Microsoft hired one fo the kids from A List Apart to whip some out. The .Net projects are free of charge for download.
//this method skips unnecessary trial divisions and makes
//trial division more feasible for finding large primes
public static void main(String[] args)
{
long n= 1000000000039L; //this is a large prime number
long i = 2L;
int test = 0;
while (n > 1)
{
while (n % i == 0)
{
n /= i;
}
i++;
if(i*i > n && n > 1)
{
System.out.println(n); //prints n if it's prime
test = 1;
break;
}
}
if (test == 0)
System.out.println(i-1); //prints n if it's the largest prime factor
}
I believe that procedural/functional/objective programming are about how to approach a problem.
The first style would plan everything in to steps, and solves the problem by implementing one step (a procedure) at a time. On the other hand, functional programming would emphasize the divide-and-conquer approach, where the problem is divided into sub-problem, then each sub-problem is solved (creating a function to solve that sub problem) and the results are combined to create the answer for the whole problem. Lastly, Objective programming would mimic the real world by create a mini-world inside the computer with many objects, each of which has a (somewhat) unique characteristics, and interacts with others. From those interactions the result would emerge.
Each style of programming has its own advantages and weaknesses. Hence, doing something such as "pure programming" (i.e. purely procedural - no one does this, by the way, which is kind of weird - or purely functional or purely objective) is very difficult, if not impossible, except some elementary problems specially designed to demonstrate the advantage of a programming style (hence, we call those who like pureness "weenie" :D).
Then, from those styles, we have programming languages that is designed to optimized for some each style. For example, Assembly is all about procedural. Okay, most early languages are procedural, not only Asm, like C, Pascal, (and Fortran, I heard). Then, we have all famous Java in objective school (Actually, Java and C# is also in a class called "money-oriented," but that is subject for another discussion). Also objective is Smalltalk. In functional school, we would have "nearly functional" (some considered them to be impure) Lisp family and ML family and many "purely functional" Haskell, Erlang, etc. By the way, there are many general languages such as Perl, Python, Ruby.
When you are many developers working on the same code base, you need some code guidelines/rules. Where I work we've desided to use 'this' on fields, properties and events.
To me it makes good sense to do it like this, it makes the code easier to read when you differentiate between class-variables and method-variables.
Try Secure Cookie protocol described in this paper by Liu, Kovacs, Huang, and Gouda:
As stated in document:
A secure cookie protocol that runs between a client and a server needs to provide the following four services: authentication, confidentiality, integrity and anti-replay.
As for ease of deployment:
In terms of efficiency, our protocol does not involve any database lookup or public key cryptography. In terms of deployability, our protocol can be easily deployed on an existing web server, and it does not require any change to the Internet cookie specication.
In short: it is secure, lightweight, works for me just great.
The defacto standard for learning Grails is the excellent Getting Started with Grails by Jason Rudolph. You can debate whether it is an online tutorial or a book since it can be purchased but is available as a free download. There are more "real" books being published and I recommend Beginning Groovy and Grails.
I hate foo and bar .. who dreamed up these non descriptive terms in programming anyway?
my $oldstring = "replace donotreplace replace donotreplace replace donotreplace";
my $newstring = $oldstring;
$newstring =~ s/replace/newword/g; # inplace replacement
print $newstring;
%: newword donotreplace newword donotreplace newword donotreplace
JavaScript-ViewState-Parser:
The parser should work with most non-encrypted ViewStates. It doesn’t handle the serialization format used by .NET version 1 because that version is sorely outdated and therefore too unlikely to be encountered in any real situation.
http://deadliestwebattacks.com/2011/05/29/javascript-viewstate-parser/
Parsing .NET ViewState
A Spirited Peek into ViewState, Part I:
http://deadliestwebattacks.com/2011/05/13/a-spirited-peek-into-viewstate-part-i/
A Spirited Peek into ViewState, Part II:
http://deadliestwebattacks.com/2011/05/25/a-spirited-peek-into-viewstate-part-ii/
For something a little different, you could use JRuby and Mocha which are combined in JtestR to write tests for your Java code in expressive and succinct Ruby. There are some useful mocking examples with JtestR here. One advantage of this approach is that mocking concrete classes is very straightforward.
urlretrieve and requests.get are simple, however the reality not. I have fetched data for couple sites, including text and images, the above two probably solve most of the tasks. but for a more universal solution I suggest the use of urlopen. As it is included in Python 3 standard library, your code could run on any machine that run Python 3 without pre-installing site-package
import urllib.request
url_request = urllib.request.Request(url, headers=headers)
url_connect = urllib.request.urlopen(url_request)
#remember to open file in bytes mode
with open(filename, 'wb') as f:
while True:
buffer = url_connect.read(buffer_size)
if not buffer: break
#an integer value of size of written data
data_wrote = f.write(buffer)
#you could probably use with-open-as manner
url_connect.close()
This answer provides a solution to HTTP 403 Forbidden when downloading file over http using Python. I have tried only requests and urllib modules, the other module may provide something better, but this is the one I used to solve most of the problems.
The rule of thumb is to avoid Catching and Throwing the basic Exception
object. This forces you to be a little smarter about exceptions; in other words you should have an explicit catch for a SqlException
so that your handling code doesn't do something wrong with a NullReferenceException
.
In the real world though, catching and logging the base exception is also a good practice, but don't forget to walk the whole thing to get any InnerExceptions
it might have.
If you have a value that includes a decimal, but the decimal value is negligible (ie: 100.0) and try to int that, you will get an error. It seems silly, but calling float first fixes this.
str(int(float([variable])))
A devkit that allows one to develop iPhone apps in Objective-C, C++
or just plain C with Visual Studio:
Check it out at iOS build env
You can build iPhone apps directly within Visual Studio (2008, 2010, Express).
Pretty neat, it even builds IPA
files for your app after a successful compilation. The code works as is on jailbroken devices, for the rest of the planet I believe the final compilation & submission to the App Store has to be done on a Mac. But still, it enables you to develop using a well-known IDE.
I've always wondered how costly it is to always assume that invoke is required...
private void OnCoolEvent(CoolObjectEventArgs e)
{
BeginInvoke((o,e) => /*do work here*/,this, e);
}
It seems the static method in the interface might be supported in Java 8, well, my solution is just define them in the inner class.
interface Foo {
// ...
class fn {
public static void func1(...) {
// ...
}
}
}
The same technique can also be used in annotations:
public @interface Foo {
String value();
class fn {
public static String getValue(Object obj) {
Foo foo = obj.getClass().getAnnotation(Foo.class);
return foo == null ? null : foo.value();
}
}
}
The inner class should always be accessed in the form of Interface.fn...
instead of Class.fn...
, then, you can get rid of ambiguous problem.
There's an alternative approach to this:
#include <iterator>
#include <algorithm>
// ...
copy(istream_iterator<int>(iFile), istream_iterator<int>(),
ostream_iterator<int>(cerr, "\n"));
Even though @Rick has the accepted answer for this question, there's actually a shorter way to do this, using the poorly named Uri.GetLeftPart()
method.
Uri url = new Uri("http://www.mywebsite.com:80/pages/page1.aspx");
string output = url.GetLeftPart(UriPartial.Authority);
There is one catch to GetLeftPart()
, however. If the port is the default port for the scheme, it will strip it out. Since port 80 is the default port for http, the output of GetLeftPart()
in my example above will be http://www.mywebsite.com
.
If the port number had been something other than 80, it would be included in the result.
For #include ""
a compiler normally searches the folder of the file which contains that include and then the other folders. For #include <>
the compiler does not search the current file's folder.
Explaining multiple-inheritance with virtual bases requires a knowledge of the C++ object model. And explaining the topic clearly is best done in an article and not in a comment box.
The best, readable explanation I found that solved all my doubts on this subject was this article: http://www.phpcompiler.org/articles/virtualinheritance.html
You really won't need to read anything else on the topic (unless you are a compiler writer) after reading that...
I realise that it's been a very long time but thought I'd add anyway. If you just want the table, and not the create table statement you could use
select into x from db.schema.y where 1=0
to copy the table to a new DB
Dynamic module import landed in Firefox 67+.
(async () => {
await import('./synth/BubbleSynth.js')
})()
With error handling:
(async () => {
await import('./synth/BubbleSynth.js').catch((error) => console.log('Loading failed' + error))
})()
It also works for any kind of non-modules libraries, on this case the lib is available on the window object, the old way, but only on demand, which is nice.
Example using suncalc.js, the server must have CORS enabled to works this way!
(async () => {
await import('https://cdnjs.cloudflare.com/ajax/libs/suncalc/1.8.0/suncalc.min.js')
.then(function(){
let times = SunCalc.getTimes(new Date(), 51.5,-0.1);
console.log("Golden Hour today in London: " + times.goldenHour.getHours() + ':' + times.goldenHour.getMinutes() + ". Take your pics!")
})
})()
_x000D_
I think a good place to start is with Ninject, it is new and has taken into account alot of fine tuning and is really fast. Nate, the developer, really has a great site and great support.
If subtracting microtimes gives you negative results, try using the function with the argument true
(microtime(true)
). With true
, the function returns a float instead of a string (as it does if it is called without arguments).
It really depends on your usage pattern. A detailed benchmark between string.Join, string,Concat and string.Format can be found here: String.Format Isn't Suitable for Intensive Logging
(This is actually the same answer I gave to this question)
Just looking though my email archives, there are a number of pretty long "first" names (of course what is meant by first is variable by culture). One example is Krishnamurthy - which is 13 letters long. A good guess might be 20 to 25 letters based on this. Email should be much longer since you might have [email protected]. Also, gmail and some other mail programs allow you to use [email protected] where "sometag" is anything you want to put there so that you can use it to sort incoming emails. I frequently run into web forms that don't allow me to put in my full email address without considering any tags. So, if you need a fixed email field maybe something like [email protected] in characters for a total of 90 characters (if I did my math right!).
Normally I would agree with Yaakov Ellis but in this special case there is another viable solution:
Use two tables:
Table: Item
Columns: ItemID, Title, Content
Indexes: ItemID
Table: Tag
Columns: ItemID, Title
Indexes: ItemId, Title
This has some major advantages:
First it makes development much simpler: in the three-table solution for insert and update of item
you have to lookup the Tag
table to see if there are already entries. Then you have to join them with new ones. This is no trivial task.
Then it makes queries simpler (and perhaps faster). There are three major database queries which you will do: Output all Tags
for one Item
, draw a Tag-Cloud and select all items for one Tag Title.
All Tags for one Item:
3-Table:
SELECT Tag.Title
FROM Tag
JOIN ItemTag ON Tag.TagID = ItemTag.TagID
WHERE ItemTag.ItemID = :id
2-Table:
SELECT Tag.Title
FROM Tag
WHERE Tag.ItemID = :id
Tag-Cloud:
3-Table:
SELECT Tag.Title, count(*)
FROM Tag
JOIN ItemTag ON Tag.TagID = ItemTag.TagID
GROUP BY Tag.Title
2-Table:
SELECT Tag.Title, count(*)
FROM Tag
GROUP BY Tag.Title
Items for one Tag:
3-Table:
SELECT Item.*
FROM Item
JOIN ItemTag ON Item.ItemID = ItemTag.ItemID
JOIN Tag ON ItemTag.TagID = Tag.TagID
WHERE Tag.Title = :title
2-Table:
SELECT Item.*
FROM Item
JOIN Tag ON Item.ItemID = Tag.ItemID
WHERE Tag.Title = :title
But there are some drawbacks, too: It could take more space in the database (which could lead to more disk operations which is slower) and it's not normalized which could lead to inconsistencies.
The size argument is not that strong because the very nature of tags is that they are normally pretty small so the size increase is not a large one. One could argue that the query for the tag title is much faster in a small table which contains each tag only once and this certainly is true. But taking in regard the savings for not having to join and the fact that you can build a good index on them could easily compensate for this. This of course depends heavily on the size of the database you are using.
The inconsistency argument is a little moot too. Tags are free text fields and there is no expected operation like 'rename all tags "foo" to "bar"'.
So tldr: I would go for the two-table solution. (In fact I'm going to. I found this article to see if there are valid arguments against it.)
This should be the most reliable way regardless of the compiler:
m=std::stringstream();
you may use
ImageSourceConverter class
to get what you want
img1.Source = (ImageSource)new ImageSourceConverter().ConvertFromString("/Assets/check.png");
I've tried Komodo out a bit, and I really like it so far. Aptana, an Eclipse variant, is also rather useful for a wide variety of things. There's always good ole' VI, too!
Here is a solution using the javax.crypto library and the apache commons codec library for encoding and decoding in Base64:
import java.security.spec.KeySpec;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESedeKeySpec;
import org.apache.commons.codec.binary.Base64;
public class TrippleDes {
private static final String UNICODE_FORMAT = "UTF8";
public static final String DESEDE_ENCRYPTION_SCHEME = "DESede";
private KeySpec ks;
private SecretKeyFactory skf;
private Cipher cipher;
byte[] arrayBytes;
private String myEncryptionKey;
private String myEncryptionScheme;
SecretKey key;
public TrippleDes() throws Exception {
myEncryptionKey = "ThisIsSpartaThisIsSparta";
myEncryptionScheme = DESEDE_ENCRYPTION_SCHEME;
arrayBytes = myEncryptionKey.getBytes(UNICODE_FORMAT);
ks = new DESedeKeySpec(arrayBytes);
skf = SecretKeyFactory.getInstance(myEncryptionScheme);
cipher = Cipher.getInstance(myEncryptionScheme);
key = skf.generateSecret(ks);
}
public String encrypt(String unencryptedString) {
String encryptedString = null;
try {
cipher.init(Cipher.ENCRYPT_MODE, key);
byte[] plainText = unencryptedString.getBytes(UNICODE_FORMAT);
byte[] encryptedText = cipher.doFinal(plainText);
encryptedString = new String(Base64.encodeBase64(encryptedText));
} catch (Exception e) {
e.printStackTrace();
}
return encryptedString;
}
public String decrypt(String encryptedString) {
String decryptedText=null;
try {
cipher.init(Cipher.DECRYPT_MODE, key);
byte[] encryptedText = Base64.decodeBase64(encryptedString);
byte[] plainText = cipher.doFinal(encryptedText);
decryptedText= new String(plainText);
} catch (Exception e) {
e.printStackTrace();
}
return decryptedText;
}
public static void main(String args []) throws Exception
{
TrippleDes td= new TrippleDes();
String target="imparator";
String encrypted=td.encrypt(target);
String decrypted=td.decrypt(encrypted);
System.out.println("String To Encrypt: "+ target);
System.out.println("Encrypted String:" + encrypted);
System.out.println("Decrypted String:" + decrypted);
}
}
Running the above program results with the following output:
String To Encrypt: imparator
Encrypted String:FdBNaYWfjpWN9eYghMpbRA==
Decrypted String:imparator
Beautiful set of stencils from Microsoft here.
A bit late to the game...but here's a quite comprehensive post I wrote a few months back, detailing the major differences between MYISAM and InnoDB. Grab a cuppa (and maybe a biscuit), and enjoy.
The major difference between MyISAM and InnoDB is in referential integrity and transactions. There are also other difference such as locking, rollbacks, and full-text searches.
Referential integrity ensures that relationships between tables remains consistent. More specifically, this means when a table (e.g. Listings) has a foreign key (e.g. Product ID) pointing to a different table (e.g. Products), when updates or deletes occur to the pointed-to table, these changes are cascaded to the linking table. In our example, if a product is renamed, the linking table’s foreign keys will also update; if a product is deleted from the ‘Products’ table, any listings which point to the deleted entry will also be deleted. Furthermore, any new listing must have that foreign key pointing to a valid, existing entry.
InnoDB is a relational DBMS (RDBMS) and thus has referential integrity, while MyISAM does not.
Data in a table is managed using Data Manipulation Language (DML) statements, such as SELECT, INSERT, UPDATE and DELETE. A transaction group two or more DML statements together into a single unit of work, so either the entire unit is applied, or none of it is.
MyISAM do not support transactions whereas InnoDB does.
If an operation is interrupted while using a MyISAM table, the operation is aborted immediately, and the rows (or even data within each row) that are affected remains affected, even if the operation did not go to completion.
If an operation is interrupted while using an InnoDB table, because it using transactions, which has atomicity, any transaction which did not go to completion will not take effect, since no commit is made.
When a query runs against a MyISAM table, the entire table in which it is querying will be locked. This means subsequent queries will only be executed after the current one is finished. If you are reading a large table, and/or there are frequent read and write operations, this can mean a huge backlog of queries.
When a query runs against an InnoDB table, only the row(s) which are involved are locked, the rest of the table remains available for CRUD operations. This means queries can run simultaneously on the same table, provided they do not use the same row.
This feature in InnoDB is known as concurrency. As great as concurrency is, there is a major drawback that applies to a select range of tables, in that there is an overhead in switching between kernel threads, and you should set a limit on the kernel threads to prevent the server coming to a halt.
When you run an operation in MyISAM, the changes are set; in InnoDB, those changes can be rolled back. The most common commands used to control transactions are COMMIT, ROLLBACK and SAVEPOINT. 1. COMMIT - you can write multiple DML operations, but the changes will only be saved when a COMMIT is made 2. ROLLBACK - you can discard any operations that have not yet been committed yet 3. SAVEPOINT - sets a point in the list of operations to which a ROLLBACK operation can rollback to
MyISAM offers no data integrity - Hardware failures, unclean shutdowns and canceled operations can cause the data to become corrupt. This would require full repair or rebuilds of the indexes and tables.
InnoDB, on the other hand, uses a transactional log, a double-write buffer and automatic checksumming and validation to prevent corruption. Before InnoDB makes any changes, it records the data before the transactions into a system tablespace file called ibdata1. If there is a crash, InnoDB would autorecover through the replay of those logs.
InnoDB does not support FULLTEXT indexing until MySQL version 5.6.4. As of the writing of this post, many shared hosting providers’ MySQL version is still below 5.6.4, which means FULLTEXT indexing is not supported for InnoDB tables.
However, this is not a valid reason to use MyISAM. It’s best to change to a hosting provider that supports up-to-date versions of MySQL. Not that a MyISAM table that uses FULLTEXT indexing cannot be converted to an InnoDB table.
In conclusion, InnoDB should be your default storage engine of choice. Choose MyISAM or other data types when they serve a specific need.
Go to Tools > Options > Advanced "Tab"(?) > Encryption Tab
Click the "Validation" button, and uncheck the checkbox for checking validity
Be advised though that this is pretty unsecure as it leaves you wide open to accept any invalid certificate. I'd only do this if using the browser on an Intranet where the validity of the cert isn't a concern to you, or you aren't concerned in general.
consoleargs deserves to be mentioned here. It is very easy to use. Check it out:
from consoleargs import command
@command
def main(url, name=None):
"""
:param url: Remote URL
:param name: File name
"""
print """Downloading url '%r' into file '%r'""" % (url, name)
if __name__ == '__main__':
main()
Now in console:
% python demo.py --help
Usage: demo.py URL [OPTIONS]
URL: Remote URL
Options:
--name -n File name
% python demo.py http://www.google.com/
Downloading url ''http://www.google.com/'' into file 'None'
% python demo.py http://www.google.com/ --name=index.html
Downloading url ''http://www.google.com/'' into file ''index.html''
You could encode the binary data using base64 and put it into a Base64 element; the below article is a pretty good one on the subject.
select r.id, r.name from table AS r
INNER JOIN(select CEIL(RAND() * (select MAX(id) from table)) as id) as r1
ON r.id >= r1.id ORDER BY r.id ASC LIMIT 1
This will require a lesser computation time
def transpose_finite_iterable(iterable):
return zip(*iterable) # `itertools.izip` for Python 2 users
works fine for finite iterable (e.g. sequences like list
/tuple
/str
) of (potentially infinite) iterables which can be illustrated like
| |a_00| |a_10| ... |a_n0| |
| |a_01| |a_11| ... |a_n1| |
| |... | |... | ... |... | |
| |a_0i| |a_1i| ... |a_ni| |
| |... | |... | ... |... | |
where
n in N
,a_ij
corresponds to j
-th element of i
-th iterable,and after applying transpose_finite_iterable
we get
| |a_00| |a_01| ... |a_0i| ... |
| |a_10| |a_11| ... |a_1i| ... |
| |... | |... | ... |... | ... |
| |a_n0| |a_n1| ... |a_ni| ... |
Python example of such case where a_ij == j
, n == 2
>>> from itertools import count
>>> iterable = [count(), count()]
>>> result = transpose_finite_iterable(iterable)
>>> next(result)
(0, 0)
>>> next(result)
(1, 1)
But we can't use transpose_finite_iterable
again to return to structure of original iterable
because result
is an infinite iterable of finite iterables (tuple
s in our case):
>>> transpose_finite_iterable(result)
... hangs ...
Traceback (most recent call last):
File "...", line 1, in ...
File "...", line 2, in transpose_finite_iterable
MemoryError
So how can we deal with this case?
deque
After we take a look at docs of itertools.tee
function, there is Python recipe that with some modification can help in our case
def transpose_finite_iterables(iterable):
iterator = iter(iterable)
try:
first_elements = next(iterator)
except StopIteration:
return ()
queues = [deque([element])
for element in first_elements]
def coordinate(queue):
while True:
if not queue:
try:
elements = next(iterator)
except StopIteration:
return
for sub_queue, element in zip(queues, elements):
sub_queue.append(element)
yield queue.popleft()
return tuple(map(coordinate, queues))
let's check
>>> from itertools import count
>>> iterable = [count(), count()]
>>> result = transpose_finite_iterables(transpose_finite_iterable(iterable))
>>> result
(<generator object transpose_finite_iterables.<locals>.coordinate at ...>, <generator object transpose_finite_iterables.<locals>.coordinate at ...>)
>>> next(result[0])
0
>>> next(result[0])
1
Now we can define general function for working with iterables of iterables ones of which are finite and another ones are potentially infinite using functools.singledispatch
decorator like
from collections import (abc,
deque)
from functools import singledispatch
@singledispatch
def transpose(object_):
"""
Transposes given object.
"""
raise TypeError('Unsupported object type: {type}.'
.format(type=type))
@transpose.register(abc.Iterable)
def transpose_finite_iterables(object_):
"""
Transposes given iterable of finite iterables.
"""
iterator = iter(object_)
try:
first_elements = next(iterator)
except StopIteration:
return ()
queues = [deque([element])
for element in first_elements]
def coordinate(queue):
while True:
if not queue:
try:
elements = next(iterator)
except StopIteration:
return
for sub_queue, element in zip(queues, elements):
sub_queue.append(element)
yield queue.popleft()
return tuple(map(coordinate, queues))
def transpose_finite_iterable(object_):
"""
Transposes given finite iterable of iterables.
"""
yield from zip(*object_)
try:
transpose.register(abc.Collection, transpose_finite_iterable)
except AttributeError:
# Python3.5-
transpose.register(abc.Mapping, transpose_finite_iterable)
transpose.register(abc.Sequence, transpose_finite_iterable)
transpose.register(abc.Set, transpose_finite_iterable)
which can be considered as its own inverse (mathematicians call this kind of functions "involutions") in class of binary operators over finite non-empty iterables.
As a bonus of singledispatch
ing we can handle numpy
arrays like
import numpy as np
...
transpose.register(np.ndarray, np.transpose)
and then use it like
>>> array = np.arange(4).reshape((2,2))
>>> array
array([[0, 1],
[2, 3]])
>>> transpose(array)
array([[0, 2],
[1, 3]])
Since transpose
returns iterators and if someone wants to have a tuple
of list
s like in OP -- this can be made additionally with map
built-in function like
>>> original = [('a', 1), ('b', 2), ('c', 3), ('d', 4)]
>>> tuple(map(list, transpose(original)))
(['a', 'b', 'c', 'd'], [1, 2, 3, 4])
I've added generalized solution to lz
package from 0.5.0
version which can be used like
>>> from lz.transposition import transpose
>>> list(map(tuple, transpose(zip(range(10), range(10, 20)))))
[(0, 1, 2, 3, 4, 5, 6, 7, 8, 9), (10, 11, 12, 13, 14, 15, 16, 17, 18, 19)]
There is no solution (at least obvious) for handling potentially infinite iterable of potentially infinite iterables, but this case is less common though.
All answers on this page are really great for a complex object. But for those containing builtin iterable types as attributes, like str
, list
, set
or dict
, or any implementation of collections.Iterable
, you can omit certain things in your class.
class Test(object):
def __init__(self, string):
self.string = string
def __iter__(self):
# since your string is already iterable
return (ch for ch in self.string)
# or simply
return self.string.__iter__()
# also
return iter(self.string)
It can be used like:
for x in Test("abcde"):
print(x)
# prints
# a
# b
# c
# d
# e
My favourite solution is from MVP Daniel Vaughan: Enforcing Single Instance Wpf Applications
It use MemoryMappedFile to send command line arguments to the first instance:
/// <summary>
/// This class allows restricting the number of executables in execution, to one.
/// </summary>
public sealed class SingletonApplicationEnforcer
{
readonly Action<IEnumerable<string>> processArgsFunc;
readonly string applicationId;
Thread thread;
string argDelimiter = "_;;_";
/// <summary>
/// Gets or sets the string that is used to join
/// the string array of arguments in memory.
/// </summary>
/// <value>The arg delimeter.</value>
public string ArgDelimeter
{
get
{
return argDelimiter;
}
set
{
argDelimiter = value;
}
}
/// <summary>
/// Initializes a new instance of the <see cref="SingletonApplicationEnforcer"/> class.
/// </summary>
/// <param name="processArgsFunc">A handler for processing command line args
/// when they are received from another application instance.</param>
/// <param name="applicationId">The application id used
/// for naming the <seealso cref="EventWaitHandle"/>.</param>
public SingletonApplicationEnforcer(Action<IEnumerable<string>> processArgsFunc,
string applicationId = "DisciplesRock")
{
if (processArgsFunc == null)
{
throw new ArgumentNullException("processArgsFunc");
}
this.processArgsFunc = processArgsFunc;
this.applicationId = applicationId;
}
/// <summary>
/// Determines if this application instance is not the singleton instance.
/// If this application is not the singleton, then it should exit.
/// </summary>
/// <returns><c>true</c> if the application should shutdown,
/// otherwise <c>false</c>.</returns>
public bool ShouldApplicationExit()
{
bool createdNew;
string argsWaitHandleName = "ArgsWaitHandle_" + applicationId;
string memoryFileName = "ArgFile_" + applicationId;
EventWaitHandle argsWaitHandle = new EventWaitHandle(
false, EventResetMode.AutoReset, argsWaitHandleName, out createdNew);
GC.KeepAlive(argsWaitHandle);
if (createdNew)
{
/* This is the main, or singleton application.
* A thread is created to service the MemoryMappedFile.
* We repeatedly examine this file each time the argsWaitHandle
* is Set by a non-singleton application instance. */
thread = new Thread(() =>
{
try
{
using (MemoryMappedFile file = MemoryMappedFile.CreateOrOpen(memoryFileName, 10000))
{
while (true)
{
argsWaitHandle.WaitOne();
using (MemoryMappedViewStream stream = file.CreateViewStream())
{
var reader = new BinaryReader(stream);
string args;
try
{
args = reader.ReadString();
}
catch (Exception ex)
{
Debug.WriteLine("Unable to retrieve string. " + ex);
continue;
}
string[] argsSplit = args.Split(new string[] { argDelimiter },
StringSplitOptions.RemoveEmptyEntries);
processArgsFunc(argsSplit);
}
}
}
}
catch (Exception ex)
{
Debug.WriteLine("Unable to monitor memory file. " + ex);
}
});
thread.IsBackground = true;
thread.Start();
}
else
{
/* Non singleton application instance.
* Should exit, after passing command line args to singleton process,
* via the MemoryMappedFile. */
using (MemoryMappedFile mmf = MemoryMappedFile.OpenExisting(memoryFileName))
{
using (MemoryMappedViewStream stream = mmf.CreateViewStream())
{
var writer = new BinaryWriter(stream);
string[] args = Environment.GetCommandLineArgs();
string joined = string.Join(argDelimiter, args);
writer.Write(joined);
}
}
argsWaitHandle.Set();
}
return !createdNew;
}
}
As the accepted answer says, the most idiomatic way is to just use a module.
With that in mind, here's a proof of concept:
def singleton(cls):
obj = cls()
# Always return the same object
cls.__new__ = staticmethod(lambda cls: obj)
# Disable __init__
try:
del cls.__init__
except AttributeError:
pass
return cls
See the Python data model for more details on __new__
.
Example:
@singleton
class Duck(object):
pass
if Duck() is Duck():
print "It works!"
else:
print "It doesn't work!"
Notes:
You have to use new-style classes (derive from object
) for this.
The singleton is initialized when it is defined, rather than the first time it's used.
This is just a toy example. I've never actually used this in production code, and don't plan to.
First Solution
I developed this as a cleaned up version of .NET Win 7-style folder select dialog by Bill Seddon of lyquidity.com (I have no affiliation). (I learned of his code from another answer on this page). I wrote my own because his solution requires an additional Reflection class that isn't needed for this focused purpose, uses exception-based flow control, doesn't cache the results of its reflection calls. Note that the nested static VistaDialog
class is so that its static reflection variables don't try to get populated if the Show
method is never called. It falls back to the pre-Vista dialog if not in a high enough Windows version. Should work in Windows 7, 8, 9, 10 and higher (theoretically).
using System;
using System.Reflection;
using System.Windows.Forms;
namespace ErikE.Shuriken {
/// <summary>
/// Present the Windows Vista-style open file dialog to select a folder. Fall back for older Windows Versions
/// </summary>
public class FolderSelectDialog {
private string _initialDirectory;
private string _title;
private string _fileName = "";
public string InitialDirectory {
get { return string.IsNullOrEmpty(_initialDirectory) ? Environment.CurrentDirectory : _initialDirectory; }
set { _initialDirectory = value; }
}
public string Title {
get { return _title ?? "Select a folder"; }
set { _title = value; }
}
public string FileName { get { return _fileName; } }
public bool Show() { return Show(IntPtr.Zero); }
/// <param name="hWndOwner">Handle of the control or window to be the parent of the file dialog</param>
/// <returns>true if the user clicks OK</returns>
public bool Show(IntPtr hWndOwner) {
var result = Environment.OSVersion.Version.Major >= 6
? VistaDialog.Show(hWndOwner, InitialDirectory, Title)
: ShowXpDialog(hWndOwner, InitialDirectory, Title);
_fileName = result.FileName;
return result.Result;
}
private struct ShowDialogResult {
public bool Result { get; set; }
public string FileName { get; set; }
}
private static ShowDialogResult ShowXpDialog(IntPtr ownerHandle, string initialDirectory, string title) {
var folderBrowserDialog = new FolderBrowserDialog {
Description = title,
SelectedPath = initialDirectory,
ShowNewFolderButton = false
};
var dialogResult = new ShowDialogResult();
if (folderBrowserDialog.ShowDialog(new WindowWrapper(ownerHandle)) == DialogResult.OK) {
dialogResult.Result = true;
dialogResult.FileName = folderBrowserDialog.SelectedPath;
}
return dialogResult;
}
private static class VistaDialog {
private const string c_foldersFilter = "Folders|\n";
private const BindingFlags c_flags = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic;
private readonly static Assembly s_windowsFormsAssembly = typeof(FileDialog).Assembly;
private readonly static Type s_iFileDialogType = s_windowsFormsAssembly.GetType("System.Windows.Forms.FileDialogNative+IFileDialog");
private readonly static MethodInfo s_createVistaDialogMethodInfo = typeof(OpenFileDialog).GetMethod("CreateVistaDialog", c_flags);
private readonly static MethodInfo s_onBeforeVistaDialogMethodInfo = typeof(OpenFileDialog).GetMethod("OnBeforeVistaDialog", c_flags);
private readonly static MethodInfo s_getOptionsMethodInfo = typeof(FileDialog).GetMethod("GetOptions", c_flags);
private readonly static MethodInfo s_setOptionsMethodInfo = s_iFileDialogType.GetMethod("SetOptions", c_flags);
private readonly static uint s_fosPickFoldersBitFlag = (uint) s_windowsFormsAssembly
.GetType("System.Windows.Forms.FileDialogNative+FOS")
.GetField("FOS_PICKFOLDERS")
.GetValue(null);
private readonly static ConstructorInfo s_vistaDialogEventsConstructorInfo = s_windowsFormsAssembly
.GetType("System.Windows.Forms.FileDialog+VistaDialogEvents")
.GetConstructor(c_flags, null, new[] { typeof(FileDialog) }, null);
private readonly static MethodInfo s_adviseMethodInfo = s_iFileDialogType.GetMethod("Advise");
private readonly static MethodInfo s_unAdviseMethodInfo = s_iFileDialogType.GetMethod("Unadvise");
private readonly static MethodInfo s_showMethodInfo = s_iFileDialogType.GetMethod("Show");
public static ShowDialogResult Show(IntPtr ownerHandle, string initialDirectory, string title) {
var openFileDialog = new OpenFileDialog {
AddExtension = false,
CheckFileExists = false,
DereferenceLinks = true,
Filter = c_foldersFilter,
InitialDirectory = initialDirectory,
Multiselect = false,
Title = title
};
var iFileDialog = s_createVistaDialogMethodInfo.Invoke(openFileDialog, new object[] { });
s_onBeforeVistaDialogMethodInfo.Invoke(openFileDialog, new[] { iFileDialog });
s_setOptionsMethodInfo.Invoke(iFileDialog, new object[] { (uint) s_getOptionsMethodInfo.Invoke(openFileDialog, new object[] { }) | s_fosPickFoldersBitFlag });
var adviseParametersWithOutputConnectionToken = new[] { s_vistaDialogEventsConstructorInfo.Invoke(new object[] { openFileDialog }), 0U };
s_adviseMethodInfo.Invoke(iFileDialog, adviseParametersWithOutputConnectionToken);
try {
int retVal = (int) s_showMethodInfo.Invoke(iFileDialog, new object[] { ownerHandle });
return new ShowDialogResult {
Result = retVal == 0,
FileName = openFileDialog.FileName
};
}
finally {
s_unAdviseMethodInfo.Invoke(iFileDialog, new[] { adviseParametersWithOutputConnectionToken[1] });
}
}
}
// Wrap an IWin32Window around an IntPtr
private class WindowWrapper : IWin32Window {
private readonly IntPtr _handle;
public WindowWrapper(IntPtr handle) { _handle = handle; }
public IntPtr Handle { get { return _handle; } }
}
}
}
It is used like so in a Windows Form:
var dialog = new FolderSelectDialog {
InitialDirectory = musicFolderTextBox.Text,
Title = "Select a folder to import music from"
};
if (dialog.Show(Handle)) {
musicFolderTextBox.Text = dialog.FileName;
}
You can of course play around with its options and what properties it exposes. For example, it allows multiselect in the Vista-style dialog.
Second Solution
Simon Mourier gave an answer that shows how to do the exact same job using interop against the Windows API directly, though his version would have to be supplemented to use the older style dialog if in an older version of Windows. Unfortunately, I hadn't found his post yet when I worked up my solution. Name your poison!
I'd say
concat('This is line 1.', 0xd0a, 'This is line 2.')
or
concat(N'This is line 1.', 0xd000a, N'This is line 2.')
By default - No.
There's the length
property that is commonly used for the same result in the following way:
if ($(selector).length)
Here, 'selector' is to be replaced by the actual selector you are interested to find if it exists or not. If it does exist, the length property will output an integer more than 0 and hence the if
statement will become true and hence execute the if block. If it doesn't, it will output the integer '0' and hence the if block won't get executed.
Nowadays you can get the FileVersionInfo from Get-Item or Get-ChildItem, but it will show the original FileVersion from the shipped product, and not the updated version. For instance:
(Get-Item C:\Windows\System32\Lsasrv.dll).VersionInfo.FileVersion
Interestingly, you can get the updated (patched) ProductVersion by using this:
(Get-Command C:\Windows\System32\Lsasrv.dll).Version
The distinction I'm making between "original" and "patched" is basically due to the way the FileVersion is calculated (see the docs here). Basically ever since Vista, the Windows API GetFileVersionInfo is querying part of the version information from the language neutral file (exe/dll) and the non-fixed part from a language-specific mui file (which isn't updated every time the files change).
So with a file like lsasrv (which got replaced due to security problems in SSL/TLS/RDS in November 2014) the versions reported by these two commands (at least for a while after that date) were different, and the second one is the more "correct" version.
However, although it's correct in LSASrv, it's possible for the ProductVersion and FileVersion to be different (it's common, in fact). So the only way to get the updated Fileversion straight from the assembly file is to build it up yourself from the parts, something like this:
Get-Item C:\Windows\System32\Lsasrv.dll | ft FileName, File*Part
Or by pulling the data from this:
[System.Diagnostics.FileVersionInfo]::GetVersionInfo($this.FullName)
You can easily add this to all FileInfo objects by updating the TypeData in PowerShell:
Update-TypeData -TypeName System.IO.FileInfo -MemberName FileVersion -MemberType ScriptProperty -Value {
[System.Diagnostics.FileVersionInfo]::GetVersionInfo($this.FullName) | % {
[Version](($_.FileMajorPart, $_.FileMinorPart, $_.FileBuildPart, $_.FilePrivatePart)-join".")
}
}
Now every time you do Get-ChildItem
or Get-Item
you'll have a FileVersion
property that shows the updated FileVersion ...
Well, Apache is HTTP webserver, where as Tomcat is also webserver for Servlets and JSP. Moreover Apache is preferred over Apache Tomcat in real time
The truth is even in 3.x it still works, surprisingly the projects builds and deploys. But the LATEST/RELEASE keyword causing problems in m2e and eclipse all over the place, ALSO projects depends on the dependency which deployed through the LATEST/RELEASE fail to recognize the version.
It will also causing problem if you are try to define the version as property, and reference it else where.
So the conclusion is use the versions-maven-plugin if you can.
The average first name is about 6 letters. That leaves 43 for a last name. :) Seems like you could probably shorten it if you like.
The main question is how many rows do you think you will have? I don't think varchar(50) is going to kill you until you get several million rows.
The most readable, IMO:
SELECT * FROM TABLE WHERE Date >
DATEADD(yy, -1, CONVERT(datetime, CONVERT(varchar, GETDATE(), 101)))
Which:
There's variants with DATEDIFF and DATEADD to get you midnight of today, but they tend to be rather obtuse (though slightly better on performance - not that you'd notice compared to the reads required to fetch the data).
Yes, this can be scripted with VBScript. For example the following code can create a zip from a directory:
Dim fso, winShell, MyTarget, MySource, file
Set fso = CreateObject("Scripting.FileSystemObject")
Set winShell = createObject("shell.application")
MyTarget = Wscript.Arguments.Item(0)
MySource = Wscript.Arguments.Item(1)
Wscript.Echo "Adding " & MySource & " to " & MyTarget
'create a new clean zip archive
Set file = fso.CreateTextFile(MyTarget, True)
file.write("PK" & chr(5) & chr(6) & string(18,chr(0)))
file.close
winShell.NameSpace(MyTarget).CopyHere winShell.NameSpace(MySource).Items
do until winShell.namespace(MyTarget).items.count = winShell.namespace(MySource).items.count
wscript.sleep 1000
loop
Set winShell = Nothing
Set fso = Nothing
You may also find http://www.naterice.com/blog/template_permalink.asp?id=64 helpful as it includes a full Unzip/Zip implementation in VBScript.
If you do a size check every 500 ms rather than a item count it works better for large files. Win 7 writes the file instantly although it's not finished compressing:
set fso=createobject("scripting.filesystemobject")
Set h=fso.getFile(DestZip)
do
wscript.sleep 500
max = h.size
loop while h.size > max
Works great for huge amounts of log files.
In our databases we use an enum that ensures we pass it either TRUE or FALSE. If you do it either of the first two ways it is too easy to either start adding new meaning to the integer without going through a proper design, or ending up with that char field having Y, y, N, n, T, t, F, f values and having to remember which section of code uses which table and which version of true it is using.
The new v8 engine which should come out today supports it (i think)
$("#iFrameId").ready(function (){
// do something once the iframe is loaded
});
have you tried .ready instead?
IMO, this is the cleanest answer:
<form action="" method="get">_x000D_
Name: <input type="text" name="name"/><br/>_x000D_
Pwd: <input type="password" name="password"/><br/>_x000D_
<div class="yourCustomDiv"/>_x000D_
<input type="submit" style="display:none"/>_x000D_
</form>
_x000D_
Better yet, if you are using javascript to submit the form using the custom div, you should also use javascript to create it, and to set the display:none style on the button. This way users with javascript disabled will still see the submit button and can click on it.
It has been noted that display:none will cause IE to ignore the input. I created a new JSFiddle example that starts as a standard form, and uses progressive enhancement to hide the submit and create the new div. I did use the CSS styling from StriplingWarrior.
When a client sends ABORT, no transactions are rolled back. To avoid this behavior we have to use SET_XACT_ABORT ON https://docs.microsoft.com/en-us/sql/t-sql/statements/set-xact-abort-transact-sql?view=sql-server-ver15
because the solution folder was inside OneDrive folder.
If you moving the solution folders out of the one drive folder made the errors go away.
best
The abort
function does this. For example:
abort("Message goes here")
Note: the abort
message will be written to STDERR
as opposed to puts
which will write to STDOUT
.
I am using this piece of code to cast int to my enum:
if (typeof(YourEnum).IsEnumDefined(valueToCast)) return (YourEnum)valueToCast;
else { //handle it here, if its not defined }
I find it the best solution.
Visual Editor is a good choice.
It generates very clean code, with no "layout" files beside of your sourcen using a simple but convenient pattern. It's very easy to patch the generated code and directly see the result. There are some stability problems (some times, the preview window does not refresh anymore...), but nothing that a "clean Project" can't fix...
We're talking about C++ right? Why on earth are we still using macros!?
C++ inline functions give you the same speed as a macro, with the added benefit of type-safety and parameter evaluation (which avoids the issue that Rodney and dwj mentioned.
inline const char * const BoolToString(bool b)
{
return b ? "true" : "false";
}
Aside from that I have a few other gripes, particularly with the accepted answer :)
// this is used in C, not C++. if you want to use printf, instead include <cstdio>
//#include <stdio.h>
// instead you should use the iostream libs
#include <iostream>
// not only is this a C include, it's totally unnecessary!
//#include <stdarg.h>
// Macros - not type-safe, has side-effects. Use inline functions instead
//#define BOOL_STR(b) (b?"true":"false")
inline const char * const BoolToString(bool b)
{
return b ? "true" : "false";
}
int main (int argc, char const *argv[]) {
bool alpha = true;
// printf? that's C, not C++
//printf( BOOL_STR(alpha) );
// use the iostream functionality
std::cout << BoolToString(alpha);
return 0;
}
Cheers :)
@DrPizza: Include a whole boost lib for the sake of a function this simple? You've got to be kidding?
Delegate is a type-safe function pointer. Event is an implementation of publisher-subscriber design pattern using delegate.
First follow this procedure:
Log in on A as user a and generate a pair of authentication keys. Do not enter a passphrase:
a@A:~> ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/a/.ssh/id_rsa):
Created directory '/home/a/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/a/.ssh/id_rsa.
Your public key has been saved in /home/a/.ssh/id_rsa.pub.
The key fingerprint is:
3e:4f:05:79:3a:9f:96:7c:3b:ad:e9:58:37:bc:37:e4 a@A
Now use ssh to create a directory ~/.ssh as user b on B. (The directory may already exist, which is fine):
a@A:~> ssh b@B mkdir -p .ssh
b@B's password:
Finally append a's new public key to b@B:.ssh/authorized_keys and enter b's password one last time:
a@A:~> cat .ssh/id_rsa.pub | ssh b@B 'cat >> .ssh/authorized_keys'
b@B's password:
From now on you can log into B as b from A as a without password:
a@A:~> ssh b@B
then this will work without entering a password
ssh b@B "cd /some/directory; program-to-execute &"
The issue is finding an alternative to MS Access that includes a visual, drag and drop development environment with a "reasonable" database where the whole kit and caboodle can be deployed free of charge.
My first suggestion would be to look at this very complete list of MS Access alternatives (many of which are free), followed by a gander at this list of open source database development tools on osalt.com.
My second suggestion would be to check out WaveMaker, which is sort of an open source PowerBuilder for the cloud (disclaimer: I work there so should not be considered to be an unbiased source of information ;-)
WaveMaker combines a drag and drop IDE with an open source Java back end. It is licensed under the Apache license and boasts a 15,000-strong developer community.
Revisiting this question a few years later, UglifyJS, seems to be the best option as of now.
As stated below, it runs on the NodeJS platform, but can be easily modified to run on any JavaScript engine.
--- Old answer below---
Google released Closure Compiler which seems to be generating the smallest files so far as seen here and here
Previous to that the various options were as follow
Basically Packer does a better job at initial compression , but if you are going to gzip the files before sending on the wire (which you should be doing) YUI Compressor gets the smallest final size.
The tests were done on jQuery code btw.
@daniel james mentions in the comment compressorrater which shows Packer leading the chart in best compression, so I guess ymmv
<?php
function executeCurl($arrOptions) {
$mixCH = curl_init();
foreach ($arrOptions as $strCurlOpt => $mixCurlOptValue) {
curl_setopt($mixCH, $strCurlOpt, $mixCurlOptValue);
}
$mixResponse = curl_exec($mixCH);
curl_close($mixCH);
return $mixResponse;
}
// If any HTTP authentication is needed.
$username = 'http-auth-username';
$password = 'http-auth-password';
$requestType = 'POST'; // This can be PUT or POST
// This is a sample array. You can use $arrPostData = $_POST
$arrPostData = array(
'key1' => 'value-1-for-k1y-1',
'key2' => 'value-2-for-key-2',
'key3' => array(
'key31' => 'value-for-key-3-1',
'key32' => array(
'key321' => 'value-for-key321'
)
),
'key4' => array(
'key' => 'value'
)
);
// You can set your post data
$postData = http_build_query($arrPostData); // Raw PHP array
$postData = json_encode($arrPostData); // Only USE this when request JSON data.
$mixResponse = executeCurl(array(
CURLOPT_URL => 'http://whatever-your-request-url.com/xyz/yii',
CURLOPT_RETURNTRANSFER => true,
CURLOPT_HTTPGET => true,
CURLOPT_VERBOSE => true,
CURLOPT_AUTOREFERER => true,
CURLOPT_CUSTOMREQUEST => $requestType,
CURLOPT_POSTFIELDS => $postData,
CURLOPT_HTTPHEADER => array(
"X-HTTP-Method-Override: " . $requestType,
'Content-Type: application/json', // Only USE this when requesting JSON data
),
// If HTTP authentication is required, use the below lines.
CURLOPT_HTTPAUTH => CURLAUTH_BASIC,
CURLOPT_USERPWD => $username. ':' . $password
));
// $mixResponse contains your server response.
I use variableToString. It handles every PHP type and is flexible (you can extend it if you want).
You should look at the article C++ Programming/Type Casting.
It contains a good description of all of the different cast types. The following taken from the above link:
const_cast
const_cast(expression) The const_cast<>() is used to add/remove const(ness) (or volatile-ness) of a variable.
static_cast
static_cast(expression) The static_cast<>() is used to cast between the integer types. 'e.g.' char->long, int->short etc.
Static cast is also used to cast pointers to related types, for example casting void* to the appropriate type.
dynamic_cast
Dynamic cast is used to convert pointers and references at run-time, generally for the purpose of casting a pointer or reference up or down an inheritance chain (inheritance hierarchy).
dynamic_cast(expression)
The target type must be a pointer or reference type, and the expression must evaluate to a pointer or reference. Dynamic cast works only when the type of object to which the expression refers is compatible with the target type and the base class has at least one virtual member function. If not, and the type of expression being cast is a pointer, NULL is returned, if a dynamic cast on a reference fails, a bad_cast exception is thrown. When it doesn't fail, dynamic cast returns a pointer or reference of the target type to the object to which expression referred.
reinterpret_cast
Reinterpret cast simply casts one type bitwise to another. Any pointer or integral type can be casted to any other with reinterpret cast, easily allowing for misuse. For instance, with reinterpret cast one might, unsafely, cast an integer pointer to a string pointer.
MySQL prior to version 5 did not allow aggregate functions in ORDER BY clauses.
You can get around this limit with the deprecated syntax:
SELECT COUNT(id), `Tag` from `images-tags`
GROUP BY `Tag`
ORDER BY 1 DESC
LIMIT 20
1, since it's the first column you want to group on.
Here's the accepted answer implementation ported to Java in case anyone needs it.
package com.project529.garage.util;
/**
* Mean radius.
*/
private static double EARTH_RADIUS = 6371;
/**
* Returns the distance between two sets of latitudes and longitudes in meters.
* <p/>
* Based from the following JavaScript SO answer:
* http://stackoverflow.com/questions/27928/calculate-distance-between-two-latitude-longitude-points-haversine-formula,
* which is based on https://en.wikipedia.org/wiki/Haversine_formula (error rate: ~0.55%).
*/
public double getDistanceBetween(double lat1, double lon1, double lat2, double lon2) {
double dLat = toRadians(lat2 - lat1);
double dLon = toRadians(lon2 - lon1);
double a = Math.sin(dLat / 2) * Math.sin(dLat / 2) +
Math.cos(toRadians(lat1)) * Math.cos(toRadians(lat2)) *
Math.sin(dLon / 2) * Math.sin(dLon / 2);
double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
double d = EARTH_RADIUS * c;
return d;
}
public double toRadians(double degrees) {
return degrees * (Math.PI / 180);
}
It surprises me that no one mentioned the key difference between these two is that the temp table supports parallel insert while the table variable doesn't. You should be able to see the difference from the execution plan. And here is the video from SQL Workshops on Channel 9.
This also explains why you should use a table variable for smaller tables, otherwise use a temp table, as SQLMenace answered before.
This will get you a string array of all the resources:
System.Reflection.Assembly.GetExecutingAssembly().GetManifestResourceNames();
A single regex to parse and breakup a full URL including query parameters and anchors e.g.
https://www.google.com/dir/1/2/search.html?arg=0-a&arg1=1-b&arg3-c#hash
^((http[s]?|ftp):\/)?\/?([^:\/\s]+)((\/\w+)*\/)([\w\-\.]+[^#?\s]+)(.*)?(#[\w\-]+)?$
RexEx positions:
url: RegExp['$&'],
protocol:RegExp.$2,
host:RegExp.$3,
path:RegExp.$4,
file:RegExp.$6,
query:RegExp.$7,
hash:RegExp.$8
you could then further parse the host ('.' delimited) quite easily.
What I would do is use something like this:
/*
^(.*:)//([A-Za-z0-9\-\.]+)(:[0-9]+)?(.*)$
*/
proto $1
host $2
port $3
the-rest $4
the further parse 'the rest' to be as specific as possible. Doing it in one regex is, well, a bit crazy.
I followed around five different answers as well as all the blog posts in the previous answers and still had problems. I was trying to add a listener to some existing code that was tracing using the TraceSource.TraceEvent(TraceEventType, Int32, String)
method where the TraceSource
object was initialised with a string making it a 'named source'.
For me the issue was not creating a valid combination of source and switch elements to target this source. Here is an example that will log to a file called tracelog.txt
. For the following code:
TraceSource source = new TraceSource("sourceName");
source.TraceEvent(TraceEventType.Verbose, 1, "Trace message");
I successfully managed to log with the following diagnostics configuration:
<system.diagnostics>
<sources>
<source name="sourceName" switchName="switchName">
<listeners>
<add
name="textWriterTraceListener"
type="System.Diagnostics.TextWriterTraceListener"
initializeData="tracelog.txt" />
</listeners>
</source>
</sources>
<switches>
<add name="switchName" value="Verbose" />
</switches>
</system.diagnostics>
There are a couple of ways to do your check for class equality before checking member equality, and I think both are useful in the right circumstances.
instanceof
operator.this.getClass().equals(that.getClass())
.I use #1 in a final
equals implementation, or when implementing an interface that prescribes an algorithm for equals (like the java.util
collection interfaces—the right way to check with with (obj instanceof Set)
or whatever interface you're implementing). It's generally a bad choice when equals can be overridden because that breaks the symmetry property.
Option #2 allows the class to be safely extended without overriding equals or breaking symmetry.
If your class is also Comparable
, the equals
and compareTo
methods should be consistent too. Here's a template for the equals method in a Comparable
class:
final class MyClass implements Comparable<MyClass>
{
…
@Override
public boolean equals(Object obj)
{
/* If compareTo and equals aren't final, we should check with getClass instead. */
if (!(obj instanceof MyClass))
return false;
return compareTo((MyClass) obj) == 0;
}
}
Reading through this, I'm amazed I didn't see this. I have found multiple algorithms that would work for this.
If the value of an object was never defined, this will prevent from returning true
if it is defined as null
or undefined
. This is helpful if you want true to be returned for values set as undefined
if(obj.prop === void 0) console.log("The value has never been defined");
If you want it to result as true
for values defined with the value of undefined
, or never defined, you can simply use === undefined
if(obj.prop === undefined) console.log("The value is defined as undefined, or never defined");
Commonly, people have asked me for an algorithm to figure out if a value is either falsy, undefined
, or null
. The following works.
if(obj.prop == false || obj.prop === null || obj.prop === undefined) {
console.log("The value is falsy, null, or undefined");
}
string myMessage="helloworld";
int len;
int slength = (int)myMessage.length() + 1;
len = MultiByteToWideChar(CP_ACP, 0, myMessage.c_str(), slength, 0, 0);
wchar_t* buf = new wchar_t[len];
MultiByteToWideChar(CP_ACP, 0, myMessage.c_str(), slength, buf, len);
std::wstring r(buf);
std::wstring stemp = r.C_str();
LPCWSTR result = stemp.c_str();
EDIT: You cannot overload operators in current, common browser-based implementations of JavaScript interpreters.
To answer the original question, one way you could do this, and mind you, this is a bit of a hack, simply serialize the two arrays to JSON and then compare the two JSON strings. That would simply tell you if the arrays are different, obviously you could do this to each of the objects within the arrays as well to see which ones were different.
Another option is to use a library which has some nice facilities for comparing objects - I use and recommend MochiKit.
EDIT: The answer kamens gave deserves consideration as well, since a single function to compare two given objects would be much smaller than any library to do what I suggest (although my suggestion would certainly work well enough).
Here is a naïve implemenation that may do just enough for you - be aware that there are potential problems with this implementation:
function objectsAreSame(x, y) {
var objectsAreSame = true;
for(var propertyName in x) {
if(x[propertyName] !== y[propertyName]) {
objectsAreSame = false;
break;
}
}
return objectsAreSame;
}
The assumption is that both objects have the same exact list of properties.
Oh, and it is probably obvious that, for better or worse, I belong to the only-one-return-point camp. :)
I had similar problem except that it happened without installing any plugin. I begin to get this dialog about source control every time I open the project + tons of windows popping up and floating which I had to close one by one.
Windows -> Rest Windows Layout, fixed it for me without any problems. It does bring the default setting which I don't mind at all :)
You could use some LINQ to get the list:
var types = from type in this.GetType().Assembly.GetTypes()
where type is ISomeInterface
select type;
But really, is that more readable?
One of the major advantages of MVC which has not mentioned here is that MVC provides RESTful urls which enables SEO. When you name your Controllers and Actions wisely, it makes it easier for search engines to find your site if they only take a look at your site Urls. For example you have a car sale website and a page which displays available Lamborghini Veneno cars, instead of having www.MyCarSale.com/product/6548 referring to the page you can choose www.MyCarSale.com/SportCar/Lamborghini-Veneno url for SEO purpose.
Here is a good answer to MVC Advantages and here is an article How to create a SEO friendly Url.
You need to analyze the JSON calls using Wireshark, so you will see if you include the charset in the formation of the JSON page or not, for example:
0000 48 54 54 50 2f 31 2e 31 20 32 30 30 20 4f 4b 0d HTTP/1.1 200 OK. 0010 0a 43 6f 6e 74 65 6e 74 2d 54 79 70 65 3a 20 74 .Content -Type: t 0020 65 78 74 2f 68 74 6d 6c 0d 0a 43 61 63 68 65 2d ext/html ..Cache- 0030 43 6f 6e 74 72 6f 6c 3a 20 6e 6f 2d 63 61 63 68 Control: no-cach
0000 48 54 54 50 2f 31 2e 31 20 32 30 30 20 4f 4b 0d HTTP/1.1 200 OK. 0010 0a 43 61 63 68 65 2d 43 6f 6e 74 72 6f 6c 3a 20 .Cache-C ontrol: 0020 6e 6f 2d 63 61 63 68 65 0d 0a 43 6f 6e 74 65 6e no-cache ..Conten 0030 74 2d 54 79 70 65 3a 20 74 65 78 74 2f 68 74 6d t-Type: text/htm 0040 6c 3b 20 63 68 61 72 73 65 74 3d 49 53 4f 2d 38 l; chars et=ISO-8 0050 38 35 39 2d 31 0d 0a 43 6f 6e 6e 65 63 74 69 6f 859-1..C onnectio
Why is that? because we can not put on the page of JSON a goal like this:
In my case I use the manufacturer Connect Me 9210 Digi:
It worked for me without having to convert the data passed by JSON for UTF-8 and then redo the conversion on the page ...
Another useful tip is to use %*
to mean "all". For example:
echo off
set arg1=%1
set arg2=%2
shift
shift
fake-command /u %arg1% /p %arg2% %*
When you run:
test-command admin password foo bar
the above batch file will run:
fake-command /u admin /p password admin password foo bar
I may have the syntax slightly wrong, but this is the general idea.
I wrote the following code that works fine. But I think it only works with .wav
format.
public static synchronized void playSound(final String url) {
new Thread(new Runnable() {
// The wrapper thread is unnecessary, unless it blocks on the
// Clip finishing; see comments.
public void run() {
try {
Clip clip = AudioSystem.getClip();
AudioInputStream inputStream = AudioSystem.getAudioInputStream(
Main.class.getResourceAsStream("/path/to/sounds/" + url));
clip.open(inputStream);
clip.start();
} catch (Exception e) {
System.err.println(e.getMessage());
}
}
}).start();
}
If your list is very big and you are filtering repeatedly - you can sort the original list on the filter attribute, binary search to find the start and end points.
Initial time O(n*log(n)) then O(log(n)).
Standard filtering will take O(n) each time.
Here I am trying to help you do the job step by step: (this may be the answer to other questions)
that is pretty much it. now you can use SQLite in your project. to use it in your project on the code level you may use this below example code:
make a connection string:
string connectionString = @"URI=file:{the location of your sqlite database}";
establish a sqlite connection:
SQLiteConnection theConnection = new SQLiteConnection(connectionString );
open the connection:
theConnection.Open();
create a sqlite command:
SQLiteCommand cmd = new SQLiteCommand(theConnection);
Make a command text, or better said your SQLite statement:
cmd.CommandText = "INSERT INTO table_name(col1, col2) VALUES(val1, val2)";
Execute the command
cmd.ExecuteNonQuery();
that is it.
How to measure similarity between two images entirely depends on what you would like to measure, for example: contrast, brightness, modality, noise... and then choose the best suitable similarity measure there is for you. You can choose from MAD (mean absolute difference), MSD (mean squared difference) which are good for measuring brightness...there is also available CR (correlation coefficient) which is good in representing correlation between two images. You could also choose from histogram based similarity measures like SDH (standard deviation of difference image histogram) or multimodality similarity measures like MI (mutual information) or NMI (normalized mutual information).
Because this similarity measures cost much in time, it is advised to scale images down before applying these measures on them.
Instead of VALUES
part of INSERT
query, just use SELECT
query as below.
INSERT INTO table1 ( column1 , 2, 3... )
SELECT col1, 2, 3... FROM table2
Kara is about programming a bug(!) coming up in various versions, e.g. Finite State Machine, Java, Turing Machine, Multithreading
Kara http://www.swisseduc.ch/compscience/karatojava/kara/icons/kara-worldeditor.gif
an SQL that shows SQL commands, need to run to duplicate a database from one database to another. for each table there is create a table statement and an insert statement. it assumes both databases are on the same server:
select @fromdb:="crm";
select @todb:="crmen";
SET group_concat_max_len=100000000;
SELECT GROUP_CONCAT( concat("CREATE TABLE `",@todb,"`.`",table_name,"` LIKE `",@fromdb,"`.`",table_name,"`;\n",
"INSERT INTO `",@todb,"`.`",table_name,"` SELECT * FROM `",@fromdb,"`.`",table_name,"`;")
SEPARATOR '\n\n')
as sqlstatement
FROM information_schema.tables where table_schema=@fromdb and TABLE_TYPE='BASE TABLE';
The problems with the existing answers:
rm
directly on an unquoted command substitution (rm `...`
), there's an added risk of unintended globbing.rm
to directories will fail).wnoise's answer addresses these issues, but the solution is GNU-specific (and quite complex).
Here's a pragmatic, POSIX-compliant solution that comes with only one caveat: it cannot handle filenames with embedded newlines - but I don't consider that a real-world concern for most people.
For the record, here's the explanation for why it's generally not a good idea to parse ls
output: http://mywiki.wooledge.org/ParsingLs
ls -tp | grep -v '/$' | tail -n +6 | xargs -I {} rm -- {}
Note: This command operates in the current directory; to target a directory explicitly, use a subshell ((...)
):
(cd /path/to && ls -tp | grep -v '/$' | tail -n +6 | xargs -I {} rm -- {})
The same applies analogously to the commands below.
The above is inefficient, because xargs
has to invoke rm
once for each filename.
Your platform's xargs
may allow you to solve this problem:
If you have GNU xargs
, use -d '\n'
, which makes xargs
consider each input line a separate argument, yet passes as many arguments as will fit on a command line at once:
ls -tp | grep -v '/$' | tail -n +6 | xargs -d '\n' -r rm --
-r
(--no-run-if-empty
) ensures that rm
is not invoked if there's no input.
If you have BSD xargs
(including on macOS), you can use -0
to handle NUL
-separated input, after first translating newlines to NUL
(0x0
) chars., which also passes (typically) all filenames at once (will also work with GNU xargs
):
ls -tp | grep -v '/$' | tail -n +6 | tr '\n' '\0' | xargs -0 rm --
Explanation:
ls -tp
prints the names of filesystem items sorted by how recently they were modified , in descending order (most recently modified items first) (-t
), with directories printed with a trailing /
to mark them as such (-p
).
ls -tp
always outputs file / directory names only, not full paths, that necessitates the subshell approach mentioned above for targeting a directory other than the current one ((cd /path/to && ls -tp ...)
).grep -v '/$'
then weeds out directories from the resulting listing, by omitting (-v
) lines that have a trailing /
(/$
).
tail -n +6
skips the first 5 entries in the listing, in effect returning all but the 5 most recently modified files, if any.
Note that in order to exclude N
files, N+1
must be passed to tail -n +
.
xargs -I {} rm -- {}
(and its variations) then invokes on rm
on all these files; if there are no matches at all, xargs
won't do anything.
xargs -I {} rm -- {}
defines placeholder {}
that represents each input line as a whole, so rm
is then invoked once for each input line, but with filenames with embedded spaces handled correctly.--
in all cases ensures that any filenames that happen to start with -
aren't mistaken for options by rm
.A variation on the original problem, in case the matching files need to be processed individually or collected in a shell array:
# One by one, in a shell loop (POSIX-compliant):
ls -tp | grep -v '/$' | tail -n +6 | while IFS= read -r f; do echo "$f"; done
# One by one, but using a Bash process substitution (<(...),
# so that the variables inside the `while` loop remain in scope:
while IFS= read -r f; do echo "$f"; done < <(ls -tp | grep -v '/$' | tail -n +6)
# Collecting the matches in a Bash *array*:
IFS=$'\n' read -d '' -ra files < <(ls -tp | grep -v '/$' | tail -n +6)
printf '%s\n' "${files[@]}" # print array elements
I personally use Visual Leak Detector, though it can cause large delays when large blocks are leaked (it displays the contents of the entire leaked block).
Additionally there is PDFTextStream which is a commercial Java library that can also be used from Python.
Add OSHI dependency via maven:
<dependency>
<groupId>com.github.dblock</groupId>
<artifactId>oshi-core</artifactId>
<version>2.2</version>
</dependency>
Get a battery capacity left in percentage:
SystemInfo si = new SystemInfo();
HardwareAbstractionLayer hal = si.getHardware();
for (PowerSource pSource : hal.getPowerSources()) {
System.out.println(String.format("%n %s @ %.1f%%", pSource.getName(), pSource.getRemainingCapacity() * 100d));
}
If you need the port number also, you can use
Request.Url.Authority
Example:
string url = Request.Url.Authority + HttpContext.Current.Request.RawUrl.ToString();
if (Request.ServerVariables["HTTPS"] == "on")
{
url = "https://" + url;
}
else
{
url = "http://" + url;
}
The crux of the matter is that the word reference in the expression "pass by reference" means something completely different from the usual meaning of the word reference in Java.
Usually in Java reference means a a reference to an object. But the technical terms pass by reference/value from programming language theory is talking about a reference to the memory cell holding the variable, which is something completely different.
Beside all the other important aspects already mentioned here, Collections API (e.g. Map interface) is being modified all the time to conform to the "latest and greatest" additions to Java spec.
For example, compare Java 5 Map iterating:
for (Elem elem : map.keys()) {
elem.doSth();
}
versus the old Hashtable approach:
for (Enumeration en = htable.keys(); en.hasMoreElements(); ) {
Elem elem = (Elem) en.nextElement();
elem.doSth();
}
In Java 1.8 we are also promised to be able to construct and access HashMaps like in good old scripting languages:
Map<String,Integer> map = { "orange" : 12, "apples" : 15 };
map["apples"];
Update: No, they won't land in 1.8... :(
Are Project Coin's collection enhancements going to be in JDK8?
In management studio:
Properties
, then Options
.Tasks
-> Shrink
-> Files
Alternatively, the SQL to do it:
ALTER DATABASE mydatabase SET RECOVERY SIMPLE
DBCC SHRINKFILE (mydatabase_Log, 1)
a simpler way search downloads in the start menu and click on downloads in the search results to see where it will take you the drive will be highlighted in the explorer.
Try running
lsof | grep /mnt/data
That should list any process that is accessing /mnt/data that would prevent it from being unmounted.
There's a relatively new service called HockeyApp, which seems to rival TestFlight, however they claim to give you access to unlimited users, but it does cost some $$ unlike TestFlight which has now been integrated directly into iTunes Connect.
I use following approach to finding memory leaks in Java. I've used jProfiler with great success, but I believe that any specialized tool with graphing capabilities (diffs are easier to analyze in graphical form) will work.
Basically analysis should start from greatest positive diff by, say, object types and find what causes those extra objects to stick in memory.
For web applications that process requests in several threads analysis gets more complicated, but nevertheless general approach still applies.
I did quite a number of projects specifically aimed at reducing memory footprint of the applications and this general approach with some application specific tweaks and trick always worked well.