(obj) as Array<keyof T>;
    for (let key of objectKeys)
       console.log('key:' + key);

Error "There is already an open DataReader associated with this Command which must be closed first" when using 2 distinct commands

I bet the problem is being shown in this line

SqlDataReader dr3 = com2.ExecuteReader();

I suggest that you execute the first reader and do a dr.Close(); and the iterate historicos, with another loop, performing the com2.ExecuteReader().

public List<string[]> get_dados_historico_verificacao_email_WEB(string email)

        List<string[]> historicos = new List<string[]>();
        sql = "SELECT * FROM historico_verificacao_email WHERE nm_email = '" + email + "' ORDER BY  dt_verificacao_email DESC, hr_verificacao_email DESC"; 
        com = new SqlCommand(sql, conexao);
        SqlDataReader dr = com.ExecuteReader();

        if (dr.HasRows)
            while (dr.Read())
                string[] dados_historico = new string[6];
                dados_historico[0] = dr["nm_email"].ToString();
                dados_historico[1] = dr["dt_verificacao_email"].ToString();
                dados_historico[1] = dados_historico[1].Substring(0, 10);
                dados_historico[2] = dr["hr_verificacao_email"].ToString();
                dados_historico[3] = dr["ds_tipo_verificacao"].ToString();
                dados_historico[5] = dr["cd_login_usuario"].ToString();


            sql = "SELECT COUNT(e.cd_historico_verificacao_email) QT FROM emails_lidos e WHERE e.cd_historico_verificacao_email = '" + dr["cd_historico_verificacao_email"].ToString() + "'";
            tipo_sql = "seleção";
            com2 = new SqlCommand(sql, conexao);

            for(int i = 0 ; i < historicos.Count() ; i++)
                SqlDataReader dr3 = com2.ExecuteReader();
                while (dr3.Read())
                    historicos[i][4] = dr3["QT"].ToString(); //quantidade de emails lidos naquela verificação


        return historicos;

How to check if an object implements an interface?

In general for AnInterface and anInstance of any class:


Django: List field in model?

If you're on Django 1.10 or newer AND Postgres as your database, you can use ArrayField. It's better to use than django-taggit or other alternatives, as it's native to the Django framework.

from django.db import models
from django.contrib.postgres.fields import ArrayField

class ChessBoard(models.Model):
    board = ArrayField(
            models.CharField(max_length=10, blank=True),

If you're on Django 3.1 or newer they've added support for JSONField with most database backends (MariaDB 10.2.7+, MySQL 5.7.8+, Oracle, PostgreSQL, and SQLite 3.9.0+). You can use this to store your Array!

from django.db import models

class ChessBoard(models.Model):
    list_of_pieces = models.JSONField()

Shell script to capture Process ID and kill it if exist

You probably wanted to write

`ps -ef | grep syncapp | awk '{print $2}'`

but I will endorse @PaulR's answer - killall -9 syncapp is a much better alternative.

Python Key Error=0 - Can't find Dict error in code

The error you're getting is that self.adj doesn't already have a key 0. You're trying to append to a list that doesn't exist yet.

Consider using a defaultdict instead, replacing this line (in __init__):

self.adj = {}

with this:

self.adj = defaultdict(list)

You'll need to import at the top:

from collections import defaultdict

Now rather than raise a KeyError, self.adj[0].append(edge) will create a list automatically to append to.

installing cPickle with python 3.5

cPickle comes with the standard library… in python 2.x. You are on python 3.x, so if you want cPickle, you can do this:

>>> import _pickle as cPickle

However, in 3.x, it's easier just to use pickle.

No need to install anything. If something requires cPickle in python 3.x, then that's probably a bug.

What is the most "pythonic" way to iterate over a list in chunks?

One-liner, adhoc solution to iterate over a list x in chunks of size 4 -

for a, b, c, d in zip(x[0::4], x[1::4], x[2::4], x[3::4]):
    ... do something with a, b, c and d ...

How to get just the responsive grid from Bootstrap 3?

Checkout zirafa/bootstrap-grid-only. It contains only the bootstrap grid and responsive utilities that you need (no reset or anything), and simplifies the complexity of working directly with the LESS files.

Reverting to a specific commit based on commit id with Git?

Do you want to roll back your repo to that state, or you just want your local repo to look like that?

If you reset --hard, it will make your local code and local history be just like it was at that commit. But if you wanted to push this to someone else who has the new history, it would fail:

git reset --hard c14809fa

And if you reset --soft, it will move your HEAD to where they were , but leave your local files etc. the same:

git reset --soft c14809fa

So what exactly do you want to do with this reset?

Edit -

You can add "tags" to your repo.. and then go back to a tag. But a tag is really just a shortcut to the sha1.

You can tag this as TAG1.. then a git reset --soft c14809fa, git reset --soft TAG1, or git reset --soft c14809fafb08b9e96ff2879999ba8c807d10fb07 would all do the same thing.

Limiting number of displayed results when using ngRepeat

Another (and I think better) way to achieve this is to actually intercept the data. limitTo is okay but what if you're limiting to 10 when your array actually contains thousands?

When calling my service I simply did this:

    $scope.tasks = data.slice(0,10);

This limits what is sent to the view, so should be much better for performance than doing this on the front-end.

Automatically resize jQuery UI dialog to the width of the content loaded by ajax

I had the same problem when I upgraded jquery UI to 1.8.1 without upgrading the corresponding theme. Only is needed to upgrade the theme too and "auto" works again.

How to remove leading zeros using C#

This is the code you need:

string strInput = "0001234";
strInput = strInput.TrimStart('0');

How to see local history changes in Visual Studio Code?

I think there is no out-of-the-box support for that in VS Code.

You can install a plugin to give you similar functionality. Eg.:

Or the more famous:

Some details may need to be configured: The VS Code search gets confused sometimes because of additional folders created by this type of plugins. You can configure it to ignore such folders or change their locations (adding such folders to your .gitignore file also solves this problem).

center a row using Bootstrap 3

I use this peace of code and I have successeful

<div class="row  center-block">
<div style="margin: 0 auto;width: 90%;"> 
    <div class="col-md-12" style="top:10px;">
    <div class="col-md-12" style="top:10px;">

CSS class for pointer cursor

There is no classes for that. But you can add inline style for your div or other elements like,

<div class="" style="cursor: pointer;">

Using NULL in C++?

From crtdbg.h (and many other headers):

#ifndef NULL
#ifdef __cplusplus
#define NULL    0
#define NULL    ((void *)0)

Therefore NULL is 0, at least on the Windows platform. So no, not that I know of.

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

For people reading this that use Angular 2 rc4 or later, it appears LocationStrategy has been moved from router to common. You'll have to import it from there.

Also note the curly brackets around the 'provide' line.


// Imports for loading & configuring the in-memory web api
import { XHRBackend } from '@angular/http';

// The usual bootstrapping imports
import { bootstrap }      from '@angular/platform-browser-dynamic';
import { HTTP_PROVIDERS } from '@angular/http';

import { AppComponent }         from './app.component';
import { APP_ROUTER_PROVIDERS } from './app.routes';
import { Location, LocationStrategy, HashLocationStrategy} from '@angular/common';

bootstrap(AppComponent, [
    {provide: LocationStrategy, useClass: HashLocationStrategy}

How to modify existing XML file with XmlDocument and XmlNode in C#

You need to do something like this:

// instantiate XmlDocument and load XML from file
XmlDocument doc = new XmlDocument();

// get a list of nodes - in this case, I'm selecting all <AID> nodes under
// the <GroupAIDs> node - change to suit your needs
XmlNodeList aNodes = doc.SelectNodes("/Equipment/DataCollections/GroupAIDs/AID");

// loop through all AID nodes
foreach (XmlNode aNode in aNodes)
   // grab the "id" attribute
   XmlAttribute idAttribute = aNode.Attributes["id"];

   // check if that attribute even exists...
   if (idAttribute != null)
      // if yes - read its current value
      string currentValue = idAttribute.Value;

      // here, you can now decide what to do - for demo purposes,
      // I just set the ID value to a fixed value if it was empty before
      if (string.IsNullOrEmpty(currentValue))
         idAttribute.Value = "515";

// save the XmlDocument back to disk

Difference of two date time in sql server

Please check below trick to find the date difference between two dates

 DATEDIFF(DAY,ordr.DocDate,RDR1.U_ProgDate) datedifff

where you can change according your requirement as you want difference of days or month or year or time.

How can strip whitespaces in PHP's variable?

This is an old post but the shortest answer is not listed here so I am adding it now

strtr($str,[' '=>'']);

Another common way to "skin this cat" would be to use explode and implode like this

implode('',explode(' ', $str));

Array Index Out of Bounds Exception (Java)

import java.util.Scanner;
class ar1 {
    public static void main(String[] args) {
        //Scanner sc=new Scanner(;
        int[] a={10,20,30,40,12,32};
        int bi=0,sm=0;
        for(int i=0;i<=a.length-1;i++) {


How to add external fonts to android application

To implement you need use Typeface go through with sample below

Typeface typeface = Typeface.createFromAsset(getAssets(), "fonts/Roboto/Roboto-Regular.ttf");
for (View view : allViews)
   if (view instanceof TextView) 
      TextView textView = (TextView) view;

Where Sticky Notes are saved in Windows 10 1607

In windows 10 you can recover in this way, there is no .snt file

  1. Start Run
  2. Go to this %LocalAppData%\Packages\Microsoft.MicrosoftStickyNotes_8wekyb3d8bbwe
  3. Copy this folder Microsoft.MicrosoftStickyNotes_8wekyb3d8bbwe
  4. Replace it with new Microsoft.MicrosoftStickyNotes_8wekyb3d8bbwe
  5. Check your sticky notes now, you will get all your data

how to execute php code within javascript

You can't run PHP with javascript. JavaScript is a client side technology (runs in the users browser) and PHP is a server side technology (run on the server).

If you want to do this you have to make an ajax request to a PHP script and have that return the results you are looking for.

Why do you want to do this?

How to determine if a decimal/double is an integer?

I faced a similar situation, but where the value is a string. The user types in a value that's supposed to be a dollar amount, so I want to validate that it's numeric and has at most two decimal places.

Here's my code to return true if the string "s" represents a numeric with at most two decimal places, and false otherwise. It avoids any problems that would result from the imprecision of floating-point values.

    // must be numeric value
    double d = double.Parse(s);
    // max of two decimal places
    if (s.IndexOf(".") >= 0)
        if (s.Length > s.IndexOf(".") + 3)
            return false;
    return true;
    return false;

I discuss this in more detail at

What is the difference between an interface and abstract class?

usually Abstract class used for core of something but interface used for appending peripheral.

when you want to create base type for vehicle you should use abstract class but if you want to add some functionality or property that is not part of base concept of vehicle you should use interface,for example you want to add "ToJSON()" function.

interface has wide range of abstraction rather than abstract class. you can see this in passing arguments.look this example:

enter image description here

if you use vehicle as argument you just can use one of its derived type (bus or car-same category-just vehicle category). but when you use IMoveable interface as argument you have more choices.

Using async/await for multiple tasks

I just want to add to all great answers above, that if you write a library it's a good practice to use ConfigureAwait(false) and get better performance, as said here.

So this snippet seems to be better:

 public static async Task DoWork() 
     int[] ids = new[] { 1, 2, 3, 4, 5 };
     await Task.WhenAll(ids.Select(i => DoSomething(1, i))).ConfigureAwait(false);

A full fiddle link here.

AES Encrypt and Decrypt

There is an interesting "pure-swift" Open Source library:

Example with AES decrypt (got from project file):

import CryptoSwift
let setup = (key: keyData, iv: ivData)
let decryptedAES = AES(setup).decrypt(encryptedData)

Twitter Bootstrap Modal Form Submit


<div class="modal-footer">
<button class="btn" data-dismiss="modal" aria-hidden="true">Close</button>
<button class="btn btn-primary" onclick="event.preventDefault();document.getElementById('your-form').submit();">Save changes</button>

Change package name for Android in React Native

Before changing your react native package name! please make a backup of and file. Because this lib remove your and

after doing this you can simply use react-native-rename npm package.


npm install react-native-rename -g

Then from the root of your React Native project execute the following

react-native-rename "new_project_name" -b com.mycompany.newprojectname

finally you can check it out your new package name in your AndroidManifest.xml. Don't forgot to rename the package name in your and .

Thank you.

Add some word to all or some rows in Excel?

  1. Insert a column left to the column in question(adding column A beside column B).
  2. Provide the value you want to append in 1st cell of column A
  3. Insert a column right to the column in question ( column C)
  4. Add this formula -> =CONCATENATE("A1","B1")
  5. Drag it down to apply to all values in column
  6. You will find concatenated values in column C

This worked for me !

How to combine GROUP BY and ROW_NUMBER?

Wow, the other answers look complex - so I'm hoping I've not missed something obvious.

You can use OVER/PARTITION BY against aggregates, and they'll then do grouping/aggregating without a GROUP BY clause. So I just modified your query to:

select T2.ID AS T2ID
    ,T2.Name as T2Name
    ,T1.ID AS T1ID
    ,T1.Name As T1Name
FROM @t2 T2
    SELECT Rel.t2ID
 --       ,MAX(Rel.t1ID)AS t1ID 
-- the MAX returns an arbitrary ID, what i need is: 
      ,ROW_NUMBER()OVER(Partition By Rel.t2ID Order By Price DESC)As PriceList
        ,SUM(Price)OVER(PARTITION BY Rel.t2ID) AS Price
        FROM @t1 T1 
        INNER JOIN @relation Rel ON Rel.t1ID=T1.ID
--        GROUP BY Rel.t2ID
)AS T1Sum ON  T1Sum.t2ID = T2.ID
where t1Sum.PriceList = 1

Which gives the requested result set.

OperationalError, no such column. Django

I faced this problem and this is how I solved it.

1) Delete all the migration records from your app's migration directory. These are files named 0001_,0002_,0003_ etc. Be careful as to not delete the file.

2) Delete the db.sqlite3 file. It will be regenerated later.

Now, run the following commands:

python makemigrations appname
python migrate

Be sure to write the name of your app after makemigrations. You might have to create a superuser to access your database again. Do so by the following

python createsuperuser

The type initializer for 'CrystalDecisions.CrystalReports.Engine.ReportDocument' threw an exception

This is because of lack of Capability .... If you see the Inner Exception you will see this message

"Access is denied.
Access to speech functionality requires ID_CAP_SPEECH_RECOGNITION to be defined in the manifest."

So to get rid of this exception. turn on the capability for Speech Recognition from the Manifest file.

I had the same problem, and It solved my Problem. :)

Change DataGrid cell colour based on values

Just put instead

<Style TargetType="{x:DataGridCell}" >

But beware that this will target ALL your cells (you're aiming at all the objects of type DataGridCell ) If you want to put a style according to the cell type, I'd recommend you to use a DataTemplateSelector

A good example can be found in Christian Mosers' DataGrid tutorial:

Have fun :)

how to start stop tomcat server using CMD?

This is what I used to start and stop tomcat 7.0.29, using ant 1.8.2. Works fine for me, but leaves the control in the started server window. I have not tried it yet, but I think if I change the "/K" in the startup sequence to "/C", it may not even do that.

<target name="tomcat-stop">
    <exec dir="${appserver.home}/bin" executable="cmd">
        <arg line="/C start cmd.exe /C shutdown.bat"/>

<target name="tomcat-start" depends="tomcat-stop" >
    <exec dir="${appserver.home}/bin" executable="cmd">
        <arg line="/K start cmd.exe /C startup.bat"/>


Disable dragging an image from an HTML page

img {
  -moz-user-select: none;
  -webkit-user-select: none;
  -ms-user-select: none;
  user-select: none;
  -webkit-user-drag: none;
  user-drag: none;
  -webkit-touch-callout: none;

I used it on my website at It's works like a magic!!! :)

the best way to make codeigniter website multi-language. calling from lang arrays depends on lang session?

I am using such code in config.php:

$lang = 'ru'; // this language will be used if there is no any lang information from useragent (for example, from command line, wget, etc...

if (!empty($_SERVER['HTTP_ACCEPT_LANGUAGE'])) $lang = substr($_SERVER['HTTP_ACCEPT_LANGUAGE'],0,2);
$tmp_value = $_COOKIE['language'];
if (!empty($tmp_value)) $lang = $tmp_value;
switch ($lang)
    case 'ru':
        $config['language'] = 'russian';
        case 'uk':
        $config['language'] = 'ukrainian';
        case 'foo':
        $config['language'] = 'foo';
        $config['language'] = 'english';

.... and then i'm using usualy internal mechanizm of CI

o, almost forget! in views i using buttons, which seting cookie 'language' with language, prefered by user.

So, first this code try to detect "preffered language" setted in user`s useragent (browser). Then code try to read cookie 'language'. And finaly - switch sets language for CI-application

How can I put a ListView into a ScrollView without it collapsing?

try this, this works for me, I forgot where I found it, somewhere in stack overflow, i'm not here to explained it why it doesn't work, but this is the answer :).

    final ListView AturIsiPulsaDataIsiPulsa = (ListView) findViewById(;
    AturIsiPulsaDataIsiPulsa.setOnTouchListener(new ListView.OnTouchListener() 
        public boolean onTouch(View v, MotionEvent event) 
            int action = event.getAction();
            switch (action) 
                case MotionEvent.ACTION_DOWN:
                // Disallow ScrollView to intercept touch events.

                case MotionEvent.ACTION_UP:
                // Allow ScrollView to intercept touch events.

            // Handle ListView touch events.
            return true;

EDIT !, I finally found out where I got the code. here ! : ListView inside ScrollView is not scrolling on Android

Compare two dates with JavaScript

By far the easiest method is to subtract one date from the other and compare the result.

var oDateOne = new Date();_x000D_
var oDateTwo = new Date();_x000D_
alert(oDateOne - oDateTwo === 0);_x000D_
alert(oDateOne - oDateTwo < 0);_x000D_
alert(oDateOne - oDateTwo > 0);

Safest way to get last record ID from a table

I think this one will also work:


How can I display an RTSP video stream in a web page?

I know that this post is old but I was looking for something very similar the other day (view my IP cam's RTSP video feed on a simple html page without any fancy ActiveX plugins). Lucky me, I found a solution! It is based on ffmpeg, NodeJS, NGINX (not mandatory but useful) and Node Media Server.

The description in the link is detailed and easy to follow, but I still had some tweaks to deal with before I got it to work (regarding endpoints on the NodeJS server). I made an own question for it and got a good and working answer.

Select current date by default in ASP.Net Calendar control

Two ways of doing it.

Late binding

<asp:Calendar ID="planning" runat="server" SelectedDate="<%# DateTime.Now %>"></asp:Calendar>

Code behind way (Page_Load solution)

protected void Page_Load(object sender, EventArgs e)

private void BindCalendar()
    planning.SelectedDate = DateTime.Today;

Altough, I strongly recommend to do it from a BindMyStuff way. Single entry point easier to debug. But since you seems to know your game, you're all set.

Copy Image from Remote Server Over HTTP

If you have PHP5 and the HTTP stream wrapper enabled on your server, it's incredibly simple to copy it to a local file:

copy('', '/tmp/file.jpeg');

This will take care of any pipelining etc. that's needed. If you need to provide some HTTP parameters there is a third 'stream context' parameter you can provide.

Angular ForEach in Angular4/Typescript?

in angular4 foreach like that. try this.

 selectChildren(data, $event) {
      let parentChecked = data.checked;
       this.hierarchicalData.forEach(obj => {
          obj.forEach(childObj=> {
            value.checked = parentChecked;

Setting "checked" for a checkbox with jQuery

If you happen to be using Bootstrap (perhaps unawarely) ...


How to escape single quotes in MySQL

For programmatic access, you can use placeholders to automatically escape unsafe characters for you.

In Perl DBI, for example, you can use:

my $string = "This is Ashok's pen";
$dbh->do("insert into my_table(my_string) values(?)",undef,($string)); 

How do I change the background color with JavaScript?

But you would want to configure the body color before the <body> element exists. That way it has the right color from the get go.

    var myColor = "#AAAAAA";
                background-color: '+myColor+';\

This you can put in the <head> of the document or in your js file.

Here is a nice color to play with.

var myColor = '#'+(Math.random()*0xFFFFFF<<0).toString(16);

npm not working after clearing cache

at [email protected] the command that is been supported is npm cache verify

What do $? $0 $1 $2 mean in shell script?

They are called the Positional Parameters.

3.4.1 Positional Parameters

A positional parameter is a parameter denoted by one or more digits, other than the single digit 0. Positional parameters are assigned from the shell’s arguments when it is invoked, and may be reassigned using the set builtin command. Positional parameter N may be referenced as ${N}, or as $N when N consists of a single digit. Positional parameters may not be assigned to with assignment statements. The set and shift builtins are used to set and unset them (see Shell Builtin Commands). The positional parameters are temporarily replaced when a shell function is executed (see Shell Functions).

When a positional parameter consisting of more than a single digit is expanded, it must be enclosed in braces.

C# refresh DataGridView when updating or inserted on another form

Create a small function and use it anywhere

public SqlConnection con = "Your connection string"; 
public void gridviewUpdate()
    string select = "SELECT * from table_name";
    SqlDataAdapter da = new SqlDataAdapter(select, con);
    DataSet ds = new DataSet();
    da.Fill(ds, "table_name");
    datagridview.DataSource = ds;
    datagridview.DataMember = "table_name";

Windows equivalent of linux cksum command

Open Windows PowerShell, and use the below command:

Get-FileHash C:\Users\Deepak\Downloads\ubuntu-20.10-desktop-amd64.iso

Session only cookies with Javascript

For creating session only cookie with java script, you can use the following. This works for me.

document.cookie = "cookiename=value; expires=0; path=/";

then get cookie value as following

 //get cookie 
var cookiename = getCookie("cookiename");
if (cookiename == "value") {
    //write your script

//function getCookie        
function getCookie(cname) {
    var name = cname + "=";
    var ca = document.cookie.split(';');
    for (var i = 0; i < ca.length; i++) {
        var c = ca[i];
        while (c.charAt(0) == ' ') c = c.substring(1);
        if (c.indexOf(name) != -1) return c.substring(name.length, c.length);
    return "";

Okay to support IE we can leave "expires" completely and can use this

document.cookie = "mtracker=somevalue; path=/";

Setting the default ssh key location

If you are only looking to point to a different location for you identity file, the you can modify your ~/.ssh/config file with the following entry:

IdentityFile ~/.foo/identity

man ssh_config to find other config options.

Reading and displaying data from a .txt file

In Java 8, you can read a whole file, simply with:

public String read(String file) throws IOException {
  return new String(Files.readAllBytes(Paths.get(file)));

or if its a Resource:

public String read(String file) throws IOException {
  URL url = Resources.getResource(file);
  return Resources.toString(url, Charsets.UTF_8);

Java SSLHandshakeException "no cipher suites in common"

You're initialising your SSLContext with a null KeyManager array.

The key manager is what handles the server certificate (on the server side), and this is what you're probably aiming to set when using

However, as described in the JSSE Reference Guide, using null for the first parameter doesn't do what you seem to think it does:

If the KeyManager[] parameter is null, then an empty KeyManager will be defined for this context. If the TrustManager[] parameter is null, the installed security providers will be searched for the highest-priority implementation of the TrustManagerFactory, from which an appropriate TrustManager will be obtained. Likewise, the SecureRandom parameter may be null, in which case a default implementation will be used.

An empty KeyManager doesn't contain any RSA or DSA certificates. Therefore, all the default cipher suites that would rely on such a certificate are disabled. This is why you get all these "Ignoring unavailable cipher suite" messages, which ultimately result in a "no cipher suites in common" message.

If you want your keystore to be used as a keystore, you'll need to load it and initialise a KeyManagerFactory with it:

    KeyStore ks = KeyStore.getInstance("JKS");
    InputStream ksIs = new FileInputStream("...");
    try {
        ks.load(ksIs, "password".toCharArray());
    } finally {
        if (ksIs != null) {

    KeyManagerFactory kmf = KeyManagerFactory.getInstance(KeyManagerFactory
    kmf.init(ks, "keypassword".toCharArray());

The use kmf.getKeyManagers() as the first parameter to SSLContext.init().

For the other two parameters, since you're visibly not requesting client-certificate authentication, you should leave the trust manager to its default value (null) instead of copying/pasting a trust manager that's a potential cause of vulnerability, and you can also use the default null SecureRandom.

jQuery get an element by its data-id

You can always use an attribute selector. The selector itself would look something like:


getMinutes() 0-9 - How to display two digit numbers?

Using ECMAScript Internationalization API, more info:

const twoDigitMinutes = date.toLocaleString('en-us', { minute: '2-digit' });

How to append in a json file in Python?

You need to update the output of json.load with a_dict and then dump the result. And you cannot append to the file but you need to overwrite it.

How to implement a Navbar Dropdown Hover in Bootstrap v4?

CSS and Desktop only solution

@media (min-width: 992px) { 
.dropdown:hover>.dropdown-menu {
  display: block;

Animate a custom Dialog

I have created the Fade in and Fade Out animation for Dialogbox using ChrisJD code.

  1. Inside res/style.xml

    <style name="AppTheme" parent="android:Theme.Light" />
    <style name="PauseDialog" parent="@android:style/Theme.Dialog">
        <item name="android:windowAnimationStyle">@style/PauseDialogAnimation</item>
    <style name="PauseDialogAnimation">
        <item name="android:windowEnterAnimation">@anim/fadein</item>
        <item name="android:windowExitAnimation">@anim/fadeout</item>

  2. Inside anim/fadein.xml

    <alpha xmlns:android=""
        android:fromAlpha="0.0" android:toAlpha="1.0" android:duration="500" />
  3. Inside anim/fadeout.xml

    <alpha xmlns:android=""
        android:fromAlpha="1.0" android:toAlpha="0.0" android:duration="500" />
  4. MainActivity

    Dialog imageDiaglog= new Dialog(MainActivity.this,;

Adding a color background and border radius to a Layout

background.xml in drawable folder.

<?xml version="1.0" encoding="UTF-8"?> 
<shape xmlns:android=""> 
    <solid android:color="#FFFFFF"/>    
        android:color="#0FECFF" />

    //specify gradient



img onclick call to JavaScript function

Put the javascript part and the end right before the closing </body> then it should work.

  <img onclick="exportToForm('1.6','55','10','50','1');" src="China-Flag-256.png"/>
  <button onclick="exportToForm('1.6','55','10','50','1');" style="background-color: #00FFFF">Export</button>

  <script type="text/javascript">
      function exportToForm(a,b,c,d,e) {
      alert(a + b);
      window.external.values(a.value, b.value, c.value, d.value, e.value);

How to get a specific output iterating a hash in Ruby?

hash.each do |key, array|
  puts "#{key}-----"
  puts array

Regarding order I should add, that in 1.8 the items will be iterated in random order (well, actually in an order defined by Fixnum's hashing function), while in 1.9 it will be iterated in the order of the literal.

How do I clear only a few specific objects from the workspace?

You'll find the answer by typing ?rm

rm(data_1, data_2, data_3)

Convert CString to const char*

If your CString is Unicode, you'll need to do a conversion to multi-byte characters. Fortunately there is a version of CString which will do this automatically.

CString unicodestr = _T("Testing");
CStringA charstr(unicodestr);
DoMyStuff((const char *) charstr);

Xcode "Build and Archive" from command line

I found some of the other answers here hard to get going. This article did if for me. Some paths may need to be absolute, as mentioned in the other answers.

The Command:

xcrun -sdk iphoneos PackageApplication \
    "/path/to/build/" \
    -o "output/path/to/MyApp.ipa" \
    --sign "iPhone Distribution: My Company" \
    --embed "/path/to/something.mobileprovision"

entity object cannot be referenced by multiple instances of IEntityChangeTracker. while adding related objects to entity in Entity Framework 4.1

Steps to reproduce can be simplified to this:

var contextOne = new EntityContext();
var contextTwo = new EntityContext();

var user = contextOne.Users.FirstOrDefault();

var group = new Group();
group.User = user;


Code without error:

var context = new EntityContext();

var user = context.Users.FirstOrDefault();

var group = new Group();
group.User = user; // Be careful when you set entity properties. 
// Be sure that all objects came from the same context


Using only one EntityContext can solve this. Refer to other answers for other solutions.

WPF popup window

In WPF there is a control named Popup.

Popup myPopup = new Popup();
myPopup.IsOpen = true;

Get local href value from anchor (a) tag

document.getElementById("link").getAttribute("href"); If you have more than one <a> tag, for example:

    <a href="1"></a>_x000D_
    <a href="2"></a>_x000D_
    <a href="3"></a>_x000D_

You can do it like this: document.getElementById("link")[0].getAttribute("href"); to access the first array of <a> tags, or depends on the condition you make.

How to validate array in Laravel?

The recommended way to write validation and authorization logic is to put that logic in separate request classes. This way your controller code will remain clean.

You can create a request class by executing php artisan make:request SomeRequest.

In each request class's rules() method define your validation rules:

public function rules()
   return [
    "name"    => [
          'array', // input must be an array
          'min:3'  // there must be three members in the array
    "name.*"  => [
          'string',   // input must be of type string
          'distinct', // members of the array must be unique
          'min:3'     // each string must have min 3 chars

In your controller write your route function like this:

// SomeController.php
public function store(SomeRequest $request) 
  // Request is already validated before reaching this point.
  // Your controller logic goes here.

public function update(SomeRequest $request)
  // It isn't uncommon for the same validation to be required
  // in multiple places in the same controller. A request class
  // can be beneficial in this way.

Each request class comes with pre- and post-validation hooks/methods which can be customized based on business logic and special cases in order to modify the normal behavior of request class.

You may create parent request classes for similar types of requests (e.g. web and api) requests and then encapsulate some common request logic in these parent classes.

How can I get table names from an MS Access Database?

To build on Ilya's answer try the following query:

SELECT MSysObjects.Name AS table_name
FROM MSysObjects
WHERE (((Left([Name],1))<>"~") 
        AND ((Left([Name],4))<>"MSys") 
        AND ((MSysObjects.Type) In (1,4,6)))
order by MSysObjects.Name 

(this one works without modification with an MDB)

ACCDB users may need to do something like this

SELECT MSysObjects.Name AS table_name
FROM MSysObjects
WHERE (((Left([Name],1))<>"~") 
        AND ((Left([Name],4))<>"MSys") 
        AND ((MSysObjects.Type) In (1,4,6))
        AND ((MSysObjects.Flags)=0))
order by MSysObjects.Name 

As there is an extra table is included that appears to be a system table of some sort.

A circular reference was detected while serializing an object of type 'SubSonic.Schema .DatabaseColumn'.

JSON, like xml and various other formats, is a tree-based serialization format. It won't love you if you have circular references in your objects, as the "tree" would be:

root B => child A => parent B => child A => parent B => ...

There are often ways of disabling navigation along a certain path; for example, with XmlSerializer you might mark the parent property as XmlIgnore. I don't know if this is possible with the json serializer in question, nor whether DatabaseColumn has suitable markers (very unlikely, as it would need to reference every serialization API)

In jQuery, how do I get the value of a radio button when they all have the same name?



How do I stretch an image to fit the whole background (100% height x 100% width) in Flutter?

I think that for your purpose Flex could work better than Container():

new Flex(
    direction: Axis.vertical,
    children: <Widget>[

How to get a list of column names

Try this sqlite table schema parser, I implemented the sqlite table parser for parsing the table definitions in PHP.

It returns the full definitions (unique, primary key, type, precision, not null, references, table constraints... etc)

Mongoose and multiple database in single node.js project

As an alternative approach, Mongoose does export a constructor for a new instance on the default instance. So something like this is possible.

var Mongoose = require('mongoose').Mongoose;

var instance1 = new Mongoose();

var instance2 = new Mongoose();

This is very useful when working with separate data sources, and also when you want to have a separate database context for each user or request. You will need to be careful, as it is possible to create a LOT of connections when doing this. Make sure to call disconnect() when instances are not needed, and also to limit the pool size created by each instance.

Regex match digits, comma and semicolon?

You almost have it, you just left out 0 and forgot the quantifier.


"Default Activity Not Found" on Android Studio upgrade

Since Android Studio 3.5 or 3.6 I started getting the Default Activity not found and I became tired of Invalidating Caches & Restart, rebuilding project etc.

It turned out, the way I handle multi-modules and manifests was erroneous. I had the default Activity's Manifest in library module only, but it should've been in both app modules.

Assuming librarymodule appmodule1 appmodule2

  1. Remove HomeActivity from librarymodule Manifest whatsoever.
  2. Add:
class AppModuleActivity1 : HomeActivity() to appmodule1
class AppModuleActivity2 : HomeActivity() to appmodule2
  1. To appmodule1 Manifest inside application tag, I added:
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
  1. Same about appmodule2 but change 2 for 1 in naming.

Call a function with argument list in python

To expand a little on the other answers:

In the line:

def wrapper(func, *args):

The * next to args means "take the rest of the parameters given and put them in a list called args".

In the line:


The * next to args here means "take this list called args and 'unwrap' it into the rest of the parameters.

So you can do the following:

def wrapper1(func, *args): # with star

def wrapper2(func, args): # without star

def func2(x, y, z):
    print x+y+z

wrapper1(func2, 1, 2, 3)
wrapper2(func2, [1, 2, 3])

In wrapper2, the list is passed explicitly, but in both wrappers args contains the list [1,2,3].

How do I test a private function or a class that has private methods, fields or inner classes?

For Java I'd use reflection, since I don't like the idea of changing the access to a package on the declared method just for the sake of testing. However, I usually just test the public methods which should also ensure the private methods are working correctly.

you can't use reflection to get private methods from outside the owner class, the private modifier affects reflection also

This is not true. You most certainly can, as mentioned in Cem Catikkas's answer.

Convert a date format in epoch

  String dateTime="15-3-2019 09:50 AM" //time should be two digit like 08,09,10 
   DateTimeFormatter dtf  = DateTimeFormatter.ofPattern("dd-MM-yyyy hh:mm a");
        LocalDateTime zdt  = LocalDateTime.parse(dateTime,dtf);
        LocalDateTime now =;
        ZoneId zone = ZoneId.of("Asia/Kolkata");
        ZoneOffset zoneOffSet = zone.getRules().getOffset(now);
        long a= zdt.toInstant(zoneOffSet).toEpochMilli();

you can get zone id form this a link!

c - warning: implicit declaration of function ‘printf’

You need to include a declaration of the printf() function.

#include <stdio.h>

Leading zeros for Int in Swift


Xcode 9.0.1, swift 4.0



import Foundation

let array = [0,1,2,3,4,5,6,7,8]

Solution 1

extension Int {

    func getString(prefix: Int) -> String {
        return "\(prefix)\(self)"

    func getString(prefix: String) -> String {
        return "\(prefix)\(self)"

for item in array {
    print(item.getString(prefix: 0))

for item in array {
    print(item.getString(prefix: "0x"))

Solution 2

for item in array {
    print(String(repeatElement("0", count: 2)) + "\(item)")

Solution 3

extension String {

    func repeate(count: Int, string: String? = nil) -> String {

        if count > 1 {
            let repeatedString = string ?? self
            return repeatedString + repeate(count: count-1, string: repeatedString)
        return self

for item in array {
    print("0".repeate(count: 3) + "\(item)")

Best cross-browser method to capture CTRL+S with JQuery?

This should work (adapted from

var ctrl_down = false;
var ctrl_key = 17;
var s_key = 83;

$(document).keydown(function(e) {
    if (e.keyCode == ctrl_key) ctrl_down = true;
}).keyup(function(e) {
    if (e.keyCode == ctrl_key) ctrl_down = false;

$(document).keydown(function(e) {
    if (ctrl_down && (e.keyCode == s_key)) {
        alert('Ctrl-s pressed');
        // Your code
        return false;

How do I remove link underlining in my HTML email?

You should write something like this.

<a href="#" style="text-decoration:none;">BOOK NOW</a>

How to get element by class name?

you can use


suppose you have some elements and applied a class name 'test', so, you can get elements like as following

var tests = document.getElementsByClassName('test');

its returns an instance NodeList, or its superset: HTMLCollection (FF).

Read more

ASP.NET MVC Yes/No Radio Buttons with Strongly Bound Model MVC

Here is a more complete example using a fieldset for accessibility reasons and specifying the first button as the default. Without a fieldset, what the radio buttons are for as a whole can not be programmatically determined.


public class MyModel
    public bool IsMarried { get; set; }



    @Html.RadioButtonFor(e => e.IsMarried, true, new { id = "married-true" })
    @Html.Label("married-true", "Yes")

    @Html.RadioButtonFor(e => e.IsMarried, false, new { id = "married-false" })
    @Html.Label("married-false", "No")

You can add a @checked argument to the anonymous object to set the radio button as the default:

new { id = "married-true", @checked = 'checked' }

Note that you can bind to a string by replacing true and false with the string values.

How can I wait In Node.js (JavaScript)? l need to pause for a period of time

If you want to "code golf" you can make a shorter version of some of the other answers here:

const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));

But really the ideal answer in my opinion is to use Node's util library and its promisify function, which is designed for exactly this sort of thing (making promise-based versions of previously existing non-promise-based stuff):

const util = require('util');
const sleep = util.promisify(setTimeout);

In either case you can then pause simply by using await to call your sleep function:

await sleep(1000); // sleep for 1s/1000ms

Byte Array and Int conversion in Java

I found a simple way in which is in the []

long newLong = Longs.fromByteArray(oldLongByteArray);
int newInt = Ints.fromByteArray(oldIntByteArray);

Have a nice try :)

How to enable cross-origin resource sharing (CORS) in the express.js framework on node.js

Try to this cors npm modules.

var cors = require('cors')

var app = express()

This module provides many features to fine tune cors setting such as domain whitelisting, enabling cors for specific apis etc.

IF a == true OR b == true statement

Comparison expressions should each be in their own brackets:

{% if (a == 'foo') or (b == 'bar') %}
{% endif %}

Alternative if you are inspecting a single variable and a number of possible values:

{% if a in ['foo', 'bar', 'qux'] %}
{% endif %}

How to check whether a string contains a substring in Ruby

Ternary way

my_string.include?('ahr') ? (puts 'String includes ahr') : (puts 'String does not include ahr')


puts (my_string.include?('ahr') ? 'String includes ahr' : 'String not includes ahr')

How to set default value to all keys of a dict object in python?

defaultdict can do something like that for you.


>>> from collections import defaultdict
>>> d = defaultdict(list)
>>> d
defaultdict(<class 'list'>, {})
>>> d['new'].append(10)
>>> d
defaultdict(<class 'list'>, {'new': [10]})

What do I need to do to get Internet Explorer 8 to accept a self signed certificate?

What were you doing before? For self-signed certificates, I would normally install the certificate locally on the client system.

You may be able to use Group Policy to push a certificate to every system.

How could I use requests in asyncio?

Requests does not currently support asyncio and there are no plans to provide such support. It's likely that you could implement a custom "Transport Adapter" (as discussed here) that knows how to use asyncio.

If I find myself with some time it's something I might actually look into, but I can't promise anything.

How do I disable fail_on_empty_beans in Jackson?

In my case, I missed to write @JsonProperty annotation in one of the fields which was causing this error.

Using different Web.config in development and production environment

I'd like to know, too. This helps isolate the problem for me

<connectionStrings configSource="connectionStrings.config"/>

I then keep a connectionStrings.config as well as a "{host} connectionStrings.config". It's still a problem, but if you do this for sections that differ in the two environments, you can deploy and version the same web.config.

(And I don't use VS, btw.)

How to get all privileges back to the root user in MySQL?

This worked for me on Ubuntu:

Stop MySQL server:

/etc/init.d/mysql stop

Start MySQL from the commandline:


In another terminal enter mysql and issue:

grant all privileges on *.* to 'root'@'%' with grant option;

You may also want to add

grant all privileges on *.* to 'root'@'localhost' with grant option;

and optionally use a password as well.

flush privileges;

and then exit your MySQL prompt and then kill the mysqld server running in the foreground. Restart with

/etc/init.d/mysql start  

How to Apply global font to whole HTML document

Try this:

    font-family:your font;
    font-size:your value;
    font-weight:your value;

node.js http 'get' request with query string parameters

If you don't want use external package , Just add the following function in your utilities :

var params=function(req){
  let q=req.url.split('?'),result={};
           try {
           } catch (e) {
  return result;

Then , in createServer call back , add attribute params to request object :

     req.params=params(req); // call the function above ;
       * http://mysite/add?name=Ahmed
     console.log( ; // display : "Ahmed"


How to set Spinner default value to null?

I assume that you want to have a Spinner with first empty invisible item (that is a strange feature of Spinner that cannot show a list without selecting an item). You should add a class that will contain data:

data class YourData(val id: Int, val name: String?)

This is the adapter.

class YourAdapter(
    context: Context,
    private val textViewResourceId: Int,
    private var items: ArrayList<YourData>
) : ArrayAdapter<YourData>(context, textViewResourceId, items) {

    private var inflater: LayoutInflater = context.getSystemService(
        Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater

    override fun getCount(): Int = items.size + 1

    override fun getItem(position: Int): YourData? =
        if (position == 0) YourData(0, "") else items[position - 1]

    override fun getItemId(position: Int): Long = position.toLong()

    override fun getView(position: Int, convertView: View?, parent: ViewGroup): View =
        if (position == 0) {
        } else {
            getTextView(convertView, parent, position - 1)

    override fun getDropDownView(position: Int, convertView: View?, parent: ViewGroup): View =
        getView(position, convertView, parent)

    private fun getFirstTextView(convertView: View?): View {
        // Just simple TextView as initial selection.
        var textView: TextView? = convertView as? TextView
        val holder: FirstViewHolder
        if (textView?.tag !is FirstViewHolder) {
            textView = TextView(context) // inflater.inflate(R.layout.your_text, parent, false) as TextView
            textView.height = 0 // Hide first item.
            holder = FirstViewHolder()
            holder.textView = textView
            textView.tag = holder
        return textView

    private fun getTextView(
        convertView: View?,
        parent: ViewGroup,
        position: Int
    ): TextView {
        var textView: TextView? = convertView as? TextView
        val holder: ViewHolder
        if (textView?.tag is ViewHolder) {
            holder = textView.tag as ViewHolder
        } else {
            textView = inflater.inflate(textViewResourceId, parent, false) as TextView
            holder = ViewHolder()
            holder.textView = textView
            textView.tag = holder
        holder.textView.text = items[position].name

        return textView

    private class FirstViewHolder {
        lateinit var textView: TextView

    private class ViewHolder {
        lateinit var textView: TextView

To create:

YourAdapter(context!!, R.layout.text_item, ArrayList())

To add items:

private fun fill(items: List<YourData>, adapter: YourAdapter) { {

When you load items to your Spinner with that fill() command, you should know, that indices are also incremented. So if you wish to select 3rd item, you should now select 4th: spinner?.setSelection(index + 1)

What causes imported Maven project in Eclipse to use Java 1.5 instead of Java 1.6 by default and how can I ensure it doesn't?

I wanted to add something to the answer already provided. maven-compiler-plugin by default will compile your project using Java 1.5 which is where m2e get's its information.

That's why you have to explicitly declare the maven-compiler-plugin in your project with something other then 1.5. Your effective pom.xml will implicitly use the default set in the maven-compiler-plugin pom.xml.

How to use the CancellationToken property?

You have to pass the CancellationToken to the Task, which will periodically monitors the token to see whether cancellation is requested.

// CancellationTokenSource provides the token and have authority to cancel the token
CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
CancellationToken token = cancellationTokenSource.Token;  

// Task need to be cancelled with CancellationToken 
Task task = Task.Run(async () => {     
  while(!token.IsCancellationRequested) {
      await Task.Delay(1000);
}, token);

Console.WriteLine("Press enter to stop the task"); 

In this case, the operation will end when cancellation is requested and the Task will have a RanToCompletion state. If you want to be acknowledged that your task has been cancelled, you have to use ThrowIfCancellationRequested to throw an OperationCanceledException exception.

Task task = Task.Run(async () =>             
    while (!token.IsCancellationRequested) {
         await Task.Delay(1000);                
}, token)
.ContinueWith(t =>
      t.Exception?.Handle(e => true);
      Console.WriteLine("You have canceled the task");
Console.WriteLine("Press enter to stop the task");                 

Hope this helps to understand better.

Error handling in C code

Here's a simple program to demonstrate the first 2 bullets of Nils Pipenbrinck's answer here.

His first 2 bullets are:

  • store all possible error-states in one typedef'ed enum and use it in your lib. Don't just return ints or even worse, mix ints or different enumerations with return-codes.

  • provide a function that converts errors into something human readable. Can be simple. Just error-enum in, const char* out.

Assume you have written a module named mymodule. First, in mymodule.h, you define your enum-based error codes, and you write some error strings which correspond to these codes. Here I am using an array of C strings (char *), which only works well if your first enum-based error code has value 0, and you don't manipulate the numbers thereafter. If you do use error code numbers with gaps or other starting values, you'll simply have to change from using a mapped C-string array (as I do below) to using a function which uses a switch statement or if / else if statements to map from enum error codes to printable C strings (which I don't demonstrate). The choice is yours.


/// @brief Error codes for library "mymodule"
typedef enum mymodule_error_e
    /// No error
    /// Invalid arguments (ex: NULL pointer where a valid pointer is required)

    /// Out of memory (RAM)

    /// Make up your error codes as you see fit

    // etc etc
    /// Total # of errors in this list (NOT AN ACTUAL ERROR CODE);
    /// NOTE: that for this to work, it assumes your first error code is value 0 and you let it naturally 
    /// increment from there, as is done above, without explicitly altering any error values above
} mymodule_error_t;

// Array of strings to map enum error types to printable strings
// - see important NOTE above!
const char* const MYMODULE_ERROR_STRS[] = 

// To get a printable error string
const char* mymodule_error_str(mymodule_error_t err);

// Other functions in mymodule
mymodule_error_t mymodule_func1(void);
mymodule_error_t mymodule_func2(void);
mymodule_error_t mymodule_func3(void);

mymodule.c contains my mapping function to map from enum error codes to printable C strings:


#include <stdio.h>

/// @brief      Function to get a printable string from an enum error type
/// @param[in]  err     a valid error code for this module
/// @return     A printable C string corresponding to the error code input above, or NULL if an invalid error code
///             was passed in
const char* mymodule_error_str(mymodule_error_t err)
    const char* err_str = NULL;

    // Ensure error codes are within the valid array index range
    if (err >= MYMODULE_ERROR_COUNT)
        goto done;

    err_str = MYMODULE_ERROR_STRS[err];

    return err_str;

// Let's just make some empty dummy functions to return some errors; fill these in as appropriate for your 
// library module

mymodule_error_t mymodule_func1(void)

mymodule_error_t mymodule_func2(void)

mymodule_error_t mymodule_func3(void)

main.c contains a test program to demonstrate calling some functions and printing some error codes from them:


#include <stdio.h>

int main()
    printf("Demonstration of enum-based error codes in C (or C++)\n");

    printf("err code from mymodule_func1() = %s\n", mymodule_error_str(mymodule_func1()));
    printf("err code from mymodule_func2() = %s\n", mymodule_error_str(mymodule_func2()));
    printf("err code from mymodule_func3() = %s\n", mymodule_error_str(mymodule_func3()));

    return 0;


Demonstration of enum-based error codes in C (or C++)
err code from mymodule_func1() = MYMODULE_ERROR_OK
err code from mymodule_func2() = MYMODULE_ERROR_INVARG
err code from mymodule_func3() = MYMODULE_ERROR_MYERROR


You can run this code yourself here:

Iterate over values of object

It's not a map. It's simply an Object.

Edit: below code is worse than OP's, as Amit pointed out in comments.

You can "iterate over the values" by actually iterating over the keys with:

var value;
Object.keys(map).forEach(function(key) {
    value = map[key];

How to add an item to a drop down list in ASP.NET?

Try following code;

DropDownList1.Items.Add(new ListItem(txt_box1.Text));

WebView showing ERR_CLEARTEXT_NOT_PERMITTED although site is HTTPS


Add the below line in your application tag:


As shown below:


UPDATE: If you have network security config such as: android:networkSecurityConfig="@xml/network_security_config"

No Need to set clear text traffic to true as shown above, instead use the below code:

<?xml version="1.0" encoding="utf-8"?>
    <domain-config cleartextTrafficPermitted="true">

    <base-config cleartextTrafficPermitted="false"/>

Set the cleartextTrafficPermitted to true

Hope it helps.

How to cherry-pick multiple commits

Actually, the simplest way to do it could be to:

  1. record the merge-base between the two branches: MERGE_BASE=$(git merge-base branch-a branch-b)
  2. fast-forward or rebase the older branch onto the newer branch
  3. rebase the resulting branch onto itself, starting at the merge base from step 1, and manually remove commits that are not desired:

    git rebase ${SAVED_MERGE_BASE} -i

    Alternatively, if there are only a few new commits, skip step 1, and simply use

    git rebase HEAD^^^^^^^ -i

    in the first step, using enough ^ to move past the merge-base.

You will see something like this in the interactive rebase:

pick 3139276 commit a
pick c1b421d commit b
pick 7204ee5 commit c
pick 6ae9419 commit d
pick 0152077 commit e
pick 2656623 commit f

Then remove lines b (and any others you want)

reducing number of plot ticks

The solution @raphael gave is straightforward and quite helpful.

Still, the displayed tick labels will not be values sampled from the original distribution but from the indexes of the array returned by np.linspace(ymin, ymax, N).

To display N values evenly spaced from your original tick labels, use the set_yticklabels() method. Here is a snippet for the y axis, with integer labels:

import numpy as np
import matplotlib.pyplot as plt

ax = plt.gca()

ymin, ymax = ax.get_ylim()
custom_ticks = np.linspace(ymin, ymax, N, dtype=int)

What's the -practical- difference between a Bare and non-Bare repository?

$ git help repository-layout

A Git repository comes in two different flavours:

  • a .git directory at the root of the working tree;
  • a .git directory that is a bare repository (i.e. without its own working tree), that is typically used for exchanging histories with others by pushing into it and fetching from it.

Spring Boot REST service exception handling

@RestControllerAdvice is a new feature of Spring Framework 4.3 to handle Exception with RestfulApi by a cross-cutting concern solution:

 package com.khan.vaquar.exception;

import javax.servlet.http.HttpServletRequest;

import org.owasp.esapi.errors.IntrusionException;
import org.owasp.esapi.errors.ValidationException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.MissingServletRequestParameterException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import org.springframework.web.servlet.NoHandlerFoundException;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.khan.vaquar.domain.ErrorResponse;

 * Handles exceptions raised through requests to spring controllers.
public class RestExceptionHandler {

    private static final String TOKEN_ID = "tokenId";

    private static final Logger log = LoggerFactory.getLogger(RestExceptionHandler.class);

     * Handles InstructionExceptions from the rest controller.
     * @param e IntrusionException
     * @return error response POJO
    @ExceptionHandler(value = IntrusionException.class)
    public ErrorResponse handleIntrusionException(HttpServletRequest request, IntrusionException e) {       
        log.warn(e.getLogMessage(), e);
        return this.handleValidationException(request, new ValidationException(e.getUserMessage(), e.getLogMessage()));

     * Handles ValidationExceptions from the rest controller.
     * @param e ValidationException
     * @return error response POJO
    @ExceptionHandler(value = ValidationException.class)
    public ErrorResponse handleValidationException(HttpServletRequest request, ValidationException e) {     
        String tokenId = request.getParameter(TOKEN_ID);, e);

        if (e.getUserMessage().contains("Token ID")) {
            tokenId = "<OMITTED>";

        return new ErrorResponse(   tokenId,

     * Handles JsonProcessingExceptions from the rest controller.
     * @param e JsonProcessingException
     * @return error response POJO
    @ExceptionHandler(value = JsonProcessingException.class)
    public ErrorResponse handleJsonProcessingException(HttpServletRequest request, JsonProcessingException e) {     
        String tokenId = request.getParameter(TOKEN_ID);, e);
        return new ErrorResponse(   tokenId,

     * Handles IllegalArgumentExceptions from the rest controller.
     * @param e IllegalArgumentException
     * @return error response POJO
    @ExceptionHandler(value = IllegalArgumentException.class)
    public ErrorResponse handleIllegalArgumentException(HttpServletRequest request, IllegalArgumentException e) {
        String tokenId = request.getParameter(TOKEN_ID);, e);
        return new ErrorResponse(   tokenId,

    @ExceptionHandler(value = UnsupportedOperationException.class)
    public ErrorResponse handleUnsupportedOperationException(HttpServletRequest request, UnsupportedOperationException e) {
        String tokenId = request.getParameter(TOKEN_ID);, e);
        return new ErrorResponse(   tokenId,

     * Handles MissingServletRequestParameterExceptions from the rest controller.
     * @param e MissingServletRequestParameterException
     * @return error response POJO
    @ExceptionHandler(value = MissingServletRequestParameterException.class)
    public ErrorResponse handleMissingServletRequestParameterException( HttpServletRequest request, 
                                                                        MissingServletRequestParameterException e) {
        String tokenId = request.getParameter(TOKEN_ID);, e);
        return new ErrorResponse(   tokenId,

     * Handles NoHandlerFoundExceptions from the rest controller.
     * @param e NoHandlerFoundException
     * @return error response POJO
    @ExceptionHandler(value = NoHandlerFoundException.class)
    public ErrorResponse handleNoHandlerFoundException(HttpServletRequest request, NoHandlerFoundException e) {
        String tokenId = request.getParameter(TOKEN_ID);, e);
        return new ErrorResponse(   tokenId,
                                    "The resource " + e.getRequestURL() + " is unavailable");

     * Handles all remaining exceptions from the rest controller.
     * This acts as a catch-all for any exceptions not handled by previous exception handlers.
     * @param e Exception
     * @return error response POJO
    @ExceptionHandler(value = Exception.class)
    public ErrorResponse handleException(HttpServletRequest request, Exception e) {
        String tokenId = request.getParameter(TOKEN_ID);
        log.error(e.getMessage(), e);
        return new ErrorResponse(   tokenId,
                                    "An internal error occurred");


Get month name from number

This is not so helpful if you need to just know the month name for a given number (1 - 12), as the current day doesn't matter.




are more useful here.

Here is an example:

import calendar

for month_idx in range(1, 13):
    print (calendar.month_name[month_idx])
    print (calendar.month_abbr[month_idx])
    print ("")

Sample output:





Android studio takes too much memory

I have Android Studio 2.1.1 Bro use genymotion emulator It Faster If Use Android Marshmallow. And My Ram Is 4gb.And Install Plugin for genymotion in Android Studio.You Will see good result in instead of wasting time start android emualtor it will take 5 min.genymotion 10 to 20 second speed and faster so I recommended to you use genymotion.

How to autoplay HTML5 mp4 video on Android?

I simplified the Javascript to trigger the video to start.

 var bg = document.getElementById ("bg"); _x000D_
 function playbg() {_x000D_; _x000D_
<video id="bg" style="min-width:100%; min-height:100%;"  playsinline autoplay loop muted onload="playbg(); "><source src="Files/snow.mp4" type="video/mp4"></video>_x000D_

*"Files/snow.mp4" is just sample url

WARNING: API 'variant.getJavaCompile()' is obsolete and has been replaced with 'variant.getJavaCompileProvider()'

In my case, it was caused from gms services 4.3.0. So i had to change it to:

I have found this by running:

gradlew sync -Pandroid.debug.obsoleteApi=true

in terminal. Go to view -> tool windows -> Terminal in Android Studio.

Where is Java's Array indexOf?

For primitives, if you want to avoid boxing, Guava has helpers for primitive arrays e.g. Ints.indexOf(int[] array, int target)

Android Device Chooser -- device not showing up

In galaxy note 3 you need to enable the developer option. Access the "About Device" and click on the Build number multiple time until a message appear which telling you that the developer option has been enabled. Go back to general and there your go..the developer option has been enabled and select USB debugging option. This is for Galaxy note 3 N9005 Andriod 4.3.

How to remove html special chars?

Either decode them using html_entity_decode or remove them using preg_replace:

$Content = preg_replace("/&#?[a-z0-9]+;/i","",$Content); 

(From here)

EDIT: Alternative according to Jacco's comment

might be nice to replace the '+' with {2,8} or something. This will limit the chance of replacing entire sentences when an unencoded '&' is present.

$Content = preg_replace("/&#?[a-z0-9]{2,8};/i","",$Content); 

How to get the size of a range in Excel

The overall dimensions of a range are in its Width and Height properties.

Dim r As Range
Set r = ActiveSheet.Range("A4:H12")

Debug.Print r.Width
Debug.Print r.Height

Xampp Access Forbidden php

The only solution that worked for me after spending hours researching online

sudo chmod -R 0777 /opt/lampp/htdocs/projectname

Debugging iframes with Chrome developer tools

When the iFrame points to your site like this:

    <script type="text/javascript" src="/jquery.js"></script>
    <iframe id="my_frame" src="/wherev"></iframe>

You can access iFrame DOM through this kind of thing.

var iframeBody = $(window.my_frame.document.getElementsByTagName("body")[0]);
iframeBody.append($("<h1/>").html("Hello world!"));

Column order manipulation using col-lg-push and col-lg-pull in Twitter Bootstrap 3

This answer is in three parts, see below for the official release (v3 and v4)

I couldn't even find the col-lg-push-x or pull classes in the original files for RC1 i downloaded, so check your bootstrap.css file. hopefully this is something they will sort out in RC2.

anyways, the col-push-* and pull classes did exist and this will suit your needs. Here is a demo

<div class="row">
    <div class="col-sm-5 col-push-5">
        Content B
    <div class="col-sm-5 col-pull-5">
        Content A
    <div class="col-sm-2">
        Content C


Also see This blog post on the subject

  • col-vp-push-x = push the column to the right by x number of columns, starting from where the column would normally render -> position: relative, on a vp or larger view-port.

  • col-vp-pull-x = pull the column to the left by x number of columns, starting from where the column would normally render -> position: relative, on a vp or larger view-port.

    vp = xs, sm, md, or lg

    x = 1 thru 12

I think what messes most people up, is that you need to change the order of the columns in your HTML markup (in the example below, B comes before A), and that it only does the pushing or pulling on view-ports that are greater than or equal to what was specified. i.e. col-sm-push-5 will only push 5 columns on sm view-ports or greater. This is because Bootstrap is a "mobile first" framework, so your HTML should reflect the mobile version of your site. The Pushing and Pulling are then done on the larger screens.

  • (Desktop) Larger view-ports get pushed and pulled.
  • (Mobile) Smaller view-ports render in normal order.


<div class="row">
    <div class="col-sm-5 col-sm-push-5">
        Content B
    <div class="col-sm-5 col-sm-pull-5">
        Content A
    <div class="col-sm-2">
        Content C

View-port >= sm


View-port < sm



With v4 comes flexbox and other changes to the grid system and the push\pull classes have been removed in favor of using flexbox ordering.

  • Use .order-* classes to control visual order (where * = 1 thru 12)
  • This can also be grid tier specific .order-md-*
  • Also .order-first (-1) and .order-last (13) avalable

<div class="row">_x000D_
  <div class="col order-2">1st yet 2nd</div>_x000D_
  <div class="col order-1">2nd yet 1st</div>_x000D_

CSS float right not working correctly

Verry Easy, change order of element:


<div style="">

    My Text

    <button type="button" style="float: right; margin:5px;">
       My Button


Change to:

<div style=""> 

    <button type="button" style="float: right; margin:5px;">
       My Button

   My Text


How do I create a WPF Rounded Corner container?

I know that this isn't an answer to the initial question ... but you often want to clip the inner content of that rounded corner border you just created.

Chris Cavanagh has come up with an excellent way to do just this.

I have tried a couple different approaches to this ... and I think this one rocks.

Here is the xaml below:

    <!-- Rounded yellow border -->
            <!-- Rounded mask (stretches to fill Grid) -->

            <!-- Main content container -->
                <!-- Use a VisualBrush of 'mask' as the opacity mask -->
                    <VisualBrush Visual="{Binding ElementName=mask}"/>

                <!-- Any content -->
                <Image Source=""/>

Are there any SHA-256 javascript implementations that are generally considered trustworthy?

OUTDATED: Many modern browsers now have first-class support for crypto operations. See Vitaly Zdanevich's answer below.

The Stanford JS Crypto Library contains an implementation of SHA-256. While crypto in JS isn't really as well-vetted an endeavor as other implementation platforms, this one is at least partially developed by, and to a certain extent sponsored by, Dan Boneh, who is a well-established and trusted name in cryptography, and means that the project has some oversight by someone who actually knows what he's doing. The project is also supported by the NSF.

It's worth pointing out, however...
... that if you hash the password client-side before submitting it, then the hash is the password, and the original password becomes irrelevant. An attacker needs only to intercept the hash in order to impersonate the user, and if that hash is stored unmodified on the server, then the server is storing the true password (the hash) in plain-text.

So your security is now worse because you decided add your own improvements to what was previously a trusted scheme.

Is Google Play Store supported in avd emulators?

Easiest way: You should create a new emulator, before opening it for the first time follow these 3 easy steps:

1- go to C:\Users[user].android\avd[your virtual device folder] open "config.ini" with text editor like notepad

2- change

"PlayStore.enabled=false" to "PlayStore.enabled=true"

3- change

mage.sysdir.1 = system-images\android-30\google_apis\x86\


image.sysdir.1 = system-images\android-30\google_apis_playstore\x86\

Android Facebook integration with invalid key hash

According Facebook Login for Android, you must provide the key hash value. In order to obtain it, you will need the key used to sign your application.

keytool \
    -exportcert \
    -alias YourKeyAlias \
    -storepass YourStoreKeyPassword \
    -keystore PathToYourKeyStoreFile | openssl sha1 -binary | openssl base64

default web page width - 1024px or 980px?

This is a bit of an open ended question since screen sizes are changing all the time and what might have been correct two years ago would likely be out of date now.

I use Twitter Bootstrap 3 at present and it uses a fluid grid system designed to work at sizes ranging from mobile/very small all the way up to the huge wide screen monitors that are now available.

Currently the upper default in BS3 is 1200px which translates to a container width of 1144px after taking account of margins and padding of the grids elements.

In my experience, modern designers are working to a width of around 1366px for desktop. All recent designs I've been given to implement have been 1366px.

Note also that you can customise the BS3 grid quite heavily. For example we will use a 32 column grid with 4px gutter in our sites/designs going forwards.

Ultimately the decision on page width needs to be made based on your website analytics and the screen sizes that your visitors typically use.

CSV new-line character seen in unquoted field error

I know this has been answered for quite some time but not solve my problem. I am using DictReader and StringIO for my csv reading due to some other complications. I was able to solve problem more simply by replacing delimiters explicitly:

with urllib.request.urlopen(q) as response:
    raw_data =
    encoding ='utf8') 
    data = raw_data.decode(encoding)
    if '\r\n' not in data:
        # proably a windows delimited thing...try to update it
        data = data.replace('\r', '\r\n')

Might not be reasonable for enormous CSV files, but worked well for my use case.

how to call a onclick function in <a> tag?

You should read up on the onclick html attribute and the documentation. Below is what you want.

<a href='#' onclick='"", "myWin", "scrollbars=yes,width=400,height=650"); return false;'>1</a>


What does Python's socket.recv() return for non-blocking sockets if no data is received until a timeout occurs?

In the case of a non blocking socket that has no data available, recv will throw the socket.error exception and the value of the exception will have the errno of either EAGAIN or EWOULDBLOCK. Example:

import sys
import socket
import fcntl, os
import errno
from time import sleep

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
fcntl.fcntl(s, fcntl.F_SETFL, os.O_NONBLOCK)

while True:
        msg = s.recv(4096)
    except socket.error, e:
        err = e.args[0]
        if err == errno.EAGAIN or err == errno.EWOULDBLOCK:
            print 'No data available'
            # a "real" error occurred
            print e
        # got a message, do something :)

The situation is a little different in the case where you've enabled non-blocking behavior via a time out with socket.settimeout(n) or socket.setblocking(False). In this case a socket.error is stil raised, but in the case of a time out, the accompanying value of the exception is always a string set to 'timed out'. So, to handle this case you can do:

import sys
import socket
from time import sleep

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

while True:
        msg = s.recv(4096)
    except socket.timeout, e:
        err = e.args[0]
        # this next if/else is a bit redundant, but illustrates how the
        # timeout exception is setup
        if err == 'timed out':
            print 'recv timed out, retry later'
            print e
    except socket.error, e:
        # Something else happened, handle error, exit, etc.
        print e
        if len(msg) == 0:
            print 'orderly shutdown on server end'
            # got a message do something :)

As indicated in the comments, this is also a more portable solution since it doesn't depend on OS specific functionality to put the socket into non-blockng mode.

See recv(2) and python socket for more details.