Programs & Examples On #Key

A unique identifier used to retrieve a paired value. Used in hashtables and databases.

How to check if multiple array keys exists

$myArray = array('key1' => '', 'key2' => '');
$keys = array('key1', 'key2', 'key3');
$keyExists = count(array_intersect($keys, array_keys($myArray)));

Will return true, because there are keys from $keys array in $myArray

SSH Key: “Permissions 0644 for '' are too open.” on mac

Key should be readable by the logged in user.

Try this:

chmod 400 ~/.ssh/Key file
chmod 400 ~/.ssh/

Python dictionary: Get list of values for list of keys

A little speed comparison:

Python 2.7.11 |Anaconda 2.4.1 (64-bit)| (default, Dec  7 2015, 14:10:42) [MSC v.1500 64 bit (AMD64)] on win32
In[1]: l = [0,1,2,3,2,3,1,2,0]
In[2]: m = {0:10, 1:11, 2:12, 3:13}
In[3]: %timeit [m[_] for _ in l]  # list comprehension
1000000 loops, best of 3: 762 ns per loop
In[4]: %timeit map(lambda _: m[_], l)  # using 'map'
1000000 loops, best of 3: 1.66 µs per loop
In[5]: %timeit list(m[_] for _ in l)  # a generator expression passed to a list constructor.
1000000 loops, best of 3: 1.65 µs per loop
In[6]: %timeit map(m.__getitem__, l)
The slowest run took 4.01 times longer than the fastest. This could mean that an intermediate result is being cached 
1000000 loops, best of 3: 853 ns per loop
In[7]: %timeit map(m.get, l)
1000000 loops, best of 3: 908 ns per loop
In[33]: from operator import itemgetter
In[34]: %timeit list(itemgetter(*l)(m))
The slowest run took 9.26 times longer than the fastest. This could mean that an intermediate result is being cached 
1000000 loops, best of 3: 739 ns per loop

So list comprehension and itemgetter are the fastest ways to do this.

UPDATE: For large random lists and maps I had a bit different results:

Python 2.7.11 |Anaconda 2.4.1 (64-bit)| (default, Dec  7 2015, 14:10:42) [MSC v.1500 64 bit (AMD64)] on win32
In[2]: import numpy.random as nprnd
l = nprnd.randint(1000, size=10000)
m = dict([(_, nprnd.rand()) for _ in range(1000)])
from operator import itemgetter
import operator
f = operator.itemgetter(*l)
%timeit f(m)
%timeit list(itemgetter(*l)(m))
%timeit [m[_] for _ in l]  # list comprehension
%timeit map(m.__getitem__, l)
%timeit list(m[_] for _ in l)  # a generator expression passed to a list constructor.
%timeit map(m.get, l)
%timeit map(lambda _: m[_], l)
1000 loops, best of 3: 1.14 ms per loop
1000 loops, best of 3: 1.68 ms per loop
100 loops, best of 3: 2 ms per loop
100 loops, best of 3: 2.05 ms per loop
100 loops, best of 3: 2.19 ms per loop
100 loops, best of 3: 2.53 ms per loop
100 loops, best of 3: 2.9 ms per loop

So in this case the clear winner is f = operator.itemgetter(*l); f(m), and clear outsider: map(lambda _: m[_], l).

UPDATE for Python 3.6.4:

import numpy.random as nprnd
l = nprnd.randint(1000, size=10000)
m = dict([(_, nprnd.rand()) for _ in range(1000)])
from operator import itemgetter
import operator
f = operator.itemgetter(*l)
%timeit f(m)
%timeit list(itemgetter(*l)(m))
%timeit [m[_] for _ in l]  # list comprehension
%timeit list(map(m.__getitem__, l))
%timeit list(m[_] for _ in l)  # a generator expression passed to a list constructor.
%timeit list(map(m.get, l))
%timeit list(map(lambda _: m[_], l)
1.66 ms ± 74.2 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)
2.1 ms ± 93.2 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)
2.58 ms ± 88.8 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)
2.36 ms ± 60.7 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)
2.98 ms ± 142 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)
2.7 ms ± 284 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)
3.14 ms ± 62.6 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)

So, results for Python 3.6.4 is almost the same.

How do I check if the user is pressing a key?

Try this:

import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.JFrame;
import javax.swing.JTextField;

public class Main {

    public static void main(String[] argv) throws Exception {

    JTextField textField = new JTextField();

    textField.addKeyListener(new Keychecker());

    JFrame jframe = new JFrame();


    jframe.setSize(400, 350);



class Keychecker extends KeyAdapter {

    public void keyPressed(KeyEvent event) {

        char ch = event.getKeyChar();




Return None if Dictionary key is not available

I usually use a defaultdict for situations like this. You supply a factory method that takes no arguments and creates a value when it sees a new key. It's more useful when you want to return something like an empty list on new keys (see the examples).

from collections import defaultdict
d = defaultdict(lambda: None)
print d['new_key']  # prints 'None'

Which characters are valid/invalid in a JSON key name?

Unicode codepoints U+D800 to U+DFFF must be avoided: they are invalid in Unicode because they are reserved for UTF-16 surrogate pairs. Some JSON encoders/decoders will replace them with U+FFFD. See for example how the Go language and its JSON library deals with them.

So avoid "\uD800" to "\uDFFF" alone (not in surrogate pairs).

PHP: How to use array_filter() to filter array keys?

With this function you can filter a multidimensional array

function filter_array_keys($array,$filter_keys=array()){

    //This first loop will loop until the count var is stable//
        //This loop will loop thru the child element list//
        $keys = array_keys($l[$r]);

            $object = &$l[$r][$keys[$z]];

                $object=array_filter($object,function($el) use(&$i,$keys_on_array,$filter_keys){
                    $key = $keys_on_array[$i];

                    if(in_array($key,$filter_keys) || is_int($key))return false;                
                    return true;                        

                $l[] = &$l[$r][$keys[$z]];

    return $l[0];


How to get array keys in Javascript?

for (var i = 0; i < widthRange.length; ++i) {
  if (widthRange[i] != null) {
    // do something

You can't really get just the keys you've set because that's not how an Array works. Once you set element 46, you also have 0 through 45 set too (though they're null).

You could always have two arrays:

var widthRange = [], widths = [], newVal = function(n) {
  return n;
widthRange[newVal(26)] = { whatever: "hello there" };

for (var i = 0; i < widths.length; ++i) {

edit well it may be that I'm all wet here ...

How to get key names from JSON using jq

To print keys on one line as csv:

echo '{"b":"2","a":"1"}' | jq -r 'keys | [ .[] | tostring ] | @csv'



For csv completeness ... to print values on one line as csv:

echo '{"b":"2","a":"1"}' | jq -rS . | jq -r '. | [ .[] | tostring ] | @csv'



How to update a value, given a key in a hashmap?

@Matthew's solution is the simplest and will perform well enough in most cases.

If you need high performance, AtomicInteger is a better solution ala @BalusC.

However, a faster solution (provided thread safety is not an issue) is to use TObjectIntHashMap which provides a increment(key) method and uses primitives and less objects than creating AtomicIntegers. e.g.

TObjectIntHashMap<String> map = new TObjectIntHashMap<String>()

Get the new record primary key ID from MySQL insert query?

Here what you are looking for !!!


This is the best alternative of SCOPE_IDENTITY() function being used in SQL Server.

You also need to keep in mind that this will only work if Last_INSERT_ID() is fired following by your Insert query. That is the query returns the id inserted in the schema. You can not get specific table's last inserted id.

For more details please go through the link The equivalent of SQLServer function SCOPE_IDENTITY() in mySQL?

Sort rows in data.table in decreasing order on string key `order(-x,v)` gives error on data.table 1.9.4 or earlier

DT[order(-x)] works as expected. I have data.table version 1.9.4. Maybe this was fixed in a recent version.
Also, I suggest the setorder(DT, -x) syntax in keeping with the set* commands like setnames, setkey

Python: Tuples/dictionaries as keys, select, sort

With keys as tuples, you just filter the keys with given second component and sort it:

blue_fruit = sorted([k for k in data.keys() if k[1] == 'blue'])
for k in blue_fruit:
  print k[0], data[k] # prints 'banana 24', etc

Sorting works because tuples have natural ordering if their components have natural ordering.

With keys as rather full-fledged objects, you just filter by k.color == 'blue'.

You can't really use dicts as keys, but you can create a simplest class like class Foo(object): pass and add any attributes to it on the fly:

k = Foo()
k.color = 'blue'

These instances can serve as dict keys, but beware their mutability!

Initializing a dictionary in python with a key value and no corresponding values

Based on the clarifying comment by @user2989027, I think a good solution is the following:

definition = ['apple', 'ball']
data = {'orange':1, 'pear':2, 'apple':3, 'ball':4}
my_data = {}
for k in definition:
  except KeyError:
print my_data

I tried not to do anything fancy here. I setup my data and an empty dictionary. I then loop through a list of strings that represent potential keys in my data dictionary. I copy each value from data to my_data, but consider the case where data may not have the key that I want.

How to print all key and values from HashMap in Android?

you can use this code:

for (Object variableName: mapName.keySet()){
    variableKey += variableName + "\n";
    variableValue += mapName.get(variableName) + "\n";
System.out.println(variableKey + variableValue);

this code will make sure that all the keys are stored in a variable and then printed!

There are no primary or candidate keys in the referenced table that match the referencing column list in the foreign key

Foreign keys work by joining a column to a unique key in another table, and that unique key must be defined as some form of unique index, be it the primary key, or some other unique index.

At the moment, the only unique index you have is a compound one on ISBN, Title which is your primary key.

There are a number of options open to you, depending on exactly what BookTitle holds and the relationship of the data within it.

I would hazard a guess that the ISBN is unique for each row in BookTitle. ON the assumption this is the case, then change your primary key to be only on ISBN, and change BookCopy so that instead of Title you have ISBN and join on that.

If you need to keep your primary key as ISBN, Title then you either need to store the ISBN in BookCopy as well as the Title, and foreign key on both columns, OR you need to create a unique index on BookTitle(Title) as a distinct index.

More generally, you need to make sure that the column or columns you have in your REFERENCES clause match exactly a unique index in the parent table: in your case it fails because you do not have a single unique index on Title alone.

iterating through Enumeration of hastable keys throws NoSuchElementException error

You call nextElement() twice in your loop. This call moves the enumeration pointer forward. You should modify your code like the following:

while (e.hasMoreElements()) {
    String param = e.nextElement();

Map<String, String>, how to print both the "key string" and "value string" together

There are various ways to achieve this. Here are three.

    Map<String, String> map = new HashMap<String, String>();
    map.put("key1", "value1");
    map.put("key2", "value2");
    map.put("key3", "value3");

    System.out.println("using entrySet and toString");
    for (Entry<String, String> entry : map.entrySet()) {

    System.out.println("using entrySet and manual string creation");
    for (Entry<String, String> entry : map.entrySet()) {
        System.out.println(entry.getKey() + "=" + entry.getValue());

    System.out.println("using keySet");
    for (String key : map.keySet()) {
        System.out.println(key + "=" + map.get(key));


using entrySet and toString

using entrySet and manual string creation

using keySet

How to find array / dictionary value using key?

It's as simple as this :


Differences between key, superkey, minimal superkey, candidate key and primary key

I have always found it difficult to remember all the keys; so I keep the below notes handy, hope they help someone! Let me know if it can be improved.

  • Key: An attribute or combination of attributes that uniquely identify an entity/record in a relational table.

  • PK: A single key that is unique and not-null. It is one of the candidate keys.

  • Foreign Key: FK is a key in one table (child) that uniquely identifies a row of another table (parent). A FK is not-unique in the child table. It is a candidate key in the parent table. Referential integrity is maintained as the value in FK is present as a value in PK in parent table else it is NULL.

  • Unique Key: A unique key that may or may not be NULL

  • Natural key: PK in OLTP. It may be a PK in OLAP.

  • Surrogate Key: It is the Surrogate PK in OLAP acting as the substitute of the PK in OLTP. Artificial key generated internally in OLAP.

  • Composite Key: PK made up of multiple attributes

  • SuperKey: A key that can be uniquely used to identify a database record, that may contain extra attributes that are not necessary to uniquely identify records.

  • Candidate Key: A candidate key can be uniquely used to identify a database record without any extraneous data. They are Not Null and unique. It is a minimal super-key.

  • Alternate Key: A candidate key that is not the primary key is called an alternate key.

  • Candidate Key/s with Extraneous data: Consider that can be used to identify a record in the Employee table but candidate key alone is sufficient for this task. So becomes the extraneous data.

Note that the PK, Foreign Key, Unique Key, Natural key, Surrogate Key, Composite Key are defined as Database objects; where the Natural key is a PK in the OLTP and could be a PK in the target OLAP. For the rest of the keys, it's up to the DB designer/architect to decide whether unique/not-null/referential integrity constraints need to enforced or not.

Below I have tried to use set theory to simplify the representation of the membership of the keys w.r.t. each other.

key = { All of the below keys   }
PK  = { PK  }
Foreign Key = { Key with Not Null constraint    }
Unique Key  = { {Candidate Key/s}, {attributes containing NULL} }
Natural key = { PK  }
Surrogate Key   = { PK  }
Composite Key   = { PK  }
Super Key   = { {Candidate Key/s}, {Candidate Key/s with Extraneous data}   }
Candidate Key   = { PK, {Alternate Key/s}   }
Alternate Key   = { {Candidate Keys} - PK   }
Candidate Key/s with Extraneous data    = {     }

I have summarized it below:

Database Keys

Notes: an-overview-of-the-database-keys-primary-key-composite-key-surrogate-key-et-al

php: how to get associative array key from numeric index?

If it is the first element, i.e. $array[0], you can try:

echo key($array);

If it is the second element, i.e. $array[1], you can try:

echo key($array);

I think this method is should be used when required element is the first, second or at most third element of the array. For other cases, loops should be used otherwise code readability decreases.

How can I get dictionary key as variable directly in Python (not by searching from value)?

You could simply use * which unpacks the dictionary keys. Example:

d = {'x': 1, 'y': 2}
t = (*d,)
print(t) # ('x', 'y')

How to echo out the values of this array?

you need the set key and value in foreach loop for that:

foreach($item AS $key -> $value) {
echo $value;

this should do the trick :)

What is the use of adding a null key or value to a HashMap in Java?

One example of usage for null values is when using a HashMap as a cache for results of an expensive operation (such as a call to an external web service) which may return null.

Putting a null value in the map then allows you to distinguish between the case where the operation has not been performed for a given key (cache.containsKey(someKey) returns false), and where the operation has been performed but returned a null value (cache.containsKey(someKey) returns true, cache.get(someKey) returns null).

Without null values, you would have to either put some special value in the cache to indicate a null response, or simply not cache that response at all and perform the operation every time.

How do I make a composite key with SQL Server Management Studio?

enter image description here

  1. Open the design table tab
  2. Highlight your two INT fields (Ctrl/Shift+click on the grey blocks in the very first column)
  3. Right click -> Set primary key

Differences between INDEX, PRIMARY, UNIQUE, FULLTEXT in MySQL?


  • KEY or INDEX refers to a normal non-unique index. Non-distinct values for the index are allowed, so the index may contain rows with identical values in all columns of the index. These indexes don't enforce any restraints on your data so they are used only for access - for quickly reaching certain ranges of records without scanning all records.

  • UNIQUE refers to an index where all rows of the index must be unique. That is, the same row may not have identical non-NULL values for all columns in this index as another row. As well as being used to quickly reach certain record ranges, UNIQUE indexes can be used to enforce restraints on data, because the database system does not allow the distinct values rule to be broken when inserting or updating data.

    Your database system may allow a UNIQUE index to be applied to columns which allow NULL values, in which case two rows are allowed to be identical if they both contain a NULL value (the rationale here is that NULL is considered not equal to itself). Depending on your application, however, you may find this undesirable: if you wish to prevent this, you should disallow NULL values in the relevant columns.

  • PRIMARY acts exactly like a UNIQUE index, except that it is always named 'PRIMARY', and there may be only one on a table (and there should always be one; though some database systems don't enforce this). A PRIMARY index is intended as a primary means to uniquely identify any row in the table, so unlike UNIQUE it should not be used on any columns which allow NULL values. Your PRIMARY index should be on the smallest number of columns that are sufficient to uniquely identify a row. Often, this is just one column containing a unique auto-incremented number, but if there is anything else that can uniquely identify a row, such as "countrycode" in a list of countries, you can use that instead.

    Some database systems (such as MySQL's InnoDB) will store a table's records on disk in the order in which they appear in the PRIMARY index.

  • FULLTEXT indexes are different from all of the above, and their behaviour differs significantly between database systems. FULLTEXT indexes are only useful for full text searches done with the MATCH() / AGAINST() clause, unlike the above three - which are typically implemented internally using b-trees (allowing for selecting, sorting or ranges starting from left most column) or hash tables (allowing for selection starting from left most column).

    Where the other index types are general-purpose, a FULLTEXT index is specialised, in that it serves a narrow purpose: it's only used for a "full text search" feature.


  • All of these indexes may have more than one column in them.

  • With the exception of FULLTEXT, the column order is significant: for the index to be useful in a query, the query must use columns from the index starting from the left - it can't use just the second, third or fourth part of an index, unless it is also using the previous columns in the index to match static values. (For a FULLTEXT index to be useful to a query, the query must use all columns of the index.)

Java AES and using my own Key

This wll work.

public class CryptoUtils {

    private  final String TRANSFORMATION = "AES";
    private  final String encodekey = "1234543444555666";
    public  String encrypt(String inputFile)
            throws CryptoException {
        return doEncrypt(encodekey, inputFile);

    public  String decrypt(String input)
            throws CryptoException {
    // return  doCrypto(Cipher.DECRYPT_MODE, key, inputFile);
    return doDecrypt(encodekey,input);

    private  String doEncrypt(String encodekey, String inputStr)   throws CryptoException {
        try {

            Cipher cipher = Cipher.getInstance(TRANSFORMATION);

            byte[] key = encodekey.getBytes("UTF-8");
            MessageDigest sha = MessageDigest.getInstance("SHA-1");
            key = sha.digest(key);
            key = Arrays.copyOf(key, 16); // use only first 128 bit

            SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES");

            cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);

            byte[] inputBytes = inputStr.getBytes();     
            byte[] outputBytes = cipher.doFinal(inputBytes);

            return Base64Utils.encodeToString(outputBytes);

        } catch (NoSuchPaddingException | NoSuchAlgorithmException
                | InvalidKeyException | BadPaddingException
                | IllegalBlockSizeException | IOException ex) {
            throw new CryptoException("Error encrypting/decrypting file", ex);

    public  String doDecrypt(String encodekey,String encrptedStr) { 
          try {     

              Cipher dcipher = Cipher.getInstance(TRANSFORMATION);
              dcipher = Cipher.getInstance("AES");
              byte[] key = encodekey.getBytes("UTF-8");
              MessageDigest sha = MessageDigest.getInstance("SHA-1");
              key = sha.digest(key);
              key = Arrays.copyOf(key, 16); // use only first 128 bit

              SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES");

              dcipher.init(Cipher.DECRYPT_MODE, secretKeySpec);
            // decode with base64 to get bytes

              byte[] dec = Base64Utils.decode(encrptedStr.getBytes());  
              byte[] utf8 = dcipher.doFinal(dec);

              // create new string based on the specified charset
              return new String(utf8, "UTF8");

          } catch (Exception e) {


      return null;

How can I see if a Perl hash already has a certain key?

I would counsel against using if ($hash{$key}) since it will not do what you expect if the key exists but its value is zero or empty.

How do I check if a Key is pressed on C++

As mentioned by others there's no cross platform way to do this, but on Windows you can do it like this:

The Code below checks if the key 'A' is down.

if(GetKeyState('A') & 0x8000/*Check if high-order bit is set (1 << 15)*/)
    // Do stuff

In case of shift or similar you will need to pass one of these:

if(GetKeyState(VK_SHIFT) & 0x8000)
    // Shift down

The low-order bit indicates if key is toggled.

SHORT keyState = GetKeyState(VK_CAPITAL/*(caps lock)*/);
bool isToggled = keyState & 1;
bool isDown = keyState & 0x8000;

Oh and also don't forget to

#include <Windows.h>

How to print a dictionary's key?

In Python 3:

# A simple dictionary
x = {'X':"yes", 'Y':"no", 'Z':"ok"}

# To print a specific key (for example key at index 1)
print([key for key in x.keys()][1])

# To print a specific value (for example value at index 1)
print([value for value in x.values()][1])

# To print a pair of a key with its value (for example pair at index 2)
print(([key for key in x.keys()][2], [value for value in x.values()][2]))

# To print a key and a different value (for example key at index 0 and value at index 1)
print(([key for key in x.keys()][0], [value for value in x.values()][1]))

# To print all keys and values concatenated together
print(''.join(str(key) + '' + str(value) for key, value in x.items()))

# To print all keys and values separated by commas
print(', '.join(str(key) + ', ' + str(value) for key, value in x.items()))

# To print all pairs of (key, value) one at a time
for e in range(len(x)):
    print(([key for key in x.keys()][e], [value for value in x.values()][e]))

# To print all pairs (key, value) in a tuple
print(tuple(([key for key in x.keys()][i], [value for value in x.values()][i]) for i in range(len(x))))

What is key=lambda

A lambda is an anonymous function:

>>> f = lambda: 'foo'
>>> print f()

It is often used in functions such as sorted() that take a callable as a parameter (often the key keyword parameter). You could provide an existing function instead of a lambda there too, as long as it is a callable object.

Take the sorted() function as an example. It'll return the given iterable in sorted order:

>>> sorted(['Some', 'words', 'sort', 'differently'])
['Some', 'differently', 'sort', 'words']

but that sorts uppercased words before words that are lowercased. Using the key keyword you can change each entry so it'll be sorted differently. We could lowercase all the words before sorting, for example:

>>> def lowercased(word): return word.lower()
>>> lowercased('Some')
>>> sorted(['Some', 'words', 'sort', 'differently'], key=lowercased)
['differently', 'Some', 'sort', 'words']

We had to create a separate function for that, we could not inline the def lowercased() line into the sorted() expression:

>>> sorted(['Some', 'words', 'sort', 'differently'], key=def lowercased(word): return word.lower())
  File "<stdin>", line 1
    sorted(['Some', 'words', 'sort', 'differently'], key=def lowercased(word): return word.lower())
SyntaxError: invalid syntax

A lambda on the other hand, can be specified directly, inline in the sorted() expression:

 >>> sorted(['Some', 'words', 'sort', 'differently'], key=lambda word: word.lower())
['differently', 'Some', 'sort', 'words']

Lambdas are limited to one expression only, the result of which is the return value.

There are loads of places in the Python library, including built-in functions, that take a callable as keyword or positional argument. There are too many to name here, and they often play a different role.

python JSON only get keys in first level

As Karthik mentioned, dct.keys() will work but it will return all the keys in dict_keys type not in list type. So if you want all the keys in a list, then list(dct.keys()) will work.

How to get the stream key for

This may be an old thread but I came across it and figured that I would give a final answer.

The twitch api is json based and to recieve your stream key you need to authorize your app for use with the api. You do so under the connections tab within your profile on itself.. Down the bottom of said tab there is "register your app" or something similar. Register it and you'll get a client-id header for your get requests.

Now you need to attach your Oauthv2 key to your headers or as a param during the query to the following get request.

curl -H 'Accept: application/vnd.twitchtv.v3+json' -H 'Authorization: OAuth ' \ -X GET

documentataion here

As you can see in the documentation above, if you've done these two things, your stream key will be made available to you.

As I said - Sorry for the bump but some people do find it hard to read the twitch* api.

Hope that helps somebody in the future.

How do you test a public/private DSA keypair?

Delete the public keys and generate new ones from the private keys. Keep them in separate directories, or use a naming convention to keep them straight.

How to get a random value from dictionary?

With modern versions of Python(since 3), the objects returned by methods dict.keys(), dict.values() and dict.items() are view objects*. And hey can be iterated, so using directly random.choice is not possible as now they are not a list or set.

One option is to use list comprehension to do the job with random.choice:

import random

colors = {
    'purple': '#7A4198',
    'orange': '#EF5C35',
    'blue': '#19457D',
    'green': '#5AF9B5',
    'red': ' #E04160',
    'yellow': '#F9F985'

color=random.choice([hex_color for color_value in colors.values()]

print(f'The new color is: {color}')


php - push array into array - key issue

first convert your array too JSON

   $col[] = json_encode($row,JSON_UNESCAPED_UNICODE);

then vonvert back it to array

foreach($col as &$array){
   $array = json_decode($array,true);

good luck

How to find keys of a hash?

I wanted to use the top rated answer above

Object.prototype.keys = function () ...

However when using in conjunction with the google maps API v3, google maps is non-functional.

for (var key in h) ...

works well.

How to get the index with the key in Python dictionary?

Dictionaries in python have no order. You could use a list of tuples as your data structure instead.

d = { 'a': 10, 'b': 20, 'c': 30}
newd = [('a',10), ('b',20), ('c',30)]

Then this code could be used to find the locations of keys with a specific value

locations = [i for i, t in enumerate(newd) if t[0]=='b']

>>> [1]

How to add multiple values to a dictionary key in python?

Make the value a list, e.g.

a["abc"] = [1, 2, "bob"]


There are a couple of ways to add values to key, and to create a list if one isn't already there. I'll show one such method in little steps.

key = "somekey"
a.setdefault(key, [])


>>> a
{'somekey': [1]}

Next, try:

key = "somekey"
a.setdefault(key, [])


>>> a
{'somekey': [1, 2]}

The magic of setdefault is that it initializes the value for that key if that key is not defined, otherwise it does nothing. Now, noting that setdefault returns the key you can combine these into a single line:



>>> a
{'somekey': [1, 2, 'bob']}

You should look at the dict methods, in particular the get() method, and do some experiments to get comfortable with this.

Accessing dict_keys element by index in Python3

Call list() on the dictionary instead:

keys = list(test)

In Python 3, the dict.keys() method returns a dictionary view object, which acts as a set. Iterating over the dictionary directly also yields keys, so turning a dictionary into a list results in a list of all the keys:

>>> test = {'foo': 'bar', 'hello': 'world'}
>>> list(test)
['foo', 'hello']
>>> list(test)[0]

SSL: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch

I got a MD5 hash with different results for both key and certificate.

This says it all. You have a mismatch between your key and certificate.

The modulus should match. Make sure you have correct key.

PHP: Get key from array?

If it IS a foreach loop as you have described in the question, using $key => $value is fast and efficient.

Python: create dictionary using dict() with integer keys?

There are also these 'ways':

>>> dict.fromkeys(range(1, 4))
{1: None, 2: None, 3: None}
>>> dict(zip(range(1, 4), range(1, 4)))
{1: 1, 2: 2, 3: 3}

Android EditText delete(backspace) key event

My problem was, that I had custom Textwatcher, so I didn't want to add OnKeyListener to an EditText as well as I didn't want to create custom EditText. I wanted to detect if backspace was pressed in my afterTextChanged method, so I shouldn't trigger my event.

This is how I solved this. Hope it would be helpful for someone.

public class CustomTextWatcher extends AfterTextChangedTextWatcher {

private boolean backspacePressed;

public void afterTextChanged(Editable s) {
    if (!backspacePressed) {

public void onTextChanged(CharSequence s, int start, int before, int count) {
    super.onTextChanged(s, start, before, count);
    backspacePressed = count == 0; //if count == 0, backspace is pressed

get dictionary value by key

static void XML_Array(Dictionary<string, string> Data_Array)
    String value;
    if(Data_Array.TryGetValue("XML_File", out value))
     ... Do something here with value ...

how to fetch array keys with jQuery?

Don't Reinvent the Wheel, Use Underscore

I know the OP specifically mentioned jQuery but I wanted to put an answer here to introduce people to the helpful Underscore library if they are not aware of it already.

By leveraging the keys method in the Underscore library, you can simply do the following:

_.keys(foo)  #=> ["alfa", "beta"]

Plus, there's a plethora of other useful functions that are worth perusing.

How to Generate Unique Public and Private Key via RSA

The RSACryptoServiceProvider(CspParameters) constructor creates a keypair which is stored in the keystore on the local machine. If you already have a keypair with the specified name, it uses the existing keypair.

It sounds as if you are not interested in having the key stored on the machine.

So use the RSACryptoServiceProvider(Int32) constructor:

public static void AssignNewKey(){
    RSA rsa = new RSACryptoServiceProvider(2048); // Generate a new 2048 bit RSA key

    string publicPrivateKeyXML = rsa.ToXmlString(true);
    string publicOnlyKeyXML = rsa.ToXmlString(false);
    // do stuff with keys...


Alternatively try setting the PersistKeyInCsp to false:

public static void AssignNewKey(){
    const int PROVIDER_RSA_FULL = 1;
    const string CONTAINER_NAME = "KeyContainer";
    CspParameters cspParams;
    cspParams = new CspParameters(PROVIDER_RSA_FULL);
    cspParams.KeyContainerName = CONTAINER_NAME;
    cspParams.Flags = CspProviderFlags.UseMachineKeyStore;
    cspParams.ProviderName = "Microsoft Strong Cryptographic Provider";
    rsa = new RSACryptoServiceProvider(cspParams);

    rsa.PersistKeyInCsp = false;

    string publicPrivateKeyXML = rsa.ToXmlString(true);
    string publicOnlyKeyXML = rsa.ToXmlString(false);
    // do stuff with keys...

JavaScript: Object Rename Key

This is a small modification that I made to the function of pomber; To be able to take an Array of Objects instead of an object alone and also you can activate index. also the "Keys" can be assigned by an array

function renameKeys(arrayObject, newKeys, index = false) {
    let newArray = [];
        const keyValues = Object.keys(obj).map((key,i) => {
            return {[newKeys[i] || key]:obj[key]}
        let id = (index) ? {'ID':item} : {}; 
        newArray.push(Object.assign(id, ...keyValues));
    return newArray;


const obj = [{ a: "1", b: "2" }, { a: "5", b: "4" } ,{ a: "3", b: "0" }];
const newKeys = ["A","C"];
const renamedObj = renameKeys(obj, newKeys);

Merging two CSV files using Python

When I'm working with csv files, I often use the pandas library. It makes things like this very easy. For example:

import pandas as pd

a = pd.read_csv("filea.csv")
b = pd.read_csv("fileb.csv")
b = b.dropna(axis=1)
merged = a.merge(b, on='title')
merged.to_csv("output.csv", index=False)

Some explanation follows. First, we read in the csv files:

>>> a = pd.read_csv("filea.csv")
>>> b = pd.read_csv("fileb.csv")
>>> a
   title  stage    jan    feb
0   darn  3.001  0.421  0.532
1     ok  2.829  1.036  0.751
2  three  1.115  1.146  2.921
>>> b
   title    mar    apr    may       jun  Unnamed: 5
0   darn  0.631  1.321  0.951    1.7510         NaN
1     ok  1.001  0.247  2.456    0.3216         NaN
2  three  0.285  1.283  0.924  956.0000         NaN

and we see there's an extra column of data (note that the first line of fileb.csv -- title,mar,apr,may,jun, -- has an extra comma at the end). We can get rid of that easily enough:

>>> b = b.dropna(axis=1)
>>> b
   title    mar    apr    may       jun
0   darn  0.631  1.321  0.951    1.7510
1     ok  1.001  0.247  2.456    0.3216
2  three  0.285  1.283  0.924  956.0000

Now we can merge a and b on the title column:

>>> merged = a.merge(b, on='title')
>>> merged
   title  stage    jan    feb    mar    apr    may       jun
0   darn  3.001  0.421  0.532  0.631  1.321  0.951    1.7510
1     ok  2.829  1.036  0.751  1.001  0.247  2.456    0.3216
2  three  1.115  1.146  2.921  0.285  1.283  0.924  956.0000

and finally write this out:

>>> merged.to_csv("output.csv", index=False)



Get HTML5 localStorage keys

This will print all the keys and values on localStorage:


for (let i=0; i< localStorage.length; i++) {
    let key = localStorage.key(i);
    let value = localStorage[key];
    console.log(`localStorage ${key}:  ${value}`);

Keylistener in Javascript

Here's an update for modern browsers in 2019

let playerSpriteX = 0;_x000D_
document.addEventListener('keyup', (e) => {_x000D_
  if (e.code === "ArrowUp")        playerSpriteX += 10_x000D_
  else if (e.code === "ArrowDown") playerSpriteX -= 10_x000D_
  document.getElementById('test').innerHTML = 'playerSpriteX = ' + playerSpriteX;_x000D_
Click on this window to focus it, and hit keys up and down_x000D_
<div id="test">playerSpriteX = 0</div>

Original answer from 2013

window.onkeyup = function(e) {
   var key = e.keyCode ? e.keyCode : e.which;

   if (key == 38) {
       playerSpriteX += 10;
   }else if (key == 40) {
       playerSpriteX -= 10;


Python method for reading keypress?

Figured it out by testing all the stuff by myself. Couldn't find any topics about it tho, so I'll just leave the solution here. This might not be the only or even the best solution, but it works for my purposes (within getch's limits) and is better than nothing.

Note: proper keyDown() which would recognize all the keys and actual key presses, is still valued.

Solution: using ord()-function to first turn the getch() into an integer (I guess they're virtual key codes, but not too sure) works fine, and then comparing the result to the actual number representing the wanted key. Also, if I needed to, I could add an extra chr() around the number returned so that it would convert it to a character. However, I'm using mostly down arrow, esc, etc. so converting those to a character would be stupid. Here's the final code:

from msvcrt import getch
while True:
    key = ord(getch())
    if key == 27: #ESC
    elif key == 13: #Enter
    elif key == 224: #Special keys (arrows, f keys, ins, del, etc.)
        key = ord(getch())
        if key == 80: #Down arrow
        elif key == 72: #Up arrow

Also if someone else needs to, you can easily find out the keycodes from google, or by using python and just pressing the key:

from msvcrt import getch
while True:

get all keys set in memcached

Base on @mu ? answer here. I've written a cache dump script.

The script dumps all the content of a memcached server. It's tested with Ubuntu 12.04 and a localhost memcached, so your milage may vary.

#!/usr/bin/env bash

echo 'stats items'  \
| nc localhost 11211  \
| grep -oe ':[0-9]*:'  \
| grep -oe '[0-9]*'  \
| sort  \
| uniq  \
| xargs -L1 -I{} bash -c 'echo "stats cachedump {} 1000" | nc localhost 11211'

What it does, it goes through all the cache slabs and print 1000 entries of each.

Please be aware of certain limits of this script i.e. it may not scale for a 5GB cache server for example. But it's useful for debugging purposes on a local machine.

How can I sort a std::map first by value, then by key?

As explained in Nawaz's answer, you cannot sort your map by itself as you need it, because std::map sorts its elements based on the keys only. So, you need a different container, but if you have to stick to your map, then you can still copy its content (temporarily) into another data structure.

I think, the best solution is to use a std::set storing flipped key-value pairs as presented in ks1322's answer. The std::set is sorted by default and the order of the pairs is exactly as you need it:

3) If lhs.first<rhs.first, returns true. Otherwise, if rhs.first<lhs.first, returns false. Otherwise, if lhs.second<rhs.second, returns true. Otherwise, returns false.

This way you don't need an additional sorting step and the resulting code is quite short:

std::map<std::string, int> m;  // Your original map.
m["realistically"] = 1;
m["really"]        = 8;
m["reason"]        = 4;
m["reasonable"]    = 3;
m["reasonably"]    = 1;
m["reassemble"]    = 1;
m["reassembled"]   = 1;
m["recognize"]     = 2;
m["record"]        = 92;
m["records"]       = 48;
m["recs"]          = 7;

std::set<std::pair<int, std::string>> s;  // The new (temporary) container.

for (auto const &kv : m)
    s.emplace(kv.second, kv.first);  // Flip the pairs.

for (auto const &vk : s)
    std::cout << std::setw(3) << vk.first << std::setw(15) << vk.second << std::endl;


  1  realistically
  1     reasonably
  1     reassemble
  1    reassembled
  2      recognize
  3     reasonable
  4         reason
  7           recs
  8         really
 48        records
 92         record

Code on Ideone

Note: Since C++17 you can use range-based for loops together with structured bindings for iterating over a map. As a result, the code for copying your map becomes even shorter and more readable:

for (auto const &[k, v] : m)
    s.emplace(v, k);  // Flip the pairs.

SQL keys, MUL vs PRI vs UNI

DESCRIBE <table>; 

This is acutally a shortcut for:


In any case, there are three possible values for the "Key" attribute:

  1. PRI
  2. UNI
  3. MUL

The meaning of PRI and UNI are quite clear:

  • PRI => primary key
  • UNI => unique key

The third possibility, MUL, (which you asked about) is basically an index that is neither a primary key nor a unique key. The name comes from "multiple" because multiple occurrences of the same value are allowed. Straight from the MySQL documentation:

If Key is MUL, the column is the first column of a nonunique index in which multiple occurrences of a given value are permitted within the column.

There is also a final caveat:

If more than one of the Key values applies to a given column of a table, Key displays the one with the highest priority, in the order PRI, UNI, MUL.

As a general note, the MySQL documentation is quite good. When in doubt, check it out!

How to efficiently count the number of keys/properties of an object in JavaScript?

The standard Object implementation (ES5.1 Object Internal Properties and Methods) does not require an Object to track its number of keys/properties, so there should be no standard way to determine the size of an Object without explicitly or implicitly iterating over its keys.

So here are the most commonly used alternatives:

1. ECMAScript's Object.keys()

Object.keys(obj).length; Works by internally iterating over the keys to compute a temporary array and returns its length.

  • Pros - Readable and clean syntax. No library or custom code required except a shim if native support is unavailable
  • Cons - Memory overhead due to the creation of the array.

2. Library-based solutions

Many library-based examples elsewhere in this topic are useful idioms in the context of their library. From a performance viewpoint, however, there is nothing to gain compared to a perfect no-library code since all those library methods actually encapsulate either a for-loop or ES5 Object.keys (native or shimmed).

3. Optimizing a for-loop

The slowest part of such a for-loop is generally the .hasOwnProperty() call, because of the function call overhead. So when I just want the number of entries of a JSON object, I just skip the .hasOwnProperty() call if I know that no code did nor will extend Object.prototype.

Otherwise, your code could be very slightly optimized by making k local (var k) and by using prefix-increment operator (++count) instead of postfix.

var count = 0;
for (var k in myobj) if (myobj.hasOwnProperty(k)) ++count;

Another idea relies on caching the hasOwnProperty method:

var hasOwn = Object.prototype.hasOwnProperty;
var count = 0;
for (var k in myobj) if (, k)) ++count;

Whether this is faster or not on a given environment is a question of benchmarking. Very limited performance gain can be expected anyway.

How to permanently add a private key with ssh-add on Ubuntu?

This didn't answer the same issue for me under Mac OS X Lion. I ended up adding:

ssh-add ~/.ssh/id_rsa &>/dev/null

To my .zshrc (but .profile would be fine too), which seems to have fixed it.

(As suggested here: )

PHP Multidimensional Array Searching (Find key by specific value)

Try this

function recursive_array_search($needle,$haystack) {
        foreach($haystack as $key=>$value) {
            if($needle==$value['uid'] OR (is_array($value) && recursive_array_search($needle,$value) !== false)) {
                return $current_key;
        return false;

How to iterate through table in Lua?

To iterate over all the key-value pairs in a table you can use pairs:

for k, v in pairs(arr) do
  print(k, v[1], v[2], v[3])


pears   2   p   green
apples  0   a   red
oranges 1   o   orange

Edit: Note that Lua doesn't guarantee any iteration order for the associative part of the table. If you want to access the items in a specific order, retrieve the keys from arr and sort it. Then access arr through the sorted keys:

local ordered_keys = {}

for k in pairs(arr) do
    table.insert(ordered_keys, k)

for i = 1, #ordered_keys do
    local k, v = ordered_keys[i], arr[ ordered_keys[i] ]
    print(k, v[1], v[2], v[3])


  apples  a   red     5
  oranges o   orange  12
  pears   p   green   7

How do I remove lines between ListViews on Android?



Or in Java:


Not able to start Genymotion device

try to clear the cache in genymotion Setting -> Misc -> Clear cache.

Check this image

maybe it will solve the problem.

What is the simplest jQuery way to have a 'position:fixed' (always at top) div?

In a project, my client would like a floating box in another div, so I use margin-top CSS property rather than top in order to my floating box stay in its parent.

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

In Other ways to get difference between date;

import dateutil.parser
import datetime
last_sent_date = "" # date string
timeDifference = current_date - dateutil.parser.parse(last_sent_date)
time_difference_in_minutes = (int(timeDifference.days) * 24 * 60) + int((timeDifference.seconds) / 60)

So get output in Min.


Include an SVG (hosted on GitHub) in MarkDown

This will work. Link to your SVG using the following pattern:<repo-owner>/<repo>/<branch>/path/to.svg

The downside is hardcoding the owner and repo in the path, meaning the svg will break if either of those are renamed.

Convert string to date in bash

We can use date -d option

1) Change format to "%Y-%m-%d" format i.e 20121212 to 2012-12-12

date -d '20121212' +'%Y-%m-%d'

2)Get next or last day from a given date=20121212. Like get a date 7 days in past with specific format

date -d '20121212 -7 days' +'%Y-%m-%d'

3) If we are getting date in some variable say dat

dat2=$(date -d "$dat -1 days" +'%Y%m%d')

Missing artifact in pom.xml

Place ojdbc6.jar in your project resources folder of eclipse. then add the following dependency code in your pom.xml

<groupId> oracle </groupId>

How to navigate to to different directories in the terminal (mac)?

To check that the file you're trying to open actually exists, you can change directories in terminal using cd. To change to ~/Desktop/sass/css: cd ~/Desktop/sass/css. To see what files are in the directory: ls.

If you want information about either of those commands, use the man page: man cd or man ls, for example.

Google for "basic unix command line commands" or similar; that will give you numerous examples of moving around, viewing files, etc in the command line.

On Mac OS X, you can also use open to open a finder window: open . will open the current directory in finder. (open ~/Desktop/sass/css will open the ~/Desktop/sass/css).

PHP max_input_vars

New Cpanels block to see the .htaccess file or if you add a .user.ini you wont be able to see it. but with a little hack you can make it work. Edit for example wp-config.php and in the URL bar replace wp-config.php by .htaccess now you can paste the values and save it. enter image description here

Run Stored Procedure in SQL Developer?

To run procedure from SQL developer-only execute following command


Laravel - Session store not set on request

It's not on the laravel documentation, I have been an hour to achieve this:

My session didn't persist until i used the "save" method...


What is the $$hashKey added to my JSON.stringify result

If you are using Angular 1.3 or above, I recommend that you use "track by" in your ng-repeat. Angular doesn't add a "$$hashKey" property to the objects in your array if you use "track by". You also get performance benefits, if something in your array changes, angular doesn't recreate the entire DOM structure for your ng-repeat, it instead recreates the part of the DOM for the values in your array that have changed.

How does #include <bits/stdc++.h> work in C++?

#include <bits/stdc++.h> is an implementation file for a precompiled header.

From, software engineering perspective, it is a good idea to minimize the include. If you use it actually includes a lot of files, which your program may not need, thus increase both compile-time and program size unnecessarily. [edit: as pointed out by @Swordfish in the comments that the output program size remains unaffected. But still, it's good practice to include only the libraries you actually need, unless it's some competitive competition]

But in contests, using this file is a good idea, when you want to reduce the time wasted in doing chores; especially when your rank is time-sensitive.

It works in most online judges, programming contest environments, including ACM-ICPC (Sub-Regionals, Regionals, and World Finals) and many online judges.

The disadvantages of it are that it:

  • increases the compilation time.
  • uses an internal non-standard header file of the GNU C++ library, and so will not compile in MSVC, XCode, and many other compilers

"Exception has been thrown by the target of an invocation" error (mscorlib)

This is may have 2 reasons

1.I found the connection string error in my web.config file i had changed the connection string and its working.

  1. Connection string is proper then check with the control panel>services> SQL Server Browser > start or not

Generating Random Passwords

Added some supplemental code to the accepted answer. It improves upon answers just using Random and allows for some password options. I also liked some of the options from the KeePass answer but did not want to include the executable in my solution.

private string RandomPassword(int length, bool includeCharacters, bool includeNumbers, bool includeUppercase, bool includeNonAlphaNumericCharacters, bool includeLookAlikes)
    if (length < 8 || length > 128) throw new ArgumentOutOfRangeException("length");
    if (!includeCharacters && !includeNumbers && !includeNonAlphaNumericCharacters) throw new ArgumentException("RandomPassword-Key arguments all false, no values would be returned");

    string pw = "";
        pw += System.Web.Security.Membership.GeneratePassword(128, 25);
        pw = RemoveCharacters(pw, includeCharacters, includeNumbers, includeUppercase, includeNonAlphaNumericCharacters, includeLookAlikes);
    } while (pw.Length < length);

    return pw.Substring(0, length);

private string RemoveCharacters(string passwordString, bool includeCharacters, bool includeNumbers, bool includeUppercase, bool includeNonAlphaNumericCharacters, bool includeLookAlikes)
    if (!includeCharacters)
        var remove = new string[] { "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z" };
        foreach (string r in remove)
            passwordString = passwordString.Replace(r, string.Empty);
            passwordString = passwordString.Replace(r.ToUpper(), string.Empty);

    if (!includeNumbers)
        var remove = new string[] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9" };
        foreach (string r in remove)
            passwordString = passwordString.Replace(r, string.Empty);

    if (!includeUppercase)
        passwordString = passwordString.ToLower();

    if (!includeNonAlphaNumericCharacters)
        var remove = new string[] { "!", "@", "#", "$", "%", "^", "&", "*", "(", ")", "-", "_", "+", "=", "{", "}", "[", "]", "|", "\\", ":", ";", "<", ">", "/", "?", "." };
        foreach (string r in remove)
            passwordString = passwordString.Replace(r, string.Empty);

    if (!includeLookAlikes)
        var remove = new string[] { "(", ")", "0", "O", "o", "1", "i", "I", "l", "|", "!", ":", ";" };
        foreach (string r in remove)
            passwordString = passwordString.Replace(r, string.Empty);

    return passwordString;

This was the first link when I searched for generating random passwords and the following is out of scope for the current question but might be important to consider.

  • Based upon the assumption that System.Web.Security.Membership.GeneratePassword is cryptographically secure with a minimum of 20% of the characters being Non-Alphanumeric.
  • Not sure if removing characters and appending strings is considered good practice in this case and provides enough entropy.
  • Might want to consider implementing in some way with SecureString for secure password storage in memory.

How to deal with the URISyntaxException

A space is encoded to %20 in URLs, and to + in forms submitted data (content type application/x-www-form-urlencoded). You need the former.

Using Guava:

dependencies {
     compile ''

You can use UrlEscapers:

String encodedString = UrlEscapers.urlFragmentEscaper().escape(inputString);

Don't use String.replace, this would only encode the space. Use a library instead.

YouTube Video Embedded via iframe Ignoring z-index?

Joshc's answer was on the right track, but I found that it totally deletes the ?rel=0 querystring and replaces it with the ?wmode=transparent item - which has the effect of displaying the YouTube Suggested Videos list at the end of the playback, even though you originally didn't want this to happen.

I changed the code so that the src attribute of the embedded video is scanned first, to see if there is a question mark ? in it already (because this denotes the presence of a pre-existing query string, which might be something like ?rel=0 but could in theory be anything that YouTube choose to append in the future). If there's a query string already there, we want to preserve it, not destroy it, because it represents a setting chosen by whoever pasted in this YouTube video, and they presumably chose it for a reason!

So, if ? is found, the wmode=transparent will be appended using the format: &mode=transparent to just tag it on the end of the pre-existing query string.

If no ? is found, then the code will work in exactly the same way as it did originally (in toomanyairmiles's post), appending just ?wmode=transparent as a new query string to the URL.

Now, regardless of what may or may not be on the end of the YouTube URL as a query string already, it gets preserved, and the required wmode parameters get injected or added without damage to what was there before.

Here's the code to drop into your document.ready function:

$('iframe').each(function() {
  var url = $(this).attr("src");
  if (url.indexOf("?") > 0) {
      "src" : url + "&wmode=transparent",
      "wmode" : "opaque"
  else {
      "src" : url + "?wmode=transparent",
      "wmode" : "opaque"

Java, looping through result set

The problem with your code is :

     String  show[]= {rs4.getString(1)};
     String actuate[]={rs4.getString(2)};

This will create a new array every time your loop (an not append as you might be assuming) and hence in the end you will have only one element per array.

Here is one more way to solve this :

    StringBuilder sids = new StringBuilder ();
    StringBuilder lids = new StringBuilder ();

    while ( {
        sids.append(rs4.getString(1)).append(" ");
        lids.append(rs4.getString(2)).append(" ");

    String show[] = sids.toString().split(" "); 
    String actuate[] = lids.toString().split(" ");

These arrays will have all the required element.

Generate PDF from HTML using pdfMake in Angularjs

this is what it worked for me I'm using html2pdf from an Angular2 app, so I made a reference to this function in the controller

var html2pdf = (function(html2canvas, jsPDF) {

declared in html2pdf.js.

So I added just after the import declarations in my angular-controller this declaration:

declare function html2pdf(html2canvas, jsPDF): any;

then, from a method of my angular controller I'm calling this function:

      pdfContent => {
        html2pdf(pdfContent, {
          margin:       1,
          filename:     'myfile.pdf',
          image:        { type: 'jpeg', quality: 0.98 },
          html2canvas:  { dpi: 192, letterRendering: true },
          jsPDF:        { unit: 'in', format: 'A4', orientation: 'portrait' }

Hope it helps

Get distance between two points in canvas

If you have the coordinates, use the formula to calculate the distance:

var dist = Math.sqrt( Math.pow((x1-x2), 2) + Math.pow((y1-y2), 2) );

If your platform supports the ** operator, you can instead use that:

const dist = Math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2);

how to refresh page in angular 2

The simplest possible solution I found was:

In your markup:

<a [href]="location.path()">Reload</a>

and in your component typescript file:

        private location: Location
  ) { }

How to get Top 5 records in SqLite?

select price from mobile_sales_details order by price desc limit 5

Note: i have mobile_sales_details table


select column_name from table_name order by column_name desc limit size.  

if you need top low price just remove the keyword desc from order by

Is it possible to write to the console in colour in .NET?

Yes. See this article. Here's an example from there:

Console.BackgroundColor = ConsoleColor.Blue;
Console.ForegroundColor = ConsoleColor.White;
Console.WriteLine("White on blue.");

enter image description here

What is the best way to add options to a select from a JavaScript object with jQuery?

I have made something like this, loading a dropdown item via Ajax. The response above is also acceptable, but it is always good to have as little DOM modification as as possible for better performance.

So rather than add each item inside a loop it is better to collect items within a loop and append it once it's completed.

    ... Collect items

Append it,


or even better


Set value of textarea in jQuery

Have you tried val?


Batch file to delete files older than N days

My command is

forfiles -p "d:\logs" -s -m*.log -d-15 -c"cmd /c del @PATH\@FILE" 

@PATH - is just path in my case, so I had to use @PATH\@FILE

also forfiles /? not working for me too, but forfiles (without "?") worked fine.

And the only question I have: how to add multiple mask (for example ".log|.bak")?

All this regarding forfiles.exe that I downloaded here (on win XP)

But if you are using Windows server forfiles.exe should be already there and it is differs from ftp version. That is why I should modify command.

For Windows Server 2003 I'm using this command:

forfiles -p "d:\Backup" -s -m *.log -d -15 -c "cmd /c del @PATH"

Stop Excel from automatically converting certain text values to dates

Hi I have the same issue,

I write this vbscipt to create another CSV file. The new CSV file will have a space in font of each field, so excel will understand it as text.

So you create a .vbs file with the code below (for example Modify_CSV.vbs), save and close it. Drag and Drop your original file to your vbscript file. It will create a new file with "SPACE_ADDED" to file name in the same location.

Set objArgs = WScript.Arguments

Set objFso = createobject("scripting.filesystemobject")

dim objTextFile
dim arrStr ' an array to hold the text content
dim sLine  ' holding text to write to new file

'Looping through all dropped file
For t = 0 to objArgs.Count - 1
    ' Input Path
    inPath = objFso.GetFile(wscript.arguments.item(t))

    ' OutPut Path
    outPath = replace(inPath, objFso.GetFileName(inPath), left(objFso.GetFileName(inPath), InStrRev(objFso.GetFileName(inPath),".") - 1) & "_SPACE_ADDED.csv")

    ' Read the file
    set objTextFile = objFso.OpenTextFile(inPath)

    'Now Creating the file can overwrite exiting file
    set aNewFile = objFso.CreateTextFile(outPath, True) 

    'Open the file to appending data
    set aNewFile = objFso.OpenTextFile(outPath, 8) '2=Open for writing 8 for appending

    ' Reading data and writing it to new file
    Do while NOT objTextFile.AtEndOfStream
        arrStr = split(objTextFile.ReadLine,",")

        sLine = ""  'Clear previous data

        For i=lbound(arrStr) to ubound(arrStr)
            sLine = sLine + " " + arrStr(i) + ","

        'Writing data to new file
        aNewFile.WriteLine left(sLine, len(sLine)-1) 'Get rid of that extra comma from the loop


    'Closing new file

Next ' This is for next file

set aNewFile=nothing
set objFso = nothing
set objArgs = nothing

How do I make a batch file terminate upon encountering an error?

One minor update, you should change the checks for "if errorlevel 1" to the following...


This is because on XP you can get negative numbers as errors. 0 = no problems, anything else is a problem.

And keep in mind the way that DOS handles the "IF ERRORLEVEL" tests. It will return true if the number you are checking for is that number or higher so if you are looking for specific error numbers you need to start with 255 and work down.

How to determine whether a substring is in a different string

In [7]: substring = "please help me out"

In [8]: string = "please help me out so that I could solve this"

In [9]: substring in string
Out[9]: True

How to remove unused imports in Intellij IDEA on commit?

In Mac IntelliJ IDEA, the command is Cmd + Option + O

For some older versions it is apparently Ctrl + Option + O.

(Letter O not Zero 0) on the latest version 2019.x

Sync data between Android App and webserver

I would suggest using a binary webservice protocol similar to Hessian. It works very well and they do have a android implementation. It might be a little heavy but depends on the application you are building. Hope this helps.

How to use template module with different set of variables?

- name: copy vhosts
  template: src=site-vhost.conf dest=/etc/apache2/sites-enabled/{{ item }}.conf
    - somehost.local
    - otherhost.local
  notify: restart apache

IMPORTANT: Note that an item does not have to be just a string, it can be an object with as many properties as you like, so that way you can pass any number of variables.

In the template I have:

<VirtualHost *:80>
    ServerAdmin [email protected]
    ServerName {{ item }}
    DocumentRoot /vagrant/public

    ErrorLog ${APACHE_LOG_DIR}/error-{{ item }}.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined


How to obfuscate Python code effectively?

Maybe you can try on pyconcrete

encrypt .pyc to .pye and decrypt when import it

encrypt & decrypt by library OpenAES


Full encrypted

  • convert all of your .py to *.pye

    $ compile --source={your py script}  --pye
    $ compile --source={your py module dir} --pye
  • remove *.py *.pyc or copy *.pye to other folder

  • encrypted as main.pye, it can't be executed by normal python. You must use pyconcrete to process the main.pye script. pyconcrete(exe) will be installed in your system path (ex: /usr/local/bin)

    pyconcrete main.pye
    src/*.pye  # your libs

Partial encrypted (pyconcrete as lib)

  • download pyconcrete source and install by

    $ python install \
      --install-lib={your project path} \
      --install-scripts={where you want to execute and pyconcrete(exe)}
  • import pyconcrete in your main script

  • recommendation project layout       # import pyconcrete and your lib
    pyconcrete/*  # put pyconcrete lib in project root, keep it as original files
    src/*.pye     # your libs

Can we add div inside table above every <tr>?

In the html tables, <table> tag expect <tr> tag right after itself and <tr> tag expect <td> tag right after itself. So if you want to put a div in table, you can put it in between <td> and </td> tags as data.

        <p>It works well</p>_x000D_

How to calculate the running time of my program?

At the beginning of your main method, add this line of code :

final long startTime = System.nanoTime();

And then, at the last line of your main method, you can add :

final long duration = System.nanoTime() - startTime;

duration now contains the time in nanoseconds that your program ran. You can for example print this value like this:


If you want to show duration time in seconds, you must divide the value by 1'000'000'000. Or if you want a Date object: Date myTime = new Date(duration / 1000); You can then access the various methods of Date to print number of minutes, hours, etc.

C# - insert values from file into two arrays

var Text = File.ReadAllLines("Path"); foreach (var i in Text) {    var SplitText = i.Split().Where(x=> x.Lenght>1).ToList();    //@Array1 add SplitText[0]    //@Array2 add SpliteText[1]   }  

Identify if a string is a number

You can always use the built in TryParse methods for many datatypes to see if the string in question will pass.


decimal myDec;
var Result = decimal.TryParse("123", out myDec);

Result would then = True

decimal myDec;
var Result = decimal.TryParse("abc", out myDec);

Result would then = False

JavaScript/regex: Remove text between parentheses

var str = "Hello, this is Mike (example)";

alert(str.replace(/\s*\(.*?\)\s*/g, ''));

That'll also replace excess whitespace before and after the parentheses.

MySQL duplicate entry error even though there is no duplicate entry

i have just tried, and if you have data and table recreation wouldnt work, just alter table to InnoDB and try again, it would fix the problem

How can I list (ls) the 5 last modified files in a directory?

The accepted answer lists only the filenames, but to get the top 5 files one can also use:

ls -lht | head -6


-l outputs in a list format

-h makes output human readable (i.e. file sizes appear in kb, mb, etc.)

-t sorts output by placing most recently modified file first

head -6 will show 5 files because ls prints the block size in the first line of output.

I think this is a slightly more elegant and possibly more useful approach.

Example output:

total 26960312 -rw-r--r--@ 1 user staff 1.2K 11 Jan 11:22 -rw-r--r--@ 1 user staff 2.7M 10 Jan 15:26 03-cookies-1.pdf -rw-r--r--@ 1 user staff 9.2M 9 Jan 16:21 Wk1_sem.pdf -rw-r--r--@ 1 user staff 502K 8 Jan 10:20 lab-01.pdf -rw-rw-rw-@ 1 user staff 2.0M 5 Jan 22:06 0410-1.wmv

Use index in pandas to plot data


Uses index as x-axis by default.

How can I get list of values from dict?

You can use * operator to unpack dict_values:

>>> d = {1: "a", 2: "b"}
>>> [*d.values()]
['a', 'b']

or list object

>>> d = {1: "a", 2: "b"}
>>> list(d.values())
['a', 'b']

changing iframe source with jquery

Using attr() pointing to an external domain may trigger an error like this in Chrome: "Refused to display document because display forbidden by X-Frame-Options". The workaround to this can be to move the whole iframe HTML code into the script (eg. using .html() in jQuery).


var divMapLoaded = false;
$("#container").scroll(function() {
    if ((!divMapLoaded) && ($("#map").position().left <= $("#map").width())) {
    $("#map-iframe").html("<iframe id=\"map-iframe\" " +
        "width=\"100%\" height=\"100%\" frameborder=\"0\" scrolling=\"no\" " +
        "marginheight=\"0\" marginwidth=\"0\" " +
        "src=\";cid=0x3e589d98063177ab&amp;ie=UTF8&amp;iwloc=A&amp;brcurrent=5,0,1&amp;ll=41.123115,16.853177&amp;spn=0.005617,0.009943&amp;output=embed\"" +
    divMapLoaded = true;

Angular 2 change event on every keypress

The (keyup) event is your best bet.

Let's see why:

  1. (change) like you mentioned triggers only when the input loses focus, hence is of limited use.
  2. (keypress) triggers on key presses but doesn't trigger on certain keystrokes like the backspace.
  3. (keydown) triggers every time a key is pushed down. Hence always lags by 1 character; as it gets the element state before the keystroke was registered.
  4. (keyup) is your best bet as it triggers every time a key push event has completed, hence this also includes the most recent character.

So (keyup) is the safest to go with because it...

  • registers an event on every keystroke unlike (change) event
  • includes the keys that (keypress) ignores
  • has no lag unlike the (keydown) event

How to detect if a stored procedure already exists

A better option might be to use a tool like Red-Gate SQL Compare or SQL Examiner to automatically compare the differences and generate a migration script.

Print the contents of a DIV

I think there is a better solution. Make your div to print cover the entire document, but only when it's printed:

@media print {
    .myDivToPrint {
        background-color: white;
        height: 100%;
        width: 100%;
        position: fixed;
        top: 0;
        left: 0;
        margin: 0;
        padding: 15px;
        font-size: 14px;
        line-height: 18px;

How to select all elements with a particular ID in jQuery?

Can you assign a unique CSS class to each distinct timer? That way you could use the selector for the CSS class, which would work fine with multiple div elements.

Initialize a long in Java

To initialize long you need to append "L" to the end.
It can be either uppercase or lowercase.

All the numeric values are by default int. Even when you do any operation of byte with any integer, byte is first promoted to int and then any operations are performed.

Try this

byte a = 1; // declare a byte
a = a*2; //  you will get error here

You get error because 2 is by default int.
Hence you are trying to multiply byte with int. Hence result gets typecasted to int which can't be assigned back to byte.

Port 80 is being used by SYSTEM (PID 4), what is that?

I've found out that "SQL Server Reporting Services (MSSQLSERVER)" starts automatically and listens on port 80.

I hope this helps.


Forbidden You don't have permission to access / on this server

Found my solution on Apache/2.2.15 (Unix).

And Thanks for answer from @QuantumHive:

First: I finded all

Order allow,deny
Deny from all

instead of

Order allow,deny

Allow from all

and then:

I setted

# Control access to UserDir directories.  The following is an example
# for a site where these directories are restricted to read-only.
#<Directory /var/www/html>
#    AllowOverride FileInfo AuthConfig Limit
#    Options MultiViews Indexes SymLinksIfOwnerMatch IncludesNoExec
#        Order allow,deny
#        Allow from all
#    </Limit>
#    <LimitExcept GET POST OPTIONS>
#        Order deny,allow
#        Deny from all
#    </LimitExcept>

Remove the previous "#" annotation to

# Control access to UserDir directories.  The following is an example
# for a site where these directories are restricted to read-only.
<Directory /var/www/html>
    AllowOverride FileInfo AuthConfig Limit
    Options MultiViews Indexes SymLinksIfOwnerMatch IncludesNoExec
        Order allow,deny
        Allow from all
    <LimitExcept GET POST OPTIONS>
        Order deny,allow
        Deny from all

ps. my WebDir is: /var/www/html

How to change Rails 3 server default port in develoment?

Combining two previous answers, for Rails 4.0.4 (and up, presumably), this suffices at the end of config/boot.rb:

require 'rails/commands/server'

module Rails
  class Server
    def default_options
      super.merge({Port: 10524})

How do I get the latest version of my code?

You have to merge your files first. Do a git status to see what are the files that need to be merged (means you need to resolve the conflicts first). Once this is done, do git add file_merged and do your pull again.

How to detect escape key press with pure JS or jQuery?

pure JS (no JQuery)

document.addEventListener('keydown', function(e) {
    if(e.keyCode == 27){
      //add your code here

MySQL Workbench - Connect to a Localhost

If xamp already installed on your computer user these settings

enter image description here

nodejs send html file to client

After years, I want to add another approach by using a view engine in Express.js

var fs = require('fs');

app.get('/test', function(req, res, next) {
    var html = fs.readFileSync('./html/test.html', 'utf8')
    res.render('test', { html: html })
    // or res.send(html)

Then, do that in your views/test if you choose res.render method at the above code (I'm writing in EJS format):

<%- locals.html %>

That's all.

In this way, you don't need to break your View Engine arrangements.

Most efficient way to get table row count

Following is the most performant way to find the next AUTO_INCREMENT value for a table. This is quick even on databases housing millions of tables, because it does not require querying the potentially large information_schema database.

mysql> SHOW TABLE STATUS LIKE 'table_name';
// Look for the Auto_increment column

However, if you must retrieve this value in a query, then to the information_schema database you must go.

WHERE  TABLE_SCHEMA = 'DatabaseName'
AND    TABLE_NAME   = 'TableName';

How do I clone a Django model instance object and save it to the database?

There's a clone snippet here, which you can add to your model which does this:

def clone(self):
  new_kwargs = dict([(, getattr(old, for fld in old._meta.fields if !=]);
  return self.__class__.objects.create(**new_kwargs)

ASP.NET Core 1.0 on IIS error 502.5

So I got a new server, this time it's Windows 2008R2 and my app works fine.

I can't say for sure what the problem was with the old server but I have one idea.

So because I previously compiled the app without any platform in mind it gave me the dll version which only works if the target host has .Net Core Windows Hosting package installed. In my case it was installed and that was fine.

After the app didn't work I decieded to compile it as a console app with win7-x64 as runtime. This time the moment I ran the exe of my app on the server, it crashed with an error about a missing dll:

The program can't start because api-ms-win-crt-runtime-l1-1-0.dll is missing

That dll is from Universal C Runtime that's included in the Visual C++ Redistributable for Visual Studio 2015.

I tried to install that package (both x64 & x86) but it failed each time (don't know why) on Windows Server 2012 R2.

But when I tried to install them in the new server, Windows Server 2008 R2, they successfully installed. That might have been the reason behind it, but still can't say for sure.

What does it mean with bug report captured in android tablet?

It's because you have turned on USB debugging in Developer Options. You can create a bug report by holding the power + both volume up and down.

Edit: This is what the forums say:

By pressing Volume up + Volume down + power button, you will feel a vibration after a second or so, that's when the bug reporting initiated.

To disable:

/system/bin/ must be deleted/renamed.

There should be a folder on your SD card called "bug reports".

Have a look at this thread:

And this one:

Spring - No EntityManager with actual transaction available for current thread - cannot reliably process 'persist' call

If you have

@Transactional // Spring Transactional
class MyDao extends Dao {

and super-class

class Dao {
    public void save(Entity entity) { getEntityManager().merge(entity); }

and you call

@Autowired MyDao myDao;;

you won't get a Spring TransactionInterceptor (that gives you a transaction).

This is what you need to do:

class MyDao extends Dao {
    public void save(Entity entity) {; }

Unbelievable but true.

How to import/include a CSS file using PHP code and not HTML code?

Just put

echo "<link rel='stylesheet' type='text/css' href='CSS/main.css'>";

inside the php code, then your style is incuded. Worked for me, I tried.

Error: [$resource:badcfg] Error in resource configuration. Expected response to contain an array but got an object?

First of all you should configure $resource in different manner: without query params in the URL. Default query parameters may be passed as properties of the second parameter in resource(url, paramDefaults, actions). It is also to be mentioned that you configure get method of resource and using query instead.


angular.module('', ['ngResource'])       
  .factory('getTaskService', function($resource) {
    return $resource(
      { method: 'getTask', q: '*' }, // Query parameters
      {'query': { method: 'GET' }}


openssl s_client -cert: Proving a client certificate was sent to the server

In order to verify a client certificate is being sent to the server, you need to analyze the output from the combination of the -state and -debug flags.

First as a baseline, try running

$ openssl s_client -connect host:443 -state -debug

You'll get a ton of output, but the lines we are interested in look like this:

SSL_connect:SSLv3 read server done A
write to 0x211efb0 [0x21ced50] (12 bytes => 12 (0xC))
0000 - 16 03 01 00 07 0b 00 00-03                        .........
000c - <SPACES/NULS>
SSL_connect:SSLv3 write client certificate A

What's happening here:

  • The -state flag is responsible for displaying the end of the previous section:

    SSL_connect:SSLv3 read server done A  

    This is only important for helping you find your place in the output.

  • Then the -debug flag is showing the raw bytes being sent in the next step:

    write to 0x211efb0 [0x21ced50] (12 bytes => 12 (0xC))
    0000 - 16 03 01 00 07 0b 00 00-03                        .........
    000c - <SPACES/NULS>
  • Finally, the -state flag is once again reporting the result of the step that -debug just echoed:

    SSL_connect:SSLv3 write client certificate A

So in other words: s_client finished reading data sent from the server, and sent 12 bytes to the server as (what I assume is) a "no client certificate" message.

If you repeat the test, but this time include the -cert and -key flags like this:

$ openssl s_client -connect host:443 \
   -cert cert_and_key.pem \
   -key cert_and_key.pem  \
   -state -debug

your output between the "read server done" line and the "write client certificate" line will be much longer, representing the binary form of your client certificate:

SSL_connect:SSLv3 read server done A
write to 0x7bd970 [0x86d890] (1576 bytes => 1576 (0x628))
0000 - 16 03 01 06 23 0b 00 06-1f 00 06 1c 00 06 19 31   ....#..........1
0620 - 95 ca 5e f4 2f 6c 43 11-                          ..^%/lC.
SSL_connect:SSLv3 write client certificate A

The 1576 bytes is an excellent indication on its own that the cert was transmitted, but on top of that, the right-hand column will show parts of the certificate that are human-readable: You should be able to recognize the CN and issuer strings of your cert in there.

Simulating Key Press C#

Use mouse_event or keybd_event. They say not to use them anymore but you don't have to find the window at all.

using System;
using System.Runtime.InteropServices;

public class SimulatePCControl

[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
public static extern void keybd_event(uint bVk, uint bScan, uint dwFlags, uint dwExtraInfo);

private const int VK_LEFT = 0x25;

public static void LeftArrow()
    keybd_event(VK_LEFT, 0, 0, 0);


Virtual Key Codes are here for this one:

Also for mouse:

using System.Runtime.InteropServices;
using UnityEngine;

public class SimulateMouseClick
[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
public static extern void mouse_event(uint dwFlags, uint dx, uint dy, uint cButtons, uint dwExtraInfo);
//Mouse actions
private const int MOUSEEVENTF_LEFTDOWN = 0x02;
private const int MOUSEEVENTF_LEFTUP = 0x04;
private const int MOUSEEVENTF_RIGHTDOWN = 0x08;
private const int MOUSEEVENTF_RIGHTUP = 0x10;

public static void Click()
    //Call the imported function with the cursor's current position
    uint X = (uint)0;
    uint Y = (uint)0;

//...other code needed for the application

jQuery: How can I create a simple overlay?

By overlay do you mean content that overlaps/covers the rest of the page? In HTML, you could do this by using a div that uses absolute or fixed positioning. If it needed to be generated dynamically, jQuery could simply generate a div with the position style set appropriately.

New line character in VB.Net?

it's :


for example

Msgbox ("Fst line" & vbnewline & "second line")

Form Submit Execute JavaScript Best Practice?

I know it's a little late for this. But I always thought that the best way to create event listeners is directly from JavaScript. Kind of like not applying inline CSS styles.

function validate(){
    //do stuff
function init(){
    document.getElementById('form').onsubmit = validate;
window.onload = init;

That way you don't have a bunch of event listeners throughout your HTML.

Using ORDER BY and GROUP BY together

One way to do this that correctly uses group by:

select l.* 
from table l
inner join (
    m_id, max(timestamp) as latest 
  from table 
  group by m_id
) r
  on l.timestamp = r.latest and l.m_id = r.m_id
order by timestamp desc

How this works:

  • selects the latest timestamp for each distinct m_id in the subquery
  • only selects rows from table that match a row from the subquery (this operation -- where a join is performed, but no columns are selected from the second table, it's just used as a filter -- is known as a "semijoin" in case you were curious)
  • orders the rows

Error Importing SSL certificate : Not an X.509 Certificate

Does your cacerts.pem file hold a single certificate? Since it is a PEM, have a look at it (with a text editor), it should start with


and end with


Finally, to check it is not corrupted, get hold of openssl and print its details using

openssl x509 -in cacerts.pem -text

How to get text from EditText?

If you are doing it before the setContentView() method call, then the values will be null.

This will result in null:


Button btn = (Button)findViewById(;
String text = (String) btn.getText();


while this will work fine:


Button btn = (Button)findViewById(;
String text = (String) btn.getText();

CSS center display inline block?

The accepted solution wouldn't work for me as I need a child element with display: inline-block to be both horizontally and vertically centered within a 100% width parent.

I used Flexbox's justify-content and align-items properties, which respectively allow you to center elements horizontally and vertically. By setting both to center on the parent, the child element (or even multiple elements!) will be perfectly in the middle.

This solution does not require fixed width, which would have been unsuitable for me as my button's text will change.

Here is a CodePen demo and a snippet of the relevant code below:

.parent {
  display: flex;
  justify-content: center;
  align-items: center;
<div class="parent">
  <a class="child" href="#0">Button</a>

Reverse colormap in matplotlib

There are two types of LinearSegmentedColormaps. In some, the _segmentdata is given explicitly, e.g., for jet:

>>> cm.jet._segmentdata
{'blue': ((0.0, 0.5, 0.5), (0.11, 1, 1), (0.34, 1, 1), (0.65, 0, 0), (1, 0, 0)), 'red': ((0.0, 0, 0), (0.35, 0, 0), (0.66, 1, 1), (0.89, 1, 1), (1, 0.5, 0.5)), 'green': ((0.0, 0, 0), (0.125, 0, 0), (0.375, 1, 1), (0.64, 1, 1), (0.91, 0, 0), (1, 0, 0))}

For rainbow, _segmentdata is given as follows:

>>> cm.rainbow._segmentdata
{'blue': <function <lambda> at 0x7fac32ac2b70>, 'red': <function <lambda> at 0x7fac32ac7840>, 'green': <function <lambda> at 0x7fac32ac2d08>}

We can find the functions in the source of matplotlib, where they are given as

_rainbow_data = {
        'red': gfunc[33],   # 33: lambda x: np.abs(2 * x - 0.5),
        'green': gfunc[13], # 13: lambda x: np.sin(x * np.pi),
        'blue': gfunc[10],  # 10: lambda x: np.cos(x * np.pi / 2)

Everything you want is already done in matplotlib, just call cm.revcmap, which reverses both types of segmentdata, so


should do the job - you can simply create a new LinearSegmentData from that. In revcmap, the reversal of function based SegmentData is done with

def _reverser(f):
    def freversed(x):
        return f(1 - x)
    return freversed

while the other lists are reversed as usual

valnew = [(1.0 - x, y1, y0) for x, y0, y1 in reversed(val)] 

So actually the whole thing you want, is

def reverse_colourmap(cmap, name = 'my_cmap_r'):
     return mpl.colors.LinearSegmentedColormap(name, cm.revcmap(cmap._segmentdata)) 

Valid characters in a Java class name

Class names should be nouns in UpperCamelCase, with the first letter of every word capitalised. Use whole words — avoid acronyms and abbreviations (unless the abbreviation is much more widely used than the long form, such as URL or HTML). The naming conventions can be read over here:

How to split a dos path into its components in Python

You can simply use the most Pythonic approach (IMHO):

import os

your_path = r"d:\stuff\morestuff\furtherdown\THEFILE.txt"
path_list = your_path.split(os.sep)
print path_list

Which will give you:

['d:', 'stuff', 'morestuff', 'furtherdown', 'THEFILE.txt']

The clue here is to use os.sep instead of '\\' or '/', as this makes it system independent.

To remove colon from the drive letter (although I don't see any reason why you would want to do that), you can write:

path_list[0] = path_list[0][0]

Is there a "goto" statement in bash?

This is a small correction of the Judy Schmidt script put up by Hubbbitus.

Putting non-escaped labels in the script was problematic on the machine and caused it to crash. This was easy enough to resolve by adding # to escape the labels. Thanks to Alexej Magura and access_granted for their suggestions.

# include this boilerplate
function goto {  
cmd=$(sed -n "/$#label#:/{:a;n;p;ba};" $0 | grep -v ':$')
eval "$cmd"


goto $start

echo "start"
goto bing

echo boom
goto eof

echo bang
goto boom

echo bing
goto bang

echo "the end mother-hugger..."

Error:java: javacTask: source release 8 requires target release 1.8

Don't forget to set dependencies for your module: enter image description here

How do I get the height of a div's full content with jQuery?

  1. Using scrollHeight is not only buggy, but doesn't work when your container has a hardcoded height (which is probably most cases, since you wanna get contents height without doing container.height() itself)
  2. @shazboticus-s-shazbot solution is good when you can mess around with the container height temporarily / have a hard-coded height.
  3. An alternative solution would be:

    // Get children in array format, as we'll be reducing them into a single number_x000D_
    // Filter out text and comment nodes, only allowing tags_x000D_
    .filter(el => el.nodeType === 1)_x000D_
    // Sum up all the children individual heights_x000D_
    .reduce((accumulator, el) => $(el).outerHeight(true) + accumulator, 0);

Of course, this latter alternative only works when #outer doesn't have immediate text childrens that take up space and you want to measure. Those are my 2 cents.

  1. If you want to measure unwrapped text, I'd suggest modifying your DOM tree and having an inner <div> of which you can measure easily by doing $('#outer').children().height()

Incrementing in C++ - When to use x++ or ++x?

Postfix form of ++,-- operator follows the rule use-then-change ,

Prefix form (++x,--x) follows the rule change-then-use.

Example 1:

When multiple values are cascaded with << using cout then calculations(if any) take place from right-to-left but printing takes place from left-to-right e.g., (if val if initially 10)

 cout<< ++val<<" "<< val++<<" "<< val;

will result into

12    10    10 

Example 2:

In Turbo C++, if multiple occurrences of ++ or (in any form) are found in an expression, then firstly all prefix forms are computed then expression is evaluated and finally postfix forms are computed e.g.,

int a=10,b;
b=a++ + ++a + ++a + a;

It's output in Turbo C++ will be

48 13

Whereas it's output in modern day compiler will be (because they follow the rules strictly)

45 13
  • Note: Multiple use of increment/decrement operators on same variable in one expression is not recommended. The handling/results of such
    expressions vary from compiler to compiler.

.NET Global exception handler in console application

I just inherited an old VB.NET console application and needed to set up a Global Exception Handler. Since this question mentions VB.NET a few times and is tagged with VB.NET, but all the other answers here are in C#, I thought I would add the exact syntax for a VB.NET application as well.

Public Sub Main()
    REM Set up Global Unhandled Exception Handler.
    AddHandler System.AppDomain.CurrentDomain.UnhandledException, AddressOf MyUnhandledExceptionEvent

    REM Do other stuff
End Sub

Public Sub MyUnhandledExceptionEvent(ByVal sender As Object, ByVal e As UnhandledExceptionEventArgs)
    REM Log Exception here and do whatever else is needed
End Sub

I used the REM comment marker instead of the single quote here because Stack Overflow seemed to handle the syntax highlighting a bit better with REM.

How do I solve this "Cannot read property 'appendChild' of null" error?

Just reorder or make sure, the (DOM or HTML) is loaded before the JavaScript.

If statement within Where clause

You can't use IF like that. You can do what you want with AND and OR:

SELECT t.first_name,
  FROM employeetable t
 WHERE ((status_flag = STATUS_ACTIVE   AND t.status = 'A')
     OR (status_flag = STATUS_INACTIVE AND t.status = 'T')
     OR (source_flag = SOURCE_FUNCTION AND t.business_unit = 'production')
     OR (source_flag = SOURCE_USER     AND t.business_unit = 'users'))
   AND t.first_name LIKE firstname
   AND t.last_name  LIKE lastname
   AND t.employid   LIKE employeeid;

How to run server written in js with Node.js

I open a text editor, in my case I used Atom. Paste this code

var http = require('http');
http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello World\n');
}).listen(1337, '');
console.log('Server running at');

and save as




directory. Next I open node.js commamd prompt enter

cd c:\xampp\htdocs\myproject


node helloworld.js

next I open my chrome browser and I type


and there it is.

How to convert an enum type variable to a string?

Personally, I would go for something simple and use an operator to do so.

Considering the following enum:


We can create an operator to output the result in an std::ostream.

std::ostream &operator<<(std::ostream &stream, const WeekDay day) {
  switch (day) {
    case MONDAY:
      stream << "Monday";
    case TUESDAY:
      stream << "Tuesday";
    case WEDNESDAY:
      stream << "Wednesday";
    case THURSDAY:
      stream << "Thursday";
    case FRIDAY:
      stream << "Friday";
    case SATURDAY:
      stream << "Saturday";
    case SUNDAY:
      stream << "Sunday";

  return stream;

The boilerplate code is indeed pretty big compared to some other methods presented in this thread. Still, it has the avantage of being pretty straightforward and easy to use.

std::cout << "First day of the week is " << WeekDay::Monday << std::endl;

Convert char to int in C#

I'm using Compact Framework 3.5, and not has a "char.Parse" method. I think is not bad to use the Convert class. (See CLR via C#, Jeffrey Richter)

char letterA = Convert.ToChar(65);
letterA = '?';
ushort valueA = Convert.ToUInt16(letterA);
char japaneseA = Convert.ToChar(valueA);

Works with ASCII char or Unicode char

What is the difference between '/' and '//' when used for division?

In Python 3.x, 5 / 2 will return 2.5 and 5 // 2 will return 2. The former is floating point division, and the latter is floor division, sometimes also called integer division.

In Python 2.2 or later in the 2.x line, there is no difference for integers unless you perform a from __future__ import division, which causes Python 2.x to adopt the 3.x behavior.

Regardless of the future import, 5.0 // 2 will return 2.0 since that's the floor division result of the operation.

You can find a detailed description at

How to use a class from one C# project with another C# project

If you have two projects in one solution folder.Just add the Reference of the Project into another.using the Namespace you can get the classes. While Creating the object for that the requried class. Call the Method which you want.


class FirstClass()
   public string Name()
      return "James";

Here add reference to the Second Project


class SeccondClass
    FirstProject.FirstClass obj=new FirstProject.FirstClass();

Calling a Function defined inside another function in Javascript

You are not calling the function inner, just defining it.

function outer() { 
    function inner() {

    inner(); //Call the inner function


How to check if a user is logged in (how to properly use user.is_authenticated)?

Following block should work:

    {% if user.is_authenticated %}
        <p>Welcome {{ user.username }} !!!</p>       
    {% endif %}

How to access your website through LAN in ASP.NET

You will need to configure you IIS (assuming this is the web server your are/will using) allowing access from WLAN/LAN to specific users (or anonymous). Allow IIS trought your firewall if you have one.

Your application won't need to be changed, that's just networking problems ans configuration you will have to face to allow acces only trought LAN and WLAN.

Select Row number in postgres

SELECT tab.*,
    row_number() OVER () as rnum
  FROM tab;

Here's the relevant section in the docs.

P.S. This, in fact, fully matches the answer in the referenced question.

How to maximize the browser window in Selenium WebDriver (Selenium 2) using C#?

There's an outstanding issue to add this functionality to WebDriver, which can be tracked here:

A workaround would be to use the JavascriptExector as follows:

public void resizeTest() {
((IJavaScriptExecutor)driver).ExecuteScript("window.resizeTo(1024, 768);");

How to get xdebug var_dump to show full object/array

Or you can use an alternative:

It works with zero set up and has much more features than Xdebug's var_dump anyway. To bypass the nested limit on the fly with Kint, just use

 +d( $variable ); // append `+` to the dump call

TortoiseSVN Error: "OPTIONS of 'https://...' could not connect to server (...)"

This can occur because of you are trying to checking out the repository by accessing it via a proxy server without enabling the proxy server in the place you need to change the settings in TortoiseSvn. So if you are using a proxy server make sure that you put a tick in "Enable Proxy Server" in Settings->Network and give your Server address and Port number in the relevant places. Now try to check out again.

Run react-native on android emulator

On macOs I manage to fix this by adding:

export ANDROID_HOME=$HOME/Library/Android/sdk
export PATH=$PATH:$ANDROID_HOME/emulator
export PATH=$PATH:$ANDROID_HOME/tools/bin
export PATH=$PATH:$ANDROID_HOME/platform-tools

to ~/.zsh_profile file.

and than type to your terminal

source $HOME/.zsh_profile

The issue was caused by using iTerm2 shell so it's required to edit its own config instead of default $HOME/.bash_profile as described in the official documentation

How to remove package using Angular CLI?

It's an open issue #900 on GitHub, unfortunately at this point of time it looks that in Angular CLI there's nothing like ng remove/rm/..., only using npm uninstall DEPENDENCY is the current workaround.

What does "hard coded" mean?


In a college there are many students doing different courses, and after an examination we have to prepare a marks card showing grade. I can calculate grade two ways

1. I can write some code like this

    if(totalMark <= 100 && totalMark > 90) { grade = "A+"; }
    else if(totalMark <= 90 && totalMark > 80) { grade = "A"; }
    else if(totalMark <= 80 && totalMark > 70) { grade = "B"; }
    else if(totalMark <= 70 && totalMark > 60) { grade = "C"; }

2. You can ask user to enter grade definition some where and save that data

Something like storing into a database table enter image description here

In the first case the grade is common for all the courses and if the rule changes the code needs to be changed. But for second case we are giving user the provision to enter grade based on their requirement. So the code will be not be changed when the grade rules changes.

That's the important thing when you give more provision for users to define business logic. The first case is nothing but Hard Coding.

So in your question if you ask the user to enter the path of the file at the start, then you can remove the hard coded path in your code.

How to yum install Node.JS on Amazon Linux

I usually use NVM to install node on server. It gives me option to install multiple version of nodejs. Commands are given below

curl -o- | bash

then check if it's install properly

command -v nvm

after that, run this to install latest version

nvm install node


nvm install 11

How is malloc() implemented internally?

The sbrksystem call moves the "border" of the data segment. This means it moves a border of an area in which a program may read/write data (letting it grow or shrink, although AFAIK no malloc really gives memory segments back to the kernel with that method). Aside from that, there's also mmap which is used to map files into memory but is also used to allocate memory (if you need to allocate shared memory, mmap is how you do it).

So you have two methods of getting more memory from the kernel: sbrk and mmap. There are various strategies on how to organize the memory that you've got from the kernel.

One naive way is to partition it into zones, often called "buckets", which are dedicated to certain structure sizes. For example, a malloc implementation could create buckets for 16, 64, 256 and 1024 byte structures. If you ask malloc to give you memory of a given size it rounds that number up to the next bucket size and then gives you an element from that bucket. If you need a bigger area malloc could use mmap to allocate directly with the kernel. If the bucket of a certain size is empty malloc could use sbrk to get more space for a new bucket.

There are various malloc designs and there is propably no one true way of implementing malloc as you need to make a compromise between speed, overhead and avoiding fragmentation/space effectiveness. For example, if a bucket runs out of elements an implementation might get an element from a bigger bucket, split it up and add it to the bucket that ran out of elements. This would be quite space efficient but would not be possible with every design. If you just get another bucket via sbrk/mmap that might be faster and even easier, but not as space efficient. Also, the design must of course take into account that "free" needs to make space available to malloc again somehow. You don't just hand out memory without reusing it.

If you're interested, the OpenSER/Kamailio SIP proxy has two malloc implementations (they need their own because they make heavy use of shared memory and the system malloc doesn't support shared memory). See:

Then you could also have a look at the GNU libc malloc implementation, but that one is very complicated, IIRC.

How do I configure Maven for offline development?

A new plugin has appeared to fix shortcomings of mvn dependency:go-offline:

Add it in your pom, then run mvn -T1C de.qaware.maven:go-offline-maven-plugin:resolve-dependencies. Once you've setup all dynamic dependencies, maven won't try to download anything again (until you update versions).

Ubuntu says "bash: ./program Permission denied"

Sounds like you don't have the execute flag set on the file permissions, try:

chmod u+x program_name

How to fit Windows Form to any screen resolution?

Probably a maximized Form helps, or you can do this manually upon form load:

Code Block

this.Location = new Point(0, 0);

this.Size = Screen.PrimaryScreen.WorkingArea.Size;

And then, play with anchoring, so the child controls inside your form automatically fit in your form's new size.

Hope this helps,

Making text background transparent but not text itself

Don't use opacity for this, set the background to an RGBA-value instead to only make the background semi-transparent. In your case it would be like this.

.content {
    background: rgb(204, 204, 204); /* Fallback for older browsers without RGBA-support */
    background: rgba(204, 204, 204, 0.5);

See for more info and samples of rgba-values in css.

Thymeleaf: Concatenation - Could not parse as expression

Note that with | char, you can get a warning with your IDE, for exemple I get warning with the last version of IntelliJ, So the best solution it's to use this syntax:

th:text="${'static_content - ' + you_variable}"

How can I capture packets in Android?

It's probably worth mentioning that for http/https some people proxy their browser traffic through Burp/ZAP or another intercepting "attack proxy". A thread that covers options for this on Android devices can be found here:

T-sql - determine if value is integer

Use TRY_CONVERT which is an SQL alternative to TryParse in .NET. IsNumeric() isn’t aware that empty strings are counted as (integer)zero, and that some perfectly valid money symbols, by themselves, are not converted to (money)zero. reference

                 ELSE 0


$ cd $HOME
$ wget --quiet
$ export SSL_CERT_FILE=$HOME/cacert.pem


Allowed characters in filename

Here is the code to clean file name in python.

import unicodedata

def clean_name(name, replace_space_with=None):
    Remove invalid file name chars from the specified name

    :param name: the file name
    :param replace_space_with: if not none replace space with this string
    :return: a valid name for Win/Mac/Linux

    # ref:
    # ref:
    # No control chars, no: /, \, ?, %, *, :, |, ", <, >

    # remove control chars
    name = ''.join(ch for ch in name if unicodedata.category(ch)[0] != 'C')

    cleaned_name = re.sub(r'[/\\?%*:|"<>]', '', name)
    if replace_space_with is not None:
        return cleaned_name.replace(' ', replace_space_with)
    return cleaned_name

Set padding for UITextField with UITextBorderStyleNone

@Evil trout's answer is great. I have been using this approach for quite a some time now. The only thing it lacks is "dealing with numerous text fields". I tried other approaches but does not seem to work.

Subclassing UITextField just to add a padding didn't make any sense to me. So, I iterated over all UITextFields to add the padding.

-(void) addPaddingToAllTextFields:(UIView*)view {

    for(id currentView in [view subviews]){
        if([currentView isKindOfClass:[UITextField class]]) {
            // Change value of CGRectMake to fit ur need
            [currentView setLeftView:[[UIView alloc] initWithFrame:CGRectMake(0, 0, 10, 20)]];
            [currentView setLeftViewMode:UITextFieldViewModeAlways];

        if([currentView respondsToSelector:@selector(subviews)]){
            [textfieldarray addObjectsFromArray:[self addPaddingToAllTextFields:currentView]];

Case Statement Equivalent in R

There is a switch statement but I can never seem to get it to work the way I think it should. Since you have not provided an example I will make one using a factor variable:

 dft <-data.frame(x = sample(letters[1:8], 20, replace=TRUE))
[1] "a" "b" "c" "d" "e" "f" "g" "h"

If you specify the categories you want in an order appropriate to the reassignment you can use the factor or numeric variables as an index:

c("abc", "abc", "abc", "def", "def", "def", "g", "h")[dft$x]
 [1] "def" "h"   "g"   "def" "def" "abc" "h"   "h"   "def" "abc" "abc" "abc" "h"   "h"   "abc"
[16] "def" "abc" "abc" "def" "def"

dft$y <- c("abc", "abc", "abc", "def", "def", "def", "g", "h")[dft$x] str(dft)
'data.frame':   20 obs. of  2 variables:
 $ x: Factor w/ 8 levels "a","b","c","d",..: 4 8 7 4 6 1 8 8 5 2 ...
 $ y: chr  "def" "h" "g" "def" ...

I later learned that there really are two different switch functions. It's not generic function but you should think about it as either switch.numeric or switch.character. If your first argument is an R 'factor', you get switch.numeric behavior, which is likely to cause problems, since most people see factors displayed as character and make the incorrect assumption that all functions will process them as such.

How to get current time and date in C++?

Yes and you can do so with formatting rules specified by the currently-imbued locale:

#include <iostream>
#include <iterator>
#include <string>

class timefmt
    timefmt(std::string fmt)
        : format(fmt) { }

    friend std::ostream& operator <<(std::ostream &, timefmt const &);

    std::string format;

std::ostream& operator <<(std::ostream& os, timefmt const& mt)
    std::ostream::sentry s(os);

    if (s)
        std::time_t t = std::time(0);
        std::tm const* tm = std::localtime(&t);
        std::ostreambuf_iterator<char> out(os);

            .put(out, os, os.fill(),
                 tm, &mt.format[0], &mt.format[0] + mt.format.size());


    return os;

int main()
    std::cout << timefmt("%c");

Output: Fri Sep 6 20:33:31 2013

Git log to get commits only for a specific branch

In my situation, we are using Git Flow and GitHub. All you need to do this is: Compare your feature branch with your develop branch on GitHub.

It will show the commits only made to your feature branch.

For example:

Splitting words into letters in Java

You can use

String [] strArr = Str.split("");

Get user's current location

The old freegeoip API is now deprecated and will be discontinued on July 1st, 2018.

The new API is from You have to create the account in ipstack.Then you can use the access key in the API url.

$url = "";
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_PROXYPORT, 3128);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
$response = curl_exec($ch);
$response = json_decode($response);
$city  = $response->city; //You can get all the details like longitude,latitude from the $response .

For more information check here :/

Equivalent of *Nix 'which' command in PowerShell?

Here is an actual *nix equivalent, i.e. it gives *nix-style output.

Get-Command <your command> | Select-Object -ExpandProperty Definition

Just replace with whatever you're looking for.

PS C:\> Get-Command notepad.exe | Select-Object -ExpandProperty Definition

When you add it to your profile, you will want to use a function rather than an alias because you can't use aliases with pipes:

function which($name)
    Get-Command $name | Select-Object -ExpandProperty Definition

Now, when you reload your profile you can do this:

PS C:\> which notepad

How to create strings containing double quotes in Excel formulas?

I use a function for this (if the workbook already has VBA).

Function Quote(inputText As String) As String
  Quote = Chr(34) & inputText & Chr(34)
End Function

This is from Sue Mosher's book "Microsoft Outlook Programming". Then your formula would be:

="Maurice "&Quote("Rocket")&" Richard"

This is similar to what Dave DuPlantis posted.

Deprecated Gradle features were used in this build, making it incompatible with Gradle 5.0

Solution for the issue: deprecated gradle features were used in this build making it incompatible with gradle 6.0. android studio This provided solution worked for me.

First change the classpath in dependencies of build.gradle of your project From: classpath '' To: classpath ''

Then make changes in the file this file exists in the Project's gradle>wrapper folder From: distributionUrl=https\:// To: distributionUrl=https\://

Then Sync your gradle.

Open directory using C

Parameters passed to the C program executable is nothing but an array of string(or character pointer),so memory would have been already allocated for these input parameter before your program access these parameters,so no need to allocate buffer,and that way you can avoid error handling code in your program as well(Reduce chances of segfault :)).

How to detect online/offline event cross-browser?

well, you can try the javascript plugin which can monitor the browser connection in real time and notifies the user if internet or the browsers connection with the internet went down.

Wiremonkey Javascript plugin and the demo you can find here

HTML/CSS: Making two floating divs the same height

Several years ago, the float property used to solve that problem with the table approach using display: table; and display: table-row; and display: table-cell;.

But now with the flex property, you can solve it with 3 lines of code: display: flex; and flex-wrap: wrap; and flex: 1 0 50%;

.parent {
    display: flex;
    flex-wrap: wrap;

.child {
 // flex: flex-grow flex-shrink flex-basis;
    flex: 1 0 50%;

1 0 50% are the flex values we gave to: flex-grow flex-shrink flex-basis respectively. It's a relatively new shortcut in flexbox to avoid typing them individually. I hope this helps someone out there

Difference between "char" and "String" in Java

char is a primitive type, and it can hold a single character.

String is instead a reference type, thus a full-blown object. It can hold any number of characters (internally, String objects save them in a char array).

Primitive types in Java have advantages in term of speed and memory footprint. But they are not real objects, so there are some possibilities you lose using them. They cannot be used as Generic type parameters, they could not have methods or fields, and so on.

However, every Java primitive type has a corresponding full-blown object, and the conversion between them is done automagically by the compiler (this is called autoboxing).

You can for example do:

int i=12;
Integer l=i;

The compiler takes care of converting the int to a Integer.

Convert Variable Name to String?

Here is a succinct variation that lets you specify any directory. The issue with using directories to find anything is that multiple variables can have the same value. So this code returns a list of possible variables.

def varname( var, dir=locals()):
  return [ key for key, val in dir.items() if id( val) == id( var)]

How do I 'overwrite', rather than 'merge', a branch on another branch in Git?

How about:

git branch -D email
git checkout staging
git checkout -b email
git push origin email --force-with-lease

What is the significance of load factor in HashMap?

What is load factor ?

The amount of capacity which is to be exhausted for the HashMap to increase its capacity ?

Why load factor ?

Load factor is by default 0.75 of the initial capacity (16) therefore 25% of the buckets will be free before there is an increase in the capacity & this makes many new buckets with new hashcodes pointing to them to exist just after the increase in the number of buckets.

Now why should you keep many free buckets & what is the impact of keeping free buckets on the performance ?

If you set the loading factor to say 1.0 then something very interesting might happen.

Say you are adding an object x to your hashmap whose hashCode is 888 & in your hashmap the bucket representing the hashcode is free , so the object x gets added to the bucket, but now again say if you are adding another object y whose hashCode is also 888 then your object y will get added for sure BUT at the end of the bucket (because the buckets are nothing but linkedList implementation storing key,value & next) now this has a performance impact ! Since your object y is no longer present in the head of the bucket if you perform a lookup the time taken is not going to be O(1) this time it depends on how many items are there in the same bucket. This is called hash collision by the way & this even happens when your loading factor is less than 1.

Correlation between performance , hash collision & loading factor ?

Lower load factor = more free buckets = less chances of collision = high performance = high space requirement.

Correct me if i am wrong somewhere.

What's the foolproof way to tell which version(s) of .NET are installed on a production Windows Server?

Well, like Dean said, you can look at the registry and do what he did. To check if he really has CLR .NET Framework installed, you should look for the MSCorEE.dll file in the %SystemRoot%\System32 directory.

Python: Number of rows affected by cursor.execute("SELECT ...)

From PEP 249, which is usually implemented by Python database APIs:

Cursor Objects should respond to the following methods and attributes:


This read-only attribute specifies the number of rows that the last .execute*() produced (for DQL statements like 'select') or affected (for DML statements like 'update' or 'insert').

But be careful—it goes on to say:

The attribute is -1 in case no .execute*() has been performed on the cursor or the rowcount of the last operation is cannot be determined by the interface. [7]

Future versions of the DB API specification could redefine the latter case to have the object return None instead of -1.

So if you've executed your statement, and it works, and you're certain your code will always be run against the same version of the same DBMS, this is a reasonable solution.

Bootstrap - Uncaught TypeError: Cannot read property 'fn' of undefined

I went back to jquery-2.2.4.min.js and it works.

Using Jquery AJAX function with datatype HTML

var datos = $("#id_formulario").serialize();
    url: "url.php",      
    type: "POST",                   
    dataType: "html",                 
    data: datos,                 
    success: function (prueba) { 

});//FIN  AJAX

Batch Script to Run as Administrator

Solutions that did not work

No: The - create a shortcut [ -> Compatibility -> "run this program as an administrator" ] solution does not work.

This option is greyed out in Windows 7. Even with UAC disabled

No: The runas /env /user:domain\Administrator <program.exe/command you want to execute> is also not sufficient because it will prompt the user for the admin password.

Solution that worked

Yes: Disable UAC -> Create a job using task scheduler, this worked for me.

  • Create a job under task scheduler and make it run as a user with administrator permissions.
  • Explicitly mark: "Run with highest privileges"
  • Disable UAC so there will be no prompt to run this task

You can let the script enable UAC afterwards by editing the registry if you would want. In my case this script is ran only once by creation of a windows virtual machine, where UAC is disabled in the image.

Still looking forward for the best approach for a script run as admin without too much hassle.

How to set IntelliJ IDEA Project SDK

For a new project select the home directory of the jdk

eg C:\Java\jdk1.7.0_99 or C:\Program Files\Java\jdk1.7.0_99

For an existing project.

1) You need to have a jdk installed on the system.

for instance in


2) go to project structure under File menu ctrl+alt+shift+S

3) SDKs is located under Platform Settings. Select it.

4) click the green + up the top of the window.

5) select JDK (I have to use keyboard to select it do not know why).

select the home directory for your jdk installation.

should be good to go.

Concatenating strings doesn't work as expected

std::string a = "Hello ";
std::string b = "World ";
std::string c = a;

Android - get children inside a View?

This method takes all views inside a layout, this is similar to Alexander Kulyakhtin's answer. The difference is, it accepts any type of parent layouts & returns an Array List of views.

public List<View> getAllViews(ViewGroup layout){
        List<View> views = new ArrayList<>();
        for(int i =0; i< layout.getChildCount(); i++){
        return views;

Terminating a Java Program

  1. System.exit() is a method that causes JVM to exit.
  2. return just returns the control to calling function.
  3. return 8 will return control and value 8 to calling method.

How do I get started with Node.js

First, learn the core concepts of Node.js:

Then, you're going to want to see what the community has to offer:

The gold standard for Node.js package management is NPM.

Finally, you're going to want to know what some of the more popular packages are for various tasks:

Useful Tools for Every Project:

  • Underscore contains just about every core utility method you want.
  • Lo-Dash is a clone of Underscore that aims to be faster, more customizable, and has quite a few functions that underscore doesn't have. Certain versions of it can be used as drop-in replacements of underscore.
  • TypeScript makes JavaScript considerably more bearable, while also keeping you out of trouble!
  • JSHint is a code-checking tool that'll save you loads of time finding stupid errors. Find a plugin for your text editor that will automatically run it on your code.

Unit Testing:

  • Mocha is a popular test framework.
  • Vows is a fantastic take on asynchronous testing, albeit somewhat stale.
  • Expresso is a more traditional unit testing framework.
  • node-unit is another relatively traditional unit testing framework.
  • AVA is a new test runner with Babel built-in and runs tests concurrently.

Web Frameworks:

  • Express.js is by far the most popular framework.
  • Koa is a new web framework designed by the team behind Express.js, which aims to be a smaller, more expressive, and more robust foundation for web applications and APIs.
  • sails.js the most popular MVC framework for Node.js, and is based on express. It is designed to emulate the familiar MVC pattern of frameworks like Ruby on Rails, but with support for the requirements of modern apps: data-driven APIs with a scalable, service-oriented architecture.
  • Meteor bundles together jQuery, Handlebars, Node.js, WebSocket, MongoDB, and DDP and promotes convention over configuration without being a Ruby on Rails clone.
  • Tower (deprecated) is an abstraction of a top of Express.js that aims to be a Ruby on Rails clone.
  • Geddy is another take on web frameworks.
  • RailwayJS is a Ruby on Rails inspired MVC web framework.
  • Sleek.js is a simple web framework, built upon Express.js.
  • Hapi is a configuration-centric framework with built-in support for input validation, caching, authentication, etc.
  • Trails is a modern web application framework. It builds on the pedigree of Rails and Grails to accelerate development by adhering to a straightforward, convention-based, API-driven design philosophy.

  • Danf is a full-stack OOP framework providing many features in order to produce a scalable, maintainable, testable and performant applications and allowing to code the same way on both the server (Node.js) and client (browser) sides.

  • Derbyjs is a reactive full-stack JavaScript framework. They are using patterns like reactive programming and isomorphic JavaScript for a long time.

  • is a powerful Node.js framework for creating APIs and easily connecting to backend data sources. It has an Angular.js SDK and provides SDKs for iOS and Android.

Web Framework Tools:


  • Connect is the Rack or WSGI of the Node.js world.
  • Request is a very popular HTTP request library.
  • is handy for building WebSocket servers.

Command Line Interaction:

  • minimist just command line argument parsing.
  • Yargs is a powerful library for parsing command-line arguments.
  • Commander.js is a complete solution for building single-use command-line applications.
  • Vorpal.js is a framework for building mature, immersive command-line applications.
  • Chalk makes your CLI output pretty.

Code Generators:

  • Yeoman Scaffolding tool from the command-line.
  • Skaffolder Code generator with visual and command-line interface. It generates a customizable CRUD application starting from the database schema or an OpenAPI 3.0 YAML file.

Work with streams:

Change the encoding of a file in Visual Studio Code

So here's how to do that:

In the bottom bar of VSCode, you'll see the label UTF-8. Click it. A popup opens. Click Save with encoding. You can now pick a new encoding for that file.

Alternatively, you can change the setting globally in Workspace/User settings using the setting "files.encoding": "utf8". If using the graphical settings page in VSCode, simply search for encoding. Do note however that this only applies to newly created files.

versionCode vs versionName in Android Manifest

android:versionCode — An integer value that represents the version of the application code, relative to other versions.

The value is an integer so that other applications can programmatically evaluate it, for example to check an upgrade or downgrade relationship. You can set the value to any integer you want, however you should make sure that each successive release of your application uses a greater value. The system does not enforce this behavior, but increasing the value with successive releases is normative.

android:versionName — A string value that represents the release version of the application code, as it should be shown to users.

The value is a string so that you can describe the application version as a .. string, or as any other type of absolute or relative version identifier.

As with android:versionCode, the system does not use this value for any internal purpose, other than to enable applications to display it to users. Publishing services may also extract the android:versionName value for display to users.

Typically, you would release the first version of your application with versionCode set to 1, then monotonically increase the value with each release, regardless whether the release constitutes a major or minor release. This means that the android:versionCode value does not necessarily have a strong resemblance to the application release version that is visible to the user (see android:versionName, below). Applications and publishing services should not display this version value to users.

Rounding to two decimal places in Python 2.7?

You can use str.format(), too:

>>> print "financial return of outcome 1 = {:.2f}".format(1.23456)
financial return of outcome 1 = 1.23

How can I determine the current CPU utilization from the shell?

Linux does not have any system variables that give the current CPU utilization. Instead, you have to read /proc/stat several times: each column in the cpu(n) lines gives the total CPU time, and you have to take subsequent readings of it to get percentages. See this document to find out what the various columns mean.

Check whether a string matches a regex in JS



console.log( /^[a-z\d]{5,}$/.test("abc123") );_x000D_
console.log( /^[a-z\d]{5,}$/.test("ab12") );

Lotus Notes email as an attachment to another email

Copy the mail as a document link (right click on the mail and you should get this option) and paste it in the new mail. This worked for me

Pandas: Convert Timestamp to

Use the .date method:

In [11]: t = pd.Timestamp('2013-12-25 00:00:00')

In [12]:
Out[12]:, 12, 25)

In [13]: ==, 12, 25)
Out[13]: True

To compare against a DatetimeIndex (i.e. an array of Timestamps), you'll want to do it the other way around:

In [21]: pd.Timestamp(, 12, 25))
Out[21]: Timestamp('2013-12-25 00:00:00')

In [22]: ts = pd.DatetimeIndex([t])

In [23]: ts == pd.Timestamp(, 12, 25))
Out[23]: array([ True], dtype=bool)

link with target="_blank" does not open in new tab in Chrome

Because JavaScript is handling the click event. When you click, the following code is called:

el.addEvent('click', function(e){
        new Event(e).stop();
        if( == i){
   = null;
            obj.options.onClose(this.href, i);
   = i;
            obj.options.onOpen(this.href, i);

The onOpen manually changes the location.

Edit: Regarding your comment... If you can modify ImageMenu.js, you could update the script which calls onClose to pass the a element object (this, rather than this.href)

obj.options.onClose(this, i);

Then update your ImageMenu instance, with the following onOpen change:

window.addEvent('domready', function(){
    var myMenu = new ImageMenu($$('#imageMenu a'), {
        openWidth: 310,
        border: 2,
        onOpen: function(e, i) {
            if ( === '_blank') {
            } else {
                location = e.href;

This would check for the target property of the element to see if it's _blank, and then call, if found.

If you'd prefer not to modify ImageMenu.js, another option would be to modify your links to identify them in your onOpen handler. Say something like:

<a href="" target="_blank" style="width: 105px;"></a>

Then, update your onOpen call to:

onOpen: function(e, i) {
    if (e.indexOf('_b=1') > -1) {;   
    } else {
        location = e;

The only downside to this is the user sees the hash on hover.

Finally, if the number of links that you plan to open in a new window are low, you could create a map and check against that. Something like:

var linksThatOpenInANewWindow = {
    '': 1

onOpen: function(e, i) {
    if (linksThatOpenInANewWindow[e] === 1) {;   
    } else {
        location = e

The only downside is maintenance, depending on the number of links.

Others have suggested modifying the link (using # or javascript:) and adding an inline event handler (onclick) - I don't recommend that at all as it breaks links when JS is disabled/not supported.

What is the difference between Google App Engine and Google Compute Engine?

Google Compute Engine (GCE)

Virtual Machines (VMs) hosted in the cloud. Before the cloud, these were often called Virtual Private Servers (VPS). You'd use these the same way you'd use a physical server, where you install and configure the operating system, install your application, install the database, keep the OS up-to-date, etc. This is known as Infrastructure-as-a-Service (IaaS).

VMs are most useful when you have an existing application running on a VM or server in your datacenter, and want to easily migrate it to GCP.

Google App Engine

App Engine hosts and runs your code, without requiring you to deal with the operating system, networking, and many of the other things you'd have to manage with a physical server or VM. Think of it as a runtime, which can automatically deploy, version, and scale your application. This is called Platform-as-a-Service (PaaS).

App Engine is most useful when you want automated deployment and automated scaling of your application. Unless your application requires custom OS configuration, App Engine is often advantageous over configuring and managing VMs by hand.

Find in Files: Search all code in Team Foundation Server

We have set up a solution for Team Foundation Server Source Control (not SourceSafe as you mention) similar to what Grant suggests; scheduled TF Get, Search Server Express. However the IFilter used for C# files (text) was not giving the results we wanted, so we convert source files to .htm files. We can now add additional meta-data to the files such as:

  • Author (we define it as the person that last checked in the file)
  • Color coding (on our todo-list)
  • Number of changes indicating potential design problems (on our todo-list)
  • Integrate with the VSTS IDE like Koders SmartSearch feature
  • etc.

We would however prefer a protocolhandler for TFS Source Control, and a dedicated source code IFilter for a much more targeted solution.

How do I get the selected element by name and then get the selected value from a dropdown using jQuery?

Remove the onchange event from the HTML Markup and bind it in your document ready event

<select  name="a[b]" >
     <option value='Choice 1'>Choice 1</option>
     <option value='Choice 2'>Choice 2</option>

and Script


Working sample :

Convert integer into byte array (Java)

You can use BigInteger:

From Integers:

byte[] array = BigInteger.valueOf(0xAABBCCDD).toByteArray();
// --> {-86, -69, -52, -35 }

The returned array is of the size that is needed to represent the number, so it could be of size 1, to represent 1 for example. However, the size cannot be more than four bytes if an int is passed.

From Strings:

BigInteger v = new BigInteger("AABBCCDD", 16);
byte[] array = v.toByteArray();

However, you will need to watch out, if the first byte is higher 0x7F (as is in this case), where BigInteger would insert a 0x00 byte to the beginning of the array. This is needed to distinguish between positive and negative values.

How to vertically center <div> inside the parent element with CSS?

You can vertically align a div in another div. See this example on JSFiddle or consider the example below.


<div class="outerDiv">
    <div class="innerDiv"> My Vertical Div </div>


.outerDiv {
    display: inline-flex;  // <-- This is responsible for vertical alignment
    height: 400px;
    background-color: red;
    color: white;

.innerDiv {
    margin: auto 5px;   // <-- This is responsible for vertical alignment
    background-color: green;   

The .innerDiv's margin must be in this format: margin: auto *px;

[Where, * is your desired value.]

display: inline-flex is supported in the latest (updated/current version) browsers with HTML5 support.

It may not work in Internet Explorer :P :)

Always try to define a height for any vertically aligned div (i.e. innerDiv) to counter compatibility issues.

Can I run Keras model on gpu?

Of course. if you are running on Tensorflow or CNTk backends, your code will run on your GPU devices defaultly.But if Theano backends, you can use following

Theano flags:

"THEANO_FLAGS=device=gpu,floatX=float32 python"

PHP json_decode() returns NULL with valid JSON?

For my case, it's because of the single quote in JSON string.

JSON format only accepts double-quotes for keys and string values.


$jsonString = '{\'hello\': \'PHP\'}'; // valid value should be '{"hello": "PHP"}'
$json = json_decode($jsonString);
print $json; // null

I got this confused because of Javascript syntax. In Javascript, of course, we can do like this:

let json = {
    hello: 'PHP' // no quote for key, single quote for string value

// OR:
json = {
    'hello': 'PHP' // single quote for key and value

but later when convert those objects to JSON string:

JSON.stringify(json); // "{"hello":"PHP"}"

Requests -- how to tell if you're getting a 404

Look at the r.status_code attribute:

if r.status_code == 404:
    # A 404 was issued.


>>> import requests
>>> r = requests.get('')
>>> r.status_code

If you want requests to raise an exception for error codes (4xx or 5xx), call r.raise_for_status():

>>> r = requests.get('')
>>> r.raise_for_status()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "requests/", line 664, in raise_for_status
    raise http_error
requests.exceptions.HTTPError: 404 Client Error: NOT FOUND
>>> r = requests.get('')
>>> r.raise_for_status()
>>> # no exception raised.

You can also test the response object in a boolean context; if the status code is not an error code (4xx or 5xx), it is considered ‘true’:

if r:
    # successful response

If you want to be more explicit, use if r.ok:.

Switch with if, else if, else, and loops inside case

but i only wanted the for statement to be attached to the if statement, not the else if statements as well.

Well get rid of the else then. If the else if is not supposed to be part of the for then write it as:

           for(int i=0; i<something_in_the_array.length;i++)

                break;  // redundant now

           else if(whatever_value==3)
                break;  // redundant now

Having said that:

  • it is not at all clear what you are really trying to do here,
  • not having the else part in the loop doesn't seem to make a lot of sense here,
  • a lot of people (myself included) think it is to always use braces ... so that people don't get tripped up by incorrect indentation when reading your code. (And in this case, it might help us figure out what you are really trying to do here ...)

Finally, braces are less obtrusive if you put the opening brace on the end of the previous line; e.g.

  if (something) {

rather than:

  if (something) 

How to export and import environment variables in windows?

I would use the SET command from the command prompt to export all the variables, rather than just PATH as recommended above.

C:\> SET >> allvariables.txt

To import the variablies, one can use a simple loop:

C:\> for /F %A in (allvariables.txt) do SET %A

HTML5: Slider with two inputs possible?

I've been looking for a lightweight, dependency free dual slider for some time (it seemed crazy to import jQuery just for this) and there don't seem to be many out there. I ended up modifying @Wildhoney's code a bit and really like it.

function getVals(){_x000D_
  // Get slider values_x000D_
  var parent = this.parentNode;_x000D_
  var slides = parent.getElementsByTagName("input");_x000D_
    var slide1 = parseFloat( slides[0].value );_x000D_
    var slide2 = parseFloat( slides[1].value );_x000D_
  // Neither slider will clip the other, so make sure we determine which is larger_x000D_
  if( slide1 > slide2 ){ var tmp = slide2; slide2 = slide1; slide1 = tmp; }_x000D_
  var displayElement = parent.getElementsByClassName("rangeValues")[0];_x000D_
      displayElement.innerHTML = slide1 + " - " + slide2;_x000D_
window.onload = function(){_x000D_
  // Initialize Sliders_x000D_
  var sliderSections = document.getElementsByClassName("range-slider");_x000D_
      for( var x = 0; x < sliderSections.length; x++ ){_x000D_
        var sliders = sliderSections[x].getElementsByTagName("input");_x000D_
        for( var y = 0; y < sliders.length; y++ ){_x000D_
          if( sliders[y].type ==="range" ){_x000D_
            sliders[y].oninput = getVals;_x000D_
            // Manually trigger event first time to display values_x000D_
  section.range-slider {_x000D_
    position: relative;_x000D_
    width: 200px;_x000D_
    height: 35px;_x000D_
    text-align: center;_x000D_
section.range-slider input {_x000D_
    pointer-events: none;_x000D_
    position: absolute;_x000D_
    overflow: hidden;_x000D_
    left: 0;_x000D_
    top: 15px;_x000D_
    width: 200px;_x000D_
    outline: none;_x000D_
    height: 18px;_x000D_
    margin: 0;_x000D_
    padding: 0;_x000D_
section.range-slider input::-webkit-slider-thumb {_x000D_
    pointer-events: all;_x000D_
    position: relative;_x000D_
    z-index: 1;_x000D_
    outline: 0;_x000D_
section.range-slider input::-moz-range-thumb {_x000D_
    pointer-events: all;_x000D_
    position: relative;_x000D_
    z-index: 10;_x000D_
    -moz-appearance: none;_x000D_
    width: 9px;_x000D_
section.range-slider input::-moz-range-track {_x000D_
    position: relative;_x000D_
    z-index: -1;_x000D_
    background-color: rgba(0, 0, 0, 1);_x000D_
    border: 0;_x000D_
section.range-slider input:last-of-type::-moz-range-track {_x000D_
    -moz-appearance: none;_x000D_
    background: none transparent;_x000D_
    border: 0;_x000D_
  section.range-slider input[type=range]::-moz-focus-outer {_x000D_
  border: 0;_x000D_
<!-- This block can be reused as many times as needed -->_x000D_
<section class="range-slider">_x000D_
  <span class="rangeValues"></span>_x000D_
  <input value="5" min="0" max="15" step="0.5" type="range">_x000D_
  <input value="10" min="0" max="15" step="0.5" type="range">_x000D_

Reading a text file with SQL Server

BULK INSERT dbo.temp 

FROM 'c:\temp\file.txt' --- path file in db server 



it work for me but save as by editplus to ansi encoding for multilanguage

How to check if keras tensorflow backend is GPU or CPU version?

Also you can check using Keras backend function:

from keras import backend as K

I test this on Keras (2.1.1)

How to find substring from string?

In C, use the strstr() standard library function:

const char *str = "/user/desktop/abc/post/";
const int exists = strstr(str, "/abc/") != NULL;

Take care to not accidentally find a too-short substring (this is what the starting and ending slashes are for).

String MinLength and MaxLength validation don't work ( mvc)

Try using this attribute, for example for password min length:

[StringLength(100, ErrorMessage = "???????????? ????? ?????? 20 ????????", MinimumLength = User.PasswordMinLength)]

Mockito. Verify method arguments

The other method is to use the org.mockito.internal.matchers.Equals.Equals method instead of redefining one :

verify(myMock).myMethod((inputObject)Mockito.argThat(new Equals(inputObjectWanted)));

Ignore Duplicates and Create New List of Unique Values in Excel

In the worksheet module for the sheet containing the list:

Private Sub Worksheet_Change(ByVal Target As Range)

    Dim rngDest As Range

    If Not Intersect(Target, Me.Columns(1)) Is Nothing Then

        Set rngDest = ThisWorkbook.Sheets("Sheet2").Range("A1")

        Me.Range(Me.Range("A2"), Me.Cells(Rows.Count, 1).End(xlUp)).AdvancedFilter _
            Action:=xlFilterCopy, CopyToRange:=rngDest, Unique:=True

    End If

End Sub

How to build an APK file in Eclipse?

When you run the project on the emulator, the APK file is generated in the bin directory. Keep in mind that just building the project (and not running it) will not output the APK file into the bin directory.

jQuery multiple conditions within if statement


if (!(i == 'InvKey' || i == 'PostDate')) {


if (i != 'InvKey' || i != 'PostDate') {

that says if i does not equals InvKey OR PostDate

How to import or copy images to the "res" folder in Android Studio?

To import files from OS X Finder into Android Studio, just drag the relevant files to your resource folder.

  • Drag & Drop by default moves files to your project (not what you always want)
  • Pressing ? (Alt) while dragging copies files

Don't find a permanent config option for this, but this is the workaround I'm using

Equivalent of Math.Min & Math.Max for Dates?

How about:

public static T Min<T>(params T[] values)
    if (values == null) throw new ArgumentNullException("values");
    var comparer = Comparer<T>.Default;
    switch(values.Length) {
        case 0: throw new ArgumentException();
        case 1: return values[0];
        case 2: return comparer.Compare(values[0],values[1]) < 0
               ? values[0] : values[1];
            T best = values[0];
            for (int i = 1; i < values.Length; i++)
                if (comparer.Compare(values[i], best) < 0)
                    best = values[i];
            return best;
// overload for the common "2" case...
public static T Min<T>(T x, T y)
    return Comparer<T>.Default.Compare(x, y) < 0 ? x : y;

Works with any type that supports IComparable<T> or IComparable.

Actually, with LINQ, another alternative is:

var min = new[] {x,y,z}.Min();

How to change the status bar color in Android?

One more solution:

final View decorView = w.getDecorView();
View view = new View(BaseControllerActivity.this);
final int statusBarHeight = UiUtil.getStatusBarHeight(ContextHolder.get());
view.setLayoutParams(new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, statusBarHeight));

Gridview get Checkbox.Checked value

For run all lines of GridView don't use for loop, use foreach loop like:

foreach (GridViewRow row in yourGridName.Rows) //Running all lines of grid
    if (row.RowType == DataControlRowType.DataRow)
         CheckBox chkRow = (row.Cells[0].FindControl("chkRow") as CheckBox);

         if (chkRow.Checked)
              //if checked do something

get the margin size of an element with jquery

Exemple, for :

<div id="myBlock" style="margin: 10px 0px 15px 5px:"></div>

In this js code :

var myMarginTop = $("#myBlock").css("marginBottom");

The var becomes "15px", a string.

If you want an Integer, to avoid NaN (Not a Number), there is multiple ways.

The fastest is to use native js method :

var myMarginTop = parseInt( $("#myBlock").css("marginBottom") );

How to check in Javascript if one element is contained within another

You can use the contains method

var result = parent.contains(child);

or you can try to use compareDocumentPosition()

var result = nodeA.compareDocumentPosition(nodeB);

The last one is more powerful: it return a bitmask as result.

"Please provide a valid cache path" error in laravel

Ensure the below folders in storage directory:

  • logs
  • framework
  • framework/cache
  • framework/cache/data
  • framework/sessions
  • framework/testing
  • framework/views

Below is a command-line snippet that does for you

cd storage
mkdir logs
mkdir framework
mkdir framework/cache && framework/cache/data
mkdir framework/sessions
mkdir framework/testing
mkdir framework/views
chgrp -R www-data ../storage
chown -R www-data ../storage

What is the difference between MVC and MVVM?

In very short - in MVC Controler is aware of (controls) view, while in MVVM, ViewModel is unaware of who consumes it. ViewModel exposes its observable properties and actions to whoever might be interested in using it. That fact makes testing easier since there is no reference to UI within ViewModel.

Open Excel file for reading with VBA without display

Open the workbook as hidden and then set it as "saved" so that users are not prompted when they close out.

Dim w As Workbooks

Private Sub Workbook_Open()
    Application.ScreenUpdating = False
    Set w = Workbooks
    w.Open Filename:="\\server\PriceList.xlsx", UpdateLinks:=False, ReadOnly:=True 'this is the data file were going to be opening
    ActiveWindow.Visible = False
    Application.ScreenUpdating = True
End Sub

Private Sub Workbook_BeforeClose(Cancel As Boolean)
    w.Item(2).Saved = True 'this will suppress the safe prompt for the data file only
End Sub

This is somewhat derivative of the answer posted by Ashok.

By doing it this way though you will not get prompted to save changes back to the Excel file your reading from. This is great if the Excel file your reading from is intended as a data source for validation. For example if the workbook contains product names and price data it can be hidden and you can show an Excel file that represents an invoice with drop downs for product that validates from that price list.

You can then store the price list on a shared location on a network somewhere and make it read-only.

jQuery UI Dialog with ASP.NET button postback


Using this code solved my problem and it worked in every browser, Internet Explorer 7, Firefox 3, and Google Chrome. I start to love jQuery... It's a cool framework.

I have tested with partial render too, exactly what I was looking for. Great!

<script type="text/javascript">
    function openModalDiv(divname) {
        $('#' + divname).dialog({ autoOpen: false, bgiframe: true, modal: true });
        $('#' + divname).dialog('open');
        $('#' + divname).parent().appendTo($("form:first"));

    function closeModalDiv(divname) {
        $('#' + divname).dialog('close');
<input id="Button1" type="button" value="Open 1" onclick="javascript:openModalDiv('Div1');" />
<div id="Div1" title="Basic dialog" >
    <asp:UpdatePanel ID="UpdatePanel1" runat="server">
          postback test<br />
          <asp:Button ID="but_OK" runat="server" Text="Send request" /><br />
          <asp:TextBox ID="tb_send" runat="server"></asp:TextBox><br />
          <asp:Label ID="lbl_result" runat="server" Text="prova" BackColor="#ff0000></asp:Label>
    <input id="Button2" type="button" value="cancel" onclick="javascript:closeModalDiv('Div1');" />

How do I remove background-image in css?

Since in css3 one might set multiple background images setting "none" will only create a new layer and hide nothing.

I have not found a solution yet...

Comparing two arrays & get the values which are not common

Look at Compare-Object

Compare-Object $a1 $b1 | ForEach-Object { $_.InputObject }

Or if you would like to know where the object belongs to, then look at SideIndicator:

Compare-Object $a1 $b1

React - clearing an input value after form submit

The answers above are incorrect, they will all run weather or not the submission is successful... You need to write an error component that will receive any errors then check if there are errors in state, if there are not then clear the form....

use .then()


 const onSubmit =  e => {
const fd = new FormData();
fd.append("ticketType", ticketType);
fd.append("ticketSubject", ticketSubject);
fd.append("ticketDescription", ticketDescription);
fd.append("itHelpType", itHelpType);
fd.append("ticketPriority", ticketPriority);
fd.append("ticketAttachments", ticketAttachments);
    ticketType: "IT",
    ticketSubject: "",
    ticketDescription: "",
    itHelpType: "",
    ticketPriority: ""


100% Min Height CSS layout

For min-height to work correctly with percentages, while inheriting it's parent node min-height, the trick would be to set the parent node height to 1px and then the child's min-height will work correctly.

Demo page

#1146 - Table 'phpmyadmin.pma_recent' doesn't exist


$cfg['Servers'][$i]['userconfig'] = 'pma__userconfig'; 

Change into:

$Cfg ['Servers'] [$ i] ['table_uiprefs'] = ‘pma_table_uiprefs’;

Then work for me.

How to force IE to reload javascript?

Paolo's general idea (i.e. effectively changing some part of the request uri) is your best bet. However, I'd suggest using a more static value such as a version number that you update when you have changed your script file so that you can still get the performance gains of caching.

So either something like this:

<script src="/my/js/file.js?version=2.1.3" ></script>

or maybe

<script src="/my/js/file.2.1.3.js" ></script>

I prefer the first option because it means you can maintain the one file instead of having to constantly rename it (which for example maintains consistent version history in your source control). Of course either one (as I've described them) would involve updating your include statements each time, so you may want to come up with a dynamic way of doing it, such as replacing a fixed value with a dynamic one every time you deploy (using Ant or whatever).

Can ordered list produce result that looks like 1.1, 1.2, 1.3 (instead of just 1, 2, 3, ...) with css?

        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <meta name="author" content="Sandro Alvares - KingRider">
        <style type="text/css">
            li.title { 
                font-size: 20px; 
                font-weight: lighter; 
                padding: 15px; 
                counter-increment: ordem; 
            .foo { 
                counter-reset: foo; 
                padding-left: 15px; 
            .foo li { 
                list-style-type: none; 
            .foo li:before { 
                counter-increment: foo; 
                content: counter(ordem) "." counter(foo) " "; 
            <li class="title">TITLE ONE</li>
            <ol class="foo">
                <li>text 1 one</li>
                <li>text 1 two</li>
                <li>text 1 three</li>
                <li>text 1 four</li>
            <li class="title">TITLE TWO</li>
            <ol class="foo">
                <li>text 2 one</li>
                <li>text 2 two</li>
                <li>text 2 three</li>
                <li>text 2 four</li>
            <li class="title">TITLE THREE</li>
            <ol class="foo">
                <li>text 3 one</li>
                <li>text 3 two</li>
                <li>text 3 three</li>
                <li>text 3 four</li>


Interview Question: Merge two sorted singly linked lists without creating new nodes

Here is the code on how to merge two sorted linked lists headA and headB:

Node* MergeLists1(Node *headA, Node* headB)
    Node *p = headA;
    Node *q = headB;
    Node *result = NULL; 
    Node *pp = NULL;
    Node *qq = NULL;
    Node *head = NULL;
    int value1 = 0;
    int value2 = 0;
    if((headA == NULL) && (headB == NULL))
        return NULL;
        return headB;
    else if(headB==NULL)
        return headA;
        while((p != NULL) || (q != NULL))
            if((p != NULL) && (q != NULL))
                int value1 = p->data;
                int value2 = q->data;
                if(value1 <= value2)
                    pp = p->next;
                    p->next = NULL;
                    if(result == NULL)
                        head = result = p;
                        result->next = p;
                        result = p;
                    p = pp;
                    qq = q->next;
                    q->next = NULL;
                    if(result == NULL)
                        head = result = q;
                        result->next = q;
                        result = q;
                    q = qq;
                if(p != NULL)
                    pp = p->next;
                    p->next = NULL;
                    result->next = p;
                    result = p;
                    p = pp;
                if(q != NULL)
                    qq = q->next;
                    q->next = NULL;
                    result->next = q;
                    result = q;
                    q = qq;
    return head;

JQuery .on() method with multiple event handlers to one selector

Also, if you had multiple event handlers attached to the same selector executing the same function, you could use

$('table.planning_grid').on('mouseenter mouseleave', function() {
    //JS Code

How to include a quote in a raw Python string

Just to include new Python f String compatible functionality:

var_a = 10

f"""This is my quoted variable: "{var_a}". """

Where can I get a list of Ansible pre-defined variables?

The debug module can be used to analyze variables. Be careful running the following command. In our setup it generates 444709 lines with 16MB:

ansible -m debug -a 'var=hostvars' localhost

I am not sure but it might be necessary to enable facts caching.

If you need just one host use the host name as a key for the hostvars hash:

ansible -m debug -a 'var=hostvars.localhost' localhost

This command will display also group and host variables.

MS-DOS Batch file pause with enter key

The only valid answer would be the pause command.

Though this does not wait specifically for the 'ENTER' key, it waits for any key that is pressed.

And just in case you want it convenient for the user, pause is the best option.

How to place two divs next to each other?

here is the solution:

#wrapper {
    width: 500px;
    border: 1px solid black;
    overflow: auto; /* so the size of the wrapper is alway the size of the longest content */
#first {
    float: left;
    width: 300px;
    border: 1px solid red;
#second {
    border: 1px solid green;
    margin: 0 0 0 302px; /* considering the border you need to use a margin so the content does not float under the first div*/

your demo updated;

VSCode: How to Split Editor Vertically

Use Move editor into Next Group shortcut

Mac: ^+?+->

If you want to change shortcut,

Open command pallette

Mac: ?+shift+p

Select Preferences: Open Keyboard Shortcuts

Search View: Move editor into Next Group

Image height and width not working?

You must write

<img src="theSource" style="width:30px;height:30px;" />

Inline styling will always take precedence over CSS styling. The width and height attributes are being overridden by your stylesheet, so you need to switch to this format.

Can someone provide an example of a $destroy event for scopes in AngularJS?


Here I have created handle-destroy directive.

ctrl.directive('handleDestroy', function() {
    return function(scope, tElement, attributes) {        
        scope.$on('$destroy', function() {
            alert("In destroy of:" + scope.todo.text);

Changing background color of ListView items on Android

Ok, I got it to work like this:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="">
    <item android:state_pressed="false" android:drawable="@color/BackgroundColor" />
    <item android:drawable="@color/transparent" />


How to check if two arrays are equal with JavaScript?

Based on Tim James answer and Fox32's comment, the following should check for nulls, with the assumption that two nulls are not equal.

function arrays_equal(a,b) { return !!a && !!b && !(a<b || b<a); }

> arrays_equal([1,2,3], [1,3,4])
> arrays_equal([1,2,3], [1,2,3])
> arrays_equal([1,3,4], [1,2,3])
> arrays_equal(null, [1,2,3])
> arrays_equal(null, null)

How to calculate number of days between two given dates?

Here are three ways to go with this problem :

from datetime import datetime

Now =
StartDate = datetime.strptime(str(Now.year) +'-01-01', '%Y-%m-%d')
NumberOfDays = (Now - StartDate)

print(NumberOfDays.days)                     # Starts at 0
print(    # Starts at 1
print(Now.strftime('%j'))                    # Starts at 1

Removing leading zeroes from a field in a SQL statement

select replace(replace(rtrim(replace(replace(replace(replace(ltrim(replace(replace([COLUMN],' ','[Ltrim]'),[Ltrim],' ')),' ',[Ltrim]),'[Ltrim]',' '),' ','[Rtrim]'),[Rtrim],' ')),' ',[Rtrim]),'[Rtrim]',' ') As Result

This is a Sql script that emulates the functionality of the TRIM command in tsql prior to 2017, its basically the same as the other recomendateions,but the others replace with a single uncommon character which still can occur, '[Rtrim]' or '[Ltrim]' could still occur in text, but replacing hat with a unique text, for example a Guid would solve that problem.

i havent tested it regarding speed

How do you completely remove the button border in wpf?

Programmatically, you can do this:

btn.BorderBrush = new SolidColorBrush(Colors.Transparent);

Getting the Facebook like/share count for a given URL

I see this nice tutorial on how to get the like count from facebook using PHP.

public static function get_the_fb_like( $url = '' ){
 $pageURL = '';

 $url = ($url == '' ) ? $pageURL : $url; // setting a value in $url variable

 $params = 'select comment_count, share_count, like_count from link_stat where url = "'.$url.'"';
 $component = urlencode( $params );
 $url = ''.$component;
 $fbLIkeAndSahre = json_decode( $this->file_get_content_curl( $url ) ); 
 $getFbStatus = $fbLIkeAndSahre->data['0'];
 return $getFbStatus->like_count;

here is a sample code.. I don't know how to paste the code with correct format in here, so just kindly visit this link for better view of the code.

Creating a Custom Facebook like Counter

did you register the component correctly? For recursive components, make sure to provide the "name" option

Adding my scenario. Just in case someone has similar problem and not able to identify ACTUAL issue.

I was using vue splitpanes.

Previously it required only "Splitpanes", in latest version, they made another "Pane" component (as children of splitpanes).

Now thing is, if you don't register "Pane" component in latest version of splitpanes, it was showing error for "Splitpanes". as below.

[Vue warn]: Unknown custom element: <splitpanes> - did you register the component correctly? For recursive components, make sure to provide the "name" option.

What is MVC and what are the advantages of it?

I think another benefit of using the MVC pattern is that it opens up the doors to other approaches to the design, such as MVP/Presenter first and the many other MV* patterns.

Without this fundamental segregation of the design "components" the adoption of these techniques would be much more difficult.

I think it helps to make your code even more interface-based.. Not only within the individual project, but you can almost start to develop common "views" which mean you can template lot more of the "grunt" code used in your applications. For example, a very abstract "data view" which simply takes a bunch of data and throws it to a common grid layout.


If I remember correctly, this is a pretty good podcast on MV* patterns (listened to it a while ago!)

Two decimal places using printf( )

What you want is %.2f, not 2%f.

Also, you might want to replace your %d with a %f ;)

#include <cstdio>
int main()
printf("When this number: %f is assigned to 2 dp, it will be: %.2f ", 94.9456, 94.9456);
return 0;

This will output:

When this number: 94.945600 is assigned to 2 dp, it will be: 94.95

See here for a full description of the printf formatting options: printf

append multiple values for one key in a dictionary

You would be best off using collections.defaultdict (added in Python 2.5). This allows you to specify the default object type of a missing key (such as a list).

So instead of creating a key if it doesn't exist first and then appending to the value of the key, you cut out the middle-man and just directly append to non-existing keys to get the desired result.

A quick example using your data:

>>> from collections import defaultdict
>>> data = [(2010, 2), (2009, 4), (1989, 8), (2009, 7)]
>>> d = defaultdict(list)
>>> d
defaultdict(<type 'list'>, {})
>>> for year, month in data:
...     d[year].append(month)
>>> d
defaultdict(<type 'list'>, {2009: [4, 7], 2010: [2], 1989: [8]})

This way you don't have to worry about whether you've seen a digit associated with a year or not. You just append and forget, knowing that a missing key will always be a list. If a key already exists, then it will just be appended to.